JP2006001329A - Steering device of industrial vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device of an industrial vehicle capable of effectively mitigating an impact at the turning limit position of a steering wheel, and saving troubles for adjusting a sensor to detect the steering angle. <P>SOLUTION: A control device to control a driving device to turn a steering wheel comprises a maximum steering angle setting means to set the maximum steering angles L, R of the steering wheel, a steering angle determination means to determine whether or not the present steering angle A is present in a range of the predetermined angle B in which the steering angle is reduced from the maximum steering angles L, R as the absolute value, a steering direction determination means to determine whether the steering direction of the steering wheel is decreased or increased as the absolute value, and a drive control means to control the driving device. The drive control means controls the driving device so that the turning speed of the steering wheel is suppressed when the present steering angle A is determined to be within the above angular range, and the steering direction is the direction in which the steering angle is increased as the absolute value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a steering device used in an industrial vehicle such as a forklift.

  Conventionally, as a steering device used for an industrial vehicle, there is a so-called power steering device that turns a steering wheel provided in a vehicle body by a driving device in accordance with a steering operation, an electric power steering device using an electric motor or the like, A hydraulic power steering device using a hydraulic cylinder or the like is employed.

  Now, when the steering wheel is turned using the thrust and torque generated by the drive device, the handle operating force may be light, and the handle may be operated too quickly. In this case, when the steering wheel is turned to the turning limit position, the turning is suddenly stopped and an impact is generated. However, if the thrust and torque of the drive device are too small to avoid this, the original effect of the power steering device is weakened. Therefore, as disclosed in, for example, Patent Document 1, when the steering angle of a steered wheel is detected and the steered angle is within an angle range near the turning limit of the steered wheel, a technique for suppressing the maximum value of the output of the drive device. Has been proposed.

  By the way, when the sensor for detecting the steering angle of the steered wheel is provided as described above, it is necessary to adjust the sensor so that the angle that becomes the limit of turning is accurately detected. However, such adjustment work is time-consuming because there are errors in manufacturing the steering device and mounting errors for each vehicle. Further, since the sensor itself has individual differences and mounting errors, it takes much time. Therefore, for example, in Patent Document 2, the steering wheel is automatically steered to the turning limit at the time of starting, the sensor is calibrated using the steering angle detected at that time, and the time required for the adjustment work as described above is reduced. A technique that can be omitted is disclosed.

JP 2001-88729 A JP 2000-344122 A

  The present invention can effectively reduce the impact at the turning limit position of the steered wheel instead of the above-described conventional technique, and can save time and effort for adjusting the sensor for detecting the steering angle. An object is to provide a steering device.

  In order to achieve the above-described object, the present invention provides a steering device that steers a steering wheel provided on a vehicle body so as to be capable of turning by a driving device in accordance with a steering operation. In an industrial vehicle steering system comprising a sensor for detecting a steering angle and a control unit for controlling the drive unit based on a detection result of the sensor, the control unit sets a maximum steering angle for the steering wheel. Steering angle setting means and steering angle determination means for determining whether or not the current steering angle detected by the sensor is within a predetermined angle range in a direction in which the steering angle becomes smaller as an absolute value from the maximum steering angle. And a steering direction determining means for determining whether the steering direction of the steered wheel is a direction in which the steering angle is reduced or increased as an absolute value, and a drive control means for controlling the drive device The drive control means determines that the current steering angle is within the angle range by the steering angle determination means, and the steering angle is the absolute value of the direction steered by the steering direction determination means. The driving device is controlled so that the turning speed of the steered wheel is suppressed when it is determined that the direction is larger.

  According to the present invention as described above, when the steering angle approaches the maximum steering angle and falls within the above angle range, the speed at which the steering wheel is driven to turn is suppressed. Therefore, the steering angle can be gradually brought close to the maximum steering angle, and if the maximum steering angle is set to the steering angle corresponding to the turning limit position, the impact when the steering wheel reaches the turning limit position can be reduced. At the same time, it is possible to realize a smooth steering by preventing a sudden turn during traveling. Further, when the steering angle moves away from the maximum steering angle, the turning speed of the steered wheels is not suppressed, so that a speedy response of the steered wheels with respect to the steering operation is obtained, and the operability related to steering is not deteriorated.

  In addition, as a method of suppressing the turning speed of the steering wheel, there is a method of suppressing a speed at which the drive device operates. In the case of using an actuator that performs expansion / contraction operation on the drive device, steering is performed by suppressing the expansion / contraction speed. In the case of using an actuator that rotates in the drive device, the speed at which the steering wheel turns can be suppressed by suppressing the rotation speed. Further, as a method for determining whether the steering wheel is steered in a direction in which the steering angle becomes smaller or larger as an absolute value, for example, the change amount of the steering angle of the steered wheel detected by the sensor is used. In addition to the above-described sensor, a sensor for detecting the operation angle of the handle is provided, and a method of determining based on the amount of change in the operation angle of the handle detected by this sensor. In addition to this, it is possible to make a determination based on the operating direction of the actuator provided in the driving device. In the case of using an actuator that expands and contracts, an actuator that rotates depending on whether the operating direction is the extension direction or the shortening direction is used. Then, it can be determined whether the operating direction is clockwise or counterclockwise.

  The smaller absolute value means that the steering angle decreases in the negative direction when the maximum steering angle is a positive value, and the steering angle when the maximum steering angle is a negative value. Increases in the positive direction. On the other hand, increasing as an absolute value means that the steering angle increases in the positive direction when the maximum steering angle is a positive value, and the steering angle when the maximum steering angle is a negative value. Decreases in the negative direction. Therefore, it is not always necessary to determine the absolute value of the steering angle in order to determine whether the steering angle is reduced or increased.

  In the present invention, the maximum steering angle setting means includes a comparison means for comparing a current steering angle detected by the sensor with a preset maximum steering angle, and the current steering angle is absolute by the comparison means. A time measuring means for measuring a continuation time in which the state determined to be larger than the maximum steering angle as a value and a time when the current steering angle is determined to be larger than the maximum steering angle as an absolute value by the comparison means, Storage means for resetting and storing the maximum steering angle, and the storage means includes a steering angle value detected within the continuation time when the continuation time reaches a predetermined time. The minimum absolute value can be set as the maximum steering angle.

  According to this, if the state where the current steering angle detected by the sensor is larger than the set maximum steering angle as an absolute value continues for a predetermined time, the maximum steering angle is updated to a larger value. Will go. For example, even if the maximum steering angle is not set in advance to the limit angle at which steering is possible, the steering wheel is steered to the limit position for turning during steering, and the state is continued for a predetermined time. The angle is set to the limit angle corresponding to this and stored. Accordingly, by performing the steering, the maximum steering angle can be set accordingly, and it is not necessary to adjust the sensor in advance, so that the labor of the operator can be saved. Furthermore, the absolute value of the steering angle value detected within the duration is set to the maximum steering angle, so that it can be prevented from being affected by disturbance, and the maximum steering angle can be set more accurately. It can be carried out.

  In the present invention, the maximum steering angle setting means includes a comparison means for comparing a current steering angle detected by the sensor with a preset maximum steering angle, and a current steering angle by the comparison means. When the absolute value is determined to be larger than the maximum steering angle, the current steering angle can be reset as the maximum steering angle, and the storage unit can be configured to store, and in this way, If the current steering angle is larger than the set maximum steering angle as an absolute value, the maximum steering angle will be updated to a larger value at any time, so work related to sensor adjustment and maximum steering angle setting Saves time and effort.

  In the present invention, when the steering angle determining means determines that the current steering angle is not within the angle range, and the steering angle determining means determines that the current steering angle is within the angle range. And when the steering direction determining means determines that the steering direction of the steered wheels is a direction in which the steering angle becomes smaller as an absolute value, the drive device is operated at a predetermined operating speed. The steering angle determination means determines that the current steering angle is within the angle range, and the direction steered by the steering direction determination means is a direction in which the steering angle increases as an absolute value. When it is determined that, the drive device can be operated at a speed lower than a speed limit set slower than the operation speed.

  According to this, not only when the steering angle is a direction where the steering angle is reduced as an absolute value, but also when the steering angle is a direction where the steering angle is increased as an absolute value, the current steering angle is within the above angle range. If not, the driving device is operated at an operating speed set to an appropriate value or less, so that the steering wheel can be turned with good driving feeling for the driver. Similarly, even if the current steering angle is within the above angle range, if the steering direction is a direction in which the steering angle becomes smaller as an absolute value, the drive device is operated at the operation speed or lower. On the other hand, if the current steering angle is within the above angle range and the steering direction is a direction in which the steering angle is increased as an absolute value, the drive device is operated at a speed lower than the speed limit that is slower than the operating speed. Therefore, the steering wheel can be turned so that the steering angle gradually approaches the maximum steering angle.

  In the above configuration, the drive control means obtains a difference between the current steering angle detected by the sensor and the maximum steering angle, and a speed limit setting for setting the speed limit to a slower speed as the difference decreases. If the means is provided, the drive device operates at a slower speed limit as the steering angle approaches the maximum steering angle. Accordingly, the turning speed of the steered wheels also decreases accordingly, and the steering angle increases more gently. The steering angle can be approached.

  In an industrial vehicle in which the steering wheel is provided so as to be able to turn left and right in a plan view from a state where the steering wheel is directed in a straight direction (hereinafter referred to as a straight traveling state), the sensor is based on the straight traveling state. The maximum steering angle setting means detects the maximum left steering angle based on the maximum value of the counterclockwise steering angle detected from the straight traveling state detected by the sensor, and the clockwise maximum steering angle from the straight traveling state. The right maximum steering angle can be set for each based on the maximum value of the steering angle. In this way, even if the steered wheel is steered counterclockwise from the straight traveling state or steered clockwise, the steering angle can gradually approach the maximum left and right steering angles. In addition, since the left and right maximum steering angles are set, even if the limit position of the counterclockwise turn and the limit position of the clockwise turn are not symmetric with respect to the straight traveling state, it is possible to The steering angle can be set to an angle corresponding to each limit position.

  As described above, according to the present invention, the steering wheel can be turned so that the current steering angle gradually approaches the maximum steering angle, so the maximum steering angle is set to the steering angle corresponding to the limit position of turning. If set, the impact when the steered wheel reaches the turning limit position can be mitigated. In addition, since the steering wheel is steered so that the steering angle becomes large, the maximum steering angle is updated to a large value at any time, so that it is possible to save the labor of adjusting the sensor and setting the maximum steering angle. it can.

  Hereinafter, an embodiment in which the present invention is applied to a counterbalance forklift will be described with reference to the drawings.

  As shown in FIG. 1, the counterbalance forklift includes a lift device 2 at a front portion of a vehicle body 1, and a fork 3 is supported by the lift device 2 so as to be movable up and down. In addition, a pair of left and right front wheels 4 as drive wheels is provided in the lower front portion of the vehicle body 1, and a pair of left and right rear wheels 5 as steering wheels are provided in the lower rear portion of the vehicle body 1. A weight 6 is provided at the rear part of the vehicle body 1, and a battery 7 is provided at the center in the front-rear direction. A seat 8 on which a driver is seated is provided above the battery 7. In the drawing, 9 is a head guard provided in the vehicle body 1 so as to cover the seat 8 from above.

  A steering handle 10 is rotatably supported at a front position of the seat 8, and the steering handle 10 and an orbit roll (registered trademark) 11 mounted on the vehicle body 1 are connected by an interlocking mechanism (not shown), and the steering The orbit roll 11 operates according to the rotation of the handle 10. An oil tank 12 is mounted at the front position of the battery 7, and a motor 13 that operates by receiving power supply from the battery 7 and a pump 14 driven by the motor 13 are mounted at the rear position of the battery 7. ing. Note that a sensor 15 including an encoder that detects a rotation speed of the steering handle 10, that is, an operation speed, is attached to the interlocking mechanism. The operation speed V detected by the sensor 15 is input to the controller 30 described later.

  As shown in FIG. 2, the rear wheel 5 is supported by a rear axle device 20, and is provided on the vehicle body 1 via the rear axle device 20. The rear axle device 20 is pivotally supported by an axle frame 21 attached to the vehicle body 1, and left and right ends of the axle frame 21, and a pair of left and right knuckles 22 on which the rear wheel 5 is supported, and the axle frame 21. A cylinder 23 having a rod supported and capable of moving back and forth in the left and right direction, an arm 24 that connects the knuckle 22 and the cylinder 23, and a sensor 25 that includes a potentiometer that detects the turning angle of the knuckle 22, that is, the steering angle. It is configured. The cylinder 23 is a double-acting / double-rod hydraulic cylinder, and is disposed somewhat rearward of the position where the knuckle 22 is supported by the axle frame 21. The arm 24 is provided by connecting the rear portions of the left and right knuckles 22 and the left and right ends of the rod of the cylinder 23. Note that the stroke of the rod of the cylinder 23 is set to a predetermined value, and when the rod moves to the limit of this stroke, the left and right knuckles 22 each reach the limit of turning.

  As shown in FIG. 2, the sensor 25 is provided on the turning shaft of the left knuckle 22 and detects the steering angle A of the left knuckle 22. Here, as shown by a solid line in FIG. 3, the left rear wheel 5 is in the straight direction (hereinafter also referred to as a straight state), that is, the rotation axis of the left rear wheel 5 with respect to the left knuckle 22 is in the left-right direction. In this state, the steering angle A is 0. From this state, the counterclockwise plan view is negative of the steering angle A, and the clockwise counterclockwise view is positive. As shown in FIG. 3, as an absolute value, the maximum value of the steering angle A is the left maximum steering angle L counterclockwise in plan view, and the maximum value of the steering angle A is the maximum right steering angle R clockwise in plan view. It is. Further, the left knuckle 22 and the left rear wheel 5 supported by the left knuckle 22 rotate integrally, and the right knuckle 22 and the right rear wheel 5 supported by the left knuckle 22 rotate integrally. The steering angle A of the left knuckle 22 is the steering angle A of the left rear wheel 5.

  As shown in FIG. 2, the pump 14 is connected to the orbit roll 11 and the oil tank 12 by hydraulic piping, and is driven by the motor 13 to suck oil from the oil tank 12 and return to the orbit roll 11. Exhale. When the steering handle 10 is rotated and the orbit roll 11 operates, the oil is supplied from the orbit roll 11 to one oil chamber of the cylinder 23, and the oil discharged from the other oil chamber passes through the orbit roll 11. Then, it is returned to the oil tank 12. When the steering handle 10 is operated clockwise as viewed from the driver on the seat 8, the rod of the cylinder 23 moves to the right in plan view, and accordingly, the left and right knuckle 22 and the rear wheel 5 are left in plan view. Turn around. Conversely, when the steering handle 10 is operated counterclockwise, the rod of the cylinder 23 moves to the left in plan view, and accordingly, the left and right knuckle 22 and the rear wheel 5 each turn clockwise in plan view. If the steering handle 10 is not operated and the orbit roll 11 is not operating in a neutral state, the oil supplied from the pump 14 to the orbit roll 11 is returned to the oil tank 12 as it is.

  The output of the sensor 25, that is, the steering angle A of the left rear wheel 5 is input to the controller 30 mounted on the vehicle body 1, and the controller 30 controls the motor 13 based on the steering angle A and the operation speed V described above. I do. Hereinafter, this control will be described in detail. The controller 30 includes a memory composed of a ROM area, a RAM area, and a battery backup RAM area, and various data relating to the control are stored in this memory.

  As shown in FIG. 4, when the steering angle A is detected by the sensor 25 (S1), the controller 30 sets the left and right maximum steering angles L and R (S2). A comparison using the maximum steering angles L and R and a predetermined angle B (positive value) is performed. That is, whether the steering angle A is equal to or larger than the angle (RB) smaller than the right maximum steering angle R by the predetermined angle B (S3), or the angle larger than the left maximum steering angle L by the predetermined angle B (L + B), that is, absolute It is determined whether the value is equal to or less than an angle smaller than the left maximum steering angle L by a predetermined angle B (S4). If it is determined that the steering angle A is smaller than the angle RB and larger than the angle L + B, that is, L + B <A <RB (NO in S3, NO in S4), the controller 30 causes the motor 13 to The reference rotational speed N to be operated is set to the rotational speed N2 previously stored in the ROM area (S5).

  If it is determined in S3 that the steering angle A is equal to or greater than the angle RB (YES in S3), it is subsequently determined whether the steering angle A is larger than the maximum right steering angle R (S6). If it is determined that the steering angle A is larger than the maximum right steering angle R (YES in S6), the controller 30 sets the reference rotational speed N to the rotational speed N1 (<N2) stored in the ROM area in advance (S7). ). If it is determined in S6 that the steering angle A is smaller than the maximum right steering angle R (NO in S6), the controller 30 determines whether or not the amount of change ΔA per unit time of the steering angle A is smaller than 0, that is, negative. It is determined whether it is the value of (S8). Here, if the amount of change ΔA is smaller than 0 (YES in S8), the steering angle A is changing in a direction of decreasing (a direction of decreasing as an absolute value), and the reference rotational speed N is set to the rotational speed N2. (S5). If the amount of change ΔA is greater than 0 (NO in S8), the steering angle A is changing in a direction of increasing (a direction of increasing absolute value), and the rotational speed N ′ of the motor 13 is calculated ( In step S9, the reference rotational speed N is set to the calculated rotational speed N ′ (S10). In S9, the rotational speed N ′ is calculated as being proportional to the difference between the steering angle A and the maximum right steering angle R. The smaller this difference is, the closer the rotational speed N1 is. The value is close to the number N2.

  In S3 described above, it is determined that the steering angle A is not equal to or greater than the angle RB (NO in S3). Further, in S4, if it is determined that the steering angle A is equal to or smaller than the angle L + B (YES in S4), then It is determined whether or not the steering angle A is smaller than the left maximum steering angle L. If it is determined that the steering angle A is smaller than the left maximum steering angle L (YES in S11), the controller 30 sets the reference rotational speed N to the rotational speed N1 (S7). If it is determined that the steering angle A is greater than the left maximum steering angle L (NO in S11), the controller 30 determines whether or not the change amount ΔA per unit time of the steering angle A is greater than 0, that is, a positive value. It is determined whether or not there is (S12). Here, if the change amount ΔA is larger than 0 (YES in S12), the steering angle A is changed in a direction of increasing (a direction of decreasing as an absolute value), and the reference rotation speed N is set to the rotation speed N2. (S5). If the amount of change ΔA is smaller than 0 (NO in S12), it means that the steering angle A is changing in the direction of decreasing (in the direction of increasing as an absolute value), and the rotational speed N ′ is calculated (S13). A reference rotational speed N is set to the calculated rotational speed N ′ (S10). In S13, the rotation speed N ′ is calculated as being proportional to the difference between the steering angle A and the left maximum steering angle L. The smaller this difference, the closer to the rotation speed N1, and the larger the difference, the rotation. The value is close to the number N2.

  As a result, the relationship between the steering angle A of the left rear wheel 5 and the reference rotational speed N of the motor 13 is expressed, for example, as shown in FIGS. In these figures, LE is the steering angle when the left rear wheel 5 reaches the limit of turning counterclockwise, and RE is the steering angle when the left rear wheel 5 reaches the limit of turning clockwise. It is. LS and RS are initial values of a steering angle, which will be described later. The initial value LS is LS <0 and sufficiently larger than LE (absolute value is small), and the initial value RS is RS> 0 and sufficiently smaller than RE. Value (small value as an absolute value).

  When the reference rotational speed N is set in any of S5, S7, and S10, the operation speed V of the steering handle 10 is detected (S14), and the controller 30 operates the chopper that operates the motor 13 based on the operation speed V. The duty D is set (S15). Here, the relationship between the operation speed V and the chopper duty D is preset as shown in FIG. 6, and the chopper duty D is set to D = 20% when the operation speed V is less than the predetermined speed V1. In the range of V1 or more and less than V2 (> V1), the value increases or decreases between 20% and 100% in proportion to the operation speed V, and in the range of V2 or more, D = 100%. And the controller 30 controls the motor 13 according to this chopper duty D and the reference | standard rotation speed N set previously (S16). As a result, an amount of oil corresponding to the number of rotations of the motor 13 is discharged from the pump 14, the rod of the cylinder 23 moves at a speed corresponding to this amount, and the left and right knuckles 22 and the rear wheels 5 turn.

  In the above, the processing for setting the maximum steering angles L and R in S2 corresponds to the maximum steering angle setting means in the present invention, and the steering angle A and the maximum steering angles L and R in S3, S6, and S4 and S11 are used. The process of performing the comparison corresponds to the steering angle determination unit, and the process of determining whether the change amount ΔA of the steering angle A per unit time in S8 and S12 is positive or negative corresponds to the steering direction determination unit. Further, the processing from S4, S6, S8, S12 to the drive control of the motor 13 in S16 corresponds to the drive control means in the present invention. In particular, the rotational speed N ′ is calculated in S9, S13, and in S10. The process of setting the reference rotational speed N to the rotational speed N ′ corresponds to the speed limit setting means.

  The process for setting the maximum steering angles L and R in S2 described above will be described in detail below. That is, as shown in FIG. 7A, first, it is determined whether or not the activation flag is set (S20). If it is not set (NO in S20), the maximum steering angle L stored in advance in the ROM area is determined. , R are read out (S21), and the current maximum steering angles L, R stored in the battery backup RAM area (hereinafter referred to as preset values) LL, RL are read out. Read (S22). Then, the initial values LS and RS are compared with the preset values LL and RL, respectively. Here, the preset values LL and RL are both set to 0 in the initial state, that is, in the state where the steering angle A has never been detected or the battery backup RAM area is cleared. For the right maximum steering angle R, the initial value RS and the preset value RL are compared (S23). For example, when the preset value RL = 0, the initial value RS is larger (NO in S23). The initial value RS is adopted as the value of the maximum steering angle R, and the right maximum steering angle R is set to the initial value RS (S24). If the preset value RL is larger (YES in S23), the preset value RL is adopted as the value of the right maximum steering angle R, and the right maximum steering angle R is set to the preset value RL (S25). Similarly, for the left maximum steering angle L, the initial value LS and the preset value LL are compared (S26). For example, when the preset value LL = 0, the initial value LS is smaller (YES in S26). ), The initial value LS is adopted as the value of the left maximum steering angle R, and the left maximum steering angle R is set to the initial value LS (S27). If the preset value LL is smaller (NO in S26), the preset value LL is adopted as the value of the left maximum steering angle L, and the left maximum steering angle L is set to the preset value LL (S28). Then, when the setting of the left and right maximum steering angles L and R by the initial values LS and RS is completed, the activation flag is set (S29). Since the activation flag is set in the RAM area, the setting is canceled when the main power of the forklift is turned off and the power supply to the controller 30 is cut off.

  If it is determined that the start flag is set in S29 or the start flag is set in S20 (YES in S20), the controller 30 sets the left and right maximum steering angles L and R by the steering angle A. That is, as shown in FIG. 7B, the steering angle A is compared with the maximum right steering angle R and the maximum left steering angle L (S30, S31), and if the steering angle A is larger than the maximum right steering angle R (YES in S30). ), A process for updating the right maximum steering angle R is performed. If the steering angle A is smaller than the left maximum steering angle L (YES in S31), a process for updating the left maximum steering angle L is performed. If the steering angle A is smaller than the maximum right steering angle R (NO in S30) and larger than the maximum left steering angle L (NO in S31), the minimum value of the steering angle A currently stored in the RAM area. Amin and the maximum value Amax are initialized (S32). Here, the minimum value Amin is initialized to a value that is sufficiently larger than RE (a value that is large as an absolute value), and the maximum value Amax is initialized to a value that is sufficiently smaller than LE (a value that is large as an absolute value). It is said. Further, the timer provided in the controller 30 is cleared to set the time keeping time to 0 (S33), the setting of the left and right maximum steering angles L and R by the steering angle A is completed, and the processing is continued from S3 in FIG.

  As shown in FIG. 7B, if the steering angle A is larger in S30 (YES in S30), the time is advanced by the timer provided in the controller 30 (S34), and is the steering angle A smaller than the minimum value Amin? It is determined whether or not (S35). If the steering angle A is smaller (YES in S35), the steering angle A is stored again in the RAM area as the minimum value Amin (S36), and if the steering angle A is larger (NO in S35), the current time It is determined whether or not the time measured by the timer has elapsed for a preset time t while keeping the minimum value Amin stored in (S37). If the time count has not reached time t (NO in S37), the process proceeds to S3 in FIG. If the measured time has reached time t (YES in S37), the value of the right maximum steering angle R is reset to the minimum value Amin of the steering angle A stored at the present time (S38). Further, the current value of the right maximum steering angle R set in this way is stored as a preset value RL in the battery backup RAM area (S39), and then the timer is cleared to set the time count to 0 (S33). The process proceeds to S3 in FIG.

  On the other hand, if the steering angle A is smaller in S30 (NO in S30) and the steering angle A is smaller in S31 (YES in S31), the time is advanced by a timer provided in the controller 30 (S40). It is determined whether A is larger than the maximum value Amax (that is, whether the absolute value is smaller than the maximum value Amax) (S41). If the steering angle A is larger (YES in S41), the steering angle A is stored again in the RAM area as the maximum value Amax (S42), and if the steering angle A is smaller (NO in S41), the current time It is determined whether or not the time measured by the timer has elapsed for a preset time t while keeping the maximum value Amax stored in (S43). If the measured time has not reached time t (NO in S43), the process proceeds to S3 in FIG. 4 as it is. If the measured time has reached time t (YES in S43), the value of the left maximum steering angle L is reset to the maximum value Amax of the steering angle A stored at the present time (S44). Further, the current value of the left maximum steering angle L set in this way is stored as a preset value LL in the battery backup RAM area (S45), and then the timer is cleared to set the time count to 0 (S33). The process proceeds to S3 in FIG.

  In the above description, the process of comparing using the steering angle A and the maximum steering angles L and R in S30 and S31 corresponds to the comparison means in the present invention, and the time measurement process by the timer provided in the controller 30 corresponds to the time measurement means. Among the steering angles A detected from the start of the time measurement by the timer until the time t elapses, the right maximum steering angle R is set using the minimum value Amin, and the left maximum is set using the maximum value Amax. The process of setting the steering angle L and storing these corresponds to the storage means.

  According to such a forklift, in the initial state, the initial values LS and RS are adopted as the left and right maximum steering angles L and R. Therefore, the steering angle A of the left rear wheel 5 at this time and the reference rotation of the motor 13 The relationship with the number N is expressed as shown in FIG. When the steering wheel 10 is operated from this state and the left rear wheel 5 is steered until the steering angle A is smaller than the initial value LS and larger than the initial value RS, the steering angle A and the reference rotation after that are steered. The relationship with the number N is expressed as shown in FIG. Further, when the steering handle 10 is largely operated and the rod of the cylinder 23 moves to the stroke limit, the relationship between the steering angle A and the reference rotational speed N after that is expressed as shown in FIG. .

  5B and 5C show the case where the left rear wheel 5 is steered counterclockwise and clockwise in plan view, but the relationship between the steering angle A and the reference rotational speed N is shown. When the left rear wheel 5 is steered counterclockwise from the straight traveling state, only the left side in the drawing, that is, the range where the steering angle A is smaller than 0 changes, and the steering is steered clockwise from the straight traveling state. In the figure, only the right side in the figure, that is, the range where the steering angle A is larger than 0 changes.

  As described above, according to this embodiment, the rear wheel 5 is steered, and the steering angle A reaches the range of the angle B in a direction that decreases from the left and right maximum steering angles L and R as absolute values. Then, when the steering angle A is steered in the direction in which the absolute value increases, the reference rotational speed N of the motor 13 is limited to a smaller value from the rotational speed N2 as the steering angle A increases. Even if a quick operation is performed (for example, at an operation speed V equal to or higher than the speed V2), the speed at which the rear wheel 5 turns is reduced. Therefore, the rear wheel 5 is steered so that the steering angle A gradually approaches the left and right maximum steering angles L and R. For example, if the left and right maximum steering angles L and R are LE and RE, which are turning limits, respectively, as shown in FIG. 5C, the rear wheel 5 gradually approaches the turning limit position. The occurrence of an impact when the limit position is reached can be suppressed. Further, when there is no possibility of occurrence of an impact, the reference rotational speed N is set to the rotational speed N2, and the motor 13 can operate at the maximum rotational speed N2, so that an appropriate turning speed of the rear wheel 5 is ensured. The driver can obtain a good driving feeling.

  In addition, according to this embodiment, even if LE and RE, which are steering angles representing the turning limit, are not set in advance, the left rear wheel 5 rotates counterclockwise and clockwise until it reaches the turning limit position. If the vehicle is steered, the left and right maximum steering angles L and R are set to LE and RE, respectively. Therefore, for example, it is not necessary to set a steering angle indicating the turning limit in the initial state, and the turning limit position of the rear wheel 5 is different for each forklift, or there is a difference in mounting of the sensor 25 for each forklift. However, since it is not necessary to set the steering angle that represents the limit of turning for each of them, it is possible to save time and labor for adjustment of the sensor 25 and setting of the steering angle. In addition, if the steering angle A is larger than the left and right maximum steering angles L and R as an absolute value for a predetermined time t, and if the steering is in the clockwise direction in a plan view from the straight traveling state, during this time t If the right maximum steering angle R is updated with the minimum value Amin of the steering angle A and the steering is in the counterclockwise direction from the straight traveling state, the maximum left steering angle L with the maximum value Amax of the steering angle A during this time t Therefore, it is possible to prevent the influence of noise and the like and set the left and right maximum steering angles L and R more accurately.

  Furthermore, according to this embodiment, even if LE and RE may become larger than the original due to the secular change of the rear axle device 20 during long-term use, the left rear wheel 5 is changed to the left and right again. If steering is performed until the turning limit is reached, the left and right maximum steering angles L and R are set to LE and RE after changing, respectively, so that no inconvenience occurs. In addition, even if the rear wheel 5 or the sensor 25 is replaced, as long as the preset values RL and LL stored by clearing the battery backup RAM area are returned to 0, the left and right maximum steering angles L, Since R is set to the initial values LS and RS and is updated according to the subsequent steering, it does not take time and labor associated with replacement of parts.

  The start flag set in S29 can be held even after the main power of the forklift is turned off so that it is set in the battery backup RAM area, so that the initial values LS and RS from the next time onwards can be maintained. Setting processing of the left and right maximum steering angles L and R can be omitted. In addition, an operation tool such as a switch that can be operated by the driver is provided, and when this operation tool is operated, the setting of the start flag is canceled or the preset values RL and LL are returned to the initial state. can do. Furthermore, the setting values RL and LL are not stored in the battery backup RAM area, and the left and right maximum steering angles L and R are always set using the initial values LS and RS when the main power of the forklift is turned on. In this way, since the processing related to the preset values RL and LL is not required at all, the setting processing of the left and right maximum steering angles L and R can be simplified.

  Moreover, although the counter balance type forklift was described in the above embodiment, the present invention is not limited to this, and can be applied to other types of forklifts and other industrial vehicles. However, it is more effective to apply the present invention to a vehicle such as a forklift that is frequently and largely steered.

It is a side view concerning the embodiment of the present invention. It is a functional diagram concerning the embodiment of the present invention. It is a schematic diagram concerning the embodiment of the present invention. It is a control flow figure concerning an embodiment of the present invention. It is a control characteristic figure concerning the embodiment of the present invention. It is a control characteristic figure concerning the embodiment of the present invention. It is a control flow figure concerning an embodiment of the present invention. It is a control flow figure concerning an embodiment of the present invention.

Explanation of symbols

1 Car body 4 Front wheel (drive wheel)
5 Rear wheels (steering wheels)
DESCRIPTION OF SYMBOLS 10 Steering handle 11 Orbit roll 12 Oil tank 13 Motor 14 Pump 15 Sensor 20 Rear axle device 21 Axle frame 22 Knuckle 23 Cylinder 24 Arm 25 Sensor 30 Controller A Steering angle L Left maximum steering angle R Right maximum steering angle N Reference rotation speed of motor V Operating speed D Motor chopper duty

Claims (4)

A steering device that steers a steering wheel that is provided on a vehicle body so as to be able to turn by a drive device according to a steering operation, and detects a current steering angle of the steering wheel, and detection of the sensor In a steering device for an industrial vehicle comprising a control device for controlling the drive device based on the result,
The control device detects maximum steering angle setting means for setting the maximum steering angle of the steered wheels, and is detected by the sensor within a predetermined angle range in a direction in which the steering angle becomes smaller as an absolute value from the maximum steering angle. Steering angle determination means for determining whether or not there is a current steering angle; steering direction determination means for determining whether the steering direction of the steered wheel is a direction in which the steering angle decreases or increases as an absolute value; Drive control means for controlling the drive device,
The drive control means determines that the current steering angle is within the angle range by the steering angle determination means, and the direction steered by the steering direction determination means is a direction in which the steering angle increases as an absolute value. A steering apparatus for an industrial vehicle, characterized in that, when it is determined that there is a vehicle, the drive device is controlled so that the turning speed of the steering wheel is suppressed. The maximum steering angle setting means includes a comparison means for comparing a current steering angle detected by the sensor with a preset maximum steering angle, and the maximum steering angle with the current steering angle as an absolute value by the comparison means. A time measuring means for measuring the duration of time during which the state determined to be greater than the angle continues, and a maximum steering angle when the current steering angle is determined to be larger than the maximum steering angle as an absolute value by the comparison means. Storage means for resetting and storing,
The storage means sets, when the duration time reaches a predetermined time, the smallest steering angle value detected within the duration time as a maximum steering angle as an absolute value. The steering device for an industrial vehicle according to claim 1. The drive control unit determines that the current steering angle is within the angle range when the steering angle determination unit determines that the current steering angle is not within the angle range, and the steering angle determination unit determines that the current steering angle is within the angle range. And when the steering direction determining means determines that the steering direction of the steered wheel is a direction in which the steering angle is reduced as an absolute value, the drive device is operated at a predetermined operating speed or less,
When it is determined by the steering angle determination means that the current steering angle is within the angle range, and the steering direction is determined by the steering direction determination means to be a direction in which the steering angle is increased as an absolute value. 3. The steering device for an industrial vehicle according to claim 1, wherein the drive device is operated at a speed lower than a speed limit set slower than the operation speed.   The drive control means includes a speed limit setting means for obtaining a difference between the current steering angle detected by the sensor and the maximum steering angle, and setting the speed limit to a slower speed as the difference is smaller. The steering device for an industrial vehicle according to claim 3, wherein the steering device is an industrial vehicle.

Images