Steering system for industrial vehicles

Abstract

To provide a steering device of an industrial vehicle which can more surely prevent steering force of manual steering being made heavier by rounding a motor, when the industrial vehicle is in a manual steering state, with a more simple configuration.SOLUTION: A steering device 100 of an industrial vehicle is configured to switch between an automatic steering state and a manual steering state. The steering device 100 of the industrial vehicle includes: a steering shaft 21 rotated according to steering of a steering vehicle of the industrial vehicle; a manual steering part 20 for rotating the steering shaft 21 according to manual operation of a steering operation part; an automatic steering part 30 for rotating the steering shaft 21 by driving a first gear 31 rotated according to operation of a motor and a second gear 32 provided on the steering shaft 21 side; and a rotation shaft moving part 40 which is configured so as to move the position of at least one rotation shaft of the first gear 31 and the second gear 32, between an engagement position P1 where the first gear 31 and the second gear 32 are engaged with each other, and an idling position P2 where the first gear 31 and the second gear 32 are separated from each other.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a steering device for an industrial vehicle.

Background Art

[0002] Conventionally, a steering switching mechanism that switches between two systems, a manual steering system directly connected to a steering wheel and an automatic steering system directly connected to an electric motor, is known (for example, Patent Document 1). In the mechanism described in Patent Document 1, by interposing a clutch mechanism in the automatic steering system, the gear group and the electric motor constituting the automatic steering system are idling when manually steering, and the steering operation of manual steering is made heavier. It is intended to suppress the increase.

Prior Art Documents

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a configuration in which a clutch mechanism is interposed in the automatic steering system as in the above prior art, it is necessary for the clutch mechanism to operate reliably, and the steering device tends to become complicated. Therefore, it is desirable to suppress the increase in the steering force of manual steering due to the rotation of the motor when the industrial vehicle is in the manual steering state with a simpler configuration and more reliably.

Means for Solving the Problems

[0005] A steering system for an industrial vehicle according to one aspect of the present invention is configured to be switchable between an automatic steering state and a manual steering state, and comprises a steering shaft that rotates in accordance with the steering direction of the steering wheels of the industrial vehicle; a manual steering unit that rotates the steering shaft in accordance with the manual operation of the steering control unit; an automatic steering unit that rotates the steering shaft by a first gear that rotates in accordance with the operation of a motor, which drives a second gear provided on the steering shaft side; and a rotating shaft moving unit configured to move the position of at least one of the rotating shafts of the first gear and the second gear between a meshing position in which the first gear and the second gear mesh with each other and a free-spinning position in which the first gear and the second gear are separated.

[0006] According to one aspect of the present invention, a steering device for an industrial vehicle is configured such that the position of at least one of the rotating shafts of the first gear and the second gear is movable between a meshing position and an idle position by a rotating shaft moving part. By moving the rotating shaft so that its position is in the meshing position, for example, when the industrial vehicle is in an automatic steering state, the operation of the motor is transmitted to the steering shaft via the first gear and the second gear, thereby realizing automatic steering. On the other hand, by moving the rotating shaft so that its position is in the idle position, for example, when the industrial vehicle is in a manual steering state, the steering force of manual steering is not input from the second gear to the first gear. As a result, compared to a configuration in which, for example, a clutch mechanism is interposed in the automatic steering part, it is possible to suppress the increase in steering force due to the motor's rotation when the industrial vehicle is in a manual steering state with a simpler configuration and more reliable method.

[0007] In order to suitably achieve the above effects, the rotating shaft moving part may specifically include a sliding mechanism that slides the rotating shaft so that the first gear can move forward and backward relative to the second gear, a hydraulic cylinder that brings the first gear closer to the second gear, and an elastic member that moves the first gear away from the second gear.

[0008] In one embodiment, the manual steering unit includes a stopper member that rotates together with the steering shaft and a receiving member that defines the range of rotation of the steering shaft when the stopper member abuts against it. The rotating shaft movement unit may move the position of the rotating shaft to the free-spinning position when the industrial vehicle is in a manual steering state. In this case, even if the structure is such that an impact load is generated in the manual steering unit when the stopper member abuts against the receiving member, moving the rotating shaft to the free-spinning position prevents the impact load generated by manual steering from being input from the second gear to the first gear. This eliminates the need to reinforce the first and second gears to prepare for impact loads. [Effects of the Invention]

[0009] According to one aspect of the present invention, it is possible to suppress, with a simpler configuration and more reliably, the increase in steering force due to the motor's rotation when an industrial vehicle is in a manually steered state. [Brief explanation of the drawing]

[0010] [Figure 1] This is a side view of an exemplary industrial vehicle to which a steering system according to one embodiment of the industrial vehicle is applied. [Figure 2] Figure 1 is a partial cross-sectional view showing the steering system of an industrial vehicle in a left-side view of the vehicle. [Figure 3] Figure 1 is a partial cross-sectional view showing the steering system of an industrial vehicle as seen from the rear of the vehicle. [Figure 4] This is a partial cross-sectional view showing the abutment member and receiving member of the manual steering mechanism in an oblique view. [Figure 5] This is a partial cross-sectional view showing the configuration of the rotating shaft movement section in plan view. [Figure 6] This is a partial cross-sectional view showing an example of the operation of the rotating shaft movement part in a plan view. [Figure 7] Figure 1 is a block diagram showing the functional configuration of the steering system of an industrial vehicle. [Figure 8] Figure 7 is a flowchart showing an example of controller processing. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same or equivalent elements will be denoted by the same reference numerals, and redundant descriptions will be omitted. In the following description, "front and rear" corresponds to the front-rear direction of the industrial vehicle, and "front" corresponds to "FR" in the drawings. "Left and right" corresponds to the width direction of the industrial vehicle, and "right" corresponds to "RH" in the drawings. "Up and down" corresponds to the height direction of the industrial vehicle, and "up" corresponds to "UP" in the drawings.

[0012] Figure 1 is a side view of an exemplary industrial vehicle to which a steering system for an industrial vehicle according to one embodiment is applied. The industrial vehicle 10 is configured to be switchable between an automatic steering state and a manual steering state. The automatic steering state is a state in which the industrial vehicle 10 can automatically steer and drive without requiring steering operations from a worker riding in the industrial vehicle 10. In the automatic steering state, a worker may or may not be riding in the industrial vehicle 10. The manual steering state is a state in which the industrial vehicle 10 steers and drives in response to steering operations from a worker riding in the industrial vehicle 10.

[0013] As shown in Figure 1, the industrial vehicle 10 comprises a body 1 including a driver's seat 2, a front frame 3, and a rear frame 4. The driver's seat 2 is located, for example, in the center of the industrial vehicle 10 in the longitudinal direction. The front frame 3 includes a frame and exterior panels 3a located in front of the driver's seat 2. The rear frame 4 includes a frame and exterior panels 4a located behind the driver's seat 2. The driver's seat 2 is mounted on the front end of the rear frame 4. A towing mechanism (not shown) for towing a trolley is provided in the center of the rear end of the rear frame 4. The towing mechanism can be connected to or disconnected from the trolley by operating a lever operated by a worker seated in the driver's seat 2.

[0014] At the lower center of the front part of the vehicle body 1, a steering wheel 5 is provided. On both the left and right sides of the rear part of the vehicle body 1, a pair of drive wheels 6 are provided. Inside the rear frame 4 behind the driver's seat 2, a power unit 7 including a traveling battery and a traveling motor (not shown) are mounted. The traveling motor is driven by the power of the traveling battery to drive the drive wheels 6. That is, the industrial vehicle 10 is configured as a battery-powered electric tractor.

[0015] Here, the industrial vehicle 10 is equipped with components such as various sensors for automatic steering control. A vehicle speed sensor 51 for detecting the speed of the industrial vehicle 10 is provided on the drive wheel 6. The vehicle speed sensor 51 may be provided for a shaft or the like that rotates integrally with the drive wheel 6. The vehicle speed sensor 51 transmits a signal of the detection result of the vehicle speed sensor 51 to a controller 50 described later.

[0016] At the center of the front end of the front frame 3, a front radar sensor 11 for detecting an object in front of the industrial vehicle 10 is provided. The front radar sensor 11 is a detection device that detects an object in front of the industrial vehicle 10 using radio waves (for example, millimeter waves) or light. The front radar sensor 11 may be, for example, a millimeter wave radar.

[0017] At the left and right ends of the front end of the front frame 3, front guide sensors 12 for detecting a guide tape are provided. The front guide sensors 12 detect the position of a guide tape provided on the traveling route. The front radar sensor 11 and the front guide sensors 12 may be provided on a bumper 8 attached to the front end of the front frame 3.

[0018] At the left and right ends of the rear end of the rear frame 4, rear guide sensors 13 for detecting a guide tape are provided. The rear guide sensors 13 detect the position of a guide tape provided on the traveling route.

[0019] A doorpost member 9, for example, in the shape of a rectangular frame, is provided at the rear end of the rear frame 4. A lidar 14 [LiDAR: Light Detection And Ranging] for detecting objects around the industrial vehicle 10 is provided above the doorpost member 9. The lidar 14 is a detection device that uses light to detect objects around the industrial vehicle 10. The lidar 14 transmits light around the industrial vehicle 10 and detects an object by receiving the light reflected by the object. The lidar 14 may be a 2D lidar or a 3D lidar.

[0020] A controller 50 is fixed behind the driver's seat 2 of the rear frame 4. The controller 50 is an electronic control unit that oversees automatic driving control including automatic steering. The controller 50 includes a CPU [Central Processing Unit], a ROM [Read Only Memory], a RAM [Random Access Memory], a CAN [Controller Area Network] communication circuit, etc. In the controller 50, for example, a program stored in the ROM is loaded into the RAM, and various functions are realized by executing the program loaded into the RAM with the CPU. The controller 50 may be composed of a plurality of electronic control units.

[0021] The controller 50 may have a database that stores map information of the location where the industrial vehicle 10 is used. The map information may include predetermined locations set in advance on fixed structures such as shelves as landmark information. The controller 50 may accurately recognize the position of the industrial vehicle 10 using SLAM (Simultaneous Localization and Mapping) technology or the like, utilizing the locations of the landmark information included in the map information and the detection results of the LiDAR 14. The controller 50 generates a route used for the automated driving of the industrial vehicle 10. Based on the pre-set map information, the recognized position of the industrial vehicle 10, the driving state of the industrial vehicle 10 (vehicle speed, etc.), and the surrounding environment recognized by the LiDAR 14, the controller 50 generates an automated driving route using various methods. Based on the recognized position of the industrial vehicle 10, the driving state of the industrial vehicle 10, the surrounding environment recognized by the LiDAR 14, and the generated route, the controller 50 can execute automated driving of the industrial vehicle 10. The controller 50 controls the drive motors so that the industrial vehicle 10 travels along the generated path, and also performs automatic steering by automatically steering the steering wheels 5.

[0022] The controller 50 may perform automatic driving without using a generated path based on the position information of a guide tape provided on the travel path, using the forward guide sensor 12 and the rear guide sensor 13. The controller 50 steers the steering wheels 5 by controlling the steering motor (motor) 33, described later, based on the amount of positional misalignment between the guide tape and the industrial vehicle 10 detected by the forward guide sensor 12 and the rear guide sensor 13. The guide tape is, for example, a magnetic tape.

[0023] Figure 2 is a partial cross-sectional view showing the steering system of the industrial vehicle in Figure 1 from the left side of the vehicle. Figure 3 is a partial cross-sectional view showing the steering system of the industrial vehicle in Figure 1 from the rear of the vehicle. As shown in Figures 1 to 3, the steering system 100 of the industrial vehicle includes a manual steering unit 20 that rotates the steering shaft 21 in response to manual operation of the steering wheel 15.

[0024] The driver's seat 2 is equipped with a steering wheel (steering control unit) 15 for the operator sitting in it to perform steering operations. When the operator sitting in the seat rotates the steering wheel 15, the steering wheels 5 are steered in accordance with the rotation of the steering wheel 15.

[0025] More specifically, a steering column 16 is erected on the front frame 3, facing the operator seated in the driver's seat 2. The steering wheel 15 is connected to the upper end of a steering shaft 17 housed within the steering column 16. The lower end 17a of the steering shaft 17 is pivotally supported by a bearing 17b provided on the floor surface 3b of the front frame 3, allowing it to rotate perpendicular to the floor surface 3b. A first sprocket 22a is fixed to the lower end 17a of the steering shaft 17. The first sprocket 22a rotates integrally with the steering shaft 17.

[0026] As shown in Figures 2 and 3, an intermediate shaft 23, a second sprocket 22b, and a third sprocket 24a are positioned to the left rear of the first sprocket 22a. The intermediate shaft 23 is a shaft that relays the rotation from the steering shaft 17 and transmits it to the steering shaft 21. The lower end 23a of the intermediate shaft 23 is pivotally supported by a bearing 23b provided on the floor surface 3b so as to be perpendicular to the floor surface 3b. The second sprocket 22b and the third sprocket 24a are fixed to the intermediate shaft 23 in order from the top of the vehicle. The second sprocket 22b and the third sprocket 24a rotate integrally with the intermediate shaft 23.

[0027] As shown in Figure 3, a steering shaft 21 and a case 25 are located behind the steering shaft 17. The steering shaft 21 is a shaft that rotates in accordance with the steering direction of the steering wheels 5 of the industrial vehicle 10. The steering shaft 21 receives steering forces from at least one of the steering forces from the steering shaft 17 and the steering force from the steering motor 33, which will be described later. The steering shaft 21 extends, for example, in the vertical direction of the vehicle so as to be perpendicular to the floor surface 3b behind the steering shaft 17. The lower end portion 21a of the steering shaft 21 is pivotally supported by a bearing 21b provided on the floor surface 3b so as to be perpendicular to the floor surface 3b. A second gear 32 (described later) and a fourth sprocket 24b are fixed to the steering shaft 21 in that order from the top of the vehicle. The second gear 32 and the fourth sprocket 24b rotate integrally with the steering shaft 21.

[0028] Below the steering shaft 21, the steering wheel 5 is positioned. The steering wheel 5 has a pair of tires 5a and a steering axle 5b. The steering axle 5b pivotally supports the pair of tires 5a at both ends so that they can rotate around the central axis of the tires 5a. The lower end 21a of the steering shaft 21 is fixed to the center of the steering axle 5b via a connecting member 26. The steering axle 5b rotates in a horizontal plane perpendicular to the steering shaft 21 in accordance with the rotation of the steering shaft 21. In other words, the steering shaft 21 rotates in accordance with the steering direction of the steering wheel 5 of the industrial vehicle 10.

[0029] Figure 4 is a partial cross-sectional view showing the abutment member and receiving member of the manual steering unit in perspective. As shown in Figure 4, the manual steering unit 20 has an abutment member 28 and a receiving member 29. The abutment member 28 is provided on a projection 27 of the connecting member 26. The projection 27 is a member provided so as to project radially from the connecting member 26 toward the steering shaft 21. The shape of the projection 27 is not particularly limited, but for example it is rectangular. On the projection 27, the abutment member 28 is erected along the steering shaft 21 at a position spaced apart from the steering shaft 21 in the radial direction of the steering shaft 21. Therefore, when the steering shaft 21 rotates, the abutment member 28 rotates along the outer circumference of the steering shaft 21.

[0030] A pair of receiving members 29 are provided on the underside of the floor surface 3b, corresponding to the pair of side end faces 28a of the abutment member 28. Note that the floor surface 3b is not shown in Figure 4. The pair of receiving members 29 are positioned relative to the position of the abutment member 28 when the steering wheel 5 is in a straight-ahead position, with the rotation angle of the steering shaft 21 corresponding to the upper limit of the steering angle of the steering wheel 5. Therefore, when the steering shaft 21 rotates to the upper limit of the steering angle, the connecting member 26 and the projection 27 rotate around the axis of the steering shaft 21, and one of the side end faces 28a of the abutment member 28 abuts against the receiving member 29, restricting the rotation of the steering shaft 21. In this way, the abutment member 28 and the receiving member 29 function as a mechanical end mechanism that defines the upper limit of the steering angle of the steering wheel 5.

[0031] The shapes of the protrusion 27 and the receiving member 29 are not particularly limited. The shape of the protrusion 27 may be, for example, a plate, and the shape of the receiving member 29 may be, for example, a rectangular parallelepiped. The shape of the protrusion 27 and the receiving member 29 and the mounting method may be such that they can withstand the impact load when the protrusion 27 and the receiving member 29 abut each other. This impact load is transmitted to the steering shaft 21 via the protrusion 27.

[0032] Figure 5 is a partial cross-sectional view showing the configuration of the rotating shaft moving section in plan view. As shown in Figures 2, 3, and 5, the case 25 is a member for supporting the steering shaft 21 and the automatic steering section 30 described later. The case 25 extends in the left-right direction in an arch shape that, for example, exhibits a U-shape when viewed from the front-rear direction. The case 25 covers the intermediate shaft 23, the second sprocket 22b, the third sprocket 24a, the fourth sprocket 24b, the second gear 32, and the steering shaft 21. The case 25 has a bearing section 25a provided corresponding to the upper end of the steering shaft 21, and rotatably supports the upper end of the steering shaft 21. A reinforcing wall section 25b may be formed at the right end of the case 25 so as to partially surround the steering shaft 21 depending on the load applied to the steering shaft 21. The case 25 is made of a metal such as aluminum and can be formed by casting or the like.

[0033] A first chain 22c is stretched between the first sprocket 22a and the second sprocket 22b. The second sprocket 22b has more teeth than the first sprocket 22a. Therefore, the rotation of the steering shaft 17 is reduced in speed and transmitted to the intermediate shaft 23. A second chain 24c is stretched between the third sprocket 24a and the fourth sprocket 24b. The fourth sprocket 24b has more teeth than the third sprocket 24a. Therefore, the rotation of the intermediate shaft 23 is reduced in speed and transmitted to the steering shaft 21.

[0034] With the manual steering unit 20 described above, in the steering device 100 of the industrial vehicle, when an operator seated in the driver's seat 2 operates the steering wheel 15 (rotates the steering wheel 15), the rotation of the steering wheel 15 is transmitted to the steering shaft 21 via the intermediate shaft 23, enabling the steering of the steering wheels 5 by manual steering.

[0035] Next, the configuration of the steering system 100 for the industrial vehicle, which relates to automatic steering, will be described. The steering system 100 for the industrial vehicle is equipped with a driving changeover switch 52 for switching between an automatic steering state (unmanned driving mode) and a manual steering state (manned driving mode). As shown in Figure 1, the driving changeover switch 52 is provided, for example, on the steering column 16 (see Figure 1). The driving changeover switch 52 switches between the automatic steering state (unmanned driving mode) and the manual steering state (manned driving mode). The driving changeover switch 52 may include a lever for operation by the work vehicle. The driving changeover switch 52 transmits a signal indicating the switch state to the controller 50.

[0036] As shown in Figures 2 and 3, the steering system 100 of the industrial vehicle includes an automatic steering unit 30 that performs automatic steering using a steering motor 33. The automatic steering unit 30 has a steering motor 33 and a reduction unit 34. The steering motor 33 is connected to a controller 50. In the automatic steering state, the steering motor 33 receives control signals related to automatic steering and its rotation is controlled to automatically steer the steering wheels 5. The steering motor 33 can be any known steering motor. The reduction unit 34, as an example, has a first-stage reduction gear 34a and a second-stage reduction gear 34b. For the first-stage reduction gear 34a and the second-stage reduction gear 34b, various known configurations can be adopted as long as the rotational speed of the steering motor 33 can be reduced to a desired rotational speed. Power from the steering motor 33 is transmitted to the steering shaft 21 in the following order: first-stage reduction gear 34a, second-stage reduction gear 34b, first gear 31, and second gear 32.

[0037] The first-stage reduction gear 34a may include, for example, a small-diameter gear on the output shaft side of the steering motor 33, and a case housing a large-diameter gear that meshes with the small-diameter gear, a small-diameter gear, and a large-diameter gear. Here, "small-diameter" and "large-diameter" refer to the relative dimensions of the gears used in the first-stage reduction gear 34a.

[0038] The second-stage reducer 34b may be, for example, a planetary gear mechanism. The second-stage reducer 34b includes, for example, a sun gear which is the input shaft, an internal gear which is the fixed shaft, and a carrier which is the output shaft. The sun gear is connected to an input shaft which is coaxial with the shaft of the large-diameter gear of the first-stage reducer 34a. The internal gear is fixed to the case 25 side. The carrier is fixed to the first gear 31 which is the output destination.

[0039] The first gear 31 and the second gear 32 are reduction gears that can mesh with each other. Here, the first gear 31 and the second gear 32 are, for example, spur gears or helical gears. The first gear 31 is fastened, for example, with bolts to the carrier of the planetary gear mechanism of the second-stage reduction gear 34b. The first rotation axis (rotation axis) 31a of the first gear 31 is coaxial with the planetary gear mechanism of the second-stage reduction gear 34b. The second gear 32 is provided on the steering shaft 21. Here, the second gear 32 is fixed to the steering shaft 21. The second gear 32 is fitted, for example, to the steering shaft 21 by a key or spline. The second rotation axis 32a of the second gear 32 is coaxial with the steering shaft 21. Therefore, here, the first rotation axis 31a and the second rotation axis 32a are, for example, parallel to each other.

[0040] With the automatic steering unit 30 described above, in the steering device 100 of the industrial vehicle, the steering motor 33 rotates in response to the control signal from the controller 50, and the first gear 31, which rotates in response to the operation of the steering motor 33, drives the second gear 32 provided on the steering shaft 21, thereby rotating the steering shaft 21 and enabling steering of the steering wheels 5 by automatic steering.

[0041] The automatic steering unit 30 is equipped with steering angle sensors 55 and 56 for controlling the automatic steering. The steering angle sensor 55 is located on the steering shaft 21 side (see Figure 2). The steering angle sensor 55 detects the rotational speed of the steering shaft 21 using, for example, a sensor gear 55a that meshes with the second gear 32. The steering angle sensor 56 is located on the steering motor 33 side (see Figure 6). The steering angle sensor 56 detects the rotational speed of the steering shaft 21 using, for example, a sensor gear 56a that meshes with the first gear 31. The controller 50 acquires the two detection results from the steering angle sensors 55 and 56 and recognizes whether there is an abnormality in the automatic steering unit 30 by comparing these results. The steering angle sensors 55 and 56 may also be located on the steering shaft 21 side.

[0042] Here, when the industrial vehicle 10 is in a manually steered state, if an operator seated in the driver's seat 2 operates the steering wheel 15, the steering force of the manual steering is transmitted to the steering shaft 21. If, for the sake of comparison, it is assumed that the second gear 32 and the steering motor 33 are always able to transmit power, the steering motor 33 will rotate along with the steering force of the manual steering via the second gear 32 fixed to the steering shaft 21, making it harder for the operator to operate the steering wheel 15. Furthermore, regarding the impact load generated in the manual steering section 20 when the abutment member 28 strikes the receiving member 29, if, for the sake of comparison, it is assumed that the first gear 31 and the second gear 32 are always meshed, then the first gear 31 and the second gear 32 would need to be designed with sufficient strength to withstand this impact load.

[0043] Therefore, the steering device 100 of the industrial vehicle suppresses the rotation and impact load on the steering motor 33 when the industrial vehicle 10 is in a manually steered state by preventing the first gear 31 from engaging with the second gear 32.

[0044] Figure 6 is a partial cross-sectional view showing an example of the operation of the rotating shaft moving part in a plan view. As shown in Figures 5 and 6, the steering device 100 of the industrial vehicle includes a rotating shaft moving part 40 that allows the position of at least one of the first rotating shaft 31a and the second rotating shaft 32a (in this case, the first rotating shaft 31a) to be moved. The rotating shaft moving part 40 allows the position of the first rotating shaft 31a to be moved between a meshing position P1 and a free-spinning position P2.

[0045] The meshing position P1 refers to the positional relationship between the first rotation axis 31a and the second rotation axis 32a such that the first gear 31 and the second gear 32 mesh with each other. In the meshing position P1, the first gear 31 and the second gear 32 mesh with each other with a predetermined backlash, and power transmission is possible between the first gear 31 and the second gear 32. The idle position P2 refers to the positional relationship between the first rotation axis 31a and the second rotation axis 32a such that the first gear 31 and the second gear 32 are separated from each other and not meshing. In the idle position P2, power transmission is impossible between the first gear 31 and the second gear 32. The idle position P2 is located a predetermined straight-line distance away from the meshing position P1 along a virtual straight line 41 connecting the first rotation axis 31a and the second rotation axis 32a. The predetermined straight-line distance is greater than the meshing depth between the teeth of the first gear 31 and the teeth of the second gear 32.

[0046] As an example, the rotating shaft moving section 40 has a sliding mechanism 42 that allows the first rotating shaft 31a to slide relative to the second gear 32 so that the first gear 31 can move back and forth. The sliding mechanism 42 is a mechanism for moving the position of the first rotating shaft 31a on a virtual straight line 41. The sliding mechanism 42 includes, for example, a guide recess 43 formed on the upper surface 25c of the case 25, and a sliding section 44 that moves along the guide recess 43. The guide recess 43 guides the sliding section 44 so that it slides along the virtual straight line 41.

[0047] Specifically, the guide recess 43 includes, for example, a pair of guide wall portions 43a parallel to the virtual straight line 41, and end wall portions 43b connecting both ends of the pair of guide wall portions 43a to each other. The guide recess 43 is a region enclosed by the guide wall portions 43a and the end wall portions 43b, and is recessed to, for example, a predetermined depth.

[0048] The extended length of the pair of guide wall portions 43a corresponds to a predetermined linear distance from the meshing position P1 to the free-rotating position P2. The planar shape of the end wall portion 43b corresponds to the outer circumference shape of the slide portion 44 located at the meshing position P1 or the free-rotating position P2. Therefore, the planar shape of the recess of the guide recess 43 here is oval. The width dimension (diameter of the cylinder) perpendicular to the virtual straight line 41 and the first rotation axis 31a of the slide portion 44 is less than the distance between the guide wall portions 43a, for example, slightly smaller than the distance between them. In plan view, the end wall portion 43b has an arc shape with a diameter equal to the distance between the guide wall portions 43a.

[0049] The sliding portion 44 is a part that slidably supports the configuration on the first rotation shaft 31a side of the automatic steering unit 30. The sliding portion 44 may also serve as the bottom of the planetary gear mechanism of the second-stage reduction gear 34b, for example. The shape of the sliding portion 44 is cylindrical with the first rotation shaft 31a as the center, similar to the bottom of the planetary gear mechanism of the second-stage reduction gear 34b. The sliding portion 44 may be a separate component from the bottom of the planetary gear mechanism of the second-stage reduction gear 34b.

[0050] The sliding portion 44 is mounted slidably to the upper surface 25c of the case 25 while fitted into the guide recess 43. As an example, the sliding mechanism 42 may include a pair of oval through holes 45 provided in the case 25 along a virtual straight line 41, and a fastening member 46 inserted through the oval through holes 45. The length of the oval through holes 45 is equivalent to the extended length of the pair of guide wall portions 43a. The fastening member 46 screws onto the sliding portion 44 so that the sliding portion 44 slides against the upper surface 25c of the case 25. The fastening member 46 can be, for example, a bolt with male threads cut to a length that does not completely tighten the sliding portion 44.

[0051] With this sliding mechanism 42, the planetary gear mechanism of the second-stage reducer 34b, which is the sliding part 44, can move along a virtual straight line 41 relative to the upper surface 25c of the case 25 while fitted into the guide recess 43. The position of the first rotation axis 31a, which is coaxial with the planetary gear mechanism, can move between the meshing position P1 and the free-spinning position P2. In Figure 6, the circles representing the first gear 31, the second gear 32, the sensor gear 55a, and the sensor gear 56a are, for example, outer circles connecting the tips of the teeth, and the circles of the gears that mesh with each other are shown to intersect.

[0052] The rotating shaft moving part 40 here includes, for example, a hydraulic cylinder 47 that brings the first gear 31 closer to the second gear 32, and an elastic member 48 that moves the first gear 31 away from the second gear 32.

[0053] The hydraulic cylinder 47 is positioned on the opposite side of the steering shaft 21 from the slide mechanism 42. The hydraulic cylinder 47 is attached to the slide portion 44, for example, so as to push the slide portion 44 on the side opposite to the steering shaft 21. Hydraulic pressure is supplied to the hydraulic cylinder 47 from the hydraulic circuit of the industrial vehicle 10. For example, when the driving change switch 52 is switched to the automatic steering state while the industrial vehicle 10 is stopped, the controller 50 controls the hydraulic valve of the hydraulic circuit to supply hydraulic pressure to the hydraulic cylinder 47 from the hydraulic circuit of the industrial vehicle 10. The hydraulic valve of the hydraulic circuit here constitutes the rotating shaft moving part. The hydraulic cylinder 47 pushes the slide portion 44, causing the slide portion 44 to slide toward the steering shaft 21. This causes the first gear 31 to advance toward the second gear 32. In other words, the rotating shaft moving part 40 moves the position of the first rotating shaft 31a to the meshing position P1, enabling power transmission between the first gear 31 and the second gear 32.

[0054] The elastic member 48 is positioned on the steering shaft 21 side relative to the slide mechanism 42. The elastic member 48 is, for example, a compression coil spring with one end attached to the slide portion 44 so as to press against the steering shaft 21 side of the slide portion 44, and the other end supported by a projection 25d on the case 25 side. When hydraulic pressure is no longer supplied to the hydraulic cylinder 47, the pressing force of the elastic member 48 releases the hydraulic fluid from the hydraulic cylinder 47 into the hydraulic circuit of the industrial vehicle 10. For example, when the industrial vehicle 10 is stopped and the operation changeover switch 52 is switched to manual steering mode, the controller 50 controls the hydraulic valve of the hydraulic circuit so as not to supply hydraulic pressure to the hydraulic cylinder 47. The elastic member 48 pushes the slide portion 44, causing the slide portion 44 to slide away from the steering shaft 21. The hydraulic cylinder 47 is pushed back from the slide portion 44. As a result, the first gear 31 retracts relative to the second gear 32. In other words, the rotating shaft movement unit 40 moves the position of the first rotating shaft 31a to the idle position P2, making power transmission between the first gear 31 and the second gear 32 impossible.

[0055] Figure 7 is a block diagram showing the functional configuration of the steering system of the industrial vehicle shown in Figure 1. As shown in Figure 7, the controller 50 is connected to the vehicle speed sensor 51, the driving changeover switch 52, and the rotary shaft movement unit 40. The controller 50 has a functional configuration that includes a driving state recognition unit 53 and a steering control unit 54.

[0056] The driving state recognition unit 53 acquires the vehicle speed of the industrial vehicle 10 based on the detection result of the vehicle speed sensor 51. The driving state recognition unit 53 recognizes that the industrial vehicle 10 is stopped if, for example, the vehicle speed of the industrial vehicle 10 is below a predetermined stopping speed. Based on the switch state of the driving changeover switch 52, the driving state recognition unit 53 recognizes whether the steering system 100 of the industrial vehicle is in an automatic steering state (unmanned driving mode) or a manual steering state (manned driving mode).

[0057] The steering control unit 54 controls the rotation shaft movement unit 40 to move the position of the first rotation shaft 31a between the meshing position P1 and the free-spinning position P2, based on the recognition result of the driving state recognition unit 53. For example, if the steering control unit 54 recognizes that the industrial vehicle 10 is stationary and the state of the steering device 100 of the industrial vehicle is recognized as being in an automatic steering state, it controls the rotation shaft movement unit 40 to supply hydraulic pressure from the hydraulic circuit of the industrial vehicle 10 to the hydraulic cylinder 47. For example, if the steering control unit 54 recognizes that the industrial vehicle 10 is stationary and the state of the steering device 100 of the industrial vehicle is recognized as being in a manual steering state, it controls the rotation shaft movement unit 40 so as not to supply hydraulic pressure from the hydraulic circuit of the industrial vehicle 10 to the hydraulic cylinder 47.

[0058] Figure 8 is a flowchart showing an example of the controller's processing in Figure 7. The processing shown in the flowchart in Figure 7 is repeatedly executed at predetermined calculation cycles, for example, when it is recognized that the industrial vehicle 10 is stationary.

[0059] In S01, the controller 50 of the steering system 100 of the industrial vehicle acquires the vehicle speed using the driving state recognition unit 53. In S02, the controller 50 acquires the switch state using the driving state recognition unit 53.

[0060] In S03, the controller 50, using the steering control unit 54, determines whether or not the vehicle is in an automatic steering state. If it is determined that the vehicle is in an automatic steering state (S03: YES), in S04, the controller 50 controls the rotation shaft movement unit 40, using the steering control unit 54, to move the position of the first rotation shaft 31a to the meshing position P1. On the other hand, if it is determined that the industrial vehicle 10 is in a manual steering state (S03: NO), in S05, the controller 50 controls the rotation shaft movement unit 40, using the steering control unit 54, to move the position of the first rotation shaft 31a to the free-spinning position P2. After that, the controller 50 completes the calculation process shown in Figure 8.

[0061] [Effects and Effects] As explained above, in the steering device 100 for industrial vehicles, the position of the first rotating shaft 31a is configured to move between a meshing position P1 and a free-spinning position P2 by the rotating shaft moving part 40. By moving the first rotating shaft 31a so that its position is the meshing position P1, for example, when the industrial vehicle 10 is in an automatic steering state, the operation of the steering motor 33 is transmitted to the steering shaft 21 via the first gear 31 and the second gear 32, thereby realizing automatic steering. On the other hand, by moving the first rotating shaft 31a so that its position is the free-spinning position P2, for example, when the industrial vehicle 10 is in a manual steering state, the steering force for manual steering is not input from the second gear 32 to the first gear 31. This makes it possible to suppress the increase in steering force due to the steering motor 33's rotation when the industrial vehicle 10 is in manual steering mode, with a simpler configuration and more reliable results compared to a configuration in which, for example, a clutch mechanism is interposed in the automatic steering unit.

[0062] In the steering system 100 of the industrial vehicle, the manual steering unit 20 includes a stopper member 28 that rotates together with the steering shaft 21, and a receiving member 29 that defines the range of rotation of the steering shaft 21 when the stopper member 28 abuts against it. The rotating shaft moving unit 40 moves the position of the first rotating shaft 31a to the free-spinning position P2 when the industrial vehicle 10 is in a manual steering state. In this configuration, even if the structure is such that an impact load is generated in the manual steering unit 20 when the stopper member 28 abuts against the receiving member 29, moving the first rotating shaft 31a so that its position is the free-spinning position P2 prevents the impact load generated by manual steering from being input from the second gear 32 to the first gear 31. As a result, it becomes unnecessary to reinforce the first gear 31 and the second gear 32 in preparation for impact loads.

[0063] [Differentiation] The present invention is not limited to the embodiments described above. The present invention can be implemented in various forms, including the embodiments described above, with various modifications and improvements based on the knowledge of those skilled in the art.

[0064] For example, in the above embodiment, the rotating shaft moving part 40 had a hydraulic cylinder 47 that moves the first gear 31 closer to the second gear 32 and an elastic member 48 that moves the first gear 31 away from the second gear 32. However, an electric cylinder may be used instead of the hydraulic cylinder 47 and the elastic member 48. In this case, the electric cylinder can replace both the function of moving the first gear 31 relative to the second gear 32 by the hydraulic cylinder 47 and the function of moving the first gear 31 relative to the second gear 32 by the elastic member 48.

[0065] In the above embodiment, the rotating shaft moving unit 40 was configured to move only the first rotating shaft 31a, but it may also be configured to move only the second rotating shaft 32a, or it may be configured to move both the first rotating shaft 31a and the second rotating shaft 32a.

[0066] In the above embodiment, the first rotating shaft 31a of the first gear 31 was coaxial with the second-stage reducer 34b of the reduction unit 34, but the invention is not limited to this. The first gear 31 may be provided on a rotating shaft other than the output shaft of the reduction unit 34. In this case, the other rotating shaft corresponds to the first rotating shaft. In the above embodiment, the second gear 32 was fixed to the steering shaft 21, but the invention is not limited to this. The second gear 32 may be located on the steering shaft 21 side of the first gear 31, and the second gear 32 may be provided on a rotating shaft other than the steering shaft 21. In this case, the other rotating shaft corresponds to the second rotating shaft. In short, the automatic steering unit 30 only needs to be able to rotate the steering shaft 21 by having the steering motor 33 rotate, which in turn drives the second gear 32 provided on the steering shaft 21 side, through the rotation of the steering motor 33.

[0067] In the above embodiment, the first rotation axis 31a and the second rotation axis 32a were parallel to each other, but are not limited thereto. The first rotation axis 31a and the second rotation axis 32a may intersect each other, as long as at least one of them can move between the meshing position P1 and the free-spinning position P2 by the rotation axis moving part 40.

[0068] In the above embodiment, the slide mechanism 42 is exemplified as a guide recess 43 and a slide portion 44, but the guide recess 43 may be omitted.

[0069] In the above embodiment, a first-stage reduction gear 34a and a second-stage reduction gear 34b were exemplified in the automatic steering unit 30, but they may be a single reduction gear, or three or more reduction gears may be used.

[0070] In the above embodiment, the rotating shaft moving unit 40 was controlled by the controller 50 based on the detection result of the vehicle speed sensor 51 and the switch state of the operation changeover switch 52, but is not limited to this. The rotating shaft moving unit 40 may have a manual operation mechanism that operates the slide mechanism 42 so that the position of the first rotating shaft 31a can be moved between the meshing position P1 and the free-spinning position P2 by manual operation by an operator. As the manual operation mechanism, for example, a known structure that transmits manual operating force can be adopted, such as an operating lever and a link mechanism.

[0071] In the above embodiment, a battery-powered electric towing vehicle was exemplified as the industrial vehicle 10, but it is not limited to this. The industrial vehicle 10 may be engine-powered, or it may be other industrial vehicles such as transport vehicles other than towing vehicles.

[0072] In the above embodiment, the steering force was transmitted to the manual steering unit 20 by a chain and sprocket, but the steering force may also be transmitted by gears or the like.

[0073] In the above embodiment, a steering wheel 15 was exemplified as the steering control unit, but it is not limited to this. The steering control unit may also be of the steering lever type.

[0074] In the above embodiment, a driver's seat 2 for the worker to sit in was provided in the industrial vehicle 10, but in an industrial vehicle where the worker rides standing, the driver's seat 2 may be omitted. [Explanation of Symbols]

[0075] 5... Steering wheel, 10... Industrial vehicle, 15... Steering wheel (steering operation part), 20... Manual steering part, 21... Steering shaft, 28... Abutment member, 29... Receiving member, 30... Automatic steering part, 31... First gear, 31a... First rotating shaft (rotating shaft), 32... Second gear, 32a... Second rotating shaft (rotating shaft), 33... Steering motor (motor), 40... Rotating shaft moving part, 42... Sliding mechanism, 47... Hydraulic cylinder, 48... Elastic member, 100... Steering device for industrial vehicles, P1... Engaged position, P2... Free-spinning position.

Claims

1. A steering system for an industrial vehicle configured to allow switching between automatic steering and manual steering, A steering shaft that rotates in accordance with the steering direction of the steering wheels of the aforementioned industrial vehicle, A manual steering unit that rotates the steering shaft in response to manual operation of the steering control unit, An automatic steering unit that rotates the steering shaft by having a first gear, which rotates in accordance with the operation of the motor, drive a second gear provided on the steering shaft side, The device comprises a rotating shaft moving part configured to move the position of at least one of the rotating shafts of the first gear and the second gear between a meshing position in which the first gear and the second gear are meshed with each other and a free-rotating position in which the first gear and the second gear are separated, The rotating shaft moving part has a sliding mechanism that allows the first gear to move back and forth relative to the second gear, and slides the rotating shaft. The aforementioned slide mechanism is The rotating shaft includes a guide recess for moving the position of the first rotating shaft of the first gear, It includes a sliding part that is slidably mounted on the upper surface of the case while fitted into the guide recess and supports the first rotation axis, The guide recess includes a pair of guide walls parallel to a virtual straight line connecting the first rotation axis of the first gear and the second rotation axis of the second gear. A steering device for an industrial vehicle, wherein the extended length of a pair of guide walls corresponds to a predetermined straight-line distance from the engagement position to the free-spinning position.

2. The slide mechanism is formed on the upper surface of the case that covers the second gear and the steering shaft and supports the automatic steering unit, The steering device for an industrial vehicle according to claim 1, wherein the sliding portion supports the first rotating shaft such that the first gear is located on the lower side of the case.

3. The steering device for an industrial vehicle according to claim 1 or 2, wherein the rotating shaft moving part comprises a hydraulic cylinder that moves the first gear closer to the second gear by being supplied with hydraulic pressure from the hydraulic circuit of the industrial vehicle, and an elastic member that moves the first gear away from the second gear by being deprived of the supply of hydraulic pressure to the hydraulic cylinder.

4. A steering device for an industrial vehicle configured to be switchable between an automatic steering state and a manual steering state, A steering shaft that rotates in accordance with the steering direction of the steering wheels of the aforementioned industrial vehicle, A manual steering unit that rotates the steering shaft in response to manual operation of the steering control unit, An automatic steering unit that rotates the steering shaft by having a first gear, which rotates in accordance with the operation of the motor, drive a second gear provided on the steering shaft side, The device comprises a rotating shaft moving part configured to move the position of at least one of the rotating shafts of the first gear and the second gear between a meshing position in which the first gear and the second gear are meshed with each other and a free-rotating position in which the first gear and the second gear are separated, The manual steering unit includes a stopper member that rotates together with the steering shaft, and a receiving member that defines the range of rotation of the steering shaft when the stopper member abuts against it. The steering device for an industrial vehicle, wherein the rotating shaft moving part moves the position of the rotating shaft to the free-spinning position when the industrial vehicle is in the manual steering state, thereby preventing the impact load transmitted to the steering shaft when the abutment member strikes the receiving member from being input from the second gear to the first gear.

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