WO2006012540A2

WO2006012540A2 - Portable electric driven compressed air gun

Info

Publication number: WO2006012540A2
Application number: PCT/US2005/026104
Authority: WO
Inventors: Christopher S. Pedicini; John D. Witzigreuter
Original assignee: Tricord Solutions, Inc.
Priority date: 2004-07-22
Filing date: 2005-07-22
Publication date: 2006-02-02
Also published as: WO2006012540A3

Abstract

A portable electric motor driven air gun powered by a power source. The motor is coupled to a lead screw or a rack and pinion which drives a piston. The piston compresses air in a chamber producing high-pressure air. When sufficient energy is stored within the air stream by the piston a valve opens which releases the air to act on the projectile. The compressed air is used to push a projectile such as a paintball, an airsoft ball, a 'bb', or a pellet through a barrel. In one embodiment, the lead screw is then reversed and the piston is reset for the next shot. In another embodiment, the pinion rotates until it comes to an interrupted thread surface, at which point the rack and pinion are returned to the starting position via a spring. The piston may be coupled to a bolt thru a lost motion device to facilitate positioning of the projectile for firing. The direction speed and operative modes of the gun are preferably controlled with an electric circuit. The power source is preferably rechargeable and allows the air gun to be operated completely independent from either a wall outlet or a compressed air supply.

Description

PORTABLE ELECTRIC DRIVEN COMPRESSED AIR GUN

TECHNICAL FIELD

[0001] This invention relates to pneumatic guns, air rifles, pellet rifles, paintball guns and the like. Such pneumatic guns are typically driven by either hand cocked springs, compressed gas, or hand operated pumps. The disadvantages of these guns are outlined in more detail below.

BACKGROUND ART

[0002] Air rifles have been around for many years and have seen numerous evolutionary changes over the years. The most common methods for propelling the projectile use the energy from compressed gas or from a spring. There are four major techniques shown in the prior art for launching the projectile with many variations based upon such teachings. These techniques include: (i) the use of stored compressed gas in the form of carbon dioxide cylinders or other high pressure storage tanks; (ii) using a powerful spring to push a piston which compresses air which then pushes the projectile; (iii) using a hand pump to pressurize the air for subsequent release; and (iv) using a direct acting means such as a solenoid plunger or centrifugal force to push the projectile out of the barrel. All of these methods have distinct disadvantages when compared to the present invention.

[0003] The first technique requires a source of compressed air, such as a tank or canister. Filling, transporting and using such a canister represents a significant inconvenience and burden for the user. Often, additional equipment such as regulators, evaporation chambers, multistage regulators and complicated timing circuits are required to reduce and control the very high pressure in the cylinder to a level suitable for launching the projectile. This further increases the cost and complexity of such an air gun. Additionally, in the case of carbon dioxide driven air or paintball guns, there is a large variation in the velocity of the projectile with varying ambient temperatures. Furthermore, these tanks store an incredible amount of energy which, if released suddenly through a tank fault, could represent a significant safety factor. Disposable cartridges, which can be used in less costly air guns, significantly increase refuse issues. Additional teachings such as those contained in US Patent Nos. 6,516,791, 6,474,326, 5,727,538 and 6,532,949 teach of various ways of porting and controlling high pressure air supplies to improve the reliability of air guns (specifically paintball guns and the like) by differentiating between the airstream which is delivered to the bolt which facilitates chambering the projectile and the airstream which pushes the projectile out of the barrel. All of these patents still suffer from the major inconvenience and potential safety hazard of storing a large volume of highly compressed gas within the air gun. Additionally, as they combine electronic control with the propulsion method of stored compressed gas, the inherent complexity of the mechanism increases, thus, increasing cost and reliability issues. Further, US Patent No 6,142,137 teaches about using electrical means to assist in the trigger control of a compressed air gun such as a paintball gun. In this patent, an electromotive device is used in conjunction with electronics to define various modes of fire control such as single shot, burst or automatic modes. While this addresses the ability of multiple modes of fire, it does not solve the fundamental propulsion problem associated with gas cylinders and, in addition, it is expensive and complicated.

[0004] The second technique is actually quite simple and has been used for quite a few years in many different types of pellet, "bb" or air rifles. The basic principle is to store energy in a spring which is later released to rapidly compress air. This air then pushes the projectile out of the barrel at high velocity. Problems with this method include the need to "cock" the spring between shots. Thus, it is only suitable for single shot devices and is limited to very slow rates of fire. Furthermore, the spring results in a double recoil effect when it is released. The first recoil is due to the unwinding of the spring and the second recoil is due to the spring slamming the piston into the end of the cylinder (i.e. forward recoil). Additionally, the spring air rifles require a significant amount of maintenance and, if dry-fired, the mechanism can be damaged. Finally, the effort required for such "cocking" is often substantial and can be difficult for many individuals. References to these style air guns can be found in US Patent Nos. 3,128,753, 3,212,490, 3,523,538, and 1,830,763. Additional variations on the above technique have been attempted through the years including using an electric motor to cock the spring that drives a piston. This variation is detailed in US Patent Nos. 4,899,717 and 5,129,383. While this innovation solves the problem of cocking effort, the resulting air rifle still suffers from a complicated mechanism, double recoil and maintenance issues associated with the spring piston system. Another mechanism which uses a motor to wind a spring is shown in US Patent No. 5,261,384. Again, the use of indirect means to store the electrical energy in a spring before release to the piston to push the projectile results in an inefficient and complicated assembly. Furthermore, the springs in such systems are highly stressed mechanical elements that are prone to breakage and which increase the weight of the air gun. A similar reference can be seen in US Patent No. 1,447,458 which shows a spring winding and then delivery to a piston to compress air and propel a projectile. In this case, the device is for non-portable operation.

[0005] The third technique, using a hand pump to pressurize the air, is often used on low end devices and suffers from the need to pump the air gun between 2 to 10 times to build up enough air supply for sufficient projectile velocity. This again limits the air rifle or paintball gun to slow rates of fire. Additionally, because of the delay between when the air is compressed and when the compressed air is released to the projectile, variations in the energy are quite common for a standard number of pumps. Further taught in US Patent No. 2,568,432 and 2,834,332 is a method to use a solenoid to directly move a piston which compresses air and forces the projectile out of the air rifle. While this solves the obvious problem of manually pumping a chamber up in order to fire a gun, these devices suffer from the inability to store sufficient energy in the air stream. Solenoids are inefficient devices and can only convert very limited amounts of energy due to their operation. Furthermore, since the air stream is coupled directly to the projectile in this technique, the projectile begins to move as the air is being compressed. This limits the ability of the solenoid to store energy in the air stream to a very short time period and further relegates its use to low energy air rifles. In order to improve the design, the piston must actuate in an extremely fast time frame in order to prevent significant projectile movement during the compression stroke. This results in a very energetic piston mass similar to that shown in spring piston designs and further results in the undesirable double recoil effect as the piston mass must come to a halt. Additionally, this technique suffers from dry-fire in that the air is compressed between the piston and the projectile. A missing projectile allows the air to communicate to the atmosphere through the barrel and can damage the mechanism in a dry-fire scenario. Another variant of this approach is disclosed in US Patent No. 1,375,653, which uses an internal combustion engine instead of a solenoid to act against the piston. Although this solves the issue of sufficient power, it is no longer considered an air rifle as it becomes a combustion driven gun. Moreover, it suffers from the aforementioned disadvantages including complexity and difficulty in controlling the firing sequence. Further taught in US Patent No. 4,137,893 is the use of an air compressor coupled to a storage tank which is then coupled to the air gun. Although this solves the issue of double recoil, it is not suitable to a portable system due to inefficiencies of compressing air and the large tank volume required. When air is used in this fashion, it compresses via adiabatic means, but the heat of compression is dissipated due to the large volume of air and the subsequent storage in a tank. In order to overcome the variation in air pressure, further expense and complexity in terms of valving and regulators must be added. A variation of the above is to use a direct air compressor as shown in US Patent No. 1,743,576. Again, due to the large volume of air between the compression means and the projectile, much of the heat of compression is lost leading to a very inefficient operation. Additionally, this patent teaches of a continuously operating device which suffers from a significant lock time (time between trigger pull and projectile leaving the barrel) as well as the inability to run in a semiautomatic or single shot mode. Further disadvantages of this device include the pulsating characteristics of the air stream which are caused by the release and reseating of the check valve during normal operation.

[0006] The fourth technique is to use direct mechanical action on the projectile itself.

The teachings in US Patent Nos. 1,343,127 and 2,550,887 represent such mechanisms. Limitations of this approach include difficulty in achieving high projectile velocity since the transfer of energy must be done extremely rapidly between the impacting hammer and the projectile. Additionally, this method suffers from the need to absorb a significant impact as the solenoid plunger must stop and return for the next projectile. This can cause a double-recoil firing characteristic. Since the solenoid plunger represents a significant fraction of the moving mass (i.e. it often exceeds the projectile weight) this type of system is very inefficient and limited to low velocity, low energy air guns as may be found in toys and the like. Variations of this method include those disclosed in US Patent No. 4,694,815 in which a hammer driven by a spring contacts the projectile. The spring is "cocked" via an electric motor, but again, this does not overcome the prior mentioned limitations.

[0007] All of the currently available devices suffer from a number of disadvantages, some of which include: difficult operation - cocking or pumping air rifles can be time consuming and a physical chore; inability to rapidly move between single fire, semiautomatic, burst or automatic modes; inability to support rapid-fire operation required by the above; significant inconvenience in the refilling transport and use of high-pressure gas cylinders; Non- portability - traditional air rifles at carnivals and the like are tethered to a compressed air supply or due to inefficient compressor operation require a large power source such as a wall outlet; double recoil effects; complicated mechanisms and air porting schemes leading to potentially expensive production costs and reliability issues; inefficient usage and/or coupling of the compressed air to the projectile resulting in low energy projectiles and large energy input requirements. DISCLOSURE OF THE EVVENTION

[0008] In accordance with the present invention, a piston is driven by a lead screw, a rack and pinion mechanism, or other linear motion converter, to compress air within a cylinder. When the desired pressure or stroke is reached a valve is opened, or is allowed to open, releasing the high-pressure air toward a projectile and launching the projectile. In the first embodiment, an electric motor, which derives its power from a low impedance electrical source, such as rechargeable batteries, is coupled, either directly or through, a reduction means to the lead screw creating a very simple and robust design. Additionally, the piston may be mechanically coupled to a bolt in order to force the bolt to move in turn with the movement of the piston. In another embodiment, the electric motor is coupled to the rack via a pinion, and the coupling mechanism includes provisions to decouple the motor from the rack at a point in the cycle. The piston and rack assembly is coupled to a bolt in order to force the bolt to move in cooperation with the movement of the piston. This coupling includes springs and sliding members to reduce the travel of the bolt to a fractional percentage of the overall piston movement. This increases the overall safety and reduces the wear of the mechanism.

[0009] Accordingly, besides the objects and advantages of the portable electric air gun as described, several objects and advantages of the present invention are: 1) To provide an electric motor driven gun in which the operating element has an added degree of safety in that the energy is on demand and not stored in high pressure cylinders; 2) to provide a means in which the operation is portable eliminating any tethering of hoses or cords; 3) to provide a means in which the operation uses relatively low pressure air thus reducing the sound profile and allowing for stealth operation; 4) to provide a means in which the control of the projectile is enabled by electronic means thus increasing the safety profile and speed control; 5) to provide an electric motor driven gun in which the source of energy is a rechargeable power supply thus eliminating the use of disposable or refillable gas pressure cylinders and decreasing overall operational cost; 6) to provide an electric motor driven gun which is mechanically simpler to construct and simpler to operate; 7) to provide a means for reducing the lock time in a fire on demand electric motor driven air gun; 8) to provide a means in which the feed mechanism for the projectiles is controlled by the electric motor thus allowing for a simple design which does not rob energy from the air stream; 9) to provide a means in which the compression is more efficiently utilized by reducing the delay between compression and firing, thus, accessing a large part of the heat energy of compression; 10) to provide a design which uses direct air compression and eliminates the spring piston and its associated double recoil; and 1 1) to provide a design in which the energy to return the piston is at least partially recovered to enhance the projectile speed or cycle rate. Further objects and advantages will become more apparent from a consideration of the ensuing detailed description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference numbers for the drawings are shown below.

[00010] Figure 1 is a side assembly view of the electric powered air gun in the forward or firing position in a first embodiment;

[00011] Figure 2 is a side assembly view of the electric powered air gun in the retracted position in a first embodiment;

[00012] Figure 3 is a view of the electric powered air gun using pre-compression in a first embodiment;

[00013] Figure 4A is a side assembly view of an electric release valve in closed position in a first embodiment;

[00014] Figure 4B is a side assembly view of an electric release valve in open position in a first embodiment;

[00015] Figure 5 is a side assembly view of the electric powered air gun with energy storage partway thru the cycle in a first embodiment;

[00016] Figure 6 is a side assembly view of the electric powered air gun with a projectile feeding mechanism timed to the compression mechanism in a first embodiment;

[00017] Figure 7 is a side assembly view of an electric air gun with a spring return mechanism for the piston in a first embodiment;

[00018] Figure 8 is a schematic of a control circuit in a first embodiment;

[00019] Figure 9 is a side assembly view of the electric powered air gun in the forward or firing position in a second embodiment;

[00020] Figure 10 is a side assembly view of the electric powered air gun in the retracted position in a second embodiment;

[00021] Figure 11 is a side assembly view of the rack and pinion piston drive assembly in a second embodiment; [00022] Figure 12 is a side assembly view of the rack and pinion piston drive assembly used in combination with an elastic storage element and retaining mechanism in a second embodiment; and

[00023] Figure 13 is a schematic of a control circuit in a second embodiment.

Reference numbers in Drawings:

1 Motor

2 Power Source

3 Control Circuit

4 Lead Screw

4a Rack

5 Piston

6 Bolt

7 Valve

8 Barrel

9 Projectile

10 Start Switch

11 Magnet

12 Sensor Switch

13 Compressed Air Passageway

14 Cylinder

15 Bolt Link

16 Projectile Inlet Port

17 Bumper

18 Solenoid

19 Solenoid Detent

20 Bolt Return Spring Forward Air Chamber

Projectile Feeder

Lost motion coupling

Rear Air Chamber

Pinion Gear

Spur Gear

Plunger

Bias Spring

Piston Spring Return

Electric Release Clutch

Projectile Carousel

Communication Link

Grip

Support Bearing

Inertia Balancing Wheel

Projectile Feeder Motor

Check Valve

Relief Valve

Ball Hopper a Actuation Limit Spring a Pinion Gear a Drive Train a Plunger a Bias Spring a Piston Return Spring a Elastic storage element 37a Retaining mechanism

38a Communication Link

39a Grip

40a Support Bearing

41a Rack Pinion

42a Trigger

43a Check Valve

44a Relief Valve

45a Rack and pinion assembly

46a Gear teeth

47a Section without gear teeth

BEST MODE FOR CARRYING OUT THE INVENTION

[00024] Although the following relates to the preferred embodiments of the design, it will be understood by those familiar with the art that changes to materials, part descriptions and activation methods can be made without departing from the spirit of the invention. Additional embodiments will be described which have particular advantages depending on the design requirements or the particular electric air gun

[00025] Referring to Figure 1 , in a first embodiment, the user presses a start switch (10), which may be referred to as a trigger. This causes power to be directed from the power source (2), such as a battery, to the motor (1) by the control circuit (3). The preferred control circuit is described later in further detail but can be as simple as any means for connecting and disconnecting power to the motor (1) to allow an air compression and projectile fire cycle. The motor (1) begins to turn causing energy to be transferred into and through the rotating elements in the system. The preferred system includes motor rotor, a gear set, a lead screw (4) and possibly an inertia balancing wheel (41). The purpose of the inertia balancing wheel (41) is to level out the load cycle by increasing the inertial energy available to compress the air as the piston (5) approaches the end of the compression cycle. In the preferred embodiment, the piston (5) begins the cycle in the forward (or firing) position. The lead screw (4) is coupled to the motor (1), preferentially through a gear reduction system comprising a pinion gear (31) and a spur gear (32). Other coupling means including but not limited to pulleys, gear belts, planetary systems could be used without departing from the spirit of the invention. In the preferred embodiment, the piston (5) begins to move rearward in cooperation with the lead screw (4) compressing the air in the rear air chamber (30). The purpose of this compression is to take advantage of the rearward stroke of the piston (5) for the purpose of storing energy for firing the projectile (9). The rear air chamber (30) accomplishes this by storing the piston return energy in the form of an air spring. The rear air chamber (30) expands against the backside of the piston (5) on the forward stroke thus recovering a large portion of the energy used in the rearward stroke of the piston (5). This energy works in cooperation with the motor (1) to increase the energy available for compressing the air in the forward air chamber (21). Although the preferred embodiment is shown as an air spring, alternative means such as mechanical springs (compression, power, torsion etc) could also be used to store energy during the rearward stroke of the piston (5). The net effect of this improvement is increased cycle rate and increased power of the electric air gun.

[00026] Although the preferred embodiment shows the initial position of the piston (5) at the forward part of the stroke, it is possible to retain the energy of the rearward stroke and store the electric air gun in the rearward position. This is shown in figure 5. One advantage of this approach is it reduces the lock time on the first shot. For this particular technique the initial position of the piston (5) would be at the rear of the cylinder (14) with a cycle consisting of the power or fire stroke followed by a return in which the return energy was stored in a spring. This alternative reduces the lock time on the first shot since the traverse distance between trigger pull and the firing point of the linear compressor is only the forward stroke of the piston (5). The advantage in reduced lock time is the operator is most likely to notice delays on the first shot of a sequence but less likely to notice on subsequent shots. The means for retaining the piston (5) in such position could be electrical such as a solenoid detent (19), spring ball detent, or mechanical coupling of the start switch (10). In both of these embodiments, the motor (1) and stored energy cooperate in compressing the air in the forward air chamber (21) during the firing stroke.

[00027] Continuing our discussion of the cycle, as the lead screw (4) turns it moves a piston (5), which is coupled to the lead screw (4), down the cylinder (14) in the rear direction, storing energy in the air spring. During this rearward movement of the piston (5), air is replenished in the forward air chamber (21) either through a check valve (43) or by holding the firing valve (7) open or with another valve. Upon sufficient rearward travel, the control circuit (3) makes a decision to reverse the motor based on timing or input from a sensor switch (12). The sensor switch (12) could be a hall sensor for determining piston location, a pressure sensor in the rear compartment, a speed detection means or any combination of the above. Preferably the reversal of the motor (1) takes place at a slow motor speed when most of the rotational kinetic energy has been stored in the spring element. The switching of the motor (1) from forward to reverse could involve an intermediate braking period to reduce any extra energy in the motor (1) and reduce the load seen on the motor (1). As the motor moves the piston (5) forward, the energy stored on the "rearward" cycle pushes against the backside of the piston (5). This energy cooperates with the motor energy and compresses the air in the forward air chamber (21) in such a way that the compression exponent exceeds the isothermal case of 1 and approaches the adiabatic case of 1.4. Compression exponents in this range are referred to as polytropic exponents and allow for a more efficient design. At the appropriate forward point the compressed air in the forward air chamber (21) is channeled to the projectile through the valve (7). In a good design, the time involved in the compression cycle is sufficiently short so as to yield a compression exponent of at least 1.10 .

[00028] At the end of the compression stroke, the forward air chamber (21) contains high-pressure air that is released to the projectile through the valve (7). The opening of the valve can be by direct mechanical coupling and/or electrical techniques. The preferred means is to use an electronic solenoid (18) which is controlled in response to timing and/or a sensor such as air pressure, piston location or motor speed. Ideally, the point of valve release is when the motor (1) has slowed to such a point that most of the rotational kinetic energy has been converted to energy in the compressed air. At or near the end of the piston (5) stroke, as shown in Figures 4A and 4B, the valve (7) is caused to shift open. This rapidly releases the compressed air into the compressed air passageway (13) and then into the barrel (8) of the air gun. In order to be effective in an electric marker, it is essential that valve losses be held to a minimum. There are two key parameters that must be carefully controlled: first is to limit the losses in terms of pressure drop through the valve (7) and second is the ability of the valve (7) to open quickly. The valve (7) characteristics are extremely important to the efficiency of the electric air gun. The preferred valve (7) will have a Cv greater then 1 and an opening time of less then 20 milliseconds. Cv is a standard measurement used in the valve industry for sizing a valve, wherein Cv is defined as the flow coefficient. The opening time is defined as the time between the valve (7) initially cracking open to the point at which 80% of the valve flow characteristics are useable. Without a sufficiently high flow valve and a low actuation time, it is difficult to achieve efficient operational of an electric motor driven air gun. A preferred example of such a valve (7) is shown in the attached figure 4A. In this figure, the valve (7) position is maintained normally closed by the bias spring (34). At the actuation point, the solenoid (18) is powered which pulls the plunger (33) to the solenoid (18). The plunger (33) pulls the valve (7) in the downward direction as shown in figure 4B. Once the valve (7) pulls down far enough, air begins to pass through the valve passageway. This allows the air pressure to act on the face of the valve (7) causing it to quickly open up by forcing the bias spring (34) to compress rapidly. In this example, the bias spring (34) is set with a 2-lb preload and a 4-lb solid load. Since the air pressure is approximately 100 psi and the area of the valve (7) is approximately 0.1 square inches, this equates to a net force of 6-lbs which rapidly accelerates the light weight valve (7) causing it to fully open in less then 10 milliseconds. The rapid opening of the valve (7) coupled with the large passageways give an efficient coupling of the compressed air energy to the projectile (9). This effectively accelerates the projectile (9) to its desired speed with minimal loss of air energy. The Cv rating of this particular valve would be approximately 4, with the passage openings of about 0.4 inch diameter.

[00029] The projectile (9), which is located within the barrel (8), begins to accelerate under the force of the compressed air and is driven out of the barrel (8) at a high velocity. The preferred embodiment uses a sensor switch (12) to recognize when the piston (5) is in its approximate initial (and also final) position and ready for cycle initiation. The preferred sensor switch (12) is a hall switch used in conjunction with a magnet (11), which is attached to the piston (5). It is understood that any sensing means which allows positional information of the piston could be used for the sensor switch (12), including but not limited to: reed switches, optical sensors and mechanical limit switches. It is further preferred to have a sensor monitoring the rotation of the system. Such a sensor could be attached to the pinion (36) which would allow the control circuit (3) to determine the piston (5) location by counting revolutions and processing the information as it relates to the lead or linear inch per revolution of the lead screw (4). Additionally, by counting the pinion (36) rotations, the control circuit (3) could determine the velocity of the system. Such information could be used to alter the speed of the piston (5), release the valve (7) or determine the reversal points of the motor (1). After the air pressure has been released to the projectile, a full cycle has been completed in the preferred embodiement and the electric air gun is ready for initiation of another cycle. It should be noted while a lead screw (4) is described in this embodiment, substantially similar elements which convert rotational motion to linear motion (i.e. a linear motion converter) may be substituted. Such elements could include, but are not limited to, slider crank type mechanisms, rack and pinion systems or gear and belt driven systems.

[00030] Additionally, depending on the form factor or shape desired for the electric air gun, the piston (5) need not be round. An elliptical design or even polygonal- shape with filleted corners is possible. These alternate shapes allow different form factors for the electric air gun and prevent piston (5) rotation as a result of the applied lead screw (4) torque.

[00031] A bolt is used in many air gun designs to chamber the projectile. It can be either manually operated or automatically operated. For automatic operation, the present invention preferably uses a mechanical bolt link (15) to connect the bolt (6) to the piston (5). Thus the motor (1) can be used to control the movement of the bolt (6) which results in more efficient actuation. When the piston (5) is at the firing point (also the start point in the preferred embodiment), the bolt (6) is fully forward and the projectile (9) is seated and ready to be fired. As the piston (5) and bolt (6) retract, the bolt (6) opens the projectile inlet port (16), as shown in Figure 5, that allows the next projectile (9) to be moved from the projectile feeder (22) into the barrel (8). This projectile (9) waits to be chambered by the bolt (6) until the next firing cycle is started. Another method to drive the bolt (6) includes a separate lead screw driven off the spur gear (32). This lead screw would advance and retract the bolt in concert with the motion of the piston (5) but would allow elimination of the bolt link (15). Various lost motion methods could also be used to move the bolt. By using a lost motion link to drive the bolt, the link could move with the piston and only move the bolt at the ends of its stroke thereby reducing the travel of the bolt. Bolt linkages could be used in concert with a spring to bias the bolt in one direction to increase ball drop time.

[00032] Depending on the need to reduce the size of the electric motor driven compressed air gun, it is possible to use a portion of the rearward stroke to pre-compress and displace air to the front cylinder (14). This allows a reduction in the size of the unit and is illustrated in Figure 3. In this figure, a check valve (43) and relief valve (44) have been added to the electric motor driven air gun. The check valve (43) allows air to freely flow into the forward air chamber (21) of the cylinder (14) during the rearward stroke. The relief valve (44) channels the pre-compressed air from the rear air chamber (30) to the forward air chamber (21) after the relief pressure is exceeded. The typical relief pressure is about 2 atmospheres but can be set for any particular pressure between about 1.5 and 8 atmospheres. Once the pressure in the rear air chamber (30) reaches the relief point, the air in the rear chamber (30) flows through the relief valve (44) into the front air chamber. (21). This causes the check valve (43) to close and allows a higher volume of compressed air to be used in a limited space thus decreasing the size of the electric air gun. Upon the piston (5) finishing its rearward movement, the motor (1) reverses direction and causes the piston (5) to compress the forward air chamber (21). Due to the pre-compression, the starting pressure in the forward air chamber (21) is greater then 1 atmosphere.

[00033] Although the coupling of the lead screw (4) to the piston (5) has been through a lead nut, it is recognized by those familiar with the art that alternative means such as magnetic coupling can be used. The advantage of such a noncontact coupling is it allows for a reduced cylinder length and a more compact electric air gun. It will be understood to those familiar with the art that combinations of the above mechanisms and usage of alternative means are possible without departing from the spirit of the invention.

[00034] The preferred invention includes additional enhancements like end of stroke bumpers (17) shown in Figure 1. These elements absorb excess kinetic energy at the ends of stroke and help minimize reactionary forces or prevent damage in the event of a malfunction. These bumpers are preferably made from elastomeric materials including but not limited to urethanes, rubbers and neoprenes. They are designed to absorb impacts of up to 150 inch-lbs without damage.

[00035] Although the preferred embodiment employs a linear compressor described as a lead screw driven piston compressor, it is understood that various other direct mechanical air compression means such as linear compressors using bellows or rotary compressors as in gear or screw compressors could be adapted to operate in the previously described cyclic fashion without departing from the spirit of this invention. These methods directly compress the air in an on demand fashion as opposed to less efficient compression and storage techniques.

[00036] In accordance with the present invention, it is beneficial to combine feeders with the operational characteristics of the electric air gun. In the preferred mode, a projectile feeder (22) is timed to work with the electric air gun as shown in Figure 7. The timing is such that as the bolt (6) is moved in preparation for receiving a projectile (9), a signal is transmitted between the control circuit (3) of the electric motor driven air gun and the projectile feeder motor (42). This ensures that the feeding is done synchronously yielding a more reliable device. In the preferred embodiment, the communication link (38) between the projectile feeder (22) and the electric motor driven air gun is a two -way communication. The preferred requirement for such communications are a minimum of one input and one output, wherein the output from the control circuit (3) is a request for feed and the input is a signal from the projectile feeder (22) that the feed is complete. Additionally, it is possible to use a mechanical power take off from the main drive motor (1) to move the projectile carousel (37).

[00037] A further embodiment to the present invention is possible that incorporates a spring return piston and a drive disconnect feature as shown in Figure 7. In this design, the drive assembly for the piston (5) is released either through a 4-gear clutch design such as described in authors prior patents or an electric release clutch (36), a centrifugal clutch or other clutching means. Releasing the drive in this fashion allows a return spring to rapidly reposition the piston (5) in the cylinder (14) and be ready for the next shot. Other variations on this approach include the use of a vacuum return from the backside of the cylinder (14) when the drive is decoupled. Decoupling the drive from the lead screw (4) allows a rapid return since the spring need only return the piston (5) and not back the entire drive train. A further advantage of this approach are that the motor (1) can drive in a single direction and it reduces the possibility for catastrophic crashes at the ends of the cylinder stroke. Additionally, the retract speed is extremely fast allowing for quick rapid-fire operation.

Circuit Operation:

[00038] A schematic of the current control circuit (3) is shown in Figure 8. In the preferred embodiment, the control circuit (3) includes a microprocessor, high power switching elements and at least one control circuit input. The control circuit input(s) can be internal or external timers or sensors. The preferred design uses a start switch (10), at least one sensor to detect position of the compression piston (5), a motor speed sensor and FETs to switch power to the motor (1). Although these elements are used in the preferred design, it is understood by those familiar with the art that considerably simplification is possible without departing from the spirit of the invention. The cycle begins with the pressing of the start switch (10). Although the power can be directed to the motor (1) through the start switch (10), it is preferable to use low RDS on Mosfets or Relays. In order to maintain responsiveness of an electric air gun, it is desirable that the overall resistance from the power source (2) to the motor (1) be kept very low. A key design parameter is that the overall circuit resistance from the power source (2) to the motor (1) must be less then .02 ohms per applied volt from the power source (2). Additionally, it is preferred that the motor (1) employs rare earth magnets. These motors have higher power densities and give more compact designs with higher cycle rates and higher efficiencies. For very high performance electric air guns, a brushless motor has advantages of lower maintenance, high power density and good heat dissipation. The issue of heat dissipation is important to intermittent on demand electric air guns. A separate cooling fan may be applied to cool the switching elements and/or the motor depending on the duty cycle requirements.

[00039] Once power is applied to the motor (1), through the switching elements the piston (5) begins to advance via rotation of the lead screw (4). The feedback elements are preferably used to determine the location of the piston (5). The control circuit (3) can then make decisions in regards to releasing the high- pressure air in the case of a solenoid or other electromotive retention of the spool. Additionally, this information can be used for reversing or controlling power to the motor (1) depending on the type of compressor used. At the end of a cycle, a further control circuit input such as another sensor, pressure transducer or a timer may be used to shut the power off from the motor and thus leave the electric air gun ready for the next cycle.

[00040] A further enhancement of the control circuit includes storing a number of start switch (10) pulls. This allows the gun to continue cycling in a seamless fashion in the event the start switch (10) is actuated faster than the electrical projectile (9) launches can occur. For example, up to one additional trigger pulls could be stored thus allowing the user the ability to fire sequential shots in a semiautomatic fashion without having to coordinate the shots with the finish of a cycle in the electric air gun. A further embodiment includes the ability to have a shot counter to warn the user when less then a certain number of shots remain. For example, with a power source (2) which is good for 300 shots, a warning light could be illuminated when less then 25 shots remain. Further embodiments involve the use of power source monitoring circuitry to ensure that the user is warned when the power source (2) is low.

[00041] The preferred sensor locations include on the rotational elements for the lead screw counter and in the cylinder (14) to sense at least one position of the piston (5). It is understood by those skilled in the art that the sensors can be used in conjunction with circuit elements to allow location at different places and that sensors can be of many forms including but not limited to limit switches, hall effect sensors, photosensors and reed switches without departing from the spirit of the invention.

[00042] A further improvement in the electric air gun includes routing at least a portion of the power through the start switch (10) to allow cycling only if the start switch (10) is depressed. To reduce contact wear, the control circuit (3) preferably introduces a delay such that the high power is switched after the start switch (10) is fully closed thus eliminating arcing.

[00043] Additional enhancements to the control circuit include provision for or providing a communication port to allow integration of: fully automatic firing, burst mode firing, password protection, assigned operating hours, integration to projectile feeders, laser dot sighting, adapter ports for synchronization with other players, hardwired safeties, failsafe lockout conditions, watchdog timers, and onboard distance sensors. A further embodiment to the design is to power the motor (1) for a brief period after the valve (7) is opened. This serves to maintain cylinder air pressure while the projectile (9) is being pushed out the barrel (8). Furthermore, the use of pulse width modulation for control of the solenoid valve or motor movement can improve the efficiency by reducing the overall power requirements consistent with certain preset targets. These could include tuning the motor energy for ball speed or reducing the holding current for the solenoid valve. For example, opening the solenoid valve at the appropriate firing time in Figure 1, may take a pulse of 10 amps. The maintenance current might only be 3 amps. By pulse width modulating, the solenoid voltage after the initial current spike the nominal current could be reduced yielding a more efficient design.

[00044] In a second embodiment illustrated in Figure 9, the user presses a start switch

(10), or trigger that causes power to be directed from the power source (2), to the motor (1) by the control circuit (3). The control circuit is described later but can be as simple as any means for connecting and disconnecting power to the motor (1) to allow an air compression and projectile fire cycle. The motor (1) turns transferring energy through the rotating elements of the system into a linear motion converter and subsequently into the compression of air. The linear motion converter is any means of converting the rotating motion into a linear translation. Examples of linear motion converters include leadscrews with leadnuts, gearbelts with gearbelt pulleys and rack and pinions. The embodiment illustrated in Figure 9 includes a motor (1), a gear reduction system (32a), and a rack and pinion assembly (45 a) including rack (4a) and rack pinion (41a). The rack pinion (41a) is coupled to the motor (1) through the gear reduction system (32a), which comprises one or more stages of gear reduction. The rack (4a) is attached to the piston (5), as shown in Figure 9. The purpose of the gear reduction system (32a) is to allow sufficient energy to be transferred from the motor (1) to the air which is being compressed by the piston (5). Other reduction means including, but not limited to, pulleys, gear belts, planetary systems, could be used without departing from the spirit of the invention. In the present embodiment, the piston (5) and the cylinder (14) form the forward air chamber (21). At its initial state before the cycle starts, the forward air chamber (21) has a volume that is greater than 3 in³, with the most desirable starting volume being between 7 in³ and 9 in³. The initial pressure of this starting air is between 0 and 2 atmospheres with the most desirable starting pressure being 1 atmosphere. The piston (5) begins to move forward in cooperation with the rack (4a) compressing the air in the forward air chamber (21) while also energizing the piston return spring (35a). The piston return spring (35a) biases the piston (5) and rack (4a) to the initial starting position. Although the return element is shown as a spring in the attached figures, alternative means such as vacuum on the back side of the cylinder (14) could be used as well. The important point is that the return element is energized by the motor (1) during the compression cycle.

[00045] Although the embodiment of Figure 9 shows the initial position of the piston (5) at the rearward part of the stroke, it is possible to change the starting point such that it corresponds to a small amount of initial compression of the air. A retaining mechanism such as a sear pin to lock the gear and rack (4a), could be used to maintain this semienergized state. The purpose of allowing some of the energy to be stored in the air stream would be to reduce the time between when trigger (42a) is pulled and shot fired (lock time) on the first shot. This reduction would stem from the fact that some of the firing energy is already stored in the air stream and that the piston (5) would not need to travel as far to complete the stroke. The advantage in reducing the lock time on the first shot is that operator is most likely to notice a delay on the first shot of a sequence but less likely to notice on subsequent shots. The means for retaining the piston (5) in such position could additionally be electrical such as a solenoid detent in addition to mechanical means. Referring to Figure 12, a substantial lock time improvement of the present invention can be achieved by using an elastic storage means (36a), such as a spring, to drive the piston. The energy is stored in the spring then cocked in the rearward position. The spring could be steel, rubber, etc. The motor (1) and linear motion converter drives the piston (5) rearward to store energy in the elastic storage element (36a). When the trigger (42a) is pulled, the retaining mechanism (37a) releases the piston (5) allowing it to be driven forward to compress the air. This releasing of the spring energy and allowing it to compress the air happens quickly giving a more responsive trigger to the player for the first shot. By incorporating a valve (7) in conjunction with this elastic storage means, we can eliminate or greatly minimize the double recoil effect commonly seen in spring piston air guns. This technique of compressing the air against a valve allows us to substantially convert most of the stored energy into energy in the air stream while at the same time controlling the speed at which the piston (5) impacts the end of the cylinder (14). This allows a much gentler impact of the piston (5) on the end of the cylinder (14), thus greatly mitigating the double recoil and associated wear seen in spring piston air guns.

[00046] Continuing our discussion of the cycle, as the pinion (41a) rotates it drives the rack (4a) which moves the piston (5), down the cylinder (14) in the forward direction, storing energy in the air stream. This energy rapidly compresses the air in the forward air chamber (21) in such a way that the compression exponent is polytropic. At the appropriate forward point the compressed air in the forward air chamber (21) is channeled to the projectile (9) through the valve (7). In an efficient design, the time involved in the compression cycle is sufficiently short so as to yield a compression exponent of at least 1.10 .

[00047] At the end of the compression stroke, the forward air chamber (21) contains high-pressure air that is released to the projectile (9) through the valve (7). The opening of the valve (7) can be by direct mechanical coupling and/or electrical techniques. As is shown in Figure 9, one embodiment incorporates an electronic solenoid (18) which is controlled in response to timing and/or a sensor such as air pressure, piston location or motor speed. Ideally, the electronics controls the motor such that the valve (7) releases when the motor (1) has slowed to such a point that most of the rotational kinetic energy has been converted to energy in the compressed air. At or near the end of the piston (5) stroke, the valve (7) is caused to shift open. This rapidly releases the compressed air into the compressed air passageway (13) and then into the barrel (8) of the air gun. In order to be effective in an electric marker, it is essential that valve (7) losses be held to a minimum. Two parameters that must be carefully controlled in the valve (7) are pressure drop through the valve (7) and valve opening time.

[00048] The projectile (9), which is located within the barrel (8), begins to accelerate under the force of the compressed air and is driven out of the barrel (8) at a high velocity. At this point, the motor (1) may be allowed to continue to rotate driving the rack pinion (41a). The rack pinion (41a) has a section (47a) of the gear in which the teeth (46a) have been cutaway. When this section (47a) opposes the mating rack (4a), there is nothing to retain the rack and pinion assembly (45a) in its current position. The piston return spring (35a) will then force the rack and piston assembly (45a) back to its initial starting position. Decoupling the motor (1) and drive train (32a) from the piston (5) and rack (4a) allows a rapid return since the piston return spring (35a) only needs to position the piston and rack assembly (45a). This results in a more efficient system with higher rates of fire. A further advantage of this approach is that the motor (1) can drive in a single direction and crashing the piston (5) into the end of the cylinder (14) can be eliminated by controlling the number of gear teeth (46a) in both the rack (4a) and rack pinion (41a).

[00049] Looking to Figures 9 and 10, a sensor switch (12) recognizes when the piston (5) is in its approximate initial position and ready for cycle initiation. The sensor switch (12) may be a hall switch used in conjunction with a magnet (11), which is attached to the piston (5). It is understood that any sensing means which allows positional information of the piston (5) could be used for the sensor switch (12), including but not limited to: reed switches, optical sensors and mechanical limit switches. It is further desired to have a means of monitoring the rotation and or rotational velocity of the system. Such means could include voltage sensing on the motor (1) or a rotational sensor located preferably in a gear within the drive train (32a). The sensor could allow the control circuit (3) to determine the piston (5) location by counting revolutions and processing the information as it relates to both speed and linear inch of travel per revolution of the motor (1). Additionally, the voltage sensing scheme could be used to monitor either the loaded or unloaded motor velocity and thus allow tuning the system for maximum energy extraction per cycle. A further use of such velocity information would be to limit the velocity of the motor (1) during the retraction of the piston (5), thus ensuring sufficient time for the rack (4a) and piston (5) to return to the start position before engaging the rack pinion (41a). Additional uses of such information could be to alter the speed of the piston (5) during the compression stroke or altering the timing of the release of the valve (7). After the air pressure has been released to the projectile (9) and the piston (5) has returned, a full cycle has been completed and the electric air gun is ready for initiation of another cycle. It should be noted while a rack and pinion assembly is described in this embodiment, substantially similar elements which convert rotational motion to linear motion (i.e. a linear motion converter) may be substituted. Such elements could include, but are not limited to, slider crank mechanisms, lead screw and nuts or gear and belt driven systems.

[00050] A bolt (6) is used in many air gun designs to chamber the projectile (9). It can be either manually operated or automatically operated. In the embodiment shown in Figures 9 and 10, the bolt (6) is coupled to the rack (4a) thru a system of linkages and springs. These linkages and springs include an actuation limit spring (30a), a bolt link (15) and a bolt return spring (20). Additionally, the air compressed by the piston (5) may travel thru the bolt (6) allowing for a more efficient and compact design. In the present design, the bolt coupling mechanism is referred to as a lost motion device. The purpose of this is to limit the motion of the bolt to a fraction of the piston (5) movement with the desired ratio being less then 80%. The actuation limit spring (30a) which is inserted between the bolt link (15) and the bolt (6) limits the bolt (6) forces improving the safety profile against possible pinch points. For example, if the user were to depress the mechanism and insert their finger in the projectile inlet port (16), the force of the bolt (6) if directly coupled to the piston (5) could injure the operator. The bolt return spring (20) maintains a normally open bolt design, increasing the time available for the projectile (9) to fall into position. Depending on the design requirements, the springs (20, 30) could be biased in such a way as to result in open or closed bolt designs. Since many of these designs will employ gravity feeders, the open bolt design is useful as it allows extra time for the projectile (9) to fall into place during intermittent firing modes.

[00051] The present invention includes additional enhancements like end of stroke bumpers (17) shown in Figure 9. These elements absorb excess kinetic energy at the ends of stroke and help minimize reactionary forces or prevent damage in the event of a malfunction. These bumpers are may be made from elastomeric materials including but not limited to urethanes, rubbers and neoprenes. They are designed to absorb impacts of at least 10 inch-lbs without damage.

Circuit Operation:

[00052] A schematic of the control circuit (3) is shown in Figure 13. In the embodiment illustrated, the control circuit (3) includes a microprocessor, high power switching elements and at least one control circuit input. The control circuit input(s) can be internal or external timers or sensors. Looking additionally to Figure 9, the gun uses a start switch (10), at least one sensor to detect position of the compression piston (5), a method of determining motor speed and FETs or relays to control power to the motor (1). Although these elements are used in the present design, it is understood by those familiar with the art that considerable simplification is possible without departing from the spirit of the invention. The cycle begins with the pressing of the start switch (10). Although the power can be directed to the motor (1) through the start switch (10), it is desirable to use Mosfets or Relays.

[00053] In order to maintain responsiveness of an electric air gun, it is desirable that the overall resistance from the power source (2) to the motor (1) be kept very low. A key design parameter is that the overall circuit resistance from the power source (2) to the motor (1) must be less then .02 ohms per applied volt from the power source (2). For very high performance electric air guns, a brushless motor has advantages of lower maintenance, high power density and good heat dissipation. The issue of heat dissipation is important to intermittent on demand electric air guns. A separate cooling fan may be needed to cool the switching elements and/or the motor depending on the duty cycle requirements. The cooling fan may be controlled in response to either a heat sensor such as a thermister or thermocouple placed within the body of the electric air gun. Additionally, the heat sensor could be used to limit the cycling of the unit should excessive temperatures be reached. It is further possible to control the cooling fan in response to a predetermined program stored within the microprocessor.

[00054] Once power is applied to the motor (1), the piston (5) begins to advance via the rotation of the rack pinion (41a) driving the rack (4a). The feedback elements are used to determine the location of the piston (5). The control circuit (3) can make decisions in regards to releasing the high-pressure air in the case of a solenoid or other electromotive retention of the valve (7). Additionally, sensor input can be useful in recovery from various jam conditions. At the end of a cycle, a further control circuit input such as another sensor, pressure transducer or a timer may be used to shut the power off from the motor (1) and thus leave the electric air gun ready for the next cycle.

[00055] A further enhancement of the control circuit (3) includes monitoring the start switch (10) depressions during a cycle. This allows the gun to continue cycling in a seamless fashion in the event the start switch (10) is actuated faster than the electrical projectile (9) launches can occur. For example, one or more additional trigger (42a) pulls could be stored thus allowing the user the ability to fire sequential shots in a semiautomatic fashion without having to coordinate the shots with the finish of a cycle in the electric air gun. A further embodiment includes the ability to have a shot counter or battery monitor to warn the user when the battery is low. For example, with a power source (2) which is good for 300 shots, a warning light could be illuminated when less then 25 shots remain. Additionally, the voltage of the battery or the voltage applied to the motor (1) during the compression cycle may be monitored. This allows the microprocessor to adjust the duty cycle of the motor (1) thru either pulsing the motor (1) or pulse width modulation of the motor power to create uniform compression cycles even as the battery voltage decays, thus extending the number of shots per charge.

[00056] The sensor locations may include at least one position of the piston (5). In order to determine motor (1) velocity, it is desirable to monitor the voltage on the motor (1) during an unloaded condition. The difference between these voltages multiplied by the motor Kv (rpm/volt) constant can be used to approximate the motor speed. It is understood by those skilled in the art that the sensors can be used in conjunction with circuit elements to allow location at different places and that sensors can be of many forms including but not limited to limit switches, hall effect sensors, photosensors and reed switches without departing from the spirit of the invention.

[00057] A further improvement in the electric air gun includes routing at least a portion of the power through the start switch (10) to allow cycling only if the start switch (10) is depressed. To reduce contact wear, the control circuit (3) may introduce a delay such that the high power is switched after the start switch (10) is fully closed thus eliminating arcing.

[00058] Additional enhancements to the control circuit include provision for or providing a communication port or a display which communicates status conditions. Safety provisions include the microprocessor locking out the unit operation on certain fault conditions, integration of a password required for operation or the inclusion of a keyswitch required for operation.

Claims

CLAIMSWe claim:

1. A valve for an electric motor driven air gun comprising: a power source; a control circuit connected to said power source; a motor; means for coupling said control circuit to said motor for the purpose of directing power from the power source to the motor; a linear motion converter; means for coupling said motor to said linear motion converter; a valve having a Cv greater than 1 and an opening time of less than 20 milliseconds, wherein said linear motion converter pushes compressed air that is released.

2. An apparatus for launching a projectile comprising: a power source; a control circuit coupled to said power source; a motor; means for coupling said control circuit to said motor for the purpose of directing power from the power source to the motor; a linear motion converter; means for coupling said motor to said linear motion converter; a piston; means for coupling said piston to said linear motion converter; a cylinder, with a front end and a rear end, in which the piston reciprocates; an energy storage means active in one direction of piston movement; an energy recovery means active in the opposite direction of piston movement; a valve; a barrel; means for controlling the valve in order to direct air, that is compressed by the piston, from the cylinder to the barrel; and a projectile located in the barrel wherein said projectile is released from the barrel due to compressed air being forced from the cylinder to the barrel.

3. An apparatus for launching a projectile comprising: a power source; a control circuit coupled to said power source; a motor; means for coupling said control circuit to said motor for the purpose of directing power from the power source to the motor; a linear motion converter; means for coupling said motor to said linear motion converter; a piston; means for coupling said piston to said linear motion converter; a cylinder, with a front end and a rear end, wherein the piston reciprocates within said cylinder; a means to transfer air from the rear end of the cylinder to the front end of the cylinder or from the front end of the cylinder to the rear end of the cylinder; a valve; a barrel; means for controlling the valve in order to direct air, that is compressed by the piston, from the cylinder to the barrel; and a projectile located in the barrel wherein said projectile is released from the barrel due to compressed air being forced from the cylinder to the barrel.

4. A cyclical apparatus for launching a projectile comprising: a power source; a control circuit coupled to said power source; an electric motor driven compressor; means for coupling said control circuit to said electric motor driven compressor for the purpose of directing power from the power source to the electric motor driven compressor; a start sensor and a stop sensor, wherein said electric motor driven compressor turns on in response to said start sensor and turns off in response to said stop sensor. a valve; a barrel; a storage chamber; means for controlling the valve in order to direct air from the storage chamber to the barrel; and a projectile located in the barrel wherein said projectile is released from the barrel due to compressed air being forced from the cylinder to the barrel.

5. An apparatus for launching a projectile comprising: a power source; a control circuit coupled to said power source; a motor; means for coupling said control circuit to said motor for the purpose of directing power from the power source to the motor; a compressor; means for coupling said motor to said compressor for the purpose of compressing air; a compression cycle, wherein said compression cycle has an ending air compression exponent greater than 1.1.

6. An apparatus for launching a projectile comprising: a power source; a control circuit coupled to said power source; an electric motor driven compressor; and a sensor, wherein the speed of the electric motor driven compressor is controlled or monitored by said sensor.

7. An apparatus for launching a projectile comprising: a power source; a control circuit coupled to said power source; an electric motor driven compressor; and means for connecting said control circuit to said electric motor driven compressor for the purpose of directing power from the power source to the electric motor driven compressor, wherein said connecting means is characterized by a resistance of less then .02 ohms per applied volt.

8. An apparatus for launching a projectile comprising: a power source; a control circuit coupled to said power source; a motor; means for coupling said control circuit to said motor for the purpose of directing power from the power source to the motor; a linear motion converter; means for coupling said motor to said linear motion converter; a piston; means for coupling said piston to said linear motion converter; a cylinder, with a front end and a rear end, in which the piston reciprocates; a valve; a projectile feeder; a bolt; means to coordinate the projectile feeder with the position of the bolt; a barrel; means for controlling the valve in order to direct air, that is compressed by the piston, from the cylinder to the barrel; and a projectile located in the barrel wherein said projectile is released from the barrel due to compressed air being forced from the cylinder to the barrel .

9. An apparatus for launching a projectile comprising: a power source; a control circuit coupled to said power source; a motor; means for coupling said control circuit to said motor for the purpose of directing power from the power source to the motor; a linear motion converter; means for coupling and de-coupling said motor to and from said linear motion converter; a piston; means for coupling said piston to said linear motion converter; a cylinder, with a front end and a rear end, in which the piston reciprocates; a mechanical energy storage element that repositions the piston after a compression cycle is complete; a valve; a barrel; means for controlling the valve in order to direct air, that is compressed by said piston, from the cylinder to the barrel; and a projectile located in the barrel wherein said projectile is released from the barrel due to compressed air being forced from the cylinder to the barrel.

10. The apparatus according to Claim 9, wherein the mechanical energy storage element is selected from the group consisting of a compression spring, a torsion spring and an air spring or vacuum.

1 1. The apparatus according to Claims 2, 3, 8 or 9, wherein the linear motion converter is a lead screw.

12. The apparatus according to Claims 2, 3, 8 or 9, wherein the linear motion converter is a slider crank mechanism.

13. The apparatus according to Claims 2, 3, 4, 8 or 9, wherein the valve is electrically controlled.

14. The apparatus according to Claims 2, 3, 8 or 9, wherein the means for coupling the motor to the linear motion converter has at least one gear.

15. The apparatus according to Claims 2, 3, 4, 8 or 9, wherein the means for controlling the valve is in response to air pressure or piston displacement.

16. The apparatus according to Claims 2, 3, 4, 8 or 9, wherein the projectile is selected from the group consisting of a paintball, an airsoft ball, a "bb", and a pellet.

17. The apparatus according to Claims 2, 3, 4, 8 or 9, further comprising one or more sensors.

18. The apparatus according to Claims 2, 3, 8 or 9, further comprising energy absorbing bumpers that are used at the ends of the stroke of the piston.

19. The apparatus according to Claims 2, 3, 4, 5, 6, 7, 8 or 9, wherein the control circuit is further comprised of a microprocessor.

20. An electrically-driven compressed air gun used for firing a projectile, said gun comprising: a power source; a motor connected to said power source; a sensor; means of controlling the motor using information from the sensor; a linear air compressor; means of coupling the motor to the linear air compressor a valve; a barrel to receive the projectile; and means for controlling the valve in order to direct compressed air from said linear air compressor to said barrel; wherein the projectile is released from said barrel due to compressed air being forced to said barrel from said linear air compressor.

21. An apparatus for launching a projectile comprising: a power source; a control circuit coupled to said power source; a motor connected to said control circuit, said control circuit directing power from the power source to the motor; a pinion connected to said motor; a rack coupled with said pinion; a piston coupled to said rack; a cylinder having a front end and a rear end, said cylinder housing said piston; an air energy storage means active in one direction of piston movement; a valve; a barrel supporting the projectile; means for controlling the valve in order to direct air, that is compressed by the piston, from the cylinder to the barrel; wherein said projectile is released from the barrel due to compressed air being forced from the cylinder to the barrel.

22. An apparatus for launching a projectile comprising: a power source; a control circuit coupled to said power source; a motor; means for coupling said control circuit to said motor for the purpose of directing power from the power source to the motor; a linear motion converter; means for coupling said motor to said linear motion converter; a piston; means for coupling said piston to said linear motion converter; a cylinder, with a front end and a rear end, wherein the piston reciprocates within said cylinder; a bolt; lost motion means for coupling said bolt to said reciprocating linear motion converter; a valve; a barrel; means for controlling the valve in order to direct air, that is compressed by the piston, from the cylinder to the barrel; and a projectile located in the barrel wherein said projectile is released from the barrel due to compressed air being forced from the cylinder to the barrel.

23. The apparatus according to Claim 21, wherein the piston is returned to its initial position by using a mechanical energy storage element selected from the group consisting of a mechanical spring, an air spring, an elastomeric element or a vacuum.

24. The apparatus according to Claim 19, wherein the linear motion converter includes a rack.

25. The apparatus according to Claim 21, wherein the rack pinion has at least 5% of its teeth removed

26. The apparatus according to Claim 20, wherein the circuit includes a separate cooling fan.

27. The apparatus according to Claims 20, wherein the projectile is selected from the group consisting of a paintball, an airsoft ball, a "bb", and a pellet.

28. The apparatus according to Claims 20, wherein the circuit includes at least one means of safety lockout.

29. The apparatus according to Claim 20, wherein the circuit brakes the motor.

30. The apparatus according to Claim 20, wherein the circuit controls the speed of the motor in response to the sensors.

31. The apparatus according to Claim 22, wherein the coupling to the bolt includes at least one spring.

32. The apparatus according to Claim 20, wherein the circuit contains a communication port for the exchange of data with an external device.

33. The apparatus according to Claim 20, wherein the circuit includes an interface for displaying attributes.

34. An apparatus for launching a projectile comprising: a power source; a control circuit coupled to said power source; a motor; means for coupling said control circuit to said motor for the purpose of directing power from the power source to the motor; a linear motion converter, a piston; means for coupling said piston to said linear motion converter; a cylinder, with a front end and a rear end, in which the piston reciprocates; an elastic energy storage means active in one direction of piston movement; a retaining mechanism, means for retaining mechanism to latch elastic storage means in energized state, a valve; a barrel; means for controlling the valve in order to direct air, that is compressed by the piston, from the cylinder to the barrel; a projectile located in the barrel wherein said projectile is released from the barrel due to compressed air being forced from the cylinder to the barrel.

35. The apparatus according to claim 34 that uses a solenoid to release the retaining mechanism.

36. The apparatus according to claim 34 that uses a mechanical linkage to release the retaining mechanism.

37. The apparatus according to claim 34 wherein the elastic energy storage means is a steel spring.

38. The apparatus according to claim 34 wherein the elastic energy storage means is rubber tubing.