JP7715480B2 - Forklift and interlock unauthorized release prevention method - Google Patents

Description

The present invention relates to a forklift and a method for preventing unauthorized release of an interlock.

Forklifts equipped with interlock units have been known for some time. For example, the engine forklift described in Patent Document 1 is equipped with an interlock unit and a seat switch (seat switch) that detects whether the operator in the driver's seat is sitting in the correct posture. When the operator leaves the seat (when the seat switch is off), the interlock unit activates the interlock, disabling the loading and unloading operation of the loading and unloading device.

In the engine forklift described in Patent Document 1, when the interlock is released with the seat switch off, the key switch must be on, the seat switch must be on, and the engine must be running at a predetermined RPM or higher. This condition prevents loading operations (such as lowering the forks) that are contrary to the operator's intentions when the interlock is released.

However, because seat switches have a relatively simple structure, a knowledgeable operator could tamper with them. For example, it is possible to tamper with the seat switch by shorting both ends of the switch so that it is always on. In this case, the safety function (interlock) provided by the interlock section is disabled. This could put the operator at risk.

Patent No. 5226157

The present invention was made in consideration of the above circumstances, and its objective is to provide a forklift and a method for preventing unauthorized release of interlocks that can prevent safety functions from being disabled.

In order to solve the above problems, the forklift according to the present invention comprises:
a vehicle body that performs a traveling operation;
A cargo handling device that performs a cargo handling 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/unloading operation;
A forklift truck 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 the determination result of the state determination process when the error is detected;
The present invention is characterized by carrying out the following.

In this configuration, the interlock unit activates the interlock when it detects a switch error that is judged to be in the first state during the state determination process while the operator is not in the driver's seat, thereby preventing the safety function (interlock) from being disabled by tampering with the switch, etc.

In the forklift,
The interlock portion is
The error detection process may be configured to detect an error when a first condition is satisfied, that is, a predetermined set time has elapsed since the first state was determined to be in the state determination process.

The forklift
a battery serving 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 an error when a second condition is met, that is, when the battery is being charged.

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/unloading operation when it is determined that the error detection has been reset and the state of the switch is determined to be the first state;
can be configured to run

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.

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.

In order to solve the above problems, the method for preventing unauthorized release of an interlock according to the present invention includes:
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 in which the interlock unit determines whether the state of the switch is the first state or the second state;
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 the determination result in the state determination process step when the error is detected by the interlock unit;
The present invention is characterized by comprising:

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/unloading operation when the interlock unit determines that the error detection has been reset and that the state of the switch is the first state;
can be configured to include

The present invention provides a forklift and an interlock unauthorized release prevention method that can prevent safety functions from being disabled.

1 is a side view of a forklift according to the present invention. 1 is a plan view showing the positions of a seat switch (SW1) and a seat belt switch (SW2) of a forklift according to the present invention. FIG. 1 is a block diagram showing a control mechanism of a forklift according to the present invention. 1 is a flow chart of a method for preventing unauthorized release of an interlock according to the present invention. FIG. 10 is a plan view of a forklift according to a modified example of the present invention.

Below, an embodiment of a forklift and an interlock unauthorized release prevention method according to the present invention will be described with reference to the accompanying drawings.

[forklift]
1 shows a forklift 100 according to one 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.

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

The vehicle body frame 111 forms the skeleton of the vehicle body 110, and has front wheels 112A and rear wheels 112B mounted at its bottom. The vehicle body frame 111 houses the battery BT, which is the power source for the forklift 100, and electric motors (travel motor M1, steering motor M2, and loading motor M3) that are driven by the power of the battery BT. The front wheels 112A are drive wheels driven by the travel motor M1, and the rear wheels 112B are steered wheels steered by the steering motor M2.

The driver's seat 113 and head guard 114 are provided on top of the vehicle frame 111. The driver's seat 113 is the operator's seat, and the head guard 114 is a protective frame that protects the operator in the driver's seat 113 from fallen luggage and the like. An accelerator 115A and a brake 115B are provided below and in front of the driver's seat 113, and the accelerator 115A and the brake 115B are connected to the front wheels 112A via a drive mechanism including a drive motor M1.

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 seated in the driver's seat 113. The seat belt switch SW2 is configured to detect an operator wearing a seat belt provided in the driver's seat 113.

As shown in Figure 2, seat switch SW1 is located at the bottom center of the driver's seat 113, and seat belt switch SW2 is located at the left end of the driver's seat 113. Seat 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. 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 seat switch SW1 and seat belt switch SW2 shown in Figure 2 can be changed as appropriate.

Referring again to FIG. 1, accelerator 115A is an accelerator pedal that can be operated by the operator in driver's seat 113 by stepping on it with their foot. When accelerator 115A is in the on state (pedal depressed), it accelerates the vehicle body 110 in accordance with the amount of pedal depression (accelerator opening), while when it switches from the on state to the off state (pedal not depressed), it generates weak regenerative braking to decelerate the vehicle body 110.

Brake 115B is a brake pedal that can be operated by the operator in the driver's seat 113 by stepping on it with their foot. When brake 115B is in the on state (pedal is depressed), it generates regenerative braking that is stronger than the regenerative braking of accelerator 115A, slowing down the vehicle body 110, but when it is in the off state (pedal is not depressed), it does not generate regenerative braking.

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

The load handling levers (tilt lever 117A and lift lever 117B) are located in front of the driver's seat 113. The load handling levers are connected to the load handling device 120 via a load handling mechanism including a load handling motor M3. By operating the load handling levers, the operator can cause the load handling device 120 to perform load handling operations.

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 in the driver's seat 113 that an interlock, which will be described later, is activated. 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., as well as a setting screen for performing various settings for the forklift 100, in addition to displaying a warning that the interlock is activated. The audio means outputs an alarm sound when the interlock is activated. The audio means may be built into the display means or may be externally attached to the display means.

The loading and 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.

The mast 121 is provided at the front of the vehicle body 110 and is configured to raise and lower the forks 123. The mast 121 comprises an outer mast and an inner mast. The outer mast comprises a pair of left and right guide rails extending vertically, and a cross beam connecting 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.

The lift bracket 122 supports the forks 123 and is configured to rise and fall along the mast 121. The lift bracket 122 is attached to one end of a lift chain and rises and falls along the inner mast while suspended from the lift chain. The other end of the lift chain is attached to the bottom of the outer mast via a chain wheel attached to the top of the lift cylinder 126. The forks 123 are a pair of L-shaped arms attached to the front of the lift bracket 122. The backrest 124 is a frame attached to the top of the lift bracket 122 to prevent cargo loaded on the forks 123 from tipping backward. When the mast 121 (inner mast) rises and falls, the lift bracket 122, forks 123, and backrest 124 also rise and fall.

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 rearward, the tilt cylinder 125 contracts and the mast 121 tilts rearward. When the tilt lever 117A is returned to the neutral position (a position that does not tilt the mast 121 forward or rearward), the tilting of the mast 121 stops.

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 lowers, and when the lift lever 117B is tilted backward, the lift cylinder 126 extends and the inner mast rises. When the lift lever 117B is returned to the neutral position (a position where the inner mast is neither tilted forward nor backward), the raising and lowering of the inner mast stops.

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

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 amount of operation (accelerator opening) of the accelerator 115A and outputs an accelerator operation signal related to that 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 that 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 (rotational speed of the driving motor M1) and outputs a speed signal related to that driving speed to the driving control unit 134.

The cargo handling sensors 132 include 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 that 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 that tilt angle to the cargo handling control unit 135.

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 cargo handling 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 installed in the wiring connecting the first terminal T1 and the ground terminal GND, and a seat belt switch SW2 is installed 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.

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 (e.g., 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 rotational speed of the travel motor M1.

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 drives 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 hydraulic oil in an amount corresponding to the rotational speed of the cargo handling motor M3, extending/retracting the tilt cylinder 125 and/or lift cylinder 126.

The interlock unit 136 executes the "interlock unauthorized release prevention method" described below. 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.

The seat occupancy determination process determines whether the seat occupancy 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 seat occupancy switch SW1 is in the on state if 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 seat occupancy switch SW1 is in the off state if the voltage value of the first terminal T1 is different from the voltage value of the ground terminal GND.

The seat belt fastening determination process determines 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 if 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 if the voltage value of the second terminal T2 is different from the voltage value of the ground terminal GND.

The error detection process is a process for detecting an error in which the state determination process determines that the seat switch SW1 and/or seat belt switch SW2 are in the on state when the operator is not in the driver's seat 113. Note that, in the case of the seat belt switch SW2, the absence of the operator in the driver's seat 113 means that the operator is not wearing a seat belt (the operator in the driver's seat 113 is not wearing a seat belt).

The above errors are primarily caused by tampering with the seat switch SW1 and seat belt switch SW2 (for example, shorting both ends of the seat switch SW1 or seat belt switch SW2). The interlock unit 136 detects the above errors when certain error conditions are met. In this embodiment, the error conditions include a first condition that a preset time (24 hours in this embodiment) has elapsed since the seat switch SW1 or seat belt switch SW2 was determined to be in the on state, and a second condition that the battery BT is being charged.

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

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

When the interlock is activated, the interlock unit 136 disables the forklift 100 from traveling and handling cargo, and when the interlock is deactivated, it enables the forklift 100 to travel and handle cargo. 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.

As described above, in the forklift 100 according to this embodiment, even if the state determination process determines that the seat switch SW1 or 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 tampering with the seat switch SW1 or seat belt switch SW2.

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

Figure 4 shows a flow diagram of the interlock unauthorized release prevention method. When the operator turns on the vehicle key switch (power switch) of the forklift 100, the interlock unit 136 begins processing the interlock unauthorized release prevention method.

Once the interlock unit 136 has started processing, it executes a seating determination process to determine whether the seat switch SW1 is in the on state or the off state, and a seat belt fastening determination process to determine whether the seat belt switch SW2 is in the on state or the off state (S1). If the seat 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 will always be in a conductive state. This will cause the interlock unit 136 to determine that the seat switch SW1 (or the seat belt switch SW2) is in the on state, even if the seat switch SW1 (or the seat belt switch SW2) is in the off state. Step S1 corresponds to the "state determination process step" of this invention.

When the interlock unit 136 determines that the seat switch SW1 is on or that the seat belt switch SW2 is on (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 timer's set time is set to 24 hours. The set time is set to 24 hours to reliably detect when the operator is absent, but it can also be changed to a time other than 24 hours. However, it is preferable that the set time be longer than the maximum continuous operating time of the forklift 100, which is calculated based on the maximum capacity of the battery BT. The set timer counts up the measured time each time step S2 is performed.

After counting up (setting), the interlock unit 136 determines whether 24 hours have passed since the timer was set, i.e., whether the first error condition is met (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 met (when an error is detected), and is turned off when the error condition is not met (when an error is not detected).

If it is determined in the processing of step S3 that 24 hours have not elapsed (No in S3), the interlock unit 136 determines whether the battery BT is being charged, i.e., whether the second error condition is met (S5). The interlock unit 136 determines that the battery BT is being charged if preparation for charging the battery BT has begun, even if no charging current is being supplied to the battery BT. Specifically, in this embodiment, the interlock unit 136 determines that the battery BT is being charged when a charging plug is connected to a charging connector provided on the vehicle main body 110. Note that the method for determining whether the battery BT is being charged is not limited to this; for example, the battery BT may be determined to be charging when a charging current is supplied to the battery BT.

If 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 step S8. On the other hand, if the interlock unit 136 determines that the battery BT is not being charged (No in S5), it proceeds directly to step S8. Steps S2 to S6 correspond to the "error detection processing steps" of this invention.

If the interlock unit 136 determines in step S1 that the seat switch SW1 is in the OFF state and that 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 step S8. Step S7 corresponds to the "reset processing step" of this invention.

After proceeding to step S8, the interlock unit 136 performs an interlock determination (S8). Specifically, if at least one of the following conditions is met: the error setting is on, the seat switch SW1 is off, and the seatbelt switch SW2 is off (Yes in S8), the interlock unit 136 activates the interlock and disables the forklift 100 from traveling and handling cargo (S9). As one method for disabling the forklift 100 from traveling and handling cargo, 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 cargo handling sensor 132 in the cargo handling control unit 135. Step S9 corresponds to the "interlock activation processing step" of this invention.

On the other hand, if all of the following conditions are met: 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, allowing the forklift 100 to travel and handle cargo (S10). Step S10 corresponds to the "interlock release processing step" of this invention.

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 in the on state (Yes in S1), if an error is detected (Yes in S3, Yes in S5), the interlock is enabled (S9). Therefore, the interlock unauthorized release prevention method according to this embodiment can prevent the safety function (interlock) from being disabled by unauthorized modifications to 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 contact fusion failures in the seat switch SW1 and/or the seat belt switch SW2.

The above describes an embodiment of the forklift and interlock unauthorized release prevention method according to the present invention, but the present invention is not limited to the above embodiment.

[Modification]
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.

The vehicle body 210 is provided with a driver's seat 213 where the operator sits in a standing position. The driver's seat is equipped with a deadman's brake 215B and a pedal-type presence switch SW3. The presence switch SW3 corresponds to the "switch" in this invention, and is turned on when the operator is pressing the pedal of the presence switch SW3, and is turned off when the operator is not pressing the pedal of the presence switch SW3.

The forklift 200 is equipped with a control mechanism including a controller 233. The control mechanism is the same as the control mechanism 130 of the above embodiment, except that it includes a presence switch SW3 instead of the seating switch SW1 and seat belt switch SW2. The controller 233 is the same as the controller 133 of the above embodiment, except that it is connected to the presence switch SW3 instead of the seating switch SW1 and seat belt switch SW2, and performs presence switch determination processing instead of seating determination processing and seat belt fastening determination processing.

The presence switch determination process determines whether the presence switch SW3 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). For example, if the presence switch SW3 is installed in the wiring connecting the first terminal T1 of the controller 233 to the ground terminal GND, the interlock unit of the controller 233 acquires the voltage value of the first terminal T1 at a predetermined interval and determines that the presence switch SW3 is in the on state if the voltage value of the first terminal T1 is the same as the voltage value of the ground terminal GND (e.g., 0 V). If the voltage value of the first terminal T1 is different from the voltage value of the ground terminal GND, the interlock unit determines that the presence switch SW3 is in the off state.

In the forklift 200 according to this modified example, the interlock unit of the controller 233 activates the interlock if an error is detected, even if it determines 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 modifications to the presence switch SW3, etc.

[Other Modifications]
The forklift of the present invention is a forklift comprising a vehicle body that performs traveling operations, a loading and unloading device that performs loading and unloading operations, a driver's seat provided on the vehicle body, a switch that enters a first state when an operator in the driver's seat is detected and enters a second state when no operator is detected, and an interlock unit that activates an interlock when the switch is in the second state to disable traveling and unloading operations, and the interlock unit can be configured as appropriate as 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 activation process that activates the interlock regardless of the determination result of the state determination process when an error is detected.

For example, in the above embodiment and modified example, 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.

In the above embodiment and variant examples, the display unit is configured to include a display means (e.g., a display) and an audio means (e.g., a speaker or buzzer), but it may also be configured to include only one of these.

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 a different type of battery forklift, an engine forklift other than a battery forklift, or a hybrid forklift equipped with a battery and an engine.

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 unit 120, 220 Load handling device 121 Mast 122 Lift bracket 123 Fork 124 Backrest 125 Tilt cylinder 126 Lift cylinder 130 Control mechanism 131 Travel sensor 132 Load handling sensor 133, 233 Controller 134 Travel control unit 135 Load handling control unit 136 Interlock unit

Claims (5)

a vehicle body that performs a traveling operation;
A cargo handling device that performs a cargo handling 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/unloading operation;
a battery that serves as a power source for the traveling operation and the loading and unloading operation;
A forklift truck 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 the determination result of the state determination process when the error is detected;
Run
In the error detection process, if a condition that the battery is being charged is satisfied, the error is detected.
A forklift characterized by: a vehicle body that performs a traveling operation;
A cargo handling device that performs a cargo handling 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/unloading operation;
A forklift truck 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 the determination result of the state determination process when the error is detected;
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/unloading operation when it is determined that the error detection has been reset and the state of the switch is determined to be the first state;
A forklift characterized by performing The interlock portion is
3. The forklift according to claim 1, wherein the error detection process detects the error when a first condition is satisfied, that is, a predetermined set time has elapsed since the first state was determined in the state determination process. The switch is
3. The forklift according to claim 1, further comprising at least one of a seating switch that detects whether the operator is seated in the driver's seat and a seat belt switch that detects whether the operator is wearing a seat belt provided in the driver's seat. The switch is
3. The forklift according to claim 1 , further comprising a pedal-type presence switch that detects the operator stepping on a predetermined position on the driver's seat.