Abstract: A hydraulic system is capable of improving the acceleration performance of a slewing motor and suppressing an increase in the flow rate of hydraulic fluid supplied to the slewing motor. The hydraulic system includes a slewing speed sensor that detects a slewing speed of a slewing body and a controller that controls a slewing motor capacity, which is a capacity of the slewing motor. The controller controls the slewing motor capacity so as to make the slewing motor capacity when the slewing speed is in a low speed range be greater than the slewing motor capacity when the slewing speed is in a high speed range.

Abstract: A hydraulic system is capable of improving the acceleration performance of a slewing motor and suppressing an increase in the flow rate of hydraulic fluid supplied to the slewing motor. The hydraulic system includes a slewing speed sensor that detects a slewing speed of a slewing body and a controller that controls a slewing motor capacity, which is a capacity of the slewing motor. The controller controls the slewing motor capacity so as to make the slewing motor capacity when the slewing speed is in a low speed range be greater than the slewing motor capacity when the slewing speed is in a high speed range.

Abstract: In a power control device, when the necessary power is greater than an upper limit value and either the integral power value or the duration time of an assist provided by an electric storage device during a continuous assist by the electric storage device exceeds a predetermined first threshold value, a controller performs a first control of reducing an assist power by the electric storage device to a value smaller than an assist power for the regular control and greater than zero. Further, when the necessary power is greater than the upper limit value and either the integral power value or the duration time exceeds a predetermined second threshold value greater than the first threshold value, the controller performs a second control of setting the assist power to zero.

Abstract: A hydraulic control device includes: a recovery oil passage; a regenerative motor that rotates an output shaft of an engine in response to a supply of the hydraulic fluid and is driven to rotate by rotation of the output shaft of the engine; a regenerative oil passage for guiding return oil from a boom cylinder to the regenerative motor without passing the return oil through the recovery oil passage; a coupling oil passage that couples the recovery oil passage and the regenerative oil passage to each other; and a regeneration-side check valve that is provided on the coupling oil passage, and allows the hydraulic fluid to flow from the recovery oil passage toward the regenerative motor, and moreover restricts the hydraulic fluid from flowing from the regenerative motor toward the recovery oil passage.

Abstract: Provided is a hydraulic shovel capable of moving a boom, an arm, and a bucket at respective adequate speeds even during complex operations thereof, without a significant pressure loss. This hydraulic shovel includes: a first pump (31) connected to a boom actuator (24) and a bucket actuator (28); a second pump (32) connected to an arm actuator (26) and the boom actuator (24); a third pump (33) connect to the arm actuator (26); a boom control valve (54) interposed between the first pump (31) and the boom actuator (24); an arm control valve (56) interposed between the second pump (32) and the arm actuator (26); a bucket control valve (58) interposed between the first pump (31) and the bucket actuator (28); a boom merging valve (55) for speed increase interposed between the second pump (32) and the boom actuator (24); and an arm merging valve (57) for speed increase interposed between the third pump (33) and the arm actuator (26).

Abstract: In a power control device, when the necessary power is greater than an upper limit value and either the integral power value or the duration time of an assist provided by an electric storage device during a continuous assist by the electric storage device exceeds a predetermined first threshold value, a controller performs a first control of reducing an assist power by the electric storage device to a value smaller than an assist power for the regular control and greater than zero. Further, when the necessary power is greater than the upper limit value and either the integral power value or the duration time exceeds a predetermined second threshold value greater than the first threshold value, the controller performs a second control of setting the assist power to zero.

Abstract: Provided is a hydraulic shovel capable of moving a boom, an arm, and a bucket at respective adequate speeds even during complex operations thereof, without a significant pressure loss. This hydraulic shovel includes: a first pump (31) connected to a boom actuator (24) and a bucket actuator (28); a second pump (32) connected to an arm actuator (26) and the boom actuator (24); a third pump (33) connect to the arm actuator (26); a boom control valve (54) interposed between the first pump (31) and the boom actuator (24); an arm control valve (56) interposed between the second pump (32) and the arm actuator (26); a bucket control valve (58) interposed between the first pump (31) and the bucket actuator (28); a boom merging valve (55) for speed increase interposed between the second pump (32) and the boom actuator (24); and an arm merging valve (57) for speed increase interposed between the third pump (33) and the arm actuator (26).

Abstract: A hydraulic control device includes: a recovery oil passage; a regenerative motor that rotates an output shaft of an engine in response to a supply of the hydraulic fluid and is driven to rotate by rotation of the output shaft of the engine; a regenerative oil passage for guiding return oil from a boom cylinder to the regenerative motor without passing the return oil through the recovery oil passage; a coupling oil passage that couples the recovery oil passage and the regenerative oil passage to each other; and a regeneration-side check valve that is provided on the coupling oil passage, and allows the hydraulic fluid to flow from the recovery oil passage toward the regenerative motor, and moreover restricts the hydraulic fluid from flowing from the regenerative motor toward the recovery oil passage.

Abstract: A controller includes a storage unit that stores a map in which an operation amount and an upper limit value of suction torque of a hydraulic pump are associated with each other, for each operation content identified by a cylinder that is an operation object out of the cylinders, and by a direction of operation performed on this cylinder; an operation torque determination unit that determines the upper limit value of suction torque for each cylinder by using the map stored in the storage unit when an actuation command relating to at least one cylinder is input by an operation lever; a high-level selection unit that selects the maximum upper limit value of suction torque out of the upper limit values of suction torque determined by the operation torque determination unit; and a regulator that regulates a displacement of the hydraulic pump so as to obtain torque equal to or lower than the suction torque selected by the high-level selection unit.

Abstract: A hydraulic drive device capable of utilizing return oil effectively while maintaining a driven speed of a hydraulic actuator, as well as a working machine having the hydraulic drive device, are provided. The hydraulic drive device includes a controller. During an external force applying period in which a return oil pressure exceeds a discharge pressure from a hydraulic pump, the controller specifies a regenerating flow rate capable of being conducted to a regeneration oil passage and a surplus flow rate other than the regenerating flow rate on the basis of power required of the hydraulic pump out of return oil other than return oil which is conduced to a tank through a control valve, then conducts the return oil of the regenerating flow rate to the regeneration oil passage and controls an MO valve and a regulator so that the return oil of the surplus flow rate is conducted to an outlet oil passage.

Abstract: A controller includes: a storage unit that stores a map in which an operation amount and an upper limit value of suction horsepower of a hydraulic pump are associated with each other, for each operation content identified by a cylinder that is an operation object out of the cylinders, and by a direction of operation performed on this cylinder; an operation horsepower determination unit that determines the upper limit value of suction horsepower for each cylinder by using the map stored in the storage unit when an actuation command relating to at least one cylinder is input by an operation lever; a high-level selection unit that selects the maximum upper limit value of suction horsepower out of the upper limit values of suction horsepower determined by the operation horsepower determination unit; and a regulator that regulates a displacement of the hydraulic pump so as to obtain horsepower equal to or lower than the suction horsepower selected by the high-level selection unit.

Abstract: A hydraulic drive device capable of utilizing return oil effectively while maintaining a driven speed of a hydraulic actuator, as well as a working machine having the hydraulic drive device, are provided. The hydraulic drive device includes a controller. During an external force applying period in which a return oil pressure exceeds a discharge pressure from a hydraulic pump, the controller specifies a regenerating flow rate capable of being conducted to a regeneration oil passage and a surplus flow rate other than the regenerating flow rate on the basis of power required of the hydraulic pump out of return oil other than return oil which is conduced to a tank through a control valve, then conducts the return oil of the regenerating flow rate to the regeneration oil passage and controls an MO valve and a regulator so that the return oil of the surplus flow rate is conducted to an outlet oil passage.

Abstract: With respect to a method of controlling a pump flow rate of a hydraulic pump, a method having a small flow rate command value is selected between a pressure feedback control for controlling the pump flow rate based on a set pressure (a cutoff pressure) and a pump pressure, and, an ordinary control for controlling the pump flow rate based on operation information, and in a case that the pressure feedback control is selected, a flow rate increasing control for increasing the flow rate command value after the case with the passage of time is performed.

Abstract: A tire HIL simulator is provided which is capable of, in a testing apparatus where a vehicle model is incorporated into a tire testing apparatus, reproducing the behavior of a tire which corresponds to the three-dimensional behavior of a vehicle, even if a three-dimensional vehicle model is used. As a device for resolving this, this tire HIL simulator includes a tire testing apparatus 2 and a controller 3 connected mutually. The tire testing apparatus 2 conducts a running test on a tire 4a using a mimic road surface body 4, and includes a side force measuring device 37 for measuring a tire side force and each actuator which gives a contact load, a side-slip angle and a camber angle, respectively.

Abstract: A tire HIL simulator is provided which is capable of, in a testing apparatus where a vehicle model is incorporated into a tire testing apparatus, reproducing the behavior of a tire which corresponds to the three-dimensional behavior of a vehicle, even if a three-dimensional vehicle model is used. As a device for resolving this, this tire HIL simulator includes a tire testing apparatus 2 and a controller 3 connected mutually. The tire testing apparatus 2 conducts a running test on a tire 4a using a mimic road surface body 4, and includes a side force measuring device 37 for measuring a tire side force and each actuator which gives a contact load, a side-slip angle and a camber angle, respectively.

Abstract: With respect to a method of controlling a pump flow rate of a hydraulic pump, a method having a small flow rate command value is selected between a pressure feedback control for controlling the pump flow rate based on a set pressure (a cutoff pressure) and a pump pressure, and, an ordinary control for controlling the pump flow rate based on operation information, and in a case that the pressure feedback control is selected, a flow rate increasing control for increasing the flow rate command value after the case with the passage of time is performed.

Abstract: A hydraulic control system of the present invention comprising control valves for controlling the direction and flow rate of pressure oil discharged from a hydraulic pump, hydraulic actuators which the pressure oil is fed to and controlled by the control valves, the hydraulic actuators including hydraulic cylinders and a hydraulic motor, and a first return passage provided as a passage for returning return oil present at the head side of one of the hydraulic cylinders to the tank, the first return passage being in communication with the tank, and a second return passage for returning return oil from each of the other hydraulic actuators including the hydraulic motor except for the hydraulic cylinders to the tank, the second return passage having a back pressure check valve and a replenishing passage, the replenishing passage being configured so as to provide a back pressure developed by the back pressure check valve to the low pressure side of each of the other hydraulic actuators to prevent cavitations.

Abstract: A control device for a working machine according to the present invention comprises a capacity variable pump for supplying working oil, a controller for controlling the discharge amount of the pump, a control valve for controlling the working oil discharged from the pump, a hydraulic actuator operated by the working oil from the control valve, an operating lever for operating the hydraulic actuator, and a relief valve to be operated when the pressure of the working oil is a relief pressure or more. The controller has a dynamic emulation model of a hydraulic driving device, and is constituted to estimate the pressure oil flow rate passing through the relief valve from the emulation model according to the operation amount of the operating lever, and to control the pump flow rate of the pump so that the relief flow rate estimation value gets close to zero. According to this, relief loss can be precisely reduced without generating a response delay or pressure loss, and the power can be saved.

Abstract: A hydraulic control system of the present invention comprising control valves for controlling the direction and flow rate of pressure oil discharged from a hydraulic pump, hydraulic actuators which the pressure oil is fed to and controlled by the control valves, the hydraulic actuators including hydraulic cylinders and a hydraulic motor, and a first return passage provided as a passage for returning return oil present at the head side of one of the hydraulic cylinders to the tank, the first return passage being in communication with the tank, and a second return passage for returning return oil from each of the other hydraulic actuators including the hydraulic motor except for the hydraulic cylinders to the tank, the second return passage having a back pressure check valve and a replenishing passage, the replenishing passage being configured so as to provide a back pressure developed by the back pressure check valve to the low pressure side of each of the other hydraulic actuators to prevent cavitations.

Abstract: A control device for a working machine according to the present invention comprises a capacity variable pump for supplying working oil, a controller for controlling the discharge amount of the pump, a control valve for controlling the working oil discharged from the pump, a hydraulic actuator operated by the working oil from the control valve, an operating lever for operating the hydraulic actuator, and a relief valve to be operated when the pressure of the working oil is a relief pressure or more. The controller has a dynamic emulation model of a hydraulic driving device, and is constituted to estimate the pressure oil flow rate passing through the relief valve from the emulation model according to the operation amount of the operating lever, and to control the pump flow rate of the pump so that the relief flow rate estimation value gets close to zero. According to this, relief loss can be precisely reduced without generating a response delay or pressure loss, and the power can be saved.