JPH10297236A - Vehicle body oscillation controller of industrial vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the regulation of oscillation of an axle if a running condition and a cargo loading condition are clearly such conditions that do not cause a trouble even if the axle is oscillated when a detector causes a failure. SOLUTION: A rear axle 10 which supports a rear wheel 11 is attached in such a manner that it can vertically oscillate for a vehicle body centered on a center pin 10a. A controller 29 detects a running condition based on the values θ, V detected by sensors 21, 22 and detects a cargo loading and unloading condition based on the values H, w detected by sensors 27, 28. When the judged values (horizontal G, etc.) obtained from the detected values θ, V exceed the set values determined in accordance with the detected values H, w an electromagnetic change-over valve 14 of a damper 13 is changed over to lock the rear axle 10. When it is diagnosed that the sensors 21, 22, 27, 28 cause failures, the maximum values θmax, Vmax, etc., which are the severest values as the detected values are set. Therefore, even if one sensor which forms a set causes a failure, the rear axle 10 is not locked as far as a vehicle runs in such a manner that a value detected by the other sensor makes the judged value less than the set value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial vehicle body swing control device for controlling an axle swingably provided on an industrial vehicle body in accordance with a traveling state or a cargo handling state. is there.

[0002]

2. Description of the Related Art Conventionally, in an industrial vehicle such as a forklift, an axle supporting a rear wheel is swingably attached to a vehicle body in order to stabilize the vehicle during traveling. When the forklift turns, the vehicle body is tilted by receiving a lateral force due to the centrifugal force, so that running stability may be reduced.

Japanese Patent Laid-Open Publication No. Sho 58-211903 discloses a forklift provided with a turning detecting means for detecting a centrifugal force. When the centrifugal force acting on the vehicle exceeds a predetermined value, the axle is fixed by an axle fixing mechanism. Techniques are disclosed. In this forklift, since the axle is fixed, the inclination of the vehicle body at the time of turning can be suppressed small, and the turning can be performed in a stable posture.

Japanese Patent Application Laid-Open No. 58-167215 discloses load detecting means for detecting that the load of a load on a fork has exceeded a predetermined weight, and detecting that the fork has risen to a predetermined height or higher. There is disclosed a technique for fixing an axle when a heavy load and a high lift that both detection means are in a detection state are provided.

Further, the applicant of the present application estimates the lateral acceleration (lateral G) acting on the vehicle by calculation from the tire angle and the vehicle speed of the steered wheels detected by the sensor, and fixes the axle when the lateral G exceeds a set value. (Japanese Patent Application No. 8-149560).

By the way, when the axle is left in a swingable state when the detector fails, it becomes difficult to secure running stability during turning, heavy load and high elevation. Therefore, in general, when the detector fails, it is desirable to forcibly restrict axle swing on the safe side.

[0007]

However, if the axle is held in a fixed state at the time of a failure of the detector, the vehicle weight on the rear wheel side due to empty load or the like when traveling on an uneven road surface. In such a case, two rear wheels may touch the road surface, and one side of the front wheels, which are drive wheels, may be lifted off the road surface, so that sufficient contact pressure of the drive wheels may not be ensured. In this case, the driving wheels may slip, and in the worst case, they may not be able to move and may get stuck.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a first object of the present invention is to provide an axle which can be used when the detector is out of order or the axle can be swung. The present invention is to provide a vehicle body swing control device for an industrial vehicle, which is capable of holding a vehicle in a swingable state and minimizing occurrence of troubles such as slipping of drive wheels. Also,
The second object is to determine whether the determination value satisfies a predetermined condition by performing axle regulation control only by looking at the detection value of the non-failed detector for obtaining the determination value. Is unnecessary. A third object is to ensure as wide a range as possible to keep the axle swingable when the detector fails. A fourth object of the present invention is to maintain the axle in a swingable state in a running state in which the detector may fail or the axle may be swung. A fifth object of the present invention is to maintain the axle in a swingable state when the detector is out of order or when the vehicle is in a running / loading state where the axle can be obviously swung. A sixth object of the present invention is to make the axle swingable in a cargo handling state in which the detector may be out of order or the axle can be swung clearly.

[0009]

In order to achieve the first object, according to the first aspect of the present invention, an axle supported to be vertically swingable with respect to a vehicle body, and a swing of the axle is provided. An axle regulating mechanism for regulating, a plurality of detectors for detecting at least one of a traveling state and a cargo handling state of the vehicle, and a determination value determined from detection values of at least two of the plurality of detectors When a predetermined condition is satisfied, the control unit includes a control unit that activates the axle control mechanism, and a failure diagnosis unit that diagnoses a failure of at least one of the detectors. In the state where the detector has been diagnosed as having a failure, it is assumed that the detection value of the detector diagnosed as having a failure has a value that most easily satisfies the predetermined condition within the detection range of the detector when the detector is normal. Axle regulations When the operation of the structure is found to be unnecessary it is set so as not to actuate the axle restricting mechanism.

According to a second aspect of the present invention, in the first aspect of the present invention, the control means sets the detected value of the detector diagnosed as faulty by the fault diagnosing means within a normal detection range. At least, when the detection value of the other detector for obtaining the determination value takes a value of a certain area within the detection range, the determination value is at least equal to or more than a value that most easily satisfies the predetermined condition. There is provided a detection value setting means for setting a predetermined value that does not satisfy the predetermined condition.

According to a third aspect of the present invention, in order to achieve the second object, the control means according to the first aspect of the present invention further comprises: a control unit for obtaining the determination value which is not the side diagnosed as having a failure. When the detection value of the detector assumes that the detection value of the detector diagnosed as a failure has a value that most easily satisfies the predetermined condition within the normal detection range, the determination value is When the value is within a predetermined range in which the predetermined condition is not satisfied, the gist is that the axle restriction mechanism is not operated.

According to a fourth aspect of the present invention, in order to achieve the third object, the predetermined value set by the detection value setting means is the detector which has been diagnosed as having failed. Is a value that makes the determination value most easily satisfy the predetermined condition within the normal detection range.

According to a fifth aspect of the present invention, in order to achieve a fourth object, in the second aspect of the present invention, the plurality of detectors include a vehicle side G and a vehicle yaw rate change rate as determination values. A first detector for detecting a detection value necessary to obtain at least one of the first detectors, wherein the control means is configured to control a lateral G or yaw rate change rate obtained from the detection values of the plurality of first detectors. When the predetermined condition that is equal to or more than the set value is satisfied, the axle restricting mechanism is set to operate, and the detection value setting unit diagnoses a failure by the failure diagnosis unit among the plurality of first detectors. As the detected value of the detector, the predetermined value which is the value that can maximize the lateral G or the yaw rate change rate within the normal detection range is set.

According to a sixth aspect of the present invention, in the fifth aspect of the invention, the plurality of first detectors include a steering angle detector for detecting a steering angle of a steered wheel, and a vehicle speed detection for detecting a vehicle speed. It consists of a container.

According to a seventh aspect of the present invention, in the fifth aspect of the invention, the plurality of first detectors include a yaw rate detector for detecting a yaw rate of the vehicle, and a vehicle speed detector for detecting a vehicle speed. Consists of

In order to achieve the fifth object, in the invention described in claim 8, in the invention described in any one of claims 5 to 7, a plurality of first detections for obtaining the lateral G are provided. A plurality of second detectors necessary for detecting the height of the center of gravity of the vehicle, in addition to the detector, wherein the control means determines that the lateral G is the height of the center of gravity of the vehicle detected from the plurality of second detectors It is set to operate the axle control mechanism when the predetermined condition is satisfied when the value becomes equal to or more than a set value determined according to the detected value, and the detection value setting unit is configured to detect the second value of the plurality of second detectors. As the detection value of the detector diagnosed as having a failure by the failure diagnosing means, the predetermined value which is a value which can make the height of the center of gravity of the vehicle highest within the normal detection range is set.

According to a ninth aspect of the present invention, in order to achieve a sixth object, in the second aspect of the present invention, the plurality of detectors determine the height of the center of gravity of the vehicle determined from the cargo handling state of the vehicle. A plurality of second detectors for detecting as a value, the control means, when satisfying the predetermined condition that the height of the center of gravity of the vehicle detected from the plurality of second detectors is equal to or more than a set value, The detection value setting means is set to operate the axle regulation mechanism, and the detection value setting means detects a failure of the second detector diagnosed by the failure diagnosis means as:
The predetermined value, which is a value that can maximize the height of the center of gravity of the vehicle within the normal detection range, is set.

According to a tenth aspect of the present invention, in the eighth or ninth aspect, the plurality of second detectors necessary for detecting the height of the center of gravity of the vehicle load a load. For this purpose, the apparatus comprises a height detector for detecting the height of the loading equipment provided in the vehicle, and a load detector for detecting the load of the load on the loading equipment.

According to the eleventh aspect of the present invention, in the first aspect,
11. The invention according to claim 10, wherein the failure diagnosis means detects the failure when a detection value of a detector to be a failure diagnosis continuously satisfies a preset failure condition for a predetermined time or more. Diagnose that the device has failed.

According to the first aspect of the present invention, when the judgment value obtained from at least two of the plurality of detectors satisfies a predetermined condition, the control means activates the axle regulating mechanism. Operates to regulate the axle swing. When the detector is diagnosed as having failed by the failure diagnosing means, the control means takes a value which makes it easier for the detected value of the failed detector to satisfy the predetermined value within the normal detection range. If it is assumed that the operation of the axle control mechanism is not required, the axle control mechanism is not operated at a predetermined time when it is recognized that the operation of the axle control mechanism is not necessary. Therefore, even if the detector breaks down, the axle swing is reliably regulated when the axle swing should be regulated, and the axle swing is not regulated when the axle can be obviously swung. become.

According to the second aspect of the present invention, when the failure is diagnosed by the failure diagnosing means, the detection value of the detector diagnosed as a failure is determined within the normal detection range. Is more severe than the value that most easily satisfies the predetermined condition, and at least when the detection value of another detector for obtaining the determination value takes a value of a certain area within the detection range. A predetermined value at which the determination value does not satisfy the predetermined condition is set by the detection value setting means. Therefore, when the detected value of the non-failed detector for obtaining the determination value takes a value within a certain area, at least the swing of the axle is not restricted.

According to the third aspect of the present invention, when the detector is diagnosed as having failed by the failure diagnosing means, the control means:
When the detection value of the other detector for obtaining the determination value not on the side where the failure has been diagnosed is a value within a predetermined range, the axle regulating mechanism is not operated. The predetermined range is such that the determination value satisfies the predetermined condition when it is assumed that the detection value of the detector diagnosed as a failure has a value that makes the determination value most easily satisfy the predetermined condition within the normal detection range. It is set as the range that disappears. Therefore, even if the detector fails, the swing of the axle is not restricted when the axle can be swung clearly only by checking the detection values of the other detectors that have not failed. Therefore, various calculations for determining whether or not the determination value satisfies the predetermined condition become unnecessary.

According to the fourth aspect of the present invention, when the detector is diagnosed as having failed by the failure diagnosing means, the detected value is set as the detected value of the detector diagnosed as having failed by the detected value setting means. Are set so as to make the determination value most easily satisfy the predetermined condition within the detection range of. Therefore, the range in which the axle swing is not restricted when the detector fails is as large as possible.

According to the fifth aspect of the present invention, when the lateral G or yaw rate change rate of the vehicle obtained from the detection values of the plurality of first detectors exceeds a set value, the control means activates the axle regulating mechanism. As a result, swinging of the axle is regulated. When any one of the plurality of first detectors is diagnosed as a failure by the failure diagnosing means, the detected value of the failed first detector is the lateral G or yaw rate change rate within the normal detection range. A value that can be increased is set by the detection value setting means. Therefore, even if one of the first detectors fails, the axle swing is reliably regulated when the axle swing is to be regulated. The swing of the axle will not be regulated.

According to the invention described in claim 6, the lateral G and yaw rate change rates of the vehicle are determined based on the steering angle of the steered wheel detected by the steering angle detector and the vehicle speed detected by the vehicle speed detector. At least one is calculated. If any of the steering angle detector and the vehicle speed detector is diagnosed as having failed by the failure diagnosing means, the detected value of the failed detector has the largest lateral G or yaw rate change rate within the normal detection range. Possible values are set by the detection value setting means. Therefore, even if one of the steering angle detector and the vehicle speed detector fails, the axle swing is regulated when the axle swing is to be regulated, and the running state in which the axle can be obviously swung is acceptable. In this case, the swing of the axle is not restricted.

According to the present invention, the lateral G of the vehicle is calculated from the yaw rate of the vehicle detected by the yaw rate detector and the vehicle speed detected by the vehicle speed detector. When either the yaw rate detector or the vehicle speed detector is diagnosed as a failure by the failure diagnosis means, a value that can maximize the lateral G within the normal detection range is detected as the detection value of the failed detector. It is set by the value setting means.
Therefore, even if one of the yaw rate detector and the vehicle speed detector fails, the axle swing is regulated when the axle swing is to be regulated, and the running state in which the axle can be obviously swung is not a problem. Sometimes the axle swing is not regulated.

According to the present invention, the lateral G obtained from the detected values of the plurality of first detectors is determined from the detected values of the plurality of second detectors in accordance with the height of the center of gravity of the vehicle. If the set value is exceeded, the control means activates the axle restricting mechanism to restrict the axle from swinging. When the second detector is diagnosed with a failure by the failure diagnosis means, a value which can make the height of the center of gravity of the vehicle highest within the normal detection range is detected as the detected value of the failed second detector. It is set by the setting means. Therefore, even if any of the second detectors fails, the oscillation of the axle is restricted when the oscillation of the axle is to be restricted. The swing of the axle will not be regulated.

According to the ninth aspect, the height of the center of gravity of the vehicle according to the cargo handling state is detected by the plurality of second detectors. When the height of the center of gravity of the vehicle becomes equal to or more than the set value, the axle regulating mechanism is operated by the control means to regulate the swing of the axle. When any one of the plurality of second detectors is diagnosed as having a failure by the failure diagnosis means, the height of the center of gravity of the vehicle within the normal detection range is determined as the detection value of the failed second detector. The predetermined value that can be the highest is set by the detection value setting means. Therefore, even if the second detector for detecting the cargo handling state fails, the swinging of the axle is regulated when the swinging of the axle is to be regulated. In this case, the swing of the axle is not restricted.

According to the tenth aspect of the invention, the lift of the loading equipment is detected by the lift detector, and the load of the load on the loading equipment is detected by the load detector. When the height detector or the load detector is diagnosed as a failure by the failure diagnosis means, a value which can make the height of the center of gravity of the vehicle the highest within the normal detection range as a detection value of the failed detector ( That is, the value corresponding to the maximum lift or the maximum load) is set by the detection value setting means. Therefore, even if either the height detector or the load detector fails, the axle swing is reliably regulated when the axle swing is to be regulated, and the axle can obviously swing. Sometimes the axle swing is not regulated.

According to the eleventh aspect of the present invention, the failure diagnosing means determines that the detection value of the detector to be diagnosed satisfies a predetermined failure condition continuously for a predetermined time or more. Diagnose the detector for failure. for that reason,
Even if the detected value satisfies the failure condition for an extremely short period of time in spite of being normal for some reason, it is not diagnosed as a failure.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS.

The forklift 1 as an industrial vehicle in this embodiment shown in FIGS. 1 and 3 is a four-wheeled vehicle driven by front wheels and steered by rear wheels. As shown in FIG.
An inner mast 2b is disposed between a pair of left and right outer masts 2a erected at the front of the machine base so that the inner mast 2b can move up and down. A fork 3 as a loading device is connected to the chain 4 (shown in FIG. 1). It is suspended so that it can go up and down. The outer mast 2a is a body frame 1 as a body.
The tilt cylinder 5 is connected via a tilt cylinder 5 so that the piston rod 5a of the tilt cylinder 5 is tilted by being driven to expand and contract. The piston rod 6a of the lift cylinder 6 provided on the rear surface of the outer mast 2a is connected to the upper end of the inner mast 2b. The piston rod 6a of the lift cylinder 6 is driven to expand and contract, so that the fork 3 moves up and down. Has become. Left and right front wheels 7 are connected to an engine 9 (FIG. 3) via a differential ring gear 8 (shown in FIG. 1) and a transmission (not shown).
).

As shown in FIG. 1 and FIG.
A rear axle 10 as an axle is supported at the rear lower part of the rear part a so as to be vertically swingable (rotatable) around a center pin 10a while extending in the vehicle width direction. The left and right rear wheels 11 as the steered wheels are steerably connected at respective distal ends of a pair of left and right piston rods of a steering cylinder disposed on the rear axle 10 via a link mechanism (both 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 the expansion and contraction of a piston rod of a steering cylinder driven based on the operation of a steering wheel 12.

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

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 (reservoir) 17 for storing hydraulic oil is connected via a check valve 18 via a pipe P3.

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. Further, a throttle valve 19 is provided on the path of the second pipeline P2. The axle regulating 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 (right side) of the king pin 20 that rotatably supports the rear wheel 11, the amount of rotation of the king pin 20 is detected, and the steering angle (the tire Angle), a first detector, and a tire angle sensor 21 as a steering angle detector. The tire angle sensor 21 includes, for example, a potentiometer and outputs a detection value (voltage value) θ corresponding to the tire angle.

As shown in FIG. 1, the rotation of the differential ring gear 8 is detected so that the forklift 1
A first speed detector and a vehicle speed sensor 22 as a vehicle speed detector. Vehicle speed sensor 2
2 is an output shaft 8a of the differential ring gear 8 as shown in FIG.
Are arranged at predetermined positions facing the convex portions 8b made of a magnetic material, which are protruded from the outer peripheral surface at a regular interval. The vehicle speed sensor 22 is, for example, an inductive sensor, and outputs an analog signal SA which is a sine wave having a frequency corresponding to the number of the convex portions 8b passing through the detection area per unit time (that is, according to the vehicle speed). .

The steering shaft 12a supporting the handle 12 is provided with a rotary encoder 23 for detecting a handle angle. The rotary encoder 23 is provided with a disk 24 provided so as to be integrally rotatable with the steering shaft 12a, and a disk capable of detecting light passing through a large number of slits 24a formed at equal intervals in the circumferential direction in order to detect the rotation of the disk 24. And a handle angle sensor 25 provided with a plurality of sets of photocouplers arranged at predetermined positions with respect to the handle 24. Handle angle sensor 25
Outputs a pulse signal h corresponding to the rotation of the handle 12 detected by the phototransistor constituting the photocoupler.

Further, as shown in FIG.
A reel 26 wound around a wire (not shown) connecting one end to a lift bracket 3a on which the fork 3 is mounted is urged in the winding direction near the lower portion of the fork 3. . The reel 26 is provided with a detector capable of detecting its rotation, a second detector, and a rotation detecting type lift sensor 27 as a lift detector. The lift sensor 27 detects the winding amount of the wire from the rotation of the reel 26,
The lift of the fork 3 is continuously detected, and a detection value H corresponding to the lift is output.

The lift cylinder 6 is provided with a detector for detecting the oil pressure in the cylinder, a second detector, and a pressure sensor 28 as a load detector. The pressure sensor 28 outputs a detection value w according to the load of the load loaded on the fork 3. As shown in FIG. 1, a controller 29 as a control means includes a solenoid 14a provided in the electromagnetic switching valve 14 and sensors 21, 22, 25,
27 and 28 are electrically connected.

Next, the electrical configuration of the forklift 1 will be described with reference to FIG. The controller 29 includes a microcomputer 30, AD conversion circuits 31 to 34, a pulse generation circuit 32a, an excitation / demagnetization drive circuit 35, and the like. The microcomputer 30 includes a CPU (central processing unit) 3 as a failure diagnosis unit and a detection value setting unit.
6, ROM (read only memory) 37, RAM (read / write memory) 38, clock circuit 39, steering counter 4
0, error counters 41 to 44, input interface 4
6 and an output interface 47.

The CPU 36 includes A / D conversion circuits 31 and 3
The detection values θ, H, and w from the sensors 21, 27, and 28 are input via the sensors 3 and 34, and the pulse signal h from the steering wheel angle sensor 25 is input. Further CPU
36, a pulse signal Sp having a frequency corresponding to the vehicle speed from the pulse generation circuit 32a and a signal S from the A / D conversion circuit 32.
A detection voltage D obtained by digitizing A is input.

The analog signal SA output from the vehicle speed sensor 22 is, for example, as shown in FIG.
A sinusoidal wave having a frequency proportional to the vehicle speed and an amplitude value corresponding to the vehicle speed is drawn around the center voltage Dc in the range of ".about.E". When the vehicle speed exceeds a certain speed, the amplitude of the detection voltage D exceeds the detection voltage range. When the vehicle stops running, the signal SA becomes constant at the center voltage Dc. The pulse generation circuit 32a outputs an H level when the analog signal SA is equal to or higher than the reference voltage Dp, and outputs an L level when the analog signal SA is lower than the reference voltage Dp, thereby providing a pulse signal having a pulse (rectangular wave) having a frequency proportional to the vehicle speed. Generate Sp. The CPU 36 obtains a value V corresponding to the vehicle speed by counting the number of pulses per unit time of the pulse signal Sp input from the pulse generation circuit 36a. The detection voltage D is used for a failure diagnosis of the vehicle speed sensor 22 described later. The detected values θ, H, w, and D are stored in the CPU 36 as A
It is input as a D value (for example, an 8-bit value).

The solenoid 14a is excited / demagnetized based on a control command signal output from the CPU 36 to the excitation / demagnetization drive circuit 35. The electromagnetic switching valve 14 is energized when a lock release command is output from the CPU 36 and the spool is arranged at the communication position, and is demagnetized when the lock signal is not output from the CPU 36 and the spool is moved to the shut-off position. Be placed.

The ROM 37 stores various program data including the swing control processing program data shown in the flowcharts of FIGS. 11 and 12, and the sensor failure diagnosis processing program data shown in FIGS. Here, the swing control refers to the state of the rear axle 10 at a predetermined time when it is determined that running instability is likely to occur based on the result of detection of the running state and cargo handling state of the vehicle.
Is controlled to minimize the lateral inclination of the vehicle body as much as possible.

In the present embodiment, the lateral G acting on the vehicle (the centrifugal acceleration acting in the lateral direction of the vehicle when turning) Gs
A change rate (yaw rate change rate) ΔY / ΔT of the yaw rate (angular velocity at the time of turning) Y of the vehicle body with respect to time is detected over time as the determination value, and the load w of the load loaded on the fork 3 and the fork 3 are detected. 3 is detected over time as the cargo handling state. In other words, the height of the center of gravity of the vehicle is detected from the load w and the lift H. As a predetermined condition, the rear axle 10 is set to be locked when any one of the values Gs and ΔY / ΔT is equal to or more than each set value set in advance. Here, the horizontal G (Gs)
Is set so that the value gradually decreases as the center of gravity of the vehicle increases according to the cargo handling state. In the present embodiment, as shown in FIGS. 8A and 8B,
The set values “0”, “G1”, and “G2” are set according to the combination of the value of the load w and the height H, that is, the height of the center of gravity of the vehicle.

That is, when the load w is lighter than the set value wo, as shown in FIG.
o (for example, Ho is less than 1/2 of the maximum lift Hmax), "G2" when the lift H is higher than a predetermined value Ho or more, "G1" (G1 = G2 / 2 in the present embodiment). Are set as the horizontal G setting values. The load w is equal to the set value w.
8B, when the lift H is lower than the predetermined value Ho, “G2” is displayed horizontally, and when the lift H is higher than the predetermined value Ho, “0” is displayed horizontally. G is set as the set value. That is, load w ≧ wo and lift H ≧
The rear axle 10 is set to be always locked when a heavy load and a high lift satisfying Ho are satisfied.

The set value of the yaw rate change rate ΔY / ΔT is set to “yo”. Each set value G1, G2,
yo is a value obtained from a driving experiment or theoretical calculation.
0 is set to be locked. Also,
The CPU 36 has two flags Fg and Fy. The flag Fg is set when the horizontal G (Gs) is equal to or greater than the set values G1 and G2 determined according to the cargo handling state at that time, and is cleared when the value is less than the set value. The flag Fy is set when the yaw rate change rate ΔY / ΔT is equal to or greater than the set value yo, and is cleared when the yaw rate change rate is smaller than the set value yo.

The clock circuit 39 outputs a clock signal to the CPU 36. The CPU 36 executes a swing control process and a sensor failure diagnosis process at regular intervals (for example, several tens of milliseconds) based on the clock signal. However, the sensor failure diagnosis processing is executed every time the swing control processing is executed a predetermined number of times.

The steering counter 40 is for counting a count value P corresponding to the steering wheel angle. CPU
Numeral 36 designates the input of two pulse signals h whose phases are shifted by 1/4 wavelength from the steering wheel angle sensor 25. By comparing the correspondence between the two pulse signals h by observing the edges and levels of the two pulse signals h, the steering wheel turning direction is obtained. Is detected. Each time an edge of the pulse signal h is detected, the count value P of the steering counter 40 is decremented when the steering wheel turning direction is leftward, and the count value P is incremented when the steering wheel turning direction is rightward.

The four error counters 41 to 44 count a count value corresponding to a continuation time in which a predetermined failure condition set in advance for each sensor is satisfied at the time of failure diagnosis processing of each of the sensors 21, 22, 27, and 28. It is for counting. The error counters 41 to 44 are incremented by a predetermined time, for example, “10” as a predetermined time, in a failure diagnosis process executed at regular time intervals in a failure diagnosis process. Each time, the count value is decremented in a range where “0” is the minimum value. Here, each sensor 21, 22, 27, 28
Disconnection / short circuit failure is diagnosed for the tire angle sensor 2
As for No. 1, the diagnosis of the dropout failure is also performed. Also, the CPU 36 has four failure flags Fθ,
FD, FH and Fw are provided. Each flag Fθ, FD,
FH and Fw are set when the count values of the corresponding error counters 41 to 44 are "10" and cleared when the count values are "0".

In this embodiment, each of the sensors 21, 22, 2
The short-circuit and disconnection faults of Nos. 7 and 28 are detected by the detected values θ, D, H, and w.
The diagnosis is made by determining whether the value (voltage value) is within the normal detection range. For example, in the case of the tire angle sensor 21, as shown in FIG.
It takes a value in the range of n ≤ θ ≤ θmax.
n holds, and θ> θmax holds when a short circuit occurs. Utilizing this, the input values θ, H, and w from the sensors 21, 27, and 28 are also set to θ <θmin and H <H.
min, if w <wmin holds, a disconnection fault, θ> θmax,
If H> Hmax and w> wmax are satisfied, diagnosis is made as a short-circuit failure. Where θmin, Hmin, wmi
n is a lower limit that can be detected when the sensors 21, 27, 28 are normal, and θmax, Hmax, wmax are
28 is an upper limit value that can be detected in the normal state. Therefore, θ
max indicates the detected value of the maximum tire angle, Hmax indicates the detected value of the maximum lift, and wmax indicates the detected value of the maximum allowable load.

Further, as shown in FIG.
The voltage value (detection voltage) D of the output signal SA from the center of the vehicle, when the vehicle speed sensor 22 is normal, oscillates around the center voltage Dc so that the frequency and amplitude increase as the vehicle speed increases,
When the vehicle is stopped, the value is constant at the center voltage Dc. Vehicle speed sensor 2
In the case of the failure of No. 2, a constant voltage is output outside the set range A (that is, the range B in FIG. 7) although no pulse wave is emitted. If the vehicle speed is "0", it should be Dc
However, it is determined that there is a failure when it is within the range of B. In other words, when the vehicle speed sensor 22 is disconnected and the power supply is short-circuited, D>
It becomes a constant value at Dmax, and D <
It becomes a constant value at Dmin. For this reason, if the detection value D of the vehicle speed sensor 22 becomes a constant value that satisfies D <Dmin or D> Dmax, it is diagnosed as a disconnection / short circuit failure.

Further, the tire angle sensor 21 in which the rotation of the king pin 20 is not input to the input shaft of the potentiometer.
When a failure occurs, a constant voltage within the normal detection range is input, so that it cannot be found only by monitoring the input value θ. Therefore, in the present embodiment, deviations Δθ and ΔP of the tire angle θ and the steering wheel angle P during a certain period of time ΔT are obtained, and a falling fault condition in which the tire angular speed Δθ becomes “0” despite the positive steering angular speed ΔP. A dropout failure is diagnosed based on whether (ΔP> 0 and Δθ = 0).

In this embodiment, the lateral G (Gs value) and the yaw rate change rate ΔY / ΔT are determined by two sensors 21 and 22.
Is indirectly estimated by calculation using the detected values θ and V of The estimated value Gs of the lateral G is calculated by the following equation (1) using the reciprocal value 1 / r of the turning radius determined from the tire angle θ using a map stored in the ROM 37 in advance.

Gs = V ² / r (1) Further, the yaw rate change rate ΔY / ΔT is calculated by the following equation (2). ΔY / ΔT = V · Δ (1 / r) / ΔT (2) where Δ (1 / r) is a value per a fixed time ΔT (for example, several tens of milliseconds) of a reciprocal value 1 / r of the turning radius. It is a difference. The reciprocal value 1 / r of the turning radius takes a negative value when the tire angle θ is the left turning angle and a positive value when the tire angle θ is the right turning angle. The above equation (2) is obtained by time-differentiating (difference) the yaw rate ω = V / r. ΔY / ΔT = V · Δ (1 / r) / Δ
In the equation of T + ΔV / ΔT · (1 / r), the vehicle speed V during turning of the forklift 1 is regarded as substantially constant (ΔV / ΔT ≒ 0), and the following term is an approximate expression in which the term is ignored.

In this embodiment, the rear axle 10
Is locked, the lock is released only when the determination value serving as the basis of the lock falls below a set value at the time of locking by a predetermined value or more, and the respective detection values w, H, and ΔY are released.
A countermeasure is taken to prevent frequent switching between lock and unlock by taking the value of .DELTA.T by chance near the set values w0, ho, and yo. In the flowcharts of FIGS. 11 and 12, S20 to S50 and S120 to
150 constitutes a detection value setting means. S190-S
240 constitutes control means. 13 and FIG.
The program data for failure diagnosis processing shown in FIG. 4 constitutes failure diagnosis means. Next, the swing control of the forklift 1 and the sensor failure diagnosis processing will be described with reference to FIGS.
This will be described with reference to the flowchart of FIG. While the ignition key is on, the CPU 36 controls the sensors 21, 22,
The detection signals θ, Sp, D, h,
H and w are input. The CPU 36 executes the swing control process at regular intervals (for example, several tens of milliseconds), and executes the sensor failure diagnosis process once each time the swing control process is performed a predetermined number of times. Further, the steering wheel angle P is counted by the CPU 36 in the steering counter 40.

First, the sensor failure diagnosis processing will be described. First, the failure diagnosis processing of the tire angle sensor 21 is shown in FIG.
It will be described according to. The CPU 36 first proceeds to step 310
, The tire angles θ, θ1 and the handle angles P, P1 are read. θ1 and P1 are detected a predetermined time before
8 is the tire angle data and the steering wheel angle data stored in FIG. In step 320, the tire angular velocity Δθ = | θ
−θ1 | is calculated. In step 330, the steering wheel angular velocity ΔP = | P-P1 | is calculated.

In step 340, it is determined whether or not the disconnection / short circuit fault condition “θ <θmin or θ> θmax” is satisfied. When the input value θ satisfies θmin <θ <θmax, it is diagnosed that the tire angle sensor 21 has not broken or short-circuited, and the routine proceeds to step 350. On the other hand, if the input value θ is θ <
When the failure condition of θmin or θ> θmax is satisfied, the tire angle sensor 21 is diagnosed as a disconnection / short circuit failure, and a failure flag Fθ is set in step 370 (F
θ = 1).

In step 350, it is determined whether or not the falling-out failure condition "tire angular velocity Δθ = 0 and steering wheel angular velocity ΔP> 0” is satisfied. If the falling-out failure condition is not satisfied, the tire angle sensor 21 is diagnosed as not having a falling-out failure, and the failure flag Fθ is cleared in step 360 (F
θ = 0). On the other hand, when the falling failure condition of Δθ = 0 and ΔP> 0 is satisfied, the tire angle sensor 21 is diagnosed as having a falling failure, and a failure flag Fθ is set in step 370.

Next, a failure diagnosis process for the sensors 22, 27 and 28 will be described with reference to FIG. First, in step 410, detection values (detection voltages) D, w, and H are read. In the next step 420, the disconnection / short-circuit failure condition of the vehicle speed sensor 22 "a constant value satisfying D <Dmin or D>Dmax"
Is determined. For example, if the value obtained as the detection value D is D <Dmin or D
If a certain value that satisfies> Dmax is taken, it is determined that the failure condition is satisfied. If the failure condition is not satisfied, it is diagnosed that the vehicle speed sensor 22 is normal, and the failure flag FD is cleared in step 430 (FD = 0). On the other hand, D <Dmin or D> D
If the failure condition that satisfies the predetermined value that satisfies max is satisfied, it is diagnosed that the vehicle speed sensor 22 has a disconnection / short circuit failure, and a failure flag FD is set in step 440 (FD =
1).

In the next step 450, the pressure sensor 28
It is determined whether the failure condition “w <wmin or w> wmax” is satisfied. That is, it is determined whether or not a voltage w, which is impossible under normal conditions, is obtained with any load. If the failure condition is not satisfied, it is diagnosed that the pressure sensor 28 is normal, and the failure flag Fw is cleared in step 460 (Fw = 0). On the other hand, w <wmin or w> wmax
If the failure condition is satisfied, the pressure sensor 28 is diagnosed as having a disconnection / short circuit failure, and a failure flag Fw is set in step 470 (Fw = 1).

In the next step 480, the lift sensor 27
It is determined whether the failure condition “H <Hmin or H> Hmax” is satisfied. That is, it is determined whether or not a voltage H that cannot be obtained in a normal state at any height is taken. When the failure condition is not satisfied, it is diagnosed that the lift sensor 27 is normal, and the failure flag FH is cleared in step 490 (FH = 0). On the other hand, when the failure condition satisfying H <Hmin or H> Hmax is satisfied, the lift sensor 27
It is diagnosed that a short-circuit fault has occurred, and a fault flag FH is set in step 500 (FH = 1).

Accordingly, each sensor 21, 22, 27, 28
Are normal, each failure flag Fθ, FD, FH, F
w are all cleared, and when even one of these sensors fails, a failure flag corresponding to the failed sensor is set. In the present embodiment, the failure flag Fθ,
Instead of setting FD, FH, and Fw, the failure flags Fθ, Fθ, and 始 め are not satisfied until the failure condition is satisfied for a predetermined time (for example, less than 1 second) until the count value of the error counters 41 to 44 reaches “10”. FD, FH and Fw are set. Therefore, for example, even when the disconnection / short-circuit fault condition happens to occur due to a transient change in the input voltages θ, D, H, and w at the time of starting the engine, etc., the fault flags Fθ, FD, FH, Fw is not set. Further, for example, even if the drop-out fault condition of ΔP> 0 and Δθ = 0 is satisfied due to delay in the response of the rear wheel steering to the steering wheel operation, etc., the fault flag Fθ is very short.
Is not set.

Next, the swing control process will be described with reference to FIG.
1, will be described with reference to FIG. The CPU 36 executes the swing control process at regular time intervals (for example, several tens of milliseconds). First, in step 10, the CPU 36 reads the detected values of the tire angle θ, the vehicle speed V, the load w, and the lift H. Here, the vehicle speed V is obtained from a count value corresponding to a frequency obtained by counting the number of pulses of the pulse signal Sp per unit time. In step 20, it is determined whether or not the failure flag Fθ = 1. When the failure flag Fθ = 0, the routine proceeds to step 40 on the assumption that the tire angle sensor 21 is normal. On the other hand, if the tire angle sensor 21 has been diagnosed as a disconnection / short-circuit failure or a disconnection failure and the failure flag Fθ = 1, the routine proceeds to step 30, where the tire angle θ is replaced with a maximum tire angle θmax as a predetermined value.

In step 40, it is determined whether or not the failure flag FD = 1. When the failure flag FD = 0, it is determined that the vehicle speed sensor 22 is normal, and the process proceeds to step S60. On the other hand, when the vehicle speed sensor 22 is diagnosed as a disconnection / short circuit failure and the failure flag FD = 1, step 50
To replace the vehicle speed V with the maximum vehicle speed Vmax as a predetermined value.

In step 60, the ROM is calculated from the tire angle θ.
Using the map stored in 37, the reciprocal value of the turning radius 1 /
Find r. In step 70, 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 the next step 80, the yaw rate change rate ΔY / ΔT is calculated. That is, the tire angle data θ1 before the predetermined time ΔT is read from the predetermined storage area of the RAM 38, and the reciprocal value 1 / r of the turning radius determined from the data θ1 is read.
1 and ΔY / ΔT = V · Δ (1 /
r) / ΔT (where Δ (1 / r) = | 1 / r−1 / r1
|) Is calculated.

In step 90, the yaw rate change rate ΔY
It is determined whether / ΔT is equal to or greater than the set value yo. ΔY
If / ΔT ≧ yo, the routine proceeds to step 100, where the flag FY is set (FY = 1). If ΔY / ΔT <yo, the routine proceeds to step 110, where the flag FY is cleared (FY = 0).

The next steps 120 to 230 are for determining whether or not to lock the rear axle 10 based on the lateral G (Gs value). First, at step 120, it is determined whether or not the failure flag Fw = 1. When the failure flag Fw = 0, it is determined that the pressure sensor 28 is normal, and the routine proceeds to step 140. On the other hand, when the failure flag Fw = 1, it is determined that the pressure sensor 28 has a disconnection / short circuit failure, and the routine proceeds to step 130, where the load w is replaced with a maximum allowable load wmax as a predetermined value.

In step 140, the failure flag FH = 1
Is determined. When the failure flag FH = 0, it is determined that the lift sensor 27 is normal and the step 1 is executed.
Move to 60. On the other hand, when the failure flag FH = 1, it is determined that the lift sensor 27 has a disconnection / short circuit failure, and the routine proceeds to step 150, where the lift H is replaced by a maximum lift Hmax as a predetermined value.

From the preset values as shown in FIGS. 8A and 8B, each value is determined based on the load w and the lift H replaced as necessary in the processing of S120 to S150. The set value of the horizontal G (Gs value) according to the combination of w and H is determined. First, in step 160, it is determined whether the load w is equal to or greater than the set value w0. Load w is set value w
If it is lighter than o, proceed to step 170 and lift H
Is determined to be greater than or equal to the set value Ho, and if the load w is greater than or equal to the set value w0, the routine proceeds to step 180, where it is determined whether or not the lift H is greater than or equal to the set value Ho.

As shown in FIG. 8A, when the load w <wo and the lift H <Ho, in step 190, it is determined whether or not the set value "G2" is adopted and Gs ≧ G2 holds. I do. Further, when the lifting height H ≧ Ho with the load w <wo, in step 200, it is determined whether or not the set value “G1” is adopted and Gs ≧ G1 holds. In each step (S190, S200), the lock condition Gs
If .gtoreq.G2 or Gs .gtoreq.G1, the routine proceeds to step 220, in which case the flag FG is set (FG = 1). On the other hand, if the lock condition is not satisfied in each step, the routine proceeds to step 230, where the flag FG is cleared (FG = 0).

On the other hand, as shown in FIG.
When the height H <Ho at wo, in step 210, it is determined whether or not the set value “G2” is adopted and Gs ≧ G2 holds. When the lock condition Gs ≧ G2 is satisfied, the flag FG is set in step 220, and when the lock condition Gs ≧ G2 is not satisfied, the flag FG is cleared in step 230.

When the load w ≧ wo and the lift H ≧ Ho, the flag FG is set in step 220 (F
G = 1). In other words, the flag FG is set to always lock the rear axle 10 in the cargo handling state where the position of the center of gravity of the forklift 1 is increased due to heavy load and high lift.

In step 240, if any one of the flags FY and FG is "1", a lock command is output. Therefore, at a time when the vehicle body tends to be relatively unstable in the lateral direction as viewed from the traveling state and the cargo handling state detected at that time, the electromagnetic switching valve 14 is switched to the shut-off position and the rear axle 10 is locked. . The tire angle sensor 21
In the case of failure, the tire angle becomes a constant value θmax and the turning radius r = rmin also takes a constant value, so that the difference Δ (1 / r) =
Since it is 0, the yaw rate change rate ΔY / ΔT is always “0”. Also, the flags FY and F which have been set once are set.
G is cleared only when the satisfaction of the lock condition is not satisfied for a predetermined time, and a delay of a predetermined time is caused in unlocking the rear axle 10.

Here, a sensor 21 for detecting a running state,
22, when the tire angle sensor 21 fails, the severest maximum tire angle θmax is adopted as the tire angle θ, and the estimated value Gs of the lateral G becomes Gs = according to the vehicle speed V at that time.
V ² / rmin (where, rmin is the minimum turning radius) are calculated. At this time, the lock condition Gs ≧ G (where G = G
As long as the vehicle travels at the vehicle speed V where (1, G2) is not established, the rear axle 10 is not locked.

FIG. 9 is a graph showing the relationship between the turning radius r and the vehicle speed V for satisfying the lock condition. When the tire angle sensor 21 fails, it is always assumed that the vehicle is turning with the minimum turning radius rmin.
When the vehicle is traveling at a low speed below (= （(G · rmin) (where G = G1, G2)), the lock condition is not satisfied (Gs <
G) and the rear axle 10 is not locked. That is, even if the tire angle sensor 21 fails, the vehicle runs at low speed (V <
Vo), the rear axle 10 is in a free state in which it can swing (except when the load is heavy and the lift is high). For this reason, even if the forklift 1 is traveling on an uneven road surface with the rear wheel 11 under the weight of the vehicle, the low-speed traveling (V
As long as <Vo), the rear axle 10 is in a free state in which it can swing, and the two front wheels, which are drive wheels, are firmly grounded on the road surface. Therefore, the slip caused by the front wheel not contacting the ground is hardly generated.

When the vehicle speed sensor 22 fails, the severest maximum vehicle speed Vmax is adopted as the vehicle speed V, and the estimated value Gs of the lateral G becomes Gs = Vmax according to the turning radius r determined from the tire angle θ at that time. It is calculated as ² / r.
At this time, the lock condition Gs ≧ G (where G = G1, G
2), a tire angle θ (ie, a turning radius ro (= Vmax ² / G)) which is a predetermined range in which ΔY / ΔT ≧ yo is not established.
The tire angular velocity Δθ which is a turning radius exceeding the turning radius exceeding the predetermined value and is less than a predetermined value (that is, Δ (1 / r) <yo · ΔT /
As long as the vehicle travels with a value of Δθ that satisfies Vmax), the rear axle 10 is not locked.

When both the tire angle sensor 21 and the vehicle speed sensor 22 fail, the lock condition Gs ≧ g
G is established, and the rear axle 10 is forcibly locked.

The sensors 27 and 2 for detecting the cargo handling state
For example, when the height sensor 27 fails, the most severe maximum height Hmax is adopted as the height H. Therefore, when the load w of the load loaded on the fork 3 is equal to or greater than w0, the rear axle 10 is forcibly locked. However, if the load w is less than the predetermined range w0, the locking condition Gs ≧ G1 at this time is satisfied. , .DELTA.Y / .DELTA.T.gtoreq.yo, the rear axle 10 is not locked as long as the vehicle travels in a traveling state (tire angle .theta., Vehicle speed V).

When the pressure sensor 28 fails, the severest maximum allowable load wmax is adopted as the load w. Therefore, when the lift H of the fork 3 is equal to or higher than Ho, the rear axle 10 is forcibly locked, but when the lift H is lower than the predetermined range Ho, the lock conditions Gs ≧ G2, ΔY / ΔT ≧ yo. As long as the vehicle travels in a traveling state (tire angle θ, vehicle speed V) in which is not established, the rear axle 10 is not locked.

The lifting sensor 27 and the pressure sensor 28
If both of the above have failed, the maximum lift Hmax and the maximum allowable load wmax are adopted, and w ≧ wo and H ≧ Ho hold, so that the rear axle 10 is always locked.

Thus, the sensors 21, 22, 27, 28
When one of them fails, the rear axle 10 is not locked as long as the vehicle runs in a predetermined traveling state or in a cargo handling mode. As a result, even if the forklift 1 travels on an undulating road surface with the rear wheel 11 loaded with vehicle weight, the rear axle 10 is free to swing, and the two front wheels as drive wheels are firmly First, no slip occurs because it touches the ground.

FIG. 10 shows the lateral G (Gs value) during turning.
6 is a graph showing a time change of the yaw rate change rate ΔY / ΔT. For example, when turning left from straight ahead while driving,
First, the rear axle 10 is locked early when the yaw rate change rate ΔY / ΔT exceeds the set value yo. Then, before the tire angle θ has settled at a constant cut angle and the yaw rate change rate ΔY / ΔT becomes less than the set value yo, the lateral G
Since the (Gs value) reaches or exceeds the set value G (= G1, G2), the forklift 1 turns while the rear axle 10 is kept in the locked state.

When the steering wheel 12 is turned from the left turn to the right turn, there is a section where the Gs value temporarily becomes smaller than the set value G when the direction of the lateral G acting on the vehicle body is switched from right to left. . However, since the yaw rate change rate ΔY / ΔT is equal to or greater than the set value yo in this section while the steering wheel is being switched, the vehicle is turned back while the rear axle 10 is kept in the locked state.

As described in detail above, according to the present embodiment,
The following effects can be obtained. (A) When the sensors 21, 22, 27, and 28 provided on the vehicle for the swing control are out of order, the severest detected value θmax within the normal detection range is used as the detected value.
, Vmax, Hmax, and wmax are employed. for that reason,
Even if one of the sensors 21 and 22 for detecting the traveling state or the sensors 27 and 28 for detecting the cargo handling state fails, the rear axle 10 is securely locked when it should be locked. In addition, the rear axle 10 can be held in a swingable free state as long as the vehicle travels in a predetermined modest traveling state or a cargo handling state.
Therefore, even when one of the sensors fails, the vehicle travels on an uneven road surface by traveling in a predetermined modest traveling state (low-speed traveling, small tire angle) or in a cargo handling state (low-lift, light load). Even when the rear axle 10 swings, the two front wheels, which are drive wheels, are firmly in contact with the road surface and can travel without slipping.

(B) Even if the tire angle sensor 21 breaks down, the rear axle 10 is not locked as long as the vehicle runs at a low speed below the vehicle speed Vo (= √ (G · rmin)), and the vehicle travels on an uneven road surface. Can run without slipping.

(C) Even if the vehicle speed sensor 22 breaks down, the rear axle 10 is locked as long as the vehicle runs at a tire angle θ smaller than the tire angle θo (the tire angle at which the turning radius is ro = Vmax ² / G). The vehicle can travel without slipping even on uneven terrain.

(D) Even when the lift sensor 27 fails, the weight w of the load loaded on the fork 3 is light as less than wo, and the tire angle at which the lock condition (Gs ≧ G1, ΔY / ΔT ≧ yo) is not satisfied, As long as you drive at vehicle speed V,
The rear axle 10 is not locked, and can travel without slipping even on a rough road surface.

(E) Even when the pressure sensor 28 fails, the height of the fork 3 is lowered to less than Ho, and the vehicle travels at the tire angle and the vehicle speed V at which the lock condition (Gs ≧ G2, ΔY / ΔT ≧ yo) is not satisfied. As long as the rear axle 10 is not locked, the vehicle can travel without slipping even on a rough road surface.

(F) The values adopted as the detection values when the sensors 21, 22, 27, 28 fail are not adopted from outside the normal detection range, but are the most severe values within the detection range. Since θmax, Vmax, Hmax, and wmax are set, the range in which the rear axle 10 can be set in the free state can be as wide as possible as described in (b) to (e).

(G) The correspondence between the steering wheel angular velocity ΔP and the tire angular velocity Δθ is the relation at the time of failure (ΔP> 0 and Δθ =
0), it is possible to detect a dropout failure of the tire angle sensor 21. Therefore, even when the dropout failure of the tire angle sensor 21, the swing control is performed based on an erroneous detection value. Can be prevented.

(H) In calculating the yaw rate change rate ΔY / ΔT, a method of differentiating (differentiating) 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 or the like is used. Therefore, there is no need to worry about noise amplification due to the difference (differential) processing, and a highly reliable estimated value ΔY / ΔT can be obtained. On the other hand, in the configuration in which the detection value of the acceleration sensor that is easily affected by vibration of the machine or the like is subjected to difference (differential) processing, the yaw rate change rate ΔY / ΔT obtained by amplifying the noise included in the detection value in a large amount is obtained. Is less reliable.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the lateral G (Gs) and the yaw rate change rate ΔY
The difference from the first embodiment is that / ΔT is calculated using the detection values of the sensors for detecting the yaw rate and the vehicle speed.

As shown in FIG. 15, a gyroscope 51 as a yaw rate detector is mounted on a balance weight 50 disposed at the rear of the forklift 1. In this embodiment, a piezoelectric gyroscope made of a piezoelectric element is used as the gyroscope 51. For example, other types such as a gas rate gyroscope or an optical gyroscope can be used.

As shown in FIG. 16, the gyroscope 5
1 is an input interface 46 via an AD conversion circuit 52.
And detects the yaw rate (angular velocity) ω (rad / sec) when the forklift 1 turns, and outputs a detection value ω corresponding to the yaw rate to the CPU 36. This embodiment has a configuration in which a gyroscope 51 is provided as a detector instead of the tire angle sensor 21 used in the first embodiment. Therefore, the tire angle sensor 2
Handle angle sensor 2 required for failure diagnosis 1
5 and the steering counter 40 are not provided. Further, an error counter 53 for diagnosing a failure of the gyroscope 51 is provided. Further, since the lift sensor 54 can check the lift in two stages of the high lift and the low lift (see FIG. 8), for example, the lift is turned on when the lift is equal to or higher than the set value Ho, and the set value H is turned on.
o Use a proximity switch that turns off below. The other configuration is the same as that of the first embodiment except for a part of the program data stored in the ROM 37.

In the present embodiment, the lateral G and the rate of change of the yaw rate ΔY / ΔT are calculated based on the detected value Y of the gyroscope 51,
The vehicle speed V obtained based on the detection signal of the vehicle speed sensor 22
Is calculated using For this reason, the swing control program data stored in the ROM 37 includes the horizontal G
Equation Gs = V · Y as a calculation equation for calculating (Gs), and equation ΔY as a calculation equation for calculating a yaw rate change rate ΔY / ΔT.
/ ΔT = | Y−Y1 | (where Y1 is the yaw rate data before the predetermined time ΔT).

As shown in FIG. 17, the gyroscope 5
1 is a yaw rate Y in the range of -90 to +90 deg / sec.
And the detection value (voltage value) ω in the normal state is 0 to E
Within the range of (power supply voltage), a range of ωmin ≦ ω ≦ ωmax is taken. Therefore, it is set so that when ω <ωmin or ω> ωmax, a disconnection / short circuit fault is diagnosed.
The output value H of the lift sensor 54 is Hmin (> 0) when the sensor is normal and Hmax (<E) when the sensor is off. Therefore, when H <Hmin or H> Hmax,
It is set to diagnose a disconnection / short circuit failure.

When the gyroscope 51 is diagnosed as having a failure, the most severe yaw rate (9
0deg / sec.) Is set. Of course, it is also possible to set ωmin (a value corresponding to -90 deg / sec.) As the severest ω. Further, when the height sensor 54 is diagnosed as a failure, it is considered that the height is high (on), and a height flag for checking whether the height is high or low when using the map of FIG. 8 is set. I try to set it. In addition, each sensor 22, including the vehicle speed sensor 22,
The failure diagnosis method of 28 and the value set as the detection value at the time of failure are set in the same manner as in the first embodiment.

The control by the CPU 36 is as follows.
First, the CPU 36 reads each detected value such as the yaw rate Y, the vehicle speed V, and the load w. And the yaw rate change rate ΔY /
ΔT is calculated using the formula ΔY / ΔT = | Y−Y1 | (where Y1 is the yaw rate data before the predetermined time ΔT), and the horizontal G
Is calculated as Gs = V · Y.

The output signal of the height sensor 54 is set when the height flag is on, and cleared when the height flag is off. Then, the set value of the horizontal G is determined from the detection value w from the pressure sensor 28 and the state of the lift flag using the map shown in FIG. If the Gs value is equal to or greater than the set value or if the yaw rate change rate ΔY / ΔT is equal to or greater than the set value yo,
A lock signal is output to lock the rear axle 10.

The control when the sensor has a fault is as follows. The CPU 36 performs a failure diagnosis using the detection values D, w, ω, and H from the sensors 22, 28, 51, and 54. If any of the detection values D, w, ω, and H satisfy the failure condition,
The error counter corresponding to the sensor is incremented. When the counter value reaches a predetermined value "10" set as a predetermined time, the sensor is diagnosed as having failed. For the sensor diagnosed as a failure, the most severe value (Vmax, wmax, ωmax, etc.) among the normal detection values set in advance is set as the detection value.

For example, when the gyroscope 51 is diagnosed as having a failure, the detected value is the maximum yaw rate Y
Set ωmax corresponding to max (= 90 deg / sec.). As a result, the lateral G is calculated as Gs = V · Ymax, and when the value Gs becomes equal to or greater than the set value of the lateral G at that time determined from the detected values w and H according to the cargo handling state, the rear axle 10 is activated. Will be locked. Here, since the yaw rate ω becomes a constant value ωmax, the yaw rate change rate ΔY
/ ΔT is always “0” at the time of this failure diagnosis, and ΔY /
Locking is not performed from the lock condition of ΔT.

FIG. 18 is a map showing the relationship between yaw rate | Y | and vehicle speed V for satisfying the lock condition. When the gyroscope 51 fails, the maximum yaw rate Yma
It is considered that the vehicle is turning at x (= 90 deg / sec.). However, as long as the vehicle travels at a low speed below the vehicle speed Vo = G / Ymax (G = G1, G2), the lock condition is not satisfied (Gs <G). As a result, the rear axle 10 is not locked (except at the time of heavy load and high lift). As a result, even when the forklift 1 is traveling on an undulating road surface with the rear wheel 11 under a heavy vehicle weight, the vehicle travels at a low speed (V <V
In the case of o), since the rear axle 10 is in a free state in which the rear axle can swing, the two front wheels, which are drive wheels, are firmly grounded on the road surface. Therefore, the slip caused by the fact that the front wheels do not touch the ground hardly occurs.

When the vehicle speed sensor 22 fails, the severest maximum vehicle speed Vmax is adopted as the vehicle speed V, and the lateral G is calculated as Gs = Vmax.Y. for that reason,
The yaw rate Y is Yo = G / Vmax (where G = G1, G
As long as the vehicle turns so as to be less than 2), the rear axle 10 is kept in the free state. Therefore, as long as the forklift 1 is turned at a speed lower than the yaw rate Yo, the slip caused by the front wheel 7 not contacting the ground is hardly generated.

Further, when the height sensor 54 fails, it is regarded as a high height (a height flag set). Therefore, if the load w is less than wo, the lock condition Gs ≧ G
As long as the vehicle travels in a traveling state (yaw rate Y, vehicle speed V) in which 1, ΔY / ΔT ≧ yo is not established, the rear axle 10 can be maintained in a free state.

When the pressure sensor 28 fails, the severest maximum allowable load wmax is adopted as the load w. Therefore, if the lift H of the fork 3 is less than Ho, as long as the vehicle travels in a traveling state (yaw rate Y, vehicle speed V) where the lock conditions Gs ≧ G2 and ΔY / ΔT ≧ yo are not satisfied, the rear axle 10 Can be kept free. When both the sensors 22 and 51 for detecting the traveling state or the sensors 28 and 54 for detecting the cargo handling state fail, the lock condition Gs ≧ G is always satisfied, so that the rear axle 10 is kept in the locked state. Is done.

Thus, the sensors 22, 28, 51, 54
Even if one of them fails, if the vehicle weight is on the rear wheel side and the vehicle is driven conservatively when traveling on uneven road surface, the rear axle 10 is not locked and the front wheel (drive wheel) 7) Since the ground 7 is almost certainly in contact with the ground, it is possible to avoid the stuck due to the slip as much as possible. It should be noted that the present invention is not limited to the above embodiment, and may be implemented as follows, for example, without departing from the spirit of the invention.

(1) In each of the above embodiments, when the detector is diagnosed as having failed, the severest detected value is actually set as the detected value of the failed detector, and a predetermined calculation and judgment using this value is performed. As a result, the axle is prevented from locking when locking is obviously not needed. On the other hand, instead of actually setting the most severe value, it was assumed that the detection value of the failed detector took the most severe value with respect to the detection values of other detectors for obtaining the determination value. At this time, a predetermined range which is determined in advance that it is not necessary to lock the axle is set and stored. When a detector malfunctions, it is possible to perform control such that the axle is not locked if the detected value is within a predetermined range only by checking the detected value of another normal detector.

For example, in the swing control of the first embodiment, a range that is clearly lower than the vehicle speed Vo (see FIG. 9) that does not require locking is set as a predetermined range of the detection value of the vehicle speed sensor 22, and is stored in a ROM or the like. It is stored in the means. When it is determined that the tire angle sensor 21 has failed, it is determined whether or not the detection value V from the vehicle speed sensor 22 is less than Vo as a predetermined range. Then, when V ≧ Vo, the rear axle 10 is locked, and when V <Vo, the rear axle 10 is controlled not to be locked. Of course, when the vehicle speed sensor 22 fails, the detection value θ of the tire angle sensor 21 is used.
Is within a predetermined range (a range where the turning radius r can be set to a value exceeding ro (see FIG. 9)).
If is within a predetermined range, control that does not lock the rear axle 10 can also be performed.

In the swing control of the second embodiment, a range that is clearly lower than the vehicle speed Vo (see FIG. 18) that does not require locking is set as a predetermined range of the detection value of the vehicle speed sensor 22, and this range is stored in a ROM or the like. It is stored in storage means.
When the gyroscope 51 is diagnosed as having failed, it is determined whether or not the detection value V from the vehicle speed sensor 22 is less than Vo as a predetermined range. Then, when V ≧ Vo, the rear axle 10 is locked, and when V <Vo, the rear axle 10 is controlled not to be locked. Of course, when the vehicle speed sensor 22 fails, it is determined whether or not the detection value ω of the gyroscope 51 is within a predetermined range (a range in which the yaw rate | Y | can be less than Yo (see FIG. 18)). If ω is within the predetermined range, control that does not lock rear axle 10 can also be performed.

This control method can be applied to each sensor for detecting the cargo handling state. For example, in a configuration in which a map or the like is created so as to always allow the axle to oscillate in a predetermined range where the load is small even at the most severe high elevation (for example, Ho ≦ H ≦ Hmax), the failure of the elevation sensor 27 At times, when the detection value of the pressure sensor 28 is within the predetermined range, it is possible to perform control so that the rear axle 10 is not locked. In addition, the most severe heavy load (for example, wo ≤ w
In a configuration in which a map or the like is formed so as to always allow the axle to swing in a predetermined range where the lift is low even when ≤ wmax), when the pressure sensor 28 fails, the detection value of the lift sensor 27 When it is within the range, control for not locking the rear axle 10 can be performed. By employing the above configuration, even when a sensor fails, it is only necessary to monitor the detection values of other normal sensors, and the predetermined calculation and determination processing performed in each of the above embodiments can be eliminated.

(2) The value adopted as the detection value when the detector fails is not limited to the value within the normal detection range.
A value outside the normal detection range can also be used. For example, when the sensors 21, 22, 27, and 28 fail, the tire angle is θa (> θmax) and the vehicle speed is Va (> Vmax).
), Lift as Ha (> Hmax), load as wa
(> Wmax) can be adopted. However, in order to secure a wide range in which the rear axle 10 can be set in a free state in which the rear axle can swing in the event of a detector failure, θmax,
It is preferable to select a value close to Vmax, Hmax, and wmax.

(3) The values adopted as the detection values when the sensor fails are the lateral G (Gs value) and the yaw rate change rate ΔY
It is sufficient if the determination values such as / ΔT, lift H, load w, etc. can be set to the most severe values (values that most easily satisfy the predetermined condition for locking the rear axle), and the maximum value within the normal detection range is sufficient. The value is not limited to the minimum value. For example, in the above-described embodiment, the same result is obtained even if Hmax and wmax are not used as the detection values when the sensors 27 and 28 fail, so that Ho ≦ H <as the detection value when the height sensor 27 fails.
A load H that satisfies wo ≦ w <wmax is used as a detection value at the time of failure of the pressure sensor 28.
May be adopted. Even if such values H and w are used as the detection values at the time of failure, the same effects as in the above embodiment can be obtained.

(4) If the tire angle θ is replaced with the maximum tire angle θmax when the tire angle sensor 21 fails, ΔY /
ΔT = 0, but instead of replacing the tire angle θ with the maximum tire angle θmax, Δ (1 / r) in the yaw rate change rate ΔY / ΔT calculation equation (Equation (2)) is used to make a turn that can occur in normal running. Maximum change rate Δ (1) of reciprocal value of radius
/ R) max may be set so that a severe ΔY / ΔT value can be calculated. Even with this configuration, when the tire angle sensor fails, the vehicle speed Vo (= yo · ΔT / Δ)
As long as the vehicle runs at a low speed less than (1 / r) max),
The rear axle can be in a free state in which it can swing.

(5) The swing control may be performed only by looking at the running state, for example, using only the lateral G of the vehicle or only the lateral G and the yaw rate change rate ΔY / ΔT as the judgment values. (6) It is not necessary to perform fault diagnosis for all sensors.
Diagnose only one or more specific faults,
A configuration in which a severe value is set as the detection value at the time of the failure may be adopted. For example, in the above embodiment, only the sensors 21 and 22 for detecting the traveling state may be diagnosed for failure, or only the sensors 27 and 28 for detecting the cargo handling state may be diagnosed for failure. Further, the failure diagnosis may be performed for only one of the sensors 21 (51) and 22 for detecting the traveling state, or the failure diagnosis may be performed for only one of the sensors 27 (54) and 28 for detecting the cargo handling state.

(7) In the first embodiment, when the vehicle speed sensor 22 is diagnosed as having a failure, the CPU 36 as a judgment value compulsory setting means uses either the estimated value Gs of the lateral G or the yaw rate change rate ΔY / ΔT. One may be forcibly set to “0” and the restriction on whether or not the rear axle 10 is in the free state may be relaxed to only one of them. For example, if Gs = 0, the restriction on the tire angle θ is cut, and if ΔY / ΔT = 0, the restriction on the tire angular velocity Δθ is cut. According to this configuration, the rear axle 1
It is possible to secure a wider range in which 0 can be set in a free state in which it can swing. Of course, when the height sensor or the pressure sensor fails, either the lateral G or the yaw rate change rate ΔY / ΔT may be forcibly set to “0”.

(8) The present invention may be implemented in a device that performs swing control using only the cargo handling state as a determination value. For example, the cargo handling state (the height of the center of gravity of the vehicle) is determined based on the lift H and the load w detected by the lift sensor and the pressure sensor.
To lock. When the lift sensor fails, the maximum lift Hmax is set as the detected value, and when the pressure sensor fails, the maximum allowable load wmax is set as the detected value. According to this configuration, even when one of the sensors forming the group for detecting the cargo handling state fails, the rear axle 10 can be set to a free swingable state in a predetermined cargo handling state.

(9) Even if the swing control based on the lateral G is performed by actually calculating the height of the center of gravity of the vehicle and using a set value determined according to the height of the center of gravity, Good. For example, the height of the center of gravity of the vehicle is calculated from the detected values H and w of the height sensor and the load sensor, and the determination of the side G is performed using the set value of the side G obtained from the height of the center using a map or the like. To do. According to this configuration, more accurate swing control according to the height of the center of gravity can be performed.

(10) The determination values for regulating and controlling the axle swing are not limited to the lateral GGs, the yaw rate change rate ΔY / ΔT, and the lateral G set values G used in the above embodiments.
For example, as the determination value, the lateral G change rate ΔG / ΔT (= V · Δ
Y / ΔT). Alternatively, the set value yo of the yaw rate change rate ΔY / ΔT may be changed according to the cargo handling state and adopted as one of the determination values.

(11) The number of detectors used to obtain one judgment value is not limited to two. For example, a configuration in which one determination value is calculated using detection values of three or more detectors may be employed. Even if the number of detectors is three or more, a severe value is set as a detection value of a failed detector, for example, a value whose determination value is most likely to satisfy a predetermined condition within a normal detection range. Thereby, a similar effect can be obtained. Further, when the method described in the above (1) is adopted, it is only necessary to monitor the detection values of the remaining detectors other than the failed detector, and it is possible to eliminate or simplify necessary calculations and processes. it can.

(12) The detection method of each sensor is not limited to the method employed in the above embodiment, and may be any method capable of detecting a required detection value. For example, a sensor that detects a piston position of a steering cylinder may be used as a tire angle sensor. In addition, an ultrasonic sensor, a proximity sensor, or the like may be used.

(13) Regulation of axle swing is not limited to complete lock. In a regulated state, the axle may swing in a small range. (14) It may be carried out by a battery type forklift.
Further, the present invention may be implemented in an industrial vehicle other than a forklift.

The technical ideas (inventions) grasped from the above embodiments and not described in the claims are described below together with their effects. (A) In the invention according to claim 3, the plurality of detectors detect a detection value necessary to obtain at least one of a lateral G of the vehicle and a change rate of the yaw rate of the vehicle as a determination value. A plurality of first detectors, and the control means, when the predetermined condition that the lateral G or yaw rate change rate obtained from the detection values of the plurality of first detectors is equal to or more than a set value is satisfied, the axle The control mechanism is set to operate, and the control means sets a detection value of a first detector of the plurality of first detectors that is not the side diagnosed with a failure so as not to operate the axle control mechanism. The determined range is determined based on the assumption that the detection value of the detector diagnosed as having a failure takes a value that can maximize the lateral G or the yaw rate change rate within the normal detection range. A range not satisfy the predetermined condition. According to this configuration, in order to determine whether to operate the axle restricting mechanism, the first non-failed side is determined.
It is only necessary to monitor the detection value of the detector, and it is not necessary to determine whether the determination value satisfies a predetermined condition. Therefore, various calculations and determination processes can be eliminated.

(B) In the invention described in claim 6, both the lateral G and the yaw rate change rate are obtained from the detected values of the steering angle detector and the vehicle speed detector, and the vehicle speed detector is A determination value compulsory setting means for compulsorily setting one of the lateral G and the yaw rate change rate to a value smaller than a set value when a failure is diagnosed is provided. According to this configuration, when the vehicle speed detector is diagnosed as a failure, one of the lateral G and the yaw rate change rate is not restricted, and a wider range in which the axle can be held in a swingable state can be secured.

(C) In the invention according to any one of claims 1 to 11, the failure diagnosis means detects a detection value corresponding to a detection value of the detector to be a failure diagnosis target. A possible comparison detector is provided, and the detection value of the comparison detector and the detection value of the detector are determined to determine whether or not the correspondence between the detection value and the detection value is a failure time. It has failure diagnosis means. According to this configuration, it is possible to prevent a problem that the swing of the axle is regulated based on an erroneous detection value due to a fallout failure of the detector. In the above-described embodiment, the CPU 36 constitutes a dropout failure diagnosing means, and the steering wheel angle sensor 25 constitutes a detector for comparison.

[0128]

As described above in detail, according to the first aspect of the present invention, the detection value of the detector diagnosed as having a failure is most likely to satisfy the predetermined value within the normal detection range. When it is assumed that the axle control mechanism is not required to operate, the axle control mechanism is not operated at a predetermined time when it is recognized that the operation of the axle control mechanism is not necessary. When it is OK to swing the axle, the axle can be held in a swingable state, and occurrence of troubles such as slipping of drive wheels can be prevented as much as possible.

According to the second aspect of the present invention, as the detection value of the detector diagnosed as having a failure, the determination value within the normal detection range is set to a value that is more severe than the value that most easily satisfies the predetermined condition. And when a detection value of another detector for obtaining the determination value takes a value of a certain area within the detection range, at least a predetermined value at which the determination value does not satisfy a predetermined condition is set. Therefore, if one of the detectors fails or the axle can be swung, it is possible to hold the axle in a swingable manner.

According to the third aspect of the present invention, the detection value of the detector diagnosed as having a failure is determined by looking at the detection value of another detector that is not the side diagnosed with the failure for obtaining the determination value. When it is assumed that the determination value has a value that most easily satisfies the predetermined condition in the normal detection range, if the detection value takes a value within a predetermined range in which the determination value does not satisfy the predetermined condition,
Since the axle control mechanism is not operated, it is not necessary to perform a calculation for determining whether the determination value satisfies a predetermined condition.

According to the fourth aspect of the present invention, the detection value of the detector diagnosed as having a failure is set to a value which makes the determination value most easily satisfy the predetermined condition within the normal detection range. Therefore, even if one of the detectors fails, the range in which the axle can be held in a swingable state can be ensured as wide as possible.

According to the invention as set forth in any one of claims 5 to 7, the detected value of the first detector diagnosed as having a failure is the most lateral G or yaw rate within the normal detection range. A value that can increase the rate of change is set, so that the axle can be held in a swingable state even when the first detector fails or in a discreet running state where the axle can be swung. And the range can be secured as wide as possible.

According to the eighth aspect of the present invention, when the second detector for detecting the height of the center of gravity of the vehicle for determining the set value of the lateral G is diagnosed as a failure, the detected value is determined as the normal value. Is set so as to maximize the height of the center of gravity of the vehicle within the detection range of
Even if one of the detector and the second detector for obtaining the height of the center of gravity breaks down, as long as the vehicle travels in a discreet traveling and cargo handling state where the axle can be swung clearly, the axle Can be held in a swingable state, and the range can be secured as wide as possible.

According to the ninth or tenth aspect of the present invention, when the second detector for obtaining the height of the center of gravity of the vehicle is diagnosed as having a failure, the detected value falls within the normal detection range. Since the value that can make the height of the center of gravity of the vehicle the highest is set, as long as one of the second detectors breaks down, the vehicle runs in a cargo handling state where the axle can be swung clearly. Can hold the axle in a swingable state, and can secure the range as wide as possible.

According to the eleventh aspect of the present invention, when the detection value of the detector to be diagnosed continuously satisfies a preset failure condition for a predetermined time or more, the detector is diagnosed as a failure. Therefore, it is possible to prevent erroneous diagnosis due to transiently satisfying the failure condition despite the normal condition.

[Brief description of the drawings]

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

FIG. 2 is a schematic diagram showing an axle regulating 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 an explanatory diagram for explaining a detection voltage of a tire angle.

FIG. 6 is a schematic diagram for explaining a detection principle of a vehicle speed sensor.

FIG. 7 is a graph showing a detection signal of a vehicle speed sensor.

FIG. 8 is a map showing set values of a lateral G with respect to a load and a lift.

FIG. 9 is a graph showing a lock area with respect to a turning radius and a vehicle speed.

FIG. 10 is a graph showing a change in a lateral G, yaw rate change rate during turning.

FIG. 11 is a flowchart of a swing control process.

FIG. 12 is also a flowchart.

FIG. 13 is a flowchart of a sensor failure diagnosis process.

FIG. 14 is also a flowchart.

FIG. 15 is a plan view of a forklift according to the second embodiment.

FIG. 16 is a block diagram showing an electrical configuration of the vehicle body swing control device.

FIG. 17 is a graph for explaining a detection voltage of the gyroscope.

FIG. 18 is a graph showing a lock region with respect to a yaw rate and a vehicle speed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Forklift as an industrial vehicle, 1a ... Body frame as a vehicle body, 3 ... Fork as a loading device, 1
0 ... rear axle as axle, 11 ... rear wheel as steered wheel, 13 ... hydraulic damper constituting axle regulation mechanism, 1
4... Constituting an axle regulating mechanism and an electromagnetic switching valve, 21
... A tire angle sensor as a detector, a first detector and a steering angle detector, 22... A vehicle speed sensor as a detector, a first detector and a vehicle speed detector, 25... A steering wheel angle sensor as a comparison detector, 27 ... Height detector as detector, second detector and height detector, 28. Pressure sensor as detector, second detector and load detector, 29. Controller as control means, 36. CPU as detection value setting means, 51... Detector, first detector and gyroscope as steering angle detector, 54... Detector, second
Height sensor as detector and height detector, Gs: lateral G, ΔY / ΔT: yaw rate change rate, θ: tire angle as steering angle, D: detected voltage, V: vehicle speed, H: lift, w …
load.

Claims (11)

[Claims] An axle supported to be able to swing up and down with respect to a vehicle body; an axle regulating mechanism for regulating swinging of the axle; and detecting at least one of a running state and a cargo handling state of the vehicle. Control means for operating the axle restriction mechanism when a determination value determined from detection values of at least two of the plurality of detectors satisfies a predetermined condition. Failure diagnosis means for diagnosing a failure of the two detectors, wherein the control means, when the failure diagnosis means has diagnosed the detector as a failure, the detection value of the detector diagnosed as a failure, If it is determined that the operation of the axle restricting mechanism is not necessary, assuming that the determination value has been set to a value that most easily satisfies the predetermined condition within the detection range in the normal state of the detector, the axle restricting mechanism is activated. Body swing control apparatus for industrial vehicles that is set so as not to. 2. The control means, as a detection value of a detector diagnosed as a failure by the failure diagnosis means, a determination value within a normal detection range that is equal to or greater than a value that most easily satisfies the predetermined condition, and Detection value setting means for setting at least a predetermined value at which the determination value does not satisfy the predetermined condition when a detection value of another detector for obtaining the determination value takes a value of a certain area within the detection range. The vehicle body swing control device according to claim 1, further comprising: 3. The control means according to claim 1, wherein the detection value of another detector for obtaining the determination value on the non-diagnosed side is a detection range of a normal state of the detected value of the detector diagnosed as a failure. If the determination value is within a predetermined range that does not satisfy the predetermined condition when it is assumed that the determination value has a value that most easily satisfies the predetermined condition, the axle restriction mechanism is not operated. 2. The vehicle body swing control device for an industrial vehicle according to claim 1. 4. The predetermined value set by the detection value setting means is a value which makes the determination value most easily satisfy the predetermined condition within a normal detection range of the detector diagnosed as a failure. Item 3. The vehicle body swing control device for an industrial vehicle according to item 2. 5. A plurality of first detectors for detecting a detection value necessary to obtain at least one of a lateral G of the vehicle and a yaw rate change rate of the vehicle as determination values. Wherein the control means satisfies the predetermined condition that a lateral G or yaw rate change rate obtained from detection values of the plurality of first detectors is equal to or more than a set value.
The detection value setting means is set to operate the axle restriction mechanism, and the detection value setting means determines a detection value of a detector diagnosed as a failure by the failure diagnosis means among the plurality of first detectors, in a normal state. 3. The vehicle body swing control device for an industrial vehicle according to claim 2, wherein the predetermined value is set to a value that can maximize the lateral G or the yaw rate change rate within the detection range of (b). 6. The vehicle body swing of an industrial vehicle according to claim 5, wherein the plurality of first detectors include a steering angle detector for detecting a steering angle of a steered wheel and a vehicle speed detector for detecting a vehicle speed. Control device. 7. The vehicle body swing control of an industrial vehicle according to claim 5, wherein the plurality of first detectors include a yaw rate detector for detecting a yaw rate of the vehicle and a vehicle speed detector for detecting a vehicle speed. apparatus. 8. In addition to a plurality of first detectors for obtaining the lateral G, a plurality of second detectors necessary for detecting the height of the center of gravity of the vehicle are provided, and the control means is configured to control the lateral When G is equal to or greater than a set value determined according to the height of the center of gravity of the vehicle detected from the plurality of second detectors, the predetermined condition is satisfied, and the axle control mechanism is set to operate. The detection value setting means sets the height of the center of gravity of the vehicle within a normal detection range as a detection value of a detector diagnosed as a failure by the failure diagnosis means among the plurality of second detectors. The vehicle body swing control device for an industrial vehicle according to any one of claims 5 to 7, wherein the predetermined value that is the highest possible value is set. 9. The plurality of detectors include a plurality of second detectors for detecting, as the determination value, a height of a center of gravity of the vehicle determined from a cargo handling state of the vehicle, and the control unit includes a plurality of second detectors. When the predetermined condition that the height of the center of gravity of the vehicle detected by the two detectors is equal to or more than a set value is satisfied, the axle control mechanism is set to be activated. 3. The industrial vehicle according to claim 2, wherein the predetermined value is set as a value that can maximize the height of the center of gravity of the vehicle within the normal detection range as a detection value of the second detector diagnosed as a failure. Body swing control device. 10. A plurality of second detectors required to detect the height of the center of gravity of the vehicle, the second detector includes a height detector that detects a height of a loading device provided on the vehicle for loading a load. The vehicle body swing control device for an industrial vehicle according to claim 8, further comprising a load detector configured to detect a load of the load on the loading device. 11. The failure diagnosis means diagnoses a failure of the detector when a detection value of the detector to be failure diagnosis continuously satisfies a preset failure condition for a predetermined time or more. The vehicle body swing control device for an industrial vehicle according to any one of claims 1 to 10.