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公开(公告)号：DE69918803T2
公开(公告)日：2005-08-04
申请号：DE69918803
申请日：1999-12-02
Applicant: HITACHI CONSTRUCTION MACHINERY
Inventor： TSURUGA YASUTAKA , KANAI TAKASHI , KAWAMOTO JUNYA , NAKATANI KENICHIRO , TAKAHASHI KIWAMU , HAMAMOTO SATOSHI , OKAZAKI YASUHARU , NAGAO YUKIAKI
Abstract: A hydraulic driving unit comprising a pump controller (18) controlling the discharge flow rate such that the pump discharge pressure is higher than the maximum load pressures in actuators(2-6) by a predetermined amount, and pressure compensation valves (12 - 16) having respective differential pressures between the discharge pressure of a hydraulic pump (1) and the maximum load pressures of the actuators (2-6) set to target compensation differential pressures, the pressure compensation valve (12) having a load-dependent characteristic that reduces the target compensation differential pressure when the load pressure increases, the pressure compensation valve (12) of the swing section being provided with a lower-limit setting spring (55) for preventing the target compensation differential pressure from lowering below a predetermined value. Thereby, the system is provided that permits acceleration without jerks at both the start for swing alone and the start for swing combination suppresses changes in the swing speed during transition from swing alone to combination, permits, at the start for swing combination, acceleration without extremely reducing the swing speed as compared with other actuators, and presents no problem, such as increases in cost and space or complicated circuit arrangement.
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公开(公告)号：DE3871755T2
公开(公告)日：1992-12-24
申请号：DE3871755
申请日：1988-12-28
Applicant: HITACHI CONSTRUCTION MACHINERY
Inventor： ICHIRYU KEN , KANAI TAKASHI , OCHIAI MASAMI , ICHIKI NOBUHIKO
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公开(公告)号：DE69727659T2
公开(公告)日：2004-10-07
申请号：DE69727659
申请日：1997-11-14
Applicant: HITACHI CONSTRUCTION MACHINERY
Inventor： TSURUGA YASUTAKA , KANAI TAKASHI , KAWAMOTO JUNYA
Abstract: Differential pressures across flow control valves (6a, 6b, 6c) are controlled by pressure compensating valves (7a, 7b, 7c) to a differential pressure DELTA PLS having the same value, and the differential pressure DELTA PLS is maintained at a target differential pressure DELTA PLSref by a pump capacity control device (5). To modify the target differential pressure DELTA PLSref depending upon a change in revolution speed of an engine (1), a flow rate detecting valve (31) is provided on discharge passages (30a, 30b) in a fixed capacity hydraulic pump (30) so that a differential pressure DELTA Pp across a variable restriction (31a) in the flow rate detecting valve (31) is conducted to a setting modifying device (32) to modify the target differential pressure DELTA PLSref. The flow rate detecting valve (31) acts to change an opening area of the variable restriction (31a) depending upon the differential pressure DELTA Pp across the variable restriction (31a) itself, and to change the differential pressure DELTA Pp in accordance with the revolution speed of the engine (1). Accordingly, saturation phenomenon is improved in accordance with the engine revolution speed, and a favorable minute operability is obtained in the case where the engine revolution speed is set low.
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公开(公告)号：DE60101349D1
公开(公告)日：2004-01-15
申请号：DE60101349
申请日：2001-01-10
Applicant: HITACHI CONSTRUCTION MACHINERY
Inventor： TSURUGA YASUTAKA , KANAI TAKASHI , KAWAMOTO JUNYA , HAMAMOTO SATOSHI , OKAZAKI YASUHARU , NAGAO YUKIAKI
Abstract: In a hydraulic drive system in which a target compensated differential pressure for each of pressure compensating valves 21a, 21b is set in accordance with a differential pressure between a pump delivery pressure and a maximum load pressure, and a target LS differential pressure is set as a variable value depending on a revolution speed of an engine 1, a fixed throttle 32 and a signal pressure variable relief valve 33 are disposed in a maximum load pressure line 35. A relief setting pressure PLMAX' of the signal pressure variable relief valve 33 is set so as to satisfy PLMAX' = PR - PGR + alpha (where alpha is a value smaller than PGR) with respect to a target LS differential pressure PGR and a setting pressure PR of the main relief valve 30. Even when a load pressure of any one actuator reaches the setting pressure of the main relief valve during the combined operation in which a plurality of actuators are simultaneously driven, pressure compensating valves are not closed, the other actuators are not sped up, and good operability in the combined operation can be ensured.
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公开(公告)号：DE69124551T2
公开(公告)日：1997-09-04
申请号：DE69124551
申请日：1991-07-03
Applicant: HITACHI CONSTRUCTION MACHINERY
Inventor： OSHINA MORIO , KANAI TAKASHI , SONODA MITSUO
IPC: E02F9/22 , F16H61/40 , F16H61/42 , F16H61/421 , F16H61/425 , F16H61/46
Abstract: A first hydraulic circuit (HC1) comprises a variable displacement hydraulic pump (2) driven by a prime mover (1), a variable displacement hydraulic motor (12) connected in a closed circuit to the variable displacement hydraulic pump (2), and a displacement control means (22)(41) for controlling a displacement of the variable displacement hydraulic motor (12). A second hydraulic circuit (HC2) comprises a hydraulic pump (4) driven by the prime mover (1), and drives a loader attachment. A displacement limitation means (23)(31)(42)(43)(44)(143)(45)(46)(47)(142) limits the maximum value of the displacement of the variable displacement hydraulic motor (12) in accordance with a load pressure of the second hydraulic circuit (HC2). For example, the displacement limitation means (23)(31)(42)(43)(44)(143)(45)(46)(47)(142) reduces the maximum value of the displacement of the variable displacement hydraulic motor (12) in proportion to the pressure in the second hydraulic circuit (HC2). The motor torque is controlled by directly adjusting the displacement of the motor (12), and a load of the hydraulic motor (12) can thus be stably controlled.
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Patent Agency Ranking
公开(公告)号：DE69934483T2
公开(公告)日：2007-11-29
申请号：DE69934483
申请日：1999-12-27
Applicant: HITACHI CONSTRUCTION MACHINERY
Inventor： TSURUGA YASUTAKA , KANAI TAKASHI , KAWAMOTO JUNYA , HAMAMOTO SATOSHI , OKAZAKI YASUHARU , NAGAO YUKIAKI
Abstract: A hydraulic drive device including a swing control system capable of accelerating it to a stationary state without any jerky swing operation at the time of starting of the swing operation, providing high energy efficiency, forming a stable swing system, and preventing a cost and space from increasing due to provision of additional circuits or complicated problem with circuit configuration from occurring, wherein a pump control device (18) is installed so as to control a discharge flow so that a pump discharge pressure becomes higher by a specified value than the max. load pressures of actuators (2 to 6), pressure compensating valves (12 to 16) are formed so that pressure differences between the discharge pressure of a hydraulic pump (1) and the max. load pressures of the actuators (2 to 6) are set as target compensating pressure differences, respectively, a load dependent characteristic which reduces the target compensating pressure differences when a load pressure rises is provided to the pressure compensating valve (12) of a swing section, and the load dependent characteristic is set so that a flow characteristic simulating the HP constant control of a swing motor can be obtained.
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公开(公告)号：DE69727552T2
公开(公告)日：2004-12-16
申请号：DE69727552
申请日：1997-11-14
Applicant: HITACHI CONSTRUCTION MACHINERY
Inventor： TSURUGA YASUTAKA , KANAI TAKASHI , KAWAMOTO JUNYA
Abstract: A differential pressure PLS between a discharge pressure of a hydraulic pump (2) and a maximum load pressure on a plurality of actuators (3a-3c) is maintained at a target differential pressure DELTA PLSref by a pump capacity control device (5). The target differential pressure DELTA PLSref is modified in accordance with the revolution speed of an engine (1) by conducting to an operation drive unit (32) a differential pressure DELTA Pp across a restriction (50) provided in a discharge passage of a fixed pump (30). An unloading valve (80) comprises first and second auxiliary control pressure chambers (80e, 80f), to which the differential pressure DELTA Pp across the restriction (50) is conducted, and a target differential pressure DELTA Pun for the unloading valve (80) is also modified according to the modification of the target differential pressure DELTA PLSref caused by the operation drive unit (32). Accordingly, a stable load sensing control can be performed without being affected by the engine revolution speed.
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公开(公告)号：DE69727552D1
公开(公告)日：2004-03-18
申请号：DE69727552
申请日：1997-11-14
Applicant: HITACHI CONSTRUCTION MACHINERY
Inventor： TSURUGA YASUTAKA , KANAI TAKASHI , KAWAMOTO JUNYA
Abstract: A differential pressure PLS between a discharge pressure of a hydraulic pump (2) and a maximum load pressure on a plurality of actuators (3a-3c) is maintained at a target differential pressure DELTA PLSref by a pump capacity control device (5). The target differential pressure DELTA PLSref is modified in accordance with the revolution speed of an engine (1) by conducting to an operation drive unit (32) a differential pressure DELTA Pp across a restriction (50) provided in a discharge passage of a fixed pump (30). An unloading valve (80) comprises first and second auxiliary control pressure chambers (80e, 80f), to which the differential pressure DELTA Pp across the restriction (50) is conducted, and a target differential pressure DELTA Pun for the unloading valve (80) is also modified according to the modification of the target differential pressure DELTA PLSref caused by the operation drive unit (32). Accordingly, a stable load sensing control can be performed without being affected by the engine revolution speed.
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公开(公告)号：DE69311239T2
公开(公告)日：1997-10-16
申请号：DE69311239
申请日：1993-02-18
Applicant: HITACHI CONSTRUCTION MACHINERY
Inventor： TANAKA HIROHISA , OSHINA MORIO , KANAI TAKASHI , TANAKA ATSUSHI
Abstract: A hydraulically driving system which comprises: a plurality of flowrate detectors (10A, 10B) for respectively detecting flowrates supplied to a plurality of hydraulic actuators (3A, 3B); valve control devices (11A, 11B) for controlling a plurality of flowrate regulating valves (40A, 40B) such that the flowrates detected by the plurality of flowrate detectors coincide with flowrates instructed by a plurality of control levers (5A, 5B); and pump included rotation control devices (12; 12A-12F) for controlling a discharge flowrate from a hydraulic pump such that the discharge flowrate from the hydraulic pump (1) is less than the total sum of the flowrates instructed by the plurality of control levers by a predetermined flowrate ( DELTA Qref; Xref). The pump inclined rotation control device controls the discharge flowrate of the hydraulic pump (1) by use of flowrate deviations ( DELTA Q1, DELTA Q2) obtained by respectively subtracting the flowrates detected by the flowrate detectors (10A, 10B) from the flowrates instructed by the control levers (5A, 5B).
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公开(公告)号：DE69109250T2
公开(公告)日：1995-09-21
申请号：DE69109250
申请日：1991-07-04
Applicant: HITACHI CONSTRUCTION MACHINERY
Inventor： OCHIAI MASAMI , KANAI TAKASHI
Abstract: A hydraulic drive system wherein a plurality of direction change-over valves (38, 39) include pressure control valves (70, 71) which are respectively disposed between the first paths (44, 45) interconnectable to supply paths (42, 43) through variable restriction portions (52, 53:54, 55) and the second paths (50, 51) interconnectable to load paths (46, 47:48, 49); and control the pressures in the first paths. The pressure control valves include valve bodies (70a, 71a) which have first pressure receiving portions (72a, 73a) being operable in the valve opening direction and disposed in the first control chambers (74a, 75a) for receiving pressures in the first paths and second pressure receiving portions (72b, 73b) being operable in the valve closing direction and disposed in the second control chambers (74b, 75b) for receiving the maximum load pressure as the first control pressure; and third pressure receiving portions (72c, 73c) being operable in the valve closing direction and disposed in the third control chambers (74c, 75c) for receiving the second control pressures and fourth pressure receiving portions (72d, 73d) being operable in the valve opening direction and disposed in the fourth control chambers (74d, 75d) for receiving the third control pressures, respectively.
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