Pumps – Condition responsive control of drive transmission or pump... – Adjustable cam or linkage
Reexamination Certificate
2008-07-15
2008-07-15
Kramer, Devon (Department: 3746)
Pumps
Condition responsive control of drive transmission or pump...
Adjustable cam or linkage
C417S219000
Reexamination Certificate
active
07399166
ABSTRACT:
A variable displacement pump includes a control valve formed with a high-pressure chamber for introducing therein high-pressure fluid on the upstream side of a metering orifice, a pressure chamber for introducing therein pressure fluid on the downstream side of the metering orifice, a low-pressure chamber arranged between the high-pressure and pressure chambers for introducing therein low-pressure fluid, and a communication passage for providing fluid communication between one of the high-pressure and low-pressure chambers and a first fluid-pressure chamber of the pump. First and second recessed grooves are formed in the outer-peripheral surface of a spool of the control valve to provide fluid communication between the low-pressure and high-pressure chambers through the communication passage of the control valve when the spool carries out selective switching between the high-pressure and low-pressure chambers to supply fluid to the communication passage, thus restraining abrupt pressure rise in the first fluid-pressure chamber.
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U.S. Appl. No. 10/889,126, filed Jul. 13, 2004, Uchino et al.
Miyazawa Shigeyuki
Uchino Kazuyoshi
Foley & Lardner LLP
Frantz Jessica L
Kramer Devon
Unisia JKC Steering Systems Co., Ltd.
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