US3626117A

US3626117A - Escapement and timer utilizing same

Info

Publication number: US3626117A
Application number: US792578*A
Authority: US
Inventors: Richard W Stafford
Original assignee: PR Mallory and Co Inc
Current assignee: Duracell Inc USA
Priority date: 1969-01-21
Filing date: 1969-01-21
Publication date: 1971-12-07
Anticipated expiration: 1988-12-07
Also published as: GB1235639A

Abstract

An escapement means for a timer utilizes a constant force coil spring such that the minimum force required to activate a ratchet means coupled to the timer cam stack can be set and maintained during the operation of the timer.

Description

United States Patent 3,626,1 17

[72] Inventor Richard W. Stafford [56] References Cited 1 N saygna, 1nd. UNITED STATES PATENTS 1 [2 P 2,868,026 1/1959 Finehout et al... 74/125 [22] Filed Jan. 21, 1969 3,115,785 12/1963 Simmons 74/125 [45] Pmmed $1971 3 417 631 12/1968 M rr 1 1 74/125 [73] Assignee P. R. Mallory 8: Co. Inc. u ay e Indianapolis, Ind. Primary Examiner-Milton Kaufman Art0rneysRichard I-I. Childress, Robert F. Meyer and Henry W. Cummings [54] ESCAPEMENT AND TIMER UTILIZING SAME 11 Claims, 3 Drawing Figs.

[52] U.S. Cl 200/38 F,

74/125 ABSTRACT: An escapement means for a timer utilizes a con- [51] Int. Cl "01h 7/08 stant force coil spring such that the minimum force required [50] Field of Search 74/3.52, to activate a ratchet means coupled to the timer cam stack can 3.5, 3.54, 125, I22; 200/38 A be set and maintained during the operation of the timer.

' PATENTEDDEE Hen 3.626117 SHEET 1 OF 2 lNVENTOR RICHARD W. STAFFORD ATTORNEY PATENTEBUEB ml 1626.117

SHEET 2 OF 2' INVENTOR FIG 5 RICHARD w. STAFFORD kmyw w ATTORNEY ESCAPEMENT AND TIMER UTILIZING SAME Control timers, sometimes known as sequential timers, are known and have received commercial acceptance in the control of the sequence of operation used to actuate electrical appliances such as washing machines, dishwashers, dryers and the like. As refinements are introduced in the electric appliance field, thereby making the appliance more commercially acceptable by the public at large, the need arises to modify the presently available control timer so as to provide a control timer capable of actuating increased numbers of electrical circuitries operatively associated with the appliance. However, it is desired that the control timer be physically small and compact. It is seen that the need arises for a more accurate, simple, efficient and effective sequential timer capable of handling increased numbers of electrical circuits.

Many of such timers utilize an escapement means for advancing the timer at predetermined intervals in a step by step manner in accordance witha programmed sequence. For the most part, such escapement means includes a spring means to force a drive means into engagement with a ratchet means coupled to the cam stack. For the most part, such springs normally had an increasing spring rate; that is, the more the spring was deflected, the more force was built up. With such a spring, excessive force was built up in the spring. Such excessive force was not only wasteful, but caused damage to the drive cam and the drive lever follower which forces the drive means into engagement with the ratchet means.

The present invention utilizes a constant force energy storage means such that the required force can be set by the design of the storage means. That is, knowing the force needed to engage the drive means with the ratchet means of the escapement, and the amount of travel of the drive means, the energy storage means can be designed to give a constant force, or putting it in the terms of a spring, the energy storage means gives a zero spring rate.

The escapement of the present invention also includes a drive pawl, a stop pawl and no-back pawls which very efficiently advance a cam stack in a step by step manner. The escapement is used in a timer having subinterval means to control sequences of operation other than that programmed by the cam stack. The timer as a whole is small, compact and accurate with a great degree of efficiency.

In addition, the timer uses a line switch to disengage the electrical power to the control'switches through a push-pull of a shaft carrying the cam stack wherein there is a shaft positioning means carried by the cam stack.

It is, therefore, an object of the present invention to provide an escapement for a timer utilizing energy storage means which does not store excessive energy.

Another object of the invention is to provide an escapement means for a timer utilizing an energy storage means of constant force which can be set for the minimum force required to engage the drive means with the cam stack of the timer.

Another object of the invention is to provide an escapement for a timer utilizing a constant force spring.

Still another object of the invention is to provide an escapement for a timer utilizing a constant force spring having one end thereof pivotally connected to a stationary point, the other end pivotally connected to the drive means engaging the cam stack of the timer.

A further object of the invention is to provide an escapement means for a timer which is compact and eflicient in operation.

Still another object of the invention is to provide a timer utilizing an escapement means for a timer wherein the timer has subinterval means.

Yet another object of the invention is to provide a shaft locating means for a push-pull of the shaft wherein the locating means is coupled to the cam stack of the timer.

Another object of the invention is to provide a timer utilizing an escapement means having a constant force energy storage means, the timer including subinterval means, the timer being compact, accurate and efi'rcient in operation.

These and other objects and the nature thereof will become apparent from the following description given in conjunction with the accompanying drawings wherein like reference numbers described elements of a similar function.

In the drawings:

FIG. 1 is an exploded view of the timer showing the relationship of its parts;

FIGS..2 and 3 are top views of the front plate of the timer showing the escapement and cooperating parts thereof.

Generally speaking, the objects of the invention are accomplished by providing an escapement means for advancing a cam stack of a timer at predetermined intervals, the escapement means including a constant force energy storage ans a drive means engaging ratchet means coupled to the cam stack, means deflecting the energy storage means so as to store energy therein, and means releasing the energy storage means, movement of the energy storage means after release forcing the drive means into engagement with the ratchet means.

The escapement is used in a timer which includes subinterval means for providing additional sequences of operation other than those programmed on the cam stack. Additionally, there is a shaft locating means that limits the push-pull" movement of the shaft to two positions, the locating means being connected to the cam stack.

Referring now to the drawings, and more particularly to FIG. I the component parts of a timer including its escapement are shown. The housing for the component parts, excepting the motor 10, is formed by connecting together front plate 12, rear plate 14, a top cover 16 and a side cover 18. A motor support bearing 20 is journaled in aperture 22 of the front plate 12. A drive cam 24 is coupled to the support bearing 20 through shaft 26. A motor mounting cover 28, fabricated from an electrically insulative material such as plastic, fits over drive cam 24. Motor 10 is coupled to drive cam 24 through bushing 30, bushing 30 having teeth 32 adapted to mate pinion 34 of the motor. Although not necessary in the practice of the invention, motor 10 is of the synchronous motor type. The motor 10 and the housing 28 are connected to front plate 12 through mounting screws 36 and 36'.

A first subinterval driving means 38, which includes a lever 40 and a pawl 41 is trapped from axial movement between motor mounting cover 28 and front plate 12 and is rotationally held by screw 36'. Pawl 41 is responsive to movement of drive cam 24 through peripheral rise and fall contours 39. The subinterval actuator means 42, which is responsive to movement of the lever 40, includes a post 42', post 42' being carried in slot 43 formed in the front plate. A drive spring 44 which biases the drive means of the escapement is held within motor mounting cover 28 through a notch or other receiving means (not shown).

A second subinterval means 33 is carried by motor mounting cover 28. Such subinterval means includes a contact blade 35 connected to the cover 28 at one end through rivet 37, electrical terminal 31 disposed between the blade and the cover 28, and electrical terminal 29 which is connected to cover 28 through rivet 27. Blade 35 carries an electrical contact 25 which is adapted to open and close an electrical circuit through engagement with rivet 27. Blade 25 is responsive to movement of drive cam 24 through rise and fall contour or lobe 23.

A cam stack 46, carried by a shaft 48, is rotatably carried between front plate 12 and rear plate 14, the shaft 48 being rotatably journaled in apertures 50 and 52 through bushing 54 and support bearing 56 respectively. Cam stack 46 includes a plurality of cams 58. Also included as part of the cam stack is a ratchet means 60 which, although not necessary, may be integrally connected to the cams. In the present timer, the cams tack which includes the cam 58 and the ratchet means 60 is molded as a single unit. Switch means 62 and 64 are located diametrically opposite each other adjacent the periphery of the earns 58 such that the switch means are responsive to the intelligence of the cams. Electrical terminals 66 are integrally formed with the switch means 62 and 64 and are carried by terminal block 68 and buss block 70. Bussing means 72 conducts current from one terminal to the other terminal to which the bussing means is connected. As actuator means 74 biases contact blade 76 to open and close contacts 78 to shut off electrical power to the control switches when the cam stack is manually set to a desired program, thus providing a line switch for the timer.

Actuator means 74 is actuated by actuator means 80 which includes a chamfered ring 82 fixedly connected to shaft 48 and which has a web portion 84 adapted to mate diametrically opposed notches 86 of the hub 88 of the cam stack 46. Bearing 56 is heat staked to the hub 88, the bearing being fitted into notches 86 through tabs 90. Shaft 48 is free to move axially with respect to the bearing 56. A shaft locating means 92 which includes a clip 94 assures that the shaft 48 can be axially positioned in only one of two positions. This is accomplished by providing a slot 96 which is adapted to seat in one of the two

grooves

98 and 100 of the knurled portion of the shaft 48. Axial movement of the actuator means 80 biases actuator means 74 through ram 75 to deflect contact blade 76 so as to open and close contact 78, the movement of the actuator means 80 being limited by the movement of the shaft 48 through the clip 94 engaging either groove 98 or groove 100. The axial and rotational movement of the shaft to set the desired programming sequence of cams 58 is facilitated through a suitable knob 48'.

It is noted that the regulating means 92 which determines the location of the shaft 84 is connected to the cam stack 46. Prior timers using a line switch to deactivate the control switches had the axial positioning means connected to one of the housing members such as rear plate 14. With the present arrangement, if the rear plate needs to be removed, the axial positioning means need not be disturbed.

Disposed between the cam stack 46 and front plate 12 there is shown drive lever 104 and drive means 106. DRive lever 104 and drive cam 24 are included as a deflecting and release means 108 for deflecting the constant energy storage means. Referring particularly to FIGS. 1, 2 and 3, the energy storage means 110 includes a coil spring 112 which is pivotally connected at one end to a fixed point such as post 114 of motor mounting cover 28 and at the other end pivotally connected to a movable point such as post 116 formed as part of drive lever 104. The drive cam 24 includes a slowly rising contour 118 followed by a sharp fall contour 120. Rotation of cam 24 through motor causes deflection of coil spring 112 through post 138 being responsive to movement of the rise and fall contour of the cam such that energy is stored in the spring. Upon reaching the fall contour 120, the energy in coil spring 112 is released and post 138 drops thus forcing drive lever 104 to pivot in the direction of the fall so as to engage drive means 106 with ratchet means 60 in a manner hereinafter described.

As previously noted, the use of the constant force energy storage means, or as is shown in the present invention, a coil spring having a constant force, permits the present escapement to function in a manner that the drive means 106 will be engaged with the ratchet means 60 at the required force without any excessive force being built into the spring. In prior art escapements, the spring that is used to actuate the drive means is a type of spring wherein the force built up in the spring increases as the spring is displaced. Such a spring would inherently have built into it excessive force. More specifically, in prior art escapements using linear spring forces, there had to be more force generated or available in the stored energy of the spring than is needed to advance the ratchet means to the next step, since the linear rate of force rapidly decreases as the energy is spent. As previously noted, such excessive force not only is wasteful, but in the application of timers, and more particularly the escapement used in timers, would cause excessive wear or damage between the drive lever 104 and the drive cam 24. In addition, the excessive force imposes a higher load requirement from the motor thus unnecessarily shortening the life of the motor. In a constant force spring, however, the same force is available throughout the ratchet advance. Such constant force springs are designed in accordance with the force required and the amount of travel needed. As an example of the design criteria for constant force springs, reference is made to Spring Design and Application, edited by Nicholas P. Chironis, McGraw Hill, 1961.

Returning now to FIG. 1, it is noted that the drive lever 104 is carried by bushing 54 which engages aperture 122. Drive means 106 includes a drive pawl 124, a stop pawl 126, a primary no-back pawl 128 and a secondary no-back pawl 130. Drive pawl 124 is pivotally carried by post 132 included as part of drive lever 104. Stop pawl 126, no-back pawl 128 and secondary no-back pawl 130 are pivotally carried by post 134 which is staked in aperture 136 of front plate 12. Drive pawl 124 engages the teeth of ratchet means 60. No-back pawl 28 holds the ratchet means 60 while the drive lever 104 and drive pawl 124 advance to pick up the next ratchet tooth. Stop pawl 126 limits the amount of advance of the drive pawl 124 and transmits pressure to force the drive pawl 124 against the ratchet means 60. No-back pawl 130 limits the amount of manual reverse torque which can be applied to the timer, where damage can result to the timer cam spring. It should be understood that secondary no-back pawl 130 is an optional feature of the present timer and that it need not be necessarily used. No-

back pawls

128 and 130, and stop pawl 126 are forced against ratchet means 60 through leaf spring 44.

Referring now to FIGS. 1-3, the operation of the timer can be described. After the desired program has been set by the appliance operator, motor 10 drives drive cam 24 counterclockwise to pivot drive lever 104 through post 132, which is biased by rise and fall

contours

118 and 120. As the lever pivots, constant force spring 112 is deflected to store energy therein. The drive means 106 will be disengaged from ratchet means 60 (FIG. 3). When post 138 reaches the fall contour 120, spring 112 is quickly released causing drive lever 106 to reverse its pivotal direction thus causing the drive means 106 to become engaged with ratchet means 60 to advance the ratchet (FIG. 2). Such advance is accomplished by the continued rotation of drive cam 24 through rise contour 118.

As a safety feature, in the case where the drive lever 104 might get hung up," cam surface 140 will force the post 138 along the fall contour 120.

As drive cam 24 rotates, the first and second subinterval means 38 and 33 are also actuated. Subinterval means 33 is actuated. Subinterval means 33 is actuated through lobe 23 in the manner previously described. Subinterval means 38 is actuated through rise and fall contours 39 actuating pawl 41 to thus engage actuator means 42 which biases contact blade 45 through post 42' to open and close contacts 47, the circuit to the components being energized being completed through terminals 49. Such actuation of the subinterval means 38 is allowed to be operative when blade 45 drops on cam 58 of cam stack 46 as shown in FIG. 3. I

Thus there is described an escapement and a timer, one of the features of which is the use of a constant force energy storage means to set the required force necessary to actuate the ratchet means of the escapement thus substantially eliminating excessive energy or force in the system. Such excessive force is not only wasteful but causes damage to the component parts of the escapement, for example, the drive lever and the drive cam of the present escapement.

What is claimed is:

1. A timer comprising:

a. a cam carrying shaft,

b. at least one cam carried by said shaft,

c. switch means responsive to movement of said cams,

d. an escapement means coupling said cams to a motor drive means so as to advance said cams in a step by step manner, said escapement means including a constant force coil spring, a drive means engaging ratchet means coupled to said cams, means deflecting said coil spring so as to store energy therein, and means releasing said coil spring, movement of said coil spring after release forcing said drive means into engagement with said ratchet means, said drive means being spring biased.

2. A timer according to claim 1, wherein said means deflecting said coil spring and means releasing said coil spring includes a cam means coupled to a motor drive means and a drive lever responsive to movement of said cam means.

3. A timer according to claim 2, wherein said cam means includes a slowly rising contour terminating in a sharp fall contour.

4. A timer according to claim 2, wherein said spring is pivotally connected to a stationary point at one end of said coil, the other end pivotally connected to said drive lever.

5. A timer according to claim 2, wherein said drive means includes a drive pawl and a no-back pawl.

6. A timer according to claim 5, wherein said drive means further includes a stop pawl.

7. A timer according to claim 6, wherein said drive means further includes a secondary no-back pawl.

8. A timer according to claim 2, wherein said motor drive means is a synchronous motor.

9. A timer according to claim 1 further including subinterval means responsive to movement of said deflecting means.

10. A timer according to claim 1, including means to axially move said shaft, and locating means coupled to said cam locating such axial movement to two positions.

11. A timer according to claim 10 further including a line switch adapted to open and close electrical contacts in response to said axial movement of said shaft.

s t a a r

Claims

1. A timer comprising: a. a cam carrying shaft, b. at least one cam carried by said shaft, c. switch means responsive to movement of said cams, d. an escapement means coupling said cams to a motor drive means so as to advance said cams in a step by step manner, said escapement means including a constant force coil spring, a drive means engaging ratchet means coupled to said cams, means deflecting said coil spring so as to store energy therein, and means releasing said coil spring, movement of said coil spring after release forcing said drive means into engagement with said ratchet means, said drive means being spring biased.