JP2020097943A - Electric pump - Google Patents

Abstract

To provide an electric pump having a structure capable of suppressing torque efficiency from being decreased.SOLUTION: An inner rotor has a first hole part which is recessed from a surface at the other side in an axial direction to one side in the axial direction, and into which a shaft is inserted, and a second hole part which is recessed from a surface at the one side in the axial direction to the other side in the axial direction. A pump cover has a support projection projecting from a pump cover body to the other side in the axial direction, inserted into the second hole part, and supporting the inner rotor. There are provided: a first gap for allowing movement of the inner rotor in a radial direction to the shaft, between an outside surface in the radial direction of the shaft, and an inside surface in the radial direction of the first hole part; and a second gap for allowing movement of the inner rotor in the radial direction to the support projection, between an outside surface in the radial direction of the support projection, and an inside surface in the radial direction of the second hole part. The pump cover further has a fluid channel having a first opening opened in a gap in the radial direction between the inner rotor and an outer rotor, and a second opening connected to the first opening and opened in the second hole part.SELECTED DRAWING: Figure 3

Description

The present invention relates to an electric pump.

An electric oil pump including an inner rotor that is rotated by a pump rotation shaft from a drive unit and an outer rotor provided outside the inner rotor is known. For example, in the electric oil pump of Patent Document 1, a bearing portion that is inserted into a supported hole provided in the inner rotor is provided. The bearing portion supports the force that acts in the radial direction of the inner rotor due to the fluid pressure.

JP, 2014-126005, A

In the electric oil pump as described above, the inner surface of the supported hole of the inner rotor is pressed against the outer peripheral surface of the bearing portion by fluid pressure. Therefore, sliding friction may occur between the inner rotor and the bearing portion, which may hinder the rotation of the inner rotor. As a result, there is a problem that the torque efficiency of the electric oil pump is reduced.

In view of the above problems, it is an object of the present invention to provide an electric pump having a structure that can suppress a decrease in torque efficiency.

An electric pump according to one aspect of the present invention includes a shaft that rotates about a central axis, a motor unit that rotates the shaft, and a motor that is connected to the shaft and that is rotated by the motor unit. A pump portion, wherein the pump portion rotates with the rotation of the shaft, an annular outer rotor that surrounds a radially outer side of the inner rotor, and a surface on one side in the axial direction to the other side in the axial direction. A pump chamber that is recessed in a side, and that accommodates the inner rotor and the outer rotor; and a pump body that is open at both ends in the axial direction, through which the shaft passes, and has an opening on one axial side opening to the pump chamber. , A pump cover attached to one axial side of the pump body, an introduction oil passage that is connected to the pump chamber and introduces fluid into the pump chamber, and is connected to the pump chamber, and discharges fluid from the pump chamber A discharge oil passage, and the inner rotor has a first hole in which the shaft is inserted from the surface on the other side in the axial direction to the one side in the axial direction, and the other side in the axial direction from the surface on the one side in the axial direction. A second hole recessed in the pump cover, the pump cover being fixed to the pump body and covering one axial side of the pump chamber, and the other axial direction from the pump cover main body. And a supporting protrusion that is inserted into the second hole and that supports the inner rotor, and a radial outer surface of the shaft and a radial inner surface of the first hole. A first gap is provided between the first rotor and the inner rotor to allow radial movement of the inner rotor with respect to the shaft, and a radial outer surface of the support protrusion and a radial inner surface of the second hole portion. A second gap that allows the inner rotor to move in the radial direction with respect to the support protrusion, and the pump cover opens between the inner rotor and the outer rotor in the radial direction. It further has a fluid passage having one opening and a second opening connected to the first opening and opening to the second hole.

According to one aspect of the present invention, there is provided an electric pump having a structure capable of suppressing a decrease in torque efficiency.

FIG. 1 is a cross-sectional view showing the electric pump of this embodiment. FIG. 2 is a view showing the electric pump of the present embodiment and is a sectional view taken along line II-II in FIG. FIG. 3 is a cross-sectional view showing a portion of the electric pump of the present embodiment, and is a partially enlarged view of FIG. 1. FIG. 4 is a sectional view showing a second portion in the first groove portion of the present embodiment. FIG. 5 is a cross-sectional view showing a portion of the pump cover of this embodiment. FIG. 6 is a sectional view showing an electric pump which is another example of the present embodiment. FIG. 7 is a sectional view showing a portion of a pump cover which is another example of the present embodiment.

As shown in FIG. 1, an electric pump 10 according to the present embodiment is connected to a shaft 41 that rotates about a central axis J1, a motor unit 20 that rotates the shaft 41, and a shaft 41, and is rotated by the motor unit 20. And a pump section 30 driven via a shaft 41. In the present embodiment, the axial direction of the central axis J1 is, for example, the vertical direction.

In the following description, the direction parallel to the axial direction of the central axis J1 is simply referred to as "axial direction". The upper side in the axial direction of the central axis J1 is simply referred to as "upper side", and the lower side is simply referred to as "lower side". In the present embodiment, the lower side corresponds to one side in the axial direction and the upper side corresponds to the other side in the axial direction. Note that the up-down direction is merely a name used for description, and does not limit the actual positional relationship or direction. A radial direction centered on the central axis J1 is simply referred to as a “radial direction”, and a circumferential direction centered at the central axis J1 is simply referred to as a “circumferential direction”.

The shaft 41 has a shaft small diameter portion 41a having a small outer diameter. The shaft small diameter portion 41 a is located at the lower end of the shaft 41. As shown in FIG. 2, the shape of the cross section orthogonal to the axial direction of the shaft small diameter portion 41a is a shape in which a circle through which the central axis J1 passes is cut out by straight lines on both sides of the central axis J1. On the outer peripheral surface of the shaft small diameter portion 41a, two flat surfaces located with the central axis J1 therebetween are provided. The two flat surfaces on the outer peripheral surface of the shaft small diameter portion 41a are parallel to the axial direction and parallel to each other. Of the outer peripheral surface of the shaft small diameter portion 41a, the portion between the two flat surfaces in the circumferential direction is a curved surface along the circumferential direction.

As shown in FIG. 1, the motor unit 20 includes a rotor 40, a stator 50, and a motor housing 21. The rotor 40 is fixed to the outer peripheral surface of the shaft 41. The stator 50 is located radially outside the rotor 40. The motor housing 21 houses the rotor 40 and the stator 50.

The pump unit 30 is located below the motor unit 20. As shown in FIGS. 1 and 2, the pump unit 30 includes a pump body 31, an introduction oil passage 38a, a discharge oil passage 38b, an inner rotor 61, an outer rotor 62, and a pump cover 32. The pump body 31 is fixed to the lower end of the motor housing 21. The pump body 31 has a pump chamber 33. The pump chamber 33 is recessed upward from the lower surface of the pump body 31 and accommodates the inner rotor 61 and the outer rotor 62. As shown in FIG. 2, the shape of the pump chamber 33 as viewed in the axial direction is circular. As shown in FIG. 1, the pump body 31 has a through hole 31a. The through hole 31a is opened at both ends in the axial direction, the shaft 41 is passed through, and the lower opening is opened to the pump chamber 33. The pump body 31 is not shown in FIG.

As shown in FIG. 2, the introduction oil passage 38 a and the discharge oil passage 38 b are provided in the pump body 31. The introduction oil passage 38 a is connected to the pump chamber 33 and introduces a fluid into the pump chamber 33. The discharge oil passage 38b is connected to the pump chamber 33 and discharges the fluid from the pump chamber 33. The introduction oil passage 38a and the discharge oil passage 38b are arranged at positions that sandwich the shaft 41 in the radial direction. In the present embodiment, the introduction oil passage 38a and the discharge oil passage 38b open at the upper end of the pump chamber 33. In the present embodiment, the fluid introduced into the pump chamber 33 and discharged from the pump chamber 33 is, for example, oil.

The inner rotor 61 rotates as the shaft 41 rotates. The inner rotor 61 has an inner rotor body 61a and a protrusion 61b. The inner rotor body 61a is a gear having a plurality of tooth portions 61e on its radially outer surface. The inner rotor body 61 a is located inside the pump chamber 33. As shown in FIG. 1, the protrusion 61b protrudes upward from the inner rotor body 61a. The protrusion 61b is inserted into the lower end of the through hole 31a. As shown in FIG. 2, the outer shape of the protruding portion 61b as viewed in the axial direction is circular.

As shown in FIG. 1, the inner rotor 61 has a first hole portion 61c recessed downward from the upper surface and a second hole portion 61d recessed upward from the lower surface. The first hole portion 61c is provided in the protruding portion 61b. That is, the first hole portion 61c is recessed downward from the upper surface of the protruding portion 61b. The shaft 41 is inserted into the first hole portion 61c. More specifically, the lower end of the shaft small diameter portion 41a is inserted into the first hole portion 61c.

As shown in FIG. 2, the radially inner side surface of the first hole portion 61c has two flat surfaces that face each other in the radial direction with a gap therebetween. The two flat surfaces on the radially inner surface of the first hole portion 61c are parallel to the axial direction and parallel to each other. A portion of the radially inner surface of the first hole portion 61c between the two flat surfaces in the circumferential direction is a curved surface along the circumferential direction. The outer shape of the first hole portion 61c viewed in the axial direction is substantially similar to the outer shape of the cross section of the shaft small diameter portion 41a orthogonal to the axial direction. The first hole portion 61c is slightly larger than the shaft small diameter portion 41a. A first gap DP1 is provided between the outer peripheral surface of the shaft small diameter portion 41a, that is, the radial outer surface of the shaft 41 and the radial inner surface of the first hole portion 61c. The first gap DP1 allows the inner rotor 61 to move in the radial direction with respect to the shaft 41. The two flat surfaces of the shaft small diameter portion 41a are opposed to the two flat surfaces of the first hole portion 61c. When the shaft 41 rotates, the shaft 41 rotates relative to the inner rotor 61 within the range of the first gap DP1. Then, as shown in FIG. 2, the boundary portion between the flat surface and the curved surface of the shaft small diameter portion 41a makes line contact with the flat surface of the first hole portion 61c. As a result, relative rotation of the inner rotor 61 with respect to the shaft 41 is suppressed, and the inner rotor 61 rotates as the shaft 41 rotates.

As shown in FIG. 1, the second hole 61d is provided in the inner rotor body 61a. That is, the second hole 61d is recessed upward from the lower surface of the inner rotor body 61a. As shown in FIG. 2, the shape of the second hole 61d viewed in the axial direction is circular. The 1st hole part 61c and the 2nd hole part 61d are arrange|positioned concentrically centering|focusing on the central axis J1, and have overlapped in the axial direction. As shown in FIG. 1, in the present embodiment, the first hole portion 61c and the second hole portion 61d are connected to each other and form a through hole that penetrates the inner rotor 61 in the axial direction. The first hole portion 61c and the second hole portion 61d may be bottomed holes that are not connected to each other.

As shown in FIG. 2, the outer rotor 62 is a ring that surrounds the outer side of the inner rotor 61 in the radial direction. The outer rotor 62 is a gear having a plurality of tooth portions 62b on the radially inner surface. The outer rotor 62 is arranged in the pump chamber 33 so as to be rotatable around the rotation axis J2. The rotation axis J2 is parallel to the central axis J1. The rotating shaft J2 is arranged at a position distant from the central axis J1 in the radial direction. The tooth portion 61e of the inner rotor 61 and the tooth portion 62b of the outer rotor 62 mesh with each other at a portion in the circumferential direction. In FIG. 2, the tooth portion 61e of the inner rotor 61 and the tooth portion 62b of the outer rotor 62 mesh with each other in the lower portion. As a result, the outer rotor 62 rotates as the inner rotor 61 rotates.

In this embodiment, the inner rotor 61 and the outer rotor 62 rotate clockwise when viewed from above. In the following description, the side that advances clockwise in the circumferential direction when viewed from the upper side is referred to as the front side in the rotational direction, and the side that advances counterclockwise when viewed from the upper side in the circumferential direction is referred to as the rear side in the rotational direction. A side located on the front side in the rotation direction of the meshing portion 63 with a virtual line C1 connecting the meshing portion 63 and the central axis J1 where the tooth portion 61e of the inner rotor 61 meshes with the tooth portion 62b of the outer rotor 62 as a boundary. That is, the area on the left side of the virtual line C1 in FIG. A side located on the rear side in the rotation direction of the meshing portion 63 with the virtual line C1 as a boundary, that is, a region on the right side of the virtual line C1 in FIG.

The introduction oil passage 38a is connected to the pump chamber 33 in the introduction area AR1, and the discharge oil passage 38b is connected to the pump chamber 33 in the discharge area AR2. In the introduction region AR1, the radial gap between the inner rotor 61 and the outer rotor 62 becomes larger toward the front side in the rotation direction. As a result, the fluid flows from the introduction oil passage 38a into the radial gap between the inner rotor 61 and the outer rotor 62. In the discharge area AR2, the radial gap between the inner rotor 61 and the outer rotor 62 becomes smaller toward the front side in the rotation direction. As a result, the fluid flowing into the radial gap between the inner rotor 61 and the outer rotor 62 is pushed out and discharged from the discharge oil passage 38b. In this way, the pump portion 30 sends the fluid from the introduction oil passage 38a to the discharge oil passage 38b. The pressure of the fluid in the ejection area AR2 is higher than the pressure of the fluid in the introduction area AR1. That is, the fluid is pressurized by the pump unit 30 and sent from the introduction area AR1 to the ejection area AR2.

As shown in FIG. 1, the pump cover 32 is attached to the lower side of the pump body 31. The pump cover 32 has a pump cover body 32a and a support protrusion 32b. The pump cover body 32a has a lid shape that expands in the radial direction. The pump cover body 32a is fixed to the pump body 31 and covers the lower side of the pump chamber 33. The support protrusion 32b projects upward from the pump cover body 32a and is inserted into the second hole 61d to support the inner rotor 61. As shown in FIG. 3, the radial movement of the inner rotor 61 with respect to the support protrusion 32b does not occur between the radial outer surface of the support protrusion 32b and the radial inner surface of the second hole 61d. A permissible second gap DP2 is provided. The support protrusion 32b functions as a bearing for the inner rotor 61. As a result, the inner rotor 61 can be supported at a position away from the shaft 41, so that the inclination of the inner rotor 61 with respect to the shaft 41 can be reduced.

As shown in FIG. 2, the pump cover 32 further includes a fluid passage 70. As shown in FIG. 3, the fluid passage 70 has a first opening 73 and a second opening 74. The first opening 73 is open between the inner rotor 61 and the outer rotor 62 in the radial direction. The second opening 74 is connected to the first opening 73 and opens in the second hole 61d. Therefore, the fluid between the inner rotor 61 and the outer rotor 62 flows into the fluid passage 70 from the first opening 73. The fluid that has flowed into the fluid passage 70 flows from the second opening 74 into the second hole 61d. This makes it possible to increase the amount of fluid flowing between the radially inner surface of the second hole portion 61d and the radially outer surface of the support protrusion 32b. Therefore, the fluid serves as a lubricant to reduce the sliding friction that occurs when the radially inner surface of the second hole 61d is pressed against the radially outer surface of the support protrusion 32b. As a result, it is possible to suppress the rotation of the inner rotor 61 from being hindered by the sliding friction, and it is possible to prevent the torque efficiency of the electric pump 10 from decreasing.

The fluid passage 70 has a first groove portion 71 and a second groove portion 72. The first groove portion 71 is a groove recessed downward from the upper surface of the pump cover body portion 32a. The first groove portion 71 has a first opening portion 73 and a second opening portion 74. Therefore, by forming a groove on the upper surface of the pump cover main body portion 32a, a part of the fluid passage 70 can be formed, and the fluid can be guided into the second hole portion 61d. Therefore, the structure of the fluid passage 70 can be simplified and the fluid passage 70 can be easily created.

As shown in FIG. 2, the first groove portion 71 is provided in the ejection area AR2. The first groove portion 71 is connected to the discharge oil passage 38b via the pump chamber 33. In the present embodiment, the first opening portion 73 of the first groove portion 71 has an opening in a portion that is connected to the discharge oil passage 38b, between the inner rotor 61 and the outer rotor 62 in the radial direction. Therefore, the fluid pressurized by the pump unit 30 flows into the fluid passage 70 through the first opening 73. Thereby, the fluid easily flows in the fluid passage 70 toward the second hole 61d, and the fluid can further flow into the second hole 61d. Therefore, it is possible to further suppress that the rotation of the inner rotor 61 is hindered by the sliding friction, and it is possible to further suppress that the torque efficiency of the electric pump 10 is reduced.

The first groove portion 71 has a first portion 71a and a second portion 71b. The first portion 71a extends along the circumferential direction. The radial dimension of the first portion 71a becomes smaller toward the front side in the rotation direction. As shown in FIGS. 2 and 3, the first portion 71a is arranged at a position that axially overlaps with a radial gap between the inner rotor 61 and the outer rotor 62. That is, the first portion 71 a has the first opening 73. The second portion 71b extends in the radial direction from the first portion 71a to the outer peripheral surface of the support protrusion 32b. That is, the radially inner end of the first groove portion 71 is located on the outer peripheral surface of the support protrusion 32b.

As described above, by providing the first portion 71a, a part of the fluid pressurized by the pump portion 30 can be released to the first portion 71a, and the fluid can be smoothly discharged from the discharge oil passage 38b. be able to. On the other hand, the second portion 71b extending in the radial direction from the first portion 71a can send a part of the fluid flowing into the first portion 71a into the second hole portion 61d. As a result, the amount of the fluid flowing into the second hole portion 61d can be easily adjusted appropriately while smoothly discharging the fluid to the discharge oil passage 38b. Therefore, it is possible to reduce the amount of fluid leaking from the second hole 61d to the introduction area AR1 while reducing the sliding friction between the inner rotor 61 and the support protrusion 32b.

As shown in FIG. 2, the second portion 71b is connected to the center of the first portion 71a in the circumferential direction. The circumferential center of the first portion 71a is the circumferential center of the ejection area AR2. The shape of the second portion 71b viewed from the upper side is a rectangular shape that is long in the radial direction. As shown in FIG. 4, the cross-sectional shape of the second portion 71b orthogonal to the radial direction is a substantially quadrangular shape. The upper corner portion 71c of the second portion 71b is a convex curved surface that connects the side surface of the second portion 71b and the upper surface of the pump cover body portion 32a. The lower corner portion 71d of the second portion 71b has a concave curved surface shape that connects the side surface of the second portion 71b and the bottom surface of the second portion 71b. The axial dimension of the second portion 71b is, for example, the same as the axial dimension of the first portion 71a. The axial dimension of the first portion 71a and the axial dimension of the second portion 71b may be different. The axial dimension of the second portion 71b may be smaller than the axial dimension of the first portion 71a.

As shown in FIG. 3, the second groove portion 72 is a groove recessed radially inward from the radially outer surface of the support protrusion 32b. The second groove portion 72 extends upward from the radial inner end of the first groove portion 71, that is, the radial inner end of the second portion 71b. By providing the second groove portion 72, the fluid flowing into the second hole portion 61d from the second opening portion 74 can be guided upward along the second groove portion 72. This makes it easier to guide the fluid between the inner rotor 61 and the support protrusions 32b, and further reduces the sliding friction between the inner rotor 61 and the support protrusions 32b. Therefore, it is possible to further suppress the reduction in torque efficiency of the electric pump 10.

As shown in FIG. 5, the second groove portion 72 extends linearly in the axial direction from the lower end to the upper end of the support protrusion 32b. The second groove 72 is opened upward. The second groove portion 72 is provided in the support projection portion 32b in a direction orthogonal to both the virtual line C1 and the central axis J1, that is, an end portion on the ejection area AR2 side in the left-right direction in FIG. The lower end of the second groove portion 72 is connected to the radially inner end of the second portion 71b. As shown in FIG. 5, the shape of the second groove portion 72 viewed in the radial direction is a rectangular shape that is long in the axial direction. Although illustration is omitted, the cross-sectional shape of the second groove portion 72 orthogonal to the axial direction is the same as the cross-sectional shape of the second portion 71b shown in FIG. 4 orthogonal to the radial direction. The radially inner surface of the second hole portion 61d is pressed against both circumferential edges of the second groove portion 72.

As shown in FIG. 2, the pump cover 32 further includes a third groove portion 80 recessed downward from the upper surface of the pump cover body portion 32a. The third groove portion 80 is arranged on the opposite side in the radial direction with the first portion 71a sandwiching the shaft 41. The third groove portion 80 is provided in the introduction area AR1. The third groove portion 80 extends along the circumferential direction. The radial dimension of the third groove portion 80 increases toward the front side in the rotation direction. The third groove portion 80 is arranged at a position that axially overlaps with a radial gap between the inner rotor 61 and the outer rotor 62. The third groove 80 is connected to the introduction oil passage 38a via the pump chamber 33.

The present invention is not limited to the above embodiment, and other configurations can be adopted. In the following description, configurations similar to those described above may be omitted by appropriately assigning the same reference numerals.

The electric pump may have a structure such as the electric pump 110 shown in FIGS. 6 and 7. The pump body 31 is not shown in FIG. In the first groove portion 171 of the fluid passage 170 provided in the pump cover 132 shown in FIG. 6, the second portion 171b is connected to the end portion of the first portion 71a on the rear side in the rotation direction. The fluid pressure in the ejection area AR2 is higher toward the rear side in the rotation direction. Therefore, according to this configuration, it is easier to allow the fluid to flow into the second hole portion 61d via the second portion 171b. The second portion may be connected to the end of the first portion 71a on the front side in the rotation direction. In this case, compared to the case shown in FIGS. 2 and 6, the amount of fluid flowing into the second hole 61d can be reduced, and the amount of fluid leaking from the second hole 61d to the introduction region AR1 can be reduced. Thus, by changing the connection position of the second portion, the amount of fluid flowing into the second hole 61d can be adjusted.

As shown in FIG. 7, the upper end portion of the second groove portion 172 in the fluid passage 170 is located below the upper end portion of the support protrusion 132b. According to this configuration, it is difficult for the fluid to wrap around to the upper side of the support protrusion 132b. Therefore, it is possible to prevent the fluid flowing into the second hole 61d from moving to the introduction area AR1 side through the upper side of the support protrusion 132b, and to prevent the fluid from leaking to the introduction area AR1. The second groove portion 172 has a spiral shape. Therefore, even if the second groove 172 is provided, it is possible to suppress an increase in sliding resistance between the support protrusion 132b and the second hole 61d. The second groove portion 172 extends toward the front side in the rotation direction from the lower side toward the upper side.

The second groove portion has a shape that extends linearly along the axial direction like the second groove portion 72 shown in FIG. 5, but has an upper end positioned below the upper end of the support protrusion 32b. May be. Further, the second groove portion may not be provided. In addition, the first portion 71a may not be provided. Further, the fluid passage need not be a groove, and may be a passage provided in the pump cover body. The fluid passage may be provided in the introduction area AR1. Moreover, the third groove portion 80 may not be provided. It should be noted that the respective configurations described above can be appropriately combined within a range in which they do not contradict each other.

10, 110... Electric pump, 20... Motor part, 30... Pump part, 31... Pump body, 31a... Through hole, 32, 132... Pump cover, 32a... Pump cover main body part, 32b, 132b... Support protrusion part, 33 ... Pump chamber, 38a... Introducing oil passage, 38b... Discharging oil passage, 40... Rotor, 41... Shaft, 61... Inner rotor, 61c... First hole portion, 61d... Second hole portion, 62... Outer rotor, 70, 170... Fluid passage, 71, 171, 1st groove part, 71a... 1st part, 71b, 171b... 2nd part, 72, 172... 2nd groove part, 73... 1st opening part, 74... 2nd opening part, DP1 ...First gap, DP2...second gap, J1...central axis

Claims (6)

A shaft that rotates around the central axis,
A motor unit for rotating the shaft,
A pump unit connected to the shaft and driven via the shaft rotated by the motor unit;
Equipped with
The pump section is
An inner rotor that rotates with the rotation of the shaft,
An annular outer rotor surrounding the radially outer side of the inner rotor,
A pump chamber accommodating the inner rotor and the outer rotor;
A pump cover disposed on at least one axial side of the inner rotor and the outer rotor;
An introduction oil passage that is connected to the pump chamber and introduces a fluid into the pump chamber,
A discharge oil passage that is connected to the pump chamber and discharges a fluid from the pump chamber,
The inner rotor is
A first hole portion in which the shaft is inserted from the surface on the other side in the axial direction to the one side in the axial direction;
A second hole recessed from the surface on one side in the axial direction to the other side in the axial direction;
Have
The pump cover is
A pump cover main body that covers one side in the axial direction of the inner rotor and the outer rotor,
A support protrusion that protrudes from the pump cover body to the other side in the axial direction and is inserted into the second hole, and supports the inner rotor;
Have
A first gap is provided between the radially outer surface of the shaft and the radially inner surface of the first hole to allow radial movement of the inner rotor with respect to the shaft.
A second gap is provided between the radially outer surface of the support protrusion and the radially inner surface of the second hole to allow radial movement of the inner rotor with respect to the support protrusion. The
The pump cover has a fluid passage having a first opening opening between the inner rotor and the outer rotor in a radial direction and a second opening connected to the first opening and opening to the second hole. In addition,
An introduction region for introducing a fluid into the inner rotor and the outer rotor,
A discharge region for discharging fluid from the inner rotor and the outer rotor,
The first opening portion is opened in a portion connected to the discharge oil passage, in a radial direction between the inner rotor and the outer rotor,
The fluid passage has a first groove portion that is recessed from the surface on the other axial side of the pump cover main body portion to one side in the axial direction and that has the first opening portion and the second opening portion,
An electric pump in which the first groove portion is provided in the discharge area.

The first groove portion,
A first portion having the first opening and extending in the circumferential direction;
A second portion extending in the radial direction from the first portion to the outer peripheral surface of the support protrusion;
The electric pump according to claim 1, further comprising: The radially inner end of the first groove portion is located on the outer peripheral surface of the support protrusion,
The fluid passage has a second groove portion that is recessed radially inward from the radially outer surface of the support protrusion,
The electric pump according to claim 1 or 2, wherein the second groove portion extends from the radially inner end of the first groove portion to the other side in the axial direction. The electric pump according to claim 3, wherein an end of the second groove portion on the other side in the axial direction is located on one side in the axial direction than an end of the support protrusion on the other side in the axial direction. The electric pump according to claim 3, wherein the second groove portion has a spiral shape. The electric pump according to claim 1, wherein the shaft has at least two flat surfaces in a cross section orthogonal to the axial direction at a lower end on one side in the axial direction.

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