Work machine

Abstract

To achieve a work machine having a fuel cell system capable of executing a fuel cell control adequate for the work machine.SOLUTION: A vehicle body controller 45 controls power generation by a fuel cell 110 so that a power storage amount of a power storage device 135 is maintained within a prescribed power storage range during a non-operation time of a work machine that is not operated by an operator, and allows the power storage range of the power storage device 135 to be changed when controlling the fuel cell 110 according to rotational speed of an electric motor 30.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a work machine. [Background technology]

[0002] In recent years, as a measure against global warming, working machines equipped with fuel cell systems have become known as working machines that do not emit greenhouse gases. In such working machines, the fuel cells have a characteristic that their voltage rises in the low power range where the generated power is low. However, the voltage rise in the fuel cell is undesirable because it leads to a shortened lifespan, and it is necessary to suppress the frequency of voltage rise as much as possible.

[0003] To address the above-mentioned issues, the technology of Patent Document 1 is known. Patent Document 1 discloses a fuel cell system that includes a battery capable of storing the power generated by the fuel cell, and when the power required by the vehicle is low, stops the power generation operation of the fuel cell and uses the stored power in the battery to cover the power required by the vehicle, such as the air conditioner, thereby reducing the frequency of operation of the fuel cell in low power ranges. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-128778 A Summary of the Invention [Problem to be solved by the invention]

[0005] In a work machine such as a hydraulic excavator having a fuel cell system, an electric motor is driven by power supplied from a fuel cell, and the power of the electric motor is used to operate a hydraulic pump, thereby operating a hydraulic actuator provided in the work machine. Generally, in a work machine, an operator can adjust the rotation speed of the hydraulic pump as desired. Also, when there is no operation input from the operator, an auto-idle control is performed to automatically reduce the rotation speed of the hydraulic pump. In order to realize these functions while preventing overcharging and overdischarging of the power storage device, a fuel cell system for a work machine needs to control the fuel cell differently from that for general vehicles such as automobiles.

[0006] The present invention has been made in consideration of the above points, and an object of the present invention is to realize a work machine having a fuel cell system that is capable of performing fuel cell control suitable for the work machine. [Means for solving the problem]

[0007] A work machine according to the present invention comprises a fuel cell, a power storage device capable of charging and discharging electric power, an electric motor driven using electric power supplied from the fuel cell and the power storage device, and a control device that controls the fuel cell, wherein the control device controls power generation by the fuel cell so that the amount of electric power stored in the power storage device is maintained within a predetermined power storage range when the work machine is not being operated, and makes the power storage range variable in accordance with the rotation speed of the electric motor. Effect of the Invention

[0008] According to the present invention, a work machine having a fuel cell system capable of performing fuel cell control suited to the work machine can be realized.

[0009] Further features related to the present invention will become apparent from the description of the present specification and the accompanying drawings. In addition, problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0010] [Figure 1] 1 is an external view of a hydraulic excavator, which is an example of a work machine according to an embodiment of the present invention. [Diagram 2] 1 is a schematic configuration diagram of a fuel cell system in a work machine according to an embodiment of the present invention; [Diagram 3] FIG. 4 is a control block diagram showing the contents of calculation processing of a vehicle body controller. [Figure 4] FIG. 4 is a control block diagram of a motor target rotation speed calculation unit. [Diagram 5] FIG. 4 is a control block diagram of a state determination calculation unit. [Figure 6] FIG. 4 is a control block diagram of an upper and lower limit determination calculation unit. [Figure 7] FIG. 4 is a control block diagram of a power generation determination calculation unit. [Figure 8] 4 is a time chart showing an example of control of a fuel cell system in a work machine according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a work machine according to the present invention will be described in detail with reference to the accompanying drawings, taking a hydraulic excavator as an example.

[0012] 1 is an external view of a hydraulic excavator, which is an example of a work machine according to an embodiment of the present invention. The hydraulic excavator 100, which is a work machine, is equipped with a running body 3 having a pair of left and right tracks 1, 2, a rotating body 4 rotatably provided on the running body 3, a boom 5 rotatably connected to one end of the rotating body 4, an arm 6 rotatably connected to one end of the boom 5, and a bucket rotatably connected to one end of the arm 6.

[0013] The rotating body 4 is provided with a driver's cab 8, a machine room 9 that houses an engine and a hydraulic pump, and a counterweight 10. The running body 3 is provided with travel motors 11 and 12 that drive the tracks 1 and 2, respectively, and a swing motor (not shown) that drives the rotating body 4.

[0014] The hydraulic excavator 100 is equipped with a pair of left and right boom cylinders 13, 14 that drive the boom 5, an arm cylinder 15 that drives the arm 6, and a bucket cylinder 16 that drives the bucket 7. In other words, the hydraulic excavator 100 has a working arm mechanism consisting of the boom 5, the arm 6, and the bucket 7, and the posture of this working arm mechanism is determined by the extension and contraction of the boom cylinders 13, 14, the arm cylinder 15, and the bucket cylinder 16, respectively.

[0015] Fig. 2 is a schematic configuration diagram of a fuel cell system in a work machine according to one embodiment of the present invention. The fuel cell system 200 shown in Fig. 2 is provided in, for example, the hydraulic excavator 100 shown in Fig. 1, and is used to drive the hydraulic excavator 100.

[0016] The fuel cell system 200 includes a hydraulic system 180, an electrical system 185, a vehicle body controller 45 that controls the operations of these systems, and an operator system 187 for receiving operational inputs from an operator.

[0017] The hydraulic system 180 includes a hydraulic pump 40, a directional control valve 65, a hydraulic actuator (e.g., the arm cylinder 15), a hydraulic oil tank 67, a pilot pump 80, a pilot relief valve 90, etc. Note that, although Fig. 2 shows the arm cylinder 15 in Fig. 1 as an example of a hydraulic actuator, the same applies to the boom cylinders 13, 14 and the bucket cylinder 16.

[0018] The hydraulic pump 40 is driven by an electric motor 30 included in an electric system 185. An output shaft of the electric motor 30 is mechanically connected to an input shaft of the hydraulic pump 40, and the electric motor 30 is rotationally driven in the electric system 185 to drive the hydraulic pump 40. The hydraulic pump 40 is a variable displacement type, and its volume is calculated by a vehicle body controller 45 and controlled by a pump regulator 50. In addition, the hydraulic pump 40 sucks hydraulic oil from a hydraulic oil tank 67 and supplies the hydraulic oil to the arm cylinder 15 via a directional control valve 65. The hydraulic oil supplied to the arm cylinder 15 drives the arm cylinder 15, and is then discharged to the hydraulic oil tank 67 via the directional control valve 65.

[0019] An electric control lever 63, described later, of the operator system 187 transmits a lever operation signal Lv corresponding to the amount and direction of operation by the operator to the vehicle body controller 45. The electromagnetic proportional valves 65a, 65b provided in the directional control valve 65 generate a control pressure for the directional control valve 65 by appropriately reducing the pressure in a pilot pipe 95, described later, in accordance with a command value output from the vehicle body controller 45 in response to the lever operation signal Lv.

[0020] The pilot pump 80 is a device that generates pressure in a pilot circuit used to control hydraulic equipment. The pilot pump 80 is mechanically connected to the electric motor 30 and is driven by the electric motor 30. The hydraulic oil discharged by the pilot pump 80 is adjusted by a pilot relief valve 90 so as to maintain the pressure in a pilot pipe 95 at a set value (pilot relief pressure).

[0021] Electrical system 185 includes electric motor 30, inverter 35, bidirectional converter 130, step-down converter 115, step-up converter 112, fuel cell 110, fuel cell controller 145, power storage device 135, power storage device controller 140, A / C compressor 120, electric fan 125, auxiliary device controller 147, etc. Step-up converter 112, bidirectional converter 130, step-down converter 115, and inverter 35 are connected to each other via high-voltage circuit 150. High-voltage circuit 150 may include, for example, a smoothing capacitor, a fuse, etc. in addition to wiring connecting these circuits.

[0022] The fuel cell 110 is a power generation device that generates electric power through a chemical reaction between hydrogen and oxygen. The electric power generated by the fuel cell 110 is boosted by a boost converter 112 and supplied to a high voltage circuit 150. The electric power generated by the fuel cell 110 is controlled by the fuel cell controller 145 based on a target power value output from the vehicle body controller 45 to the fuel cell controller 145.

[0023] The power storage device 135 is a device capable of charging and discharging electric power, and is configured using a secondary battery such as a lithium ion battery. The charging and discharging of the power storage device 135 is controlled by the power storage device controller 140 based on the value of a target voltage output from the vehicle body controller 45 to the power storage device controller 140.

[0024] The bidirectional converter 130 converts the power input and output between the power storage device 135 and the high voltage circuit 150. For example, when surplus power occurs in the high voltage circuit 150, the bidirectional converter 130 steps down the voltage of the high voltage circuit 150 to the voltage of the power storage device 135 and outputs it to the power storage device 135. This allows the power surplus in the high voltage circuit 150 to be charged to the power storage device 135. Also, when the power of the high voltage circuit 150 is insufficient, the bidirectional converter 130 steps up the voltage of the power storage device 135 to the voltage of the high voltage circuit 150 and outputs it to the high voltage circuit 150. This allows the power insufficient in the high voltage circuit 150 to be discharged to the power storage device 135.

[0025] The inverter 35 converts the voltage of the high voltage circuit 150 into a three-phase AC voltage, thereby converting the DC power supplied from the fuel cell 110 and the power storage device 135 into AC power and outputs it to the electric motor 30. In this way, the electric motor 30 is driven using the power supplied from the fuel cell 110 and the power storage device 135.

[0026] The step-down converter 115 steps down the voltage of the high-voltage circuit 150 to a drive voltage for the A / C compressor 120 and the electric fan 125. As a result, power is supplied from the high-voltage circuit 150 to the A / C compressor 120 and the electric fan 125, which are auxiliaries of the hydraulic excavator 100, to drive these auxiliaries. Note that the power of the high-voltage circuit 150 stepped down by the step-down converter 115 may be supplied to other auxiliaries mounted on the hydraulic excavator 100. The operations of the A / C compressor 120 and the electric fan 125 are controlled by the auxiliary equipment controller 147 based on command values ​​output from the vehicle body controller 45 to the auxiliary equipment controller 147.

[0027] The operator system 187 includes the electric operation lever 63, the electric motor control dial 190, an auto idle switch 195, and an idling stop switch 197. Each of these operating means in the operator system 187 is installed at a predetermined position in the operator's cab 8 so that the operator can operate them.

[0028] The electric control lever 63 generates a lever operation signal Lv in response to the amount and direction of operation by the operator, and transmits it to the vehicle body controller 45 .

[0029] The electric motor control dial 190 is a dial-type switch that can be rotated by the operator, and sets the value designated by the dial as the target rotation speed of the electric motor 30 and transmits this setting information to the vehicle body controller 45 .

[0030] The auto idle switch 195 is a switch that determines whether to permit or prohibit auto idle control in the hydraulic excavator 100. The hydraulic excavator 100 is equipped with an auto idle function that reduces the rotation speed of the electric motor 30 to the minimum regardless of the value of the electric motor control dial 190 when an idle state in which no operational input is made by the operator continues for a certain period of time or more. The operator can set this auto idle function to either enabled or disabled by operating the auto idle switch 195.

[0031] The idling stop switch 197 is a switch that determines whether to permit or prohibit idling stop control in the hydraulic excavator 100. The hydraulic excavator 100 is equipped with an idling stop function that automatically stops the electric motor 30 when a state in which the rotation speed of the electric motor 30 has been reduced by the auto-idling function continues for a certain period of time or more. The operator can set this idling stop function to either enable or disable by operating the idling stop switch 197.

[0032] Signals from each operating portion of the operator system 187, that is, the electric operation lever 63, the electric motor control dial 190, the auto idle switch 195, and the idling stop switch 197, are each transmitted to the vehicle body controller 45.

[0033] The vehicle body controller 45 corresponds to a higher-level controller that controls the entire system of the hydraulic excavator 100. The vehicle body controller 45 outputs appropriate command values ​​to the pump regulator 50 that controls the hydraulic pump 40, the electromagnetic proportional valves 65a, 65b that adjust the pressure in the pilot pipe 95, and each device of the electrical system 185 that corresponds to a lower-level controller (the inverter 35, the fuel cell controller 145, the power storage device controller 140, and the auxiliary controller 147).

[0034] The power storage device controller 140, fuel cell controller 145, inverter 35 and auxiliary controller 147 each acquire information relating to the state of each device to be controlled (the state of charge (SOC) of the power storage device 135, the voltage and current of the fuel cell 110, the voltage, current and actual rotation speed of the electric motor 30, the voltage and current of the A / C compressor 120, and the voltage and current of the electric fan 125) and transmit this information to the vehicle controller 45.

[0035] Next, the contents of the calculation processing performed by the vehicle body controller 45 will be described below with reference to Figs.

[0036] 3 is a control block diagram showing the contents of the calculation process of the vehicle body controller 45. The vehicle body controller 45 calculates the target values ​​for the power generated by the fuel cell 110 and the rotation speed of the motor 30 according to the control block diagram of FIG. 3 based on the input information of the lever operation amount 64, the auto-idle setting 196, the electric motor control setting 191, the idling stop setting 198, the power storage device SOC 350, the actual motor rotation speed 365, the electric motor current 317, the electric motor voltage 319, the A / C compressor current 322, the A / C compressor voltage 324, the electric fan current 326, and the electric fan voltage 328. The obtained calculation results are then transmitted to the fuel cell controller 145 and the inverter 35 as the fuel cell power generation target value 410 and the electric motor target rotation speed 425, respectively. The fuel cell controller 145 controls the power generation by the fuel cell 110 according to the fuel cell power generation target value 410 from the vehicle body controller 45. The inverter 35 controls the drive of the electric motor 30 in accordance with a target electric motor speed 425 from the vehicle body controller 45 .

[0037] In the vehicle body controller 45, each of the above input information is acquired as follows. That is, the lever operation amount 64 represents the operation amount of the electric operation lever 63, and is acquired by the lever operation signal Lv input from the electric operation lever 63. The auto idle setting 196 represents the setting state (permitted or prohibited) of the auto idle control by the auto idle switch 195, the electric motor control setting 191 represents the setting state of the target rotation speed of the electric motor 30 by the electric motor control dial 190, and the idling stop setting 198 represents the setting state (permitted or prohibited) of the idling stop control by the idling stop switch 197. The power storage device SOC 350 represents the state of charge (SOC) corresponding to the amount of electricity stored in the power storage device 135, and is input from the power storage device controller 140. The electric motor actual rotation speed 365 represents the actual rotation speed of the electric motor 30, and is input from the inverter 35. Motor current 317 and motor voltage 319 represent the current and voltage of motor 30 and are input from inverter 35. A / C compressor current 322 and A / C compressor voltage 324 represent the current and voltage of A / C compressor 120 and are input from auxiliary controller 147. Motor fan current 326 and motor fan voltage 328 represent the current and voltage of motor fan 125 and are input from auxiliary controller 147.

[0038] The lever operation amount 64, auto idle setting 196, and motor control setting 191 are input to a motor target rotation speed calculation unit 430 together with a state determination value 315 calculated by a state determination calculation unit 310, which will be described later. The motor target rotation speed calculation unit 430 has a control block shown in Fig. 4, which will be described later, and calculates a target value for the rotation speed of the motor 30 based on this input information, and outputs the calculation result as a motor target rotation speed 425.

[0039] The lever operation amount 64, the idling stop setting 198, and the power storage device SOC 350 are input to a state determination calculation unit 310. The state determination calculation unit 310 has a control block shown in Fig. 5 described below, and determines whether the state of the hydraulic excavator 100 corresponds to "0 (working)", "1 (idling)", "2 (idling stop)", or "3 (system shutdown)" based on this input information, and outputs one of values ​​0 to 3 according to the determination result as a state determination value 315.

[0040] Motor power requirement calculation unit 320 multiplies motor current 317 and motor voltage 319 measured by inverter 35, and then multiplies the multiplied value by a coefficient (1 / 1000) to adjust the units, to calculate the power required to drive motor 30, and outputs the calculation result as motor power requirement 321.

[0041] A / C compressor required power calculation unit 330 multiplies A / C compressor current 322 and A / C compressor voltage 324 measured by auxiliary controller 147, and then multiplies the multiplied value by a coefficient (1 / 1000) to adjust the units, to calculate the power required to drive A / C compressor 120, and outputs the calculation result as A / C compressor required power 331.

[0042] An electric fan required power calculation unit 332 multiplies electric fan current 326 and electric fan voltage 328 measured by auxiliary controller 147, and further multiplies the result by a coefficient (1 / 1000) to adjust the units, to calculate the power required to drive electric fan 125, and outputs the calculation result as electric fan required power 333.

[0043] Adder 340 adds A / C compressor required power 331 and electric fan required power 333 to calculate the power required to drive the accessories, and outputs the calculation result as accessory required power 341.

[0044] Charge / discharge power calculation unit 355 calculates the power when charging or discharging power storage device 135 based on power storage device SOC 350, and outputs the calculation result as charge / discharge power 360. For example, charge / discharge power calculation unit 355 stores information indicating the relationship between power storage device SOC 350 and charge / discharge power 360 in the form of a function, table, or the like in advance, and can use this information to determine the value of charge / discharge power 360 so as to bring the state of charge of power storage device 135 closer to a predetermined target SOC.

[0045] The adder 345 adds up the electric motor required power 321, the auxiliary required power 341, and the charging / discharging power 360 to calculate the required power for the fuel cell 110 when the hydraulic excavator 100 is in an operating state, and outputs the calculation result as the first fuel cell required power 347.

[0046] The state judgment value 315 and the actual motor rotation speed 365 are input to an upper / lower limit judgment calculation unit 370. The upper / lower limit judgment calculation unit 370 has a control block shown in FIG. 6 described later, and calculates two types of judgment values ​​for controlling power generation by the fuel cell 110 so that the SOC of the power storage device 135 is maintained within a predetermined range based on this input information. Of the two types of judgment values ​​calculated, the judgment value corresponding to the lower limit of the SOC, i.e., the SOC value for restarting power generation when the fuel cell 110 is in a power generation stopped state, is output as a restart judgment value 375. In addition, the judgment value corresponding to the upper limit of the SOC, i.e., the SOC value for stopping power generation when the fuel cell 110 is in a power generation state, is output as a stop judgment value 380.

[0047] The restart determination value 375 and the stop determination value 380 are input to a power generation determination calculation unit 385 together with the power storage device SOC 350. The power generation determination calculation unit 385 has a control block shown in Fig. 7 described below, and determines whether or not to cause the fuel cell 110 to generate power based on this input information. If it is determined that the fuel cell 110 should generate power, it outputs "1 (power generation)" as the power generation determination value 390, and if it is determined that the fuel cell 110 should not generate power, it outputs "0 (stop)".

[0048] The selection unit 397 selects either a predetermined minimum power generation power 395 or 0 based on the power generation determination value 390 calculated by the power generation determination calculation unit 385, thereby calculating the power required for the fuel cell 110 when the hydraulic excavator 100 is in an idle state or an idling stop state, and outputs the calculation result as the second fuel cell required power 400. In other words, when the power generation determination value 390 is 1, the selection unit 397 outputs the minimum power generation power 395, which is predetermined as the power generation capacity of the fuel cell 110 when the hydraulic excavator 100 is not being operated, as the second fuel cell required power 400, and when the power generation determination value 390 is 0, the selection unit 397 outputs "0", which means that power generation by the fuel cell 110 is stopped, as the second fuel cell required power 400. This enables the fuel cell controller 145 to control the fuel cell 110 so that the SOC of the power storage device 135 is maintained within a predetermined range.

[0049] The selection unit 405 selects either the first fuel cell requested power 347, the second fuel cell requested power 400, or 0 based on the state determination value 315 obtained by the state determination calculation unit 310, thereby calculating a target value for the power generation of the fuel cell 110 according to the state of the hydraulic excavator 100, and outputs the calculation result as the fuel cell power generation target value 410. That is, when the state determination value 315 is "0 (working)", the selection unit 405 outputs the first fuel cell requested power 347 as the fuel cell power generation target value 410, and when the state determination value 315 is "1 (idling)" or "2 (idling stop)", the selection unit 405 outputs the second fuel cell requested power 400 as the fuel cell power generation target value 410. When the state determination value 315 is "3 (system shutdown)", the selection unit 405 outputs "0", which means that power generation by the fuel cell 110 is stopped, as the fuel cell power generation target value 410.

[0050] By performing the above-described arithmetic processing, the vehicle body controller 45 can calculate the target power to be generated by the fuel cell 110 in accordance with the state of the hydraulic excavator 100, and control the power generation by the fuel cell 110 based on this target power. That is, when the hydraulic excavator 100 is in a working state due to the operation of the operator, the vehicle body controller 45 can calculate the required power necessary to drive the electric motor 30 and each auxiliary device (A / C compressor 120, electric fan 125), calculate the power requested of the fuel cell 110 based on this required power, and calculate the target power of the fuel cell 110 based on this requested power. Also, when the hydraulic excavator 100 is not being operated, that is, when the operator is not operating the hydraulic excavator 100, it is possible to determine whether the state of the hydraulic excavator 100 corresponds to an idle state, an idling stop state, or a system shutdown state, and based on the determination result, calculate the target power of the fuel cell 110 so that the amount of electricity stored in the electricity storage device 135 is maintained within a predetermined electricity storage range.

[0051] 4 is a control block diagram of the motor target speed calculation unit 430. The lever operation amount 64, the auto idle setting 196, the motor control setting 191, and the state determination value 315 are input to the motor target speed calculation unit 430.

[0052] The determination calculation unit 432 determines whether the lever operation amount 64 is equal to or greater than a predetermined threshold value γ, and outputs an operation determination value 434 that indicates the determination result. Specifically, if the lever operation amount 64 is equal to or greater than the threshold value γ, it outputs "1 (operation state)" as the operation determination value 434, and if the lever operation amount 64 is less than the threshold value γ, it outputs "0 (non-operation state)" as the operation determination value 434.

[0053] Based on the operation determination value 434 by the determination calculation unit 432, the determination calculation unit 436 determines whether or not a state in which the lever operation amount 64 is less than the threshold value γ has continued for a predetermined idle determination time or more, and outputs the determination result as the idle determination value 440. Specifically, if "0 (non-operation state)" is continuously output as the operation determination value 434 for a period of time equal to or longer than a preset idle determination time, the determination calculation unit 436 outputs "1 (idle determination)" as the idle determination value 440 for that continuing period, and outputs 0 otherwise.

[0054] An AND calculation unit 445 calculates an AND value of the idle determination value 440 and the auto idle setting 196, and outputs the calculation result as an auto idle implementation determination value 450. Specifically, when both the idle determination value 440 and the auto idle setting 196 are 1, that is, when the state in which the lever operation amount 64 is less than the threshold value γ continues for more than the specified idle determination time, and when the operator has set the auto idle switch 195 to permit auto idle control, the AND calculation unit 445 outputs "1 (auto idle implemented)" as the auto idle implementation determination value 450, and in other cases outputs "0 (auto idle not implemented)."

[0055] The set rotation speed calculation unit 460 calculates a set value of the rotation speed of the electric motor 30 when the hydraulic excavator 100 is in a working state, based on the electric motor control setting 191, and outputs the calculation result as a set rotation speed 465. For example, the set rotation speed calculation unit 460 pre-stores information indicating the relationship between the dial value of the electric motor control dial 190 represented by the electric motor control setting 191 and the set rotation speed 465 in the form of a function, table, or the like, and by using this information, it is possible to determine the value of the set rotation speed 465 so that the rotation speed of the electric motor 30 when the hydraulic excavator 100 is in a working state becomes the rotation speed set by the operator using the dial value of the electric motor control dial 190.

[0056] The selection unit 470 selects either a predetermined auto-idle rotation speed or a set rotation speed 465 based on the auto-idle execution determination value 450 found by the AND calculation unit 445, thereby calculating a target value of the rotation speed when driving the electric motor 30 in accordance with the state of the hydraulic excavator 100, and outputs the calculation result as a driving target rotation speed 475. That is, when the auto-idle execution determination value 450 is "1 (auto-idle execution)", the hydraulic excavator 100 is put into an auto-idle state to reduce the rotation speed of the electric motor 30, so that an auto-idle rotation speed that is preset as a rotation speed lower than that in a working state is output as the driving target rotation speed 475. On the other hand, when the auto-idle execution determination value 450 is 0, the rotation speed set by the operator using the dial value of the electric motor control dial 190 is output as the driving target rotation speed 475.

[0057] The selection unit 480 selects either the driving target rotation speed 475 or 0 based on the state determination value 315, and outputs the selected value as the motor target rotation speed 425. That is, when the state determination value 315 is "0 (working)" or "1 (idling)", the selection unit 480 outputs the driving target rotation speed 475 as the motor target rotation speed 425 in order to put the motor 30 in a driving state. When the state determination value 315 is "2 (idling stop)" or "3 (system shutdown)", the selection unit 480 outputs 0 as the motor target rotation speed 425 in order to stop the motor 30.

[0058] By performing the above-described calculation process, the electric motor target rotation speed calculation unit 430 can output a preset auto idle rotation speed as the electric motor target rotation speed 425 during auto idle control when the state in which the operator has not operated the electric operation lever 63 continues for a predetermined idle determination time or longer and the operator has set the auto idle control to permitted using the auto idle switch 195. On the other hand, when at least one of these auto idle conditions is not satisfied, the rotation speed set by the operator using the dial value of the electric motor control dial 190 can be output as the electric motor target rotation speed 425 during non-auto idle control. Furthermore, when the state of the hydraulic excavator 100 corresponds to either "2 (idling stop)" or "3 (system shutdown)", the electric motor target rotation speed 425 can be set to 0 to stop the electric motor 30.

[0059] 5 is a control block diagram of state determination calculation unit 310. State determination calculation unit 310 receives lever operation amount 64, idling stop setting 198, and power storage device SOC 350.

[0060] The determination calculation unit 505 determines whether the lever operation amount 64 is less than a predetermined threshold value γ, and outputs an operation determination value 510 that indicates the determination result. Specifically, if the lever operation amount 64 is less than the threshold value γ, "1 (non-operation state)" is output as the operation determination value 510, and if the lever operation amount 64 is equal to or greater than the threshold value γ, "0 (operation state)" is output as the operation determination value 510.

[0061] The selection unit 525 selects either "0 (working)" or "1 (idle)" based on the operation determination value 510 calculated by the determination calculation unit 505, and outputs the selection result as the first state determination value 530. That is, when the operation determination value 510 is "0 (operating state)", the selection unit 525 outputs "0 (working)" as the first state determination value 530, and when the operation determination value 510 is "1 (non-operating state)", the selection unit 525 outputs "1 (idle)" as the first state determination value 530.

[0062] The determination calculation unit 545 determines whether the idle state of the hydraulic excavator 100 has continued for a predetermined idling stop determination time or more, based on the first state determination value 530 from the selection unit 525, and outputs the determination result as an idling stop determination value 550. Specifically, if "1 (idling)" is continuously output as the first state determination value 530 for a period of time equal to or longer than a preset idling stop determination time, the determination calculation unit 545 outputs 1 as the idling stop determination value 550 for that continuing period, and outputs 0 in other cases. Note that this idling stop determination time is set to be at least longer than the idling determination time described with reference to FIG. 4.

[0063] The AND operation unit 565 operates an AND value of the idling stop determination value 550 and the idling stop setting 198, and outputs the operation result as an idling stop implementation determination value 570. Specifically, when both the idling stop determination value 550 and the idling stop setting 198 are 1, that is, when the idling state of the hydraulic excavator 100 has continued for a prescribed idling stop determination time or longer and the operator has set the idling stop switch 197 to permit idling stop control, the AND operation unit 565 outputs "1 (idling stop implemented)" as the idling stop implementation determination value 570, and otherwise outputs "0 (idling stop not implemented)."

[0064] The selection unit 575 selects either the first state determination value 530 or “2 (idling stop)” based on the idling stop implementation determination value 570 calculated by the AND operation unit 565, and outputs the selection result as the second state determination value 580. That is, when the idling stop implementation determination value 570 is “0 (idling stop not implemented)”, the selection unit 575 outputs the first state determination value 530 as it is as the second state determination value 580, and when the idling stop implementation determination value 570 is “1 (idling stop implemented)”, the selection unit 575 outputs “2 (idling stop)” as the second state determination value 580.

[0065] The determination calculation unit 590 determines whether or not the idling stop state of the hydraulic excavator 100 has continued for a predetermined shutdown determination time or longer, based on the second state determination value 580 from the selection unit 575, and outputs the determination result as a shutdown determination value 595. Specifically, if "2 (idling stop)" is continuously output as the second state determination value 580 for a period of time equal to or longer than a preset shutdown determination time, the determination calculation unit 590 outputs 1 as the shutdown determination value 595, and otherwise outputs 0.

[0066] The determination calculation unit 605 determines whether the power storage device SOC 350 is equal to or greater than a preset target value for the hydraulic excavator 100 during work, and outputs a power storage amount determination value 610 indicating the determination result. Specifically, if the power storage device SOC 350 is equal to or greater than the target value during work, 1 is output as the power storage amount determination value 610, and if the power storage device SOC 350 is less than the target value, 0 is output as the power storage amount determination value 610.

[0067] The AND operation unit 615 operates an AND value of the shutdown determination value 595 and the power storage amount determination value 610, and outputs the operation result as a system shutdown implementation determination value 620. Specifically, when both the shutdown determination value 595 and the power storage amount determination value 610 are 1, that is, when the idling stop state of the hydraulic excavator 100 has continued for a specified shutdown determination time or more and the current power storage amount of the power storage device 135 is a predetermined target value or more, the AND operation unit 615 outputs "1 (system shutdown implemented)" as the system shutdown implementation determination value 620, and otherwise outputs "0 (system shutdown not implemented)."

[0068] The selection unit 600 selects either the second state determination value 580 or "3 (system shutdown)" based on the system shutdown implementation determination value 620 calculated by the AND operation unit 615, and outputs the selection result as the state determination value 315. In other words, when the system shutdown implementation determination value 620 is "0 (system shutdown not implemented)", the selection unit 600 outputs the second state determination value 580 as it is as the state determination value 315, and when the system shutdown implementation determination value 620 is "1 (system shutdown implemented)", the selection unit 600 outputs "3 (system shutdown)" as the state determination value 315.

[0069] By performing the calculation processing described above, the state determination calculation unit 310 can appropriately determine the state of the hydraulic excavator 100 depending on the operation state of the electric control lever 63, the setting state of the idling stop control by the idling stop switch 197, the charging state of the power storage device 135, etc., and output one of the values ​​"0 (working)", "1 (idling)", "2 (idling stop)", or "3 (system shutdown)" as the state determination value 315.

[0070] 6 is a control block diagram of upper / lower limit determination calculation unit 370. Upper / lower limit determination calculation unit 370 receives state determination value 315 and actual motor rotation speed 365.

[0071] The upper limit calculation unit 650 calculates an upper limit for the SOC of the power storage device 135 according to the state of the motor 30 based on the actual motor rotation speed 365, and outputs the calculation result as an upper limit 655. For example, the upper limit calculation unit 650 stores information indicating the relationship between the actual motor rotation speed 365 and the upper limit 655 in advance in a memory (not shown) in the form of a function, a table, or the like, and by using this information, the upper limit calculation unit 650 can determine the upper limit 655 so that the higher the rotation speed of the motor 30 is, the lower the upper limit 655 is between a predetermined third judgment value and a fourth judgment value. The fourth judgment value corresponds to the SOC upper limit of the power storage device 135 when the motor 30 is at the minimum rotation speed, and the third judgment value corresponds to the SOC upper limit of the power storage device 135 when the motor 30 is at the maximum rotation speed.

[0072] The selection unit 660 selects either the upper limit value 655 calculated by the upper limit value calculation unit 650 or the fourth determination value based on the state determination value 315, and outputs the selection result as the stop determination value 380. That is, when the state determination value 315 is “2 (idling stop)”, the selection unit 660 outputs the fourth determination value as the stop determination value 380, and otherwise outputs the upper limit value 655 as the stop determination value 380.

[0073] The lower limit value calculation unit 665 calculates a lower limit value for the SOC of the power storage device 135 according to the state of the electric motor 30 based on the actual motor rotation speed 365, and outputs the calculation result as a lower limit value 670. For example, the lower limit value calculation unit 665 stores information indicating the relationship between the actual motor rotation speed 365 and the lower limit value 670 in the form of a function, a table, or the like in advance, and by using this information, the lower limit value 670 can be determined so that the lower limit value 670 becomes a lower value as the rotation speed of the electric motor 30 increases between a predetermined first judgment value and a second judgment value. Note that the second judgment value corresponds to the SOC lower limit value of the power storage device 135 when the electric motor 30 is at the minimum rotation speed, and the first judgment value corresponds to the SOC lower limit value of the power storage device 135 when the electric motor 30 is at the maximum rotation speed.

[0074] The selection unit 675 selects either the lower limit value 670 calculated by the lower limit value calculation unit 665 or the first determination value based on the state determination value 315, and outputs the selection result as the restart determination value 375. In other words, when the state determination value 315 is “2 (idling stop)”, the first determination value is output as the restart determination value 375, and in other cases, the lower limit value 670 is output as the restart determination value 375.

[0075] By performing the calculation process described above, the upper / lower limit determination calculation unit 370 can determine an upper limit value and a lower limit value for the SOC of the power storage device 135 according to the rotation state of the electric motor 30, and can use these as determination values ​​when stopping or restarting power generation of the fuel cell 110 to calculate two types of determination values ​​for controlling the fuel cell 110. That is, when the rotation speed of the electric motor 30 decreases, the stop determination value 380 and the restart determination value 375 can be increased accordingly. Furthermore, when the hydraulic excavator 100 is in an idling stop state and the electric motor 30 is stopped as a result, the stop determination value 380 can be set to the fourth determination value, which is the maximum value, and the restart determination value 375 can be set to the first determination value, which is the minimum value.

[0076] 7 is a control block diagram of power generation determination calculation unit 385. Power storage device SOC 350, restart determination value 375, and stop determination value 380 are input to power generation determination calculation unit 385.

[0077] The stop determination calculation unit 700 determines whether the power storage device SOC 350 is less than or equal to the stop determination value 380, and if the power storage device SOC 350 is less than or equal to the stop determination value 380, outputs 1 as the calculation value 730, and if the power storage device SOC 350 is greater than the stop determination value 380, outputs 0 as the calculation value 730.

[0078] The restart determination calculation unit 710 determines whether the storage device SOC 350 is less than or equal to the restart determination value 375, and if the storage device SOC 350 is less than or equal to the restart determination value 375, outputs 1 as the second power generation determination value 715, and if the storage device SOC 350 is greater than the restart determination value 375, outputs 0 as the second power generation determination value 715.

[0079] The AND operation unit 740 operates an AND value of the operation value 730 and the previous power generation determination value 390, and outputs the operation result as a first power generation determination value 705. Specifically, if both the operation value 730 and the previous power generation determination value 390 are 1, that is, if the power storage device SOC 350 is equal to or less than the stop determination value 380 and the power generation determination operation unit 385 determined in the previous calculation that the fuel cell 110 should generate power, then the AND operation unit 740 outputs 1 as the first power generation determination value 705, and if the power storage device SOC 350 is greater than the stop determination value 380 or if the power generation determination operation unit 385 determined in the previous calculation that the fuel cell 110 should not generate power, then the AND operation unit 740 outputs 0 as the first power generation determination value 705.

[0080] The OR calculation unit 720 calculates an OR value of the first power generation determination value 705 and the second power generation determination value 715, and outputs the calculation result as the power generation determination value 390. Specifically, when at least one of the first power generation determination value 705 and the second power generation determination value 715 is 1, that is, when the power storage device SOC 350 is equal to or less than the stop determination value 380 and the power generation determination calculation unit 385 has determined in the previous calculation that the fuel cell 110 should generate power, or when the power storage device SOC 350 is equal to or less than the restart determination value 375, the OR calculation unit 720 outputs "1 (power generation)" as the power generation determination value 390. On the other hand, when neither of these power generation conditions is satisfied, the OR calculation unit 720 outputs "0 (stop)" as the power generation determination value 390.

[0081] By performing the calculation process described above, when the amount of stored power in the power storage device 135 exceeds the stop determination value 380, the power generation determination calculation unit 385 can output "0 (stop)" as the power generation determination value 390 until the amount of stored power falls below the restart determination value 375. Furthermore, when the amount of stored power in the power storage device 135 falls below the restart determination value 375, the power generation determination calculation unit 385 can output "0 (stop)" as the power generation determination value 390 until the amount of stored power exceeds the stop determination value 380. This makes it possible to control power generation by the fuel cell 110 (including the execution, stop, and restart of power generation) so that the amount of stored power in the power storage device 135 is maintained within a predetermined power storage range from the restart determination value 375 to the stop determination value 380.

[0082] FIG. 8 is a time chart showing an example of the control of the fuel cell system in the work machine according to one embodiment of the present invention. In the time chart of FIG. 8, when the vehicle body controller 45 controls the power generation of the fuel cell 110 in the fuel cell system 200 of FIG. 2, graphs 810 to 840 show an example of the time change of the state determination value 315 and the fuel cell power generation target value 410 calculated by the vehicle body controller 45, and the actual motor rotation speed 365 and the power storage device SOC 350 observed at this time. In the graph 830 of the power storage device SOC 350, the two broken lines show the upper and lower limits of the power storage range of the power storage device 135. The vehicle body controller 45 controls the power generation of the fuel cell 110 so that the amount of power stored in the power storage device 135 is maintained within the power storage range between the upper and lower limits.

[0083] Assume that work is performed in the hydraulic excavator 100 from time T0 to time T1. At this time, as shown in graph 810, the state determination value 315 is "0 (working)". Therefore, in the vehicle body controller 45, the rotation speed set by the operator using the dial value of the motor control dial 190 is output as the motor target rotation speed 425 from the motor target rotation speed calculation unit 430. By controlling the rotation speed of the motor 30 according to this motor target rotation speed 425, for example, as shown in graph 820, the actual motor rotation speed 365 is maintained at the maximum rotation speed. Note that in this example, the description will be given assuming that the rotation speed set using the dial value of the motor control dial 190 is the maximum rotation speed.

[0084] Furthermore, first fuel cell required power 347, which is the sum of electric motor required power 321, auxiliary required power 341, and charge / discharge power 360, is output as a fuel cell power generation target value 410. By controlling the power generation of the fuel cell 110 in accordance with this fuel cell power generation target value 410, for example, as shown in graph 830, the power storage device SOC 350 is maintained at a predetermined target value during work.

[0085] At time T1, when the operator is no longer operating the electric operation lever 63, it is determined that the hydraulic excavator 100 has entered an idle state, and as shown in graph 810, the state determination value 315 transitions from "0 (working)" to "1 (idle)." At this time, in the vehicle body controller 45, a restart determination value 375 and a stop determination value 380 are set in accordance with the actual motor rotation speed 365. In this example, as shown in graph 820, since the actual motor rotation speed 365 is the maximum rotation speed at time T1, the first determination value and the third determination value corresponding thereto are set as the restart determination value 375 and the stop determination value 380, respectively.

[0086] Furthermore, minimum power generation 395, which is predetermined as the power generation power of the fuel cell 110 when the hydraulic excavator 100 is not being operated, is output as the fuel cell power generation target value 410. This fuel cell power generation target value 410 is greater than the power consumption of the electric motor 30, the A / C compressor 120, and the electric fan 125 when the hydraulic excavator 100 is not being operated. Therefore, the power storage device 135 is charged by the surplus power, and as shown in graph 830, the power storage device SOC 350 gradually increases.

[0087] At time T2, when the power storage device SOC 350 reaches the third determination value (stop determination value 380), the power generation determination calculation unit 385 in the vehicle body controller 45 sets the power generation determination value 390 to 0, thereby stopping the power generation of the fuel cell 110. As a result, the electric motor 30, the A / C compressor 120, and the electric fan 125 are driven using the electric power stored in the power storage device 135, and as shown in graph 830, the power storage device SOC 350 gradually decreases.

[0088] At time T3, when the power storage device SOC 350 reaches the first judgment value (restart judgment value 375), the power generation judgment value 390 in the vehicle body controller 45 becomes 1 by the power generation judgment calculation unit 385, and power generation of the fuel cell 110 is restarted. At this time, similar to the period from time T1 to time T2, a minimum power generation power 395 that is predetermined as the power generation power of the fuel cell 110 is output as the fuel cell power generation target value 410. Therefore, the power storage device 135 is charged by the surplus power, and as shown in graph 830, the power storage device SOC 350 gradually increases.

[0089] Thereafter, fuel cell 110 alternately starts and stops generating power so that power storage device SOC 350 falls within the range from the first determination value to the third determination value.

[0090] At time T4, it is assumed that a predetermined idle determination time or more has elapsed since time T1 when the hydraulic excavator 100 entered an idle state. At this time, if the operator has permitted the setting of auto idle control using the auto idle switch 195, in the vehicle body controller 45, a predetermined auto idle rotation speed (e.g., minimum rotation speed) is output as the electric motor target rotation speed 425 from the electric motor target rotation speed calculation unit 430, and the rotation speed of the electric motor 30 is controlled according to this electric motor target rotation speed 425. As a result, for example, as shown in graph 820, the electric motor actual rotation speed 365 drops from the maximum rotation speed (the rotation speed set by the dial value of the electric motor control dial 190) to the minimum rotation speed (auto idle rotation speed), and the high idle state is switched to auto idle control.

[0091] Furthermore, in accordance with this change in the actual motor rotation speed 365, as shown in graph 830, the restart determination value 375 increases from the first determination value to the second determination value, and the stop determination value 380 increases from the third determination value to the fourth determination value. This changes the range of the power storage device SOC 350 used to control the power generation of the fuel cell 110. In the subsequent auto-idle state, the fuel cell 110 alternates between generating power and stopping so that the power storage device SOC 350 is within the range from the second determination value to the fourth determination value.

[0092] Then, at time T5, it is assumed that a predetermined idling stop judgment time or more has passed since time T1 when the hydraulic excavator 100 became in an idling state. At this time, if the operator permits the setting of idling stop control using the idling stop switch 197, the state judgment value 315 in the vehicle body controller 45 changes from "1 (idling)" to "2 (idling stop)" as shown in graph 810. As a result, 0 is output as the electric motor target rotation speed 425 from the electric motor target rotation speed calculation unit 430, and stop control of the electric motor 30 is performed in accordance with this electric motor target rotation speed 425. As a result, for example, as shown in graph 820, the electric motor actual rotation speed 365 becomes 0.

[0093] Furthermore, as shown in graph 830, accompanying this change in the actual motor rotation speed 365, the restart determination value 375, which increased from the first determination value to the second determination value when the actual motor rotation speed 365 dropped from the maximum rotation speed to the minimum rotation speed (auto idle rotation speed) at time T4, decreases from the second determination value to the first determination value. This expands the range of the power storage device SOC 350 used for controlling the power generation of the fuel cell 110. That is, since the hydraulic excavator 100 does not normally suddenly shift to a working state in an idling stop state, the restart determination value 375 for resuming the power generation of the fuel cell 110 is lowered so that the range of the power storage device SOC 350 is expanded and the stop time of the fuel cell 110 becomes longer.

[0094] In the subsequent idling stop state, the fuel cell 110 alternately generates and stops power generation so that the power storage device SOC 350 falls within the range from the first determination value to the fourth determination value.

[0095] At time T6, it is assumed that a predetermined shutdown judgment time or more has elapsed since time T5 when the hydraulic excavator 100 entered the idling stop state. At this time, the vehicle body controller 45 judges that the conditions for system shutdown are met, and the judgment calculation unit 590 outputs 1 as the shutdown judgment value 595. However, since the power storage device SOC 350 has not reached the predetermined target value during work, the state judgment value 315 remains at "2 (idling stop)." That is, in order to ensure stability when the system is restarted, the current control state is maintained until the power storage device SOC 350 reaches the target value during work.

[0096] After that, at time T7, when the power storage device SOC 350 reaches the working target value, in the vehicle body controller 45, the state determination value 315 transitions from "2 (idling stop)" to "3 (system shutdown)" as shown in graph 810. This causes the fuel cell power generation target value 410 to become 0, and the fuel cell 110 is controlled to stop in accordance with this fuel cell power generation target value 410, and the fuel cell system 200 is shut down at time T8.

[0097] As described above, in the fuel cell system 200 of this embodiment, when the operator is not operating the hydraulic excavator 100, the amount of stored electricity in the electricity storage device 135 can be maintained within a predetermined storage range by switching between stopping and restarting power generation of the fuel cell 110. In addition, the stop determination value 380 and the restart determination value 375 can be increased or decreased depending on the rotation speed of the electric motor 30 at this time, thereby making it possible to vary the storage range of the electricity storage device 135. Therefore, even if the rotation speed of the electric motor 30 is instantly restored from a low rotation speed state to a normal state when the hydraulic excavator 100 resumes work, it is possible to prevent the electricity storage device 135 from falling into an over-discharge while suppressing a voltage rise in the fuel cell 110.

[0098] In the fuel cell system 200 of this embodiment, with the above-described configuration, by determining whether or not to generate power in the fuel cell 110 depending on the rotation speed of the electric motor 30, it is possible to prevent over-discharge of the storage device 135 while suppressing deterioration of the fuel cell 110.

[0099] According to the embodiment of the present invention described above, the following advantageous effects are achieved.

[0100] (1) A hydraulic excavator 100, which is a work machine, includes a fuel cell 110, a power storage device 135 capable of charging and discharging electric power, an electric motor 30 driven by electric power supplied from the fuel cell 110 and the power storage device 135, and a vehicle body controller 45 as a control device that controls the fuel cell 110. When the hydraulic excavator 100 is not being operated by an operator, that is, when the state of the hydraulic excavator 100 corresponds to any one of "1 (idle)", "2 (idling stop)", and "3 (system shutdown)", the vehicle body controller 45 controls power generation by the fuel cell 110 so that the amount of electric power stored in the power storage device 135 (power storage device SOC 350) is maintained within a predetermined power storage range, and increases or decreases a stop determination value 380 and a restart determination value 375 according to the rotation speed of the electric motor 30 (actual electric motor rotation speed 365), thereby making the power storage range variable. In this way, a work machine having a fuel cell system 200 capable of performing fuel cell control suitable for a work machine such as the hydraulic excavator 100 can be realized.

[0101] (2) The above-mentioned power storage range is defined as a charging state between a stop determination value 380 at which power generation by the fuel cell 110 is stopped and a restart determination value 375 at which power generation by the fuel cell 110 is restarted. When the power storage device SOC 350 exceeds the stop determination value 380, the vehicle body controller 45 controls power generation by the fuel cell 110 so as to stop power generation by the fuel cell 110 until the power storage device SOC 350 becomes lower than the restart determination value 375. In addition, the upper limit value calculation unit 650 determines the upper limit value 655 so that the higher the actual motor rotation speed 365 becomes, the lower the value becomes, so that the stop determination value 380 increases with a decrease in the actual motor rotation speed 365. In this way, the upper limit value of the amount of stored power of the power storage device 135, which corresponds to a threshold value at which power generation by the fuel cell 110 is stopped, can be appropriately determined according to the rotation speed of the motor 30 so that the power storage device 135 is not overcharged.

[0102] (3) The above-mentioned storage range is defined as a charging state between a stop determination value 380 at which power generation by the fuel cell 110 is stopped and a restart determination value 375 at which power generation by the fuel cell 110 is restarted. When the power storage device SOC 350 becomes lower than the restart determination value 375, the vehicle body controller 45 controls power generation by the fuel cell 110 so as to maintain power generation by the fuel cell 110 until the power storage device SOC 350 exceeds the stop determination value 380. In addition, the lower limit value calculation unit 665 determines the lower limit value 670 so that the lower the actual motor rotation speed 365 becomes, the lower the restart determination value 375 becomes as the actual motor rotation speed 365 decreases. In this way, the lower limit value of the amount of stored power of the power storage device 135, which corresponds to the threshold value at which power generation by the fuel cell 110 is restarted, can be appropriately determined according to the rotation speed of the motor 30 so as to prevent the power storage device 135 from being overdischarged.

[0103] (4) When the non-operation state of the hydraulic excavator 100 continues for a predetermined idle determination time or more, the vehicle body controller 45 causes the electric motor target rotation speed calculation unit 430 to output a preset auto idle rotation speed as the electric motor target rotation speed 425 during auto idle control, thereby reducing the rotation speed of the electric motor 30 to a predetermined auto idle rotation speed. Furthermore, when the non-operation state of the hydraulic excavator 100 continues for a predetermined idle stop determination time or more, the electric motor target rotation speed calculation unit 430 outputs 0 as the electric motor target rotation speed 425, thereby implementing idling stop control to stop the electric motor 30. Furthermore, when the electric motor 30 is stopped by the idling stop control, the restart determination value 375, which was increased when the rotation speed of the electric motor was reduced to the auto idle rotation speed as described above, is reduced. As a result, during the idling stop state, the range of the power storage device SOC 350 is expanded, and power generation control of the fuel cell 110 can be performed so that the stop time of the fuel cell 110 is extended.

[0104] (5) After stopping the electric motor 30 by the above-mentioned idling stop control, if the hydraulic excavator 100 is not operated for a predetermined shutdown judgment time or longer, the vehicle body controller 45 shuts down the fuel cell system 200 of the hydraulic excavator 100, including the fuel cell 110, when the power storage device SOC 350 is equal to or higher than a predetermined working target value. This makes it possible to shut down the fuel cell system 200 at an appropriate timing while ensuring stability when the system is restarted.

[0105] Although the embodiments of the present invention have been described above in detail, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the spirit of the present invention described in the claims. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those having all of the configurations described. In addition, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0106] 30: Electric motor 35: Inverter 40: Hydraulic pump 45: Vehicle controller 63: Electric control lever 100: Hydraulic excavator 110: Fuel cell 112: Boost converter 115: Step-down converter 120: A / C compressor 125: Electric fan 130: Bidirectional converter 135: Power storage device 140: Power storage device controller 145: Fuel cell controller 147: Auxiliary controller 190: Motor control dial 195: Auto idle switch 197: Idling stop switch 200: Fuel cell system

Claims

1. A fuel cell; A power storage device capable of charging and discharging electric power; an electric motor that is driven by power supplied from the fuel cell and the power storage device; A control device for controlling the fuel cell. The control device controls power generation by the fuel cell so that the amount of stored electricity in the electricity storage device is maintained within a predetermined storage range when the work machine is not being operated, and varies the storage range in accordance with the rotation speed of the electric motor. A working machine characterized by:

2. 2. The work machine according to claim 1, the charge range is defined as a charge state between a stop determination value for stopping power generation of the fuel cell and a restart determination value for restarting power generation of the fuel cell, The control device includes: controlling the fuel cell so that, when the amount of stored electricity exceeds the stop determination value, power generation by the fuel cell is stopped until the amount of stored electricity becomes lower than the restart determination value; The stop determination value is increased as the rotation speed of the electric motor decreases. A working machine characterized by:

3. 3. The working machine according to claim 1 or 2, the charge range is defined as a charge state between a stop determination value for stopping power generation of the fuel cell and a restart determination value for restarting power generation of the fuel cell, The control device includes: When the amount of stored electricity falls below the restart determination value, the fuel cell is controlled so as to maintain power generation by the fuel cell until the amount of stored electricity exceeds the stop determination value; The restart determination value is increased as the rotation speed of the motor decreases. A working machine characterized by:

4. 4. The work machine according to claim 3, The control device includes: When a non-operation state of the working machine continues for a predetermined idle determination time or longer, the rotation speed of the electric motor is reduced to a predetermined auto idle rotation speed, When the non-operation state of the work machine continues for a predetermined idling stop determination time or longer, an idling stop control is implemented to stop the electric motor, When the electric motor is stopped by the idling stop control, the restart determination value that has been increased when the rotation speed of the electric motor is reduced to the auto idle rotation speed is decreased. A working machine characterized by:

5. 5. The working machine according to claim 4, The control device shuts down a fuel cell system of the work machine, including the fuel cell, when a non-operation state of the work machine continues for a predetermined time or more after the electric motor is stopped by the idling stop control and when the amount of electricity stored in the electricity storage device is equal to or greater than a predetermined target value. A working machine characterized by:

Images