Claims
- 1. A three-way control valve for use with a single-acting cylinder or the like in control of advance, return or hold operation thereof comprising, a valve body having an inlet port, a control port and a tank port, a first bore in said body in communication with all three of said ports, a first poppet check valve in said first bore and having a valve seat whereby, when seated, flow from the control port to the inlet port is blocked, a second poppet check valve in said first bore and having a valve seat whereby, when seated, flow from the control port to the tank port is blocked, a second bore in said body in parallel adjacent relation to said first bore and in communication with said inlet port and the tank port, a spool valve in said second bore with spaced opposed lands and one of said lands defining a poppet valve member coacting with a valve seat to control flow to the tank port, a passage connecting said first bore with said second bore intermediate said spaced opposed lands of said valve spool for fluid flow from the inlet port to the tank port, the poppet valve member in said second bore having an open position to permit flow from the inlet port to the tank port in hold and return operations and to block said flow in an advance operation whereby fluid flows past said first check valve to said control port, means for positioning said poppet valve member, both of said check valves being held on their respective valve seats by fluid pressure in a hold operation, means for opening said second check valve and holding said first check valve closed in a return operation to permit fluid flow from the control port to the tank port, and decompression valve means operable to bleed fluid from the control port to the tank port to reduce said fluid pressure and reduce the force required to open said second check valve, said decompression valve means including a relatively small poppet valve carried by said second check valve, spring means acting between said first check valve and said small poppet valve, a movable pin for opening said small poppet valve, and a movable member for sequentially engaging said pin and said second check valve, said spaced opposed lands of said spool valve being of unequal area with the land defining said poppet valve member being of a greater area to render said valve member pressure-sensitive as moved toward said valve seat for the poppet valve member to initiate said advance operation.
- 2. A control valve as defined in claim 1 wherein said means for positioning said poppet valve member includes a first movable plunger, said means for opening said second check valve includes a second movable plunger, and a pivoted three-position control handle for manual operation of said plungers with said pressure-sensitive valve member imparting a control feel to said control handle when acting on said first movable plunger.
- 3. A three-way control valve for use with a single-acting cylinder or the like in control of advance, return or hold operation thereof comprising, a valve body having an inlet port, a control port and a tank port, a first bore in said body in communication with all three of said ports, a first poppet check valve in said first bore and having a valve seat whereby, when seated, flow from the control port to the inlet port is blocked, a second poppet check valve in said first bore and having a valve seat whereby, when seated, flow from the control port to the tank port is blocked, a second bore in said body in parallel adjacent relation to said first bore and in communication with said inlet port and the tank port, a spool valve in said second bore with spaced opposed lands and one of said lands defining a poppet valve member coacting with a valve seat to control flow to the tank port, a passage connecting said first bore with said second bore intermediate said spaced opposed lands of said valve spool for fluid flow from the inlet port to the tank port, the poppet valve member in said second bore having an open position to permit flow from the inlet port to the tank port in hold and return operations and to block said flow in an advance operation whereby fluid flows past said first check valve to said control port, means for positioning said poppet valve member, both of said check valves being held on their respective valve seats by fluid pressure in a hold operation, means for opening said second check valve and holding said first check valve closed in a return operation to permit fluid flow from the control port to the tank port, said first poppet check valve being a ball valve; said second poppet check valve having an elongate body movable in said first bore with a frusto-conical valve section and an internal chamber, and a passage extending therefrom to the end of said elongate check valve body, an open end of said internal chamber being larger than and partially receiving said ball valve for guiding thereof; and decompression means including a ball check positioned within said internal chamber and seated against an end of said passage; a spring guided in said internal chamber and acting against both said ball check and the ball valve, and a pin in said passage for opening said ball check for flow through said passage; a movable member for sequentially engaging said pin and then said elongate body to open the ball check and then the second poppet check valve with such action compressing said spring acting on the ball valve; and a guide land on said elongate body engageable within said first bore and shaped to permit flow therepast from the inlet port to the control port and from the control port to said internal chamber, said spool valve being hydraulically unbalanced to exert a force opposing said poppet valve member positioning means in moving the poppet valve member to said flow-blocking position.
- 4. A control valve as defined in claim 3 wherein said means for positioning said poppet valve member includes a movable plunger, and a pivoted multi-position control handle for manual operation of said plunger and said movable member with said hydraulically unbalanced spool valve imparting a control feel to said control handle when acting on said movable plunger.
Parent Case Info
This is a division of application Ser. No. 469,424, filed May 13, 1974, now U.S. Pat. No. 3,934,610.
Foreign Referenced Citations (1)
Number |
Date |
Country |
1,017,793 |
Dec 1952 |
FR |
Divisions (1)
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Number |
Date |
Country |
Parent |
469424 |
May 1974 |
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