US 3491602 A
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Description (OCR text may contain errors)
;Jan.27, 1970 ,R.w.NEw 3,491,602
SWITCH ACTUATING APPARATUS Filed Jan. 25, 1968 2 Sheets-Sheet l I 10 \v 411 PH? m, i
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SWITCH VAC'I'UAITING APPARATUS 2 Sheets-Sheet 2 Filed Jan. 25, 1968 Russ/5L W :NEW
Arrazwsrs United States Patent 3,491,602 SWITCH ACTUATING APPARATUS Russel W. New, Dallas, Tex., assignor to Meter-All Mfg. Co., Inc., Dallas, Tex., a corporation of Texas Filed Jan. 25, 1968, Ser. No. 700,581 Int. Cl. F16h 25/12, 25/16; F1611 11/04 I U.S. CI. 74-56 6 Claims ABSTRACT OF THE DISCLOSURE A switch actuating cam is rotated on a shaft through a positive clutch. A spring resists the rotation of the shaft through a slipping clutch. When the posrtrve clutch is disengaged, the spring will return the cam to its original position through the slipping clutch.
This invention relates to apparatus for actuating a switch and, in particular, to such apparatus that employs a rotating cam to actuate the switch.
When a rotating cam is used to actuate a sw1tch, 1t is often important that the position of the cam relatrve to the switch actuator or actuating arm be the same at the beginning of each cycle of operation. For example, in the control system of an automatic liquid dispensing machine, such as a coin-operated gasoline pump, a cam may be used to actuate a switch each time a quantity of liquid is dispensed that corresponds to a preselected monetary amount. This is usually done by mounting the switch actuating cam on a shaft driven by the computer that calculates the monetary amount of liquid dispensed. Each time the switch is actuated, the credit established in the pump control system by the purchaser is reduced by the preselected monetary amount.
For example, the control system may be set to reecive twenty-five and fifty cent pieces. For each twenty-five cents deposited, a credit of twenty-five cents is established in the control system. A switch is arranged to be actuated by a cam driven by the computer output shaft for each twenty-five cents worth of gasoline dispensed. Each time the switch is actuated, it erases one twenty-five cent credit from the control system. When all of the credit is erased or debited, the pump shuts down. Therefore, the cam that actuates the credit erase switch stops in the same position relative to the switch actuator at the end of each dispensing operation.
Most coin-operated gasoline pumps, however, can be and usually are operated manually part of the time. During manual operation, the credit erase switch cam continues to be rotated by the output shaft of the computer. During manual operation, sales in amounts other than multiples of twenty-five cents are made. Therefore, the position of the credit erase switch cam relative to the switch will not be known when the time comes to switch the pump to coin operation. The usual practice when switching to coin operation is to buy a quarters worth of gasoline and pump it out into a can until the pump shuts down. The pump may dispense anywhere from one cent to twenty-five cents worth of gasoline, 'but the credit erase switch cam is now positioned to give the next customer the full amount of his purchase.
It is an object of this invention to provide apparatus for actuating a switch with a rotating cam that returns the cam to the same position relative to the switch actuator after each operation of the apparatus.
It is another object of this invention to provide apparatus for actuating a switch with a rotating ca-m driven by a purchase registering computer that returns the cam to the same position relative to the switch actuator after each purchase regardless of the amount of the purchase.
It is a further object of this invention to provide apparatus for actuating a switch with a cam that can be used on a combination manual and coin-operated liquid dispensing machine, such as a gasoline pump, wherein the switch actuating cam will be returned to the same position relative to the switch actuator after each operation, whether manual or coin-operated.
These and other objects, advantages, and features of this invention will be apparent to those skilled in the art from a consideration of this specification including the appended claims and attached drawings.
The invention will now be described in detail in connection with the attached drawings in which,
FIGURE 1 is a plan view of the preferred embodiment of the switch actuating apparatus of this invention being driven by the output shaft of a gasoline pump computer and actuated by the on-off switch shaft of the gasoline P p;
FIGURE 2 is a side view of an alternate embodiment of the power portion of the cam reset mechanism of the apparatus;
FIGURE 3 is an isometric view of the power portion of the cam reset mechanism of the apparatus of FIG- URE 1;
FIGURE 4 is a cross sectional view of the apparatus of FIGURE 1 with the clutch between the computer and the actuating cam shaft disengaged;
FIGURES 5 and 6 are views taken along line 5-5 of FIGURE 1 with the switch actuating cam in two different positions relative to the switch; and
FIGURE 7 is a view in elevation of the apparatus of FIGURE 1 arranged to be actuated by the reset mechanism of the gasoline pump.
The apparatus is located in housing 10, which is adapted to be mounted on a gasoline pump adjacent output shaft 11 of the computer of the pump. The end of output shaft 11, as shown in the drawings, is splined to provide teeth that mesh with gear 12. Usually, output shaft 11 rotates one time for each ten cents worth of liquid dispensed. Therefore, if the apparatus of this invention is to actuate the switch for every twenty-five cents worth of liquid dispensed, the gear ratio between gear 12 and shaft 11 should be two and one-half to one.
Gear 12 is mounted on one end of shaft 13, which extends through the side wall of housing 10. Shaft 13 is supported for rotation by bushing 14, which is threadedly connected in the side wall of housing 10.
Mounted inside housing 10 is switch 15. It has a switch actuating arm or actuator 16. The switch is supported inside housing 10 by L-shaped bracket 17. Positioned adjacent switch 15 is first or cam shaft 20, which is rotatably supported by L-shaped bracket 18 and bushing 21.
Cam means are mounted on shaft 20 for actuating switch 15, when the shaft is rotated in one direction. The cam means includes disc 22 and projection 23 located on the periphery of the disc to engage actuator 16 and actuate the switch with each revolution of disc 22 in the said one direction. Set screw 32 holds cam disc 22 against rotation relative to the shaft.
Cam shaft 20 is positioned with its longitudinal axis in alignment with the longitudinal axis of shaft 13 which we shall refer to henceforth as the second or drive shaft. Both shafts are hollow and elongated guide pin 24 extends into the central opening of both shafts to help hold the shafts in alignment. The outer ends of both first shaft 20 and second shaft 13 are tapped to receive machine screws 25. These screws hold guide rod 24 in position in the central openings of both shafts.
Means are provided for rotating cam shaft 20 in one direction, when output shaft 11 of the computer is being rotated as gasoline is being dispensed, and which releases shaft 20 for rotation in the opposite direction when the gasoline pump is not operating. In the embodiment shown, first clutch means are provided for this purpose. The first clutch means includes discs 30 and 31 mounted on the adjacent ends of shafts 20 and 13, respectively. The adjacent surfaces of discs 30 and 31 have radially extending notches that provide engaging teeth for transmitting torque from one disc to the other, when the two discs are in engagement. Shaft 20 is held against longitudinal movement to the left, as viewed in the drawings, by cam disc 22 and bushing 21. The shaft is held against axial longitudinal movement to the right, as viewed in the drawings, by collar 33, which is tixed on the shaft by set screw 34.
Drive shaft 13, however, is free to move axially through bushing 14. The shaft is urged to the left, as viewed in the drawings, by coil spring 36, which is located between a side wall of the housing and first clutch disc 31. Coil spring 36 then urges clutch disc 31 into engagement with clutch disc 30 on shaft 20. The clutch discs are moved out of engagement by lever 38. This lever is generally Z- shaped and is mounted for pivotal movement around pin 39. It has upper extension 40, which engages gear 12, and lower extension 41, which is engaged by rod 42. Rod 42 is operated by the pump switch, which the customer operates to turn the pump on and off. When the pump is turned off cam rod 42 will move the upper end of lever 38 to the right, moving gear 12 to the right and first clutch disc 31 out of engagement with clutch disc 30. When the pump is turned on to deliver gasoline, rod cam 42 is moved down, allowing lever 38 to pivot to the left as spring 36 moves clutch disc 31 into engagement with clutch disc 30, establishing a torque transmitting connection between the drive shaft and the cam shaft.
An alternate arrangement for moving the clutch discs out of engagement is shown in FIGURE 7. Here shaft 70 of the pump reset mechanism provides the power. Lever 71 is pivotally attached at .one end to shaft 70 by a clamp 72. The other end of the lever engages gear 12 (shaft 11 is not shown). Plate 73, which is attached to housing 10, has a notch or opening (not shown) cut in it through which lever 71 extends. The side of the opening or the bottom of the notch, as the case may be, engages the lever and acts as a fulcrum around which the lever pivots to move gear 12 away from the housing to disengage to clutch plates as the reset shaft is rotated counterclockwise. The linkage in the pump and computer usually is arranged to require the computer to be reset, each time the pump switch has been turned off, before the pump can be turned on again.
Means are provided for rotating the cam shaft in a direction opposite to that in which it is rotated to actuate the switch, when the first clutch is engaged, and stop means are provided to limit the amount the shaft can be rotated in said opposite direction to thereby return the cam means to the same position relative to the switch actuator after each operation of the apparatus. In the embodiment shown, a cam reset member comprising disc 44 is located on the cam shaft between cam disc 22 and first clutch plate 30. The disc is free to rotate relative to the cam shaft. On opposite sides of disc 44 are clutch plates 45 and 46. Pressure plate 47 and coil spring 48 are located between clutch plate 45 and cam disc 22. Since the clutch plates, the reset disc, and the pressure plate are free to move axially along the cam shaft, coil spring 48 holds them in engagement with each other and with clutch disc 30.
Means are provided to exert a force on the reset member urging it to rotate in the opposite direction from which shaft 20 is rotated, when the pump is operating and the apparatus is actuating switch 15. In the embodirnent shown, in FIGURES 1, 3 and 4 an elongated strip 50 of spring material is formed into coil 51 and mounted for rotation on shaft 52. End 53 of strip 50 is attached to reset member 44 so that rotation of the member with shaft 20 unwinds coil 51 and winds the strip around the reset member. Due to the way it is made, the strip resists being unwound. It wants to return end 53 to the coil and as a result, exerts a constant force urging the reset member to rotate in the opposite direction from that in which it is rotated by shaft 26. Spring elements of this type are described by F. A. Votta, Jr., in a paper published in the Transactions of the ASME for May, 1952. Such springs can be purchased from Hunter Spring Company, a division of Ametek, Inc., Hatfield, Pa.
Spring strip 50 exerts a constant force on reset member 44. If the torque transmitting ability of the second clutch, made up clutch plates 45 and 46 etc., is sufiicient to cause reset member 44 to overcome the spring force of coil 51 then it would continue to do so as shaft 20 is rotated. Therefore, bracket 60 is mounted on housing 10 and provided with slot 61 through which strip 50 passes. The upper end of strip 50 is narrower than the remainder of the strip. Slot 61 is not as wide as the remainder of the strip, so shoulder 62, formed at the change in width in the strip, will engage bracket 60 and limit the length of strip that can be wrapped around reset member 44. If a conventional coil spring was employed for this purpose, it would have a spring rate and thus the force it would exert as it was extended by the rotation of reset member 44 would increase. With this arrangement, the clutch could be arranged to slip, when reset member 44 has been rotated the desired distance and a given force is being exerted by the spring. In this embodiment, however, the torque transmitting ability of the second clutch is more than enough to overcome the spring force of strip- 50, and, therefore, it slips only because stop bracket 60 limits the amount of strip that can be uncoiled. When the first clutch is disengaged by lever 38, the clutch will transmit from the reset member to ciutch disc 30' of the first plate the torque imposed on reset member by strip 56. This torque will rotate shaft 20 in the opposite direction from which it is rotated by drive shaft 13 causing cam disc 32 with its projection 23 to rotate in the same opposite direction.
An alternate arrangement for providing power to rotate the cam shaft and cam disc is shown in FIGURE 2. Here metal strip is coiled around disc 81, which is mounted for rotation around shaft 82. One end of the strip is attached to disc 81 and the other to reset member 44 so the strip is wound around the reset member in the opposite direction. To limit the rotation of reset member 44 to just over one revolution, pawl 83 is located to engage notch 84 in the disc. Initially the notch is closed by the strip itself.
Stop means are provided to limit the distance cam disc 22 can be rotated in the opposite direction so that it will be rotated back to the same position relative to switch actuator 16 after each operation of the apparatus. In the embodiment shown, projection 23 engages the end of switch actuator 16 and stops the backward rotation of the cam disc as shown in FIGURE 6. Since projection 23 may stop in the position shown in FIGURE 5, reset cam 44 preferably rotates with shaft 20 more than one revolution before shoulder 62 on the strip engage top bracket 69. This will insure that the reset member and cam disc 22 will be rotated in the opposite direction far enough to return it to the position shown in FIGURE 6, when the first clutch means is disconnected.
To avoid any backlash on the reset of the cam, i.e., any tendency of actuator 16 to move toward the outer end of the projection, the pivot point of the actuator should be level with the top of the cam disc 22 so that the end of the actuator and the sides of the projection are square with each other when they engage, as shown in FIGURE 6.
In the operation of the embodiment shown in FIG- URES 1, 3 and 4, when the attendant turns the pump on and lifts the nozzle from its resting place on the pump, cam 42 will allow lever 38 to pivot to the left and spring 36 to move cam disc 31 of the first clutch into engagement with clutch disc 30. This provides a torque transmitting connection between cam shaft 20 and drive shaft 13. Gasoline is then dispensed causing shaft 11 in the computer head to rotate gear 12 and in turn, the two shafts and projection 23 will actuate switch 15 with each revolution of shaft 20. This action will also cause reset member 44 to rotate something more than one revolution, pulling strip 50 from coil 51 until stop bracket 60 prevents any further rotation of reset member 44. Clutch plates 45 and 46 will then slip. After the attendant delivers the amount of gas purchased, he will cut off the pump and hang up the hose. Cam 42 will then move lever 38 to the right disengaging clutch discs 30 and 31. Strip 50 will tend to recoil around coil 51 and rotate reset cam 44 and, through clutch plates 45 and 46, shaft in the opposite direction. Shaft 20 and cam disc 22 will rotate in the opposite direction until projection 23 engages actuator 16 of switch 15. This may be anywhere from one degree to 359 degrees depending on where the projection is relative to the actuator, when the first clutch is disengaged. Wherever it is, it will be returned to the same position relative to the switch actuator and be ready for the pump to be switched to coin operation at any time.
Equipping the apparatus with the spring strip and stop of FIGURE 2 would not change the operation as described above except as to the specific stop means. Using the reset shaft and the mechanism of FIGURE 7 would affect only the point of time in the operation that the switch cam is reset.
From the foregoing, it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus and structure.
It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.
As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.
The invention having been described, what is claimed 1. Apparatus for actuating a switch comprising a cam shaft positioned adjacent the switch, cam means mounted on the shaft to actuate the switch as the shaft is rotated in one direction, means for rotating the cam shaft in said one direction to actuate the switch the desired number of times and which releases the shaft for rotation in the opposite direction when the switch has been actuated the desired number of times, stop means for limiting the rotation of the shaft in said opposite direction, and means for rotating the shaft in said opposite direction to the extent permitted by the stop means when the shaft is released for said rotation to thereby return the cam means to the same position relative to the switch after each operation of the switch actuating apparatus.
2. The apparatus of claim 1 in which the means for rotating the shaft in the opposite direction includes a re set member rotatably mounted on the shaft, means for exerting a resilient force on the reset member resisting its rotation with the shaft in the direction the shaft is rotated to actuate the switch, and means for transmitting sufficient torque to the reset member from the shaft to rotate the reset member more than one revolution and from the reset member to the shaft to rotate the shaft in the opposite direction to the extent permitted by the stop means when the shaft is released for said rotation,
3. The switch mechanism of claim 2 in which the shaft is connected to the reset member through a clutch which slips after the reset member has rotated more than one revolution.
4. The switch mechanism of claim 3 in which the means exerting a force on the reset member resisting its rotation with the shaft is a strip of flat spring material formed into a coil with one end attached to the reset member, means for mounting the coil for rotation to permit the reset member to unwind the coil as it is rotated by the shaft when the switch mechanism is operating, and means for limiting the distance the strip can be unwound from the coil to stop the rotation of the reset member after it has rotated at least one revolution With the shaft.
5. The switch mechanism of claim 1 in which the cam means includes a cam member mounted on the shaft for rotation with the shaft and having a projection for actuatin g the switch with each revolution of the shaft.
6. Apparatus for actuating the actuating arm of a switch, comprising, a cam shaft adjacent the actuating arm of the switch, a cam member mounted on the cam shaft for rotation by the shaft and provided with a projection to engage the actuating arm of the switch and actuate the switch with each rotation of the shaft when said shaft is rotated in one direction, said actuating arrn being positioned to engage the projection on the cam member, when the shaft is rotated in the opposite direction, and hold the cam member and shaft against further rotation in that direction, means for rotating the cam shaft in said switch actuating direction, first clutch means for connecting the cam shaft and the shaft rotating means when the clutch means is engaged and for disconnecting the shaft and the shaft rotating means when the clutch means is disengaged, and a reset assembly including a reset member rotatably mounted on the shaft, means for exerting a force on the reset member urging it to rotate in the opposite direction from that of the shaft when it is actuating the switch, and second clutch means for transmitting from the shaft to the reset member sufiicient torque to rotate the reset member more than one revolution after which the second clutch means slips whereby the force exerting means will rotate the reset member and through the second clutch means the shaft backward, when the first clutch means is disengaged, until the projection on the cam member engages the actuating arm of the switch to thereby return the cam member to the same position relative to the switch after each operation of the mechanism.
References Cited UNITED STATES PATENTS 692,783 2/1902 Dyre 74-55 1,596,793 8/1926 Bishop. 2,462,363 2/1949 Cook 192-67 2,788,850 4/ 1957 Levenberger 74-567 3,151,704 10/1964 Clarke. 3,236,106 2/1966 Krupp et al 74-567 3,375,814 4/1968 Hamman.
FRED C MATTERN, JR., Primary Examiner W. S. RATLIFF, JR., Assistant Examiner US. Cl. X.R.