Forklift and interlock fraudulent 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 release of an interlock. [Background technology]

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

[0003] In the engine forklift described in Patent Document 1, when the interlock is released with the seat switch off, the conditions are that the key switch is on, the seat switch is on, and the engine is at or above a certain RPM. This condition makes it possible to prevent the operator from performing a loading operation (for example, lowering the forks) against his / her will when the interlock is released.

[0004] However, since the seat switch has a relatively simple structure, a knowledgeable operator can tamper with the seat switch. For example, it is possible to tamper with the seat switch by shorting both ends to make it always on, which would disable the safety function (interlock) provided by the interlock unit. This could put the operator at risk. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5226157 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a forklift and a method for preventing unauthorized release of an interlock that can prevent a safety function from being disabled. [Means for solving the problem]

[0007] In order to solve the above problems, the forklift according to the present invention comprises: A vehicle body that performs a traveling operation; A loading device that performs a loading operation; A driver's seat provided in the vehicle body; a switch that is in a first state when an operator in the driver's seat is detected and in a second state when the operator is not detected; an interlock unit that enables an interlock when the switch is in the second state to disable the traveling operation and the loading and unloading operation; A forklift comprising: The interlock portion is 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 that causes the state determination process to determine the first state when the operator is absent from the driver's seat; an interlock enabling process for enabling the interlock regardless of a result of the state determining process when the error is detected; The present invention is characterized by carrying out the following steps.

[0008] In this configuration, the interlock unit activates the interlock when it detects a switch error that is judged to be in the first state in the state determination process when the operator is absent from the driver's seat, thereby preventing the safety function (interlock) from being disabled by tampering with the switch, etc.

[0009] In the forklift, The interlock portion is The error detection process may be configured to detect, as the error, a case that satisfies a first condition that a predetermined set time has elapsed since the first state was determined in the state determination process.

[0010] The forklift is A battery is provided as a power source for the traveling operation and the loading and unloading operation, The interlock portion is The error detection process may be configured to detect the occurrence of an error when a second condition is satisfied, that is, when the battery is being charged.

[0011] In the forklift, The interlock portion is a reset process of 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 to enable the traveling operation and the loading and unloading operation when it is determined that the detection of the error has been reset and the state of the switch is determined to be the first state; can be configured to run

[0012] In the forklift, The switch is The vehicle may be configured to include at least one of a seating 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 in the driver's seat.

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

[0014] In order to solve the above problems, the interlock unauthorized release prevention method according to the present invention comprises the steps of: A method for preventing unauthorized release of an interlock of a forklift, the method comprising: a switch that is in a first state when an operator in a driver's seat is detected and in a second state when the operator is not detected; and an interlock unit that enables an interlock to disable traveling and loading / unloading operations when the switch is in the second state, a state determination process step of determining whether the state of the switch is the first state or the second state by the interlock unit; an error detection processing step of detecting an error that causes the state determination processing step to determine the first state when the operator is absent from the driver's seat by the interlock unit; an interlock enabling process step of enabling the interlock regardless of a result of the determination process step when the error is detected by the interlock unit; The present invention is characterized by comprising:

[0015] The interlock unauthorized release prevention method includes: a reset process step of resetting the detection of the error in the error detection process step when the interlock unit determines that the second state is reached in the state determination process step; an interlock release processing step of releasing the interlock to enable the traveling operation and the loading and unloading operation when the interlock unit determines that the detection of the error has been reset and that the state of the switch is the first state; The information can be configured to include: Effect of the Invention

[0016] According to the present invention, it is possible to provide a forklift and an interlock unauthorized release prevention method that can prevent a safety function from being disabled. [Brief description of the drawings]

[0017] [Figure 1] 1 is a side view of a forklift according to the present invention. [Diagram 2] 1 is a plan view showing the positions of a seat switch (SW1) and a seat belt switch (SW2) of the forklift according to the present invention. FIG. [Diagram 3] 1 is a block diagram showing a control mechanism of a forklift according to the present invention; [Figure 4] 1 is a flow diagram of an interlock unauthorized release prevention method according to the present invention. [Diagram 5] FIG. 11 is a plan view of a forklift according to a modified example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, 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] 1 shows a forklift 100 according to an embodiment of the present invention. The forklift 100 is a counterbalance type battery forklift, and includes a vehicle body 110 and a cargo handling device 120.

[0020] The vehicle body 110 includes a 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 handlebar 116, loading 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 has front wheels 112A and rear wheels 112B provided at the bottom. A battery BT, which is the power source of the forklift 100, and electric motors (a traveling motor M1, a steering motor M2, and a loading motor M3) driven by the electric power of the battery BT are housed inside the vehicle body frame 111. The front wheels 112A are driving wheels driven by the traveling motor M1, and the rear wheels 112B are steering wheels steered by the steering motor M2.

[0022] Driver's seat 113 and head guard 114 are provided on the upper part of body frame 111. Driver's seat 113 is a seat for an operator, and head guard 114 is a protective frame for protecting the operator in driver's seat 113 from dropped baggage and the like. An axel 115A and a brake 115B are provided at the lower front part of driver's seat 113, and the axel 115A and the brake 115B are connected to front wheel 112A via a traveling mechanism including a traveling motor M1.

[0023] The driver's seat 113 is provided with a seating switch SW1 and a seat belt switch SW2, which correspond to the "switch" of the present invention. The seating switch SW1 is configured to detect an operator who is seated in the driver's seat 113. The seat belt switch SW2 is configured to detect an operator who is fastening a seat belt provided in the driver's seat 113.

[0024] As shown in Fig. 2, the seating switch SW1 is provided at the center of the lower part 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 seated in 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 seat belt buckle, and turned off when the tongue plate is not inserted into the buckle. The positions of the seating switch SW1 and the seat belt switch SW2 shown in Fig. 2 can be changed as appropriate.

[0025] 1 again, accelerator 115A is an accelerator pedal configured to be operable by being stepped on by an operator in driver's seat 113. When accelerator 115A is in an on state (pedal is depressed), it accelerates the traveling of vehicle body 110 according to the amount of depression of the pedal (accelerator opening), and when it is switched from the on state to an off state (pedal is not depressed), it generates weak regenerative braking to decelerate vehicle body 110.

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

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

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

[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 at the driver's seat 113 that an interlock, which will be described later, is enabled. The display unit 118 of this embodiment includes a display means (e.g., a display) and an audio means (e.g., a speaker or a buzzer). The display means displays a screen showing the remaining charge of the battery BT, the traveling speed, etc., and displays a setting screen for performing various settings of the forklift 100, in addition to displaying a warning that the interlock is enabled. The audio means outputs an alarm sound when the interlock is enabled. The audio means may be built into the display means or may be externally attached to the display means.

[0030] The loading / unloading device 120 includes a mast 121 , a lift bracket 122 , a fork 123 , a backrest 124 , a tilt cylinder 125 , and a lift cylinder 126 .

[0031] The mast 121 is provided at the front of the vehicle body 110, and is configured to raise and lower the fork 123. The mast 121 includes an outer mast and an inner mast. The outer mast includes a pair of left and right guide rails that extend in the vertical direction, and a cross beam that connects the upper ends of the guide rails. The inner mast is provided inside the guide rails of the outer mast, and rises and falls along the guide rails of the outer mast.

[0032] The lift bracket 122 is configured to support the fork 123 and to move up and down along the mast 121. The lift bracket 122 is attached to one end of a lift chain and moves up and down along the inner mast while being suspended from 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 on the upper part of the lift cylinder 126. The fork 123 is a pair of L-shaped arms on the left and right, and is provided on the front 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 on 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 forward and backward directions. 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 that does not tilt the mast 121 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 expands and the inner mast rises. When the lift lever 117B is returned to the neutral position (a position that does not tilt forward or backward), the raising and lowering of the inner mast stops.

[0035] 3, the forklift 100 includes a control mechanism 130. The control mechanism 130 includes a travel sensor 131, a load sensor 132, a controller 133 (a travel control unit 134, a load control unit 135, and an interlock unit 136), a seat switch SW1, and a seat belt switch SW2.

[0036] The driving sensors 131 include an accelerator sensor, a brake sensor, a forward / reverse 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 driving 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 driving control unit 134. The forward / reverse sensor outputs a forward / reverse lever operation signal related to the state of the forward / reverse lever to the driving control unit 134. The vehicle speed sensor detects the driving speed of the vehicle body 110 (the rotation speed of the driving motor M1), and outputs a speed signal related to the driving speed to the driving control unit 134.

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

[0038] The controller 133 is, for example, composed of a microcomputer, and is housed inside the vehicle body frame 111. The controller 133 includes a travel control unit 134, a loading control unit 135, an interlock unit 136, a first terminal T1, a second terminal T2, and a ground terminal GND. A seating switch SW1 is provided in the wiring connecting the first terminal T1 and the ground terminal GND, and a seat belt switch SW2 is provided 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 travel control unit 134 controls the travel mechanism including the travel motor M1. The travel mechanism includes the travel motor M1 and a travel inverter that rotates and drives the travel motor M1. The travel control unit 134 acquires various signals (accelerator operation signal, brake operation signal, forward / reverse lever operation signal, and speed signal) from the travel sensor 131 at a predetermined cycle and controls the travel inverter. The control of the travel inverter is, for example, speed control (for example, PI control or PID control) that brings the travel speed of the forklift 100 closer to a predetermined target speed. When the travel inverter rotates the travel motor M1 in accordance with the speed control, the forklift 100 moves forward or backward at a travel speed that corresponds to the rotation speed of the travel motor M1.

[0040] The cargo handling control unit 135 controls the cargo handling mechanism including the cargo handling motor M3. The cargo handling mechanism includes the cargo handling motor M3, a cargo handling inverter that rotates the cargo handling motor M3, and a hydraulic device. The cargo handling control unit 135 acquires various signals (tilt operation signal and lift operation signal) from the cargo handling sensor 132 at a predetermined cycle and controls the cargo handling inverter. When the cargo handling inverter rotates the cargo handling motor M3, the hydraulic device moves an amount of hydraulic oil according to the rotation speed of the cargo handling motor M3 to extend / retract 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 fastening determination process), an error detection process, a reset process, and an interlock process.

[0042] The seating determination process is a process for determining whether the seating switch SW1 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). The interlock unit 136 acquires the voltage value of the first terminal T1 at a predetermined period, and determines that the seating switch SW1 is in an on state when the voltage value of the first terminal T1 is the same as the voltage value of the ground terminal GND (e.g., 0 [V]), and determines that the seating switch SW1 is in an 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 fastening determination process is a process for determining whether the seat belt switch SW2 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). The interlock unit 136 acquires the voltage value of the second terminal T2 at a predetermined period, and determines that the seat belt switch SW2 is in an 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 an 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 seating 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. In the case of the seat belt switch SW2, the absence of the operator from the driver's seat 113 means that the operator is absent with the seat belt fastened (the operator in the driver's seat 113 is not fastening the seat belt).

[0045] The above errors are mainly caused by unauthorized modifications to the seat switch SW1 and the seat belt switch SW2 (for example, modifications that short-circuit both ends of the seat switch SW1 or the seat belt switch SW2). The interlock unit 136 detects the above errors when predetermined error conditions are met. The error conditions in this embodiment include a first condition that a preset time (24 hours in this embodiment) has elapsed since the seat switch SW1 or the seat belt switch SW2 was determined to be in the on state, and a second condition that the battery BT is being charged.

[0046] The reset process is a process for resetting the detection of an error in the error detection process (preventing an error from being detected) when the state determination process determines that the seat switch SW1 and the seat belt switch SW2 are in the off state. In this embodiment, resetting the detection of an error means changing the error setting performed by the interlock unit 136 from on to off.

[0047] The interlock process is a process for switching between enabling and disabling the interlock, and includes an interlock enabling process and an interlock disabling 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, the interlock unit 136 enables the interlock (interlock enabling process). When both the seat switch SW1 and the seat belt switch SW2 are in the on state, and when no error is detected, the interlock unit 136 disabling the interlock (interlock disabling process).

[0048] When the interlock unit 136 activates the interlock, it disables the traveling and loading operations of the forklift 100, and when the interlock is released, it enables the traveling and loading operations of the forklift 100. Furthermore, when the interlock is activated, the interlock unit 136 causes the display means of the display unit 118 to display a warning 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, even if the state determination process determines 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, the forklift 100 according to this embodiment can prevent the safety function (interlock) from being disabled due to unauthorized modification of the seat switch SW1 or the seat belt switch SW2.

[0050] [How to prevent unauthorized release of interlock] Next, a method for preventing unauthorized release of an interlock according to an embodiment of the present invention will be described. The method for preventing unauthorized release of an interlock according to the present embodiment is executed by the interlock unit 136 of the forklift 100.

[0051] A flow diagram of the interlock unauthorized release prevention method is shown in Fig. 4. When the operator turns on the vehicle key switch (power switch) of the forklift 100, the interlock unit 136 starts the process of the interlock unauthorized release prevention method.

[0052] The interlock unit 136, which has started the process, executes a seating determination process for determining whether the seating switch SW1 is in an on state or an off state, and a seat belt fastening determination process for determining whether the seat belt switch SW2 is in an on state or an off state (S1). If the seating switch SW1 (or the seat belt switch SW2) has been tampered with by shorting both ends, the first terminal T1 (or the second terminal T2) and the ground terminal GND are always in a conductive state, so that even if the seating switch SW1 (or the seat belt switch SW2) is in an off state, the interlock unit 136 will determine that the seating switch SW1 (or the seat belt switch SW2) is in an on state. Step S1 corresponds to the "state determination process step" of the present invention.

[0053] When the interlock unit 136 determines that the seat switch SW1 is in the on state or 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 reliably detect that the operator is absent, but it can be changed to a time other than 24 hours. However, it is preferable that the set time is 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 measured time every time the process of step S2 is performed.

[0054] After counting up (setting), the interlock unit 136 determines whether 24 hours have passed since the timer was set, that is, whether the first error condition is satisfied (S3). If the interlock unit 136 determines that 24 hours have passed (Yes in S3), it turns on the error setting (S4). Note that the error setting is a setting made by the interlock unit 136, and is turned on when the error condition is satisfied (when an error is detected) and is turned off when the error condition is not satisfied (when an error is not detected).

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

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

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

[0059] On the other hand, if all of the conditions are met, that is, the error setting is off, the seat switch SW1 is on, and the seat belt switch SW2 is on (No in S8), the interlock unit 136 releases the interlock to enable the forklift 100 to travel and handle cargo (S10). Step S10 corresponds to the "interlock release process step" of the present invention.

[0060] As described above, in the interlock unauthorized release prevention method according to this embodiment, even if it is determined that the seat switch SW1 or the seat belt switch SW2 is on (Yes in S1), if an error is detected (Yes in S3, Yes in S5), the interlock is enabled (S9). Therefore, according to the interlock unauthorized release prevention method according to this embodiment, it is possible to prevent the safety function (interlock) from being disabled by unauthorized modification of the seat switch SW1 or the seat belt switch SW2. Note that the interlock unauthorized release prevention method according to this embodiment also functions as a method for detecting a contact fusion failure of the seat switch SW1 and / or the seat belt switch SW2.

[0061] Although the embodiment of the forklift and the method for preventing unauthorized release of interlock according to the present invention have been described above, the present invention is not limited to the above embodiment.

[0062] [Variations] 5 shows a forklift 200 according to a modified example of the present invention. The forklift 200 is a reach-type battery forklift, and includes a vehicle body 210 and a cargo handling device 220.

[0063] A driver's seat 213 in which an operator sits standing is provided on the vehicle body 210, and the driver's seat is provided with a deadman's brake 215B and a pedal-type presence switch SW3. The presence switch SW3 corresponds to the "switch" of the present invention, and is turned on when the operator presses the pedal of the presence switch SW3, and is turned off when the operator does not press the pedal of the presence switch SW3.

[0064] The forklift 200 includes a control mechanism including a controller 233. The control mechanism is the same as the control mechanism 130 of the above embodiment, except that the control mechanism includes a presence switch SW3 instead of the seating switch SW1 and the seat belt switch SW2. The controller 233 is the same as the controller 133 of the above embodiment, except that the presence switch SW3 is connected instead of the seating switch SW1 and the seat belt switch SW2, and that the controller 233 performs a presence switch determination process instead of the seating determination process and the seat belt fastening 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 a wire 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 period, and determines that the presence switch SW3 is in an 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 presence switch SW3 is in an off state when the voltage value of the first terminal T1 is different from the voltage value of the ground terminal GND.

[0066] In the forklift 200 according to this modification, the interlock unit of the controller 233 activates the interlock when an error is detected even if it is determined that the presence switch SW3 is in the on state. Therefore, the forklift 200 according to this embodiment can prevent the safety function (interlock) from being disabled due to unauthorized modification of the presence switch SW3.

[0067] [Other variations] The forklift of the present invention is a forklift equipped with 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 in the vehicle body, a switch that goes to a first state when an operator in the driver's seat is detected and goes to a second state when the operator is not detected, and an interlock unit that enables an interlock to disable traveling and loading and unloading operations when the switch is in the second state, and the configuration of the interlock unit can be modified as appropriate so long as it executes a state determination process that determines whether the state of the switch is the first state or the second state, an error detection process that detects an error that would cause the state determination process to determine the first state when the operator is absent from the driver's seat, and an interlock enabling process that enables the interlock regardless of the determination result of the state determination process when an error is detected.

[0068] For example, in the above embodiment and modified examples, the interlock unit detects an error when an error condition (first condition or second condition) is met in the error detection process and turns on the error setting, but the error condition may include other conditions (conditions for detecting that the operator is definitely absent) instead of the first condition and / or the second condition.

[0069] In the above embodiment and modified examples, 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 it may be configured to include only one of them.

[0070] In the above embodiment, a counterbalance type battery forklift is used as an example, and in the modified example, a reach type battery forklift is used as an example, but 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 equipped with a battery and an engine. [Explanation of symbols]

[0071] 100, 200 Forklift 110, 210 Vehicle body 111 Body frame 112A front wheel 112B rear wheel 113, 213 Driver's seat 114 Head Guard 115A Accelerator 115B, 215B Brake 116 Handle 117A Tilt Lever 117B Lift lever 118 Display section 120, 220 Cargo handling equipment 121 Mast 122 Lift bracket 123 Fork 124 Backrest 125 Tilt Cylinder 126 Lift cylinder 130 Control Mechanism 131 Driving Sensor 132 Loading Sensor 133, 233 Controller 134 Driving control unit 135 Cargo handling control section 136 Interlock section

Claims

1. A vehicle body that performs a traveling operation; A loading device that performs a loading operation; A driver's seat provided in the vehicle body; a switch that is in a first state when an operator in the driver's seat is detected and in a second state when the operator is not detected; an interlock unit that enables an interlock when the switch is in the second state to disable the traveling operation and the loading and unloading operation; A forklift comprising: The interlock portion is 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 that causes the state determination process to determine the first state when the operator is absent from the driver's seat; an interlock enabling process for enabling the interlock regardless of a result of the state determining process when the error is detected; A forklift characterized by performing the following:

2. The interlock portion is In the error detection process, a case where a first condition is satisfied, that is, a predetermined set time has elapsed since the first state was determined in the state determination process, is detected as the error.

2. The forklift according to claim 1 .

3. A battery is provided as a power source for the traveling operation and the loading and unloading operation, The interlock portion is In the error detection process, a case where a second condition that the battery is being charged is satisfied is detected as the error.

2. The forklift according to claim 1 .

4. The interlock portion is a reset process of 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 to enable the traveling operation and the loading and unloading operation when it is determined that the detection of the error has been reset and the state of the switch is determined to be the first state; 2. The forklift according to claim 1, wherein the forklift performs the steps of:

5. The switch is At least one of a seating 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 in the driver's seat.

2. The forklift according to claim 1 .

6. The switch is A pedal-type presence switch is included which detects the operator stepping on a predetermined position on the driver's seat.

2. The forklift according to claim 1 .

7. A method for preventing unauthorized release of an interlock of a forklift, the method comprising: a switch that is in a first state when an operator in a driver's seat is detected and in a second state when the operator is not detected; and an interlock unit that enables an interlock to disable traveling and loading / unloading operations when the switch is in the second state, the method comprising: a state determination process step of determining whether a state of the switch is the first state or the second state by the interlock unit; an error detection processing step of detecting an error that causes the state determination processing step to determine the first state when the operator is absent from the driver's seat by the interlock unit; an interlock enabling process step of enabling the interlock regardless of a result of the determination process step when the error is detected by the interlock unit; A method for preventing unauthorized release of an interlock, comprising:

8. a reset process step of resetting detection of the error in the error detection process step when the interlock unit determines that the second state is reached in the state determination process step; an interlock release processing step of releasing the interlock to enable the traveling operation and the loading and unloading operation when the interlock unit determines that the detection of the error has been reset and that the state of the switch is the first state; The method for preventing unauthorized release of an interlock according to claim 7, further comprising:

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