JP2010168904A - Air supply device for fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air supply device for a fuel cell, in which radial foil bearings for supporting the rotating shaft of an electric motor are hardly worn. <P>SOLUTION: This air supply device 6 for a fuel cell includes a centrifugal compressor 15 which is connected to one end of a rotating shaft 10 and operated by the rotation of the electric motor 13, an air supply passage 35 which sucks air from the outside by the operation of the centrifugal compressor 15, compresses the air by the centrifugal compressor 15, and supplies the air to a fuel cell stack, a valve 39 provided midway to the air supply passage 35, and a control unit 40 for regulating the quantity of the air by suppressing the rotational speed of the electric motor 13. The control unit 40 includes a valve control unit 41 for regulating the quantity of air by controlling the valve 39 while maintaining the rotational speed of the electric motor at which the rotating shaft 10 is floated by the dynamic pressure of the air in the radial foil bearings 31, 32. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an air supply device for a fuel cell that compresses and supplies air containing oxygen for reacting with hydrogen or the like to generate electric power in a fuel cell such as a fuel cell vehicle.

  2. Description of the Related Art Recently, fuel cells such as hydrogen and alcohol do not burn, but generate electric power by electrochemically reacting with oxygen in the air in a fuel cell, and a fuel cell vehicle that runs by rotating an electric motor with the generated electric power. Development is progressing. In order to supply air to the fuel cell, an electric motor, a centrifugal compressor connected to one end of a rotating shaft of the electric motor and operated by rotation of the electric motor, and air from the outside by operation of the centrifugal compressor A fuel cell air supply device is used that includes an air supply passage that sucks the air and compresses the air with a centrifugal compressor and supplies the compressed air to the fuel cell stack.

In the fuel cell air supply device, since it is necessary to supply air to the fuel cell in a sufficiently compressed state, the impeller of the centrifugal compressor must be rotated at a high speed of about several tens of thousands of revolutions. For this reason, the rotating shaft of the electric motor may be supported in a non-contact state during high-speed rotation by using a foil bearing or a magnetic bearing instead of a normal rolling bearing.
For example, the rotating shaft is supported from the radial direction by a pair of radial foil bearings provided on both sides in the axial direction of the rotating shaft across the rotor of the electric motor, and from the axial direction by a pair of axial magnetic bearings provided in the same region. Support is performed (see, for example, Patent Document 1).

JP 2007-192115 A

  A radial foil bearing has one or two or more foil segments made of a very thin metal foil attached to the inner surface of a through-hole formed on a rotating shaft having a diameter larger than the portion supported by the radial foil bearing. Composed. According to the radial foil bearing, until the rotational speed of the rotating shaft to support reaches a predetermined value, the foil segment directly contacts the outer peripheral surface of the rotating shaft to support the rotating shaft from the radial direction. After reaching the predetermined value, the rotary shaft is lifted from the surface of the foil segment over the entire circumference by the dynamic pressure generated between the outer peripheral surface of the rotary shaft and the foil segment. Can support.

  However, in particular, the centrifugal compressor for a fuel cell vehicle is often controlled in a wide range from a low speed to a high speed according to the traveling state of the fuel cell vehicle. Therefore, particularly when the foil segment is controlled so that the rotation (low-speed rotation) continues for a long time in a state where the foil segment directly contacts the outer peripheral surface of the rotating shaft and supports the rotating shaft from the radial direction, There is a problem that the characteristics for levitation of the rotary shaft in the radial foil bearing are likely to be deteriorated or lost as the wear amount is increased in a short period of time.

  An object of the present invention is to provide an air supply device for a fuel cell that hardly causes wear in a radial foil bearing.

  In order to achieve the above object, the present invention is connected to an electric motor (13) including a rotary shaft (10), a rotor (11) and a stator (12), and one end of the rotary shaft of the electric motor. A centrifugal compressor (15) that is operated by rotation, a pair of radial foil bearings (31, 32) that support the rotating shaft by floating by a dynamic pressure generated when the electric motor rotates, and an operation of the centrifugal compressor The air supply path (35) for sucking air from outside, compressing the air with a centrifugal compressor and supplying the air to the fuel cell stack, and the amount of air supplied to the fuel cell stack by controlling the rotation speed of the electric motor The air supply path includes a valve (39) for adjusting the amount of air, and the control unit has a rotary shaft in a radial foil bearing that is driven by dynamic pressure. An air supply device for a fuel cell (6) having a valve control unit (41) for adjusting the amount of air supplied to the fuel cell stack by controlling the valve while maintaining the rotation speed of the electric motor ) (Claim 1). The alphanumeric characters in parentheses indicate corresponding components in the embodiments described later.

According to the present invention, by controlling the valve by the valve control unit, the fuel cell stack is maintained while maintaining the rotational speed at which the rotary shaft floats by the dynamic pressure in the radial foil bearing without reducing the rotational speed of the electric motor. The amount of air supplied to the can be adjusted.
Therefore, when the fuel cell vehicle is running, the foil segment directly contacts the outer peripheral surface of the rotating shaft and prevents rotation (low speed rotation) with the rotating shaft supported from the radial direction for a long time. The segment can be prevented from wearing in a short period of time. Therefore, according to the present invention, it is possible to provide an air supply device for a fuel cell in which the amount of wear is increased and the characteristics for floating the rotary shaft in the radial foil bearing are less likely to be lost or lost.

According to the present invention, the valve can be provided on the upstream side (36) of the air flow from the centrifugal compressor in the air supply path (Claim 2).
In this case, the amount of air sucked from the outside through the air supply path is limited by a valve, so that the rotation speed of the electric motor whose rotative shaft is lifted by dynamic pressure is maintained and the air supplied to the fuel cell stack is maintained. The amount can be suppressed. The amount of air supplied to the fuel cell stack can be adjusted by adjusting the valve.

Further, according to the present invention, the air supply path is divided into the main path (43) reaching the fuel cell stack on the downstream side (37) of the air flow from the centrifugal compressor, and the branch reaching from the main path to the accumulator (44). And a valve can be provided in the branch path (Claim 3).
In this case, the amount of air supplied to the fuel cell stack through the main path can be suppressed by sending a part of the air compressed by the centrifugal compressor to the accumulator through the branch path. The amount of air supplied to the fuel cell stack can be adjusted by adjusting the valve.

  The compressed air sent to the accumulator can be supplied to the fuel cell stack at any time. For example, when a large amount of air is required, such as during rapid acceleration or high-speed driving of a fuel cell vehicle, supplying the air to the fuel cell stack reduces the power consumption by providing a margin for the rotation of the electric motor. it can.

It is a block diagram which shows an example of the vehicle-mounted fuel cell apparatus in which the air supply apparatus for fuel cells of this invention is integrated. It is a schematic sectional drawing of the air supply apparatus for fuel cells concerning one Embodiment of this invention. 3 is a flowchart illustrating an example of control of an electric motor and a valve by a control unit in the fuel cell air supply device of FIG. 2. It is a schematic sectional drawing which shows the modification of the air supply apparatus for fuel cells of this invention. It is a flowchart which shows an example of control of the electric motor and valve | bulb by a control part among the air supply apparatuses for fuel cells of FIG.

Embodiments of the present invention will be specifically described below with reference to the drawings.
FIG. 1 is a block diagram showing an example of an on-vehicle fuel cell device in which the fuel cell air supply device of the present invention is incorporated.
Referring to FIG. 1, a fuel cell device 1 of this example supplies a fuel cell stack 2, a power controller 3 that controls power supplied from the fuel cell stack 2, and supplies hydrogen to the fuel cell stack 2. A high-pressure hydrogen tank 4 and a hydrogen pump 5, a fuel cell air supply device 6 for supplying compressed air to the fuel cell stack 2, a humidifier 7 for humidifying the air compressed by the fuel cell air supply device 6, A cooler 8 that cools the fuel cell stack 2 and the power controller 3 is provided.

  In the fuel cell device 1, the hydrogen supplied from the high-pressure hydrogen tank 4 via the hydrogen pump 5 and the air taken from the outside are compressed by the fuel cell air supply device 6 and humidified by the humidifier 7. Are supplied to the fuel cell stack 2. Then, the electric motor 9 that drives the vehicle with the electric power controlled by the electric power controller 3 is driven by the electrochemical reaction between hydrogen and air in the fuel cell stack 2.

FIG. 2 is a schematic cross-sectional view of the fuel cell air supply device 6 according to one embodiment of the present invention.
Referring to FIG. 2, the fuel cell air supply device 6 of this example includes an electric motor 13 including a rotary shaft 10, a rotor 11, and a stator 12, a housing 14 that houses the electric motor 13 therein, and the housing 14 and a centrifugal compressor 15 coupled to one end (the left end in the figure). In this embodiment, the housing 14 has a cylindrical shape with both ends closed.

The rotating shaft 10 has a cylindrical shaft body 16. The rotor 11 has a cylindrical shape having an inner diameter that matches the outer diameter of the shaft main body 16, is fitted on the shaft main body 16, and is rotated integrally with the rotary shaft 10. The stator 12 has a cylindrical shape whose outer diameter matches the inner diameter of the housing 14, and is fitted into the housing 14 and fixed.
On the rotary shaft 10, on the side of the centrifugal compressor 15 from the shaft body 16, there are an attachment portion 19 to which the magnetic disk 18 constituting the axial magnetic bearing 17 is attached, and an attachment portion 21 to which the impeller 20 of the centrifugal compressor 15 is attached. It is provided in order. Each part and the shaft body 16 are integrally formed so as to be coaxial with the central axis L1 of the rotary shaft 10.

The mounting portion 19 has a smaller diameter than the shaft main body 16 and is fitted into a through hole provided at the center of the disk-shaped magnetic disk 18. The mounting portion 21 has a cylindrical shape with a smaller diameter than the mounting portion 19, and an impeller 20 is fixed to the tip.
Further, on the side of the rotating shaft 10 opposite to the centrifugal compressor 15 side from the shaft body 16 (right side in the drawing, hereinafter sometimes referred to as “machine end side”), a magnetic disk 23 constituting an axial magnetic bearing 22 is provided. The attachment part 24 to which is attached is provided. The mounting portion 24 and the shaft body 16 are integrally formed so as to be coaxial with the central axis L1 of the rotating shaft 10. The mounting portion 24 has a smaller diameter than the shaft body 16 and is fitted into a through hole provided at the center of the disk-shaped magnetic disk 23.

An annular electromagnet 25 that constitutes an axial magnetic bearing 17 together with the magnetic disk 18 is provided in the housing 14 on the centrifugal compressor 15 side of the stator 12.
The electromagnet 25 is configured by embedding an electromagnetic coil 27 in an annular casing 26 that is fitted in the housing 14 and surrounds the shaft body 16. The electromagnet 25 is provided on the machine end side with respect to the magnetic disk 18, and the magnetic disk 18 is opposed to the electromagnet 25 from the centrifugal compressor 15 side.

On the other hand, an annular electromagnet 28 that forms an axial magnetic bearing 22 together with the magnetic disk 23 is provided in the housing 14 on the machine end side of the stator 12.
The electromagnet 28 is configured by embedding an electromagnetic coil 30 in an annular casing 29 that is fitted in the housing 14 and surrounds the shaft body 16. The electromagnet 28 is provided on the centrifugal compressor 15 side from the magnetic disk 23, and the magnetic disk 23 is opposed to the electromagnet 28 from the machine end side.

  The surfaces of the electromagnets 25 and 28 facing the magnetic disks 18 and 23 are planes orthogonal to the central axis L2 of the housing 14, respectively. The surfaces of the magnetic disks 18 and 23 that face the electromagnets 25 and 28 are planes orthogonal to the central axis L1 of the rotary shaft 10, respectively. The distance between both surfaces of both magnetic disks 18 and 23 is set to be larger by a certain clearance than the distance between both surfaces of both electromagnets 25 and 28 facing the magnetic disks 18 and 23, respectively.

Therefore, when the central axis L1 of the rotary shaft 10 and the central axis L2 of the housing 14 coincide with each other, the magnetic shafts 27 and 30 of both the electromagnets 25 and 28 are energized to generate a magnetic force. A pair of axial magnetic bearings 17 and 22 are supported in a non-contact state in the axial direction.
The casings 26 and 29 of the electromagnets 25 and 28 have a through hole at the center of the ring having an inner diameter that matches the outer diameter of the radial foil bearings 31 and 32, and the radial foil bearings 31 and 32 are inserted into the through holes. It is fitted and held.

  Each of the radial foil bearings 31 and 32 has one or more foil segments 33 and 34 made of a very thin metal foil or the like on the inner surface of a through hole formed in the rotating shaft 10 having a diameter larger than that of the shaft body 16. It is configured with an attached. The shaft body 16 has a dynamic pressure between the outer peripheral surface and the foil segments 33 and 34 when the rotational speed is increased while the foil segments 33 and 34 of the radial foil bearings 31 and 32 are in sliding contact during low-speed rotation. It is a cylindrical surface that generates

  According to the radial foil bearings 31 and 32, the foil segments 33 and 34 are in direct contact with the outer peripheral surface of the shaft body 16 of the rotating shaft 10 until the rotational speed of the rotating shaft 10 reaches a predetermined value. The shaft 10 can be supported from the radial direction. Further, after the rotational speed reaches a predetermined value or more, due to the dynamic pressure generated between the outer peripheral surface of the shaft body 16 and the foil segments 33, 34, the rotational segment 10 is moved over the entire circumference of the foil segment 33, It can be lifted from the surface of 34 and supported in a non-contact state.

An end surface on the machine end side of the mounting portion 24 of the rotating shaft 10 is a plane (sensor target surface) orthogonal to the central axis L1 of the rotating shaft 10. A displacement sensor 42 for detecting the distance between the magnetic disks 18, 23 and the electromagnets 25, 28, that is, the amount of displacement in the axial direction of the rotary shaft 10, is located at a position facing the sensor target surface of the housing 14. Is provided.
The displacement amount detected by the displacement sensor 42 is input to a displacement control unit (not shown), and the displacement control unit determines the distance between the magnetic disks 18 and 23 and the electromagnets 25 and 28 based on these displacement amounts. The energization amount to the electromagnetic coils 27 and 30 is controlled so as to be constant.

The centrifugal compressor 15 rotates the electric motor 13 to operate the centrifugal compressor 15, thereby sucking air from the outside as indicated by a solid line arrow in the figure, and the air is sent by the centrifugal compressor 15. An air supply path 35 that is compressed and supplied to the fuel cell stack 2 is connected.
In the embodiment, the air supply path 35 includes an upstream part 36 and a downstream part 37 of the air flow from the centrifugal compressor 15. The air supply path 35 is controlled to be opened and closed by driving an electric motor 38 in the middle of the upstream part 36. A valve 39 that adjusts the amount of air that flows through the supply path 35 and is supplied to the fuel cell stack 2 is provided.

The opening amount of the valve 39 is increased by the opening / closing control, so that the amount of air supplied to the fuel cell stack 2 through the air supply path 35 is increased, and the opening amount is decreased, so that the air supply path It serves to reduce the amount of air supplied to the fuel cell stack 2 through 35.
The fuel cell air supply device 6 includes a control unit 40. The control unit 40 controls the rotational speed of the electric motor 13 by adjusting the voltage value of the driving power input to the electric motor 13 and the fuel cell stack 2 through the air supply path 35 by the operation of the centrifugal compressor 15. It works to adjust the amount of air supplied to the.

Further, the control unit 40 controls the opening amount of the valve 39 by driving the electric motor 38 and adjusts the amount of air flowing through the air supply path 35, thereby supplying the fuel cell stack 2 through the air supply path 35. A valve control unit 41 for adjusting the amount of air is provided.
FIG. 3 is a flowchart showing an example of control of the electric motor 13 and the valve 39 by the control unit 40.

Referring to FIG. 3, when start of operation of fuel cell air supply device 6 is selected in step S <b> 1, control unit 40 inputs a control signal from valve control unit 41 to electric motor 38 in step S <b> 2 to control valve 39. Is fully opened, and in step S3, driving power is supplied to the electric motor 13 to start driving.
Next, in step S4, the control unit 40 determines whether or not the rotating shaft 10 has floated from the surface of the foil segments 33 and 34 of the radial foil bearings 31 and 32 due to dynamic pressure due to the increase in the rotational speed of the electric motor 13. To do. Whether or not the rotating shaft 10 has floated can be determined, for example, by any of the following methods.

(1) A rotation speed sensor for detecting the rotation speed of the rotation shaft 10 is provided, and the rotation speed detected by the rotation speed sensor is set based on the characteristics of the radial foil bearings 31 and 32. It is determined whether or not the number has been reached, and it is estimated whether or not the rotating shaft 10 has floated.
(2) A displacement sensor for detecting the radial displacement amount of the rotary shaft 10 is provided, and it is determined whether the rotary shaft has floated directly from the radial displacement amount of the rotary shaft 10 detected by the displacement sensor. .

  If it is determined in step S4 that the rotary shaft 10 has floated, the control unit 40 proceeds to step S5 and controls only the rotational speed of the electric motor 13 as in the conventional case. That is, the control unit 40 reduces the rotational speed of the electric motor 13 when the amount of air supplied to the fuel cell stack 2 through the air supply path 35 is excessive, and rotates the electric motor 13 when it is insufficient. The number is increased, and if it is neither excessive nor insufficient, control is performed to maintain the rotational speed of the electric motor 13.

Whether the amount of air is excessive or insufficient is determined by comparing the amount of electric power generated in the fuel cell stack 2 with the amount of electric power required in accordance with, for example, the traveling state of the fuel cell vehicle, The unit 37 can be provided with a meter, and can be directly judged from the amount of air detected by the meter.
Next, in step S6, it is determined whether or not the end of the operation of the fuel cell air supply device 6 is selected. If the end of the operation is selected, the process proceeds to step S7, where the drive of the electric motor 13 is stopped and the fuel cell air is stopped. The operation of the supply device 6 is terminated.

On the other hand, when the operation end is not selected, the control unit 40 returns to step S4 and determines in step S4 that the rotating shaft 10 is not lifted up or until the operation end is selected in step S6. → S5 → S6 is repeated.
If it is determined in step S4 that the rotary shaft 10 has not floated, the control unit 40 proceeds to step S8 and performs control to increase the rotational speed of the electric motor 13.

Next, the process proceeds to step S9, where it is determined whether or not the amount of air supplied to the fuel cell stack 2 through the air supply path 35 is insufficient.
If it is determined that the amount of air is insufficient, the control unit 40 proceeds to step S6, where the end of the operation of the fuel cell air supply device 6 is selected in step S6, or the rotary shaft 10 has floated in step S4. Or steps S4 → S8 → S9 → S6 are repeated until it is determined in step S9 that the amount of air is not insufficient.

Thereby, the rotation speed of the electric motor 13 can be raised and the rotating shaft 10 can be floated as early as possible. After the rotary shaft 10 has surfaced, the routine proceeds to the normal rotational speed control described above (steps S4 → S5 → S6).
If it is determined in step S9 that the amount of air is not insufficient, the control unit 40 proceeds to step S10, performs control to reduce the valve opening amount by the valve control unit 41, and then proceeds to step S6. In step S4, the end of the operation of the fuel cell air supply device 6 is selected in step S4, or it is determined in step S4 that the rotary shaft 10 has floated, or in step S9 it is determined that the amount of air is insufficient. → S8 → S9 → S10 → S6 are repeated.

As a result, the rotational speed of the electric motor 13 can be increased while suppressing the flow rate so that excessive air is not supplied, and the rotary shaft 10 can be floated as early as possible. After the rotary shaft 10 has surfaced, the routine proceeds to the normal rotational speed control described above (steps S4 → S5 → S6).
By performing such control, for example, when the fuel cell vehicle is running, the foil segments 33 and 34 of the radial foil bearings 31 and 32 directly contact the outer peripheral surface of the shaft body 16 of the rotating shaft 10 so that the rotating shaft 10 has a diameter. It is possible to prevent the foil segments 33 and 34 from being worn in a short period of time by preventing the rotation (low-speed rotation) in a state of being supported from the direction from continuing for a long time. Therefore, it is possible to satisfactorily maintain the characteristics for floating the rotary shaft 10 in the radial foil bearings 31 and 32 over a long period of time.

Although the description of the embodiment of the present invention has been described above, the present invention is not limited to the contents of the above-described embodiment, and various modifications can be made within the scope of the claims. In the following description, differences from the embodiment shown in FIGS. 1 to 3 will be mainly described, and the same components are denoted by the same reference numerals and description thereof will be omitted.
FIG. 4 is a schematic sectional view showing a modification of the fuel cell air supply device 6 of the present invention.

Referring to FIG. 4, in the fuel cell air supply device 6 of this example, the downstream portion 37 of the air flow from the centrifugal compressor 15 in the air supply path 35 is connected to the main path 43 reaching the fuel cell stack 2 and the above-described portion. A branch path 45 that branches from the main path 43 and reaches the accumulator 44. A valve 39 is provided in the middle of the branch path 45.
The opening amount of the valve 39 is increased by opening / closing control, thereby increasing the amount of air sent to the accumulator 44 through the branch passage 45 and decreasing the amount of air supplied to the fuel cell stack 2 through the main passage 43. By reducing the amount of opening, the amount of air sent to the accumulator 44 is decreased, and the amount of air supplied to the fuel cell stack 2 through the main path 43 is increased.

FIG. 5 is a flowchart illustrating an example of control of the electric motor 13 and the valve 39 by the control unit 40.
Referring to FIG. 5, in this example, control unit 40 controls each unit in the same manner as in the example of FIG. 3 except that control of valve 39 in steps S2 and S10 is different.
That is, in step S <b> 2, the control unit 40 controls the valve 39 to be fully closed by inputting a control signal from the valve control unit to the electric motor 38. As a result, the branch path 45 from the centrifugal compressor 15 to the accumulator 44 is blocked, and the centrifugal compressor 15 is directly connected only to the fuel cell stack 2 via the main path 43.

In this state, after driving the electric motor 13 in step S3, if it is determined in step S4 that the rotary shaft 10 has floated, the control unit 40 repeats steps S4 → S5 → S6 to perform normal rotation speed control.
If it is determined in step S4 that the rotary shaft 10 has not floated, the control unit 40 proceeds to step S8 and performs control to increase the rotation speed of the electric motor 13. That is, steps S4 → S8 → S9 → S6 are repeated.

Thereby, the rotation speed of the electric motor 13 can be raised and the rotating shaft 10 can be floated as early as possible. After the rotary shaft 10 has floated, the routine proceeds to normal rotational speed control (steps S4 → S5 → S6).
If it is determined in step S9 that the amount of air supplied to the fuel cell stack 2 through the air supply path 35 is not insufficient, the control unit 40 increases the opening amount of the valve 39 by the valve control unit 41 in step S10. To control. That is, steps S4 → S8 → S9 → S10 → S6 are repeated.

As a result, the rotational speed of the electric motor 13 can be increased while sending a part of the air to the accumulator 44 so that excessive air is not supplied to the fuel cell stack 2, and the rotary shaft 10 can be floated as early as possible. After the rotary shaft 10 has floated, the routine proceeds to normal rotational speed control (steps S4 → S5 → S6).
By performing such control, for example, when the fuel cell vehicle is running, the foil segments 33 and 34 of the radial foil bearings 31 and 32 directly contact the outer peripheral surface of the shaft body 16 of the rotating shaft 10 so that the rotating shaft 10 has a diameter. It is possible to prevent the foil segments 33 and 34 from being worn in a short period of time by preventing the rotation (low-speed rotation) in a state of being supported from the direction from continuing for a long time. Therefore, it is possible to satisfactorily maintain the characteristics for floating the rotary shaft 10 in the radial foil bearings 31 and 32 over a long period of time.

The compressed air accumulated and accumulated in the accumulator 44 can be supplied to the fuel cell stack 2 at any time. For example, when a large amount of air is required, for example, when the fuel cell vehicle is rapidly accelerating or traveling at high speed, if the air is supplied to the fuel cell stack 2, the electric motor 13 is consumed with a margin for rotation. Electric power can be reduced.
In addition, the fuel cell air supply device of the present invention can be used for purposes other than in-vehicle use.

  6: Fuel cell air supply device, 10: Rotating shaft, 11: Rotor, 12: Stator, 13: Electric motor, 15: Centrifugal compressor, 31, 32: Radial foil bearing, 35: Air supply path, 36: Upstream Section (upstream side), 37: downstream section (downstream side), 39: valve, 40: control section, 41: valve control section, 43: main path, 44: accumulator, 45: branch path.

Claims (3)

An electric motor including a rotating shaft, a rotor and a stator;
A centrifugal compressor connected to one end of a rotating shaft of the electric motor and operated by rotation of the electric motor;
A pair of radial foil bearings that support the rotating shaft by floating by a dynamic pressure generated when the electric motor rotates;
An air supply path for sucking air from the outside by the operation of the centrifugal compressor, compressing the air with the centrifugal compressor, and supplying the air to the fuel cell stack;
A controller that controls the number of air supplied to the fuel cell stack by controlling the number of revolutions of the electric motor,
The air supply path includes a valve for adjusting the amount of air;
The control unit includes a valve control unit that controls the valve to adjust the amount of air supplied to the fuel cell stack while maintaining the rotation speed of the electric motor in which the rotation shaft of the radial foil bearing floats due to dynamic pressure. An air supply device for a fuel cell.   The air supply device for a fuel cell according to claim 1, wherein the valve is provided in the air supply path on the upstream side of the air flow from the centrifugal compressor.   The air supply path includes a main path that reaches the fuel cell stack on the downstream side of the air flow from the centrifugal compressor, and a branch path that branches from the main path and reaches the accumulator, and the valve is provided in the branch path. The fuel cell air supply device according to claim 1.

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