Forklift and interlock unauthorized release prevention method

Abstract

To provide a forklift capable of preventing a safety function from being disabled.SOLUTION: A forklift includes a vehicle body that performs a traveling operation, a loading device that performs a loading operation, switches SW1 and SW2 that are in a first state when an operator in the driver's seat is detected and in a second state when no operator is detected, and an interlock unit 136 that enables an interlock in the second state to disable traveling and loading operations. The interlock unit 136 executes a state determination process that determines whether the state of the switches SW1 and SW2 is the first state or the second state, an error detection process that detects an error in the switches SW1 and SW2, and an interlock enable process that enables the interlock regardless of the determination result of the state determination process when an error is detected.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a forklift and a method for preventing unauthorized unlocking of an interlock.

Background Art

[0002] Conventionally, forklifts equipped with an interlock part have been known. For example, the engine forklift described in Patent Document 1 includes an interlock part and a seat switch (seating switch) that detects whether the operator in the driver's seat is seated in a correct posture. When the operator leaves the seat (when the seat switch is off), the interlock part enables the interlock and makes the loading and unloading operation of the loading and unloading device impossible.

[0003] In the engine forklift described in Patent Document 1, when unlocking the interlock with the seat switch off, it is conditional that the key switch is on, the seat switch is on, and the engine is at a predetermined rotational speed or higher. With this condition, it is possible to prevent a loading and unloading operation (for example, the lowering operation of the fork) contrary to the operator's intention from occurring when the interlock is released.

[0004] By the way, since the seating switch has a relatively simple structure, a knowledgeable operator can illegally modify the seating switch. For example, it is possible to illegally modify it so that both ends of the seating switch are short-circuited and it is always in the on state. In that case, the safety function (interlock) by the interlock part is invalidated. As a result, there is a risk of endangering the operator.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a forklift and an interlock unauthorized release prevention method capable of suppressing the inactivation of a safety function.

Means for Solving the Problems

[0007] In order to solve the above problems, a forklift according to the present invention includes: a vehicle body that performs a traveling operation; a loading and unloading device that performs a loading and unloading operation; a driver's seat provided on the vehicle body; a switch that enters a first state when an operator of the driver's seat is detected and enters a second state when the operator is not detected; an interlock unit that enables an interlock and disables the traveling operation and the loading and unloading operation when the switch is in the second state; and is a forklift including: the interlock unit includes: a state determination process for determining whether the state of the switch is the first state or the second state; an error detection process for detecting an error such that the first state is determined in the state determination process when the operator is absent from the driver's seat; an interlock activation process for activating the interlock regardless of the determination result in the state determination process when the error is detected; and is characterized by executing:

[0008] In this configuration, when the interlock unit detects an error in the switch such that the first state is determined in the state determination process when the operator is absent from the driver's seat, the interlock unit activates the interlock, so that it is possible to suppress the inactivation of the safety function (interlock) due to unauthorized modification of the switch or the like.

[0009] In the forklift, the interlock unit, In the error detection process, when a first condition that a predetermined set time has elapsed since the determination of the first state in the state determination process is satisfied, it can be configured to detect this as the error.

[0010] The forklift is provided with a battery that is a power source for the traveling operation and the handling operation, The interlock section In the error detection process, when a second condition that the battery is being charged is satisfied, it can be configured to detect this as the error.

[0011] In the forklift, The interlock section when the second state is determined in the state determination process, a reset process for resetting the detection of the error in the error detection process, and when it is determined that the detection of the error has been reset and the state of the switch is the first state, an interlock release process for releasing the interlock and enabling the traveling operation and the handling operation, can be configured to execute.

[0012] In the forklift, The switch can be configured to include at least one of a seat switch that detects the operator sitting in the driver's seat and a seat belt switch that detects the operator wearing a seat belt provided on the seat in the driver's seat.

[0013] In the forklift, The switch can be configured to include a pedal-type presence switch that detects the operator stepping on a predetermined location in the driver's seat.

[0014] In order to solve the above problems, the interlock unauthorized release prevention method according to the present invention A forklift interlock unauthorized release prevention method comprising: a switch that enters a first state when an operator in the driver's seat is detected and enters a second state when the operator is not detected; and an interlock unit that enables the interlock and disables the traveling operation and the cargo handling operation when the switch is in the second state. A state determination processing step of determining, by the interlock unit, whether the state of the switch is the first state or the second state. An error detection processing step of detecting, by the interlock unit, an error such that the first state is determined in the state determination processing step when the operator is absent from the driver's seat. An interlock enabling processing step of enabling the interlock by the interlock unit regardless of the determination result in the state determination processing step when the error is detected. Characterized by including the above.

[0015] The interlock unauthorized release prevention method A reset processing step of resetting the detection of the error in the error detection processing step when the second state is determined in the state determination processing step by the interlock unit. An interlock release processing step of releasing the interlock and enabling the traveling operation and the cargo handling operation when it is determined by the interlock unit that the detection of the error has been reset and the state of the switch is the first state. Can be configured to include the above.

Advantages of the Invention

[0016] According to the present invention, it is possible to provide a forklift and an interlock unauthorized release prevention method capable of suppressing the invalidation of the safety function.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying out the Invention

[0018] Hereinafter, embodiments of a forklift and an interlock unauthorized release prevention method according to the present invention will be described with reference to the accompanying drawings.

[0019] [Forklift] FIG. 1 shows a forklift 100 according to an embodiment of the present invention. The forklift 100 is a counterbalanced battery forklift and includes a vehicle body 110 and a cargo handling device 120.

[0020] The vehicle body 110 includes a vehicle body frame 111, a pair of left and right front wheels 112A and rear wheels 112B, a driver's seat 113, a head guard 114, an accelerator 115A and a brake 115B, a steering wheel 116, cargo handling levers (tilt lever 117A and lift lever 117B), and a display unit 118.

[0021] The vehicle body frame 111 constitutes the skeleton of the vehicle body 110, and the front wheels 112A and the rear wheels 112B are provided at the lower part. Inside the vehicle body frame 111, a battery BT which is a power source of the forklift 100 and electric motors (travel motor M1, steering motor M2, cargo handling motor M3) driven by the power of the battery BT are accommodated. The front wheel 112A is a drive wheel driven by the travel motor M1, and the rear wheel 112B is a steering wheel steered by the steering motor M2.

[0022] The driver's seat 113 and the head guard 114 are provided on the upper part of the vehicle body frame 111. The driver's seat 113 is the seat for the operator, and the head guard 114 is a protective frame for protecting the operator in the driver's seat 113 from falling luggage or the like. An accelerator 115A and a brake 115B are provided at the lower front part of the driver's seat 113, and the accelerator 115A and the brake 115B are connected to the front wheels 112A via a traveling mechanism including a traveling motor M1.

[0023] A seating switch SW1 and a seat belt switch SW2 corresponding to the "switch" of the present invention are provided on the driver's seat 113. The seating switch SW1 is configured to detect an operator sitting on the driver's seat 113. The seat belt switch SW2 is configured to detect an operator wearing the seat belt provided on the driver's seat 113.

[0024] As shown in FIG. 2, the seating switch SW1 is provided at the lower center of the driver's seat 113, and the seat belt switch SW2 is provided at the left end of the driver's seat 113. The seating switch SW1 is turned on when the operator is sitting on the driver's seat 113 and turned off when the operator is away from the driver's seat 113. The seat belt switch SW2 is turned on when the tongue plate of the seat belt is inserted into the buckle of the seat belt and turned off when the tongue plate is not inserted into the buckle. Note that the positions of the seating switch SW1 and the seat belt switch SW2 shown in FIG. 2 can be changed as appropriate.

[0025] Referring to FIG. 1 again, the accelerator 115A is an accelerator pedal configured to be operable by the operator of the driver's seat 113 stepping on it with the foot. When the accelerator 115A is in the on state (the pedal is depressed), it accelerates the traveling of the vehicle body 110 according to the depression amount of the pedal (accelerator opening), while when it switches from the on state to the off state (the pedal is not depressed), it generates a weak regenerative brake to decelerate the vehicle body 110.

[0026] Brake 115B is a brake pedal configured to be operable by an operator in the driver's seat 113 stepping on it with a foot. When in the on state (the pedal is depressed), brake 115B generates a regenerative brake stronger than the regenerative brake of accelerator 115A to decelerate the vehicle body 110, while when in the off state (the pedal is not depressed), it does not generate a regenerative brake.

[0027] The steering wheel 116 is provided in front of the driver's seat 113. The steering wheel 116 is connected to the rear wheel 112B via a steering mechanism including a steering motor M2. The operator can change the direction of the rear wheel 112B according to the rotation direction by rotating the steering wheel 116. A forward / backward lever for switching the running of the vehicle body 110 between forward and backward is provided at the lower part of the steering wheel 116. When the accelerator 115A is turned on with the forward / backward lever tilted forward, the vehicle body 110 moves forward, and when the accelerator 115A is turned on with the forward / backward lever tilted backward, the vehicle body 110 moves backward.

[0028] The handling levers (tilt lever 117A and lift lever 117B) are provided in front of the driver's seat 113. The handling levers are connected to the handling device 120 via a handling mechanism including a handling motor M3. The operator can cause the handling device 120 to perform a handling operation by operating the handling levers.

[0029] The display unit 118 is provided in front of the driver's seat 113 (for example, on the dashboard). The display unit 118 is configured to visually and / or audibly notify the operator of the driver's seat 113 that the interlock described later is activated. The display unit 118 of the present embodiment includes a display means (for example, a display) and an audio means (for example, a speaker or a buzzer). In addition to the warning display indicating that the interlock is activated, the display means displays a screen indicating the remaining amount of the battery BT, the traveling speed, etc., or a setting screen for performing various settings of the forklift 100. The audio means outputs a warning sound when the interlock is activated. The audio means may be built into the display means or externally attached to the display means.

[0030] The cargo handling device 120 includes a mast 121, a lift bracket 122, forks 123, a backrest 124, a tilt cylinder 125, and a lift cylinder 126.

[0031] The mast 121 is provided on the front side of the vehicle body 110 and is configured to raise and lower the forks 123. The mast 121 includes an outer mast and an inner mast. The outer mast includes a pair of left and right guide rails extending in the vertical direction and a cross beam connecting the upper end portions of the guide rails. The inner mast is provided inside the guide rails of the outer mast and moves up and down along the guide rails of the outer mast.

[0032] The lift bracket 122 supports the fork 123 and is configured to move up and down along the mast 121. The lift bracket 122 is attached to one end of the lift chain and moves up and down along the inner mast while being suspended by the lift chain. The other end of the lift chain is attached to the lower part of the outer mast via a chain wheel provided at the upper part of the lift cylinder 126. The fork 123 is a pair of left and right L-shaped arms and is provided on the front surface of the lift bracket 122. The backrest 124 is a frame for preventing the load loaded on the fork 123 from collapsing backward and is provided at the upper part of the lift bracket 122. When the mast 121 (inner mast) moves up and down, the lift bracket 122, the fork 123, and the backrest 124 also move up and down.

[0033] The tilt cylinder 125 is a hydraulic cylinder for tilting the mast 121 in the front-rear direction. In this embodiment, when the tilt lever 117A is tilted forward, the tilt cylinder 125 extends and the mast 121 tilts forward, and when the tilt lever 117A is tilted backward, the tilt cylinder 125 contracts and the mast 121 tilts backward. When the tilt lever 117A is returned to the neutral position (a position where it is not tilted forward or backward), the tilting of the mast 121 stops.

[0034] The lift cylinder 126 is a hydraulic cylinder for raising and lowering the mast 121. In this embodiment, when the lift lever 117B is tilted forward, the lift cylinder 126 contracts and the inner mast descends, and when the lift lever 117B is tilted backward, the lift cylinder 126 extends and the inner mast ascends. When the lift lever 117B is returned to the neutral position (a position where it is not tilted forward or backward), the raising and lowering of the inner mast stops.

[0035] As shown in FIG. 3, the forklift 100 includes a control mechanism 130. The control mechanism 130 is composed of a traveling sensor 131, a handling sensor 132, a controller 133 (travel control unit 134, handling control unit 135, interlock unit 136), a seating switch SW1, and a seat belt switch SW2.

[0036] The traveling sensor 131 includes an accelerator sensor, a brake sensor, a forward / backward movement sensor, and a vehicle speed sensor. The accelerator sensor detects the operation amount (accelerator opening) of the accelerator 115A and outputs an accelerator operation signal related to the operation amount (accelerator opening) to the travel control unit 134. The brake sensor detects the state (on state / off state) of the brake 115B and outputs a brake operation signal related to the state to the travel control unit 134. The forward / backward movement sensor outputs a forward / backward movement lever operation signal related to the state of the forward / backward movement lever to the travel control unit 134. The vehicle speed sensor detects the traveling speed of the vehicle body 110 (rotation speed of the traveling motor M1) and outputs a speed signal related to the traveling speed to the travel control unit 134.

[0037] The handling sensor 132 includes a tilt sensor and a lift sensor. The tilt sensor detects the tilting angle of the tilt lever 117A and outputs a tilt operation signal related to the tilting angle to the handling control unit 135. The lift sensor detects the tilting angle of the lift lever 117B and outputs a lift operation signal related to the tilting angle to the handling control unit 135.

[0038] The controller 133 is composed of, for example, a microcomputer and is housed inside the vehicle body frame 111. The controller 133 includes a travel control unit 134, a handling control unit 135, an interlock unit 136, a first terminal T1, a second terminal T2, and a ground terminal GND. The seating switch SW1 is interposed in the wiring connecting the first terminal T1 and the ground terminal GND, and the seat belt switch SW2 is interposed in the wiring connecting the second terminal T2 and the ground terminal GND. The first terminal T1 and the second terminal T2 are connected to the interlock unit 136.

[0039] The traveling control unit 134 controls a traveling mechanism including a traveling motor M1. The traveling mechanism includes the traveling motor M1 and a traveling inverter that rotationally drives the traveling motor M1. The traveling control unit 134 acquires various signals (an accelerator operation signal, a brake operation signal, a forward / backward lever operation signal, and a speed signal) from the traveling sensor 131 at a predetermined period and controls the traveling inverter. The control of the traveling inverter is, for example, speed control (e.g., PI control or PID control) for bringing the traveling speed of the forklift 100 closer to a predetermined target speed. When the traveling inverter rotates the traveling motor M1 according to the speed control, the forklift 100 moves forward or backward at a traveling speed corresponding to the rotational speed of the traveling motor M1.

[0040] The handling control unit 135 controls a handling mechanism including a handling motor M3. The handling mechanism includes the handling motor M3, a handling inverter that rotationally drives the handling motor M3, and a hydraulic device. The handling control unit 135 acquires various signals (a tilt operation signal and a lift operation signal) from the handling sensor 132 at a predetermined period and controls the handling inverter. When the handling inverter rotates the handling motor M3, the hydraulic device moves an amount of hydraulic oil corresponding to the rotational speed of the handling motor M3 to extend / contract the tilt cylinder 125 and / or the lift cylinder 126.

[0041] The interlock unit 136 executes an "interlock unauthorized release prevention method" described later. Specifically, the interlock unit 136 executes a state determination process (in this embodiment, a seating determination process and a seat belt wearing determination process), an error detection process, a reset process, and an interlock process.

[0042] The sitting determination process is a process for determining whether the sitting switch SW1 is in the ON state (corresponding to the "first state" of the present invention) or the OFF state (corresponding to the "second state" of the present invention). The interlock unit 136 acquires the voltage value of the first terminal T1 at a predetermined cycle, and determines that the sitting switch SW1 is in the ON state when the voltage value of the first terminal T1 is the same as the voltage value of the ground terminal GND (for example, 0 [V]), and determines that the sitting switch SW1 is in the OFF state when the voltage value of the first terminal T1 is different from the voltage value of the ground terminal GND.

[0043] The seat belt wearing determination process is a process for determining whether the seat belt switch SW2 is in the ON state (corresponding to the "first state" of the present invention) or the OFF state (corresponding to the "second state" of the present invention). The interlock unit 136 acquires the voltage value of the second terminal T2 at a predetermined cycle, and determines that the seat belt switch SW2 is in the ON state when the voltage value of the second terminal T2 is the same as the voltage value of the ground terminal GND, and determines that the seat belt switch SW2 is in the OFF state when the voltage value of the second terminal T2 is different from the voltage value of the ground terminal GND.

[0044] The error detection process is a process for detecting an error in which the sitting switch SW1 and / or the seat belt switch SW2 are determined to be in the ON state in the state determination process when the operator is absent from the driver's seat 113. Note that the operator being absent from the driver's seat 113 means that, in the case of the seat belt switch SW2, the operator wearing the seat belt is absent (the operator in the driver's seat 113 is not wearing the seat belt).

[0045] The above error is mainly an error caused by unauthorized modification of the sitting switch SW1 and the seat belt switch SW2 (for example, modification to short-circuit both ends of the sitting switch SW1 or the seat belt switch SW2). The interlock unit 136 detects the above error when a predetermined error condition is satisfied. The error condition in the present embodiment includes a first condition that a preset time (24 hours in the present embodiment) has elapsed since the determination of the ON state of the sitting switch SW1 or the seat belt switch SW2, and a second condition that the battery BT is being charged.

[0046] The reset process is a process that resets the detection of an error in the error detection process (to make it so that no error is detected) when it is determined in the state determination process that the seat switch SW1 and the seat belt switch SW2 are in the off state. In this embodiment, to reset the detection of an error means to turn off the error setting performed by the interlock unit 136 from on to off.

[0047] The interlock process is a process that switches between enabling and releasing the interlock, and includes an interlock enabling process and an interlock releasing process. The interlock unit 136 enables the interlock (interlock enabling process) when at least one of the seat switch SW1 and the seat belt switch SW2 is in the off state, or when an error is detected. When both the seat switch SW1 and the seat belt switch SW2 are in the on state and no error is detected, the interlock unit 136 releases the interlock (interlock releasing process).

[0048] When the interlock unit 136 enables the interlock, the traveling operation and the handling operation of the forklift 100 are made impossible, and when the interlock is released, the traveling operation and the handling operation of the forklift 100 are made possible. Further, the interlock unit 136 that has enabled the interlock causes the display means of the display unit 118 to perform a warning display and causes the audio means of the display unit 118 to output a warning sound.

[0049] In the forklift 100 according to this embodiment, as described above, in the state determination process, even when it is determined that the seat switch SW1 or the seat belt switch SW2 is in the on state, if an error is detected in the error detection process, the interlock is enabled. Therefore, according to the forklift 100 according to this embodiment, it is possible to suppress the invalidation of the safety function (interlock) due to unauthorized modification of the seat switch SW1 or the seat belt switch SW2 or the like.

[0050] [Method for Preventing Unlawful Release of Interlock] Next, a method for preventing unlawful release of interlock according to an embodiment of the present invention will be described. The method for preventing unlawful release of interlock in this embodiment is executed by the interlock unit 136 of the forklift 100.

[0051] Fig. 4 shows a flowchart of the method for preventing unlawful release of interlock. When the vehicle key switch (power switch) of the forklift 100 is turned on by the operator, the interlock unit 136 starts the process of the method for preventing unlawful release of interlock.

[0052] The interlock unit 136 that has started the process executes a seating determination process for determining whether the seating switch SW1 is in the on state or the off state, and a seat belt wearing determination process for determining whether the seat belt switch SW2 is in the on state or the off state (S1). Here, when an illegal modification is made to short-circuit both ends of the seating switch SW1 (or the seat belt switch SW2), the first terminal T1 (or the second terminal T2) and the ground terminal GND are always in a conductive state. Therefore, even if the seating switch SW1 (or the seat belt switch SW2) is in the off state, the interlock unit 136 determines that the seating switch SW1 (or the seat belt switch SW2) is in the on state. Step S1 corresponds to the "state determination process step" of the present invention.

[0053] When the interlock unit 136 determines that the seating switch SW1 is in the ON state or determines that the seat belt switch SW2 is in the ON state (Yes in S1), it sets a timer (S2). The timer is, for example, a timer built into the microcomputer of the interlock unit 136, and the set time of the timer is set to 24 hours. The set time is set to 24 hours to ensure that the operator is absent, but it can also be changed to a time other than 24 hours. However, the set time is preferably longer than the maximum continuous operating time of the forklift 100 calculated based on the maximum capacity of the battery BT. The set timer counts up the measurement time each time the process of step S2 is performed.

[0054] After the count-up (after setting), the interlock unit 136 determines whether 24 hours have elapsed since the timer was set, that is, whether the first condition of the error condition is satisfied (S3). When the interlock unit 136 determines that 24 hours have elapsed (Yes in S3), it turns on the error setting (S4). Note that the error setting is a setting performed by the interlock unit 136, which is turned on when the error condition is satisfied (when an error is detected) and turned off when the error condition is not satisfied (when no error is detected).

[0055] In the process of step S3, when it is determined that 24 hours have not elapsed (No in S3), the interlock unit 136 determines whether the battery BT is being charged, that is, whether the second condition of the error condition is satisfied (S5). The interlock unit 136 determines that the battery BT is being charged even if no charging current is supplied to the battery BT when the charging preparation of the battery BT is started. Specifically, the interlock unit 136 of the present embodiment determines that the battery BT is being charged when a charging plug is connected to the charging connector provided on the vehicle body 110. Note that the method for determining whether the battery BT is being charged is not limited to this, and for example, it may be determined that the battery BT is being charged when a charging current is supplied to the battery BT.

[0056] When the interlock unit 136 determines that the battery BT is being charged (Yes in S5), it turns on the error setting (S6) and proceeds to the process of step S8. On the other hand, when the interlock unit 136 determines that the battery BT is not being charged (No in S5), it proceeds directly to the process of step S8. Steps S2 to S6 correspond to the "error detection processing step" of the present invention.

[0057] When the interlock unit 136 determines in the determination of step S1 that the seat switch SW1 is in the off state and the seat belt switch SW2 is in the off state (No in S1), it resets the timer (sets the measurement time to 0) and turns off the error setting (S7), and proceeds to the process of step S8. Step S7 corresponds to the "reset processing step" of the present invention.

[0058] The interlock unit 136 that has proceeded to the process of step S8 performs an interlock determination (S8). Specifically, when the interlock unit 136 satisfies at least one of the conditions that the error setting is on, the seat switch SW1 is in the off state, and the seat belt switch SW2 is in the off state (Yes in S8), it activates the interlock to disable the traveling operation and the handling operation of the forklift 100 (S9). As one method of disabling the traveling operation and the handling operation of the forklift 100, the interlock unit 136 invalidates the input of various signals from the traveling sensor 131 in the traveling control unit 134 and invalidates the input of various signals from the handling sensor 132 in the handling control unit 135. Step S9 corresponds to the "interlock activation processing step" of the present invention.

[0059] On the other hand, when all of the conditions that the error setting is off, the seat switch SW1 is in the on state, and the seat belt switch SW2 is in the on state are satisfied (No in S8), the interlock unit 136 releases the interlock to enable the traveling operation and the handling operation of the forklift 100 (S10). Step S10 corresponds to the "interlock release processing step" of the present invention.

[0060] In the method for preventing unlocking of interlock according to this embodiment, as described above, even when it is determined that the seating switch SW1 or the seat belt switch SW2 is in the on state (Yes in S1), if an error is detected (Yes in S3, Yes in S5), the interlock is activated (S9). Therefore, according to the method for preventing unlocking of interlock according to this embodiment, it is possible to suppress the safety function (interlock) from being invalidated due to unauthorized modification of the seating switch SW1 or the seat belt switch SW2. Note that the method for preventing unlocking of interlock according to this embodiment also functions as a method for detecting contact welding failure of the seating switch SW1 and / or the seat belt switch SW2.

[0061] As described above, the embodiments of the forklift and the method for preventing unlocking of interlock according to the present invention have been described, but the present invention is not limited to the above embodiments.

[0062] [Modification Example] FIG. 5 shows a forklift 200 according to a modification example of the present invention. The forklift 200 is a reach - type battery forklift, and includes a vehicle body 210 and a loading / unloading device 220.

[0063] The vehicle body 210 is provided with a driver's seat 213 on which an operator can ride in a standing state. The driver's seat is provided with a dead - man brake 215B and a pedal - type presence switch SW3. The presence switch SW3 corresponds to the "switch" of the present invention, and is in the on state when the operator steps on the pedal of the presence switch SW3, and is in the off state when the operator does not step on the pedal of the presence switch SW3.

[0064] The forklift 200 is provided with a control mechanism including a controller 233. The control mechanism is common to the control mechanism 130 of the above embodiment, except that it includes a presence switch SW3 instead of the seat switch SW1 and the seat belt switch SW2. The controller 233 is common to the controller 133 of the above embodiment, except that the presence switch SW3 is connected instead of the seat switch SW1 and the seat belt switch SW2, and the presence switch determination process is performed instead of the seat determination process and the seat belt wearing determination process.

[0065] The presence switch determination process is a process for determining whether the presence switch SW3 is in an on state (corresponding to the "first state" of the present invention) or an off state (corresponding to the "second state" of the present invention). For example, when the presence switch SW3 is interposed in the wiring connecting the first terminal T1 of the controller 233 and the ground terminal GND, the interlock unit of the controller 233 acquires the voltage value of the first terminal T1 at a predetermined cycle, and when the voltage value of the first terminal T1 is the same as the voltage value of the ground terminal GND (for example, 0 [V]), it determines that the presence switch SW3 is in the on state, and when the voltage value of the first terminal T1 is different from the voltage value of the ground terminal GND, it determines that the presence switch SW3 is in the off state.

[0066] In the forklift 200 according to this modification, the interlock unit of the controller 233 activates the interlock even when an error is detected even if it is determined that the presence switch SW3 is in the on state. Therefore, according to the forklift 200 according to the present embodiment, it is possible to suppress the invalidation of the safety function (interlock) due to unauthorized modification of the presence switch SW3 or the like.

[0067] [Other Modifications] The forklift according to the present invention includes a vehicle body that performs a traveling operation, a loading and unloading device that performs a loading and unloading operation, a driver's seat provided on the vehicle body, a switch that enters a first state when an operator of the driver's seat is detected and enters a second state when no operator is detected, and an interlock unit that enables an interlock and disables the traveling operation and the loading and unloading operation when the switch is in the second state. The interlock unit can appropriately change its configuration if it executes a state determination process for determining whether the state of the switch is the first state or the second state, an error detection process for detecting an error such that the state determination process determines the first state when the operator is absent from the driver's seat, and an interlock enabling process for enabling the interlock regardless of the determination result in the state determination process when an error is detected.

[0068] For example, in the above-described embodiment and modification, the interlock unit detects, as an error, a case where an error condition (the first condition or the second condition) is satisfied in the error detection process and turns on the error setting. However, the error condition may include other conditions (conditions for detecting that the operator is surely absent) instead of the first condition and / or the second condition.

[0069] In the above-described embodiment and modification, the display unit is configured to include a display means (for example, a display) and an audio means (for example, a speaker or a buzzer), but a configuration including only one of them may also be used.

[0070] In the above-described embodiment, a counterbalance type battery forklift is described as an example, and in the modification, a reach type battery forklift is described as an example. However, the forklift of the present invention may be another type of battery forklift, an engine forklift other than a battery forklift, or a hybrid forklift including a battery and an engine.

Description of Reference Numerals

[0071] 100, 200 Forklift 110 and 210 Vehicle Body 111 Body Frame 112A Front Wheel 112B Rear Wheel 113 and 213 Driver's Seat 114 Head Guard 115A Accelerator 115B and 215B Brake 116 Steering Wheel 117A Tilt Lever 117B Lift Lever 118 Display Unit 120 and 220 Cargo Handling Device 121 Mast 122 Lift Bracket 123 Fork 124 Backrest 125 Tilt Cylinder 126 Lift Cylinder 130 Control Mechanism 131 Travel Sensor 132 Cargo Handling Sensor 133 and 233 Controller 134 Travel Control Unit 135 Cargo Handling Control Unit 136 Interlock Unit

Claims

1. A vehicle body that performs a traveling operation, A cargo handling device that performs a cargo handling operation, A driver's seat provided on the vehicle body, A switch that enters a first state when the operator of the driver's seat is detected and enters a second state when the operator is not detected, An interlock unit that enables the interlock and disables the traveling operation and the cargo handling operation when the switch is in the second state, A battery that serves as a power source for the traveling operation and the cargo handling operation, A forklift comprising: The interlock unit: A state determination process for determining whether the state of the switch is the first state or the second state, An error detection process for detecting an error such that the first state is determined in the state determination process when the operator is absent from the driver's seat, An interlock enabling process for enabling the interlock regardless of the determination result in the state determination process when the error is detected, Executes, In the error detection process, a case where the condition that the battery is being charged is satisfied is detected as the error A forklift characterized by the above.

2. A vehicle body that performs a traveling operation, A cargo handling device that performs a cargo handling operation, A driver's seat provided on the vehicle body, A switch that enters a first state when the operator of the driver's seat is detected and enters a second state when the operator is not detected, An interlock unit that enables the interlock and disables the traveling operation and the cargo handling operation when the switch is in the second state, A forklift comprising: The interlock unit: A state determination process for determining whether the state of the switch is the first state or the second state, An error detection process for detecting an error such that the first state is determined in the state determination process when the operator is absent from the driver's seat, An interlock enabling process for enabling the interlock regardless of the determination result in the state determination process when the error is detected, A reset process for resetting the detection of the error in the error detection process when the second state is determined in the state determination process, An interlock release process for releasing the interlock and enabling the traveling operation and the cargo handling operation when it is determined that the detection of the error has been reset and it is determined that the state of the switch is the first state, A forklift characterized by executing the above.

3. The interlock part is in the error detection process, when a first condition that a predetermined set time has elapsed since the first state was determined in the state determination process is satisfied, it is detected as the error The forklift according to claim 1 or 2, characterized in that.

4. The switch is at least one of a seat switch that detects the operator sitting in the driver's seat and a seat belt switch that detects the operator wearing a seat belt provided on the driver's seat The forklift according to claim 1 or **********

5. The switch is a pedal-type presence switch that detects the operator stepping on a predetermined location of the driver's seat The forklift according to claim 1 or 2, characterized in that.

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