Abstract: Provided is an apparatus to lower a load, comprising a hydraulic pump, a hydraulic actuator having first and second ports, a manipulation device, a hydraulic circuit including meter-in and meter-out flow passages for the first and second ports respectively and a regeneration flow passage with a check valve, a control valve, a meter-out flow controller adjusting a meter-out flow rate according to the manipulation device, a back pressure valve, and a non-regeneration operation relief valve whose set pressure is not less than a sum of a minimum set pressure of the back pressure valve, an inlet-outlet pressure difference of the meter-out flow controller when the meter-out flow rate is maximum and a discharge flow rate of the hydraulic pump is maximum, and an actuator pressure difference for driving the hydraulic actuator with no load, and not less than a maximum set pressure of the back pressure valve.

Abstract: An engine control apparatus includes a governor and a controller which derives a lever operation-related rotational speed control target value derives an accelerator operation-related rotational speed control target value-corresponding to a detected operation amount of the accelerator member, based on an accelerator operation/rotational speed correlation function defining a relationship between the rotational speed control target value and the operation amount of the accelerator member; performs a lower value selection for selecting a lower one of the derived lever operation-related rotational speed control target value and accelerator operation-related rotational speed control target value; and causes the governor to control the rotational speed of the engine such that the rotational speed of the engine is set to the rotational speed control target value selected by the lower value selection.

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: To stop, in an emergency, a revolving superstructure quickly from rotating while preventing damage of a mechanical brake. A revolving superstructure is driven swiveling using a permanent magnetic-type swiveling electric motor; in an emergency, such as a malfunction in a drive or control system for the swiveling electric motor, allowing electric power generated in the electric motor due to inertial rotation to be consumed in an external braking resistor so as to make an electric braking action; and a mechanical brake is activated to stop the rotation and hold the stopped revolving superstructure when a rotation speed of the revolving superstructure becomes equal to or lower than a preset value.

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 hydraulic control system for a working machine according to the present invention comprises a hydraulic pump for supplying working oil to a hydraulic actuator through a control valve, a relief mechanism disposed on the discharge side of the pump, the relief mechanism assuming an open state when a pump discharge pressure which varies according to the pump flow rate exceeds a predetermined pressure and assuming a closed state when the pump discharge pressure becomes the predetermined one or lower, an ordinary control means for controlling the pump flow rate in accordance with working information, and a pressure feedback control means for controlling the pump flow rate in accordance with the pump discharge pressure. In this system, out of controls performed by both control means, control wherein the flow rate by one control becomes smaller than that of the other is selected, thereby opening/closing control of the relief mechanism is performed.

Abstract: To stop, in an emergency, a revolving superstructure quickly from rotating while preventing damage of a mechanical brake. A revolving superstructure is driven swiveling using a permanent magnetic-type swiveling electric motor; in an emergency, such as a malfunction in a drive or control system for the swiveling electric motor, allowing electric power generated in the electric motor due to inertial rotation to be consumed in an external braking resistor so as to make an electric braking action; and a mechanical brake is activated to stop the rotation and hold the stopped revolving superstructure when a rotation speed of the revolving superstructure becomes equal to or lower than a preset value.

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: In a neutral range preset, there are set a zone for stopping and holding a rotating body only by a mechanical brake, a zone for holding the body only by performing position holding control, and a zone for simultaneously exerting both effects, i.e., the effect of the mechanical brake and the effect of the holding control. On-the-spot holding torque generated when the position holding control is performed is stored. The higher of the on-the-spot holding torque stored and accelerating torque according to an operation amount of the body at a rotation starting time is set as electric motor torque for acceleration. When performing a pressing work including pressing a bucket against an object for work, torque control is carried out according to the operation amount.

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: In a neutral range preset, there are set a zone for stopping and holding a rotating body only by a mechanical brake, a zone for holding the body only by performing position holding control, and a zone for simultaneously exerting both effects, i.e., the effect of the mechanical brake and the effect of the holding control. On-the-spot holding torque generated when the position holding control is performed is stored. The higher of the on-the-spot holding torque stored and accelerating torque according to an operation amount of the body at a rotation starting time is set as electric motor torque for acceleration. When performing a pressing work including pressing a bucket against an object for work, torque control is carried out according to the operation amount.

Abstract: In a construction machine comprising an electric motor 6 for driving a rotational system, an operating member for instructing an operation of the electric motor 6, and a controller 9 for controlling the electric motor 6 according to an operation command from the operating member, the controller 9 has an emulation model 9a for simulating dynamic characteristics of a hydraulic rotation driving device in real time, and a target value for control is calculated from the emulation model 9a according to the operation command from the operating member to control the electric motor 6. Accordingly, the electric motor can mildly respond to the operation of a lever in an intermediate range and swiftly respond to a quick operation of the lever.

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 hydraulic control system for a working machine according to the present invention comprises a hydraulic pump for supplying working oil to a hydraulic actuator through a control valve, a relief mechanism disposed on the discharge side of the pump, the relief mechanism assuming an open state when a pump discharge pressure which varies according to the pump flow rate exceeds a predetermined pressure and assuming a closed state when the pump discharge pressure becomes the predetermined one or lower, an ordinary control means for controlling the pump flow rate in accordance with working information, and a pressure feedback control means for controlling the pump flow rate in accordance with the pump discharge pressure. In this system, out of controls performed by both control means, control wherein the flow rate by one control becomes smaller than that of the other is selected, thereby opening/closing control of the relief mechanism is performed.

Abstract: The present invention relates to a control system and method for a hydraulic working machine characterized by having a construction wherein a flow discharge control valve is disposed in a discharge-side pipe line of a main flow control valve, the amount of operation of an operating lever is converted to a pilot pressure by a remote controlled valve, the pilot pressure is then input to a controller and is calculated into a pressure change speed as operation speed, in a pressure change speed calculator, further, the operation speed is calculated into an electromagnetic valve current in an electromagnetic valve current calculator, then the electromagnetic proportional valve current is output to an electromagnetic proportional valve from a command unit, and the degree of opening of the discharge flow control valve is controlled with a secondary pressure in the electromagnetic proportional valve.

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: The present invention relates to a control system and method for a hydraulic working machine characterized by having a construction wherein a flow discharge control valve is disposed in a discharge-side pipe line of a main flow control valve, the amount of operation of an operating lever is converted to a pilot pressure by a remote controlled valve, the pilot pressure is then input to a controller and is calculated into a pressure change speed as operation speed, in a pressure change speed calculator, further, the operation speed is calculated into an electromagnetic valve current in an electromagnetic valve current calculator, then the electromagnetic proportional valve current is output to an electromagnetic proportional valve from a command unit, and the degree of opening of the discharge flow control valve is controlled with a secondary pressure in the electromagnetic proportional valve.