Engine-powered industrial vehicles

Abstract

To prevent contact between objects and engine-powered industrial vehicles. [Solution] The forklift comprises an engine, a power transmission mechanism, a control device, a direction lever, and an object detection unit. The direction lever determines the direction of travel of the forklift according to the operating position. The object detection unit detects the position of objects present in the direction of travel of the forklift. The power transmission mechanism can be switched between a drive transmission state, in which the driving force of the engine is transmitted to the power transmission mechanism, and a drive non-transmission state, in which the driving force of the engine is not transmitted to the power transmission mechanism. The control device puts the forklift into a no-start state S3 when the object detection unit has detected an object, the direction of travel determined by the direction of travel determination unit matches the direction of travel, and the vehicle speed of the forklift is below a stop judgment threshold. In the no-start state S3, the power transmission mechanism is set to a no-drive state.

Description

Technical Field

[0001] The present disclosure relates to engine-powered industrial vehicles.

Background Art

[0002] The industrial vehicle disclosed in Patent Document 1 includes a control device, an object detection unit, and a direction sensor. The control device controls the industrial vehicle. The object detection unit detects the position of an object. The direction sensor detects the operation direction of a direction lever that indicates the traveling direction. The direction sensor detects whether the direction lever is operated in the direction indicating forward or the direction indicating backward with respect to the neutral position. When an object exists in the traveling direction of the industrial vehicle when starting the industrial vehicle, the control device prohibits the start of the industrial vehicle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the case of an engine-powered industrial vehicle in which the industrial vehicle travels with an engine, when the direction lever is operated to a position different from the neutral position, the engine-powered industrial vehicle advances due to creep. Therefore, even though an object exists in the traveling direction of the engine-powered industrial vehicle, the engine-powered industrial vehicle may start and the object and the engine-powered industrial vehicle may come into contact with each other. In this case, since the work efficiency is reduced, it is required to appropriately suppress the contact between the object and the engine-powered industrial vehicle when starting the engine-powered industrial vehicle.

Means for Solving the Problems

[0005] An engine-driven industrial vehicle that solves the above problems comprises an engine, a power transmission mechanism that transmits the driving force of the engine to the drive wheels, and a control device that adjusts the driving force transmitted to the drive wheels, wherein the engine-driven industrial vehicle comprises a direction determination unit that determines the direction of travel of the engine-driven industrial vehicle by being operated to a forward position that instructs forward movement or a reverse position that instructs reverse movement, with respect to a neutral position, and an object detection unit that detects the position of an object present in the direction of travel of the engine-driven industrial vehicle, wherein the power transmission mechanism is switchable between a drive transmission state in which the driving force of the engine is transmitted to the power transmission mechanism and a drive non-transmission state in which the driving force of the engine is not transmitted to the power transmission mechanism The control device puts the engine-powered industrial vehicle into a no-start state when the object detection unit has detected an object and the direction of travel determined by the direction of travel determination unit matches, and the vehicle speed of the engine-powered industrial vehicle is below a stop determination threshold. The control device also releases the no-start state when the direction of travel determined by the direction of travel determination unit is changed while the engine-powered industrial vehicle is in the no-start state, and the engine speed is below a predetermined speed. The no-start state includes at least one of the following: the power transmission mechanism is changed to the non-drive transmission state, and a braking force is applied to the engine-powered industrial vehicle.

[0006] With respect to the above-mentioned engine-driven industrial vehicle, when the start-prohibition state is released, the engine-driven industrial vehicle is put into a forced-operation state, and when the engine-driven industrial vehicle is in the forced-operation state, even if the direction of travel determined by the direction of travel determination unit returns to the direction of travel before the start-prohibition state was released after the start-prohibition state is released, the forced-operation state is maintained, the start-prohibition state is a state in which the power transmission mechanism is changed to the non-drive transmission state, and the forced-operation state is a state in which the engine-driven industrial vehicle is made capable of moving by forcibly changing the power transmission mechanism to the drive transmission state.

[0007] With respect to the above-mentioned engine-driven industrial vehicle, the forced operation state is a state in which a vehicle speed limit is set, and when the engine-driven industrial vehicle is in the forced operation state, the control device may allow the vehicle to proceed at or below the higher of the vehicle speed limit and the vehicle speed corresponding to the engine's idle speed. [Effects of the Invention]

[0008] According to the present invention, contact between an object and an engine-powered industrial vehicle can be suppressed. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view of a forklift. [Figure 2] This is a schematic diagram of a forklift. [Figure 3] This is a schematic diagram of the driving and cargo handling systems. [Figure 4] This is a flowchart showing the object detection process. [Figure 5] This diagram schematically shows the area where starting is restricted. [Figure 6] This is a state transition diagram for the launch restriction control. [Figure 7] This is a schematic diagram of the modified forklift configuration. [Modes for carrying out the invention]

[0010] The following describes one embodiment of an engine-powered industrial vehicle. <Forklift> As shown in Figure 1, the forklift 10 as an engine-powered industrial vehicle comprises a body 11, two drive wheels 12, two steering wheels 14, and a cargo handling device 20. In the following description, front, rear, left, and right refer to the front, rear, left, and right of the forklift 10.

[0011] The vehicle body 11 is equipped with a head guard 15 located above the driver's seat. The two drive wheels 12 are located at the front lower part of the vehicle body 11. The two drive wheels 12 are spaced apart from each other in the vehicle width direction.

[0012] The two steering wheels 14 are located at the lower rear of the vehicle body 11. The two steering wheels 14 are spaced apart from each other in the vehicle width direction. <Cargo handling equipment> The cargo handling device 20 comprises a mast 21, a pair of forks 22, and a lift cylinder 23. The mast 21 is located at the front of the vehicle body 11. The forks 22 are mounted to be able to move up and down together with the mast 21. Loads are loaded onto the forks 22. The lift cylinder 23 is a hydraulic cylinder. The mast 21 moves up and down by the extension and retraction of the lift cylinder 23. The forks 22 move up and down in conjunction with the movement of the mast 21. In this embodiment, the forklift 10 is operated by a passenger to perform both driving and cargo handling operations.

[0013] <Forklift Configuration> As shown in Figure 2, the forklift 10 includes a travel system 30, a cargo handling system 70, a control device 81, an accelerator pedal 84, an accelerator sensor 85, a tire angle sensor 86, a seating sensor 87, a direction lever 88, a direction switch 90, a forward connection wire 101, a reverse connection wire 102, a forward detection wire 103, a reverse detection wire 104, a first forward relay 111, a first reverse relay 112, a second forward relay 121, a second reverse relay 122, and an object detection unit 131.

[0014] <Driving System> As shown in Figure 3, the travel system 30 is a mechanism for moving the forklift 10. The travel system 30 includes an engine 31, an output shaft 33, a rotational speed sensor 34, a power transmission mechanism 40, a solenoid valve 50, a forward solenoid 51, a reverse solenoid 52, a differential 60, an axle 61, a vehicle speed sensor 62, and a travel control device 63.

[0015] <Engine> The engine 31 is the driving source for the traveling operation and the cargo handling operation of the forklift 10. The engine 31 in this embodiment is a gasoline engine that uses gasoline as fuel. The engine 31 includes a throttle actuator 32. The throttle actuator 32 adjusts the throttle opening of a throttle valve (not shown) provided in the intake passage so as to follow the target rotational speed of the engine 31 calculated from the opening degree of the accelerator pedal 84. By adjusting the throttle opening with the throttle actuator 32, the amount of air supplied to the engine 31 is adjusted. Thereby, the rotational speed of the engine 31 is controlled. As the engine 31, a diesel engine that uses light oil as fuel may be used. As the engine 31, an engine that uses liquefied petroleum gas or compressed natural gas as fuel may be used. The output shaft 33 is connected to the engine 31. The output shaft 33 rotates by the drive of the engine 31.

[0016] <Rotation speed sensor> The rotation speed sensor 34 is provided on the output shaft 33. The rotation speed sensor 34 detects the rotational speed of the engine 31. The rotational speed of the engine 31 is the rotational speed of the output shaft 33. The rotation speed sensor 34 outputs an electric signal corresponding to the rotational speed of the output shaft 33 to the traveling control device 63.

[0017] <Power transmission mechanism> The power transmission mechanism 40 transmits the driving force of the engine 31 to the drive wheels 12. The power transmission mechanism 40 includes a torque converter 41 and a transmission 42.

[0018] <Torque converter> The torque converter 41 is connected to the output shaft 33. The driving force of the engine 31 is transmitted to the torque converter 41 via the output shaft 33. The torque converter 41 includes a pump connected to the output shaft 33 and a turbine. In the torque converter 41, the turbine rotates by the working oil discharged from the pump.

[0019] <Transmission> The transmission 42 comprises an input shaft 43, a forward clutch 44, a forward gear train 45, a reverse clutch 46, a reverse gear train 47, and an output shaft 48. The input shaft 43 is connected to a torque converter 41. Drive force is transmitted from the torque converter 41 to the transmission 42 via the input shaft 43.

[0020] <Forward clutch and reverse clutch> The forward clutch 44 is located on the input shaft 43. The forward gear train 45 is located between the forward clutch 44 and the output shaft 48. The forward clutch 44 can be switched between a connected state and a disconnected state. The connected state is when the input shaft 43 and the forward gear train 45 are connected. The disconnected state is when the input shaft 43 and the forward gear train 45 are disconnected. When the input shaft 43 and the forward gear train 45 are connected by the forward clutch 44, driving force is transmitted from the input shaft 43 to the forward gear train 45. The driving force transmitted to the forward gear train 45 is then transmitted to the output shaft 48. When the forward clutch 44 is connected to the forward gear train 45, it can be said that the driving force of the engine 31 is transmitted to the output shaft 48. When the forward clutch 44 and the forward gear train 45 are disconnected, no driving force is transmitted from the input shaft 43 to the forward gear train 45. A hydraulic clutch is used as the forward clutch 44. An example of a hydraulic clutch is a wet multi-plate clutch.

[0021] The reverse clutch 46 is provided on the input shaft 43. The reverse gear train 47 is provided between the reverse clutch 46 and the output shaft 48. The reverse clutch 46 can be switched between an engaged state and an engaged state. The engaged state is when the input shaft 43 and the reverse gear train 47 are engaged. The engaged state is when the input shaft 43 and the reverse gear train 47 are disconnected. When the reverse clutch 46 is engaged between the input shaft 43 and the reverse gear train 47, driving force is transmitted from the input shaft 43 to the reverse gear train 47. The driving force transmitted to the reverse gear train 47 is then transmitted to the output shaft 48. When the reverse clutch 46 is engaged with the reverse gear train 47, it can be said that the driving force of the engine 31 is transmitted to the output shaft 48. When the reverse clutch 46 and the reverse gear train 47 are disconnected, no driving force is transmitted from the input shaft 43 to the reverse gear train 47. A hydraulic clutch is used as the reverse clutch 46. An example of a hydraulic clutch is a wet multi-plate clutch.

[0022] <Solenoid valve> The solenoid valve 50 controls the supply and discharge of hydraulic fluid to the forward clutch 44 and the reverse clutch 46. The supply and discharge of hydraulic fluid by the solenoid valve 50 switches between the engaged and disengaged states of the clutches 44 and 46.

[0023] <Forward solenoid and reverse solenoid> Solenoids 51 and 52 switch the supply and discharge of hydraulic fluid to clutches 44 and 46 by the solenoid valve 50. When the forward solenoid 51 is energized, hydraulic fluid is supplied from the solenoid valve 50 to the forward clutch 44. When hydraulic fluid is supplied to the forward clutch 44, the forward clutch 44 is engaged. When the reverse solenoid 52 is energized, hydraulic fluid is supplied from the solenoid valve 50 to the reverse clutch 46. When hydraulic fluid is supplied to the reverse clutch 46, the reverse clutch 46 is engaged.

[0024] A single electromagnetic directional control valve may be used as the solenoid valve 50. The electromagnetic directional control valve is a solenoid valve whose spool switches to a position that supplies hydraulic fluid to the forward clutch 44 when the forward solenoid 51 is energized, and switches to a position that supplies hydraulic fluid to the reverse clutch 46 when the reverse solenoid 52 is energized. When both the forward solenoid 51 and the reverse solenoid 52 are demagnetized, the spool of the electromagnetic directional control valve switches to a position that discharges hydraulic fluid from both clutches 44 and 46. The hydraulic fluid that operates the forward clutch 44 and the reverse clutch 46 is supplied by a hydraulic pump located inside the power transmission mechanism 40. The configuration of this hydraulic pump is a well-known configuration.

[0025] Two solenoid valves may be used as the solenoid valve 50. The two solenoid valves are provided corresponding to the forward clutch 44 and the reverse clutch 46, respectively. In this case, the forward solenoid 51 and the reverse solenoid 52 can individually control each solenoid valve 50 to supply hydraulic fluid to both clutches 44 and 46 and to discharge hydraulic fluid from both clutches 44 and 46.

[0026] <Drive transmission state and drive non-transmission state> The power transmission mechanism 40 can be switched between a drive transmission state, in which the driving force of the engine 31 is transmitted to the power transmission mechanism 40, and a drive non-transmission state, in which the driving force of the engine 31 is not transmitted to the power transmission mechanism 40. When either the forward clutch 44 or the reverse clutch 46 is engaged, the driving force of the engine 31 is transmitted to the power transmission mechanism 40, thereby causing the forklift 10 to move. The drive transmission state is when either the forward clutch 44 or the reverse clutch 46 is engaged. When the forward clutch 44 or the reverse clutch 46 is disengaged, the driving force of the engine 31 is not transmitted to the power transmission mechanism 40. The drive non-transmission state is when the forward clutch 44 or the reverse clutch 46 is disengaged.

[0027] <Differential gear and axle> The differential 60 is connected to the output shaft 48. The axle 61 is connected to the differential 60. The drive wheels 12 are connected to the axle 61. When the output shaft 48 rotates, the axle 61 rotates. The rotation of the axle 61 causes the drive wheels 12 to rotate, causing the forklift 10 to move forward. If the forward clutch 44 and the forward gear train 45 are engaged, the forklift 10 moves forward. If the reverse clutch 46 and the reverse gear train 47 are engaged, the forklift 10 moves backward.

[0028] <Vehicle speed sensor> The vehicle speed sensor 62 is a sensor for detecting the vehicle speed of the forklift 10. The vehicle speed sensor 62 is installed, for example, on the output shaft 48 or the axle 61. The vehicle speed sensor 62 outputs a pulse signal corresponding to the vehicle speed of the forklift 10 to the driving control device 63.

[0029] <Traction control device> The driving control device 63 is an engine control unit that controls the engine 31. The driving control device 63 adjusts the throttle opening by controlling the throttle actuator 32. By adjusting the throttle opening, the driving force of the engine 31 is adjusted.

[0030] <Cargo handling system> The cargo handling system 70 is a mechanism for operating the cargo handling device 20. The cargo handling system 70 includes an oil tank 71 for storing hydraulic fluid, a hydraulic pump 72, and a hydraulic mechanism 73.

[0031] <Hydraulic pump> The hydraulic pump 72 is driven by the engine 31. The hydraulic pump 72 draws hydraulic fluid from the oil tank 71. The drawn hydraulic fluid is supplied to the hydraulic mechanism 73.

[0032] <Hydraulic mechanism> The hydraulic mechanism 73 includes a control valve. The control valve controls the supply and discharge of hydraulic fluid to the hydraulic equipment. Examples of hydraulic equipment include a lift cylinder 23 and a tilt cylinder for tilting the cargo handling device 20. The cargo handling device 20 operates by the supply or discharge of hydraulic fluid. The hydraulic equipment may be any hydraulic equipment provided by the forklift 10, or it may be hydraulic equipment provided by the vehicle body 11.

[0033] <Control device> As shown in Figure 2, the control device 81 comprises a processor 82 and a storage unit 83. Examples of the processor 82 include a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and a DSP (Digital Signal Processor). The storage unit 83 includes RAM (Random Access Memory) and ROM (Read Only Memory). The storage unit 83 stores program code or instructions configured to cause the processor 82 to execute processing. The storage unit 83, i.e., the computer-readable medium, includes any available medium accessible by a general-purpose or dedicated computer. The control device 81 may also be composed of hardware circuits such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The control device 81, which is a processing circuit, may include one or more processors operating according to a computer program, one or more hardware circuits such as an ASIC or FPGA, or a combination thereof.

[0034] <Accelrop> The accelerator sensor 85 detects the amount of movement of the accelerator pedal 84. The amount of movement of the accelerator pedal 84 can also be called the accelerator opening angle. The accelerator sensor 85 outputs an electrical signal corresponding to the accelerator opening angle to the control device 81. The control device 81 can recognize the accelerator opening angle from the electrical signal from the accelerator sensor 85.

[0035] <Tire Angle Sensor> The tire angle sensor 86 detects the steering angle of the steering wheel 14. The tire angle sensor 86 outputs an electrical signal corresponding to the steering angle to the control device 81. The control device 81 can recognize the steering angle from the electrical signal from the tire angle sensor 86.

[0036] <Seat sensor> The seating sensor 87 is a mechanism that turns on when an occupant is seated in the driver's seat. The seating sensor 87 is located, for example, under the driver's seat. Examples of the seating sensor 87 include a switch, a pressure sensor, a weight sensor, an optical sensor, and a camera.

[0037] <Direction lever> The direction lever 88 determines the direction of travel of the forklift 10. The direction lever 88 is operated by the operator of the forklift 10. The direction lever 88 is operated to either a forward position, which indicates moving forward, or a reverse position, which indicates moving backward, relative to the neutral position. For example, the forward position is when the direction lever 88 is tilted forward from the neutral position. The reverse position is when the direction lever 88 is tilted backward from the neutral position. The direction lever 88 is the part that determines the direction of travel.

[0038] <Direction switch> The direction switch 90 switches according to the operating direction of the direction lever 88. The direction switch 90 comprises one movable contact 91 and three fixed contacts 92, 93, and 94. The movable contact 91 is connected to the positive terminal of the battery mounted on the forklift 10. The three fixed contacts 92, 93, and 94 include a neutral fixed contact 92, a forward fixed contact 93, and a reverse fixed contact 94. When the direction lever 88 is in the neutral position, the movable contact 91 and the neutral fixed contact 92 are connected. When the direction lever 88 is in the forward position, the movable contact 91 and the forward fixed contact 93 are connected. When the direction lever 88 is in the reverse position, the movable contact 91 and the reverse fixed contact 94 are connected.

[0039] <Forward connection line and reverse connection line> The forward connection line 101 connects the forward fixed contact 93 and the forward solenoid 51. When the movable contact 91 and the forward fixed contact 93 are connected, the forward connection line 101 is electrically connected to the battery. This energizes the forward solenoid 51. When the movable contact 91 and the forward fixed contact 93 are connected, the reverse solenoid 52 is demagnetized.

[0040] The reverse connection wire 102 connects the reverse fixed contact 94 and the reverse solenoid 52. When the movable contact 91 and the reverse fixed contact 94 are connected, the reverse connection wire 102 is electrically connected to the battery. This energizes the reverse solenoid 52. When the movable contact 91 and the reverse fixed contact 94 are connected, the forward solenoid 51 is demagnetized.

[0041] When the direction lever 88 is in the forward position, the forward solenoid 51 is energized, supplying hydraulic fluid to the forward clutch 44. This enables the forklift 10 to move forward. When the direction lever 88 is in the reverse position, the reverse solenoid 52 is energized, supplying hydraulic fluid to the reverse clutch 46. This enables the forklift 10 to move in reverse. When the direction lever 88 is in the neutral position, both solenoids 51 and 52 are demagnetized, and no hydraulic fluid is supplied to the clutches 44 and 46. In this case, the driving force of the engine 31 is not transmitted to the power transmission mechanism 40.

[0042] <Forward detection line and reverse detection line> The forward detection line 103 connects the forward connection line 101 to the control device 81. When voltage from the battery is applied to the forward connection line 101, voltage is applied to the control device 81 via the forward detection line 103. The reverse detection line 104 connects the reverse connection line 102 to the control device 81. When voltage from the battery is applied to the reverse connection line 102, voltage is applied to the control device 81 via the reverse detection line 104. The control device 81 can determine that the direction lever 88 is in the forward position if voltage is input from the forward detection line 103. The control device 81 can determine that the direction lever 88 is in the reverse position if voltage is input from the reverse detection line 104. The control device 81 can determine that the direction lever 88 is in the neutral position if there is no voltage input from either the forward detection line 103 or the reverse detection line 104.

[0043] <First forward relay and first reverse relay> The first forward relay 111 is located on the forward connection line 101. The first forward relay 111 can be switched between a connected state and a disconnected state. When the first forward relay 111 is in the connected state, the forward connection line 101 and the forward solenoid 51 are electrically connected. When the first forward relay 111 is in the disconnected state, the forward connection line 101 and the forward solenoid 51 are electrically disconnected. The first reverse relay 112 is located on the reverse connection line 102. The first reverse relay 112 can be switched between a connected state and a disconnected state. When the first reverse relay 112 is in the connected state, the reverse connection line 102 and the reverse solenoid 52 are electrically connected. When the first reverse relay 112 is in the disconnected state, the reverse connection line 102 and the reverse solenoid 52 are electrically disconnected.

[0044] The first forward relay 111 and the first reverse relay 112 are switched between connected and disconnected states by the control device 81. When the seating sensor 87 detects that an occupant is seated, the control device 81 connects the first forward relay 111 and the first reverse relay 112. If the seating sensor 87 does not detect that an occupant is seated for a predetermined period of time or longer, the control device 81 disconnects the first forward relay 111 and the first reverse relay 112. The predetermined period can be set to any desired time. When the first forward relay 111 and the first reverse relay 112 are disconnected, the solenoids 51 and 52 are demagnetized regardless of the position of the direction lever 88, and the driving force of the engine 31 is no longer transmitted to the power transmission mechanism 40. In other words, the power transmission mechanism 40 is in a non-driving state.

[0045] <Second forward relay and second reverse relay> The second forward relay 121 is located on the forward connection line 101. The second forward relay 121 can be switched between a connected state and a disconnected state. When the second forward relay 121 is in the connected state, the forward connection line 101 and the forward solenoid 51 are electrically connected. When the second forward relay 121 is in the disconnected state, the forward connection line 101 and the forward solenoid 51 are electrically disconnected. The second reverse relay 122 is located on the reverse connection line 102. The second reverse relay 122 can be switched between a connected state and a disconnected state. When the second reverse relay 122 is in the connected state, the reverse connection line 102 and the reverse solenoid 52 are electrically connected. When the second reverse relay 122 is in the disconnected state, the reverse connection line 102 and the reverse solenoid 52 are electrically disconnected.

[0046] The second forward relay 121 and the second reverse relay 122 are switched between connected and disconnected states by the control device 81. The control device 81 connects the second forward relay 121 and the second reverse relay 122 when a switchback operation is not being performed. The control device 81 disconnects the second forward relay 121 and the second reverse relay 122 when a switchback operation is being performed. A switchback operation is an operation in which the direction of travel is changed from forward to reverse or from reverse to forward by operating the direction lever 88. The control device 81 determines that a switchback operation is being performed when the direction of travel indicated by the direction lever 88 does not match the direction of travel of the forklift 10. When the second forward relay 121 and the second reverse relay 122 are disconnected, the solenoids 51 and 52 are demagnetized regardless of the position of the direction lever 88, and the driving force of the engine 31 is no longer transmitted to the power transmission mechanism 40. In other words, the power transmission mechanism 40 is in a non-driving state.

[0047] <Object detection unit> The object detection unit 131 comprises a stereo camera 132, a detection device 133, and an alarm device 136. The stereo camera 132 has two cameras and performs imaging using both cameras. As shown in Figure 1, the stereo camera 132 is positioned on the head guard 15. The stereo camera 132 is positioned to provide a bird's-eye view of the road surface on which the forklift 10 travels, from above the forklift 10. In this embodiment, the stereo camera 132 images the area behind the forklift 10. Therefore, the objects detected by the object detection unit 131 are objects behind the forklift 10. The detection direction of the object detection unit 131 can be said to be the rear. The alarm device 136 and the detection device 133 may be unitized with the stereo camera 132 and positioned together with the stereo camera 132 on the head guard 15. Alternatively, the alarm device 136 and the detection device 133 may be positioned at locations different from the head guard 15.

[0048] The detection device 133 comprises a processor 134 and a storage unit 135. For example, the processor 134 may be a CPU, GPU, or DSP. The storage unit 135 includes RAM and ROM. The storage unit 135 stores various programs for detecting objects from images captured by the stereo camera 132. The storage unit 135 can be said to store program code or instructions configured to cause the processor 134 to execute processing. The storage unit 135, i.e., the computer-readable medium, includes any available medium accessible by a general-purpose or dedicated computer. The detection device 133 may also be composed of hardware circuits such as ASICs or FPGAs. The detection device 133, which is a processing circuit, may include one or more processors operating according to a computer program, one or more hardware circuits such as ASICs or FPGAs, or a combination thereof.

[0049] <Object detection processing> The detection device 133 detects objects located behind the forklift 10 by repeatedly performing the following object detection process at a predetermined control cycle. The detection device 133 also derives the position of the detected object. The object's position is the relative position between the forklift 10 and the object.

[0050] As shown in Figure 4, in step S100, the detection device 133 acquires an image from the stereo camera 132. Next, in step S110, the detection device 133 acquires a parallax image by performing stereo processing. A parallax image associates parallax [px] with each pixel. A parallax image does not necessarily need to be displayed; it simply refers to data in which parallax is associated with each pixel in the parallax image. Parallax is obtained by comparing two images captured by the stereo camera 132 and deriving the difference in the number of pixels between the images for identical feature points captured in each image. Feature points are recognizable parts such as the edges of objects. Feature points can be detected from luminance information, etc.

[0051] Next, in step S120, the detection device 133 derives the coordinates of the feature points in the world coordinate system, which is a coordinate system in real space. The world coordinate system is a coordinate system in which, when the forklift 10 is positioned on the horizontal plane, the axis extending in the direction of the width of the forklift 10 is the X-axis, the axis perpendicular to the X-axis in the horizontal direction is the Y-axis, and the axis extending in the vertical direction is the Z-axis. The coordinates of the feature points are derived by first deriving the coordinates of the feature points in the camera coordinate system from the baseline length of the stereo camera 132, the focal length of the stereo camera 132, and the disparity image obtained in step S110, and then converting these coordinates to coordinates in the world coordinate system. As shown in Figure 1, the X-axis, Y-axis, and Z-axis are indicated by arrows X, Y, and Z.

[0052] As shown in Figure 4, in step S130, the detection device 133 extracts objects by clustering feature points. The detection device 133 groups together feature points that are assumed to represent the same object from among the feature points that represent parts of an object, and extracts this point group as an object. The detection device 133 performs clustering by considering feature points located within a predetermined range as a single point group from the coordinates of the feature points in the world coordinate system derived in step S120. The detection device 133 considers the clustered point group as a single object. Note that the clustering of feature points performed in step S130 can be carried out using various methods.

[0053] Next, in step S140, the detection device 133 derives the coordinates of the object in the world coordinate system. The coordinates of the object can be derived from the coordinates of the feature points that make up the point cloud. The coordinates of the object in the world coordinate system represent the relative position between the forklift 10 and the object. More specifically, in the coordinates of the object in the world coordinate system, the X coordinate represents the distance from the origin to the object in the left-right direction, and the Y coordinate represents the distance from the origin to the object in the front-back direction. The origin is, for example, a coordinate system where the X and Y coordinates are the position of the stereo camera 132 and the Z coordinate is the road surface. It is also possible to derive the Euclidean distance from the position of the stereo camera 132 to the object from the X and Y coordinates. In the coordinates of the object in the world coordinate system, the Z coordinate represents the height of the object from the road surface.

[0054] <Alarm device> The alarm device 136 is a device that provides an alarm to the occupants of the forklift 10. Examples of the alarm device 136 include a buzzer that provides an audible alarm, a lamp that provides a visual alarm, or a combination of these.

[0055] <Control performed by the control device> The control device 81, the driving control device 63, and the object detection unit 131 are configured to acquire information from each other. The control device 81, the driving control device 63, and the object detection unit 131 acquire information from each other by communicating in accordance with vehicle communication protocols such as CAN (Controller Area Network) and LIN (Local Interconnect Network).

[0056] The control device 81 derives the vehicle speed of the forklift 10. The vehicle speed of the forklift 10 can be derived using the detection result of the vehicle speed sensor 62, the gear ratio, the outer diameter of the drive wheels 12, and the steering angle detected by the tire angle sensor 86. The detection result of the vehicle speed sensor 62 can be obtained from the driving control device 63. The gear ratio and the outer diameter of the drive wheels 12 can be stored in the memory unit 83 in advance. The control device 81 also derives the direction of travel of the forklift 10 along with the vehicle speed. The direction of travel of the forklift 10 is either forward or reverse.

[0057] The control device 81 activates the alarm device 136 by transmitting an alarm command to the object detection unit 131. More specifically, the object detection unit 131 includes an activation unit that activates the alarm device 136, and upon receiving an alarm command, the activation unit activates the alarm device 136.

[0058] <Departure Restriction Area> The control device 81 performs launch restriction control. Launch restriction control is a control performed while the forklift 10 is stopped, and it restricts the launch of the forklift 10 according to the object detection status by the object detection unit 131. First, the launch restriction area used in launch restriction control will be explained.

[0059] As shown in Figure 5, a launch restriction area AA1, used for launch restriction control, is set within the object detection range of the object detection unit 131. The object detection range of the object detection unit 131 can also be said to be the imaging range of the stereo camera 132. The launch restriction area AA1 is an area that extends from the position of the stereo camera 132 to the rear of the forklift 10 and in the width direction of the forklift 10. The launch restriction area AA1 is an area defined by the X and Y coordinates in the world coordinate system.

[0060] The starting restriction area AA1 is divided into three areas: the central area N, the left area NL located to the left of the central area N, and the right area NR located to the right of the central area N. The central area N is the area facing the forklift 10 in the front-to-back direction. The left-to-right dimension of the central area N matches the width dimension of the forklift 10. The central area N can also be described as the area that the forklift 10 passes through when it moves straight in the reverse direction. The left area NL can be described as the area that the forklift 10 passes through when it turns left in the reverse direction. The right area NR can be described as the area that the forklift 10 passes through when it turns right in the reverse direction. The front-to-back dimension and the left-to-right dimension of the starting restriction area AA1 can be adjusted arbitrarily.

[0061] <Starting speed restriction control> As shown in Figure 6, in the launch restriction control, the control device 81 changes the state of the forklift 10 to one of the following states: normal control state S10, launch restriction state S2, launch prohibition state S3, or forced operation state S4, and controls are performed according to each state.

[0062] <Normal control state> Normal control state S10 is a state in which no vehicle speed limit is imposed. When the forklift 10 is in normal control state S10, the control device 81 calculates the target rotational speed from the accelerator opening detected by the accelerator sensor 85. The target rotational speed is a larger value as the accelerator opening increases. The control device 81 generates a rotational speed command from the target rotational speed. The control device 81 sends this rotational speed command to the travel control device 63. The travel control device 63 controls the engine 31 to follow the target rotational speed. More specifically, the travel control device 63 adjusts the throttle opening by controlling the throttle actuator 32. As a result, the forklift 10 travels at a vehicle speed corresponding to the amount of accelerator pedal 84 operated by the operator. In this way, the control device 81 can control the rotational speed of the engine 31 by sending a rotational speed command to the travel control device 63. It can be said that the driving force transmitted to the drive wheels 12 is adjusted by controlling the rotational speed of the engine 31.

[0063] <Starting restriction status> The starting restriction state S2 is a state in which the starting of the forklift 10 from a stationary state is restricted when an object is present in the starting restriction area AA1. Starting means transitioning the forklift 10 from a stationary state to a state in motion. In the starting restriction state S2, the starting of the forklift 10 may be restricted by limiting the vehicle speed, or by issuing a warning using the warning device 136.

[0064] <No departure allowed> The "no starting" state S3 is a state in which the forklift 10 is prohibited from starting. In the "no starting" state S3, the control device 81 controls the system to cut off the driving force to the drive wheels 12. In the "no starting" state S3, the control device 81 cuts off the second forward relay 121 and the second reverse relay 122, thereby disabling the power transmission mechanism 40. As a result, the travel system 30 is in the same state as when the direction lever 88 is in the neutral position. More specifically, the clutches 44, 46 and the gear train 45, 47 are not connected, and the driving force of the engine 31 is not transmitted to the power transmission mechanism 40. In the "no starting" state S3, the warning from the warning device 136 may be made stronger than in the "restricted starting" state S2. Making the warning stronger means, for example, if the warning device 136 is a buzzer, the buzzer sound may be made louder. If the warning device 136 is a combination of a lamp and a buzzer, the system may be switched from warning with one of the lamps and buzzers to warning with both.

[0065] <Forced operation state> The forced operation state S4 is a state in which a speed limit is imposed on the forklift 10 by setting a vehicle speed limit value VS1 [km / h]. The control device 81 controls the forklift 10 so that its speed does not exceed the vehicle speed limit value VS1. The vehicle speed limit value VS1 is a value greater than 0 and lower than the maximum vehicle speed that the forklift 10 can reach. For example, the vehicle speed limit value VS1 can be set to any value from 1 [km / h] to 4 [km / h]. The control device 81 can be said to allow the forklift 10 to proceed at a speed below the vehicle speed limit value VS1. In the forced operation state S4, progress is permitted with a limit imposed on the rotational speed of the engine 31. In this embodiment, a limit is imposed so that the rotational speed of the engine 31 does not exceed the idle speed. The control device 81 allows the vehicle speed to exceed the vehicle speed limit value VS1 if the rotational speed of the engine 31 is at the idle speed. The forced operation state S4 can be described as a state in which movement is permitted at or below the higher of the vehicle speed limit VS1 and the vehicle speed corresponding to the idle speed. In the forced operation state S4, the warning from the warning device 136 may be weaker than in the prohibited start state S3. In the forced operation state S4, the power transmission mechanism 40 is set to the drive transmission state. Note that in the forced operation state S4, it is not necessary to set the vehicle speed limit VS1 [km / h]. In other words, the forced operation state S4 is sufficient if the forklift 10 is in a state where it can move.

[0066] <Transition from normal control state to launch restriction state> When the forklift 10 is in the normal control state S10 and the starting restriction condition is met, the control device 81 transitions the state of the forklift 10 from the normal control state S10 to the starting restriction state S2. The meeting of the starting restriction condition means that the following first restriction condition and second restriction condition are met.

[0067] First restriction condition: An object is present in the launch restriction area AA1. Second restriction condition: Forklift 10 is stopped. Whether or not the first restriction condition is met can be determined from the object's X and Y coordinates. Since the launch restriction area AA1 is defined by the X and Y coordinates, it can be determined from the object's X and Y coordinates whether or not the object is in the launch restriction area AA1.

[0068] Whether or not the second limiting condition is met can be determined from the vehicle speed calculated by the control device 81. The control device 81 determines that the forklift 10 is stopped if the vehicle speed is less than or equal to the stop determination threshold [km / h]. The stop determination threshold is set to a value that the forklift 10 can be considered to be stopped, and can be set to any value from 0 [km / h] to 0.5 [km / h], for example.

[0069] <Transition from restricted launch state to normal control state> When the forklift 10 is in the restricted starting state S2, if the conditions for releasing the restricted starting state are met, the control device 81 transitions the state of the forklift 10 from the restricted starting state S2 to the normal control state S10. The conditions for releasing the restricted starting state are met if at least one of the following first release conditions, second release conditions, third release conditions, and fourth release conditions is met.

[0070] First deactivation condition: No objects are present in the launch restriction area AA1. Second deactivation condition: Forklift 10 is moving forward at a speed exceeding the specified speed. Third deactivation condition: Forklift 10 continues to move in reverse at a speed exceeding a specified speed for a specified period of time.

[0071] Fourth deactivation condition: Forklift 10 is reversing at a speed exceeding the specified speed. The predetermined speed for the second release condition can be set to any value as long as it is higher than the stop judgment threshold. For example, the predetermined speed for the second release condition can be set to any value within the range of 1 [km / h] to 2 [km / h].

[0072] The predetermined speed for the third release condition can be set to any value as long as it is higher than the stop judgment threshold. For example, the predetermined speed for the third release condition can be set to any value within the range of 1 [km / h] to 2 [km / h]. The predetermined time for the third release condition can be set to any value. For example, the predetermined time for the third release condition can be set to any value within the range of 1 second to 2 seconds.

[0073] The predetermined speed for the fourth release condition can be set to any value as long as it is higher than the predetermined speed for the third release condition. For example, the predetermined speed for the fourth release condition can be set to any value within the range of 3 [km / h] to 5 [km / h].

[0074] <Transition from a restricted start state to a prohibited start state> When the forklift 10 is in the restricted starting state S2, if the condition for prohibiting starting is met, the control device 81 transitions the state of the forklift 10 from the restricted starting state S2 to the prohibited starting state S3. The condition for prohibiting starting is met when all of the following conditions are met: the first prohibition condition, the second prohibition condition, and the third prohibition condition. When the forklift 10 is in the restricted starting state S2, if both the prohibited starting condition and the condition for releasing the restricted starting condition are met, the control device 81 prioritizes the condition for releasing the restricted starting condition and transitions the forklift 10 to the normal control state S10.

[0075] First prohibition condition: An object is present in the area where forklift 10 is scheduled to travel. Second prohibition condition: Forklift 10 is stopped. Third prohibition condition: Direction lever 88 is in the reverse position.

[0076] Whether or not the first prohibition condition is met can be determined from the detection result of the tire angle sensor 86 and the X and Y coordinates of the object. The planned area of ​​travel for the forklift 10 is the area in the central area N, left area NL, and right area NR where the forklift 10 is expected to travel. A left turn is determined when the angle of the steering wheel 14 detected by the tire angle sensor 86 is greater than or equal to a predetermined angle in the left turn direction. A right turn is determined when the angle of the steering wheel 14 detected by the tire angle sensor 86 is greater than or equal to a predetermined angle in the right turn direction. The predetermined angle used to determine left and right turns can be arbitrarily set from, for example, the range of 4° to 6°. A straight turn is determined when the angle of the steering wheel 14 detected by the tire angle sensor 86 is less than the predetermined angle. In the case of a straight turn, the planned area of ​​travel is the central area N. In the case of a left turn, the planned areas of travel are the left area NL and the central area N. In the case of a right turn, the planned areas of travel are the right area NR and the central area N. The control device 81 determines that the first prohibition condition is met if the regions N, NL, NR in which an object exists coincide with the planned travel region. If one object is located across multiple regions N, NL, NR, or if multiple objects are located in different regions N, NL, NR, the control device 81 determines that an object exists in each of the regions N, NL, NR. In this case, the control device 81 determines that the first prohibition condition is met if any of the regions N, NL, NR in which an object exists coincide with the planned travel region.

[0077] The second prohibition condition is the same as the second restriction condition. The third prohibition condition can be determined by input from the direction switch 90 to the control device 81.

[0078] When the first and third prohibition conditions are met, the object detection unit 131 has detected an object behind the forklift, and the direction of travel determined by the direction lever 88 is the reverse direction. That is, the direction of object detection and the direction of travel determined by the direction lever 88 coincide. The control device 81 can be said to put the forklift 10 into the no-start state S3 when the object detection unit 131 has detected an object, the direction of object detection and the direction of travel determined by the direction lever 88 coincide, and the vehicle speed of the forklift 10 is below the stop judgment threshold.

[0079] <Transition from "departure prohibited" state to "forced operation" state> When the forklift 10 is in the prohibited-start state S3, and the conditions for forced operation are met, the control device 81 transitions the state of the forklift 10 from the prohibited-start state S3 to the forced operation state S4. In other words, the control device 81 releases the prohibited-start state S3 and puts the forklift 10 into the forced operation state S4.

[0080] Forced operation conditions: Direction lever 88 is in the neutral position, and the engine speed 31 is below a predetermined speed. In the no-start state S3, the direction lever 88 is in the reverse position. Therefore, when the direction lever 88 is in the neutral position, it can be said that the direction of travel determined by the direction lever 88 has been changed. The change in the direction of travel determined by the direction lever 88 includes changing the direction of travel of the forklift 10 from the reverse direction to the state in which the forklift 10 does not move. The predetermined rotational speed is set so as to suppress sudden acceleration when transitioning from the no-start state S3 to the forced operation state S4. For example, the predetermined rotational speed can be set to idle speed + 100 to 200 [rpm].

[0081] <Transition from forced operation state to normal control state> When the forklift 10 is in the forced operation state S4, if the forced operation release condition is met, the control device 81 transitions the state of the forklift 10 from the forced operation state S4 to the normal control state S10.

[0082] Condition for canceling forced operation: Direction lever 88 is in the forward position. The condition for canceling the forced operation may also be that the forklift 10 stops moving. Stopping means that the speed of the forklift 10 changes from a state where it is higher than the stop judgment threshold to a state where it is lower than or equal to the stop judgment threshold.

[0083] When the forklift 10 is in the forced operation state S4, even if the direction lever 88 is moved to the reverse position, the control device 81 does not transition the forklift 10 to the prohibited start state S3. In the forced operation state S4, even if the direction of travel determined by the direction lever 88 is returned to the direction of travel before the prohibited start state S3 was released after the prohibited start state S3 is released, the forced operation state S4 is maintained.

[0084] <effect> The operation of this embodiment will now be described. In the starting restriction state S2, the forklift 10 enters the starting prohibited state S3 when the first to third prohibition conditions are met. The first to third prohibition conditions are met when the object detection unit 131 detects an object and the direction of the detected object matches the direction of travel determined by the direction lever 88. Let's assume that the third prohibition condition is set to accelerator off. In the forklift 10, the accelerator is turned on after the direction of travel is determined by the direction lever 88. If the third prohibition condition is set to accelerator off, the transition from the starting restriction state S2 to the starting prohibited state S3 does not occur when the direction lever 88 is in the reverse position. As a result, there is a risk that the forklift 10 will start due to creep. In contrast, by setting the third prohibition condition as in the embodiment, the transition from the starting restriction state S2 to the starting prohibited state S3 occurs when the direction lever 88 is in the reverse position. In the no-start state S3, the driving force is cut off by putting the power transmission mechanism 40 into a non-driving state.

[0085] <Effects> The effects of this embodiment will now be explained. (1) In the no-start state S3, the power transmission mechanism 40 is set to a non-drive state, thereby preventing creep from occurring in the no-start state S3. Starting of the forklift 10 due to creep is suppressed. Contact between objects and the forklift 10 can be suppressed.

[0086] (2) When the forklift 10 is in the prohibited-start state S3, if the conditions for forced operation are met, the control device 81 releases the prohibited-start state S3 and transitions the forklift 10 to the forced operation state S4. In the forced operation state S4, even if the direction of travel determined by the direction lever 88 is returned to the direction of travel before the prohibited-start state S3 was released after the prohibited-start state S3 is released, the forced operation state S4 is maintained. In this embodiment, before releasing the prohibited-start state S3 by setting the direction lever 88 to the neutral position, the direction lever 88 is in the reverse position. Even if the direction lever 88 is returned to the reverse position after releasing the prohibited-start state S3 by setting the direction lever 88 to the neutral position, the forced operation state S4 is maintained. The forced operation state S4 is a state in which the forklift 10 can move. Therefore, even if there is an object in the restricted-start area AA1, the forklift 10 can be started, and a decrease in work efficiency can be suppressed.

[0087] (3) Forced operation state S4 is a state in which progress at a vehicle speed limit of VS1 or less is permitted. In forced operation state S4, there is a high probability that an object is present in the starting restriction area AA1. In such cases, by setting the vehicle speed limit of VS1, the forklift 10 can be started while suppressing contact between the forklift 10 and the object.

[0088] (4) When the forklift 10 is in the no-start state S3, the control device 81 forces the forklift 10 into the forced operation state S4 if the direction lever 88 is in the neutral position and the rotational speed of the engine 31 is below a predetermined rotational speed. This prevents the forklift 10 from entering the forced operation state S4 when the rotational speed of the engine 31 is above the predetermined rotational speed. In the forced operation state S4, the forklift 10 is allowed to move, so if the forklift 10 enters the forced operation state S4 when the rotational speed of the engine 31 is above the predetermined rotational speed, there is a risk that the forklift 10 will suddenly start. By forcing the forklift 10 into the forced operation state S4 when the rotational speed of the engine 31 is below the predetermined rotational speed, sudden starts of the forklift 10 can be suppressed. In addition, excessive driving force can be prevented from being applied to the power transmission mechanism 40. This reduces the load on the power transmission mechanism 40.

[0089] (5) In the forced operation state S4, progress is permitted with a restriction on the rotational speed of the engine 31. In the forced operation state S4, there is a possibility that an object is present in the starting restriction area AA1. By restricting the rotational speed of the engine 31, it is possible to prevent the forklift 10 from passing near an object at a high speed.

[0090] Furthermore, if the vehicle speed is maintained below the vehicle speed limit VS1, the engine speed of the engine 31 will decrease, which may lead to engine stall. If the engine speed of the engine 31 is at idle speed, engine stall can be suppressed by allowing the forklift 10 to move at a vehicle speed exceeding the vehicle speed limit VS1.

[0091] <Example of changes> The embodiment can be implemented with the following modifications. The embodiment and the following modifications can be combined with each other to the extent that they do not contradict the technical principles.

[0092] As shown in Figure 7, the drive system 30 may also include a brake mechanism 200. The brake mechanism 200 includes a brake actuator 201, a brake wheel cylinder 202, and a brake controller 203.

[0093] The brake actuator 201 is an actuator that controls the hydraulic fluid supplied to the brake wheel cylinder 202. The brake actuator 201 controls the supply of hydraulic fluid, for example, by a solenoid valve.

[0094] The brake wheel cylinder 202 is located on the drive wheel 12. The brake wheel cylinder 202 may also be located on the steering wheel 14. The brake wheel cylinder 202 generates frictional braking force by pressing the brake pad against the brake disc using hydraulic fluid supplied from the brake actuator 201.

[0095] The hardware configuration of the brake controller 203 is, for example, similar to that of the driving control device 63. The brake controller 203 controls the brake actuator 201 based on commands from the control device 81. The control device 81 can control the brake mechanism 200 by sending commands to the brake controller 203.

[0096] The control device 81 may, instead of disabling the power transmission mechanism 40 when the starting prohibited state S3 is reached, apply a braking force to the forklift 10 by controlling the brake mechanism 200. This suppresses the forklift 10 from starting due to creep. In addition to disabling the power transmission mechanism 40 when the starting prohibited state S3 is reached, the control device 81 may also apply a braking force to the forklift 10 by controlling the brake mechanism 200.

[0097] ○The control device 81 may disable the first forward relay 111 and the first reverse relay 112 when the forklift 10 is in the start-prohibited state S3, thereby putting the power transmission mechanism 40 into a non-drive state. In this case, the forklift 10 does not need to be equipped with the second forward relay 121 and the second reverse relay 122.

[0098] ○The control device 81 may, when the forklift 10 is in the no-start state S3, use an inching valve to put the power transmission mechanism 40 into a non-drive state. The inching valve adjusts whether the driving force of the engine 31 is distributed to the power transmission mechanism 40 or to the hydraulic pump 72. The power transmission mechanism 40 may be put into a non-drive state by preventing the driving force of the engine 31 from being distributed to the power transmission mechanism 40 using the inching valve. Furthermore, any means are acceptable as long as the driving force transmitted to the drive wheels 12 is adjusted by controlling the rotational speed of the engine 31. For example, the throttle valve used to control the rotational speed of the engine 31 and controlled by the throttle actuator 32 of this embodiment is referred to as the first throttle valve. The engine 31 may also have a second throttle valve in addition to the first throttle valve. The second throttle valve is provided in series with the intake path. The control device 81 may close the opening of the second throttle valve when putting the power transmission mechanism 40 into a non-drive state.

[0099] ○The power transmission mechanism 40 may be configured to switch between a power transmission state and a power non-transmission state by a command from the control device 81. In this case, if the forklift 10 is in the no-start state S3, the control device 81 may give a command to the power transmission mechanism 40 to put the power transmission mechanism 40 into a power non-transmission state.

[0100] ○The first prohibition condition may also be "an object is present in the starting restriction area AA1." The starting restriction area AA1 extends from the position of the stereo camera 132 to the rear of the forklift 10. Therefore, even if the first prohibition condition is set as described above, if the first and third prohibition conditions are met, the object detection unit 131 has detected an object behind the forklift, and the direction of travel determined by the direction lever 88 can be said to be the reverse direction.

[0101] ○The forced operation conditions may be changed to any of the following. Alternatively, the forced operation conditions may be a combination of the forced operation conditions of the embodiment and the following forced operation conditions. When the forced operation conditions are a combination of multiple forced operation conditions, the control device 81 transitions the forklift 10 to the forced operation state S4 when at least one of the multiple forced operation conditions is met.

[0102] Forced operation conditions: Direction lever 88 is in the neutral position and the accelerator is off. Forced operation conditions: With the accelerator released, change the direction lever 88 from the neutral position to the reverse position.

[0103] Even if the forced operation conditions are changed as described above, it is possible to suppress the forklift 10 from entering forced operation state S4 when the engine 31 is rotating at a high speed. In particular, if the forced operation condition is to change the direction lever 88 from the neutral position to the reverse position while the accelerator is off, the forklift 10 will enter forced operation state S4 when the direction lever 88 is moved to the reverse position while the accelerator is off. Before the direction lever 88 is moved to the reverse position, the engine 31's rotational speed increases when the accelerator is turned on, and it is possible to suppress the direction lever 88 from being moved to the reverse position while in this state. Therefore, it is possible to further suppress the forklift 10 from entering forced operation state S4 when the engine 31 is rotating at a high speed.

[0104] ○The forced operation condition may also be "direction lever 88 is in the neutral position". ○The forced operation condition may also be "the direction lever 88 is in the forward position." Thus, the change in the direction of travel determined by the direction lever 88 includes changing from the reverse direction to the forward direction.

[0105] ○In forced operation state S4, a restriction may be imposed so that the rotational speed of the engine 31 does not exceed the limited rotational speed. The limited rotational speed is a rotational speed higher than the idle speed. ○The control device 81 may send a torque command to the travel control device 63 instead of a rotational speed command. The torque command includes a target torque. The control device 81 increases the target torque as the accelerator opening is larger. The travel control device 63 controls the throttle actuator 32 so that the torque of the engine 31 follows the target torque.

[0106] ○The object detection unit 131 may detect the position of an object located in the forward direction of the forklift 10. In this case, the stereo camera 132 is positioned facing forward of the forklift 10. When the object detection unit 131 detects the position of an object located in the forward direction of the forklift 10, the starting restriction area AA1 becomes an area that extends forward from the forklift 10. In this case, the starting restriction control is performed by reversing the "rear" and "forward" controls described in the embodiment.

[0107] The object detection unit 131 may be capable of detecting the position of an object in either the reverse or forward direction of the forklift 10's movement. For example, a stereo camera for forward movement and a stereo camera for reverse movement may be provided, or a fisheye camera may be provided. In this case, the starting restriction area AA1 includes a forward area extending forward from the forklift 10 and a rear area extending backward from the forklift 10. The control device 81 may put the forklift 10 into a starting prohibition state S3 if the forklift 10 is stopped, an object is present in the forward area, and the direction lever 88 is in the forward position. The control device 81 may also put the forklift 10 into a starting prohibition state S3 if the forklift 10 is stopped, an object is present in the rear area, and the direction lever 88 is in the reverse position.

[0108] ○The direction-determining unit can be any type, as long as it can be operated by the operator of the forklift 10. The direction-determining unit may be, for example, a push button. The object detection unit 131 may use a ToF (Time of Flight) camera, LIDAR (Laser Imaging Detection and Ranging), millimeter-wave radar, etc., instead of the stereo camera 132. The object detection unit 131 may also be equipped with a combination of multiple sensors, such as the stereo camera 132 and LIDAR.

[0109] ○The alarm device 136 may be provided by a component other than the object detection unit 131. ○The alarm device 136 may be operated directly by the control device 81. ○ Forklift 10 may be one that can switch between automatic and manual operation.

[0110] ○As engine-powered industrial vehicles, any type of vehicle used for work in a limited area is acceptable, such as a towing vehicle used for transporting goods, or an order picker used for picking operations. In other words, engine-powered industrial vehicles do not need to be equipped with a cargo handling device 20 for unloading or loading goods. [Explanation of symbols]

[0111] 10...Forklift, an engine-powered industrial vehicle; 12...Drive wheels; 31...Engine; 40...Power transmission mechanism; 81...Control device; 88...Direction lever, which determines the direction of travel; 131...Object detection unit.

Claims

1. The engine and A power transmission mechanism that transmits the driving force of the engine to the drive wheels, An engine-powered industrial vehicle comprising a control device for adjusting the driving force transmitted to the drive wheels, A direction determination unit that determines the direction of travel of the engine-powered industrial vehicle by being operated to a forward position that instructs forward movement or a reverse position that instructs reverse movement, based on a neutral position, The vehicle includes an object detection unit that detects the position of an object in the direction of travel of the aforementioned engine-powered industrial vehicle, The power transmission mechanism is switchable between a drive transmission state in which the driving force of the engine is transmitted to the power transmission mechanism, and a drive non-transmission state in which the driving force of the engine is not transmitted to the power transmission mechanism. The control device is When the object detection unit has detected the object, and the direction of detection of the object matches the direction of travel determined by the direction of travel determination unit, and the vehicle speed of the engine-powered industrial vehicle is below the stop determination threshold, the engine-powered industrial vehicle is put into a state where starting is prohibited. If the engine-powered industrial vehicle is in the "no starting" state, and the direction of travel determined by the direction of travel determination unit is changed, and the engine speed is below a predetermined speed, the "no starting" state is released. An engine-powered industrial vehicle, wherein the aforementioned start-prohibition state includes at least one of the state in which the power transmission mechanism is changed to the non-drive transmission state, and the state in which a braking force is applied to the engine-powered industrial vehicle.

2. The control device is When the aforementioned start-prohibition state is released, the engine-powered industrial vehicle is forced into operation. If the engine-driven industrial vehicle is in the forced operation state, even if the direction of travel determined by the direction of travel determination unit returns to the direction of travel before the start prohibition state was released after the start prohibition state is released, the forced operation state is maintained. The aforementioned start-prohibition state is a state in which the power transmission mechanism is changed to the non-drive transmission state. The engine-powered industrial vehicle according to claim 1, wherein the forced operation state is a state in which the engine-powered industrial vehicle is made capable of moving by forcibly putting the power transmission mechanism into the drive transmission state.

3. The aforementioned forced operation state is a state in which the vehicle speed limit is set. The engine-powered industrial vehicle according to claim 2, wherein when the engine-powered industrial vehicle is in the forced operation state, the control device allows it to proceed at a speed less than or equal to the higher of the vehicle speed corresponding to the upper limit of the vehicle speed and the vehicle speed corresponding to the idle speed of the engine.

Images