US3527250A

US3527250A - Valve for manual control of hydraulic cylinders

Info

Publication number: US3527250A
Application number: US731821A
Authority: US
Inventors: Vitas T Thomas; Robert A Lovdahl
Original assignee: Tomco Inc
Current assignee: VITAS THOMAS 158 LAKEFIELD COURT RACINE WI 53402-3103
Priority date: 1968-05-24
Filing date: 1968-05-24
Publication date: 1970-09-08
Anticipated expiration: 1987-09-08

Description

spf.s,197o V.T.THOMAS am. 3,527,250

VALVE FOR MANUAL CONTROL OF HYDRAULIC'CYLINDERS Filed May 24, 1968 United States Patent O 3,527,250 VALVE FOR MANUAL CONTROL OF HYDRAULIC CYLINDERS Vitas T. Thomas and Robert A. Lovdahl, Racine, Wis.,

assignors to Tomco, Inc., Racine, Wis., a corporation of Wisconsin Filed May 24, 1968, Ser. No. 731,821 Int. Cl. Fb 15/18 U.S. Cl. 137--565 5 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This invention relates to a control valve for a portable hydraulic pump wherein the control valve is used to control the buildup of pressure to a hydraulic device, to maintain the pressure in the hydraulic device and to relieve the pressure in the hydraulic device. The control functions in a valve of the type contemplated herein are normally accomplished by a valve actuating device including a threaded spool which is subjected to the force of the high pressure hydraulic iiuid flowing through the housing. At high operating pressures the force acting on the spool increases the friction on the threads of the spool to such an extent that the spool sticks in the housing.

SUMMARY OF THE INVENTION The invention disclosed herein provides a control valve for a portable hydraulic pump having the functions of the valve controlled by an actuating device which requires substantially the same actuating force or torque regardless of the pressure of the hydraulic fluid in the control valve. More specifically, the control valve according to the invention comprises a housing having a main flow passage and a return ow passage connected to bypass a check valve in the main ilow passage with a pair of check valves in the return passage to isolate a section of the return passage from the pressure of the hydraulic uid in the main flow passages. An actuating device is mounted in the housing for movement into the isolated section of the return passage to open one of the pair of check valves in the return passage to relieve the pressure in the main passage. This arrangement of the actuating device in the section isolated by the pair of check valves prevents the force of the high pressure hydraulic fluid from acting on the actuating device so that it can be rotated easily regardless of the operating pressure in the main passage.

Other objects and advantages of the present invention will become more readily apparent when read in connection with the accompanying drawings in which:

FIG. l is a schematic view of the portable hydraulic pump.

FIG. 2 is a section View in elevation of the control valve.

DESCRIPTION OF THE PREFERRED EMBODIMENT Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely eX- Cil rice

emplify the invention which is defined in the claims appended hereto.

Referring to FIG. l, the control valve 10 is shown mounted within a housing 12 and connected by a pipeline 14 to a hydraulic pump 16 which is driven by an electric motor 18 to pump hydraulic fluid from a reservoir 20 through the control valve to a hydraulic device (not shown) through a pipeline 21. The motor 18 is connected to an electrical power source (not shown) by electric lines L1-L2 through a normally open switch 22. The control valve 10 is used to control the operation of the motor 18, to maintain pressure in the outlet line 21, and to relieve the hydraulic pressure in pipeline 21 to the hydraulic device.

More particularly, the control valve 10, as seen in FIG. 2, includes a housing or body 24 having a main ow passage 26 connected at the inlet end to the pipeline 14 by a threaded nipple 17 and at the outlet end to the pipeline 21 by a threaded nipple 23. Return flow of fluid through the passage 26 is prevented by means of a main check valve 28 having a ball 30 biased into engagement with a valve seat 34 in the passage 26 by a spring 32 positioned between the ball 30 and the nipple 23. Hydraulic fluid is returned to the reservoir by means of a return or secondary passage 40 connected to bypass the main check valve 28 in the main passage 26. The flow of fluid through passage 40 is controlled by means of a rst return check valve 42 having a ball 44 biased into engagement with a valve seat 48 provided in the return passage 40 by a spring 46 positioned between the ball 44 and a threaded plug or retainer 50 having an aperture 51. Hydraulic uid in the main passage 26 is prevented from owing through the return passage 40 by means of a second return check valve 52 having a ball 54 biased into engagement with a valve seat 56 provided in the return passage 40i by a spring 58 positioned between the ball 52 and a threaded plug 60. Valves 42 and 52 are oppositely biased and seated in passage 40 in a space relation.

The check valve 42 is opened to allow hydraulic fluid to bypass check valve 28 and return to the reservoir 20 by means of an actuating device 62 mounted in a recess 64 connected to the section of return passage 40 isolated by the check valves 42 and 52. More particularly, the actuating device 62 includes a spool 66 having a needle 68 which projects into return passage 40 in a position for engagement with the ball 44. The check valve 42 is opened by moving the spool 66 axially into engagement with ball 44 to move the ball 44 oil of the valve seat 48. This is accomplished by providing a threaded section 70` on the spool `66 which engages a threaded section 72 in the recess 64. Rotation of the spool 66 in the recess 64 will move the needle 68 either toward or away from the ball 44. The spool 66 is sealed in the recess 64 by means of an O- ring seal 74 provided in a groove 76 in the spool 66 with a plastic backup ring 78 provided in the groove 76 to prevent extrusion of the O-ring. The spool is rotated by means of a handle `80 secured to a stem `82 on the end of the spool `66 by means of a pair of pins 84 passing through a pair of sleeves connected to an actuating lever 86. The actuating lever 86 is positioned to engage switch 22 to control the operation of the motor 18 and pump 16. A pair of springs 88 are attached to the ends of the lever `8.6 to hold the lever in a neutral position with the switch 22 open and the return check valve `42 closed.

`In operation, the handle 80` is rotated counterclockwise in FIG. 1, to move the actuating lever 86 into engagement with the switch 22. This will start the motor 18 and pump 16 to force hydraulic fluid through line 14 and passage 26 in housing 10. The pressure of the hydraulic iluid will open check valve 28. The hydraulic fluid is prevented from entering the return passage 40 by check valves 42 and 52. The handle 86 Vis held in this position until the pressure-in the outletpipeline .21 reaches the desired level. When the handle is released, springs 88 rotate the actuating device 62 clockwise to a neutral position. Check valves 28 and 42 will both be closed and the pressure of the hydraulic uid in the outlet line 21 will be maintained at the desired level. 'Rotation of the handle 80 clockwise will move the spool 66 into the housing 10 and the needle 68 will engage and unseat the ball 44 from the valve seat 48 against the bias of spring 46. The hydraulic fluid in the line 26 will flow past check valve 42 and will open the check valve 52 allowing the hydraulic iluid to flow back to the reservoir through the pipeline 14 and pump 16. v

With this arrangement, the spool 66 is never subjected to the pressure of the hydraulic uid in passage 26 while hydraulic uid is being pumped through the control valve or while the pressure of the hydraulic fluid is being maintained in the outlet line 21. In the absence of any hydraulic pressure on the spool, it can be rotated freely and will never lock in the housing.

What is claimed is:

1. A control valve for a hydraulic pump, said valve comprising a housing, a main flow passage through said housing, a main valve in said main flow passage, a return fiow passage connected to said main flow passage to bypass said main valve, a first return valve in said return passage, a second return valve in said return passage, and a threaded spool having a needle positioned in said return passage for engagement with one of said return valves, said one of said return valves being resiliently biased toward a closed position and arranged to relieve pressure in said main flow passage when engaged and opened by the rotary motion of said threaded spool in one direction.

2. A control valve according to claim 1 wherein said oneV of Ysaid return valves-comprises a one-way check valve positioned to prevent the return o'w of uid through said return passage and said other of said return valves comprises a one-way check valve positioned to prevent the flow of hydraulic uid in a forward ydirection through said return flow path.

3. A control valve according to claim 2 wherein said needle is positioned for movement in said return passage between said first and second return |valves.

4. A control valve according to claim 1 including a hydraulic pump connected to said main flow passage, a normally opened switch connected to control said pump, and an actuating lever connected to said spool and positioned to engage and close said switch when said spool is in the other direction.

5. A control valve according to claim 4 including a spring positioned to bias said actuating lever and spool to a neutral position with said switch open and said rst return valve closed.

References Cited UNITED STATES PATENTS 869,755 10/1907 Tretch 137-599 XR 911,285 2/1909 Barber. 1,577,446 3/ 1926 Brown 137-599 XR 2,342,311 2/1944 Thompson. 2,518,212 8/1950 Wilson 137-599 XR 3,126,795 3/1964 Kesselring 137-599 XR ROBERT G. NILSON, Primary Examiner U.S. C1. X.R.