JPH055658U - Hydraulic system for electric industrial vehicles - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a hydraulic device for an electric industrial vehicle that can reduce the number of motors to reduce costs, further reduce noise, and realize energy saving. [Structure] The cargo handling pump 1 of the cargo handling apparatus is also used as a power steering pump for power steering (PS), and oil is passed through a flow divider 4 with load sensing to a steering control valve 5 (power cylinder 6).
And supply to the cargo handling equipment. Further, the drive motor 3 of the cargo handling pump 1 is driven by a chopper. [Effect] Since the cargo handling pump 1 is used also as the PS pump, the PS pump / motor and the attached wirings, connectors, etc. can be eliminated, and thus a significant cost reduction can be achieved, and also in the vehicle. A large space can be secured. Further, in order to secure the same PS flow rate, since the cargo handling pump 1 having a large normal capacity is used, the rotation speed may be low, noise can be significantly reduced, and energy saving can be achieved.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a hydraulic system for an electric industrial vehicle equipped with a power steering and a cargo handling device.

[0002]

[Prior Art]

 Conventionally, in an electric industrial vehicle typified by the electric forklift, a total of three DC motors are generally used for driving, cargo handling (hydraulic equipment drive) pumps and hydraulic power steering (PS) pump drive. It is used. In addition, recently, a chopper, which is widely used for driving motors, is used to drive the motor for driving the cargo handling pump, and the operability is controlled steplessly according to the movement of the cargo handling lever. Excellent vehicles have been developed.

[0003]

[Problems to be solved by the device]

 However, even in such a vehicle, three motors are required as drive motors, which is a great disadvantage in terms of cost and space.

Further, the PS motor is driven so that the total oil flow rate is supplied from the PS pump even when the PS is not operated, and there is a problem in terms of noise and energy saving. The present invention solves the above problems, and an object of the present invention is to provide a hydraulic device for an electric industrial vehicle that can reduce the number of motors to reduce the cost, further reduce noise, and save energy. is there.

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, a hydraulic system for an electric industrial vehicle according to the present invention is a hydraulic system for an electric industrial vehicle equipped with power steering and a cargo handling device, wherein the cargo handling pump of the cargo handling device is connected to the power steering device. It is also characterized in that it is also used as a power steering pump and the drive motor of this cargo handling pump is driven by a chopper.

[0006]

[Action]

 According to the above configuration of the present invention, the cargo handling pump of the cargo handling apparatus is also used as the power steering pump of the power steering, so that the number of motors is reduced, the cost and space are improved, and the cargo handling pump is also improved. By using a chopper-driven drive motor, the flow rate of oil supplied from the cargo handling pump can be controlled steplessly, and when only power steering is used, it operates at a low speed (low flow rate) and the cargo handling equipment is When it is used, it is operated by increasing the flow rate. Therefore, noise when using only power steering is reduced and energy saving is realized.

[0007]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a power steering hydraulic circuit diagram of a hydraulic system for an electric industrial vehicle showing an embodiment of the present invention. The power steering shown in FIG. 1 uses a known semi-integral type in which a steering control valve and a power cylinder are separated.

In FIG. 1, reference numeral 1 denotes a cargo handling pump driven by a cargo handling motor 2, which supplies oil from an oil tank 3 to a flow divider 4 with load sensing. The flow divider with load sensing 4 always secures the power steering (PS) flow rate as a priority flow rate and divides the supplied oil into the steering control valve 5 and the cargo handling device (not shown) to supply the oil. The steering control valve 5 is integrally attached to the lower part of the steering gear case, and operates the power cylinder 6 according to the steering operation to return the oil to the oil tank 3.

FIG. 2 shows a drive circuit diagram of the cargo handling motor 2. The cargo handling motor 2 is connected in series to a fuse 7 and a chopper 8, and this series circuit is connected to both ends of the battery 9, and to both ends of the cargo handling motor 2 and the fuse 7 are a capacitor 10 and a resistor 11 connected in series. The circuit of the diode 12 connected in parallel is connected. Further, the controller 13 of the chopper 8 is connected to both ends of the battery 9. The controller 13 is connected with a key switch 14, a direction switch 15, an angle detector 16 for the cargo handling lever, and a load sensing contact 41 of the flow divider 4 with load sensing.

The operation of the above configuration will be described. When the controller 13 confirms that the key switch 14 or the direction switch 15 has been turned on, the minimum flow rate of the oil supplied from the cargo handling pump 1 reaches the minimum required standby flow rate, so that the minimum flow rate indicated by A in FIG. The chopper 8 is controlled by the flow rate to drive the motor 2. In this state, the standby flow rate is supplied from the cargo handling pump 1 to the steering control valve 5 via the flow divider 4 with load sensing.

Next, when the controller 13 confirms the operation of the load sensing contact 41 by the steering operation, in order to secure the flow rate required for PS operation, the flow rate of the chopper 8 is changed as shown by B in FIG. Increase slightly. In this state, the flow rate required for PS operation is supplied to the steering control valve 5 via the flow divider 4 with load sensing.

Next, when the controller 13 confirms the operation of the cargo handling lever by the analog signal of the cargo handling lever angle detector 16, it is proportional to the input cargo handling lever angle and is output from the chopper 8 as shown in FIG. 3C. Increase the flow rate. In this state, the flow rate required for PS operation is supplied to the steering control valve 5 via the flow divider 4 with load sensing, and the flow rate required for the cargo handling equipment is supplied to the cargo handling equipment via the flow divider 4 with load sensing. To be done.

Further, when the angle of the cargo handling lever becomes maximum, the controller 13 sets the maximum flow rate as shown in D of FIG. In this way, the cargo handling pump 1 of the cargo handling apparatus can be used also as the PS pump, and therefore the PS pump / motor and the attached wiring, connector, etc. can be eliminated, resulting in a significant cost reduction. It is also possible to secure a large space inside the vehicle. Also, in order to secure the same PS flow rate, since the cargo handling pump 1 with a large capacity is normally used, low rotation is required, and it is only necessary to adjust the rotation speed only during PS operation, and when PS is not operated. Since it is only necessary to ensure low-speed rotation, that is, to secure a standby flow rate, noise can be significantly reduced and energy can be saved compared to the conventional method.

Although the flow divider 4 with load sensing is used in this embodiment, a combination of the flow divider and a pressure switch for detecting the pressure at the inlet of the steering control valve 5 may be used. At this time, a pressure switch is connected to the controller 13 instead of the load sensing contact 41 of the flow divider 4 with load sensing.

[0015]

[Effect of the device]

 According to the present invention having the above-described configuration, by using the cargo handling pump of the cargo handling device as the power steering pump of the power steering, the power steering pump / motor and the attached wiring, connector, etc. can be eliminated. The cost can be significantly reduced and a large space can be secured inside the vehicle. Also, by using a chopper drive for the cargo handling pump drive motor, the flow rate of oil supplied from the cargo handling pump can be controlled steplessly, and when only the power steering is used, it can be operated at a low flow rate. Noise can be reduced when using only the steering wheel, and energy can be saved.

[Brief description of drawings]

FIG. 1 is a power steering hydraulic circuit diagram of a hydraulic system for an electric industrial vehicle showing an embodiment of the present invention.

FIG. 2 is a drive circuit diagram of a cargo handling motor of the hydraulic system of the electric industrial vehicle.

FIG. 3 is an operation characteristic diagram of a cargo handling motor of the hydraulic system of the electric industrial vehicle.

[Explanation of symbols]

 1 Pump for cargo handling 2 Motor for cargo handling 3 Oil tank 4 Flow divider with load sensing 5 Steering control valve 6 Power cylinder 8 Chopper 9 Battery 13 Controller 14 Key switch 15 Direction switch 16 Angle sensor of cargo handling lever 41 Load sensing contact

Claims (1)

Claims for utility model registration: Claims: 1. A hydraulic system for an electric industrial vehicle equipped with power steering and a cargo handling device, wherein the cargo handling pump of the cargo handling device also serves as the power steering pump of the power steering. The hydraulic system for an electric industrial vehicle is characterized in that the drive motor for the cargo handling pump is a chopper drive.