JP2011131777A - Steering device for forklift - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device for a forklift having a fail-safe mechanism of not making steering impossible even if one steering motor causes a failure while being capable of laterally independent steering. <P>SOLUTION: The steering device includes a steering mechanism for steering a vehicle and a plurality of steered mechanisms for turning a steered wheel mechanically unconnected to the steering mechanism where the steered mechanisms have individually steering actuators with an electric motor as a power source, and turns the steered wheel, and is characterized in that the steered mechanisms are constituted so as to independently turn the steered wheel at different steering angles, and have the fail-safe mechanisms for mechanically transmitting drive forces of one steering actuator to the other steering actuator when a failure occurs in the steering actuator. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a steering device for an industrial vehicle, and a steer-by-wire electric steering device mainly used for a counter-type forklift.

  Conventionally, as a steering device for a counter-type forklift, a hydraulic system has been used because of the merit of on-vehicle layout. The hydraulic system does not require a mechanical connection between the steering wheel and the steering mechanism, and the steering device can be configured with a simple configuration.

  However, in a steering device using hydraulic pressure, there are problems of energy consumption in a hydraulic pump that generates hydraulic pressure and environmental load due to the use of oil. In addition, since it is driven by a hydraulic cylinder, the structure around the steered wheels is complicated, so there is a problem that the degree of freedom in layout is small and maintenance is not easy.

  As prior arts for improving this part, there are those disclosed in Patent Documents 1 and 2. Patent Document 1 is a steering device used for a forklift, and includes an angle sensor that detects a rotation angle of a steering wheel, a steering wheel that changes direction, a turning mechanism that changes the direction of the steering wheel, an angle sensor, and a turning mechanism. The electronic control unit is connected, and the steering wheel and the steering wheel are separated from each other.

  Patent Document 2 is a steer-by-wire system in which left and right steered wheels can be independently driven by a plurality of steering actuators, and has a fail-safe mechanism using wires.

JP 2005-263392 A JP 2007-001564 A

  However, in these prior arts, in a steering apparatus configured with only one electric motor as a drive source for turning, when an abnormality occurs in the electric motor, a steering mechanism such as a steering wheel and a turning mechanism Has a problem that it becomes impossible to steer because there is no mechanical connection. In addition, when equipped with a fail-safe mechanism that consists of a plurality of electric motors and mechanically transmits the driving force between the steering actuators, the left and right independent steering with the steering angle greatly different from right to left cannot be performed. There has been a problem that it is difficult to turn the steering wheel with the turning angle of the steering wheel being opposite in the left-right phase (reverse C-shaped state).

  The present invention relates to a forklift steering device having a fail-safe mechanism that uses an electric motor and that can be independently steered from side to side while simplifying the configuration of the steering device, but does not become unsteerable even if one steering motor fails. The purpose is to provide.

  In order to solve the above problems, the present invention provides a steering mechanism for steering a vehicle, a plurality of steering mechanisms for turning steered wheels that are not mechanically connected to the steering mechanism, and the plurality of turning mechanisms. The steering mechanism is provided with an individual steering actuator that uses an electric motor as a power source, and in the steering device that steers the steered wheels, the plurality of steerable mechanisms independently rotate the steered wheels at different steering angles. It is configured to be steerable, and has a fail-safe mechanism that mechanically transmits the driving force of one steering actuator to the other steering actuator when an abnormality occurs in the steering actuator. It is characterized by that.

  The steering mechanism has a steering actuator housing fixed to the vehicle, and has a pitman arm that outputs the rotational motion of the steering actuator as a rocking rotational motion, and is connected to the pitman arm. The steered wheel is steered by moving the tie rod.

  The steering mechanism includes a gear housing that has a steering actuator housing fixed to the vehicle and shares a rotating shaft with a steered wheel. The gear swings and rotates the rotating motion of the steering actuator. It is characterized by turning the steered wheels by converting to.

  In the steering mechanism, the housing of the steering actuator is fixed to the vehicle, the rotational axis of the steering actuator is on the turning axis of the steered wheel, and the steered wheel is directly driven by the rotational motion of the steering actuator. It is characterized by turning.

Furthermore, the fail-safe mechanism is slidably engaged with each other, and is constituted by two shafts having through holes in the engaging portion, and each shaft is connected to an individual steering mechanism, A pin or the like is inserted into the through hole to mechanically connect the two shafts.
Furthermore, the fail-safe mechanism includes a connecting hole in the steering mechanism, and mechanically couples the steering mechanism by inserting a substantially U-shaped shaft into the connecting hole in the event of an abnormality. Features.

  Furthermore, one or more pairs of the steering actuators are provided corresponding to the left and right steered wheels of the vehicle. Furthermore, the steering mechanism steers the rear wheels.

  And a steering angle sensor that detects a steering amount of the steering mechanism, and an ECU that controls an electric motor of the steering actuator according to an output of the steering angle sensor.

Further, the ECU is configured to individually output commands to the plurality of electric motors.
Furthermore, the power line connection path between the plurality of electric motors and the ECU has a signal cutting unit individually.

  The steering actuator includes a turning angle sensor that detects a turning angle of a turning wheel, and the ECU detects a difference between a steering amount and a turning angle detected by the steering angle sensor, and the difference It is comprised so that the said electric motor may be controlled based on this.

  Furthermore, the steering mechanism has an electric motor that generates a steering reaction force, and the electric motor includes the steering angle sensor.

According to the present invention, a steer-by-wire system in which the steering mechanism and the steering mechanism are connected only by an electric signal via the ECU, and the steered wheels are driven by a steering actuator installed in the vicinity of the steered wheels. There is no need for cylinders, etc., and the structure around the steered wheels is very compact and has a high degree of freedom in layout. In addition, since no hydraulic pressure is used, environmental load is low and maintenance is easy.
Further, in the steering mechanism, each steered wheel has a steering actuator independently, and each steered actuator can be operated individually, so that the steered wheels can be steered independently on the left and right. is there. As a result, the turning performance of the forklift in a narrow space is improved by setting the steered wheels in a reverse C shape and setting the vehicle turning center closer to the vehicle body center on the drive wheel shaft.
Furthermore, when either one of the steering actuators fails, it has an effect that the steering cannot be disabled by having a fail-safe mechanism that mechanically connects the left and right steering actuators using a safe bar or the like.

It is a schematic block diagram which shows 1st Embodiment at the time of applying this invention to a forklift. It is an electric system outline in a 1st embodiment, and a perspective view of a steering mechanism. It is a perspective view of the fail safe mechanism in a 1st embodiment. It is a perspective view of the steering mechanism which shows the modification of 1st Embodiment. It is a perspective view which shows the steering mechanism in 2nd Embodiment. It is a perspective view of the steering mechanism which shows the modification of 2nd Embodiment. It is a perspective view which shows the steering mechanism in 3rd Embodiment. It is a perspective view of the steering mechanism which shows the modification of 3rd Embodiment. It is explanatory drawing of the spot turning in a forklift.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing a first embodiment when the present invention is applied to a forklift. In the forklift 1, front wheels 3FL and 3FR that are driving wheels and rear wheels 3RL and 3RR that are steered wheels are disposed on a vehicle body 2, and a fork 4 is disposed at a front end portion.
A steering mechanism 6 is disposed in front of the driver's seat 5 on the front side of the vehicle body 2, and steering mechanisms 7A and 7B for turning the rear wheels 3RL and 3RR and a fail-safe mechanism 8 are disposed on the rear side of the vehicle body 2. It is installed. Further, an ECU 10 is provided which is supplied with electric power from the battery 9 and controls driving of electric motors (described later) of the steering mechanisms 7A and 7B. The steering mechanism 6 includes a steering wheel 11 and a steering angle sensor 12 that detects the steering angle of the steering wheel 11.

  FIG. 2 is a schematic electrical system and a perspective view of the steering mechanism in the first embodiment. The steering mechanism 6 and the steering actuators 22A and 22B that steer the steered wheels are electrically connected steer-by-wire configurations, so that the left and right steered wheels can be driven independently. Steering actuators are individually provided. The pair of steering actuators 22A and 22B are electrically driven by the ECU 10 and controlled according to the angle information of the steering angle sensor 12 and vehicle information such as the vehicle speed.

  Steering actuators 22A and 22B configured by an electric motor that is a rotational drive source, a speed reducer that increases rotational torque, and a turning angle sensor that detects the turning angle of the steered wheels are stored in housings 23A and 23B. It is fixed to the vehicle body 2. The pitman arms 24A and 24B are swung and rotated by the rotating motion of the steering actuators 22A and 22B, and the steered wheels are steered via the tie rods 25A and 25B connected to the pitman arms 24A and 24B by the swinging and rotating motion. Let The pair of steering actuators 22A and 22B have the same characteristics, and the steering mechanism is disposed symmetrically.

  FIG. 3 is a perspective view of the fail-safe mechanism in the first embodiment. The pair of left and right steering actuators 22A and 22B are connected by a safe bar 21 connected to the pitman arms 24A and 24B. The safe bar 21 is composed of two shafts having through holes in the engaging portion, and the shaft 28 enters the hollow shaft 27 and is slidable. When either one of the steering actuators 22A and 22B is abnormal, the left and right steering actuators 22A and 22B are mechanically coupled by inserting the pins 26 into the engaging portions of the two shafts. Steering is possible with a steering actuator.

  A steering angle sensor 12 connected to the steering wheel 11 rotates integrally with the steering wheel 11 and outputs a voltage according to the steering angle, and the signal is sent to the ECU 10 of the steering device. The ECU 10 also receives signals from the turning angle sensors built in the turning actuators 22A and 22B, and controls the steering device based on the difference in angle information from the steering angle sensor and the turning angle sensor. The ECU 10 is supplied with power from the battery 9 and performs various calculations necessary for steering control. Based on the calculation results, the ECU 10 individually gives an electric motor drive command to each electric motor in the steering actuators 22A and 22B. The electric motor is driven by sending. The rotation output from the electric motor is output as a swinging motion via the pitman arms 24A and 24B and steers the steered wheels via the tie rods 25A and 25B.

  The fail-safe mechanism includes a safe bar 21 that is configured by two shafts and in which a shaft 28 enters a hollow shaft 27 and is slidable. Under normal conditions, the two shafts are slidable, and the left and right steering actuators 22A and 22B can operate independently. When an abnormality occurs in either one of the steering actuators, a means for notifying the driver of the abnormality is provided. At that time, the driver inserts the pin 26 into the engaging portion of the two shafts, and the left and right rolling actuators are provided. By steering the steering actuators 22A and 22B mechanically, steering can be performed with a normal steering actuator. At this time, it is possible to idle the electric motor by cutting the electric motor power line of the steering actuator that has become abnormal.

  In the present embodiment, since two actuators are mounted, even if one of the actuators becomes inoperable, the remaining actuators can be used for steering, and the steering is not disabled. Since the turning actuators 22A and 22B have built-in turning angle sensors, it is not necessary to attach the turning angle sensor to the vehicle side, and the turning mechanism can be downsized. In addition, since each of the steering actuators 22A and 22B can steer the steered wheels at different steered angles, the turning direction of the left and right steered wheels can be freely set. Therefore, as shown in FIG. 9, the left and right steered wheels are steered in opposite phases and steered into a reverse C-shape, thereby arranging the vehicle turning center at a location close to the vehicle center on the drive wheel shaft, and narrow It is possible to turn in space. Furthermore, the actuator can be installed in the vicinity of the steered wheels compared to a hydraulic cylinder type, rack, or ball screw type steering device, so a compact configuration can be realized, and the degree of freedom in the layout near the rear wheels is high. Moreover, since no hydraulic pressure is used, there is no problem of environmental load and handling becomes easy.

  FIG. 4 is a perspective view of a steering mechanism showing a modification of the first embodiment. In this modification, a U-shaped safe bar 31 having a substantially U-shape is separately provided as a fail-safe mechanism, which is an alternative to the safe bar 21. When an abnormality occurs in any of the steering actuators, a means for notifying the driver of the abnormality is provided, and the driver inserts the U-shaped safe bar 31 into a hole provided in the pitman arms 24A and 24B. By doing so, the left and right steering actuators 22A and 22B are mechanically coupled and can be steered by a normal steering actuator.

Next, FIG. 5 is a perspective view showing a steering mechanism in the second embodiment. In the second embodiment, the steering mechanism is configured by a steering actuator and a gear provided on the rotating shaft of the steered wheel.
Steering actuators 42A and 42B composed of an electric motor that is a rotational drive source and a turning angle sensor that detects the turning angle of the steered wheels are housed in housings 43A and 43B and are fixed to the vehicle body 2. . The rotational motion from the steering actuators 42A, 42B is converted into swinging rotational motion by the gears 44A, 44B rotatably supported with respect to the vehicle body 2 by the king pins 45A, 45B on the turning center axis of the steered wheels. Steer the steered wheels.

  Moreover, the fail safe mechanism is comprised similarly to 1st Embodiment mentioned above. The pair of left and right gears 44 </ b> A and 44 </ b> B are connected by the safe bar 21. The safe bar 21 is composed of two shafts having through holes in the engaging portion, and the shaft 28 enters the hollow shaft 27 and is slidable. When either one of the steering actuators 42A and 42B is abnormal, the left and right gears 44A and 44B are mechanically coupled by inserting the pin 26 into the engaging portion of the two shafts, and for normal steering. Steerable by an actuator.

  In the present embodiment, a steering angle sensor is built in the steering actuator, so that no angle sensor is required to be attached to the vehicle, no reduction gear is required, and the steered wheels are directly driven by gears to link mechanisms, etc. The steering mechanism can be made compact. Although not shown in the figure, the addition of cover means such as housing the gears 44A and 44B in the housing can prevent foreign matter from getting caught. Furthermore, since two actuators are provided, even if one of the actuators becomes inoperable, the remaining actuators can be used for steering. The steered actuators 42A and 42B can steer the steered wheels independently at different steering angles. For example, the left and right steered wheels such as a reverse-shaped steering can be steered at different steering angles. You can turn on the ground.

  FIG. 6 is a perspective view of a steering mechanism showing a modification of the second embodiment. In this modification, a U-shaped safe bar 31 having a substantially U-shape is separately provided as a fail-safe mechanism, which is an alternative to the safe bar 21. When an abnormality occurs in any of the steering actuators, a means for notifying the driver of the abnormality is provided, and the driver inserts the U-shaped safe bar 31 into a hole provided in the gears 44A and 44B. As a result, the left and right steering actuators 42A and 42B are mechanically coupled and can be steered by a normal steering actuator.

Next, FIG. 7 is a perspective view showing a steering mechanism in the third embodiment. In the third embodiment, the steering mechanism is configured such that a steering actuator is disposed on the turning center axis of the steered wheel, and the rotational output of the actuator directly steers the steered wheel.
Steering actuators 52A and 52B composed of an electric motor that is a rotational drive source and a steering angle sensor that detects the steering angle of the steered wheels are housed in housings 53A and 53B, and the steering actuators 52A and 52B. Is fixed to the vehicle body 2 at a position where the rotation center axis is the same as the turning wheel turning center axis 55. The rotational motions of the steering actuators 52A and 52B are converted into swinging rotational motions by the steered wheel mounting members 54A and 54B fixed to the steered actuators 52A and 52B, and steer the steered wheels.

  Moreover, the fail safe mechanism is comprised similarly to 1st Embodiment mentioned above. The pair of left and right steered wheel mounting members 54 </ b> A and 54 </ b> B are connected by the safe bar 21. The safe bar 21 is composed of two shafts having through holes in the engaging portion, and the shaft 28 enters the hollow shaft 27 and is slidable. When either one of the steering actuators 52A and 52B is abnormal, the left and right steered wheel mounting members 54A and 54B are mechanically coupled to each other by inserting the pins 26 into the engaging portions of the two shafts. Steering is possible with a steering actuator.

  In the present embodiment, it is not necessary to attach an angle sensor to the vehicle by incorporating a steering angle sensor in the steering actuator, and since the steered wheels are directly driven by the actuator, a link mechanism, gears, etc. are not required, The steering mechanism can be made compact. In addition, since there are few restrictions on the layout of the steering mechanism, steering over a wide range of steering angles is possible. By rotating the drive wheels in opposite phases, it is possible to turn on the spot. In addition, since two actuators are provided, even when one of the actuators becomes inoperable, the remaining actuators can be steered and the steering is not impossible.

  FIG. 8 is a perspective view of a steering mechanism showing a modification of the third embodiment. In this modification, a U-shaped safe bar 31 having a substantially U-shape is separately provided as a fail-safe mechanism, which is an alternative to the safe bar 21. When an abnormality occurs in any of the steering actuators, a means is provided for notifying the driver of the abnormality, and the driver then places a U-shaped safe bar 31 in a hole provided in the steered wheel mounting members 54A and 54B. The left and right steering actuators 52A and 52B are mechanically coupled to each other and can be steered by a normal steering actuator.

  Moreover, in the said 1st-3rd embodiment, it can be set as the structure which added the electric motor which generates a steering reaction force to a steering mechanism. In this case, since the angle sensor built in the electric motor can be used as the steering angle sensor, it is not necessary to attach the steering angle sensor separately from the electric motor.

  The steering device of the present invention can be applied to a counter-type forklift.

1 Forklift 2 Car body 3FL, 3FR Front wheel 3RL, 3RR Rear wheel (steered wheel)
4 Fork 5 Driver's seat 6 Steering mechanism 7A, 7B Steering mechanism 8 Fail-safe mechanism 9 Battery 10 ECU
11 Steering wheel 12 Steering angle sensor 21 Safe bar 22A, 22B Steering actuator 23A, 23B Housing 24A, 24B Pitman arm 25A, 25B Tie rod 26 Pin 27 Hollow shaft 28 Shaft 31 U-shaped safe bar 42A, 42B Steering actuator 43A, 43B Housing 44A, 44B Gear 45A, 45B King pin 52A, 52B Steering actuator 53A, 53B Housing 54A, 54B Steering wheel mounting member 55 Steering wheel turning center axis

Claims (13)

A steering mechanism that steers the vehicle, a plurality of steering mechanisms that steer the steered wheels that are not mechanically connected to the steering mechanism, and the steering mechanisms that use an electric motor as a power source In a steering device that individually includes actuators for steering steered wheels,
The plurality of steering mechanisms are configured to be able to steer the steered wheels independently at different steering angles, and when an abnormality occurs in the steering actuator, the driving force of one of the steering actuators A steering device comprising a fail-safe mechanism that mechanically transmits the steering wheel to the other steering actuator.   The steering mechanism has a steering actuator housing fixed to the vehicle, and has a pitman arm that outputs the rotational motion of the steering actuator as a oscillating rotational motion, and a tie rod connected to the pitman arm includes 2. The steering apparatus according to claim 1, wherein the steered wheels are steered by moving.   The steering mechanism includes a gear housing that has a steering actuator housing fixed to the vehicle and shares a rotating shaft with a steered wheel, and the gear converts the rotational motion of the steering actuator into a oscillating rotational motion. 2. The steering apparatus according to claim 1, wherein the steered wheels are steered by doing so.   In the steering mechanism, the housing of the steering actuator is fixed to the vehicle, the rotating shaft of the steering actuator is on the turning shaft of the steered wheel, and the steered wheel is directly rotated by the rotational motion of the steered actuator. 2. The steering apparatus according to claim 1, wherein the steering apparatus is steered.   The fail-safe mechanism is slidable by being engaged with each other, and is constituted by two shafts having through holes in the engaging portion. Each shaft is connected to an individual steering mechanism, and a pin or the like is provided in the event of an abnormality. The steering apparatus according to any one of claims 1 to 4, wherein the two shafts are mechanically coupled by inserting a shaft into the through hole.   The fail-safe mechanism includes a connecting hole in the steering mechanism portion, and a mechanical mechanism is mechanically coupled by inserting a substantially U-shaped shaft into the connecting hole in an abnormal state. The steering device according to claim 1.   The steering apparatus according to any one of claims 1 to 6, wherein at least one pair of the steering actuators is provided corresponding to the left and right steered wheels of the vehicle.   The steering apparatus according to claim 1, wherein the steering mechanism steers a rear wheel.   9. A steering angle sensor for detecting a steering amount of the steering mechanism, and an ECU for controlling an electric motor of the steering actuator according to an output of the steering angle sensor. The steering apparatus as described.   The steering apparatus according to claim 9, wherein the ECU is configured to individually output a command to the plurality of electric motors.   The steering apparatus according to any one of claims 9 to 10, further comprising a signal cutting unit in a power line connection path between the plurality of electric motors and the ECU.   The steering actuator has a turning angle sensor that detects a turning angle of a turning wheel, and the ECU detects a difference between a steering amount and a turning angle detected by the steering angle sensor, and based on the difference. The steering device according to claim 9, wherein the steering device is configured to control the electric motor.   13. The steering apparatus according to claim 9, wherein the steering mechanism includes an electric motor that generates a steering reaction force, and the electric motor includes the steering angle sensor.

Images