JPH09315125A - Control device for industrial vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure easy and stable release of fixation of axle. SOLUTION: To a vehicle body frame 1a of a forklift truck a rear axle 11 is connected to be swingable around a center pin 11a and on both ends a rear wheel 8 serving as a steered wheel. Between the axle 11 and the frame 1a a damper 12 is connected which is connected to a reservoir 16 through an electromagnetic proportional valve 13. When a stationary operation signal is output from a controller, the valve 13 is turned into a full closed condition to lock the damper 12 and fix the axle 11. When the output is released from the condition, the valve 13 is gradually opened according to the release. Accordingly the fixation of the axle 11 is released gradually at a specified speed and thereby the fixation of axle 11 can be released under a stable condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an industrial vehicle in which an axle is swingably provided.

[0002]

2. Description of the Related Art Conventionally, forklifts have been proposed in which an axle can be swung with respect to a body frame in consideration of the traveling performance and riding comfort of the vehicle. In this forklift,
When the forklift turns, the forklift swings, for example, according to lateral acceleration (centrifugal force) or the like. For this reason, the running stability at the time of turning was reduced, and the running speed could not be increased.

Japanese Patent Application Laid-Open No. 58-211903 has provided a turning detecting means for detecting a centrifugal force generated at the time of turning of a forklift. When the detected value of the centrifugal force exceeds a predetermined value, the swinging operation is performed. A technique has been proposed in which an axle that is supported is fixed by an axle fixing mechanism.

In this forklift, when the centrifugal force acting on the forklift exceeds a predetermined value when the forklift turns, the axle is fixed and the forklift can turn in a stable state.

The axle is fixed by locking a damper disposed between the body frame and the axle. That is, by blocking (blocking) the pipeline for supplying and discharging hydraulic oil to and from the damper, the damper is locked and the axle is fixed. In addition, the locked state of the damper is released by bringing the pipelines into communication with each other, so that the axle can swing.

[0006]

However, when the axle is fixed and released from the fixed state, the pressure of the hydraulic oil in the damper is suddenly lowered from the state where the pressure of the hydraulic oil is increased, so that the axle suddenly rocks. To start. Therefore, there is a problem that a shock is increased when the axle is unlocked.

Further, Japanese Laid-Open Patent Publication No. 58-183307 discloses a technique in which an absorber nipple consisting of a check valve and a fixed throttle valve is used to prevent sudden swinging of the axle when the axle is unfixed. Is disclosed. However, with this technique, it is necessary to pipe two valves, a check valve and a fixed throttle valve, and there is a problem that the piping work is complicated.

The present invention has been made to solve the above problems, and an object thereof is to provide a control device for an industrial vehicle that can easily and stably release the fixation of the axle.

[0009]

In order to solve the above-mentioned problems, the invention according to claim 1 fixes an axle in an industrial vehicle in which the axle is swingably supported in a vertical direction with respect to a body frame. Fixing control means for outputting a fixed operation signal, a damper arranged between the vehicle body frame and the axle for supplying / discharging hydraulic oil according to the swing of the axle, and hydraulic oil supplied / discharged from the damper. The pipe line
It is controlled between the shielded state and the communicating state, and the damper is locked to fix the axle by setting the shielded state, and the axle can be swung by setting the communicating state, and the fixed operation signal is output. The main feature of the present invention is to provide a proportional valve that controls the opening degree of the valve portion at a predetermined speed to gradually control the communication state to the closed state when the release is released.

According to a second aspect of the present invention, in an industrial vehicle in which an axle is swingably supported in a vertical direction with respect to a vehicle body frame, a fixing control means for outputting a fixing operation signal for fixing the axle, and A damper, which is arranged between the vehicle body frame and the axle and supplies and discharges hydraulic oil in accordance with the swing of the axle, and a pipeline for flowing the hydraulic oil supplied and discharged to and from the damper, are in a closed state and a communication state. Between them, the damper is locked to lock the axle by setting the shielding state, and the axle can be swung by setting the communication state, and the communication state is established when the fixed operation signal is output. From the switching valve to control from the shielding state, provided in the pipe line,
The gist of the invention is to include a variable throttle valve that reduces the opening degree of the valve portion for a predetermined time at least after the output of the fixed operation signal is released.

According to a third aspect of the present invention, in the invention of the first or second aspect, the industrial vehicle includes load detecting means for detecting a load acting on an elevating and lowering drive means for moving the cargo handling equipment up and down, and the cargo handling equipment. And the fixed control means, when the load detected by the load detection means is equal to or higher than the reference pressure value and the elevation position is equal to or higher than the reference elevation position. The point is to output a fixed operation signal.

According to a fourth aspect of the present invention, in the invention of the third aspect, the industrial vehicle further includes a yaw rate detecting means for detecting a yaw rate acting on the vehicle, and a yaw rate detected by the yaw rate detecting means. Change rate calculating means for calculating the change rate of, the fixed control means, when the load detected by the load detecting means is a reference pressure value or more, the lift position is a reference lift position or more,
Alternatively, based on the change rate of the yaw rate calculated by the change rate calculating means, the fixed operation signal is output when the change rate of the yaw rate becomes a value larger than the reference rate value. .

According to a fifth aspect of the present invention, in the industrial vehicle according to the first or second aspect, the industrial vehicle includes a yaw rate detecting means for detecting a yaw rate acting on the vehicle, and a yaw rate detected by the yaw rate detecting means. A change rate calculating means for calculating a change rate, wherein the fixed control means is based on the change rate of the yaw rate calculated by the change rate calculating means, and the change rate of the yaw rate is larger than a reference rate value. When it becomes, the gist is to output a fixed operation signal.

A sixth aspect of the present invention is characterized in that, in the first to fifth aspects, the axle is connected to a steering wheel that is a rear wheel of an industrial vehicle. Therefore, claim 1
According to the described invention, the axle is swingable with respect to the body frame. The axle is fixed by locking the damper, and is unlocked by releasing its operation. In this case, the proportional valve controls the pipeline for flowing the hydraulic oil supplied and discharged from the damper between the shielded state and the communication state, and locks the damper to fix the axle by setting the shielded state. , The communication is made possible to swing the axle, and when the output of the fixed operation signal is released, the opening degree of the valve portion is adjusted at a predetermined speed to gradually change from the communication state to the shielding state. Control.

According to the second aspect of the invention, the axle is swingable with respect to the body frame. This axle is
The damper is fixed by being locked and can be rocked by releasing its operation. In this case, the switching valve controls the pipeline for flowing the hydraulic oil supplied to and discharged from the damper between the shielded state and the communication state,
By setting the shield state, the damper is locked to fix the axle, and the axle is swingable by setting the communication state, and when the fixed operation signal is output, the communication state is changed to the shield state. Control. Further, the variable throttle valve provided in the conduit is controlled so that the opening of the valve portion becomes small when the output of the fixed operation signal is released.
Therefore, the hydraulic oil does not suddenly flow out from the damper by the variable throttle valve, so that the fixation of the axle is gradually released at a predetermined speed. Therefore, the fixation of the axle can be released in a stable state.

According to the third aspect of the invention, the load detecting means detects the load acting on the ascending / descending drive means for ascending / descending the cargo handling equipment. The lift position detecting means detects the lift position of the cargo handling equipment. The fixed control means outputs a fixed operation signal when the load detected by the load detection means becomes equal to or higher than the reference pressure value and the lift position becomes equal to or higher than the reference lift reference position.
Therefore, for example, when the lifting position of the cargo handling equipment becomes less than the reference lifting position from the state where the fixed operation signal is output and the output of the fixed operation signal is released, the damper gradually supplies and discharges the hydraulic oil. Since it is started, the cargo handling work in the cargo handling equipment can be stably performed.

According to the invention described in claim 4, the yaw rate detecting means detects the yaw rate acting on the vehicle. The change rate calculation means calculates the change rate of the yaw rate detected by the yaw rate detection means. Then, the fixed control means, when the load detected by the load detection means is equal to or higher than the reference pressure value and the lift position is equal to or higher than the reference lift position,
Alternatively, when the change rate of the yaw rate calculated by the change rate calculating means becomes larger than the reference rate value, the fixed operation signal is output. Therefore, even when the output of the fixed operation signal is released during the cargo handling work in the cargo handling equipment or the traveling of the industrial vehicle, the fixation of the axle is gradually released, so that the cargo handling work in the cargo handling equipment and the traveling of the industrial vehicle are stabilized. It can be carried out.

According to the invention of claim 5, the yaw rate detecting means detects the yaw rate acting on the vehicle. The change rate calculation means calculates the change rate of the yaw rate detected by the yaw rate detection means. Then, the fixed control means outputs a fixed operation signal when the change rate of the yaw rate calculated by the change rate calculating means becomes equal to or larger than the reference rate value. Therefore, even if the fixed operation signal is released when the industrial vehicle is running, the axle fixation is gradually released,
Industrial vehicles can be driven in a stable state.

According to the sixth aspect of the present invention, the axle is connected to the steered wheels which are the rear wheels of the industrial vehicle. Therefore,
The turning property and the operability of the industrial vehicle can be improved.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a side view showing a forklift 1 as an industrial vehicle.

The forklift 1 is provided with a pair of left and right outer masts 2 on its front part, and an inner mast 3 is arranged between the outer masts 2 so as to be able to move up and down. A fork 4 is provided on the inner mast 3 so as to be able to move up and down. That is,
The fork 4 moves up and down along the outer mast 2.

A tilt cylinder 5 is connected between the outer mast 2 and the body frame 1a of the forklift 1. The body 5a of the tilt cylinder 5 is connected to the vehicle body frame 1a, and the piston rod 5b of the tilt cylinder 5 is connected to the outer mast 2. That is,
As the piston rod 5b of the tilt cylinder 5 expands and contracts, the outer mast 2 is tilted and the fork 4 is tilted. The inner mast 3 has a body 6a
The piston rod 6b of the lift cylinder 6, which is connected to the vehicle body frame 1a, is connected. That is, the inner mast 3 moves up and down based on the expansion and contraction of the piston rod 6b of the lift cylinder 6, and as the inner mast 3 moves up and down,
The fork 4 moves up and down.

At the front portion of the vehicle body frame 1a of the forklift 1, a pair of left and right front wheels 7 are provided. Each front wheel 7
Is connected to the engine M via a differential ring gear U and a transmission D, and each front wheel 7 is driven by the engine M.
That is, the front wheels 7 are driving wheels. A pair of left and right rear wheels 8 are provided at the rear of the main body 1a of the forklift 1.

FIG. 2 shows a connecting structure for connecting the rear wheels 8. A rear axle 11 extending in the vehicle width direction is provided at the lower rear portion of the vehicle body frame 1a of the forklift 1 so as to be swingable (rotatable) about a center pin 11a. The rear wheels 8 are provided on both the left and right sides of the rear axle 11.
Are connected. The rear wheel 8 is a steering wheel 10 in the cab 9
The steered wheels are steered based on the operation of. The rear axle 11 constitutes an axle connecting the two rear wheels 8.

A hydraulic damper (hereinafter simply referred to as “damper”) 12 is connected between the vehicle body frame 1a and the rear axle 11. The damper 12 is a double-acting hydraulic cylinder. That is, the damper 12 is the rear wheel 8
It is designed to absorb the force acting on.

The damper 12 includes a cylindrical body 12a,
And a piston 12b disposed in the body 12a. The piston 12b has a piston rod 12c
Are connected. At the tip of the piston rod 12c,
The rear axle 11 is connected.

The inside of the damper 12 is the first piston 12b.
It is partitioned into a room R1 and a second room R2. A first hydraulic pipe P1 is connected to the first chamber R1, and a second hydraulic pipe P2 is connected to the second chamber R2. The first hydraulic pipe P1 and the second hydraulic pipe P2 are connected to the solenoid proportional valve 13. Further, a third hydraulic pipe P3 and a fourth hydraulic pipe P4 are connected to the solenoid proportional valve 13.

FIG. 6 is a schematic diagram showing an example of the solenoid proportional valve 13. The solenoid proportional valve 13 includes a cylindrical body 14 and a cylindrical spool 15. Further, the electromagnetic proportional valve 13 includes an electromagnetic solenoid 13a, a spring 13b, and the like.

The first to fourth hydraulic pipes P1 to P4 are connected to first to fourth insertion holes E1 to E4 formed in the body 14. The spool 15 has a first hydraulic pipe P1 and a third hydraulic pipe P1.
A first communication groove F1 and a second communication groove F1 for communicating with the hydraulic pipe P3
A second communication groove F2 for connecting the hydraulic pipe P2 and the fourth hydraulic pipe P4 is formed.

In this case, the first insertion hole E1 and the third insertion hole E
3 and the first communication groove F1 and the like form a valve portion X1 that adjusts the flow rate of the hydraulic oil that flows between the first hydraulic pipe P1 and the third hydraulic pipe P3. The opening degree between the first insertion hole E1 (or the third insertion hole E3) and the first communication groove F1 is determined by the valve portion X.
The opening is 1. Also, the second insertion hole E2 and the fourth insertion hole E4
And the second communication groove F2, etc.
A valve portion X2 for adjusting the flow rate of the hydraulic oil flowing between the hydraulic pipe P4 and the hydraulic pipe P4 is formed. The opening degree with the second insertion hole E2 (or the fourth insertion hole E4) is the opening degree of the valve portion X2.

That is, the opening degrees of the valve portions X1 and X2 are adjusted according to the movement of the spool 15, and the opening degrees of the valve portions X1 and X2 are the same. The movement of the spool 15 is performed based on the excitation of the electromagnetic solenoid 13a. In the present embodiment, when the electromagnetic solenoid 13a is not excited, the electromagnetic proportional valve 13 connects the first insertion hole E1 and the third insertion hole E3 by the spring force of the spring 13b.
The second insertion hole E2 and the fourth insertion hole E4 are in a fully open state in which they communicate with each other.

The third hydraulic pipe P3 is connected to the fourth hydraulic pipe P4. A reservoir 16 that stores hydraulic oil is connected to the fourth hydraulic pipe P4. The second hydraulic pipe P2,
Further, fixed throttle valves 17 and 18 are provided between the reservoir 16 of the fourth hydraulic pipe P4 and the connecting portion. The damper 12 and the solenoid proportional valve 13 constitute an axle fixing mechanism. In the present embodiment, for example, the reservoir 1
6 also supplies hydraulic oil to the lift cylinder 6 that raises and lowers the fork 4. That is, the hydraulic oil supplied to and discharged from the damper 12 and the hydraulic oil supplied to and discharged from the lift cylinder 6 are both supplied from the same supply source.

As shown in FIG. 1, the forklift 1
A gyroscope 20 is provided as a yaw rate detecting means on the balance weight 19 provided at the rear portion. The gyroscope 20 is a piezoelectric gyroscope including a piezoelectric element, and is adapted to detect the angular velocity of the forklift 1 during turning, for example. This angular velocity means the yaw rate ω.

Further, as shown in FIGS. 1 and 3, the acceleration sensor 21 is provided at the center position of both front wheels 7 of the forklift 1.
Is provided. The acceleration sensor 21 is installed in the instrument panel W in the cab 9. The acceleration sensor 21 detects a lateral acceleration that actually acts when the forklift 1 is turning, that is, an actual acceleration. That is, the acceleration sensor 21 detects the centrifugal force that actually acts, that is, the actual centrifugal force Fa.

As shown in FIGS. 1 and 5, the outer mast 2
A limit switch 24 as a lift position detecting means for detecting the lift position of the fork 4 is installed on the upper part of the. The limit switch 24 is provided at a position approximately 1/4 above the outer mast 2.

Further, at the base end of the lift cylinder 6, there is provided a pressure sensor 25 as load detecting means for detecting the hydraulic pressure y of the working oil acting on the lift cylinder 6. As shown in FIG. 2, the rear wheel 8 is provided with a steering angle sensor 22 that detects a steering angle θ of the rear wheel 8.

As shown in FIG. 4, the forklift 1 is provided with a vehicle speed sensor 23 for detecting the traveling speed v of the forklift 1 by detecting the rotation of the differential ring gear U. In the present embodiment, the vehicle speed sensor 2
3 and the gyroscope 20 constitute a lateral force detecting means.

Next, the electrical configuration of the control device for an industrial vehicle configured as described above will be described with reference to the electrical block diagram shown in FIG. The control device for an industrial vehicle includes a controller 31 as fixed control means. The controller 31 is composed of a CPU (central processing unit) and the like, and the controller 31 is provided with a memory 31a composed of a RAM and the like and a timer 31b.

The gyroscope 20, the acceleration sensor 21, the steering angle sensor 22 and the vehicle speed sensor 23 are connected to the controller 31. Furthermore, the controller 3
A limit switch 24 and a pressure sensor 25 are connected to 1. In addition, the controller 31 includes a solenoid proportional valve 13
Is connected.

The gyroscope 20 detects the yaw rate ω when the forklift 1 is turning, and outputs an angular velocity signal indicating the yaw rate ω to the controller 31.

The acceleration sensor 21 detects the actual centrifugal force Fa that acts when the forklift 1 turns, and outputs an actual centrifugal force signal indicating the actual centrifugal force Fa to the controller 31.

The steering angle sensor 22 is a rear wheel 8 which is a steered wheel.
The steering angle θ is detected, and a steering angle signal indicating the steering angle θ is output to the controller 31. The vehicle speed sensor 23 detects the traveling speed v of the forklift 1,
The controller 31 outputs a traveling speed signal indicating the traveling speed v.
Output.

The limit switch 24 is turned on when the fork 4 is at the reference lift position Z or higher, and outputs the ON signal to the controller 31. The reference lift position Z is approximately 1/4 from above the outer mast 2.
In the position. When the fork 4 is below the reference elevation position Z, the limit switch 24 is off.

The pressure sensor 25 detects the hydraulic pressure y acting on the lift cylinder 6 and outputs a hydraulic pressure signal indicating the hydraulic pressure y to the controller 31. The controller 31 is configured to calculate the change rate of the angular velocity, that is, the change rate of the yaw rate ω (yaw rate change rate) Δω / ΔT based on the angular velocity signal from the gyroscope 20. The yaw rate change rate Δω / ΔT means angular acceleration. The controller 31 is the angular velocity,
That is, the yaw rate change rate Δω / ΔT is obtained by differentiating the yaw rate ω with respect to time.

The controller 31 calculates the acceleration acting in the lateral direction based on the traveling speed signal from the vehicle speed sensor 23 and the angular velocity detection signal from the gyroscope 20. That is, the centrifugal force is calculated. This centrifugal force is the calculated centrifugal force Fb obtained by calculation, and has a slightly different value from the actual centrifugal force Fa actually detected by the acceleration sensor 21 due to the difference in the way of obtaining the same. The calculated centrifugal force Fb is obtained by calculating the product of the traveling speed v and the angular velocity ω as shown in the following expression (1).

Fb = vω (1) The memory 31a of the controller 31 stores a reference ratio value serving as a reference for the yaw rate change ratio Δω / ΔT. The reference ratio value is an upper reference ratio value K1 which is a reference when the yaw rate change ratio Δω / ΔT is increasing, and a lower reference ratio value K2 which is a reference when the yaw rate change ratio Δω / ΔT is decreasing. Consists of. That is, the memory 31a
An upper reference ratio value K1 and a lower reference ratio value K2 are stored in.

Further, the memory 31a of the controller 31 stores a reference centrifugal force value serving as a reference for the centrifugal force acting on the forklift 1. The reference centrifugal force value is an upper centrifugal force value H1 that is a reference when the centrifugal force is increasing, and a lower reference centrifugal force value H2 that is a reference when the centrifugal force is decreasing.
Consists of That is, the upper reference centrifugal force value H is stored in the memory 31a.
1 and the lower reference centrifugal force value H2 are stored.

Further, the memory 31a of the controller 31 stores a reference pressure value N serving as a reference for the hydraulic pressure y acting on the lift cylinder 6. As shown in FIG. 9, the controller 31 compares the yaw rate change rate Δω / ΔT calculated based on the angular velocity signal with the upper reference change rate value K1, and the yaw rate change rate Δω / ΔT shows the upper reference change rate value K1. When the value becomes larger than the upper reference change ratio value K1 from the following values, the output of the fixed operation signal is started.

The controller 31 outputs the fixed operation signal, and the yaw rate change rate Δω / ΔT calculated based on the angular velocity signal and the lower reference rate value K2.
When the yaw rate change ratio Δω / ΔT becomes a value smaller than the lower reference ratio value K2 than the lower reference ratio value K2, the stop control for stopping the output of the fixed operation signal is performed. It is like this.

In this embodiment, the controller 31
In the stop control, the output of the fixed operation signal is not immediately stopped, but the output of the fixed operation signal is stopped after the elapse of the predetermined time T. That is, the controller 3
1 indicates that the yaw rate change rate Δω / ΔT is the lower reference rate value K2.
When the value becomes smaller than the lower reference ratio value K2 from the above value, the controller 31 causes the timer 31b to start counting from that time, and stops outputting the fixed operation signal when the timer 31b measures the predetermined time T. During this timing, the controller 31 determines that the yaw rate change rate Δω / Δ
When T becomes equal to or higher than the lower reference ratio K2, the timing is stopped. That is, the controller 31 outputs the fixed operation signal for the predetermined time T even if the yaw rate change rate Δω / ΔT is less than the lower reference rate value K2.

As shown in FIG. 10, the controller 31
When the absolute value of the calculated centrifugal force Fb becomes larger than the upper reference centrifugal force value H1 from a value equal to or lower than the upper reference centrifugal force value H1, the fixed operation signal is started to be output.

The controller 31 stops outputting the fixed operation signal when the absolute value of the calculated centrifugal force Fb becomes a value smaller than the lower reference centrifugal force value H2 while the fixed operation signal is being output. Has become.

That is, in the present embodiment, the controller 31 outputs a fixed operation signal when at least one of the following conditions 1) to 5) is satisfied. That is, each of the following conditions 1) to 5) is a traveling fixed condition for fixing the axle based on the traveling of the forklift 1.

1) When the yaw rate change rate Δω / ΔT is larger than the upper reference rate value K1. 2) The yaw rate change ratio Δω / ΔT is the upper reference ratio value K.
When the value is greater than 1 and is less than or equal to the upper reference ratio value K1, and is greater than the lower reference ratio value K2.

3) From the state shown in 2) above, the yaw rate change rate value Δω / ΔT becomes smaller than the lower reference change rate value K2 and becomes smaller than the lower reference change rate value K2 within a predetermined time T. When.

4) When the absolute value of the calculated centrifugal force Fb is larger than the upper reference centrifugal force value H1. 5) When the absolute value of the calculated centrifugal force Fb changes from a value larger than the upper reference centrifugal force value H1 to a value less than or equal to the upper reference centrifugal force value H1 and larger than the lower reference centrifugal force value H2.

Further, the controller 31 has a pressure sensor 25.
The weight of the load placed on the fork 4 is determined based on the detection signal from the. Further, the controller 31 is adapted to calculate the center of gravity of the forklift 1 based on the detection signal from the pressure sensor 25, that is, the weight of the load placed on the fork 4. The center of gravity of the forklift 1 means the center of gravity of the entire forklift including the vehicle body and the load. In this case, the controller 31 uses the outer mast 2 as shown by the alternate long and short dash line in FIG.
Calculates the center of gravity when is tilted rearmost.

Further, the controller 31 outputs a fixed operation signal based on the ON signal from the limit switch 24 and the pressure signal from the pressure sensor 25. That is, the fixed operation signal is output under the following condition 6). The condition 6) is a cargo handling fixing condition for fixing the rear axle 11 based on the cargo handling work of the forklift 1.

6) When the ON signal is output from the limit switch 24 and the hydraulic pressure y acting on the lift cylinder 6 is equal to or higher than the reference pressure value N. In this case, the controller 31
When at least one of the traveling fixed conditions 1) to 5) is satisfied, the fixed operation signal is output with priority given to the traveling fixed condition regardless of the cargo handling fixed condition 6). There is. That is, the controller 31 outputs the fixed operation signal when at least one of the traveling fixed conditions or the cargo handling fixed conditions 1) to 6) is satisfied.

Then, the controller 31 releases the output of the fixed operation signal when none of the traveling fixed conditions 1) to 5) or the cargo handling fixed condition 6) is satisfied.

The solenoid proportional valve 13 is an electromagnetic solenoid 1
The spool 15 is moved based on the excitation state of 3a, and the opening degree of the valve portions X1 and X2 of the solenoid proportional valve 13 is adjusted.
The electromagnetic solenoid 13a is excited by an exciting current, and moves the spool 15 based on the current value of the exciting current. That is, the spool 15 moves based on the current value of the exciting current, and the opening degrees of the valve portions X1 and X2 are adjusted. This current value fluctuates between the minimum current value and the maximum current value.
In the present embodiment, the minimum current value means a current of 0 amperes, that is, a state in which no current flows. In this case, the spool 15 is urged and moved only by the spring force of the spring 13b, and the valve portion X1, shown in FIG.
The X2 is positioned so as to be fully opened.

When the maximum current value is flowing, the spool 15 moves against the spring force and the valve portion X1,
The opening of X2 is fully closed. That is, the opening degrees of the valve portions X1 and X2 become smaller as the current value of the exciting current becomes larger, and become larger as the current value of the exciting current becomes smaller. In the present embodiment, the signal in which the current value of the exciting current is the maximum current value is the fixed operation signal.

In this case, the controller 31 reduces the current value of the exciting current from the maximum current value to the minimum value when none of the traveling fixed conditions 1) to 5) or the fixed cargo handling condition 6) is satisfied. The current value is gradually decreased at a predetermined rate. That is, the controller 31 releases the fixed operation signal whose current value is the maximum current value and outputs the fixed release signal. The fixed release signal is a signal that gradually reduces the current value of the exciting current from the maximum current value to the minimum current value at a predetermined rate.

When this lock release signal is output, the electromagnetic solenoid 13a is reduced in accordance with the decrease in the current value of the lock release signal.
Changes the excitation state, and the spool 15 moves at a speed based on the excitation state. That is, the valve portions X1 and X2 are gradually opened at a predetermined speed according to the speed of the spool 15.

Further, the controller 31 satisfies at least one of the traveling fixed conditions or the fixed cargo handling conditions 1) to 6) from the state in which the fixed operation signal is not output, and starts the output of the fixed operation signal. In this case, the current value is immediately raised from the minimum current value to the maximum current value, and the fixed operation signal is output. Therefore, the solenoid proportional valve 13 closes the valve portions X1 and X2 immediately when the fixed operation signal is output,
The first and second hydraulic pipes P1 and P2 are shielded and the damper 12 is locked. As a result, the rear axle 11 cannot swing, and the damper 12 fixes the rear axle 11.

Next, the operation and effect of the control device for the industrial vehicle configured as described above will be described. As shown in FIG. 8, when the cargo handling fixing condition 6) is satisfied from the state where the fixed operation signal is not output, the controller 31 immediately outputs the fixed operation signal and the solenoid proportional valve 13 outputs the fixed operation signal. The valve portions X1 and X2 are immediately closed based on the above. Therefore, the solenoid proportional valve 12 shields the first hydraulic pipe P1 and the third hydraulic pipe P3, and the second hydraulic pipe P2 and the fourth hydraulic pipe P3.
The hydraulic pipe P4 is shielded, the damper 12 is locked, and the rear axle 11 is fixed.

Next, when the cargo handling fixing condition 6) is released by lowering the lift position of the fork 4 from the state where the rear axle 11 is fixed, the controller 31 changes the current value from the maximum current value to the minimum current value. The value is gradually decreased at a predetermined rate. That is, the controller 31 terminates the output of the fixed operation signal having the maximum current value and outputs the fixed release signal. Then, the spool 15 moves the opening degrees of the valve portions X1 and X2 from the fully open state to the fully closed state as the current value of the fixing release signal decreases. In this case, spool 1
5 gradually moves at a predetermined speed as the current value of the fixed release signal decreases. Therefore, the valve portions X1 and X2 are gradually opened at a predetermined speed. Therefore, the damper 12 gradually starts supplying and discharging the hydraulic oil, and the fixation of the rear axle 11 is gradually released.

When releasing the fixing of the rear axle 11 in this way, the valve portions X1 and X2 are gradually opened, and the damper 1
2 gradually starts supplying and discharging the hydraulic oil, so that the flow rate of the hydraulic oil supplied to and discharged from the lift cylinder 6 moving up and down the fork 4 does not change rapidly. Therefore, even if the rear axle 11 is released from the fixed state during the cargo handling work, the cargo handling work by the fork 4 is performed in a stable state.

According to this embodiment, the following (a) to
It has the effect shown in (e). (A) Rear axle 11 based on the output of the fixed operation signal
When the output of the fixed operation signal is released from the state where is fixed, the solenoid proportional valve 13 gradually opens the valve portions X1 and X2, and gradually releases the swing of the rear axle 11. Therefore, the shock that occurs when the rear axle 11 is released from the fixed state is relieved, and the rear axle 11 is stable in a stable state.
Can be unlocked. Moreover, the solenoid proportional valve 13 gradually opens its valve portions X1 and X2 as the duty ratio of the fixing release signal output from the controller 31 decreases. Therefore, the solenoid proportional valve 13 can easily and reliably gradually release the swing of the rear axle 11 as the duty ratio decreases.

(B) Especially, since the lift position of the fork 4 is reduced from the state where the rear axle 11 is fixed by the cargo handling fixing condition 6), the cargo handling fixing condition 6) is not satisfied and the rear axle 11 is fixed. When it is released, the valve portions X1 and X2 are gradually opened, and the supply and discharge of the hydraulic oil to and from the damper 12 is gradually started. Therefore, it is possible to prevent the hydraulic oil from suddenly flowing into the damper 12 side due to the release of the fixing of the rear axle 11 and the operation of the lift cylinder 6 becoming unstable. Therefore, the impact acting on the lift cylinder 6 when the rear axle 11 is released from the fixed state can be reduced, and the cargo handling work by the fork 4 can be smoothly performed in a stable state.

(C) For example, when the forklift 1 is turning, the rear axle 11 is fixed based on the yaw rate change rate Δω / ΔT, and the fixed condition is released. Even when it is released, the fixing of the rear axle 11 is gradually released, so the impact generated when releasing the fixing of the rear axle 11 can be reduced, and the running performance and turning performance of the forklift 1 can be improved.

(D) Similar to the effect of (c) above, the fixed condition of the rear axle 11 is released from the state where the rear axle 11 is fixed based on the calculated centrifugal force Fb, so that the rear axle 11 is released from the fixed state. In this case, the rear axle 11 is gradually released from the fixed state, so that the impact generated when the rear axle 11 is released from the fixed state can be reduced, and the running performance and turning performance of the forklift 1 can be improved.

Further, in the present embodiment, the rear axle 11 is fixed based on the yaw rate change rate Δω / ΔT and the calculated centrifugal force Fb. Therefore, the forklift 1 can be swung more smoothly, and the swivelability of the lift 1 can be improved.

Furthermore, in the present embodiment, as in the effect shown in (b) above, the impact acting on the lift cylinder 6 when the rear axle 11 is released from being fixed can be reduced, and the fork 4 can smoothly move in a stable state. Cargo handling can be performed. Therefore, in the forklift 1, the cargo handling work by the fork 4 can be performed in a stable state, and the traveling property and the turning property thereof can be improved.

(E) In the forklift 1, the rear axle 11 connecting the rear wheels 8 which are the steered wheels is swingably provided, and the rear axle 11 has a yaw rate change ratio Δω /
Since it is configured to be fixed based on ΔT and the calculated centrifugal force Fb, the turning performance and operability of the forklift 1 can be further improved.

The present invention is not limited to the above-mentioned embodiment, and can be carried out as follows with appropriate changes without departing from the spirit of the invention. (1) In the above embodiment, the solenoid proportional valve 13 is used to gradually release the fixing of the rear axle 11. However, as shown in FIG. 11, the solenoid proportional valve 13 is replaced with an electromagnetic switching valve 41. The variable throttle valve 42 may be used instead of the fixed throttle valve 17 to gradually release the fixation of the rear axle 11.

The electromagnetic switching valve 41 includes a body and a spool, and a flow valve portion 43 and a stop valve portion 44 are formed on the spool. The electromagnetic switching valve 41 adjusts the hydraulic oil flowing through the hydraulic pipes P1 to P4 by moving the spool with respect to the body and selecting the flow valve portion 43 or the stop valve portion 44.

When the flow valve portion 43 is selected, the first hydraulic pipe P1 and the third hydraulic pipe P3 are communicated with each other, and the second hydraulic pipe P3 is connected to the second hydraulic pipe P3.
The hydraulic pipe P2 and the fourth hydraulic pipe P4 communicate with each other. This time,
The hydraulic oil in the first chamber R1 and the second chamber R2 of the damper 12 is in communication with the reservoir 16. Therefore, each first
In the chamber R1 and the second chamber R2, hydraulic oil can flow in and out, and the damper 12 makes the rear axle 11 rotatable about the center pin 11a, that is, swingable.

When the stop valve portion 44 is selected, the working oil flowing through the hydraulic pipes P1 to P4 is blocked. Therefore, the hydraulic oil cannot enter or exit the first chamber R1 and the second chamber R2. That is, the rear axle 11 becomes unswingable and is fixed by the damper 12.

The variable throttle valve 42 is formed with a large throttle portion having a large throttle diameter and a small throttle portion having a small throttle diameter, so that the variable throttle valve 42 can change the throttle diameter in two steps. There is.

As shown in FIG. 12, the controller 31 is connected with the electromagnetic switching valve 41 and the variable throttle valve 42, and the gyroscope 20, the acceleration sensor 21, the steering angle sensor 22, the vehicle speed sensor 23, and the limit switch. 24 and the pressure sensor 25 are connected.

The controller 31 includes various sensors 20 to 20.
25) The traveling fixed condition 1) to be calculated based on 25 etc.
5) or at least one of the fixed conditions 6)
When the two conditions are satisfied, the fixed operation signal is output to the electromagnetic switching valve 41 and the variable throttle valve 42.

When the fixed operation signal is output, the electromagnetic switching valve 41 selects the stop valve portion 44, shields the first and second hydraulic pipes P1 and P2, and locks the damper 12. Therefore, the rear axle 11 cannot swing and the damper 12 fixes the rear axle 11.

The electromagnetic switching valve 41 selects the flow valve portion 43 when the fixed operation signal is not output, and the damper 12
The first chamber R1 and the second chamber R2 are set to a state in which hydraulic oil can flow in and out. Therefore, the rear axle 11 is in a swingable state.

As shown in FIG. 13, the variable throttle valve 42 is
When the fixed operation signal is not output, the large aperture section is selected. When the fixed operation signal is output from this state, the throttle of the variable throttle valve 42 is switched from the large throttle portion to the small throttle portion. Next, when the fixed operation signal is released, the variable throttle valve 42 switches the throttle from the small throttle to the large throttle after a predetermined predetermined time J has elapsed from the time when the fixed operation signal was released.

According to the variable throttle valve 42 thus constructed, the fixed operation signal is output, and when the output of the fixed operation signal is released from the state where the rear axle 11 is fixed,
The throttle of the variable throttle valve 42 is a small throttle portion. Therefore, when the electromagnetic switching valve 42 makes the rear axle 11 swingable based on the release of the fixed operation signal, the throttle of the variable throttle valve 42 is a small throttle portion, so that the rear axle 11 suddenly moves. The swingable state is prevented.

(2) In the above embodiment, the fixed throttle valve 18 may be the variable throttle valve 42. (3) In the above-described another embodiment (1), the variable throttle valve 42 whose throttle can be adjusted in two stages is used, but a variable throttle valve which can be adjusted in multiple stages may be used.

(4) In the above embodiment, as shown in FIG. 14, the electromagnetic proportional valve 13 shown in FIG. 2 and the variable throttle valve 42 shown in FIG. 11 may be used together. In this case, as shown in FIG. 15, the electromagnetic proportional valve 13 and the variable throttle valve 42 are both connected to the controller 31, and the gyroscope 20, the acceleration sensor 21, the steering angle sensor 22, the vehicle speed sensor 23, and the limit switch 24 are connected. And the pressure sensor 25 are connected.

The controller 31 includes various sensors 20 to 20.
25) The traveling fixed condition 1) to be calculated based on 25 etc.
5) or at least one of the fixed conditions 6)
When the two conditions are satisfied, the fixed operation signal is output to the solenoid proportional valve 13 and the variable throttle valve 42. That is, the controller 31 outputs a fixed operation signal or the like to the electromagnetic proportional valve 13 and the variable throttle valve 42 to control the swing of the rear axle 11. That is, the controller 31 controls the electromagnetic proportional valve 13 and the variable throttle valve 42 described in the above embodiment to control the swing of the rear axle 11.

When the fixed operation signal is output, the solenoid proportional valve 13 locks the damper 12 and fixes the rear axle 11. At this time, the variable throttle valve 42 selects the small throttle portion,
Since the throttle diameter is made small, the flow rate of the hydraulic oil supplied to and discharged from the damper 12 can be made small, and the rear axle 11 can be fixed more quickly and reliably.

When the output of the fixed operation signal is released,
The solenoid proportional valve 13 gradually opens the valve portions X1 and X2 as the current value of the fixing release signal decreases, and gradually opens the rear axle 11
Is released. At this time, since the small throttle portion of the variable throttle valve 42 is selected, the fixation of the rear axle 11 can be released more slowly and reliably.

(5) In the above embodiment, the variable throttle valve 42 always selects the large throttle valve portion, and only when the fixed operation signal is released, the small throttle valve portion is opened for a predetermined time J from the release time. It may be configured to be selected.

(6) In the above embodiment, the fork 4 is attached to the outer mast 2 instead of the limit switch 24.
You may use the position sensor which used the optical scale etc. which detect the elevation position of. In this case, the controller 31
The lift position of the fork 4 is determined based on the detection signal from the position sensor, and when the lift position is equal to or higher than the reference lift position N, the controller 31 outputs a fixed operation signal.

(7) In the above embodiment, the controller 31 is configured to compare the calculated centrifugal force Fb with the upper reference centrifugal force value H1 and the lower reference centrifugal force value H2 and output a fixed operation signal. The controller 31 determines that the actual centrifugal force F
It may be configured to compare a with the upper reference centrifugal force value H1 and the lower reference centrifugal force value H2 and output the fixed operation signal. In this case, since the centrifugal force acting on the forklift 1 does not need to be calculated based on the traveling speed v and the yaw rate ω, the controller 31 can easily output the fixed operation signal based on the actual centrifugal force Fa.

(8) In the above embodiment, the opening of the solenoid proportional valve 13 may be set by changing the duty ratio of the exciting current. This duty ratio is 0% to 1
It is set between 00%. When the duty ratio is 0%, the electromagnetic solenoid 13a is demagnetized and the valve portions X1 and X2 are demagnetized.
The opening of is fully open. When the duty ratio is 100%, the excitation state of the electromagnetic solenoid 13a is maximized and the valve portions X1 and X2 are closed. That is, the valve part X
The opening degrees of 1 and X2 become smaller as the duty ratio becomes larger, and become larger as the duty ratio becomes smaller. in this case,
A signal having a duty ratio of the exciting current of 100% becomes a fixed operation signal. When the rear axle 11 is released from being fixed, the duty ratio is gradually increased to 100% at a predetermined rate.
From 0% to 0%, the fixing of the rear axle 11 is gradually released.

Among the technical ideas grasped from the above-mentioned embodiments, technical ideas other than the claims will be described below together with effects. (1) In the invention of claim 4, the industrial vehicle is
Further, a lateral force detecting means for detecting a lateral force acting on the vehicle is provided, and in the fixed control means, the load detected by the load detecting means becomes a reference pressure value or more, and the lift position is a reference lift position or more. When the change rate of the yaw rate becomes larger than the reference rate value based on the change rate of the yaw rate calculated by the change rate calculating means, or the lateral force is the reference force value. A control device for an industrial vehicle that outputs a fixed operation signal when: According to this industrial vehicle control device, for example, even when the output of the fixed operation signal is released during the cargo handling work in the cargo handling equipment or the traveling of the industrial vehicle, the fixation of the axle is gradually released, so the cargo handling work in the cargo handling equipment Also, it is possible to stably drive the industrial vehicle.

(2) In the invention of claim 1 or 2, the industrial vehicle is provided with a lateral force detecting means for detecting a lateral force acting on the vehicle, and the fixed control means is based on the lateral force. A control device for an industrial vehicle that outputs a fixed operation signal when the force falls below a force value. According to this control device for an industrial vehicle, even if the output of the fixed operation signal is released during traveling of the industrial vehicle, the fixation of the axle is gradually released, so that the industrial vehicle can be stably driven.

[0098]

As described above in detail, according to the first aspect of the invention, when the output of the fixed operation signal is released from the state where the axle is fixed, the opening degree of the valve portion is changed at a predetermined speed. Since it is adjusted and gradually controlled from the communication state to the blocked state,
You can gradually unlock the axle.

According to the second aspect of the invention, the valve portion of the variable throttle valve is small when the output of the fixed operation signal is released from the state where the axle is fixed. Therefore, the supply and discharge of the hydraulic oil to and from the damper is gradually started, so that the fixation of the axle can be gradually released.

According to the third aspect of the present invention, for example, when the lifting position of the cargo handling equipment becomes less than the reference lifting position from the state where the fixed operation signal is output, and the output of the fixed operation signal is released. Since the damper gradually starts supplying and discharging the hydraulic oil, the cargo handling work in the cargo handling equipment can be stably performed.

According to the fourth aspect of the present invention, even if the output of the fixed operation signal is released during the cargo handling work in the cargo handling equipment or the traveling of the industrial vehicle, for example, the fixation of the axle is released, so the cargo handling equipment. The cargo handling work and the traveling of the industrial vehicle can be stably performed.

According to the fifth aspect of the present invention, even if the fixed operation signal is released while the industrial vehicle is running, for example, the fixation of the axle is gradually released, so that the industrial vehicle can be run in a stable state. it can.

According to the sixth aspect of the present invention, since the axle is a shaft that connects the steered wheels that are the rear wheels of the industrial vehicle,
The turning property and the operability of the industrial vehicle can be improved.

[Brief description of drawings]

FIG. 1 is a side view showing a forklift.

FIG. 2 is a schematic configuration diagram showing a mechanism for fixing a rear axle.

FIG. 3 is a plan view showing a forklift.

FIG. 4 is a schematic configuration diagram showing a mechanism that connects both front wheels of a forklift.

FIG. 5 is a schematic side view showing a front portion of a forklift.

FIG. 6 is a schematic configuration diagram showing an outline of an electromagnetic proportional valve.

FIG. 7 is an electric block diagram for controlling swing of a rear axle of a forklift truck and fixing the rear axle.

FIG. 8 is an explanatory diagram for explaining the operation of the solenoid proportional valve.

FIG. 9 is an explanatory diagram in the case where the swing of the rear axle is controlled by the change rate of the yaw rate.

FIG. 10 is an explanatory diagram in the case where the swing of the rear axle is controlled by a calculated centrifugal force.

FIG. 11 is a schematic configuration diagram showing a mechanism for fixing a rear axle in another example.

FIG. 12 is an electric block diagram for controlling swing of a rear axle of a forklift truck in another example and fixing the rear axle.

FIG. 13 is an explanatory view illustrating the operation of a variable throttle valve in another example.

FIG. 14 is a schematic configuration diagram showing a mechanism for fixing a rear axle in another example.

FIG. 15 is an electric block diagram for controlling swing of a rear axle of a forklift truck in another example and fixing the rear axle.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Forklift as an industrial vehicle, 1a ... Body frame, 4 ... Fork as cargo handling equipment, 8 ... Rear wheel, 11
... rear axle constituting an axle, 12 ... hydraulic damper, 13 ... electromagnetic proportional valve as proportional valve, 20 ... lateral force detecting means and gyroscope as yaw rate detecting means, 23 ... lateral force detecting A vehicle speed sensor constituting the means, 24 ... a limit switch as a lift position detecting means, 25 ... a pressure sensor as a load detecting means, 31 ... a controller as a change ratio calculating means and a fixed control means, 41 ... an electromagnetic switching valve, 42 … Variable throttle valve,
P1 to P4 ... First to fourth hydraulic pipes.

Claims (6)

[Claims] 1. An industrial vehicle in which an axle is swingably supported in a vertical direction with respect to a body frame, and a fixing control means for outputting a fixing operation signal for fixing the axle, the body frame and the axle. A damper, which is disposed between the dampers and supplies and discharges the hydraulic oil according to the swing of the axle, and a pipe line through which the hydraulic oil supplied and discharged from the damper flows are controlled between a shielded state and a communicating state, and the shielded By setting the state, the damper is locked to fix the axle, and by making it in the communicating state, the axle can be swung, and when the output of the fixed operation signal is released, the valve portion opens at a predetermined speed. A control device for an industrial vehicle, comprising: a proportional valve that adjusts the degree to gradually control from a communication state to a closed state. 2. In an industrial vehicle in which an axle is swingably supported in a vertical direction with respect to a body frame, a fixing control means for outputting a fixing operation signal for fixing the axle, and the body frame and the axle. A damper disposed between the dampers for supplying / discharging the hydraulic oil in accordance with the swing of the axle, and a pipeline for flowing the hydraulic oil supplied / discharged to / from the damper,
Controls between the shielded state and the communicating state, locks the damper to fix the axle by setting the shielded state, and makes the axle swingable by setting the communicating state and outputs the fixed operation signal. And a switching valve that controls from a communication state to a closed state, and that the opening degree of the valve section is set to be small for at least a predetermined time from the time when the output of the fixed operation signal is released, which is provided in the pipeline. Control device for an industrial vehicle, comprising: 3. The industrial vehicle comprises: load detecting means for detecting a load acting on an elevating and lowering drive means for moving the cargo handling equipment up and down; and lifting height position detecting means for detecting a lifting height position of the cargo handling equipment, 3. The industrial vehicle according to claim 1, wherein the fixed control unit outputs a fixed operation signal when the load detected by the load detection unit is equal to or higher than a reference pressure value and the lift position is equal to or higher than the reference lift position. Control device. 4. The industrial vehicle further comprises yaw rate detecting means for detecting a yaw rate acting on the vehicle, and change rate calculating means for calculating a change rate of the yaw rate detected by the yaw rate detecting means, The fixed control means, when the load detected by the load detection means is equal to or higher than the reference pressure value and the lift position is equal to or higher than the reference lift position, or the change in the yaw rate calculated by the change ratio calculation means. 4. The control device for an industrial vehicle according to claim 3, wherein when the rate of change of the yaw rate becomes larger than the reference rate value based on the rate, a fixed operation signal is output. 5. The industrial vehicle comprises yaw rate detecting means for detecting a yaw rate acting on the vehicle, and change rate calculating means for calculating a change rate of the yaw rate detected by the yaw rate detecting means. The control means outputs a fixed operation signal when the change rate of the yaw rate becomes larger than a reference rate value based on the change rate of the yaw rate calculated by the change rate calculating means. 2. The control device for an industrial vehicle described in 2. 6. The control device for an industrial vehicle according to claim 1, wherein the axle connects a steered wheel that is a rear wheel of the industrial vehicle.