JP2009274617A - Oscillation controller for industrial vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oscillation controller for an industrial vehicle capable of improving running stability of a vehicle when the vehicle travels out of an irregular road surface. <P>SOLUTION: In a forklift, a vehicle body 11a and a rear axle 20 are connected to each other via a dumper 22. The damper 22 is connected to a control valve 23 via a first pipe conduit P1 and a second pipe conduit P2. The vehicle body 11a includes a swing angle detection sensor 30 that detects a swing angle of the rear axle 20. When it is detected that the swing angle has reached a second reference swing angle after reaching a first reference angle, a CPU outputs a lock signal to the control valve 23 to lock the rear axle 20. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a swing control device for an industrial vehicle in which an axle is swingably provided.

  In an industrial vehicle such as a forklift, in consideration of the running stability and riding comfort of the vehicle, the axle is mounted so as to be able to swing up and down with respect to the vehicle body, and a swing control device that controls the swing control of the axle As an example, an axle swinging device that restricts swinging of the rear wheel shaft in either the clockwise direction or the counterclockwise direction or both has been proposed (see, for example, Patent Document 1).

The axle swing device described in Patent Document 1 is configured to estimate a rolling angle that is a rotation angle of the center of gravity of the vehicle around the roll shaft when the vehicle is turning, and to control the swing control of the axle with the rolling angle. Has been. Specifically, by estimating the rolling angle from the traveling speed, turning direction, total weight, center of gravity position and turning radius, and comparing the rolling angle with the operation reference value and the stop reference value calculated from the center of gravity position, Based on the comparison result, swing control is performed by controlling supply / discharge of the hydraulic cylinder disposed between the vehicle body frame and the axle.
JP 11-129722 A

  By the way, the industrial vehicle which performs rocking | fluctuation regulation can improve the earthing | grounding property of a wheel because an axle shaft rocks | fluctuates, when a wheel approaches an uneven road surface. However, when the wheels are removed from the uneven road surface to the horizontal road surface, the axle is also returned to the horizontal state together with the vehicle main body, but the vehicle swings in the opposite direction due to inertia acting on the vehicle main body or deflection of the tire. . For this reason, from the viewpoint of running stability and riding comfort of the vehicle, it is necessary to consider swing regulation when the vehicle is removed from the uneven road surface. However, the axle swing device disclosed in Patent Document 1 Only swing regulation is considered.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide an industrial vehicle swing control device capable of improving the running stability of a vehicle when it is removed from an uneven road surface. is there.

  In order to achieve the above object, an invention according to claim 1 is provided in an industrial vehicle that supports an axle that is swingable in a vertical direction with respect to the vehicle body, and is disposed between the vehicle body and the axle. In a swing control device for an industrial vehicle that controls the locking and unlocking of the axle by controlling the supply and discharge of hydraulic oil to and from the installed damper, the swing angle that detects the swing angle that indicates the inclination of the axle with respect to the vehicle body Detection means; first determination means for determining whether the swing angle has reached a first reference swing angle for determining that the axle is tilted; and the swing angle is a direction in which the axle is horizontal. A second determination means for determining whether or not a second reference swing angle at which it has been swung is reached, and after the first determination means makes an affirmative determination, the second determination means makes an affirmative determination Triggered by And summarized in that and a control means for executing the swing restriction control to lock the axle.

  In this invention, when the wheel approaches the uneven road surface and the first determination means determines that the swing angle has reached the first reference swing angle, the wheel rolls on the uneven road surface and the axle tilts. Judge that Then, when the second determination means affirmatively determines that the swing angle has reached the second reference swing angle in an attempt to remove the wheel from the uneven road surface, the axle swings in a horizontal direction from the tilted state. Judge. Then, a control means performs rocking | fluctuation control control triggered by the affirmation determination of a 2nd determination means, and locks an axle. Therefore, the vehicle body is prevented from swinging in the roll direction when the wheel is removed from the uneven road surface, and the running stability of the vehicle when the wheel is removed from the uneven road surface can be improved.

  According to a second aspect of the present invention, in the first aspect of the invention, when the control means satisfies a predetermined unlock condition after the start of the swing restriction control, the swing restriction control is terminated. The gist of the invention is to perform unlock control for unlocking the axle and unlocking the axle.

  In this invention, after the wheels of the industrial vehicle have taken off the uneven road surface, the axle can be returned to the unlocked state. Therefore, when the industrial vehicle reaches the uneven road surface again, the axle is in a swingable state. Therefore, the function of ensuring the wheel contact area when traveling on an uneven road surface is not impaired.

  According to a third aspect of the present invention, there is provided an inclination detection means for detecting an inclination of the vehicle main body with respect to a vehicle width direction, and the control means is determined from the detection result of the inclination detection means that the vehicle main body is not horizontal. In this case, unlock control for unlocking the axle is executed, and when it is determined that the vehicle main body is horizontal, the first determination unit and the second determination unit are used to determine whether the vehicle body is horizontal. The gist is to execute the swing restriction control.

  In the present invention, when the control unit determines that the vehicle body is horizontal based on the detection result of the inclination detection unit, the control unit performs the swing restriction control when the wheel is removed from the uneven road surface, and the vehicle body swings in the roll direction. Suppress. Also, when the industrial vehicle is running with the vehicle body tilted with respect to the vehicle width direction, the control means determines that the vehicle body is not horizontal and locks the axle even when the wheels are removed from the uneven road surface. Absent. Therefore, it is possible to prevent a situation in which one wheel floats off the road surface.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the first reference swing angle is larger than the second reference swing angle, A predetermined angle difference is set between the reference swing angle and the second reference swing angle, and the control means has the swing angle smaller than the first reference swing angle, The gist is to execute the unlock control for unlocking the axle in the range of the angle difference larger than the second reference swing angle.

  In the present invention, the first reference swing angle is set to an angle at which the axle can be determined to be inclined, the second reference swing angle is different from the first reference swing angle, and the axle is horizontal. It can be set to an angle at which it can be determined that it has swung in the direction. When the industrial vehicle travels on an uneven road surface with small undulations, the first reference swing angle is set to be larger than the second reference swing angle so that the swing angle does not reach the first reference swing angle. Is set. Therefore, the first reference swing angle is set to the second reference swing angle after the second reference swing angle is set so that the timing for performing the swing restriction control can be as short as possible immediately before the uneven road surface is removed. By setting the angle larger than that, frequent switching control of axle locking and unlocking can be prevented.

  ADVANTAGE OF THE INVENTION According to this invention, the driving | running | working stability of a vehicle when it remove | deviates from an uneven road surface can be improved.

  Hereinafter, an embodiment in which the present invention is embodied in a swing control device for a forklift will be described with reference to FIGS. In the following description, “front”, “rear”, “left”, “right”, “upper”, and “lower” refer to “front” when the forklift driver is facing forward (forward direction) of the forklift. ”,“ Back ”,“ left ”,“ right ”,“ upper ”, and“ lower ”. The “left-right direction” corresponds to the vehicle width direction of the forklift.

  As shown in FIG. 1, an inner mast 13 is disposed between a pair of left and right outer masts 12 erected on the front of the machine base of the forklift 11, and a fork 14 as a cargo handling attachment is attached to the inner mast 13. Is suspended through a lift bracket and a chain (both not shown) so as to be lifted and lowered.

  The outer mast 12 is supported so as to be tiltable with respect to the vehicle main body 11a, and is tilted when the piston rod 15a of the tilt cylinder 15 connected between the outer mast 12 and the vehicle main body 11a is expanded and contracted. A piston rod 16a of a lift cylinder 16 disposed on the back surface of the outer mast 12 is connected to an upper end portion of the inner mast 13, and the piston rod 16a of the lift cylinder 16 is driven to expand and contract so that the fork 14 moves up and down. It has become. The left and right front wheels 17 are operatively connected to the engine 18 via a differential ring gear and a transmission (not shown) and are driven by the engine 18.

  As shown in FIG. 2, the rear axle 20 as an axle extends in the vehicle width direction between the left and right rear wheels 19 and swings in the vertical direction around the center pin 20a. (Rotation) is supported. The left and right rear wheels 19 are connected to the front ends of a pair of left and right piston rods of a steering cylinder (not shown) disposed on the rear axle 20 via a link mechanism (not shown). The rear axle 20 is supported so as to be able to swing together. The left and right rear wheels 19 are steered by driving the steering cylinder based on the operation of the handle 21 (see FIG. 1).

  One hydraulic damper (hereinafter simply referred to as “damper”) 22 is disposed between the vehicle body 11 a and the rear axle 20 in a state of connecting the two. The damper 22 is a double-acting hydraulic cylinder. The cylinder 22a of the damper 22 is connected to the vehicle body 11a side, and the tip of the piston rod 22c extending from the piston 22b accommodated in the cylinder 22a is on the rear axle 20 side. It is connected to.

  The damper 22 is connected to the control valve 23 via a first pipe line P1 and a second pipe line P2 that are connected to each of the first chamber R1 and the second chamber R2 defined by the piston 22b. ing. As the control valve 23, a normally closed type 2-port 2-position switching valve that is closed by the biasing force of the spring 23b when the solenoid 23a is demagnetized is used. A stop valve portion 24 and a flow valve portion 25 are formed on the spool. ing. The solenoid 23a of the control valve 23 is electrically connected to a controller 26 mounted on the vehicle body. An accumulator (reservoir) 27 for storing hydraulic oil is connected to the second pipeline P2 via the third pipeline P3. The third pipe P3 is provided with a check valve 28 that prevents hydraulic oil from flowing back from the second pipe P2 to the accumulator 27.

  By arranging the spool of the control valve 23 in the closed position shown in FIG. 2 with respect to the body, the damper 22 is locked so that the hydraulic oil cannot flow out / inflow in the two chambers R1, R2, and the rear axle 20 Oscillation is restricted and locked (fixed).

  On the other hand, the damper 22 is disposed between the chambers R1 and R2 by arranging the spool of the control valve 23 in the open position with respect to the body (the state where the spool position is switched from the state of FIG. 2 to the opposite side). Thus, the rear axle 20 is allowed to swing. Further, a throttle valve 29 is provided on the route of the second pipeline P2. An axle restricting mechanism for restricting the swinging of the axle is configured by the damper 22 and the control valve 23 and the like.

  A swing angle sensor 30 as a swing angle detecting means for detecting the swing angle θ of the rear axle 20 is disposed in the vehicle main body 11a. Note that in the forklift 11 of the present embodiment, the swing angle θ indicates the inclination of the rear axle 20 with respect to the vehicle body 11a, that is, the angle formed with respect to the horizontal direction when the rear axle 20 swings in the vertical direction. The rear axle 20 is set so that the swing angle θ when horizontal is 0 degrees. When the right rear wheel 19 rolls on the concave road surface and the rear axle 20 tilts from the horizontal to the vertical direction, the swing angle θ changes to a positive value, and the right rear wheel 19 moves on the convex road surface. The swing angle θ is set to change to a negative value when the rear axle 20 is tilted from the horizontal to the vertical direction after rolling. A rotary potentiometer is used as the swing angle sensor 30, and the swing of the rear axle 20 is transmitted to the swing angle sensor 30 via the link 31. The swing angle sensor 30 is electrically connected to the controller 26 and is configured to input a detection signal indicating the swing angle θ of the rear axle 20 to the controller 26.

Next, the electrical configuration of the swing control system of the forklift 11 will be described with reference to FIG.
The controller 26 that controls the swing control of the forklift 11 incorporates a microcomputer 32, an AD conversion circuit 33, an excitation / demagnetization drive circuit 34, and the like. The microcomputer 32 includes a CPU (Central Processing Unit) 35, a ROM (Read Only Memory) 36, a RAM (Read / Write Memory) 37, a timer 38, an input interface 39 and an output interface 40.

  A swing angle sensor 30 is connected to the CPU 35 constituting the first determination unit, the second determination unit, and the control unit via an AD conversion circuit 33 and an input interface 39. In addition, a solenoid 23 a is connected to the CPU 35 via an excitation / demagnetization drive circuit 34 and an output interface 40. The control valve 23 is switched to the closed position when the solenoid 23a is demagnetized based on the output of the lock signal from the CPU 35, and is moved to the open position when the solenoid 23a is excited based on the output of the unlock signal. Can be switched. In this embodiment, the unlock signal is an excitation command, and the lock signal is a demagnetization command to the solenoid 23a.

  The ROM 36 stores various program data including program data in the swing suppression mode. The ROM 36 also stores a first reference swing angle α (hereinafter referred to as “swing angle α”) and a second reference swing angle β (hereinafter referred to as “swing angle β”). The swing angle α is set to an angle at which the rear axle 20 can be regarded as inclined, and is set to ± 5 degrees or more, for example. The swing angle β is smaller than the swing angle α, and is set to an angle at which the rear axle 20 may be regarded as returning to the horizontal, and is a value close to 0 degrees (for example, ± 2 to 3). Degree). Further, the ROM 36 stores a specified lock time T1 (for example, 0.5 s to 1 s) as a time required until the rear axle 20 stops swinging after the rear wheel 19 is removed from the uneven road surface. The specified lock time is obtained in advance by experiment or calculation.

  The timer 38 is activated when an activation signal is input from the CPU 35, starts counting a lock timer T indicating the time since the rear axle 20 was started to be locked, and receives a stop signal from the CPU 35. The count of the lock timer T is stopped, and the lock timer T counted so far is reset. The timer 38 is configured to output the count result to the CPU 35 while the lock timer T is counting.

  The CPU 35 performs the swing suppression mode according to the flowchart shown in FIG. In the swing suppression mode, the CPU 35 compares the value of the swing angle θ detected by the swing angle sensor 30 with the swing angle α stored in advance in the ROM 36, and when the swing angle θ is equal to or greater than the swing angle α. It is determined that the rear axle 20 is tilted. Further, the CPU 35 determines that the rear axle 20 swings in the horizontal direction when the swing angle θ once becomes equal to or greater than the swing angle α and then becomes equal to or less than the swing angle β. The CPU 35 outputs a lock signal to the control valve 23 when the swing angle θ is changed from the swing angle α to the swing angle β.

Next, the operation of the swing control device configured as described above will be described.
In order to prevent the rear axle 20 from swinging and the vehicle body 11a from swinging in the roll direction when the forklift 11 is removed from the uneven road surface, the CPU 35 sets the swing suppression mode in a predetermined cycle according to the flowchart of FIG. Do it every time. In step S1, the CPU 35 detects whether or not the swing angle θ is greater than or equal to the swing angle α, that is, whether or not the rear axle 20 is tilted. At this time, if the CPU 35 detects that the swing angle θ is equal to or greater than the swing angle α, the CPU 35 makes an affirmative determination that the rear axle 20 is tilted, and the CPU 35 proceeds to step S2 to turn on the tilt flag and save it in the RAM 37. To do. Next, the process proceeds to step S3, an unlock signal is output, the damper 22 is unlocked, the rear axle 20 is unlocked, the process proceeds to step S4, and a stop signal is output. The count of T is stopped and the lock timer T is reset, and the swing suppression mode is terminated.

  If the swing angle θ is less than the swing angle α in step S1, the CPU 35 proceeds to step S5 and determines whether the swing angle θ is equal to or less than the swing angle β. If the CPU 35 detects that the swing angle θ is equal to or smaller than the swing angle β, the CPU 35 proceeds to step S6 and detects whether or not the timer 38 is being activated. If the timer 38 is not activated in step S6, the CPU 35 proceeds to step S7 and determines whether or not the tilt flag is ON. In step S7, if the inclination flag is not ON, the process proceeds to step S3. If the inclination flag is ON, an affirmative determination is made that the swing angle .theta. Has reached the swing angle .beta. move on. In step S8, the inclination flag stored in the RAM 37 is rewritten to OFF. Thereafter, the CPU 35 proceeds to step S9 in order to execute the swing restriction control for locking the rear axle 20, and in step S9, outputs a lock signal, locks the damper 22 and locks the rear axle 20, In step S10, an activation signal is output to the timer 38, the timer 38 starts counting the lock timer T, and the swing suppression mode is terminated.

  If the CPU 35 determines in step S5 that the swing angle θ is larger than the swing angle β, the swing angle θ is in the range of the angle difference between the swing angle β and the swing angle α, and the process proceeds to step S11. Unlock control for unlocking the rear axle 20 is executed. Then, the CPU 35 outputs an unlock signal, changes the damper 22 from the locked state to the unlocked state, and unlocks the rear axle 20. Then, it progresses to step S12, a stop signal is output to the timer 38, and rocking | fluctuation suppression mode is complete | finished.

  In step S6, if the lock timer T is activated, the CPU 35 proceeds to step S13 and determines whether or not the unlock condition that the lock timer T is equal to the specified lock time T1 is satisfied. If the lock timer T is not equal to the specified lock time T1, the CPU 35 proceeds to step S14 to execute the swing restriction control, outputs a lock signal to lock the damper 22, and then proceeds to step S15. 38 counts up the lock timer T and ends the swing suppression mode. In step S13, when the unlock condition that the lock timer T is equal to the specified lock time T1 is satisfied, the unlock control is executed in step S11 to place the damper 22 in the unlock state, and then step S12. In this order, the swing suppression mode is terminated. In step S3 and step S11, when the damper 22 is already in the unlocked state, in step S3 and step S11, control for holding the damper 22 in the unlocked state is performed. In step S9 and step S14, when the damper 22 is already in the locked state, in step S9 and step S14, control is performed to hold the damper 22 in the locked state.

Next, the control content of the swing control device will be described.
As shown in FIG. 5, when the forklift 11 travels on a horizontal road surface at time t0 to t1, the rear axle 20 is horizontal, so the swing angle θ is 0 degree, and no lock signal is output from the CPU 35. The axle 20 is swingable in the vertical direction. Thereafter, during the time t1 to t2, the forklift 11 reaches the concave road surface, and when the right rear wheel 19 rolls on the concave road surface, the rear axle 20 swings and the swing angle θ is a positive value. It increases to become. When the swing angle θ reaches the swing angle α, the tilt flag is turned on, and the CPU 35 determines that the rear axle 20 is tilted. At this time, since the CPU 35 holds the state of outputting the unlock signal, either the right rear wheel 19 that rolls on the concave road surface or the left rear wheel 19 that does not roll on the concave road surface. Is also in contact with the road surface. Thereafter, when the forklift 11 is about to take off from the concave road surface, the rear axle 20 gradually returns to a horizontal state, so that the swing angle θ decreases. At time t3, the swing angle θ reaches the swing angle β from the swing angle α, and the CPU 35 turns off the tilt flag and outputs a lock signal to fix the vehicle main body 11a and the rear axle 20. Therefore, when the forklift 11 is removed from the concave road surface, the forklift 11 is caused to swing to the opposite side to the inclined side due to inertia and tire deflection caused by returning from the inclined state to the original state. Even if the force to act on the vehicle main body 11a, the vehicle main body 11a and the rear axle 20 are fixed, so that the swinging of the vehicle main body 11a is suppressed. After that, when the lock timer T has passed the specified lock time T1 from the time t3, the CPU 35 determines that the vehicle body 11a does not swing due to the forklift 11 taking off the concave road surface, and outputs an unlock signal. Is output (the lock signal is turned OFF), and the damper 22 is returned to the unlocked state.

  Further, when the forklift 11 continuously travels on a plurality of uneven road surfaces with small undulations, the swing angle θ does not reach the swing angle α, so the CPU 35 does not output a lock signal. Therefore, in the state where the CPU 35 is in the swing suppression mode, the swing restriction control is not executed unless the forklift 11 is traveling on an uneven road surface having a predetermined undulation, and the rear axle 20 is locked. Never happen. Therefore, it is possible to prevent the CPU 35 from performing frequent switching control of locking and unlocking the rear axle 20.

In this embodiment, the following effects can be obtained.
(1) The forklift 11 includes a damper 22 disposed between the vehicle body 11 a and the rear axle 20, and a control valve 23 that controls the supply and discharge of hydraulic oil to and from the damper 22. When detecting that the swing angle θ has reached the swing angle β from the swing angle α, the CPU 35 outputs a lock signal to the control valve 23 in order to lock the rear axle 20. Therefore, when the rear wheel 19 is removed from the uneven road surface, the control valve 23 is controlled so as to lock the vehicle body 11a and the rear axle 20, so that the forklift 11 swings in the roll direction when the rear wheel 19 is removed from the uneven road surface. Can be suppressed.

  (2) When the lock timer T becomes equal to the specified lock time T1, the CPU 35 switches the signal output to the control valve 23 from the lock signal to the unlock signal, and switches the rear axle 20 from the locked state to the unlocked state. . Therefore, when the rear wheel 19 of the forklift 11 again comes to the uneven road surface, the rear axle 20 is in a swingable state, so that the ground contact area of the left and right rear wheels 19 is ensured when traveling on the uneven road surface. Thus, the running stability of the forklift 11 can be obtained.

  (3) The angle difference is set so that the swing angle α is larger than the swing angle β. Further, the CPU 35 is configured to output an unlock signal to the control valve 23 when the swing angle θ is smaller than the swing angle α and within a range larger than the swing angle β. Therefore, even if the swing angle β is set to a level close to the horizontal so that the timing for performing the swing restriction control is set to be just before the uneven road surface is removed, the rear wheel 19 rolls on the uneven road surface with small undulations. In this case, since the swing angle θ does not reach the swing angle α, the CPU 35 does not perform the swing restriction control. Therefore, frequent switching control of locking and unlocking of the rear axle 20 can be prevented.

  (4) The swing suppression mode can be executed by using the swing angle sensor 30 and the damper 22 that have been conventionally incorporated in the forklift 11 without adding new sensors or members. Therefore, it is possible to suppress the swing of the rear axle 20 that occurs when the vehicle is removed from the uneven road surface without increasing the number of parts.

  (5) The CPU 35 uses a condition as to whether or not the lock timer T is equal to the specified lock time T1 as an unlock condition for switching the rear axle 20 from locked to unlocked. Therefore, for example, the calculation result is not compared with the case of calculating the detection result detected by the yaw rate sensor and determining whether or not to switch the rear axle 20 from locked to unlocked based on the calculated value. The control configuration can be simplified by a good amount.

The embodiment is not limited to the above, and may be embodied as follows, for example.
O Before executing the swing control mode, a process for determining whether or not to perform the swing control mode may be executed. For example, an inclination sensor (for example, a semiconductor sensor) is provided as an inclination detecting means for detecting the inclination of the vehicle main body 11a with respect to the vehicle width direction with respect to the vehicle main body 11a, and the CPU 35 inclines the vehicle main body 11a in the vehicle width direction. It may be determined whether or not to perform the swing suppression mode according to the above. Then, the CPU 35 operates according to the flowchart shown in FIG. If the CPU 35 determines in step S20 that the vehicle main body 11a is in the horizontal state in the vehicle width direction from the detection result detected by the tilt sensor, the process proceeds to step S21 to execute the swing control mode. In the swing control mode in step S21, the same processing as in steps S1 to S15 shown in FIG. 4 is performed, and after the swing control mode is completed, the entire processing is ended. If it is determined in step S20 that the vehicle main body 11a is not in a horizontal state with respect to the vehicle width direction from the detection result detected by the tilt sensor, the process proceeds to step S22, and the tilt flag is turned off and stored in the RAM 37. Next, proceeding to step S22, the CPU 35 executes unlock control, outputs an unlock signal, outputs a stop signal to the timer 38, and ends the entire process. When the CPU 35 performs such control, when the forklift 11 is running with the vehicle body 11a tilted with respect to the vehicle width direction, the rear axle 20 is locked even when the rear wheel 19 is removed from the uneven road surface. Not performed. Therefore, it is possible to prevent a situation in which the rear wheel 19 is lifted off the road surface which is caused by locking the rear axle 20 while the forklift 11 is traveling on a road surface inclined with respect to the vehicle width direction.

  Priority is given to the lock and unlock control of the damper 22 performed by control other than the swing control mode, and the swing control mode is executed at predetermined intervals only when control other than the swing control mode is not performed. You may comprise. For example, in order to ensure the running stability of the forklift 11, the rear axle 20 should be locked based on characteristics such as the yaw rate, the vehicle speed, the weight of the load transferred to the fork, and the lift height of the fork. If it is determined, the CPU 35 is configured to output a lock signal. And when it is judged that it is not necessary to lock the rear axle 20 based on the above-mentioned characteristic, you may comprise so that rocking | fluctuation control mode may be performed.

  In the swing control mode, the unlock condition for switching the rear axle 20 from locked to unlocked may be changed. For example, when the yaw rate sensor is used and the CPU 35 calculates the yaw rate in the roll direction of the vehicle main body 11a detected by the yaw rate sensor and it is determined that the rear axle 20 does not swing based on the calculated value, the rear axle 20 You may comprise so that unlock control which switches from lock to unlock may be performed. In this case, a map indicating the relationship between the yaw rate in the roll direction of the vehicle main body 11a and the threshold value at which it can be determined that the rear axle 20 does not swing is stored in the ROM 36 in advance.

  ○ The processing content in step S1 may be changed. For example, instead of proceeding to step S2 when the swing angle θ is greater than or equal to the swing angle α in step S1, the process may proceed to step S2 when the swing angle θ is greater than the swing angle α.

  ○ The processing content in step S5 may be changed. For example, in step S5, instead of proceeding to step S6 when the swing angle θ is equal to or smaller than the swing angle β, the process may proceed to step S6 when it is smaller than the swing angle β.

  The swing angle α and the swing angle β may be the same angle, and the angle may be used as the reference swing angle γ. However, in this case, it is necessary to set the reference swing angle γ to an angle at which frequent switching control of locking and unlocking does not occur and the driving stability of the target vehicle can be ensured.

As the control valve 23, a normally open type solenoid valve may be used instead of the normally closed type solenoid valve.
The present invention may be applied to a battery-type forklift. Further, the present invention may be applied to industrial vehicles other than fork riffs, for example, tow tractors.

The schematic side view which shows a forklift. The schematic block diagram which shows a rocking | fluctuation control apparatus. The block diagram which shows the electric constitution of a rocking | fluctuation control apparatus. The flowchart of rocking | fluctuation suppression mode. A time chart when the swing suppression mode is executed. The flowchart of the control which CPU performs in another embodiment.

Explanation of symbols

  α ... first reference swing angle, β ... second reference swing angle, θ ... swing angle, 11 ... forklift as an industrial vehicle, 11a ... vehicle body, 20 ... rear axle as an axle, 22 ... damper, 23 ... Control valve, 30... Swing angle sensor as swing angle detection means, 35... CPU constituting first determination means, second determination means, and control means.

Claims (4)

Provided in an industrial vehicle that supports an axle that is swingable in the vertical direction with respect to the vehicle body, and controls the supply and discharge of hydraulic oil to and from a damper disposed between the vehicle body and the axle. In a swing control device for an industrial vehicle that controls locking and unlocking,
Swing angle detecting means for detecting a swing angle indicating an inclination of the axle with respect to the vehicle body;
First determination means for determining whether or not the swing angle has reached a first reference swing angle for determining that the axle is inclined;
Second determination means for determining whether or not the swing angle has reached a second reference swing angle for determining that the axle has swung in a horizontal direction;
Control means for executing swing restriction control for locking the axle when the second determination means makes an affirmative determination after the first determination means makes an affirmative determination;
An industrial vehicle swing control device comprising:   When the predetermined unlock condition is satisfied after the start of the swing restriction control, the control means ends the swing restriction control, unlocks the axle, and unlocks the axle. The swing control device for an industrial vehicle according to claim 1, wherein Inclination detecting means for detecting the inclination of the vehicle body with respect to the vehicle width direction,
When it is determined from the detection result of the tilt detection means that the vehicle main body is not horizontal, the control means executes unlock control for unlocking the axle, and the vehicle main body is determined to be horizontal. In this case, the swing control device for an industrial vehicle according to claim 1 or 2, wherein the swing restriction control is executed based on determination results of the first determination unit and the second determination unit. The first reference swing angle is larger than the second reference swing angle, and a predetermined angle difference is set between the first reference swing angle and the second reference swing angle. And
The control means executes unlock control for unlocking the axle in a range of the angle difference in which the swing angle is smaller than the first reference swing angle and larger than the second reference swing angle. The industrial vehicle swing control device according to any one of claims 1 to 3.

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