JP2002370898A - Lift truck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lift truck capable of reducing fatigue of an operator without impairing an operation feeling and operability, and without expanding an operation space. SOLUTION: This lift truck is provided with operation detecting means 26a and 26b for outputting a detecting signal by detecting an excess over a prescribed value in a control input of an operation lever 8 for automatically returning to a prescribed position by a spring at unoperating time, an actuator 28 for driving the operation lever 8 in the operation direction, and a control part 31 for operating the actuator 28 when the control input of the operation lever 8 detected by the operation detecting means 26a and 26b exceeds the prescribed value, and freeing the actuator 28 when the control input is within the prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lift truck such as a forklift.

[0002]

2. Description of the Related Art In general, lift trucks are used, for example, to advance or retreat a vehicle body, to raise or lower a carrier such as a fork, to tilt a carrier forward and backward,
An operation lever corresponding to each operation is provided to control the forward / backward movement of the transporter, the traverse of the transporter, the rotation of the transporter, the opening / closing of the transporter, and a handle for controlling the running of the vehicle body is provided. Performs the required cargo handling work by appropriately manipulating the operation tools such as the operation lever and the handle.

In general, each operation lever is provided so as to be operated forward and backward around a neutral position, and is automatically returned to the neutral position by a spring when not operated. The operator operates the operation lever against the spring, and the resistance felt by the operator by the elastic force of the spring is used for steering as a so-called operation feeling.

[0004]

However, it is certain that the resistance caused by the spring may cause fatigue of the operator, and the greater the operation amount of the operation lever, the greater the fatigue of the operator. The longer the continuous operation time, the more tired the operator.

For example, when a carrier such as a fork is raised to a high elevation or lowered from a high elevation, that is, when the moving distance is long, an elevation operation lever provided for elevating the transportation is moved forward or backward by a constant amount. Must be kept in the state of being pushed down to the position, so that the influence on the fatigue of the operator increases.

Therefore, resistance to the operation of the operating lever,
That is, in order to reduce the operating resistance and reduce the fatigue of the operator, it is conceivable to reduce the setting force of the spring and to lengthen the operating lever and increase the lever ratio on the operating side. Each method has another problem from the viewpoint of reducing operator fatigue.

That is, when the setting force of the spring is weakened, physical fatigue of the operator is reduced, but at the same time, the operation lever returns to the neutral position, that is, the so-called neutral return deteriorates, resulting in impaired operation feeling. This causes a problem that the operator is tired psychologically.

If the operating lever is lengthened to reduce the operating resistance and the lever ratio on the operating side is increased, the so-called neutral return is not impaired, and the force required for operating the operating lever is reduced. It is necessary to operate the operation lever large, and physical fatigue cannot be reduced as much as expected, and a large space is required for operation of the lever, which is disadvantageous in reducing the size and size of the vehicle body. Problem arises.

[0009] The present invention solves this problem of the prior art,
An object of the present invention is to provide a lift truck capable of reducing operator fatigue without impairing the operation feeling or expanding the operation space.

[0010]

According to the present invention, there is provided a lift truck having an operation lever automatically returning to a predetermined position by a spring when not operated.
Operation detecting means for detecting that the operation amount of the operation lever exceeds a predetermined value and outputting a detection signal; an actuator for driving the operation lever in an operation direction; and an operation lever for detecting the operation lever detected by the operation detection means. A technical means is provided in which a control unit is provided that activates the actuator when the operation amount exceeds a predetermined value and releases the actuator when the operation amount is within the predetermined value.

According to this, when the operation amount of the operation lever exceeds a predetermined value, the actuator drives the operation lever in the operation direction, so that the operation force required for the operator to operate the operation lever is reduced. Is obtained.

According to this, the setting force of the spring does not have to be reduced, and when the operation amount of the operation lever is within a predetermined value, the actuator is free, that is, freely moved by an external force. Since this state is established, the effect is obtained that the urging force of the spring is not suppressed by the actuator, and so-called neutral return is not impaired.

Further, according to this, since the operator's force required for operating the operation lever can be reduced without changing the lever ratio of the operation lever, there is no need to lengthen the operation lever. can get.

However, if the operator moves the valve shaft larger than the position corresponding to the operation position of the operation lever, the transporter moves more than the operator predicts, which is dangerous. In order to prevent such a danger, it is necessary that the output of the actuator is smaller than the elastic force of the spring for returning the valve shaft to the neutral position.

In the present invention, when the actuator is operated over the entire operation area of the operation lever except for a predetermined position where the operation lever automatically returns, in an area where the operation amount of the operation lever is small, Since the elastic force of the spring is small, there is a possibility that the stability of the operation is impaired, or the operation resistance felt by the operator becomes too small and the operation feeling is impaired.

Therefore, in the present invention, the control unit activates the actuator when the operation amount of the operation lever exceeds a predetermined value, and frees the actuator within the predetermined value to solve this problem. . In particular,
When the operation lever is positioned in a large operation area where the operation amount of the operation lever exceeds a predetermined value close to the maximum operation amount, for example, when the maximum operation amount is 100%, the operation lever is located in a large operation area exceeding 80 to 95%. It is recommended to be configured to work.

Further, in the present invention, the elastic force of the spring increases or decreases in accordance with the magnitude of the operation of the operation lever even in the region where the actuator operates, so that when the operation amount of the operation lever is reduced, the operation becomes smaller. Or the operation feeling may be impaired.On the contrary, when the operation amount is large, the driving force of the actuator is weak, and the purpose of reducing the fatigue of the operator may not be sufficiently achieved. Occurs.

Therefore, in the present invention, the control unit increases or decreases the driving force of the actuator according to the magnitude of the operation amount of the operating tool detected by the operation detecting means in the region where the actuator is operated. It is recommended that

As described above, when increasing or decreasing the driving force of the actuator, the rate of increase or decrease of the driving force of the actuator is determined in consideration of the fact that the elastic force of the spring increases or decreases in proportion to the magnitude of the operation amount. It is preferable to determine.

Of course, the rate of increase / decrease of the driving force of the actuator may be constant, may be changed continuously, or may be changed in a stepwise manner. Since it is preferable to follow the conventional operation feeling in which the resistance increases, the rate of increase or decrease in the driving force of the actuator is equal to or less than the rate of change in the elastic force of the spring, even when the actuator is changed or kept constant. It is recommended to set to increase or decrease with.

The present invention can be applied to any operation lever of the lift truck, and may be applied to all operation levers provided on the lift truck.
In particular, the present invention may be applied to only one or a small number of specific operation levers, such as an elevation operation lever for controlling elevation of a transporter, which frequently performs operations that affect the fatigue of the operator.

In the present invention, the operation detecting means may be configured to detect that the operation amount of the operation lever exceeds a predetermined value and output a detection signal composed of, for example, an electric signal. .

For example, as the operation detecting means for outputting an ON or OFF electric signal as a detection signal, a switch driven by the above-mentioned operation lever or a driving member interlocked with the operation lever may be used. A non-contact driving type switch typified by a contact driving type switch, a reed switch, and the like are included.

Further, a sensor whose output value changes depending on the positional relationship with the operating lever or a member to be detected linked thereto, for example, a photo sensor, an acoustic sensor, a magnetic sensor, etc. can be used as the operation detecting means. There is a region where the strength changes continuously in the detection signal of
It becomes easy to increase or decrease the driving force of the actuator according to the magnitude of the operation amount of the operation lever.

Further, other than these, it is also possible to use measuring means such as a potentiometer or a rotary encoder capable of detecting the position based on the number of signals. Therefore, it becomes easy to increase or decrease the driving force of the actuator.

In addition, the operation amount of the operating lever can be detected by a pressure sensor for detecting the elastic force of the spring or a strain gauge for detecting the amount of deformation of the spring. Even when a gauge is used, the signal value of the detection signal continuously changes, so that it becomes easy to increase or decrease the driving force of the actuator according to the magnitude of the operation amount of the operation lever.

In the present invention, the driving energy of the actuator is not particularly limited, and for example, electricity, hydraulic pressure, pneumatic pressure, water pressure, etc. can be used. Generally, a driving energy source mounted on a lift truck, that is, a battery is used. It is preferable to use a power supply or a pressure oil supply source.

The actuator may be a rotary drive type actuator such as an electric motor, a rotary solenoid, a hydraulic motor, a rotary hydraulic cylinder, an air motor, a rotary air cylinder, a water wheel, etc.
Motor, linear solenoid, electric cylinder, hydraulic cylinder,
The actuator may be a linear drive type actuator such as an air cylinder or a hydraulic cylinder, but it must be able to move freely by an external force when supply of driving energy such as electricity, hydraulic pressure, pneumatic pressure, or hydraulic pressure is stopped.

When the operation amount of the operation lever detected by the operation detection means exceeds a predetermined value, the control unit supplies drive energy to the actuator to operate the actuator, and the operation amount of the operation lever is reduced. Any actuator may be used as long as the supply of the driving energy to the actuator is interrupted when the value is within the predetermined value and the actuator is released.

That is, when the driving energy of the actuator is electricity and the actuator is to be turned on / off, the control unit only needs to be configured to open and close a power supply circuit connecting the actuator and a power supply. ,
For example, it may be constituted by a microcomputer and a driver for turning on and off the power supply circuit of the actuator in accordance with a command given by the microcomputer.

When the drive energy of the actuator is electric and the actuator is controlled to be turned on and off, a relay coil is provided in a circuit for connecting the operation detecting means to a power supply. The control unit may be constituted by an interposed relay switch.

Further, when the drive energy of the actuator is electric and the actuator is to be turned on / off, the operation detecting means is interposed in the power supply circuit of the actuator and the operation detecting means fulfills the function of the control section. It is also possible to make it.

In addition, when the driving energy of the actuator is electricity and the driving force of the external actuator is increased or decreased in accordance with the magnitude of the operation of the operation lever,
The control unit may be configured to not only turn on / off the supply of power to the actuator, but also increase / decrease the power at the time of ON in accordance with the magnitude of the detection signal.

For example, a microcomputer for calculating a current value or a voltage value to be supplied to the actuator in accordance with the magnitude of the signal value of the detection signal, and a driver for supplying power to the actuator in accordance with the calculation result. May be configured.

Further, the control section may be constituted by a transformer in which the operation detecting means is connected to the primary side and the actuator is connected to the secondary side.

When the driving energy of the actuator is hydraulic, for example, an electromagnetic control valve is interposed between the actuator and the pressure oil supply source, and the control unit controls the electromagnetic control valve by the operation detecting means. When the detected operation amount of the operation lever exceeds a predetermined value, a pressure oil supply source is connected to the actuator, and when the operation amount is within the predetermined value, the actuator is disconnected from the pressure oil supply source to be free. I just need.

As the above-mentioned electromagnetic control valve, a two-position switching valve such as a single-acting electromagnetic control valve or a double-acting electromagnetic valve incorporating a return spring may be used. For example, a variable throttle valve such as a proportional valve may be used. Alternatively, according to a two-position switching valve, the actuator is on / off controlled, and if a proportional valve is used, the actuator is proportionally controlled.

When the driving energy of the actuator is pneumatic or hydraulic, the starting energy is the same as in the case of hydraulic pressure except that the pressure medium is different.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a lift truck according to an embodiment of the present invention will be specifically described with reference to the drawings.

FIG. 1 is a structural view of a lift truck according to one embodiment of the present invention, FIG. 2 is a front view of a main part of the lift truck, FIG. 3 is a plan view of the main part, and FIG. FIG. 1 is a perspective view of the lift truck. First, an outline of the lift truck according to an embodiment of the present invention will be described with reference to FIG.

This lift truck includes a mast 2 provided at the front of the vehicle body 1 so as to be able to move forward and backward, and a carrier 3 supported on the mast 2 so as to be able to move up and down and to be raised and lowered. 3 includes a backrest 3a and a pair of left and right forks 3b supported by the backrest 3a.

A power room 4 for housing a traveling device and a hydraulic power unit is provided at the rear left portion of the vehicle body 1.
A cockpit 5 on which an operator stands and rides is formed in the right rear part, and a battery case 6 for storing a battery is provided in front of the power room 4 and the cockpit 5.

A control panel 7 is provided on the upper side of the battery case 6. The control panel 7 includes a control lever 8, which is generally called a lift lever, which is operated to raise and lower the transporter 3, and a tilt lever. An operation lever 9 which is called to raise and lower the transporter 3;
Generally called a reach lever, the mast 2 and the carrier 3
Operating lever 1 operated to move back and forth
The operation lever 11 is generally referred to as an accelerator lever and is operated from left to right to operate the vehicle body 1.

A steering handle 12 operated to control the running direction of the vehicle body 1 is disposed above the power room 4, and a deadman type brake pedal 13 is disposed on the floor 14 of the cockpit 5. .

As shown in FIGS. 1 and 2, of the operation levers 8, 9, 10, and 11, three operation levers 8, 9, 10 on the left side (three right side in FIG. 2) are connected to the battery. The bracket 6 is supported by a bracket 15 fixed to the front wall of the case 6 via a common support shaft 16 so as to be able to rotate independently of each other around the left and right axes.

A valve array 17 composed of three sections is fixed to the bracket 15, and the operating levers 8, 9, 10 are connected to links 21, 22, 23 by valve shafts 18, 19, 20 of the respective sections. When not operated, the operating levers 8, 9, and 10 are automatically returned to a neutral position where the operating levers 8, 9, and 10 are upright by a spring provided in the valve array 17 when not operated.

The hydraulic piping connected to the valve array 17 is not directly related to the present invention and will not be described.
The pipe is arranged such that when the operator lowers the operation lever 8 used for the lifting operation from the neutral position to the front, the transporter 3 moves down, and when the operator tilts the control lever 8 backward, the transporter 3 rises. The pipe is arranged so that when the operator lowers the operation lever 9 for the up / down operation from the neutral position to the front, the transporter 3 is inclined forward, and when the operator is tilted backward, the transporter 3 is inclined backward. Further, the pipe is arranged so that the transporter 3 moves forward when the operator lowers the operation lever 10 for forward / backward movement from the neutral position forward, and the transporter 3 moves backward when the operator tilts the control lever 10 forward and backward.

As shown in FIGS. 1 and 3, another bracket 25 is fixed to the valve box 24 of the valve array 17, and the bracket 25 is provided with operation detecting means 26a and 26b made of, for example, a microswitch. Can be These operation detecting means 26a and 26b also serve as operation detecting means for turning on and off a hydraulic motor for driving a hydraulic pump interposed in the hydraulic pipe.

When the operation lever 8 is operated in a range exceeding, for example, 80% of the maximum operation amount in the forward leaning direction, one operation detection means 26a is driven by the valve shaft 18, and
The operation detecting means 26a outputs a forward leaning operation detection signal consisting of an ON signal.
When the operation is performed in a range exceeding 0%, the other operation detecting means 26b is driven by the driving member 27 connected to the link 21, and a backward tilt operation detection signal including an ON signal is output.

As shown in FIGS. 1 and 2, the bracket 15 supports an actuator 28 composed of, for example, an electric cylinder via a sub-bracket 32, and a piston rod 29 of the actuator 28
0, it is interlockingly connected to the operation lever 8.

As will be described later, the actuator 28 is shortened or extended when the power is supplied, and is free when the power is not supplied so that the actuator 28 is automatically returned to the neutral position by a spring built in the valve array 17. Controlled.

That is, the lift truck supplies a drive current in the direction in which the actuator 28 is extended to the actuator 28 when a forward tilt operation detection signal is input from the operation detection means 26a, and the lift track supplies the drive current from the operation detection means 26b. The control unit 31 supplies a drive current in a direction in which the actuator 28 shortens when a backward tilt operation detection signal is input.

The control unit 31 outputs, for example, an extension drive command when the forward tilt operation detection signal is input, and a microcomputer that outputs a shortening drive command when the rearward tilt detection signal is input. For example, the power supply circuit is interposed in a power supply circuit connected to a battery. When the extension drive instruction is received, the power supply circuit is connected to the actuator 28 so that a current in a direction in which the actuator 28 extends can be connected. Actuator 2
8 is connected so that the current in the direction of shortening flows.
Otherwise, it is composed of a driver that opens the power supply circuit.

According to this lift truck, for example, the operator operates the operation lever 8 for raising / lowering operation in a range exceeding 80% of the maximum operation amount in the ascending direction, ie, the forward tilt direction (or the descending direction, ie, the backward tilt direction). Then, one operation detecting means 26a (or the other operation detecting means 26b) detects this operation, extends (or shortens) the actuator 28, is provided in the valve array 17, and moves the valve shaft 18 to the neutral position. Since the elastic force of the spring that attempts to return to the maximum operation amount is suppressed, the operator can maintain the operation force in a range exceeding 80% of the maximum operation amount in the ascending or descending direction with a correspondingly small force, and the fatigue of the operator is reduced.

However, since the actuation of the actuator 28 must not move the valve shaft 18 more than the position corresponding to the operation amount of the operation lever 8 operated by the operator, the driving force of the actuator 28 is limited by the elasticity of the spring. It must be smaller than the force.

If the operation amount of the operation lever 8 is within 80% of the maximum operation amount in the ascending or descending direction, the actuator 28 is in a non-energized state and can freely expand and contract by an external force. The biasing of the operation lever 8 in the neutral direction is not hindered by the actuator 28, and the so-called neutral return does not deteriorate.

Further, since the lever ratio of the operation lever 8 does not need to be changed, the operation stroke of the operation lever 8 does not increase, and there is no possibility that the operator's fatigue may increase due to the expansion of the operation stroke. The space required for operating the lever 8 does not need to be enlarged, and there is no increase in size or coarseness.

In this embodiment, as shown in FIGS. 1 and 3, the operation detecting means 26b is driven by a driving member 27 fixed to the link 21 linked to the operating lever 8, and the operation detecting means 26a Are driven by the valve shaft 18 having a shackle.
6a and 26b are both driven by the valve shaft 18, and both the operation detecting means 26a and 26b are both operated by the operating lever 8 or the valve shaft 18.
It can be driven by a driving member that is linked to.

Further, two operation detecting means 26a and 26b are provided for one operating lever and the valve shaft 18, and one of the operation detecting means 26a detects that the operating lever 8 is operated in the forward tilt direction. The other operation detecting means 26b is configured to detect that the operating lever 8 is operated in the backward tilt direction, but the operation of the operating lever 11 is detected by the operation detecting means 33 including a potentiometer. Like,
One operation detecting means, such as a potentiometer, which can detect operations in both forward and backward tilts may be provided for one operation lever 8 and one valve shaft 18. In this case, the control unit 31 is provided with a determination unit that determines whether the operation direction and the operation amount of the operation lever 8 is equal to or greater than a predetermined determination value based on a position signal given from a potentiometer. What is necessary is just to comprise so that the said actuator 28 may be extended or shortened according to the determination result.

Further, in this embodiment, the operation detecting means 26
a and 26b are also used as operation detecting means for turning on and off a hydraulic motor that drives a hydraulic pump interposed in a hydraulic pipe, that is, operation detecting means for operating a cargo handling function. Apart from the detection means, these operation detection means 26a for operating lever assist control,
26b may be provided.

In addition, in this embodiment, the valve shaft 18 is driven by the actuator 28 in both the forward tilt direction and the backward tilt direction, but the valve shaft 18 is driven only in one of the forward tilt direction and the backward tilt direction. The shaft 18 may be driven,
Actuator for driving valve shaft 18 in the forward tilt direction and valve shaft 8
And two actuators for driving the actuator in the backward tilt direction.

Of course, the operating force of the operating levers 9, 10, and 11 other than the operating lever 8 for raising and lowering the transporter 3 can be assisted by the actuator in the same manner as in the case of the operating lever 8. is there.

[0063]

As described above, the present invention detects that an operation amount of the operation lever exceeds a predetermined value in a lift truck having an operation lever automatically returning to a predetermined position by a spring when not operated. An operation detecting means for outputting a detection signal, and an actuator for driving the operation lever in the operation direction, and operating the actuator when an operation amount of the operation lever detected by the operation detection means exceeds a predetermined value, A controller is provided for releasing the actuator when the value is within a predetermined value.

When the operation amount of the operation lever exceeds a predetermined value without reducing the urging force of the spring or changing the lever ratio of the operation lever, the operator operates the operation lever. Therefore, the effect that the operation force required for the operation is reduced is obtained.

When the operation amount of the operation lever exceeds a predetermined value, the operation force required for the operator to operate the operation lever is reduced, so that the fatigue of the operator can be reduced. Is obtained.

Further, from the effect that the urging force of the spring is not reduced, there is obtained an effect that the so-called neutral return does not deteriorate and there is no fear that the operator's psychological fatigue is increased.

Further, since the lever ratio of the operating lever is not changed, there is no possibility that the operating stroke of the operating lever is expanded and the physical fatigue of the operator is increased, and the operation lever is required for operating the operating lever. Therefore, it is possible to obtain an advantageous effect that the operation device or the vehicle body is advantageously reduced in size and size.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of the present invention.

FIG. 2 is a front view of a main part of the present invention.

FIG. 3 is a plan view of a main part of the present invention.

FIG. 4 is a perspective view of the present invention.

[Explanation of symbols]

 Reference Signs List 8 operating lever 9 operating lever 10 operating lever 11 operating lever 26 operation detecting means 28 actuator 31 control unit 33 operation detecting means

Claims (5)

[Claims] 1. A lift truck having an operation lever automatically returning to a predetermined position by a spring when not operated, an operation detection means for detecting that the operation amount of the operation lever exceeds a predetermined value and outputting a detection signal; An actuator for driving the operation lever in the operation direction, and actuating the actuator when an operation amount of the operation lever detected by the operation detection means exceeds a predetermined value, and releasing the actuator when the operation amount is within a predetermined value. The lift truck according to claim 1, further comprising a control unit. 2. The lift truck according to claim 1, wherein the operation detecting means outputs a detection signal when the operation lever is positioned in a large operation area exceeding a predetermined value close to a maximum operation amount. 3. The driving force of the actuator is increased or decreased in accordance with a magnitude of an operation amount of the operation tool detected by the operation detection means in a region where the actuator is operated. 3. The lift truck according to 2. 4. The lift truck according to claim 1, wherein the operating tool is a lifting operation lever provided for controlling lifting and lowering of a transporter of the lift truck. . 5. The lift truck according to claim 1, wherein an output of said actuator is smaller than an elastic force of a spring for automatically returning an operation lever to a neutral position when not operated. .