Pump for fuel battery

Abstract

To provide a pump for a fuel battery to reduce a time required for starting up, while minimizing the waste of power consumption.SOLUTION: A control unit 50 executes normal start-up mode processing when a temperature detected by a temperature sensor 51 is higher than a set temperature that is set in advance, and executes low-temperature start-up mode processing when the temperature detected by the temperature sensor 51 is equal to or less than the set temperature. In the low-temperature start-up mode processing, a start-up current value supplied to a motor 34 is increased compared to when executing the normal start-up mode processing, and a rapid acceleration rotation start-up is executed in which rotation acceleration of the motor 34 is increased compared to when executing the normal start-up mode processing, and the start-up current value supplied to the motor 34 is increased compared to when executing the normal start-up mode processing after executing the rapid acceleration rotation start-up, and a low acceleration rotation start-up is executed in which the rotation acceleration of the motor 34 is decreased compared to when executing the rapid acceleration rotation start-up.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a pump for a fuel cell.

Background Art

[0002] In recent years, vehicles equipped with a fuel cell system including a fuel cell that generates electricity by chemically reacting hydrogen, which is a fuel gas, with oxygen contained in air, which is an oxidant gas, have been put into practical use. The pump for a fuel cell is used, for example, as a pump that supplies hydrogen to the fuel cell. The pump for a fuel cell is disclosed, for example, in Patent Document 1.

[0003] Such a pump for a fuel cell includes a drive shaft and a driven shaft, a motor, a drive gear and a driven gear, a drive rotor and a driven rotor, and a housing. The motor rotates the drive shaft. The drive gear is fixed to the drive shaft. The driven gear is fixed to the driven shaft and meshes with the drive gear. The drive rotor rotates integrally with the drive shaft. The driven rotor rotates integrally with the driven shaft and meshes with the drive rotor. The housing has a gear chamber and a pump chamber. The gear chamber houses the drive gear and the driven gear. Oil is enclosed in the gear chamber. The oil contributes to lubricating the drive gear and the driven gear and suppressing an increase in temperature. The pump chamber houses the drive rotor and the driven rotor. Further, the pump for a fuel cell includes a control unit. The control unit controls the driving of the motor. Then, the hydrogen pump for a fuel cell supplies hydrogen to the fuel cell by the synchronous rotation of the drive rotor and the driven rotor.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in a fuel cell pump, hydrogen off-gas, which is hydrogen that has not reacted with oxygen in the fuel cell, is inhaled into the pump chamber. The hydrogen off-gas contains water generated as the fuel cell generates electricity. Therefore, for example, when the operation of the fuel cell pump is stopped in a low-temperature environment, the water present in the pump chamber freezes and turns into ice. If the water existing between the driving rotor and the driven rotor and the inner surface of the housing partitioning the pump chamber in the pump chamber freezes and turns into ice, the driving rotor and the driven rotor may adhere to the housing via the ice.

[0006] Here, when starting the fuel cell pump, even if the driving rotor and the driven rotor are fixed to the housing via ice, consider that the control unit always supplies the motor with a starting current value that can peel the driving rotor and the driven rotor from the ice existing between the driving rotor and the driven rotor and the inner surface of the housing. In this case, for example, even when the driving rotor and the driven rotor are not fixed to the housing via ice, the control unit supplies the motor with a starting current value that can peel the driving rotor and the driven rotor from the ice existing between the driving rotor and the driven rotor and the inner surface of the housing. Therefore, since an unnecessarily large starting current value will be supplied to the motor, electric power will be wasted.

[0007] Also, when the operation of the fuel cell pump is stopped in a low-temperature environment, the temperature of the oil in the gear chamber becomes low. The higher the viscosity of the oil as the temperature becomes lower. The higher the viscosity of the oil, the more difficult it is for the driving gear and the driven gear to rotate when starting the fuel cell pump, so the time required to start the fuel cell pump becomes longer. Therefore, while suppressing the wasteful consumption of electric power, it is desired to shorten the time required to start the fuel cell pump.

Means for Solving the Problem

[0008] A fuel cell pump for solving the above problems includes a drive shaft and a driven shaft, a motor for rotating the drive shaft, a drive gear fixed to the drive shaft, and a driven gear fixed to the driven shaft and meshing with the drive gear, a drive rotor that rotates integrally with the drive shaft, and a driven rotor that rotates integrally with the driven shaft and meshes with the drive rotor, a housing having a gear chamber that houses the drive gear and the driven gear and is filled with oil, and a pump chamber that houses the drive rotor and the driven rotor, and a control unit for controlling the drive of the motor. The fuel cell pump supplies fuel gas or oxidant gas to a fuel cell by the synchronous rotation of the drive rotor and the driven rotor. A temperature detection unit for detecting temperature is electrically connected to the control unit. When the temperature detected by the temperature detection unit is higher than a preset temperature, the control unit executes normal start-up mode processing. When the temperature detected by the temperature detection unit is equal to or lower than the preset temperature, the control unit executes low-temperature start-up mode processing. In the low-temperature start-up mode processing, a rapid acceleration rotation start is executed, in which the starting current value supplied to the motor is increased and the rotational acceleration of the motor is increased compared to when the normal start-up mode processing is executed. After the rapid acceleration rotation start is executed, a low acceleration rotation start is executed, in which the starting current value supplied to the motor is increased and the rotational acceleration of the motor is decreased compared to when the rapid acceleration rotation start is executed.

[0009] Here, when the temperature detected by the temperature detection unit is higher than the preset set temperature, even if there is water in the pump chamber, it is presumed that the water will not freeze in the pump chamber. Also, when the temperature detected by the temperature detection unit is equal to or lower than the set temperature, if there is water in the pump chamber, it is presumed that the water will freeze in the pump chamber. Further, when the temperature detected by the temperature detection unit is higher than the preset set temperature, it is presumed that the viscosity of the oil in the gear chamber is not high. Also, when the temperature detected by the temperature detection unit is equal to or lower than the set temperature, it is presumed that the viscosity of the oil in the gear chamber is relatively high. These presumptions have been grasped in advance through experiments or the like. Therefore, the "set temperature" is a temperature obtained in advance through experiments or the like in order to determine whether the water freezes in the pump chamber when there is water in the pump chamber, and further to determine whether the viscosity of the oil is relatively high.

[0010] And when the temperature detected by the temperature detection unit is equal to or lower than the set temperature, the control unit executes the low-temperature start mode process. In the low-temperature start mode process, first, an emergency acceleration rotation start is executed in which the starting current value supplied to the motor is made larger than when the normal start mode process is executed, and the rotational acceleration of the motor is made larger than when the normal start mode process is executed. According to this, the drive rotor and the driven rotor start rotating all at once at the commanded rotational speed corresponding to the starting current value. Therefore, for example, when starting the fuel cell pump, even if the drive rotor and the driven rotor are fixed to the housing via ice, it becomes possible to peel the drive rotor and the driven rotor from the ice existing between the drive rotor and the driven rotor and the inner surface of the housing. As a result, when starting the fuel cell pump, the drive rotor and the driven rotor are more likely to rotate.

[0011] Furthermore, in the low-temperature startup mode process, after performing the rapid acceleration rotation startup, a low-acceleration rotation startup is executed in which the startup current value supplied to the motor is made larger than when performing the normal startup mode process, and the rotational acceleration of the motor is made smaller than when performing the rapid acceleration rotation startup. To stir the oil with a relatively high viscosity by the driving gear and the driven gear, it is better to rotate the driving gear and the driven gear so that their rotational speeds gradually approach the commanded rotational speed corresponding to the startup current value, rather than rotating them all at once at the commanded rotational speed corresponding to the startup current value. Therefore, when starting the fuel cell pump, even if the viscosity of the oil is relatively high, the oil in the gear chamber can be efficiently stirred by the driving gear and the driven gear, so that the viscosity of the oil can be reduced. As a result, when starting the fuel cell pump, it becomes easier for the driving gear and the driven gear to rotate.

[0012] On the other hand, when the temperature detected by the temperature detection unit is higher than the set temperature, the control unit executes the normal startup mode process. Therefore, for example, when starting the fuel cell pump, even though the driving rotor and the driven rotor are not fixed to the housing via ice, the startup current value supplied to the motor is not made larger than when performing the normal startup mode process. Also, for example, when starting the fuel cell pump, even though the viscosity of the oil is not high, the startup current value supplied to the motor is not made larger than when performing the normal startup mode process. As a result, supplying an unnecessarily large startup current value to the motor is avoided, so that wasteful consumption of power can be suppressed. As described above, it is possible to shorten the time required to start the fuel cell pump while suppressing wasteful consumption of power.

[0013] In the fuel cell pump, the control unit may repeatedly execute the rapid acceleration rotation startup and the low-acceleration rotation startup in the low-temperature startup mode process. According to this, it becomes easier to peel off the drive rotor and the driven rotor from the ice existing between the drive rotor and the driven rotor and the inner surface of the housing, and the oil in the gear chamber can be more efficiently stirred by the drive gear and the driven gear. Therefore, it is possible to facilitate the start-up of the fuel cell pump.

[0014] In the fuel cell pump, in the low-temperature start-up mode process, the control unit may increase the starting current value supplied to the motor compared to when the normal start-up mode process is executed, in addition to the rapid acceleration rotation start-up and the low acceleration rotation start-up, and execute a reverse rotation start-up for rotating the motor in the reverse direction.

[0015] According to this, by executing the reverse rotation start-up, the drive rotor and the driven rotor rotate in the reverse direction. Therefore, for example, when starting the fuel cell pump, even if the drive rotor and the driven rotor are fixed to the housing via ice, it becomes easier to peel off the drive rotor and the driven rotor from the ice existing between the drive rotor and the driven rotor and the inner surface of the housing. As a result, it is possible to facilitate the start-up of the fuel cell pump.

[0016] In the fuel cell pump, the control unit may execute the reverse rotation start-up after executing the low acceleration rotation start-up. For example, consider the case where the control unit executes the reverse rotation start-up after executing the rapid acceleration rotation start-up. In this case, even if it is not necessary to execute the reverse rotation start-up because the drive rotor and the driven rotor can be peeled off from the ice existing between the drive rotor and the driven rotor and the inner surface of the housing by the rapid acceleration rotation start-up, the control unit will execute the reverse rotation start-up. And the control unit will execute the low acceleration rotation start-up after executing the reverse rotation start-up. Therefore, the control unit is configured to execute the reverse rotation start-up after executing the low acceleration rotation start-up. According to this, it is possible to efficiently start up the fuel cell pump.

Advantages of the Invention

[0017] According to the present invention, it is possible to shorten the time required for starting a fuel cell pump while suppressing wasteful power consumption.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0019] Hereinafter, an embodiment in which a fuel cell pump is embodied will be described with reference to FIGS. 1 to 5. The fuel cell pump of the present embodiment is used as a pump for supplying hydrogen to a fuel cell that generates electricity by chemically reacting hydrogen, which is a fuel gas, and oxygen contained in air, which is an oxidant gas.

[0020] <Overview of the Fuel Cell Pump> As shown in FIG. 1, the fuel cell pump 10 includes a housing 11. The housing 11 is cylindrical. The housing 11 is made of metal. The housing 11 is made of, for example, aluminum. The housing 11 has a motor housing 12, a gear housing 13, a rotor housing 14, and a cover member 15.

[0021] The motor housing 12 has a plate-shaped end wall 12a and a cylindrical peripheral wall 12b. The peripheral wall 12b extends from the outer peripheral portion of the end wall 12a. The motor housing 12 has a cylindrical boss portion 16. The boss portion 16 protrudes from the central portion of the inner surface 12e located on the side of the peripheral wall 12b in the end wall 12a. The axis of the boss portion 16 coincides with the axis of the peripheral wall 12b.

[0022] The gear housing 13 has a plate-shaped end wall 13a and a cylindrical peripheral wall 13b. The peripheral wall 13b extends from the outer peripheral portion of the end wall 13a. The gear housing 13 is connected to the end portion located on the opening side of the peripheral wall 12b of the motor housing 12. The end wall 13a of the gear housing 13 closes the opening of the peripheral wall 12b of the motor housing 12.

[0023] The gear housing 13 has a through hole 17. The through hole 17 is circular. The through hole 17 penetrates the end wall 13a in the thickness direction of the end wall 13a. The axis of the through hole 17 coincides with the axis of the boss portion 16. The gear housing 13 has a recess 18. The recess 18 is formed on the inner surface 13e located on the side of the peripheral wall 13b in the end wall 13a. The recess 18 is circular. The axis of the recess 18 extends parallel to the axis of the through hole 17.

[0024] The rotor housing 14 has a plate-shaped end wall 14a and a cylindrical peripheral wall 14b. The peripheral wall 14b extends from the outer peripheral portion of the end wall 14a. The rotor housing 14 is connected to the end portion located on the opening side of the peripheral wall 13b of the gear housing 13. The end wall 14a of the rotor housing 14 closes the opening of the peripheral wall 13b of the gear housing 13. The axial directions of the peripheral wall 12b of the motor housing 12, the axial direction of the peripheral wall 13b of the gear housing 13, and the axial direction of the peripheral wall 14b of the rotor housing 14 coincide with each other.

[0025] The rotor housing 14 has a through hole 19. The through hole 19 is circular. The through hole 19 penetrates the end wall 14a in the thickness direction of the end wall 14a. The axis of the through hole 19 coincides with the axis of the through hole 17. The rotor housing 14 has a through hole 20. The through hole 20 is circular. The through hole 20 penetrates the end wall 14a in the thickness direction of the end wall 14a. The axis of the through hole 20 coincides with the axis of the recess 18. Therefore, the axis of the through hole 19 extends parallel to the axis of the through hole 20.

[0026] The cover member 15 is plate-shaped. The cover member 15 is connected to an end portion located on the opening side of the peripheral wall 14b of the rotor housing 14. The cover member 15 closes the opening of the peripheral wall 14b while facing the end wall 14a.

[0027] The housing 11 has a motor chamber 21, a gear chamber 22, and a pump chamber 23. The motor chamber 21 is defined by the end wall 12a of the motor housing 12, the peripheral wall 12b of the motor housing 12, and the end wall 13a of the gear housing 13. The gear chamber 22 is defined by the end wall 13a of the gear housing 13, the peripheral wall 13b of the gear housing 13, and the end wall 14a of the rotor housing 14. The pump chamber 23 is defined by the end wall 14a of the rotor housing 14, the peripheral wall 14b of the rotor housing 14, and the cover member 15.

[0028] The fuel cell pump 10 includes a drive shaft 24 and a driven shaft 25. The first end of the drive shaft 24 is disposed inside the boss portion 16. The second end of the drive shaft 24 protrudes into the pump chamber 23 through the motor chamber 21, the through hole 17, the gear chamber 22, and the through hole 19. A bearing 26 is provided between the drive shaft 24 and the inner peripheral surface of the boss portion 16. The drive shaft 24 is rotatably supported by the boss portion 16 via the bearing 26. A bearing 27 is provided between the drive shaft 24 and the inner peripheral surface of the through hole 17. The drive shaft 24 is rotatably supported by the end wall 13a of the gear housing 13 via the bearing 27. A bearing 28 is provided between the drive shaft 24 and the inner peripheral surface of the through hole 19. The drive shaft 24 is rotatably supported by the end wall 14a of the rotor housing 14 via the bearing 28.

[0029] The first end of the driven shaft 25 is disposed inside the recess 18. The second end of the driven shaft 25 protrudes into the pump chamber 23 through the gear chamber 22 and the through hole 20. A bearing 29 is provided between the driven shaft 25 and the inner peripheral surface of the recess 18. The driven shaft 25 is rotatably supported by the end wall 13a of the gear housing 13 via the bearing 29. A bearing 30 is provided between the driven shaft 25 and the through hole 20. The driven shaft 25 is rotatably supported by the end wall 14a of the rotor housing 14 via the bearing 30.

[0030] Thus, the drive shaft 24 and the driven shaft 25 are rotatably supported by the housing 11. The drive shaft 24 and the driven shaft 25 are arranged parallel to each other in the housing 11. The axial directions of the drive shaft 24 and the driven shaft 25 coincide with the axial direction of each of the peripheral walls 12b, 13b, 14b.

[0031] The fuel cell pump 10 includes a seal member 31. The seal member 31 is disposed closer to the motor chamber 21 than the bearing 27 inside the through hole 17. The seal member 31 seals between the drive shaft 24 and the inner peripheral surface of the through hole 17. The fuel cell pump 10 includes a seal member 32. The seal member 32 is disposed closer to the pump chamber 23 than the bearing 28 inside the through hole 19. The seal member 32 seals between the drive shaft 24 and the inner peripheral surface of the through hole 19. The fuel cell pump 10 includes a seal member 33. The seal member 33 is disposed closer to the pump chamber 23 than the bearing 30 inside the through hole 20. The seal member 33 seals between the driven shaft 25 and the inner peripheral surface of the through hole 20.

[0032] The fuel cell pump 10 includes a motor 34. The motor 34 is housed in the motor chamber 21. Accordingly, the motor chamber 21 houses the motor 34. The motor 34 has a motor rotor 35 and a motor stator 36. The motor rotor 35 is cylindrical. The motor rotor 35 is fixed to the drive shaft 24. The motor rotor 35 is configured to be rotatable integrally with the drive shaft 24. The motor stator 36 is cylindrical. The motor stator 36 is fixed to the inner peripheral surface of the peripheral wall 12b of the motor housing 12. The motor stator 36 surrounds the motor rotor 35. The motor stator 36 has a motor coil 37. And the motor 34 is driven when electric power is supplied to the motor coil 37. When the motor 34 is driven, the motor rotor 35 rotates integrally with the drive shaft 24. In this way, the motor 34 rotates the drive shaft 24.

[0033] The fuel cell pump 10 includes a drive gear 38 and a driven gear 39. The drive gear 38 and the driven gear 39 are housed in the gear chamber 22. Accordingly, the gear chamber 22 houses the drive gear 38 and the driven gear 39. The drive gear 38 is disc-shaped. The drive gear 38 is fixed to the drive shaft 24. The driven gear 39 is disc-shaped. The driven gear 39 is fixed to the driven shaft 25. The driven gear 39 meshes with the drive gear 38.

[0034] The drive gear 38 and the driven gear 39 are accommodated in the gear chamber 22 in a meshed state with each other. Note that oil is enclosed in the gear chamber 22. The oil contributes to lubricating the drive gear 38 and the driven gear 39 and suppressing the rise in temperature. The drive gear 38 and the driven gear 39 can rotate at high speed without seizure or wear by rotating while immersed in the oil.

[0035] The fuel cell pump 10 includes a drive rotor 40 and a driven rotor 41. The drive rotor 40 and the driven rotor 41 are accommodated in the pump chamber 23. Therefore, the pump chamber 23 accommodates the drive rotor 40 and the driven rotor 41. The drive rotor 40 is provided at the second end of the drive shaft 24. Therefore, the drive shaft 24 is cantilever-supported by the housing 11. The drive rotor 40 rotates integrally with the drive shaft 24. The driven rotor 41 is provided at the second end of the driven shaft 25. Therefore, the driven shaft 25 is cantilever-supported by the housing 11. The driven rotor 41 rotates integrally with the driven shaft 25. The driven rotor 41 meshes with the drive rotor 40. Therefore, the drive rotor 40 and the driven rotor 41 are accommodated in the pump chamber 23 in a meshed state with each other.

[0036] As shown in FIG. 2, the drive rotor 40 and the driven rotor 41 are formed in a two-lobe shape (ladle shape) in a cross-sectional view perpendicular to the axial direction of the drive shaft 24 and the driven shaft 25. The drive rotor 40 has two ridge teeth 40a and a valley tooth 40b formed between both ridge teeth 40a. The driven rotor 41 has two ridge teeth 41a and a valley tooth 41b formed between both ridge teeth 41a.

[0037] Then, the drive rotor 40 and the driven rotor 41 can rotate in the pump chamber 23 while repeating the meshing of the ridge teeth 40a of the drive rotor 40 and the valley teeth 41b of the driven rotor 41 and the meshing of the valley teeth 40b of the drive rotor 40 and the ridge teeth 41a of the driven rotor 41. The drive rotor 40 rotates in the direction of arrow R1 shown in FIG. 2, and the driven rotor 41 rotates in the direction of arrow R2 shown in FIG. 2.

[0038] At the lower part of the circumferential wall 14b of the rotor housing 14 in the gravity direction Z1, a suction port 42 is formed. Also, at the upper part of the circumferential wall 14b of the rotor housing 14 in the gravity direction Z1, a discharge port 43 is formed. The suction port 42 is connected to the hydrogen discharge port 45a of the fuel cell 45 via the first connection pipe 44. The discharge port 43 is connected to the hydrogen supply port 45b of the fuel cell 45 via the second connection pipe 46.

[0039] As shown in FIGS. 1 and 2, when the drive shaft 24 rotates by the drive of the motor 34, the driven shaft 25 rotates in the reverse direction with respect to the drive shaft 24 via the gear connection of the drive gear 38 and the driven gear 39 that mesh with each other. As a result, the drive rotor 40 and the driven rotor 41 rotate in the reverse direction while meshing with each other. In this way, the drive rotor 40 and the driven rotor 41 rotate synchronously.

[0040] In the fuel cell pump 10, when the drive rotor 40 and the driven rotor 41 rotate synchronously, the hydrogen off-gas, which is the hydrogen that did not react with oxygen in the fuel cell 45, is inhaled into the pump chamber 23 via the hydrogen discharge port 45a, the first connection pipe 44, and the suction port 42. Then, the hydrogen off-gas inhaled into the pump chamber 23 is discharged from the discharge port 43 and supplied to the fuel cell 45 via the second connection pipe 46 and the hydrogen supply port 45b by the synchronous rotation of the drive rotor 40 and the driven rotor 41. In this way, the fuel cell pump 10 supplies hydrogen to the fuel cell 45 when the drive rotor 40 and the driven rotor 41 rotate synchronously. The fuel cell pump 10 of the present embodiment is a roots pump provided with the drive rotor 40 and the driven rotor 41.

[0041] <Control Unit> As shown in FIG. 1, the fuel cell pump 10 includes a control unit 50. The control unit 50 controls the driving of the motor 34. The control unit 50 is an inverter device. The fuel cell pump 10 includes a cover 47. The cover 47 is attached to the end wall 12a of the motor housing 12. And an inverter chamber 48 is defined by the end wall 12a of the motor housing 12 and the cover 47. The inverter chamber 48 houses the control unit 50. In the present embodiment, the pump chamber 23, the gear chamber 22, the motor chamber 21, and the inverter chamber 48 are arranged in this order in the axial direction of the drive shaft 24 and the driven shaft 25.

[0042] The fuel cell pump 10 includes a temperature sensor 51 as a temperature detection unit that detects temperature. The temperature sensor 51 is electrically connected to the control unit 50. Therefore, the control unit 50 is electrically connected to the temperature sensor 51 that detects temperature. The temperature sensor 51 is configured to be able to detect the temperature of the housing 11, for example. The temperature of the housing 11 is a temperature related to the temperature in the pump chamber 23 and the temperature in the gear chamber 22. The control unit 50 receives a signal regarding the temperature T1 detected by the temperature sensor 51. The control unit 50 stores in advance a temperature comparison program that compares the temperature T1 detected by the temperature sensor 51 with a preset set temperature T2 based on the signal received from the temperature sensor 51. The control unit 50 stores in advance a processing execution program. In the processing execution program, when the temperature T1 detected by the temperature sensor 51 is higher than the set temperature T2, normal startup mode processing is executed. Also, in the processing execution program, when the temperature T1 detected by the temperature sensor 51 is less than or equal to the set temperature T2, low-temperature startup mode processing is executed. Therefore, the control unit 50 executes normal startup mode processing when the temperature T1 detected by the temperature sensor 51 is higher than the set temperature T2, and executes low-temperature startup mode processing when the temperature T1 detected by the temperature sensor 51 is less than or equal to the set temperature T2.

[0043] Here, when the temperature T1 detected by the temperature sensor 51 is higher than the set temperature T2, it is presumed that even if there is water in the pump chamber 23, the water will not freeze in the pump chamber 23. Also, when the temperature T1 detected by the temperature sensor 51 is equal to or lower than the set temperature T2, if there is water in the pump chamber 23, it is presumed that the water will freeze in the pump chamber 23. Further, when the temperature T1 detected by the temperature sensor 51 is higher than the set temperature T2, it is presumed that the viscosity of the oil in the gear chamber 22 is not high. Also, when the temperature T1 detected by the temperature sensor 51 is equal to or lower than the set temperature T2, it is presumed that the viscosity of the oil in the gear chamber 22 is relatively high. These presumptions are grasped in advance by experiments or the like. Therefore, the "set temperature T2" is a temperature obtained in advance by experiments or the like in order to determine whether the water freezes in the pump chamber 23 when there is water in the pump chamber 23, and further to determine whether the viscosity of the oil is relatively high.

[0044] <Normal startup mode process> When the control unit 50 executes the normal startup mode process, a program for supplying the startup current, which is the minimum startup current value required to start the fuel cell pump 10, to the motor 34 for the minimum required time is stored in advance. Note that the cycle of the startup current during the execution of the normal startup mode process is always set to be constant.

[0045] <Low-temperature startup mode process> In the low-temperature startup mode process, the control unit 50 stores in advance a program for executing a rapid acceleration rotation startup and, after executing the rapid acceleration rotation startup, executing a low acceleration rotation startup. In the rapid acceleration rotation startup, the startup current value supplied to the motor 34 is made larger than that during the execution of the normal startup mode process, and the rotational acceleration of the motor 34 is made larger than that during the execution of the normal startup mode process. In the low acceleration rotation startup, the startup current value supplied to the motor 34 is made larger than that during the execution of the normal startup mode process, and the rotational acceleration of the motor 34 is made smaller than that during the execution of the rapid acceleration rotation startup. Note that the rotational acceleration of the motor 34 is the amount of change in the rotational speed of the motor 34 per unit time.

[0046] In the control unit 50, in the low-temperature start-up mode process, in addition to the rapid acceleration rotation start-up and the low acceleration rotation start-up, a program for executing reverse rotation start-up is stored in advance. Therefore, in the low-temperature start-up mode process, the control unit 50 executes reverse rotation start-up in addition to the rapid acceleration rotation start-up and the low acceleration rotation start-up. In the reverse rotation start-up, the starting current value supplied to the motor 34 is made larger than when the normal start-up mode process is executed, and the motor 34 is rotated in the reverse direction.

[0047] In the control unit 50, a program for executing reverse rotation start-up after executing low acceleration rotation start-up is stored in advance. Therefore, the control unit 50 executes reverse rotation start-up after executing low acceleration rotation start-up. Also, in the control unit 50, in the low-temperature start-up mode process, a program for repeatedly executing rapid acceleration rotation start-up, low acceleration rotation start-up, and reverse rotation start-up in this order is stored in advance. Therefore, in the low-temperature start-up mode process, the control unit 50 repeatedly executes rapid acceleration rotation start-up and low acceleration rotation start-up.

[0048] FIG. 3 shows an example of a current waveform when the fuel cell pump 10 is started by executing the low-temperature start-up mode process. As shown in FIG. 3, in the rapid acceleration rotation start-up, the period of the starting current supplied to the motor 34 is set to be a constant period from the start of execution of the rapid acceleration rotation start-up. The period of the starting current supplied to the motor 34 during the execution of the rapid acceleration rotation start-up is set to be shorter than the period of the starting current supplied to the motor 34 during the execution of the normal start-up mode process.

[0049] On the other hand, in the low acceleration rotation start-up, the period of the starting current supplied to the motor 34 is set to gradually become shorter from the start of execution of the low acceleration rotation start-up. Note that the period of the starting current supplied to the motor 34 during the execution of the low acceleration rotation start-up is set to be shorter than the period of the starting current supplied to the motor 34 during the execution of the normal start-up mode process.

[0050] Furthermore, in reverse rotation startup, the period of the startup current supplied to the motor 34 is set to be a constant period from the start of execution of the reverse rotation startup. Note that the way of flowing current to the motor 34 during execution of the reverse rotation startup is opposite to the way of flowing current to the motor 34 during execution of the rapid acceleration rotation startup. The period of the startup current supplied to the motor 34 during execution of the reverse rotation startup is almost the same as the period of the startup current supplied to the motor 34 during execution of the rapid acceleration rotation startup.

[0051] Figure 4 shows the displacement of the rotational speed of the motor 34 in the low-temperature startup mode process. As shown in Figure 4, the slope of the solid line indicating the displacement of the rotational speed of the motor 34 during execution of the low acceleration rotation startup is gentler than the slope of the solid line indicating the displacement of the rotational speed of the motor 34 during execution of the rapid acceleration rotation startup. Therefore, the amount of change in the rotational speed of the motor 34 per unit time during execution of the low acceleration rotation startup is smaller than the amount of change in the rotational speed of the motor 34 per unit time during execution of the rapid acceleration rotation startup. Therefore, in the low acceleration rotation startup, the rotational acceleration of the motor 34 is smaller than that during execution of the rapid acceleration rotation startup.

[0052] The slope of the solid line indicating the displacement of the rotational speed of the motor 34 during execution of the reverse rotation startup is almost the same as the slope of the solid line indicating the displacement of the rotational speed of the motor 34 during execution of the rapid acceleration rotation startup. Therefore, the amount of displacement of the rotational speed of the motor 34 per unit time during execution of the reverse rotation startup is almost the same as the amount of displacement of the rotational speed of the motor 34 per unit time during execution of the rapid acceleration rotation startup. Therefore, the rotational acceleration of the motor 34 during execution of the reverse rotation startup is almost the same as the rotational acceleration of the motor 34 during execution of the rapid acceleration rotation startup. Therefore, the rotational acceleration of the motor 34 during execution of the low acceleration rotation startup is smaller than the rotational acceleration of the motor 34 during execution of the reverse rotation startup.

[0053] Note that when the control unit 50 executes the low-temperature start-up mode process, for example, when executing the normal start-up mode process, it supplies a starting current value approximately twice the starting current value supplied to the motor 34 to the motor 34. The starting current values supplied to the motor 34 during the execution of each of the rapid acceleration rotation start-up, low acceleration rotation start-up, and reverse rotation start-up are the same. In the rapid acceleration rotation start-up, the rotational acceleration of the motor 34 is made larger than when executing the normal start-up mode process.

[0054] <Vector control mode process> The control unit 50 stores in advance a program for determining whether or not the rotational speed of the motor 34 has reached the target rotational speed. Specifically, the control unit 50 determines whether or not the rotational speed of the motor 34 has reached the target rotational speed by determining whether or not the current value supplied to the motor 34 has reached the current value corresponding to the target rotational speed of the motor 34.

[0055] When the control unit 50 is executing the low-temperature start-up mode process, after executing the rapid acceleration rotation start-up and the low acceleration rotation start-up, it determines whether or not the rotational speed of the motor 34 has reached the target rotational speed. When the control unit 50 determines that the rotational speed of the motor 34 has reached the target rotational speed, it determines that the fuel cell pump 10 has started to operate. On the other hand, when the control unit 50 determines that the rotational speed of the motor 34 has not reached the target rotational speed, it determines that the fuel cell pump 10 is stopped. Here, the "state where the fuel cell pump 10 is stopped" means the "state where the drive rotor 40 and the driven rotor 41 are not rotating". Also, the "state where the fuel cell pump 10 has started to operate" means the "state where the drive rotor 40 and the driven rotor 41 have started to rotate". And the control unit 50 stores in advance a program for executing a vector control process for sensorless vector control of the motor 34 when it determines that the fuel cell pump 10 has started to operate.

[0056] <Abnormality determination process> The control unit 50 stores in advance a program for executing an abnormality determination process for determining that some abnormality has occurred when it determines that the rotational speed of the motor 34 has not reached the target rotational speed after executing the normal start-up mode process.

[0057] [Operation of the Embodiment] Next, the operation of this embodiment will be described. As shown in FIG. 5, when the control unit 50 attempts to start the fuel cell pump 10, first, in step S11, it receives a signal regarding the temperature T1 detected by the temperature sensor 51. Then, in step S12, the control unit 50 compares the temperature T1 detected by the temperature sensor 51 with a preset set temperature T2 based on the signal received from the temperature sensor 51.

[0058] In the comparison result obtained in step S12, when the temperature T1 detected by the temperature sensor 51 is higher than the set temperature T2, the control unit 50 proceeds to step S13 and, in step S13, executes normal start-up mode processing. As a result, the control unit 50 supplies the starting current, which is the minimum required starting current value for starting the fuel cell pump 10, to the motor 34 for the minimum required time. The period of the starting current at this time is always a constant period.

[0059] In step S14, the control unit 50 determines whether the rotational speed of the motor 34 has reached the target rotational speed. If the control unit 50 determines in step S14 that the rotational speed of the motor 34 has reached the target rotational speed, it proceeds to the normal control in step S15. Then, when the control unit 50 determines that the fuel cell pump 10 has started to operate, in step S15, it executes vector control mode processing for sensorless vector control of the motor 34.

[0060] On the other hand, if the control unit 50 determines in step S14 that the rotational speed of the motor 34 has not reached the target rotational speed, it proceeds to step S16, determines that some abnormality has been detected, and performs abnormality determination processing.

[0061] Incidentally, in the fuel cell pump 10, the hydrogen off-gas that did not react with oxygen in the fuel cell 45 is inhaled into the pump chamber 23. The hydrogen off-gas contains water generated along with the power generation of the fuel cell 45. For this reason, for example, when the operation of the fuel cell pump 10 is stopped in a low-temperature environment, the water present in the pump chamber 23 freezes into ice. In the pump chamber 23, if the water existing between the driving rotor 40 and the driven rotor 41 and the inner surface of the rotor housing 14 partitioning the pump chamber 23 freezes into ice, the driving rotor 40 and the driven rotor 41 may adhere to the rotor housing 14 via the ice. Also, when the operation of the fuel cell pump 10 is stopped in a low-temperature environment, the temperature of the oil in the gear chamber 22 decreases. The higher the viscosity of the oil, the more difficult it is for the driving gear 38 and the driven gear 39 to rotate when starting the fuel cell pump 10.

[0062] In the comparison result obtained in step S12, when the temperature T1 detected by the temperature sensor 51 is equal to or lower than the set temperature T2, the control unit 50 proceeds to step S17 and, in step S17, executes the low-temperature start mode process. In the low-temperature start mode process, first, a rapid acceleration rotation start is executed. According to this, the driving rotor 40 and the driven rotor 41 start rotating all at once at a command rotational speed corresponding to the starting current value. Therefore, for example, even if the driving rotor 40 and the driven rotor 41 are fixed to the rotor housing 14 via ice when starting the fuel cell pump 10, it is possible to peel the driving rotor 40 and the driven rotor 41 from the ice existing between the driving rotor 40 and the driven rotor 41 and the inner surface of the rotor housing 14.

[0063] Furthermore, in the low-temperature start-up mode process, after performing a rapid acceleration rotation start-up, a low acceleration rotation start-up is executed. To stir the oil with a relatively high viscosity using the drive gear 38 and the driven gear 39, it is better to rotate the drive gear 38 and the driven gear 39 so that their rotational speeds gradually approach the commanded rotational speed corresponding to the starting current value, rather than rotating them all at once at the commanded rotational speed corresponding to the starting current value. Therefore, when starting the fuel cell pump 10, even if the viscosity of the oil is relatively high, the oil in the gear chamber 22 is efficiently stirred by the drive gear 38 and the driven gear 39, so that the viscosity of the oil decreases.

[0064] In step S17, when the rapid acceleration rotation start-up and the low acceleration rotation start-up are completed in the first low-temperature start-up mode process, the control unit 50 proceeds to step S18, and in step S18, it determines whether the rotational speed of the motor 34 has reached the target rotational speed. If the control unit 50 determines in step S18 that the rotational speed of the motor 34 has not reached the target rotational speed, it proceeds to step S17 and executes the reverse rotation start-up of the first low-temperature start-up mode process. According to this, the drive rotor 40 and the driven rotor 41 rotate in the reverse direction. Therefore, for example, when starting the fuel cell pump 10, even if the drive rotor 40 and the driven rotor 41 were fixed to the rotor housing 14 via ice, it becomes easier to peel the drive rotor 40 and the driven rotor 41 from the ice existing between the drive rotor 40 and the driven rotor 41 and the inner surface of the rotor housing 14.

[0065] Furthermore, the control unit 50 executes the rapid acceleration rotation start-up and the low acceleration rotation start-up of the second low-temperature start-up mode process again. In this way, even if the control unit 50 executes the low-temperature start-up mode process, if the rotational speed of the motor 34 has not reached the target rotational speed, it determines that the fuel cell pump 10 has not yet started, and executes the low-temperature start-up mode process again.

[0066] On the other hand, when the control unit 50 determines in step S18 that the rotational speed of the motor 34 has reached the target rotational speed, it shifts to the normal control in step S15. Then, when it is determined that the fuel cell pump 10 has started to operate, in step S15, a vector control mode process for performing sensorless vector control of the motor 34 is executed.

[0067] [Effects of the Embodiment] In the above embodiment, the following effects can be obtained. (1) When the temperature T1 detected by the temperature sensor 51 is equal to or lower than the set temperature T2, the control unit 50 executes the low-temperature start mode process. In the low-temperature start mode process, first, a rapid acceleration rotation start is executed in which the starting current value supplied to the motor 34 is made larger than when the normal start mode process is executed, and the rotational acceleration of the motor 34 is made larger than when the normal start mode process is executed. According to this, the drive rotor 40 and the driven rotor 41 start rotating all at once at the commanded rotational speed corresponding to the starting current value. Therefore, for example, when starting the fuel cell pump 10, even if the drive rotor 40 and the driven rotor 41 are fixed to the rotor housing 14 via ice, it is possible to peel the drive rotor 40 and the driven rotor 41 from the ice existing between the drive rotor 40 and the driven rotor 41 and the inner surface of the rotor housing 14. As a result, when starting the fuel cell pump 10, the drive rotor 40 and the driven rotor 41 become easier to rotate.

[0068] Furthermore, in the low-temperature startup mode process, after performing a rapid acceleration rotation startup, a low-acceleration rotation startup is executed, in which the startup current value supplied to the motor 34 is made larger than when performing the normal startup mode process, and the rotational acceleration of the motor 34 is made smaller than when performing the rapid acceleration rotation startup. To stir the oil with a relatively high viscosity by the driving gear 38 and the driven gear 39, it is better to rotate the driving gear 38 and the driven gear 39 so that their rotational speeds gradually approach the commanded rotational speed corresponding to the startup current value, rather than rotating the driving gear 38 and the driven gear 39 at once at the commanded rotational speed corresponding to the startup current value. Therefore, when starting the fuel cell pump 10, even if the viscosity of the oil is relatively high, the oil in the gear chamber 22 can be efficiently stirred by the driving gear 38 and the driven gear 39, so that the viscosity of the oil can be lowered. As a result, when starting the fuel cell pump 10, the driving gear 38 and the driven gear 39 become easier to rotate.

[0069] On the other hand, when the temperature T1 detected by the temperature sensor 51 is higher than the set temperature T2, the control unit 50 executes the normal startup mode process. Therefore, for example, when starting the fuel cell pump 10, even though the driving rotor 40 and the driven rotor 41 are not fixed to the rotor housing 14 via ice, the startup current value supplied to the motor 34 is not made larger than when performing the normal startup mode process. Also, for example, when starting the fuel cell pump 10, even though the viscosity of the oil is not high, the startup current value supplied to the motor 34 is not made larger than when performing the normal startup mode process. As a result, supplying an unnecessarily large startup current value to the motor 34 is avoided, so that wasteful consumption of power can be suppressed. As described above, it is possible to shorten the time required to start the fuel cell pump 10 while suppressing wasteful consumption of power.

[0070] (2) In the low-temperature startup mode process, the control unit 50 repeatedly executes rapid acceleration rotation startup and low acceleration rotation startup. According to this, it becomes easier to peel off the drive rotor 40 and the driven rotor 41 from the ice existing between the drive rotor 40 and the driven rotor 41 and the inner surface of the rotor housing 14, and the oil in the gear chamber 22 can be more efficiently stirred by the drive gear 38 and the driven gear 39. Therefore, it becomes easier to start the fuel cell pump 10.

[0071] (3) In the low-temperature startup mode process, the control unit 50, in addition to rapid acceleration rotation startup and low acceleration rotation startup, increases the startup current value supplied to the motor 34 compared to when executing the normal startup mode process, and executes reverse rotation startup for rotating the motor 34 in the reverse direction. According to this, by executing reverse rotation startup, the drive rotor 40 and the driven rotor 41 rotate in the reverse direction. Therefore, for example, when starting the fuel cell pump 10, even if the drive rotor 40 and the driven rotor 41 are fixed to the rotor housing 14 via ice, it becomes easier to peel off the drive rotor 40 and the driven rotor 41 from the ice existing between the drive rotor 40 and the driven rotor 41 and the inner surface of the rotor housing 14. As a result, it becomes easier to start the fuel cell pump 10.

[0072] (4) For example, consider the case where the control unit 50 executes reverse rotation startup after executing rapid acceleration rotation startup. In this case, rapid acceleration rotation startup can peel off the drive rotor 40 and the driven rotor 41 from the ice existing between the drive rotor 40 and the driven rotor 41 and the inner surface of the rotor housing 14. Even if there is no need to execute reverse rotation startup, the control unit 50 will execute reverse rotation startup. Then, the control unit 50 will execute low acceleration rotation startup after executing reverse rotation startup. Therefore, the control unit 50 is configured to execute reverse rotation startup after executing low acceleration rotation startup. According to this, the fuel cell pump 10 can be efficiently started.

[0073] (5) By performing reverse rotation startup in the low-temperature startup mode process, the drive gear 38 and the driven gear 39 also rotate in reverse, so that the oil in the gear chamber 22 can be stirred by the drive gear 38 and the driven gear 39. Therefore, by performing reverse rotation startup, the oil in the gear chamber 22 can be stirred more efficiently by the drive gear 38 and the driven gear 39, so that the fuel cell pump 10 can be made easier to start up.

[0074] (6) The heat of the motor 34 generated by performing rapid acceleration rotation startup and low acceleration rotation startup in the low-temperature startup mode process is transmitted to the drive gear 38 and the driven gear 39, and the drive rotor 40 and the driven rotor 41. Therefore, since the temperature in the gear chamber 22 and the temperature in the pump chamber 23 can be increased, the temperature of the oil can be increased and the ice existing in the pump chamber 23 can be melted. As a result, the fuel cell pump 10 can be started up efficiently.

[0075] [Modification example] Note that the above embodiment can be implemented with the following modifications. The above embodiment and the following modification examples can be implemented in combination with each other as long as they do not technically conflict with each other.

[0076] ○ In the embodiment, the control unit 50 does not have to repeatedly execute rapid acceleration rotation startup and low acceleration rotation startup in the low-temperature startup mode process. ○ In the embodiment, the control unit 50 does not have to execute reverse rotation startup in the low-temperature startup mode process.

[0077] ○ In the embodiment, the control unit 50 may execute reverse rotation startup after executing rapid acceleration rotation startup. ○ In an embodiment, the temperature sensor 51 may be configured to be able to detect, for example, the temperature inside the pump chamber 23, or may be configured to be able to detect, for example, the temperature inside the gear chamber 22. Further, the temperature sensor 51 may be configured to be able to detect, for example, the outside air temperature. In short, the temperature detected by the temperature sensor 51 may be a temperature related to the temperature inside the pump chamber 23 or the temperature inside the gear chamber 22.

[0078] ○ In an embodiment, the temperature sensor 51 may be provided in the housing 11 that partitions the pump chamber 23, and the temperature inside the pump chamber 23 may be estimated based on the temperature detected by the temperature sensor 51. The temperature sensor 51 may be provided in the housing 11 that partitions the gear chamber 22, and the temperature inside the gear chamber 22 may be estimated based on the temperature detected by the temperature sensor 51.

[0079] ○ In an embodiment, the fuel cell pump 10 may include a pressure sensor. The pressure sensor detects the pressure of hydrogen discharged from the pump chamber 23 to the second connection pipe 46 through the discharge port 43 due to the rotation of the drive rotor 40 and the driven rotor 41. Then, when the control unit 50 receives a detection signal of the discharge pressure from the pressure sensor, it may determine that the fuel cell pump 10 is operating, and when it does not receive a detection signal of the discharge pressure from the pressure sensor, it may determine that the fuel cell pump 10 is stopped.

[0080] ○ In an embodiment, when the control unit 50 executes the low-temperature start mode process, for example, it may supply a starting current value approximately three times the starting current value supplied to the motor 34 during the execution of the normal start mode process to the motor 34. In short, in rapid acceleration rotation start, it is sufficient that the starting current value supplied to the motor 34 is larger than that during the execution of the normal start mode process, and in low acceleration rotation start, it is sufficient that the starting current value supplied to the motor 34 is larger than that during the execution of the normal start mode process. Further, in reverse rotation start, it is sufficient that the starting current value supplied to the motor 34 is larger than that during the execution of the normal start mode process.

[0081] ○ In the embodiment, in the low-temperature start mode process after the second time, at the timing when the rapid acceleration rotation start is executed, the process may proceed to step S18, and in step S18, it may be determined whether the rotational speed of the motor 34 has reached the target rotational speed. In short, in the low-temperature start mode process, after executing the rapid acceleration rotation start, it is sufficient that the process of executing the low acceleration rotation start is performed at least once.

[0082] ○ In the embodiment, steps S14 and S18 may be omitted. That is, in FIG. 5, in the case of step S13, if it is not possible to proceed from step S13 to step S15, a retry may be performed. Also, in FIG. 5, in the case of step S17, if it is not possible to proceed from step S17 to step S15, a retry may be performed.

[0083] ○ In the embodiment, the starting current values supplied to the motor 34 during the execution of the rapid acceleration rotation start, the low acceleration rotation start, and the reverse rotation start may be different. In short, the starting current values supplied to the motor 34 during the execution of the rapid acceleration rotation start, the low acceleration rotation start, and the reverse rotation start may be larger than the starting current value supplied to the motor 34 during the execution of the normal start mode process.

[0084] ○ In the embodiment, the cross-sectional view of the drive rotor 40 and the driven rotor 41 perpendicular to the rotational axis direction of the drive shaft 24 and the driven shaft 25 may be, for example, a three-lobed shape or a four-lobed shape.

[0085] ○ In the embodiment, the drive rotor 40 and the driven rotor 41 may be, for example, in a helical shape. ○ In the embodiment, the fuel cell pump 10 is a pump that supplies hydrogen to a fuel cell that generates electricity by chemically reacting hydrogen, which is a fuel gas, with oxygen contained in air, which is an oxidant gas, but it may also be a pump that supplies air to the fuel cell.

Description of Reference Numerals

[0086] 10…Fuel cell pump, 11…Housing, 22…Gear chamber, 23…Pump chamber, 24…Drive shaft, 25…Driven shaft, 34…Motor, 38…Drive gear, 39…Driven gear, 40…Drive rotor, 41…Driven rotor, 45…Fuel cell, 50…Control unit, 51…Temperature sensor as temperature detection unit, T1…Temperature, T2…Set temperature.

Claims

1. A drive shaft and a driven shaft, a motor for rotating the drive shaft, a drive gear fixed to the drive shaft, and a driven gear fixed to the driven shaft and meshing with the drive gear, a drive rotor that rotates integrally with the drive shaft, and a driven rotor that rotates integrally with the driven shaft and meshes with the drive rotor, a housing having a gear chamber that houses the drive gear and the driven gear and is filled with oil, and a pump chamber that houses the drive rotor and the driven rotor, a control unit for controlling the drive of the motor, a fuel cell pump that supplies fuel gas or oxidant gas to a fuel cell by the synchronous rotation of the drive rotor and the driven rotor, a temperature detection unit for detecting temperature is electrically connected to the control unit, when the temperature detected by the temperature detection unit is higher than a preset temperature, the control unit executes normal start-up mode processing, and when the temperature detected by the temperature detection unit is equal to or lower than the preset temperature, the control unit executes low-temperature start-up mode processing, in the low-temperature start-up mode processing, a rapid acceleration rotation start-up is executed in which the starting current value supplied to the motor is increased and the rotational acceleration of the motor is increased compared to when the normal start-up mode processing is executed, and after the rapid acceleration rotation start-up is executed, a low acceleration rotation start-up is executed in which the starting current value supplied to the motor is increased and the rotational acceleration of the motor is decreased compared to when the rapid acceleration rotation start-up is executed. A fuel cell pump characterized by that.

2. The control unit repeatedly executes the rapid acceleration rotation start-up and the low acceleration rotation start-up in the low-temperature start-up mode processing. The fuel cell pump according to Claim 1.

3. In the low-temperature start-up mode processing, the control unit increases the starting current value supplied to the motor compared to when the normal start-up mode processing is executed, and executes a reverse rotation start-up for rotating the motor in reverse, in addition to the rapid acceleration rotation start-up and the low acceleration rotation start-up. The fuel cell pump according to Claim 1 or Claim 2.

4. The control unit executes the reverse rotation start-up after executing the low acceleration rotation start-up. The fuel cell pump according to Claim 3.

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