Provided is a work machine capable of achieving both low fuel consumption and ensuring of workability. The work machine is configured to, in a state where an output of an engine or hydraulic pump has increased to an increase threshold (S12: Yes) with the rotational speed being at a first rotational speed (S11: Yes), raise the rotational speed from the first rotational speed to a second rotational speed (S13); in a process of raising the rotational speed to the second rotational speed, output, to a regulator, a signal instructing reduction in the discharge rate (S14) so as to keep the output of the engine or hydraulic pump constant; and after the rotational speed has reached the second rotational speed, output, to the regulator, a signal instructing increase in the discharge rate (S16) so as to make the output of the engine or hydraulic pump have a value corresponding to a request load.

In a control unit of a hydraulic control device, a workload calculation unit calculates the amount of workload cut in a first pump when supply of first oil from the first pump to a continuously variable transmission mechanism through a check valve is switched to supply of second oil from a second pump to the continuously variable transmission mechanism. A workload determination unit determines whether the amount of workload loss of an ACG is more than the amount of workload cut. A motor controller stops a motor or decreases a rotation number if the workload determination unit determines that the amount of workload loss is more than the amount of workload cut.

A hydraulic system, a mobile mining machine and to a method of controlling a hydraulic actuator is provided. The hydraulic system includes two hydraulic pumps (P1, P2) for generating hydraulic power for a hydraulic actuator. The pumps are powered by means of a common electric motor. Operation of the actuator is controlled by controlling speed and direction of the motor, whereby hydraulic lines (19a, 19b) may be without actively controlled control valves.

Control system for a Continuously Variable Transmission with two pairs of conical sheaves each with an adjustable running radius, the sheave of each pair being coupled to a hydraulic actuator and the inlet port of each actuator being connected with the hydraulic actuator setting means, fed from the outlet port of a hydraulic displacement pump, connected to a supply of hydraulic medium and coupled to an electric motor which is controlled by a controller which controls the speed of the electric motor with a first control signal which is generated as a function of the actual transmission ratio of the transmission on one hand and of the desired speed of change of this transmission ratio on the other hand, all this in such a way that the speed of this first motor increases with an increase of the transmission ratio of the transmission on one hand and an increase of the speed of change of the ratio on the other hand, while the outlet port of the displacement pump is connected to the inlet of an electronically controllable pressure relief valve of which the set point is determined by a second control signal as a function of the set transmission ratio on one hand and the value of the actual torque transmitted through the transmission on the other hand, in such a way that de value of the resulting hydraulic pressure increases as the transmission ratio increases on one hand, and as the torque transmitted through the transmission increases on the other hand.

The invention relates to a method for controlling the driving engine (M) and hydraulic pumps (PUMP1, PUMP2) of a hydraulic machine (10), the method comprising: driving at least one hydraulic variable displacement pump (PUMP1, PUMP2) that supplies pressurized medium to the hydraulic system of the machine by the driving engine (M), determining the working pressure pi, p2) and volume flow (Qip, Q2p) output from at least one hydraulic pump (PUMP1, PUMP2), determining the torque (T-ip, T2p) required of at least one hydraulic pump (PUMP1, PUMP2) or the total torque (Tpk0k) required by two or more hydraulic pumps (PUMP1, PUMP2) by means of the working pressure (p-i, p2) and volume flow (Qip, Q2p) of pressurized medium output from at least one hydraulic pump (PUMP1, PUMP2), as well as the rotation speed (i) of the driving engine (M); controlling the rotation speed (i) of the driving engine (M) and the displacement (V1p, V2p) of at least one hydraulic pump (PUMP1, PUMP2) automatically so that the torque (Td, Tdeff) produced by the driving engine approaches the torque (Tip, T2p) required by at least one hydraulic pump (PUMP1, PUMP2) driven by the driving engine (M), or the total torque (Tpk0k) of two or more hydraulic pumps (PUMP1, PUMP2) in such a way that the volume flow (Q1p, Q2p) produced by at least one hydraulic pump (PUMP1, PUMP2) will remain unchanged. The invention also relates to a system for controlling the driving engine (M) and hydraulic pumps (PUMP1, PUMP2) of a hydraulic machine (10), as well as a pile driving rig comprising the system according to the invention.

A hydraulic excavator drive system includes: a first pump connected to a head-side chamber of a boom cylinder; and a second pump that supplies hydraulic oil to one of, or both, an arm cylinder and a bucket cylinder. The first pump is driven by an electric motor. The drive system further includes a switching valve that is in a first position at a boom raising operation and in a second position at a vehicle body lifting operation. The first position is a position in which the switching valve brings a rod-side chamber of the boom cylinder into communication with a tank, and the second position is a position in which the switching valve brings the rod-side chamber into communication with the second pump.

In a control unit of a hydraulic control device, a workload calculation unit calculates the amount of workload cut in a first pump when supply of first oil from the first pump to a continuously variable transmission mechanism through a check valve is switched to supply of second oil from a second pump to the continuously variable transmission mechanism. A workload determination unit determines whether the amount of workload loss of an ACG is more than the amount of workload cut. A motor controller stops a motor or decreases a rotation number if the workload determination unit determines that the amount of workload loss is more than the amount of workload cut.

A dynamic system for a lifting apparatus is disclosed. The dynamic system includes a first motor and a second motor decoupled from the first motor. During the ascent of the lifting apparatus, only the first motor is involved in the driving of the lifting apparatus. During the descent of the lifting apparatus, only the second motor is involved in charging the battery system. Since the first motor and the second motor are decoupled from each other, the first motor can have a high driving efficiency and the second motor can have a high power generation efficiency, the problem that when only one motor is adopted, the motor needs to balance between the driving efficiency and power generation efficiency is solved. The energy recovery rate of this invention can be increased from 10% in the prior art to about 30%.

Control system for a Continuously Variable Transmission with two pairs of conical sheaves each with an adjustable running radius, the sheave of each pair being coupled to a hydraulic actuator and the inlet port of each actuator being connected with the hydraulic actuator setting means, fed from the outlet port of a hydraulic displacement pump, connected to a supply of hydraulic medium and coupled to an electric motor which is controlled by a controller which controls the speed of the electric motor with a first control signal which is generated as a function of the actual transmission ratio of the transmission on one hand and of the desired speed of change of this transmission ratio on the other hand, all this in such a way that the speed of this first motor increases with an increase of the transmission ratio of the transmission on one hand and an increase of the speed of change of the ratio on the other hand, while the outlet port of the displacement pump is connected to the inlet of an electronically controllable pressure relief valve of which the set point is determined by a second control signal as a function of the set transmission ratio on one hand and the value of the actual torque transmitted through the transmission on the other hand, in such a way that de value of the resulting hydraulic pressure increases as the transmission ratio increases on one hand, and as the torque transmitted through the transmission increases on the other hand.

A hydraulic drive system for operating a hydraulic cylinder in first and second movement profiles. A hydraulic drive unit includes first and second hydraulic machines, each with first and second connections. In the first movement profile, a first cylinder chamber of the hydraulic cylinder is fluidly connected to a first fluid reservoir and a second cylinder chamber is fluidly connected to the second connection of the second hydraulic machine. In the second movement profile, the first connection of the first hydraulic machine is connected to the second connection of the second hydraulic machine.