JP3155158B2 - Battery-powered forklift - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery type forklift capable of improving safety.

[0002]

2. Description of the Related Art In general, a battery-powered forklift using a battery as a driving source turns on / off a connection between a driving system such as an electric motor for traveling and cargo handling and a battery by turning on / off a key switch. Enables and disables system startup. Therefore, when the key switch is off, the forklift cannot travel and cannot lift, lower, or tilt a load support such as a fork.

[0003]

By the way, the forklift not only stops the forklift at a safe place when the cargo handling operation is completed, but also moves the fork a to the lowermost position as shown in FIG. It is often required by safety regulations or the like that the vehicle is brought into contact with the fork a in such a manner that the vehicle is brought into contact with the fork a in a safe stop state by contacting the vehicle with the ground while tilting forward at the angle θ.

However, it is often the case that the forklift is stopped by turning off the key switch while the fork is tilted backward, without keeping the safe stop state. In such a case, since the drive system is shut off and the fork a of the forklift cannot be tilted forward as it is, it is necessary to perform a troublesome key operation such as turning on the key switch again and further turning off the key switch after the operation. There was a problem.

The present invention has been devised in view of such a problem, and is based on the fact that a fork operation is performed for a fixed time and for a fixed time even after the key switch is turned off. It is an object of the present invention to provide a battery-powered forklift that can easily realize the above-described safe stop state without requiring the operation of a switch, and can solve the above-mentioned problems.

[0006]

According to the present invention, a tilt cylinder for tilting a load support such as a fork with respect to a road surface, a pump for supplying hydraulic oil to the tilt cylinder, and a motor control circuit are provided. An electric motor connected to a battery via a motor, a switching valve interposed between the tilt cylinder and the pump and operable to be switched by tilt operation means, and the motor control circuit and the motor control circuit. In a battery-powered forklift provided with a key switch for turning on and off a connection with a control power supply circuit capable of supplying control power, the control power supply circuit detects a key switch off operation to set a predetermined delay time. Timer means for measuring the delay time, and the control power supply is controlled by the motor control during the period from the start of the delay time measurement to the end of the time measurement. And the motor control circuit drives the electric motor only by inputting a tilt forward operation signal based on an operation of tilting the load supporter of the tilt operation means during the delay time. A battery-operated forklift characterized in that:

According to a second aspect of the present invention, a tilt cylinder for tilting a load support such as a fork with respect to a road surface, a pump for supplying hydraulic oil to the tilt cylinder are driven, and a battery is supplied to the battery via a motor control circuit. An electric motor to be connected, an electromagnetic switching valve interposed between the tilt cylinder and the pump and having a solenoid control circuit are provided, and the control power is supplied to the motor control circuit and the solenoid control circuit. In a battery-operated forklift having a key switch for turning on and off a control power supply circuit, the control power supply circuit may measure a preset delay time by detecting an off operation of the key switch. A timer means, and the control power supply is supplied to the motor control circuit from the start of timing of the delay time to the end of timing. And the motor control circuit drives the electric motor by inputting a tilt forward tilt operation signal for tilting the load support of the tilt operating means forward during the delay time. The solenoid control circuit is a battery type forklift characterized in that the solenoid is energized so as to open the electromagnetic switching valve in a direction in which the tilt forward operation is performed.

The invention according to claim 3 further comprises a lift cylinder for raising and lowering a load support such as a fork with respect to a road surface;
An electric motor that drives a pump that supplies hydraulic oil to the lift cylinder and is connected to a battery via a motor control circuit; and an electromagnetic switching valve that is interposed between the lift cylinder and the pump and has a solenoid control circuit. A battery-operated forklift provided with a key switch that switches on and off a connection between the motor control circuit and the solenoid control circuit and a control power supply circuit that can supply control power to the motor control circuit and the solenoid control circuit. Timer means capable of measuring a preset delay time by detecting an OFF operation of a key switch, and controls the control power supply to the motor control circuit and the solenoid control during a period from the start to the end of the delay time. Circuit, while the motor control circuit, during the delay time, To drive the electric motor with the input of the lift lowering operation signal for lowering the support,
The solenoid control circuit is a battery type forklift characterized in that a solenoid is excited so as to open the electromagnetic switching valve in a direction in which the lift lowering operation is performed.

[0009]

The control power supply circuit can supply control power to the motor control circuit during a delay time after the key switch is turned off, and the motor control circuit can control the load support of the tilt operation means during the delay time. The electric motor can be driven by input of a tilt forward tilt operation signal for tilting the tool forward. In other words, even after the key switch is turned off, the load support can be tilted forward without turning on the key switch again within a fixed delay time.

The invention according to claim 2 or 3 controls the electromagnetic switching valve when the switching valve interposed between the tilt cylinder or the lift cylinder for tilting or lifting the load support and the pump and the pump is an electromagnetic switching valve. By supplying control power to the solenoid control circuit within the delay time, the load support can be tilted forward and down within the delay time even after the key switch is turned off.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; As shown in FIG. 1, a tilt cylinder 3 for tilting a load support 2 such as a fork of a battery-type forklift (not shown) with respect to a road surface, and hydraulic oil for the tilt cylinder 3 are provided. And a switching valve 5 interposed between the tilt cylinder 3 and the pump P. The electric motor M drives a pump P that supplies the motor P, and is connected to a battery BA via a motor control circuit 4.

The forklift is, for example, a counterbalance type forklift that can tilt the load support 2 by tilting the well-known mast member MT forward with the tilt cylinder 3. It is also possible to employ a type in which the load support 2 can be directly tilted forward by the tilt cylinder 3 like a forklift of a type.

In the present embodiment, the switching valve 5 is a manual switching valve which is manually operated. By operating a tilt lever 6 as a tilt operating means, the tilt forward tilt port P1 is operated.
And the tilt port P2 after tilting can be appropriately switched, and after the operation, can be automatically returned to the neutral position by a spring.

In the present embodiment, the tilt lever 6 is provided with a tilt forward tilt operation detector 7 composed of a limit switch. By being applied, the key switch KS can output the tilt forward operation signal S1 to the motor control circuit 4 described later while the tilt forward operation is performed regardless of the on / off state of the key switch KS. .

The pump P is connected to an electric motor M
And supplies hydraulic oil to the tilt cylinder 3. The electric motor M is connected to the battery BA via the motor control circuit 4.

The motor control circuit 4 can receive the control power (VB + in this example) from the control power supply circuit 10 and can drive the electric motor M in response to the input of the tilt forward tilt operation signal S1.

Although not shown, the motor control circuit 4 includes, for example, a lift signal for moving the load support 2 up and down,
When the forklift is a reach type forklift, a reach signal or the like for moving the load support 2 back and forth is input, and the electric motor M can be driven based on such various signals.

In the present embodiment, the control power supply circuit 10 bypasses the key switch KS, and the first connection path L1 to which the battery voltage VB is constantly input from the + side of the battery BA.
A second output signal VS1 of the key switch KS so that the on / off operation of the key switch KS can be detected.
When the output signal VS1 is zero, it is possible to detect that the key switch KS has been turned off. Such a key switch KS
In this example, the output signal VS1 is also input to the motor control circuit 4, so that the motor control circuit 4 can also detect that the key switch KS is turned off.

In the conventional battery-powered forklift, when the output signal VS1 is zero, that is, when the key switch KS is off, the control power supply circuit 10
The supply of control power to the motor control circuit 4 was immediately cut off.

The control power supply circuit 10 includes a key switch KS
And a timer means 10A capable of measuring a preset delay time by detecting an OFF operation of the timer. The timer means 10A can store and hold a preset time (for example, 60 seconds as a time within one hour) as the delay time T, and detect that the output VS1 of the key switch KS becomes zero. Timing of the delay time T may be started.

The control power supply circuit 10 can supply the control power supply (VB + in this example) to the motor control circuit 4 from the start of the time measurement of the delay time T to the end of the time measurement.

When the key switch KS is turned on, the control power supply circuit 10 detects this by the key switch output VS1 and sends the control power supply VB + to the motor control circuit 4.
Can be supplied. During this time, when the tilt lever 6 performs the tilt forward operation, the port of the switching valve 5 is switched to the tilt forward tilt port P1, while the tilt forward operation detector 7 sends the tilt control signal S1 to the motor control circuit 4. Is output.

When the control power is supplied and the motor control circuit 4 receives the tilt forward tilt operation signal S1, the motor control circuit 4 rotates the electric motor M by passing a current thereto, and the hydraulic oil discharged from the pump P is supplied to the switching valve 5 The port P1 is supplied to the bottom of the tilt cylinder 3 to extend the piston rod, and the load support 2 can be tilted forward.

Next, when the key switch KS is turned off,
The control power supply circuit 10 detects this by the key switch output VS1, and can supply control power to the motor control circuit 4 immediately after the key switch is turned off until the delay time T.

The motor control circuit 4 includes a key switch KS
Can be detected by the output signal VS1 and the electric motor M can be driven only by the input of the tilt forward operation signal S1 based on the operation of the tilt lever 6 during the delay time T. As described above, the tilt forward operation can be performed.

Accordingly, after the key switch KS is turned off, the tilt forward operation can be performed within the delay time, and after the delay time T has elapsed, the control power supply circuit 10 supplies control power to the motor control circuit 4. Is stopped and all operations can be prohibited, so there is no safety problem. Note that the delay time T
In this embodiment, the time is set to 60 seconds, but an appropriate time such as about 1 minute or more or less than 1 hour can be adopted.

Further, during this delay time T, the safety can be further improved by prohibiting any other cargo handling operation other than tilting forward.

The lift lowering operation for lowering the load support 2 can be performed irrespective of the state of the key switch by using a manually operated type such as the tilt switching valve of the present embodiment for the lift switching valve.

Next, FIG. 2 shows a hydraulic circuit for each of the tilt and the lift for explaining one embodiment of the second and third aspects of the present invention, and FIG. 3 shows an electric block diagram. . As shown in the figure, in the present embodiment, in addition to the tilt cylinder 3, a lift cylinder 1 that can lift and lower the load support 2 is provided.
The switching of the hydraulic oil to 1 exemplifies the proportional electromagnetic switching valves 12 and 13.

First, in this hydraulic circuit, hydraulic oil discharged from a pump P which is driven to rotate by an electric motor M passes through a sequence valve 14 and a proportional solenoid switch valve 12 for tilt and a proportional solenoid switch valve 13 for lift And a return flow path R1 returning to the tank T is formed.

The return flow path R1 is connected to the sequence valve 1
First branch flow path R2 branched into two on the upstream side of
And the second branch flow path R3. The first branch flow path R2 is connected to the return flow path R1 via a relief valve 15 that releases excess hydraulic oil in the hydraulic circuit, and the second branch circuit R3 is connected to the input side by a pressure reducing valve 16 from the input side. The pilot hydraulic oil having a low output pressure is connected to the pilot flow path R4 of each of the proportional electromagnetic control valves 12 and 13.

When the pressure of the pilot hydraulic oil reaches a predetermined value, the sequence valve 14 permits the flow from the inlet side to the outlet side to conduct the return flow path R1, and the conduction causes the return flow path R1 to flow through the pipeline. When the hydraulic oil pressure decreases, the valve is closed again, so that the downstream pressure can always be maintained at a constant high pressure.

Each of the proportional electromagnetic switching valves 12 and 13 comprises a valve spool 16 and a pair of solenoid valves 17 and 19 capable of displacing the valve spool 16. The solenoid valves 17 and 19 are supplied with pilot operating oil via a pilot line R4, while the tilt operation lever 2 is
0, the control current proportional to the operation amount of the lift operation lever 21 (shown in FIG. 3) is controlled by the solenoids SOL1-2 and SOL3-.
When the power is supplied to the spool 4, a secondary pressure that is proportional to the control current signal value and moves the valve spool 16 is generated to increase or decrease the hydraulic passage opening area inside the spool, thereby controlling the hydraulic oil flow rate. is there.

The proportional electromagnetic switching valve 13 for the lift
Is supplied to the bottom of the lift / lift cylinder 11 via the poppet valve 22. This poppet valve 22
A type of seat valve with a conical valve body that can move perpendicular to the orifice opening surface, can completely stop hydraulic oil leakage when fully closed, and is effective in inching and descent when lifting and stopping the lift This is preferable in that it can be prevented from occurring.

FIG. 3 shows an electrical block diagram of FIG.
In this embodiment, a solenoid control circuit 23 is provided in addition to the circuit configuration of FIG. The solenoid control circuit 23 receives the key switch output VS1 and the control power supply VB (+) from the control power supply circuit 10. The other parts are the same as those in FIG. 1 and the description is omitted.

The solenoid control circuit 23 receives voltage signals from potentiometers 25 and 26 which can detect the operation amounts of the tilt operation lever 20 and the lift lever 21 as voltage signals. Note that the solenoid control circuit 23
Is configured to output a chopper signal CH capable of controlling the rotation of the electric motor M to the motor control circuit 4 in the present embodiment,
3 to output a control signal for exciting the solenoids SOL1 to SOL4 of the solenoid valves.

The operation of the present embodiment will be described. When the key switch KS is turned on, the key switch output VS1 becomes a predetermined voltage value. A control power supply VB (+) is supplied to the solenoid control circuit 23.

When the tilt operation lever 20 is tilted forward, the operation amount is detected by the potentiometer 25 as a tilt forward tilt operation signal S 1, and is input to the solenoid control circuit 23 as a voltage value.

The solenoid control circuit 23 outputs a chopper signal CH for driving the electric motor M based on the voltage value of the potentiometer 25, and the motor control circuit 4 receiving this outputs the electric motor M based on the chopper signal CH. Can be driven.

The solenoid control circuit 23 controls the solenoid SOL1 to open the valve spool 16 in such a direction that the proportional electromagnetic switching valve 12 performs the tilt forward operation.
A control signal for exciting SOL2 is output.

The pair of solenoid valves 17, 19 can generate a secondary pressure for moving the valve spool 16 to the tilt forward operation port P3 by excitation of the solenoids SOL1, SOL2.

By a series of such operations, hydraulic oil proportional to the operation amount is supplied to the bottom of the tilt cylinder 3, and
The piston rod of the tilt cylinder 3 is extended to enable a tilt forward tilting operation. The lift lowering operation is also realized by the same operation as the tilt forward operation.

Next, when the key switch KS is turned off, the control power supply circuit 10, the motor control circuit 4B, and the solenoid control circuit 23 detect these by the key switch output VS1, and set a predetermined delay time T. Start timing. During the delay time T from the start of timing to the end of timing, the control power supply circuit 10 can supply control power to the motor control circuit 4 and the solenoid control circuit 23.

If the tilt forward operation of the tilt operation lever 20 is performed during the delay time T, in this embodiment, the potentiometer 25 as a tilt forward operation detector is provided.
Can detect this, and outputs a tilt forward operation signal S1 to the solenoid control circuit 23, and the key switch K
It operates in the same manner as when S is on, and implements a forward tilt.

Further, the above-described tilt forward operation can be similarly realized for the lift lowering operation. That is, when the lift lowering operation of the lift operating lever 21 is performed during the delay time T, the potentiometer 26 as a lift lowering operation detector can detect this, and the lift lowering operation signal S
2 is output to the solenoid control circuit 23.

The solenoid control circuit 23 outputs a chopper signal CH capable of driving the electric motor M and opens the valve spool 16 in a direction in which the proportional electromagnetic switching valve 13 performs the lift lowering operation. , And SOL4.

The pair of solenoid valves 17 and 19 of the proportional electromagnetic switching valve 13 generate a secondary pressure for moving the valve spool 16 to the lift lowering operation port P4 by exciting the solenoids SOL3 and SOL4. Hydraulic oil proportional to the volume can be delivered from the bottom of the lift cylinder 3.

Therefore, the piston rod of the lift cylinder 11 can be contracted, and the lift lowering operation can be performed.

As described above, in this embodiment, during the delay time after the key switch KS is turned off, both the forward tilt of the tilt and the lowering of the lift can be realized, and the safe stop state can be secured.

[0050]

As described above, the battery-operated forklift of the present invention performs a minimum cargo-handling operation only for ensuring the safe stop state of the forklift within a certain period of time even after the key switch is turned off. As a result, safety can be improved, and troublesome operations such as turning on and off the key switch again are not required, and operability can be improved.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit and an electric block diagram showing an embodiment of the invention of claim 1;

FIG. 2 is a hydraulic circuit diagram showing one embodiment of the second and third aspects of the present invention.

FIG. 3 is an electric block diagram showing one embodiment of the invention according to claims 2 and 3;

FIG. 4 is a conceptual diagram for explaining a conventional technique.

[Explanation of symbols]

 2 Load Support 3 Tilt Cylinder 4 Motor Control Circuit 5 Switching Valve 6 Tilt Operating Lever 7 Tilt Forward Tilt Operation Detector 9 Main Switch 10 Control Power Circuit 11 Lift Cylinder 12 Electromagnetic Switching Valve 13 Electromagnetic Switching Valve 23 Solenoid Control Circuit P Pump BA Battery KS Key switch M Electric motor

Claims (3)

(57) [Claims] 1. A tilt cylinder for tilting a load support such as a fork with respect to a road surface, and an electric motor which drives a pump for supplying hydraulic oil to the tilt cylinder and is connected to a battery via a motor control circuit. A switching valve interposed between the tilt cylinder and the pump and switchable by tilt operation means, and the motor control circuit and a control power supply circuit capable of supplying control power to the motor control circuit. A battery-powered forklift provided with a key switch for turning on and off the connection between the control switch, the control power supply circuit includes timer means capable of measuring a preset delay time by detecting an off operation of the key switch; and While the control power can be supplied to the motor control circuit from the start of timing of the delay time to the end of timing, the motor A battery-powered forklift, wherein the control circuit drives the electric motor only by inputting a tilt forward tilt operation signal based on an operation of tilting the load supporter forward by tilt operating means during the delay time. 2. A tilt cylinder for tilting a load support such as a fork with respect to a road surface, and an electric motor which drives a pump for supplying hydraulic oil to the tilt cylinder and is connected to a battery via a motor control circuit. Providing an electromagnetic switching valve interposed between the tilt cylinder and the pump, and having a solenoid control circuit, a control power supply circuit capable of supplying control power to the motor control circuit and the solenoid control circuit, and A battery-powered forklift provided with a key switch for turning on and off the connection between the control power supply circuit, the control power supply circuit includes timer means capable of measuring a preset delay time by detecting the off operation of the key switch, and From the start of timing of the delay time to the end of timing, the control power is supplied to the motor control circuit and the solenoid control. And the motor control circuit drives the electric motor by inputting a tilt forward tilt operation signal for tilting the load support of the tilt operating means during the delay time, and the solenoid control A battery type forklift, wherein a circuit excites a solenoid to open the electromagnetic switching valve in a direction to perform the tilt forward tilting operation. 3. A lift cylinder for raising and lowering a load support such as a fork with respect to a road surface, and an electric motor which drives a pump for supplying hydraulic oil to the lift cylinder and is connected to a battery via a motor control circuit. Providing an electromagnetic switching valve interposed between the lift cylinder and the pump and having a solenoid control circuit, between the motor control circuit and the solenoid control circuit, and a control power supply circuit capable of supplying control power thereto. A battery-powered forklift provided with a key switch for turning on and off the connection, wherein the control power supply circuit includes timer means capable of measuring a preset delay time by detecting an off operation of the key switch; From the start of time measurement to the end of time measurement, the control power is supplied to the motor control circuit and the solenoid control circuit. The motor control circuit drives the electric motor by inputting a lift lowering operation signal for lowering the load supporter of the lift operating means during the delay time, and the solenoid control circuit A battery-powered forklift, wherein a solenoid is excited to open the electromagnetic switching valve in a direction in which a lift lowering operation is performed.