JP6329576B2 - Circulation pump for fuel cell system - Google Patents

Description

  The present invention relates to a circulation pump for a fuel cell system.

As shown in Patent Document 1 below, in a fuel cell system, a gas supply path through which gas (cathode gas, anode gas) supplied to the fuel cell flows, and off gas (cathode off gas, anode off gas) discharged from the fuel cell flows. An off-gas discharge path, a return flow path connecting the gas supply path and the off-gas discharge path, and a circulation pump provided on the return flow path.
Then, when the circulation pump is driven, the off gas in the off gas discharge path returns to the gas supply path and is supplied to the fuel cell again.

For example, a cascade pump is used as a circulation pump for a fuel cell system (hereinafter sometimes simply referred to as “circulation pump”) (see Patent Document 2 below).
The circulation pump includes a housing in which a C-shaped C-shaped channel is formed inside, a disk-shaped impeller having a plurality of grooves formed on the outer peripheral side, and a rotating shaft that rotates together with the impeller. .
One end of the C-shaped channel is continuous with the suction port, and the other end of the C-shaped channel is continuous with the discharge port.
Then, when the impeller rotates at a high speed, the gas flowing into the C-shaped channel is rotated approximately once, and high-pressure gas is discharged from the discharge port.
In Patent Document 2 below, one end of the rotating shaft to which the impeller is fixed is not supported by a rolling bearing or the like.

Japanese National Patent Publication No. 08-500931 JP 2002-31074 A

Here, in order to support one end portion of the rotating shaft by the rolling bearing, it is considered to form a hole portion on the inner surface of the housing and radially inward of the C-shaped flow path, and to fit the rolling bearing in the hole portion. Has been.
However, the dew condensation water (hereinafter simply referred to as “liquid”) in the off-gas channel flows into the C-shaped channel together with the off-gas. Therefore, there is a possibility that the liquid enters the radial inner side beyond the inner peripheral edge of the C-shaped flow path, and the liquid adheres to the rolling bearing. As a result, the lubricating oil in the rolling bearing flows out, obstructing the smooth rotation of the rotating shaft, and may cause abnormal noise.

  Therefore, the present invention is an invention created in view of the above-described background, and an object thereof is to provide a circulation pump for a fuel cell system in which a liquid hardly adheres to a rolling bearing.

As means for solving the above-described problems, a circulation pump for a fuel cell system according to the present invention includes a housing having a C-shaped flow path, a disk-shaped impeller having a plurality of grooves formed on the outer peripheral side, and A rotating shaft that rotates integrally with the impeller, and a rolling bearing that rotatably supports one end of the rotating shaft, wherein the housing is a substantially C-shaped C-shape that forms the C-shaped flow path. A ring-shaped continuation that is located in the center of the groove, the hole in which the rolling bearing is fitted, the inner peripheral edge of the C-shaped groove and the edge of the hole The impeller is formed with a through-hole through which the rotating shaft penetrates at a central portion, a ring-shaped base portion whose one end surface faces the continuous surface, and the plurality of grooves, A ring-shaped blade portion covering the C-shaped groove portion, on one of the continuous surface and the one end surface The first convex portions other projecting towards the continuous surface and the end surface is formed, the first protrusion is provided with a first annular portion formed around the rotating shaft, the first convex portion, The first convex portion includes a barrier portion that is formed on the continuous surface and extends radially outward from an outer peripheral surface of the first annular portion .

  According to the invention, when the liquid that has entered between the continuous surface (housing) and the one end surface (the impeller) moves toward the rolling bearing, the liquid contacts the first annular portion and moves toward the rolling bearing. It is prevented from moving. For this reason, it can suppress that a liquid adheres to a rolling bearing.

Between the continuous surface (housing) and the one end surface (impeller), an air flow that gradually approaches the central portion (rolling bearing) while rotating around the rotation shaft is generated by the rotation of the impeller. Therefore, the liquid that has entered between the continuous surface (housing) and the one end surface (impeller) gradually approaches the central portion (rolling bearing) while circling around the rotating shaft.
However, according to the said barrier part, it becomes difficult for gas to circulate around a rotating shaft, and the gas and liquid which circulate around the rotating shaft reduce. For this reason, it can suppress that a liquid adheres to a rolling bearing.

  Moreover, in the said invention, it is preferable that the said rotating shaft extends in a horizontal direction, and the one end side of the said C-shaped groove part is located below the said rotating shaft while continuing to a discharge outlet.

  According to the above configuration, while the circulation pump is stopped (when the impeller is stopped rotating), the liquid moves downward along the C-shaped groove portion to one end side or the other end side by its own weight. Moreover, since the one end side of a C-shaped groove part is located below a rotating shaft, many liquids in a C-shaped groove part are drained from a discharge outlet.

  In the present invention, it is preferable that the barrier portion extends downward as viewed from the rotation axis direction.

For example, when the barrier portion extends upward from the upper portion of the first annular portion, the liquid adhering to the barrier portion may move to the lower side due to its own weight, in other words, move to the first annular portion side, and may adhere to the rolling bearing. is there.
However, according to the said structure, a liquid moves to the lower end side (tip side) of a barrier part with dead weight. For this reason, it can suppress that a liquid adheres to a rolling bearing.

  In the invention, the other one of the continuous surface and the one end surface is formed with a second convex portion that protrudes toward one of the continuous surface and the one end surface, and the second convex portion is the first convex portion. It is a second annular part that orbits the rotating shaft on the inner peripheral side of the annular part, and it is preferable that the first annular part and the second annular part have a labyrinth structure.

  According to the above configuration, even if the liquid exceeds the first annular portion, it is difficult to enter the gap between the first annular portion and the second annular portion. Therefore, it can suppress that a liquid adheres to a rolling bearing.

  The cathode off gas contains more liquid than the anode off gas. Therefore, in the said invention, it is preferable to provide in the return flow path by the side of a cathode.

  ADVANTAGE OF THE INVENTION According to this invention, the circulation pump for fuel cell systems which a liquid cannot adhere to a rolling bearing can be provided.

1 is an overall configuration diagram of a fuel cell system. It is sectional drawing which cut the cathode side circulation pump in the rotating shaft direction, and is the II-II arrow directional cross-sectional view of FIG. It is the rear view which looked at the front housing from back. It is the front view which looked at the impeller from the front. It is the expanded sectional view which expanded a part of FIG. It is sectional drawing which shows the 1st modification of a 2nd convex part. It is sectional drawing which shows the 2nd modification of a 2nd convex part.

  Next, a fuel cell system in which the circulation pump according to the present invention is applied to a cathode-side circulation pump will be described.

(Fuel cell system)
The fuel cell system 100 includes a fuel cell stack 110, an anode system 120 that supplies and discharges hydrogen (fuel gas) to and from the anode of the fuel cell stack 110, and air containing oxygen to the cathode of the fuel cell stack 110 (oxidation) A cathode system 130 that supplies and discharges (agent gas), and an ECU (Electronic Control Unit) 140 that electronically controls them.

(Fuel cell stack)
The fuel cell stack 110 is a stack formed by stacking a plurality of solid polymer type single cells (fuel cells), and the plurality of single cells are electrically connected in series.
The single cell includes an MEA (Membrane Electrode Assembly) and two conductive anode separators and cathode separators sandwiching the MEA.
The MEA includes an electrolyte membrane (solid polymer membrane) made of a monovalent cation exchange membrane or the like, and an anode and a cathode sandwiching the electrolyte membrane.

In the anode separator, grooves and through holes for supplying and discharging hydrogen to and from the anode of each MEA are formed, and these grooves and through holes function as the anode flow path 111 (fuel gas flow path).
In the cathode separator, grooves and through holes for supplying and discharging air to and from the cathode of each MEA are formed, and these grooves and through holes function as a cathode channel 112 (oxidant gas channel). .

When hydrogen is supplied to each anode via the anode flow path 111 and air is supplied to each cathode via the cathode flow path 112, an electrode reaction occurs, and a potential difference (OCV (Open Circuit Voltage) is generated in each single cell. ), Open circuit voltage).
Next, when the fuel cell stack 110 and the external circuit are electrically connected and current is taken out, the fuel cell stack 110 generates power.
Further, when the fuel cell stack 110 generates electricity in this way, moisture (water vapor) is generated at the cathode, and this moisture permeates the electrolyte membrane to the anode side. All off-gas is humid.

  The anode system 120 includes a hydrogen tank 121, an injector 122, an ejector 123, a purge valve 124, an anode-side circulation pump 125, and pipes 126a to 126g.

The hydrogen tank 121 is a container that stores hydrogen at a high pressure, and hydrogen is supplied to the injector 122 via a pipe 126a.
The injector 122 is a device that receives a signal from the ECU 140 and intermittently injects new hydrogen from the hydrogen tank 121 from the nozzle. The hydrogen injected from the injector 122 is supplied into the anode flow path 111 through the pipe 126b, the ejector 123, and the pipe 126c.

The ejector 123 generates a negative pressure by injecting new hydrogen from the injector 122 with a nozzle, and by this negative pressure, the anode off-gas of the pipe 126g is sucked to mix the new hydrogen and the anode off-gas, and the anode flow path 111 It injects towards
The purge valve 124 is a normally closed type, and is provided on the downstream side of the pipe 126 d connected to the outlet of the anode flow path 111. The purge valve 124 is opened by the ECU 70 when impurities (water vapor, nitrogen, etc.) accompanying hydrogen are discharged (purged) when the system is started or when the fuel cell stack 110 generates power. As a result, the impurities are discharged to the outside through the pipe 126e and the pipe 135d.

  The anode-side circulation pump 125 is a pump that is provided on the return flow path (the pipes 126f and 126g), and pumps the anode off gas to the supply path side to control the hydrogen circulation amount.

  The cathode system 130 includes an air pump 131, an inlet side sealing valve 132, an outlet side sealing valve 133, the cathode side circulation pump 1, and pipes 135a to 135f.

  The air pump 131 is a device that pumps air (oxygen) and supplies the air (oxygen) to the cathode channel 112 via the pipes 135a and 135b.

The inlet-side sealing valve 132 is provided on the flow path (between the pipe 135a and the pipe 135b) connecting the inlet of the cathode flow path 112 and the outside.
The outlet side sealing valve 133 is provided on the flow path (between the pipe 135c and the pipe 135d) connecting the outlet of the cathode flow path 112 and the outside.
The inlet side sealing valve 132 and the outlet side sealing valve 133 are closed when the fuel cell stack 110 stops generating power in response to a signal from the ECU 140. Thereby, generation | occurrence | production of highly active hydroxy radical etc. can be suppressed by oxygen flowing in from the outside, and it can prevent that an electrode catalyst layer is oxidized with a hydroxy radical and a fuel cell deteriorates.

The cathode-side circulation pump 1 is driven after the start of power generation stop of the fuel cell stack 110 in response to a signal from the ECU 140, and fuels oxygen in the circulation channel (part of the pipe 135b, part of 135c, 135e, 135f). Supply to the battery stack 110.
When the cathode side circulation pump 1 is driven, the inlet side sealing valve 132 and the outlet side sealing valve 133 are closed. On the anode side, the purge valve 124 is closed and the anode-side circulation pump 125 is driven.
According to this, the fuel cell stack 110 generates electric power, oxygen in the circulation channel (part of the pipe 135b, part of 135c, 135e, 135f) is consumed, and generation of hydroxy radicals is suppressed.

As shown in FIG. 2, the cathode-side circulation pump 1 includes a housing 2 in which a C-shaped groove 25 is formed, a disk-shaped impeller 3 accommodated in the housing 2, and a rotation that rotates integrally with the impeller 3. A shaft 4, a first bearing 5 and a second bearing 6 that rotatably support the rotating shaft 4, a rotor 7 fixed to the rotating shaft 4, and a stator 8 provided on the outer peripheral side of the rotor 7. .
For convenience of explanation, the direction in which the rotating shaft 4 extends will be described as the front-rear direction. In addition, one end side of the rotating shaft 4 supported by the first bearing 5 will be described as the rear, and the other end side of the rotating shaft 4 supported by the second bearing 6 will be described as the front.

The housing 2 includes a bottomed cylindrical rear housing 21 that opens toward the front, and a substantially disk-shaped front housing 22 that closes the opening of the rear housing 21.
The rear housing 21 and the front housing 22 are integrated by fastening a bolt B that penetrates the rear flange 21 a of the rear housing 21 to the front flange 22 a of the front housing 22.

In the rear housing 21, the rotating shaft 4, the rotor 7, and the stator 8 are accommodated.
On the front surface (inner surface) of the bottom wall 21 b of the rear housing 21, a circular first bearing hole 21 c for fitting the first bearing 5 is formed.

  As shown in FIG. 3, the front housing 22 includes a suction port 23 and a discharge port 24 penetrating in the front-rear direction, a substantially C-shaped C-shaped groove portion 25 that forms a C-shaped channel, a partition wall portion 26, and C A second bearing hole 27 located at the center of the groove 25 and a ring that forms part of the rear surface 22b of the front housing 22 and is located between the C groove 25 and the second bearing hole 27 And a continuous surface 28 having a shape.

The downstream end of the pipe 135e (see FIG. 1) is connected to the suction port 23. As a result, the anode off gas flows into the housing 2 through the suction port 23 (see arrow A1).
An upstream end of a pipe 135f (see FIG. 1) is connected to the discharge port 24. As a result, the anode off gas in the housing 2 is discharged to the pipe 135f through the discharge port 24 (see arrow A4).
The suction port 23 is located on the lower left side when viewed from the direction of the central axis O.
The discharge port 24 is located on the lower right side when viewed from the direction of the central axis O.

The C-shaped groove 25 is formed by denting a part of the rear surface 22b of the front housing 22 forward.
The C-shaped groove portion 25 extends in the circumferential direction about the central axis O and is formed in an arc shape (C shape).
One end of the C-shaped groove portion 25 is continuous with the suction port 23, and the other end of the C-shaped groove portion 25 is continuous with the discharge port 24.
The bottom surface 25c of the C-shaped groove portion 25 is formed in an arc shape (C shape) as viewed from the extending direction (circumferential direction) (see FIG. 2).

  The partition wall portion 26 extends in an arc shape between one end (suction port 23) and the other end (discharge port 24) of the C-shaped groove portion 25, and prevents the C-shaped groove portion 25 from making a round.

  The second bearing hole 27 is a circular hole formed in the rear surface 22b of the front housing 22, and the second bearing 6 is fitted therein.

As shown in FIG. 3, the continuous surface 28 is a ring-shaped surface formed on the rear surface 22 b of the front housing 22, is on the inner peripheral side of the C-shaped groove portion 25 and the partition wall portion 26, and is a second bearing. It is located on the outer peripheral side of the hole 27 for use.
The outer peripheral edge of the continuous surface 28 is continuous with the inner peripheral edge 25 a of the C-shaped groove 25.
The inner circumferential edge of the continuous surface 28 is continuous with the rear edge 27 a of the second bearing hole 27.
As shown in FIG. 2, the continuous surface 28 is recessed forward of the inner peripheral edge 25 a of the C-shaped groove 25. A first convex portion 40 that protrudes toward the impeller 3 is formed on the continuous surface 28.
The first convex portion 40 will be described later.

The impeller 3 is a part having a substantially disk shape, and is disposed so as to face the rear surface 22 b of the front housing 22.
As shown in FIG. 4, the impeller 3 includes a ring-shaped base portion 30 in which a through hole 31 through which the rotation shaft 4 passes is formed in the center portion, and a ring-shaped blade portion 32 that circulates on the outer peripheral side of the base portion 30. .

The blade portion 32 includes a bottom wall 35 that extends radially outward from the outer peripheral surface of the base portion 30, an annular outer peripheral wall 36 that projects forward from the outer peripheral edge of the bottom wall 35, and a front side from the inner peripheral edge of the bottom wall 35. And a plurality of partition walls that radially extend between the outer peripheral wall 36 and the inner peripheral wall 37 and partition the space surrounded by the bottom wall 35, the outer peripheral wall 36, and the inner peripheral wall 37 in the circumferential direction. 38. Thereby, a plurality of grooves 39 arranged in the circumferential direction are formed on the front surface side of the blade portion 32.
In addition, as shown in FIG. 2, when the blade | wing part 32 is cut to radial direction, the bottom wall 35, the outer peripheral wall 36, and the inner peripheral wall 37 are united, and comprise circular arc shape (C shape).

As shown in FIG. 2, the blade portion 32 is located behind the C-shaped groove portion 25 and the partition wall portion 26 in the housing 2.
The outer peripheral wall 36 and the inner peripheral wall 37 of the blade part 32 are slidably contacted with the inner peripheral edge 25 a and the outer peripheral edge 25 b of the C-shaped groove part 25, and the blade part 32 is behind the C-shaped groove part 25. Covering. For this reason, the gas and the liquid in the C-shaped groove 25 enter the plurality of grooves 39 of the impeller 3.

The rotating shaft 4 is fitted into the inner peripheral surface 33 of the base 30, and the impeller 3 and the rotating shaft 4 are integrated.
The base 30 is disposed behind the continuous surface 28 of the front housing 22. Further, the front surface 34 of the base portion 30 faces the continuous surface 28 in a state of being separated in the axial direction.
A second convex portion 50 that projects toward the continuous surface 28 is formed on the front surface 34. The second convex portion 50 will be described later.

Since the first bearing 5 and the second bearing 6 have the same configuration, the second bearing 6 will be described as a representative example, and the description of the first bearing 5 will be omitted.
As shown in FIG. 5, the second bearing 6 is a radial ball bearing in which a plurality of balls 6c are provided between an inner ring 6a and an outer ring 6b. Seal members 6d and 6e are provided between the inner ring 6a and the outer ring 6b and before and after the ball 6c. For this reason, it is difficult for the liquid to enter the second bearing 6, and the outflow of the lubricating oil in the second bearing 6 is suppressed.

As shown in FIG. 2, the rotor 7 includes a plurality of permanent magnets 7 a and a pair of rotor holders 7 b and 7 b that are annular and fix the plurality of permanent magnets 7 a to the outer peripheral surface of the rotating shaft 4.
The stator 8 is for generating a rotational moment of the rotor 7, and includes a plurality of coils 8 a and a stator holder 8 b that has an annular shape and fixes the plurality of coils 8 a to the rear housing 21.

The electric current flowing through the plurality of coils 8a is controlled by the ECU 140 so as to rotate clockwise when the rotor 7 is viewed from behind. Therefore, when the cathode-side circulation pump 1 is driven, the impeller 3 and the rotating shaft 4 rotate in the clockwise direction when viewed from the rear.
When the impeller 3 rotates, the cathode offgas and the liquid that have flowed into the C-shaped groove portion 25 from the suction port 23 are rotated substantially once and are pumped to the other end side (discharge port) side of the C-shaped groove portion 25 ( (See arrows A2 and A3 in FIG. 3). As a result, high-pressure cathode off-gas and liquid are discharged from the discharge port 24 (see arrow A4 in FIG. 3).

  Further, when the impeller 3 rotates, an airflow (see arrows B <b> 1-B <b> 3 in FIG. 3) is generated between the continuous surface 28 and the front surface 34 while gradually rotating around the rotation shaft 4. Therefore, the liquid that has moved inward in the radial direction from between the inner peripheral edge 25 a of the C-shaped groove 25 and the inner peripheral wall 37 of the blade portion 32 gradually moves toward the second bearing 6 while circling the rotary shaft 4. .

Below, the 1st convex part 40 and the 2nd convex part 50 are demonstrated.
As shown in FIG. 3, the first convex portion 40 includes a first annular portion 41 that circulates around the rotation shaft 4, and a barrier portion 42 that extends radially outward from the outer peripheral surface of the first annular portion 41.

The first annular portion 41 is a wall for preventing the liquid from moving inward in the radial direction. The first annular portion 41 includes a circular outer annular portion 43 as viewed from the central axis O direction and a circular inner annular portion 44 provided inside the outer annular portion 43 and viewed from the central axis O direction. It has two layers.
For this reason, as shown in FIG. 5, even if the liquid that has entered between the continuous surface 28 and the front surface 34 moves to the center axis O side, it contacts the outer annular portion 43 and the inner annular portion 44 (see arrow C). ). For this reason, the liquid is less likely to move to the inner peripheral side than the outer annular portion 43 and the inner annular portion 44, and the liquid is suppressed from adhering to the second bearing 6.
The inner annular portion 44 and the rear end surface of the inner annular portion 44 are separated from the front surface 34 of the impeller 3.

As shown in FIG. 3, the barrier portion 42 extends from the outer peripheral surface of the outer annular portion 43 to the outside in the radial direction, and prevents the gas from circling the rotating shaft 4 (see arrows B1 to B3). .
Therefore, according to the barrier portion 42, the gas circulating around the rotation shaft 4 is reduced, and the liquid moving toward the second bearing 6 is also reduced, so that the liquid adheres to the second bearing 6. Can be suppressed.

  The lower end 42 a of the barrier portion 42 extends to the vicinity of the inner peripheral edge 25 a of the C-shaped groove portion 25. For this reason, the gas circulating around the rotating shaft 4 is greatly reduced, and the amount of liquid moving toward the second bearing 6 is also greatly reduced.

The barrier portion 42 extends downward from the lower portion of the outer annular portion 43. For this reason, the liquid adhering to the barrier part 42 moves to the lower end 42a of the barrier part 42 by its own weight. Therefore, there is no possibility of moving to the second bearing 6 side along the barrier portion 42.
The barrier portion 42 extends toward the partition wall portion 26. In other words, the barrier portion 42 extends between the suction port 23 and the discharge port 24.

The second convex part 50 is formed in a cylindrical shape.
As shown in FIG. 5, the outer peripheral surface 50 a of the second convex portion 50 faces the inner peripheral surface 44 a of the inner annular portion 44 in the radial direction of the rotating shaft 4.
Further, the gap L1 between the outer peripheral surface 50a of the second convex portion 50 and the inner peripheral surface 44a of the inner annular portion 44 is formed to be narrow and has a labyrinth structure. Even if it gets over, it enters the space between the outer peripheral surface 50a of the second convex portion 50 and the inner peripheral surface 44a of the inner annular portion 44 and is difficult to move to the second bearing 6 side. Thereby, the liquid is less likely to adhere to the second bearing 6.

  In addition, a protrusion 51 is formed on the front edge on the inner peripheral side of the second convex portion 50. The protrusion 51 is in contact with the rear surface of the inner ring 6a of the second bearing 6, so that the impeller 3 is not displaced forward.

Although the embodiment has been described above, the present invention is not limited to this.
For example, the first convex portion 40 may be configured only from the first annular portion 41.
Moreover, when the 1st convex part 40 is comprised only from the 1st annular part 41, you may form toward the front surface 34 instead of the continuous surface 28. Furthermore, the 1st annular part 41 is only the outer side annular part 43. It may be.

  Further, the barrier portion 42 extends downward from the inner annular portion 44, but may extend toward the left side, for example. This is because even with such a configuration, it is possible to block the flow of gas around the rotating shaft 4. However, in order to prevent the adhered liquid from moving to the second bearing 6 side due to its own weight, the barrier portion 42 preferably extends downward as viewed from the rotation axis direction as shown in the embodiment.

  Further, with respect to the barrier portion 42, the longer the radial length, the more the flow of gas that circulates around the rotation shaft 4 can be blocked. Therefore, it is preferable that the lower end 42 a of the barrier portion 42 is continuous with the inner peripheral edge 25 a of the C-shaped groove portion 25.

  Further, in this embodiment, the example applied to the cathode-side circulation pump 1 provided in the cathode-side return flow path (the pipes 135e and 135f) has been described, but may be applied to the anode-side circulation pump 125. .

Moreover, although the 2nd convex part 50 of embodiment protrudes ahead from the front surface 34, this invention is not limited to this.
For example, as shown in FIG. 6, the 2nd convex part 60 may be spaced apart from the shaft part 61 in which the rotating shaft 4 fits in the impeller 3.
Alternatively, as shown in FIG. 7, the second convex portion 70 may extend radially outward from the shaft portion 61 and be separated from the front surface 34.
Alternatively, although not particularly illustrated, it may be provided between the outer annular portion 43 and the inner annular portion 44 or on the outer peripheral side of the outer annular portion 43.

1 Cathode side circulation pump (circulation pump for fuel cell system)
2 Housing 3 Impeller 4 Rotating shaft 5 First bearing 6 Second bearing (rolling bearing)
22 Front housing 22b Rear surface 23 Suction port 24 Discharge port 25 C-shaped groove (C-shaped channel)
25a Inner peripheral edge 25b Outer peripheral edge 27 Second bearing hole (hole)
27a Rear edge 28 Continuous surface 30 Base portion 31 Through hole 32 Blade portion 34 Front surface (one end surface)
39 Groove 40 First convex portion 41 First annular portion 42 Barrier portion 50, 60, 70 Second convex portion (second annular portion)

Claims (5)

A housing in which a C-shaped channel is formed;
A disc-shaped impeller having a plurality of grooves formed on the outer peripheral side;
A rotating shaft that rotates integrally with the impeller;
A rolling bearing that rotatably supports one end of the rotating shaft;
With
The housing is
A substantially C-shaped C-shaped groove portion forming the C-shaped flow path;
A hole located at the center of the C-shaped groove, and into which the rolling bearing is fitted;
A ring-shaped continuous surface continuous to the inner peripheral edge of the C-shaped groove and the edge of the hole;
With
The impeller is
A through hole through which the rotation shaft passes is formed at the center, and a ring-shaped base portion having one end surface facing the continuous surface;
The plurality of grooves are formed, and a ring-shaped blade portion covering the C-shaped groove portion,
With
One of the continuous surface and the one end surface is formed with a first convex portion that protrudes toward the other of the continuous surface and the one end surface,
The first convex portion includes a first annular portion that goes around the rotating shaft ,
The first convex portion is formed on the continuous surface,
The circulation pump for a fuel cell system, wherein the first convex portion includes a barrier portion extending radially outward from an outer peripheral surface of the first annular portion . The rotating shaft extends in a horizontal direction;
The C-end side of the groove, as well as continuous to the discharge port, a circulation pump for a fuel cell system according to claim 1, characterized in that located on the lower side than the rotary shaft. The circulation pump for a fuel cell system according to claim 2 , wherein the barrier portion extends downward as viewed from the rotation axis direction. On the other of the continuous surface and the one end surface, a second convex portion that protrudes toward one of the continuous surface and the one end surface is formed,
The second convex portion is a second annular portion that orbits the rotating shaft on the inner peripheral side of the first annular portion,
The circulation pump for a fuel cell system according to any one of claims 1 to 3 , wherein the first annular portion and the second annular portion have a labyrinth structure. The circulation pump for a fuel cell system according to any one of claims 1 to 4 , wherein the circulation pump is provided in a return channel on the cathode side.

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