Hydraulic drive system and improved control valve assembly therefor
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
F16D-031/02
F16K-031/12
출원번호
US-0832967
(2004-04-27)
발명자
/ 주소
Singh, Rodney V.
출원인 / 주소
Eaton Corporation
인용정보
피인용 횟수 :
33인용 특허 :
4
초록▼
A control valve assembly (43) for use in a system in which a pump-motor unit (35) can either receive drive torque from a drive-line (17) or transmit torque thereto. The system includes a high pressure accumulator (41) and the control valve assembly is disposed between the pump-motor unit and the acc
A control valve assembly (43) for use in a system in which a pump-motor unit (35) can either receive drive torque from a drive-line (17) or transmit torque thereto. The system includes a high pressure accumulator (41) and the control valve assembly is disposed between the pump-motor unit and the accumulator, and includes a mode valve (45) normally biased closed by pressure in a control cavity (89), the fluid pressure in which is controlled by a pilot valve assembly (49) in response to an electrical signal (133). A step-orifice valve (47) associated with the mode valve poppet member (79) provides a relatively larger orifice (115) into the control cavity (89) when pressure therein is high, and a relatively smaller orifice (119) into the control cavity when pressure therein is low, i.e., when the pilot valve assembly (49) is open. Thus, a large volume of flow can occur from the accumulator to the unit (35) in a motoring mode, with a relatively low pressure drop, while the poppet member is able to have softer, relatively longer opening time, but a relatively faster closing time.
대표청구항▼
1. A control valve assembly for use in a hydraulic system adapted for use on a system having a drive-line operable to transmit driving torque to a drive axle, said hydraulic drive system including a pump-motor unit operable, in a pumping mode, to receive drive torque from said drive-line, and operab
1. A control valve assembly for use in a hydraulic system adapted for use on a system having a drive-line operable to transmit driving torque to a drive axle, said hydraulic drive system including a pump-motor unit operable, in a pumping mode, to receive drive torque from said drive-line, and operable, in a motoring mode, to transmit drive torque to said drive-line; a high pressure accumulator in fluid communication with a first port of said pump-motor unit through said control valve assembly whereby, when said pump-motor unit is in said pumping mode, pressurized fluid is communicated from said first port to said high pressure accumulator, and when said pump-motor unit is in said motoring mode, pressurized fluid is communicated from said high pressure accumulator to said first port; said control valve assembly including a valve housing defining a poppet seat and a port in fluid communication with said accumulator, and being characterized by:(a) a main poppet member defining a control cavity, fluid pressure in said control cavity biasing said main poppet member toward said poppet seat;(b) substantially all flow between said high pressure accumulator and said first port of said pump-motor unit flowing past said main poppet member and said poppet seat in either said pumping mode or said motoring mode;(c) a pilot valve assembly having open and closed conditions and operable to control fluid communication from said control cavity to a source of low pressure, in response to an electrical input signal;(d) a step-orifice valve assembly operable to control fluid communication from said accumulator through said port, defined by said valve housing, to said control cavity, and defining a first, relatively larger flow orifice when fluid pressure in said control cavity is relatively high, and a second, relatively smaller flow orifice when fluid pressure in said control cavity is relatively low, to provide a relatively small flow to said pilot valve assembly.2. A control valve assembly as claimed in claim 1, characterized by said main poppet member being configured, relative to said poppet seat such that, when the fluid pressure at said port, defined by said valve housing, is substantially equal to the fluid pressure in said control cavity, said poppet member is biased into closed, sealing engagement with said poppet seat.3. A control valve assembly as claimed in claim 2, characterized by a relatively light compression spring being disposed in said control cavity and operable to assist said fluid pressure in said control cavity to bias said poppet member toward said poppet seat.4. A control valve assembly as claimed in claim 3, characterized by said poppet member being configured, relative to said poppet seat, to provide an outer poppet area, disposed radially outward from said poppet seat, and in fluid communication with said first port of said pump-motor unit whereby, in said pumping mode, fluid pressure generated by said pump-motor unit acting as a pump, biases said poppet member to an open position, permitting flow from said pump-motor unit to charge said high pressure accumulator.5. A control valve assembly as claimed in claim 4, characterized by said step-orifice valve assembly being operable, when said pump-motor unit is in said pumping mode, to maintain the fluid pressure in said control cavity substantially equal to the fluid pressure in said fluid port, defined by said valve housing, whereby, when said pump-motor unit ceases pumping pressurized fluid into fluid communication with said outer poppet area disposed radially outward from said poppet seat, said poppet member quickly returns to its closed, sealing engagement with said poppet seat, under the influence of said compression spring.6. A control valve assembly as claimed in claim 1 characterized by said second, relatively smaller flow orifice being selected such that during operation in said motoring mode, there is a relatively small pilot flow through said smaller flow orifice and to said pilot valve assembly in its open condition.7. A control valve assembly as claimed in claim 1, characterized by, said pilot valve assembly being sized such that, when said pilot valve assembly is in said open condition, pilot flow through said pilot valve assembly is much greater than the flow through said step-orifice valve assembly, causing a substantial decrease in fluid pressure within said control cavity, thereby causing said step-orifice valve assembly to shift to a position in which the only fluid communication from said accumulator to said control cavity is through said second, relatively smaller flow orifice.
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