Abstract: A hydraulic control device for a forklift includes: a plurality of hydraulic mechanisms including a lifting/lowering hydraulic cylinder and a tilting hydraulic cylinder; a hydraulic pump; an electric motor; a discharge control mechanism; a proportional valve; a flow rate control valve; and a controller. When the lifting/lowering hydraulic cylinder performs a lowering operation of the fork and a hydraulic mechanism other than the lifting/lowering hydraulic cylinder simultaneously performs a further operation, the controller controls an open degree of the proportional valve in accordance with a rotation speed difference of a required lowering operation rotation speed for the hydraulic pump, which is required to perform the lowering operation at an instructed speed that is in accordance with an operation amount of the lifting/lowering control member, and a required further operation rotation speed for the hydraulic pump, which is required to perform the further operation.

Abstract: An electromagnetic switching valve, for which the maximum opening is set to be small, is disposed on piping between a lift cylinder and a hydraulic pump motor. A pilot check valve, for which the maximum opening is set to be larger than the electromagnetic switching valve, is disposed on piping, different from the piping, between the lift cylinder and the hydraulic pump motor. In addition, during lowering operations, first, the electromagnetic switching valve is opened, and then after the same is opened, the pilot check valve is opened after a prescribed time has passed. Thus, the shock generated when lowering an object to be raised/lowered is reduced and a fork is operated quickly.

Abstract: A hydraulic control device for a forklift includes a hydraulic pump, a single electric motor for driving the hydraulic pump, an outflow control mechanism provided between a lift cylinder and the hydraulic pump, a flow control valve provided between the outflow control mechanism and a draining portion, and a controller. When a lowering operation of a fork and either forward or rearward mast tilting operations of a mast are performed at the same time, the controller controls the electric motor based on a target speed of the hydraulic pump. The flow control valve controls the flow rate of hydraulic fluid from the lift cylinder to the hydraulic pump and the flow rate from the lift cylinder to the draining portion in accordance with the difference between the actual rotation speed of the hydraulic pump and the target rotation speed of the hydraulic pump.

Abstract: A hydraulic drive device for cargo handling vehicle has: a tank; a pump for drawing in a hydraulic oil from the tank and supplying the hydraulic oil to hydraulic cylinders; an electric motor for driving the pump; a solenoid-controlled proportional valve disposed between an inlet port of the pump and a bottom chamber of an up-and-down hydraulic cylinder and configured to open with a valve travel depending upon a control input of a descent control of an up-and-down control member; a pressure compensation valve disposed between a branch portion located between the pump and the solenoid-controlled proportional valve and the tank and configured to open with a valve travel depending upon a pressure difference between pressures upstream and downstream of the solenoid-controlled proportional valve; and a valve disposed between the pressure compensation valve and the tank and configured to be switched between an open position and a close position.

Abstract: An outlet port of a hydraulic pump/motor and a bottom chamber of a lift cylinder are connected to each other by a hydraulic fluid passage. A hydraulic fluid passage that is connected to a hydraulic fluid tank is formed to branch off the hydraulic fluid passage. A flow control valve controls the hydraulic fluid delivered from the lift cylinder when the fork is lowered, thereby regulating the flow rate of hydraulic fluid supplied to the hydraulic pump/motor and the flow rate of hydraulic fluid supplied to the hydraulic fluid tank. If regenerative operation can be performed, the flow control valve is closed and hydraulic fluid is delivered to the hydraulic pump/motor. If regenerative operation cannot be performed, the flow control valve is opened and hydraulic fluid is delivered to the hydraulic fluid tank. In either case, the fork can be lowered at an instructed speed.

Abstract: A hydraulic control device for a forklift includes: a plurality of hydraulic mechanisms including a lifting/lowering hydraulic cylinder and a tilting hydraulic cylinder; a hydraulic pump; an electric motor; a discharge control mechanism; a proportional valve; a flow rate control valve; and a controller. When the lifting/lowering hydraulic cylinder performs a lowering operation of the fork and a hydraulic mechanism other than the lifting/lowering hydraulic cylinder simultaneously performs a further operation, the controller controls an open degree of the proportional valve in accordance with a rotation speed difference of a required lowering operation rotation speed for the hydraulic pump, which is required to perform the lowering operation at an instructed speed that is in accordance with an operation amount of the lifting/lowering control member, and a required further operation rotation speed for the hydraulic pump, which is required to perform the further operation.

Abstract: An electromagnetic switching valve, for which the maximum opening is set to be small, is disposed on piping between a lift cylinder and a hydraulic pump motor. A pilot check valve, for which the maximum opening is set to be larger than the electromagnetic switching valve, is disposed on piping, different from the piping, between the lift cylinder and the hydraulic pump motor. In addition, during lowering operations, first, the electromagnetic switching valve is opened, and then after the same is opened, the pilot check valve is opened after a prescribed time has passed. Thus, the shock generated when lowering an object to be raised/lowered is reduced and a fork is operated quickly.

Abstract: An outlet port of a hydraulic pump/motor and a bottom chamber of a lift cylinder are connected to each other by a hydraulic fluid passage. A hydraulic fluid passage that is connected to a hydraulic fluid tank is formed to branch off the hydraulic fluid passage. A flow control valve controls the hydraulic fluid delivered from the lift cylinder when the fork is lowered, thereby regulating the flow rate of hydraulic fluid supplied to the hydraulic pump/motor and the flow rate of hydraulic fluid supplied to the hydraulic fluid tank. If regenerative operation can be performed, the flow control valve is closed and hydraulic fluid is delivered to the hydraulic pump/motor. If regenerative operation cannot be performed, the flow control valve is opened and hydraulic fluid is delivered to the hydraulic fluid tank. In either case, the fork can be lowered at an instructed speed.

Abstract: A hydraulic drive device for cargo handling vehicle has: a tank; a pump for drawing in a hydraulic oil from the tank and supplying the hydraulic oil to hydraulic cylinders; an electric motor for driving the pump; a solenoid-controlled proportional valve disposed between an inlet port of the pump and a bottom chamber of an up-and-down hydraulic cylinder and configured to open with a valve travel depending upon a control input of a descent control of an up-and-down control member; a pressure compensation valve disposed between a branch portion located between the pump and the solenoid-controlled proportional valve and the tank and configured to open with a valve travel depending upon a pressure difference between pressures upstream and downstream of the solenoid-controlled proportional valve; and a valve disposed between the pressure compensation valve and the tank and configured to be switched between an open position and a close position.

Abstract: A hydraulic control device for a forklift includes a hydraulic pump, a single electric motor for driving the hydraulic pump, an outflow control mechanism provided between a lift cylinder and the hydraulic pump, a flow control valve provided between the outflow control mechanism and a draining portion, and a controller. When a lowering operation of a fork and either forward or rearward mast tilting operations of a mast are performed at the same time, the controller controls the electric motor based on a target speed of the hydraulic pump. The flow control valve controls the flow rate of hydraulic fluid from the lift cylinder to the hydraulic pump and the flow rate from the lift cylinder to the draining portion in accordance with the difference between the actual rotation speed of the hydraulic pump and the target rotation speed of the hydraulic pump.

Abstract: It is an subject of the present invention to provide a vibration actuator in which a plurality of rotors can be driven by a single vibration unit. When a composite vibrator (2) is driven to generate a composite vibration combining a plurality of vibrations, a first stator (3) and a second stator (4) vibrate, thereby causing elliptical movements in corner portions (8) and (9) of the first stator (3) and the second stator (4), respectively. As a result, a first rotor (A) abutting onto and pressurized against the corner portion (8) of the first stator (3) and a second rotor (B) abutting onto and pressurized against the corner portion (9) of the second stator (4) are rotated at the same time. Further, in this case, by selecting vibration modes of the plurality of vibrations constituting the composite vibration, the two rotors (A) and (B) can be rotated in the same direction or in opposite directions with respect to each other.

Abstract: Provided is an ultrasonic motor capable of realizing high torque. When two terminals are selected from a first terminal (31t), a second terminal (32t), and a third terminal (33t) of a vibrator (3), and AC voltages whose phases are shifted by 90 degrees relative to each other are respectively applied through both of those two terminals, vibration is generated in the stator vibration body (S), and elliptical vibration in a plane corresponding to the selected two terminals is generated at each of a step (9) of a first stator (2) and a corner (11) of a second stator (10), which are in contact with a rotor (6). Since the first stator (2) and the second stator (10) form the single stator vibration body (S), the step (9) of the first stator (2) and the corner (11) of the second stator (10) vibrate in the same vibration mode, rotational force is transmitted from both the step (9) of the first stator (2) and the corner (11) of the second stator (10), and the rotor (6) rotates with high torque.

Abstract: Provided is a vibration actuator in which a plurality of rotors can be driven by a single vibration unit. Two rotors (A) and (B) are attracted toward corresponding stators to be contacted with and pressurized against the corresponding stators (3) and (4), respectively, through a tension of a wire member (8). A composite vibration combining a plurality of vibrations is generated by a composite vibrator (2) to cause elliptical movements in corner portions of the stators (3) and (4). As a result, the two rotors (A) and (B) abutting onto and pressurized against the two stators (3) and (4) are rotated about rotation centers (C1) and (C2) thereof, respectively, at the same time.

Abstract: It is an subject of the present invention to provide a vibration actuator in which a plurality of rotors can be driven by a single vibration unit. When a composite vibrator (2) is driven to generate a composite vibration combining a plurality of vibrations, a first stator (3) and a second stator (4) vibrate, thereby causing elliptical movements in corner portions (8) and (9) of the first stator (3) and the second stator (4), respectively. As a result, a first rotor (A) abutting onto and pressurized against the corner portion (8) of the first stator (3) and a second rotor (B) abutting onto and pressurized against the corner portion (9) of the second stator (4) are rotated at the same time. Further, in this case, by selecting vibration modes of the plurality of vibrations constituting the composite vibration, the two rotors (A) and (B) can be rotated in the same direction or in opposite directions with respect to each other.

Abstract: Provided is a vibration actuator in which a plurality of rotors can be driven by a single vibration unit. Two rotors (A) and (B) are attracted toward corresponding stators to be contacted with and pressurized against the corresponding stators (3) and (4), respectively, through a tension of a wire member (8). A composite vibration combining a plurality of vibrations is generated by a composite vibrator (2) to cause elliptical movements in corner portions of the stators (3) and (4). As a result, the two rotors (A) and (B) abutting onto and pressurized against the two stators (3) and (4) are rotated about rotation centers (C1) and (C2) thereof, respectively, at the same time.

Abstract: Provided is an ultrasonic motor capable of realizing high torque. When two terminals are selected from a first terminal (31t), a second terminal (32t), and a third terminal (33t) of a vibrator (3), and AC voltages whose phases are shifted by 90 degrees relative to each other are respectively applied through both of those two terminals, vibration is generated in the stator vibration body (S), and elliptical vibration in a plane corresponding to the selected two terminals is generated at each of a step (9) of a first stator (2) and a corner (11) of a second stator (10), which are in contact with a rotor (6). Since the first stator (2) and the second stator (10) form the single stator vibration body (S), the step (9) of the first stator (2) and the corner (11) of the second stator (10) vibrate in the same vibration mode, rotational force is transmitted from both the step (9) of the first stator (2) and the corner (11) of the second stator (10), and the rotor (6) rotates with high torque.