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 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 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.
摘要:
When the pump pressure detected through a pressure detecting line 48 is raised higher than a first predetermined pressure Pd1, a recovery switching valve 44 is shifted to a valve-closed position to cease the recovery function. At this time, the pump delivery pressure detected through a pressure detecting line 51 is higher than a second predetermined pressure Pd1* close to the first predetermined pressure Pd1, and an engine speed increasing device 52 controls an engine controller 11 to increase the rotational speed of an engine 10, thereby increasing the pump delivery rate. Thus, it is possible to make small speed change of an actuator and to increase working efficiency with no deterioration in operability, even when a recovery function is ceased.
摘要:
A plurality of directional control valves (5, 6) respectively disposed between a hydraulic pump (50) and a plurality of actuators (3, 4) each comprises a pump port (9), a pressure chamber (10), a feeder passage (11), actuator ports (12a, 12b), a reservoir port (13), first meter-in variable restrictors (15a, 15b) disposed between the pump port and the pressure chamber, and a pressure compensating valve (16) disposed between the pressure chamber and the feeder passage and having a pair of opposite ends, one of which is subjected to a pressure in the pressure chamber and the other of which is subjected to a maximum load pressure among the plurality of actuators. The hydraulic pump (1) includes a pump flow control device (2) for controlling a delivery rate of the hydraulic pump so that a delivery pressure of the hydraulic pump is held higher by a predetermined value than the maximum pressure obtained, as a load sensing pressure, from load pressures of the plurality of actuators. At least one of the plurality of directional control valves has a bleed passage (21) for communicating between the feeder passage (11) and the reservoir port (13), and second variable restrictors (22a, 22b) disposed in the bleed passage and moved in conjunction with the first meter-in variable restrictors, making it possible to prevent abrupt operation of the actuator adapted for driving an inertial body, and suppress vibration produced in a circuit even when any of the pump delivery rate and the load pressure is fluctuated.
摘要:
In a controller (229) of a hydraulic control system for construction machines, a valve control signal calculating function (301) works such that when an operation pattern signal (A-I) for actuators (201, 202 . . . ) is outputted, it selects corresponding one of plural output patterns for an auxiliary valve control pressure stored, as a function of a differential pressure signal between a pump delivery pressure and a maximum load pressure, in relation to the operation pattern signals, followed by calculating an auxiliary valve control pressure (Pc) dependent upon the differential pressure signal based on the selected output pattern, and also selects corresponding one of plural sets of rates of change (K . . . , K . . . ) for the auxiliary valve control pressure stored in relation to the operation pattern signals, followed by combining the calculated auxiliary valve control amount with the selected set of speed changes to calculate each of valve control signals (S21-S26).