Industrial vehicle

Abstract

To provide an industrial vehicle capable of accurately detecting the failure of a sensor and maintaining the workability of the vehicle.SOLUTION: The forklift 1 includes the battery 30, the traveling device 5, the machine base 10 including the operation stand 17, the boarding floor 18, and the opening 19, the sensor 23 that detects protrusion of the object R from the opening 19 based on whether or not the inspection light L from the light emitting unit 24 connected to the battery 30 is received by the light receiving unit 25, and the failure determining unit 4 that determines whether or not a failure has occurred in the sensor 23. The failure determination unit 4 determines that the sensor 23 has an open failure when the light receiving unit 25 does not continuously receive the inspection light L even though the power supply from the battery 30 to the light emitting unit 24 is ON, and determines that the sensor 23 has a short failure when the light receiving unit 25 outputs a signal indicating that the inspection light L is received even though the power supply from the battery 30 to the light emitting unit 24 is OFF.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to industrial vehicles. [Background technology]

[0002] An example of a conventional industrial vehicle is a material handling vehicle described in Patent Document 1. Patent Document 1 discloses an industrial vehicle and a method for keeping the legs of an operator in the industrial vehicle within an operator compartment. This conventional industrial vehicle is provided with a sensor, which is a detector that emits inspection light, which is a plurality of photoelectric beams, at the entrance to the compartment where the operator boards. The sensor detects the presence of an object passing through the compartment entrance when the deadman's brake is released and a command to move the vehicle is input, or when the vehicle is currently moving. If the object is detected, the industrial vehicle stops. This conventional industrial vehicle also has a self-diagnosis function for detecting sensor failure. The self-diagnosis related to failure detection is performed while the industrial vehicle is traveling. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 7,259,662 Summary of the Invention [Problem to be solved by the invention]

[0004] When an object such as an operator's foot protrudes outside the base of an industrial vehicle, it is desirable to promptly notify the operator. To detect such protrusion, it is preferable to equip the vehicle with a self-diagnosis function for detecting a failure of the sensor that detects protrusion, as in the conventional industrial vehicle described above. However, because the failure of the sensor does not directly affect the vehicle's operation, restricting the vehicle's operation every time a sensor failure is detected may reduce the operability of the vehicle, such as for transporting work.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide an industrial vehicle that can accurately detect sensor failures and maintain the workability of the vehicle. [Means for solving the problem]

[0006] The gist of the present disclosure is as follows. [1] An industrial vehicle comprising: a power supply unit that supplies power to each component of the vehicle; a traveling device that includes wheels and a steering device; a base that includes an operation console with operating levers including an accelerator lever, a boarding floor with operating pedals including a brake pedal, and an opening that serves as an entrance and exit to the boarding floor; a sensor that detects an object protruding from the opening based on whether or not an inspection light from a light-emitting unit connected to the power supply unit is received by a light-receiving unit; and a failure determination unit that determines whether or not a failure has occurred in the sensor, wherein the failure determination unit determines that the sensor has an open failure if the light-receiving unit does not continuously receive the inspection light even though the power supply from the power supply unit to the light-emitting unit is ON, and determines that the sensor has a short failure if the light-receiving unit outputs a signal indicating that the inspection light has been received even though the power supply from the power supply unit to the light-emitting unit is OFF.

[0007] In this industrial vehicle, based on the power supply status to the light-emitting unit and the reception status of the inspection light at the light-receiving unit in that case, it is possible to accurately determine whether the sensor failure is an open failure or a short failure, distinguishing it from the normal detection of an object protruding from an opening. By determining the cause of the sensor failure, it is possible to implement vehicle driving restrictions according to the cause of the failure, thereby avoiding unnecessary driving restrictions and maintaining the vehicle's workability.

[0008] [2] In the industrial vehicle described in [1], the failure determination unit determines that the sensor has an open failure if, after the sensor detects an object protruding from the opening, the accelerator lever is in neutral for a predetermined period of time, and then the accelerator lever is turned on again, and the sensor continues to detect an object protruding from the opening. In this case, by setting the condition for clearing the error as the accelerator lever being in neutral for a predetermined period of time, it is possible to provide the worker with an opportunity to correct the protrusion of their foot from the opening. On the other hand, by using the continuous detection of an object protruding from the opening after the accelerator lever has been in neutral for a predetermined period of time as the determination criterion, it is possible to accurately determine whether the sensor has an open failure.

[0009] [3] The industrial vehicle according to [1] or [2], further comprising a key input unit for starting the vehicle, wherein the light-emitting unit receives power from the power supply device so as to be turned on and off in conjunction with the on and off of the key input unit, and the light-receiving unit receives power from the power supply device for a predetermined period of time by relay driving when the key input unit is turned off. In this case, a sensor short-circuit failure can be detected when the key input unit is off. By detecting a sensor short-circuit failure when the vehicle is not started, the impact on workability can be eliminated.

[0010] [4] The industrial vehicle according to any one of [1] to [3], further comprising a travel control unit that controls the drive of the travel device, wherein the travel control unit executes a travel prohibition process that prohibits the vehicle from traveling when the failure determination unit determines that the sensor has an open failure, and allows the vehicle to travel when the accelerator lever has been in neutral for a predetermined period of time after the travel prohibition process is executed. In this case, by setting the accelerator lever being in neutral for a predetermined period of time as a condition for clearing the error of the sensor open failure, it is possible to give the worker an opportunity to correct any protrusion of a foot from the opening, while maintaining the workability of the vehicle.

[0011] [5] The industrial vehicle according to [1] or [3], further comprising a travel control unit that controls the driving of the travel device, and the travel control unit allows the vehicle to travel even when the failure determination unit determines that the sensor has a short-circuit failure. In this case, by allowing the vehicle to travel after determining that the sensor has a short-circuit failure, it is possible to provide the worker with an opportunity to be careful not to stick their feet out of the opening, while maintaining the workability of the vehicle.

[0012] [6] The industrial vehicle according to any one of [1] to [5], further comprising an alarm unit that executes different alarm processing when the sensor detects that the object has protruded from the machine base and when the failure determination unit determines that a failure has occurred in the sensor. In this case, by separating the notification of the detection of protrusion from the notification of the detection of a sensor failure, it is possible to prevent a worker from misinterpreting the notification content. [Effects of the Invention]

[0013] According to the present disclosure, sensor failure can be detected with high accuracy, and the workability of the vehicle can also be maintained. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a perspective view showing a reach forklift that is one embodiment of an industrial vehicle according to the present disclosure. FIG. [Figure 2] FIG. 2 is an enlarged perspective view of a main part showing the positional relationship of the alarm device with respect to the reach forklift. [Figure 3] FIG. 1 is a block diagram showing the functional configuration of a reach forklift. [Figure 4] 10 is a flowchart showing an example of the operation of the main control device in determining an open circuit fault. [Figure 5] 10 is a flowchart showing an example of the operation of the main control device in determining whether a short circuit has occurred. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an industrial vehicle according to one aspect of the present disclosure will now be described in detail with reference to the drawings.

[0016] Fig. 1 is a perspective view showing a reach forklift, which is one embodiment of an industrial vehicle according to the present disclosure. As shown in Fig. 1, the reach forklift 1 (host vehicle) includes a base 10, a traveling device 5, and a battery 30 (power supply device). The reach forklift 1 is a stand-on forklift used for transporting cargo at manufacturing sites, logistics sites, etc.

[0017] In the following description, the height direction of the base 10 is defined as D1, the front-rear direction relative to the base 10 as D2, and the width direction relative to the base 10 as D3. The height direction D1, front-rear direction D2, and width direction D3 are perpendicular to one another. When the reach forklift 1 is positioned on a horizontal plane, the height direction D1 is the direction along the vertical direction, and the front-rear direction D2 and width direction D3 are directions along the horizontal direction.

[0018] The traveling device 5 includes wheels and a steering device. Specifically, the traveling device 5 includes road tires as front wheels, drive tires and caster tires as rear wheels, a traveling motor, a steering device, a steering motor, etc. A cargo handling device (not shown) is attached to the front of the reach forklift 1. The cargo handling device includes a mast, lift brackets, forks, a cargo handling motor, etc.

[0019] The base 10 is the body of the reach forklift 1. The base 10 has a front portion 11, a pair of left and right side portions 12 and 13, and a rear portion 14, and is generally shaped like a rectangular parallelepiped. The base 10 is provided with a head guard 16 supported by a pair of pillars 15a and 15b.

[0020] The base 10 includes an operation console 17 having operation levers including an accelerator lever 17a, a boarding floor 18 having operation pedals including a brake pedal 18a, and an opening 19 that serves as an entrance and exit to the boarding floor 18. The space defined by the boarding floor 18 is a space where the operator of the reach forklift 1 boards and operates the vehicle. In the example of FIG. 1 , the opening 19 is provided in the rear portion 14, to the right of the center in the width direction D3, along the height direction D1 from the same height as the boarding floor 18 to the upper end of the rear portion 14.

[0021] On the base 10, the control console 17 is disposed across the front and sides (here, on the left side) as viewed from the boarding floor 18. As described above, the control console 17, located in front as viewed from the boarding floor 18, is provided with an accelerator lever 17a used to operate the reach forklift 1 to travel (forward and backward). As will be described later, when the reach forklift 1 is traveling, an object R (see FIG. 2), such as the operator's foot, may protrude outside the base 10. For this reason, the control console 17 is provided with a display 17c (see FIG. 3) to notify the operator that the object R has protruded outside the base 10. If the object R protrudes outside the base 10, an indicator lights up on the display 17c to notify the operator that the object R has protruded. In addition to this indicator, the display 17c may also display the speed of the reach forklift 1, the remaining charge of the battery 30, etc.

[0022] The operation console 17 is provided with a key input unit 17d (input unit: see Figure 3) for starting the reach forklift 1. Turning the key input unit 17d ON permits the reach forklift 1 to operate. The key input unit 17d accepts key input for starting the reach forklift 1. The key may be either a physical key or an electronic key. The operation console 17 is also provided with a buzzer 17e (see Figure 3) that sounds an alarm to alert the user that the object R has protruded beyond the base 10. The operation console 17 is also provided with an accelerator lever 17a, a display 17c, the key input unit 17d, and the buzzer 17e, as well as a reach lever, tilt lever, lift lever, and other levers used to operate the reach forklift 1. A steering wheel 17b for controlling the traveling direction of the reach forklift 1 is provided on the operation console 17 on the left side as viewed from the boarding floor 18.

[0023] A brake pedal 18a is provided at a corner of the boarding floor 18 (in FIG. 1, the corner formed by the front and left operation consoles 17). The reach forklift 1 employs a deadman's type brake that is released by stepping on the brake pedal 18a. With a deadman's type brake, the brake is applied when the brake pedal 18a is in the OFF position, and the brake is released when the brake pedal 18a is in the ON position.

[0024] A floor switch 18b is also provided on the boarding floor 18. The floor switch 18b is a type of safety device in the reach forklift 1, and is configured, for example, by a pressure-sensitive switch. The floor switch 18b is turned ON by the weight of the operator on the boarding floor 18, and is turned OFF when the operator leaves the boarding floor 18.

[0025] The battery 30 (see FIG. 3) supplies power to each component of the reach forklift 1. Specifically, the battery 30 supplies power to the main control device 2, the sensor 23, and the relay drive circuit 8 (relay drive). The main control device 2, the sensor 23, and the relay drive circuit 8 will be described in detail later.

[0026] The reach forklift 1 described above travels and performs cargo handling operations by an operator who enters the boarding floor 18 through an opening 19 in the rear section 14 of the base 10 and operates the accelerator lever 17a, brake pedal 18a, etc., of the control console 17. As mentioned above, when the reach forklift 1 travels, there is a possibility that an object R may protrude outside the base 10 because the opening 19 may not have a door or the like. For example, if the operator's feet protrude from the opening 19, it is preferable that a nearby supervisor detect this protrusion and provide on-the-spot guidance to the operator, such as correcting their posture. Therefore, the reach forklift 1 according to this embodiment is equipped with an alarm device 20 that alerts nearby supervisors when an object R, such as the operator's feet, protrudes outside the base 10. The configuration of the alarm device 20 is described in detail below.

[0027] 2 is an enlarged perspective view of the main parts showing the positional relationship of the alarm device with respect to the reach forklift. The alarm device 20 includes a bracket 21, a bracket 28, a lamp 22, a sensor 23, and an alarm unit 6 (see FIG. 3). The alarm device 20 may also include a display 17c and a buzzer 17e.

[0028] The bracket 21 is a member that houses at least the lamp 22 therein. In this embodiment, the bracket 21 houses the lamp 22 and a sensor 23 that includes a light-projecting unit 24, which will be described later. The bracket 21 is in the shape of a metal box and has a main surface 21a and a pair of side surfaces 21b, 21c adjacent to the main surface 21a. To ensure strength, the metal that constitutes the bracket 21 is, for example, iron or stainless steel. In this embodiment, the bracket 21 has a substantially rectangular parallelepiped shape in which the length in the height direction D1 is longer than the lengths in the front-rear direction D2 and the width direction D3.

[0029] The bracket 21 is disposed on the rear portion 14 of the machine base 10. Specifically, the bracket 21 is disposed below the opening 19 on the rear portion 14 of the machine base 10. In the example of FIG. 2 , the bracket 21 is disposed adjacent to the left edge of the lower portion of the opening 19 on the rear portion 14 of the machine base 10, with the main surface 21a facing the rear of the machine base 10 and one of the side surfaces 21b, 21c along the edge of the opening 19.

[0030] A slit 26 is provided near the center of the main surface 21a of the bracket 21 in the height direction D1, allowing the lamp 22 housed in the bracket 21 to be exposed. The slit 26 extends on the main surface 21a in the width direction D3 of the machine base 10. In this embodiment, the slit 26 is formed across the entire main surface 21a in the width direction D3 and extends to a pair of side surfaces 21b, 21c adjacent to the main surface 21a. Of the side surfaces 21b, 21c of the bracket 21, the side surface 21b on the opening 19 side is provided with a pair of upper and lower circular windows 27, 27 for passing the inspection light L from the light-projecting unit 24 of the sensor 23. The windows 27, 27 are arranged side by side in the height direction D1 on either side of the slit 26.

[0031] The sensor 23 is a device that detects whether the object R has protruded from the opening 19. For example, a photoelectric sensor is used as the sensor 23. The sensor 23 has the aforementioned light-projecting unit 24 that projects inspection light L and a light-receiving unit 25 that receives the inspection light L. The sensor 23 detects whether the object R has protruded from the opening 19 based on whether the inspection light L from the light-projecting unit 24 connected to the battery 30 is received by the light-receiving unit 25. In this embodiment, a pair of upper and lower sensors 23A, 23B are arranged in the height direction D1 of the machine base 10. In the following description, when there is no need to distinguish between the sensors 23A and 23B, the sensors 23A and 23B will be collectively referred to as the sensors 23.

[0032] In the example of FIG. 2, the light-projecting unit 24A of the sensor 23A and the light-projecting unit 24B of the sensor 23B are disposed within the bracket 21 at a fixed interval in the height direction D1. Within the bracket 21, the light-projecting unit 24A of the upper sensor 23A is disposed at a position higher than the slit 26, and the light-projecting unit 24B of the lower sensor 23B is disposed at a position lower than the slit 26. The inspection light L from the light-projecting units 24A and 24B passes through the window 27, crosses the opening 19 along the width direction D3, and travels toward the light-receiving unit 25. When the sensor 23 does not detect protrusion of the object R, this is equivalent to when the light-receiving unit 25 receives the inspection light L. Conversely, when the sensor 23 detects protrusion, this is equivalent to when the light-receiving unit 25 does not receive the inspection light L.

[0033] In this embodiment, when arranging light receiving portion 25A of sensor 23A and light receiving portion 25B of sensor 23B, another metal bracket 28 conforming to the shape of bracket 21 is arranged on rear portion 14 of machine base 10. Like bracket 21, bracket 28 has a main surface 28a and a pair of side surfaces 28b adjacent to main surface 28a.

[0034] Bracket 28 is disposed on the opposite side of bracket 21 across opening 19, with main surface 28a facing rearward of machine base 10 and one of a pair of side surfaces 28b disposed adjacent to the right edge of the lower portion of opening 19 so as to be along the edge of opening 19. One of the pair of side surfaces 28b of bracket 28 faces side surface 21b of bracket 21, which has window portion 27. Side surface 27b is provided with a pair of upper and lower circular windows (not shown) that allow inspection light L from light-projecting unit 24A of sensor 23A and light-projecting unit 24B of sensor 23B to pass through. Light-receiving unit 25A of sensor 23A and light-receiving unit 25B of sensor 23B are disposed side by side in bracket 28 along height direction D1 so as to correspond to the positions of the pair of upper and lower windows of side surface 27b, respectively. The light receiving units 25A and 25B output a signal indicating that the inspection light L has been received to the main control device 2 in response to receiving the inspection light L from the light projecting units 24A and 24B.

[0035] The lamp 22 is a device that emits light for notification. For example, an LED or the like can be used as the lamp 22. The lamp 22 has, for example, a light-transmitting case and emits light for notification over a wide range from the front and side of the case. The lamp 22 is disposed on the machine base 10 in a position that is visible from the periphery of the machine base 10. In this embodiment, the above-mentioned bracket 21 is disposed on the rear surface 14, and the lamp 22 housed in the bracket 21, the light-emitting portion 24A of the sensor 23A, and the light-emitting portion 24B of the sensor 23B are disposed on the rear surface 14 of the machine base 10. Furthermore, the lamp 22, the light-emitting portion 24A of the sensor 23A, and the light-emitting portion 24B of the sensor 23B are all disposed on the same side of the opening 19. In this embodiment, by being housed in the above-mentioned bracket 21, the lamp 22, the light-emitting portion 24A of the sensor 23A, and the light-emitting portion 24B of the sensor 23B are arranged adjacent to the bottom of the opening 19 so as to be on the same side (left side) of the opening 19.

[0036] Within bracket 21, lamp 22 is disposed at a height position corresponding to slit 26. As described above, slit 26 extends across main surface 21a of bracket 21 and a pair of side surfaces 21b, 21c adjacent to main surface 21a. This makes it possible to expand the visible range of the notification light emitted from lamp 22.

[0037] FIG. 3 is a block diagram showing the functional configuration of a reach forklift. In FIG. 3, solid lines indicate signal transmission paths for each component, and dashed lines indicate power transmission paths for each component. The main control device 2 shown in FIG. 3 is physically configured, for example, by an ECU (Electronic Control Unit) mounted on the reach forklift 1. The ECU is an electronic control unit having a CPU, ROM, RAM, a CAN communication circuit, etc. In the ECU, various functions are realized, for example, by loading a program stored in ROM into RAM and executing the program loaded into RAM by the CPU. The main control device 2 is connected to the above-mentioned sensor 23, accelerator lever 17a, brake pedal 18a, floor switch 18b, display 17c, buzzer 17e, lamps 22, traveling device 5, etc.

[0038] The main control device 2 is also connected to the key input unit 17d, a battery 30, and a relay drive circuit 8. Information regarding the ON / OFF status of a key input into the key input unit 17d is input to the main control device 2. The battery 30 supplies power to each component, including the sensor 23. The relay drive circuit 8 functions as a switch between the battery 30 and the light-receiving unit 25. The relay drive circuit 8 is connected between the battery 30 and the light-receiving unit 25. The ON / OFF of the relay drive circuit 8 is controlled by the main control device 2. As shown in FIG. 3 , the light-emitting unit 24 receives power from the battery 30 so that it turns ON / OFF in conjunction with the ON / OFF status of the key input unit 17d. In this way, the key input unit 17d may function as a switch between the battery 30 and the light-emitting unit 24. When the key input unit 17d is turned OFF, the light-receiving unit 25 receives power from the battery 30 via the relay drive circuit 8 for a predetermined time. Here, the predetermined time refers to a time sufficient for the failure determination unit 4, described below, to determine whether the sensor 23 has failed.

[0039] The main control device 2 has, as functional components, a protrusion determination unit 3, a malfunction determination unit 4, a notification unit 6, and a travel control unit 7. The protrusion determination unit 3 determines whether or not the object R protrudes from the machine base 10 based on a signal indicating whether or not the inspection light L has been received by the light receiving unit 25 of the sensor 23. When the inspection light L projected from the light projecting unit 24 of the sensor 23 is not received by the light receiving unit 25, the protrusion determination unit 3 determines that the object R protrudes from the machine base 10, and outputs information indicating the protrusion to the notification unit 6.

[0040] The failure determination unit 4 determines whether a failure has occurred in the sensor 23. Here, the failure determination unit 4 determines whether an open failure or a short failure has occurred in the sensor 23. An open failure is a malfunction in which the light receiving unit 25 does not output a signal indicating that the inspection light L has been received, even though the inspection light L from the light projecting unit 24 is incident on the light receiving unit 25. When an open failure occurs, the protrusion determination unit 3 detects the protrusion of the object R from the opening 19, even if the object R does not protrude from the opening 19, and the alarm unit 6 performs an alarm process. A short failure is a malfunction in which the light receiving unit 25 outputs a signal indicating that the inspection light L has been received, even though the inspection light L from the light projecting unit 24 is not incident on the light receiving unit 25. When a short failure occurs, the protrusion determination unit 3 does not detect the protrusion of the object R, even if the object R protrudes from the opening 19, and the alarm unit 6 does not perform an alarm process.

[0041] The failure determination unit 4 determines that the sensor 23 has an open-circuit failure when the light-receiving unit 25 does not continuously receive the inspection light L even though power supply from the battery 30 to the light-projecting unit 24 is ON. In this embodiment, the failure determination unit 4 determines that the sensor 23 has an open-circuit failure when, after the sensor 23 detects that the object R has protruded from the opening 19, the accelerator lever 17a is in neutral for a predetermined time, and then the accelerator lever 17a is again operated to ON, but the sensor 23 continues to detect that the object R has protruded from the opening 19. When the failure determination unit 4 determines that the sensor 23 has an open-circuit failure, it outputs information indicating the open-circuit failure to the alarm unit 6. Furthermore, when the key input on the key input unit 17d is turned OFF after determining that the sensor 23 has an open-circuit failure, the failure determination unit 4 outputs information instructing the alarm unit 6 to clear the error. Note that the predetermined time here means a time sufficient for the operator to return the accelerator lever 17a to neutral at their will. The predetermined time is set to, for example, about one second. By setting it in this manner, it is possible to prevent the malfunction determination unit 4 from making the above determination in cases where the accelerator lever 17a is returned to neutral by an operation unintentional by the operator.

[0042] The failure determination unit 4 determines that the sensor 23 has a short-circuit failure when the light receiving unit 25 outputs a signal indicating that it has received the inspection light L, even though the power supply from the battery 30 to the light projecting unit 24 is turned off. When the failure determination unit 4 determines that the sensor 23 has a short-circuit failure, it outputs information indicating the short-circuit failure to the notification unit 6.

[0043] The notification unit 6 executes various notification processes based on information from the protrusion determination unit 3 and the failure determination unit 4. Here, the notification unit 6 executes different notification processes depending on whether the sensor 23 in the protrusion determination unit 3 detects that the object R has protruded from the machine base 10 or whether the failure determination unit 4 determines that an open circuit failure or a short circuit failure has occurred in the sensor 23.

[0044] When the sensor 23 detects that the object R has protruded from the opening 19, the notification unit 6 performs different processing depending on the traveling state of the reach forklift 1, which is determined, for example, by the ON / OFF status of the key, the ON / OFF status of the floor switch 18b, the ON / OFF status of the accelerator lever 17a and the brake pedal 18a, and the speed of the reach forklift 1.

[0045] For example, when the reach forklift 1 is in a state ready to travel (the key is ON, the floor switch 18b is ON, one of the accelerator lever 17a and the brake pedal 18a is ON, and the reach forklift 1 is stopped), the notification unit 6 lights up an indicator on the display 17c and outputs information to the travel control unit 7 to prohibit the reach forklift 1 from traveling.

[0046] For example, when the reach forklift 1 is in a traveling start state (the key is ON, the floor switch 18b is ON, both the accelerator lever 17a and the brake pedal 18a are ON, and the reach forklift 1 is stopped), the notification unit 6 performs a notification process by lighting up the indicator on the display 17c, lighting up the lamp 22, and sounding the buzzer 17e, and also outputs information to the traveling control unit 7 to prohibit the reach forklift 1 from traveling.

[0047] For example, when the reach forklift 1 is in a traveling state (the key is ON, the floor switch 18b is ON, both the accelerator lever 17a and the brake pedal 18a are ON, and the reach forklift 1 is traveling), the notification unit 6 performs a notification process by lighting up the indicator on the display 17c, lighting up the lamp 22, and sounding the buzzer 17e, but does not output information to the traveling control unit 7 to prohibit the reach forklift 1 from traveling.

[0048] When the notification unit 6 receives information from the failure determination unit 4 indicating that the sensor 23 has an open failure, it causes the display 17c to display an error code indicating the open failure separately from the indicator lighting that occurs when the protrusion of the object R through the opening 19 is detected. When the notification unit 6 receives information that the sensor 23 has an open failure, it outputs information to the travel control unit 7 that prohibits the reach forklift 1 from traveling. When the notification unit 6 receives information that the sensor 23 has an open failure and then receives information that indicates that the accelerator lever 17a has been in neutral for a predetermined time and then the accelerator lever 17a has been operated again to ON, it continues to display the error code while outputting information to the travel control unit 7 that permits the reach forklift 1 to travel.

[0049] When the notification unit 6 receives information from the failure determination unit 4 that the sensor 23 has a short circuit failure, it causes the display 17c to display an error code indicating the short circuit failure. In this embodiment, since the key is OFF when the short circuit failure is determined, the notification unit 6 may cause the display 17c to display an error code notifying of the short circuit failure the next time the key is turned ON in the key input unit 17d. Unlike in the case of an open circuit failure, the notification unit 6 does not output information to the travel control unit 7 prohibiting the reach forklift 1 from traveling, even when it receives information that the sensor 23 has a short circuit failure. In other words, when the sensor 23 has a short circuit failure, an error code indicating the short circuit failure is displayed, but the reach forklift 1 is permitted to travel.

[0050] The travel control unit 7 controls the operation of the travel device 5. When the travel control unit 7 receives information from the notification unit 6 prohibiting the reach forklift 1 from traveling, it prohibits the reach forklift 1 from traveling using the travel device 5. When the travel control unit 7 receives information from the notification unit 6 permitting the reach forklift 1 to travel, it permits the reach forklift 1 to travel using the travel device 5. When the failure determination unit 4 determines that the sensor 23 has an open failure, the travel control unit 7 receives information from the notification unit 6 prohibiting the reach forklift 1 from traveling and executes a travel prohibition process to prohibit the reach forklift 1 from traveling. After executing the travel prohibition process, if the accelerator lever is in neutral for a predetermined time, the travel control unit 7 receives information from the notification unit 6 permitting the reach forklift 1 to travel and permits the reach forklift 1 to travel. Even when the failure determination unit 4 determines that the sensor 23 has a short-circuit failure, the travel control unit 7 does not receive information from the notification unit 6 prohibiting the reach forklift 1 from traveling and permits the reach forklift 1 to travel.

[0051] FIG. 4 is a flowchart showing an example of the operation of the main control device in determining an open circuit failure. As shown in FIG. 4, the failure determination unit 4 first determines whether the light receiving unit 25 is receiving the test light L (step S101). If the failure determination unit 4 determines that the light receiving unit 25 is receiving the test light L, the failure determination unit 4 ends this process. On the other hand, if the failure determination unit 4 determines in step S101 that the light receiving unit 25 is not receiving the test light L, the failure determination unit 4 determines whether the accelerator lever 17a has been in neutral for a predetermined time (step S102). If the failure determination unit 4 determines that the accelerator lever 17a has not been in neutral for a predetermined time, the failure determination unit 4 executes step S102 again. On the other hand, if the failure determination unit 4 determines that the accelerator lever 17a has been in neutral for a predetermined time, the failure determination unit 4 subsequently determines whether the accelerator lever 17a has been turned ON (step S103). If the failure determination unit 4 determines that the accelerator lever 17a has not been turned ON, the failure determination unit 4 executes step S103 again. On the other hand, when the failure determination unit 4 determines that the accelerator lever 17a has been turned ON, it determines whether the light receiving unit 25 is receiving the inspection light L (step S104). When the failure determination unit 4 determines that the light receiving unit 25 is receiving the inspection light L, it ends this process. On the other hand, when the failure determination unit 4 determines that the light receiving unit 25 is not receiving the inspection light L, it determines that the sensor 23 has an open circuit failure, and outputs information indicating the open circuit failure to the notification unit 6 and information prohibiting the reach forklift 1 from traveling to the travel control unit 7 (step S105).

[0052] Thereafter, the notification unit 6 determines whether the accelerator lever 17a has been returned to neutral for a predetermined time (step S106). If the notification unit 6 determines that the accelerator lever 17a has not been returned to neutral for a predetermined time, it executes step S106 again. On the other hand, if the notification unit 6 determines that the accelerator lever 17a has been returned to neutral for a predetermined time, it outputs information permitting the reach forklift 1 to travel to the travel control unit 7 (step S107), and ends this process.

[0053] Fig. 5 is a flowchart showing an example of the operation of the main control device in determining whether a short circuit has occurred. As shown in Fig. 5, the main control device 2 first determines whether the key input unit 17d is OFF (step S201). If the main control device 2 determines that the key input unit 17d is not OFF (is ON), it executes step S201 again. On the other hand, if the main control device 2 determines in step S202 that the key input unit 17d is OFF, it turns on the relay drive circuit 8 (step S202).

[0054] Thereafter, the failure determination unit 4 determines whether the light receiving unit 25 is receiving the inspection light L (step S203). If the failure determination unit 4 determines that the light receiving unit 25 is not receiving the inspection light L, the failure determination unit 4 ends this process. On the other hand, if the failure determination unit 4 determines in step S203 that the light receiving unit 25 is receiving the inspection light L, the failure determination unit 4 determines that the sensor 23 has a short-circuit failure, outputs information indicating the short-circuit failure to the notification unit 6, and outputs information permitting the reach forklift 1 to travel to the travel control unit 7 (step S204), and ends this process.

[0055] As described above, the failure determination unit 4 provided in the reach forklift 1 of this embodiment determines that the sensor 23 has an open circuit failure if the light-receiving unit 25 does not continuously receive the inspection light L even though the power supply from the battery 30 to the light-projecting unit 24 is ON, and determines that the sensor 23 has a short circuit failure if the light-receiving unit 25 outputs a signal indicating that it has received the inspection light L even though the power supply from the battery 30 to the light-projecting unit 24 is OFF. With this configuration, based on the power supply status to the light-projecting unit 24 and the reception status of the inspection light L by the light-receiving unit 25 at that time, it is possible to accurately determine whether the failure of the sensor 23 is an open circuit failure or a short circuit failure, distinguishing it from normal detection of an object R protruding from the opening 19. Furthermore, by determining the cause of the failure of the sensor 23, it is possible to implement travel restrictions on the reach forklift 1 according to the cause of the failure, thereby avoiding unnecessary travel restrictions and maintaining the operability of the reach forklift 1.

[0056] Furthermore, since the failure determination unit 4 can determine whether the sensor 23 has failed while the reach forklift 1 is stopped, it will not determine that the sensor 23 has failed while the reach forklift 1 is traveling and will not execute control such as prohibiting the traveling device 5 from traveling. This allows the workability of the reach forklift 1 to be maintained.

[0057] In this embodiment, the failure determination unit 4 determines that the sensor 23 has an open failure when the accelerator lever 17a is in neutral for a predetermined time after the sensor 23 detects that the object R has protruded from the opening 19, and then the accelerator lever 17a is again operated to ON, and the sensor 23 continues to detect that the object R has protruded from the opening 19. In this case, by setting the condition for canceling the error as the accelerator lever 17a being in neutral for a predetermined time, it is possible to provide the worker with an opportunity to correct the protrusion of their foot from the opening 19. On the other hand, by using the continuous detection of the object R protruding from the opening 19 after the accelerator lever 17a has been in neutral for a predetermined time as the determination criterion, it is possible to accurately determine that the sensor 23 has an open failure.

[0058] In this embodiment, the reach forklift 1 is equipped with a key input unit 17d for starting the vehicle, the light-emitting unit 24 receives power from a battery 30 and turns on and off in conjunction with the on and off of the key input unit 17d, and the light-receiving unit 25 receives power from the battery 30 for a predetermined period of time via the relay drive circuit 8 when the key input unit 17d is turned off. In this case, a short-circuit failure of the sensor 23 can be determined when the key input unit 17d is in the off state. By determining a short-circuit failure of the sensor 23 when the reach forklift 1 has not yet started, it is possible to eliminate any impact on workability.

[0059] In this embodiment, the reach forklift 1 is equipped with a travel control unit 7 that controls the drive of the traveling device 5. When the failure determination unit 4 determines that the sensor 23 has an open failure, the travel control unit 7 executes a travel prohibition process to prohibit the reach forklift 1 from traveling, and when the accelerator lever 17a has been in neutral for a predetermined period of time after the travel prohibition process is executed, the reach forklift 1 is permitted to travel. In this case, by setting the accelerator lever 17a being in neutral for a predetermined period of time as the error release condition for the open failure of the sensor 23, an opportunity is given to the operator to correct any protrusion of the foot from the opening 19, while the operability of the reach forklift 1 can be maintained.

[0060] In this embodiment, the travel control unit 7 allows the reach forklift 1 to travel even when the failure determination unit 4 determines that the sensor 23 has a short-circuit failure. In this case, by allowing the reach forklift 1 to travel after determining that the sensor 23 has a short-circuit failure, the operator is given an opportunity to be careful not to stick their feet out of the opening 19, while also maintaining the operability of the reach forklift 1.

[0061] In this embodiment, the reach forklift 1 is equipped with a notification unit 6 that executes different notification processes when the sensor 23 detects that the object R has protruded from the machine base and when the failure determination unit 4 determines that a failure has occurred in the sensor 23. In this case, by separating the notification of the detection of protrusion from the notification of the detection of a failure in the sensor 23, it is possible to prevent the operator from misinterpreting the notification content. [Explanation of symbols]

[0062] 1...reach forklift (industrial vehicle), 4...fault determination unit, 5...traveling device, 6...alarm unit, 7...traveling control unit, 8...relay drive circuit (relay drive), 10...machine base, 17...operation console, 17a...accelerator lever, 17c...display, 17d...key input unit, 18...boarding floor, 18a...brake pedal, 19...opening, 23 (23A, 23B)...sensor, 24 (24A, 24B)...light-emitting unit, 25 (25A, 25B)...light-receiving unit, 30...battery (power supply unit), L...inspection light, R...object.

Claims

1. a power supply device that supplies power to each component of the vehicle; a running device including wheels and a steering device; a machine base including an operation console having operation levers including an accelerator lever, a boarding floor having operation pedals including a brake pedal, and an opening serving as an entrance and exit to the boarding floor; a sensor that detects whether an object has protruded from the opening based on whether or not an inspection light from a light-emitting unit connected to the power supply device is received by a light-receiving unit; a failure determination unit that determines whether or not a failure has occurred in the sensor, The failure determination unit When the light receiving unit does not continuously receive the inspection light even though the power supply from the power supply device to the light emitting unit is ON, it is determined that the sensor has an open circuit failure, In an industrial vehicle, if the power supply from the power supply device to the light-emitting unit is turned off but the light-receiving unit outputs a signal indicating that it has received the inspection light, the sensor is determined to have a short circuit failure.

2. The failure determination unit 2. The industrial vehicle according to claim 1, wherein, after the sensor detects an object protruding from the opening, the accelerator lever is in neutral for a predetermined time, and then the accelerator lever is operated to ON again, and if the sensor continues to detect an object protruding from the opening, it is determined that the sensor has an open failure.

3. a key input unit for starting the host vehicle; the light-emitting unit receives power from the power supply device so as to be turned on and off in conjunction with the turning on and off of the key input unit; 2. The industrial vehicle according to claim 1, wherein when the key input unit is turned off, the light receiving unit receives power from the power supply unit for a predetermined time by driving a relay.

4. a travel control unit that controls the driving of the travel device; 2. The industrial vehicle according to claim 1, wherein the driving control unit executes a driving prohibition process to prohibit the vehicle from driving when the failure determination unit determines that the sensor has an open failure, and allows the vehicle to drive when the accelerator lever is in neutral for a predetermined period of time after the driving prohibition process is executed.

5. a travel control unit that controls the driving of the travel device; 2. The industrial vehicle according to claim 1, wherein the travel control unit allows the vehicle to travel even when the failure determination unit determines that the sensor has a short-circuit failure.

6. 6. The industrial vehicle according to claim 1, further comprising an alarm unit that executes different alarm processing when the sensor detects that the object has protruded from the machine base and when the failure determination unit determines that a failure has occurred in the sensor.

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