Methods of measuring pressure of hydraulic fluid, methods of evaluating soundness and hydraulic drive devices for carrying out the methods
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
B60T-013/16
B60T-013/10
출원번호
US-0071153
(2005-03-04)
우선권정보
JP-2002-108160(2002-04-10)
발명자
/ 주소
Nakano,Keita
출원인 / 주소
Advics Co., Ltd.
대리인 / 주소
Buchanan Ingersoll & Rooney PC
인용정보
피인용 횟수 :
6인용 특허 :
12
초록▼
A condition of hydraulic fluid conducted from an accumulator to an operation device via a pressure control unit, is evaluated by determining a pressure (Pa) of the fluid in a flow path interconnecting the accumulator and the control unit, and determining a stabilization time (T) when an absolute val
A condition of hydraulic fluid conducted from an accumulator to an operation device via a pressure control unit, is evaluated by determining a pressure (Pa) of the fluid in a flow path interconnecting the accumulator and the control unit, and determining a stabilization time (T) when an absolute value of a pressure gradient per unit time of the pressure falls below a predetermined value. A pressure drop (ΔPa) of the pressure is determined during a period between a time (T0) when the pressure begins to decrease, or at a time before the time (T0) and the stabilization time (T). The pressure drop is compared with a predetermined pressure drop that is obtainable under normal conditions. An increase in (ΔPa) can signify the entry of air into the hydraulic fluid, or a leakage of the hydraulic fluid.
대표청구항▼
What is claimed is: 1. A method of evaluating soundness of a hydraulic drive device, wherein the hydraulic drive device comprises a pressure generator for generating a flow of a pressurized hydraulic fluid, a pressure-variable accumulator for accumulating the pressure of the pressurized hydraulic f
What is claimed is: 1. A method of evaluating soundness of a hydraulic drive device, wherein the hydraulic drive device comprises a pressure generator for generating a flow of a pressurized hydraulic fluid, a pressure-variable accumulator for accumulating the pressure of the pressurized hydraulic fluid supplied from the pressure generator, and a pressure control unit that is arranged and constructed to receive the pressurized hydraulic fluid from the accumulator and to control the pressure of the pressurized hydraulic fluid in response to an input from an external device, so that the pressurized hydraulic fluid having the controlled pressure is used for driving an operation device, comprising: detecting a first pressure of the hydraulic fluid within a flow path of the hydraulic fluid by a first pressure sensor, wherein the flow path extends between the pressure control unit and the operation device, and the first pressure sensor is coupled to the flow path, detecting a second pressure of the hydraulic fluid discharged from the accumulator by a second pressure sensor, wherein the second pressure sensor is coupled to the accumulator, determining a stabilization time by an operation control unit, wherein the stabilization time is a time when an absolute value of a pressure gradient per unit time of the pressurized hydraulic fluid supplied from the accumulator becomes smaller than a predetermined value during the supply of the hydraulic fluid from the pressure control unit to the operation device, and the operation control unit receives detection signals from the first and second pressure sensors, determining a pressure drop of the second pressure during a period between a time prior to starting the operation of the pressure control unit and the stabilization time, determining the first pressure at the stabilization time or at a time immediately after the stabilization time, and comparing the determined pressure drop with a pressure drop under a normal condition and comparing the detected first pressure at the stabilization time with a value under normal condition of the first pressure at stabilization time or at a time immediately after the stabilization time. 2. A method as in claim 1, wherein the evaluation is performed when the pressure generator is not operated. 3. A method as in claim 1, further including resting the pressure generator in a non-operative state during the evaluation. 4. A method of evaluating a condition of a hydraulic fluid supplied from a hydraulic drive device to an operation device, wherein the hydraulic drive device comprises a pressure generator arranged and constructed to pressurize the hydraulic fluid, an accumulator arranged and constructed to receive the supply of the pressurized hydraulic fluid from the pressure generator in order to accumulate the pressure of the pressurized hydraulic fluid, and a pressure control unit arranged and constructed to receive the pressurized hydraulic fluid from the accumulator and to control the pressure of the hydraulic fluid to be supplied to the operation device in response to operation of an external device, comprising: measuring a pressure (Pa) of the hydraulic fluid within a flow path connecting the accumulator and the pressure control unit, determining a stabilization time (T) that is the time when an absolute value of a pressure gradient per unit time of the pressure (Pa) becomes smaller than a predetermined value, determining a pressure drop (ΔPa) of the pressure (Pa) during a period between a time (T0) when the pressure (Pa) begins to decrease and the stabilization time (T) or during a period between at a time before the time (T0) and the stabilization time (T), comparing the determined pressure drop (ΔPa) of the pressure (Pa) with a predetermined pressure drop obtainable under a normal condition; measuring a control pressure (Pm) of the hydraulic fluid within a flow path connecting the pressure control unit and the operation device, and comparing the measured control pressure (Pm) at the stabilization time or at a time immediately after the stabilization time (T) with a predetermined control pressure value obtainable under a normal condition at that time. 5. A method as in claim 4, further including determining a pressure (Pw) supplied to the operation device to be substantially equal to the pressure (Pm) measured at the stabilization time (T) or at a time immediately after the stabilization time (T). 6. A method as in claim 4, wherein the step of determining the pressure (Pw) comprises calculating the pressure (Pw) by multiplying the pressure (Pm) measured at the stabilization time (T) or at a time immediately after the stabilization time by a predetermined correction coefficient. 7. A method as in claim 4, wherein the pressure (Pa) is measured continuously or periodically, so that the pressure gradient is calculated from the measured values of the pressure (Pa). 8. A method as in claim 4, further including temporally storing the measured values of the pressure (Pa) in an operation control unit, so that the measured values stored in the operation control unit are used for calculation of the pressure gradient. 9. A method as in claim 4, wherein the determination of the pressure (Pw) of the hydraulic fluid supplied to the operation device is performed when the pressure generator is not operated. 10. A method as in claim 4, further including resting the pressure generator in a non-operative state during the determination of the pressure (Pw) of the hydraulic fluid that is supplied to the operation device. 11. A method as in claim 4, wherein the hydraulic drive device comprises a brake device, and the operation device comprises a plurality of wheel brakes. 12. A method as in claim 11, wherein the external device comprise a brake pedal. 13. A hydraulic drive device for carrying out a method of claim 4 comprising: the pressure generator, the accumulator and the pressure control unit, a first pressure sensor arranged and constructed to detect the pressure (Pa), an operation control unit arranged and constructed to determine the stabilization time (T) and the pressure drop (ΔPa) and to compare the determined pressure drop (ΔPa) with the predetermined pressure drop; a second pressure sensor arranged and constructed to detect a pressure (Pm) of the hydraulic fluid within a flow path connecting the pressure control unit and the operation device, wherein the operation control unit is further arranged and constructed to compare the measured pressure (Pm) at the stabilization time (T) or at a time immediately after the stabilization time (T) with a predetermined value of the pressure (Pm) to be obtained under a normal condition at that time.
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이 특허에 인용된 특허 (12)
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