JPH09309308A - Control device of industrial vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To turn an industrial vehicle speedily and in a stabler state. SOLUTION: A rear axle 11 is connected to a car body frame 1a of a forklift free to oscillate around a center pin 11a as its center, and rear wheels 8 as steering wheels are connected to its both ends. A damper 12 is connected between the rear axle 11 and the car body frame 1a, and the damper 12 is connected to a reservoir 16 through a solenoid valve 13. The solenoid valve 13 locks the damper 12 and fixes the rear axle 11 when a fixed motion signal is output from a controller. Additionally, when the fixed motion signal is not output, it unlocks the damper 12 and makes the rear axle 11 in a state free to oscillate. In this case, the controller computes a yaw rate changing ratio in accordance with a detection signal from a gyroscope to detect a yaw rate working on the relative vehicle and outputs the fixed motion signal at the time when the change rate becomes larger than a standard value.

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, and more particularly to a control device for fixing a swingably supported axle.

[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 a lateral acceleration (centrifugal force) is generated when the forklift turns, the forklift swings according to the centrifugal force. For this reason, the running stability at the time of turning was reduced, and the running speed could not be increased.

In view of this, Japanese Patent Laid-Open No. 58-211903 is provided with a turning detection means for detecting the centrifugal force generated when the forklift turns, and when the detected centrifugal force value exceeds a predetermined value, the swing is detected. A technique has been proposed in which an movably supported axle is fixed by an axle fixing mechanism.

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

[0005]

However, when the forklift makes a left turn immediately after making a right turn, for example, there is a section where the centrifugal force becomes equal to or less than a predetermined value when shifting from the right turn to the left turn. At this time, although the forklift is turning, the fixation of the axle is released, and the turning operation of the forklift becomes unstable.

Similarly, in Japanese Patent Laid-Open No. Sho 58-214406, when the turning angle and the vehicle speed exceed a predetermined value based on the turning angle of the steered wheels and the vehicle speed of the forklift,
A technique for fixing the axle of a forklift has been proposed. Also in this case, similarly, for example, when the right turn and the left turn are continuously performed, a section in which the turning angle is equal to or less than a predetermined value occurs, and the axle is released from being fixed during the turn of the forklift, and the forklift is turned off. There is a problem that the turning operation becomes unstable.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a control device for an industrial vehicle, which is capable of quickly and stably turning the industrial vehicle. It is in.

[0008]

In order to solve the above problems, the invention according to claim 1 is an industrial vehicle in which an axle is swingably supported in a vertical direction with respect to a vehicle body frame. And an axle fixing mechanism which is provided between the vehicle body frame and the vehicle body frame and which is swingably supported with respect to the vehicle body frame. The axle fixing mechanism is provided in the industrial vehicle and detects a yaw rate acting on the vehicle. Based on the yaw rate change means calculated by the change rate calculation means, and a change rate calculation means for calculating the change rate of the yaw rate detected by the yaw rate detection means. When the change rate becomes larger than the reference rate, the axle fixing mechanism is operated to output a fixing operation signal for fixing the axle and the body frame. As its gist in that a first control means for.

The gist of the invention of claim 2 is that in the invention of claim 1, the yaw rate detecting means is a gyroscope for directly detecting the yaw rate.

According to a third aspect of the present invention, in the first or second aspect of the invention, a lateral force detecting means is provided on the industrial vehicle for detecting a lateral force acting on the vehicle, and the lateral force. Based on the detection signal from the detection means, when the value of the lateral force becomes larger than the reference force value, the fixed operation signal for operating the axle fixing mechanism to fix the axle and the body frame. It is the gist to have the 2nd control means which outputs.

According to a fourth aspect of the present invention, in the first to third aspects of the present invention, the axle fixing mechanism is a hydraulic damper connected to the vehicle body frame and the axle, and is supplied to and discharged from the hydraulic damper. The pipeline for flowing the operating oil is controlled to be switched between a shielded state and a communicating state based on the fixed operation signal, and the pipeline is shielded to fix the axle to the vehicle body frame so that the communicating state is established. The gist of the present invention is to provide a switching valve that swingably supports the axle with respect to the vehicle body frame.

According to a fifth aspect of the present invention, in the first to fourth aspects of the present invention, the axle connects a steering wheel that is a rear wheel of an industrial vehicle. Therefore, according to the invention of claim 1,
In this industrial vehicle, the axle is swingable with respect to the body frame. The axle is fixed by operation of the axle fixing mechanism, and is brought into a swinging state by releasing the operation. In this case, the yaw rate detecting means detects the yaw rate acting on the vehicle. The change rate detecting means calculates a change rate of the yaw rate detected by the yaw rate detecting means. The first control means operates the axle fixing mechanism when the value of 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. Then, a fixing operation signal for fixing the axle and the body frame is output. That is, the axle fixing mechanism fixes the axle so as not to swing with respect to the body frame based on the fixing operation signal.

According to the second aspect of the invention, the yaw rate is directly detected by the gyroscope. According to the third aspect of the invention, the lateral force detecting means detects the lateral force acting on the vehicle. The second control means operates the axle fixing mechanism to operate the axle and the vehicle body frame when the value of the lateral force becomes larger than the reference force value based on the detection signal from the lateral force detecting means. A fixed operation signal for fixing and is output. Therefore, the axle fixing mechanism operates the axle fixing mechanism by operating the axle fixing mechanism when the lateral force value is larger than the reference force value or when the change rate of the yaw rate is larger than the reference rate value. Fix it.

According to the fourth aspect of the invention, when the fixed operation signal is output from the first or second control means, the switching valve brings the pipe line into the closed state. Therefore, it becomes impossible to supply and discharge the hydraulic oil to and from the hydraulic damper, and the axle is fixed.
Further, when the fixed operation signal is not output from the first and second control means, the switching valve puts the pipe line in the communicating state. Therefore, the hydraulic oil can be supplied to and discharged from the hydraulic damper, and the axle can swing.

According to the fifth aspect of the 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.

[0016]

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 at 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 vehicle 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.

A piston rod 6b of a lift cylinder 6 having a body 6a connected to the vehicle body frame 1a is connected to the inner mast 3. That is, the lift cylinder 6
Inner mast 3 based on expansion and contraction of piston rod 6b of
Is moved up and down, and as the inner mast 3 is moved up and down, the fork 4 is moved up and down.

A pair of left and right front wheels 7 are provided at the front of the vehicle body frame 1a of the forklift 1. Each front wheel 7
Is connected to an engine E via a differential ring gear G and a transmission D (see FIG. 4), and each front wheel 7 is driven by the engine E. That is, the front wheels 7 are driving wheels. Further, a pair of left and right rear wheels 8 is provided at the rear of the main body 1a of the forklift 1.
Is provided.

FIG. 2 shows a connecting structure for connecting the rear wheels 8. A rear axle 11 that constitutes an axle 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 able to swing (rotate) about a center pin 11a. The rear wheel 8 is connected to the left and right ends of the rear axle 11. The rear wheels 8 are steered wheels that are steered based on the operation of the steering wheel 10 in the cab 9. In this case, the left and right rear wheels 8 rotate about the center pin 11a. 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 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 electromagnetic switching valve 13. The electromagnetic switching valve 13 includes a body and a spool, and a flow valve portion 14 and a stop valve portion 15 are formed on the spool. Further, a third hydraulic pipe P3 and a fourth hydraulic pipe P4 are connected to the electromagnetic switching valve 13. The third hydraulic pipe P3 is connected to the fourth hydraulic pipe P4. A reservoir 16 for storing hydraulic oil is provided in the fourth hydraulic pipe P4.
Is connected.

The electromagnetic switching valve 13 adjusts the hydraulic oil flowing in each of the hydraulic pipes P1 to P4 by moving the spool with respect to the body and selecting the flow valve portion 14 or the stop valve portion 15. ing.

When the flow valve section 14 is selected, the first hydraulic pipe P1 and the third hydraulic pipe P3 are communicated with each other and the second hydraulic pipe P1 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 15 is selected, the hydraulic oil flowing through the hydraulic pipes P1 to P4 is shielded. Therefore, the hydraulic oil is in a state in which it cannot flow into and out of the first chamber R1 and the second chamber R2. That is, the damper 12 is in a locked state in which the piston 12b cannot operate. That is, the rear axle 11 cannot be swung, and is fixed by the damper 12.

The second hydraulic pipe P2 and the fourth hydraulic pipe P
Throttle valves 17, 18 between the reservoir 16 of 4 and the connection.
Is provided. The damper 12 and the electromagnetic switching valve 13 and the like constitute an axle fixing mechanism.

As shown in FIG. 1, the forklift 1
A gyroscope 20 as a yaw rate detecting means is provided 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 2 is provided at the center position between the front wheels 7 of the forklift 1.
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 FIG. 2, the rear wheel 8 is provided with a steering angle sensor 22 for detecting the steering angle θ of the rear wheel 8. As shown in FIG. 4, the forklift 1 is provided with a vehicle speed sensor 23 that detects the traveling speed v of the forklift 1 by detecting the rotation of the differential ring gear G. In the present embodiment, the vehicle speed sensor 23 and the gyroscope 20 constitute 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 first control means and second 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 controller 31 is connected to the gyroscope 20, the acceleration sensor 21, the steering angle sensor 22 and the vehicle speed sensor 23. Also, the controller 31
An electromagnetic switching valve 13 is connected to.

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.
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 and outputs a traveling speed signal indicating the traveling speed v to the controller 31.

The controller 31 is the gyroscope 2
The rate of change of the angular velocity based on the angular velocity signal from 0, that is, the rate of change of the yaw rate ω (yaw rate change rate) Δ
It is designed to calculate ω / ΔT. The yaw rate change rate Δω / ΔT means angular acceleration. The controller 31 obtains the yaw rate change rate Δω / ΔT by differentiating the angular velocity, that is, the yaw rate ω.

The controller 31 is adapted to calculate 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.

As shown in FIG. 7, the controller 31 is
The yaw rate change rate Δω / ΔT calculated based on the angular velocity signal is compared with the upper reference change rate value K1, and the yaw rate change rate Δω / ΔT is determined to be the upper reference change rate value K1 or less from the upper reference change rate value K1. When the value becomes larger, 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 the present 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 becomes the lower reference rate value K2 or less.

As shown in FIG. 8, the controller 31 is
When the absolute value of the calculated centrifugal force Fb becomes a value larger than the upper reference centrifugal force value H1 from a value less than or equal to the upper reference centrifugal force H1, the output of the fixed operation signal is started.

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 the fixed operation signal when at least one of the conditions 1) to 5) is satisfied.

1) When the yaw rate change ratio Δω / ΔT is larger than the upper reference ratio 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 a value 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.

When the fixed operation signal is output, the electromagnetic switching valve 13 selects the stop valve portion 15, and the first and second hydraulic pipes P1,
Shield P2 and lock the damper 12. Therefore, the rear axle 11 cannot swing and the damper 1
2 fixes the rear axle 11.

The electromagnetic switching valve 13 selects the flow valve portion 14 when the fixed operation signal is not output, and the damper 12 is selected.
The first chamber R1 and the second chamber R2 are set in a state in which hydraulic oil can flow in and out. Therefore, the rear axle 11 is in a swingable state.

Next, the operation and effect of the control device for the industrial vehicle will be described. FIG. 6 is a flowchart for performing control for fixing the rear axle 11. However, for convenience of description, it is assumed that the fixed operation signal is not output at the start of the control according to this flowchart and the rear axle 11 is held in a swingable state.
The description of “step” in the specification is abbreviated as “S” in FIG.

First, the controller 31 executes step 10
At 1, the traveling speed v of the forklift 1 is read based on the traveling speed signal from the vehicle speed sensor 23. In step 102, the controller 31 reads the yaw rate ω based on the angular velocity signal from the gyroscope 20.

In step 103, the controller 31 calculates the centrifugal force Fb based on the traveling speed v and the yaw rate ω.
Ask for. The calculated centrifugal force Fb is obtained by the product of the traveling speed v and the yaw rate ω according to the above equation (1).

At step 104, the controller 31 determines the yaw rate ω based on the read yaw rate ω.
Of the yaw rate, that is, the yaw rate change rate Δω / ΔT is calculated. In step 105, the controller 31 applies a low-pass filter to the calculated yaw rate change ratio Δω / ΔT to remove noise.

At step 106, the controller 31 determines whether the absolute value of the calculated centrifugal force Fb is larger than the upper reference calculated centrifugal force value H1. When the absolute value of the calculated centrifugal force Fb is larger than the upper reference centrifugal force value H1, the process proceeds to step 107, and in step 107, the controller 31 outputs a fixed operation signal to the electromagnetic switching valve 13. Then, the electromagnetic switching valve 13 selects the stop valve portion 15, locks the damper 12, and fixes the rear axle 11.
For this reason, the rear axle 11 is held in a state where it cannot swing. Then, the controller 31 performs the processing from step 101 again.

Further, in step 106, the calculated centrifugal force Fb
If the absolute value of is less than or equal to the upper reference centrifugal force value H1, the process proceeds to step 108, and the controller 31 determines in step 108 that the absolute value of the calculated centrifugal force Fb is less than the lower reference centrifugal force value H2. Determine whether or not. When the absolute value of the calculated centrifugal force Fb is less than the lower reference centrifugal force value H2, the controller 31 moves to step 109 and does not output the fixed operation signal. That is, the controller 31 continues the state in which the fixed operation signal is not output. Then, the controller 31 shifts the processing to step 110.

Further, in step 108, the calculated centrifugal force Fb
Is equal to or higher than the lower reference centrifugal force value H2, the process proceeds to step 110 while maintaining that state. That is, since the controller 31 does not output the fixed operation signal in step 108, the process proceeds to step 110 without outputting the fixed operation signal.

At step 110, the controller 31
Is the yaw rate change rate Δω / ΔT is the upper reference rate value K1.
Is greater than or equal to. The controller 31
When the change ratio Δω / ΔT is larger than the upper reference ratio value K1, the routine proceeds to step 111, where a fixed operation signal is output to the electromagnetic switching valve 13. Then, the damper 12 is locked and the rear axle 11 is fixed. Then, the controller 31 performs the processing from step 101 again.
In step 110, when the yaw rate change rate Δω / ΔT is less than or equal to the upper reference rate value K1, the controller 31 proceeds to step 112.

At step 112, the controller 31
Is the yaw rate change rate Δω / ΔT is the lower reference rate value K2.
It is determined whether it is less than. Yaw rate change rate Δω
If / ΔT is less than the lower reference ratio value K2, the controller 31 determines in step 113 that the yaw rate change ratio Δω / ΔT is less than the lower reference ratio value K2 based on the timing of the timer 31b. It is determined whether the time T has passed. If the predetermined time T has not elapsed, the controller 31 performs the processing from step 101 again. If the predetermined time T has elapsed, the controller 31 proceeds to step 114, and again holds step 101 in which the fixed operation signal is not output.
Perform the processing from. Each process of steps 112 to 114 is a process which exerts its effect when the controller 31 outputs the fixed operation signal at the time of performing the process of step 112 as described later, and outputs the fixed operation signal. Not at the moment not having that effect.

Thus, in steps 112 to 114,
When the process proceeds to step 101 again without outputting the fixed operation signal, the controller 31 performs the same processing as the processing when the fixed operation signal is not output.

On the other hand, step 107 or step 111
In the case where the processing from step 101 is performed again from the state in which the fixed operation signal is output,
Up to 105, the same processing as in the case where the fixed operation signal is not output is performed.

When the yaw rate change ratio Δω / ΔT is larger than the upper reference ratio value K1 in step 106, the controller 31 continues to output the fixed operation signal in step 107 to fix the rear axle 11. to continue. Then, the controller 31 again moves the process to step 101.

In step 106, when the calculated centrifugal force Fb is less than or equal to the upper reference centrifugal force value H1, the process proceeds to step 108, and it is determined whether the calculated centrifugal force Fb is less than the lower reference centrifugal force value H2. Calculated centrifugal force Fb is lower standard centrifugal force value H
When it is less than 2, the process proceeds to step 109, and the controller 31 stops the output of the fixed operation signal. Then, step 11 in the case where the above-mentioned fixed operation is not output.
Perform processing of 0 or less.

At step 108, the controller 31
When the calculated centrifugal force Fb is greater than or equal to the lower reference centrifugal force value H2, the state in which the fixed operation signal is output is maintained,
Move to step 110.

In step 110, when the yaw rate change rate Δω / ΔT is larger than the upper reference rate value K1, the process proceeds to step 111, and the output of the fixed operation signal is continued.
Therefore, the fixing of the rear axle 11 is continued. Then, the controller 31 performs the processing from step 101 again.

If the yaw rate change ratio Δω / ΔT is less than or equal to the upper reference ratio value K1 in step 110, the process proceeds to step 112, and when the yaw rate change ratio Δω / ΔT is less than the lower reference ratio value K2, Controller 31
Moves the processing to step 113. Step 113
Then, the controller 31 determines that the yaw rate change rate Δω / ΔT is the lower reference rate value K2 based on the timing of the timer 31b.
It is determined whether or not the predetermined time T has elapsed from the time point when the time is less than the time, and if the predetermined time T has not elapsed, the controller 31 performs the processing from step 101 again while outputting the fixed operation signal. .

When it is determined in step 113 that the predetermined time T has been timed, the controller 31 stops outputting the fixed operation signal in step 114 and sets the rear axle 11 in a swingable state. To do. Then, the controller 31 performs the processing from step 101 again.

Next, the case where the forklift 1 turns straight from the right based on the control of the above flow chart will be described with reference to FIG. In the present embodiment, the steering angle θ is a positive direction when turning right and a negative direction when turning left. Similarly, with respect to the yaw rate ω, the actual centrifugal force Fa, and the calculated centrifugal force Fb, the direction acting when turning right is the positive direction, and the direction acting when turning left is the negative direction.

The driver of the forklift 1 operates the steering wheel 10
When the forklift 1 starts turning right and the steering angle θ increases, the yaw rate ω, the calculated centrifugal force Fb, the actual centrifugal force Fa, and the yaw rate change ratio Δω / ΔT increase as the steering angle θ increases. To do. In this case, the yaw rate change ratio Δω / ΔT rises first, and the upper reference ratio value K
It is a value greater than 1. When the yaw rate change rate Δω / ΔT becomes larger than the upper reference rate value K1, the controller 31 outputs a fixed operation signal to fix the rear axle 11. That is, the rear axle 11 is fixed according to the yaw rate change rate Δω / ΔT. At this point, the calculated centrifugal force Fb is not yet larger than the upper reference centrifugal force value H1. Therefore, when turning is started, the rear axle 11 is fixed faster than when the rear axle 11 is fixed at the calculated centrifugal force value Ha.

When the steering angle θ further increases, the yaw rate ω, the calculated centrifugal force Fb, and the actual centrifugal force Fa increase. Eventually, the calculated centrifugal force Fb becomes a value larger than the upper reference centrifugal force value H1. At this point, the yaw rate change rate Δω / ΔT
Is a value larger than the upper reference ratio value K1, and the rear axle 11 is held in a fixed state. Then, the driver stops operating the steering wheel 10 and keeps turning while maintaining the steering angle θ at the predetermined angle. At this time, the yaw rate ω, the calculated centrifugal force Fb, and the actual centrifugal force Fa are maintained at predetermined constant values.

Until the steering angle θ is maintained at a predetermined angle, the yaw rate change rate Δω / ΔT changes from increasing to decreasing and eventually becomes smaller than the lower reference rate value K2. At this point, the calculated centrifugal force Fb is greater than the upper reference centrifugal force value H1, so the controller 3
1 outputs a fixed operation signal based on the fact that the calculated centrifugal force Fb is larger than the upper reference centrifugal force value H1. Therefore, the fixation of the rear axle 11 is maintained.

This action is the same when the forklift 1 makes a left turn from going straight. That is, when the forklift 1 that is traveling straight ahead starts turning right or left,
First, the rear axle 11 is fixed on the basis that the yaw rate change rate Δω / ΔT becomes larger than the upper reference change rate value K1, and then the yaw rate change rate becomes smaller than the lower reference change rate value K2. After that, the fixed state of the rear axle 11 is maintained based on the fact that the calculated centrifugal force Fb becomes larger than the upper reference centrifugal force value H1.

Next, the case where the right turn and the left turn are continuously performed will be described with reference to FIG. When the steering wheel 10 is operated from the state where the vehicle is making a right turn and the steering angle θ is decreased from the state where the steering angle θ is constant, the yaw rate ω and the calculated centrifugal force Fb start to decrease from a predetermined constant value. To do. When the calculated centrifugal force Fb has a predetermined constant value, the upper reference centrifugal force value H1 is exceeded, so the controller 31 outputs a fixed operation signal to fix the rear axle 11.

Further, the yaw rate change ratio Δω / ΔT starts increasing as the steering angle θ decreases. Eventually, the value becomes larger than the upper reference ratio value K1. At this time, the calculated centrifugal force Fb is larger than the lower reference centrifugal force value H2.

Further, as the steering angle θ decreases, the calculated centrifugal force Fb becomes a value smaller than the lower reference ratio value K2. However, since the yaw rate change rate Δω / ΔT is larger than the upper reference rate value K1, the controller 31
Keeps outputting the fixed operation signal and continues to fix the rear axle 11. Then, the yaw rate change rate Δω / ΔT becomes maximum in the vicinity of the steering angle θ of approximately “0”.

When the steering angle θ becomes “0” and the steering angle θ further decreases, that is, the forklift 1 starts turning to the left. When the steering angle θ decreases, the calculated centrifugal force Fb and the yaw rate ω continue to decrease, eventually become a negative value, and further decrease. From this negative value, the absolute value of the calculated centrifugal force Fb and the absolute value of the yaw rate ω start to increase.

Eventually, the absolute value of the calculated centrifugal force Fb exceeds the upper reference centrifugal force value H1. At this time, the yaw rate change rate Δω / ΔT is a value equal to or higher than the lower reference rate value K2.
Therefore, the controller 31 keeps the state of outputting the fixed operation signal and keeps the state of fixing the rear axle 11.

Further, when the steering angle θ decreases, the yaw rate change ratio Δω / ΔT becomes a value smaller than the lower reference ratio value K2. However, the controller 31 determines that the yaw rate change ratio Δω / ΔT has become smaller than the lower reference ratio value K1 and that the predetermined time T has not elapsed, and that the absolute value of the calculated centrifugal force Fb is larger than the upper reference centrifugal force H1. Therefore, the fixed operation signal is continuously output, and the rear axle 11
Keep fixing.

The driver stops the operation of the steering wheel 10 and
When the steering angle θ is maintained at a predetermined constant angle, the yaw rate ω and the calculated centrifugal force Fb are eventually maintained at predetermined constant values. Further, the yaw rate change ratio Δω / ΔT eventually becomes “0”.

After the elapse of the predetermined time T, the controller 31 cancels the condition for outputting the fixed operation signal based on the yaw rate change rate Δω / ΔT, but outputs the fixed operation signal based on the calculated centrifugal force value Fb. It is assumed that the condition for is satisfied and the fixed operation signal is continuously output, and the rear axle 11 is continuously fixed.

That is, when a right turn to a left turn is continuously performed, a section Y1 in which the condition for outputting the fixed operation signal by the calculated centrifugal force Fb is released near the steering angle θ becomes "0".
However, the condition for outputting the fixed operation signal based on the yaw rate change ratio Δω / ΔT is satisfied. Therefore, when shifting from the right turn to the left turn, the rear axle 11 is always fixed. Further, after the steering angle θ is held at a predetermined constant angle for turning left, even if the section Y2 that satisfies the condition of outputting the fixed operation signal by the yaw rate change ratio Δω / ΔT ends, the fixed by the calculated centrifugal force Fb. Since the condition for outputting the operation signal is satisfied, the rear axle 11 remains fixed. Therefore, when performing a right turn to a left turn continuously, the turn is always performed with the rear axle 11 fixed.

This action is the same when making a left turn to a right turn, and the turning operation is always performed with the rear axle 11 fixed. The roll angle shown in FIG. 10 is an angle showing the rolling state of the forklift 1,
It is detected by a rolling sensor (not shown) provided on the vehicle body frame 1a.

According to this embodiment, the following (a) to
It has the effect shown in (). (B) The controller 31 changes the yaw rate change rate Δω / Δ
A fixed operation signal is output based on T, and the rear axle 11
Since the vehicle is fixed, the rear axle 11 can be quickly fixed, for example, at the start of turning when the forklift 1 starts turning straight or leftward. Therefore, the turning of the forklift 1 can be started in a stable state.

(B) The controller 31 outputs a fixed operation signal based on the yaw rate change rate Δω / ΔT, and also outputs a fixed operation signal based on the calculated centrifugal force Fb. Therefore, the yaw rate change rate Δω /
Even after the fixed operation signal is output based on ΔT and the fixed operation signal is not output based on the yaw rate change ratio Δω / ΔT, the controller 31 still operates the calculation centrifugal force Fb.
Since the fixed operation signal is output based on the above, the forklift 1 can be turned in a stable state from the start of turning.

(C) Further, the controller 31 outputs the fixed operation signal based on the calculated centrifugal force Fb in addition to outputting the fixed operation signal based on the yaw rate change ratio Δω / ΔT. Therefore, for example, when the forklift 1 continuously makes a right turn to a left turn, the fixed operation signal based on the calculated centrifugal force Fb generated near the steering angle θ becomes “0” (the section shown in FIG. 10). Even when Y1) is reached, the fixed operation signal is output based on the yaw rate change rate Δω / ΔT. Therefore, when the forklift 1 makes a right turn to a left turn continuously, the rear axle 1 is always
1 is performed in a fixed state, and the turning operation can be performed in a stable state.

(D) When the yaw rate change rate Δω / ΔT becomes larger than the upper reference rate value K1, the controller 31 outputs a fixed operation signal to fix the rear axle 11, and the lower reference rate value K2. When it becomes a small value, the processing for canceling the output of the fixed operation signal is started. Therefore, for example, the rear axle 11 can be fixed in a more stable state than when the rear axle 11 is fixed using only one upper reference ratio value K1. That is, for example, if only one upper reference ratio value K1 is used and the yaw rate change ratio Δω / ΔT is larger than the upper reference ratio value K1, a fixed operation signal is output and if it is smaller than the lower reference ratio value K2. If
When the control for stopping the output of the fixed operation signal is performed, when the yaw rate change ratio Δω / ΔT makes a turn so as to change in the vicinity of the upper reference ratio value K1, the output and the stop of the fixed operation signal are frequently repeated. For this reason, the rear axle 1
The fixation of 1 and the release of the fixation are frequently repeated. However, by outputting the fixed operation signal based on the upper reference ratio value K1 and the lower reference ratio value K2,
Even if the yaw rate change rate Δω / ΔT is the upper reference rate value K
Even if the vehicle is turning such that the yaw rate change ratio Δω / ΔT becomes larger than the upper reference ratio value K1, the yaw rate change ratio Δω / ΔT is smaller than the lower reference ratio value K2. The fixed operation signal is continuously output until the value is reached. Therefore, the rear axle 11 can be fixed in a more stable state.

(E) The controller 31 calculates the calculation centrifugal force F
When b is greater than the upper reference centrifugal force value H1, a fixed operation signal is output to fix the rear axle 11, and when it is less than the lower reference centrifugal force value H2, the fixed operation signal is output. Start the process to cancel. Therefore, as in the case of the yaw rate change ratio Δω / ΔT shown in the above effect (C), for example, a more stable state than when the rear axle 11 is fixed by using only one upper reference centrifugal force value H1. The rear axle 11 can be fixed with.

(V) The controller 31 outputs the fixed operation signal, for example, when the yaw rate change ratio Δω / ΔT becomes a value larger than the upper reference ratio value K1, and becomes a value smaller than the lower reference ratio value K2, 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. Therefore, the turning operation of the forklift 1 can be performed in a more stable state.

For example, when the yaw rate change rate Δω / ΔT becomes a value smaller than the lower reference rate value K2, even if the condition for outputting the fixed operation signal by the calculated centrifugal force Fb is not satisfied, the predetermined time period T In some cases, the condition for outputting the fixed operation signal by the calculated centrifugal force Fb may be satisfied. In this case, the turning operation can be continued with the rear axle 11 fixed, and the turning operation of the forklift 1 can be performed in a more stable state.

Further, for example, when the forklift 1 travels while performing high-frequency turning to turn the turning direction of the forklift 1 left and right in a short time (1 second or less), the calculated centrifugal force value Fb is usually the upper reference centrifugal force value. The fixed operation signal is output based on the yaw rate change rate Δω / ΔT without exceeding H1. Therefore, even when the yaw rate change ratio Δω / ΔT becomes a value smaller than the lower reference ratio value K2 during the high-frequency switching traveling, the controller 31
Does not immediately stop outputting the fixed operation signal but continues to output the fixed operation signal for a predetermined time T. For this reason, the forklift 1 is operated while performing high-frequency turning back in a stable state.
Can be driven.

(G) The axle fixing mechanism comprises a damper 12 and an electromagnetic switching valve 13. Therefore, the controller 31 outputs a fixed operation signal to the solenoid operated directional control valve 13, and the solenoid operated directional control valve 1
The rear axle 11 can be easily fixed by locking the damper 12 by shielding the hydraulic pipes P1 to P4 communicating with the damper 12.

(H) In the present forklift 1, the rear axle 11 that connects the rear wheels 8 that 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.

(I) The controller 31 calculates the calculation centrifugal force F
b was compared with the upper reference centrifugal force value K1 and the lower reference centrifugal force value K2 to control the output of the fixed operation signal. In this case, FIG.
As shown in, the calculated centrifugal force Fb rises earlier than the actual centrifugal force Fa. That is, the calculated centrifugal force Fb responds to the turning of the forklift 1 faster than the actual centrifugal force Fa. Therefore, by controlling the output of the fixed operation signal based on the calculated centrifugal force Fb, the controller 31 can more quickly control the fixed operation signal with respect to the turning of the forklift 1.

(N) The yaw rate ω acting on the forklift 1, that is, the angular velocity, can be directly and easily detected by the gyroscope 20, and the controller 31 can easily determine the yaw rate ω based on the signal from the gyroscope 20. Can be determined.

The present invention is not limited to the above-mentioned embodiments, but can be carried out as follows without departing from the spirit of the invention. (1) In the above embodiment, the yaw rate ω is detected by the gyroscope 20, and the controller 31 calculates the yaw rate change rate Δω / ΔT based on the yaw rate ω. The controller 31 determines the yaw rate change ratio Δω / Δ based on the steering angle θ detected by the steering angle sensor 22 and the traveling speed v detected by the vehicle speed sensor 23.
You may estimate T.

That is, the controller 31 obtains the reciprocal of the turning radius r from the steering angle θ. Then, the controller 31 obtains the reciprocal change rate Δ (1 / r) / ΔT of the turning radius r. Further, the controller 31 estimates the yaw rate change rate Δω / ΔT by multiplying the change rate Δ (1 / r) / ΔT of the reciprocal of the turning radius r by the traveling speed v. That is, the estimated yaw rate change rate Δωx / ΔT is given by the following equation (2).

Δωx / ΔT = v · Δ (1 / r) / ΔT (2) This estimated yaw rate change rate Δω / ΔTx is an approximate value of the yaw rate change rate Δω / ΔT. That is, the yaw rate ω is expressed by the following equation (3) based on the steering angle θ (turning radius r) and the traveling speed v.

Ω = v / r = v (1 / r) (3) Then, the controller 31 changes the ratio (1 / r) of the yaw rate ω by Δ (1 / r) / ΔT and the traveling speed v.
Estimated yaw rate change rate Δωx
Calculate / ΔT. That is, the yaw rate change rate Δω / Δ
Estimate T.

In this case, the steering angle sensor 22 and the vehicle speed sensor 23 constitute a yaw rate detecting means. (2) In the above embodiment, the gyroscope 20 is a piezoelectric gyroscope. For this, a gas rate gyroscope and an optical gyroscope may be used.

(3) 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 Fa
May be compared with the upper reference centrifugal force value H1 and the lower reference centrifugal force value H2 to output a fixed operation signal. In this case, since it is not necessary to calculate the centrifugal force acting on the forklift 1 based on the traveling speed v and the yaw rate ω, it is possible to easily output the fixed operation signal based on the actual centrifugal force Fa.

(4) In step 112 of the above embodiment, when the yaw rate change ratio Δω / ΔT becomes smaller than the lower reference ratio value K2, the output of the fixed operation signal may be immediately stopped.

(5) In the above embodiment, the controller 31 sets the yaw rate change rate Δω / ΔT to the upper reference rate value K.
The output of the fixed operation signal was controlled by comparing with two reference ratio values of 1 and the lower reference ratio value K2. For this, the controller 31 may control the output of the fixed operation signal based on one reference ratio value. In this case, for example, the controller 31
Outputs a fixed operation signal when the value is larger than the reference ratio value, and stops outputting the fixed operation signal when the value is less than the reference ratio value.

Similarly, the controller 31 may control the output of the fixed operation signal based on one reference centrifugal force value. In this case, for example, the controller 31 outputs the fixed operation signal when the calculated centrifugal force Fb is larger than the reference centrifugal force value, and stops the output of the fixed operation signal when the calculated centrifugal force Fb is equal to or smaller than the reference centrifugal force value. To do.

(6) The above embodiment may be applied to the forklift 1 that does not use the acceleration sensor 21 and does not detect the actual centrifugal force Fa. In this case, since the acceleration sensor 21 is not used, the structure thereof can be simplified and the control of the controller 31 can be simplified.

(7) In the above embodiment, since the fixed operation signal is output only under the condition based on the calculated centrifugal force Fb, the calculated centrifugal force Fb becomes a value smaller than the lower reference centrifugal force value H2. Alternatively, it may be controlled to output the fixed operation signal only for a predetermined time.

The technical ideas other than the claims that can be understood from the above-described embodiments will be described below along with their effects. (1) In the invention according to claim 1, the reference ratio value is composed of an upper reference ratio value K1 and a lower reference ratio value K2, and the controller 31 has a yaw rate change ratio Δω / ΔT larger than the upper reference ratio value K1. When the yaw rate change ratio Δω / ΔT becomes a value smaller than the lower reference ratio value, the control device for the industrial vehicle performs the stop control for stopping the output of the fixed operation signal. According to this control device, the forklift can be turned in a more stable state.

(2) In the invention according to claim 3, the reference force value is composed of the upper reference centrifugal force value H1 and the lower reference centrifugal force value H2, and the controller 31 calculates the calculated centrifugal force value Fb from the upper reference centrifugal force value H1. A control device for an industrial vehicle, which outputs a fixed operation signal when the value becomes large, and stops outputting the fixed operation signal when the calculated centrifugal force value Fb becomes smaller than the lower reference centrifugal force value H2. According to this control device, the forklift can be turned in a more stable state.

[0110]

As described in detail above, according to the first aspect of the present invention, the swing of the axle is controlled based on the change rate of the yaw rate, so that the axle can be quickly fixed at the start of turning.

According to the second aspect of the invention, the yaw rate can be directly and easily detected by the gyroscope. According to the third aspect of the present invention, since the swing of the axle is controlled based on the change rate of the yaw rate and the lateral force, the industrial vehicle can be turned in a stable state.

According to the invention described in claim 4, the axle can be easily fixed by the hydraulic damper and the electromagnetic switching valve.
According to the invention of claim 5, the swing of the axle on the steered wheel side of the industrial vehicle is controlled, so that the turning performance and the operability 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 connection structure for connecting rear wheels.

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 the forklift 1.

FIG. 5 is an electric block diagram for controlling swing of a rear axle of a forklift truck and fixing the rear axle.

FIG. 6 is a flowchart for controlling swing of a rear axle of a forklift truck and fixing the rear axle.

FIG. 7 is an explanatory diagram in the case of controlling the swing of the rear axle with a yaw rate change rate.

FIG. 8 is an explanatory diagram in the case where the swing of the rear axle is controlled by a calculated centrifugal force.

FIG. 9 is an explanatory diagram when the forklift starts rightward traveling from straight traveling.

FIG. 10 is an explanatory diagram of a case where the forklift continuously makes a right turn travel and a left turn travel.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Forklift as an industrial vehicle, 1a ... Body frame, 11 ... Rear axle which comprises an axle, 12 ... Hydraulic damper which comprises an axle fixing mechanism, 13 ... Electromagnetic switching valve as a switching valve which constitutes an axle fixing mechanism, 20 ... a gyroscope as a yaw rate detecting means and a gyroscope as a yaw rate detecting means, 21 ... an acceleration sensor as a lateral force detecting means, 23 ... a vehicle speed sensor constituting a lateral force detecting means, 31 ... first and The controller as the second control means and the change ratio calculation means, P1 as the conduit
P4 ... First to fourth hydraulic pipes.

Claims (5)

[Claims] 1. An industrial vehicle in which an axle is swingably supported in a vertical direction with respect to a body frame, and the industrial vehicle is disposed between the body frame and the axle and is swingably supported with respect to the body frame. Axle fixing mechanism for fixing the axle to the vehicle body frame, yaw rate detection means provided in the industrial vehicle for detecting a yaw rate acting on the vehicle, and a change rate of the yaw rate detected by the yaw rate detection means. Based on the change rate of the yaw rate calculated by the change rate calculating means, the change rate of the yaw rate becomes larger than a reference rate value, the axle fixing mechanism is operated. A control device for an industrial vehicle, comprising: a first control means that is operated to output a fixed operation signal for fixing an axle and a body frame. 2. The control device for an industrial vehicle according to claim 1, wherein the yaw rate detecting means is a gyroscope that directly detects the yaw rate. 3. A lateral force detecting means provided on the industrial vehicle for detecting a lateral force acting on the vehicle, and a value of the lateral force based on a detection signal from the lateral force detecting means. The second control means for operating the axle fixing mechanism to output a fixing operation signal for fixing the axle and the vehicle body frame when is larger than the reference force value. A control device for the industrial vehicle described. 4. The axle fixing mechanism includes a hydraulic damper connected to the vehicle body frame and the axle, and a pipeline for flowing hydraulic oil supplied to and discharged from the hydraulic damper.
Switching control between a shielded state and a communicating state is performed based on the fixed operation signal, and the pipeline is shielded to fix the axle to the vehicle body frame. The control device for an industrial vehicle according to any one of claims 1 to 3, further comprising a switching valve that swingably supports the valve. 5. The control device for an industrial vehicle according to claim 1, wherein the axle is connected to a steering wheel that is a rear wheel of the industrial vehicle.