JPH10338011A - Vehicle body oscillation control device for industrial vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cope with the situation of a vehicle when the unstable attitude of a vehicle is foreseeable for a driver, etc., so that turn action of an industrial vehicle can be made in a stable condition. SOLUTION: A rear axle 10 for supporting rear wheels 11 is provided fluctuation freely to a vehicle body frame with the center pin 10a as the center, and the vehicle body frame and the end part of the rear axle 10 are connected via a damper 13. A controller 25 inputs a tire angle signal θ from a tire angle sensor 21, and a vehicle speed V from a vehicle speed sensor 22, to calculate lateral G and a lateral G change ratio η. When any of the lateral G and the lateral G change ratio η has a set value or more respectively, the controller 25 switches an electromagnetic selector valve 14 to make a damper 13 into an unexpandable lock condition to lock the rear axle 10 to the vehicle body frame. When the lateral G has a given value or more in this locked condition, an alarm is sounded with travel foreseen unstably.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle body swing control device for an industrial vehicle, and more particularly to a vehicle body swing control device for fixing an axle supported to be able to swing.

[0002]

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

Japanese Patent Laid-Open Publication No. Sho 58-221903 discloses a turning detecting means for detecting a centrifugal force generated during turning of a forklift. When the detected centrifugal force exceeds a predetermined value, the swinging motion is detected. A technique has been proposed in which an axle movably supported is fixed by an axle fixing mechanism.

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

Further, the applicant of the present invention detects both lateral acceleration (lateral G) acting on a vehicle from a detector for detecting a tire angle of a steered wheel and a detector for detecting a vehicle speed without using an acceleration sensor. A technique has been proposed in which the lateral G is estimated by calculation using a device, and the axle is fixed when the estimated lateral G is equal to or greater than a set value (Japanese Patent Laid-Open No. 8-149560). As a detector for detecting a tire angle, for example, a potentiometer or the like for detecting rotation during steering of a steered wheel is used.

[0006]

However, as described above, when the centrifugal force exceeds a predetermined value, or when the lateral G
Becomes larger than the set value, the posture of the vehicle may become unstable when the traveling state continues even when the axle is fixed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to make a driver or the like unstable in posture of a vehicle so that the turning operation of an industrial vehicle can be performed in a stable state. An object of the present invention is to provide a vehicle body swing control device for an industrial vehicle that can cope with such a situation.

[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. , An axle fixing mechanism that fixes an axle swingably supported on the vehicle body frame to the vehicle body frame, a driving state detecting unit that detects a driving state of the industrial vehicle, The lateral G estimating means for estimating the lateral G applied to the industrial vehicle based on the detection result of the state detecting means, and the lateral G estimating means estimates when the axle fixing mechanism fixes the axle to the body frame. The gist of the present invention is a vehicle body swing control device for an industrial vehicle including a control unit that outputs a lateral G countermeasure signal when the lateral G becomes larger than a reference value.

According to a second aspect of the present invention, in the first aspect, the lateral G estimating means includes a lateral G to be added to an industrial vehicle in the future.
The gist is to estimate According to a third aspect of the present invention, in the second aspect, the traveling state detecting means includes a vehicle speed detecting means for detecting a vehicle speed of an industrial vehicle, and a steering angle detecting means for detecting a steering angle of the industrial vehicle. The gist of the means is to make an estimation based on the vehicle speed and the steering angle.

According to a fourth aspect of the present invention, in the first aspect, the traveling state detecting means is a yaw rate detecting means for detecting a yaw rate applied to the industrial vehicle, and the lateral G estimating means is a means for detecting the yaw rate detected by the yaw rate detecting means. The gist is to estimate the lateral G currently applied to the industrial vehicle based on the yaw rate.

[0011] The invention according to claim 5 is the invention according to claims 1 to 4.
In any of the above, the gist is that a warning means for inputting the lateral G countermeasure signal and issuing a warning based on the lateral G countermeasure signal is provided.

Therefore, according to the present invention, in the industrial vehicle, the axle can swing with respect to the body frame. The axle is fixed by operation of the axle fixing mechanism, and is brought into a swinging state by releasing the operation. In this case, the traveling state detecting means detects the traveling state of the industrial vehicle, and the lateral G estimating means estimates the lateral G based on the traveling state of the vehicle detected by the traveling state detecting means. The control means outputs a lateral G countermeasure signal when the lateral G becomes larger than the reference value based on the lateral G estimated by the lateral G estimating means.

According to the second aspect of the present invention, the lateral G estimating means estimates a lateral G to be added to the industrial vehicle in the future. According to the third aspect of the present invention, the vehicle speed detecting means detects the vehicle speed of the industrial vehicle, and the steering angle detecting means detects the steering angle of the industrial vehicle. Further, the lateral G estimating means includes:
The lateral G is estimated based on the vehicle speed and the steering angle.

According to the invention described in claim 4, the yaw rate detecting means detects a yaw rate applied to the industrial vehicle.
The lateral G estimating means estimates the lateral G currently applied to the industrial vehicle based on the yaw rate detected by the yaw rate detecting means.

According to the fifth aspect of the present invention, the warning means inputs the lateral G countermeasure signal and issues a warning based on the lateral G countermeasure signal. As a result, the driver can know that the vehicle will become unstable when the current running state continues.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) A first embodiment in which the present invention is embodied in a body swing control device of a forklift will be described below with reference to FIGS.

The forklift 1 as an industrial vehicle in the present embodiment is a four-wheeled vehicle with front-wheel drive and rear-wheel steering.
An inner mast 3 is provided between a pair of left and right outer masts 2 erected at the front of the machine stand of the forklift 1 so that the inner mast 3 can be moved up and down via a chain (not shown). It is suspended in. The outer mast 2 is connected to the vehicle body frame 1a via a tilt cylinder 5, and tilts when the piston rod 5a of the tilt cylinder 5 is driven to expand and contract. The piston rod 6a of the lift cylinder 6 disposed on the back surface of the outer mast 2 is connected to the upper end of the inner mast 3, and the fork 4 is moved up and down by the expansion and contraction drive of the piston rod 6a of the lift cylinder 6. Has become.

The left and right front wheels 7 are operatively connected to an engine 9 via a differential ring gear 8 (shown in FIG. 1) and a transmission (not shown), and are driven by the power of the engine 9. As shown in FIGS. 1 and 2, a rear axle 10 as an axle is swingable (rotatable) up and down around a center pin 10 a in a state extending in a vehicle width direction at a rear lower portion of the body frame 1 a. Supported. The left and right rear wheels 11 are steerably connected to each end of a pair of left and right piston rods of a steering cylinder (not shown) disposed on the rear axle 10 via a link mechanism (not shown). And is supported so as to be able to swing integrally with the rear axle 10. The left and right rear wheels 11 are steered by driving the steering cylinder based on the operation of the steering wheel 12.

A single hydraulic damper (hereinafter simply referred to as "damper") 13 is disposed between the vehicle body frame 1a and the rear axle 10 so as to connect them.
The damper 13 is a double-acting hydraulic cylinder, and a cylindrical cylinder 13a of the damper 13 is provided on the body frame 1a side.
Is connected to the rear axle 10, and a piston rod 1 extending from a piston 13b housed in a cylinder 13a.
The tip of 3c is connected.

The damper 13 functions as a switching valve via a first pipe P1 and a second pipe P2 which are connected to each of a first chamber R1 and a second chamber R2 partitioned by a piston 13b. Are connected to the electromagnetic switching valve 14. Solenoid switching valve 14
Is a normally closed type two-port two-position switching valve that closes when demagnetized. The spool has a stop valve portion 15 and a flow valve portion 16 formed thereon. The third in the second pipeline P2
An accumulator 17 for storing hydraulic oil via a pipe P3
Are connected via a check valve 18.

By disposing the spool of the electromagnetic switching valve 14 at the shut-off position shown in FIG. 2 with respect to the body, the damper 13 is in a locked state in which the outflow / inflow of the hydraulic oil in both chambers R1 and R2 is impossible. The swing of the axle 10 is locked. On the other hand, when the spool of the electromagnetic switching valve 14 is disposed at the communication position with the body (the state where the spool position is switched to the opposite side from the state of FIG. 2), the damper 13 operates between the two chambers R1 and R2. The oil is in a free state in which the outflow / inflow of the oil is possible, and the swing of the rear axle 10 is allowed. A throttle valve 19 is provided on the second pipe P2. The axle fixing mechanism is constituted by the damper 13, the electromagnetic switching valve 14, and the like.

As shown in FIGS. 1 and 2, on one side of a kingpin 20 that rotatably supports the rear wheel 11, the amount of rotation of the kingpin 20 is detected and the steering angle (tire angle) of the rear wheel 11 is detected.
A tire angle sensor 21 serving as a steering angle detecting means, which constitutes a running state detecting means and a lateral G estimating means, which detects θ, is provided. The tire angle sensor 21 includes, for example, a potentiometer. As shown in FIG. 1, the differential ring 8 detects the rotation of the differential ring gear 8 to detect the vehicle speed V of the forklift 1, and constitutes running state detecting means and lateral G estimating means. A sensor 22 is provided.

As shown in FIG. 1, the outer mast 2 is provided with a lift sensor 23 having a predetermined height, for example, a limit switch. Lift sensor 23 is fork 4
Is set to turn on when the lift height of the set is equal to or more than the set value ho, and set to be turned off when the lift is less than the set value ho. In this embodiment, the set value ho is set to half the maximum lift height hmax. Further, the lift cylinder 6 is provided with a pressure sensor 24 for detecting the oil pressure inside the cylinder. The pressure sensor 24 outputs a detection value according to the load w on the fork 4.

Next, the electrical configuration of the vehicle body swing control device of the forklift 1 will be described with reference to FIG. The forklift 1 is provided with a controller 25 as control means for performing swing control and the like to be described later. Controller 2
5 includes a microcomputer 26, an AD conversion circuit 27 to
29 and an excitation / demagnetization drive circuit 30 are incorporated. The microcomputer 26 includes running state detecting means and a lateral G
CPU (central processing unit) 31, R as estimating means
OM (read only memory) 32, RAM (read / write memory) 33, clock circuit 34, counters 35 and 36,
An input interface 37 and an output interface 38 are provided.

The CPU 31 stores the detected values θ from the tire angle sensor 21, the vehicle speed sensor 22, and the pressure sensor 24,
V and w are input via the AD conversion circuits 27 to 29, and an on / off signal from the elevation sensor 23 is input. The electromagnetic switching valve 14 has a CPU
The switching is controlled by exciting and demagnetizing the solenoid 14a based on a control signal output from the excitation / demagnetization drive circuit 30 by the solenoid 31a. That is, the electromagnetic switching valve 14 is demagnetized based on a lock signal output from the CPU 31 via the excitation / demagnetization drive circuit 30 and is placed in the cut-off position, and the solenoid 14a is energized based on the lock release signal to move to the communication position. Be placed.

The CPU 31 has an output interface 3
An alarm device 40 as a warning means is connected via 8. Various kinds of program data are stored in the ROM 32, and one of them is the program data of the swing control processing shown in the flowcharts of FIGS. Here, the swing control is control for locking the swing of the rear axle 10 at a time when a predetermined operating condition is satisfied. In the present embodiment, the lateral G acting on the vehicle (the centrifugal acceleration acting in the lateral direction of the machine when turning) Gs And a calculated value obtained by calculating the temporal change rate η of the lateral G as a judgment value. When either one of the Gs value and the η value exceeds each set value, the swing of the rear axle 10 is locked. Is set.

In the flowcharts of FIGS. 7 and 8, S30 constitutes the horizontal G estimating means, and S10, S20,
S40 constitutes a running state detecting means. Horizontal G (Gs
6) are set in accordance with the load w and the lift H as shown in the maps of FIGS. 6 (a) and 6 (b). In other words, when the load w is less than the set value wo, when the load w
As shown in the figure, when the lift H is less than ho (the lift sensor 23 is turned off), the set value is set to “G2” and the lift H
Is equal to or greater than ho (the lift sensor 23 is turned on), the set value is "G1" (in the present embodiment, G1 is set to G2 / 2).
Is set to When the load w is equal to or greater than the set value w0, the set value is set to "G2" when the lift H is less than ho, as shown in FIG. The rear axle 10 is set to be locked.

The ROM 32 stores set values G1, G2, go of the lateral G change rate η. Each set value G1,
G2 and go are values obtained from running experiments or theoretical calculations, and are set so that the rear axle 10 is locked at a time necessary for achieving running stability.
The CPU 31 has two flags Fg and Fgv. The flag Fg is set when the horizontal G (Gs) exceeds the set values G1 and G2, and the flag Fgv is set when the horizontal G change rate η exceeds the set value go. Is set.

Further, the ROM 32 stores a map for obtaining a reciprocal value 1 / r of the turning radius of the vehicle from the tire angle θ. In the present embodiment, the lateral G (Gs) is estimated by calculation using two detected values θ and V from the tire angle sensor 21 and the vehicle speed sensor 22. Estimated value Gs of lateral G
Is given by the following equation (1) using the reciprocal value 1 / r of the turning radius determined from the tire angle θ.

Gs = V ² / r (1) The time difference ΔG / ΔT of the lateral G, that is, the lateral G change rate η
Is represented by the following equation (2).

Η = ΔG / ΔT = V ² Δ (1 / r) / ΔT (2) In the present embodiment, the lateral G change rate η is calculated by two detection values based on the relationship of the equation (2). It is calculated by the following equation using θ and V.

Η = ΔG / ΔT = V ² · | 1 / r−1 / r1 | where η is a change amount of the lateral G per a predetermined time ΔT (for example, several tens of milliseconds), 1 / r, 1 / r1 is a reciprocal value of the turning radius before and after the predetermined time ΔT has elapsed, respectively.
In the present embodiment, the tire angle data θ for a plurality of past times (the control time interval ΔTo is one time) is stored in the RAM 32, and the tire angle data θ1 before the predetermined time ΔT (= n · ΔTo) is stored. Read, current detection value θ and old detection value θ
Reciprocal value of each turning radius determined from 1 and 1 / r, 1
/ (R1) = Δ (1 / r-1 / r1 |)
r) / ΔT. In the present embodiment, for example, the tire angle θ takes a negative value at the left turning angle and a positive value at the right turning angle, and the reciprocal value 1 / r obtained from the θ value also corresponds to the negative value. With a sign.

Incidentally, the lateral G change rate η corresponds to the time derivative of the equation (1) and is expressed by the following equation. η = V ² · Δ (1 / r) / ΔT + (1 / r) · 2V · ΔV / ΔT (3) In the equation (3), ΔV / ΔT is the rate of change of the vehicle speed V with time. Usually, in the forklift 1, since the vehicle speed V during the turning can be regarded as substantially constant, ΔV /
The ΔT value is a value sufficiently smaller than the Δ (1 / r) / ΔT value in the preceding section. Therefore, in the present embodiment, the above equation (2) approximated by ignoring the latter term in the equation (3) is employed for estimating η.

In the present embodiment, measures are taken to prevent frequent switching between lock and unlock due to the load w, the lift H, and the lateral G change rate η taking values near the set values. doing. That is, when the flag Fgv is “1”, the set value “α ·
When the flag Fg is “1”, the setting values for Gs are “wo”, “α · wo” and “α · ho” smaller than “ho” (for example, 0.5 <α). <
1) is adopted respectively.

The two counters 35 and 36 operate for a predetermined duration T based on the clock signal from the clock circuit 34.
And the horizontal G (Gs) and η are values to be unlocked (that is, the judgment values Gs and η are values less than the respective set values go, G1 and G2). The duration of the condition is measured. The lock is released after the lock release condition is satisfied for a predetermined continuation time T, and the two counters 35 and 36 are for counting the continuation time.

Next, the swing control of the forklift 1 will be described with reference to the flowcharts of FIGS. While the ignition key is on, each sensor 21 to 24
Detection signals θ, V, w, etc. from the
The CPU 31 executes the swing control process at intervals of a predetermined time ΔTo (for example, 10 to 50 milliseconds).

First, in step 10, the CPU 31 reads the detected values of the tire angle θ, the vehicle speed V, and the load w. In step 20, the reciprocal value 1 / r of the turning radius is obtained from the tire angle θ using the map stored in the ROM 32.

In step 30, the estimated value Gs of the lateral G is obtained from the equation (1) using the vehicle speed V and the reciprocal value 1 / r of the turning radius.
Is calculated. In step 40, the lateral G change rate η is calculated. That is, the tire angle data θ1 before the predetermined time ΔT is read out from the predetermined storage area of the RAM 33, and the reciprocal value 1 / r1 of the turning radius before the predetermined time ΔT obtained from the θ1 value is obtained by:
Using the current 1 / r value and the vehicle speed V, η = V ² · 1 /
lateral G change rate η based on the relationship of equation (2) of r−1 / r1 |
Is calculated.

In step 50, it is determined whether or not η is equal to or greater than a set value go. If η is equal to or greater than the set value go,
Proceeding to step 60, the flag Fgv is set to "1". If η is less than the set value go, proceed to step 70,
Unlock condition (η <go when Fgv = 0, Fgv = 1
In this case, it is determined whether or not η <α · go) is satisfied for a predetermined duration T. The counter 35 counts the predetermined duration T. The counter 35 is reset each time η ≧ go is satisfied, and the counter 35 starts counting whenever η <go or η <α · go is satisfied.

If the counter 35 has not counted the predetermined duration T in step 70,
And the flag Fgv is not changed. On the other hand, if the lock release condition is satisfied for the predetermined duration T, step 8
Proceeding to 0, the flag Fgv is set to "0". That is,
The lock is not released immediately when the lock release condition is satisfied, but the lock release is delayed by a predetermined duration T.

The next steps 90 to 170 are for determining whether the rear axle 10 should be in a free state or a locked state based on the lateral G (Gs). In the present embodiment, the free / lock determination of the rear axle 10 based on the lateral G (Gs) is performed as shown in FIG.
As shown in the maps of (a) and (b), the determination is performed based on the set values G1, G2, etc. set according to the load w and the lift H.

In step 90, it is determined whether the load w is equal to or greater than the set value w0. If the load w is less than the set value wo, the process proceeds to step 100. If the load w is equal to or more than the set value wo, the process proceeds to step 110.

When the load w is less than the set value wo,
In step 100, it is determined whether or not the height H is equal to or greater than a set value ho. When the lift H is less than the set value ho, it is determined in step 120 whether or not Gs ≧ G2 is satisfied. When the lift H is not less than the set value ho, it is determined in step 130 whether Gs ≧ G1 is satisfied. Determine whether or not. In each step, when Gs ≧ G2 or Gs ≧ G1, the process proceeds to step 150, and the flag Fg is set to “1”.

In each step, Gs ≧ G2 or Gs ≧ G1 does not hold (that is, Gs <G2 or Gs
If <G1), the process proceeds to step 160. Step 1
At 60, it is determined whether or not the lock release condition (that is, Gs <G2 or Gs <G1) is satisfied for a predetermined duration T. The counter 36 counts the predetermined continuation time T. Whenever Gs ≧ G2 or Gs ≧ G1, the counter 3
6 is reset and Gs <G2 or Gs <
Each time G1 is established, counting of the counter 36 is started.

In step 160, when the counter 36 has not counted the predetermined duration T (when the unlock condition has not continued for the predetermined duration T), the process proceeds to step 180, and the flag Fg is changed. Absent. on the other hand,
If the lock release condition is satisfied for the predetermined duration T, the routine proceeds to step 170, where the flag Fg is set to "0".
That is, also in this case, the lock is not immediately released at the same time as the unlock condition is satisfied, but the lock release is delayed by a predetermined duration T.

On the other hand, if the load w is equal to or greater than the set value w0, it is determined in step 110 whether the lift H is equal to or greater than the set value ho. Then, the lift H is equal to the set value h.
o In the above case, the routine proceeds to step 150, where "1" is set in the flag Fg. If the lift H is less than the set value ho, the routine proceeds to step 140, where it is determined whether or not Gs ≧ G2. When Gs ≧ G2 holds,
In step 150, "1" is set to the flag Fg. When Gs ≧ G2 is not satisfied (that is, Gs <G2), the process proceeds to step 160, and it is determined whether or not the lock release condition (that is, Gs <G2) is satisfied for a predetermined duration T. If this condition is satisfied, step 1
In step 70, the flag Fg is set to "0", and if not satisfied, the flag Fg is not changed and the next step 180
Proceed to.

In step 180, if either of the flags Fgv and Fg is "1", a lock command (lock signal) is output. As a result, when at least one of the lateral G (Gs) and the lateral G change rate η exceeds each set value,
The electromagnetic switching valve 14 is switched to the shut-off position, and the rear axle 10 is locked.

FIG. 5 is a graph showing changes in the lateral G (Gs) and the lateral G change rate η during turning. In this graph, for example, when the vehicle turns left from straight ahead while traveling, the rear axle 10 is turned on when the lateral G change rate η (corresponding to ηH and ηL in the figure), which is the rising change of the lateral G, exceeds the set value go. Is locked. Therefore, the rear axle 10 is locked almost immediately at the same time as the turning start, and the lock timing is not delayed. Then, immediately after the horizontal G (G
s, where G _SH and G _{SL are} equivalent to the set values (G1, G
2) As described above, the lock of the rear axle 10 is maintained as it is even when the tire angle θ falls to a certain cut angle and the lateral G change rate η decreases.

Then, the steering wheel 12 is turned from left turning to right turning.
When changing from the right side G to the left side G, there is a section where the side G is extremely short but less than the set value. However, the horizontal G is the set value (G1,
G2), the lateral G change rate η exceeds the set value go since the tire angle θ is being changed in this section. Therefore, the lock of the rear axle 10 is not released during the turning. In addition, since there is a time delay when the lock is released, when both the flag Fgv = 1 and the flag Fg = 1 are switched, an overlap in which both of them become “1” is secured. The lock is not unlocked due to a slight timing shift of the value change.

Note that GSH and GSL in FIG. 5 represent the lateral G during high-speed running and low-speed running, respectively. Further, in the present embodiment, once the lock of the rear axle 10 is executed, the lock of the rear axle 10 is not changed unless the set value at that time is slightly smaller than the set value α (for example, 0 <α <1). Release is not performed. Therefore, each judgment value η, H, w is set to its set value go,
Frequent switching between lock and unlock due to accidental values near ho and wo is prevented.

Returning again to the flowcharts of FIGS. 8 and 9, after the processing of step 180, step 190
Move to In step 190, the alarm 40
It is determined whether a condition for sounding (hereinafter referred to as a sounding condition) is satisfied.

The ringing conditions are as follows. (A) When both w ≧ wo and H ≧ ho are satisfied (b) w ≧ wo, H <ho, and Gs ≧ G3 (> G2)
(C) w <wo, H ≧ ho, and Gs ≧ G4 (> G1)
(D) w <wo, H <ho, and Gs ≧ G5 (> G2)
Here, in the case of the above (a), when the load w is equal to or greater than the set value w0 and the lift H is equal to or greater than the set value ho, and the vehicle continues traveling, the axle fixing mechanism Even if the rear axle 10 is locked, there is a risk of unstable running
0 is sounded.

In the case of (b), the load w is equal to the set value w.
o, the lift H is less than the set value ho, and
Since the lateral G (Gs) is equal to or greater than the sounding reference value G3, if the vehicle continues to travel as it is, the rear axle 1 is driven by the axle fixing mechanism.
Even if 0 is locked, there is a risk of unstable running, so the alarm 40 is sounded. The ringing reference value G
3 or more means that the horizontal G (Gs
). The area A indicates an area where running becomes unstable even if the rear axle 10 is locked by the axle fixing mechanism. The vertical axis represents the vehicle speed V, and the horizontal axis represents the tire angle θ. A region B indicates a region where traveling is stable when the rear axle 10 is locked by the axle fixing mechanism. A region C indicates a region where traveling is stable without locking the rear axle 10 by the axle fixing mechanism.

Next, in the case of (c), the load w is less than the set value w0, the lift H is not less than the set value ho, and the lateral G (Gs) is not less than the ringing reference value G4. Therefore, if the vehicle continues to travel as it is, the vehicle may run unstable even if the rear axle 10 is locked by the axle fixing mechanism.
The alarm 40 is caused to sound. The above-mentioned ringing reference value G4 or more means that the horizontal G
(Gs). The area A1 indicates an area where running becomes unstable even if the rear axle 10 is locked by the axle fixing mechanism. The vertical axis represents the vehicle speed V, and the horizontal axis represents the tire angle θ. A region B1 indicates a region where traveling is stable when the rear axle 10 is locked by the axle fixing mechanism. A region C1 indicates a region where the traveling is stable without locking the rear axle 10 by the axle fixing mechanism.

Next, in the case of (d), the load w is less than the set value w0, the lift H is less than the set value ho, and the lateral G (Gs) is greater than the sound reference value G5. Therefore, if the vehicle continues to travel as it is, the vehicle may run unstable even if the rear axle 10 is locked by the axle fixing mechanism.
The alarm 40 is caused to sound. The above-mentioned ringing reference value G5 or more means that the horizontal G
(Gs). The area A2 indicates an area where running becomes unstable even if the rear axle 10 is locked by the axle fixing mechanism. The vertical axis represents the vehicle speed V, and the horizontal axis represents the tire angle θ. A region B2 indicates a region where running is stable when the rear axle 10 is locked by the axle fixing mechanism. A region C2 indicates a region where traveling is stable without locking the rear axle 10 by the axle fixing mechanism.

The ringing reference values G3, G4, G5 correspond to the reference values of the present invention. If any of the above sound conditions (a) to (d) is satisfied, step 200 is executed.
Then, in step 200, a sound signal of the alarm device 40 is output, the alarm device 40 is sounded, and this flowchart is temporarily ended. If it is determined in step 190 that none of the sounding conditions is satisfied, the flowchart is temporarily terminated. The sound signal corresponds to the lateral G countermeasure signal of the present invention.

As described above in detail, according to the present embodiment,
The following effects can be obtained. (A) When the rear axle 10 is locked, the side G (Gs
If the sound condition is satisfied, the alarm 40 is sounded. Generally, when skidding occurs, the rear wheel 1
After 1 was removed by steering, the vehicle slipped,
There is a time delay before the direction of the vehicle changes. In the present embodiment, the lateral G (Gs) is determined by the vehicle speed V and the tire angle θ.
), The lateral G at that time is not detected, but the lateral G that will be added to the future that occurs thereafter is estimated. Therefore, in the above flowchart, step 2
At 00, a warning is issued by sounding before the lateral G actually occurs.

For this reason, the driver operating the vehicle is informed
A warning can be given in advance, and attention can be given to the operation of the vehicle thereafter. (B) Since the lateral G change rate η, which is a change in the rise of the lateral G, is employed as one of the determination values for determining whether or not the rear axle 10 should be locked, the rear axle 10 can be quickly locked at the start of a turn, and can be turned back. At times, the rear axle 10 can be held in a locked state to ensure the stability of the vehicle body.

(C) Since the lateral G change rate η having V ² as a factor is employed, it is possible to reduce unnecessary lock at the time of low-speed running which becomes a problem when the yaw rate change rate Y is employed. For example, when the vehicle is traveling on an uneven road surface with the vehicle center of gravity being on the rear wheel 11 side, the occurrence of the problem that the front wheel 7 slips because the rear axle 10 is locked can be reduced as much as possible.

(D) Since the respective determination values η and Gs used for determining whether or not to lock are calculated by calculation using the detected values of the tire angle θ and the vehicle speed V,
There is no need to provide a detector such as an acceleration sensor capable of directly detecting the lateral G. In particular, a tire angle sensor 21 and a vehicle speed sensor 22 provided for other controls and the like in the forklift 1
Can be used for swing control, and the cost of the apparatus can be relatively reduced by sharing sensors.

(E) Set values (G1, G2) for determining whether to lock based on the lateral G (Gs) are set in accordance with the load w and the lift H in consideration of the change in the center of gravity of the vehicle. Therefore, useless locking when the center of gravity of the vehicle is low can be relatively reduced.

(F) Set values of horizontal G (Gs) (G1, G
2) is not separately changed in accordance with the load w and the lift H, but is separately set in two regions bounded by predetermined set values w o and ho. It's easy.

(G) In a configuration in which the lateral G is directly detected by the acceleration sensor, it is often thought that the detected lateral G value may be directly subjected to differential (differential) processing to obtain the lateral G change rate η.
The detection value of the acceleration sensor is easily affected by vibration of the vehicle body and the like, and noise due to vibration and the like is mixed in the detection value. Therefore, when the difference (differential) processing is performed on the lateral G value, the noise is amplified, and the obtained estimated value η becomes a value with low reliability. On the other hand, according to the present embodiment, when calculating the η value, a method is used in which the 1 / r value obtained from the detection value θ of the tire angle sensor 21 that is hardly affected by vibration of the machine base or the like is subtracted. Even if the difference (differential) processing is performed on the 1 / r value, which is originally very little affected by noise, an error due to noise amplification hardly occurs, and a highly reliable estimated value η can be obtained.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. In this embodiment, a detecting means for detecting a detection value used for estimating the lateral G (Gs), the lateral G change rate η, and the like is different from the aforementioned embodiment.

As shown in FIG. 13, on a balance weight 43 disposed at the rear of the forklift 1, a gyroscope 41 serving as a yaw rate detecting means and constituting a lateral G estimating means and a running state detecting means is mounted. ing. In this embodiment, a piezoelectric gyroscope including a piezoelectric element is used as the gyroscope 41. For example, other types such as a gas rate gyroscope or an optical gyroscope can be used.

As shown in FIG. 14, the gyroscope 4
1 is an input interface 37 via an AD conversion circuit 42.
And detects the yaw rate (angular velocity) ω (rad / sec) when the forklift 1 turns, and outputs a detected value ω corresponding to the yaw rate to the CPU 31. In the present embodiment, the CPU 31 constitutes a lateral G estimating unit and a determining unit.

In this embodiment, a gyroscope 41 is used instead of the tire angle sensor 21 used in the above embodiment.
Is provided as a detector, and the other configuration has the same configuration as the above-described embodiment. However, RO
M32 stores program data consisting of the flowchart shown in FIG. Also, the lateral G is calculated by the equation Gs = V
The ω and the yaw rate change rate Y are calculated based on the formula Y = Δω / ΔT, and the lateral G change rate η is calculated based on the formula ΔG / ΔT = V · Δω / ΔT (= V · Y).

The control by the CPU 31 is as follows.
First, in step 210, the CPU 31 reads each detected value such as the yaw rate ω, the vehicle speed V, and the load w. In step 220, the yaw rate change rate Y is calculated. CPU
Reference numeral 31 stores yaw rate data for a plurality of times in the past up to a predetermined time ΔT before in a predetermined storage area of the RAM 33, reads the yaw rate data ω1 before the predetermined time ΔT, and uses the old detection value ω1 and the current detection value ω. , Yaw rate change rate Y
= Δω / ΔT (where Δω / ΔT = | ω−ω1 |). In the next step 230, the lateral G change rate η = V · Y (= V · Δω / ΔT) is calculated. And
In step 240, the horizontal G is calculated as Gs = V · ω. Subsequently, the process proceeds from step 240 to step 50.

The processing from the next step 50 onward is the same as that of the first embodiment, so that the following description will be omitted. According to this embodiment, in calculating η and Y, a method is used in which the detection value ω of the gyroscope 41 that is hardly affected by vibration of the machine base or the like is adopted. Even if the difference (differential) processing is performed, a significant error due to noise amplification does not occur, and highly reliable estimated values η and Y can be obtained.

The present invention is not limited to the above embodiments, but may be modified as appropriate without departing from the gist of the invention, for example, as follows. (1) In the first embodiment in which the lateral G change rate η is always used regardless of the speed range of the vehicle speed, a configuration is adopted in which the vehicle speed sensor 22 and the gyroscope 41 used in the second embodiment are combined as detectors. You may. That is, using the detected value ω of the gyroscope 41 and the vehicle speed V, the lateral G change rate η
= V · Δω / ΔT, lateral G; Gs = V · ω is calculated. With this configuration, the same effect as in the first embodiment can be obtained. That is, the effect of preventing the delay of the rear axle lock at the start of turning, the effect of maintaining the rear axle lock at the time of switching operation, and the lateral G change rate η having the vehicle speed V as a factor.
By using (= V · Δω / ΔT), an effect of avoiding unnecessary lock can be obtained.

(2) In the first embodiment, the lateral G is detected by the acceleration sensor, and the lateral G change rate η is calculated by η = ΔG / ΔT by time-difference of the detection value of the acceleration sensor, and the swing control is performed. The configuration may be made based on the lateral G and η. Also with this configuration, it is possible to prevent delay in regulation of the axle swing at the start of turning, and to maintain the axle in the swing regulation state during switching of the steering wheel. In this case, η can be set to an appropriate set value common to the level of the vehicle speed. Therefore,
Useless locking of the rear axle in the low speed range can be reduced.

(3) The detection value used for calculating the judgment value is not limited to the above embodiments. For example, instead of the tire angle sensor 21, a steering wheel angle sensor for detecting the rotation angle of the steering wheel 12 is used, and the reciprocal value 1 / r of the turning radius is obtained from the steering wheel angle θH, so that each determination value Gs,
A method of calculating η and Y may be adopted. (4) The lateral G is detected by the acceleration sensor, and the lateral G change rate η or the yaw rate change rate Y is calculated from each detected value from the tire angle sensor and the vehicle speed sensor or from each detected value from the yaw rate detector and the vehicle speed sensor. May be adopted. According to this configuration, when the detection value of the acceleration sensor is subjected to the difference (differential) processing, the reliability of the determination value (η, Y) obtained by amplifying the noise becomes poor. Since a detection value from a detector that is difficult to pick up noise is subjected to difference processing, a highly reliable determination value can be obtained.

(5) Noise removal processing such as applying a low-pass filter to the detection value from each sensor or the judgment value calculated using the detection value may be performed. (6) The method of detecting the tire angle θ is not limited to the method of detecting the amount of rotation of the king pin 20. For example, a detector that detects the position of a piston of a steering cylinder included in the power steering device may be employed as the tire angle sensor.

(7) The types of detectors (detection means) for detecting each detection value used for calculating the determination value are not limited to two types. For example, the determination value may be estimated using each detection value obtained from three or more detectors having different detection targets.

(8) The regulation of the swing of the axle is not limited to the lock for completely fixing the axle. The regulation may be such that the swing range becomes narrower in the regulated state of the axle.
The effects of the present invention can be obtained if the swing range is reduced during the regulation of the axle.

(9) The present invention may be applied to a battery type forklift. Further, the present invention may be applied to industrial vehicles other than forklifts. (10) In each of the above embodiments, the sound signal for driving the alarm device 40 is used as the lateral G countermeasure signal, but the engine speed may be reduced. That is, for example,
In the first embodiment, instead of the sounding condition being satisfied in step 190, a determination is made on the same condition as in step 190 as a fuel injection amount reduction satisfying condition. When this condition is satisfied, the CPU 31 outputs a first signal as a lateral G countermeasure signal to an engine ECU (electronic control device) (not shown) that controls the engine 9. Based on this input, the engine ECU controls a fuel injection valve (not shown) to reduce the fuel injection amount of the engine 9, and as a result, the engine speed decreases. Therefore, since the vehicle speed decreases, the lateral G applied to the vehicle can be reduced.

In this case, the engine ECU constitutes engine control means. Further, in order to decrease the engine speed, the throttle opening may be reduced. In this case, when the engine ECU inputs a lateral G countermeasure signal, the engine ECU controls an electronic throttle valve driven by a pulse motor or the like in a valve closing direction. As a result, the engine speed decreases.

(11) In the case of the battery type forklift, since the motor is used as a drive source for the wheels (drive wheels), the rotation speed of the motor may be reduced. That is, in this case, unlike the above (10), a lateral G countermeasure signal is input from the CPU 31 to the controller for controlling the motor in order to reduce the motor rotation speed. Then, the controller controls the motor drive circuit so as to reduce the control voltage applied to the motor. As a result,
Since the rotation speed of the motor decreases and the vehicle speed decreases, the lateral G applied to the vehicle can be reduced.

In this case, the controller constitutes a motor control means. The technical ideas (inventions) grasped from the above embodiments and not described in the claims are listed below together with their effects.

(A) The industrial vehicle is an engine-equipped vehicle and has an engine control means for controlling the engine. A lateral G countermeasure signal is input to the engine control means. The control device for an industrial vehicle according to any one of claims 1 to 5, wherein the control device controls the engine speed to decrease based on the engine speed. With this configuration, since the vehicle speed is reduced, it is possible to prevent the vehicle from being in an unstable posture.

In this case, the engine-equipped forklift (10) is an engine-equipped vehicle, and the engine ECU that controls the engine that is the driving source of the drive wheels constitutes the engine control means.

(B) The industrial vehicle is a battery-equipped vehicle and has motor control means for a motor for driving the driving wheels. A lateral G countermeasure signal is input to the motor control means. 6. An engine speed reduction control based on a signal.
The control device for an industrial vehicle according to any one of the above. With this configuration, since the vehicle speed is reduced, it is possible to prevent the vehicle from being in an unstable posture.

In this case, the battery type forklift (11) is a vehicle equipped with a battery, and a controller for controlling a motor which is a driving source of driving wheels constitutes a motor control means.

(C) Claims 1 to 5 and (a)
The invention according to any one of (b) and (b), further comprising a center-of-gravity height measuring means for measuring the height of the center of gravity of the vehicle, and The set value is determined. According to this configuration, the set value of the lateral G changes according to the height of the center of gravity of the vehicle measured by the center-of-gravity height measuring means, so that unnecessary regulation of axle swing can be reduced. The center-of-gravity height measuring means includes the lift sensor 23 and the pressure sensor 24 in each of the above embodiments.
And a CPU 31.

[0085]

As described above in detail, according to the first aspect of the present invention, the posture of the vehicle is unstable for the driver or the like so that the turning operation of the industrial vehicle is performed in a stable state. If so, the response can be possible.

According to the second aspect of the present invention, since the lateral G estimating means can estimate the lateral G to be added to the industrial vehicle in the future, the posture of the vehicle is unstable to the driver or the like as soon as possible. Can be expected, and the response can be made quickly.

According to the third aspect of the present invention, the lateral G is estimated by using the detection values of the two different detecting means provided on the vehicle and different from each other, so that the acceleration for directly detecting the lateral G can be obtained. The required lateral G can be obtained without providing a detector.

According to the invention described in claim 4, the yaw rate detecting means detects the detection of the yaw rate applied to the industrial vehicle, and the lateral G estimating means detects the yaw rate based on the yaw rate detected by the yaw rate detecting means. Thus, the lateral G currently added can be estimated.

According to the fifth aspect of the present invention, the warning means inputs the lateral G countermeasure signal and issues a warning based on the lateral G countermeasure signal, so that the driver can continue the current driving state. Then, it can be known that the vehicle becomes unstable.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a forklift body swing control device according to a first embodiment.

FIG. 2 is a schematic diagram showing an axle fixing mechanism.

FIG. 3 is a side view of the forklift.

FIG. 4 is a block diagram showing an electric configuration of the vehicle body swing control device.

FIG. 5 is a graph showing a change in a lateral G and a lateral G change rate during turning.

FIG. 6 is a map diagram showing a horizontal G lock region with respect to load and lift.

FIG. 7 is a flowchart of a swing control process.

FIG. 8 is also a flowchart.

FIG. 9 is also a flowchart.

FIG. 10 is an explanatory diagram for showing a horizontal G ringing condition.

FIG. 11 is an explanatory diagram for showing a horizontal G ringing condition.

FIG. 12 is an explanatory diagram for showing a horizontal G ringing condition.

FIG. 13 is a plan view of a forklift according to a third embodiment.

FIG. 14 is a block diagram showing an electrical configuration of the vehicle body swing control device.

FIG. 15 is a flowchart of a part of a swing control process.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Forklift as an industrial vehicle, 1a ... Body frame, 10 ... Rear axle as an axle, 13 ... Hydraulic damper which comprises an axle fixing mechanism, 14 ... Electromagnetic switching valve which comprises an axle fixing mechanism and as a switching valve, 21: a tire angle sensor as a lateral G estimating means and a steering angle detecting means; 22: a vehicle speed sensor as a lateral G estimating means and a vehicle speed detecting means; 23: a lift sensor constituting a center of gravity height measuring means;
24: a pressure sensor constituting the center of gravity height measuring means; 25, a controller as a control means; 31: a CPU constituting the lateral G estimating means, the yaw rate change measuring means, and the center of gravity height measuring means, and 40, a warning means. , A gyroscope as yaw rate detecting means, Gs... Lateral G, η... Lateral G change rate, Y.
Yaw rate change rate.

Claims (5)

[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 traveling state detecting means for detecting a traveling state of the industrial vehicle, and a lateral for estimating a lateral G applied to the industrial vehicle based on a detection result of the traveling state detecting means. And a lateral G countermeasure signal when the lateral G estimated by the lateral G estimating means becomes larger than a reference value while the axle fixing mechanism fixes the axle to the body frame. A vehicle body swing control device for an industrial vehicle, comprising: 2. The vehicle body swing control device for an industrial vehicle according to claim 1, wherein the lateral G estimating means estimates a lateral G to be added to the industrial vehicle in the future. 3. The traveling state detecting means includes a vehicle speed detecting means for detecting a vehicle speed of the industrial vehicle, and a steering angle detecting means for detecting a steering angle of the industrial vehicle. The vehicle body swing control device for an industrial vehicle according to claim 2, wherein the estimation is performed based on the angle. 4. The running state detecting means is a yaw rate detecting means for detecting a yaw rate applied to the industrial vehicle, and the lateral G estimating means is configured to detect a yaw rate of the industrial vehicle based on the yaw rate detected by the yaw rate detecting means. The vehicle body swing control device for an industrial vehicle according to claim 1, wherein the added lateral G is estimated. 5. The apparatus according to claim 1, further comprising a warning unit that inputs the lateral G countermeasure signal and issues a warning based on the lateral G countermeasure signal. Body swing control device for industrial vehicles.