WO2008059496A2

WO2008059496A2 - Magnetic means of reducing the parasitic output of periodic systems and associated method

Info

Publication number: WO2008059496A2
Application number: PCT/IL2007/001402
Authority: WO
Inventors: Shachar Rotem; Ori Goldor
Original assignee: Q-Core Ltd.
Priority date: 2006-11-13
Filing date: 2007-11-13
Publication date: 2008-05-22
Also published as: IL179232A0; WO2008059496A3

Abstract

The present invention discloses a mechanism which moves cyclically when one or more or the resisting forces upon which the mechanism operates is a force pointing in a fixed direction along the entire operation cycle. Its size is a function of cycle's progress, being cyclical, the force Fk. The cyclic motion can be linear, angular, or other. In addition, installation of system mechanism to balance magnetic forces uses permanent magnets The invention also discloses methods and mechanisms adapted to reduce the parasitic output of periodic systems comprising at least one moving member acted upon by obstructive forces, the magnitude of said obstructive forces being dependent upon the displacement of said moving member; and a plurality of balancing elements providing balancing forces upon said moving member, said balancing forces at each point along the path of motion of the moving member being of approximately equal magnitude to that of said obstructive forces at said point; such that the parasitic output is reduced to about zero.

Description

MAGNETIC MEANS OF REDUCING THE PARASITIC OUTPUT OF PERIODIC SYSTEMS AND ASSOCIATED METHOD

FIELD OF THE INVENTION

The present invention generally relates to a magnetic means of reducing the parasitic output of periodic systems and an associated method. More specifically the invention relates to the provision of a displacement dependent magnetic counterforce to balance displacement dependent forces in periodic systems.

BACKGROUND OF THE INVENTION

Periodic systems may be defined as systems wherein at least one component performs a series of steps repeatedly a plurality of times. Parasitic input applies to energy consumed by a periodic system to produce parasitic output. Parasitic output comprises parasitic input and internal losses. The parasitic input is greater than the parasitic output because of internal losses that are to be reduced. Means and methods for minimizing scales and sizes of periodic systems, for balancing periodic systems, characterized by reducing parasitic output to about zero and for reducing mass of moving member in a various periodic systems e.g., in infusion pumps are still a long felt needs.

SUMMARY OF THE INVENTION

It is thus one object of the present invention to disclose a mechanism which moves cyclically when one or more or the resisting forces upon which the mechanism operates is a force pointing in a fixed direction along the entire operation cycle. Its size is a function of cycle's progress — being cyclical - the force F_k. The cyclic motion can be linear, angular, or other. In addition, installation of system mechanism to balance magnetic forces uses permanent magnet.

It is another object of the present invention to disclose a mechanism as defined above, where in addition to magnetic balancing throughout the cycle, a single or several locations (exact spots) where the magnetic force is stronger are defined. This type of mechanism has an integrated property of being a magnetic balancing mechanism and a locking point along the entire cycle (toggle?) as described in this document. It is another object of the present invention to disclose a mechanism as defined above, in which the magnetic balancing mechanism acts throughout the cycle, but with a given offset. That is, F_m≠Fk in parts of the cycle or during the entire cycle.

It is another object of the present invention to disclose a mechanism as defined above wherein the magnetic balancing only occurs during part of the cycle.

It is another object of the present invention to disclose a mechanism as defined above wheren the balancing magnetic interface uses permanent magnets that operate against permanent magnets, some of which are possibly connected to static parts and some of which are connected to moving parts, or to a magnetic balance interface where the magnets operate against individual metal parts or any material that react to magnetic fields, where the magnetic are integrated with static or moving parts of the mechanism.

BRIEF DESCRIPTION OF THE FIGURES

The objects and advantages of various embodiments of the invention will become apparent from the following description when read in conjunction with the accompanying drawings wherein

Figure 1 represents the force-displacement profile mapping the force needed to squeeze a silicon tube containing water at a range of pressures;

Figure 2 represents the balancing mechanism according to one embodiment of the invention;

Figure 3 represents a balancing mechanism for a finger-type peristaltic infusion pump according to one embodiment of the invention; and

Figure 4 presents the force profile operating on the mechanism (Fk) which is linear in this case.

Figure 5 represents the force-displacement profile mapping the force needed to squeeze a silicon tube containing water at a range of pressures.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following description is provided, alongside all chapters of the present invention, so as to enable any person skilled in the art to make use of said invention and sets forth the best modes contemplated by the inventor of carrying out this invention. Various modifications, however, will remain apparent to those skilled in the art, since the generic principles of the present invention have been defined specifically to provide an energy-saving mechanism used with cyclical mechanical mechanisms operating with spring systems; a spring system is broadly defined for any system that exerts a large negative force (resistance motion) whose amplitude is a function of the movement's magnitude. Here, the energy source is limited and the mechanism is moved by electricity or other means. An example in using this system is in portable medical instruments such as infusion systems or feed pumps that operate using suction mechanisms based open cyclical pressing on a flexible pipe by mechanical "fingers". Later on, the principles upon which this innovative mechanism is based are explained. However, as mentioned, the same principle can be applied to many additional mechanisms and systems.

As mentioned, this system's operating principles is explained with reference to the mechanical of a finger-type peristaltic infusion pump (known also as DDS). However, one must not deduce from this that this innovative system can not be utilized on other mechanisms.

Mechanical "finger-operated" pumps use at least three mechanical "fingers" that press upon a flexible pipe in a given order - producing cyclical pressing action. Thus, each pressing by a mechanical "finger" is part of an overall cyclical pumping routine. This cycle has at least two vital and two optional operation steps.

1. Pressing.

2. Pause in pressing (optional step).

3. Release.

4. Pause in the release action (optional step).

In order to explain the principle of this innovation, without being specific, one may assume several assumptions that will simplify describing it:

Mechanical "fingers" move linearly towards flexible pipes and when they press on them. Pressing on these pipes (moving along the X-axis - abscissa) is defined to be positive when movement is towards the pipes. It is assumed that gravitational forces are of negligible amplitude relative other forces operating in the system. A general description of the main resistive forces to the mechanical "finger" movement will be:

Step 1 - during pressing (forward movement of the mechanical finger)

1. F = [- F₄ (or) - F₁ (X) - F₄, (X)](I _{+ J}t/)

Step 2 - during a pause in pressing

2. F = -F, (.T)(I + //)

Step 3 - during release (rearward movement of the mechanical "finger")

3. F = [- F₄ (X) + F₁, (X)](I + //)

Step 4 - during release (if x≠O)

Where:

F is the balanced force that the motion exerts on the mechanical "finger". This also includes the mechanism's internal friction forces. FΛcfuat«r+ F = O.

F_k is the spring's force (depends upon the distance that the mechanical "finger" has moved). This force does not resist movement when the mechanical "finger" recedes.

F_v is the viscous force that is a function of the mechanical "finger's" velocity..

F_d is the dynamic force that is a function of the mechanical "finger's" acceleration. (This assumes that it always acts in the direction opposite to the movement). μ is the general friction coefficient between the system's moving parts, (both static and dynamic). Usual engineering operations are done on the two main operational steps to prevent energy waste:

• Friction coefficients are reduced.

• The cyclical actions are designed such that movement profiles will have the least amount of accelerations (F_d- >0).

The present invention is adapted to save very significant amounts of energy by "zeroing" the spring force component (F_k=O) over the entire operating cycle - irrespective of the force's amplitude, when this spring is properly designed, it may exert the largest force.

In this type of pump, the main spring force is F_k - where:

5. F_k » F_r,F_d

F * -F_k (l + μ)

The spring's force is zeroed by adding a magnetic force (F_m) that acts upon the mechanical "finger". The magnitude of this magnetic force that acts on the mechanical "finger" is equal to the spring's force. However, the magnetic force operates in the direction opposite that of the spring force.

Among the reasons why this is possible is that the spring's force always acts in the same direction is irrespective of the mechanical "finger's" movement direction (see equations 1 and

3).

6 F - -F

The balancing force that acts on the mechanical "finger" will be: During step 1 - pressure:

7. F * [- F_k (x) + F₁₁, (X)](I + //) = 0

During step 2 - pause (on pressing).

8. F = [- F_k (x) + F_m (X)](I ₊ μ) = 0 During step 3 - release.

9. F * [- F_k (x) + F_n, (X)](I ₊ ;/) = 0

During step 4 - pause (if x≠O).

A conclusion that is immediately seen is that the force F equals zero, even when the system's efficiency (friction) is low.

The balancing magnetic force is produced by connecting a permanent magnet to the mechanism's static part and a magnetic metal (that reacts with magnetic fields) to the mechanism's moving part (See figure 1). Permanent magnets can be combined with electromagnets. However, understandably, these magnets do not lead to energy savings. Another way of accomplishing this is using two magnets or connecting the magnetic metal to the static part and the magnet to the moving part (see drawing). Understandably, this type of interface can utilize several magnets and several pieces of magnetic metal. Magnetic variables are: magnetic strength of the magnets, type of magnetic metals, geometric configurations of each component, and sizes and shapes of air gaps between the magnets.

Understandably, one can argue that by balancing the spring's force acting on the mechanism by using a magnetic force, the ability to again use the spring's force of step 3 (release step) is lost when instead of expending energy (even the smallest amount of energy) one could do this using the spring's force. This argument is not valid for most cases since even when combining the return that the mechanism's movement is desirably controlled, especially within a predetermined known velocity profile. This desire, forces us to introduce a restraining force to oppose the spring's force. Understandably, this argument does not solve the pause step (step 2) and the final pause after release (step 4).

Another way of explaining how this invention operates is by using the analogy of balancing weights used in elevators.

A non-magnetically balanced mechanism is similar to an elevator cell connected to an electric motor via a wire or cable. The electric motor must produce a large force to lift the elevator cell (with its contents) upwards. When the elevator stops at its highest level, a large force is expended, or alternately an arresting mechanism, whose turning on and off necessitates use of much force due to weights of the cell and its contents, is needed. When the elevator cell is lowered by the electric motor, the same force that was needed to raise this cell must be used to lower it. Otherwise, the raise elevator cell would crash when it descends.

A large amount of force must be expended by the electric motor or by the elevator's arresting mechanism to maintain its position when the elevator is at its lowest position, when the elevator cell is still suspended in its air shaft.

The magnet balancing mechanism is to be compared with the elevator cell, whose entire weight (and contents) is one side (that is raised) and is connected to one side of an electric motor's wheel while the other side (which is lowered) is connected to the wheel's second side. Weights whose mass equals the average mass the elevator cell and its contents (which are usually raised or lowered) are connected to the wheel's second side. This weight can also be a weight selected by the elevator's designer.

When this mechanism is used, the only force that must provided by the elevator motor is the force needed to balance the difference between the elevator weights (the cell and its varied contents and the counter-balancing weight). It is also understood the elevator motor must produce accelerating and decelerating forces and is forced to compensate for overall system losses.

It is noted that use of this mechanism in elevators (See fig. 2), such as the use of any magnetic balancing mechanism, can be used with smaller relays, motors, transport, etc. This will result in the reduction of general system losses.

Although almost similar principles are involved, three significant differences exist in magnetic balancing systems used in elevators:

• Magnetic balancing mechanisms can generally be used with relatively small operating inductance gaps, while elevators may move very large operating distances.

• Magnetic balancing mechanisms may operate at any required orientation (relative to the gravitation force vector). This is the difference in use in elevators or in any mechanisms based on gravitational balance.

• Magnetic balancing mechanisms do not necessarily increase the weight of a system's moving parts. Therefore, the magnitude of force required to accelerate the system does not increase. On the other hand, balancing weights of elevators double the weight that must be accelerated.

It is important to emphasize that the patent on the magnetic balancing mechanism is substantially different than from any mechanisms presently available where magnets are used to "arrest items in their final stage". Cyclic motion of these mechanisms is the only saving where there is no need to provide forces to maintain the system in its final position. Moreover, when these mechanisms are used, it is difficult to maintain a steady velocity when the system approaches or recedes from a magnet — and understandably there is no energy saving during operation.

Construction of a magnetic balance for a given mechanism: To begin with, the spring force function operating in the system are defined. After this, the magnetic force (using permanent magnets) that produces a force which is similar to that of the spring force must be defined. In the past, this definition could only be done for very simple cases - where simple analytic calculations were done together with actual system tests. Presently, FEA (finite element analysis) Computer Programs such as the ANSOFT Maxwell 3D Program can be used. Using this analysis, one can design and produce various magnet interfaces that balance the mechanical mechanism along the entire movement vector.

An example of a magnetic balance that produces an almost linear force profile within the operating range of the mechanical mechanism (about 3 mm) is given below. This also, in turn, develops almost linear forces.

Figure 3 represents a balancing mechanism for a finger-type peristaltic infusion pump (here, one type of a Q-core commercially-available pumping mechanism) according to yet another and specific embodiment of the invention.

The graph showed in figure 4 presents the force profile operating on the mechanism (Fk) which is linear in this case. The magnetic balancing force (F_m) and the equal force (F) is like the force needed by the external operator (motor, solenoid, other) in order to move the mechanism in a cyclic motion (in a system where the acceleration and the general losses are negligible).

Additional advantages of this invention are presented: Reduction of the force needed to do the work (F) directly affects the following:

• Force relay mechanisms (such hoists, cam wheels, relays, hinges, other) will be miniaturized. This scaling down will reduce the weights of these components. Weight reduction will reduce the dynamic forces developed in the system — leading to additional energy savings.

• Activators such as electric motors or solenoids can be of lower strength and also be smaller. This change will reduce wasted (thermal) energy in motor solenoids or solenoids (including eddy currents) This will lead to a direct saving in energy consumption for the entire operation cycle.

• Friction losses will be reduced or will completely disappear. (For example, those losses that occur between the magnetically balance mechanical finger that moves linearly and the cam that pushes and pulls it). This will again lead to a direct saving in energy consumption for the entire operation cycle.

• Reduction of friction force will necessarily lead to a reduction of wear and tear of moving parts and will increase lifetimes of the moving mechanisms.

• The possibility of using much smaller activators (electric motors), much smaller relays, and lower strength energy sources will be translated into immediate saving in mechanism production costs.

The terms 'about' or 'approximately' apply hereinafter to any value in a range from below 30% of a specified value to above 30% of said value.

The term 'parasitic input' applies hereinafter to the energy consumed by the system to produce parasitic output. The parasitic input is greater than the parasitic output because of internal losses. For example, an elevator with a cabin of weight 10,000 N being used to raise a man of weight 700 N through 10 m produces 7 kJ of output of which only 7 kJ are necessary output the remaining 100 kJ are parasitic output due to raising the cabin itself.

The term 'balancing elements' refers hereinafter to elements provided to a system so as to provide balancing forces. Such balancing elements include inter alia, magnetic elements, electrostatic elements, fix magnets, mechanical elements such as springs, wires, strings or any combination thereof.

The term 'balancing forces' refers hereinafter to forces provided to balance other forces. Balancing forces are approximately equal in magnitude and opposite in direction to the forces they are balancing.

The term 'displacement' refers hereinafter to the extent and direction of any change in the position of a body.

The term 'dynamic systems' refers hereinafter to any system which contains at least one moving member.

The term 'input' applies hereinafter to energy consumed by a system.

The term 'magnitude' applies hereinafter to the modulus quantity of a vector.

The term 'moving member' refers hereinafter to any portion of a device whose position changes during the working of the device.

The term 'necessary output' applies hereinafter to the energy needed to be produced by a system in order to perform the task for which the system is designed. For example in order perform the task of raising a man of weight 700 N through 10m the necessary output of a system such as an elevator is 7 kJ of energy.

The term Obstructive forces' refers hereinafter to any force which acts upon a moving member during its movement. More specifically this term is used to refer to forces dependent upon the displacement of a moving member.

The term 'output' applies hereinafter to energy produced by a system.

The term 'periodic system' applies hereinafter to any system wherein at least one component performs a series of steps repeatedly a plurality of times.

The term 'plurality' applies hereinafter to any integer greater than or equal to one.

The term 'useful input' applies hereinafter to the energy consumed by a system in the process of performing the task for which the system is designed.

The term 'useful output' applies hereinafter to energy produced by a system in the process of performing the task for which the system is designed. For example, an elevator raising a cabin of weight 10,000 N containing a man of weight 700 N through 10m produces 107 Id of useful output.

The term 'wear' applies hereinafter to any amortization, depreciation, amortization, wastage or other kinds of wear.

The present invention discloses a cost effective mechanism of reducing the parasitic output of periodic systems. The mechanism comprising modules selected inter lia from a group consisting of at least one moving member acted upon by obstructive forces, the magnitude of said obstructive forces being dependent upon the displacement of said moving member; and a plurality of balancing elements providing balancing forces upon said moving member, said balancing forces at each point along the path of motion of the moving member being of approximately equal magnitude to that of said obstructive forces at said point; such that the parasitic output is reduced to about zero.

The present invention also discloses a mechanism as defined above, wherein the balancing elements comprise a plurality of permanent magnetic elements situated upon the moving member and in its locality so as to provide balancing forces of equal magnitude but in the opposite direction of said obstructive forces, said magnetic elements are selected from ferromagnetic elements, paramagnetic elements, fix magnets, superconducting elements or any combination thereof.

The present invention also discloses a mechanism as defined above, wherein the balancing elements comprise a plurality of permanent magnetic elements situated adjacent to the moving member and in its locality so as to provide balancing forces of equal magnitude but in the opposite direction of said obstructive forces, said magnetic elements are selected from ferromagnetic elements, paramagnetic elements, fix magnets, metals, superconducting elements or any combination thereof.

The present invention also discloses a mechanism as defined above, wherein the moving member moves with linear motion and the obstructive forces act in a direction parallel to its motion.

The present invention also discloses a mechanism as defined above, wherein it additionally comprising a set of pressing fingers which act against a fluid carrying elastic tube such that fluids are forced to flow through said tube; and a set of balancing elements to balance the obstructing forces exerted by said tube upon said peristaltic fingers.

The present invention also discloses a method of reducing the parasitic output of periodic systems. The method comprising steps of obtaining a force-displacement profile that is the forces of at least one moving member acted upon by obstructive forces; and, providing magnetic balancing forces at each point along the path of the moving member, said balancing forces being of approximately equal magnitude to the obstructive forces but acting in the opposite direction; of said obstructive forces at said point, thereby reducing the parasitic output to about zero. The present invention also discloses a method as defined above, wherein the method additionally comprising steps of providing a plurality of balancing elements, a plurality of magnetic elements selected from ferromagnetic elements, paramagnetic elements, superconducting elements or any combination thereof; calculating a configuration of said elements which provides balancing forces matching a predetermined profile; and situating said balancing elements in positions upon said moving member and in its locality as calculated. The present invention also discloses a method as defined above, wherein the method additionally comprising step of providing a moving member that moves with linear motion with obstructive forces parallel to its motion and providing balancing forces in a direction parallel to the motion of said moving member.

The present invention also discloses a method as defined above, wherein the method additionally comprising step of providing a set of peristaltic pressing-fingers which act against a fluid carrying tube such that the flow of fluids through said tube are controlled; and providing balancing elements to balance the obstructing forces exerted by the tube upon the pressing- fingers.

The present invention also discloses method for minimizing scales and sizes of periodic systems in a mechanism as defined in any of the above.

The present invention also discloses a method as defined above, wherein the method is characterized by performing approximately zero work against said obstructive forces.

The present invention also discloses a method of reducing mass of moving member in periodic systems in mechanisms as defined in any of the above.

It is according to one embodiment of the present invention to disclose a mechanism as defined in any of the above, wherein the moving member moves with linear motion and the obstructive forces act in a direction parallel to its motion.

It is according to another embodiment of the present invention to disclose a mechanism as defined in any of the above, which additionally comprising a set of pressing fingers which act against a fluid-carrying flexible tube, such that fluids are forced to flow through said tube; and, a set of balancing elements to balance the obstructing forces exerted by said tube upon said peristaltic fingers.

It is according to another embodiment of the present invention to teach a method additionally providing a set of peristaltic fingers which act against a fluid carrying tube such that the flow of fluids through said tube are controlled; and providing balancing elements to balance the obstructing forces exerted by the tube upon the fingers.

Reference is now made to figure 5 representing the force-displacement profile mapping the force needed to squeeze a silicon tube containing water at a range of pressures. This profile describes the obstructive forces (parasitic forces) acting upon a peristaltic finger of an infusion pump while it squeezes the tube and it is used to calculate the configuration magnetic elements used as balancing elements in the system.

The drug delivery set chosen for the test was designed to reduce the influence of dynamic flow effects and was comprising of a silicon tube. To further eliminate the dynamic flow effects on the force measured, the silicon tube was filled with water and corked on both sides.

The finger engaged with tube at a displacement of approximately 1 mm at the point marked 1. The build up of force is approximately linear, up to a displacement of approximately 4.5 mm, 2, at which point the two sides of the tube touch each other. After that point force build up vs. distance is still linear but steeper. The build up of force is mainly influenced by the silicon tube then by the pressure of the fluid.

It was found that to achieve a positive and reliable shut off of the drug flow, the tube must be squeezed more then 3.5 mm with a force of up to 0.6 kg. It is therefore recommended that the balancing forces should not exceed approximately 0.7 kg in order to minimize harm to the silicon tube as well as to minimize energy consumption through the disengagement function of the electric motor.

Claims

1. A mechanism of reducing the parasitic output of periodic systems comprising; a. at least one moving member acted upon by obstructive forces, the magnitude of said obstructive forces being dependent upon the displacement of said moving member; and b. a plurality of balancing elements providing balancing forces upon said moving member, said balancing forces at each point along the path of motion of the moving member being of approximately equal magnitude to that of said obstructive forces at said point; such that the parasitic output is reduced to about zero.

2. The mechanism according to claim 1, wherein said balancing elements comprise a plurality of permanent magnetic elements situated upon the moving member and in its locality so as to provide balancing forces of equal magnitude but in the opposite direction of said obstructive forces, said magnetic elements are selected from ferromagnetic elements, paramagnetic elements, fix magnets, superconducting elements or any combination thereof.

3. The mechanism according to claim 1, wherein said balancing elements comprise a plurality of permanent magnetic elements situated adjacent to the moving member and in its locality so as to provide balancing forces of equal magnitude but in the opposite direction of said obstructive forces, said magnetic elements are selected from ferromagnetic elements, paramagnetic elements, fix magnets, metals, superconducting elements or any combination thereof.

4. The mechanism according to claim 1, wherein the moving member moves with linear motion and the obstructive forces act in a direction parallel to its motion.

5. The mechanism according to claim 1, additionally comprising a. a set of pressing fingers which act against a fluid carrying elastic tube such that fluids are forced to flow through said tube; and, b. a set of balancing elements to balance the obstructing forces exerted by said tube upon said peristaltic fingers.

6. A method of reducing the parasitic output of periodic systems comprising; a. obtaining a force-displacement profile that is the forces of at least one moving member acted upon by obstructive forces; and, b. providing magnetic balancing forces at each point along the path of the moving member, said balancing forces being of approximately equal magnitude to the obstructive forces but acting in the opposite direction; of said obstructive forces at said point; thereby reducing the parasitic output to about zero.

7. The method according to claim 6, additionally comprising: a. providing a plurality of balancing elements, a plurality of magnetic elements selected from ferromagnetic elements, paramagnetic elements, superconducting elements or any combination thereof; b. calculating a configuration of said elements which provides balancing forces matching a predetermined profile; c. situating said balancing elements in positions upon said moving member and in its locality as calculated.

8. The method according to claim 6, additionally providing a moving member that moves with linear motion with obstructive forces parallel to its motion and providing balancing forces in a direction parallel to the motion of said moving member.

9. The method according to claim 6, additionally providing a set of peristaltic pressing- fmgers which act against a fluid carrying tube such that the flow of fluids through said tube are controlled; and providing balancing elements to balance the obstructing forces exerted by the tube upon the pressing-fingers.

10. A method of minimizing scales and sizes of periodic systems as defined in claim 6 or in any of its dependent claims.

11. A method of balancing periodic systems as defined in claim 6 or in any of its dependent claims, characterized by performing approximately zero work against said obstructive forces.

12. A method of reduces mass of moving member in periodic systems as defined in claim 6 or in any of its dependent claims.