Patent Description:
<CIT> discloses an industrial vehicle that travels by transmitting a driving force of an engine to driven wheels via a driving force transmitting device coupled to the engine. When a driver becomes unseated so that a sitting signal of a sitting detection switch is turned OFF, a controller of the industrial vehicle stops energizing a forward solenoid valve or a reverse solenoid valve after a predetermined delay time elapses. When the driver is seated again, the controller restarts energizing the forward solenoid valve or the reverse solenoid valve if the sitting signal of the sitting detection switch is ON and a forward signal or a reverse signal of a forward/reverse instruction switch is turned ON after the controller detects that an operated direction of a forward/reverse operation lever is neutral.

A driver of an industrial vehicle may be temporarily unseated, for example, in order to check the surrounding situation during driving. However, in the above-described configuration, when an unseated state continues until the delay time elapses, the transmission of the driving force is interrupted. The operational feeling of the industrial vehicle during driving is changed by such interruption of the driving force transmission. As a change in the operational feeling increases, the driving comfort for the driver may be reduced significantly. In addition, there is known from <CIT> a creep torque command interrupt for electric vehicles. A safety monitoring system employs a method of preventing an unwanted drive-off off the vehicle by means of considering amongst others whether the driver has left the vehicle. <CIT> discloses releasing a load handling interlock of a forklift truck under the consideration of a key switch being on, a seat switch being on and the engine being rotated with a predetermined engine speed or more. Further, <CIT> discloses a vehicle driving force control unit which considers amongst others a driver sensing unit for sensing a state in which the driver is not sitting on the driver seat.

The mentioned problems are solved by the subject-matter of the independent claims.

In one aspect, an industrial vehicle according to independent claim <NUM> is provided.

In another aspect, there is provided a method for controlling an industrial vehicle is provided in independent claim <NUM>.

An industrial vehicle <NUM> according to a first background art will now be described.

As shown in <FIG>, the industrial vehicle <NUM> includes a vehicle body <NUM>, two driven wheels <NUM>, <NUM>, two steered wheels <NUM>, a driver's seat <NUM>, and a cargo handling device <NUM>. The industrial vehicle <NUM> of the present embodiment is a counterbalance forklift.

The driven wheels <NUM>, <NUM> are provided in a front lower part of the vehicle body <NUM>. The two driven wheels <NUM>, <NUM> are separated from each other in a vehicle width direction.

The two steered wheels <NUM> are provided in a rear lower part of the vehicle body <NUM>. The two steered wheels <NUM> are separated from each other in the vehicle width direction.

The driver's seat <NUM> is a seat on which a driver sits. The driver's seat <NUM> is provided in an upper part of the vehicle body <NUM>.

The cargo handling device <NUM> includes a mast <NUM>, two forks <NUM>, and lift cylinders <NUM>. The mast <NUM> is provided in front of the vehicle body <NUM>. The forks <NUM> are lifted and lowered together with the mast <NUM>. A cargo is mounted on the forks <NUM>. The lift cylinders <NUM> include hydraulic cylinders. The lift cylinders <NUM> are extended or retracted to lift or lower the mast <NUM>. The forks <NUM> are lifted or lowered as the mast <NUM> is lifted or lowered. The industrial vehicle <NUM> of the present embodiment performs a traveling operation and a cargo handling operation when operated by the driver.

As shown in <FIG>, the industrial vehicle <NUM> includes a controller <NUM>, an accelerator <NUM>, an accelerator sensor <NUM>, a direction instructing unit <NUM>, a direction detecting unit <NUM>, a seat switch <NUM>, a driver detecting unit <NUM>, a travel system <NUM>, and a bus <NUM>.

The controller <NUM> includes a processor <NUM> and a memory <NUM>. The processor <NUM> may include, for example, a central processing unit (CPU), a graphics processing unit (GPU), or a digital signal processor (DSP). The memory <NUM> includes a random-access memory (RAM) and a read-only memory (ROM). The memory <NUM> stores programs for operating the industrial vehicle <NUM>. The memory <NUM> stores program codes or commands configured to cause the processor <NUM> to execute processes. The memory <NUM>, which is a computer-readable medium, includes any type of medium that is accessible by a general-purpose computer or a dedicated computer. The controller <NUM> may include a hardware circuit such as an application specific integrated circuit (ASIC) and a field programmable gate array (FPGA). The controller <NUM>, which is processing circuitry, may include one or more processors that operate according to a computer program, one or more hardware circuits such as an ASIC and an FPGA, or a combination thereof.

The accelerator <NUM> is operated by the driver when accelerating the vehicle body <NUM>. The accelerator <NUM> instructs the controller <NUM> to accelerate the industrial vehicle <NUM> in response to operation by the driver. The accelerator <NUM> is, for example, an accelerator pedal. The accelerator <NUM> may have any specific configuration, and may be a switch, a lever, a touch panel, or the like.

The accelerator sensor <NUM> detects an accelerator operated amount, which is the operated amount of the accelerator <NUM>. The accelerator sensor <NUM> outputs an electric signal that corresponds to the accelerator operated amount to the controller <NUM>. The controller <NUM> acquires the accelerator operated amount based on the electric signal from the accelerator sensor <NUM>.

The direction instructing unit <NUM> is used to instruct the traveling direction of the vehicle body <NUM> in accordance with an operated direction. The traveling direction of the vehicle body <NUM> is regarded as the traveling direction of the industrial vehicle <NUM>. Specifically, the direction instructing unit <NUM> is a direction lever. The operated direction includes a direction instructing a forward movement and a direction instructing a reverse movement. The direction instructing unit <NUM> is configured to be operable in the direction instructing a forward movement or the direction instructing a reverse movement with reference to a neutral position. The specific configuration of the direction instructing unit <NUM> is not limited to a direction bar, but may be a switch, a touch panel, or the like.

The direction detecting unit <NUM> detects the operated direction of the direction instructing unit <NUM>. The direction detecting unit <NUM> is also referred to as a direction sensor. The direction detecting unit <NUM> detects whether the direction instructing unit <NUM> is operated in the direction instructing a forward movement or the direction instructing a reverse movement with reference to the neutral position of the direction instructing unit <NUM>. The direction detecting unit <NUM> outputs an electric signal corresponding to the operated direction of the direction instructing unit <NUM> to the controller <NUM>. The controller <NUM> acquires the operated direction of the direction instructing unit <NUM> based on the electric signal from the direction detecting unit <NUM>. The controller <NUM> recognizes whether a forward movement is instructed by the driver, whether a reverse movement is instructed by the driver, or whether neither is instructed by the driver.

The seat switch <NUM> is a mechanism that is turned ON when the driver is seated on the driver's seat <NUM>. The seat switch <NUM> is provided, for example, under the driver's seat <NUM>. The specific configuration of the seat switch <NUM> is not limited to a switch, but may be a pressure sensitive sensor, a weight sensor, an optical sensor, a camera, or the like.

The driver detecting unit <NUM> is an electronic control unit that detects a driver state. The driver state includes an unseated state and a seated state. In the unseated state, the driver is not seated on the driver's seat <NUM>. In the seated state, the driver is seated on the driver's seat <NUM>. The driver state is detected based on a detection result of the seat switch <NUM>. For example, when the seat switch <NUM> is ON, the driver detecting unit <NUM> determines that the driver state is the seated state. When the seat switch <NUM> is OFF, the driver detecting unit <NUM> determines that the driver state is the unseated state.

The method for detecting the driver state is not limited to the above described method, but may be any appropriate method. For example, when a weight sensor is used as a mechanism corresponding to the seat switch <NUM>, the driver detecting unit <NUM> determines that the driver state is the seated state if the weight detected by the weight sensor is greater than or equal to a specified value, and determines that the driver state is the unseated state if the weight detected by the weight sensor is less than the specified value. When a camera is used as a mechanism corresponding to the seat switch <NUM>, the driver detecting unit <NUM> may extract a specified feature quantity from an image captured by the camera and determine the driver state based on the feature quantity. Examples of the feature quantity include a positional relationship between the driver and the driver's seat <NUM> in the image, the posture of the driver, and the like.

The travel system <NUM> causes the vehicle body <NUM> to travel. The travel system <NUM> includes an engine <NUM>, an output shaft <NUM>, a rotation speed sensor <NUM>, a driving force transmitting mechanism <NUM>, a differential <NUM>, an axle <NUM>, a vehicle speed sensor <NUM>, and a travel controller <NUM>. The industrial vehicle <NUM> is a vehicle having an engine.

The engine <NUM> is a drive source for traveling operation and cargo handling operation of the industrial vehicle <NUM>. The engine <NUM> of the present embodiment is a gasoline engine, which uses gasoline as fuel. The engine <NUM> includes a throttle actuator <NUM>. The fuel of the engine <NUM> is not limited to gasoline, and may be, for example, liquefied petroleum gas (LPG) or compressed natural gas (CNG). The engine <NUM> is not limited to a gasoline engine, and may be a diesel engine, for example.

The throttle actuator <NUM> adjusts a throttle opening degree. The throttle actuator <NUM> adjusts the throttle opening degree to adjust the amount of air supplied to the engine <NUM>. Accordingly, the rotation speed of the engine <NUM> is controlled.

The output shaft <NUM> is coupled to the engine <NUM>. The output shaft <NUM> rotates when driven by the engine <NUM>.

The rotation speed sensor <NUM> is provided at the output shaft <NUM>. The rotation speed sensor <NUM> detects the rotation speed of the engine <NUM>. The rotation speed of the engine <NUM> is also the rotation speed of the output shaft <NUM>. The rotation speed sensor <NUM> outputs an electric signal corresponding to the rotation speed of the output shaft <NUM> to the travel controller <NUM>.

The driving force transmitting mechanism <NUM> transmits the driving force of the engine <NUM> to the driven wheels <NUM>, <NUM>. The driving force transmitting mechanism <NUM> includes a torque converter <NUM>, a transmission <NUM>, and two electromagnetic valves <NUM>.

The torque converter <NUM> is coupled to the output shaft <NUM>. The driving force of the engine <NUM> is transmitted to the torque converter <NUM> via the output shaft <NUM>. The torque converter <NUM> includes a pump and turbine that are coupled to the output shaft <NUM>. In the torque converter <NUM>, the turbine is rotated by hydraulic oil discharged from the pump.

The transmission <NUM> includes an input shaft <NUM>, a forward clutch <NUM>, a forward gear train <NUM>, a reverse clutch <NUM>, a reverse gear train <NUM>, and an output shaft <NUM>.

The input shaft <NUM> is coupled to the torque converter <NUM>. The driving force is transmitted from the torque converter <NUM> to the transmission <NUM> via the input shaft <NUM>.

The forward clutch <NUM> is provided at the input shaft <NUM>. The forward gear train <NUM> is provided between the forward clutch <NUM> and the output shaft <NUM>. The forward clutch <NUM> is switched between an engaged state and a disengaged state. The engaged state is a state in which the input shaft <NUM> and the forward gear train <NUM> are connected to each other. The disengaged state is a state in which the input shaft <NUM> and the forward gear train <NUM> are disconnected from each other. When the forward clutch <NUM> connects the input shaft <NUM> and the forward gear train <NUM> to each other, the driving force is transmitted from the input shaft <NUM> to the forward gear train <NUM>. The driving force transmitted to the forward gear train <NUM> is then transmitted to the output shaft <NUM>. When the forward clutch <NUM> is connected to the forward gear train <NUM>, the driving force of the engine <NUM> is transmitted to the output shaft <NUM>. When the forward clutch <NUM> and the forward gear train <NUM> are disconnected from each other, the driving force is not transmitted from the input shaft <NUM> to the forward gear train <NUM>.

The reverse clutch <NUM> is provided at the input shaft <NUM>. The reverse gear train <NUM> is provided between the reverse clutch <NUM> and the output shaft <NUM>. The reverse clutch <NUM> is switched between an engaged state and a disengaged state. The engaged state is a state in which the input shaft <NUM> and the reverse gear train <NUM> are connected to each other. The disengaged state is a state in which the input shaft <NUM> and the reverse gear train <NUM> are disconnected from each other. When the reverse clutch <NUM> connects the input shaft <NUM> and the reverse gear train <NUM> to each other, the driving force is transmitted from the input shaft <NUM> to the reverse gear train <NUM>. The driving force transmitted to the reverse gear train <NUM> is then transmitted to the output shaft <NUM>. When the reverse clutch <NUM> is connected to the reverse gear train <NUM>, the driving force of the engine <NUM> is transmitted to the output shaft <NUM>. When the reverse clutch <NUM> and the reverse gear train <NUM> are disconnected from each other, the driving force is not transmitted from the input shaft <NUM> to the reverse gear train <NUM>.

The forward clutch <NUM> and the reverse clutch <NUM> are hydraulic clutches. The hydraulic clutches may be wet multi-disc clutches.

The output shaft <NUM> receives the driving force when the forward clutch <NUM> or the reverse clutch <NUM> is engaged. The output shaft <NUM> is rotated by the driving force transmitted from the forward clutch <NUM> or the reverse clutch <NUM>.

The two electromagnetic valves <NUM> correspond to the forward clutch <NUM> and the reverse clutch <NUM>, respectively. The electromagnetic valves <NUM> control supply and discharge of hydraulic oil to and from the forward clutch <NUM> and the reverse clutch <NUM>. The electromagnetic valves <NUM> supply or discharge hydraulic oil in accordance with the amount of electricity supplied to the solenoids. The clutches <NUM>, <NUM> are respectively switched between the engaged state and the disengaged state of by supply and discharge of hydraulic oil by the electromagnetic valves <NUM>. When the direction instructing unit <NUM> instructs a forward movement, the forward clutch <NUM> and the forward gear train <NUM> are connected to each other. When the direction instructing unit <NUM> instructs a backward movement, the reverse clutch <NUM> and the reverse gear train <NUM> are connected to each other. When the direction instructing unit <NUM> instructs a neutral state, that is, when the direction instructing unit <NUM> is in the neutral position, the forward clutch <NUM> and the reverse clutch <NUM> are both disengaged. When one of the forward clutch <NUM> and the reverse clutch <NUM> is engaged, resistance is produced in the engine <NUM> due to engine braking. In contrast, when the forward clutch <NUM> and the reverse clutch <NUM> are both disengaged, no resistance is produced in the engine <NUM> due to engine braking.

The electromagnetic valve <NUM> is configured to be controlled by the controller <NUM>. The controller <NUM> controls the amount of electricity to the solenoids in the electromagnetic valves <NUM>, thereby controlling supply and discharge of hydraulic oil by the electromagnetic valve <NUM>.

The differential <NUM> is coupled to the output shaft <NUM>. The axle <NUM> is coupled to the differential <NUM>. The driven wheels <NUM>, <NUM> are coupled to the axle <NUM>. The axle <NUM> rotates as the output shaft <NUM> rotates. The industrial vehicle <NUM> travels when the driven wheels <NUM>, <NUM> are rotated by rotation of the axle <NUM>. When the forward clutch <NUM> and the forward gear train <NUM> are connected to each other, the industrial vehicle <NUM> moves forward. When the reverse clutch <NUM> and the reverse gear train <NUM> are connected to each other, the industrial vehicle <NUM> moves backward.

The vehicle speed sensor <NUM> is a sensor for detecting a vehicle speed, that is, a moving speed of the vehicle body <NUM>. The moving speed of the vehicle body <NUM> is regarded as the traveling speed of the industrial vehicle <NUM>. The vehicle speed sensor <NUM> is provided, for example, at the output shaft <NUM> or the axle <NUM>. The vehicle speed sensor <NUM> outputs a pulse signal corresponding to the vehicle speed to the travel controller <NUM>.

The travel controller <NUM> is an engine control unit that controls the engine <NUM>. The hardware configuration of the travel controller <NUM> is, for example, similar to that of the controller <NUM>. The travel controller <NUM> adjusts the throttle opening degree by controlling the throttle actuator <NUM>. The driving force of the engine <NUM> is adjusted by adjusting the throttle opening degree. The travel controller <NUM> controls the electromagnetic valve <NUM> that switches the clutches <NUM>, <NUM> between the engaged state and the disengaged state. Accordingly, the clutches <NUM>, <NUM> is switched between the engaged state and the disengaged state.

The travel controller <NUM> and the controller <NUM> are configured to obtain information from each other via the bus <NUM>. The controller <NUM> transmits a specified command signal via the bus <NUM>. In this manner, the controller <NUM> controls the engine <NUM> via the travel controller <NUM>. The command signal is, for example, a target value of the torque or the rotation speed of the engine <NUM>. The target value is determined, for example, in accordance with operation of the accelerator <NUM>. The travel controller <NUM> of the present embodiment controls the throttle actuator <NUM> such that the rotation speed of the engine <NUM> detected by the rotation speed sensor <NUM> becomes the target value. Accordingly, the engine <NUM> generates driving force. The driving force of the engine <NUM> accelerates the industrial vehicle <NUM>. Therefore, the accelerator <NUM> is regarded as a device that instructs acceleration by the driving force of the engine <NUM> in response to operation by the driver.

Further, the controller <NUM> is capable of acquiring the rotation speed of the engine <NUM> detected by the rotation speed sensor <NUM> via the bus <NUM> and the travel controller <NUM>.

The controller <NUM> sets the operation mode M based on the driver state detected by the driver detecting unit <NUM>. The operation mode M includes a normal mode M1, a limit mode M2, and an interruption mode M3.

The normal mode M1 is a mode in which the industrial vehicle <NUM> travels in response to operation by the driver. In the normal mode M1, the industrial vehicle <NUM> is accelerated in accordance with an operated amount of the accelerator <NUM>. That is, the normal mode M1 is an operation mode M in which acceleration of the industrial vehicle <NUM> is controlled by operation of the accelerator <NUM>. In the normal mode M1, the solenoid of the electromagnetic valve <NUM> is energized in response to operation of the direction instructing unit <NUM>. As a result, the electromagnetic valve <NUM> supplies or discharges hydraulic oil in accordance with operation of the direction instructing unit <NUM>. The operation mode M when the industrial vehicle <NUM> is activated, that is, the initial state of the operation mode M is the normal mode M1.

The limit mode M2 is a mode in which the driving force of the engine <NUM> is limited. In the limit mode M2, the controller <NUM> limits the target value of the rotation speed of the engine <NUM> up to a specified limit value. Accordingly, acceleration of the industrial vehicle <NUM> by the accelerator <NUM> is limited. That is, the limit mode M2 is an operation mode M in which acceleration of the industrial vehicle <NUM> by the accelerator <NUM> is limited. The limit value is, for example, the rotation speed of the engine <NUM> during idling. The controller <NUM> transmits the target value of the rotation speed to the travel controller <NUM>. When the target value that corresponds to the operated amount of the accelerator <NUM> is greater than the limit value, the controller <NUM> sets the target value of the rotation speed to the limit value. The travel controller <NUM> controls the engine <NUM> such that the rotation speed of the engine <NUM> becomes the target value transmitted from the controller <NUM>.

The target value of the rotation speed of the engine <NUM> may be set to the limit value in the normal mode M1. In this case, the limit value in the limit mode M2 is less than the limit value in the normal mode M1. The limit mode M2 is an operation mode M in which the limit value of the rotation speed of the engine <NUM> is less than that in the normal mode M1. In other words, the normal mode M1 is an operation mode M in which the limit value is greater than that in the limit mode M2.

In the limit mode M2, the solenoid of the electromagnetic valve <NUM> is energized in response to operation of the direction instructing unit <NUM>. As a result, the electromagnetic valve <NUM> supplies or discharges hydraulic oil in accordance with operation of the direction instructing unit <NUM>.

The interruption mode M3 is a mode in which the transmission of the driving force to the driven wheels <NUM>, <NUM> by the driving force transmitting mechanism <NUM> is interrupted. In the interruption mode M3, the controller <NUM> stops energizing the solenoid of the electromagnetic valve <NUM>. Accordingly, the supply of hydraulic oil to the clutches <NUM>, <NUM> is stopped. Therefore, unlike the normal mode M1 or the limit mode M2, the clutches <NUM>, <NUM> are both disengaged in the interruption mode M3 regardless of the operated direction of the direction instructing unit <NUM>. When the clutches <NUM>, <NUM> are both disengaged, the driving force from the engine <NUM> to the driven wheels <NUM>, <NUM> is interrupted by the driving force transmitting mechanism <NUM>. Accordingly, in the interruption mode M3, the driving force is not transmitted from the engine <NUM> to the driven wheels <NUM>, <NUM> even though the engine <NUM> is running. The interruption mode M3 is thus an operation mode M in which the industrial vehicle <NUM> cannot be accelerated by operation of the accelerator <NUM>. In the interruption mode M3, since the transmission of the driving force by the driving force transmitting mechanism <NUM> is interrupted, creep does not occur.

The controller <NUM> performs a travel controlling process for controlling the travel of the industrial vehicle <NUM> based on the operation mode M. One example of the travel controlling process will now be described. The travel controlling process of the present embodiment is repeatedly performed while the industrial vehicle <NUM> is activated.

As shown in <FIG>, the controller <NUM> determines whether the driver state is the unseated state in step S1. This determination is made based on, for example, a detection result of the driver detecting unit <NUM>.

If the determination result in step S1 is affirmative, that is, if the driver state is the unseated state, the process of step S2 is performed. In step S2, the controller <NUM> performs an unseated state process. The unseated state process is a process for setting the operation mode M when the driver state is the unseated state. After the unseated state process ends, the controller <NUM> ends the travel controlling process and restarts the travel controlling process from step S1.

The controller <NUM> of the present embodiment performs the unseated state process when an unseated state duration T1 becomes longer than or equal to a specified suspension time Td. The unseated state duration T1 is a period during which the unseated state continues. Specifically, the unseated state duration T1 is a time period during which the unseated state continues from the time at which the driver detecting unit <NUM> detects the unseated state. The suspension time Td may be set freely. For example, the suspension time Td is <NUM> seconds or shorter, preferably <NUM> seconds or shorter. When the unseated state duration T1 is shorter than the suspension time Td, the controller <NUM> omits the unseated state process and ends the travel controlling process.

An example of the unseated state process in step S2 will now be described.

As shown in <FIG>, the controller <NUM> determines whether the unseated state duration T1 is shorter than or equal to a specified unseated state determination time Tx in step S21. The unseated state determination time Tx can be set arbitrarily based on expected manners in which the unseated state occurs. The unseated state determination time Tx may be set arbitrarily as long as it is longer than the suspension time Td, and is, for example, <NUM> second or longer and <NUM> seconds or shorter, and preferably <NUM> seconds or longer and <NUM> seconds or shorter. The controller <NUM> performing the process of step S21 corresponds to an unseated state determining unit of the present embodiment.

In a case in which the determination result in step S21 is affirmative, the process of step S22 is performed. The case in which the determination result in step S21 is affirmative corresponds to a case in which the unseated state duration T1 is determined to be shorter than or equal to the unseated state determination time Tx. In step S22, the controller <NUM> sets the operation mode M to the limit mode M2. In this case, the controller <NUM> changes the operation mode M from the normal mode M1 to the limit mode M2. The controller <NUM> performing the process of step S22 corresponds to a limit setting unit of the present embodiment.

In a case in which the determination result in step S21 is negative, the process of step S23 is performed. The case in which the determination result in step S21 is negative corresponds to a case in which the controller <NUM>, which serves as the unseated state determining unit, determines that the unseated state duration T1 is longer than the unseated state determination time Tx. In step S23, the controller <NUM> sets the operation mode M to the interruption mode M3. In this case, the controller <NUM> changes the operation mode M from the limit mode M2 to the interruption mode M3. The controller <NUM> performing the process of step S23 corresponds to an interruption setting unit of the present embodiment.

After the process of step S22 or step S23, the controller <NUM> ends the unseated state process.

If the determination result in step S1 is negative, that is, if the driver state is the seated state, the process of step S3 is performed as shown in <FIG>. In step S3, the controller <NUM> determines whether the operation mode M is the normal mode M1.

If the determination result in step S3 is affirmative, the controller <NUM> ends the travel controlling process while maintaining the operation mode M at the normal mode M1. That is, if the industrial vehicle <NUM> is traveling in the normal mode M1 with the driver state being the seated state, the travel in the normal mode M1 is continued.

In a case in which the determination result in step S3 is negative, the process of step S4 is performed. The case in which the determination result in step S3 is negative corresponds to a case in which the operation mode M is set to the limit mode M2 or the interruption mode M3. A situation that corresponds to such a case includes, for example, a situation in which the limit mode M2 or the interruption mode M3 is set by the unseated state process in step S2 performed in the past, and is maintained. In step S4, the controller <NUM> performs the returning process. The returning process is a process for setting, to the normal mode M1 again, the operation mode M that has been set to the limit mode M2 or the interruption mode M3. After the returning process ends, the controller <NUM> ends the travel controlling process and restarts the travel controlling process from step S1.

An example of the returning process in step S4 will now be described.

As shown in <FIG>, the controller <NUM> determines whether the operation mode M is set to the limit mode M2 in step S41.

If the determination result in step S41 is affirmative, that is, if the operation mode M is set to the limit mode M2, the process of step S42 is performed. In step S42, in a case in which the operation mode M is set to the limit mode M2, the controller <NUM> sets the operation mode M to the normal mode M1 when the driver state detected by the driver detecting unit <NUM> becomes the seated state. In order to perform the process of step S42 in the present embodiment, it suffices if the driver state is switched from the unseated state to the seated state, and the accelerator <NUM> or the direction instructing unit <NUM> does not necessarily need to be operated. In this case, the controller <NUM> changes the operation mode M from the limit mode M2 to the normal mode M1.

The time at which the controller <NUM> changes the operation mode M from the limit mode M2 to the normal mode M1 is not limited to the time at which the driver detecting unit <NUM> detects the seated state. For example, the controller <NUM> may change the operation mode M from the limit mode M2 to the normal mode M1 when a specified suspension time elapses after the driver detecting unit <NUM> detects the seated state.

If the determination result in step S41 is negative, that is, if the operation mode M is set to the interruption mode M3, the process of step S43 is performed. In step S43, the controller <NUM> determines whether a specified cancellation condition is met. The cancellation condition is a condition that needs to be met in order to reset the operation mode M to the normal mode M1. The cancellation condition includes a condition in which the driver state is the seated state and a condition in which the direction detecting unit <NUM> has detected a change in an operation position. The condition in which the direction detecting unit <NUM> has detected a change in the operation position refers to a condition in which the operated direction of the direction instructing unit <NUM> has been changed.

In a case in which the determination result in step S43 is affirmative, that is, in a case in which the cancellation condition is met, the process of step S42 is performed. The case in which the cancellation condition is met includes a case in which the driver state is the seated state and the direction detecting unit <NUM> has detected a change in the operation position. In step S42, the controller <NUM> sets the operation mode M to the normal mode M1. If the controller <NUM> performs the process of step S42 in the returning process, the controller <NUM> changes the operation mode M from the interruption mode M3 to the normal mode M1 in step S42.

If the determination result in step S43 is negative, that is, if the cancellation condition is not met, the controller <NUM> omits step S42 and ends the returning process. Therefore, the operation mode M is maintained at the interruption mode M3.

Operation of the present embodiment will now be described.

The driver may become unseated from the driver's seat <NUM> while the industrial vehicle <NUM> is traveling in the normal mode M1. Such an unseated state occurs, for example, when the driver checks the surrounding situation. Particularly, in the industrial vehicle <NUM> such as a forklift, the cargo handling device <NUM> or a cargo mounted on the cargo handling device <NUM> may block the forward field of vision from the driver's seat <NUM>. Therefore, even in a situation in which the industrial vehicle <NUM> is traveling, the driver may stand up from the driver's seat <NUM> in order to check the situation in front of the industrial vehicle <NUM>. In this case, the driver detecting unit <NUM> detects that the driver state has become the unseated state. Accordingly, the determination result in step S1 is affirmative, and the unseated state process is performed in step S2.

At least immediately after the driver becomes unseated from the driver's seat <NUM>, the unseated state duration T1 is shorter than or equal to the unseated state determination time Tx. Accordingly, the determination result in step S21 is affirmative, and the operation mode M is changed to the limit mode M2 in step S22. Specifically, the operation mode M is changed from the normal mode M1 to the limit mode M2. Thus, the target value of the rotation speed of the engine <NUM> transmitted from the controller <NUM> to the travel controller <NUM> is lower than that in the normal mode M1. Accordingly, the rotation speed of the engine <NUM> is reduced. At this time, the transmission of the driving force by the driving force transmitting mechanism <NUM> is not interrupted. Therefore, in the limit mode M2, the resistance of the engine <NUM> due to engine braking is transmitted to the driven wheels <NUM>, <NUM> via the driving force transmitting mechanism <NUM> as in the normal mode M1.

If the driver continues being unseated after the operation mode M is set to the limit mode M2, the unseated state duration T1 becomes longer than the unseated state determination time Tx. In this case, the determination result in step S21 is negative. The controller <NUM> thus sets the operation mode M to the interruption mode M3 in step S23. Specifically, the controller <NUM> changes the operation mode M from the limit mode M2 to the interruption mode M3. Accordingly, the controller <NUM> stops energizing the solenoid of the electromagnetic valve <NUM> and interrupts the transmission of the driving force by the driving force transmitting mechanism <NUM>. As a result, in the interruption mode M3, unlike the cases of the normal mode M1 or the limit mode M2, the resistance of the engine <NUM> due to engine braking is not transmitted to the driven wheels <NUM>, <NUM>.

The present embodiment has the following advantages.

(<NUM>-<NUM>) The operation mode M includes the normal mode M1, the limit mode M2, which limits the driving force of the engine <NUM>, and the interruption mode M3, which interrupts the transmission of the driving force by the driving force transmitting mechanism <NUM>. If it is determined in step S21 that the unseated state duration T1 is shorter than or equal to the unseated state determination time Tx, the controller <NUM> performs the process of step S22 to set the operation mode M to the limit mode M2. If it is determined in step S21 that the unseated state duration T1 is longer than the unseated state determination time Tx, the controller <NUM> performs the process of step S23 to set the operation mode M to the interruption mode M3.

With this configuration, even if the driver becomes unseated from the driver's seat <NUM> so that the driver state is the unseated state, the controller <NUM> sets the operation mode M to the limit mode M2 if the unseated state duration T1 is shorter than or equal to the unseated state determination time Tx. At this time, the driving force is limited without the transmission of the driving force being interrupted if the duration of the unseated state is short, that is, if the unseated state duration T1 is shorter than or equal to the unseated state determination time Tx. If the unseated state continues after the operation mode M is set to the limit mode M2 so that the unseated state duration T1 becomes longer than the unseated state determination time Tx, the operation mode M, which has been set to the limit mode M2, is set to the interruption mode M3.

Accordingly, the transmission of the driving force is interrupted after the driving force is limited in the limit mode M2.

As a result, a change in the operational feeling of the industrial vehicle <NUM> due to the driver becoming unseated from the driver's seat <NUM> is reduced as compared to a case in which the operation mode M, which has been set to the normal mode M1, is set to the interruption mode M3 without being set to the limit mode M2. As such, the driving comfort of the industrial vehicle <NUM> is prevented from being reduced.

(<NUM>-<NUM>) In a case in which the operation mode M is set to the limit mode M2, the controller <NUM> performs the process of step S42 to set the operation mode M to the normal mode M1 when the driver state detected by the driver detecting unit <NUM> becomes the seated state.

With this configuration, even in a case in which the operation mode M is set to the limit mode M2, the operation mode M returns to the normal mode M1 through a simple operation of, for example, the driver sitting on the driver's seat <NUM> again. Therefore, it is easy to return the operation mode M from the limit mode M2 to the normal mode M1.

(<NUM>-<NUM>) When the operation mode M is set to the interruption mode M3, the controller <NUM> determines whether the driver state is the seated state in step S43 and whether the direction detecting unit <NUM> has detected a change in the operated direction of the direction instructing unit <NUM>. When the determination result in step S43 is affirmative, the controller <NUM> performs the process of step S42 to set the operation mode M to the normal mode M1.

With this configuration, when the transmission of the driving force is interrupted in the interruption mode M3, the driver needs to sit on the driver's seat <NUM> in order to return the operation mode M to the normal mode M1. In addition to this, in order to return the operation mode M to the normal mode M1, it is necessary to change the operation position by operating the direction instructing unit <NUM>. Thus, the operation mode M can be returned to the normal mode M1 not only when the driver is seated, but also when the driver indicates their intention to continue driving the industrial vehicle <NUM> by operating the direction instructing unit <NUM>. This reduces the possibility that the operation mode M will be returned to the normal mode M1 without the driver's intention of driving the industrial vehicle <NUM>, so the safety of the industrial vehicle <NUM> is improved.

An industrial vehicle <NUM> according to a second embodiment will now be described. The same reference numerals are given to those components in the second embodiment that are the same as the corresponding components of the first embodiment, and redundant explanations may be omitted.

As shown in <FIG>, part of the sequence of the unseated state process is different between the first embodiment and the second embodiment. One example of the unseated state process according to the second embodiment will now be described.

In step S101, the controller <NUM> determines whether the industrial vehicle <NUM> is in a stopped state. The controller <NUM> performing the process of step S101 corresponds to a stopped state determining unit of the present embodiment. The controller <NUM> of the present embodiment determines whether the industrial vehicle <NUM> is in a stopped state based on the vehicle speed detected by the vehicle speed sensor <NUM>. When the vehicle speed detected by the vehicle speed sensor <NUM> is greater than a specified speed threshold, the controller <NUM> determines that the industrial vehicle <NUM> is traveling. When the vehicle speed is lower than or equal to the speed threshold, the controller <NUM> determines that the industrial vehicle <NUM> is in a stopped state. The determination of whether the industrial vehicle <NUM> is traveling or in a stopped state is not limited to the method described above, and any method can be employed. For example, the controller <NUM> may perform the determination based on a detection result of the rotation speed sensor <NUM>.

In a case in which the determination result in step S101 is affirmative, the process of step S23 is performed. The case in which the determination result in step S101 is affirmative corresponds to a case in which the unseated state is detected while the industrial vehicle <NUM> is in a stopped state. In step S23, the controller <NUM> sets the operation mode M to the interruption mode M3. In this case, the controller <NUM> changes the operation mode M from the normal mode M1 to the interruption mode M3. The controller <NUM> performing the processes of step S101 and step S23 corresponds to a forcible interruption unit of the present embodiment.

If the determination result in step S101 is negative, that is, if it is determined that the industrial vehicle <NUM> is traveling, the process of step S102 is performed. In step S102, the controller <NUM> determines whether the accelerator <NUM> is being operated. Whether the accelerator <NUM> is being operated is used as an index indicating whether the driver has an intention to drive the industrial vehicle <NUM>.

If the determination result in step S102 is negative, that is, if it is determined that the accelerator <NUM> is not being operated, the process of step S21 is performed. Thus, if the unseated state is detected in a situation in which the accelerator <NUM> is not being operated in the normal mode M1, the operation mode M is changed from the normal mode M1 to the limit mode M2 in step S22, or the operation mode M is changed from the normal mode M1 to the interruption mode M3 in step S23.

If the determination result in step S102 is affirmative, that is, if the accelerator <NUM> is being operated, the process of step S103 is performed. In step S103, the controller <NUM> determines whether the operation mode M is the normal mode M1.

If the determination result in step S103 is negative, that is, if the operation mode M is the limit mode M2 or the interruption mode M3, the process of step S21 is performed. In this manner, the controller <NUM> sets the operation mode M to the limit mode M2 or the interruption mode M3 in accordance with the unseated state duration T1.

In a case in which the determination result in step S103 is affirmative, the process of step S104 is performed. The case in which the determination result in step S103 is affirmative corresponds to a case in which the unseated state is detected while the accelerator <NUM> is being operated in the normal mode M1. The controller <NUM> determines whether the unseated state duration T1 is shorter than or equal to the unseated state determination time Tx in step S104.

In a case in which the determination result in step S104 is negative, the process of step S23 is performed. The case in which the determination result in step S104 is negative is, for example, a case in which the accelerator <NUM> has been operated for a period longer than the unseated state determination time Tx while the unseated state continues. In this case, the controller <NUM> sets the operation mode M to the interruption mode M3. Thus, it is possible to prevent the industrial vehicle <NUM> from traveling in the normal mode M1 for a long period of time while the unseated state continues.

In a case in which the determination result in step S104 is affirmative, the process of step S105 is performed. In step S105, the controller <NUM> continues the travel in the normal mode M1. In this case, the processes of Step S21 and Step S22 are omitted. Therefore, even in a case in which the unseated state is detected while the accelerator <NUM> is being operated in the normal mode M1, the controller <NUM> maintains the operation mode M at the normal mode M1 as long as the unseated state duration T1 is shorter than or equal to the unseated state determination time Tx. The controller <NUM> performing the processes of steps S103 to S105 corresponds to a travel continuing unit of the present embodiment.

When the driver becomes unseated from the driver's seat <NUM> even if the industrial vehicle <NUM> is in a stopped state in the normal mode M1, the determination result in step S101 is affirmative, and the process of step S23 is performed. In step S23, the controller <NUM> sets the operation mode M to the interruption mode M3. In this case, the controller <NUM> changes the operation mode M from the normal mode M1 to the interruption mode M3. Therefore, if the driver becomes unseated from the driver's seat <NUM> while the industrial vehicle <NUM> is in a stopped state, the controller <NUM> omits the limitation of the driving force in the limit mode M2 and interrupts the transmission of the driving force by the driving force transmitting mechanism <NUM>.

If the driver becomes unseated from the driver's seat <NUM> while the industrial vehicle <NUM> is traveling, the determination result in step S101 is negative, and the process of step S102 is performed. In this case, if the driver is operating the accelerator <NUM>, the determination result in step S102 is affirmative, and the process of step S103 is performed. In this case, if the operation mode M is the normal mode M1, the determination result in step S103 is affirmative, and the process of step S105 is performed. In step S105, the controller <NUM> continues the traveling in the normal mode M1 even if the driver state is the unseated state.

The second embodiment has the following advantages.

(<NUM>-<NUM>) The controller <NUM> performs the process of step S101, in which it is determined whether the industrial vehicle <NUM> is in a stopped state, and the process of step S23, in which the operation mode M is set to the interruption mode M3 if the unseated state is detected while the industrial vehicle <NUM> is in a stopped state.

With this configuration, in a case in which the industrial vehicle <NUM> is in a stopped state, the operation mode M is set to the interruption mode M3 without performing the limit mode M2 even if the unseated state duration T1 is shorter than or equal to the unseated state determination time Tx. In the interruption mode M3, since the transmission of the driving force by the driving force transmitting mechanism <NUM> is interrupted, creep does not occur. Therefore, it is possible to prevent the industrial vehicle <NUM> in a stopped state from moving due to creep while the driver is unseated from the driver's seat <NUM>.

(<NUM>-<NUM>) If the unseated state is detected while the accelerator <NUM> is being operated in the normal mode M1, the controller <NUM> performs the process of step S105, in which the travel in the normal mode M1 is continued.

If the accelerator <NUM> is being operated, there is a possibility that the driver has an intention to continue driving the industrial vehicle <NUM>. Thus, even if the driver state is the unseated state, the driver can drive the industrial vehicle <NUM> in the normal mode M1 by operating the accelerator <NUM>. Therefore, it is possible to further improve the driving comfort of the industrial vehicle <NUM> by reflecting the intention of the driver to continue driving the industrial vehicle <NUM>.

The above-described embodiments may be modified as described below. The above-described embodiments and the following modifications can be combined as long as the combined modifications remain technically consistent with each other.

The travel controlling processes described in the background art and second embodiment are merely examples, and the present disclosure is not limited to these.

In the background art and in the embodiment, the process of step S41 may be omitted. In this case, for example, the controller <NUM> executes the process of step S43 regardless of whether the operation mode M is the limit mode M2 or the interruption mode M3. Even in the case of the limit mode M2, the controller <NUM> sets the operation mode M to the normal mode M1 if the cancellation condition is met.

In other words, the trigger for changing the operation mode M from the limit mode M2 to the normal mode M1 is not limited to the fact that the driver state detected by the driver detecting unit <NUM> becomes the seated state.

The driver detecting unit <NUM> may be separate from or integrated with the controller <NUM>. The driver detecting unit <NUM> may be a functioning unit that is implemented by the controller <NUM>.

In the background art and in the embodiment, the cancellation condition does not necessarily need to include a condition in which the driver state is the seated state and a condition in which the direction detecting unit <NUM> has detected a change in the operation position. For example, the cancellation condition may be met when a cancellation button provided in the industrial vehicle <NUM> is operated.

In the background art and in the embodiment, the trigger for performing the process of step S42, which sets the operation mode M to the normal mode M1 in a case in which the operation mode M is set to the limit mode M2, is not limited to the fact that the driver state becomes the seated state, but may be changed. For example, the trigger may be the same as the cancellation condition in step S43.

In the background art and in the embodiment, the normal mode M1 does not necessarily need to be defined explicitly. For example, an operation mode M other than the limit mode M2 and the interruption mode M3 may be defined as the normal mode M1.

In the background art and in the embodiment, the industrial vehicle <NUM> may include a seat belt, a buckle connected to the seat belt, and a seat belt use sensor. The seat belt, the buckle, and the seat belt use sensor are not shown in the drawings. The seat belt, the buckle, and the seat belt use sensor are attached to the driver's seat <NUM>.

The seat belt use sensor is configured to detect whether the driver is using the seat belt. For example, the seat belt use sensor includes a switch. For example, the switch of the seat belt use sensor is turned ON when the seat belt is fastened to the buckle, and is turned OFF when the seat belt is not fastened to the buckle. The specific configuration of the seat belt use sensor is arbitrary, and may include, for example, a pressure sensitive sensor, an optical sensor, or a camera.

The driver detecting unit <NUM> may detect the driver state based on a detection result of the seat belt use sensor. For example, the driver detecting unit <NUM> determines that the driver state is the seated state in a case in which the seat belt use sensor is ON, and determines that the driver state is the unseated state in a case in which the seat belt use sensor is OFF.

Further, the driver detecting unit <NUM> may detect the driver state based on the detection result of the seat switch <NUM> and the detection result of the seat belt use sensor. For example, the driver detecting unit <NUM> determines that the driver state is the seated state in a case in which the seat belt use sensor is turned ON after the seat switch <NUM> is turned ON. This configuration promotes the driving of the industrial vehicle <NUM> with the seat belt being used properly.

On the other hand, the driver detecting unit <NUM> determines that the driver state is the unseated state in a case in which the seat switch <NUM> is OFF, in a case in which the seat belt use sensor is OFF, or in a case in which the seat belt use sensor is turned ON before the seat switch <NUM> is turned ON. The case in which the seat belt use sensor is turned ON before the seat switch <NUM> is turned ON includes, for example, a case in which the seat belt is fastened to the buckle before the driver sits on the driver's seat <NUM>.

The information used by the driver detecting unit <NUM> to detect the driver state is not limited to the detection result of the seat switch <NUM>, but may be changed.

In the background art and in the embodiment, the industrial vehicle <NUM> is not limited to a forklift. For example, the industrial vehicle <NUM> may be a towing tractor.

Claim 1:
An industrial vehicle (<NUM>), comprising:
an engine (<NUM>);
a driven wheel (<NUM>, <NUM>);
a driving force transmitting mechanism (<NUM>) configured to transmit a driving force of the engine (<NUM>) to the driven wheel (<NUM>, <NUM>);
a driver's seat (<NUM>) on which a driver is seated;
a driver detecting unit (<NUM>) configured to detect a driver state of driver states including an unseated state, in which the driver is unseated from the driver's seat (<NUM>), and a seated state, in which the driver is seated on the driver's seat (<NUM>);
an accelerator (<NUM>) that instructs acceleration by the driving force in response to operation by the driver; and
a controller (<NUM>) configured to set an operation mode of operation modes based on the driver state detected by the driver detecting unit (<NUM>), wherein
the operation modes include a normal mode, a limit mode that limits the driving force, and an interruption mode that interrupts a transmission of the driving force to the driven wheel (<NUM>, <NUM>) by the driving force transmitting mechanism (<NUM>), and
the controller (<NUM>) includes:
an unseated state determining unit configured to determine, when the driver state is the unseated state, whether an unseated state duration, during which the unseated state continues, is shorter than or equal to a specified unseated state determination time;
a limit setting unit configured to set the operation mode to the limit mode; and
an interruption setting unit configured to set the operation mode to the interruption mode, wherein
under a condition that the accelerator (<NUM>) is not operated, or the accelerator (<NUM>) is being operated in the operation mode other than the normal mode,
the limit setting unit is configured to set the operation mode to the limit mode when the unseated state determining unit determines that the unseated state duration is shorter than or equal to the unseated state determination time, and
the interruption setting unit is configured to set the operation mode to the interruption mode when the unseated state determining unit determines that the unseated state duration is longer than the unseated state determination time,
the controller (<NUM>) includes a travel continuing unit that is configured to continue a travel in the normal mode if the unseated state is detected while the accelerator (<NUM>) is being operated in the normal mode.