JP6174465B2 - Steering device, industrial vehicle and program - Google Patents

Description

  The present invention relates to a steering device and the like mounted on an industrial vehicle.

  Industrial vehicles such as forklifts are equipped with a steering device that steers the steering wheel based on the driver's steering operation. In this steering device, the steering wheel is steered in the left-right direction according to the steering operation. It is configured.

  By the way, in a steering apparatus, it is common that the angle range which can operate a steering is larger than the angle range which can steer a steered wheel. Specifically, the angle range in which the steerable wheels can be steered is less than one rotation, while the angle range in which the steering can be operated is 1 to 7 or more. For this reason, even if the driver turns the steering a plurality of times in the same direction, the steered wheels may continue to be steered in the same direction and the vehicle body may continue to turn in the same direction. That is, even in an industrial vehicle having a handle that also serves as an indication of the traveling direction of the vehicle on the steering, the position of the handle and the traveling direction of the vehicle do not correspond one-to-one.

  For this reason, when a driver gets on an industrial vehicle parked and parked for the first time, the steering handle cannot always be used as a guideline, and the vehicle moves in an unexpected direction of the driver. There is. On the other hand, in Patent Document 1, for example, a sensor that detects the presence of the driver based on a change in the load on the driver's seat is provided, and the driver is not in the vehicle when parked or stopped. In addition, a configuration is disclosed in which operation control of the steering mechanism (hereinafter referred to as “steering wheel return control”) is performed so that the steering angle of the steering wheel is returned to a predetermined reference angle (for example, 0 °; straight traveling direction of the vehicle).

JP 2013-6585 A

  However, in the steering wheel return control, there is a concern about the burden on the tire of the steered wheels caused by steering the steered wheels when the industrial vehicle is stopped. That is, in the state where the ground contact surface of the tire is not changed, the ground contact portion receives friction from the road surface, so that the tire is unevenly worn and the life of the tire is shortened. On the other hand, in the configuration described in Patent Document 1, an effective method has not been shown.

  The present invention has been made in view of such circumstances, and an object of the present invention is to reduce uneven wear of tires in an industrial vehicle that performs steering wheel return control as compared with the related art.

  (1) The present invention made to achieve the above object is a steering device mounted on an industrial vehicle, and includes a steering mechanism and steering wheel return control means. The steering mechanism is a mechanism for steering the steered wheels to determine the traveling direction of the industrial vehicle, and the steered wheel return control means is configured to control the steering angle of the steered wheels when the predetermined permission condition is satisfied when the industrial vehicle is stopped. The operation control of the steering mechanism is performed so that becomes a predetermined reference angle.

  According to such a configuration, for example, at the time of parking and stopping, for a driver who recognizes that the steering wheel return control is performed before getting off the industrial vehicle and getting on next, Since the vehicle is not started in an unintended direction when boarding and starting for the first time, the usability is improved.

  However, in the steering wheel return control, there is a concern about the burden on the tire as described above. On the other hand, the steering device of the present invention further includes road surface determination means. This road surface determination means determines whether or not the road surface when the industrial vehicle is stopped is in a state with small unevenness (hereinafter referred to as “low wear state”). Then, the steering wheel return control means performs the operation control with the road surface determination means that the road surface determination means determines that it is in a low wear state as one of the above-described permission conditions.

  According to such a configuration, for example, when the vehicle is parked or stopped on a road surface with large unevenness, the steering wheel return control is not performed. That is, since the steering wheel return control is performed according to the road surface condition, the tire is not rubbed on the road surface with large unevenness in the steering wheel return control. Therefore, according to the present invention, in an industrial vehicle that performs steering wheel return control, uneven wear of tires can be reduced more than in the past.

  (2) The steering device of the present invention may further include a notification unit. The notification means notifies the driver that the operation control is not performed when the road surface determination means determines that the wear state is not low. The notification timing may be, for example, any timing from when the driver parks and stops the industrial vehicle to when the driver leaves the vehicle, or the driver gets on the parked industrial vehicle. Any timing from when the vehicle starts to start. In consideration of the possibility of the driver changing during parking and stopping, it is preferable to notify at the latter timing or both timings.

  According to such a configuration, for example, when the steering wheel return control is not performed during parking and stopping, the driver can be made aware of this. In other words, the driver can grasp in advance that the vehicle may start in a direction different from the direction predicted in anticipation of the execution of the steering wheel return control. It is possible to allow the driver to make appropriate preparations and confirmations so as not to start.

  (3) In the present invention, the road surface state when the industrial vehicle is stopped can be recognized using an image sensor such as a camera, a radar sensor (for example, a roughness sensor) using infrared rays, or the like. However, in the configuration using these sensors, the process for recognizing the road surface condition is likely to be complicated, and there is a concern that the cost is increased.

  On the other hand, the steering device of the present invention may further include vibration detection means. The vibration detecting means detects a state value based on the vibration of the industrial vehicle. Then, the road surface determination means determines the low wear state based on the detection value of the vibration detection means. According to such a configuration, it is not necessary to perform image analysis, infrared scanning, or the like, and the road surface state can be recognized by a relatively simple process, which can contribute to cost reduction.

  (4) By the way, with a structure provided with a vibration detection means, it is difficult to detect a vibration state when the industrial vehicle is stopped. For this reason, the steering apparatus of the present invention may further include vibration storage means. The vibration storage means stores the detection value of the vibration detection means in a predetermined storage means. The road surface determination means determines the low wear state based on the detection value stored by the vibration storage means during traveling of the industrial vehicle.

  According to such a configuration, the road surface state can be recognized by suitably detecting the vibration state. That is, since the road surface state immediately before the industrial vehicle stops can be recognized based on the detection value stored in the storage unit, the road surface state when the vehicle is stopped can be accurately estimated.

  (5) In more detail, the steering device of the present invention may further include a speed detection means. This speed detection means detects the traveling speed of the industrial vehicle. The road surface determining means is a period in which the speed detected by the speed detecting means is equal to or higher than a predetermined threshold speed, and based on the detection value stored by the vibration storage means within a certain period closest to the stop of the industrial vehicle, Judge the low wear state.

  According to such a configuration, the vibration state of the vehicle can be detected more suitably by using the detection value when the vehicle is traveling at a certain speed in the period immediately before the industrial vehicle stops, and thus The estimation accuracy relating to the road surface condition when the vehicle is stopped can be improved.

  (6) In the steering device of the present invention, the road surface determination unit may determine that the road surface is not in a low wear state when the detection value of the vibration detection unit exceeds a predetermined vibration threshold value a plurality of times.

  According to such a configuration, it is possible to suppress the influence of noise accompanying the detection of the vibration state, and to exclude a small part of unevenness on the local road surface from the above determination. As a result, the vibration state of the industrial vehicle can be detected more suitably, and as a result, the estimation accuracy regarding the road surface state when the vehicle is stopped can be further improved.

  (7) Although the configuration for adding road surface conditions as one of the permission conditions has been described as to whether or not the steering wheel return control can be performed, the present invention may be configured to add vehicle body conditions as follows.

  Specifically, in the steering device according to the present invention, the industrial vehicle includes a drive mechanism that separates the steered wheels from the road surface, and the steered wheel return control means is operated by the drive mechanism when the industrial vehicle is stopped. The control of the operation is performed by separating the vehicle from the road surface as a vehicle body condition that is one of the above-described permission conditions.

  According to such a configuration, since the steered wheel is separated from the road surface before the steered wheel return control is performed, the tire can be prevented from rubbing against the road surface in the steered wheel return control. Therefore, according to the present invention, it is possible to suppress the burden on the tire of the steered wheel due to the steered wheel return control, so that uneven wear of the tire can be reduced as compared with the conventional case.

  (8) Specifically, the steering apparatus of the present invention may further include a separation determination unit. This separation determination means determines whether or not the steered wheel is separated from the road surface (hereinafter referred to as “road surface separation state”). Then, the steered wheel return control means performs the operation control based on the above vehicle body condition that the separation determination means determines that the road surface is separated.

  According to such a configuration, since it is confirmed that the steered wheel is separated from the road surface, the steered wheel return control is performed, so that the tire does not rub against the road surface in the steered wheel return control, and as a result, the steered wheel returns. In an industrial vehicle that performs control, uneven wear of tires can be more reliably reduced than in the past.

  (9) Further, in the steering device according to the present invention, the separation determining means flows to the electric motor in a configuration in which the steering mechanism includes an electric motor that drives the steered wheels to assist the steering by the driver. The road surface separation state may be determined based on the current value.

  According to such a configuration, it is possible to suitably determine the road surface separation state by utilizing the fact that the current value decreases when the motor load changes from a large state to a small state. That is, for example, before the steering wheel return control is performed, when the steering wheel is steered by the electric motor, when the road surface is separated, the rotation of the motor is less than that when the steering wheel is in contact with the road surface. Since the current value flowing to the motor decreases temporarily, the road surface separation state can be suitably determined by detecting this.

  (10) The drive mechanism may be a mechanism configured to lift a portion on the steering wheel side of the vehicle body of the industrial vehicle. This mechanism may be a hydraulic type or an electric type. That is, by automatically jacking up a part of the vehicle body, the steered wheels can be reliably separated from the road surface.

  (11) Further, the drive mechanism uses a lock cylinder for restricting the vertical swing of the steered wheel, and is configured to lift the steered wheel by a piston that moves up and down by a pressure change inside the lock cylinder. It may be a mechanism.

  According to such a configuration, the suspension lock device that restricts the function of the provided suspension mechanism in order to prevent the rear wheel as the steering wheel from floating, for example, when loading a forklift or traveling downhill. The steering wheel can be suitably separated from the road surface using this mechanism. In other words, in the mechanism of the suspension lock device, an operation (piston raising operation) different from the normally used functional operation (piston lock operation) can be applied to the operation of the steering wheel lifting function (for example, cylinder And adjusting the size and movable area of the piston), it is not necessary to add a new drive mechanism, which can contribute to cost reduction.

  (12) Moreover, in order to solve the problem of the present invention, an industrial vehicle including the steering device described above may be used as the present invention. Industrial vehicles are vehicles for cargo handling and transportation that are used at sites such as forklifts, factory premises, warehouses, distribution centers, stations, airports, and the like.

  (13) Further, the present invention can be distributed to the market as a program. Specifically, it is a program for causing a computer to function as the steering wheel return control means and the road surface determination means described in (1) to (6) above.

(14) Further, specifically, there is a program for functioning as the steering wheel return control means described in (7) to (11) above.
By incorporating these programs into one or a plurality of computers (specifically, computers installed in the steering device), it is possible to obtain the same effects as those achieved by the steering device of the present invention. The program of the present invention may be stored in a ROM, flash memory, or the like incorporated in a computer and loaded from the ROM, flash memory, or the like into the computer, or loaded into the computer via a network. May be.

  Further, the above program may be used by being recorded on a recording medium in any form readable by a computer. The recording medium includes a portable semiconductor memory (for example, a USB memory).

It is a perspective view which illustrates the whole structure of the forklift as an industrial vehicle of a 1st embodiment. (A) is sectional drawing which illustrates the whole structure of a steering device, (b) is a block diagram which illustrates the structure of the controller of a steering device. 4 is a flowchart illustrating contents of a return control process executed by a controller in the first embodiment. It is a flowchart which illustrates the content of the road surface determination process performed in S140 of a return control process. (A) is continuous data of the detection value of the vibration sensor when it is determined that the wear state is low, and (b) is continuous data of the detection value of the vibration sensor when it is determined that the wear state is not low. . It is a side view which illustrates the whole structure of the forklift of 2nd Embodiment. It is a flowchart which illustrates the content of the return control process of 2nd Embodiment. (A) is a rear view illustrating the overall configuration of the forklift according to the third embodiment, (b) is a rear view illustrating a mode when the steering wheel is lifted by the drive mechanism, and (c) is a hydraulic pressure. It is explanatory drawing which illustrates the structure of a formula drive mechanism.

Below, the forklift which is an industrial vehicle as an embodiment of the present invention is explained with a drawing.
The present invention is not construed as being limited in any way by the following embodiments. Moreover, the aspect which abbreviate | omitted a part of following embodiment as long as the subject could be solved is also embodiment of this invention. Moreover, all the aspects which can be considered in the limit which does not deviate from the essence of the invention specified only by the wording described in the claims are embodiments of the present invention.

<First Embodiment>
As shown in FIG. 1, the forklift 1 according to the present embodiment is a so-called reach-type forklift, in which a cargo handling mechanism 3 is provided at a front portion of a vehicle body 2, and a driver's seat 4 and a steering device 5 are provided at a rear portion of the vehicle body 2. Is provided.

  The loading mechanism 3 moves the fork 31 inserted into the insertion hole of the pallet on which the load is placed, the mast 33 that supports the fork 31 so as to be movable up and down, and the fork 31 along the mast 33 in the vertical direction. And a lift cylinder (not shown), a reach cylinder (not shown) for moving the fork 31 and the mast 33 in the front-rear direction, and the like.

  The vehicle body 2 controls the hydraulic pump 21 (see FIG. 8C) that supplies the pressurized oil to the cylinders provided in the mechanisms such as the lift cylinder and the reach cylinder, and the supply destination of the pressurized oil. The hydraulic mechanism 8 (refer FIG.8 (c)) comprised by the switching valve (not shown), the hydraulic tank 23 which stores oil, etc. is accommodated. The driver's seat 4 is a place where the driver gets on the forklift 1 and operates the forklift 1 in a standing posture.

  The steering device 5 is mounted at a position adjacent to the driver's seat 4 on the rear side of the vehicle body 2, and as shown in FIG. 2 (a), the steering 51 that receives the driver's operation and the traveling direction of the forklift 1 The steering wheel 53 to be steered to determine the steering wheel 54, the steering mechanism 54 for steering the steering wheel 53 in accordance with the operation amount of the steering wheel 51, the driving motor 59 for driving to rotate the steering wheel 53, and the operation torque of the steering wheel 51 are detected. Torque sensor 71, rudder angle sensor 73 for detecting the rudder angle of the steered wheels 53, controller 75 for controlling the operation of the entire steering device 5, driver detection sensor 77 for detecting the presence of the driver of the forklift 1, traveling of the forklift 1 A vehicle speed sensor 79 for detecting the speed (vehicle speed) and a key switch switching state for starting the forklift 1 as a whole are detected. A key sensor 81 that performs notification to the vicinity of the forklift 1, a vibration sensor 85 that detects a state value based on vibration of the vehicle body 2, a known inclination sensor 87 that detects a state value based on the tilt of the vehicle body 2 in the front-rear direction, Etc.

  The driver detection sensor 77 is a sensor that is not mounted as an operation input end of a normal forklift 1 such as a load sensor that detects the presence of the driver based on a change in the load (weight) of the driver's seat 4, an infrared sensor, or an image sensor. There is a sensor that detects that the driver is present in the driver's seat 4.

  The vibration sensor 85 is an acceleration sensor that detects vertical acceleration applied to the steering wheel 53. For example, the vibration sensor 85 is typically used for controlling a suspension mechanism that drives the steering wheel 53 so as not to transmit road surface unevenness to the vehicle body 2. However, in this embodiment, it is used for detecting the uneven state (road surface state) of the road surface. Note that the suspension mechanism described above is not mounted on the forklift 1 of the present embodiment. Further, in order to detect the road surface state, an image sensor, a radar sensor (for example, a roughness sensor) or the like may be used. In this way, a vibration sensor 85 that can be mounted as an operation input end of a normal forklift 1 is used. This is thought to contribute to cost reduction.

The steering 51 is configured to be able to steer the steering wheel 53 by a driver's operation, and a handle 52 that can be used when the driver performs a steering operation is attached.
The steered wheels 53 are also drive wheels that apply a driving force for traveling the forklift 1 to the road surface. In the present embodiment, the steerable wheel 53 has a steerable angle range of less than one rotation (less than 360 °), whereas the steerable wheel 51 has an operable angle range of more than one rotation (360 ° or more; this embodiment). In the form, it is 360 ° × 7 (7 rotations). In the present embodiment, the steering angle of the steered wheels 53 in a state where the forklift 1 can go straight is set to 0 °, for example.

  The steering mechanism 54 includes a steering wheel support portion 55 that supports the steering wheel 53, a steering transmission mechanism 61 that transmits the steering torque of the steering wheel 51 to the steering wheel 53, and the steering wheel 53 is steered by the steering 51. An assist motor 63 for assisting, an operation circuit 65 for operating the assist motor 63, and the like are provided.

  Among these, the steering wheel support portion 55 is fixed to the main body so as to be rotatable along the direction in which the steering wheel 53 is steered, and a steering gear 57 surrounding the steering wheel support portion 55 is formed in the rotation direction. Has been.

  The assist motor 63 is a well-known electric power steering (EPS) motor. The assist motor 63 rotates a gear (not shown) meshed with the steering gear 57 of the steering wheel support portion 55 with a steering torque corresponding to the torque of the steering 51 transmitted by the steering transmission mechanism 61. Thus, the steering wheel support portion 55 and the steering wheel 53 supported by the steering wheel support portion 55 are steered via the steering gear 57.

  The steering transmission mechanism 61 is a rod-shaped member extending from the steering 51 toward the steering wheel support portion 55, and meshes with the steering gear 57 of the steering wheel support portion 55 at the end portion (lower end) on the steering wheel 53 side. The transmission gear 67 is provided, and the operation torque of the steering 51 is transmitted to the steering wheel support portion 55 and the steering wheel 53 supported by the steering wheel 57 via the transmission gear 67 and the steering gear 57.

  The notification unit 83 alerts the periphery of the forklift 1 (for example, a driver) or notifies the operation state of the forklift 1 to the surroundings, and outputs a buzzer that generates a notification sound and a predetermined voice message. And a drive circuit for driving a buzzer. The voice output device is configured to output a plurality of types of voice messages in accordance with a command from the controller 75, and the drive circuit is configured to generate a plurality of types of notification sounds to the buzzer in accordance with a command from the controller 75. Has been.

  The controller 75 is communicably connected to the operation unit 6 disposed in front of the driver's seat 4 and is configured to detect the driver's operation content on the operation unit 6. As shown in FIG. 2B, the controller 75 includes a microcomputer (hereinafter referred to as “microcomputer”) 75a having a CPU, ROM, RAM, and the like, and a memory 75b as a storage device. The CPU of the microcomputer 75a is configured to execute various processes according to programs stored in the ROM or the memory 75b.

  Specifically, the controller 75 (specifically, the CPU of the microcomputer 75a; the same applies hereinafter) is based on the detection value of the torque sensor 71 and has a size corresponding to the steering operation of the driver (operation torque of the steering wheel 51). A well-known steering process for controlling the operation of the steering mechanism 54 is performed so that the steering mechanism 53 is steered.

  Further, while the controller 75 determines that the forklift 1 is traveling (vehicle speed> 0) based on the detection value of the vehicle speed sensor 79, the controller 75 sets the detection value every time the detection value of the vibration sensor 85 is input. The vibration storage process stored in the memory 75b is performed. In this vibration storage process, the detected values that have been stored in time series are deleted from the oldest in order so as not to exceed the amount of data corresponding to the allocation area of the memory 75b, and the newly input detection values are stored instead. (That is, it is overwritten and updated). Further, in the vibration storage process of the present embodiment, the traveling speed of the forklift 1 when the detection value of the vibration sensor 85 is input is associated with the detection value of the vibration sensor 85 based on the detection result by the vehicle speed sensor 79. It is memorized in chronological order.

In addition to the area for storing these travel speeds and detection values in time series, an area for storing history information to be described later is allocated to the memory 75b.
Further, the controller 75 steers the steering wheel 53 so that the steering angle of the steered wheels 53 returns to a predetermined reference angle when the forklift 1 is stopped and a predetermined permission condition is satisfied, for example, when there is no driver on the forklift 1. A return control process (described later) for controlling the operation of the mechanism 54, a power-off process for performing a power-off operation after the key switch is switched from the on state to the off state, and the like are executed.

  Note that the power-off process is performed based on the detection result of the key sensor 81 in order to maintain the power-on state until the return control process is completed after the key switch is switched from the on state to the off state. This is a process of turning off the power of the forklift 1 after the process is completed. This power-off process is set to “return mode” that permits operation control of the steering mechanism 54 by the return control process (hereinafter referred to as “steering wheel return control”), for example, by an operation mode changeover switch provided in the operation unit 6. This is implemented when the vehicle is in the “non-return mode” in which the steering wheel return control is not permitted. That is, when the “non-return mode” is set, when the key switch is switched from the on state to the off state, the power of the forklift 1 is turned off accordingly.

<Return control processing (1)>
Next, the return control process executed by the controller 75 will be described with reference to FIG. This process is started when the forklift 1 is powered on in the return mode. That is, it starts when the key switch is switched from the off state to the on state based on the detection result by the key sensor 81 in the return mode.

  When this process is started, the controller 75 performs steering wheel return control in the previous main process (S160) based on the history information stored in the memory 75b in the previous main process (S170) in S105. It is determined whether or not it has been implemented, and the driver is notified according to the determination result. That is, when the steering wheel return control is performed in the previous main processing (S160), the notification unit 83 is notified to notify the driver that the steering wheel 53 is set to the reference angle by the execution. If the steering wheel return control is not performed in the previous main processing (S160), the driver indicates that the steering wheel 53 is not set to the reference angle due to the failure. To notify the notification unit 83 of the voice message.

  Next, the controller 75 determines whether or not the forklift 1 is parked or stopped in S110. Specifically, based on the detection result by the vehicle speed sensor 79, the forklift 1 is stopped (the vehicle speed is zero), and the key switch is changed from the on state to the off state based on the detection result by the key sensor 81. When it is determined that this condition is satisfied as the first parking / stopping condition (S110; YES), the process proceeds to S120 and it is determined that this condition is not satisfied (S110; NO). Wait as it is.

  In S120, the controller 75 determines whether or not the forklift 1 is parked on a slope. Specifically, based on the detection value of the inclination sensor 87, when it is determined that the forklift 1 is parked on a flat road surface that is not on a slope, the second parking condition is satisfied (S120). NO), the process proceeds to S130, and if it is determined that this condition is not satisfied (S120; YES), the process is terminated via S170.

  Next, the controller 75 determines whether or not a driver is present on the forklift 1 in S130. Specifically, based on the detection result of the driver detection sensor 77, when it is determined that the driver seat is not on the driver's seat 4 and this condition is satisfied (S130; NO), S140 If it is determined that this condition is not satisfied (S130; YES), the process returns to S110.

  In addition, about the aspect of a 1st parking stop condition, a 2nd parking stop condition, and an unmanned condition, it does not necessarily need to be the content demonstrated above, and various aspects of patent document 1 can be employ | adopted. For example, even if the key switch is on in S110 to S130, if other conditions are satisfied, the process may proceed to the next S140. That is, the steering wheel return control may be implemented not only when the forklift 1 is parked but also when the forklift 1 is parked.

  Subsequently, in S140, the controller 75 performs a road surface determination process for determining whether or not the road surface when the forklift 1 is stopped is in a state with small unevenness (hereinafter referred to as “low wear state”). In addition, it cannot be overemphasized that a state without an unevenness | corrugation is contained in a low abrasion state. Specifically, in this road surface determination process, as shown in FIG. 4, from the data stored in the memory 75b by the vibration storage process, first, a state where the traveling speed of the forklift 1 is equal to or higher than a predetermined threshold speed is determined for a certain period of time. The continuous data of the detection value of the vibration sensor 85 in the fixed period closest to the time when the forklift 1 is stopped is extracted during the continuous period (S210). Then, based on the continuous data of the detection values extracted in S210, it is determined whether or not the detection value of the vibration sensor 85 exceeds a predetermined vibration threshold value (see FIG. 5A) a plurality of times (S220). Subsequently, in S220, when it is determined that the detection value of the vibration sensor 85 exceeds the vibration threshold by a predetermined threshold number of times (multiple times) (S220; YES, see FIG. 5B), when the forklift 1 is stopped. It is determined that the road surface is not in a low wear state (S230), and the process proceeds to S150. On the other hand, in S220, when it is determined that the detection value of the vibration sensor 85 does not exceed the vibration threshold value more than the threshold number (multiple times) (S220; NO), it is determined that the road surface when the forklift 1 is stopped is in a low wear state. (S240), and the process proceeds to S150.

  Next, when the controller 75 determines in S150 that the road surface condition when the forklift 1 is stopped is a low-wear state based on the result of the road surface determination process in S140, and satisfies this condition ( (S150; YES), the process proceeds to S160, and if it is determined that this condition is not satisfied (S150; NO), this process is terminated via S170.

  In S160, the controller 75 performs steering wheel return control. That is, operation control of the steering mechanism 54 (specifically, the assist motor 63) is started so that the steering angle of the steering wheel 53 detected by the steering angle sensor 73 returns to a predetermined reference angle. Here, in the steering wheel return control, the steering wheel 53, by extension, the steering gear 57, the transmission gear 67, the steering transmission mechanism 61, and the steering 51 are steered by causing the operation circuit 65 to operate the assist motor 63 to thereby control the steering angle sensor. The rudder angle detected by 73 is returned to the reference angle. More specifically, the controller 75 operates when the assist motor 63 is driven so that the steering speed of the steering wheel 53 detected based on the detection result of the steering angle sensor 73 is constant (for example, 18 ° / s). By changing the duty ratio, the steering angle of the steered wheels 53 is returned to the reference angle. The reference angle is not necessarily limited to 0 ° indicating the straight traveling direction of the forklift 1, and may be an angle within an allowable range of, for example, ± 20 ° (= 40 °) centered on this 0 °. Good. Further, the reference angle may be variably set based on the continuous data of the detection values extracted in S210 from the angle within the allowable range. For example, according to the magnitude of the detection value of the vibration sensor 85 and the number of times that the vibration threshold is exceeded, when these values and number are small (small), the reference angle is set to 0 °, and these values and number are large. In the case of (large), it may be set to an angle (+ 20 ° or −20 °) at which the steering amount of the driven steering wheel 53 is minimized among the angles within the allowable range.

  In the subsequent S165, the controller 75 notifies the notifying unit 83 of the buzzer so as to notify the periphery of the forklift 1 that the steering wheel return control is being performed with the start of the steering wheel return control in S160. Outputs a command. Thereby, the notification unit 83 continuously generates a notification sound such as “Peepy” (short sound) from the start to the end of the steering wheel return control.

  In continuing S170, the controller 75 memorize | stores the historical information regarding implementation of this process in the memory 75b, and complete | finishes this process. That is, when the execution date and time of this process, the road surface state based on the continuous data of the detection values extracted in S210, whether or not the steering wheel return control (S160) is executed, and when the steering wheel return control is executed, the driven steering wheel is driven. If the steering amount of 53 and the steering wheel return control are not performed, information for specifying which permission condition is not satisfied among the first and second parking / stopping conditions, unmanned conditions and road surface conditions, etc. Is stored in the memory 75b as history information.

  In the road surface determination process of S140, when it is determined that the detection value of the vibration sensor 85 exceeds the vibration threshold value a plurality of times (S220; YES), it is determined that the road surface when the forklift 1 is stopped is not in a low wear state. However, the present invention is not limited to this (S230). If the detection value of the vibration sensor 85 exceeds even once, it may be determined that the road surface is not in a low wear state.

  However, if the detected value of the vibration sensor 85 exceeds the vibration threshold value even once, when it is determined that the wear state is not low, the detection error of the vibration sensor 85 or unevenness on a very small part of the local road surface. There is a concern that it may be determined that the road surface when the forklift 1 is stopped is not in a low wear state. On the other hand, by setting that the detection value of the vibration sensor 85 exceeds the vibration threshold value a plurality of times as in the present embodiment as a determination condition that the road surface is not in a low wear state, the influence of noise such as detection errors can be obtained. In addition, since only a small unevenness on the local road surface is excluded from the determination conditions, it is possible to improve the estimation accuracy regarding the road surface state when the forklift 1 is stopped.

  In addition, in order to perform the road surface determination process of S140, in the vibration storage process, the detection value of the vibration sensor 85 is always stored in the memory 75b while the forklift 1 is traveling. However, the present invention is not limited to this. Instead, based on the detection value of the vehicle speed sensor 79, the detection value may be stored in the memory 75b when the vehicle speed is equal to or higher than the threshold speed. Further, in the vibration storage process, when the state where the vehicle speed is equal to or higher than the threshold speed is not continued for a certain period of time, the continuous data of the detection values stored in the memory 75b may be deleted from the memory 75b. Furthermore, the updated data may be overwritten so that only the latest data of the detected value remains in the memory 75b. Further, in the vibration storage process, when it is determined that the forklift 1 is moving in the stopping direction, such as the vehicle speed is decelerated based on the detection result by the vehicle speed sensor 79 or the detection result by the brake switch (not shown), the vibration is stored. Storage of the detection value of the sensor 85 in the memory 75b may be started. By doing so, the storage area in the memory 75b can be saved and the life of the memory 75b can be extended.

<Main effect (1)>
As described above, in the steering device 5 mounted on the forklift 1, in the return control process executed by the controller 75, the steering angle of the steered wheels 53 is satisfied when a predetermined permission condition is satisfied when the forklift 1 is stopped. Operation control (steering wheel return control) of the steering mechanism 54 is performed so that a predetermined reference angle is obtained. For this reason, for example, when the vehicle is parked or stopped, a driver who recognizes that the steering wheel return control is performed between the time when the vehicle gets off the forklift 1 and the next time that the user gets on the vehicle, When the vehicle is first started, the forklift 1 is not started in an unintended direction, so that the usability is improved.

  Here, in the return control process, it is determined whether or not the road surface when the forklift 1 is stopped is in a state with small unevenness (low wear state), and it is determined that the road surface is in a low wear state. Steering wheel return control is performed as one of the road surface conditions. For this reason, for example, when the vehicle is parked or stopped on a road surface with large unevenness, the steering wheel return control is not performed. In other words, since the steering wheel return control is performed according to the road surface state at the time of parking and stopping, the tire is not rubbed on the road surface with large unevenness in the steering wheel return control. Therefore, in the forklift 1 that performs steering wheel return control, uneven wear of the tire can be reduced as compared with the conventional case.

  Further, in the return control process, when it is determined that the road surface state at the time of parking / stopping is not a low wear state, it is stored in the memory 75b that the steering wheel return control has not been performed based on the determination result, In the next return control process, the driver is notified that the steering wheel return control has not been performed. For this reason, since it is possible to make the driver know in advance that the forklift 1 may start in a direction different from the direction predicted in anticipation of the execution of the steering wheel return control, in the unintended direction. It is possible to make the driver perform appropriate preparation and confirmation so that the forklift 1 does not start.

  Note that the notification timing to the driver may be notified immediately when it is determined in the return control process that the road surface state at the time of parking / stopping is not a low wear state, as in the present embodiment. In addition, when the driver gets in the driver's seat 4 and before the forklift 1 is started, for example, when the driver changes while parked or stopped, or when the boarding interval is vacant. However, it is possible to reliably notify the driver who starts the forklift 1.

<Correspondence with Invention>
In this embodiment, the controller 75 that performs the process of S160 is the steering wheel return control means, the controller 75 that performs the process of S140 is the road surface determination means, the controller 75 that performs the processes of the notification unit 83 and S105 is the notification means, and the vibration sensor. Reference numeral 85 denotes vibration detection means, memory 75b corresponds to storage means, controller 75 for performing vibration storage processing corresponds to vibration storage means, and vehicle speed sensor 79 corresponds to an example of speed detection means.

Second Embodiment
Next, a second embodiment of the present invention will be described. In the first embodiment, when the forklift 1 is stopped, the road surface is in a state with small unevenness (low wear state), which is a road surface condition that is one of the permission conditions for performing the steering wheel return control. On the other hand, the second embodiment is different in that the steering wheel 53 is separated from the road surface when the forklift 1 is stopped as a vehicle body condition which is one of the permission conditions. In the following, this difference and the configuration necessary to realize this will be mainly described, the same reference numerals are used for the parts common to the first embodiment, and description thereof will be omitted.

That is, the forklift 1 according to the second embodiment is provided with a hoisting mechanism 9 for lifting this portion at the lower end portion on the rear side of the vehicle body 2 as shown in FIG.
As shown in FIG. 6 (b), the hoisting mechanism 9 is a hydraulic jack used to separate the steering wheel 53 from the road surface before the steering wheel return control is performed, and is a hydraulic cylinder fixed to the vehicle body 2. 91, a piston rod 93 that moves up and down by a pressure change inside the hydraulic cylinder 91, a grounding portion 95 that supports the road surface in a state in which the piston rod 93 is pivotally supported at the lower end portion and extends downward. It is constituted by.

  The hydraulic cylinder 91 is fixed to the vehicle body 2 with the piston rod 93 and the grounding portion 95 facing downward, and as shown in FIG. 8C, an upper chamber 91a that is an upper oil chamber in the hydraulic cylinder 91, and a hydraulic pressure A lower chamber 91 b that is a lower oil chamber in the cylinder 91 is communicated with the hydraulic mechanism 8 via a supply / discharge mechanism 92.

  The supply / discharge mechanism 92 includes an oil supply path 92a for supplying oil (operating oil) boosted from the hydraulic mechanism 8 to the hydraulic cylinder 91, an oil discharge path 92b for discharging oil from the hydraulic cylinder 91 to the hydraulic mechanism 8, The directional switching valve 94 is configured to selectively switch each communication destination of the oil supply path 92a and the oil discharge path 92b to either the upper chamber 91a or the lower chamber 91b of the hydraulic cylinder 91. The hydraulic mechanism 8 is provided with a relief valve 97 that operates when the pressure in the oil supply path 92a communicating with the hydraulic pump 21 exceeds a set pressure. The relief valve 97 is provided on a path 92c that connects the oil supply path 92a and the oil discharge path 92b. When the relief valve 97 is operated, the pressure in the oil supply path 92a is reduced by opening the path 92c, and the relief pressure Is returned to the hydraulic tank 23 through the oil discharge path 92b.

  That is, when the hydraulic oil is supplied from the hydraulic mechanism 8 to the upper chamber 91a of the hydraulic cylinder 91 via the supply / discharge mechanism 92, the piston rod 93 moves downward due to the pressure increase in the upper chamber 91a. By doing (extending), the ground contact portion 95 presses the road surface and the lower end portion on the rear side of the vehicle body 2 is lifted, so that the steering wheel 53 can be separated from the road surface.

  Further, in the hoisting mechanism 9, the communication destinations of the oil supply path 92 a and the oil discharge path 92 b are switched by the direction switching valve 94, and the hydraulic mechanism 8 moves from the hydraulic mechanism 8 to the lower chamber 91 b through the supply / discharge mechanism 92. When hydraulic oil is supplied, the piston rod 93 moves upward (shrinks) due to the pressure increase in the lower chamber 91b, so that the ground contact portion 95 is separated from the road surface, and the lower end portion on the rear side of the vehicle body 2 is lowered. The steered wheel 53 can be grounded on the road surface.

  In the forklift 1 of the second embodiment, the controller 75 is configured to be able to control the hydraulic pump 21 and the switching valve (not shown) of the hydraulic mechanism 8 and the direction switching valve 94 of the supply / discharge mechanism 92.

<Return control processing (2)>
Next, a return control process executed by the controller 75 in the second embodiment will be described with reference to FIG. In addition, since the start conditions of this process are the same as that of 1st Embodiment, description is abbreviate | omitted. In this process, the same reference numerals (step numbers) are used for the processes common to the first embodiment, and detailed description thereof is omitted.

  When this process is started, the controller 75 performs steering wheel return control in the previous main process (S160) based on the history information stored in the memory 75b in the previous main process (S170) in S105. It is determined whether or not it has been implemented, and the driver is notified according to the determination result.

  Further, in S210, the controller 75 determines whether or not the first and second parking / stopping conditions and the unmanned condition in the first embodiment are satisfied, and when it is determined that these conditions are satisfied (S210; (YES), the process proceeds to S220, and if it is determined that these conditions are not satisfied (S210; NO), the process is terminated via S170. In the present embodiment, the road surface condition in the first embodiment is not determined. However, as a modification, there may be a mode in which the road surface condition is determined. That is, when it is determined that the road surface condition is satisfied, the processing after S150 in the first embodiment is performed, and when it is determined that the road surface condition is not satisfied, the processing after S220 in the second embodiment is performed. You may make it implement.

  Next, the controller 75 starts preparation for steering wheel return control. That is, in S220, a first switching command is issued to the direction switching valve 94 so that the oil supply path 92a communicates with the upper chamber 91a of the hydraulic cylinder 91 and the oil discharge path 92b communicates with the lower chamber 91b of the hydraulic cylinder 91. Output (set to energized state).

  In subsequent S230, the controller 75 operates the cargo handling motor M (see FIG. 8C), and the working oil boosted from the hydraulic pump 21 is supplied to the upper chamber 91a of the hydraulic cylinder 91 via the oil supply path 92a. Supply. The cargo handling motor M is for driving the hydraulic pump 21. As a result, the piston rod 93 moves (extends) downward due to the pressure increase in the upper chamber 91a of the hydraulic cylinder 91.

  In subsequent S240, the controller 75 determines whether or not a predetermined time has elapsed by a built-in timer (not shown). Here, the certain time is determined as the time required until the ground contact portion 95 presses the road surface and the lower end on the rear side of the vehicle body 2 is lifted.

  In S160, the controller 75 performs steering wheel return control. That is, operation control of the steering mechanism 54 (specifically, the assist motor 63) is started so that the steering angle of the steering wheel 53 detected by the steering angle sensor 73 returns to a predetermined reference angle.

  In the subsequent S165, the controller 75 notifies the notifying unit 83 of the buzzer so as to notify the periphery of the forklift 1 that the steering wheel return control is being performed with the start of the steering wheel return control in S160. Outputs a command.

  Next, the controller 75 determines whether or not the steering wheel return control is completed. If the controller 75 determines that the steering wheel return control is completed, the hydraulic cylinder 91 passes the oil discharge path 92b to the direction switching valve 94 in S250. A second switching command is output (set to the energized state) so as to communicate with the upper chamber 91a and to communicate the oil supply path 92a with the lower chamber 91b of the hydraulic cylinder 91.

  Then, the controller 75 activates the cargo handling motor M in S260, determines whether or not a certain time has passed in the subsequent S270, and proceeds to S280 when the certain time has passed (S260; YES). The fixed time here means that the piston rod 93 moves upward (shrinks) due to the pressure increase in the lower chamber 91b of the hydraulic cylinder 91, so that the ground contact portion 95 is separated from the road surface, and the rear side of the vehicle body 2 is This time is determined as the time required until the lower end is lowered (the steered wheel 53 contacts the road surface). Thereafter, the controller 75 deenergizes the direction switching valve 94 and returns it to neutral in S280.

  In continuing S170, the controller 75 memorize | stores the historical information regarding implementation of this process in the memory 75b, and complete | finishes this process. In other words, when the execution date and time of this process, whether or not the steering wheel return control (S160) is executed, and when the steering wheel return control is executed, the steering amount of the driven steering wheel 53 and the steering wheel return control are not executed. In such a case, information for identifying which permission condition is not satisfied among the first and second parking / stopping conditions and the unmanned condition is stored in the memory 75b as history information.

  In the return control process, it is counted that a predetermined time has elapsed in S240, and the steering wheel return control (S160) is started after the elapse of this time. However, the present invention is not limited to this, and the assist motor Based on the current value flowing through 63, it is determined whether or not the steered wheels 53 are separated from the road surface (road surface separated state). After determining that the steered wheels 53 are separated from the road surface, the steering wheel return control (S160) is performed. ) May be started.

  Thus, the road surface separation state can be suitably determined by utilizing the fact that the current value decreases when the motor load changes from a large state to a small state. That is, for example, before the steering wheel return control is performed, the steering wheel 53 is steered by the assist motor 63 so that when the road surface is separated from the road surface, the motor wheel is compared with the state in which the steering wheel 53 is in contact with the road surface. Since the rotation temporarily increases and the value of the current flowing to the motor decreases, the road surface separation state can be suitably determined by detecting this.

<Main effect (2)>
As described above, in the forklift 1 of the second embodiment, the return control process executed by the controller 75 of the steering device 5 under the configuration including the weight mechanism 9 as a drive mechanism for separating the steering wheel 53 from the road surface. , The steering wheel return control is performed with the vehicle body condition, which is one of the permission conditions, being that the steering wheel 53 is separated from the road surface by the heavy load mechanism 9 when the vehicle is parked or stopped.

  For this reason, the tire can be prevented from rubbing against the road surface in the steering wheel return control, so that the burden on the tire of the steering wheel 53 due to the steering wheel return control can be suppressed, and the uneven wear of the tire can be reduced more than before. Can be reduced.

  The hoisting mechanism 9 may be an electric type, but by adopting a hydraulic type as in the second embodiment, the hydraulic mechanism 8 normally mounted on the forklift 1 can be used. Therefore, it can contribute to cost reduction.

<Correspondence with Invention>
In the present embodiment, the controller 75 that performs the process of S240 corresponds to an example of a separation determination unit.

<Third Embodiment>
Next, a third embodiment of the present invention will be described. In the second embodiment, the driving mechanism that separates the steering wheel 53 from the road surface is configured to include the weight mechanism 9 (that is, a mechanism that lifts a part of the vehicle body 2), but in the third embodiment, The drive mechanism is different in that it includes a mechanism configured to lift the steering wheel 53. In the following, this difference and the configuration necessary to realize this will be mainly described, the same reference numerals are used for the parts common to the first embodiment, and description thereof will be omitted.

  That is, as shown in FIG. 8A, the forklift 1 of the third embodiment is connected to the driving wheel, which is also the steering wheel 53, on the rear wheel side via the suspension mechanism 10 on the rear wheel side. A caster wheel 101 is provided. The drive wheels (steering wheels 53) and caster wheels 101 are supported by the vehicle body 2 via the suspension mechanism 10. In addition, the steering wheel support portion 55 is provided with an extension portion 102 of the steering device 5 that is spaced apart from the steering wheel support portion 55 and extends downward on the caster wheel 101 side.

  The suspension mechanism 10 includes an upper link 103, a lower link 105, a caster link 107, a main spring 109, a caster spring 111, and the like. The upper link 103 is pivotally supported by a link pin at the right end portion on the vehicle body 2 and the left end portion on the extending portion 102 of the steering device 5, and the lower link 105 is located on the lower side of the upper link 103 with the intermediate portion at the vehicle body 2. The left end is pivotally supported by a link pin on the extended portion 102 of the steering device 5. The caster link 107 is pivotally supported by a link pin at the left end at the middle portion of the lower link 105, and a caster wheel 101 is rotatably attached to the lower right end of the caster link 107, and the upper surface of the caster link 107 and the lower link 105 A caster spring 111 is disposed therebetween. The main spring 109 is provided so as to be sandwiched between the vehicle body 2 and the upper surface of the extending portion 102, and thus the drive wheel (steering wheel 53) and the caster wheel 101 can move up and down.

  The locking device 11 of the suspension mechanism 10 includes a lock cylinder 121, a piston rod 123, and the like. The lock cylinder 121 is fixed to the vehicle body 2 on the upper side of the right end portion on the upper surface of the extension portion 102, and the piston rod 123 has an upper end portion disposed inside the lock cylinder 121 and a lower end portion of the extension portion 102. It is being fixed to the right end part in the upper surface. The operating principles of the lock cylinder 121 and the piston rod 123 are the same as in the second embodiment.

  That is, according to the second embodiment, in the lock device 11 of the suspension mechanism 10, the piston rod 123 is switched from a freely movable state (free state) to a non-movable state (locked state). For example, in the forklift 1, the suspension mechanism 10 is locked when the suspension mechanism 10 is free as described above and the vehicle body 2 is tilted (for example, conditions caused by steering operation during lift, lift operation, etc.). By switching to the state, a well-known suspension lock function that suppresses tilting of the vehicle body 2 is realized.

  On the other hand, in the lock device 11 of the suspension mechanism 10 according to the present embodiment, each communication destination of the oil supply path 92a and the oil discharge path 92b is switched by the direction switching valve 94, and is locked from the hydraulic mechanism 8 via the supply / discharge mechanism 92. When the hydraulic oil is supplied to the lower chamber 91b of the cylinder 121, the piston rod 123 moves upward (shrinks) due to the pressure increase in the lower chamber 91b, whereby the driving wheel (steering wheel 53) is lifted, and FIG. As shown in (b), the attachment portion 130 provided at the lower left end portion of the vehicle body 2 can be brought into contact with the road surface, and the drive wheels (steering wheels 53) can be separated from the road surface. That is, the size and the movable area of the lock cylinder 121 and the piston rod 123 are set in advance so that the drive wheel (steering wheel 53) can be separated from the road surface in this way. The attachment portion 130 is provided at a position corresponding to the driving wheel (steering wheel 53) at the lower left end portion of the vehicle body 2, and in a neutral state where the locking device 11 of the suspension mechanism 10 is not operated. The lower end is attached so as to be located below the lower surface of the vehicle body 2 and above the ground contact surface of the steering wheel 53.

  Thus, according to the forklift 1 of the third embodiment, the steering wheel 53 can be suitably separated from the road surface by using the mechanism of the lock device 11 that restricts the function of the provided suspension mechanism 10. That is, in the locking device 11 of the suspension mechanism 10, the operation (the lifting operation of the piston rod 123) opposite to the operation of the normally used suspension locking function (the lifting operation of the piston rod 123) is performed as the operation of the lifting function of the steering wheel 53. By being configured so as to be applicable to the above, it is not necessary to attach a new drive mechanism, which can contribute to cost reduction.

<Return control processing (3)>
Next, a return control process executed by the controller 75 in the third embodiment will be described. Note that the return control process of the third embodiment has the same base as that of the second embodiment, and therefore only different parts will be described with reference to FIG.

  That is, in S220 of this process, the controller 75 communicates the direction switching valve 94 with the oil supply path 92a in the lower chamber 91b of the lock cylinder 121 and the oil discharge path 92b in communication with the upper chamber 91a of the lock cylinder 121. A first switching command is output (turned on).

  In S230, the controller 75 operates the cargo handling motor M (see FIG. 8C) to supply the working oil boosted from the hydraulic pump 21 to the lower chamber 91b of the hydraulic cylinder 91 via the oil supply path 92a. To do. As a result, the piston rod 93 moves upward (shrinks) due to the pressure increase in the lower chamber 91b of the hydraulic cylinder 91.

  In S240, the controller 75 determines whether or not a predetermined time has elapsed by a built-in timer (not shown), and when the predetermined time has elapsed (S240; YES), the controller 75 proceeds to S160. Here, the certain time is determined as the time required for the steering wheel 53 to be lifted and the attachment portion 130 to contact the road surface.

In the return control process of the third embodiment, the processes of S250 to S270 are not performed.
In S280, the controller 75 deenergizes the direction switching valve 94 and returns it to neutral. As a result, the piston rod 93 moves (extends) downward due to the pressure drop in the lower chamber 91b of the hydraulic cylinder 91. And the attachment part 130 will leave | separate from a road surface, the left end part of the back side of the vehicle body 2 will go up, and it will be in the state which the steering wheel 53 contacts the road surface.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, In the range which does not deviate from the summary of this invention, it is possible to implement in various aspects.

  DESCRIPTION OF SYMBOLS 1 ... Forklift, 2 ... Vehicle body, 3 ... Cargo handling mechanism, 4 ... Driver's seat, 5 ... Steering device, 6 ... Operation part, 8 ... Hydraulic mechanism, 9 ... Heavy load mechanism, 10 ... Suspension mechanism, 11 ... Locking device, 21 DESCRIPTION OF SYMBOLS ... Hydraulic pump, 23 ... Hydraulic tank, 31 ... Fork, 33 ... Mast, 51 ... Steering, 52 ... Handle, 53 ... Steering wheel, 54 ... Steering mechanism, 55 ... Steering wheel support, 57 ... Steering gear, 59 ... Drive Motor 61: Steering transmission mechanism 63 ... Assist motor 65 ... Operation circuit 67 ... Transmission gear 71 ... Torque sensor 73 ... Steering angle sensor 75 ... Controller 75a ... Microcomputer 75b ... Memory 77 ... Driver Detection sensor, 79 ... Vehicle speed sensor, 81 ... Key sensor, 83 ... Notification unit, 85 ... Vibration sensor, 87 ... Inclination sensor, 91 ... Hydraulic cylinder, 91a ... Upper chamber, 91b ... Lower , 92 ... Supply / discharge mechanism, 92a ... Oil supply path, 92b ... Oil discharge path, 93 ... Piston rod, 94 ... Direction switching valve, 95 ... Grounding part, 97 ... Relief valve, 101 ... Caster wheel, 102 ... Extension part, DESCRIPTION OF SYMBOLS 103 ... Upper link, 105 ... Lower link, 107 ... Caster link, 109 ... Main spring, 111 ... Caster spring, 121 ... Lock cylinder, 123 ... Piston rod, 130 ... Additional part, M ... Carrying motor.

Claims (14)

A steering system that will be installed in an industrial vehicle,
Steering operated by a driver of the industrial vehicle;
A steering mechanism for steering a steered wheel to determine a traveling direction of the industrial vehicle in response to an operation of the steering by the driver ;
Steering wheel return control means for controlling the operation of the steering mechanism so that the steering angle of the steering wheel becomes a predetermined reference angle when a predetermined permission condition is satisfied when the industrial vehicle is stopped;
Includes a road surface determination means for determining whether the road surface on which the steering wheel had us when stopped before Symbol industrial vehicle is grounded is small have state of the irregularities, and
The predetermined permission condition is a steering device characterized by comprising the road by the road surface judging means is judged to be small state uneven. Steering device according to claim 1, characterized in that when the road surface is determined not to be smaller state uneven by the road surface judging means comprises notifying means for notifying the driver to not perform the operation control. Comprising vibration detecting means for detecting a state value based on vibration of the industrial vehicle;
The steering apparatus according to claim 1 or 2, wherein the road surface determination unit determines whether or not the road surface is in an uneven state based on a detection value of the vibration detection unit. . A vibration storage means for storing the detection value of the vibration detection means in a predetermined storage means;
The road surface determination means determines whether or not the road surface is in an uneven state based on the detection value stored by the vibration storage means during travel of the industrial vehicle. Item 4. The steering device according to Item 3. Comprising a speed detecting means for detecting the traveling speed of the industrial vehicle;
The road surface determination means is a period in which the speed detected by the speed detection means is equal to or higher than a predetermined threshold speed, and the detected value stored in the vibration storage means is within a certain period closest to when the industrial vehicle is stopped. The steering device according to claim 4, wherein it is determined whether or not the road surface is in a state of small unevenness based on the determination. The said road surface determination means determines that the said road surface is not a state with small unevenness | corrugation , when the detection value of the said vibration detection means exceeds the predetermined vibration threshold value in multiple times. The steering device according to any one of claims. A steering system that will be installed in an industrial vehicle,
Steering operated by a driver of the industrial vehicle;
A steering mechanism for steering a steered wheel to determine a traveling direction of the industrial vehicle in response to an operation of the steering by the driver ;
Steering wheel return control means for controlling the operation of the steering mechanism so that the steering angle of the steering wheel becomes a predetermined reference angle when a predetermined permission condition is satisfied when the industrial vehicle is stopped;
And a driving mechanism for separating the pre-Symbol steering wheel from the road surface,
The predetermined permission condition is a steering device characterized by comprising the drive mechanism at the time of stopping the industrial vehicle is moved away the steering wheel from the road surface. A separation determining means for determining whether or not the steered wheel is separated from the road surface;
The steering apparatus according to claim 7, wherein the steering wheel return control unit performs the operation control when the separation determination unit determines that the road surface is separated. The steering mechanism has an electric motor that drives the steered wheels to assist the steering by the driver,
The steering apparatus according to claim 8, wherein the separation determination unit determines the road surface separation state based on a current value flowing through the electric motor.   The steering device according to any one of claims 7 to 9, wherein the drive mechanism is a mechanism configured to lift a portion of the body of the industrial vehicle on the steering wheel side. .   The drive mechanism uses a lock cylinder for restricting the vertical swing of the steering wheel, and is configured to lift the steering wheel by a piston that moves up and down by a pressure change inside the lock cylinder. The steering apparatus according to any one of claims 7 to 9, wherein   An industrial vehicle equipped with the steering device according to any one of claims 1 to 11. Steering operated by an industrial vehicle driver;
A steering mechanism for steering a steered wheel to determine a traveling direction of the industrial vehicle in response to an operation of the steering by the driver;
A controller for controlling a steering device comprising:
請 Motomeko 1 to Claim 6 program for functioning as the steering wheel return control means and the road surface judging means according to any one of. Steering operated by an industrial vehicle driver;
A steering mechanism for steering a steered wheel to determine a traveling direction of the industrial vehicle in response to an operation of the steering by the driver;
A drive mechanism for separating the steering wheel from the road surface;
A controller for controlling a steering device comprising:
請 Motomeko 7 to program for functioning as the steering wheel return control unit according to any one of claims 11.

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