Engine-powered forklift

Abstract

To suppress contact between an object and an engine type industrial vehicle.SOLUTION: A forklift includes an engine, a power transmission mechanism, a control device, a direction lever, and an object detection part. The direction lever determines a travel direction of the forklift according to an operation position. The object detection part detects the position of an object existing in the travel direction of the forklift. The power transmission mechanism can be switched between a drive transmission state where drive force of the engine is transmitted to the power transmission mechanism, and a drive non-transmission state where the drive force of the engine is not transmitted to the power transmission mechanism. In the case where the object detection part detects the object and the object detection direction and the travel direction determined by a travel direction determination part coincide with each other, and vehicle speed of the forklift is equal to or less than a stop determination threshold, the control device sets the forklift to be in a start prohibition state S3. In the start prohibition state S3, the power transmission mechanism is set to be the drive non-transmission state.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to an engine-driven forklift Regarding. [Background technology]

[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 operating direction of a direction lever that indicates the direction of travel. The direction sensor detects whether the direction lever is being operated in a direction that indicates forward travel or in a direction that indicates reverse travel, based on the neutral position. The control device prohibits the industrial vehicle from starting if an object is present in the direction of travel of the industrial vehicle when starting the industrial vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-93124 Summary of the Invention [Problem to be solved by the invention]

[0004] Engine-powered industrial vehicles forklift In this case, if the direction lever is operated to a position other than the neutral position, the engine-driven forklift For this reason, engine-driven forklift Even though there is an object in the direction of travel of the engine-driven forklift The object and the engine forklift In this case, the engine-driven forklift When launching the object and the engine forklift It is necessary to appropriately suppress contact between the [Means for solving the problem]

[0005] Engine-powered system that solves the above problems forklift is an engine-type vehicle equipped with an engine, a power transmission mechanism that transmits the driving force of the engine to driving wheels, and a control device that adjusts the driving force transmitted to the driving wheels. forklift And, With the neutral position as the reference, it can be operated to a forward position to instruct forward movement or a reverse position to instruct reverse movement. The engine type forklift a direction determining unit for determining the direction of travel of the engine; forklift an object detection unit that detects the position of an object present in the traveling direction of the vehicle; The power transmission mechanism includes a torque converter and a transmission, and the transmission includes an input shaft to which driving force is transmitted from the torque converter, a forward clutch provided on the input shaft, a forward gear train that is connected to the input shaft when the forward clutch is in an engaged state and that is disconnected from the input shaft when the forward clutch is in a disengaged state, a reverse clutch provided on the input shaft, and a reverse gear train that is connected to the input shaft when the reverse clutch is in an engaged state and that is disconnected from the input shaft when the reverse clutch is in a disengaged state, 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 engine-powered forklift truck includes: a solenoid valve that controls supply and discharge of hydraulic oil to the forward clutch and the reverse clutch; a forward solenoid that switches between supplying and discharging hydraulic oil to the forward clutch by the solenoid valve, the forward solenoid supplying hydraulic oil from the solenoid valve to the forward clutch when the solenoid valve is energized; a reverse solenoid that switches between supplying and discharging hydraulic oil to the reverse clutch by the solenoid valve, the reverse solenoid supplying hydraulic oil from the solenoid valve to the reverse clutch when the solenoid valve is energized; a first forward relay provided in a forward connecting line that electrically connects a battery and the forward solenoid when the travel direction determination unit is in the forward position; a second forward relay provided in the forward connecting line; a first reverse relay provided in a reverse connecting line that electrically connects the battery and the reverse solenoid when the travel direction determination unit is in the reverse position; and a second reverse relay provided in the reverse connecting line. The control device When a switchback operation is not performed, the second forward relay and the second reverse relay are connected, and when the switchback operation is performed, the second forward relay and the second reverse relay are disconnected, When the object detection unit detects the object, and the detected direction of the object coincides with the traveling direction determined by the traveling direction determination unit, forklift When the vehicle speed is equal to or less than the stop determination threshold, forklift the traveling direction determining unit Even when the second forward relay and the second reverse relay are set to the forward position or the reverse position, the second forward relay and the second reverse relay are set to the disconnected state, so that the forward clutch and the reverse clutch can This is the state in which the power transmission mechanism is changed to the non-power transmission state.

[0006] If the object detection unit detects an object and the detected direction of the object matches the traveling direction determined by the traveling direction determination unit, forklift By starting the engine forklift In this case, engine-driven forklift In the start-prohibited state, the drive force is cut off by putting the power transmission mechanism into a non-transmitting state. Decision This reduces the engine speed due to creep. forklift The launch of the object and the engine forklift This can suppress contact.

[0007] The above engine type forkliftRegarding the above, the control device forklift When the traveling direction determined by the traveling direction determination unit is changed in the case where the traveling direction ... forklift is forced into an operating state, and the engine-type forklift In the forced operation state, even if the traveling direction determined by the traveling direction determination unit is returned to the traveling direction before the start prohibition state was released after the start prohibition state is released, the forced operation state is maintained, and the forced operation state is By forcibly putting the power transmission mechanism into the drive transmission state, The engine type Forklift possible to progress to It may be in a state.

[0008] The above engine type forklift Regarding the above, the forced operation state may be a state in which travel at a vehicle speed equal to or lower than an upper vehicle speed limit value is permitted. The above engine type forklift Regarding the above, the control device forklift When the start prohibition state is in effect, the traveling direction determined by the traveling direction determination unit is changed, and when the rotation speed of the engine is less than a predetermined rotation speed, the start prohibition state is released and the engine type forklift may be in the forced operating state.

[0009] The above engine type forklift In the forced operation state, the engine may be allowed to proceed with a limit imposed on the engine speed. [Effects of the Invention]

[0010] According to the present invention, an object and an engine-type forklift This can suppress contact. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view of a forklift. [Figure 2] FIG. 1 is a schematic diagram of a forklift. [Figure 3]FIG. 2 is a schematic diagram of a traveling system and a cargo handling system. [Figure 4] 10 is a flowchart illustrating an object detection process. [Figure 5] FIG. 2 is a diagram schematically illustrating a departure restriction area. [Figure 6] FIG. 4 is a state transition diagram of the start restriction control. [Figure 7] FIG. 10 is a schematic configuration diagram of a modified example of a forklift truck. DETAILED DESCRIPTION OF THE INVENTION

[0012] An embodiment of an engine-powered industrial vehicle will be described below. <Forklift> 1, a forklift 10 as an engine-powered industrial vehicle includes a vehicle 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.

[0013] The vehicle body 11 is provided with a head guard 15 provided above the driver's seat. The two drive wheels 12 are arranged at the front lower part of the vehicle body 11. The two drive wheels 12 are arranged spaced apart from each other in the vehicle width direction.

[0014] The two steering wheels 14 are arranged at the rear lower part of the vehicle body 11. The two steering wheels 14 are arranged spaced apart from each other in the vehicle width direction. <Loading equipment> The cargo handling device 20 includes a mast 21, a pair of forks 22, and a lift cylinder 23. The mast 21 is provided at the front of the vehicle body 11. The forks 22 are provided so that they can be raised and lowered together with the mast 21. A load is placed on the forks 22. The lift cylinder 23 is a hydraulic cylinder. The mast 21 is raised and lowered by extension and contraction of the lift cylinder 23. As the mast 21 is raised and lowered, the forks 22 are raised and lowered. The forklift 10 of this embodiment is operated by a rider to perform traveling and cargo handling operations.

[0015] <Forklift configuration> As shown in FIG. 2, the forklift 10 includes a traveling 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 line 101, a reverse connection line 102, a forward detection line 103, a reverse detection line 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.

[0016] <Driving system> 3, the traveling system 30 is a mechanism for propelling the forklift 10. The traveling system 30 includes an engine 31, an output shaft 33, a rotation speed sensor 34, a power transmission mechanism 40, a solenoid valve 50, a forward solenoid 51, a reverse solenoid 52, a differential 60, axles 61, a vehicle speed sensor 62, and a traveling control device 63.

[0017] <Engine> The engine 31 is a drive source for the traveling and loading / unloading operations of the forklift 10. In this embodiment, the engine 31 is a gasoline engine fueled by gasoline. The engine 31 is equipped with a throttle actuator 32. The throttle actuator 32 adjusts the throttle opening of a throttle valve (not shown) provided in the intake path so that the engine 31 follows a target rotation speed calculated from the opening of the accelerator pedal 84. The throttle opening is adjusted by the throttle actuator 32, thereby adjusting the amount of air to the engine 31. This controls the rotation speed of the engine 31. A diesel engine fueled by light oil may be used as the engine 31. An engine fueled by liquefied petroleum gas (compressed natural gas) may be used as the engine 31. An output shaft 33 is connected to the engine 31. The output shaft 33 is rotated by the drive of the engine 31.

[0018] <Rotational speed sensor> The rotation speed sensor 34 is provided on the output shaft 33. The rotation speed sensor 34 detects the rotation speed of the engine 31. The rotation speed of the engine 31 is the rotation speed of the output shaft 33. The rotation speed sensor 34 outputs an electric signal corresponding to the rotation speed of the output shaft 33 to the travel control device 63.

[0019] <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 .

[0020] <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 is rotated by the hydraulic oil discharged from the pump.

[0021] <Transmission> The transmission 42 includes 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 the torque converter 41. Driving force is transmitted from the torque converter 41 to the transmission 42 via the input shaft 43.

[0022] <Forward clutch and reverse clutch> The forward clutch 44 is provided on the input shaft 43. The forward gear train 45 is provided between the forward clutch 44 and the output shaft 48. The forward clutch 44 can be switched between an engaged state and a disengaged state. In the engaged state, the input shaft 43 and the forward gear train 45 are connected. In the disengaged state, the input shaft 43 and the forward gear train 45 are disengaged. 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, 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 disengaged, driving force is not 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.

[0023] 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 a disengaged state. In the engaged state, the input shaft 43 and the reverse gear train 47 are connected. In the disengaged state, the input shaft 43 and the reverse gear train 47 are disengaged. When the input shaft 43 and the reverse gear train 47 are connected by the reverse clutch 46, 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 connected to the reverse gear train 47, 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 disengaged, driving force is not 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.

[0024] <Solenoid valve> The solenoid valve 50 controls the supply and discharge of hydraulic oil to the forward clutch 44 and the reverse clutch 46. The supply and discharge of hydraulic oil by the solenoid valve 50 switches the clutches 44, 46 between an engaged state and a disengaged state.

[0025] <Forward solenoid and reverse solenoid> Solenoids 51 and 52 switch between supplying and discharging hydraulic oil to the clutches 44 and 46 via a solenoid valve 50. When the forward solenoid 51 is energized, hydraulic oil is supplied from the solenoid valve 50 to the forward clutch 44. When hydraulic oil is supplied to the forward clutch 44, the forward clutch 44 is in an engaged state. When the reverse solenoid 52 is energized, hydraulic oil is supplied from the solenoid valve 50 to the reverse clutch 46. When hydraulic oil is supplied to the reverse clutch 46, the reverse clutch 46 is in an engaged state.

[0026] A single electromagnetic directional control valve may be used as the solenoid valve 50. The electromagnetic directional control valve is a solenoid valve in which the spool switches to a position where hydraulic oil is supplied to the forward clutch 44 when the forward solenoid 51 is energized, and the spool switches to a position where hydraulic oil is supplied to the reverse clutch 46 when the reverse solenoid 52 is energized. When both the forward solenoid 51 and the reverse solenoid 52 are de-energized, the electromagnetic directional control valve switches the spool to a position where hydraulic oil is discharged from both clutches 44, 46. The hydraulic oil 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 well known.

[0027] 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 solenoid valves 50 are individually controlled by the forward solenoid 51 and the reverse solenoid 52 to supply hydraulic oil to and discharge hydraulic oil from both clutches 44, 46.

[0028] <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 in an engaged state, the driving force of the engine 31 is transmitted to the power transmission mechanism 40, thereby moving the forklift 10 forward. When either the forward clutch 44 or the reverse clutch 46 is in an engaged state, the drive transmission state is reached. When the forward clutch 44 and the reverse clutch 46 are in a disengaged state, the driving force of the engine 31 is not transmitted to the power transmission mechanism 40. When the forward clutch 44 and the reverse clutch 46 are in a disengaged state, the drive non-transmission state is reached.

[0029] <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. When the axle 61 rotates, the drive wheels 12 rotate, causing the forklift 10 to move forward. When the forward clutch 44 and the forward gear train 45 are engaged, the forklift 10 moves forward. When the reverse clutch 46 and the reverse gear train 47 are engaged, the forklift 10 moves backward.

[0030] <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 provided, 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 travel control device 63.

[0031] <Drive control device> The cruise control device 63 is an engine control unit that controls the engine 31. The cruise 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.

[0032] <Loading and unloading> 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 that stores hydraulic oil, a hydraulic pump 72, and a hydraulic mechanism 73.

[0033] <Hydraulic pump> The hydraulic pump 72 is driven by the engine 31. The hydraulic pump 72 pumps up hydraulic oil from the oil tank 71. The pumped up hydraulic oil is supplied to the hydraulic mechanism 73.

[0034] <Hydraulic mechanism> The hydraulic mechanism 73 includes a control valve. The control valve controls the supply and discharge of hydraulic oil to the hydraulic equipment. Examples of the hydraulic equipment include a lift cylinder 23 and a tilt cylinder that tilts the loading device 20. The loading device 20 operates by the supply and discharge of hydraulic oil. The hydraulic equipment may be any hydraulic equipment provided in the forklift 10 or may be any hydraulic equipment provided in the vehicle body 11.

[0035] <Control device> As shown in FIG. 2 , the control device 81 includes a processor 82 and a storage unit 83. Examples of the processor 82 include a central processing unit (CPU), a graphics processing unit (GPU), and a digital signal processor (DSP). The storage unit 83 includes a random access memory (RAM) and a read-only memory (ROM). The storage unit 83 stores program code or instructions configured to cause the processor 82 to execute processing. The storage unit 83, i.e., a computer-readable medium, includes any available medium accessible by a general-purpose or special-purpose computer. The control device 81 may be configured with a hardware circuit such as an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA). 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.

[0036] <Accelerator sensor> The accelerator sensor 85 detects the amount of operation of the accelerator pedal 84. The amount of operation of the accelerator pedal 84 can also be referred to as the accelerator opening. The accelerator sensor 85 outputs an electric signal corresponding to the accelerator opening to the control device 81. The control device 81 can recognize the accelerator opening from the electric signal from the accelerator sensor 85.

[0037] <Tire angle sensor> The tire angle sensor 86 detects the steering angle of the steered wheels 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.

[0038] <Seat sensor> The seating sensor 87 is a mechanism that is turned on when a passenger is seated in the driver's seat. The seating sensor 87 is provided, for example, under the driver's seat. The seating sensor 87 may be, for example, a switch, a pressure sensor, a weight sensor, an optical sensor, or a camera.

[0039] <Direction lever> The direction lever 88 determines the direction of travel of the forklift 10. The direction lever 88 is operated by the rider of the forklift 10. The direction lever 88 is operated to a forward position that commands forward travel or a reverse position that commands reverse travel, with the neutral position being used as a reference. For example, the forward position is a position where the direction lever 88 is tilted forward from the neutral position. The reverse position is a position where the direction lever 88 is tilted rearward from the neutral position. The direction lever 88 is a travel direction determination unit.

[0040] <Direction switch> The direction switch 90 switches depending on the operating direction of the direction lever 88. The direction switch 90 has one movable contact 91 and three fixed contacts 92, 93, and 94. The movable contact 91 is connected to the positive terminal of a 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.

[0041] <Forward and reverse connecting lines> 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 and the battery are electrically connected. This energizes the forward solenoid 51. When the movable contact 91 and the forward fixed contact 93 are connected, the reverse solenoid 52 is de-energized.

[0042] The reverse connection line 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 line 102 and the battery are electrically connected. This excites the reverse solenoid 52. When the movable contact 91 and the reverse fixed contact 94 are connected, the forward solenoid 51 is de-energized.

[0043] When the direction lever 88 is in the forward position, the forward solenoid 51 is energized, and hydraulic oil is supplied to the forward clutch 44, thereby enabling the forklift 10 to move forward. When the direction lever 88 is in the reverse position, the reverse solenoid 52 is energized, and hydraulic oil is supplied to the reverse clutch 46, thereby enabling the forklift 10 to move backward. When the direction lever 88 is in the neutral position, both solenoids 51, 52 are de-energized, and therefore hydraulic oil is not supplied to the clutches 44, 46. In this case, the driving force of the engine 31 is not transmitted to the power transmission mechanism 40.

[0044] <Forward detection line and backward detection line> The forward movement detection line 103 connects the forward movement connection line 101 and the control device 81. When voltage from the battery is applied to the forward movement connection line 101, voltage is applied to the control device 81 via the forward movement detection line 103. The reverse movement detection line 104 connects the reverse movement connection line 102 and the control device 81. When voltage from the battery is applied to the reverse movement connection line 102, voltage is applied to the control device 81 via the reverse movement detection line 104. When voltage is input from the forward movement detection line 103, the control device 81 can determine that the direction lever 88 is in the forward movement position. When voltage is input from the reverse movement detection line 104, the control device 81 can determine that the direction lever 88 is in the reverse movement position. When there is no voltage input from either the forward movement detection line 103 or the reverse movement detection line 104, the control device 81 can determine that the direction lever 88 is in the neutral position.

[0045] <First forward relay and first reverse relay> The first forward relay 111 is provided in the forward connection line 101. The first forward relay 111 is switched between a connected state and a disconnected state. When the first forward relay 111 is in a connected state, the forward connection line 101 and the forward solenoid 51 are electrically connected. When the first forward relay 111 is in a disconnected state, the forward connection line 101 and the forward solenoid 51 are electrically disconnected. The first reverse relay 112 is provided in the reverse connection line 102. The first reverse relay 112 is switched between a connected state and a disconnected state. When the first reverse relay 112 is in a connected state, the reverse connection line 102 and the reverse solenoid 52 are electrically connected. When the first reverse relay 112 is in a disconnected state, the reverse connection line 102 and the reverse solenoid 52 are electrically disconnected.

[0046] The first forward relay 111 and the first reverse relay 112 are switched between a connected state and a disconnected state by the control device 81. When the seat sensor 87 detects that a passenger is seated, the control device 81 switches the first forward relay 111 and the first reverse relay 112 to a connected state. When the seat sensor 87 detects no passenger is seated for a predetermined time or longer, the control device 81 switches the first forward relay 111 and the first reverse relay 112 to a disconnected state. The predetermined time can be set to any desired time. When the first forward relay 111 and the first reverse relay 112 are switched to a disconnected state, the solenoids 51, 52 are de-energized 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 drive non-transmitting state.

[0047] <Second forward relay and second reverse relay> The second forward relay 121 is provided in the forward connection line 101. The second forward relay 121 is switched between a connected state and a disconnected state. When the second forward relay 121 is in a connected state, the forward connection line 101 and the forward solenoid 51 are electrically connected. When the second forward relay 121 is in a disconnected state, the forward connection line 101 and the forward solenoid 51 are electrically disconnected. The second reverse relay 122 is provided in the reverse connection line 102. The second reverse relay 122 is switched between a connected state and a disconnected state. When the second reverse relay 122 is in a connected state, the reverse connection line 102 and the reverse solenoid 52 are electrically connected. When the second reverse relay 122 is in a disconnected state, the reverse connection line 102 and the reverse solenoid 52 are electrically disconnected.

[0048] The second forward relay 121 and the second reverse relay 122 are switched between a connected state and a disconnected state by the control device 81. When a switchback operation is not being performed, the control device 81 sets the second forward relay 121 and the second reverse relay 122 to a connected state. When a switchback operation is being performed, the control device 81 sets the second forward relay 121 and the second reverse relay 122 to a disconnected state. A switchback operation is an operation in which the traveling direction 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 traveling direction indicated by the direction lever 88 does not match the traveling direction of the forklift 10. When the second forward relay 121 and the second reverse relay 122 are set to a disconnected state, the solenoids 51 and 52 are de-energized regardless of the position of the direction lever 88, and the driving force of the engine 31 is not transmitted to the power transmission mechanism 40. In other words, the power transmission mechanism 40 is in a non-drive transmission state.

[0049] <Object detection unit> The object detection unit 131 includes a stereo camera 132, a detection device 133, and an alarm device 136. The stereo camera 132 includes two cameras and captures images using the two cameras. As shown in FIG. 1 , the stereo camera 132 is disposed on the head guard 15. The stereo camera 132 is disposed so as to provide a bird's-eye view of the road surface on which the forklift 10 is traveling from above the forklift 10. The stereo camera 132 of this embodiment captures images behind the forklift 10. Therefore, 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 rearward. The alarm device 136 and the detection device 133 may be united with the stereo camera 132 and disposed on the head guard 15 together with the stereo camera 132. The alarm device 136 and the detection device 133 may also be disposed in positions different from the head guard 15.

[0050] The detection device 133 includes a processor 134 and a storage unit 135. The processor 134 may be, for example, a CPU, a GPU, or a DSP. The storage unit 135 includes a RAM and a 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 codes or instructions configured to cause the processor 134 to execute processing. The storage unit 135, i.e., a computer-readable medium, includes any available medium accessible by a general-purpose or special-purpose computer. The detection device 133 may be configured by a hardware circuit such as an ASIC or FPGA. 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 an ASIC or FPGA, or a combination thereof.

[0051] <Object detection processing> The detection device 133 repeatedly performs the following object detection process at a predetermined control period to detect an object present behind the forklift 10. The detection device 133 also derives the position of the detected object. The object position is the relative position between the forklift 10 and the object.

[0052] As shown in FIG. 4, in step S100, the detection device 133 acquires an image from the stereo camera 132. Next, in step S110, the detection device 133 performs stereo processing to acquire a disparity image. A disparity image is one in which disparity [px] is associated with each pixel. A disparity image does not necessarily need to be displayed, but refers to data in which disparity is associated with each pixel in the disparity image. Disparity 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 the same feature point appearing in each image. A feature point is a part that can be recognized as a boundary, such as the edge of an object. Feature points can be detected from brightness information, etc.

[0053] Next, in step S120, the detection device 133 derives the coordinates of the feature points in a 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 a horizontal plane, an axis extending in the vehicle width direction of the forklift 10 is the X-axis, an axis perpendicular to the X-axis is the Y-axis, and an axis extending in the vertical direction is the Z-axis. The coordinates of the feature points are derived by deriving the coordinates of the feature points in the camera coordinate system from the base length of the stereo camera 132, the focal length of the stereo camera 132, and the parallax image obtained in step S110, and then converting the coordinates into coordinates in the world coordinate system. As shown in FIG. 1, the X-axis, Y-axis, and Z-axis are indicated by arrows X, Y, and Z.

[0054] As shown in FIG. 4, in step S130, the detection device 133 extracts an object by clustering feature points. The detection device 133 groups together a set of feature points, which are points that represent parts of an object, that are assumed to represent the same object into a single point cloud, and extracts the point cloud as an object. The detection device 133 performs clustering by regarding feature points located within a predetermined range from the coordinates of the feature points in the world coordinate system derived in step S120 as a single point cloud. The detection device 133 regards the clustered point cloud as a single object. Note that the clustering of feature points performed in step S130 can be performed using various methods.

[0055] 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, the X coordinate of the object's coordinates in the world coordinate system represents the left-right distance from the origin to the object, and the Y coordinate represents the front-rear distance from the origin to the object. The origin is, for example, a coordinate system in which the X and Y coordinates represent the placement position of the stereo camera 132 and the Z coordinate represents the road surface. It is also possible to derive the Euclidean distance from the placement position of the stereo camera 132 to the object from the X and Y coordinates. The Z coordinate of the object's coordinates in the world coordinate system represents the height of the object from the road surface.

[0056] <Alarm device> The warning device 136 is a device that issues a warning to the rider of the forklift 10. Examples of the warning device 136 include a buzzer that issues a warning by sound, a lamp that issues a warning by light, or a combination of these.

[0057] <Control performed by the control device> The control device 81, the driving control device 63, and the object detection unit 131 are configured to be able to acquire information from one another. The control device 81, the driving control device 63, and the object detection unit 131 acquire information from one another by communicating in accordance with a vehicle communication protocol such as CAN (Controller Area Network) or LIN (Local Interconnect Network).

[0058] 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, the steering angle detected by the tire angle sensor 86, etc. The detection result of the vehicle speed sensor 62 can be acquired from the travel control device 63. The gear ratio and the outer diameter of the drive wheels 12 may be stored in advance in the memory unit 83. The control device 81 derives the traveling direction of the forklift 10 as well as the vehicle speed of the forklift 10. The traveling direction of the forklift 10 is either the forward direction or the reverse direction.

[0059] The control device 81 activates the alarm device 136 by transmitting an alarm command to the object detection unit 131. In detail, the object detection unit 131 includes an activation unit that activates the alarm device 136, and the activation unit activates the alarm device 136 upon receiving the alarm command.

[0060] <Departure Restriction Area> The control device 81 performs start limit control. The start limit control is a control that is performed while the forklift 10 is stopped, and is a control that limits the start of the forklift 10 depending on the object detection status by the object detection unit 131. First, a start limit area used in the start limit control will be described.

[0061] 5, a start restriction area AA1 used for start restriction control is set within the range in which an object can be detected by the object detection unit 131. The range in which an object can be detected by the object detection unit 131 can also be said to be the range in which an image can be captured by the stereo camera 132. The start restriction area AA1 is an area that extends from the position in which the stereo camera 132 is disposed to the rear of the forklift 10 and in the vehicle width direction of the forklift 10. The start restriction area AA1 is an area defined by X and Y coordinates in the world coordinate system.

[0062] The departure restricted area AA1 is divided into three areas: a central area N, a left area NL located to the left of the central area N, and a 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 longitudinal direction. The left-right dimension of the central area N matches the widthwise dimension of the forklift 10. The central area N can also be said to be the area through which the forklift 10 passes when traveling straight backward. The left area NL can also be said to be the area through which the forklift 10 passes when turning left while traveling backward. The right area NR can also be said to be the area through which the forklift 10 passes when turning right while traveling backward. The longitudinal dimension of the departure restricted area AA1 and the left-right dimension of the departure restricted area AA1 can be adjusted as desired.

[0063] <Start Limit Control> As shown in FIG. 6, in the start restriction control, the control device 81 sets the state of the forklift 10 to one of a normal control state S10, a start restriction state S2, a start prohibition state S3, and a forced operation state S4, and performs control according to each state.

[0064] <Normal control state> The normal control state S10 is a state in which no vehicle speed limit is imposed. When the forklift 10 is in the normal control state S10, the control device 81 calculates a target rotation speed from the accelerator opening detected by the accelerator sensor 85. The target rotation speed increases as the accelerator opening increases. The control device 81 generates a rotation speed command from the target rotation speed. The control device 81 sends the rotation speed command to the cruise control device 63. The cruise control device 63 controls the engine 31 to follow the target rotation speed. More specifically, the cruise control device 63 adjusts the throttle opening by controlling the throttle actuator 32. This allows the forklift 10 to travel at a vehicle speed that corresponds to the amount of operation of the accelerator pedal 84 by the rider. In this way, the control device 81 can control the rotation speed of the engine 31 by sending a rotation speed command to the cruise control device 63. Controlling the rotation speed of the engine 31 can be said to adjust the driving force transmitted to the drive wheels 12. The control device 81 can be said to be able to adjust the driving force transmitted to the drive wheels 12.

[0065] <Start restriction state> The start restriction state S2 is a state in which the start of the forklift 10 from a stopped state is restricted when an object is present in the start restriction area AA1. Starting refers to transitioning the forklift 10 from a stopped state to a state in which the forklift 10 is moving forward. In the start restriction state S2, the start of the forklift 10 may be restricted by restricting the vehicle speed or by issuing an alarm using the alarm device 136.

[0066] <No start state> The start-prohibited state S3 is a state in which the forklift 10 is prohibited from starting. In the start-prohibited state S3, the control device 81 controls to cut off the driving force to the drive wheels 12. In the start-prohibited state S3, the control device 81 cuts off the second forward relay 121 and the second reverse relay 122, thereby putting the power transmission mechanism 40 into a non-driving state. This puts the traveling system 30 into a state similar to when the direction lever 88 is in the neutral position. More specifically, the clutches 44, 46 and the gear trains 45, 47 are not connected, and the driving force of the engine 31 is not transmitted to the power transmission mechanism 40. In the start-prohibited state S3, the alarm device 136 may issue a stronger warning than in the start-restricted state S2. For example, if the alarm device 136 is a buzzer, the buzzer sound may be increased. If the alarm device 136 is a combination of a lamp and a buzzer, the alarm may be switched from using either the lamp or the buzzer to using both.

[0067] <Forced operation state> The forced operation state S4 is a state in which a vehicle speed upper limit VS1 [km / h] is set to impose a vehicle speed limit on the forklift 10. The control device 81 controls the vehicle speed of the forklift 10 so that it does not exceed the vehicle speed upper limit VS1. The vehicle speed upper limit VS1 is a value greater than 0 and lower than the maximum vehicle speed that the forklift 10 can achieve. The vehicle speed upper limit VS1 can be set to any value between 1 [km / h] and 4 [km / h], for example. It can be said that the control device 81 allows the forklift 10 to travel at a speed equal to or lower than the vehicle speed upper limit VS1. In the forced operation state S4, travel 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 rotational speed. The control device 81 allows the vehicle speed to exceed the vehicle speed upper limit VS1 as long as the rotational speed of the engine 31 is the idle rotational speed. The forced operation state S4 can be said to be a state in which the forklift 10 is permitted to travel at a speed equal to or lower than the upper vehicle speed limit VS1 or the vehicle speed corresponding to the idle rotation speed, whichever is higher. In the forced operation state S4, the warning issued by the warning device 136 may be weaker than in the start prohibition state S3. In the forced operation state S4, the power transmission mechanism 40 is set to a drive transmission state. Note that the upper vehicle speed limit VS1 [km / h] does not need to be set in the forced operation state S4. In other words, the forced operation state S4 is sufficient as long as the forklift 10 is allowed to travel.

[0068] <Transition from normal control state to start restriction state> If the start restriction condition is satisfied when the forklift 10 is in the normal control state S10, the control device 81 transitions the state of the forklift 10 from the normal control state S10 to the start restriction state S2. The satisfaction of the start restriction condition means that the following first and second restriction conditions are satisfied.

[0069] First restriction condition: An object exists in the departure restriction area AA1. Second restriction condition: the forklift 10 is stopped. Whether the first restriction condition is met can be determined from the X and Y coordinates of the object. Because the departure restriction area AA1 is defined by the X and Y coordinates, it can be determined from the X and Y coordinates of the object whether the object is present in the departure restriction area AA1.

[0070] Whether or not the second restriction 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 when the vehicle speed is equal to or less than a stop determination threshold [km / h]. The stop determination threshold is set to a value at which the forklift 10 is considered to be stopped, and can be set to any value between 0 [km / h] and 0.5 [km / h], for example.

[0071] <Transition from start restriction state to normal control state> When the start restriction release condition is satisfied while the forklift 10 is in the start restriction state S2, the control device 81 transitions the state of the forklift 10 from the start restriction state S2 to the normal control state S10. The satisfaction of the start restriction release condition means that at least one of the following first release condition, second release condition, third release condition, and fourth release condition is satisfied.

[0072] First release condition: There are no objects in the departure restriction area AA1. Second release condition: the forklift 10 is moving forward at a speed equal to or greater than a predetermined speed. Third release condition: The forklift 10 continues to move backward at a speed equal to or greater than a predetermined speed for a predetermined period of time.

[0073] Fourth release condition: The forklift 10 is moving backward at a speed equal to or greater than a predetermined speed. The predetermined speed for the second cancellation condition can be set to any value as long as it is higher than the stop determination threshold value. For example, the predetermined speed for the second cancellation condition can be set to any value within the range of 1 km / h to 2 km / h.

[0074] The predetermined speed of the third cancellation condition can be set to any value as long as it is higher than the stop determination threshold. The predetermined speed of the third cancellation condition can be set to any value within the range of 1 km / h to 2 km / h, for example. The predetermined time of the third cancellation condition can be set to any value within the range of 1 second to 2 seconds, for example.

[0075] The predetermined speed for the fourth cancellation condition can be set to any value as long as it is higher than the predetermined speed for the third cancellation condition. The predetermined speed for the fourth cancellation condition can be set to any value within the range of 3 km / h to 5 km / h, for example.

[0076] <Transition from start restriction state to start prohibition state> If a start prohibition condition is met when the forklift 10 is in the start restricted state S2, the control device 81 transitions the state of the forklift 10 from the start restricted state S2 to the start prohibited state S3. The start prohibition condition is met when all of the following first prohibition condition, second prohibition condition, and third prohibition condition are met. If both the start prohibition condition and the start restriction release condition are met when the forklift 10 is in the start restricted state S2, the control device 81 prioritizes the start restriction release condition and transitions the forklift 10 to the normal control state S10.

[0077] First prohibition condition: An object exists in the area where the forklift 10 is scheduled to move. Second prohibition condition: the forklift 10 is stopped. Third prohibited condition: The direction lever 88 is in the reverse position.

[0078] Whether 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 expected travel area of ​​the forklift 10 is the area among the center area N, left area NL, and right area NR into which the forklift 10 is expected to travel. A left turn is determined when the angle of the steering wheels 14 detected by the tire angle sensor 86 is equal to or greater than a predetermined angle in the left turn direction. A right turn is determined when the angle of the steering wheels 14 detected by the tire angle sensor 86 is equal to or greater than a predetermined angle in the right turn direction. The predetermined angle used to determine left and right turns can be set arbitrarily, for example, within a range of 4° to 6°. A straight drive is determined when the angle of the steering wheels 14 detected by the tire angle sensor 86 is less than the predetermined angle. The expected travel area for straight drive is the center area N. The expected travel areas for left turns are the left area NL and center area N. The expected travel areas for right turns are the right area NR and center area N. The control device 81 determines that the first prohibition condition is met when the area N, NL, NR where the object exists matches the planned travel area. When one object is located across multiple areas N, NL, NR, or when multiple objects are located in different areas N, NL, NR, the control device 81 determines that the object is present in each of the areas N, NL, NR. In this case, the control device 81 determines that the first prohibition condition is met when any of the areas N, NL, NR where the object exists matches the planned travel area.

[0079] The second prohibition condition is the same as the second restriction condition. The third prohibition condition can be determined by an input from the direction switch 90 to the control device 81.

[0080] The first and third prohibition conditions are satisfied when the object detection unit 131 detects an object behind the forklift 10 and the traveling direction determined by the direction lever 88 is a reverse direction. In other words, the detected direction of the object matches the traveling direction determined by the direction lever 88. When the object detection unit 131 detects an object and the detected direction of the object matches the traveling direction determined by the direction lever 88, and the vehicle speed of the forklift 10 is equal to or lower than the stop determination threshold, the control device 81 can be said to put the forklift 10 into the start prohibition state S3.

[0081] <Transition from start prohibition state to forced operation state> If the forced operation condition is met while the forklift 10 is in the start prohibition state S3, the control device 81 transitions the state of the forklift 10 from the start prohibition state S3 to the forced operation state S4. It can be said that the control device 81 releases the start prohibition state S3 and puts the forklift 10 into the forced operation state S4.

[0082] Forced operation condition: The direction lever 88 is in the neutral position, and the rotation speed of the engine 31 is less than a predetermined rotation speed. In the start-prohibited state S3, the direction lever 88 is in the reverse position, so when the direction lever 88 is in the neutral position, it can be said that the traveling direction determined by the direction lever 88 has changed. A change in the traveling direction determined by the direction lever 88 includes a change from a state in which the traveling direction of the forklift 10 is in reverse to a state in which the forklift 10 does not move forward. The predetermined rotation speed is set so as to suppress sudden acceleration when the start-prohibited state S3 transitions to the forced operation state S4. An example of the predetermined rotation speed is the idle rotation speed + 100 to 200 [rpm].

[0083] <Transition from forced operation state to normal control state> If the forced operation release condition is met while the forklift 10 is in the forced operation state S4, the control device 81 transitions the state of the forklift 10 from the forced operation state S4 to the normal control state S10.

[0084] Condition for canceling forced operation: The direction lever 88 is in the forward position. The forced operation cancellation condition may be the stop of the forklift 10. The stop of the forklift 10 occurs when the vehicle speed of the forklift 10 goes from a state higher than the stop determination threshold to a state lower than or equal to the stop determination threshold.

[0085] When the forklift 10 is in the forced operation state S4, the control device 81 does not transition the forklift 10 to the start prohibition state S3 even if the direction lever 88 is moved to the reverse position. In the forced operation state S4, even if the traveling direction determined by the direction lever 88 is returned to the traveling direction before the start prohibition state S3 was released after the start prohibition state S3 was released, the forced operation state S4 can be said to be maintained.

[0086] <effect> The operation of this embodiment will be described. In the start restricted state S2, the forklift 10 enters the start prohibited state S3 when the first to third prohibited conditions are satisfied. The first to third prohibited conditions are satisfied when the object detection unit 131 detects an object and the detected direction of the object matches the traveling direction determined by the direction lever 88. Let us assume that the third prohibited condition is set to accelerator off. In the forklift 10, the accelerator is turned on after the traveling direction is determined by the direction lever 88. When the third prohibited condition is set to accelerator off, the start restricted state S2 does not transition to the start prohibited state S3 when the direction lever 88 is shifted to the reverse position. This may result in the forklift 10 starting due to creep. In contrast, by setting the third prohibited condition as in the embodiment, the start restricted state S2 transitions to the start prohibited state S3 when the direction lever 88 is shifted to the reverse position. In the start inhibition state S3, the power transmission mechanism 40 is set in a drive non-transmission state, thereby cutting off the driving force.

[0087] <Effects> The effects of this embodiment will be described. (1) By placing the power transmission mechanism 40 in a non-driving state in the start-prohibited state S3, creep is prevented from occurring in the start-prohibited state S3. This prevents the forklift 10 from starting due to creep. This prevents the forklift 10 from coming into contact with an object.

[0088] (2) When the forklift 10 is in the start-prohibited state S3 and the forced operation condition is met, the control device 81 releases the start-prohibited state S3 and transitions the forklift 10 to the forced operation state S4. In the forced operation state S4, even if the traveling direction determined by the direction lever 88 is returned to the traveling direction before the start-prohibited state S3 was released after the start-prohibited state S3 was released, the forced operation state S4 is maintained. In this embodiment, before the direction lever 88 is set to the neutral position to release the start-prohibited state S3, the direction lever 88 is in the reverse position. Even if the direction lever 88 is set to the neutral position to release the start-prohibited state S3 and then the direction lever 88 is set to the reverse position, the forced operation state S4 is maintained. The forced operation state S4 is a state in which the forklift 10 is allowed to travel. Therefore, even if an object is present in the start-restricted area AA1, the forklift 10 can be started, thereby preventing a decrease in work efficiency.

[0089] (3) The forced operation state S4 is a state in which the forklift 10 is permitted to travel at a speed equal to or less than the upper vehicle speed limit VS1. In the forced operation state S4, there is a high possibility that an object is present in the departure restriction area AA1. In such a case, by setting the upper vehicle speed limit VS1, the forklift 10 can be started while preventing contact between the forklift 10 and the object.

[0090] (4) When the forklift 10 is in the start prohibition state S3, the control device 81 puts the forklift 10 into the forced operation state S4 if the direction lever 88 is in the neutral position and the engine 31 rotation speed is less than a predetermined rotation speed. This prevents the forklift 10 from entering the forced operation state S4 when the engine 31 rotation speed is equal to or greater than the predetermined rotation speed. In the forced operation state S4, the forklift 10 is permitted to move forward. Therefore, if the forced operation state S4 is entered when the engine 31 rotation speed is equal to or greater than the predetermined rotation speed, the forklift 10 may suddenly start moving. By putting the forklift 10 into the forced operation state S4 when the engine 31 rotation speed is less than the predetermined rotation speed, it is possible to prevent the forklift 10 from suddenly starting moving. In addition, it is possible to prevent excessive driving force from being applied to the power transmission mechanism 40. This reduces the load on the power transmission mechanism 40.

[0091] (5) In the forced operation state S4, the forklift 10 is allowed to proceed with a limit imposed on the rotation speed of the engine 31. In the forced operation state S4, there is a risk that an object may be present in the departure restriction area AA1. By imposing a limit on the rotation speed of the engine 31, it is possible to prevent the forklift 10 from passing near the object while traveling at a high speed.

[0092] Furthermore, if an attempt is made to maintain the vehicle speed at or below the upper vehicle speed limit VS1, the rotation speed of the engine 31 will decrease, which may result in an engine stall. If the rotation speed of the engine 31 is an idle rotation speed, engine stall can be prevented by allowing the forklift 10 to travel at a vehicle speed exceeding the upper vehicle speed limit VS1.

[0093] <Example of change> The embodiment can be modified as follows: The embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0094] 7, the propulsion system 30 may include a brake mechanism 200. The brake mechanism 200 includes a brake actuator 201, a brake wheel cylinder 202, and a brake controller 203.

[0095] The brake actuator 201 is an actuator that controls the hydraulic oil supplied to the brake wheel cylinder 202. The brake actuator 201 controls the supply of the hydraulic oil by, for example, a solenoid valve.

[0096] The brake wheel cylinder 202 is provided on the driving wheel 12. The brake wheel cylinder 202 may be provided on the steered wheel 14. The brake wheel cylinder 202 presses the brake pad against the brake disc using hydraulic oil supplied from the brake actuator 201, thereby generating a frictional braking force.

[0097] The hardware configuration of the brake controller 203 is similar to that of, for example, the driving control device 63. The brake controller 203 controls the brake actuator 201 in response to a command from the control device 81. It can be said that the control device 81 can control the brake mechanism 200 by sending a command to the brake controller 203.

[0098] During the start-prohibited state S3, the control device 81 may apply a braking force to the forklift 10 by controlling the brake mechanism 200 instead of placing the power transmission mechanism 40 in the drive non-transmitting state. This prevents the forklift 10 from starting due to creep. During the start-prohibited state S3, the control device 81 may apply a braking force to the forklift 10 by controlling the brake mechanism 200 in addition to placing the power transmission mechanism 40 in the drive non-transmitting state.

[0099] When the forklift 10 is in the start-prohibited state S3, the control device 81 may set the power transmission mechanism 40 in a drive-disconnected state by disconnecting the first forward relay 111 and the first reverse relay 112. In this case, the forklift 10 may not be provided with the second forward relay 121 and the second reverse relay 122.

[0100] When the forklift 10 is in the start-prohibited state S3, the control device 81 may place the power transmission mechanism 40 in a drive-disconnected state using an inching valve. 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 placed in a drive-disconnected state by preventing the driving force of the engine 31 from being distributed to the power transmission mechanism 40 using the inching valve. Any means may be used as long as the rotation speed of the engine 31 is controlled to adjust the driving force transmitted to the drive wheels 12. For example, the throttle valve used to control the rotation speed of the engine 31 and controlled by the throttle actuator 32 in the embodiment is referred to as the first throttle valve. The engine 31 may be provided with a second throttle valve in addition to the first throttle valve. The second throttle valve is provided in series in the intake path. The control device 81 may close the opening of the second throttle valve when placing the power transmission mechanism 40 in a drive-disconnected state.

[0101] The power transmission mechanism 40 may be configured to switch between a power transmission state and a power non-transmission state in response to a command from the control device 81. In this case, when the forklift 10 is in the start-prohibited state S3, the control device 81 may issue a command to the power transmission mechanism 40 to place the power transmission mechanism 40 in the power non-transmission state.

[0102] The first prohibition condition may be "the presence of an object in the departure restriction area AA1." The departure restriction area AA1 extends from the position where the stereo camera 132 is disposed to the rear of the forklift 10. Therefore, even if the first prohibition condition is set as described above, if the first prohibition condition and the third prohibition condition are met, it can be said that the object detection unit 131 has detected an object behind the forklift 10 and the traveling direction determined by the direction lever 88 is the reverse direction.

[0103] The forced operation condition may be changed to any of the following. The forced operation condition may also be a combination of the forced operation condition of the embodiment and the following forced operation conditions. When the forced operation condition is 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.

[0104] Forced operation condition: The direction lever 88 is in the neutral position and the accelerator is off. Forced operation condition: With the accelerator off, change the direction lever 88 from the neutral position to the reverse position.

[0105] Even when the forced operation condition is changed as described above, it is possible to prevent the forklift 10 from entering the forced operation state S4 when the rotation speed of the engine 31 is high. In particular, when the forced operation condition is that the direction lever 88 is changed from the neutral position to the reverse position with the accelerator pedal off, the forklift 10 enters the forced operation state S4 by moving the direction lever 88 to the reverse position with the accelerator pedal off. This prevents the rotation speed of the engine 31 from increasing when the accelerator pedal is on before the direction lever 88 is in the reverse position, and the direction lever 88 from being moved to the reverse position while in this state. This further prevents the forklift 10 from entering the forced operation state S4 when the rotation speed of the engine 31 is high.

[0106] The forced operation condition may be "the direction lever 88 is in the neutral position." The forced operation condition may be "the direction lever 88 is in the forward position." In this way, the change in the traveling direction determined by the direction lever 88 includes a change from the reverse direction to the forward direction.

[0107] In the forced operation state S4, a limit may be imposed so that the rotation speed of the engine 31 does not exceed a limit rotation speed. The limit rotation speed is a rotation speed that is higher than the idle rotation speed. The control device 81 may send a torque command to the cruise control device 63 instead of a rotation speed command. The torque command includes a target torque. The control device 81 increases the target torque as the accelerator opening degree increases. The cruise control device 63 controls the throttle actuator 32 so that the torque of the engine 31 follows the target torque.

[0108] The object detection unit 131 may detect the position of an object present in the forward direction of the forklift 10. In this case, the stereo camera 132 is disposed facing the front of the forklift 10. When the object detection unit 131 detects the position of an object present in the forward direction of the forklift 10, the departure restriction area AA1 becomes an area extending forward from the forklift 10. In this case, the departure restriction control is performed with the "rear" and "front" described in the embodiment reversed.

[0109] The object detection unit 131 may be capable of detecting the position of an object present in either the reverse direction or the forward direction of the forklift 10. For example, a stereo camera for forward travel and a stereo camera for reverse travel may be provided, or a fisheye camera may be provided. In this case, the start restriction area AA1 includes a forward area extending forward from the forklift 10 and a rear area extending rearward from the forklift 10. The control device 81 may place the forklift 10 in the start prohibition state S3 when the forklift 10 is stopped, when an object is present in the forward area, and when the direction lever 88 is in the forward position. The control device 81 may place the forklift 10 in the start prohibition state S3 when the forklift 10 is stopped, when an object is present in the rear area, and when the direction lever 88 is in the reverse position.

[0110] The travel direction determination unit may be any device that can be operated by the driver of the forklift 10. For example, the travel direction determination unit may be a push button. The object detection unit 131 may use a time-of-flight (ToF) camera, a laser imaging detection and ranging (LIDAR), a millimeter-wave radar, or the like, instead of the stereo camera 132. The object detection unit 131 may be equipped with a combination of multiple sensors, such as the stereo camera 132 and a LIDAR.

[0111] The alarm device 136 may be provided in a component other than the object detection unit 131. The alarm device 136 may be directly activated by the control device 81. The forklift 10 may be capable of switching between automatic operation and manual operation.

[0112] The engine-powered industrial vehicle may be any vehicle used for work in a limited area, such as a towing vehicle used for transporting cargo, an order picker used for picking work, etc. In other words, the engine-powered industrial vehicle may not be equipped with a cargo handling device 20 for loading and unloading cargo. [Explanation of symbols]

[0113] 10...Forklift which is 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 driving wheels; a control device that adjusts the driving force transmitted to the drive wheels, a forward direction determination unit that determines the forward direction of the engine-powered forklift by being operated to a forward position that instructs forward movement or a reverse position that instructs reverse movement, based on a neutral position; an object detection unit that detects the position of an object present in the traveling direction of the engine-powered forklift, The power transmission mechanism includes: A torque converter, a transmission; The transmission is an input shaft to which driving force is transmitted from the torque converter; a forward clutch provided on the input shaft; a forward gear train that is connected to the input shaft when the forward clutch is in an engaged state and that is disconnected from the input shaft when the forward clutch is in a disengaged state; a reverse clutch provided on the input shaft; a reverse gear train that is connected to the input shaft when the reverse clutch is in an engaged state and that is disconnected from the input shaft when the reverse clutch is in a disengaged state, 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 engine-powered forklift truck comprises: an electromagnetic valve that controls the supply and discharge of hydraulic oil to the forward clutch and the reverse clutch; a forward solenoid that switches between supplying and discharging hydraulic oil to the forward clutch by the electromagnetic valve, and that supplies hydraulic oil from the electromagnetic valve to the forward clutch when the forward solenoid is excited; a reverse solenoid that switches between supplying and discharging hydraulic oil to the reverse clutch by the electromagnetic valve, and that supplies hydraulic oil from the solenoid valve to the reverse clutch when the reverse solenoid is excited; a first forward relay provided in a forward connection line that electrically connects a battery and the forward solenoid when the travel direction determination unit is in the forward position; a second forward relay provided in the forward connection line; a first reverse relay provided in a reverse connection line that electrically connects the battery and the reverse solenoid when the traveling direction determination unit is in the reverse position; a second reverse relay provided in the reverse connecting line, The control device When a switchback operation is not being performed, the second forward relay and the second reverse relay are connected; When the switchback operation is being performed, the second forward relay and the second reverse relay are brought into an interrupted state; when the object detection unit detects the object, and the detected direction of the object coincides with the traveling direction determined by the traveling direction determination unit, and when the vehicle speed of the engine-powered forklift is equal to or less than a stop determination threshold, the engine-powered forklift is put into a start-prohibited state; the start-prohibited state is a state in which the power transmission mechanism is changed to the drive non-transmission state by the forward clutch and the reverse clutch by disengaging the second forward relay and the second reverse relay, even when the travel direction determination unit is operated to the forward position or the reverse position.

2. The control device When the engine-powered forklift is in the start-prohibited state, if the traveling direction determined by the traveling direction determination unit is changed, the start-prohibited state is released and the engine-powered forklift is brought into a forced operation state; When the engine-powered forklift is in the forced operation state, even if the traveling direction determined by the traveling direction determination unit is returned to the traveling direction before the start prohibition state was released after the start prohibition state is released, the forced operation state is maintained; 2. The engine-powered forklift according to claim 1, wherein the forced operating state is a state in which the power transmission mechanism is forced into the drive transmission state, thereby enabling the engine-powered forklift to move forward.

3. 3. The engine-powered forklift according to claim 2, wherein the forced operation state is a state in which the engine-powered forklift is capable of traveling at a speed equal to or lower than an upper vehicle speed limit.

4. The control device 4. The engine-powered forklift according to claim 2, wherein, when the engine-powered forklift is in the start-prohibited state, the traveling direction determined by the traveling direction determination unit is changed and the engine speed is less than a predetermined speed, the start-prohibited state is released and the engine-powered forklift is put into the forced operation state.

5. The engine-powered forklift according to any one of claims 2 to 4, wherein in the forced operation state, the engine can travel with a limit imposed on the number of revolutions of the engine.

Images