JP3166617B2 - 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 having an axle swingably provided.

[0002]

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

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

[0004] In this forklift, when the centrifugal force acting on the forklift at the time of turning of the forklift becomes a predetermined value or more, the axle can be fixed and turned in a stable state.

The axle is fixed by locking a damper disposed between the body frame and the axle. In other words, the axle is fixed by blocking (blocking) the pipeline for supplying and discharging the hydraulic oil to the damper so that the damper cannot supply and discharge the hydraulic oil. Further, the locked state of the damper is released by making the pipes communicate with each other, and the axle can swing.

[0006]

However, when the axle is released from the fixed state, the pressure suddenly drops from the state where the pressure of the hydraulic oil in the damper is increased, so that the axle swings suddenly. Start. Therefore, there is a problem that a shock at the time of releasing the fixing of the axle becomes large.

Japanese Patent Application Laid-Open No. 58-183307 discloses a technique that uses an absorber nipple including a check valve and a fixed throttle valve to prevent abrupt swinging of the axle when the axle is unlocked. Is disclosed. However, in this technique, it is necessary to pipe two valves, a check valve and a fixed throttle valve, and there is a problem that the piping work is complicated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an industrial vehicle control device capable of easily and stably releasing the fixing of an axle.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an invention according to claim 1 is to fix an axle in an industrial vehicle having an axle supported to be vertically swingable with respect to a body frame. And a damper disposed between the vehicle body frame and the axle for supplying and discharging hydraulic oil in accordance with the swing of the axle, and a hydraulic oil supplied and discharged from the damper. Through the pipeline
Controlled between the closing state and the communication state, the damper lock is fixed to axle by a blocking state, with the axle swingable by a communicating state, the
When the output of the fixed operation signal is started,
Close control from the communication state to the blocking state, and wherein when the output of the fixed operation signal is canceled, and control of gradually blocking state by controlling the opening degree of the valve portion at a predetermined speed to the communicated state The gist of the present invention is that a proportional valve is provided.

According to a second aspect of the present invention, there is provided an industrial vehicle having an axle vertically swingably supported with respect to a vehicle body frame, a fixing control means for outputting a fixing operation signal for fixing the axle, A damper disposed between the vehicle body frame and the axle and supplying and discharging hydraulic oil in accordance with the swing of the axle, and a pipe through which the hydraulic oil supplied and discharged to and from the damper flows, in a shielding state and a communicating state. Between the control, the damper is locked by setting the shielded state, the axle is fixed, and the axle can be rocked by setting the communication state, and when the output of the fixed operation signal is started, valve
A switching valve for immediately closing the part to control the communication state from the communication state to the shielding state; and a switching valve provided in the pipe line, the opening degree of the valve part being reduced only for a predetermined time at least after the output of the fixed operation signal is released. The main point is that the variable throttle valve is provided.

According to a third aspect of the present invention, in the first or second aspect of the invention, the industrial vehicle includes a load detecting means for detecting a load acting on a lifting drive means for lifting and lowering the cargo handling equipment, and the loading equipment. Lifting position detecting means for detecting the lifting position of, the fixed control means, when the load detected by the load detecting means is equal to or more than the reference pressure value, when the lifting position is equal to or more than the reference lifting position And outputting a fixed operation signal.

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

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

According to a sixth aspect of the present invention, in the first aspect, the axle connects a steering wheel, which is a rear wheel of an industrial vehicle. Therefore, claim 1
According to the described invention, the axle is swingable with respect to the body frame. This axle is fixed by the damper being locked, and is released when the damper is released to be able to swing. In this case, the proportional valve controls the pipeline through which the hydraulic oil supplied and discharged from the damper flows between a shielded state and a communication state, and locks the damper by setting the shielded state to fix the axle. The communication state allows the axle to swing and the fixed signal to be output.
When the force starts, close the valve immediately and check if
Control vital to al shielding state, wherein when the output of the fixed operation signal has been canceled is controlled from the gradually closing state by adjusting the opening degree of the valve portion at ,, a predetermined speed to the communicating state.

According to the second aspect of the invention, the axle is swingable with respect to the body frame. This axle is
The damper is locked by being locked, and is released when the damper is released to be able to swing. In this case, the switching valve controls a pipeline through which the hydraulic oil supplied to and discharged from the damper flows between a shielded state and a communicating state,
By making the said shielding state, the damper is locked and the axle is fixed, and the axle can be rocked by making the communication state, and when the fixing operation signal is output, the communication state is changed to the shielding state. Control. Further, the variable throttle valve provided in the pipe line is controlled so that the opening of the valve portion becomes small when the output of the fixed operation signal is released.
Accordingly, since the hydraulic oil does not rapidly flow out of the damper by the variable throttle valve, the release of the axle is gradually performed at a predetermined speed. Therefore, the fixation of the axle can be released in a stable state.

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

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

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

According to the invention described in claim 6, the axle connects the steering wheels, which are the rear wheels of the industrial vehicle. Therefore,
The turning property and the operability of the industrial vehicle can be improved.

[0020]

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

The forklift 1 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. That is,
The fork 4 moves up and down along the outer mast 2.

A tilt cylinder 5 is connected between the outer mast 2 and the body frame 1a of the forklift 1. The body 5a of the tilt cylinder 5 is connected to the vehicle body frame 1a, and the piston rod 5b of the tilt cylinder 5 is connected to the outer mast 2. That is,
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 has a body 6a.
Is connected to a piston rod 6b of a lift cylinder 6 connected to the vehicle body frame 1a. That is, the inner mast 3 moves up and down based on the expansion and contraction of the piston rod 6 b of the lift cylinder 6, and as the inner mast 3 moves up and down,
The fork 4 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
Is connected to an engine M via a differential ring U and a transmission D, and each front wheel 7 is driven by the engine M.
That is, the front wheels 7 are driving wheels. A pair of left and right rear wheels 8 are provided at the rear of the main body 1a of the forklift 1.

FIG. 2 shows a connecting structure for connecting the rear wheels 8. A rear axle 11 extending in the vehicle width direction is provided at the 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 wheels 8 are provided on both left and right sides of the rear axle 11.
Are connected. The rear wheel 8 is a steering wheel 10 in the cab 9
The steered wheels are steered based on the operation of. The rear axle 11 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 the electromagnetic proportional valve 13. Further, a third hydraulic pipe P3 and a fourth hydraulic pipe P4 are connected to the electromagnetic proportional valve 13.

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

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

In this case, the first through hole E1 and the third through hole E
The valve portion X1 for adjusting the flow rate of the hydraulic oil flowing between the first hydraulic pipe P1 and the third hydraulic pipe P3 is formed by the third communication pipe F1, the first communication groove F1, and the like. The opening degree between the first insertion hole E1 (or the third insertion hole E3) and the first communication groove F1 is determined by the valve portion X.
The opening degree is 1. The second insertion hole E2 and the fourth insertion hole E4
And the second hydraulic pipe P2 and the third
A valve portion X2 for adjusting the flow rate of the hydraulic oil flowing between the hydraulic pipe P4 and the hydraulic pipe P4 is formed. And the opening degree with the 2nd penetration hole E2 (or 4th penetration hole E4) becomes the opening degree of the valve part X2.

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

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

Further, as shown in FIG.
A gyroscope 20 is provided as a yaw rate detecting means on a balance weight 19 provided at a rear portion of the gyroscope. 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 hydraulic 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 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 for detecting the rotation of the differential gear U to detect the traveling speed v of the forklift 1. In this embodiment, the vehicle speed sensor 2
3 and the gyroscope 20 constitute a lateral force detecting means.

Next, the electrical configuration of the control device for an industrial vehicle configured as described above will be described with reference to the electrical block diagram shown in FIG. The control device for an industrial vehicle includes a controller 31 as fixed control means. The controller 31 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 proportional 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 rate Δω / ΔT is obtained by differentiating the yaw rate ω with respect to time.

The controller 31 calculates the acceleration acting in the lateral direction based on the traveling speed signal from the vehicle speed sensor 23 and the angular velocity detection signal from the gyroscope 20. That is, the centrifugal force is calculated. This centrifugal force is 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) 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 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, the memory 31a of the controller 31 stores a reference centrifugal force value serving as a reference of the centrifugal force acting on the forklift 1. 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.

The memory 31a of the controller 31 stores a reference pressure value N serving as a reference for the hydraulic pressure y acting on the lift cylinder 6. As shown in FIG. 9, the controller 31 compares the yaw rate change rate Δω / ΔT calculated based on the angular velocity signal with the upper reference change rate value K1, and 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 a value 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 the above 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 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 of the forklift 1 based on the detection signal from the pressure sensor 25, that is, the weight of the load placed on the fork 4. The center of gravity of the forklift 1 means the center of gravity of the entire forklift including the vehicle body and the load. In this case, the controller 31 controls the outer mast 2 as shown by a one-dot chain line in FIG.
Calculates the center of gravity when is tilted most rearward.

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.

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

The electromagnetic proportional valve 13 is provided with an electromagnetic solenoid 1
The spool 15 is moved based on the excitation state of 3a, and the opening of the valve portions X1 and X2 of the electromagnetic proportional valve 13 is adjusted.
The electromagnetic solenoid 13a is excited by an exciting current, and moves the spool 15 based on the value of the exciting current. That is, the spool 15 moves based on the current value of the exciting current, and the opening of the valve portions X1 and X2 is adjusted. This current value fluctuates between the minimum current value and the maximum current value.
In the present embodiment, the minimum current value means a current of 0 amperes, that is, a state in which no current flows. In this case, the spool 15 is moved by being urged only by the spring force of the spring 13b, and the valve portions X1,
It is positioned at a position where X2 is fully opened.

When the current of the maximum current value is flowing, the spool 15 moves against the spring force, and the valve portion X1,
The opening of X2 is fully closed. That is, the opening degree of the valve portions X1 and X2 decreases as the current value of the exciting current increases, and increases as the current value of the exciting current decreases. In this embodiment, a signal in which the current value of the exciting current is the maximum current value is used as the fixed operation signal.

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

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

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

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

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

When the fixing of the rear axle 11 is released as described above, the valve portions X1 and X2 are gradually opened and the damper 1
2 gradually starts to supply and discharge the hydraulic oil, so that the flow rate of the hydraulic oil supplied to and discharged from the lift cylinder 6 that moves the fork 4 up and down does not change abruptly. Therefore, even if the fixing of the rear axle 11 is released during the cargo handling operation, the cargo handling operation by the fork 4 is performed in a stable state.

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

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

(C) For example, when the forklift 1 turns, the condition of the rear axle 11 being fixed based on the yaw rate change ratio Δω / ΔT is released, and the fixing of the rear axle 11 is released. Even in the case where the rear axle 11 is released, the fixing of the rear axle 11 is gradually released, so that an impact generated when the rear axle 11 is released can be reduced, and the traveling performance and the turning performance of the forklift 1 can be improved.

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

In the present embodiment, the rear axle 11 is fixed based on the yaw rate change ratio Δω / ΔT and the calculated centrifugal force Fb. Therefore, since the turning of the forklift 1 can be performed more smoothly, the turning performance of the lift 1 can be improved.

Further, in the present embodiment, as shown in the effect (b) above, the impact acting on the lift cylinder 6 when the rear axle 11 is released can be reduced, and the fork 4 can be smoothly and stably operated. Cargo handling work can be performed. Accordingly, in the present forklift 1, the cargo handling operation with the fork 4 can be performed in a stable state, and the traveling performance and the turning performance can be improved.

(E) In the present forklift 1, the rear axle 11 for connecting the rear wheel 8, which is the 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 as follows with appropriate modifications without departing from the spirit of the invention. (1) In the above-described embodiment, the fixing of the rear axle 11 is gradually released by using the electromagnetic proportional valve 13, but as shown in FIG. 11, the electromagnetic switching valve 41 is used instead of the electromagnetic proportional valve 13. Alternatively, the fixing of the rear axle 11 may be gradually released by using a variable throttle valve 42 instead of the fixed throttle valve 17.

The electromagnetic switching valve 41 has a body and a spool, and a flow valve portion 43 and a stop valve portion 44 are formed on the spool. The electromagnetic switching valve 41 adjusts the 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 43 or the stop valve portion 44.

When the flow valve section 43 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 makes the rear axle 11 rotatable around the center pin 11a, that is, in a swingable state.

When the stop valve section 44 is selected, the hydraulic oil flowing through each of the hydraulic pipes P1 to P4 is shielded. Therefore, the operating oil cannot enter or exit the first chamber R1 and the second chamber R2. That is, the rear axle 11 cannot swing and is fixed by the damper 12.

The variable throttle valve 42 has a large throttle portion with a large throttle diameter and a small throttle portion with a small throttle diameter. The variable throttle valve 42 can change the throttle diameter in two stages. I have.

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

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

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

When the fixed operation signal is not being output, the electromagnetic switching valve 41 selects the flow valve portion 43 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.

As shown in FIG. 13, the variable throttle valve 42
When no fixed operation signal is output, the large aperture section is selected. When the fixed operation signal is output from this state, the aperture of the variable throttle valve 42 switches from the large aperture to the small aperture. Next, when the fixed operation signal is released, the variable throttle valve 42 switches the aperture from the small aperture to the large aperture after a lapse of a predetermined time J from the time when the fixed operation signal is released.

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

(2) In the above embodiment, the fixed throttle valve 18 may be a variable throttle valve 42. (3) Although the variable throttle valve 42 capable of adjusting the throttle in two stages is used in the above another embodiment (1), a variable throttle valve adjustable in multiple stages may be used.

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

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

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

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

(5) In the above embodiment, the variable throttle valve 42 always selects the large throttle valve portion, and only when the fixed operation signal is released, the variable throttle valve 42 opens the small throttle valve portion for a predetermined time J from the release time. You may comprise so that it may select.

(6) 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.

(7) In the above embodiment, the controller 31 outputs the fixed operation signal by comparing the calculated centrifugal force Fb with the upper reference centrifugal force value H1 and the lower reference centrifugal force value H2. The controller 31 calculates the actual centrifugal force F
a may be configured to output a fixed operation signal by comparing a with the upper reference centrifugal force value H1 and the lower reference centrifugal force value H2. 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, the controller 31 can easily output the fixed operation signal based on the actual centrifugal force Fa.

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

Among the technical ideas grasped from the above embodiment, the technical ideas other than the claims are described below together with the effects. (1) In the invention described in claim 4, the industrial vehicle is:
Further, the vehicle further comprises a lateral force detecting means for detecting a lateral force acting on the vehicle. , When the change rate of the yaw rate becomes larger than the reference rate value based on the change rate of the yaw rate calculated by the change rate calculation means, or when the lateral force becomes the reference force value. An industrial vehicle control device that outputs a fixed operation signal when: According to the control device for an industrial vehicle, for example, even when the output of the fixed operation signal is released at the time of the cargo handling operation at the cargo handling device or the traveling of the industrial vehicle, the fixation of the axle is gradually released. In addition, the traveling of the industrial vehicle can be stably performed.

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

[0098]

As described above in detail, according to the first aspect of the present invention , the fixed operation signal is output from the state in which the axle can swing.
Immediately after the output starts, the communication state changes to the shielding state
When the damper is locked and the axle is fixed,
In addition, when the output of the fixed operation signal is released from the state where the axle is fixed, the opening of the valve portion is adjusted at a predetermined speed and the control is gradually performed from the closed state to the communication state , so that The axle can be unlocked.

According to the second aspect of the present invention, the axle swings.
When the output of the fixed operation signal is started from the possible state
Immediately switches from the communication state to the shielding state, and the damper
Locked and axle fixed. When the output of the fixed operation signal is released from the state where the axle is fixed, the valve portion of the variable throttle valve is small. Accordingly, the supply and discharge of the hydraulic oil to the damper is gradually started, so that the fixing of the axle can be gradually released.

According to the third aspect of the present invention, for example, when the lifting position of the cargo handling equipment becomes less than the reference lifting position from the state where the fixed operation signal is output, the output of the fixed operation signal is released. Since the supply and discharge of hydraulic oil is gradually started in the damper, it is possible to stably perform the cargo handling work in the cargo handling equipment.

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

According to the fifth aspect of the invention, for example, even if the fixed operation signal is released during traveling of the industrial vehicle, the fixing of the axle is gradually released, so that the industrial vehicle can be driven in a stable state. it can.

According to the sixth aspect of the present invention, since the axle is a shaft connecting the steering wheels, which are the rear wheels of the industrial vehicle,
The turning property and the operability of the industrial vehicle 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 mechanism for fixing a rear axle.

FIG. 3 is a plan view showing a forklift.

FIG. 4 is a schematic configuration diagram showing a mechanism 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 a schematic configuration diagram showing an outline of an electromagnetic proportional valve.

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

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

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

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

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

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

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

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

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

[Explanation of symbols]

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

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60G 17/005 B66F 9/22 B66F 9/24

Claims (6)

(57) [Claims] 1. An industrial vehicle in which an axle is swingably supported in a vertical direction with respect to a body frame, wherein: a fixed control means for outputting a fixed operation signal for fixing the axle; A damper disposed between the dampers for supplying and discharging the hydraulic oil in accordance with the swing of the axle; and a pipe for flowing the hydraulic oil supplied and discharged from the damper, between a shielded state and a communicating state, and controlling the shielding. locking the damper is fixed to the axle by a state, with the axle swingable by a communicating state, the fixed
When the operation signal output starts, close the valve immediately.
Te controls from the communication state to the shielding state, and when the output of the fixed operation signal is canceled, controls from the gradually closing state by adjusting the opening degree of the valve portion at a predetermined speed to the communicated state An industrial vehicle control device including a proportional valve. 2. An industrial vehicle in which an axle is swingably supported in a vertical direction with respect to a body frame, wherein: a fixed control means for outputting a fixed operation signal for fixing the axle; A damper, which is disposed between and supplies hydraulic oil according to the swinging of the axle, and a pipe through which hydraulic oil is supplied and discharged to and from the damper,
Controlled between the closing state and the communication state, to fix the axle to lock the damper in that with the blocking state, as well as the axle swingable by a communicating state, the
When the output of the fixed operation signal is started,
A switching valve that is closed to control from a communicating state to a blocking state; and a variable valve that is provided in the pipeline and reduces the opening of the valve unit only for a predetermined time from when the output of the fixed operation signal is released. A control device for an industrial vehicle including a throttle valve. 3. The industrial vehicle includes: load detection means for detecting a load acting on a lifting drive means for lifting and lowering the cargo handling equipment; and lifting position detection means for detecting a lifting position of the cargo handling equipment. The industrial vehicle according to claim 1, wherein the fixed control unit outputs a fixed operation signal when the load detected by the load detection unit is equal to or higher than a reference pressure value and the lift position is equal to or higher than the reference lift position. Control device. 4. The industrial vehicle further comprises: a yaw rate detecting means for detecting a yaw rate acting on the vehicle; and a change rate calculating means for calculating a change rate of a yaw rate detected by the yaw rate detecting means. The fixed control means detects that the load detected by the load detection means is equal to or higher than the reference pressure value and the lift position is equal to or higher than the reference lift position, or that the change in the yaw rate calculated by the change rate calculation means is used. 4. The control device for an industrial vehicle according to claim 3, wherein a fixed operation signal is output when the rate of change of the yaw rate becomes larger than the reference rate based on the rate. 5. The industrial vehicle comprises: a yaw rate detecting means for detecting a yaw rate acting on the vehicle; and a change rate calculating means for calculating a change rate of the yaw rate detected by the yaw rate detecting means, The control means outputs a fixed operation signal based on the change rate of the yaw rate calculated by the change rate calculation means when the change rate of the yaw rate becomes larger than a reference rate value. 3. The control device for an industrial vehicle according to 2. 6. The control device for an industrial vehicle according to claim 1, wherein the axle connects a steering wheel that is a rear wheel of the industrial vehicle.