US2991759A

US2991759A - Cushioning and flow control valve

Info

Publication number: US2991759A
Application number: US29755A
Authority: US
Inventors: John S Pilch
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-05-17
Filing date: 1960-05-17
Publication date: 1961-07-11
Anticipated expiration: 1978-07-11

Description

J. S. PILCH CUSHIONING AND FLOW CONTROL VALVE Filed May 17, 1960 ww@ @Wawy Lv July l1, 1961 United States Patent 2,991,759 CUSHIONING AND FLOW CONTROL VALVE John S. lilch, Ware Machine Works, Inc.,

` P.O. Box '140, Ware, Mass.

Filed May 17, 1960, Ser. No. 29,755 Claims. (Cl. 121-40) This invention relates to a new and improved boom cushioning and flow control valve for hydraulic systems and to a hydraulic system employing said valve and has particular reference to a new and improved valve and hydraulic system for controlling the movement of various mechanisms such as the boom on a hydraulic trencher, the push arms on a hydraulic loader, or any other hydraulic circuit.

An object of the invention is to provide a new and improved valve and hydraulic system of the type set forth which acts as a positive seal when the unit is not in operation to eliminate the load creeping downward, or if the -levers on the main control valve were accidentally port'26 to the down side of the lift cylinder through line moved while the hydraulic pump was not operating, the valve of the present invention will eliminate the possibility of oil escaping from the cylinder in question which would cause the mechanism to drop downward.

Another object is to provide a valve and system of` the type set forth which, when the control valve is moved to lower the load, starts the lowering operation gradually and without a sudden burst of speed.

Another object is to provide a device of the type set forth which cushions the end of the travel of the apparatus.

Other objects and advantages of the invention will be apparent lfrom the following description taken in connection with the accompanying drawing.

Referring lto the drawing: I f

FIG. 1 is a longitudinal sectional view of a hydraulic cylinder embodying the present invention;

' FIG. v2 is a fragmentary sectional view illustrating a step in the operation of the device;

FIG. 3 is a fragmentary sectional view, generally similar to FIG. 2, but illustrating another step in the operation of the device; and

FIG. 4 is a schematic view of a hydraulic system embodyingthe invention.

Referring more particularly to the drawing wherein similar reference characters designate corresponding parts l throughout, the hydraulic system shown in FIG. 4 comprises a main `control valve 10 adapted to receive hydraulic lluid under pressure through hydraulic line 11 and having an outlet 12 connected =by hydraulic line 13 to port 14 on the down side of cylinder 15. Hydraulicline v13 is also connected 'by the line 16 to the port 17 in the end of cylinder 18. Cylinder 18 has the port 19,connected by hydraulic line 20 to the port 21 on control valve 10. Cylinder 18 has the portion 18a with port 18b which is connected by hydraulic line 21 to port 22 `on-the lift side of cylinder 15. l v In cylinder 15 is provided the double acting piston 23 connected to the ram 24.

In port 17 of cylinder 18 is provided the member 2 5 having the pilot orifice 26 as hereinafter described. In f cylinder 18 is provided the cushion timing piston 27 which has the Q ring seal 28 in its periphery.

The piston 18 is provided with the end cap 18e having the extension portion 18a and in end cap 18e` is provided a seat 29 for cushioning valve 30 which is provided at its end adjacent timing piston 27 with ports 31 which are always adapted to be positioned beyond the end of seat 29.

'Cushioning valve 30 has the spring seat portion 32 engaging coil spring 33 which has its opposite end engaging the inner surface of threaded cap 3:4` andfon the side ice Patented `July 11, 1961 of cushioning valve 30 opposite spring seat 32 are prof vided the ports or passages 35.

It will belnoted that the ports 35 are graduated in size and are spaced from each other a considerable distance and these ports could 'be replaced by one long tapered slot in order that the plunger open the proper distance depending upon the volume of fluid being supplied by the pump which eliminates jerky movement of the equipment and assures the elimination of vacuum in the cylinder.

With the present device, as the operator lowers his load, the cushion timing piston 27 is in the position shown in FIG. 1 and as the operator moves the main control valve into hold position, closing oli the lines fromv the cylinder to the oil reservoir there would be a sudden jar if a heavy load on the end of a boom or a loader bucket full of material was stopped suddenly. With the present valve, as the load attempts to come down, this load creates pressure on the -lift side of the lift cylinder forcing fluid through port 19 and through ow control cushioning plunger 30 gradually moving the cushioning timing piston to the left and iluid thenwould flow through 13 and port 14. As this operation continues, oil would beescaping on a graduated scale because of the graduated ports or orifices 35 and as soon as the cushion timing piston 27 has traveled to the Ifull extent on theleft;2 the plunger would be closed as shown in FIG, 3, and the boom could not `travel downward any more. It can =be clearly seen that with the use of this valve, after theV oper@ ator has manually closed oif the main control valve'10, the trencher boom or loader arms can travel downward a a predetermined distance and at a graduated pace and be automatically brought to a smooth stop. The valve of the present invention actsV as a positive seal by preventing Huid passing and/ or leaking from the lift side lof `the lift cylinder through ythe main control valve 10 and this prevents the trencher -boom from creeping downward while the trencher is not -inruse, and even more importantly, acts as a safety device by preventing the boom from dropping if any person moves the control handle of control valve 10 while thetrencheris not in use. The operation of the valve as a positive seal is as follows y' At all times, when the main control valve s closed, the flow vcontrol plungery 30 is closed against seatv 2 9, see FIG. 3, bypressure exerted from the lift side of the -li-ft cylinder through line 21 and port 181;. This prevents oil passing out of the lift side of the lift cylinder if the main control valve leaks or is opened accidentally while the trencher is not running. l

The ow control plunger 30 is unseated to connect po'rt 22.with the main control valve only when hydraulic pressure from the pump is applied -to thedown side fof the lift cylinder 15. This pressure passes from port 12 to port .14 through line 13 into the down side'ofthelift cylinder 15 and exerts pressure against the lift'cylinder piston 23. `The lift cylinder piston 23 is unable to ymove at that moment because line 21 is closed by seated plunger 30. This pressure being applied to the down side of lift cylinder 15 also passes through line 16 through pilot orifice 26 and pushes cushion timing piston 27 tothe right which in turn pushes flow control plunger 30V to the right unseating the same and allowing fluid to How from port 22 to the main control Valve. i*

As stated above, the valve also acts as a cushioning valve when starting to lower the trencher boom. As explained above, when hydraulic pressure isY applied tothe down side of cylinder 15, iluid cannot escape from the lift side of lcylinder 15 until iluid from the down side :of said cylinder has passed through the pilot orice 26. and moved the cushion timing piston 27 to the right, thereby unseating plunger 30.VA .As plunger 30 begins to unseat iluid ows through the graduated orifices or ports 35, completing the circuit -from port 22 to the main control valve. The oriices or ports 35 being graduated, restrict the ow of fluid at first and then as each is opened, allow more uid to ow until their total area is more than that of the lines in the system and complete full ilow is accomplished. This graduated restriction, from no ow to full ilow, when done in a short period of time, acts as a cushion and because of this, the trencher boom starts to move downward very slowly and then gradually speeds up to fyull downward speed making downward operation smooth and free of jerks.

The valve, as statedabove, also acts as a cushioning valve when stopping downwardmovement of the trencher boom. In this arrangement, when the boom is being lowered, pressure applied to the down side of the lift cylinder holds the dow control and cushioning plunger 30 open, as described above in connection with the action of the valve as a positive seal, and when the operator closes the main control valve to stop downward movement, the owing cycle takes place which cushions the stopping of the downward movement of the trencher boom and associated parts:

The closing of the main control valve by the operator stops the ow of fluid through lines 13 and 11 and due to the momentum and weight of the boom and associated parts, pressure is exerted on the lift side of the lift cylinder 15, while the pressure immediately drops on the down side of the lift cylinder.

The pressure already present between piston 27 and orifice 26 escapes through pilot orifice 26 through

lines

16 and 13 to the down side of the liftcylinder 15, thereby lowering the pressure in the chamber between piston 27 and pilot orifice 26 and as this pressure drops, pressure from the lift side of the lift cylinder is exerted on the side of piston 27 opposite pilot orice 26 by owing through the orices 35 in the ow control plunger 30 and causing the cushion timing piston 30 to move toward piston 27. Pressure on the right side of timing piston 27 and on the right end of flow control plunger 30 keeps the cushion timing piston 27 moving toward orice 26 and due to the graduated orifices in the ow control plunger 30, the more the cushion timing piston 27 moves to the left, the more the restriction until the iiow control plunger 30 is fully seated as shown in FIG. 3. This graduated cutdown of ow cushions the downward movement of the trencher boom and it is gradually brought to a stop.

The ow control valve also acts to provide anti-cavitation to the down side of the lift cylinder during downward movement of the trencher boom. VIn this operation, as the trencher boom is being lowered due to the weight of the trencher bucket, dipper stick, etc., there is a tendency for the fluid from the lift side of the lift cylinder to escape at a faster rate than the pump through the manual control valve supplies fluid to the down side of the lift cylinder 15. With the present valve, as shown in FIG. 3, uid from the lift side of the cylinder cannot escape until line 16 is pressurized and tluid pressure that is escaping from the lift side of the lift cylinder piston is attempting to keep plunger 30 closed. The pump supplying iluid to the down side of the lift cylinder 15 and pressurizing line 16, dueto the cushion timing piston being larger in diameter than the ilow control and cushioning plunger 30, forces the cushion timing piston Z7 to move to the right and open plunger 30 and keeps it open only as long as there is pressure in line 16. It will be understood that plunger 30 is opened only the proper distance or amount, as an example, if the motor were idling and the pump were turning out only a small volume of fluid then the plunger 30 might conceivably be moved over very little a's the rst few orices 35 would be large enough to take the ow of uid being supplied 4by the pump whereas, if the pump were running at a Vhigher pace, plunger 30 would be 'moved a greater distance tothe right and ,So on and, therefore, at Ano time 4 I can line 16 be under a vacuum which would allow the pump to cavitate.

From the foregoing, it will be seen that I have provided new and improved means for obtaining all of the objects and advantages of the invention.

I claim:

1. In a device of the type set forth, a cylinder, a piston in said cylinder, a restricted orifice for controlling the passage of fluid to said cylinder on one side of said piston, a uid passage connected to said cylinder on the opposite side of said piston, a chamber communicating with said cylinder on the side thereof opposite `said restricted oritice, a valve for controlling the passage of fluidv `from said cylinder to said chamber, said valve being adapted to be moved in one direction by said piston, resilient means for normally urging said valve in a direction opposing movement thereof by said piston, and said valvehaving a passage therethrough connecting said cylinder with said chamber, and port means in said chamber adapted to be connected to a hydraulic line.

2. In a device of the type set forth, a cylinder, a piston in said cylinder, a restricted orifice -for controlling the passage of fluid to said cylinder on one side of said piston, a uid passage connected to said cylinder on the opposite side of said piston, a chamber communicating with said cylinder on the side thereof opposite said restricted orice, a valve for controlling the passage of fluid from said cylinder to said chamber, said valve being adapted to be moved in one direction by said piston, resilient means for normally urging said valve in a direction opposing movement thereof by said piston, and s aid valve having a passage therethrough connecting said cylinder with said chamber, said valve having port means of progressively increasing area as said valve is moved into into said chamber by said piston, and port means in said chamber adapted to be connected to a hydraulic line.

3. In a device of the type set forth, a cylinder, a piston in said cylinder, a restricted orifice for controlling the passage of uid to said cylinder on one side of said piston, a uid passage connected to said cylinder `on the opposite side of said piston, a chamber communicating with said cylinder on the side thereof opposite said restricted orifice, a valve for controlling the passage of fluid from said cylinder to said chamber, said valve being adapted to be moved in one direction by said piston, resilient means for normally urging said'valve in a direction opposing movement thereof by said piston, and said valve having a passage therethrough connecting said cylinder with said chamber and port means in said chamber adapted to be connected to a hydraulic line.

4. In a device of the type set forth, a cylinder, a piston in said cylinder, a restricted orifice for controlling the passage of fluid to said cylinder on one side of said piston, a Huid passage connected to ,said cylinder on the opposite side of said piston, a chamber communicating with said cylinder on the side thereof opposite said restricted orifice, a valve for controlling the passage of uid from said cylinderto said chamber, said valve being adapted to be moved in one direction by said piston, resilient means for normally urging said valve in a direction opposing move rnent thereof by said piston, and said v alve having a passage therethrough connecting said cylinder with said chamber, said valve having port means of progressively increasing area as said valve is moved into said chamber by said piston and port means in said chamber adapted to be connected to a hydraulic line. i

`5. In a device of the type set forth, a cylinder, a piston in said cylinder, a restricted orice for controlling the passage of uid to said cylinder on one side `of said piston, .a fluid passage connected to said cylinder on the `opposite side of said piston, a chamber communicating with said cylinder on the side thereof opposite `said restricted orice, a valve for controlling the passage `o f uid lfrom said cylinder to said chamber, said valve being adapted to be moved in one direction by said piston, resilient means for normally urging said valve in a direction opposing movement thereof by said piston, and said valve having a passage therethrough connecting said cylinder with said chamber, said valve being adapted to be closed by said resilient means and opened by the force of fluid in said cylinder from a hydraulic line and passing through said restricted orifice, and port means in said chamber adapted to be connected to a hydraulic line.

6. In a device of the type set forth, a cylinder, a piston in said cylinder, a restricted orifice for controlling the passage of fluid to said cylinder on one side of said piston, a fluid passage connected to said cylinder on the opposite side of said piston, a chamber communicating with said cylinder on the side thereof opposite said restricted orifice, a port in said chamber, a valve for controlling the passage of fluid from said cylinder to said chamber, said valve being adapted to be moved in one direction by said piston, resilient means for normally urging said valve in a direction opposing movement thereof by said piston, and said valve having a passage connecting said cylinder with said chamber, sai-d restricted orifice being connected by a hydraulic line to the control valve and the down side of a cylinder and said port in said chamber being connected by a hydraulic line to the lift side of a cylinder with said fluid passage on the side of said cylinder opposite said restricted orifice being connected to the control valve.

7. In a device of the type set forth, a cylinder, a piston in said cylinder, a restricted orifice for controlling the passage of fluid to said cylinder on one side of said piston, a fluid passage connected to said cylinder on the opposite side of said piston, a chamber communicating with said cylinder on the side thereof opposite said restricted orice, a port in said chamber, a valve for controlling the passage of fluid from said cylinder to said chamber, said valve being adapted to be moved in one direction by said piston, resilient means for normally urging said valve in a direction opposing movement thereof by said piston, and said valve having a passage connecting said cylinder with said chamber, said valve having port means of progressively increasing area as said valve is moved into said chamber by said piston, said restricted orice being connected by a hydraulic line to the control valve and the down side of a cylinder and said port in said chamber being connected by a hydraulic line to the lift side of a cylinder with said fluid passage on the 'side of said cylinder opposite said restricted orifice being connected to the control valve.

8. In a device of the type set forth, a cylinder, a piston in said cylinder, a restricted orifice for controlling the passage of fluid to said cylinder on one side of said piston, a fluid passage connected to said cylinder on the opposite side of said piston, a chamber communicating with said cylinder on the side thereof opposite said restricted orice, a port in said chamber, a valve for controlling the passage of fluid from said cylinder to said chamber, said valve being adapted to be moved in one direction by said piston, resilient means for normally urging said valve in a direction opposing movement thereof by said piston, and said valve having a passage connecting said cylinder with said chamber and port means in said chamber adapted to be connected to a hydraulic line, said restricted orifice being connected by a hydraulic line to the control valve and the down side of a cylinder and said port in said chamber being connected by a hydraulic line to the lift side of a cylinder with said fluid passage on the side of said cylinder opposite said restricted orifice being connected to the control valve.

9. In a device of the type set forth, a cylinder, a piston in said cylinder, a restricted orifice for controlling the passage of fluid to said cylinder on one side of said piston, a fluid passage connected to said cylinder on the opposite side of said piston, a chamber communicating with said cylinder on the side thereof opposite said restricted orifice, a port in said chamber, a valve for controlling the passage of fluid from said cylinder to said chamber, said valve being adapted to be moved in one direction by said piston, resilient means for normally urging said valve in a direction opposing movement thereof by said piston, and said valve having a passage connecting said cylinder with said chamber, said valve having port means of progressively increasing area as said valve is moved into said chamber by said piston and port means in said chamber adapted to be connected to a hydraulic line, said restricted orifice being connected by a hydraulic line to the control valve and the down side of a cylinder and said port in said chamber being connected by a hydraulic line to the lift side of cylinder opposite said restricted orifice with said fluid passage on the side of said cylinder being connected to the control valve.

l0. In a device of the type set forth, a cylinder, a piston in said cylinder, a restricted orifice for controlling the passage of fluid to said cylinder on one side of said piston, a fluid passage connected to said cylinder on the opposite side of said piston, a chamber communicating with said cylinder on the side thereof opposite said restricted orifice, a port in said chamber, a valve for controlling the passage of fluid from said cylinder opposite said restricted orifice to said chamber, said valve being adapted to be moved in one direction by said piston, resilient means for normally urging said valve in a direction opposing movement thereof by said piston, and said valve having a passage connecting said cylinder with said chamber, said valve being adapted to be closed by said resilient means and opened by the force of fluid in said cylinder from a hydraulic line and passing through said restricted orifice, said restricted orifice being connected by a hydraulic line to the control valve and the down side of a cylinder and said port in said chamber being connected by a hydraulic line to the lift side of a cylinder with said fluid passage on the side of said cylinder opposite said restricted orifice being connected to the control valve.

References Cited in the file of this patent UNITED STATES PATENTS 2,588,520 Halgren et al Mar. 11, 1952