JPH11321267A - Body oscillation control device for industrial vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a lowering of ground pressure of a drive wheel as small as possible when a vehicle turns in the direction of making a driven wheel an outer wheel at the time of locking link mechanism suspending a right/left pair of drive wheel and driven wheel in such a way as to allow oscillation in the rolling direction of a body, and reduce unnecessary lock of the link mechanism. SOLUTION: A drive wheel 3 and an auxiliary wheel forming a right/left pair are suspended to a body frame through link mechanism 20 in such a way as to allow oscillation in the rolling direction of a body. When lateral acceleration computed from the respective detection values of a steering angle sensor and a vehicle speed sensor becomes the set value or more, a controller 57 closes a solenoid changeover valve 47 to lock a damper 44. At the time of turning in the direction of making the auxiliary wheel 4 on outer wheel, the damper 44 is locked with delayed timing of a caster spring 30 being almost completely contracted into specified length. The set value of lateral acceleration is selected according to the center-of-gravity height of a vehicle with lift height H and load W detected by a lift height sensor 55 and a load sensor 56, as parameters.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial vehicle having a suspension mechanism such as a reach-type forklift, in which a driving wheel and an auxiliary wheel are suspended via a link mechanism so as to be able to swing in a roll direction with respect to a vehicle body. The present invention relates to a vehicle body swing control device for an industrial vehicle that performs control for locking a link mechanism to restrict swinging of a vehicle body in a roll direction.

[0002]

2. Description of the Related Art Reach-type forklifts, for example,
There are three-wheeled vehicles with two front wheels and one rear wheel. In this three-wheeled vehicle type, an auxiliary wheel is usually provided so as to form a pair with a driving wheel which is a rear wheel. Drive wheels and auxiliary wheels
The body is suspended from the body frame via a link mechanism to allow the body to swing in the roll direction, and a spring or damper is interposed between the body and the link mechanism to form a rear suspension. I have. For example, when traveling on an uneven road surface, the drive wheels and auxiliary wheels swing relative to the vehicle body by the movement of the link mechanism, thereby absorbing road surface irregularities and stabilizing the vehicle body posture in the left-right direction. I have. However, when the forklift turns, the centrifugal force acts laterally on the car body due to the lateral force.However, this suspension function causes the car body to be tilted rather strongly, and reduces the stability of the car body when turning. Had become.

Therefore, Japanese Patent Application Laid-Open Nos. Hei 6-191250 and Hei 6-191251 disclose that an acceleration sensor is provided in a reach type forklift, and the tilting acceleration (lateral acceleration) G detected by the acceleration sensor is a predetermined value. As described above, a suspension device in which a cylinder device interposed between a vehicle body frame and a link mechanism is locked by closing an on-off valve is disclosed. According to this forklift, when the tilting acceleration exceeds a predetermined value during turning,
Since the link mechanism is fixed to the vehicle body frame and the swing of the vehicle body in the roll direction is regulated, the lateral inclination of the vehicle body is suppressed to be small, and it is easy to maintain a stable vehicle body posture during turning.

In Japanese Patent Application Laid-Open Nos. Hei 6-191250 and Hei 6-191251, the cylinder device is locked even when the vehicle speed is lower than a set value. This is because, when carrying out cargo handling work, the load is lifted high and the height of the center of gravity of the vehicle is increased, so that the vehicle tends to be relatively unstable. In order to lock.

[0005]

However, in a reach type forklift, an auxiliary wheel (caster wheel) is usually attached to a link mechanism via a caster spring. For this reason, when the forklift turns in a direction in which the auxiliary wheel is used as the outer wheel, even if the tilting acceleration G becomes a predetermined value or more and the cylinder device is locked, the caster spring is laterally moved from the vehicle body posture at the time of locking. If there is still room for compression deformation due to the acceleration G, the caster spring is compression-deformed and the vehicle body is further inclined in the lateral direction. The fact that the vehicle body leans somewhat further is not a problem if the tilt is within a safe range. However, when the vehicle body tilts in the lateral direction with the cylinder device locked and the drive wheels fixed to the vehicle body frame, the drive wheels tend to rise from the road surface. As a result, there is a fear that the contact pressure of the drive wheel is reduced, and in some cases, the drive wheel is lifted off the road surface.

[0006] A decrease in the contact pressure of the drive wheels or the rise of the drive wheels from the road surface causes the drive wheels to slip or idle, and the driving force is hardly transmitted to the road surface, so that the running speed becomes slow or the braking force when the brake is applied is reduced. There was a fear of becoming weak.
In addition, since the driving wheels also serve as the steering wheels, there is a possibility that the steering performance may be reduced when the auxiliary wheels are turned as the outer wheels. Therefore, it is necessary to take measures to prevent the ground pressure of the drive wheel from being reduced by locking the cylinder device when the auxiliary wheel turns as the outer wheel. The caster spring is provided to absorb the unevenness of the road surface, and the spring constant is smaller than the elastic force of the link mechanism.
When the caster spring is compressed and the link mechanism starts to move, the inclination of the vehicle body is within a sufficiently safe range.

Further, since the cylinder device is always locked when the vehicle speed is low at which there is a possibility that the cargo handling operation is performed, the link mechanism is unnecessarily locked even when the height of the center of gravity of the forklift is low. Such an unnecessary lock was sometimes inconvenient. For example, if the vehicle is constantly locked at a low vehicle speed, it is difficult to absorb vibration due to unevenness of the road surface.
Although the auxiliary wheels can absorb some vibration due to the expansion and contraction of the caster springs, it is difficult for the vehicle body to absorb the vibration when the drive wheels travel on uneven road surfaces. Furthermore, if the vehicle is locked on the front wheel while traveling on uneven road surface, it will be in a three-point support state of the front two wheels and the rear auxiliary wheel, and the rear drive wheel will rise. May occur, and slip is likely to occur due to a decrease in the contact pressure of the drive wheels. For this reason, it has been desired to lock the link mechanism only when necessary.

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 allow a pair of right and left driving wheels and driven wheels to swing in the roll direction of a vehicle body. In an industrial vehicle in which a suspended link mechanism is lock-controlled when the vehicle turns, the unnecessary locking of the link mechanism is reduced while minimizing the decrease in the ground pressure of the drive wheels during turning of the vehicle whose driven wheel is the outer wheel. It is an object of the present invention to provide a vehicle body swing control device for an industrial vehicle, which can control the vehicle body swing. A second object is that, in a configuration in which the driven wheel is an auxiliary wheel attached to a link mechanism via an elastic member, when the vehicle in which the auxiliary wheel is an outer wheel turns, the decrease in the ground pressure of the drive wheel is effectively reduced. To keep it down. A third object is to realize a lock control that can save the trouble of actually calculating the height of the center of gravity of the vehicle, and does not detect all the parameters that determine the height of the center of gravity, and considers the height of the center of gravity approximately. It is in. A fourth object is to realize a finer lock control according to the height of the center of gravity of the vehicle by continuously changing the set value of the lateral acceleration in accordance with the continuous change of the parameter detected by the detector, thereby making it unnecessary. To further reduce the number of locks. A fifth object is to quickly lock the link mechanism at least at the start of turning of a vehicle whose driving wheels are outer wheels. A sixth object is to lock the link mechanism only when the lateral acceleration is caused by the turning of the vehicle. A seventh object is to alleviate the shock of the vehicle body when the lock of the link mechanism is released.

[0009]

In order to achieve the first object, according to the first aspect of the present invention, a pair of drive wheels and driven wheels on the left and right allow the body to swing in the roll direction. Thus, in an industrial vehicle suspended from a vehicle body via a link mechanism, a swing regulation mechanism for locking the link mechanism, a lateral acceleration measuring means for measuring a lateral acceleration of the vehicle, and a center of gravity of the vehicle A center-of-gravity height measuring means for continuously or intermittently measuring at least one parameter for determining the height or the center-of-gravity height, which is previously set by changing discontinuously or continuously with respect to the center-of-gravity height or the parameter; From among the set values of the lateral acceleration, a set value corresponding to the measured value measured by the center-of-gravity height measuring means is selected, and when the lateral acceleration measured by the lateral acceleration measuring means is equal to or more than the set value, the swinging is performed. A lock mechanism for operating the regulating mechanism to lock the link mechanism is performed, and the lock is not performed when the driven wheel is in the turning direction of the vehicle that is the outer wheel, or the lock timing is such that the drive wheel is the outer wheel. And control means set to be relatively delayed from the lock timing in the turning direction of the vehicle.

According to a second aspect of the present invention, in the second aspect, the driven wheel is an auxiliary wheel attached to the link mechanism via an elastic member. When the auxiliary wheel is in the turning direction of the vehicle as the outer wheel, the link mechanism is set to be locked at a timing of waiting until the elastic member contracts by a predetermined amount.

According to a third aspect of the present invention, in the third aspect of the present invention, in the first or second aspect, the center-of-gravity height measuring means includes a parameter for determining a height of the center of gravity of the vehicle. The control means includes at least one detector for detecting continuously or intermittently, and the set value of the lateral acceleration tends to take a smaller value in advance as the height of the center of gravity of the vehicle is higher with respect to the parameter. , Are set discontinuously or continuously.

According to a fourth aspect of the present invention, in order to achieve the fourth object, in the invention according to any one of the first to third aspects, the center-of-gravity height measuring means includes a center-of-gravity height of the vehicle. A plurality of detectors for detecting a plurality of parameters for determining the parameter, at least one of the detectors to continuously detect the parameter, the control means, the set value of the lateral acceleration At least one parameter is set to change continuously.

According to a fifth aspect of the present invention, in order to achieve a fourth object, in the third or fourth aspect of the present invention, the center-of-gravity height measuring means is mounted on a vehicle so as to be vertically movable. The apparatus includes a lift detector that detects the lift of the device as the parameter, and a load detector that detects the load of the load on the loading device as the parameter.

According to a sixth aspect of the present invention, in order to achieve the fifth object, in the first aspect of the present invention, the rate of change of the yaw rate or the lateral acceleration of the vehicle is determined. A turning change measuring means for measuring, and the control means, when the yaw rate change rate or the lateral acceleration change rate becomes equal to or more than a set value when the drive wheel is in a turning direction in which the driving wheel is an outer wheel, the control means controls the swing restriction mechanism. Actuating is the gist.

According to a seventh aspect of the present invention, in the first aspect of the present invention, the lateral acceleration measuring means includes a vehicle speed detector for detecting a vehicle speed of the vehicle;
A physical quantity detector for detecting a physical quantity necessary to calculate the lateral acceleration using the vehicle speed; and a lateral acceleration estimating means for estimating the lateral acceleration by an arithmetic operation using respective detection data detected by the two detectors. ing.

In order to achieve the sixth object, according to the invention set forth in claim 8, in the invention set forth in any one of claims 1 to 7, the control means may control the swing restricting mechanism. The operation of the swing regulation mechanism is set to be stopped after a lapse of a predetermined time from the point in time when the lock condition for activation is not satisfied.

According to a ninth aspect of the present invention, in order to achieve a seventh object, in the first aspect of the present invention, the control means operates the swing regulating mechanism. The set value at the time of stopping the operation of the swing regulation mechanism is set smaller than the set value at the time.

According to a tenth aspect of the present invention, in order to achieve a seventh object, in the invention according to any one of the first to ninth aspects, the swing restriction mechanism is provided in the link mechanism. A regulating force adjusting unit capable of adjusting a regulating force applied for locking is provided, and the control unit performs the lock control by controlling the regulating force adjusting unit.
When stopping the operation of the swing regulation mechanism, the gist of the invention is to control the regulation force adjusting means so that the lock of the link mechanism is gradually released.

According to the first aspect of the present invention, when the lateral acceleration measured by the lateral acceleration measuring means exceeds a set value, the locking mechanism is operated to lock the link mechanism. Control is performed by control means. The set value of the lateral acceleration used at this time is measured by the center-of-gravity height measuring means from among the set values which are previously set discontinuously or continuously with respect to the center-of-gravity height or a parameter for determining the center-of-gravity height. The set value according to the measured value is selected. That is, the height of the center of gravity of the vehicle is considered in determining the timing for locking the link mechanism. For example, the link mechanism is locked with a smaller lateral acceleration as the center of gravity is higher. If the set value of the lateral acceleration is one, the set value must be determined based on when the center of gravity is the highest, and it will be locked unnecessarily when the center of gravity is low, but this kind of unnecessary Locking is reduced. Further, when the driven wheel is in the turning direction of the vehicle as the outer wheel, the link mechanism is not locked, or the locking timing is relatively delayed as compared with when the driving wheel is in the turning direction as the outer wheel. For this reason, since the vehicle body leans to the driven wheel side while the link mechanism is locked, it is easy to avoid that the drive wheel is lifted off the road surface.

According to the second aspect of the invention, when the vehicle in which the auxiliary wheel is the outer wheel turns, the lock timing is delayed so that the link mechanism is locked at the timing when the elastic member contracts by a predetermined amount. As a result, the amount of contraction of the elastic member after locking is eliminated or relatively reduced, so that a decrease in the ground pressure of the drive wheels can be suppressed as small as possible during turning of the vehicle in which the auxiliary wheels are outer wheels.

According to the third aspect of the present invention, the parameters for determining the height of the center of gravity of the vehicle are detected continuously or intermittently by at least one detector. A parameter (detection value) detected in advance from among the set values of the lateral acceleration that are set discontinuously or continuously, with a tendency to take a smaller value as the height of the center of gravity of the vehicle becomes higher with respect to the parameter.
Is selected according to. Instead of actually calculating the height of the center of gravity of the vehicle, the height of the center of gravity is considered indirectly by looking at a parameter that determines the height of the center of gravity. Therefore, it is possible to directly select a set value from the detected data without having to calculate the height of the center of gravity from the data detected by the detector. Further, by selectively selecting an element that is considered to have a high contribution rate in determining the height of the center of gravity by using parameters, the number of detectors can be reduced.

According to the present invention, at least one of the plurality of parameters detected by the plurality of detectors is continuously detected. The lateral acceleration set value is selected so as to change continuously according to the continuous change of the parameter. Since a finer set value of the lateral acceleration according to the height of the center of gravity of the vehicle is selected, more appropriate lock control according to the height of the center of gravity of the vehicle is realized.

According to the fifth aspect of the present invention, the lift of the loading equipment is detected by the height detector, and the load of the load on the loading equipment is detected by the load detector. Height and load 2
The set value of the lateral acceleration is selected from the two parameters. Lift and load are two of the highest contributing factors in determining the height of the center of gravity of the vehicle, so by using these two factors as parameters, finer lock control can be performed according to the height of the center of gravity of the vehicle. Is achieved.

According to the sixth aspect of the present invention, the lateral acceleration at the time of turning has a relatively slow rise, but is measured by the turning change measuring means when the driving wheel is in the turning direction in which the driving wheel is the outer wheel. When the rate of change of the yaw rate or the rate of change of the lateral acceleration at which the value at the time of turning quickly rises becomes equal to or higher than the set value, the swing regulation mechanism is activated. Therefore, the link mechanism is quickly locked without delay in timing at the start of turning.

According to the seventh aspect of the present invention, the vehicle speed is detected by the vehicle speed detector, and the physical quantity required for calculating the lateral acceleration using the vehicle speed is detected by the physical quantity detector. The lateral acceleration estimating means calculates the lateral acceleration by using the respective detected data of the vehicle speed and the physical quantity detected by the two detectors. Since the vehicle speed detector is originally provided in the vehicle, it is only necessary to add a physical quantity detector.

According to the eighth aspect of the present invention, the operation of the swing restriction mechanism is stopped after a lapse of a predetermined time from when the lock condition for operating the swing restriction mechanism is not satisfied.
Therefore, when the state near the boundary where the lock condition is satisfied / unsatisfied happens to happen, or when the measured values of the lateral acceleration and the yaw rate change rate (or the lateral acceleration change rate) are both used as parameters of the lock control, the lateral acceleration When the timing at which the rate of change of the yaw rate and the rate of change of the yaw rate become equal to or more than each set value is shifted, frequent switching that does not require control is avoided.

According to the ninth aspect of the present invention, once the swing regulation mechanism is operated, the operation of the swing regulation mechanism is operated as long as the set value at the time of operation stop is smaller than the set value at the time of operation. Is maintained. Therefore, when the state near the boundary where the lock condition is satisfied / unsatisfied happens to happen, or when the measured values of the lateral acceleration and the yaw rate change rate (or the lateral acceleration change rate) are both used as parameters of the lock control, the lateral acceleration When the timing at which the rate of change of the yaw rate and the rate of change of the yaw rate become equal to or more than each set value is shifted, frequent switching that does not require control is avoided.

According to the tenth aspect of the present invention, when the operation of the swing regulation mechanism is stopped, the regulation force adjusting means by the control means gradually reduces the regulation force which locks the link mechanism. Is controlled. As a result, since the lock of the link mechanism is gradually released, a shock is less likely to occur in the vehicle body when the lock of the link mechanism is released.

[0029]

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

As shown in FIGS. 2 and 3, a reach type forklift 1 (hereinafter referred to as a forklift) as an industrial vehicle is a three-wheeled vehicle having two front wheels and one rear wheel. The left and right front wheels 2 are driven wheels, and one rear wheel is a driving wheel 3 also serving as a steering wheel. The drive wheel 3 is offset to the left in the vehicle width direction, and an auxiliary wheel (caster wheel) 4 as a driven wheel that is paired with the drive wheel 3 on the right and left is provided to the right of the drive wheel 3.

The forklift 1 has a mast 5 in front of a vehicle body (machine stand) 1a. The mast 5 can be moved in the front-rear direction along a pair of left and right reach legs 6 extending forward of the vehicle body 1a by driving a reach cylinder (not shown). Mast 5 is outer mast 7 and inner mast 8
When the inner mast 8 is moved up and down with respect to the outer mast 7 by driving the lift cylinder 9 disposed on the outer mast 7, the lift bracket 10 is moved up and down with a stroke approximately twice as large as the stroke. Lift bracket 1
At 0, a fork 11 as a loading device used as an attachment is tiltably attached.

A driver's cab 1 of a standing type is provided on the right rear portion of the vehicle body 1a.
2 are provided. A steering wheel 14 is provided on an upper surface of a storage box 13 erected to the left of the cab 12. The instrument panel 15 on the front side of the cab 12 is provided with an operation lever 16 for cargo handling operation and accelerator operation.

FIG. 4 shows a rear suspension structure of the forklift 1. A drive unit 17 having a drive wheel 3 and a caster unit 18 having an auxiliary wheel 4 are provided at a rear portion of the vehicle body 1a with a link mechanism 2 with respect to a vehicle body frame 19 so as to allow the vehicle body 1a to swing in the roll direction.
It is suspended so as to be able to swing up and down through a zero.

The link mechanism 20 includes four links: an upper link 21, a link 22, a lower link 23, and a caster link 24. Each of the links 21 to 24 is connected by four axes 25, 26, 27, 28 located at the vertices of the quadrilateral.

The upper link 21 is disposed substantially horizontally above the driving wheel 3 and extends substantially horizontally.
Is connected to the vehicle body frame 19 rotatably. The lower arm 23 is disposed so as to extend substantially horizontally obliquely below the upper link 21, and is rotatably connected to the vehicle body frame 19 by a fixed shaft 26 located near the center thereof. A left end of the upper link 21 and a left end of the lower link 23 are connected to both ends of a substantially L-shaped link 22 extending substantially vertically by shafts 27 and 28 so as to be relatively rotatable.

As shown in FIGS. 4 and 5, the caster link 24 is disposed substantially horizontally on the lower right side of the lower link 23 and its right end is connected to a guide shaft 29 attached to the right end of the lower link 23. It is inserted and connected so as to be relatively displaceable in the vertical direction. The left end of the caster link 24 is rotatably connected to a fixed shaft 26. Lower link 23
A pair of front and rear caster springs 30 as elastic members is interposed between the caster link 24 and the caster link 24. The pair of auxiliary wheels 4 is supported on the caster link 24 via a rotation mechanism (not shown) so as to be rotatable in a horizontal plane. Thus, the caster unit 1
8 are configured. Each of the links 22 to 24 is formed in a substantially U-shape in plan view having two arms facing each other at a predetermined distance in the front-rear direction as shown in FIG. Are provided as a pair.

The drive unit 17 is configured as follows. A suspension spring 32 is interposed between the upper surface of the link 22 and the support member 31 fixed to the body frame 19, and the link 22 is urged downward with respect to the body frame 19 by the suspension spring 32. The shaft 27 connecting the upper link 21 and the link 22 is connected to a support 34 on which a drive motor 33 is mounted.

A gear box 35 is attached to the lower part of the support base 34 so as to be relatively rotatable in a horizontal plane, and the drive wheel 3 is rotatably supported by the lower part of the gear box 35. The gear wheel 36 fixed to the upper part of the gear box 35 meshes with a gear 38 at the lower end of a steering shaft 37 that rotates in conjunction with the operation of the steering wheel 14 as shown in FIG. The drive wheel 3 is steered in accordance with the rotation operation of. The steering shaft 37 is inserted into and connected to a gear box 40 operatively connected to a motor 39 for power steering. When the motor 39 is driven when the steering wheel 14 is operated, the operation force is reduced. The steering wheel 14 and the steering shaft 37 are connected to both ends of a shaft 41 connecting the steering wheel 14 and the steering shaft 37 by a universal joint.

The suspension spring 32 is provided for the purpose of pressing the driving wheel 3 against the road surface to secure the ground pressure, and has a relatively strong elastic force. On the other hand, the caster spring 30 provided for absorbing vibration from the road surface has a relatively weak elastic force as compared with the suspension spring 32. Therefore, the input of the force from the auxiliary wheel 4 is transmitted to the lower link 23 after the caster spring 30 has almost contracted to a predetermined length. However, while the caster spring 30 is contracted, the lower link 23 is slightly displaced strictly.

As shown in FIG. 4, one hydraulic damper 4 is provided between a support plate 42 extending horizontally from the support base 34 and a support member 43 extending horizontally from the body frame 19.
4 are interposed. The damper 44 comprises a double-acting hydraulic cylinder. The damper 44 connects the base end of the cylinder 44a to the support member 43 and has a piston rod 4
4b is connected to the support plate 42.

Two pipes 45 and 46 are connected to the cylinder 44a so as to communicate with two chambers partitioned by a piston 44c inside the cylinder 44a.
The opposite ends of the solenoid valves 5 and 46 are respectively connected to two ports of the electromagnetic switching valve 47. The electromagnetic switching valve 47 is
Normally closed type 2 port 2 that closes when demagnetized
It is a position switching valve. An accumulator 49 for storing hydraulic oil is connected to a pipe 48 connected to the pipe 46, and a check valve 50 is provided on the pipe 48 downstream of the accumulator 49. Further, a throttle valve 51 is provided on the pipeline 46.

When the spool of the electromagnetic switching valve 47 is switched to the shut-off position shown in FIG. 4, the flow path for the hydraulic oil in the two chambers of the cylinder 44a to move is shut off, and the damper 44
Is locked so that the piston rod 44b cannot be expanded or contracted. Further, the spool of the electromagnetic switching valve 47 is in the communication position (FIG. 4).
(A position switched to a position opposite to the position shown in FIG. 3), the two chambers of the cylinder 44a are in communication with each other so that hydraulic oil can be moved, and the damper 44 has its piston rod 44
It becomes a free (unlocked) state in which the expansion and contraction of b is allowed. In addition, the damper 44 and the electromagnetic switching valve 47 constitute a swing regulation mechanism.

When the damper 44 is not locked, the link mechanism 20 moves so that the ground pressure (wheel load) between the drive wheel 3 and the auxiliary wheel 4 is distributed at an appropriate ratio. For example, in a state where the mast 5 moves forward and the position of the center of gravity moves to the front wheel 2 side, the link mechanism 20 moves so as to lower the drive wheel 3 relatively to the vehicle body frame 19, and the drive wheel 3 Ground pressure is ensured. On the other hand, when the mast 5 is retracted and the position of the center of gravity moves to the rear wheel side, the link mechanism 20 moves so as to raise the drive wheel 3 relatively with respect to the body frame 19, and excessively touches the drive wheel 3. Part of the load is distributed to the auxiliary wheels 4 so that no pressure is applied.

As shown in FIGS. 1 and 4, the gear wheel 3
In the vicinity of 6, a steering angle sensor 52 is provided as a physical quantity detector that outputs a detection signal necessary for detecting the rotation and obtaining the steering angle (tire angle) θ of the drive wheel 3. The steering angle sensor 52 is composed of a set of magnetic sensors for detecting the rotation of the gear wheel 36 and outputting a detection signal of the number of amplitudes proportional to the amount of rotation, for example. , The two detection signals output from the respective magnetic sensors have different phase differences, for example, by １ ／ wavelength.
As the steering angle sensor, any other detection method capable of detecting the steering angle θ of the drive wheel 3 can be employed. For example, the rotation direction of the steering wheel 14 necessary for controlling the drive of the motor 39 for power steering is detected. A configuration may be employed in which the steering direction is detected by a known sensor, and the steering angle θ is detected from the steering direction and, for example, detection data of the rotation amount of the motor 39. In addition, on the upper part of the drive motor 33,
A vehicle speed sensor 54 is provided as a vehicle speed detector that detects the rotation of the brake disk 53 that rotates integrally with the drive shaft and indirectly detects the vehicle speed V.

As shown in FIGS. 1 and 2, the outer mast 7 is provided with a height sensor 55 serving as a detector and a height detector at a predetermined height. Lift sensor 55
Is provided with a lever that rotates in contact with the lower end of the inner mast 8 in this embodiment, and is turned on and off depending on the rotation position of the lever.
It is a switch type sensor provided with a limit switch to be turned off (neither is shown). The lift sensor 55 is set to turn on when the fork 11 is at a high lift higher than the set value Ho, and is turned off when the fork 11 is at a low lift below the set value Ho. ing. For example, a height approximately half of the maximum lift Hmax is set as the set value Ho. The lift cylinder 9 is connected to a detector for detecting the oil pressure inside the cylinder and a load sensor 56 as a load detector. The load sensor 56
In the present embodiment, a pressure sensor that detects the hydraulic pressure of the lift cylinder 9 outputs a detection value W according to the load of the load loaded on the fork 11. The height sensor 55 and the load sensor 56 constitute a center of gravity height measuring means.

Next, an electrical configuration of the vehicle body swing control device provided in the forklift 1 will be described with reference to FIG.
The forklift 1 includes a controller 57 as control means inside the storage box 13. The controller 57 includes a microcomputer 58, A / D conversion circuits 59 to 61, an excitation / demagnetization drive circuit 62, and the like. The microcomputer 58 includes a central processing unit (hereinafter referred to as a CP).
U) 63, a read-only memory (ROM) 64, a rewritable memory (RAM) 65, a counter 66, an input interface 67, and an output interface 68. Note that the steering angle sensor 52, the vehicle speed sensor 54, and C
The PU 63 constitutes a lateral acceleration measuring means and a turning change measuring means. The CPU 63 constitutes a lateral acceleration estimating means.

The CPU 63 receives signals from the steering angle sensor 52, the vehicle speed sensor 54, and the load sensor 56 from the AD conversion circuits 59 to 59.
Each detection signal and the height sensor 55 input through the
The data of the steering angle θ, the vehicle speed V, the load W, and the lift H are acquired based on the on / off signal input from the controller. Also,
The excitation current output from the excitation / demagnetization drive circuit 62 is turned on / off based on the control signal output from the CPU 63, so that the solenoid 47a of the electromagnetic switching valve 47 is excited / demagnetized. That is, when the lock signal is instructed from the CPU 63, the current is not output from the excitation / demagnetization drive circuit 62, and the solenoid 47a is demagnetized, the electromagnetic switching valve 47 is switched to the shut-off position. When the lock signal command is stopped from the CPU 63 and a current is output from the excitation / demagnetization drive circuit 62 to excite the solenoid 47a,
The electromagnetic switching valve 47 is switched to the communication position.

The ROM 64 stores various program data including the program data of the swing control process shown in the flowcharts of FIGS. Here, the swing control is to lock the damper 44 at a predetermined time when the centrifugal force at the time of turning of the vehicle body 1a increases,
This control is for improving the stability of the vehicle body 1a in the left-right direction. In this embodiment, the lateral acceleration G acting on the vehicle body 1a (centrifugal acceleration acting in the lateral direction of the vehicle body) G and the rate of change (yaw rate change rate) ΔY / ΔT of the yaw rate (turning angular velocity) Y when the vehicle turns are shown. The damper 44 is set to be locked at a time when one of the measured values of the lateral acceleration and the rate of change of the yaw rate is detected over time and at least one of the measured values is equal to or more than each set value.

In this embodiment, the lateral acceleration G and the yaw rate change rate ΔY / ΔT are estimated by calculation using the steering angle θ and the vehicle speed V obtained from the detection signals of the steering angle sensor 52 and the vehicle speed sensor 54. ing. The estimated value Gs of the lateral acceleration is calculated by the following equation (1) using the turning radius r determined from the steering angle θ.

Gs = V ² / r (1) Further, the yaw rate change rate ΔY / ΔT is calculated by the following equation (2) using two detected values θ and V.

ΔY / ΔT = V · {Δ (1 / r) / ΔT} (2) where r is a turning radius of the vehicle determined from a steering angle θ using a map MR described later, and Δ (1 / r) is a change amount (deviation) per predetermined time ΔT (for example, several tens of milliseconds) of the reciprocal value 1 / r of the turning radius. The deviation Δ (1 / r) is R
The steering angle data θ1 before the predetermined time ΔT is read out from the steering angle data θ of a plurality of past times (the predetermined time ΔT is one time) stored in the AM 65 and the turning radius r1 determined from the data θ1 is used to obtain Δ ( 1 / r) = | 1 / r-1 / r1
|.

Incidentally, the yaw rate change rate ΔY / ΔT
Is expressed by the following equation by time-differentiating the equation Y = V / r representing the yaw rate Y. ΔY / ΔT = V · ｛Δ (1 / r) / ΔT｝ + (1 / r) · ｛ΔV / ΔT｝ (3) While the forklift 1 is turning, the vehicle speed V at the time ΔT can be regarded as substantially constant. Therefore, in the present embodiment, the expression (2), which is an approximate expression ignoring the latter term in the expression (3), is expressed as Δ
This is adopted as an arithmetic expression for estimating the Y / ΔT value.

The ROM 64 stores a map MR shown in FIG. 8 for obtaining the turning radius r of the vehicle from the steering angle θ. In the present embodiment, the driving wheels 3 that are the steering wheels
In consideration of the fact that is offset in the vehicle width direction, two types of map lines R and L for right turn and left turn are prepared in order to obtain the turning radius r from the steering angle θ. For example, when the steering angle θ = θ1, the turning radius r _R is determined at the time of the right turn when the driving wheel 3 becomes the outer wheel, and the turning radius r is smaller than the r _R value at the time of the right turn when the auxiliary wheel 4 turns the outer wheel as the outer wheel. _L is determined.
Therefore, the estimated values of the lateral acceleration Gs and the rate of change of the yaw rate ΔY / ΔT can be correctly calculated using the steering angle data θ.

FIGS. 9A and 9B are graphs showing lock conditions for locking the damper 44. FIG. 9A shows a lock condition for the lateral acceleration, and FIG. 9B shows a lock condition for the yaw rate change rate ΔY / ΔT. As shown in FIG. 9, the condition for locking the damper 44 differs depending on whether the turning direction of the vehicle is left or right. Each graph shows the difference in the turning direction as the difference in the direction in which the lateral acceleration acts, and the horizontal axis shows the direction of the lateral acceleration.

As shown in FIG. 9A, when turning right (when the driving wheel 3 becomes an outer wheel) when a lateral acceleration in the left direction occurs, the damper 44 is locked as early as possible during the turning. ing. On the other hand, when turning left (when the auxiliary wheel 4 becomes the outer wheel) when lateral acceleration occurs in the right direction, the centrifugal force causes the vehicle body 1a to tilt rightward and the caster spring 30 almost contracts to a predetermined length. Damper 4 at timing
4 is set to be locked. That is, while the lateral acceleration Gs is smaller than the lateral acceleration Gc when the caster spring 30 is almost contracted to a predetermined length, the damper 44 is not used.
Is not locked. The lateral acceleration Gc is a value determined according to the elastic coefficient of the caster spring 30 used.

Also, as shown in FIG. 9B, when turning right (when the driving wheel 3 becomes an outer wheel) when the vehicle is subjected to a leftward lateral acceleration, the yaw rate change rate ΔY / ΔT is taken into consideration. When the detected value ΔY / ΔT exceeds the set value yo, the damper 44 is locked. The reason that the yaw rate change rate ΔY / ΔT is used as a parameter for determining the lock is that while the lateral acceleration rises slightly behind the turning start timing, the yaw rate change rate ΔY / ΔT is used to check the yaw rate change rate ΔY / ΔT so that the damper can be quickly operated after the turning start. This is because the lock 44 is locked. On the other hand, at the time of a left turn where a lateral acceleration in the right direction is applied, the yaw rate change rate ΔY / ΔT is not taken into consideration so that the damper 44 is not locked until the caster spring 30 is almost contracted to a predetermined length.

A map M1 shown in FIG.
Is stored. The map M1 is for determining the set value of the lateral acceleration. The higher the height of the center of gravity of the vehicle with the load W and the lift H as parameters, the smaller the set value of the lateral acceleration is determined as the tendency. Stipulated. In particular, in the present embodiment, as shown in FIGS. 10A and 10B, the load W is low (W <Wo) or high (W <Wo).
.Gtoreq.Wo) and the set value of the lateral acceleration is divided into four combinations of whether the lift H is a low lift (H <Ho) or a high lift (H.gtoreq.Ho). I have.

In FIG. 10, a map line GL for turning right (lateral acceleration in the left direction) and a map line GR for turning left (lateral acceleration in the right direction) are prepared in the map M1.
According to the right turn map line GL, even if the left turn map line GR is in the lock area, the lateral acceleration Gs is equal to Gc.
When the value is less than the value, a free area is created. In this example, the set value of the lateral acceleration at the time of turning left when the load is low and the lift is high, in which such a situation occurs, is indicated by a broken line in FIG. It is set as shown by. In other cases, the lateral acceleration set values are set in three steps for each turning direction so that an appropriate lateral acceleration set value corresponding to the height of the center of gravity is selected using the load W and the lift H as parameters. Is set with That is, when the load is low as shown in FIG. 10 (a), the set value of the lateral acceleration at the time of turning right at high elevation is G
1. The set value of the lateral acceleration when turning left is set to Gc, and the set value of the lateral acceleration is set to G2 in both left and right turning directions at low elevation.
(However, G2> G1). FIG.
In the case of a high load shown in (b), the set value of the lateral acceleration is set to G2 in both the left and right turning directions when the lift is low, and the set value of the lateral acceleration is set to “0” in both the left and right turns when the lift is high. Have been. That is, in this example, the damper 44 is always locked when the load is high and the lift is high. Here, when the set value of the lateral acceleration is the height of the center of gravity defined by G2, when the estimated value Gs of the lateral acceleration reaches G2, the caster spring 30 has already contracted completely, so that the locking timing in the left and right turning directions is locked. Become the same. Note that the lateral acceleration until the caster spring 30 is almost contracted to a predetermined length slightly differs depending on the height of the center of gravity. Strictly speaking, the value Gc decreases as the height of the center of gravity increases. Further, even in the case of a high load and a high lift, the set value of the lateral acceleration exceeds “0” in the allowable range even if the caster spring 30 is almost contracted to a predetermined length during the left turn, or even if not completely contracted. Can also be set to a value.

The CPU 63 sets three flags Fg, Fy, F
L is provided. The flag Fg is a set value (G1, G1) at which the lateral acceleration Gs is set according to the load W, the lift H, and the turning direction.
G2, G3, and G4), and is reset at other times. The flag Fy is set when the yaw rate change rate ΔY / ΔT is equal to or larger than the set value yo during the right turn, and is reset at other times. Further, the lock flag FL is set while the damper 44 is locked, and is reset while the damper 44 is unlocked.

As shown in FIG. 11, the lock of the damper 44 is released by releasing the lock condition (lock condition is not satisfied).
Is performed only when the state described above continues for a predetermined time T.
The duration of the lock condition released state is counted by the counter 66.

Next, the swing control process will be described with reference to FIG.
The description will be made according to the flowchart of FIG. While the ignition key is on, the CPU 63 sets the sensors 52, 5
4, 55 and 56, the detection signals are input. The CPU 63 performs swing control processing at predetermined time intervals (for example, several tens of milliseconds) based on data of the steering angle θ, the vehicle speed V, the lift H, and the load W obtained from the detection signals from the sensors 52, 54, 55, 56. Execute

First, in step 10, the CPU 63 reads the steering angle θ, the vehicle speed V, the lift H, and the load W, which are detection data. In step 20, an estimated value Gs of the lateral acceleration is calculated. That is, the turning radius r is determined from the steering angle θ using the map MR stored in the ROM 64, and the estimated value Gs of the lateral acceleration is calculated from the vehicle speed V and the turning radius r using the equation (1).

In step 30, the yaw rate change rate ΔY
/ ΔT is calculated. That is, the steering angle data θ1 before the predetermined time ΔT is read from the predetermined storage area of the RAM 65, and Δ (1 / r) is calculated using the turning radius r1 determined from the data θ1 and the turning radius r determined from the current steering angle data θ. )
= | 1 / r-1 / r1 |, and ΔY /
Calculate ΔT.

In step 40, the current turning direction is determined. The turning direction is determined from the steering angle θ. A right turn is determined when the vehicle is turning left, and a left turn is determined when the vehicle is turning right.
However, when the vehicle is in a straight running posture with a turning angle of 0 °, it is regarded as a right turn in this example. When turning right, proceed to step 50,
When the vehicle turns left, the process proceeds to step 100.

When turning right, first, at step 50,
With reference to the map M1 based on the lift H and the load W, a set value GL of the lateral acceleration according to the height of the center of gravity (= 0) using the map line GL for right turning and using the lift H and the load W as parameters. , G
1, G2). In the next step 60, ΔY
It is determined whether / ΔT is equal to or greater than the set value yo. ΔY
If / ΔT ≧ yo is satisfied, the routine proceeds to step 70, where the flag Fy is set. If ΔY / ΔT ≧ yo is not established, the routine proceeds to step 80, where the flag Fy is reset.

In the next step 90, it is determined whether or not the lateral acceleration Gs is equal to or larger than the set value GL. If Gs ≧ GL holds, the routine proceeds to step 120, where the flag Fg is set. If Gs ≧ GL does not hold, the routine proceeds to step 130, where the flag Fg is reset.

When turning left, first, at step 100, the map M1 is referred to from the height H and the load W, a map line GR for left turning is used, and the center of gravity is set using the lift H and the load W as parameters. Set value GR of lateral acceleration according to height
(= 0, Gc, G2). In the next step 110, it is determined whether or not the lateral acceleration Gs is equal to or greater than the set value GR. If Gs ≧ GR is satisfied, the routine proceeds to step 120, where the flag Fg is set. If Gs ≧ GR is not established, the routine proceeds to step 130, where the flag Fg is reset. As described above, the lock condition is different between the right turn and the left turn. At the time of turning left, the flag Fy is reset.

In step 140, it is determined whether at least one of the flags Fy and Fg has been set. That is, it is determined whether or not the lock condition is satisfied.
If the lock condition is satisfied, the routine proceeds to step 150, where a lock signal is commanded. As a result, the spool of the electromagnetic switching valve 47 is switched to the shut-off position, and the damper 44 is locked.
On the other hand, if the lock condition is not satisfied, the routine proceeds to step 160.

In step 160, it is determined whether or not a switch has been made from lock to unlock. If the CPU 63 is currently in the locked state and the lock flag FL is set, the CPU 63 determines that the operation has been switched from locked to unlocked. If it is a switch from lock to unlock, the process proceeds to step 170, where the count value K of the counter 66 is calculated.
Is incremented (K = K + 1). Counter 66
Is reset, for example, when the damper 44 is switched from unlocked to locked. On the other hand, when it is not the switching from the lock to the unlock, the process proceeds to step 190.

At step 180, it is determined whether or not the time counted by the counter 66 has exceeded a predetermined time T. That is, it is determined whether or not the lock condition release state (the flags Fg and Fy are both reset states) has continued for the predetermined time T. When it is determined that the predetermined time T has elapsed from the count value K of the counter 66, the process proceeds to step 190. In step 190, the command of the lock signal is stopped. As a result, the spool of the electromagnetic switching valve 47 is switched to the communication position, and the damper 44
Is unlocked. As described above, when switching from the lock state to the unlock state, the lock is not immediately released at the same time as the release of the lock condition, but the lock release of the damper 44 is performed after the lock condition release state continues for a predetermined time T. .

FIG. 14 shows a lateral acceleration (lateral acceleration) Gs and a yaw rate change rate ΔY in a state of low load and high elevation in which the lock timing of the damper 44 is different in the left-right turning direction.
6 is a graph showing a change in / ΔT. For example, FIG.
As shown in the figure, when the vehicle turns right from straight ahead during traveling, the yaw rate change rate ΔY before the lateral acceleration reaches the set value G1.
/ ΔT exceeds the set value yo, so that the damper 4
4 is locked. In other words, the damper 44 is locked almost immediately at the start of turning. Therefore, when turning right, as shown in FIG. 15A, the damper 44 is locked when the vehicle body 1a starts turning right and is still in a substantially horizontal posture, and the yaw rate change rate ΔY / ΔT exceeds the set value yo. While the value is being taken, the lateral acceleration Gs becomes equal to or greater than the set value G1 at a slightly delayed timing, so that the damper 44 is kept locked. Therefore, during the right turn, the relationship between the vehicle body frame 19 and the link mechanism 20 is maintained in a fixed state in the substantially horizontal posture shown in FIG. While the link mechanism 20 remains fixed to the vehicle body frame 19, the vehicle body 1a leans to the left due to the centrifugal force at the time of turning right, but the auxiliary wheels 4 may slightly rise from the road surface. Also, the ground pressure of the drive wheel 3 is ensured.

Thereafter, when turning the steering wheel (steering wheel) 14 from right turn to left turn as shown in FIG. 14 (a), the lateral acceleration Gs is turned in the direction just before the vehicle body 1a is in the straight traveling posture. In the replacement section, the value is momentarily less than the set value G1. However, since the yaw rate change rate ΔY / ΔT takes a value equal to or larger than the set value yo during the turning in the turning direction, the lock of the damper 44 is continued until the vehicle reaches the straight traveling posture. Then, when the vehicle is switched to the left turn after passing the straight traveling posture, the yaw rate change rate ΔY / ΔT is not used as a parameter for determining the lock control.
4 is released.

Then, the vehicle body 1a leans to the right due to the lateral acceleration in the right direction due to the left turn, and as shown in FIG. 15B, the estimated value Gs of the lateral acceleration Gs at the time when the caster spring 30 has almost contracted to a predetermined length. Reaches the set value Gc, and the damper 44 is locked. The vehicle body 1a tilts slightly to the right before the caster spring 30 almost contracts to a predetermined length. In this process, since the link mechanism 20 is not yet locked, even if the vehicle body 1a tilts slightly to the right, the driving wheels 3 and the auxiliary wheels 4 The ground pressure of the drive wheels 3 is ensured by moving the link mechanism 20 so as to distribute the ground pressure (wheel load) with the appropriate ratio. That is, the drive wheel 3 is displaced downward with respect to the vehicle body frame 19, and the ground pressure is secured.

Then, only when the vehicle body tilts further rightward from the vehicle body posture when the damper 44 is locked, the link mechanism 20
Is fixed to the body frame 19. Therefore, the vehicle body 1a
Even if the vehicle is further tilted right after the damper 44 is locked, a decrease in the ground pressure of the drive wheels 3 is suppressed to a small degree, depending on the right tilt angle of the vehicle body 1a at that time, and a relatively high ground pressure is secured for the drive wheels 3. Therefore, although the ground pressure of the drive wheels 3 is slightly reduced, there is no fear that the acceleration may be slowed down due to slippage, or the braking effect or the steering performance may be adversely affected.

In this embodiment, the timing for locking the link mechanism 20 is delayed as compared with the conventional device. However, in the conventional device, even if the link mechanism is locked early, the sinking of the vehicle body 1a into the auxiliary wheels 4 still occurs until the caster spring contracts to a predetermined length. As such, it was not very effective for the stability of the body. Therefore, until the caster spring 30 is fully contracted to a predetermined length, the damper 44
Is delayed, the stability of the vehicle body 1a is not sacrificed so much.

Then, the damper 44 is locked after the caster spring 30 has almost contracted to a predetermined length, so that the link mechanism 20 is fixed to the vehicle body frame 19, and the vehicle body 1a rotates in the roll direction with respect to the link mechanism 20. Movement is stopped. Therefore, the amount of inclination of the vehicle body 1a may be smaller than the force acting in the lateral direction of the vehicle body 1a. As a result, the left and right stability of the vehicle body is ensured while suppressing a decrease in the ground pressure of the drive wheels 3.

On the other hand, as shown in FIG. 14 (b), when the vehicle turns left from straight ahead during traveling, the lateral acceleration is reduced when the caster spring 30 is almost contracted to a predetermined length as shown in FIG. 15 (b). Reaches the set value Gc, and the damper 44 is locked. In the process in which the vehicle body 1a leans slightly right until the caster spring 30 almost contracts to a predetermined length, the link mechanism 20 moves so as to distribute the ground pressure (wheel load) between the drive wheel 3 and the auxiliary wheel 4 at an appropriate ratio. Thereby, the ground pressure of the drive wheel 3 is ensured. Caster spring 3
Since the damper 44 is locked after 0 has almost completely shrunk, even if the vehicle body 1a further tilts rightward, a decrease in the contact pressure of the drive wheels 3 is relatively small. as a result,
Left and right stability of the vehicle body 1a is ensured while suppressing a decrease in the contact pressure of the drive wheels 3.

Thereafter, the steering wheel 14 is turned from left turning to right turning.
When the estimated value Gs of the lateral acceleration becomes smaller than the set value Gc, the lock of the damper 44 is released. The damper 44 is unlocked with a delay of a predetermined time T from the release of the lock condition, but since it is an extremely short time, there is not much delay in timing. After the lock of the damper 44 is released, the contraction of the caster spring 30 gradually recovers while the link mechanism 20 moves so as to distribute the ground pressure (wheel load) between the drive wheel 3 and the auxiliary wheel 4 at an appropriate ratio. ,
The vehicle body 1a returns to the horizontal position.

During the left turn, the yaw rate change rate ΔY / ΔT
Is not taken into account, so that the
The unlocked (free) state of is continued. When the vehicle is in the straight traveling posture, the yaw rate change rate ΔY / ΔT has already become equal to or greater than the set value yo, so that the damper 44 is quickly locked almost simultaneously with the right turn when the vehicle body 1a is in a substantially horizontal posture. You. Yaw rate change rate ΔY / ΔT
Is greater than or equal to the set value yo, and the lateral acceleration Gs is equal to or greater than the set value G1.
As described above, the lock of the damper 44 is continued.

The unlocking of the damper 44 is executed with a delay of a predetermined time T from the time when the lock condition is not satisfied. Therefore, when the lock should be continued due to a slight difference in timing between the change of the ΔY / ΔT value and the Gs value at the start of the right turn, even if both of the flags Fy and Fg are reset, the lock of the damper 44 is prevented. Is continued. In addition, even if the estimated value Gs of the lateral acceleration happens to take a value near the set value G1, Gc, G2 at the time of turning, and the value Gs fluctuates up and down around the set value at that time, the damper does not The lock at 44 is continued. Therefore, the occurrence of unnecessary frequent switching between lock and unlock due to the fact that the lateral acceleration Gs happens to take a value near the set value at that time is also prevented.

In this embodiment, the set value of the lateral acceleration is selected stepwise according to the height of the center of gravity of the vehicle, using both the detected values of the load W and the lift H as parameters. Therefore, when the load is other than the heavy load (W ≧ Wo) and the high lift (H ≧ Ho) in which the damper 44 is always locked, the set value of the lateral acceleration for each turning direction is set in two steps according to the respective height of the center of gravity. Selected. By the way, if the set value of the lateral acceleration is uniformly set to a constant value without considering the height of the center of gravity, the height of the center of gravity is the highest so that it is OK even when the constant set value is high. For example, it is necessary to set G1 on the basis of time. In this case, unnecessary lock of the damper increases when the height of the center of gravity is relatively low. On the other hand, in the present embodiment in which the set value is determined according to the height of the center of gravity using the load W and the lift H as parameters, the area sandwiched between G1 and G2 in the free area in FIG. It means that it increased. Therefore, unnecessary lock of the damper 44 is relatively reduced as compared with the case where the set value of the lateral acceleration is a constant value that does not consider the height of the center of gravity.

By reducing unnecessary lock of the damper 44,
Stable traveling due to the movement of the link mechanism 20 is not unnecessarily impaired. Further, since the damper 44 is locked while the front wheel 2 is traveling on an uneven road surface with the vehicle weight being applied, it is relatively unlikely that the drive wheel 3 is lifted off the road surface and slips.

As described in detail above, according to the present embodiment,
The following effects can be obtained. (1) The lock condition for locking the damper 44 is different between the right turn and the left turn, and the damper 44 is locked after the caster spring 30 has almost contracted to a predetermined length during the left turn. The left and right stability of the vehicle body 1a can be ensured while keeping the ground pressure of the drive wheel 3 from decreasing during the left turn as small as possible. Therefore, it is possible to eliminate the concern that the ground contact pressure of the drive wheel 3 decreases during the left turn, for example, the occurrence of inconveniences such as slowdown of acceleration, difficulty of braking, and deterioration of steering performance.

(2) The set value of the lateral acceleration used for determining whether or not the damper 44 should be locked is appropriately set according to the height of the center of gravity of the vehicle using the load W and the lift H as parameters. Unnecessary lock of the damper 44 can be reduced because the value is selected and changed stepwise according to the height of the center of gravity. Therefore, the running stability due to the roll direction swing of the vehicle body 1a due to the movement of the link mechanism 20 is hardly impaired due to the unnecessary lock, and the damper 44 is locked while the front wheel 2 is under the vehicle weight. Can reduce the slip caused.

(3) Since the yaw rate change rate ΔY / ΔT is added to one of the parameters for determining whether or not to lock the damper 44, the damper 44 can be quickly locked at the start of the right turn, and can be locked at the right turn. Of the vehicle body 1a due to the centrifugal force can be suppressed as small as possible.

(4) The load W and the lift H are used as parameters so that a more appropriate set value of the lateral acceleration according to the height of the center of gravity of the vehicle can be determined, so that the height of the center of gravity does not have to be actually calculated.

(5) Since the lock release of the damper 44 is executed after the lock condition release state has continued for the predetermined time T, unnecessary switching between lock and unlock can be prevented. For example, even if the yaw rate change rate ΔY / ΔT and the change in the lateral acceleration Gs slightly shift at the start of the right turn, the damper 44 can be kept locked and the body posture during the right turn can be stably maintained. it can.
Further, even when the estimated value Gs of the lateral acceleration happens to take a value near the set value (G1, Gc, G2) at the time of turning, frequent switching of the lock / unlock of the damper 44 can be avoided. it can.

(6) Since the lateral acceleration Gs and the yaw rate change rate ΔY / ΔT are calculated using the detected data of the steering angle θ and the vehicle speed V, a comparatively high acceleration sensor such as an acceleration sensor for directly detecting the lateral acceleration is used. There is no need to provide an expensive detector. In particular, the vehicle speed sensor 54 originally attached to the forklift 1 can be used, and the use of sensors can reduce the cost of the apparatus relatively.

(7) Since the calculation is performed using the detected data of the steering angle θ and the vehicle speed V, only the lateral acceleration Gs during turning can be estimated. Therefore, the right and left sway of the vehicle body 1a due to the uneven road surface during straight running is reliably absorbed since the estimated value Gs is not detected at this time and the damper 44 is not locked.

(8) Since the drive wheel 3 is offset in the vehicle width direction and the turning radius r differs depending on the turning direction even when the detected data of the steering angle θ is the same, the map MR is prepared. The estimated value Gs and the yaw rate change rate ΔY / ΔT can be accurately obtained, and a highly accurate swing control can be realized.

(9) For example, if the configuration is such that the lateral acceleration is directly detected using an acceleration sensor, the detection value (lateral acceleration value) detected by the acceleration sensor includes noise such as vibration of the vehicle body 1a. Even if an attempt is made to obtain the yaw rate change rate ΔY / ΔT using the (differentiated) processed value, noise is amplified by the differential processing, and the reliability of the estimated value ΔY / ΔT becomes poor. On the other hand, according to the present embodiment,
Since the value 1 / r obtained from the steering angle data θ that is hardly affected by the vibration of the vehicle body 1a detected by the steering angle sensor 52 is differentiated (differentiated), the highly reliable estimated value ΔY / ΔT
Can be obtained.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS.
This embodiment is an example in which the set value of the lateral acceleration is set by continuously changing according to the change in the height of the center of gravity of the vehicle. Since the configuration is the same as that of the first embodiment except that the sensor used for the swing control is partially changed, the same members are denoted by the same reference numerals and description thereof will be omitted.

As shown in FIG. 16, in this embodiment, a lift sensor 70 capable of continuously detecting the height of the fork 11 is used instead of the switch-type sensor used in the first embodiment as a lift detector. You are using The lifting height sensor 70 is disposed near the lower part of the mast 5 and detects, as the rotation amount, a winding amount of a reel that winds a wire having one end connected to the lift bracket 10 while being urged in the winding direction. This is a reel type that detects the lift H. FIG.
As shown in FIG. 7, the detection signal of the elevation sensor 70 is input to the controller 57 and is input to the CPU 63 in the microcomputer 58 via the AD conversion circuit 71. As the lift sensor 70, any other sensor that can continuously detect the lift H can be used, such as an ultrasonic sensor that continuously detects the position of the piston of the lift cylinder 9 or the like. Can also be used. The height sensor 70 and the load sensor 56 constitute a center-of-gravity height measuring means, and the height sensor 70 makes the detector and the height detector fair.

The ROM 64 stores a map M2 shown in FIGS. 18 (a) and 18 (b). In the map M2, (a) and (b) are selectively used depending on whether the detection value W of the load sensor 56 is less than Wo or more than Wo. The map M2 is a map in which the set value of the lateral acceleration is continuously changed with respect to the height H of the two parameters, and is created so that an appropriate value corresponding to the height of the center of gravity can be selected more finely. Have been.

The map M2 includes two maps for turning right and turning left.
Various types of map lines GL and GR are prepared. As shown by the broken line in FIG. 18, the caster spring 30 has a left turn map line GR, as shown by a broken line in FIG. 18, even in a region where the right turn map line GL is locked at a lateral acceleration Gs less than the lateral acceleration Gc. Is set so as not to be locked until it reaches the lateral acceleration Gc at which it is almost contracted to a predetermined length. When the load is high and the load W ≧ Wo is satisfied, and the lift H is high and the lift H ≧ H1 is satisfied, the damper 44
Is always locked. The region of high load and high lift also shifts to the higher lift side and becomes a smaller region as compared with the first embodiment.

According to this embodiment, the CPU 63 uses the load W and the lift H obtained from the respective detection signals from the load sensor 56 and the lift sensor 70 as parameters, and uses the map M2 in FIG.
And select the set value of the lateral acceleration. At this time, since the set value of the lateral acceleration is set to be substantially continuously changed with respect to the parameter of the lift H, a more appropriate set value of the lateral acceleration according to the height of the center of gravity is more finely selected. Therefore, the effects (1) to (9) described in the first embodiment can be obtained in the same manner, and particularly in the effect (2) among them, the damper 44 can be provided as compared with the configuration of the first embodiment. Unnecessary lock can be further reduced.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIG. The second
In the embodiment, the setting value of the lateral acceleration is set to be continuously changed with respect to the parameter of the height H, but in this embodiment, the setting value of the lateral acceleration is set to be changed continuously with respect to the parameter of the load W. This is an example. It should be noted that the present invention can be applied to any of the configurations of the first and second embodiments except that the map for selecting the set value of the lateral acceleration used for the swing control is different. That is, it is sufficient that at least the load sensor 56 can continuously detect the load W.

The map M3 shown in FIGS. 19A and 19B is stored in the ROM 64. The map M3 uses (a) and (b) depending on whether the detected value H of the height sensor 55 (70) is less than Ho or more than Ho. Map M3 is 2
Among the three parameters, the set value of the lateral acceleration is continuously changed with respect to the load W, and is set so that an appropriate value according to the height of the center of gravity is more finely selected.

[0099] The map M3 includes two maps for turning right and turning left.
Various types of map lines GL and GR are prepared. As shown by a broken line in FIG. 19, the caster spring 30 has a left turn map line GR in a region where the right turn map line GL is locked at a lateral acceleration Gs less than the lateral acceleration Gc. Is set so as not to be locked until it reaches the lateral acceleration Gc at which it is almost contracted to a predetermined length. When the lift H is high and the load W ≧ W1 is high, the damper 44
Is always locked. The region of high load and high lift is shifted to a higher load side and becomes a smaller region as compared with the first embodiment. The load Wmax is the maximum load.

According to this embodiment, the CPU 63 uses the load W and the lift H obtained from the respective detection signals from the load sensor 56 and the lift sensor 55 (70) as parameters and refers to the map M3 in FIG. Select the acceleration setting. At this time, since the set value of the lateral acceleration is set to be substantially continuously changed with respect to the parameter of the load W, a more appropriate set value of the lateral acceleration according to the height of the center of gravity is more finely selected. For this reason, (1) to (1) described in the first embodiment.
The effect of (9) can be obtained in the same manner, and particularly in the effect of (2), unnecessary lock of the damper 44 can be further reduced as compared with the configuration of the first embodiment.

(Fourth Embodiment) Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG. This embodiment is an example in which the set value of the lateral acceleration changes continuously with respect to the two parameters of the lift H and the load W.

In this embodiment, similar to the second embodiment,
A reel type height sensor 70 is used as a height detector, and the load sensor 56 is used as a load detector. That is, the load W and the lift H are continuously detected by the sensors 56 and 70, respectively. In addition, as the lift sensor 70, other sensors capable of continuous detection, such as the ultrasonic sensor described in the second embodiment, can be used. Of course, other sensors capable of continuous detection can be used for the load sensor 56.

The ROM 64 stores a three-dimensional map M4 shown in FIG. The map M4 is set by changing the set value of the lateral acceleration continuously for each of the two parameters of the load W and the height H. Therefore, an appropriate value corresponding to the height of the center of gravity is created so as to be selected even more finely than in the second and third embodiments. For this reason, the free area is secured wider than in the second and third embodiments.

The map M4 includes two maps for right turn and left turn.
Various types of map planes GL and GR are prepared. The map area GR for left turning has a lateral acceleration Gs as shown by a broken line in FIG. 20, even in an area where the map plane GL for right turning is locked at a lateral acceleration Gs less than the lateral acceleration Gc.
Is set so as not to be locked until the caster spring 30 reaches a lateral acceleration Gc at which the caster spring 30 almost contracts to a predetermined length. In addition, when the lift H is higher than H2 and the load W is higher than Wo, the damper 44 is always locked.

According to this embodiment, the CPU 63 uses the load W and the lift H obtained from the respective detection signals from the load sensor 56 and the lift sensor 70 as parameters to obtain the map M4 in FIG.
And select the set value of the lateral acceleration. At this time, since the set value of the lateral acceleration is set to change almost continuously for each of the parameters of the lift H and the load W,
The optimum set value of the lateral acceleration for the height of the center of gravity at that time is selected. Therefore, the effects (1) to (9) described in the first embodiment can be obtained in the same manner, and particularly in the effect (2), unnecessary lock of the damper 44 is further reduced and almost eliminated. be able to.

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described with reference to FIGS.
This embodiment is different from the above embodiments in that an electromagnetic proportional valve is used in place of the electromagnetic switching valve 47 to adjust the opening. Except that the electromagnetic switching valve used for the swing control is changed to an electromagnetic proportional valve, the configuration is the same as that of the first embodiment, and the same members are denoted by the same reference numerals and description thereof will be omitted.

As shown in FIG. 21, the two pipe lines 45 and 46 connected to the cylinder 44a of the damper 44 are connected to two ports of an electromagnetic proportional valve 75 as regulating force adjusting means. The CPU 63 in the controller 57 controls the solenoid 7 of the electromagnetic proportional valve 75 by duty value control, for example.
The current flowing to 5a is controlled to adjust the opening of the electromagnetic proportional valve 75. Note that a swing regulation mechanism is constituted by the damper 44, the electromagnetic proportional valve 75, and the like.

As shown in FIG. 22, when the lock condition is satisfied, the CPU 63 outputs a lock signal to output the lock signal to the solenoid 75a.
The electric current to the solenoid valve is immediately reduced, and the electromagnetic proportional valve 75 is completely closed promptly. Further, when releasing the lock condition, the CPU 63 stops the output of the lock signal, gradually increases the current to the solenoid 75a, and gradually opens the electromagnetic proportional valve 75 from the fully closed state to the fully opened state at a substantially constant rate. It is set as follows.

Therefore, according to this embodiment, the damper 4
When the lock of 4 is released, the electromagnetic switching valve 75 is gradually closed from full open to full close, so that when the lock of the link mechanism 20 is released, a shock does not easily occur in the vehicle body 1a.
Therefore, even if the vehicle body 1a is unlocked during a turn, the vehicle body 1a can be prevented from becoming unstable due to a shock at the time of unlocking.

(Sixth Embodiment) Next, a sixth embodiment of the present invention will be described with reference to FIGS.
This embodiment is different from the above embodiments in that the setting value used for the swing control is different between when the damper 44 is locked and when the lock is released. The configuration is the same as that of the first embodiment except that the content of the swing control is partially changed.

As shown in FIG. 23, when the damper 44 is locked (when the flag Fy is set), “yo” is used as the set value for ΔY / ΔT, and when the damper 44 is unlocked ( When the flag Fy is reset, the set value “α · yo” slightly smaller than “yo” (for example,
0.5 <α <1) is used.

Further, as shown in FIG. 24, the lateral acceleration Gs
"G1", "G2", "Gc" when the damper 44 is locked (when the flag Fg is set).
Are used to release the lock of the damper 44 (when the flag Fg is reset), "G1" and "G2".
The set values “α · G1”, “α · G2”,
“Α · Gc” (for example, 0.5 <α <1) is used.

Therefore, once the damper 44 is locked, α slightly smaller than the set value at that time (for example, 0 <
The lock is not released until the value falls below the set value of α <1). Therefore, for example, the yaw rate change rate ΔY / ΔT
Of the lock / unlock which happens to take place around the set value yo or the lateral acceleration Gs happens to take place near the set value G1, G2, Gc. . Therefore, the lock control of the damper 44 can be stably performed.

Note that the embodiment is not limited to the above, and can be modified as follows. ○ 2 for lift H and load W as in the first embodiment
The method is not limited to the method of setting the set value of the lateral acceleration divided into stages. At least one may be divided into three or more stages. When the height H is divided into three or more stages, a height sensor 70 capable of continuously detecting the height H may be used. For example, a plurality of switch-type height sensors 55 may be used.
May be used.

The height of the center of gravity h using the lift H and the load W
Alternatively, a method of calculating w and determining the set value of the lateral G according to the height of the center of gravity hw may be adopted. The method of determining the set value of the lateral acceleration from the height of the center of gravity hw may be a map or a calculation. According to this method, in the fourth embodiment, FIG.
Since a two-dimensional map representing the relationship between the height of the center of gravity hw and the set value of the lateral acceleration can be used instead of the map M4 shown in FIG. 0, the process for determining the set value of the lateral acceleration can be simplified. In this configuration, each sensor for detecting the lift H and the load W and the CPU 63 constitute a center of gravity height measuring means.

In each of the above embodiments, instead of using a map, a method of calculating a set value of the lateral acceleration from each of the detected values w and H may be adopted. With this configuration, it is only necessary to store the calculation formula. For example, since it is not necessary to store a relatively complicated three-dimensional map as shown in FIG. 20, it is possible to save the trouble of creating the map and to reduce the amount of data that needs to be stored in advance for swing control. .

The region where the damper 44 set at the time of a heavy load and a high lift may be always locked may be eliminated. That is, the control is such that the damper 44 is locked when the lateral acceleration Gs exceeds the set value of the lateral acceleration determined by the parameters W and H (however, a value larger than "0") in any area.

The parameters for determining the height of the center of gravity of the vehicle are not limited to the lift H and the load W. Other factors that determine the height of the center of gravity can be used as parameters. For example, if the height of the center of gravity is affected by the tilt angle of the mast 5, the tilt angle can be used as one of the parameters.

It is not always necessary to use both the lift H and the load W as parameters for determining the height of the center of gravity of the vehicle. A method of setting the lateral acceleration using only one of the lift H and the load W as a parameter for determining the height of the center of gravity of the vehicle may be used. With this configuration, it is also possible to select a set value of the lateral acceleration according to the height of the center of gravity of the vehicle.

The lateral acceleration change rate ΔG / ΔT may be adopted instead of the yaw rate change rate ΔY / ΔT used in each of the above embodiments. The lateral acceleration change rate ΔG / ΔT is calculated from the following equation using the respective detection data of the steering angle sensor 52 and the vehicle speed sensor 54.

ΔG / ΔT = V 2 · Δ (1 / r) / ΔT (4) Here, Δ (1 / r) / ΔT is the time of the reciprocal value 1 / r of the turning radius determined from the steering angle data θ. This is the difference (time derivative). In step 30 shown in FIG. 12, the lateral acceleration change rate ΔG / ΔT is calculated using the above equation (9), and in step 60, it is determined whether or not ΔG / ΔT ≧ go. When the lateral acceleration change rate ΔG / ΔT is adopted, the same effect as when the yaw rate change rate ΔY / ΔT is adopted can be obtained. In the above embodiments, the yaw rate change rate ΔY / ΔT
In order to calculate the vehicle speed V, a calculation formula is used in which the vehicle speed V is regarded as constant and the time difference term (time derivative term) of the vehicle speed V is ignored.
On the other hand, a calculation formula considering the time difference term (time differentiation term) of the vehicle speed V may be used. For example, any of the following equations can be used.

ΔY / ΔT = V · ｛Δ (1 / r) / ΔT｝ + (1 / r) · ｛ΔV / ΔT｝ (3) ΔY / ΔT = Δ (V / r) / ΔT (5) Here, ΔV / ΔT is a time difference (time differential) of the vehicle speed V, and Δ (V / r) / ΔT is a calculated value of the yaw rate V /
r is a time difference (time derivative).

When the lateral acceleration change rate ΔG / ΔT is used instead of the yaw rate change rate ΔY / ΔT, any of the following equations may be used. ΔG / ΔT = V2 · Δ (1 / r) / ΔT + (1 / r) · 2V · ΔV / ΔT (6) ΔG / ΔT = Δ (V2 / r) / ΔT (7) where Δ ( V2 / r) / ΔT is the lateral acceleration data Gs
(= V2 / r). Vehicle speed V
When the calculation formula taking into account the time difference term is adopted, a highly accurate yaw rate change rate ΔY / ΔT or lateral acceleration change rate ΔG / ΔT can be obtained even when the vehicle speed changes. At any time, the damper 44 can be locked at an appropriate time.

In each of the above embodiments, the steering angle sensor 52 and the vehicle speed sensor 54 are used to calculate the lateral acceleration, and the calculation is performed from the respective detected data. Alternatively, the lateral acceleration may be calculated.

For example, the lateral acceleration can be calculated using the yaw rate Y and the vehicle speed V. Use a vehicle speed sensor and a yaw rate sensor (such as a gyroscope). Also in this case, if a vehicle speed sensor originally provided in the vehicle is used, it is only necessary to add a yaw rate sensor. The lateral acceleration Gs is calculated by the following equation.

Gs = Y · V (8) The yaw rate change rate ΔY / ΔT can be obtained by using the detected value Y of the yaw rate sensor and performing a time difference (time differentiation). When adopting the lateral acceleration change rate ΔG / ΔT instead of the yaw rate change rate ΔY / ΔT, the following equation is used.

ΔG / ΔT = V · ΔY / ΔT (9) Further, considering the time difference term (time differentiation term) of the vehicle speed V, any of the following equations can be adopted.

ΔG / ΔT = V · ΔY / ΔT + Y · ΔV / ΔT (10) ΔG / ΔT = Δ (V · Y) / ΔT (11) Here, Δ (V · Y) / ΔT is Acceleration data Gs
(= V · Y). In any of the above formulas, the ΔY / ΔT value or ΔG using the detection data used to calculate the lateral acceleration is used.
/ ΔT value can be obtained. Also, when a calculation formula taking into account the time difference term of the vehicle speed V is adopted, a highly accurate yaw rate change rate ΔY / ΔT or lateral acceleration change rate ΔG / ΔT can be obtained even when the vehicle speed changes. Even when turning, the damper 44
Can be locked. Note that the CPU 63, the yaw rate sensor and the vehicle speed sensor 54 constitute a lateral acceleration measuring means and a turning change measuring means.

The lateral acceleration may be directly detected by an acceleration sensor. If the lateral acceleration is detected by the acceleration sensor, lateral acceleration other than when the vehicle is turning (for example, during straight running) can also be detected. Directional stability can be increased. Also, the lateral acceleration change rate ΔG /
ΔT can be obtained by time-differentiating (difference) the detected value of the lateral acceleration. The yaw rate change rate ΔY / ΔT is calculated by the following equation using the vehicle speed V detected by the vehicle speed sensor 54.

ΔY / ΔT = (ΔG / ΔT) · (1 / V) (12) Here, ΔG / ΔT is a time difference (time derivative) of the lateral acceleration data Gr. Considering the time difference (time derivative) term of the vehicle speed, any of the following equations may be adopted.

ΔY / ΔT = (ΔG / ΔT) · (1 / V) + G · {Δ (1 / V) / ΔT} (13) ΔY / ΔT = Δ (G / V) / ΔT (14) Here, Δ (1 / V) / ΔT is the time difference (time derivative) of the reciprocal value 1 / V of the vehicle speed, and Δ (G / V) / ΔT is the time difference (time difference) of the calculated yaw rate G / V. Differential). Further, when ΔG / ΔT is used instead of ΔY / ΔT,
What is necessary is just to obtain the lateral acceleration data Gr by performing a time difference (time differentiation). When a calculation formula considering the time difference term of the vehicle speed V is adopted, the yaw rate change rate ΔY with high accuracy even when the vehicle speed changes.
/ ΔT or the rate of change in lateral acceleration ΔG / ΔT, so that even when the vehicle turns while changing the vehicle speed,
The damper 44 can be locked at an appropriate time.
When the detection value of the acceleration sensor is subjected to difference processing (differential processing), it is desirable to filter the detection value in advance to remove noise. As the filtering process, for example, there is a method of averaging detection data for a plurality of past detections. It is more preferable to apply the same filter processing to the detection data other than the lateral acceleration, so that more accurate detection data can be obtained.

The set value of the yaw rate change rate ΔY / ΔT in addition to the set value of the lateral acceleration is determined by the load W that determines the height of the center of gravity.
It is also possible to adopt a configuration in which the set value yo is set in accordance with the height of the center of gravity using the lift height H as a parameter. That is, the set value yo is changed in advance continuously or discontinuously with respect to the height of the center of gravity so that the set value of the yaw rate change rate ΔY / ΔT, which is selected as the height of the center of gravity increases, tends to become substantially small. Set it. According to this configuration, it is not necessary to set the set value yo assuming that the center of gravity of the vehicle is high, so that the damper 44 is not required due to the yaw rate change rate ΔY / ΔT when the height of the center of gravity of the vehicle is relatively low. Lock can be reduced. Of course, the yaw rate change rate ΔY
/ ΔT instead of the lateral G change rate ΔG / ΔT (= V · ΔY / Δ
T), the same control may be performed on the lateral G change rate ΔG / ΔT.

The timing of delaying the lock of the damper 44 when the auxiliary wheel 4 is in the turning direction of the vehicle as the outer wheel is not limited to the time when the caster spring 30 has almost contracted to a predetermined length. It is preferable to lock the caster spring 30 after compressing the caster spring 30 as much as possible in order to minimize the decrease in the ground pressure of the drive wheel 3. However, if it can be increased, it contributes to the suppression of a decrease in the contact pressure of the drive wheels 3. For example, locking may be started at a timing when the length of the caster spring 30 is reduced by about half of the length until the caster spring 30 is fully contracted. Further, if the left and right stability of the vehicle body 1a allows, the lock may be started with a further timing delay from the time when the caster spring 30 is completely contracted.

○ The auxiliary wheel 4 is a link (caster link)
It may be fixed to. In other words, caster spring 3
The auxiliary wheel 4 is connected to the link mechanism 20 without an elastic member such as
It may be configured to be attached to the device. Also in this configuration, by setting a relatively large set value (including a case where the lock control is not performed) when the auxiliary wheel 4 is in the left turning direction in which the auxiliary wheel 4 is the outer wheel, the ground pressure of the drive wheel 3 during the left turning is reduced. The decrease can be suppressed as small as possible. In other words, it is possible to take measures to prevent the body 1a from leaning while minimizing a decrease in the contact pressure of the drive wheels 3, and it is possible to further ensure the running stability of the body 1a during turning.

In each of the above embodiments, the drive wheel 3 and the auxiliary wheel 4 are suspended by the common link mechanism 20, but the independent suspension in which the drive wheel 3 and the auxiliary wheel 4 are suspended by separate link mechanisms. It can also be implemented in a manner. In this case, the auxiliary wheel 4 may be attached to a dedicated link mechanism via an elastic member, or may be directly fixed to the link mechanism. In short, any configuration that can prevent a decrease in the contact pressure of the drive wheel 3 when the auxiliary wheel 4 turns as the outer wheel is sufficient.

It is not always necessary to use the yaw rate change rate ΔY / ΔT or the lateral acceleration change rate ΔG / ΔT as a parameter for determining swing control (lock control).
That is, a configuration may be used in which only the lateral acceleration is used as the parameter for the lock control determination. Even with this configuration, when the auxiliary wheel 4 is in the turning direction of the vehicle as the outer wheel, a decrease in the contact pressure of the drive wheel 3 can be suppressed as small as possible.

In each of the above embodiments, a sensor for detecting that the caster spring 30 has almost shrunk to a predetermined length is provided, and it is confirmed that the caster spring 30 has shrunk to the predetermined length according to the detection value of the sensor. Only when it is done, the damper 44 may be locked. According to this configuration, the damper 44 can always be locked when the caster spring 30 has almost contracted to a predetermined length, even if the lateral acceleration value detected at the time of turning varies.

The swing regulation mechanism includes a damper 44 interposed between the link mechanism 20 and the vehicle body frame 19, an electromagnetic switching valve 47 (or an electromagnetic proportional valve 75) for controlling lock of the damper 44, and the like. However, the present invention is not limited to this. For example, a rocking control mechanism is constituted by a stopper provided to be able to advance and retreat in a gap between the link mechanism and the body frame, and an actuator for moving the stopper forward and backward, and the link mechanism is locked by making the stopper enter the gap. A method can also be adopted. The stopper comes into contact with the link mechanism at two points so that the movement of the link mechanism in either direction can be restricted. Further, the stopper may be configured such that the contact surface that contacts the link mechanism is formed into a taper that is inclined in the direction of entry, and the lock of the link mechanism is gradually released by slowly retracting the stopper.

In the above embodiments, the link mechanism 20 is locked when the lateral acceleration becomes equal to or larger than the set value Gc larger than the set value G1 during the right turn during the left turn when the auxiliary wheel 4 becomes the outer wheel. Alternatively, the link mechanism 20 may not be locked when the auxiliary wheel 4 turns to the left as the outer wheel.

The driven wheel paired with the driving wheel 3 in the vehicle width (left / right) direction is not limited to the auxiliary wheel 4. For example, the steering wheel may be a steering wheel that is paired with the driving wheel and steered together.
Even when the driven wheel is a steered wheel, by setting the set value in the turning direction in which the driven wheel becomes the outer wheel to be larger than the set value in the opposite turning direction, the steered wheel becomes A decrease in the ground pressure of the drive wheels can be suppressed as small as possible.

The method of measuring the lateral acceleration, the rate of change of the yaw rate and the rate of change of the lateral acceleration is not limited to the method of each of the above-described embodiments, and an appropriate method can be adopted.
For example, a method of indirectly deriving the lateral acceleration from the lateral inclination angle of the vehicle body detected by the inclination angle sensor may be adopted. In addition, a steering wheel angle sensor that detects the rotation angle of the steering wheel 14 can be used as a steering angle detector.

The locking of the link mechanism is not limited to completely fixing the link mechanism to the vehicle body frame, but may be a regulation for restricting the range of movement of the link mechanism with respect to the vehicle body to be narrow. A uniform effect can be obtained if the swing range between the driving wheel and the driven wheel is kept small.

A forklift other than a reach-type forklift may be used as long as a pair of drive wheels and driven wheels is suspended from the vehicle body via a link mechanism so as to allow the vehicle body to swing in the roll direction. May be applied. Furthermore, it can be widely applied to industrial vehicles other than forklifts. In addition, the drive wheel does not have to serve as the steering wheel.

Next, regarding technical ideas other than the inventions described in the claims that can be understood from the above embodiments and other examples,
These effects are described below. (1) In any one of claims 1 to 10, the control means may determine a lock timing of the link mechanism by setting a lateral acceleration set value in a turning direction of a vehicle in which the driven wheel is an outer wheel. The lateral acceleration is set to be larger than the set value of the lateral acceleration when the driving wheel is in the turning direction of the vehicle as the outer wheel. According to this configuration, the same effect as any of the first to tenth aspects can be obtained.

(2) In any one of claims 1 to 10, the link mechanism moves at least when the drive wheel is displaced. According to this configuration, the same effect as any of the first to tenth aspects can be obtained.

(3) In any one of the first to tenth aspects, the control means performs at least the lock control when the driving wheel is in a turning direction of a vehicle in which the driven wheel is an outer wheel, and the driven wheel is an outer wheel. In the turning direction of the vehicle, the link mechanism is not locked, or the set value is set to be larger than the setting value in the turning direction in which the driving wheels are the outer wheels, so that the link mechanism is changed depending on the turning direction of the vehicle. There is a difference in the lock condition for locking the lock. According to this configuration, the same effect as any of the first to tenth aspects can be obtained.

(4) In any one of the first to tenth aspects, the driving wheel and the driven wheel are suspended so as to swing together with a vehicle body via a link mechanism, and at least the driving wheel is It is designed to move integrally with the link mechanism. According to this configuration, the same effect as any of the first to tenth aspects can be obtained.

(5) In any one of the first to tenth aspects, the driving wheels are steering wheels. According to this configuration, in addition to the effects of any one of the first to tenth aspects, the steering stability in the turning direction in which the driven wheel becomes the outer wheel can be secured.

(6) According to any one of claims 2 to 10, when the auxiliary wheel is in the turning direction of the vehicle in which the auxiliary wheel is an outer wheel, the set value is such that the link mechanism is locked at a timing when the elastic member is almost fully contracted. It is set to be. According to this configuration, it is possible to more effectively reduce the decrease in the ground pressure of the drive wheels.

(7) In claim 3, the height-of-gravity measuring means includes a height detector for detecting, as the parameter, the height of a loading device provided for loading a load on the vehicle;
At least one of a load detector that detects a load of the load on the loading device as the parameter.
According to this configuration, since at least one of the lift and the load, which are major factors for changing the height of the center of gravity of the industrial vehicle, is used as a parameter, an appropriate locking of the link mechanism according to the height of the center of gravity is realized.

(8) In claim 4 or claim 5, the plurality of detectors provided in the center-of-gravity height measuring means continuously detect a plurality of parameters for determining the height of the center of gravity of the vehicle. The control means is set such that the set value of the lateral acceleration changes continuously for each of the plurality of parameters. According to this configuration, since the set value of the lateral acceleration that is almost optimal for the height of the center of gravity of the vehicle is selected, substantially optimal lock control according to the height of the center of gravity of the vehicle is realized.

(9) In claim 7, the physical quantity detector is a steering angle detector for detecting a steering angle of a steered wheel.
According to this configuration, since the vehicle speed detector is originally provided in the vehicle, the lateral acceleration can be measured only by adding the steering angle detector for detecting the steering angle of the steered wheels.

(10) In claim 7, the physical quantity detector is a yaw rate detector for detecting a yaw rate when the vehicle turns. According to this configuration, since the vehicle speed detector is originally provided in the vehicle, the lateral acceleration can be measured only by adding the yaw rate detector for detecting the yaw rate.

(11) In any one of claims 1 to 6, the lateral acceleration measuring means is an acceleration sensor. According to this configuration, the lateral acceleration other than when the vehicle is turning can also be detected, and the link mechanism can be locked when the lateral acceleration is applied other than during the turning to improve the left and right stability of the vehicle.

(12) Claim 7 and (9), (1)
0), the turning change measuring means calculates the yaw rate change rate or the lateral acceleration change rate using at least one of respective detection data of the vehicle speed detector and the physical quantity detector. It has a rate estimating means. According to this configuration, the yaw rate change rate or the lateral acceleration change rate can be calculated using the detection data of each detector used for calculating the lateral acceleration.

(13) In the above (12), the equation used by the turning change rate estimating means to calculate the yaw rate change rate or the lateral acceleration change rate includes a time differential term of the vehicle speed. I have. According to this configuration, a high-accuracy yaw rate change rate or a lateral acceleration change rate can be obtained even when the vehicle turns with a change in vehicle speed.

(14) In the tenth aspect, the regulating force adjusting means includes an electromagnetic force for opening and closing a flow path of a working fluid for a cylinder device interposed between the vehicle body and the link mechanism to expand and contract. The control means gradually releases the lock of the link mechanism by controlling the current value of the electromagnetic proportional valve. According to this configuration, Claim 10
The same effect as that of the invention is obtained.

(15) Claims 1-10 and (1)-
(14) In any one of the above (1) and (2), the swing restriction mechanism may be configured to open and close a cylinder device interposed between the vehicle body and the link mechanism and a flow path of a working fluid for the cylinder device to expand and contract. The lock control is performed by controlling the opening and closing of the on / off valve by the control unit. According to this configuration, the same effect as any one of claims 1 to 10 and the above (1) to (14) can be obtained.

[0159]

As described in detail above, according to the first aspect of the present invention, the lock timing is delayed when the driven wheel is in the turning direction in which the driven wheel becomes the outer wheel, and the height of the center of gravity or a parameter for determining the same is measured. Since the set value of lateral acceleration is selected in consideration of the height of the center of gravity of the vehicle according to the measured value, fine lock control according to the height of the center of gravity of the vehicle is realized while maintaining running stability when turning the vehicle it can.

According to the second aspect of the present invention, when the auxiliary wheel is in the turning direction of the vehicle in which the auxiliary wheel is the outer wheel, the link mechanism is set to be locked after the elastic member is contracted by a predetermined amount, and the elastic mechanism is locked after locking. Since the amount of shrinkage of the member is relatively reduced, it is possible to minimize the decrease in the contact pressure of the drive wheel when the auxiliary wheel is in the turning direction in which the auxiliary wheel is the outer wheel.

According to the third aspect of the present invention, since the set value of the lateral acceleration is directly selected from the parameters for determining the height of the center of gravity of the vehicle detected by at least one detector, the calculation for actually obtaining the height of the center of gravity is performed. You don't have to. In addition, even without detecting all parameters that determine the height of the center of gravity, it is possible to realize lock control that considers the height of the center of gravity with a small number of detectors by selecting one that seems to have a high contribution rate. Can be.

According to the present invention, the set value of the lateral acceleration is selected so as to continuously change in accordance with the continuous change of the parameter detected by the detector. More precise lock control can be realized.

According to the fifth aspect of the present invention, in determining the height of the center of gravity of the vehicle, the lift and load of the load having the highest contribution rate are two parameters for selecting the set value of the lateral acceleration. Therefore, it is possible to realize more detailed lock control in consideration of the height of the center of gravity of the vehicle.

According to the sixth aspect of the present invention, since the yaw rate change rate or the lateral acceleration change rate of the vehicle is adopted as one of the lock control parameters when the drive wheel is in the turning direction in which the driving wheel is the outer wheel, the turning is performed. At the start, the link mechanism can be locked quickly without delay.

According to the invention described in claim 7, the vehicle speed,
Since the method of estimating the lateral acceleration by calculation using the physical quantity necessary to calculate the lateral acceleration using the vehicle speed is adopted, in addition to the vehicle speed detector originally provided in the vehicle, it is only necessary to add one detector I'm done.

According to the eighth aspect of the present invention, the operation of the swing regulating mechanism is stopped after a lapse of a predetermined time from the time when the lock condition is not satisfied, so that the control is frequently switched. Can be avoided.

According to the ninth aspect of the present invention, the set value when the operation of the swing restriction mechanism is stopped is set to be smaller than the set value when the operation of the swing restriction mechanism is operated. Is frequently switched.

According to the tenth aspect, when the operation of the swing regulation mechanism is stopped, the regulation force adjusting means is configured to gradually reduce the regulation force applied to the link mechanism for locking. As a result, the shock of the vehicle body when the link mechanism is unlocked can be reduced.

[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 side view of the reach type forklift.

FIG. 3 is a plan view of the reach type forklift.

FIG. 4 is a schematic rear view showing the vehicle body swing control device.

FIG. 5 is a plan view showing a rear suspension structure.

FIG. 6 is a rear view showing a part of the rear suspension structure.

FIG. 7 is a block diagram showing an electrical configuration of the vehicle body swing control device.

FIG. 8 is a map diagram showing a relationship between a steering angle and a turning radius.

FIGS. 9A and 9B are graphs showing lock conditions of a lateral acceleration and a yaw rate change rate, respectively.

FIG. 10 is a map diagram for obtaining a set value of a lateral acceleration.

FIG. 11 is a timing chart when a lock signal command is stopped.

FIG. 12 is a flowchart of a swing control process.

FIG. 13 is also a flowchart.

FIG. 14 is a graph illustrating swing control when the vehicle is turning.

FIGS. 15A and 15B are schematic rear views of the link mechanism, wherein FIG. 15A shows a state locked when turning right, and FIG. 15B shows a state locked when turning left.

FIG. 16 is a schematic diagram of a vehicle body swing control device according to a second embodiment.

FIG. 17 is a block diagram showing an electrical configuration of the vehicle body swing control device.

FIG. 18 is a map diagram for obtaining a set value of a lateral acceleration.

FIG. 19 is a map diagram for obtaining a set value of a lateral acceleration in the third embodiment.

FIG. 20 is a map diagram for obtaining a set value of a lateral acceleration in the fourth embodiment.

FIG. 21 is a partial schematic diagram of a vehicle body swing control device according to a fifth embodiment.

FIG. 22 is a timing chart when a lock signal command is stopped.

FIG. 23 is a graph showing conditions for locking / unlocking the rate of change of the yaw rate in the sixth embodiment.

FIG. 24 is a graph showing conditions for locking / unlocking lateral acceleration.

[Explanation of symbols]

1. Reach forklift as an industrial vehicle, 1a ...
Vehicle body, 3 ... drive wheels, 4 ... auxiliary wheels as driven wheels, 11 ...
Fork as loading equipment, 19 ... body frame, 20
... Link mechanism, 30 ... Caster spring as an elastic member, 44 ... Damper which constitutes a swing regulation mechanism, 47 ... Electromagnetic switching valve which constitutes a swing regulation mechanism, 52 ... Constitutes lateral acceleration measuring means and turning change measuring means And a steering angle sensor as a physical quantity detector, 54... Constitute a lateral acceleration measuring means and a turning change measuring means, and a vehicle speed sensor as a vehicle speed detector, 55, 70. Height sensor as high detector,
56: a center of gravity height measuring means and a load sensor as a detector and a load detector; 57: a controller as control means; 63: a lateral acceleration measuring means and a turning change measuring means; and a lateral acceleration estimating means C
PU, 75... Constitute a swing regulation mechanism and an electromagnetic proportional valve as regulating force adjusting means, H... Lift as a parameter, W... Load as a parameter, Gs.
Y / ΔT: rate of change in yaw rate, G1, G2, Gc: set value, yo: set value.

Claims (10)

[Claims] 1. An industrial vehicle in which a pair of right and left driving wheels and driven wheels are suspended via a link mechanism with respect to a vehicle body so as to allow swinging of the vehicle body in a roll direction. Rocking mechanism for locking the vehicle, lateral acceleration measuring means for measuring the lateral acceleration of the vehicle, and the height of the center of gravity of the vehicle or at least one parameter for determining the height of the center of gravity continuously or intermittently. Measuring means, from the set values of the lateral acceleration previously set discontinuously or continuously with respect to the height of the center of gravity or the parameter, according to the measurement value measured by the center of gravity measuring means A set value is selected, and when the lateral acceleration measured by the lateral acceleration measuring means is equal to or more than the set value, the rocking control mechanism is operated to perform lock control for locking the link mechanism. In both cases, the lock is not performed when the driven wheel is in the turning direction of the vehicle that is the outer wheel, or the lock timing is relatively delayed from the lock timing when the driven wheel is in the turning direction of the vehicle that is the outer wheel. A vehicle body swing control device for an industrial vehicle, comprising: a control unit set to: 2. The driven wheel is an auxiliary wheel attached to the link mechanism via an elastic member. When the auxiliary wheel is in a turning direction of a vehicle in which the auxiliary wheel is an outer wheel, until the elastic member contracts by a predetermined amount. The vehicle body swing control device for an industrial vehicle according to claim 1, wherein the link mechanism is set to be locked at a timing of waiting. 3. The center-of-gravity height measuring means includes at least one detector for continuously or intermittently detecting a parameter for determining the height of the center of gravity of the vehicle. The vehicle body swing of an industrial vehicle according to claim 1 or 2, wherein the parameter is set in advance in a discontinuous or continuous manner so that the parameter has a smaller value as the height of the center of gravity of the vehicle is higher. Motion control device. 4. The center-of-gravity height measuring means includes a plurality of detectors for detecting a plurality of parameters for determining the height of the center of gravity of a vehicle, wherein at least one of the detectors continuously detects the parameter. The industrial vehicle according to any one of claims 1 to 3, wherein the control unit is set so that a set value of the lateral acceleration changes continuously with respect to at least one parameter. Body swing control device. 5. The height-of-gravity measuring means detects a lift of a loading device provided in the vehicle so as to be able to move up and down as the parameter, and detects a load of the load on the loading device as the parameter. The vehicle body swing control device for an industrial vehicle according to claim 3, further comprising: a load detector that performs the load detection. 6. A turning change measuring means for measuring a yaw rate change rate or a lateral acceleration change rate of the vehicle, wherein the control means controls the yaw rate change rate or the lateral acceleration when the driving wheel is in a turning direction in which the driving wheel is an outer wheel. The vehicle body swing control device for an industrial vehicle according to any one of claims 1 to 5, wherein when the rate of change is equal to or greater than the set value, the swing regulation mechanism is activated. 7. The lateral acceleration measuring means includes: a vehicle speed detector for detecting a vehicle speed of the vehicle; a physical quantity detector for detecting a physical quantity required to calculate a lateral acceleration using the vehicle speed; The vehicle body swing control device for an industrial vehicle according to any one of claims 1 to 6, further comprising: a lateral acceleration estimating unit configured to estimate the lateral acceleration by a calculation using the detected data. 8. The system according to claim 1, wherein the control means is configured to stop the operation of the rocking regulation mechanism after a lapse of a predetermined time from a time point at which a lock condition for operating the rocking restriction mechanism is not satisfied. The vehicle body swing control device for an industrial vehicle according to any one of claims 1 to 7. 9. The set value when stopping the operation of the swing regulating mechanism is set smaller than the set value when the control means operates the swing regulating mechanism. A vehicle body swing control device for an industrial vehicle according to any one of the preceding claims. 10. The swing regulating mechanism includes regulating force adjusting means capable of adjusting a regulating force applied to the link mechanism for locking, and the control means controls the regulating force adjusting means by controlling the regulating force adjusting means. 10. The control device according to claim 1, wherein when the lock control is performed and the operation of the swing restriction mechanism is stopped, the restriction force adjusting unit is controlled so that the lock of the link mechanism is gradually released. The vehicle body swing control device for an industrial vehicle according to any one of the preceding claims.