Steering device for industrial vehicle

Abstract

The steering device 100A of the industrial vehicle of the present application is provided with: an oil pressure pump 31; a steering cylinder 32; a manual steering circuit 40 that supplies hydraulic oil ejected from the oil pressure pump 31 to the steering cylinder 32 through a PS valve 41 that is opened and closed in accordance with operation of a steering wheel 33; an automatic steering circuit 50 that supplies hydraulic oil ejected from the oil pressure pump 31 to the steering cylinder 32 through an electromagnetic proportional valve 51 that is opened and closed in accordance with an arithmetic result of automatic driving control; and a priority valve 60 that is provided between the oil pressure pump 31 and the PS valve 41 and the electromagnetic proportional valve 51, that divides hydraulic oil to the manual steering circuit 40 and the automatic steering circuit 50, and that preferentially supplies hydraulic oil to the manual steering circuit 40 at a design flow rate that is equal to or greater than a prescribed flow rate at which the steering cylinder 32 is operated.

Description

Technical Field

[0001] This invention relates to a steering device for industrial vehicles. Background Technology

[0002] Previously, as a technology related to steering systems in industrial vehicles, there were known vehicle steering control devices that selectively switch between manual steering mode and automatic steering mode using a hydraulic switching mechanism employing a direction switching valve.

[0003] [Background Technical Documents]

[0004] [Patent Literature]

[0005] Patent Document 1: Japanese Patent Application Publication No. 9-254801 Summary of the Invention

[0006] [The problem the invention aims to solve]

[0007] The vehicle steering control device described in the background art operates as a hydraulic reaction force power steering system by simultaneously and equally supplying hydraulic pressure to both of a pair of hydraulic chambers in manual steering mode. In automatic steering mode, hydraulic pressure is supplied to either hydraulic chamber corresponding to the steering direction by switching control via a direction switching valve, enabling automatic steering. In this configuration, since the manual and automatic steering modes are selectively switched by switching the direction switching valve, it is sometimes difficult for the hydraulic circuit to function according to the manual steering performed by the operator, for example, in automatic steering mode.

[0008] The purpose of this invention is to provide a steering device for industrial vehicles that allows for manual steering even when automatic steering is in operation, thus enabling the hydraulic circuit to function.

[0009] [Technical means to solve the problem]

[0010] An industrial vehicle steering device according to one aspect of the present invention includes a hydraulic pump that injects hydraulic oil and a steering cylinder that turns a steering wheel by supplying hydraulic oil. It further includes: a manual steering circuit having a first valve that opens and closes according to steering wheel operation, through which hydraulic oil injected from the hydraulic pump is supplied to the steering cylinder; an automatic steering circuit having a second valve that opens and closes according to the calculation result of automatic driving control, through which hydraulic oil injected from the hydraulic pump is supplied to the steering cylinder; and a flow divider valve disposed between the hydraulic pump, the first valve, and the second valve, to divide the hydraulic oil into the manual steering circuit and the automatic steering circuit; and the flow divider valve is a priority valve that preferentially supplies hydraulic oil to the manual steering circuit at a design flow rate exceeding a predetermined flow rate for operating the steering cylinder.

[0011] In a steering system for an industrial vehicle according to one aspect of the present invention, hydraulic oil is diverted to a manual steering circuit and an automatic steering circuit via a flow divider valve. The flow divider valve is a priority valve that supplies hydraulic oil preferentially to the manual steering circuit at a design flow rate exceeding a predetermined flow rate to operate the steering cylinder. Therefore, even when the second valve is open according to the calculation results of automatic driving control, at least a predetermined flow rate of hydraulic oil is supplied to the manual steering circuit, allowing the steering cylinder to operate according to the steering wheel operation. Thus, the steering system for an industrial vehicle according to one aspect of the present invention enables the hydraulic circuit to function in a manner that allows for both automatic and manual steering, even when automatic steering is possible.

[0012] In one embodiment, the steering system of the industrial vehicle may further include an unloading mechanism that reduces the pressure of the hydraulic oil acting on the second valve when the predetermined automatic steering non-operating condition of suspending the supply of hydraulic oil through the second valve is met, compared to the case where the automatic steering non-operating condition is not met. In this case, if the diverter valve is configured in such a way that the supply of hydraulic oil to the second valve is never completely cut off, and if it is assumed that the remaining flow of hydraulic oil supplied to the automatic steering circuit side is not returned to the oil tank, then the pressure of the hydraulic oil from the hydraulic pump always acts on the second valve, thus placing an unnecessary load on the hydraulic pump. Therefore, by reducing the pressure of the hydraulic oil from the hydraulic pump acting on the second valve when the automatic steering non-operating condition is not met through the unloading mechanism, the unnecessary load on the hydraulic pump can be suppressed. As a result, the operating time of the steering system of the industrial vehicle due to the unnecessary load on the hydraulic pump can be reduced.

[0013] In one embodiment, the unloading mechanism may include: a control unit that determines whether automatic steering non-operation conditions are met based on information related to the execution or non-execution of automatic driving control, or vehicle speed information of the industrial vehicle; and an unloading valve configured to reduce the pressure of hydraulic oil from the hydraulic pump acting on the second valve based on the determination result of the control unit; and the control unit controls the unloading valve to reduce the pressure of hydraulic oil from the hydraulic pump acting on the second valve when it determines that the automatic steering non-operation conditions are met. In this case, by controlling the unloading valve based on the determination result of the control unit, the pressure of hydraulic oil from the hydraulic pump acting on the second valve can be reduced when the automatic steering non-operation conditions are met.

[0014] In one embodiment, the unloading mechanism may include: a control unit that determines whether automatic steering non-operation conditions are met based on information related to the execution or non-execution of automatic driving control, or vehicle speed information of an industrial vehicle; and a variable capacity pump, which is configured to change the amount of hydraulic oil injected during operation based on the determination result of the control unit; and when the control unit determines that the automatic steering non-operation conditions are met, it controls the variable capacity pump to reduce the amount of hydraulic oil injected. In this case, by controlling the injection amount of the variable capacity pump during operation based on the determination result of the control unit, the pressure of the hydraulic oil from the variable capacity pump acting on the second valve can be reduced when the automatic steering non-operation conditions are met.

[0015] In one embodiment, it is feasible for the control unit to determine that the automatic steering non-operation condition is met when the switch is in the non-executable state of automatic driving control, based on a signal from a switch used to switch between automatic driving control and non-executable state. In this case, it is possible to suppress the application of unnecessary load to the hydraulic pump when automatic driving control is not being executed and automatic steering is not being performed.

[0016] In one embodiment, it is feasible for the control unit to determine, based on the vehicle speed information, whether the industrial vehicle has been continuously stopped for a predetermined time. If it is determined that the industrial vehicle has been continuously stopped for the predetermined time, it is determined that the automatic steering non-operation condition is met. In this case, it is possible to prevent unnecessary load from being applied to the hydraulic pump when the industrial vehicle has been continuously stopped for the predetermined time.

[0017] Another aspect of the present invention provides a steering device for an industrial vehicle, comprising a hydraulic pump that injects hydraulic oil and a steering cylinder that turns a steering wheel by supplying hydraulic oil, and further comprising: a manual steering circuit having a first valve that opens and closes according to steering wheel operation, through which hydraulic oil injected from the hydraulic pump is supplied to the steering cylinder; an automatic steering circuit having a second valve that opens and closes according to the calculation result of automatic driving control, through which hydraulic oil injected from the hydraulic pump is supplied to the steering cylinder; and a diverter valve disposed between the hydraulic pump, the first valve, and the second valve, for diverting hydraulic oil to the manual steering circuit. The system includes an automatic steering circuit and a steering operation detection unit that detects steering wheel operation. A flow divider valve is a priority valve that supplies hydraulic oil preferentially to the manual steering circuit at a first flow rate exceeding a predetermined flow rate from the hydraulic oil injected from the hydraulic pump that operates the steering cylinder. It also supplies hydraulic oil to the automatic steering circuit at a second flow rate, the remaining flow rate from the hydraulic oil injected from the hydraulic pump excluding the first flow rate. Furthermore, the steering device of this industrial vehicle includes a supply limiting mechanism that restricts the supply of hydraulic oil to the steering cylinder through the automatic steering circuit when the steering operation detection unit detects steering wheel operation.

[0018] In another aspect of the steering system for an industrial vehicle according to the present invention, even when the steering wheel is being operated, the flow divider valve supplies hydraulic oil to the automatic steering circuit at a second flow rate when residual flow is generated. The supply of hydraulic oil to the steering cylinder via the automatic steering circuit is restricted by a supply limiting mechanism when the steering operation detection unit detects steering wheel operation. Thus, when the steering wheel is being operated, the operation of the steering cylinder using the hydraulic oil supplied to the automatic steering circuit is restricted. Therefore, according to another aspect of the steering system for an industrial vehicle according to the present invention, the influence of the hydraulic oil supplied via the automatic steering circuit on the operation of the steering cylinder corresponding to steering wheel operation can be suppressed.

[0019] In one embodiment, the supply limiting mechanism may include a control unit that controls the second valve to prevent the supply of hydraulic oil from the hydraulic pump to the steering cylinder when the steering operation detection unit detects steering wheel operation. In this case, when the steering wheel is operated, by blocking the hydraulic oil supplied to the automatic steering circuit with the second valve, the operation of the steering cylinder, which is achieved using the hydraulic oil supplied to the automatic steering circuit, can be limited.

[0020] In one embodiment, the supply limiting mechanism may include: an unloading valve configured to reduce the pressure of the hydraulic oil in the automatic steering circuit; and a control unit that controls the unloading valve to reduce the pressure of the hydraulic oil in the automatic steering circuit when the steering operation detection unit detects steering wheel operation. In this case, by using the unloading valve to reduce the pressure of the hydraulic oil in the automatic steering circuit when the steering wheel is operated, the operation of the steering cylinder, which is implemented using the hydraulic oil supplied to the automatic steering circuit, can be limited.

[0021] In one embodiment, it is feasible for the steering wheel operation to be a predetermined operation performed by the operator of the industrial vehicle, and the steering operation detection unit to detect the predetermined operation when the steering wheel rotation speed is below a predetermined rotation speed threshold. Since the slower the steering wheel rotation speed during operation, the smaller the flow of hydraulic oil through the manual steering circuit to the steering cylinder, excess flow is easily generated. Therefore, by detecting the predetermined operation when the steering wheel rotation speed is below the rotation speed threshold, the supply of hydraulic oil through the automatic steering circuit to the steering cylinder is limited, thereby appropriately suppressing the influence of the hydraulic oil supplied through the automatic steering circuit on the operation of the steering cylinder corresponding to the steering wheel operation.

[0022] [The effects of the invention]

[0023] According to the present invention, the hydraulic circuit can function even when automatic steering is possible, allowing for manual steering as well. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of an industrial vehicle that uses the steering device of the industrial vehicle according to the first embodiment.

[0025] Figure 2 It means Figure 1 A rough circuit diagram of the steering hydraulic circuit.

[0026] Figure 3 yes Figure 2 An example of a hydraulic circuit diagram for an electromagnetic proportional valve.

[0027] Figure 4 It means Figure 1 A block diagram illustrating the functional structure of the steering system in an industrial vehicle.

[0028] Figure 5 It is along Figure 1 A schematic cross-sectional view of the axis of the priority valve.

[0029] Figure 6 It is along Figure 1 A schematic cross-sectional view of the axis of the priority valve.

[0030] Figure 7 This is an example Figure 1 The flowchart shows the unloading process of the controller.

[0031] Figure 8 This is an example Figure 7 The flowchart shows the process for determining and handling non-working conditions during automatic steering.

[0032] Figure 9 This is a schematic diagram of an industrial vehicle that uses the steering device of the industrial vehicle according to the second embodiment.

[0033] Figure 10 It means Figure 9 A rough circuit diagram of the steering hydraulic circuit.

[0034] Figure 11 It means Figure 9 A block diagram illustrating the functional structure of the steering system in an industrial vehicle.

[0035] Figure 12 This is a timing diagram showing the flow rate of hydraulic oil in the forward steering cylinder when no restrictions are imposed by the supply restriction mechanism.

[0036] Figure 13 This is a timing diagram showing the flow rate of hydraulic oil in the forward steering cylinder when restrictions are imposed by the supply restriction mechanism.

[0037] Figure 14 This is an example Figure 9 The flowchart shows the supply constraint handling process for the controller.

[0038] Figure 15 This is an example Figure 14 The flowchart for steering operation detection and processing. Detailed Implementation

[0039] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, in the drawings, the same or equivalent elements are labeled with the same symbols, and repeated descriptions are omitted.

[0040] [First Implementation]

[0041] Figure 1 This is a schematic diagram of an industrial vehicle that uses the steering device of the industrial vehicle according to the first embodiment. Figure 1 The industrial vehicle 1A shown is, for example, an electric tractor, used to tow containers carrying goods in airports, factories, ports, etc.

[0042] Industrial vehicle 1A is configured to perform automatic driving control. Automatic driving is a vehicle control state in which the industrial vehicle 1A moves automatically according to transport instructions from, for example, an operation management system. The operation management system is a control system that performs transport instructions, monitors operation, and monitors the vehicle status of the industrial vehicle 1A. Automatic driving requires no operator intervention; the industrial vehicle 1A moves automatically.

[0043] The automated driving here is implemented in designated areas, such as runways, takeoff and landing areas, taxiways, aprons, control towers, hangars, cargo loading and unloading areas, and charging stations in airports. Industrial vehicle 1A can perform automated driving within these designated areas along a pre-set route. In this embodiment, a driving plan is generated, which includes automatically turning industrial vehicle 1A at points such as intersections along the pre-set route according to the calculation results of automated driving control. Furthermore, the driving route of industrial vehicle 1A is not fixed and can be changed from the pre-set route. A non-fixed driving route means a driving route that can be changed by altering the driving plan generated based on map information, etc., rather than a route that is difficult to change once set, such as that of an Automated Guided Vehicle (AGV) that travels along, for example, a magnetic strip set on the road surface.

[0044] [The composition of driving and steering in industrial vehicles]

[0045] Industrial vehicle 1A includes: a steering wheel, FL tire 2 and FR tire 3 located at the front of the vehicle body, and RL tire 4 and RR tire 5 located at the rear of the vehicle body. Industrial vehicle 1A includes a left drive motor 6 driving the RL tire 4 and a right drive motor 7 driving the RR tire 5, serving as drive motors. The drive motors also function as a braking unit 8 that generates regenerative braking force.

[0046] The left drive motor 6 and the right drive motor 7 are AC motors that function as generators. A speed reducer, namely the left drive unit 6a, is sandwiched between the left drive motor 6 and the RL tire 4. Similarly, a speed reducer, namely the right drive unit 7a, is sandwiched between the right drive motor 7 and the RR tire 5.

[0047] The left drive motor 6 is electrically connected to the contactor 9 via the left motor driver 6b. The right drive motor 7 is electrically connected to the contactor 9 via the right motor driver 7b. Both the left motor driver 6b and the right motor driver 7b have, for example, inverters and are electrically connected to the controller (control unit) 10A. The power operation and regeneration of the left drive motor 6 and the right drive motor 7 in the left motor driver 6b and the right motor driver 7b are controlled by the controller 10A.

[0048] Contactor 9 is electrically connected to battery B and hydraulic pump 31 of steering hydraulic circuit (hydraulic circuit) 30. Contactor 9 is also electrically connected to controller 10A, and the power supply to battery B is controlled by controller 10A.

[0049] Battery B is the power supply source for the left drive motor 6, the right drive motor 7, and the hydraulic pump 31. Battery B is composed of, for example, a lead-acid battery.

[0050] If the left drive motor 6 is rotated, the driving force of the left drive motor 6 is transmitted to the RL tire 4 through the left drive unit 6a, causing the RL tire 4 to rotate. When the industrial vehicle 1A brakes, the left drive motor 6 operates as a generator due to the rotation of the RL tire 4. If the right drive motor 7 is rotated, the driving force of the right drive motor 7 is transmitted to the RR tire 5 through the right drive unit 7a, causing the RR tire 5 to rotate. When the industrial vehicle 1A brakes, the right drive motor 7 operates as a generator due to the rotation of the RR tire 5.

[0051] The industrial vehicle 1A includes a steering device 100A. The steering device 100A of the industrial vehicle is configured as a hydraulic power steering system that turns the steering wheel by means of a supply of hydraulic fluid. Figure 2 It means Figure 1 A simplified circuit diagram of the steering hydraulic circuit. (See attached diagram.) Figure 2As shown, the steering device 100A of the industrial vehicle includes: a contactor 9, a controller 10A, a steering hydraulic circuit 30, a hydraulic pump 31, a steering cylinder 32, and a steering wheel 33. The steering hydraulic circuit 30 is a hydraulic circuit consisting of a manual steering circuit 40, an automatic steering circuit 50, and a priority valve 60.

[0052] Hydraulic pump 31 is the hydraulic pressure source for injecting hydraulic oil. Hydraulic pump 31 is configured to deliver hydraulic oil stored in oil tank 34 to hydraulic pump circuit 30a. As an example, hydraulic pump 31 is configured as a constant-capacity pump where the amount of hydraulic oil injected during operation (the amount injected at the same speed) is constant. Hydraulic pump 31 is electrically connected to contactor 9, and the speed is controlled by controller 10A via contactor 9, thereby controlling the injection volume.

[0053] The steering cylinder 32 operates by supplying hydraulic oil to steer the steering wheel, i.e., the FL tire 2 and FR tire 3. The steering cylinder 32 has a hydraulic oil supply port 32a to a left cylinder for steering the FL tire 2, and a hydraulic oil supply port 32b to a right cylinder for steering the FR tire 3. Supply port 32a is connected via a hydraulic circuit to a confluence section 30b of the manual steering circuit 40 and the automatic steering circuit 50. Supply port 32b is connected via a hydraulic circuit to another confluence section 30c of the manual steering circuit 40 and the automatic steering circuit 50.

[0054] The manual steering circuit 40 has a PS valve (first valve) 41 that opens and closes according to the operation of the steering wheel 33. The manual steering circuit 40 is a hydraulic circuit that supplies hydraulic oil injected from the hydraulic pump 31 to the steering cylinder 32 through the PS valve 41. The PS valve 41 is a so-called power steering valve.

[0055] The automatic steering circuit 50 includes a solenoid proportional valve (second valve) 51 that opens and closes according to the calculation results of automatic driving control. The automatic steering circuit 50 is a hydraulic circuit that supplies hydraulic oil injected from the hydraulic pump 31 to the steering cylinder 32 via the solenoid proportional valve 51. The solenoid proportional valve 51 is a so-called hydraulic control valve. Here, the solenoid proportional valve 51 uses the pressure of the hydraulic oil from the hydraulic pump 31 acting on it as a pilot pressure to open the internal valve stem 53 (see reference). Figure 3This is a pilot-operated solenoid proportional valve 51. For example, the solenoid proportional valve 51 neutralizes the valve stem 53, preventing the supply of hydraulic oil from the hydraulic pump 31 to the steering cylinder 32. The solenoid proportional valve 51 is electrically connected to a controller 10A, which controls its opening and closing (position of the valve stem 53). Furthermore, for convenience, in the following description, the state where hydraulic oil from the hydraulic pump 31 can be supplied to the steering cylinder 32 through the solenoid proportional valve 51 is expressed as "soleoid proportional valve 51 is open," and the state where hydraulic oil from the hydraulic pump 31 is not supplied to the steering cylinder 32 through the solenoid proportional valve 51 is expressed as "soleoid proportional valve 51 is closed."

[0056] Priority valve 60 is positioned between hydraulic pump 31, PS valve 41, and solenoid proportional valve 51. Priority valve 60 is a flow divider valve that diverts hydraulic oil supplied from hydraulic pump 31 via hydraulic pump circuit 30a to the manual steering circuit 40 on the PS valve 41 side and the automatic steering circuit 50 on the solenoid proportional valve 51 side. The structure related to the flow diversion of priority valve 60 is described in detail below.

[0057] In the manual steering circuit 40, hydraulic oil from the hydraulic pump circuit 30a flows into the PS valve 41 through the priority valve 60. The PS valve 41, which is opened according to the operation of the steering wheel 33, supplies hydraulic oil to the confluence section 30b and confluence section 30c. As a result, hydraulic oil is supplied to the steering cylinder 32, and the steering wheel, i.e., the FL tire 2 and FR tire 3, is steered according to the operation of the steering wheel 33.

[0058] In the automatic steering circuit 50, hydraulic oil from the hydraulic pump circuit 30a flows into the solenoid proportional valve 51 through the priority valve 60. The solenoid proportional valve 51, which opens according to the calculation results of the automatic driving control, supplies hydraulic oil to the confluence section 30b and confluence section 30c. As a result, hydraulic oil is supplied to the steering cylinder 32, and the steering wheel, i.e., the FL tire 2 and FR tire 3, is steered according to the calculation results of the automatic driving control.

[0059] The electromagnetic proportional valve 51 has an unloading valve 52, which is configured to reduce the pressure of the hydraulic oil (hydraulic oil of the automatic steering circuit 50) acting on the electromagnetic proportional valve 51 from the hydraulic pump 31. The unloading valve 52 is connected to the oil tank 34 via the return oil circuit 30d. The unloading valve 52 is electrically connected to the controller 10A. In the first embodiment, based on the determination result of the controller 10A, when the controller 10A determines that the automatic steering non-operating conditions are met, the unloading valve 52 causes the hydraulic oil to return to the oil tank 34 through the return oil circuit 30d, thereby reducing the pressure (i.e., pilot pressure) of the hydraulic oil acting on the electromagnetic proportional valve 51 from the hydraulic pump 31.

[0060] Figure 3 yes Figure 2 An example hydraulic circuit diagram of an electromagnetic proportional valve. (See diagram below.) Figure 3 As shown, the electromagnetic proportional valve 51 includes a pilot valve 52a and a safety valve 52b constituting the unloading valve 52, as well as a valve stem 53. In the electromagnetic proportional valve 51, along the main circuit extending from the symbol P (… Figure 3 The solid line indicates that hydraulic oil is supplied to the unloading pilot valve 52a, the safety valve 52b, and the valve stem 53. Figure 3 The symbol P and Figure 2 The symbol P corresponds to the hydraulic oil supplied by the priority valve 60.

[0061] If the unloading pilot valve 52a is actuated by the controller 10A, then along the pilot circuit ( Figure 3 (The dashed line) supplies hydraulic oil to the safety valve 52b through the unloading pilot valve 52a, and the pilot pressure acts on the safety valve 52b. This causes the safety valve 52b to actuate. Figure 3 The symbol T and Figure 2 The symbol T corresponds to the return oil circuit 30d that returns hydraulic oil from the solenoid proportional valve 51 to the oil tank 34. Hydraulic oil from symbol P flows through safety valve 52b (solid line) to symbol T and returns to the oil tank 34 based on the balance of the hydraulic oil pressure at symbol P, the pressure in the oil tank 34, the pressure equivalent to the pressure loss to the oil tank 34, and the set pressure of the spring of safety valve 52b.

[0062] As an example, valve spool 53 is configured with three possible positions: P1, P2, and P3. If valve spool 53 is actuated by controller 10A, then valve spool 53 is moved such that its position is any one of positions P1, P2, or P3. Position P1 is the valve spool position where hydraulic oil from symbol P flows to symbol C1. Position P2 is the valve spool position where hydraulic oil from symbol P flows to symbol C2. Figure 3 The symbols C1, C2 and Figure 2 The symbols C1 and C2 correspond.

[0063] With the valve stem in position P1, hydraulic oil from symbol P flows through valve stem 53 to symbol C1. Hydraulic oil passing through symbol C1 is supplied to the supply port 32b of steering cylinder 32 via confluence 30c, discharged from the supply port 32a of steering cylinder 32, and returns to symbol C2 via confluence 30b. Hydraulic oil passing through symbol C2 flows through valve stem 53 to symbol T and returns to oil tank 34.

[0064] With the valve stem in position P2, hydraulic oil from symbol P flows through valve stem 53 to symbol C2. Hydraulic oil passing through symbol C2 is supplied to the supply port 32a of steering cylinder 32 via confluence 30b, exits from the supply port 32b of steering cylinder 32, and returns to symbol C1 via confluence 30c. Hydraulic oil passing through symbol C1 flows through valve stem 53 to symbol T and returns to oil tank 34.

[0065] When the valve stem is in position P3, the hydraulic oil from symbol P will not flow to symbol C1 or symbol C2. That is, when the valve stem is in position P3, the valve stem 53 is in a neutral state.

[0066] Furthermore, the PS valve 41 is connected to the oil tank 34 via the return oil circuit 30e. In the PS valve 41, hydraulic oil flowing into it via the priority valve 60, with a flow rate exceeding that supplied to the steering cylinder 32, returns to the oil tank 34 via the return oil circuit 30e. Examples of such situations include: when the steering wheel 33 is not operated, when the steering wheel 33 is operated at a relatively slow speed, and when the steering wheel 33 is operated at an excessively slow speed.

[0067] [Components of Automatic Driving Control and Automatic Steering in Industrial Vehicles]

[0068] Figure 4 It means Figure 1 This is a block diagram illustrating the functional structure of a steering system for an industrial vehicle. The steering system 100A of the industrial vehicle includes a controller 10A, which oversees both steering control and automatic driving control of the industrial vehicle 1A. The controller 10A is an electronic control unit containing a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc. In the controller 10A, for example, various functions are achieved by loading a program recorded in the ROM into the RAM and executing the program loaded into the RAM using the CPU. The controller 10A can also detect the voltage of the battery B. Furthermore, the controller 10A can be composed of multiple electronic units.

[0069] The controller 10A is connected to the GNSS receiver 21, the surrounding conditions sensor 22, the driving information sensor 23, the map database 24, and the toggle switch 25.

[0070] The GNSS receiver 21 determines the location (e.g., latitude and longitude) of the industrial vehicle 1A on a map by receiving signals from three or more GNSS satellites. The GNSS receiver 21 then transmits the determined location information of the industrial vehicle 1A to the controller 10A.

[0071] The surrounding environment sensor 22 is an onboard detector for detecting the surrounding environment of the industrial vehicle 1A. The surrounding environment sensor 22 includes a camera and a LiDAR (Light Detection and Ranging) system. Camera image information is used, for example, for road pattern recognition and matching. Obstacle information detected by the LiDAR is used, for example, to help the industrial vehicle 1A avoid hazards. The surrounding environment sensor 22 sends information related to the surrounding environment of the industrial vehicle 1A to the controller 10A.

[0072] The driving information sensor 23 is a detector that monitors the driving status of the industrial vehicle 1A. The driving information sensor 23 includes a vehicle speed sensor, an acceleration sensor, and a yaw rate sensor (gyroscope sensor). The vehicle speed sensor detects the speed of the industrial vehicle 1A. For example, a speed sensor is used that is installed on both the left drive motor 6 and the right drive motor 7 and detects the rotational speed of the left drive motor 6 and the right drive motor 7, respectively. The driving information sensor 23 sends the detected driving information to the controller 10A.

[0073] Map database 24 is a database that stores map information. Map database 24 is formed, for example, within a storage device (e.g., an HDD) mounted on industrial vehicle 1A. The map information includes road location information, road shape information (e.g., types of curves and straight sections, curvature of curves), location information of intersections and branch points, and location information of structures, including information on designated areas such as runways, takeoff and landing areas, taxiways, aprons, control towers, hangars, cargo loading and unloading areas, and charging stations in an airport. The map information also includes location information of road surface patterns used for location identification of industrial vehicle 1A. Furthermore, map database 24 may be formed on a server that can communicate with industrial vehicle 1A.

[0074] The switch 25 is used to switch between executing and not executing autonomous driving control. Depending on its operating position, the switch 25 can be set to either the executing or non-executing state of autonomous driving control. The switch 25 outputs a signal corresponding to its state to the controller 10A.

[0075] Next, the functional configuration of the controller 10A will be described. The controller 10A includes: a map information acquisition unit 11, a location information acquisition unit 12, a driving information acquisition unit 13, an automatic driving control unit 14, and a steering hydraulic pressure control unit 15A. In addition, some of the functions of the controller 10A described below can be executed in a server capable of communicating with the industrial vehicle 1A.

[0076] The map information acquisition unit 11 acquires map information stored in the map database 24. For example, the map information acquisition unit 11 acquires the location information of the road surface pattern used for location identification of the industrial vehicle 1A.

[0077] The location information acquisition unit 12 acquires the location information of the industrial vehicle 1A based on the reception results of the GNSS receiver 21, the detection results of the surrounding condition sensor 22, and the map information of the map database 24. The location information acquisition unit 12 acquires the self-position of the industrial vehicle 1A based on the location information of the road surface pattern contained in the map information and the relative position information of the road surface pattern detected by the surrounding condition sensor 22 relative to the industrial vehicle 1A. Alternatively, the location information acquisition unit 12 can use, for example, a SLAM (Simultaneous Localization and Mapping) method to estimate the self-position of the industrial vehicle 1A.

[0078] The driving information acquisition unit 13 acquires the driving information of the industrial vehicle 1A based on the detection results of the driving information sensor 23. Here, the driving information acquisition unit 13 acquires the vehicle speed information of the industrial vehicle 1A based on the detection results of the speed sensors installed in the left drive motor 6 and the right drive motor 7. The driving information acquisition unit 13 can also acquire the direction of the industrial vehicle 1A based on the detection results of the gyroscope sensor.

[0079] The automatic driving control unit 14 executes automatic driving control of the industrial vehicle 1A, including automatic steering, based on location information, driving information, map information, and the state of the switch 25. The automatic driving control unit 14 generates a driving plan along a target route based on the location information of the industrial vehicle 1A measured by the GNSS receiver 21, the map information from the map database 24, the surrounding conditions of the industrial vehicle 1A identified by the detection results of the surrounding condition sensor 22 (position of obstacles, etc.), and the driving status identified by the detection results of the driving information sensor 23 (vehicle speed, yaw rate, etc.). The target route is set according to the transport instructions from the operation management system. The driving plan may include, for example, the target cut-off angles of the FL tire 2 and the FR tire 3. The driving plan may also include a target speed.

[0080] The automatic driving control unit 14 executes automatic driving according to the driving plan. When a signal corresponding to the execution state of automatic driving control is input from the switch 25, the automatic driving control unit 14 executes automatic driving control, generates the driving plan, and calculates whether automatic steering is required based on the driving plan. When a signal indicating non-execution of automatic driving control is input from the switch 25, the automatic driving control unit 14 does not execute automatic driving control (non-execution of automatic driving control). The automatic driving control unit 14 can execute automatic driving control to achieve the target speed by sending control signals to the left drive unit 6a and the right drive unit 7a.

[0081] The steering hydraulic pressure control unit 15A controls the opening and closing of the electromagnetic proportional valve 51 based on the calculation results of the automatic driving control performed by the automatic driving control unit 14. The steering hydraulic pressure control unit 15A sends a command signal to the contactor 9 and the electromagnetic proportional valve 51 based on the calculation results of whether automatic steering is required performed by the automatic driving control unit 14 (automatic driving control calculation results). When automatic driving control is being executed and the calculation results indicate automatic steering, the steering hydraulic pressure control unit 15A controls the opening and closing of the electromagnetic proportional valve 51 with the cut angle of the FL tire 2 and the FR tire 3 as the target cut angle for automatic steering. The electromagnetic proportional valve 51 is controlled to be closed, for example, when automatic driving control is being executed and the calculation results indicate automatic steering is not being performed, or when automatic driving control is not being executed. The steering hydraulic pressure control unit 15A can, for example, obtain the cut angle of the FL tire 2 and the FR tire 3 based on a tire cut angle sensor (not shown).

[0082] [Regarding the flow splitting structure of the priority valve]

[0083] The flow diversion of priority valve 60 will be explained in detail. Figure 5 and Figure 6 It is along Figure 1 A schematic cross-sectional view of the axis of the priority valve. (See attached image.) Figure 5 and Figure 6 As shown, the priority valve 60 has: a valve support chamber 62 formed in the housing 61; a valve body 63 slidably disposed along the inner wall of the valve support chamber 62; and a spring 64 disposed between the inner wall of the valve support chamber 62 and the valve body 63, and pushes the valve body 63 in one direction.

[0084] The valve support chamber 62 is formed as a generally cylindrical cavity. The valve support chamber 62 has: an opening for the hydraulic pump circuit 30a, i.e., a hydraulic pump side opening 62a; an opening for the inlet circuit 40a of the forward manual steering circuit 40, i.e., a manual steering side opening 62b; and an opening for the inlet circuit 50a of the forward automatic steering circuit 50, i.e., an automatic steering side opening 62c.

[0085] The valve body 63 is slidably disposed along the inner wall of the valve support chamber 62, between the hydraulic pump-side opening 62a and the manual steering-side opening 62b. The valve body 63 divides the valve support chamber 62 into a hydraulic pump-side back pressure chamber 65, where the hydraulic pump-side opening 62a is located, and a manual steering-side back pressure chamber 66, where the manual steering-side opening 62b is located. The manual steering-side back pressure chamber 66 is the back pressure chamber of the valve body 63 located on the side of the inlet circuit 40a. A circuit 30f, branching from the hydraulic pump circuit 30a, is connected to the hydraulic pump-side back pressure chamber 65, supplying hydraulic oil from the hydraulic pump 31. That is, the oil pressure in the hydraulic pump-side back pressure chamber 65 is the same as the oil pressure in the hydraulic pump circuit 30a.

[0086] The priority valve 60 here is configured as a priority valve that prioritizes the PS valve 41 side as the priority circuit. The priority valve 60 supplies hydraulic oil to the manual steering circuit 40 preferentially at a design flow rate (first flow rate). The design flow rate is a design value for the flow rate of hydraulic oil supplied preferentially to the manual steering circuit 40, set to a certain flow rate value, for example, above a specified flow rate. The specified flow rate means the minimum hydraulic oil supply flow rate required to operate the steering cylinder 32 in order to steer the FL tire 2 and FR tire 3. That is, by preferentially supplying hydraulic oil to the manual steering circuit 40 at a design flow rate above the specified flow rate, the priority valve 60 enables the steering cylinder 32 to operate regardless of whether hydraulic oil is diverted to the automatic steering circuit 50.

[0087] The priority valve 60 has a throttle orifice 67, which is configured according to the design flow rate preferentially supplied to the PS valve 41 side. The throttle orifice 67 is formed in the valve body 63. The throttle orifice 67 communicates the hydraulic pump-side back pressure chamber 65 with the manual steering-side back pressure chamber 66. In the priority valve 60, the manual steering-side opening 62b is formed on the opposite side of the throttle orifice 67 from the hydraulic pump-side back pressure chamber 65. Therefore, hydraulic oil flowing into the hydraulic pump-side back pressure chamber 65 from the hydraulic pump circuit 30a is guided to the manual steering-side back pressure chamber 66 through the throttle orifice 67.

[0088] The flow rate of hydraulic oil through the throttle orifice 67 is determined by the pressure difference of the hydraulic oil before and after the throttle orifice 67 and the flow path area of ​​the forward manual steering side opening 62b in the manual steering side back pressure chamber 66. In the priority valve 60 of this embodiment, the flow path area of ​​the forward manual steering side opening 62b in the manual steering side back pressure chamber 66 is designed such that even if the pressure difference of the hydraulic oil before and after the throttle orifice 67 changes, the flow rate of hydraulic oil through the throttle orifice 67 remains approximately constant. In the following description, the connection opening D1 is used as an indicator of the flow path area of ​​the forward manual steering side opening 62b in the manual steering side back pressure chamber 66. The connection opening D1 is the axial dimension along the valve support chamber 62 of the manual steering side connecting flow path 68 that guides hydraulic oil from the manual steering side back pressure chamber 66 to the inlet circuit 40a.

[0089] When the flow rate of hydraulic oil from the hydraulic pump circuit 30a to the priority valve 60 exceeds the design flow rate, the priority valve 60 supplies the remaining hydraulic oil to the automatic steering circuit 50 on the electromagnetic proportional valve 51 side. In the priority valve 60, the automatic steering side opening 62c is formed to be located on the same side as the hydraulic pump side back pressure chamber 65 relative to the throttle orifice 67. Therefore, the flow rate of hydraulic oil in the forward automatic steering circuit 50 is mainly determined by the flow path area of ​​the forward automatic steering side opening 62c in the hydraulic pump side back pressure chamber 65. In the following description, the connection opening D2 is used as an indicator of the flow path area of ​​the forward automatic steering side opening 62c in the hydraulic pump side back pressure chamber 65. The connection opening D2 is the axial dimension along the valve support chamber 62 of the automatic steering side connecting flow path 69 that guides hydraulic oil from the hydraulic pump side back pressure chamber 65 to the inlet circuit 50a.

[0090] The priority valve 60 is configured such that the opening degrees D2 and D1 change as the valve body 63 moves along the inner wall of the valve support chamber 62. Specifically, the valve body 63 is configured to move in the direction of the spring 64 pushing the valve body 63, thereby decreasing the opening degree D2 of the automatic steering side flow path 69 and increasing the opening degree D1 of the manual steering side flow path 68.

[0091] Here, the hydraulic pump 31 maintains the flow rate of hydraulic oil in the hydraulic pump circuit 30a even when at least one of the opening / closing states of the PS valve 41 (manual steering) and the electromagnetic proportional valve 51 (automatic steering) changes, and the speed of the hydraulic pump 31 is controlled by the steering hydraulic pressure control unit 15A of the controller 10A. When at least one of the opening / closing states of the PS valve 41 (manual steering) and the electromagnetic proportional valve 51 (automatic steering) changes to open, a pressure loss occurs when hydraulic oil flows to at least one of the manual steering circuit 40 and the automatic steering circuit 50. Because this pressure loss is overcome to pump hydraulic oil, if the flow rate of hydraulic oil in the hydraulic pump circuit 30a is to be maintained and the speed of the hydraulic pump 31 is increased, the oil pressure in the hydraulic pump circuit 30a and the hydraulic pump-side back pressure chamber 65 increases. Due to the increase in oil pressure, the valve body 63 moves toward the manual steering side back pressure chamber 66 by the spring thrust formed by the oil pressure in the oil pressure pump side back pressure chamber 65.

[0092] For example, Figure 5 This is equivalent to a state where neither manual nor automatic steering is performed, and both PS valve 41 and electromagnetic proportional valve 51 are closed. Examples of such a state include: when automatic driving control is being executed and the result of automatic driving control calculations without automatic steering is obtained, and no operation of steering wheel 33 is performed; or when automatic driving control is not being executed and no operation of steering wheel 33 is performed.

[0093] exist Figure 5 In this example, since PS valve 41 is closed, no hydraulic oil flows through PS valve 41 in the manual steering circuit 40, and no pressure loss occurs associated with the hydraulic oil flow. Similarly, since solenoid proportional valve 51 is closed, no hydraulic oil flows through solenoid proportional valve 51 in the automatic steering circuit 50, and no pressure loss occurs associated with the hydraulic oil flow. In this case, since the oil pressure in the hydraulic pump circuit 30a and the hydraulic pump side back pressure chamber 65 does not increase due to pressure loss, no spring force generated by the oil pressure in the hydraulic pump side back pressure chamber 65 is generated in the valve body 63. Therefore, the valve body 63 does not move towards the manual steering side back pressure chamber 66, but is only pushed by the spring force of spring 64 in the direction from the manual steering side back pressure chamber 66 to the hydraulic pump side back pressure chamber 65.

[0094] In this state, since the valve body 63 moves in a balanced manner from the spring thrust from both sides of the valve body 63, the oil pressure in the hydraulic pump side back pressure chamber 65 is the pressure balanced with the spring thrust of the spring 64. The pressure difference between the oil pressure in the hydraulic pump side back pressure chamber 65 and the oil pressure in the manual steering side back pressure chamber 66 is a predetermined pressure difference corresponding to the spring thrust of the spring 64. The flow rate of hydraulic oil through the throttle orifice 67 is the flow rate corresponding to the predetermined pressure difference corresponding to the spring thrust of the spring 64. At this time, since the connection opening D1 is sufficiently large, the flow rate of hydraulic oil through the throttle orifice 67 is equivalent to the design flow rate supplied to the manual steering circuit 40. In addition, in Figure 5 In the example, the priority valve 60 is configured such that the supply of hydraulic oil to the electromagnetic proportional valve 51 on the automatic steering circuit 50 side is never completely cut off.

[0095] Figure 6 This is equivalent to further engaging manual steering even when automatic steering is not in progress, with both PS valve 41 and electromagnetic proportional valve 51 open. An example of such a state is when automatic steering is being executed, the result of automatic steering control calculations, and there is operation of the steering wheel 33.

[0096] exist Figure 6 In the example, because the solenoid proportional valve 51 is open, no hydraulic oil flows through the solenoid proportional valve 51 in the automatic steering circuit 50, resulting in a pressure loss associated with the hydraulic oil flow. Similarly, because the PS valve 41 is open, hydraulic oil flows through the PS valve 41 in the manual steering circuit 40, resulting in a pressure loss associated with the hydraulic oil flow. Therefore, the oil pressure in the hydraulic pump circuit 30a and the hydraulic pump side back pressure chamber 65 increases due to the pressure loss, generating a spring-like thrust in the valve body 63 caused by the oil pressure in the hydraulic pump side back pressure chamber 65. Consequently, the valve body 63 moves towards the manual steering side back pressure chamber 66 by the spring-like thrust caused by the oil pressure in the hydraulic pump side back pressure chamber 65, and the opening degree D1 of the manual steering side connecting flow path 68 decreases.

[0097] In this state, the pressure difference between the oil pressure in the hydraulic pump side back pressure chamber 65 and the oil pressure in the manual steering side back pressure chamber 66 is greater than [the pressure difference is missing from the original text]. Figure 5 In the example, the pressure difference, in addition to the spring force of spring 64, increases by the amount corresponding to the pressure loss. Because the pressure difference increases, the flow rate of hydraulic oil through the throttle orifice 67 may be greater than [a certain value]. Figure 5 The flow rate of the example. However, since the connectivity openness D1 is less than... Figure 5 For example, the flow rate of hydraulic oil supplied to the manual steering circuit 40 is therefore... Figure 5 The same applies to the design flow rate. The amount of hydraulic pump 31 that exceeds the design flow rate is supplied as surplus flow to the automatic steering circuit 50 side.

[0098] Furthermore, when either PS valve 41 or solenoid proportional valve 51 is opened, the position of valve body 63 is, for example... Figure 5 and Figure 6 The intermediate state is one in which the sum of the spring thrust generated by the hydraulic pressure of the manual steering side back pressure chamber 66 and the spring thrust generated by the spring 64 is balanced with the spring thrust generated by the hydraulic pressure of the hydraulic pump side back pressure chamber 65. Examples of such states include: when automatic driving control is being executed and the calculation result of automatic driving control for automatic steering is obtained, and there is no operation of the steering wheel 33; or when automatic driving control is not being executed and there is operation of the steering wheel 33.

[0099] With the priority valve 60 configured as described above, even when the electromagnetic proportional valve 51 is open according to the calculation results of the automatic driving control, at least the designed flow rate of hydraulic oil is supplied to the manual steering circuit 40. Therefore, the steering cylinder 32 can operate according to the operation of the steering wheel 33. Thus, when automatic driving control is in operation and automatic steering is being performed, in situations such as the appearance of an unexpected obstacle requiring avoidance, the steering cylinder 32 operates according to the operation of the steering wheel 33 by the operator. Therefore, even during automatic steering, obstacle avoidance can be achieved through manual steering.

[0100] Furthermore, in the priority valve 60 as described, the excess hydraulic oil flowing in the manual steering circuit 40, exceeding the design flow rate, is supplied to the automatic steering circuit 50. If the solenoid proportional valve 51 is closed in the automatic steering circuit 50, then no hydraulic oil flows through the solenoid proportional valve 51 in the automatic steering circuit 50. Here, assuming that the excess hydraulic oil supplied to the automatic steering circuit 50 does not return to the oil tank 34, the hydraulic oil remains in the automatic steering circuit 50, resulting in a high pressure (pilot pressure) of the hydraulic oil from the hydraulic pump 31 acting on the solenoid proportional valve 51. As a result, the driving energy (here, electricity) of the hydraulic pump 31 becomes excessive, and thus the operating time of the steering device 100A of the industrial vehicle may be shortened.

[0101] Therefore, in the steering system 100A of the industrial vehicle, the steering hydraulic pressure control unit 15A determines whether the automatic steering non-operation conditions are met. The unloading valve 52 is configured to reduce the pressure of the hydraulic oil acting on the solenoid proportional valve 51 based on the determination result of the steering hydraulic pressure control unit 15A. When the steering hydraulic pressure control unit 15A determines that the automatic steering non-operation conditions are met, it controls the unloading valve 52 in a manner that reduces the pressure of the hydraulic oil acting on the solenoid proportional valve 51. That is, the controller 10A and the unloading valve 52 constitute an unloading mechanism that reduces the pressure of the hydraulic oil from the hydraulic pump 31 acting on the solenoid proportional valve 51.

[0102] The automatic steering non-operating condition is a specified condition used to determine whether to suspend the supply of hydraulic oil through the solenoid proportional valve 51. The automatic steering non-operating condition can be set based on information related to the execution or non-execution of automatic driving control, or the vehicle speed information of the industrial vehicle 1A.

[0103] More specifically, the steering hydraulic control unit 15A can determine that the automatic steering non-working condition is met based on the signal from the switch 25 when the state of the switch 25 is the non-executing state of automatic driving control.

[0104] Alternatively, the steering hydraulic control unit 15A determines, based on the vehicle speed information of the industrial vehicle 1A, whether the industrial vehicle 1A has been continuously stopped for a predetermined time. If it is determined that the industrial vehicle 1A has been continuously stopped for a predetermined time, it can be determined that the automatic steering non-operating conditions are met. The steering hydraulic control unit 15A determines that the industrial vehicle 1A has been continuously stopped for a predetermined time if the vehicle speed of the industrial vehicle 1A has been below a predetermined stopping speed threshold for a predetermined time. The stopping speed threshold and the predetermined time are not particularly limited; a situation where the industrial vehicle 1A is parked in a stopped state can be envisioned, for example, set to a speed of several km / h and a duration of approximately several minutes.

[0105] The automatic steering non-operating condition is not limited to the specific example described. For example, the automatic steering non-operating condition may be determined to be met when the steering hydraulic control unit 15A malfunctions in any of the components used to perform automatic driving (e.g., GNSS receiver 21, surrounding condition sensor 22, driving information sensor 23, map database 24, and switch 25).

[0106] Based on the above unloading mechanism, when the automatic steering non-working conditions are met, the pressure of the hydraulic oil from the oil pump 31 acting on the electromagnetic proportional valve 51 can be reduced compared to the case where the automatic steering non-working conditions are not met.

[0107] [An example of computational processing performed by the controller]

[0108] Next, an example of the computational processing performed by the controller 10A will be explained. Figure 7 This is an example Figure 1 The flowchart shows the unloading process of the controller. Figure 7 The process shown is performed, for example, when the main power supply of the industrial vehicle 1A is turned on, enabling the power supply to the hydraulic pump 31.

[0109] like Figure 7 As shown, in S01, controller 10A, through steering hydraulic control unit 15A, determines whether the automatic steering non-operating conditions are met. Specifically, controller 10A, as part of the processing in S01, performs... Figure 8The example illustrates the determination and processing of non-operating automatic steering conditions.

[0110] Figure 8 This is an example Figure 7 The flowchart shows the process for determining and handling non-operating conditions during automatic steering. (Example:) Figure 8 As shown, in S11, the controller 10A receives signals from the switch 25 via the steering hydraulic pressure control unit 15A. The steering hydraulic pressure control unit 15A receives signals from the switch 25 corresponding to the state of the switch 25.

[0111] In S12, the controller 10A determines whether the automatic driving control is in a non-executing state by means of the steering hydraulic pressure control unit 15A. For example, based on the signal from the switch 25, the controller 10A determines that the automatic driving control is in a non-executing state when the switch 25 is in a non-executing state.

[0112] When the switch 25 is in the non-execution state of automatic driving control (S12 = Yes), controller 10A moves to S16 as described below. When the switch 25 is in the execution state of automatic driving control (S12 = No), controller 10A moves to S13.

[0113] In S13, the controller 10A acquires vehicle speed information through the driving information acquisition unit 13. The driving information acquisition unit 13 acquires the vehicle speed information of the industrial vehicle 1A based on the detection results of the driving information sensor 23 (e.g., the rotational speed of the left driving motor 6 and the rotational speed of the right driving motor 7).

[0114] In step S14, controller 10A, via steering hydraulic control unit 15A, determines whether industrial vehicle 1A has been continuously stopped for a predetermined time. For example, based on vehicle speed information, steering hydraulic control unit 15A determines that industrial vehicle 1A has been continuously stopped for a predetermined time if the vehicle speed of industrial vehicle 1A has been below a predetermined stopping speed threshold for a predetermined time. If steering hydraulic control unit 15A determines that industrial vehicle 1A has been continuously stopped for a predetermined time (S14 = Yes), it proceeds to step S16. If steering hydraulic control unit 15A determines that industrial vehicle 1A has not been continuously stopped for a predetermined time (S14 = No), it proceeds to step S15.

[0115] In S15, controller 10A determines, via steering hydraulic pressure control unit 15A, that the automatic steering non-operation condition has not been met. Conversely, in S16, controller 10A determines, via steering hydraulic pressure control unit 15A, that the automatic steering non-operation condition has been met. Then, controller 10A terminates. Figure 8 The processing was moved to Figure 7 SO2.

[0116] return Figure 7 If, in S02, the controller 10A determines through the steering hydraulic pressure control unit 15A that the automatic steering non-operating condition is met (S02 = Yes), it moves to S04 as described below. If, in S02, the controller 10A determines through the steering hydraulic pressure control unit 15A that the automatic steering non-operating condition is not met (S02 = No), it moves to S03.

[0117] In S03, the controller 10A, via the steering hydraulic pressure control unit 15A, sets the hydraulic pressure (pilot pressure) acting on the solenoid proportional valve 51 to a first pressure. The first pressure is the hydraulic pressure at which the remaining flow of hydraulic oil supplied to the automatic steering circuit 50 side is returned to the oil tank 34. In this embodiment, the steering hydraulic pressure control unit 15A, in S03, controls the hydraulic pressure acting on the solenoid proportional valve 51 without using the unloading valve 52 to reduce the hydraulic pressure (e.g., by closing the unloading valve 52). Therefore, the hydraulic pressure (pilot pressure) acting on the solenoid proportional valve 51 is the first pressure. Then, the controller 10A terminates. Figure 7 The controller 10A can repeat the process after a specified calculation cycle. Figure 7 The processing.

[0118] In S04, the controller 10A, via the steering hydraulic pressure control unit 15A, sets the hydraulic pressure (pilot pressure) acting on the solenoid proportional valve 51 to a second pressure, which is lower than the first pressure. The second pressure is the pressure of the hydraulic oil in the case where the remaining flow of hydraulic oil supplied to the automatic steering circuit 50 side is returned to the oil tank 34. In this embodiment, in S04, the steering hydraulic pressure control unit 15A controls the unloading valve 52 in a manner that reduces the pressure of the hydraulic oil acting on the solenoid proportional valve 51 compared to the case where the automatic steering non-operation condition is determined not to be met (S02 = No), for example, by opening the unloading valve 52. Therefore, the hydraulic pressure (pilot pressure) acting on the solenoid proportional valve 51 is the second pressure. Then, the controller 10A terminates. Figure 7 The controller 10A can repeat the process after a specified calculation cycle. Figure 7 The processing.

[0119] [Function and Effects of the First Embodiment]

[0120] In the steering system 100A of the industrial vehicle, hydraulic oil is diverted via a priority valve 60 to the manual steering circuit 40 and the automatic steering circuit 50, with a design flow rate exceeding the specified flow rate for operating the steering cylinder 32 being preferentially supplied to the manual steering circuit 40. Therefore, even when the electromagnetic proportional valve 51 is open according to the calculation results of automatic driving control, at least the specified flow rate of hydraulic oil is supplied to the manual steering circuit 40, allowing the steering cylinder 32 to operate according to the operation of the steering wheel 33. Thus, according to the steering system 100A of the industrial vehicle, the steering hydraulic circuit 30 can function, enabling manual steering even when automatic steering is possible.

[0121] Incidentally, as a comparative example, in a configuration where a locking valve, which operates based on an electrical signal, is used instead of a priority valve 60 to shunt the manual steering circuit 40 and the automatic steering circuit 50, and where a backup battery is used to send the electrical signal to the locking valve, if the backup battery fails, the locking valve cannot operate, and manual steering is impossible. In contrast, according to the steering system 100A of an industrial vehicle using a priority valve 60 as described in this invention, even without a backup battery, hydraulic oil of the designed flow rate can be mechanically supplied to the manual steering circuit 40, thus substantially mechanically connecting the steering wheel 33 and the PS valve 41. This avoids the inability to perform manual steering due to a power failure in the shunt circuit. Furthermore, since the configuration such as the backup battery power supply can be omitted, the increase in the number of parts can be suppressed.

[0122] The steering system 100A of the industrial vehicle also includes an unloading mechanism. This unloading mechanism reduces the pressure of the hydraulic oil from the hydraulic pump 31 acting on the electromagnetic proportional valve 51 when the prescribed automatic steering non-operating condition of suspending the supply of hydraulic oil through the electromagnetic proportional valve 51 is met, compared to the case where the automatic steering non-operating condition is not met. Therefore, if the priority valve 60 is configured such that the supply of hydraulic oil to the electromagnetic proportional valve 51 is never completely cut off, and if it is assumed that the remaining flow of hydraulic oil supplied to the automatic steering circuit 50 is not returned to the oil tank 34, then the pressure of the hydraulic oil from the hydraulic pump 31 will always act on the electromagnetic proportional valve 51, which would place an unnecessary load on the hydraulic pump 31. Therefore, by using the unloading mechanism, the pressure of the hydraulic oil from the hydraulic pump 31 acting on the electromagnetic proportional valve 51 is reduced when the automatic steering non-operating condition is met, thereby suppressing the unnecessary load on the hydraulic pump 31. As a result, the operating time of the steering system 100A of the industrial vehicle caused by the unnecessary load on the hydraulic pump 31 can be reduced. Furthermore, by reducing the load on the hydraulic pump 31, the hydraulic oil temperature is less likely to rise, for example, it is less likely to cause overheating of the hydraulic pump 31 and the hydraulic oil in high-temperature environments. In addition, a hydraulic pump 31 with lower heat resistance can be used.

[0123] In the steering system 100A of the industrial vehicle, the unloading mechanism includes: a controller 10A, which determines whether the automatic steering non-operation condition is met based on information related to the execution or non-execution of automatic driving control, or the vehicle speed information of the industrial vehicle 1A; and an unloading valve 52, configured to reduce the pressure of hydraulic oil from the hydraulic pump 31 acting on the solenoid proportional valve 51 based on the determination result of the controller 10A. When the controller 10A determines that the automatic steering non-operation condition is met, it controls the unloading valve 52 to reduce the pressure of hydraulic oil from the hydraulic pump 31 acting on the solenoid proportional valve 51. Thus, by controlling the unloading valve 52 based on the determination result of the controller 10A, the pressure of hydraulic oil from the hydraulic pump 31 acting on the solenoid proportional valve 51 can be reduced when the automatic steering non-operation condition is met.

[0124] In the steering system 100A of the industrial vehicle, the controller 10A determines that the automatic steering non-operation condition is met based on a signal from the switching switch 25, which is used to switch between executing and non-executing automatic driving control. When the state of the switching switch 25 is the non-executing state of automatic driving control, the controller 10A determines that the automatic steering non-operation condition is met. Thus, unnecessary load on the hydraulic pump 31 can be suppressed when automatic driving control is not executed and automatic steering is not performed.

[0125] In the steering device 100A of the industrial vehicle, the controller 10A determines whether the industrial vehicle 1A has been continuously stopped for a predetermined time based on the vehicle speed information. When it is determined that the industrial vehicle 1A has been continuously stopped for a predetermined time, it is determined that the automatic steering non-operation condition is met. Thus, unnecessary load on the hydraulic pump 31 can be suppressed when the industrial vehicle 1A has been continuously stopped for a predetermined time.

[0126] [Examples of variations of the first embodiment]

[0127] The first embodiment of the present invention has been described above, but the present invention is not limited to the first embodiment described herein.

[0128] The unloading mechanism is not limited to the unloading valve 52 and the controller 10A that controls the unloading valve 52 as described. For example, as a variation of the unloading mechanism, the controller 10A can control the rotational speed of the (fixed capacity) hydraulic pump 31 based on the determination result of the controller 10A. By reducing the rotational speed of the hydraulic pump 31 when the automatic steering non-operating conditions are met, the controller 10A can reduce the pressure of the hydraulic oil from the hydraulic pump 31 acting on the solenoid proportional valve 51.

[0129] Alternatively, as another variation of the unloading mechanism, the hydraulic pump 31 can be a variable-capacity pump configured to vary the amount of hydraulic oil injected during operation. When the controller 10A determines that the automatic steering non-operating conditions are met, it can control the variable-capacity pump by reducing the amount of hydraulic oil injected. In this case, the injection amount of the variable-capacity pump during operation is controlled based on the determination result of the controller 10A, and when the automatic steering non-operating conditions are met, the pressure of the hydraulic oil from the variable-capacity pump acting on the solenoid proportional valve 51 can be reduced.

[0130] In the first embodiment, the steering device 100A of the industrial vehicle includes an unloading mechanism, but the unloading mechanism may be omitted. In this case, such as Figure 5 For example, the priority valve 60 is configured such that the supply of hydraulic oil to the solenoid proportional valve 51 on the automatic steering circuit 50 side is never completely cut off, but a flow divider valve configured to be completely cut off can be used. By completely cutting off the supply of hydraulic oil to the solenoid proportional valve 51, compared with the case where it is not completely cut off, it is expected that the pressure (pilot pressure) of the hydraulic oil from the hydraulic pump 31 acting on the solenoid proportional valve 51 will be reduced.

[0131] [Second Implementation]

[0132] Figure 9 This is a schematic diagram of an industrial vehicle that uses the steering device of the industrial vehicle according to the second embodiment. Figure 10 It means Figure 9 A rough circuit diagram of the steering hydraulic circuit. Figure 11 It means Figure 9 A block diagram illustrating the functional structure of the steering system in an industrial vehicle.

[0133] Figure 9 The industrial vehicle 1B shown replaces the steering device 100A of the industrial vehicle with a steering device 100B. Figure 1 The industrial vehicle 1A shown is different. The industrial vehicle 1B is otherwise identical to the industrial vehicle 1A.

[0134] The steering device 100B of the industrial vehicle replaces the controller 10A with a controller (control unit) 10B, and replaces the switch 25 with a steering angle sensor (steering operation detection unit) 26. Figure 1 The steering system 100A of the industrial vehicle shown is different. The steering system 100B of the industrial vehicle is otherwise constructed identically to the steering system 100A of the industrial vehicle. The controller 10B is connected to the steering angle sensor 26.

[0135] Steering angle sensor 26 is a detector that detects the steering angle of steering wheel 33. Steering angle sensor 26 is, for example, installed on the shaft of steering wheel 33. Steering angle sensor 26 sends the detected steering angle information to controller 10B. Steering angle sensor 26 constitutes a steering operation detection unit for detecting the operation of steering wheel 33.

[0136] In the second embodiment, the operation of the unloading valve 52 is controlled by the controller 10B. For example, in addition to the functions of the steering hydraulic control unit 15A, the steering hydraulic pressure control unit 15B also detects the operation of the steering wheel 33 based on the detection results of the steering angle sensor 26. That is, the steering hydraulic pressure control unit 15B and the steering angle sensor 26 together function as a steering operation detection unit. The function of the steering operation detection unit will be described in detail below.

[0137] As described above, the priority valve 60 is configured as a priority valve with the PS valve 41 side as the priority circuit. The priority valve 60 prioritizes supplying hydraulic oil to the manual steering circuit 40 at a design flow rate (first flow rate). When the flow rate of hydraulic oil from the hydraulic pump circuit 30a to the priority valve 60 exceeds the design flow rate, the priority valve 60 supplies the remaining hydraulic oil to the automatic steering circuit 50 on the solenoid proportional valve 51 side. That is, the priority valve 60 prioritizes supplying hydraulic oil to the manual steering circuit 40 at a first flow rate, which is above the predetermined flow rate of the hydraulic oil ejected from the hydraulic pump 31 that operates the steering cylinder 32, and supplies hydraulic oil to the automatic steering circuit 50 at the remaining flow rate of the hydraulic oil ejected from the hydraulic pump 31 other than the first flow rate, i.e., the second flow rate.

[0138] However, in the priority valve 60 as described, the hydraulic oil ejected from the hydraulic pump 31, excluding the design flow rate (first flow rate) flowing to the manual steering circuit 40, i.e., the second flow rate, is supplied to the automatic steering circuit 50. Here, if we assume, for example, that the second flow rate of hydraulic oil is supplied to the steering cylinder 32 through the automatic steering circuit 50 regardless of whether the steering wheel 33 is operated, then both the hydraulic oil flowing in the manual steering circuit 40 and the hydraulic oil flowing in the automatic steering circuit 50 may be supplied to the steering cylinder 32 simultaneously. Therefore, when the steering wheel 33 is operated, the hydraulic oil supplied to the automatic steering circuit 50 may affect the operation of the steering cylinder 32 corresponding to the steering wheel 33 operation. In particular, when the steering wheel 33 is operated at a slower speed, a residual flow rate towards the automatic steering circuit 50 is more likely to occur, and therefore, the impact on the operation of the steering cylinder 32 corresponding to the steering wheel 33 operation may be greater compared to when the steering wheel 33 is operated at a faster speed.

[0139] Specifically, regarding the impact on the operation of the steering cylinder 32, for example, if hydraulic oil continuously flowing in the automatic steering circuit 50 and the manual steering circuit 40 are supplied to the steering cylinder 32 in the same steering direction, it is possible to turn the steering wheel more than the operation of the steering wheel 33. Conversely, if hydraulic oil continuously flowing in the automatic steering circuit 50 and the manual steering circuit 40 are supplied to the steering cylinder 32 in opposite steering directions, it is possible to hinder the steering wheel turning achieved by the operation of the steering wheel 33, resulting in a deterioration in the response of the operation (deterioration in efficiency).

[0140] Therefore, the steering device 100B of the industrial vehicle includes a supply limiting mechanism that restricts the supply of hydraulic oil to the steering cylinder 32 through the automatic steering circuit 50 when the steering hydraulic pressure control unit 15B detects operation of the steering wheel 33. "The steering hydraulic pressure control unit 15B detects operation of the steering wheel 33" corresponds to a situation where the hydraulic oil supplied to the automatic steering circuit 50 easily affects the operation of the steering cylinder 32 corresponding to the operation of the steering wheel 33.

[0141] The steering hydraulic pressure control unit 15B detects the operation of the steering wheel 33 based on the detection results of the steering angle sensor 26. In this invention, the operation of the steering wheel 33 is a predetermined operation performed by the operator of the industrial vehicle 1B. Predetermined operation means that the operation of the steering cylinder 32, which is achieved by the hydraulic oil continuously flowing in the manual steering circuit 40, is easily affected by the hydraulic oil continuously flowing in the automatic steering circuit 50. Furthermore, the detection of the steering wheel 33 operation performed by the steering hydraulic pressure control unit 15B can be used as a condition for the execution of automatic driving control.

[0142] As a predefined operation, consider the steering wheel 33 operation performed by the operator at a steering speed that is significantly slower than a certain threshold. The steering hydraulic control unit 15B, for example, detects the predefined operation when the steering speed of the steering wheel 33 is below a predefined steering speed threshold, based on the time change in steering angle (rotation speed) detected by the steering angle sensor 26. The steering speed threshold is a threshold used to determine whether the steering wheel 33 operation performed by the operator constitutes a predefined operation. The steering speed threshold can be preset, for example, taking into account the remaining flow rate in the forward automatic steering circuit 50. The lower the steering speed of the steering wheel 33, the less of the design flow rate from the priority valve 60 to the PS valve 41 is supplied to the steering cylinder 32 through the manual steering circuit 40, thus increasing the remaining flow rate. Therefore, the steering speed threshold can be defined as the steering speed of the steering wheel 33 when the remaining flow rate is a certain amount (e.g., half the design flow rate).

[0143] As a standard operating procedure, for example, consider the operation of the steering wheel 33 by the operator when the steering direction of the manual steering wheel is inconsistent with the direction of automatic steering. When the steering direction of the manual steering wheel is inconsistent with the direction of automatic steering, if hydraulic oil is supplied to the steering cylinder 32 via the automatic steering circuit 50, it is more likely to hinder steering achieved by the operation of the steering wheel 33 compared to the case where the steering direction is consistent with the direction of automatic steering. Therefore, the steering hydraulic pressure control unit 15B can, for example, detect the standard operating procedure when the steering direction of the manual steering wheel is inconsistent with the direction of automatic steering based on the time change of the steering angle (rotation direction) detected by the steering angle sensor 26.

[0144] As a restriction implemented by the supply limiting mechanism, for example, when the steering oil pressure control unit 15B detects operation of the steering wheel 33, the controller 10B controls the solenoid proportional valve 51 to prevent the supply of hydraulic oil from the oil pressure pump 31 to the steering cylinder 32 through the solenoid proportional valve 51 (for example, by setting the valve column 53 to neutral). This suppresses the supply of hydraulic oil to the steering cylinder 32 through the automatic steering circuit 50. In other words, the controller 10B and the solenoid proportional valve 51 constitute a supply limiting mechanism that restricts the supply of hydraulic oil to the steering cylinder 32 through the automatic steering circuit 50 when the steering oil pressure control unit 15B detects operation of the steering wheel 33.

[0145] As another restriction implemented by the supply limiting mechanism, the unloading valve 52 of the electromagnetic proportional valve 51 is configured to reduce the pressure of the hydraulic oil in the automatic steering circuit 50. Therefore, the controller 10B can control the unloading valve 52 to return the hydraulic oil to the oil tank 34 via the return circuit 30d when a specified operation of the steering wheel 33 is detected. This reduces the pressure of the hydraulic oil in the automatic steering circuit 50, suppressing the supply of hydraulic oil to the steering cylinder 32 through the automatic steering circuit 50. In this case, the controller 10B and the unloading valve 52 constitute a supply limiting mechanism that restricts the supply of hydraulic oil to the steering cylinder 32 through the automatic steering circuit 50 when the steering oil pressure control unit 15B detects an operation of the steering wheel 33.

[0146] Regarding the restrictive actions implemented by the restrictive agency, refer to... Figure 12 and Figure 13 While explaining. Figure 12 This is a timing diagram showing the flow rate of hydraulic oil in the forward steering cylinder when the restriction is not applied by the limiting mechanism. Figure 12 This corresponds to the situation where manual steering is also performed during automatic steering. Figure 12 In the diagram, the horizontal axis represents time, and the vertical axis represents the flow rate of hydraulic oil.

[0147] exist Figure 12 In the example, flow rate Qa1 represents the flow rate of hydraulic oil supplied to the steering cylinder 32 via the automatic steering circuit 50 without any restriction implemented by the limiting mechanism. Flow rate Qm represents the flow rate of hydraulic oil supplied to the steering cylinder 32 via the manual steering circuit 40 according to the operation of the steering wheel 33. Furthermore, for the sake of simplicity, it is assumed that flow rates Qa1 and Qm are small compared to the injection volume of the hydraulic pump 31, and can be increased to a predetermined flow rate Qp to operate the steering cylinder 32.

[0148] exist Figure 12 In the automatic steering control calculation, based on the results, automatic steering is initiated before time t0, and the electromagnetic proportional valve 51 is open. Therefore, hydraulic oil with a flow rate Qa1 equal to the specified flow rate Qp is supplied to the steering cylinder 32 via the automatic steering circuit 50. On the other hand, since the operator begins operating the steering wheel 33 before time t0, the PS valve 41 is closed. The hydraulic oil supplied to the manual steering circuit 40 at the designed flow rate returns to the oil tank 34 via the return circuit 30e, so the flow rate Qm before time t0 is 0.

[0149] At time t0, the operator begins to operate the steering wheel 33, further opening the PS valve 41 while the electromagnetic proportional valve 51 is already open. After time t0, corresponding to the opening of the PS valve 41, hydraulic oil is supplied to the manual steering circuit 40 side, increasing the flow rate Qm.

[0150] exist Figure 12 In this example, even if the operator begins operating the steering wheel 33 at time t0, hydraulic oil is continuously supplied to the steering cylinder 32 via the automatic steering circuit 50 at a flow rate Qa1 after time t0. Therefore, there is a risk that the hydraulic oil supplied to the steering cylinder 32 via the automatic steering circuit 50 may affect the operation of the steering cylinder 32 corresponding to the operation of the steering wheel 33. For example, during the period from time t0 to t1, when the flow rate Qm is approximately half or less of the flow rate Qa, the steering cylinder 32 may easily operate according to automatic steering rather than manual steering. In this case, it hinders the steering of the steering wheel achieved by the operation of the steering wheel 33, resulting in a deterioration in the response of the operation (increased efficiency).

[0151] Figure 13 This is a timing diagram showing the flow rate of hydraulic oil in the forward steering cylinder when restrictions are imposed by the supply limiting mechanism. Figure 13 In the example, flow rate Qa2 represents the flow rate of hydraulic oil supplied to the steering cylinder 32 via the automatic steering circuit 50 when the supply is restricted by the supply limiting mechanism. Flow rate Qa2 and other parameters... Figure 12same.

[0152] exist Figure 13 In the process of automatic steering, based on the calculation results of the automatic driving control, automatic steering is initiated before time t0, and the electromagnetic proportional valve 51 is in an open state. However, at time t0, the operator begins to operate the steering wheel 33, thereby imposing a restriction by the supply limiting mechanism. As a result, since hydraulic oil is not supplied to the steering cylinder 32 through the automatic steering circuit 50, the flow rate Qa2 is 0. Therefore, it is possible to prevent the operation of the steering cylinder 32 corresponding to the operation of the steering wheel 33 from being hindered by the hydraulic oil supplied through the automatic steering circuit 50.

[0153] [An example of computational processing performed by the controller]

[0154] Next, an example of the computational processing performed by the controller 10B will be described. Figure 14 This is an example Figure 9 The flowchart shows the supply constraint handling process for the controller. Figure 14 The processing shown is performed during the execution of automatic driving control in, for example, an industrial vehicle 1B. For example, automatic steering, achieved by automatic driving control, is performed when the valve stem 53 of the electromagnetic proportional valve 51 is in a position other than neutral.

[0155] like Figure 14 As shown, in S21, the controller 10B detects the operation of the steering wheel 33 via the steering hydraulic control unit 15B. Specifically, the controller 10B performs the processing in S21... Figure 15 The illustrated steering operation detection process.

[0156] Figure 15 This is an example Figure 14 The flowchart for steering operation detection and processing. (Example) Figure 15 As shown, in S31, the controller 10B detects the steering speed of the steering wheel 33 via the steering hydraulic pressure control unit 15B. The steering hydraulic pressure control unit 15B detects the steering speed of the steering wheel 33 based on the steering angle detected by the steering angle sensor 26.

[0157] In step S32, controller 10B, via steering hydraulic control unit 15B, determines whether the steering speed of steering wheel 33 is below a predetermined steering speed threshold (rotation speed threshold). If the steering speed of steering wheel 33 is below the steering speed threshold (S32 = Yes), controller 10B moves to step S33. In step S33, controller 10B, via steering hydraulic control unit 15B, determines whether the prescribed operation of steering wheel 33 has been detected. Then, controller 10B terminates. Figure 15 The processing was moved to Figure 14 S22.

[0158] On the other hand, when the steering speed of the steering wheel 33 exceeds the steering speed threshold (S32 = No), the controller 10B moves to S34. In S34, the controller 10B, through the steering hydraulic pressure control unit 15B, determines whether the prescribed operation of the steering wheel 33 has not been detected. Then, the controller 10B ends. Figure 15 The processing was moved to Figure 14 S22.

[0159] return Figure 14 If, in S22, the controller 10B determines, through the steering hydraulic pressure control unit 15B, that there is an operation of the steering wheel 33 (the specified operation described here) (S22 = Yes), it moves to S23. If, in S22, the controller 10B determines, through the steering hydraulic pressure control unit 15B, that there is no operation of the steering wheel 33 (S22 = No), it moves to S24.

[0160] In S23, the controller 10B, through the steering hydraulic pressure control unit 15B, restricts the supply of hydraulic oil to the steering cylinder 32 via the automatic steering circuit 50. In S23, the steering hydraulic pressure control unit 15B controls the solenoid proportional valve 51 in a manner that prevents hydraulic oil from the hydraulic pump 31 from being supplied to the steering cylinder 32 via the solenoid proportional valve 51 (for example, by setting the valve stem 53 to neutral). Alternatively, in S23, the steering hydraulic pressure control unit 15B controls the unloading valve 52 in a manner that reduces the pressure of the hydraulic oil in the automatic steering circuit 50 (for example, by opening the unloading valve 52). This restricts the supply of hydraulic oil to the steering cylinder 32 via the automatic steering circuit 50. Then, the controller 10B terminates. Figure 14 The controller 10B can repeat the processing after a specified operation cycle. Figure 14 The processing.

[0161] In S24, controller 10B does not restrict the supply of hydraulic oil to the steering cylinder 32 via the automatic steering circuit 50 through the steering oil pressure control unit 15B. In S24, the steering oil pressure control unit 15B controls the solenoid proportional valve 51 in a manner that allows hydraulic oil from the hydraulic pump 31 to be supplied to the steering cylinder 32 via the solenoid proportional valve 51 (e.g., in a manner that allows the valve stem 53 to move from the neutral position). Furthermore, in S24, the steering oil pressure control unit 15B controls the unloading valve 52 in a manner that does not reduce the pressure of the hydraulic oil in the automatic steering circuit 50 (e.g., in a manner that closes the unloading valve 52). Therefore, the supply of hydraulic oil to the steering cylinder 32 via the automatic steering circuit 50 is not restricted. Then, controller 10B terminates. Figure 14 The controller 10B can repeat the process after a specified operation cycle. Figure 14 The processing.

[0162] [The function and effects of the second embodiment]

[0163] In the steering system 100B of the industrial vehicle, even when the steering wheel 33 is operated, the priority valve 60 supplies hydraulic oil to the automatic steering circuit 50 at a second flow rate when residual flow is generated. The supply of hydraulic oil to the steering cylinder 32 via the automatic steering circuit 50 is limited by the supply limiting mechanism when the steering operation detection unit detects the operation of the steering wheel 33. Thus, when the steering wheel 33 is operated, the operation of the steering cylinder 32, achieved by the hydraulic oil supplied to the automatic steering circuit 50, is limited. Therefore, according to the steering system 100B of the industrial vehicle, the influence of the hydraulic oil supplied through the automatic steering circuit 50 on the operation of the steering cylinder 32 corresponding to the operation of the steering wheel 33 can be suppressed. In other words, the steering of the steering wheel achieved by the operation of the steering wheel 33 can be prevented from being hindered by the hydraulic oil on the automatic steering side, and the effect of deterioration in response to manual operation (deterioration in efficiency) can be suppressed.

[0164] The supply limiting mechanism of the steering device 100B of the industrial vehicle includes a controller 10B. When the steering hydraulic pressure control unit 15B detects operation of the steering wheel 33, the controller 10B controls the solenoid proportional valve 51 to prevent the supply of hydraulic oil from the hydraulic pump 31 to the steering cylinder 32 via the solenoid proportional valve 51. Thus, when the steering wheel 33 is operated, by blocking the hydraulic oil supplied to the automatic steering circuit 50 with the solenoid proportional valve 51, the operation of the steering cylinder 32, which is powered by the hydraulic oil supplied to the automatic steering circuit 50, can be limited.

[0165] In the steering device 100B of the industrial vehicle, the supply limiting mechanism includes: an unloading valve 52 configured to reduce the pressure of the hydraulic oil in the automatic steering circuit 50; and a controller 10B that controls the unloading valve 52 to reduce the pressure of the hydraulic oil in the automatic steering circuit 50 when the steering oil pressure control unit 15B detects operation of the steering wheel 33. Thus, by using the unloading valve 52 to reduce the pressure of the hydraulic oil in the automatic steering circuit 50 when the steering wheel 33 is operated, the operation of the steering cylinder 32, which is controlled by the hydraulic oil supplied to the automatic steering circuit 50, can be limited.

[0166] In the steering system 100B of the industrial vehicle, the operation of the steering wheel 33 is a predetermined operation performed by the operator of the industrial vehicle 1B. The steering hydraulic pressure control unit 15B detects the predetermined operation when the steering speed of the steering wheel 33 is below a predetermined steering speed threshold. When the steering wheel 33 is operated, the slower the rotation speed of the steering wheel 33, the smaller the flow of hydraulic oil through the manual steering circuit 40 to the steering cylinder 32, thus easily generating excess flow. Therefore, by detecting the predetermined operation when the steering speed of the steering wheel 33 is below the steering speed threshold, the supply of hydraulic oil to the steering cylinder 32 through the automatic steering circuit 50 is restricted. This suppresses the influence of the hydraulic oil supplied through the automatic steering circuit 50 on the operation of the steering cylinder 32 corresponding to the operation of the steering wheel 33.

[0167] [Example of a variation of the second embodiment]

[0168] The second embodiment of the present invention has been described above, but the present invention is not limited to the second embodiment described herein.

[0169] The supply limiting mechanism is not limited to the unloading valve 52, the solenoid proportional valve 51, and the controller 10B as described above. For example, the controller 10B can control the rotational speed of the (fixed capacity) hydraulic pump 31 as a limitation imposed by the supply limiting mechanism. When the steering hydraulic pressure control unit 15B detects the operation of the steering wheel 33, the controller 10B reduces the remaining flow by decreasing the rotational speed of the hydraulic pump 31, thereby limiting the supply of hydraulic oil to the steering cylinder 32 through the automatic steering circuit 50.

[0170] Alternatively, as another variation of the supply limiting mechanism, the hydraulic pump 31 can be a variable-capacity pump configured to vary the amount of hydraulic oil injected during operation. When the steering hydraulic pressure control unit 15B detects operation of the steering wheel 33, the controller 10B can control the variable-capacity pump by reducing the amount of hydraulic oil injected. In this case, by controlling the injection amount of the variable-capacity pump during operation, as a limitation imposed by the supply limiting mechanism, the remaining flow can be reduced when the steering hydraulic pressure control unit 15B detects operation of the steering wheel 33, thus limiting the supply of hydraulic oil to the steering cylinder 32 through the automatic steering circuit 50.

[0171] In the second embodiment, the detection of steering wheel 33 operation by the steering hydraulic pressure control unit 15B sets the execution of automatic driving control as a condition, but it is not necessary to set the execution of automatic driving control as a condition. Even in this case, if, for example, after a change from execution to non-execution of automatic driving control, the residual pressure of the hydraulic oil immediately remains through the automatic steering circuit 50, then by using the unloading valve 52 to reduce the pressure of the hydraulic oil in the automatic steering circuit 50, the response of the steering cylinder 32 corresponding to the operation of the steering wheel 33 can be improved (efficiency improvement).

[0172] When controller 10B controls the unloading valve 52 by returning hydraulic oil to the oil tank 34 via return circuit 30d, control by closing the solenoid proportional valve 51 can be omitted. Alternatively, it is sufficient that controller 10B can at least control the supply of hydraulic oil to the steering cylinder 32 via the automatic steering circuit 50 by closing the solenoid proportional valve 51. In this case, the unloading valve 52 can be omitted in the steering device 100B of the industrial vehicle.

[0173] [Other examples of variations]

[0174] In the first and second embodiments, examples are shown as follows: Figure 1 , Figure 9 The electric tractor is designated as industrial vehicle 1A or 1B, but is not limited to this. Industrial vehicles 1A or 1B can be other industrial vehicles such as forklifts.

[0175] The configuration for autonomous driving in industrial vehicles 1A and 1B is not limited to the examples of the first and second embodiments described above. For example, a lidar sensor can be used in the surrounding condition sensor 22, but other sensors can be used instead.

[0176] At least a portion of the first and second embodiments described above, as well as various variations, can be arbitrarily combined.

[0177] [Explanation of Symbols]

[0178] 1A, 1B... Industrial vehicles; 10A, 10B... Controller (control unit, supply limiting mechanism); 11... Map information acquisition unit; 12... Location information acquisition unit; 13... Driving information acquisition unit; 14... Automatic driving control unit; 15A, 15B... Steering hydraulic control unit (steering operation detection unit); 25... Switch (switch); 26... Steering angle sensor (steering operation detection unit); 30... Steering hydraulic circuit (hydraulic circuit); 31... Hydraulic pump; 32... Steering cylinder; 33... Steering wheel; 40... Manual steering circuit; 41... PS valve (first valve); 50... Automatic steering circuit; 51... Electromagnetic proportional valve (second valve, supply limiting mechanism); 52... Unloading valve (supply limiting mechanism); 60... Priority valve; 100A, 100B... Steering device for industrial vehicles.

Claims

1. A steering device for an industrial vehicle, comprising a hydraulic pump for injecting hydraulic oil and a steering cylinder for turning a steering wheel by means of a supply of said hydraulic oil, and further comprising: The manual steering circuit has a first valve that opens and closes according to the operation of the steering wheel, through which hydraulic oil injected from the hydraulic pump is supplied to the steering cylinder; An automatic steering circuit includes a second valve that opens and closes according to the calculation results of automatic driving control, through which hydraulic oil injected from the hydraulic pump is supplied to the steering cylinder; and A flow divider valve, disposed between the hydraulic pump and the first and second valves, divides the hydraulic oil into the manual steering circuit and the automatic steering circuit; and The flow divider valve is a priority valve, which supplies hydraulic oil preferentially to the manual steering circuit at a design flow rate above the specified flow rate for the steering cylinder to operate. The steering device of the industrial vehicle also includes an unloading mechanism, which reduces the pressure of the hydraulic oil from the oil pump acting on the second valve when the prescribed automatic steering non-operating condition of suspending the supply of hydraulic oil through the second valve is met, compared to the case where the automatic steering non-operating condition is not met.

2. The steering device for an industrial vehicle according to claim 1, wherein the unloading mechanism comprises: The control unit determines whether the automatic steering non-operation conditions are met based on information related to the execution or non-execution of the automatic driving control or the vehicle speed information of the industrial vehicle. as well as The unloading valve is configured to reduce the pressure of the hydraulic oil from the oil pump acting on the second valve based on the determination result of the control unit. and When the control unit determines that the automatic steering non-operating conditions are met, it controls the unloading valve in such a way as to reduce the pressure of the hydraulic oil from the oil pump acting on the second valve.

3. The steering device for an industrial vehicle according to claim 1, wherein the unloading mechanism comprises: The control unit, based on information related to the execution or non-execution of the automatic driving control, or the vehicle speed information of the industrial vehicle, determines whether the automatic steering non-operation conditions are met; and The variable capacity pump, which is the hydraulic pump in question, is configured to change the amount of hydraulic oil injected during operation based on the determination result of the control unit; and When the control unit determines that the automatic steering non-operating conditions are met, it controls the variable capacity pump to reduce the amount of hydraulic oil injected.

4. The steering device for an industrial vehicle according to claim 2 or 3, wherein the control unit determines that the automatic steering non-operation condition is met when the state of the switch is the non-executable state of the automatic steering control based on a signal from a switch for switching the execution or non-execution of the automatic driving control.

5. The steering device for an industrial vehicle according to claim 2 or 3, wherein the control unit determines, based on the vehicle speed information of the industrial vehicle, whether the industrial vehicle has been continuously stopped for a predetermined time, and when it is determined that the industrial vehicle has been continuously stopped for a predetermined time, it determines that the automatic steering non-working condition is met.

6. A steering device for an industrial vehicle, comprising a hydraulic pump for injecting hydraulic oil and a steering cylinder for turning a steering wheel by means of a supply of said hydraulic oil, and further comprising: The manual steering circuit has a first valve that opens and closes according to the operation of the steering wheel, through which hydraulic oil injected from the hydraulic pump is supplied to the steering cylinder; An automatic steering circuit has a second valve that opens and closes according to the calculation results of automatic driving control, and the hydraulic oil injected from the hydraulic pump is supplied to the steering cylinder through the second valve; A flow divider valve, disposed between the hydraulic pump and the first valve and the second valve, divides the hydraulic oil into the manual steering circuit and the automatic steering circuit; and The steering operation detection unit detects the operation of the steering wheel; The flow divider valve is a priority valve, supplying hydraulic oil preferentially to the manual steering circuit at a first flow rate exceeding the predetermined flow rate from the hydraulic oil ejected from the hydraulic pump that operates the steering cylinder, and supplying hydraulic oil to the automatic steering circuit at a second flow rate, the remaining flow rate from the hydraulic oil ejected from the hydraulic pump excluding the first flow rate; and The steering device of the industrial vehicle has a supply limiting mechanism, which restricts the supply of hydraulic oil to the steering cylinder through the automatic steering circuit when the steering operation detection unit detects the operation of the steering wheel. The supply restriction mechanism has: An unloading valve is configured to reduce the pressure of the hydraulic oil in the automatic steering circuit; and The control unit controls the unloading valve in a manner that reduces the pressure of the hydraulic oil in the automatic steering circuit when the steering operation detection unit detects the operation of the steering wheel.

7. The steering device for an industrial vehicle according to claim 6, wherein the supply limiting mechanism has a control unit that controls the second valve to prevent the supply of hydraulic oil from the hydraulic pump to the steering cylinder when the steering operation detection unit detects the operation of the steering wheel.

8. The steering device for an industrial vehicle according to claim 6 or 7, wherein the operation of the steering wheel is a predetermined operation of the steering wheel performed by the operator of the industrial vehicle; and The steering operation detection unit detects the specified operation when the rotation speed of the steering wheel is below a specified rotation speed threshold.

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