JP2013183569A - Industrial vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control performance deterioration of a fuel cell.SOLUTION: It is determined whether a forklift has been a cargo handling state just before a vehicle stop state where a vehicle key switch is turned from on to off (steps S12, S16, and S18). Then, cell voltage of a fuel cell is retained after a vehicle stop state by making the fuel cell minutely generate electricity according to the determination result (steps S13 and S19).

Description

  The present invention relates to an industrial vehicle equipped with a fuel cell.

  When using a fuel cell that generates electricity by reacting hydrogen with oxygen in the air, a configuration that can store electricity generated by the fuel cell in a power storage device is generally employed. In such a configuration, the performance of the fuel cell deteriorates when the fuel cell is in an OCV (open circuit voltage) state. This is because the catalyst (platinum) used in the fuel cell is eluted by a high voltage. The OCV state is an electrical no-load state and is a state where the potential of the fuel cell is the highest.

  Further, the performance deterioration of the fuel cell occurs due to repeated generation and stoppage of power generation. In a region lower than the high voltage at which the catalyst (platinum) is eluted, the catalyst (platinum) is oxidized, and a protective film is formed by oxidation. This protective film suppresses the elution of the catalyst (platinum) to prevent the deterioration of the performance of the fuel cell. However, the catalyst (platinum) is reduced at a lower voltage range, and the protective film due to oxidation disappears. For this reason, repetition of power generation and power generation stop causes a deterioration in the performance of the fuel cell by accompanying a transition from the reduction region (the state without the protective film) to the OCV state.

  Patent Document 1 discloses means for suppressing the performance deterioration of the fuel cell as described above. In Patent Document 1, there is a method of continuously generating power at a slightly higher voltage than that of the power storage device and suppressing performance deterioration of the fuel cell even when there is no electrical load (in other words, when the vehicle is in a no-load state). It is disclosed.

Japanese Patent Laid-Open No. 61-248367

  By the way, once an industrial vehicle such as a forklift is started, the state is not maintained for a long time, and the vehicle key switch is repeatedly turned ON / OFF repeatedly in the situation of cargo handling work. It is. For this reason, when a fuel cell is mounted on a vehicle in such a usage situation, power generation and stoppage of the fuel cell are repeated, and therefore it is necessary to suppress deterioration in the performance of the fuel cell.

  This invention was made paying attention to the problem which exists in such a prior art, and the objective is to provide the industrial vehicle which can suppress the performance degradation of a fuel cell.

  In order to solve the above-described problems, the invention according to claim 1 is an industrial vehicle that uses electric power generated by a fuel cell as a driving force of a vehicle, immediately before a vehicle stop state in which a vehicle key switch is turned from ON to OFF. A loading / unloading determination unit that determines whether or not the vehicle is in a loading / unloading state, and a control unit that executes voltage holding control for holding a cell voltage of the fuel cell when the determination result of the loading / unloading determination unit is affirmative; The main point is that

  Industrial vehicles are very unlikely to be left for a long time (for example, until the start time of the next day) in the cargo handling state, rather they can be started again in a short time after the vehicle is stopped. High nature. That is, in an industrial vehicle, there is a high possibility that the vehicle is in a stopped state in order to temporarily interrupt the cargo handling work for some reason, and then the cargo handling work is resumed in a short time. For this reason, in this invention, when it is a cargo handling state just before a vehicle stop state, the voltage holding control which hold | maintains the cell voltage of a fuel cell is performed. Thereby, since repetition of power generation and stop of power generation of the fuel cell is suppressed, the performance deterioration of the fuel cell can be suppressed as a result.

  According to a second aspect of the present invention, in the industrial vehicle according to the first aspect, the cargo handling determination unit executes a load determination process for determining whether or not a load is loaded, and loads the load. The gist is to determine that it is in the cargo handling state. According to this, since it is determined whether or not it is in a cargo handling state based on whether or not a load is loaded, it is possible to accurately determine whether or not voltage holding control is executed with a simple control configuration.

  The invention according to claim 3 is the industrial vehicle according to claim 2, wherein the control unit executes the voltage holding control for a predetermined time when the load is loaded. To do. According to this, the industrial vehicle is extremely unlikely to be left in a loaded state. Therefore, in such a case, the performance of the fuel cell can be reliably suppressed by executing the voltage holding control. .

  According to a fourth aspect of the present invention, in the industrial vehicle according to the third aspect, the vehicle is a forklift, and when the cargo handling determination unit determines that the load is not loaded, the vehicle A reverse determination unit that determines whether or not the vehicle travels backward from a state in which the vehicle is not loaded, and the control unit controls the voltage holding control for the predetermined time when the determination result of the reverse determination unit is negative. The main point is to execute.

  In a forklift, when unloading a load, the fork is pulled out from the pallet after landing the loaded pallet on the loading area. Since the fork is disposed in front of the forklift, the fork is pulled out of the pallet by moving the vehicle backward. For this reason, when the forklift is not traveling backward with no load loaded, it is highly likely that the pallet has landed at the loading area, but the fork has not been removed from the pallet. In other words, in this case, for example, there is a possibility that the once lifted load is picked up again and the cargo handling operation is resumed. Therefore, by performing the voltage holding control in such a case, the performance deterioration of the fuel cell can be reliably suppressed.

  According to a fifth aspect of the present invention, in the industrial vehicle according to the fourth aspect, the control unit holds the voltage for a time shorter than the predetermined time when the determination result of the reverse determination unit is affirmative. The gist is to execute the control.

  According to this, assuming that the possibility of resuming the cargo handling operation in a short time is low, the voltage holding control is executed for a shorter time than when the possibility is high. For this reason, the voltage holding control is executed in consideration of the vehicle starting in a short time, but the voltage holding control is executed for a short time in consideration of the high possibility that the vehicle will not start. The accompanying power consumption can be suppressed.

  According to a sixth aspect of the present invention, in the industrial vehicle according to any one of the first to fifth aspects, the vehicle is a forklift, and the cargo handling determination unit determines a lift height of the fork in advance. At least one of a lift determination process for determining whether or not the set lift is exceeded and an angle determination process for determining whether or not the tilt angle of the mast to which the fork is mounted exceeds a predetermined set angle And the control unit determines that it is in the cargo handling state when the set lift is exceeded and when the set angle is exceeded, and the control unit exceeds the set lift. The gist of the present invention is to execute the voltage holding control for the predetermined time in each of the case where the set angle and the set angle are exceeded.

  According to this, since it is determined whether or not it is in a cargo handling state based on the lift height of the fork or the tilt angle of the mast, it can be accurately determined whether or not the voltage holding control is executed with a simple control configuration. . Further, in the invention according to claim 6 including the configuration of the invention according to claims 2 to 5, in addition to the determination of whether or not the load is loaded, the lift height of the fork and the tilt angle of the mast Since the determination is also performed, it is possible to further increase the accuracy of the determination as to whether or not the cargo is being handled. Therefore, the voltage holding control can more reliably suppress the performance deterioration of the fuel cell.

  According to the present invention, it is possible to suppress performance deterioration of the fuel cell.

The front view which shows a forklift. Electrical block diagram. Schematic which shows a fuel cell. The graph explaining the voltage change of the cell which comprises a fuel cell. The flowchart of the execution determination process which determines whether voltage holding control is performed.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, a mast 13 is erected on the front portion of the body frame 12 of the forklift 11. The mast 13 includes a pair of left and right outer masts 131 supported to be tiltable back and forth with respect to the vehicle body frame 12 and an inner mast 132 that slides up and down. A hydraulic lift cylinder 14 is disposed at the rear of each outer mast 131. The tip of the piston rod 141 of the lift cylinder 14 is connected to the upper part of the inner mast 132. A chain 17 is wound around the chain wheel 15 supported on the upper part of the inner mast 132. One end of the chain 17 is fixed to the body of the lift cylinder 14 or the upper part of the outer mast 131, and the other end of the chain 17 is connected to the lift bracket 16. The fork 18 moves up and down together with the lift bracket 16 suspended from the chain 17 by expansion and contraction of the lift cylinder 14.

  The mast 13 is connected and supported so as to be tiltable with respect to the vehicle body frame 12 via a pair of hydraulic tilt cylinders 19. The tilt cylinder 19 is pivotally connected to the vehicle body frame 12 at the base end side, and is pivotally connected to the outer mast 131 at the tip of the piston rod 191. The mast 13 tilts back and forth as the tilt cylinder 19 is driven to expand and contract. The mast 13 can be tilted between a predetermined last tilt position and a most forward tilt position. When the position of the mast 13 shown by the solid line in FIG. 1 is a vertical position, the tilting operation in the direction approaching the cab 20 is the backward tilting operation, and the tilting operation in the direction away from the cab 20 is the forward tilting operation ( State of a two-dot chain line). In the configuration of the forklift 11 according to the present embodiment, the mast 13 tilts forward when the tilt cylinder 19 operates in the extending direction, while the mast 13 tilts backward when the tilt cylinder 19 operates in the contracting direction. The lift cylinder 14 and the tilt cylinder 19 obtain driving force from the cargo handling motor 30.

  A driver's seat 201 is provided in the driver's cab 20, and a steering wheel 21, a lift lever 22, and a tilt lever 23 are provided in front of the driver's seat 201. A forward / reverse lever (direction lever) DL is provided in front of the driver seat 201. The forward / reverse lever DL is illustrated in FIG. An accelerator pedal 28 is provided in front of and below the driver seat 201.

  The steering wheel 21 is for changing the steering angle of the steering wheel 24 (rear wheel). The lift lever 22 is operated when raising and lowering the fork 18. The lift lever 22 selectively instructs “up” and “down” depending on the operation direction. The tilt lever 23 is operated when the mast 13 is tilted. The tilt lever 23 selectively instructs “forward tilt” and “backward tilt” depending on the operation direction. The forward / reverse lever DL is operated to instruct the traveling direction (traveling direction) of the vehicle. The forward / reverse lever DL selectively instructs “forward” and “reverse” depending on the operation direction. The accelerator pedal 28 causes the forklift 11 to travel.

  When the lift lever 22 is operated, an operation signal corresponding to this operation is sent to the vehicle controller 27, and the vehicle controller 27 controls the raising and lowering of the fork 18 based on the input of the operation signal. When the tilt lever 23 is operated, an operation signal corresponding to this operation is sent to the vehicle controller 27, and the vehicle controller 27 controls the tilting of the mast 13 based on the input of the operation signal.

  The drive wheel 25 (front wheel) is rotationally driven by the traveling motor 26. The traveling motor 26 is controlled by the vehicle controller 27. When the forward / reverse lever DL is operated, an operation signal corresponding to this operation is sent to the vehicle controller 27. When the accelerator pedal 28 is depressed, an operation signal corresponding to this operation is sent to the vehicle controller 27. The vehicle controller 27 controls the rotation direction and the rotation speed of the traveling motor 26 based on the input of the operation signal from the forward / reverse lever DL and the operation signal from the accelerator pedal 28. As a result, the forklift 11 travels at a speed corresponding to the depression operation amount of the accelerator pedal 28 in the traveling direction instructed by the forward / reverse lever DL.

  As shown in FIG. 2, the vehicle controller 27 is electrically connected to a load sensor SE1, a lift height sensor SE2, and a tilt angle sensor SE3. The load sensor SE1 is disposed in the hydraulic circuit near the lower portion of the lift cylinder 14. The load sensor SE1 detects the loaded load (load load) of the fork 18. The load sensor SE <b> 1 detects the hydraulic pressure inside the lift cylinder 14 and outputs a detection signal corresponding to the loaded load of the fork 18 to the vehicle controller 27. The load sensor SE1 is composed of, for example, a pressure sensor. The vehicle controller 27 recognizes the loaded load of the fork 18 by inputting a detection signal from the load sensor SE1.

  The lift sensor SE2 is disposed on the mast 13. The lift sensor SE2 detects the lift position (height position) of the fork 18, and outputs a detection signal corresponding to the detected lift position of the fork 18 to the vehicle controller 27. The lift sensor SE2 is composed of, for example, a reel sensor. The vehicle controller 27 recognizes the lift position of the fork 18 by inputting the detection signal from the lift sensor SE2. The tilt angle sensor SE3 is disposed in the vicinity of the tilt cylinder 19. The tilt angle sensor SE3 detects a tilt angle. The tilt angle sensor SE3 detects an inclination angle based on an angle (horizontal angle) when the fork 18 is in a horizontal posture, and outputs a detection signal corresponding to the inclination angle to the vehicle controller 27. The tilt angle sensor SE3 is composed of, for example, a potentiometer. The vehicle controller 27 recognizes the tilt angle of the fork 18 by inputting a detection signal from the tilt angle sensor SE3.

  A storage room 31 is provided below the floor of the cab 20. A fuel cell system FU is mounted in the storage chamber 31. The storage chamber 31 is provided with a connector K (shown in FIG. 2).

  As shown in FIG. 2, the connector K electrically connects the wiring 32 on the fuel cell system FU side and the wiring 33 constituting the power circuit on the forklift 11 side. A traveling inverter 34, a cargo handling inverter 35, and a voltmeter 36 are connected to the wiring 33 on the vehicle side. The traveling inverter 34 converts the direct current supplied from the fuel cell system FU via the connector K into alternating current. The traveling motor 26 and the cargo handling motor 30 are driven by the alternating current converted by the traveling inverter 34.

  The voltmeter 36, the traveling inverter 34 and the cargo handling inverter 35 are electrically connected to the vehicle controller 27. The vehicle controller 27 controls the rotation speed of the traveling motor 26 by controlling the operation of the traveling inverter 34 and adjusting the AC voltage supplied to the traveling motor 26. Similarly, the vehicle controller 27 controls the rotation speed of the cargo handling motor 30 by controlling the operation of the cargo handling inverter 35 and adjusting the AC voltage supplied to the cargo handling motor 30.

  A vehicle key switch 29 is electrically connected to the vehicle controller 27. The vehicle key switch 29 is configured to be operable between a stop position where the power of the forklift 11 is turned off and a start position where the power is turned on. When the vehicle key switch 29 is operated from the stop position (OFF) to the start position (ON), a vehicle start signal indicating that the operation position of the vehicle key switch 29 is at the start position is output to the vehicle controller 27. . When the vehicle key switch 29 is operated to the starting position, the vehicle controller 27 starts control of the travel inverter 34 and the cargo handling inverter 35 and starts control of power supply to the travel motor 26 and the cargo handling motor 30. To do. When the vehicle key switch 29 is operated from the start position (ON) to the stop position (OFF), the vehicle key switch 29 stops outputting the vehicle start signal. For this reason, the vehicle controller 27 recognizes whether the power source of the forklift 11 is turned on or off by inputting a vehicle start signal from the vehicle key switch 29. The forklift 11 enters a vehicle stop state when the vehicle key switch 29 is turned off.

Next, the fuel cell system FU mounted in the storage chamber 31 will be described.
As shown in FIG. 2, the fuel cell system FU includes a fuel cell unit 37. The fuel cell unit 37 includes a fuel cell FC, a hydrogen tank 38 that stores hydrogen and supplies hydrogen to the fuel cell FC, and a compressor 39 that supplies air to the fuel cell FC.

  The fuel cell FC of the present embodiment is a solid polymer fuel cell and incorporates a plurality of cells composed of a fuel electrode and an air electrode partitioned by a polymer electrolyte membrane. In the fuel cell FC, power generation is performed by an electromotive reaction through an electrolyte membrane between hydrogen supplied to the fuel electrode and oxygen in the air supplied to the air electrode.

  As shown in FIG. 3, each cell 50 constituting the fuel cell FC is sandwiched between a pair of ribbed separators 51, a pair of electrodes 52, 53 sandwiched between both separators 51, and both electrodes 52, 53. And an electrolyte membrane 54. The pair of electrodes 52 and 53 includes an anode electrode 52 having an anode catalyst layer formed on a porous support layer, and a cathode electrode 53 having a cathode catalyst layer formed on a porous support layer. The fuel (hydrogen) flows in one direction through the groove on the side surface of the anode of the separator 51, and the air flows in the direction orthogonal to the flow path of the fuel through the groove on the side surface of the cathode electrode of the separator 51. The anode side becomes the fuel electrode, and the cathode side becomes the air electrode. Further, platinum or an alloy containing platinum is used for the catalyst layers of the electrodes 52 and 53.

  The fuel cell unit 37 is electrically connected to the wiring 32 on the fuel cell system FU side. An electric double layer capacitor 40 (hereinafter referred to as a capacitor 40) is electrically connected to the wiring 32 via a DC / DC converter 41 so as to be in parallel with the fuel cell FC. The capacitor 40 as the power storage device is charged by receiving power supply from the fuel cell unit 37 via the DC / DC converter 41. The DC / DC converter 41 converts electric power of a predetermined voltage (for example, 100 volts) generated by the fuel cell unit 37 into a predetermined voltage (for example, 48 volts).

  A voltmeter 42 (unit voltmeter) is connected to the wiring 32 so as to be parallel to the capacitor 40. The voltmeter 42 detects the voltage of the capacitor 40 (hereinafter referred to as “capacitor voltage”).

  The DC / DC converter 41, the voltmeter 42, and the fuel cell unit 37 are electrically connected to the fuel cell system controller 44. The fuel cell system controller 44 controls the start and stop of power generation by the fuel cell unit 37 and the power generation amount. The fuel cell system controller 44 controls the DC / DC converter 41 so as to convert the voltage of the electric power generated by the fuel cell unit 37 into a predetermined voltage suitable for charging the capacitor 40.

  The fuel cell system controller 44 is electrically connected to the vehicle controller 27. When the vehicle key switch 29 is turned ON, the vehicle controller 27 outputs a unit activation signal to the fuel cell system controller 44. The fuel cell system controller 44 starts control of power generation in the fuel cell unit 37 based on the input of the unit activation signal.

  An emergency stop button BT is provided in the cab 20 of the forklift 11 of the present embodiment. The emergency stop button BT is shown in FIG. The emergency stop button BT is electrically connected to the vehicle controller 27. When the emergency stop button BT is pressed, the vehicle controller 27 inputs a pressing operation signal. As shown in FIG. 2, the hydrogen tank 38 and the fuel cell FC are connected by piping, and the piping 60 is provided with an electric valve 61 that opens and closes the piping 60. When the vehicle controller 27 inputs a pressing operation signal from the emergency stop button BT, the vehicle controller 27 operates the valve 61 in a closed state to close the pipe 60 between the hydrogen tank 38 and the fuel cell FC. That is, the vehicle controller 27 closes the valve 61 so that hydrogen cannot be supplied to the fuel cell FC.

The cell voltage of the fuel cell FC changes as shown in FIG.
Note that the voltage [V1 (approximately 1V)] in FIG. 4 indicates the maximum value of the voltage obtained by the set of cells 50 constituting the fuel cell FC, and the voltages [V2 (approximately 0.75V), [V3 (approximately) 0.65V)] is a voltage lower than the voltage [V1], and these voltages [V1] to [V3] cause a chemical change in the catalyst (platinum) constituting the cell 50, It is also a voltage that affects the performance degradation of the fuel cell FC.

  The cell voltage of the fuel cell FC is set to [0 V] when the vehicle key switch 29 is in the OFF state. Then, when the vehicle key switch 29 is operated from OFF to ON, the fuel cell system controller 44 inputs hydrogen and air into the fuel cell FC. Thereby, the fuel cell FC starts power generation. Then, the cell voltage of the fuel cell FC rises with time as shown by the solid line in the figure. Then, the fuel cell system controller 44 generates power from the fuel cell FC so that the cell voltage is maintained within the voltage range [V1] to [V2] while the vehicle key switch 29 is kept on. Control the amount.

  On the other hand, the cell voltage of the fuel cell FC is [0V] as shown by a two-dot chain line in the figure when the vehicle key switch 29 is operated from ON to OFF to stop the vehicle power generation. Descent toward. For this reason, when the vehicle key switch 29 is repeatedly turned ON / OFF, and when power generation and power generation stop are repeatedly performed, the cell voltage has values [V2] and [V3] that can cause a chemical change in the catalyst. It can be taken repeatedly. As a result, the performance of the fuel cell FC is deteriorated.

  Therefore, in the forklift 11 according to the present embodiment, when the vehicle key switch 29 is operated to OFF, voltage holding control is performed so that the cell voltage does not vary greatly in accordance with the cargo handling state at that time. Specifically, after the vehicle key switch 29 is turned off, it is estimated whether or not the cargo handling operation is likely to be resumed in a short time (the vehicle key switch 29 is turned on). Based on this, power generation is continued to maintain the cell voltage.

Hereinafter, specific control contents of the voltage holding control will be described with reference to FIG.
The vehicle controller 27 determines whether or not the cargo handling operation is likely to be resumed. The vehicle start signal of the vehicle key switch 29, the operation signals of the forward / reverse lever DL and the accelerator pedal 28, and the load sensor SE1. The detection signals of the lift height sensor SE2 and the tilt angle sensor SE3 are input. The vehicle controller 27 stores and holds these input signals. Then, the vehicle controller 27 performs the execution determination process shown in FIG. 5 for executing the voltage holding control based on each signal stored and held at every predetermined control cycle (for example, every several milliseconds). Run.

  In the execution determination process, the vehicle controller 27 determines whether or not the vehicle key switch 29 has been turned OFF based on the vehicle start signal from the vehicle key switch 29 (step S10). When this determination result is negative, that is, when the vehicle key switch 29 is ON, the vehicle controller 27 ends the execution determination process, and performs the determination from step S10 of the execution determination process again with the arrival of the next control cycle. .

  On the other hand, when the determination result of step S10 is affirmative, the vehicle controller 27 is operated to turn off the vehicle key switch 29, so that the vehicle is stopped. Therefore, whether or not the forklift 11 is in a cargo handling state immediately before the vehicle is stopped. This is determined by the processing from step S11. More specifically, the vehicle controller 27 executes a load determination process for determining whether or not a load is loaded based on the load measurement value KK that is the detection result of the load sensor SE1 immediately before the vehicle is stopped (step). S11). In this loading determination process, the vehicle controller 27 compares the load measurement value KK with a predetermined load determination value HK. The load determination value HK is set to a value detected by the load sensor SE1 when no load is loaded.

  And the vehicle controller 27 determines whether the determination result of the loading determination process of step S11 is a cargo handling state (step S12). If the load measurement value KK is greater than the load determination value HK, the vehicle controller 27 loads the load and is in the cargo handling state, so that the determination in step S12 is affirmative. On the other hand, when the load measurement value KK is smaller than the load determination value HK, that is, when the load measurement value KK is a value indicating that no load is loaded, the vehicle controller 27 makes a negative determination in step S12.

  The vehicle controller 27 that affirmed the determination in step S12 proceeds to step S13 and outputs a control signal for causing the fuel cell system controller 44 to execute the voltage holding control for the time X. In the voltage holding control of the present embodiment, the power generation amount of the fuel cell FC is set as a minute power generation amount, and the cell voltage is maintained in the voltage [V1] to [V2] region. The power generation amount of the fuel cell FC in the voltage holding control is set to be smaller than when the vehicle key switch 29 is ON. Then, the fuel cell system controller 44 executes voltage holding control by micro power generation for a time X. As a result, as shown in FIG. 4, the cell voltage of the fuel cell FC drops toward [0V] as power generation continues even when the vehicle key switch 29 is turned OFF at time T1. Without maintaining a predetermined value. Therefore, if the vehicle key switch 29 is turned on again before the time X has elapsed, the cell voltage of the fuel cell FC does not rise from [0V], and the voltage [V2] and [V3] can be suppressed. Is done.

  Then, when the time X has elapsed, the fuel cell system controller 44 ends the voltage holding control. As a result, the cell voltage of the fuel cell FC drops to [0 V] after a lapse of time X after the vehicle key switch 29 is turned OFF. Note that the reason for setting the time X is that the vehicle key switch 29 is always turned on, that is, the cargo handling operation is resumed in a short time even when it is determined that the cargo handling state is established. Not exclusively. And in order to generate electric power with the fuel cell FC, the fuel cell unit 37 must be operated, so the electric power stored in the capacitor 40 is used. For this reason, voltage holding control is continued without setting a period even in a situation where it is estimated that the vehicle key switch 29 is likely to be turned on in a short time after being determined to be in the cargo handling state. This leads to wasteful consumption of the electric power stored in the capacitor 40. Therefore, in the present embodiment, the voltage holding control is configured to be executed during the time X. The time X is, for example, 5 to 10 minutes. After the elapse of time X, the vehicle controller 27 and the fuel cell system controller 44 enter a standby state. During the time X, the fuel cell system controller 44 controls the power generation. For example, even if the accelerator pedal 28, the lift lever 22 or the like is operated, the vehicle controller 27 does not perform control related to traveling or cargo handling. . These controls relating to traveling and cargo handling are performed when the vehicle key switch 29 is ON.

  Returning to the description of FIG. 5, when the vehicle controller 27 makes a negative determination in step S <b> 12, the vehicle controller 27 proceeds to step S <b> 14 and determines whether or not the forklift 11 has moved backward. In the forklift 11, as shown in FIG. 1, the fork 18 is disposed in front of the vehicle, and when the load is transported, the pallet P loaded with the load is scooped up by the fork 18. When the forklift 11 unloads the load, the fork 18 is pulled out from the pallet P after the loaded pallet P is landed on the loading place. At this time, in the forklift 11, the fork 18 is removed from the pallet P by moving backward. In the forklift 11 that performs such a cargo handling operation, no load is applied to the fork 18 at the stage when the loaded pallet P is landed on the loading area. That is, the detection result of the load sensor SE1 can take a value indicating that no load is loaded. However, even if the detection result of the load sensor SE1 is a value indicating that no load is loaded, when the fork 18 is not removed from the pallet P, the pallet P once landed is picked up again and conveyed. The potential remains. Therefore, in the present embodiment, in the processing of step S12 and step S14, the cargo handling operation is resumed by determining whether or not the vehicle has moved backward from a state in which no load is loaded (whether or not the fork 18 has been removed). It is determined whether the possibility is high.

  When the vehicle controller 27 makes a negative determination in step S14, the vehicle controller 27 determines that the fork 18 has not been pulled out of the pallet P and is in a cargo handling state, and proceeds to step S13. Thereby, the voltage holding control is executed during the time X.

  On the other hand, when the determination result in step S14 is affirmative, the vehicle controller 27 determines the lift of the fork 18 based on the lift height measurement value KH that is the detection result of the lift sensor SE2 immediately before the vehicle is stopped. A high determination process is executed (step S15). In this lift height determination process, the vehicle controller 27 compares the lift height measurement value KH with a predetermined lift height determination value HH. The lift height determination value HH is set to a lift height in which the fork 18 is placed when not in the cargo handling state. For example, the lifting height determination value HH is set to be about 100 mm from the traveling road surface of the forklift 11.

  And the vehicle controller 27 determines whether the determination result of the lifting height determination process of step S15 is a cargo handling state (step S16). If the lift height measurement value KH is greater than the lift height determination value HH, the vehicle controller 27 makes a positive determination in step S16 because it is in the cargo handling state, and proceeds to step S13. Thereby, the voltage holding control is executed during the time X. On the other hand, if the lift height measurement value KH is smaller than the lift height determination value HH, the vehicle controller 27 makes a negative determination in step S16 and proceeds to step S17.

  The vehicle controller 27 that has proceeded to step S17 executes an angle determination process for determining the tilt angle of the fork 18 based on the tilt angle measurement value KT that is the detection result of the tilt angle sensor SE3 immediately before the vehicle stop state (step S17). S17). In this angle determination process, the vehicle controller 27 compares the tilt angle measurement value KT with a predetermined tilt angle determination value HT. The tilt angle determination value HT is set to an angle at which the mast is arranged when not in the cargo handling state. For example, the tilt angle determination value HT is set to a value indicated when the mast 13 is in the vertical position.

  And the vehicle controller 27 determines whether the determination result of the angle determination process of step S18 is a cargo handling state (step S18). If the tilt angle measurement value KT is greater than the tilt angle determination value HT, the vehicle controller 27 is in the cargo handling state and makes an affirmative determination in step S18 and proceeds to step S13. Thereby, the voltage holding control is executed during the time X. On the other hand, if the tilt angle measurement value KT is smaller than the tilt angle determination value HT, that is, if the tilt angle measurement value KT is a value indicating the vertical position, the vehicle controller 27 makes a negative determination in step S18 and proceeds to step S19. To do.

  The vehicle controller 27 that has proceeded to step S19 outputs a control signal for causing the fuel cell system controller 44 to execute voltage holding control during the time Y, although the forklift 11 is not in the cargo handling state. Time Y is set to be shorter than time X. In the present embodiment, even when it is determined that the vehicle is not in the cargo handling state, the voltage holding control is executed in consideration of the possibility that the vehicle key switch 29 is operated to be turned on in a short time. Let However, since the possibility is low compared with the case where it is a cargo handling state, the power consumption accompanying the said control is suppressed by shortening the time which performs voltage holding control. The time Y is, for example, a time of 1 to 2 minutes. During the time Y, the fuel cell system controller 44 controls power generation, and the vehicle controller 27 does not perform control related to traveling or cargo handling.

  In the present embodiment, as described above, the vehicle controller 27 determines whether or not the vehicle is in a cargo handling state. For this reason, in this embodiment, the vehicle controller 27 functions as a cargo handling determination unit. In the present embodiment, the vehicle controller 27 and the fuel cell system controller 44 execute voltage holding control based on the determination result of whether or not the cargo handling state is set. For this reason, in this embodiment, the vehicle controller 27 and the fuel cell system controller 44 function as a control unit. Moreover, in this embodiment, it is determined by the vehicle controller 27 whether the reverse drive was performed. For this reason, in this embodiment, the vehicle controller 27 functions as a reverse determination unit.

Hereinafter, the operation of the forklift 11 of this embodiment will be described.
When the vehicle key switch 29 is ON, the forklift 11 operates the traveling motor 26 and the cargo handling motor 30 using the power generated by the fuel cell FC as a driving force. As a result, the forklift 11 travels at a desired speed by the travel motor 26. Further, the fork 18 and the mast 13 are moved up and down and tilted by controlling the supply and discharge of hydraulic oil to and from the lift cylinder 14 and the tilt cylinder 19 by the cargo handling motor 30.

  And the forklift 11 will be in a vehicle stop state, if the vehicle key switch 29 is operated from ON to OFF. At this time, in the present embodiment, it is determined whether or not the forklift 11 is in the cargo handling state immediately before the vehicle is stopped. Then, based on this determination result, voltage holding control for holding the cell voltage by causing the fuel cell FC to generate a small amount of power for a predetermined time X or time Y is executed. That is, the forklift 11 maintains the cell voltage even when the vehicle is stopped. For this reason, even when the vehicle key switch 29 is operated to be turned on for a short time after the vehicle is stopped, the cell voltage does not fluctuate greatly. That is, in the forklift 11 in which the vehicle key switch 29 is frequently turned ON / OFF, the fuel cell FC is prevented from frequently repeating power generation and power generation stop. As a result, the performance deterioration of the fuel cell FC is suppressed.

Therefore, according to the present embodiment, the following effects can be obtained.
(1) The forklift 11 is extremely unlikely to be left for a long time (for example, until the start time of the next day) while in the cargo handling state. There is a high possibility of doing. That is, in the forklift 11, there is a high possibility that the vehicle is stopped in order to temporarily stop the cargo handling work for some reason, and then the cargo handling work is resumed in a short time. For this reason, when the vehicle is in the cargo handling state immediately before the vehicle is stopped, the voltage holding control for holding the cell voltage of the fuel cell FC can be executed to suppress the power generation and the power generation stop of the fuel cell FC. Therefore, the performance deterioration of the fuel cell FC can be suppressed.

  (2) When the vehicle key switch 29 is operated to be turned off in the forklift 11 in a state where a load is loaded, it is more likely that the cargo handling operation is interrupted than the purpose of ending the cargo handling operation. For this reason, it is possible to accurately determine whether or not voltage holding control is to be executed with a simple control configuration by performing a loading determination process (step S11 in FIG. 5) in order to determine whether or not the cargo is being handled. Can do.

  (3) Further, when no load is loaded, it is also determined whether or not the fork 18 has been removed from the pallet P by performing reverse determination (step S14 in FIG. 5). When the vehicle is not traveling in reverse with no load loaded, performance degradation of the fuel cell can be reliably suppressed by executing voltage holding control.

  (4) Further, in the forklift 11, it is difficult to think of ending the cargo handling operation with the fork 18 arranged at a high position or with the mast 13 tilted forward or backward. Therefore, voltage holding control is performed with a simple control configuration by performing a lifting height determination process (step S15 in FIG. 5) and an angle determination process (step S17 in FIG. 5) in order to determine whether or not the cargo is being handled. It is possible to accurately determine whether or not to execute.

  (5) The execution determination process shown in FIG. 5 includes a load determination process, a lifting height determination process, and an angle determination process, and it is determined whether or not the voltage holding control is to be executed based on these determination results. The accuracy of the determination of whether or not it is in a state can be further increased. Therefore, the voltage holding control can more reliably suppress the performance deterioration of the fuel cell.

  (6) The voltage holding control is executed at different times according to the determination results of the loading determination process, the lift determination process, and the angle determination process. That is, when it is determined in the above determination that the cargo is being handled, the voltage holding control is executed for the time X. On the other hand, when it is determined in the above determination that the vehicle is not in the cargo handling state, the voltage holding control is executed for a time Y shorter than the time X. In the cargo handling state, there is a high possibility that the vehicle key switch 29 will be turned on again. Therefore, by performing the voltage holding control for a long time, it is possible to suppress the performance deterioration of the fuel cell. On the other hand, when the vehicle is not in the cargo handling state, the voltage holding control is executed in consideration of the possibility that the vehicle key switch 29 is turned on again in a short time, but it is highly likely that the vehicle key switch 29 is not turned on. In consideration of this, the voltage holding control is executed for a short time. Therefore, power consumption associated with voltage holding control can be suppressed. That is, by suppressing the power consumption, it is possible to suppress the influence on the running performance (such as fuel efficiency) of the forklift 11.

In addition, you may change the said embodiment as follows.
When determining whether or not the cargo handling state, the state of various attachments that cause the fork 18 to move left and right, tilt, or rotate may be considered. That is, when the state of the attachment immediately before the vehicle stop state is not suitable for the state in which the cargo handling operation is terminated, the voltage holding control may be executed.

  In the determination of whether or not the cargo is being handled, if the determination result is negative, the voltage holding control may not be executed. Specifically, if a negative determination is made in step S18 in FIG. 5, step S19 is not executed.

  ○ The industrial vehicle may be embodied in another industrial vehicle equipped with a fuel cell. For example, it may be embodied in a tow vehicle. When embodied in a towing vehicle, the determination as to whether or not the cargo is being handled is a determination as to whether or not the load is being pulled. Specifically, the process of step S10 in FIG. 5 is executed, the step of “determining whether or not towing” is subsequently executed instead of the process of step S11, and then the process of step S12 is executed. If the determination in step S12 is affirmative, the process proceeds to step S13. If a negative determination is made in step S12, the process proceeds to step S19 or voltage holding control is not executed.

  The determination as to whether or not the cargo is being handled may be configured by a loading determination process as to whether or not a load is being loaded. Specifically, the processes of steps S10, S11, and S12 of FIG. 5 are executed, and if step 12 is positively determined, the process proceeds to step S13, and if step S12 is negatively determined, the process proceeds to step S14. . If a negative determination is made in step S14, the process proceeds to step S13. If a positive determination is made in step S14, the process proceeds to step S19, or voltage holding control is not executed.

  O Moreover, you may comprise the determination whether it is a cargo handling state by a lift height determination process or an angle determination process. Specifically, in the case of configuring by the lift height determination process, if an affirmative determination is made in step S10 of FIG. 5, the process proceeds to step S15, and if an affirmative determination is made in step S16, the process proceeds to step S13. On the other hand, if a negative determination is made in step S16, the process proceeds to step S19 or the voltage holding control is not executed. When the angle determination process is used, the process proceeds to step S17 when the affirmative determination is made in step S10 of FIG. 5, and the process proceeds to step S13 when the affirmative determination is made in step S18. On the other hand, when a negative determination is made in step S18, the process proceeds to step S19 or voltage holding control is not executed.

  In the embodiment, the three processes of the load determination process, the lift determination process, and the angle determination process are combined, but the combination of the load determination process and the lift determination process, the combination of the load determination process and the angle determination process, or the lift determination process. You may determine whether it is a cargo handling state by the combination of a high determination process and an angle determination process.

  The lift sensor SE2 may be configured with a limit switch or the like. In this case, a limit switch is disposed at a lift position corresponding to the lift determination value HH, and the lift is detected and determined by turning the switch ON / OFF.

In the reverse determination of step S14, in order to determine whether or not the fork 18 has been removed from the pallet P, the reverse travel distance may be added to the determination element.
○ The voltage holding control may be performed in place of the micro power generation control. For example, a voltage may be applied to the cell 50 by supplying electric power stored in the capacitor 40 to the fuel cell FC, and the cell voltage may be held. In this case, the fuel cell FC is in a power generation stop state. As another method, the cell voltage may be measured or estimated, and when the voltage value reaches a predetermined value, the fuel cell FC may generate power. In this case, unlike the micro power generation described in the embodiment, the power generation of the fuel cell FC is intermittently performed.

  In the micro power generation control of the embodiment, control is performed so as to maintain the voltage [V1] to [V2] region, but the cell voltage at the time of the control is detected, and control is performed according to the detection result. You can go. For example, when the detected cell voltage exists in the voltage [V2] to [V3] region, even if the minute power generation control is performed so that the cell voltage is maintained in the voltage [V2] to [V3] region. good.

  The load determination value HK, the lift height determination value HH, and the tilt angle determination value HT may be set as fixed values in the vehicle controller 27, or may be set as variable values that can be arbitrarily changed in the vehicle controller 27. Also good.

  The emergency stop button BT may be electrically connected to the fuel cell system controller 44. When the emergency stop button BT is pressed, the fuel cell system controller 44 closes the valve 61.

  The execution determination process in FIG. 5 may be performed by the fuel cell system controller 44. In this case, the vehicle controller 27 may output the detection result of the load sensor SE1 or the like to the fuel cell system controller 44, or the detection result may be directly output to the fuel cell system controller 44. When the execution determination process is performed by the fuel cell system controller 44, the fuel cell system controller 44 functions as a cargo handling determination unit and a control unit.

  DESCRIPTION OF SYMBOLS 11 ... Forklift, 13 ... Mast, 18 ... Fork, 27 ... Vehicle controller, 29 ... Vehicle key switch, 44 ... Fuel cell system controller, 50 ... Cell, FC ... Fuel cell, X, Y ... Time.

Claims (6)

In industrial vehicles that use the power generated by the fuel cell as the driving force of the vehicle,
A cargo handling determination unit that determines whether or not the vehicle is in a cargo handling state immediately before a vehicle stop state in which the vehicle key switch is turned from ON to OFF,
An industrial vehicle, comprising: a control unit that executes voltage holding control for holding the cell voltage of the fuel cell when the determination result of the cargo handling determination unit is affirmative.   The load handling determination unit executes a load determination process for determining whether or not a load is loaded, and determines that the load is being handled when the load is loaded. The described industrial vehicle.   The industrial vehicle according to claim 2, wherein the control unit executes the voltage holding control for a predetermined time when the load is loaded. The vehicle is a forklift;
A reverse determination unit for determining whether or not the vehicle has traveled backward from a state in which the load is not loaded when the cargo handling determination unit determines that the load is not loaded;
The industrial vehicle according to claim 3, wherein the control unit executes the voltage holding control for the predetermined time when a determination result of the reverse determination unit is negative.   The industrial vehicle according to claim 4, wherein the control unit executes the voltage holding control for a time shorter than the predetermined time when the determination result of the reverse determination unit is affirmative. The vehicle is a forklift;
The loading / unloading determination unit is configured to determine whether or not a fork lift exceeds a predetermined set height, and a tilt angle of a mast to which the fork is mounted exceeds a predetermined set angle. And at least one of angle determination processing for determining whether or not the vehicle is in the cargo handling state when the set lift is exceeded and when the set angle is exceeded. ,
The control unit executes the voltage holding control for a predetermined time in each of a case where the set lift is exceeded and a case where the set angle is exceeded. The industrial vehicle according to any one of 5.