JP3159057B2 - Industrial vehicle control device - Google Patents

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 for connecting steerable wheels is swingable with respect to a vehicle body frame in consideration of the traveling performance and riding comfort of the vehicle. Normal,
The steered wheels are rear wheels, and the front wheels are drive wheels driven by a traveling motor.

A forklift having an axle swingably provided with an axle fixing mechanism capable of fixing the axle in order to maintain the stability of the forklift.

[0004]

However, when the axle is fixed by the axle fixing mechanism, the four wheels of the front wheel and the rear wheel are not fixed.
One of the wheels may float. Because
This is because the plane is geometrically composed of three points. For example, when a heavy load is placed on a fork, the center of gravity moves forward, and one of the rear wheels floats. In addition, when a relatively light load is placed, one of the front wheels floats because the center of gravity is located rearward.

[0005] Therefore, when a relatively light load is placed, fixing the axle causes the front wheels, which are the drive wheels, to float, and the ground force on the front wheels decreases, so that the drive force from the front wheels can be obtained. There is no problem. For this reason, there is a problem that the forklift does not travel smoothly.

When a heavy load is placed, the center of gravity moves forward, and the driving force of the front wheels increases.
Therefore, from the viewpoint of driving force, there is no problem even if the axle is fixed. However, since the center of gravity moves forward, the vehicle itself tends to lean forward. In particular, when a load is placed above, the center of gravity moves further upward, so that the vehicle becomes more unstable. Therefore, there is a problem that it is difficult to carry out the cargo handling work and traveling of the forklift smoothly.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a control apparatus for an industrial vehicle capable of performing a cargo handling operation in an industrial vehicle in a stable state.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an invention according to claim 1 is directed to an industrial vehicle having an axle supported to be vertically swingable with respect to a body frame. And an axle fixing mechanism for fixing an axle swingably supported on the vehicle body frame to the vehicle body frame, and provided to be movable up and down with respect to the vehicle body frame to hold a load. Lifting equipment for raising and lowering the cargo handling equipment, a lifting position detecting means for detecting a lifting position of the cargo handling equipment, and a load for detecting a load acting on the lifting driving means Detecting means and operating the axle fixing mechanism when the lifting position of the cargo equipment detected by the lifting position detecting means is a predetermined position and the load detected by the load detecting means is a predetermined amount or more. By a first fixed control means for outputting a locking operation signal for fixing the axle and the vehicle body frame, provided in the industrial vehicle, yaw rate acting on the vehicle
Yaw rate detecting means for detecting the yaw rate,
Yaw rate based on the yaw rate detected by the
Change rate calculating means for calculating a change rate of the
Calculates the centrifugal force acting on the vehicle based on the rate of change
And the yaw rate change ratio is larger than the reference ratio value.
When the value becomes the value, the axle and the axle
Outputs a fixed operation signal for fixing the body frame
At the same time, the calculated centrifugal force becomes a value larger than the reference force.
Second fixed control means for outputting the fixed operation signal when
Further comprising bets as its gist.

According to a second aspect of the present invention, in the first aspect, the lifting position detecting means is a limit switch. The invention according to claim 3 is
The gist of the present invention is that the lifting drive means is a lift cylinder, and the load detection means is a hydraulic pressure sensor for detecting a hydraulic pressure of the lift cylinder.

[0010]

[0011]

[0012]

According to a fourth aspect of the present invention, in the first to third aspects of the invention, the axle fixing mechanism includes a hydraulic damper connected to the vehicle body frame and the axle, and a supply / discharge of the hydraulic damper. The pipeline through which the hydraulic oil flows is controlled to be switched between a shielded state and a communication state based on the fixed operation signal, and the axle is fixed to the body frame by setting the pipeline to the shielded state. Accordingly, the gist of the present invention is to provide a switching valve for supporting the axle so as to swing with respect to the body frame.

According to a fifth aspect of the present invention, in the first to fourth aspects of the present invention, the gist of the invention is that the axle connects a steering wheel which is a rear wheel of an industrial vehicle. Therefore, claim 1
According to the described invention, in the present industrial vehicle, the axle can swing with respect to the body frame. The axle is fixed by the operation of the axle fixing mechanism, and can be swung by releasing the operation. In this case, the lifting position detecting means detects the lifting position of the cargo handling equipment,
The load detecting means detects a load acting on the lifting drive means. The first control means is configured to fix the axle when the lift position of the cargo handling equipment detected by the lift position detection means is a predetermined position and the load detected by the load detection means is equal to or more than a predetermined amount. A fixing operation signal for fixing the axle and the body frame by operating the mechanism 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. 2nd solid
The constant control means includes a yaw rate detecting means and a change rate calculating means.
The yaw rate change rate calculated by the step is
The axle fixing mechanism is activated when
Outputs a fixed operation signal for fixing the shaft and the body frame.
And perform based on the yaw rate change rate.
When the calculated centrifugal force is greater than the reference force,
Outputs fixed operation signal.

According to the present invention, the lifting position of the cargo handling equipment is detected by the limit switch. According to the third aspect of the present invention, the cargo handling equipment moves up and down based on driving of the lift cylinder, and the hydraulic pressure sensor detects a hydraulic pressure acting on the lift cylinder.

[0016]

[0017]

[0018]

According to the fourth aspect of the present invention, when the fixed operation signal is output from the first or second control means, the switching valve closes the pipeline. For this reason, supply and discharge of hydraulic oil to and from the hydraulic damper become impossible, and the axle is fixed.
Further, when the fixed operation signal is not output from the first and second control means, the switching valve brings the pipeline into 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 present invention, the axle connects the steering wheel which is the rear wheel of the industrial vehicle. Therefore,
The turning property and the operability of the industrial vehicle can be improved.

[0021]

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 has a pair of left and right outer masts 2 at the front thereof, 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.

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,
The outer mast 2 is tilted in accordance with the expansion and contraction of the piston rod 5b of the tilt cylinder 5, and the fork 4 is tilted.

The inner mast 3 is connected to a piston rod 6b of a lift cylinder 6 having a body 6a connected to the body frame 1a. 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 the fork 4 moves up and down as the inner mast 3 moves up and down.

A pair of left and right front wheels 7 are provided at the front of the body frame 1a of the forklift 1. Each front wheel 7
The engine E is connected via a differential ring U 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. 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 rear lower portion of the 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 provided on both left and right ends 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 forms 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 connected to the rear wheel 8
It absorbs the force acting on

The damper 12 has 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 firstly moved by a 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 an 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. The fourth hydraulic pipe P4 has a reservoir 16 for storing hydraulic oil.
Is connected.

The electromagnetic switching valve 13 adjusts the operating oil flowing through 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 communicate with each other, and the second hydraulic pipe P1 communicates with the second hydraulic pipe P3.
The hydraulic pipe P2 communicates with the fourth hydraulic pipe P4. At this time,
The hydraulic oil in the first chamber R1 and the second chamber R2 of the damper 12 is in a state of being communicated with the reservoir 16. Therefore, each first
The chamber R1 and the second chamber R2 are in a state in which hydraulic oil can flow in and out, and the damper 12 sets the rear axle 11 to a state in which the rear axle 11 can rotate around the center pin 11a, that is, a state in which it can swing.

When the valve stop 15 is selected, the hydraulic oil flowing through each of 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 damper 12 is in a locked state in which the piston 12b cannot operate. That is, the rear axle 11 cannot swing 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 and the connection portion
Is provided. In addition, the damper 12 and the electromagnetic switching valve 13 constitute an axle fixing mechanism.

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

Further, as shown in FIGS. 1 and 3, an acceleration sensor 21 is provided at the center of both front wheels 7 of the forklift 1.
Is provided. The acceleration sensor 21 is installed in an instrument panel W in the cab 9. The acceleration sensor 21 detects a lateral acceleration that actually acts when the forklift 1 turns, for example, 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 serving as a lift position detecting means for detecting the lift position of the fork 4 is provided at the upper portion. The limit switch 24 is provided at a position approximately 1/4 from substantially above the outer mast 2.

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

As shown in FIG. 4, the forklift 1 has a vehicle speed sensor 2 for detecting the rotation of the differential ring gear U to detect the traveling speed v of the forklift 1.
3 are provided. In this embodiment, the vehicle speed sensor 23 and the gyroscope 20 constitute a lateral force detecting unit.

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 fixed control means and second fixed control means. The controller 31 includes a CPU (Central Processing Unit) and the like, and the controller 31 includes a memory 31a such as a RAM 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. Further, the controller 3
1 is connected to a limit switch 24 and a pressure sensor 25. Further, the controller 31 includes the electromagnetic switching valve 13
Is connected.

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

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

The steering angle sensor 22 is provided for the rear wheel 8 which is a steering 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 a traveling speed v of the forklift 1,
A traveling speed signal indicating the traveling speed v is transmitted to the controller 31.
Output.

The limit switch 24 is turned on when the fork 4 is at or above the reference lift position Z, and outputs an 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 lift position Z, the limit switch 24 is off.

The pressure sensor 25 detects a hydraulic pressure y acting on the lift cylinder 6 and outputs a hydraulic signal indicating the hydraulic pressure y to the controller 31. The controller 31 calculates the rate of change of the angular velocity, that is, the rate of change of the yaw rate ω (the rate of change of the yaw 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 has an angular velocity,
That is, the yaw rate change ratio 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 a 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 a difference in how to calculate the centrifugal force. The calculated centrifugal force Fb is obtained by calculating the product of the traveling speed v and the angular speed ω as shown in the following equation (1).

Fb = v · ω (1) In the memory 31a of the controller 31, a reference ratio value serving as a reference of the yaw rate change ratio Δω / ΔT is stored. The reference ratio value includes 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
Stores an upper reference ratio value K1 and a lower reference ratio value K2.

Further, a reference centrifugal force value serving as a reference of the centrifugal force acting on the forklift 1 is stored in the memory 31a of the controller 31. The reference centrifugal force value is defined as an upper centrifugal force value H1 as a reference when the centrifugal force is increasing and a lower reference centrifugal force value H2 as 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.

In the memory 31a of the controller 31, a reference pressure value N serving as a reference of the hydraulic pressure y acting on the lift cylinder 6 is stored. 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 determines that the yaw rate change rate Δω / ΔT is the upper reference change rate value K1. When the value becomes larger than the upper reference change rate value K1 from the following value, the output of the fixed operation signal is started.

When the fixed operation signal is being output, the controller 31 calculates 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 from a value equal to or larger than the lower reference ratio value K2, stop control for stopping the output of the fixed operation signal is performed. It has become.

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

As shown in FIG.
When the absolute value of the calculated centrifugal force Fb changes from a value equal to or less than the upper reference centrifugal force H1 to a value larger than the upper reference centrifugal force value 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 smaller than the lower reference centrifugal force value H2 while the fixed operation signal is being output. Has become.

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

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 equal to the upper reference ratio value K
When the value is greater than 1 and is equal to or less than the upper reference ratio value K1 and is larger than the lower reference ratio value K2.

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

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 equal to or less than the upper reference centrifugal force value H1 and is larger than the lower reference centrifugal force value H2.

The controller 31 is provided with a pressure sensor 25
The weight of the load placed on the fork 4 is determined based on the detection signal from the fork 4. Further, the controller 31 calculates the center of gravity G (see FIG. 6) 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 G 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 calculates the center of gravity G when the outer mast 2 is tilted most rearward as shown by the dashed line in FIG.

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, a fixed operation signal is output in the case of 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 stationary operation signal is output with priority given to the traveling fixed condition regardless of the cargo handling fixing condition 6). I have. That is, the controller 31 outputs a fixed operation signal when at least one of the traveling fixed conditions or the cargo handling fixed conditions 1) to 6) is satisfied.

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 and P1.
Shield P2 and lock damper 12. Therefore, the rear axle 11 cannot swing, and the damper 1
2 fixes the rear axle 11.

When the fixed operation signal is not output, the electromagnetic switching valve 13 selects the flow valve section 14 and the damper 12
The first chamber R1 and the second chamber R2 are 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 an industrial vehicle configured as described above will be described. FIG. 8 is a flowchart for performing control for fixing the rear axle 11. However, for convenience of explanation, 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. Note that the description of “step” in the specification is abbreviated as “S” in FIG.

First, the controller 31 determines in step 10
At 1, the running speed v of the forklift 1 is read based on the running 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.

At step 103, the controller 31 reads the hydraulic pressure y acting on the lift cylinder 6 based on the hydraulic pressure signal from the pressure sensor 25. Step 10
At 4, the controller 31 calculates the calculated centrifugal force Fb based on the running speed v and the yaw rate ω. The calculated centrifugal force Fb is calculated based on the running speed v and the yaw rate ω according to the equation (1).
And the product of

At step 105, the controller 31 determines the yaw rate ω based on the read yaw rate ω.
, That is, the yaw rate change rate Δω / ΔT.

In step 106, the controller 31 applies a low-pass filter to the oil pressure y and the yaw rate change ratio Δω / ΔT to remove noise.

In step 107, the controller 31 determines whether or not the hydraulic pressure y is equal to or higher than the reference pressure value N. If the hydraulic pressure y is equal to or greater than the reference pressure value N, the process proceeds to step 108;

In step 108, the controller 31 determines whether or not an ON signal is output from the limit switch 24. If the ON signal has been output from the limit switch 24, the process proceeds to step 110, where the controller 31 outputs a fixed operation signal and fixes the rear axle 11. Then, the processing from step 101 is performed again.

On the other hand, if the conditions are not satisfied in steps 107 and 108 and the process proceeds to step 109, the controller 31 continues to output no fixed operation signal.

Then, the controller 31 shifts the processing to step 111. Controller 31 performs step 1
At 11, it is determined whether at least one of the traveling fixed conditions 1) to 5) is satisfied. In this case, if at least one of the traveling fixed conditions 1) to 5) is satisfied, step 11 is executed.
0, output the fixed operation signal, and rear axle 1
1 is fixed. Then, the controller 31 again
The processing from step 101 is performed.

At step 111, the running fixed conditions 1) to
If none of the conditions in 5) is satisfied, the controller 31 outputs the fixed operation signal again without outputting the fixed operation signal.
The processing from step 101 is performed. In this case, the controller 31 performs a process when the fixed operation signal is not output.

When the processing from step 101 is performed in the state where the fixed operation signal is output in step 110, the controller 31 performs the processing in steps 101 to 106 in the case where the fixed operation signal is not output. The same processing is performed.

When it is determined in step 107 that the hydraulic pressure y is equal to or higher than the reference pressure value N, the controller 31
Determines in step 108 whether the ON signal is output from the limit switch 24, and if the ON signal is output from the limit switch 24, continues the output of the fixed operation signal in step 110 .

If the hydraulic pressure y is smaller than the reference pressure value N in step 107, the output of the fixed operation signal is stopped in step 109. Similarly, in step 107, if the hydraulic pressure y is not less than the reference pressure value N,
If the ON signal is not output from the limit switch 24 in step 8, the output of the fixed operation signal is stopped in step 109.

When the output of the fixed operation signal is stopped in step 109, the controller 31
At 1, it is determined whether at least one of the traveling fixed conditions 1) to 5) is satisfied. In this case, if at least one of the traveling fixed conditions 1) to 5) is satisfied, step 110 is executed.
And outputs the fixed operation signal to the rear axle 11
Fixation. Then, the controller 31 performs the processing from step 101 again.

At step 111, the running fixed conditions 1) to
If none of the conditions in 5) is satisfied, the controller 31 outputs the fixed operation signal again without outputting the fixed operation signal.
The processing from step 101 is performed.

FIG. 6 is an explanatory diagram showing a change state of the center of gravity G of the forklift 1 set based on the weight of the load placed on the fork 4 of the forklift 1. Normal,
The center of gravity G1 of the forklift 1 in the front-rear direction when no load is loaded connects the left front wheel 7 and the right rear wheel 8 diagonally, and connects the right front wheel 7 and the left rear wheel 8 diagonally. It is located behind the intersection X when tied to. That is, when the center of gravity G of the forklift 1 is located between the intersection X and the center of gravity G1, the forklift 1 is in a state where both rear wheels 8 are in contact with the ground. Therefore, the contact force of the front wheel 7 decreases,
Any one of the front wheels 7 may float. Therefore,
The controller 31 does not output the fixed operation signal, and makes the rear axle 11, that is, the rear wheel 8 swingable, and raises the contact force on both front wheels 7 side.

In this embodiment, the load acting on the lift cylinder 6 when a load having a weight whose center of gravity G is located at the intersection X is placed on the fork 4, that is, the hydraulic pressure y is equal to the reference pressure value N.

The forklift 1 is placed on the fork 4.
The center of gravity G2 of the forklift 1 when a load having the maximum loading weight that can be transported is placed forward of the intersection X. When the center of gravity G of the forklift 1 is located between the center of gravity G2 and the intersection X, the forklift 1 is in a state where both front wheels 7 are in contact with the ground. Therefore, any one of the rear wheels 8 may float. In this case, since the ground contact force is sufficiently secured on the front wheel 7 side, which is the driving wheel, the rear axle 11 is particularly preferable from the viewpoint of running the forklift 1.
There is no problem with fixing.

However, in a state where the center of gravity G exists between the center of gravity G2 and the intersection point X, when the fork 4 lifts to a position higher than the reference lift position Z and the center of gravity G moves further upward, the forklift 1 The balance in the left-right direction is poor. At this time, the controller 31 outputs a fixed operation signal, fixes the rear axle 11, and causes the forklift 1 to perform the cargo handling work and travel in a stable state.

The present embodiment has the following effects (a) to (ヲ). (A) Since the rear axle 11 can be fixed based on the cargo handling state of the forklift 1, the cargo handling work can be performed in a stable state. In this case, when the hydraulic pressure y acting on the lift cylinder 6 is equal to or higher than the reference pressure value N and the lift position of the load is equal to or higher than the reference lift position Z, that is, when the left-right balance of the forklift 1 is deteriorated, Since the rear axle 11 is fixed, cargo handling work can be performed in a stable state. Further, the forklift 1
When the balance in the left-right direction is poor, the forklift 1 can be run with the rear axle 11 fixed, so that the forklift 1 can be run in a stable state.

(B) Since the lift position of the fork 4 is detected by the limit switch 24, the lift position of the fork 4 can be easily detected based on ON / OFF of the limit switch 24. Therefore, the controller 31
The lift position of the fork 4 can be easily determined based on the detection signal from the limit switch 24, and the rear axle 11 can be easily and reliably fixed based on the determined lift position.

(C) Oil pressure y acting on lift cylinder 6
Can be easily detected by the pressure sensor 25. Therefore, the controller 31 can easily act on the lift cylinder 6 based on the oil pressure signal from the pressure sensor 25.
Can be determined, and the rear axle 11 can be easily and reliably fixed based on the determined hydraulic pressure y. Furthermore,
The controller 31 can easily determine the weight of the load on the fork 4 from the hydraulic pressure y acting on the lift cylinder 6.

(D) When the traveling fixed condition is satisfied, even if the cargo handling fixing condition is not satisfied, the controller 31 outputs a fixed operation signal and the rear axle 1
1, the stability of the forklift 1 during traveling can be further improved.

(E) Since the fork 4 is used as a cargo handling device, the load can be easily held by placing the load on the fork 4. When the balance of the forklift 1 in the left-right direction is deteriorated, the cargo handling is performed with the rear axle 11 fixed, so that the cargo handling can be easily and reliably performed using the fork 4. .

(F) The controller 31 outputs a fixed operation signal based on the yaw rate change rate Δω / ΔT and fixes the rear axle 11.
The rear axle 11 can be quickly fixed at the start of turning to start turning right or left from the straight running of the vehicle. Therefore, the turning of the forklift 1 can be started in a stable state.

(G) The controller 31 outputs a fixed operation signal based on the calculated centrifugal force Fb in addition to outputting a fixed operation signal based on the yaw rate change ratio Δω / ΔT. Therefore, the yaw rate change rate Δω /
After the fixed operation signal is output based on ΔT, even if the fixed operation signal is not output based on the yaw rate change rate Δω / ΔT, the controller 31 continues to operate the centrifugal force Fb.
, The forklift 1 can be turned in a stable state from the start of turning.

(H) When the yaw rate change ratio Δω / ΔT becomes larger than the upper reference ratio value K1, the controller 31 outputs a fixed operation signal to fix the rear axle 11, and sets the lower axle ratio value K2. When the value becomes smaller, a process 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, using only one upper reference ratio value K1, if 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
In the case where the control for stopping the output of the fixed operation signal is performed, if the turning is performed such that the yaw rate change ratio Δω / ΔT changes near the upper reference ratio value K1, the output and the stop of the fixed operation signal are frequently repeated. For this reason, rear axle 1
The fixing and release of the fixing of 1 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 ratio Δω / ΔT is the upper reference ratio value K
Even if the vehicle turns around 1, once the yaw rate change rate Δω / ΔT becomes larger than the upper reference rate value K1, the yaw rate change rate Δω / ΔT is smaller than the lower reference rate value K2. The output of the fixed operation signal is continued until the value becomes a value. Therefore, the rear axle 11 can be fixed in a more stable state.

(I) The controller 31 calculates the calculated centrifugal force F
When b becomes larger than the upper reference centrifugal force value H1, a fixed operation signal is output to fix the rear axle 11, and when b becomes smaller than the lower reference centrifugal force value H2, the output of the fixed operation signal is made. The process for canceling is started. Therefore, similarly to the case of the yaw rate change rate Δω / ΔT shown in the above effect (g), a more stable state is obtained as compared with the case where the rear axle 11 is fixed using only one upper reference centrifugal force value H1, for example. With this, the rear axle 11 can be fixed.

(N) The controller 31 outputs a fixed operation signal, for example, when the yaw rate change ratio Δω / ΔT is larger than the upper reference ratio value K1, and outputs a fixed operation signal. The output of the fixed operation signal is not stopped immediately, but the output of the fixed operation signal is stopped after a predetermined time T has elapsed. 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 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 yaw rate change rate .DELTA. The condition for outputting a 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.

For example, when the forklift 1 travels while performing a high-frequency reversal in which the turning direction of the forklift 1 is switched to the right or left in a short time (1 second or less), the calculated centrifugal force value Fb is usually equal to the upper reference centrifugal force value. A fixed operation signal is output based on the yaw rate change ratio Δω / ΔT without exceeding H1. Therefore, even if the yaw rate change ratio Δω / ΔT becomes 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, and continues to output the fixed operation signal for a predetermined time T. Therefore, the forklift 1
Can be run.

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

(ヲ) In the present forklift 1, a rear axle 11 for connecting the rear wheel 8 which is a steered wheel is swingably provided, and the rear axle 11 is connected to the yaw rate change rate 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-described embodiment, and can be implemented with appropriate modifications without departing from the spirit of the invention. (1) In the above embodiment, the reference pressure value N is set to a value when the center of gravity G is located at the intersection X. On the other hand, the reference pressure value N may be set to a pressure value when the center of gravity G is located at a predetermined position between the intersection X and the center of gravity G2.

(2) In the above embodiment, the fork 4 is attached to the outer mast 2 instead of the limit switch 24.
A position sensor using an optical scale or the like for detecting the elevation position of the vehicle may be used. 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.
Further, a height sensor that can continuously detect the height may be used.

(3) In the above embodiment, a fork is used as a cargo handling device, but a clamp device for holding roll paper or the like may be used as a cargo handling device. (4) 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 calculates the yaw rate change rate 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.
T may be estimated.

That is, the controller 31 obtains the reciprocal of the turning radius r from the steering angle θ. Then, the controller 31 obtains the change rate Δ (1 / r) / ΔT of the reciprocal of the turning radius r. Further, the controller 31 estimates the yaw rate change rate Δω / ΔT by multiplying the reciprocal change rate Δ (1 / r) / ΔT 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) The estimated yaw rate change rate Δω / ΔTx is a value approximating the yaw rate change rate Δωx / ΔT. That is,
The yaw rate ω is represented by the following equation (3) based on the steering angle θ (the turning radius r) and the traveling speed v.

Ω = v / r (3) Then, the controller 31 determines the change rate Δ (1 / r) / ΔT of (1 / r) at the yaw rate ω and the traveling speed v
And the estimated yaw rate change rate Δω /
Calculate ΔTx. 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. (5) In the above embodiment, the gyroscope 20 uses a piezoelectric gyroscope. This may be done using a gas rate gyroscope and an optical gyroscope.

(6) In the above embodiment, the controller 31 compares the calculated centrifugal force Fb with the upper reference centrifugal force value H1 and the lower reference centrifugal force value H2, and outputs a fixed operation signal. The controller 31 calculates 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.

(7) In the above embodiment, in particular, the acceleration sensor 21 need not be provided in the forklift 1. The technical ideas other than the claims that can be grasped from the above embodiment will be described below together with their effects.

(1) In the invention as set forth in claim 1, the cargo handling equipment is a fork 4, and the control device for an industrial vehicle in which the load is held by placing the load on the fork 4. According to this control device, the rear axle 11 is fixed when the left-right balance of the forklift 1 is deteriorated, so that the cargo handling operation can be performed in a stable state with the fork 4.

[0107]

As described above in detail, according to the first aspect of the present invention, changes in the cargo handling state detected by the lifting position detecting means and the load detecting means, and the yaw rate acting on the vehicle.
Since the axle is fixed by operating the axle fixing mechanism based on the ratio , the cargo handling work can be performed in a stable state.

According to the second aspect of the present invention, since the lift position detecting means is a limit switch, the axle can be fixed easily and reliably based on the detection state of the limit switch.

According to the third aspect of the present invention, the lifting drive means is a lift cylinder, and the load detection means is a pressure sensor for detecting the hydraulic pressure of the lift cylinder. , The axle can be easily and reliably fixed.

[0110]

[0111] According to the invention of 請 Motomeko 4, it can be easily fixed to the axle by a hydraulic damper and an electromagnetic switching valve.

According to the fifth aspect of the invention, since the swing of the axle on the steered wheel side of the industrial vehicle is controlled, the turning property and the operability can be improved.

[Brief description of the 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 for connecting both front wheels of a forklift.

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

FIG. 6 is an explanatory diagram showing a change state of a center of gravity of a forklift.

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

FIG. 8 is a flowchart for controlling swinging of a rear axle of a forklift and fixing the rear axle.

FIG. 9 is an explanatory diagram in the case where the swing of the rear axle 11 is controlled based on the yaw rate change rate.

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

[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 comprises an axle fixing mechanism, Reference numeral 20: a gyroscope as a yaw rate detecting means; 21, an acceleration sensor as a lateral force detecting means; 24, a limit switch as a lifting position detecting means; 25, a pressure sensor as a load detecting means; 2 Controllers as fixed control means, P1 to P4... First to fourth hydraulic pipes.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60G 17/005 B66F 9/22 B66F 9/24

Claims (5)

(57) [Claims] 1. An industrial vehicle in which an axle is swingably supported in a vertical direction with respect to a body frame. The industrial vehicle is disposed between the body frame and the axle, and is swingably supported with respect to the body frame. An axle fixing mechanism for fixing the axle to the vehicle body frame, a loading / unloading device provided to be able to move up and down with respect to the vehicle body frame, and a load-holding device for holding a load; A lifting position detecting means for detecting a lifting position of the cargo handling equipment; a load detecting means for detecting a load acting on the lifting drive means; and a lifting position of the loading equipment detected by the lifting position detecting means. Is a predetermined position, and when the load detected by the load detecting means is equal to or more than a predetermined amount, a fixing operation signal for fixing the axle and the body frame by operating the axle fixing mechanism is output. A first fixed control unit to force, provided in the industrial vehicle, a yaw rate acting on the vehicle
The yaw rate detection means for detecting, on the yaw rate detected by the yaw rate detecting means
Change rate calculator that calculates the yaw rate change rate based on
A step and a centrifuge acting on the vehicle based on the yaw rate change rate
Calculate the force, the yaw rate change rate is greater than the reference rate value
When the value also becomes large, operate the axle fixing mechanism
A fixed operation signal for fixing the axle and body frame
Output and the calculated centrifugal force is greater than the reference force.
Output the fixed operation signal when the second fixed value is obtained.
A control device for an industrial vehicle, comprising: a control unit. 2. The control device for an industrial vehicle according to claim 1, wherein said elevation position detecting means is a limit switch. 3. The control device for an industrial vehicle according to claim 1, wherein the lifting drive unit is a lift cylinder, and the load detection unit is a hydraulic pressure sensor that detects a hydraulic pressure of the lift cylinder. 4. A hydraulic damper connected to the vehicle body frame and an axle , wherein the axle fixing mechanism is provided.
And a pipeline for flowing the hydraulic oil supplied to and discharged from the hydraulic damper,
Based on the fixed operation signal, the closed state and the communication state
Axles are controlled by switching between
Is fixed to the body frame, and the axle is
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 vehicle body frame . 5. The steering wheel according to claim 1, wherein the axle is a rear wheel of an industrial vehicle.
The control device for an industrial vehicle according to any one of claims 1 to 4, further comprising: