JPH028958Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tail speed control device for a battery type forklift truck.

In the conventional hydraulic circuit of this type of forklift truck, the hydraulic operating valve is generally provided with a micro switch that operates on and off in conjunction with the operating lever, and the contactor is excited by the signal from this micro switch. Due to this, there were many methods in which battery power was directly connected to the hydraulic motor.

However, in this system, since the hydraulic motor always rotates at full speed according to the load on the hydraulic system, the speed of the hydraulic system needs to be controlled only by throttling the hydraulic circuit using the lever of the hydraulic operating valve.

For this reason, in a counterbalanced forklift where the mast is tilted back and forth using a tilt cylinder, if the same lever operation is performed during high-lift as when low-lift, the forward/backward tilting frequency wave speed will be large, especially when the mast is under load. Because the overall inertia is large, there are disadvantages in terms of operability and safety, such as large swings of the shock, mast, and vehicle body when the tail is operated.

There is also a conventional forklift truck that uses chopping control of the motor, but in this case as well, the motor is controlled at a constant ratio regardless of the height of the mast, so it has not been possible to improve the above-mentioned drawbacks of the conventional method. The current situation is that this is not the case.

The present invention was developed in view of the above circumstances, and its purpose is to obtain an appropriate tail speed that does not impair workability when the lift is low, and to reduce the mast and car body when the lift is high. To provide a tailing speed control device for a lift truck, which allows a safe tailing speed with little shaking to be obtained.

The present invention will be explained below with reference to the drawings. 2 in the drawing is a fixed mast member of the mast device A, and 10
1 is a movable mast member that moves up and down the fixed mast member 2, and 11 is a fork. A lifting height micro switch 1 is attached to the fixed mast member 2.
The movable mast member 10 is equipped with a lifting height micro switch 1.
A cam 3 is installed to turn on the power.

The mast device A is provided with a swinging fulcrum B at the bottom, and the vehicle body 12 is provided with a tail cylinder 13 for operating the front and rear tilting of the mast device A.

The mast device A is provided with a lift cylinder 14 that operates the vertical movement of the movable mast member 10.

7 in the drawing is a hydraulically operated valve, a pump port 15 of this hydraulically operated valve 7 is connected to the discharge side of a pump 16 via a pipe line 17, and a tank port 18 of the hydraulically operated valve 7 is connected to a pipe line 19. It communicates with the tank 20 through the tank 20.

The connection ports 21 and 22 of the hydraulically operated valve 7 are connected to the pipe line 2
3, 24 to the tail cylinder 13, and other connection ports 25, 2 of the hydraulically operated valve 7.
6 is connected to the lift cylinder 14 via pipes 27 and 28.
It is connected to. In the drawing, 8 is a lift micro switch, and 9 is a tail micro switch.

The operation signals of the lift microswitch 8, the tilt microswitch 9, and the lift height microswitch 1 are input to the input section of the chopper controller 6.

The chopper controller 6 includes an AND gate 30 into which signals from the lift micro switch 1 and the tail micro switch 9 are input, and a signal obtained by inverting the signal from the lift micro switch 1 by an inverter 31 and a tail gate. An AND gate 32 is provided to which a signal from the microswitch 9 is input.

Switching transistors Tr ₂ and Tr ₁ are connected to the output sides of these AND gates 30 and 32, respectively.
When Tr ₁ becomes conductive, a signal A having a voltage set by the resistor R ₁ is input to the oscillation circuit 33, and when the switching transistor Tr ₂ is conductive, a signal B having a voltage set by the resistor R ₂ is input to the oscillation circuit 33.

The oscillation circuit 33 outputs a signal A' with a large chopping ratio when the signal A is input, and outputs a signal B' with a small chopping ratio when the signal B is input to the chopper circuit 34, and the chopper circuit 34 drives the pump 16. The rotation of the motor 4 is controlled.

Note that 5 in the figure is a power supply.

Further, the signal from the lift micro switch 8 is inputted to a lift control circuit (not shown) provided in the chopper controller 6 to control the speed during lift.

Next, the operation will be explained. When the movable mast member 10 is at a position lower than the fixed lift height H, the lift height micro switch 1 is turned off, so one AND gate 30 of the chopper controller 6 is set to "0".
Then, "1" is input to the other AND gate 32.

In this state, when the hydraulic operating valve 7 is operated to tail the mast device A, the tail micro switch 9 is turned on, so that a signal "1" is input to the AND gates 30 and 32.

Due to this signal "1", only the AND gate 32 whose one input is "1" outputs the signal "1" on the output side, so this signal "1" makes the switching transistor Tr ₁ conductive, and the resistance Signal A with the voltage set by _R1 is input to the oscillation circuit.

As a result, a signal A' with a large chopper ratio is output from the oscillation circuit 33 to the chopper circuit 34,
Since the motor 4 is controlled by the chopper circuit 34, when the movable mast member 10 is lower than a certain lift height H, the pump 16 rotates at a high rotation speed, making it possible to perform a tailing operation at a high speed.

On the other hand, when the movable mast signal 10 exceeds the set value H, the lift height micro switch 1 is turned on, one input of the AND gate 30 becomes "1", and one input of the AND gate 32 becomes "0". .

Therefore, when the hydraulic operating valve 7 is tilted in this state, the tailed micro switch 9 is turned on and the other inputs of the AND gates 30 and 32 both become "1".

However, since one input of the AND gate 32 remains at "0", the output of only the AND gate 31 is "1".
As a result, the switching transistor Tr ₂ becomes conductive, and the signal B having the voltage set by the resistor R ₂ is input to the oscillation circuit 33.

As a result, a signal B' with a small chopper ratio is output to the chopper circuit 34, and the chopper circuit 34 controls the motor 4, so that the tailing operation is performed at a slow speed when the head is high.

As detailed above, the present invention includes a lift height micro switch that is turned on at a fork lift height of a certain level or higher;
A tail micro switch 9 that is turned on when the hydraulically operated valve is tilted; a motor 4 that drives a pump in the hydraulic circuit of the hydraulically operated valve; and a lift height micro switch and a tail micro switch that are provided in the electric circuit of the motor. A tipper controller 6 is provided which receives each signal, selects a preset tipping ratio, and controls the motor at the selected tipping ratio. Since a small chopping ratio is selected and the motor rotates at low speed,
It becomes possible to obtain a safe steering speed with less shaking of the mast and car body.

Furthermore, when the fork lifting height is lower than the constant lifting height, a large chopping ratio is selected and the motor rotates at high speed, so that an appropriate tailing speed can be obtained without impairing workability.

[Brief explanation of the drawing]

The drawing is an explanatory diagram of the configuration of an embodiment of the present invention. 1 is a lifting height micro switch, 4 is a motor, and 6 is a lift controller.

Claims (1)

[Scope of Claim for Utility Model Registration] A lift height micro switch 1 that is turned on when the fork lift height H is higher than a certain level, a tail micro switch 9 that is turned on when the hydraulic operation valve 7 is tilted, and a hydraulic pressure of the hydraulic device valve 7. Pump 1 in the circuit
a motor 4 that drives the motor 6; and a preset chopping ratio that is provided in the electric circuit of the motor 4 and receives signals from the lifting height micro switch 1 and the tilt micro switch 9, and selects a preset chopping ratio. and a chopper controller 6 for controlling the motor 4, and when the tilt micro switch 9 is turned on while the lift height micro switch 1 is on, the motor 4 is rotated at a low speed and the lift height micro switch is turned on. 1. A tailing speed control device for a forklift truck, which controls a motor 4 to rotate at high speed when a tailing micro switch 9 is turned on when a tilt micro switch 9 is turned on.