JPS6054238B2 - Cargo handling control device for electric cargo handling vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cargo handling control device for an electric cargo handling vehicle.

In general, the running speed and cargo handling speed of electric forklift trucks powered by storage batteries, whether counter type or reach type, have recently increased.

These vehicles generally use electric motors for driving and cargo handling. Now, in order to increase the cargo handling speed, high-output electric motors and large-capacity pumps are installed to increase the pump discharge volume, but as a result, the lift speed of the fork increases, but the tail
When operating the reach cylinder, the pump pumps out the same amount or more as the lift, which not only makes it impossible to obtain appropriate reach and tail speeds, but also poses a danger to the work. If the rotation of the pump could be controlled by the amount the driver presses the accelerator like in an engine car,
Although it is possible to obtain different cargo handling speeds depending on the work, in ordinary electric vehicles, due to cost considerations, the rotational speed of the pump is uniformly determined by the battery voltage. When the cargo handling lever is operated, the switch is turned on and the motor rotates according to the battery voltage, so oil is delivered from the pump regardless of lift, tail, or reach operations. As described above, when attempting to increase the lift speed, the lift speed unnecessarily increases to the tail speed or reach speed, making the work extremely difficult and dangerous.

In order to solve this problem, the following methods have been conventionally employed, but each method has its own drawbacks. This will be explained below. 11 The lift speed is fast, and in order to appropriately slow down the tail or reach speed,
A method of switching the cargo handling motor field coil to increase the rotation speed for lifts and lower the rotation speed for other cargo handling operations.

This method makes the motor very expensive.

Furthermore, when the lift and reach (or tail) are operated simultaneously, the rotation speed is either one or the other, resulting in poor working surface alignment. 2. Make the tail and reach pipes thinner and increase the piping resistance, and when oil flows into the tail and reach, blow the main relief valve of the valve, that is, return part of the discharge amount to the tank through the relief valve. A method of sending a small amount of oil to the leech or tail to slow it down.

With this method, when the tail or reach is activated, the oil pressure always rises to the relief pressure unnecessarily, which results in high motor current consumption, shortening the battery operating time, and causing the oil temperature to rise rapidly. There is an adverse effect on packing, seals, etc.

It also has drawbacks, such as the generation of noise. There are further improvements to this method as follows. In other words, the hydraulic pressure required for tailing and reaching is lower than for lifting, so in addition to the main relief valve for lifting, relief valves with low setting values are also installed in each section of tailing and reaching, to prevent increases in current consumption and oil temperature. There is a way to lower it even a little. However, in this case the cost of the valve becomes very high. 3. Lower the voltage to the pump motor except when lifting, suppress the rotation speed,
A method to reduce the amount of discharge.

This method uses a resistor to lower the voltage,
Since some terminals of the battery must be used, the efficiency may be reduced or the battery may be damaged.

4. A method of increasing the diameter of the tail and reach cylinder and slowing down the operating speed appropriately.

This method is often difficult in terms of space, disadvantageous in terms of cost, and in practice is often impossible because the cylinder diameter becomes very large.

An object of the present invention is to eliminate the above-mentioned conventional drawbacks, and to improve cargo handling efficiency and reduce power consumption by controlling the load of a cargo handling motor in accordance with each load at each stage of cargo handling work. The purpose of the present invention is to provide a simple and highly economical cargo handling control device.

Hereinafter, an embodiment of the cargo handling control device for a storage battery type forklift truck according to the present invention will be explained based on FIGS. 1 to 4. One fluid pressure (hydraulic as an example) driven by one electric motor A lift cylinder 1, a tail cylinder 2, and a rinichi cylinder 3 as examples of a pump P and a plurality of cylinders driven by the fluid discharged from the pump.
and communication and cutoff between each cylinder and the pump P at 7.
Switching valves 4, 5, corresponding to each cylinder for switching
In order to set the speeds of the cylinders 1, 2, and 3 to different values, a cylinder for low speeds other than the maximum speed cylinder, that is, the lift cylinder 1, that is, a tail cylinder 2, a reach cylinder 9, and a reach cylinder 9 for the cylinder 3 are provided. Bypass passages 5a and 6a for bypassing the fluid from the pump P to the tank T are provided in the corresponding switching valves 5 and 6, respectively. and the lift cylinder 1 and the tail cylinder 2.
The switching valves 4, 5, and 6 corresponding to the reach cylinders 3 are three-position switching valves, and can be switched to three positions by operating handles 4b, 5b, and 6b corresponding to the switching valves. In each of the switching valves 4, 5, and 6, A, b, c, and d are ports communicating with the pump P1 tank T1 cylinder head side and the same rod side, respectively. Note that, since the lift cylinder 1 is a single-acting cylinder, the boat d of the switching valve 4 is closed by an appropriate means. Passages 7, each forming an inverted Y shape, are used to divert high-pressure fluid from boat a to tank T via boat b to valve bodies 5c and 6c corresponding to switching valves 5 and 6.
, 8 are provided. The bypass passages 5a, 6a are carved in lands 5e, 6e located at the center of the spools 5d, 6d of the corresponding switching valves 5, 6, passing through both ends of the lands 5e, 6e, respectively. In the switching valves 5 and 6 corresponding to the reach cylinder 3, in the neutral position of the switching valve (FIG. 2), the lands 5e and 6e are located at the center of the chamber 9, and the high-pressure fluid from the pump or P flows through the passage 7. ,8
, bypass passage 5a or 6a 1 chamber 9, boat b, and then flows into tank T, and at the position where boats A and c are communicated, that is, at the position where boat a communicates with the head side of cylinder 2 or 3 (FIG. 3), the pump The high pressure fluid from P passes through boats A and c to the head side of cylinder 2 or 3, and also to boat a1 passage 7, chamber 9, bypass passage 15a or 6.
The water is divided into tank T via boat a and boat b. Similarly, in the position where boats A and d are connected and high pressure fluid is supplied from pump P to the rod side of cylinder 2 or 3 (Fig. 4), the pressure fluid from pump P passes through boats A and d to cylinder 2 or 3. Also on the rod side are boat A1 passage 8, chamber 9,
Tank T via bypass passage 5a or 6a and boat b
It is divided into two parts. As described above, the bypass passages 5a and 6a
The speed of the cylinders is maintained at the set value by setting the flow rate of the cylinder and limiting the flow rate to the cylinders 2 and 3.
Further, in FIG. 1, 10 is a power storage battery, 4f,
5f and 6f are electrical switches corresponding to the operating handles 4b, 5b, and 6b, respectively, and are configured to be turned off at the neutral position and turned on at the operating position in conjunction with the handles. (However, in the case of lift cylinder 1, it is configured so that it is turned on only when lifting.) Next, to explain the operation, when tilting the lifting frame forward during cargo handling work, tilt cylinder 2 is turned on toward its head side. Send high-pressure fluid to elongate it. For this purpose, operate the operating handle 5b to
is shifted to the boat A, c communication position. At this time, the switch 5f is turned on in conjunction with the movement of the operating handle 5b, and the electric motor M rotates at a rotation rate corresponding to the voltage of the storage battery 10, causing the pump P to discharge a constant flow rate of high-pressure fluid. High-pressure fluid from pump P (high-pressure fluid is shown by a solid line and low-pressure fluid is shown by a broken line) passes through boats A and c to the cap side of cylinder 2, and from boat a via passage 7, bypass passage 5a1 chamber 9, and boat b. The flow is divided into the tanks T, the flow rate of the bypass passage 5a is restricted, and the tail cylinder 2 is extended at a set speed to tilt the elevator frame forward. Also, when extending the reach cylinder 3 to extend the reach, if the switching valve 6 is shifted to the boat A, c communication position using the operating handle 6b in the same manner as above, the high pressure fluid from the pump P is transferred to the cylinder 3 and bypassed. , the flow is divided into the tank T by the passage 6a, and the flow rate to the cylinder 3 is controlled by the flow rate of the bypass passage 6a, and the reach cylinder 3 is extended at a set speed to bring out the reach device. Next, the rearward tilting of the elevator frame and the reach retraction are performed by shortening the tail cylinder 2 and the reach cylinder 3, contrary to the above, and the switching valves 5 and 6 are shifted to the boat A and d communication positions, respectively. Working in the same manner as above, the high pressure fluid from the pump P is diverted to the rod side of the cylinder 2 or 3 and to the tank T by the bypass passage 5a or 6a, and the tail cylinder 2 and reach cylinder 3 are respectively shortened at the set speed. Then tilt the elevator frame backward and retract the reach device. On the other hand, when lifting the lift frame, use the operating handle 4b of the lift cylinder 1 to switch the switching valve 4 to the boat A, C communication position, turn on the switch 4f, and rotate the electric motor M at a rotation corresponding to the voltage of the storage battery 10 to pump the P is rotated to allow the entire discharge flow to flow into the head side of the lift cylinder 1, and the elevator frame is extended at a set speed that is higher than the set speeds of the other tail cylinders 2 and reach cylinders 3 and improves cargo handling efficiency. raise. In the above, Teilt,
The flow rate to each reach cylinder and the amount returned to the tank are determined by the load on the cylinder, piping resistance, and the size of the bypass passages 5a, 6a. Although there is some influence from the fluid temperature, the load and piping resistance are vehicle-specific values, so the cylinder speed is set to a necessary and sufficient value by changing the size of the bypass passage. Furthermore, although this embodiment is applied to a battery-powered reach forklift truck, the present invention is not limited to this; for example, a battery-powered counter forklift truck, a stacking system that has both high-speed lift and low-speed side shift functions with a single motor and pump can be used. When applied to a forklift truck or a battery-powered excavator having both high-speed packet lift and low-speed reach functions, the present invention is constructed in the same manner as described above and operates in the same manner.

As is clear from the above description, in the case of driving a plurality of cargo handling cylinders with the discharge fluid of one pump driven by one electric motor, the present invention provides a pump for cylinders that require high speed for cargo handling efficiency. For cylinders that supply the full discharge amount and require low speed for safety reasons, a bypass passage is provided in the switching valve to limit the flow rate to the cylinder and bring the cylinder speed to the set value. Compared to conventional high-pressure fluid lines equipped with relief valves, the horns are operated at different pressure levels depending on the load on the cargo handling cylinder, significantly reducing power consumption. Moreover, the pressure level is relatively low, the noise in the bypass passage is low, and the structure is simpler than the conventional one, and the manufacturing cost can be reduced.

[Brief explanation of drawings]

The drawings relate to an embodiment of the present invention, and FIG. 1 is a configuration diagram, and FIGS. 2, 3, and 4 are cutaway views showing the operating state of the switching valve. FIG. 2 is a neutral position, and FIG. 4 shows the communication position of boats A and c, and FIG. 4 shows the communication position of boats A and d. 1... Lift cylinder as an example of a maximum speed cylinder, 2... Tail cylinder as an example of a low speed cylinder, 3... Other low speed cylinders Reach cylinder as an example, 4, 5, 6...
...Switching valve, 5a, 6a...Bypass passage, M
...Electric motor, P...Pump, T...
···tank.

Claims (1)

[Claims] 1 One fluid pressure pump P driven by one electric motor M, a plurality of cylinders 1, 2, 3 driven by fluid discharged from the pump, communication between each cylinder and the pump P, and Switching valves 4, 5, and 6 corresponding to each cylinder are provided for switching shutoff, and each cylinder 1,
In order to set the speeds of 2 and 3 to different set values, the fluid from the pump P is bypassed to the tank T by the switching valves 5 and 6 corresponding to the low speed cylinders 2 and 3 other than the highest speed cylinder 1. A cargo handling control device for an electric cargo handling vehicle, characterized in that bypass passages 5a and 6a are provided, respectively.