Temperature compensated hydraulic valve |
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| 申请号 | US3648967D | 申请日 | 1970-11-10 | 公开(公告)号 | US3648967A | 公开(公告)日 | 1972-03-14 |
| 申请人 | PHYSICS INT CO; | 发明人 | O'NEILL CORMAC G; SMILEY PARKER C; | ||||
| 摘要 | A valve of the type which employs a hydraulic piston for amplifying the motion of an actuator, wherein undesirable effects of thermal expansion of the hydraulic fluid are eliminated. The valve includes an elastically expandable chamber coupled through a narrow passageway to the hydraulic cylinder for receiving fluid therefrom at a slow rate to hold the extra volume of hydraulic fluid caused by thermal expansion, and a check valve for allowing fluid to flow quickly from the chamber back to the cylinder. The narrow passageway from the hydraulic cylinder to the expandable chamber is formed by an appreciable clearance between a plunger that is moved by the hydraulic fluid and a plunger cylinder in which it slides. | ||||||
| 权利要求 | 1. In a valve assembly which includes a valve closing member movable to control flow through a passageway, a hydraulic cylinder for holding fluid, means for selectively pushing against said fluid to pressurize it, and means for coupling said fluid to said valve closing member to move it, the improvement comprising: first means coupled to said hydraulic cylinder for receiving fluid therefrom at a low flow rate; and second means coupling said first means back to said hydraulic cylinder for passing fluid substantially only in a direction towards said hydraulic cylinder at a high flow rate. 2. The improvement described in claim 1 including: means defining an elastically expandable chamber coupled to said first and second means. 3. The improvement described in claim 1 wherein: said first means includes a porous plug. 4. The improvement described in claim 1 wherein: said first means includes a plunger cylinder and a plunger slidably mounted in said plunger cylinder, a portion of the walls of said plunger and plunger cylinder having a clearance therebetween forming a narrow passageway. 5. A valve assembly comprising: means defining a first passageway and a valve seat along said passageway; a valve closing member mounted for movement against and away from said seat to close and open said passageway; a hydraulic cylinder for holding fluid; means for selectively compressing fluid in said cylinder; plunger means mounted for moving towards said valve closing member under the pressure of said fluid, to move said valve closing member; expansion chamber means for holding some of said fluid while maintaining pressure on it; and means defining a second passageway for coupling said cylinder to said expansion chamber means. 6. The valve assembly described in claim 5 wherein: said plunger means has a first portion facing said fluid in said hydraulic cylinder which is constructed with a clearance that permits the flow of said fluid thereby, and a second portion spaced from said first portion for preventing the flow of fluid which leaks by said first portion from passing to said valve closing member; and said second passageway is coupled to said first portion of said plunger means to carry fluid which flows thereby to said expansion chamber means. 7. The valve assembly described in claim 5 including: a return passageway coupling said expansion chamber means to said hydraulic cylinder; and a check valve disposed along said return passageway for allowing fluid to flow therethrough only in a direction towards said cylinder. 8. The valve assembly described in claim 5 wherein: said expansion chamber means includes a bellows having one side exposed to said fluid, and spring means for urging said bellows to expel said fluid. 9. A valve assembly comprising: means defining a passageway and a valve seat along said passageway; a valve closing member mounted for movement against and away from said seat to close and open said passageway; a hydraulic cylinder for holding fluid; means for selectively compressing fluid in said cylinder; slidably mounted plunger means for moving under the pressure of said fluid, said plunger means having a first portion for contacting said fluid to receive forces therefrom, a second portion for moving said valve closing member, and a middle portion for receiving fluid leaking past said first portion; an expansion chamber coupled to said middle portion to receive fluid therefrom while maintaining pressure on said fluid; and a return valve for coupling said expansion chamber to said hydraulic cylinder. 10. The valve described in claim 9 wherein: said means for selectively compressing fluid in said cylinder includes a piston slidably mounted in said hydraulic cylinder and an actuator for moving said piston, said piston having a sealing ring thereabout to form a tight seal with the walls of said cylinder; said second portion of said plunger has a sealing ring thereabout to prevent the leakage of fluid thereby; and said plunger is constructed to provide a leakage of said fluid between said first and middle portions thereof at a rate many times greater than the rate of fluid leakage past said sealing ring on said piston and on said second portion of said plunger. |
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