JPH05278998A - Automatic fork tilt operation stopping device for forklift - Google Patents

Abstract

PURPOSE:To control a fork into a preset posture at a necessary time. CONSTITUTION:A tilt angle sensor 14 is provided to detect a tilt angle of a fork, and a tilt lever has an automatic tilt operation stopping/release mode switching push-button switch 13, and an opeartion processing device 25 monitors a fork tilt angle theta outputted by the tilt angle sensor, and while the push-button switch is outputting an automatic tilt operation stopping mode signal, it stops the supply of pressure liquid to a tilt cylinder when a fork tilt angle coincides with a fork tilt angle theta0 preset in a memory part 26 of the operation processing device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fork tilt automatic stop device for a forklift.

[0002]

2. Description of the Related Art For example, when a forklift is used to pick up a shelf from a shelf, the fork is placed in a horizontal posture, and whether the fork is in a horizontal posture or not is conventionally determined by the driver.

On the forklift, jigs X and Y for horizontal confirmation as shown in FIG. 7 are provided on the vehicle body 1 side and the mast 2 respectively.
It is provided on the side, and if the ends of both jigs are aligned, it is determined that the fork is in a horizontal position.

[0004]

SUMMARY OF THE INVENTION In this conventional configuration,
Good if the pick-up position is lower than the eye level of the driver, but if the pick-up position is higher than the eye level of the driver,
Since you can't see the fork 3 and both jigs at a glance,
There was a problem that it was not easy to operate the fork in a horizontal position.

The present invention has been made to solve this problem, and an object of the present invention is to provide an automatic fork tilt operation stopping device capable of controlling the attitude of a fork to a preset attitude at a desired time.

[0006]

In order to achieve the above object, the present invention provides a lift lever, a transducer for converting a lift operation amount of the lift lever into an electric signal, and a lift cylinder for lifting a fork. And a tilt lever, a transducer that converts an operation amount of the tilt lever into an electric signal, a tilt cylinder that tilts a fork, a hydraulic pump that supplies and discharges pressurized liquid to and from the lift cylinder and the tilt cylinder, and the hydraulic pump. First provided in the pipe connecting the lift cylinder and the lift cylinder
Valve, a second valve provided in a pipe connecting the hydraulic pump and the tilt cylinder, and a control device, and the control device inputs the output of the transducer to the arithmetic processing device. In a forklift that controls the motor speed of the hydraulic pump and the opening / closing of the valve, the tilt lever has a tilt angle sensor for detecting the tilt angle of the fork, and the tilt lever has a push button switch for tilt operation automatic stop / release mode switching. The arithmetic processing unit monitors the fork tilt angle output from the tilt angle sensor, and the fork tilt angle is calculated in advance while the push button switch outputs the tilt operation automatic stop mode signal. When the fork tilt angle set in the memory section of the processor matches, the supply of pressure fluid to the tilt cylinder is stopped. It has a configuration that.

In the second aspect, the fork tilt angle set in the memory section of the arithmetic processing unit is an angle corresponding to the fork horizontal posture.

According to a third aspect of the present invention, the arithmetic processing unit is configured to cause the buzzer to ring when the fork tilt angle matches the fork tilt angle preset in the memory section.

According to a fourth aspect of the present invention, a display panel having a fork attitude display section is provided in a driver's cab, and the arithmetic processing unit turns on the display section in a flickering manner on condition that an automatic stop mode signal is input. After the posture coincides with the fork tilt angle set in the memory unit in advance, the display unit is made to illuminate statically.

[0010]

In the present invention, when the push button switch for changing the tilt operation automatic stop / release mode is pressed, the pummogram of the arithmetic processing unit is switched to the pummogram of the automatic stop mode, and the detection value output by the tilt angle sensor is preset. When it matches the set tilt angle set in the memory unit, the supply of the pressure liquid to the tilt cylinder is stopped.

When the automatic stop mode is released, the buzzer sounds when the fork detection value output by the tilt angle sensor matches the preset tilt angle set in the memory unit, but the pressure fluid is supplied to the tilt cylinder. Does not stop.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a vehicle body of a forklift truck using a battery as a drive source, 1A is a wheel, and 2 is a mast supported via a tilt mechanism (not shown) having a tilt cylinder 4 (from an outer mast and an inner mast). It becomes).
Reference numeral 3 denotes a fork, which is supported by the mast 2 via an elevating mechanism (not shown) including a lift cylinder 5. The tilt cylinder 4 is connected to a hydraulic pump 8 via a forward tilting proportional valve 6A and a rearward tilting proportional valve 6B, and the lift cylinder 5 is connected to a hydraulic pump 8 via an ascending proportional valve 7A and a descending proportional valve 7B. Have been contacted. 9 is a hydraulic pump 8
Motor 10 is a hydraulic tank. Reference numeral 11 is a tilt lever, and 12 is a lift lever, both of which are arranged on a driver's cab (not shown).

Reference numeral 13 denotes a push button switch for switching the tilt operation automatic stop / release mode provided on the grip portion of the tilt lever 11. Further, the tilt cylinder 4 is provided with a tilt angle sensor 14 as shown in an enlarged scale in FIG. 2, and the tilt angle sensor 14 has a tilt angle (forward tilt angle, backward tilt angle) of the mast 2 and thus the fork 3. Detect θ.

FIG. 3 shows a control device for this forklift.

Reference numeral 21 is a variable resistor for converting the operation amount of the tilt lever 11 into a voltage signal (exemplified in FIG. 5), and 22 is a variable resistor for converting the operation amount of the lift lever 12 into a voltage signal. Reference numeral 23 denotes an A / D converter, which is a voltage signal sent from the variable resistors 21 and 22 and the tilt angle sensor 1
4 is converted to a tilt angle signal θ digital signal and input to the arithmetic processing unit 24 of the control device. Reference numeral 25 is an arithmetic processing unit CPU of the arithmetic processing unit 24, 26 is a memory unit, 27
Is an I / O unit. Reference numeral 28 denotes a valve control circuit, which is based on a valve control command input from the arithmetic processing unit 24.
The opening and closing of A, 6B and 7A, 7B and the valve opening are controlled. 30 is a motor control circuit, 31 is a chopper element, 31
A is a chopper control circuit, 32 is a switch, 33 is a relay, and 11A is a lever operation detection switch built in the tilt cylinder 4.

Reference numeral 40 denotes a display panel (liquid crystal panel) provided on the front surface of a driver's cab (not shown). The display panel 40 has a display portion 41 shown in FIG. There is. The display unit 40 includes a fork mark A, a cross mark B, and a frame mark C surrounding both.

First, the tilting operation of the fork 3 will be briefly described.

When the tilt lever 11 is tilted forward from the neutral position, the lever operation detection switch 11A (shown in FIG. 3) built in the tilt lever 11 is turned on to activate the relay 33, and the switch shown in FIG. 32 turns on.
The variable resistor 21 outputs a voltage signal (shown in FIG. 5) having a magnitude corresponding to the operation amount of the tilt lever 11. This voltage signal rises from the voltage value of 1/2 of the power supply voltage V _C1 of the variable resistor 21. The CPU 25, which has input the value of this voltage signal (hereinafter referred to as the forward tilt signal) through the A / D converter 23, issues a motor speed command (shown in FIG. 6) corresponding to the value of the forward tilt signal to I
Sent to the chopper control circuit 31A through the / O section 27,
The chopper control circuit 31A gives a base signal of a pulse width corresponding to the level of the motor speed command to the base of the chopper element 31, and sends a valve control command according to the value of the forward tilt signal through the I / O unit 27 to the valve control circuit 28. Give to. The valve control circuit 28 amplifies this valve control command and gives it to the forward lean proportional valve 6A, and the forward lean proportional valve 6A opens to a valve opening degree corresponding to the magnitude of the valve control instruction. As a result, the tilt cylinder 4
The pressure liquid flows into the inside in the direction of pushing out the rod, and the pushing out of the rod causes the fork 3 to tilt forward.

When the tilt lever 11 is tilted backward from the neutral position, the variable resistor 21 outputs a voltage signal that decreases according to the operation amount of the tilt lever 11. This voltage signal decreases from the voltage value of 1/2 of the power supply voltage V _C1 of the variable resistor 21. The CPU 25, which has input the value of this voltage signal (hereinafter referred to as the rearward tilt signal) through the A / D converter 23, increases the motor speed command corresponding to the decrease of the rearward tilt signal (see FIG. 6).
(Shown in FIG. 3) through the I / O unit 27.
Then, the chopper control circuit 31A supplies a base signal having a pulse width corresponding to the level of the motor speed command to the base of the chopper element 31. Further, a valve control command that increases in response to a decrease in the backward tilt signal is given to the valve control circuit 28 through the I / O unit 27. The valve control circuit 28 amplifies this valve control command and gives it to the backward tilt proportional valve 6B, and the forward tilt proportional valve 6B opens to a valve opening degree corresponding to the magnitude of the valve control command. As a result, the pressure liquid flows into the tilt cylinder 4 in a direction in which the rod is retracted, and the fork 3 is tilted backward due to the rod retracting.

Next, the operation of the fork tilting automatic stop device of this embodiment will be described.

In this embodiment, the data of the tilt angle θ ₀ corresponding to the horizontal posture of the fork 3 is written in the memory unit 26 of the arithmetic processing unit 24 in advance.

Now, it is assumed that the fork 3 is in the backward tilting posture.

(1) Automatic stop mode When the tilt lever 11 is operated forward while pressing the push button switch 13 for changing the tilt operation automatic stop / release mode, the forward tilt proportional valve 6A operates as described above, and The fork 3 in the tilted posture approaches the horizontal posture, and the CPU 25 which receives the automatic stop mode signal m output from the push button switch 13 for tilt stop automatic stop / release mode switching is input.
Switches to the automatic stop mode and sends a flicker display command for blinking the display unit 41. As a result, the display unit 41 starts the flicker display. The CPU 25 monitors the detection value θ of the tilt angle sensor 14, the posture of the fork 3 becomes horizontal, and the detection value θ is stored in the memory unit 26.
When it matches the set tilt angle θ ₀ stored in, the tilt operation stop command is sent, and at the same time, the still display command for displaying the display unit 41 in a still state is sent. As a result, the motor speed command and the valve control signal for the forward lean proportional valve 6A disappear, the motor 9 stops, the forward lean proportional valve 6A closes, and the supply of the pressure fluid to the lift cylinder 2 is stopped. ,
The fork 3 automatically stops in the posture of the set tilt angle θ ₀ , that is, in the horizontal posture, and thereafter, the display unit 41 switches to the stationary display. The stationary display on the display unit 41 allows the driver to know that the fork 3 is in a horizontal posture and is stopped in that posture.

When the pressing of the push button switch 13 for switching the tilt operation automatic stop / release mode is stopped, the automatic stop mode is released and the fork 3 can be tilted forward and backward.

(2) When the tilt lever 11 is operated forward without pressing the push button switch 13 for tilt operation automatic stop / release mode switching, the display section 41 does not light up, and the tilt angle sensor 14 does not light up. Even if the detected value θ reaches the set tilt angle θ ₀ , the CPU 25 does not send the tilt operation stop command. In this case, the CPU 25 generates a ringing command for ringing the buzzer 50 when θ = θ ₀ , so that the driver can know that the fork 3 is in the horizontal posture.

As described above, in this embodiment, when the data of the tilt angle θ ₀ corresponding to the horizontal posture of the fork 3 is set in the memory unit 26 of the arithmetic processing unit 25 in advance, the posture of the fork 3 is set to the horizontal posture. Then, the posture fork 3 stops.

Therefore, the driver can use the jig X,
Since it is not necessary to operate the tilt lever 11 while looking at Y, even if the loading position is higher than the eyes of the driver,
The fork 3 can be easily attitude-controlled to a horizontal attitude.

Further, in this embodiment, a push button switch 13 for switching the tilt operation automatic stop / release mode is provided so that the fork automatically stops at the set posture θ ₀ in the automatic stop mode, but operates in the release mode. The hand can stop the fork 3 in any posture.

Further, in the present embodiment, the display panel 40 provided with the display unit 41 is provided on the driver's cab, and the display unit 41 has a fork attitude θ that matches the fork attitude θ ₀ preset in the memory unit 26. Until the flicker is turned on, and after matching, the driver is turned on statically.
It is possible to know at a glance that the fork 3 has become horizontal.

In the above embodiment, the case where the fork 3 is automatically controlled to the horizontal posture has been described. However, if the set tilt angle is changed, the fork 3 can be automatically controlled to another posture.

[0032]

As described above, according to the present invention, the fork can be automatically stopped in a specific posture only by setting the tilt angle data corresponding to the fork horizontal posture in the memory unit of the arithmetic processing device in advance. Even if the driver is unskilled, the fork can be accurately controlled to a desired posture.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of the present invention.

FIG. 2 is a diagram showing a tilt cylinder in the above embodiment.

FIG. 3 is a diagram showing a control device in the embodiment.

FIG. 4 is a diagram showing a display unit in the above embodiment.

FIG. 5 is a diagram showing a voltage generated by a variable resistor in the control device.

FIG. 6 is a diagram showing a motor speed command in the above embodiment.

FIG. 7 is a diagram showing an example of a conventional jig for horizontal confirmation of a fork.

[Explanation of symbols]

1 Car Body 2 Mast 3 Fork 4 Tilt Cylinder 5 Lift Cylinder 6A, 6B Proportional Valve 8 Pump 9 Pump Motor 11 Tilt Lever 13 Tilt Operation Automatic Stop / Release Mode Switching Push Button Switch 14 Tilt Angle Sensor 24 Computing Processor 25 CPU 26 Memory unit 28 Valve control circuit 40 Display panel 41 Display unit 50 Buzzer

Claims (4)

[Claims] 1. A lift lever, a transducer for converting a lift operation amount of the lift lever into an electric signal, a lift cylinder for moving a fork up and down, a tilt lever, and a transducer for converting an operation amount of the tilt lever into an electric signal. A tilt cylinder that tilts the fork, a hydraulic pump that supplies and discharges pressurized liquid to the lift cylinder and the tilt cylinder, and a first valve provided in a pipe that connects the hydraulic pump and the lift cylinder. ,
A second valve provided in a pipe connecting the hydraulic pump and the tilt cylinder and a control device are provided, and the control device inputs the output of the transducer and processes the output by the arithmetic processing device. In a forklift that controls the motor speed of the hydraulic pump and the opening / closing of the valve, the tilt angle sensor for detecting the tilt angle of the fork is provided, and the tilt lever has a pushbutton switch for changing the tilt operation automatic stop / release mode. The arithmetic processing unit monitors the fork tilt angle output by the tilt angle sensor, and while the push button switch outputs the tilt operation automatic stop mode signal, the fork tilt angle is previously stored in the memory of the arithmetic processing unit. When the fork tilt angle set in the section matches, the supply of pressure liquid to the tilt cylinder is stopped. Automatic stop device for fork tilt movement of forklifts characterized by. 2. The fork tilt operation automatic stop device for a forklift according to claim 1, wherein the fork tilt angle set in the memory unit of the arithmetic processing device is an angle corresponding to a fork horizontal posture. 3. The fork tilt of a forklift according to claim 1, wherein the arithmetic processing unit causes the buzzer to ring when the fork tilt angle matches a fork tilt angle preset in the memory section. Automatic stop device. 4. A display panel having a fork attitude display section is provided in a driver's cab, and the arithmetic processing unit makes the display section flicker lit on condition that an automatic stop mode signal is inputted, and the fork attitude is preset. The automatic fork-tilt operation stopping device for a forklift according to any one of claims 1 to 3, wherein the display is turned on after the fork-tilt angle set in the memory matches.