US3693502A - Cycling mechanism - Google Patents

Abstract

A pressure fluid operated motor moves a predetermined distance in one direction and then a predetermined distance in another direction. The activating pressurized fluid flows through an expansible chamber having a pressure relief valve to the motor. A predetermined volume of fluid must enter the expansible chamber before sufficient pressure is built up to unseat the relief valve and allow pressure fluid to flow to the motor. This results in a time delay between each change in direction of movement of the motor.

Description

United States Patent Smith [451 Sept. 26, 1972 CYCLING MECHANISM FOREIGN PATENTS OR APPLICATIONS Inventor: Charles Smith. York, 379,979 9/1932 Great Britain ..91/219 [73] Assignee: Ams chalmers Manufacturing 443,410 2/1936 Great Britain ..91/219 puny Mllwaukee Primary Examiner-Paul E. Maslousky [22] Filed: Dec. 2, 1970 Attorney-John P. Hines, Robert B. Benson and [211 pp No; 94,446 Charles L. Schwab [57] ABSTRACT U.S. Cl- A pressure operated motor moves a predete 1 91/412 mined distance in one direction and then a predeter- [51] Int. Cl. ..F0ll 1/20, F01] 25/06 mined distance in another direction. The activating [58] Field of Search ..91/219, 245, 218,307, 412, pressurized fluid flows through an expansible chamber 91/275; 92/605 having a pressure relief valve to the motor. A

predetermined volume of fluid must enter the expansi- [56] References Cited ble chamber before sufficient pressure is built up to unseat the relief valve and allow pressure fluid to flow UNITED STATES PATENTS to the motor. This results in a time delay between 3,046,951 7/1962 Freeborn ..91/275 each mange mmmem the 3,186,309 6/1965 Killebrew ..91/412 4 Claims, 2 Drawing Figures CYCLING MECHANISM This invention pertains in general to fluid cycling mechanisms and more particularly to such a mechanism having an intermediate time delay.

Cycling mechanisms are used in many different manufacturing operations such as, for instance, grinding machines and automatic welding machines. The machine is operated in one direction for a predetermined period of time and then comes to a stop. A delay in operation then takes place for a predetermined period of time. After the delay period the machine operates in the opposite or a different direction, and at the end of that stroke an additional time delay takes place.

It is the general object of this invention to provide a cycling mechanism with intermediate time delay which is relatively inexpensive and of simplified construction and operation.

A more specific object of the subject invention is to provide a fluid-operated cycling mechanism wherein the amount of time delay between alternate operations of the fluid motor is adjustable.

An additional object of the subject invention is to provide a fluid-operated cycling mechanism of the hereinbefore described type with means to automatically shift the mechanism control valve at the end of each motor operation to initiate delivery of pressure fluid for the next motor operation in a different direction.

These and other objects of the subject invention will become more fully apparent as the following description is read in light of the attached drawing wherein FIG. 1 is a cross sectional side elevation of a fluidoperated cycling mechanism constructed in accordance with the invention and FIG. 2 is an end view of FIG. 1

Referring to the attached drawing, the cycling mechanism of this invention is shown contained in a single housing generally designated 6. A fluid motor herein shown for purposes of illustration as a piston 7 is reciprocably contained in a cylindrical chamber 8 within the housing 6. The piston 7 divides the cylinder into motor chambers 9 and 11. Piston rods 12 and 13 are connected to opposite ends of the piston 7 andextend without the housing 6. These piston rods provide the connecting means to the element or elements that are to be cycled.

An additional elongated cylindrical chamber generally designated 14 is provided in the housing 6. A free-moving piston 16 is slidably contained within the cylindrical chamber 14 and divides such chamber into a pair of expansible fluid chambers 17 and 18. Means are provided to selectively adjust the extent of movement of the piston 16 in chamber 14. To this end, as hereinshown for purposes of illustration, a pair of stops l9 and 21 are threadably received in internally threaded bores provided through the housing 6 into the expansible chambers 17 and 18. The adjustable stops may be turned in or out in the threaded bores to limit the extent of movement of the piston 16.

A reversing valve is also provided in the housing 6. This reversing valve is composed of a cylindrical chamber 22 having a spool 23 slidably contained therein. The spool 23 is provided with a pair of longitudinally spaced annular lands 24 and 26. A pressure fluid inlet port 27 is connected to the control valve cylinder 22 at a point intermediate the lands 24 and 26. A fluid pressure source in the form of a pump 30 is connected to the inlet port 27. A pair of combination supply and exhaust passages 28 and 29 connect the reversing valve chamber 22 to the expansible chambers 17 and 18 respectively.

Fluid chambers 31 and 32 are provided on opposite ends of the reversing valve chamber 22 in alignment therewith. A reduced portion of the spool 23 extends into each chamber 31 and 32, and each portion is provided with a piston 33 and 34 respectively. The remote ends of pistons 33 and 34 are exposed to pressurized fluid through passageways 36 and 37 connected to the supply port 27. Each of these passageways 36 and 37 is also connected to the system sump by means of passageways 38 and 39 extending without the housing 6. In this instance it is intended that the housing 6 will be submerged in fluid, and, therefore, the exterior of the housing is the system sump. Stoppers 41 and 42 are aligned with the passageways 38 and 39 respectively. Each stopper 41 and 42 is connected respectively to the piston rods 12 and 13 for movement therewith. When a stopper engages the housing at a passageway outlet, that passageway is isolated from the system sump, and an increased pressure occurs in the cylinder chamber 31 or 32 connected to that passageway.

Chamber 18 is connected to chamber 11 in one direction by means of pressure relief valve 43 and in the opposite direction by means of check valve 44. Chamber 17 is connected to chamber 9 in one direction by means of pressure relief valve 46 and in the opposite direction by means of check valve 47. The pressure relief valves 43 and 46 permit pressurized fluid to flow from chambers 18 and 17 into chambers 11 and 9 respectively upon attainment of a predetermined fluid pressure in chambers 18 and 17. When fluid is flowing from chamber 18 to chamber 1 1, fluid is exhausting through check valve 47 from chamber 9 to chamber 17.

The operation of the cycling mechanism is as follows. In the position shown in the drawing, the piston 7 is about to move to the left. Fluid from the supply port 27 passes through the chamber 22 through passageway 29 into expansible chamber 18. Since the piston 16 has moved to the left against the stop 19, fluid will fill the expansible chamber 18 and increase in pressure until it exceeds the predetermined pressure required to unseat the pressure relief valve 43. Fluid then enters the chamber 11 and moves the piston to the left. At the end of the power stroke of piston 7 a stopper 42 will cover the passageway 39. This will cause an increase in pressure to the right of the piston 34 on the right end of the spool 23. As the pressure increases, the spool 23 will 7 move to the left causing the lands 24 and 26 to move to the left of the passageways 28 and 29. Pressure fluid will then pass through chamber 22 and passageway 28 into expansible chamber 17. As the fluid fills expansible chamber 17, the piston 16 will move to the right until it contacts stop 21. At this point the pressure in expansible chamber 17 will increase to the point where it exceeds the pressure required to unseat pressure relief valve 46 and will then enter chamber 9, moving the piston 7 to the right. As the piston 7 moves to the right, fluid in chamber 11 will pass through check valve 44 and expansible chamber 18, passageway 29, and out exhaust port 48. When the piston 7 has reached the end of its stroke to the right, the stopper 41 will close off the passageway 38 causing an increase in pressure to the left of the piston 33 at the left end of spool 23. This will cause the spool to move to the right, and the cycle will repeat itself.

From the above description it can be seen that a very simplified and inexpensive cycling mechanism has been provided. This mechanism permits adjustment of the power stroke as well as adjustment of the time interval between each power stroke.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A pressure fluid operated cycling mechanism having a pressure fluid source and a fluid sump comprising: a reversible fluid motor having a power operating cycle; a cylinder having a piston slidable therein dividing said cylinder into separate expansible fluid chambers; stop means associated with said chambers limiting the extent of movement of said piston; fluid pressure responsive means connecting said motor in pressure fluidcommunication with one of said expansible chambers after said piston has engaged said stop means and the fluid pressure in said one of said chambers has exceeded a predetermined level; a reversing valve having a spool selectively movable to permit and interrupt the flow of fluid to said chambers, opposite sides of said spool being exposed to the same fluid pressure whereby the net fluid force tending to move said spool is zero; and valve spool control means operable to increase the fluid pressure on one side of said spool relative to the other side when said motor has reached the end of an operating cycle to move said spool and interrupt the flow of pressure fluid to said one of said chambers and deliver pressure fluid to the other of said chambers.

2. The cycling mechanism set forth in claim 1 wherein said stop means are adjustable to selectively change the extent of movement of said piston.

3. The cycling mechanism set forth in claim 1 wherein the pressure fluid connected to opposite sides of said spool is also connected to sump and wherein said valve spool control means selectively and altemately interrupts the connection to sump on one side of said spool.

4. The cycling mechanism set forth in claim 3 wherein said reversible fluid motor is a reciprocating fluid motor with oppositely extending piston rods and said valve spool control means is connected to said piston rods.

Claims (4)

1. A pressure fluid operated cycling mechanism having a pressure fluid source and a fluid sump comprising: a reversible fluid motor having a power operating cycle; a cylinder having a piston slidable therein dividing said cylinder into separate expansible fluid chambers; stop means associated with said chambers limiting the extent of movement of said piston; fluid pressure responsive means connecting said motor in pressure fluid communication with one of said expansible chambers after said piston has engaged said stop means and the fluid pressure in said one of said chambers has exceeded a predetermined level; a reversing valve having a spool selectively movable to permit and interrupt the flow of fluid to said chambers, opposite sides of said spool being exposed to the same fluid pressure whereby the net fluid force tending to move said spool is zero; and valve spool control means operable to increase the fluid pressure on one side of said spool relative to the other side when said motor has reached the end of an operating cycle to move said spool and interrupt the flow of pressure fluid to said one of said chambers and deliver pressure fluid to the other of said chambers.

2. The cycling mechanism set forth in claim 1 wherein said stop means are adjustable to selectively change the extent of movement of said piston.

3. The cycling mechanism set forth in claim 1 wherein the pressure fluid connected to opposite sides of said spool is also connected to sump and wherein said valve spool control means selectively and alternately interrupts the connection to sump on one side of said spool.

4. The cycling mechanism set forth in claim 3 wherein said reversible fluid motor is a reciprocating fluid motor with oppositely extending piston rods and said valve spool control means is connected to said piston rods.

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