摘要:
A hydraulic drive system for hydraulic working machines has a variable displacement hydraulic pump, at least one actuator driven by the hydraulic fluid, a directional control valve of center bypass type for controlling the flow of the hydraulic fluid, a center bypass line for connecting the center bypass passage of the control valve to a reservoir and a fixed restrictor disposed in the center bypass line. A first control signal that determines a first target displacement of the hydraulic pump is determined by using the pressure generated by the fixed restrictor. A second control signal is generated for determining a second target displacement of a hydraulic pump. A third control signal, which is the larger one of the first and second control signals, provides a target displacement that is applied to a pump regulator that controls the displacement of the hydraulic pump. A metering characteristic as good as the conventional one can be obtained in the case of a light load, and a satisfactory metering characteristic can be achieved in the case of a heavy load, as a result.
摘要:
A hydraulic recovery device in a hydraulic system having a pump (1) driving a plurality of actuators through a plurality of control valves (2, 3), the hydraulic recovery device comprising a variable resistance valve (6, 60) in a first line being controlled by a control signal (Px), a third line, a check valve (7) disposed in the third line for allowing the hydraulic fluid to flow only in a direction from the first line toward the second line. The hydraulic recovery device further comprises (a) detecting apparatus (101; 106; 102a, 102b; 103a, 103b) for detecting a condition variable (Pd; Ph; Pia1, Pia2; Pib1, Pib2) related to an operation of the actuator (4); (b) control apparatus (100; 100A-100H) for receiving a signal from the detecting apparatus and producing a drive signal (i; i*) corresponding to the condition variable based on a relationship stored therein in advance; and (c) control signal generating apparatus (105) for receiving the drive signal and producing the control signal (Px) corresponding to the drive signal, whereby the device can optionally set a characteristic of the variable resistance valve and can avoid abrupt changes in a recovered flow rate.
摘要:
In a hydraulic drive system for a construction machine, first flow control mechanism includes first and second flow control valves (11a, 11b) and first interlock mechanism (54, 55) for interlocking the first and second flow control valves with first directional control mechanism (7), and second flow control mechanism includes third and fourth flow control valves (12a, 12b) and second interlock mechanism (56, 57) for interlocking the third and fourth flow control valves with second directional control mechanism (9). First pressure control mechanism includes at least first pressure control valve (13a) operated in response to a pressure signal in a valve-closing direction, and second pressure control mechanism includes only second pressure control valve (15b) operated in response to the pressure signal in a valve-closing direction. A first hydraulic pump (25a) is connected to a first actuator (19) via the first flow control valve (11a), the first pressure control valve (13a) and the first directional control mechanisms (7), and a second hydraulic pump ( 25b) is connected to the first actuator (19) via the second flow control valve (11b) and the first directional control mechanism (7). The first hydraulic pump (25a) is also connected to a second actuator (21) via the third flow control valve (12a) and the second directional control mechanism (9) in parallel to the first actuator (19) without passing any pressure control valve, and the second hydraulic pump (25b) is also connected to the second actuator (21) via the fourth flow control valve (12b), the second pressure control valve (15b) and the second directional control mechanism (9) in parallel to the first actuator (19).
摘要:
A hydraulic control valve apparatus including a flow control valve having a pair of variable throttles, a feeder passage, a pair of load passages, directional control valve devices comprise a seat valve having a seat valve body movably disposed in a housing to form an auxiliary variable throttle in the feeder passage, and a control variable throttle (33) formed in the seat valve body for changing an opening area in accordance with an amount of movement of the seat valve body; (b) a pilot line (24, 29-31, 35-37) for communicating a portion (7C) of the feeder passage upstream of the auxiliary variable throttle with a downstream portion (7A, 7B) of the feeder passage through the control variable throttle to determine the amount of movement of the seat valve body in accordance with a flow rate of the hydraulic fluid passing through the pilot line; and (c) pilot flow control (400; 401; 403; 405; 406; 407; 408) having a pilot variable throttle (45) disposed in the pilot line and input (800; 52-59; 159, 54-59; 231A, 231B, 251, 252) for receiving a flow restricting signal whereby an opening area of the pilot variable throttle is changed in accordance with the received flow restricting signal to control a flow rate of the hydraulic fluid passing through the pilot line.
摘要:
For enabling a boom to be smoothly raised during the triple combined operation of boom-up, arm-crowd and bucket-crowd in a hydraulic circuit system for a hydraulic excavator, in a first valve group of a hydraulic valve apparatus (12), a variable throttle valve (70) is installed in a feeder passage (32) of a bucket directional control valve (21) downstream of a load check valve (32a), and a secondary pressure C as a boom-up operation command is introduced through a line (71) to a pilot control sector (70a) of the variable throttle valve (70) which sector operates in the throttling direction, so that when the secondary pressure C is 0 or small, the variable throttle valve (70) is fully opened and, as the secondary pressure C increases, an opening area of the variable throttle valve (70) is reduced to restrict the flow rate of a hydraulic fluid supplied through the bucket directional control valve (21).
摘要:
A hydraulic drive system comprises a controller (12) and several condition sensors. A boom-up target flow rate setting section determines a boom-up target flow rate based on signals from a pressure sensor (11) and a rotational speed meter (16), a pump delivery rate detecting section determines a pump delivery rate based on signals from a tilt angle sensor (15) and the rotational speed meter (16), a differential pressure detecting section and a center bypass flow rate calculating section determine a center bypass flow rate based on signals from pressure sensors (9, 10), a boom cylinder calculating section determines a boom cylinder flow rate from the pump delivery rate and the center bypass flow rate, and a first pump target displacement volume calculating section calculates a first pump target tilt angle .theta..sub.1 in accordance with the difference between the boom-up target flow rate and the boom cylinder flow rate. In this case, .theta..sub.1 is larger than a second pump target tilt angle .theta..sub.2 for negative control and is selected by a maximum value selecting section. Then, a minimum value selecting section selects the smaller one of .theta..sub.1 and a maximum tilt angle .theta..sub.max determined with horsepower control, and drive signal generating section outputs a corresponding target current to a solenoid proportional valve (13) for driving a piston (6a) of a regulator (6) to the right in FIG. 4.
摘要:
Assessment information needed to calculate a used vehicle assessment value of a hydraulic excavator 10 is input to a portable telephone 20 and is then transmitted from the portable telephone 20. The transmitted assessment information is received at a manufacturer's base station 40 at a remote location. The used vehicle assessment value of the hydraulic excavator 10 is calculated based upon the received assessment information, and history information and operation information on the hydraulic excavator 10 read out from an operation information database 43 and a history database 42 in correspondence to an ID number assigned to the hydraulic excavator which is included in the assessment information.
摘要:
A method for outputting failure handling method includes: detecting conditions of each part of a working machine; transmitting condition signals representing the detected conditions; receiving the condition signals; calculating a handling method for a failure showed by the received condition signals; and transmitting a handling signal representing the calculated handling method.
摘要:
A tournament oil path constituting apparatus in which while a laminated block is constituted by laminating a number of oil path plates, a number of shuttle valve holes and connection grooves made continuous to the shuttle valve holes are formed at overlap faces of the oil path plates, shuttle valves are integrated to the shuttle valve holes, introductory oil paths communicating with the shuttle valve holes are formed at both of the oil path plates formed with the shuttle valve holes and the oil path plates having match faces on sides of the shuttle valve holes and a high pressure oil is selected by the shuttle valves from pressure oils conducted both of the introductory oil paths and conducted to the connection grooves. The tournament oil path constituting apparatus also including a number of main paths penetrating the number of laminated oil path plates and branch grooves branched from the main paths.
摘要:
In the arm-crowding or track operation, a calculating portion (700d2 or 700d4) calculates a modification gain (KAC or KTR) depending on an operation pilot pressure and a calculating portion (700g) calculates a decrease modification (DND) based on the KAC or KTR, while a calculating portion (700m or 700p) calculates a modification gain (KACH or KTRH) depending on an operation pilot pressure and calculating portions (700q-700s) calculate an increase modification (DNH) based on the KACH or KTRH. A reference target engine revolution speed NR0 is modified using the DND and DNH. In other operations than the arm-crowding and track operations, NR0 is modified using only the decrease modification (DND) calculated from the modification gain just depending on the operation pilot pressure. In the operation where an engine revolution speed is desired to become higher as an actuator load increases, the engine revolution speed can be controlled in accordance with change of the actuator load as well. In other operations, the engine revolution speed can be controlled just depending on the direction and input amount in and by which corresponding operation instructing apparatus is operated.