JP2013247692A - Motor pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor pump having a rotor and an impeller arranged side by side in the rotation axis direction of the rotor, in which displacement of the rotor and impeller due to pressure difference of fluid in a casing is reduced.SOLUTION: A motor pump 10 includes a stator 44 arranged on the outer peripheral side of a rotor 42. The stator 44 and rotor 42 always loads a force for reducing the displacement of a rotating body 60, occurring due to the pressure difference on the low pressure side where the pressure of the fluid in a fluid path 24 is low during operation of the motor pump 10 and the high pressure side where the pressure of the fluid is high, to the rotating body 60.

Description

  The present specification relates to an electric pump. In particular, a technique for an electric pump in which a rotor and an impeller are arranged side by side in the rotation axis direction of the rotor is disclosed.

  Patent Document 1 discloses a DC pump in which an impeller configured integrally with a magnet rotor is disposed outside a stator. The impeller is disposed outside the outer periphery of the magnet rotor. The DC pump sucks the fluid into the casing of the DC pump by the rotation of the impeller and pressurizes the fluid, and then discharges the fluid outside the casing. The DC pump further includes a magnetic body disposed on the inner side and the outer side of the magnet rotor. The magnetic body loads the impeller with a magnetic force that balances the force applied to the impeller by the pressure difference of the fluid in the casing. As a result, the impeller is prevented from contacting the casing.

JP 2004-176552 A

  In Patent Literature 1, an electric pump having a configuration in which a rotor and an impeller (impeller in Patent Literature 1) are arranged side by side in the rotation axis direction of the rotor is not considered. In this specification, in the electric pump in which the rotor and the impeller are arranged side by side in the rotation axis direction of the rotor, the electric pump for reducing the displacement of the rotor and the impeller due to the pressure difference of the fluid in the casing is provided. provide.

  The present specification discloses an electric pump including a rotating body, a stator, and a casing. The rotating body includes a rotor and an impeller arranged side by side with the rotor in the rotation axis direction of the rotor. The stator is disposed on the outer peripheral side of the rotor. The casing has a fluid path formed along the outer periphery of the impeller and accommodates the rotating body and the stator. The electric pump includes a load unit. The load portion is configured to reduce the displacement of the rotating body caused by the pressure difference between the low pressure side where the fluid pressure in the fluid path is low and the high pressure side where the fluid pressure is high when the electric pump is in operation. During operation, the rotating body is always loaded.

  In the electric pump, when the impeller rotates, the fluid is sucked into the casing and flows in the fluid path. The fluid in the fluid path is pressurized by the rotation of the impeller and discharged out of the fluid path. The fluid is pressurized while flowing in the fluid path. For this reason, in the fluid path, the pressure of the downstream fluid is higher than the pressure of the upstream fluid. Therefore, when the electric pump is operated, a fluid pressure difference is generated in the fluid path. Due to the pressure difference of the fluid, the fluid loads the rotating body with a force for displacing the rotating body.

  In the above-described electric pump, the load unit constantly loads the rotating body with a force for reducing the displacement of the rotating body due to the pressure difference of the fluid when the electric pump is operated. According to this configuration, it is possible to reduce the displacement of the rotating body due to the pressure difference of the fluid in the fluid path. Thereby, a contact with a rotary body and a casing is suppressed and the fall of the pump efficiency by the contact with a rotary body and a casing is suppressed.

The schematic longitudinal cross-sectional view of the electric pump of 1st Example is shown. Sectional drawing of the II-II cross section of FIG. 1 is shown. The figure which looked at the stator from the upper part of Drawing 1 is shown. The longitudinal cross-sectional view of the stator of 2nd Example is shown. The figure for demonstrating the core of 3rd Example is shown. The figure for demonstrating the core of 4th Example is shown. The figure for demonstrating the core of 5th Example is shown. Sectional drawing of the VIII-VIII cross section of FIG. 7 is shown. The schematic longitudinal cross-sectional view of the electric pump of 6th Example is shown. The schematic longitudinal cross-sectional view of the electric pump of 7th Example is shown. The schematic longitudinal cross-sectional view of the electric pump of 8th Example is shown. Sectional drawing of the II-II cross section of FIG. 1 in the electric pump of 9th Example is shown. The schematic longitudinal cross-sectional view of the electric pump of 10th Example is shown. The enlarged view of the XIV part of FIG. 1 which shows the structure of the permanent magnet of 11th Example is shown. The structure of the core of a modification is shown.

  First, the features of the embodiments described below are listed. Note that the features listed here are all independently effective.

(Feature 1) The load unit may include at least one of a first configuration and a second configuration. The first configuration may be a configuration in which the resultant magnetic force applied to the impeller side end of the rotor is directed from the low pressure side to the high pressure side. The second configuration may be a configuration in which the resultant magnetic force applied to the end of the rotor opposite to the impeller is directed from the high pressure side to the low pressure side.

  During the operation of the electric pump, the force due to the pressure difference in the fluid path strongly acts on the impeller of the rotating body. As a result, due to the pressure difference of the fluid, a force is applied to the rotating body so that the impeller rotates in the direction in which the impeller moves from the high pressure side to the low pressure side relative to the rotor. According to said structure, the force for reducing the displacement (namely, rotation) of a rotary body can be appropriately loaded to a rotary body by at least one structure of a 1st structure and a 2nd structure. .

(Feature 2) The load portion may include a stator and a rotor. The first configuration includes a configuration in which the area of the stator extending along the impeller side end of the rotor on the high pressure side is larger than the area of the stator extending along the end of the rotor impeller side on the low pressure side. Also good. In the second configuration, the area of the stator extending along the end opposite to the rotor impeller on the low pressure side is larger than the area of the stator extending along the end opposite to the rotor impeller on the high pressure side. May be included.

  According to this configuration, the load unit can realize the first configuration and the second configuration using the stator and the rotor. In the first configuration, the magnetic force toward the high pressure side can be increased at the impeller side end of the rotor. In the second configuration, the magnetic force toward the low pressure side can be increased at the end of the rotor opposite to the impeller. As a result, the force for reducing the displacement of the rotating body can be appropriately applied to the rotating body. Further, it is not necessary to provide a dedicated configuration for generating a force for reducing the displacement of the rotating body.

(Characteristic 3) The first configuration is such that the impeller side end of the high pressure side stator portion located on the high pressure side of the stator rotates more than the impeller side end of the low pressure side stator portion located on the low pressure side of the stator. The structure extended to the impeller side along the axial direction may be included. In the second configuration, the end portion on the opposite side of the impeller of the low-pressure side stator portion extends to the opposite side of the impeller along the rotational axis direction from the end portion on the opposite side of the impeller of the high-pressure side stator portion. A configuration may be included.

  During operation of the electric pump, a voltage is applied to the stator, so that a magnetic force directed to the stator is loaded on the rotor. According to said 1st structure, the magnetic force which goes to the high voltage | pressure side from a low voltage | pressure side can be loaded to a rotary body in the edge part by the side of the impeller of a rotor. Moreover, according to said 2nd structure, the magnetic force which goes to a low voltage | pressure side from a high voltage | pressure side can be loaded to a rotary body in the edge part on the opposite side to the impeller of a rotor. Thereby, the force for reducing the displacement of the rotating body can be appropriately applied to the rotating body.

(Feature 4) In the first configuration, the length of the high-pressure side stator portion extending along the outer peripheral surface of the rotor when the cross section orthogonal to the rotation axis is viewed at the impeller side end of the rotor A structure longer than the length of the low-pressure side stator portion extending along the outer peripheral surface may be included. In the second configuration, the length of the low-pressure side stator portion that extends along the outer peripheral surface of the rotor when viewed in a cross section orthogonal to the rotation axis at the end opposite to the impeller of the rotor is the outer peripheral surface of the rotor. The structure may be longer than the length of the high-pressure-side stator portion extending along the axis.

(Feature 5) The load portion may include a stator and a rotor. The first configuration is such that, at the impeller side end of the rotor, the size of the average gap between the high pressure side stator portion located on the high pressure side of the stator and the rotor is low pressure side stator portion located on the low pressure side of the stator. A configuration smaller than the size of the average gap with the rotor may be included. In the second configuration, the average clearance between the low-pressure side stator portion and the rotor is smaller than the average clearance between the high-pressure side stator portion and the rotor at the end opposite to the impeller of the rotor. May be included.

  In the characteristics 4 and 5, according to the first configuration, a magnetic force directed from the low pressure side to the high pressure side can be applied to the rotating body at the end portion on the impeller side of the rotor. Moreover, according to said 2nd structure, the magnetic force which goes to a low voltage | pressure side from a high voltage | pressure side can be loaded to a rotary body in the edge part on the opposite side to the impeller of a rotor. Thereby, the force for reducing the displacement of the rotating body can be appropriately applied to the rotating body.

(Feature 6) The load section may include a first magnetic body and a second magnetic body. The first magnetic body may be attached to the rotating body and make a round in the circumferential direction of the rotating body. The second magnetic body may be attached to a region of the casing that faces the first magnetic body. The second magnetic body is disposed on the high-pressure side, and generates a magnetic force in a direction to draw the first magnetic body to the second magnetic body side between the first magnetic body and the low-pressure side. And at least one magnetic body that generates a magnetic force in the direction of pressing the first magnetic body to the opposite side of the second magnetic body with the first magnetic body. It may be.

  According to this configuration, the force for reducing the displacement of the rotating body can be appropriately applied to the rotating body by the magnetic force generated by the first magnetic body and the second magnetic body.

(Feature 7) The first magnetic body may be attached to the impeller.

  According to this configuration, the magnetic force generated by the first magnetic body and the second magnetic body can be directly applied to the impeller on which the force due to the pressure difference of the fluid strongly acts.

(Feature 8) The 1st magnetic body may be attached to the end surface on the opposite side to the impeller of a rotor.

  According to this configuration, a force for reducing the displacement of the rotating body can be appropriately applied to the rotating body by a configuration other than the rotor and the stator.

(Feature 9) The load portion may include a peripheral wall that covers the stator and surrounds the rotor. The fluid path may communicate with a gap between the rotor and the peripheral wall. The load part has a configuration in which the gap between the rotor on the impeller side of the rotor and the peripheral wall is larger than the gap between the rotor on the high pressure side and the peripheral wall, and a high pressure at the end opposite to the impeller of the rotor. The gap between the rotor on the side and the peripheral wall may have at least one of the configurations larger than the gap between the rotor on the low pressure side and the peripheral wall.

  In this configuration, the fluid flows into the gap between the rotor and the peripheral wall, and flows through the gap between the rotor and the peripheral wall. When the fluid flows from a region where the gap between the rotor and the peripheral wall is relatively small into a region where the gap between the rotor and the peripheral wall is relatively large, the pressure of the fluid increases. According to the former configuration, due to the pressure of the fluid existing in the gap between the rotor and the peripheral wall, a force from the low pressure side to the high pressure side is applied to the rotating body at the impeller side end of the rotor. Further, according to the latter configuration, the force from the high pressure side to the low pressure side is applied to the rotating body at the end opposite to the impeller of the rotor due to the pressure of the fluid existing in the gap between the rotor and the peripheral wall. Is done. As a result, the force for reducing the displacement of the rotating body can be appropriately applied to the rotating body.

(Characteristic 10) The load portion may include an opposing wall facing the end surface on the opposite side of the rotor impeller. The fluid path may be in communication with a gap between the rotor and the opposing wall. The load portion may have a configuration in which a gap between the opposite end surface of the low pressure side rotor impeller and the opposing wall is larger than a clearance between the opposite end surface of the high pressure side rotor and the opposing wall. .

  In this configuration, the fluid flows into the gap between the rotor and the opposing wall and flows through the gap between the rotor and the opposing wall. When the fluid flows from a region where the gap between the rotor and the facing wall is relatively small into a region where the gap between the rotor and the facing wall is relatively large, the pressure of the fluid increases. According to said structure, the force for reducing the displacement of a rotary body can be appropriately loaded to a rotary body with the pressure of the fluid which exists in the clearance gap between a rotor and an opposing wall.

(First embodiment)
(Configuration of electric pump 10)
The electric pump 10 is installed in an engine room of an automobile and used to circulate cooling water that cools an engine, an inverter, and the like. As shown in FIG. 1, the electric pump 10 includes a pump unit 20 and a motor unit 40. The outer periphery of the electric pump 10 is composed of a casing 12. The casing 12 includes an upper casing 28 and a lower casing 46.

(Configuration of pump unit 20)
The pump unit 20 is provided in the upper casing 28. In the pump unit 20, a suction port 22, a discharge port 23 (see FIG. 2), and a cooling water path 24 are formed by an upper casing 28. Moreover, the pump unit 20 includes an impeller 26 of a rotating body 60 described later. The impeller 26 is accommodated in the upper casing 28. As shown in FIG. 2, the impeller 26 has a circular shape when viewed from above in FIG. When electric power is supplied to the electric pump 10, the impeller 26 rotates in the rotation direction R. A plurality of blades are formed on the upper surface of the impeller 26 at regular intervals. A cooling water path 24 is formed between the outer peripheral surface of the impeller 26 and the inner peripheral surface of the upper casing 28.

  The cooling water path 24 is formed along the outer periphery of the impeller 26 (that is, the rotation direction R). When viewed in a cross section parallel to the XY plane, the inner peripheral surface of the upper casing 28 is gradually separated from the outer periphery of the impeller 26 as it proceeds in the rotation direction R. For this reason, the path area of the cooling water path 24 gradually increases in accordance with the rotation direction R. A discharge port 23 is connected to a position where the path area of the cooling water path 24 is maximum. The discharge port 23 extends in the tangential direction of the cooling water passage 24. The cooling water path 24 makes a round in the circumferential direction of the impeller 26, and the cooling water path 24 with the smallest path area is connected to the position where the path area of the cooling water path 24 is the largest.

  As shown in FIG. 1, a suction port 22 is further connected to the cooling water path 24. The suction port 22 is formed at the upper end of the pump unit 20. The suction port 22 extends in a direction in which a rotating shaft (hereinafter simply referred to as “rotating shaft”) of the rotating body 60 extends.

(Configuration of motor unit 40)
The motor unit 40 is disposed below the pump unit 20. The motor unit 40 is formed in the lower casing 46. The motor unit 40 constitutes a brushless motor. The motor unit 40 includes a shaft 16, a rotor 42 of the rotating body 60, and a stator 44. The lower end of the shaft 16 is fixed to the lower casing 46. The shaft 16 extends in the vertical direction in the casing 12, and the tip thereof reaches the pump unit 20. A rotating body 60 is rotatably attached to the shaft 16. The rotating body 60 includes an impeller 26 and a rotor 42. The rotor 42 is disposed below the impeller 26 with a space therebetween. The rotor 42 is arranged side by side in the impeller 26 and the rotation axis direction of the rotating body 60 (that is, the rotation axis direction of the rotor 42 (hereinafter referred to as “Z-axis direction”)). The rotor 42 and the impeller 26 rotate around the axis of the shaft 16. The rotor 42 is accommodated in the lower casing 46. The rotor 42 has a cylindrical shape. The rotor 42 includes a plurality of permanent magnets 52. The plurality of permanent magnets 52 are arranged so as to have a plurality of magnetic poles in the circumferential direction. The impeller 26 and the rotor 42 are integrally formed. For this reason, when the rotor 42 rotates, the impeller 26 also rotates.

  Below the motor unit 40, a control circuit 18 that controls power supply to the stator 44 is disposed. The control circuit 18 is connected to an external power source (not shown) (for example, a battery mounted on the vehicle) via the terminal 14. The control circuit 18 supplies power supplied from an external power source to the motor unit 40.

(Configuration of stator 44)
The stator 44 is disposed on the outer peripheral side of the rotor 42. In FIG. 1, a longitudinal section of the stator 44 is shown, but the parallel oblique lines are omitted for easy viewing of the drawing. The stator 44 is accommodated in the lower casing 46. The stator 44 includes two cores 44a and 44b. The two cores 44 a and 44 b are covered with a resin layer that constitutes the lower casing 46. The lower casing 46 is opposed to the outer peripheral surface 42a of the rotor 42, and includes a peripheral wall 46a surrounding the rotor 42 and an opposing wall 46b facing the end surface 42b opposite to the impeller 26 of the rotor 42. The rotor 42 is disposed with a gap between the peripheral wall 46a and the opposing wall 46b. The gap between the rotor 42 and the peripheral wall 46a and the gap between the rotor 42 and the opposing wall 46b communicate with the pump unit 20 (that is, the cooling water path 24).

  Each of the two cores 44a and 44b is configured by stacking a plurality of core plates 48 in the Z-axis direction. However, the number of core plates 48 included in the core 44b located on the side where the path area of the cooling water path 24 is relatively large (that is, the left side in FIG. 1) is the side where the path area of the cooling water path 24 is relatively small ( That is, the number of core plates 48 included in the core 44a located on the right side in FIG. That is, the length of the core 44b in the Z-axis direction is longer than the length of the core 44a in the Z-axis direction. Specifically, in the Z-axis direction, the position of the end of the core 44b opposite to the pump portion 20 (ie, the impeller 26) is located at the same position as the end of the core 44a opposite to the impeller 26, while the core 44b The position of the end on the impeller 26 side is located closer to the impeller 26 than the end on the impeller 26 side of the core 44a. In other words, the end of the core 44a on the impeller 26 side extends toward the impeller 26 along the Z-axis direction from the end of the core 44b on the impeller 26 side. In the Z-axis direction, the end of the core 44b on the impeller 26 side is located at substantially the same position as the end of the rotor 42 on the impeller 26 side.

  As shown in FIG. 3, the core 44a includes three teeth 70 arranged in the Y direction. A coil 50 is wound around each tooth 70 via a resin bobbin. The configuration of the core 44b is the same as that of the core 44a except for the number of core plates 48.

(Operation of electric pump 10)
Next, the operation of the electric pump 10 will be described. When electric power is supplied to the electric pump 10 from the external power source via the terminal 14, the control circuit 18 applies a voltage to the coils 50 wound around each of the six teeth 70 in a predetermined order. Apply. As a result, the voltage of the same phase (that is, any one of U, V, and W phases) is applied to two teeth that face each other across the shaft 16 among the six teeth 70. That is, the motor unit 40 is a three-phase AC motor.

  When a voltage is applied to the coil 50, the teeth 70 around which the coil 50 is wound are magnetized. When the teeth 70 are magnetized, the permanent magnets 52 of the rotor 42 are attracted to the magnetized teeth 70. Thereby, the rotating body 60 rotates around the shaft 16. The cooling water is sucked into the pump unit 20 from the suction port 22 by the rotation of the impeller 26 and flows into the cooling water path 24. As shown in FIG. 2, the cooling water in the cooling water path 24 is increased in pressure by the rotation of the impeller 26, flows in the cooling water path 24 in the rotation direction R, and is discharged out of the cooling water path 24 from the discharge port 23. The Note that “when the electric pump 10 is operating” means when electric power is supplied to the coil wire 50 and cooling water is discharged outside the cooling water path 24 by the rotation of the rotating body 60. Note that “when the electric pump 10 is operating” does not simply mean the entire period during which power is supplied to the coil wire 50.

  As a result, when the electric pump 10 is operated, the pressure of the cooling water on the downstream side is higher than the pressure of the cooling water on the upstream side in the cooling water passage 24, and a pressure difference is generated in the cooling water. Specifically, as shown in FIG. 2, the cooling water pressure in the cooling water path 24 increases in the rotation direction R, and the cooling water pressure in the high pressure region HP is higher than the cooling water pressure in the low pressure region LP. Quite expensive. Due to the pressure difference between the pressure of the cooling water in the high pressure region HP and the pressure of the cooling water in the low pressure region LP, the impeller 26 is referred to as a force from the high pressure region HP to the low pressure region LP (hereinafter simply referred to as “pressure difference”). ) Is loaded.

  A force due to a pressure difference is applied to the rotating body 60 near the upper end of FIG. That is, the rotating body 60 has a direction in which the impeller 26 moves from the high pressure region HP to the low pressure region LP with respect to the rotor 42 about the axis passing through the intermediate position of the rotating body 60 in the Z-axis direction (FIG. 1). Force to rotate clockwise).

  As shown in FIG. 1, in the electric pump 10, the core 44 b located on the side where the path area of the cooling water path 24 is relatively large, that is, on the high pressure region HP side, has a path area of the cooling water path 24. It extends to the impeller 26 side from the core 44a located on the small side, that is, the low pressure region LP side. For this reason, when the teeth 70 are magnetized when the electric pump 10 is operated, the magnetic force toward the high pressure region HP is larger than the magnetic force toward the low pressure region LP at the end of the rotor 42 on the impeller 26 side. As a result, the resultant magnetic force applied to the end of the rotor 42 on the impeller 26 side is directed from the low pressure region LP side to the high pressure region HP side. According to this configuration, a force for reducing the displacement of the rotating body 60 (that is, rotation due to the pressure difference of the cooling water) can be appropriately applied to the rotating body 60. Further, since the voltage is supplied to the coil 50 when the electric pump 10 is operated, the resultant magnetic force is always loaded on the rotating body 60 when the electric pump 10 is operated. According to this configuration, it is possible to reduce the displacement of the rotating body 60 due to the pressure difference of the cooling water in the cooling water passage 24. Thereby, contact with the rotary body 60 and the casing 12 is suppressed, and the fall of the pump efficiency of the electric pump 10 is suppressed. In addition, since the resultant force of the magnetic force is constantly loaded on the rotating body 60 when the electric pump 10 is operated, the force applied to the rotating body 60 is changed when the electric pump 10 is operated. Can be prevented from becoming unstable.

  Further, the resultant magnetic force is generated by the stator 44 and the rotor 42. According to this configuration, it is not necessary to provide a dedicated configuration for generating a force for reducing the displacement of the rotating body 60. The rotor 42 and the stator 44 are examples of the “load portion”.

(Second embodiment)
Differences from the first embodiment will be described with reference to FIG. In FIG. 4, only the outer shape of the rotating body 60 is shown, but actually, it has the same configuration as that of the first embodiment. The stator 144 includes two cores 144a and 144b. The two cores 144a and 144b have the same configuration, but have different positions in the Z-axis direction. Specifically, the core 144b located on the high pressure region HP side (left side in FIG. 4) is located closer to the impeller 26 than the core 144a located on the low pressure region LP side (right side in FIG. 4). In other words, the core 144b located on the high-pressure region HP side extends to the impeller 26 side along the Z-axis direction from the core 144a located on the low-pressure region LP side, while the core 144b located on the low-pressure region LP side. 144a extends to the opposite side of the impeller 26 along the Z-axis direction from the core 144b located on the high-pressure region HP side.

  According to this configuration, the same effects as in the first embodiment can be obtained. Furthermore, the core 144a located on the low pressure region LP side extends to the opposite side of the impeller 26 than the core 144b located on the high pressure region HP side. For this reason, when the teeth of the cores 144a and 144b are magnetized during the operation of the electric pump 10, the magnetic force directed toward the low pressure region LP at the end opposite to the impeller 26 of the rotor 42 is directed toward the high pressure region HP. Bigger than. As a result, the resultant magnetic force applied to the end of the rotor 42 opposite to the impeller 26 is directed from the high pressure region HP side to the low pressure region LP side. According to this configuration, the force for reducing the displacement of the rotating body 60 (that is, the rotation due to the pressure difference of the cooling water), that is, the force for reducing the moment of the rotating body 60 due to the pressure difference is applied to the rotating body 60. Can be properly loaded. According to this configuration, it is possible to further reduce the displacement of the rotating body 60 due to the pressure difference of the cooling water in the cooling water passage 24. The rotor 42 and the stator 44 are examples of the “load portion”.

  In the modification, the end portions on the impeller 26 side of the core 144a and the core 144b may be at the same position in the Z-axis direction. On the other hand, the end of the core 144a opposite to the impeller 26 may extend to the opposite side of the impeller 26 along the Z-axis direction from the end of the core 144b opposite to the impeller 26. According to this configuration, the resultant force of the magnetic force applied to the end portion of the rotor 42 opposite to the impeller 26 is directed from the high pressure region HP side to the low pressure region LP side. .

(Third embodiment)
The electric pump 10 of the present embodiment is different from the electric pump 10 of the first embodiment in the configuration of the two cores 244a and 244b from the configuration of the two cores 44a and 44b. Since other configurations are the same as those of the electric pump 10 of the first embodiment, description thereof is omitted. The two cores 244a and 244b are configured by stacking a plurality of core plates 248 in the Z-axis direction. The two cores 244a and 244b include the same number of core plates 248. That is, the lengths of the two cores 244a and 244b in the Z-axis direction are the same.

  The plurality of core plates 248 includes a first core plate 248a and a second core plate 248b. Compared to the second core plate 248b, the first core plate 248a has a shorter portion extending along the outer peripheral surface 42a of the rotor 42 among the portions constituting the three teeth 270a to 270c.

  In the core 244a on the low-pressure region LP side (the right side in FIG. 5), among the plurality of core plates 248, a part of the core plates 248 located at the end portion on the impeller 26 side (for example, the Among the lengths, the core plate 248) corresponding to a quarter length is the first core plate 248a, and the other is the second core plate 248b. On the other hand, in the core 244b on the high pressure region HP side (left side in FIG. 5), a part of the core plates 248 located on the side opposite to the impeller 26 (for example, the Z-axis direction of the core plate 248) The core plate 248) corresponding to a quarter length is the first core plate 248a, and the other is the second core plate 248b.

  In this configuration, at the end of the rotor 42 on the impeller 26 side, a core 244b (second second) extending along the outer peripheral surface 42a when viewed in a cross section parallel to the XY plane (that is, a cross section orthogonal to the Z-axis direction). The length of the portion formed by the core plate 248b is longer than the length of the core 244a (portion formed by the first core plate 248a) extending along the outer peripheral surface 42a. When the teeth of the cores 244a and 244b are magnetized when the electric pump 10 is operated, the magnetic force toward the core 244b side between the core 244b and the rotor 42, that is, the high pressure region HP side, at the end of the rotor 42 on the impeller 26 side. Is larger than the magnetic force toward the core 44b between the core 244a and the rotor 42, that is, toward the low pressure region LP. That is, the resultant magnetic force applied to the end of the rotor 42 on the impeller 26 side is directed from the low pressure region LP side to the high pressure region HP side. According to this configuration, a force for reducing the displacement of the rotating body 60 (that is, rotation due to the pressure difference of the cooling water) can be appropriately applied to the rotating body 60. Further, since a voltage is applied to the coil 50 when the electric pump 10 is operated, the resultant magnetic force is constantly loaded on the rotating body 60 when the electric pump 10 is operated. According to this configuration, it is possible to reduce the displacement of the rotating body 60 due to the pressure difference of the cooling water in the cooling water passage 24. Thereby, contact with the rotary body 60 and the casing 12 is suppressed, and the fall of the pump efficiency of the electric pump 10 is suppressed.

  At the end of the rotor 42 opposite to the impeller 26, the length of the core 244a (part constituted by the second core plate 248b) extending along the outer peripheral surface 42a when viewed in a cross section parallel to the XY plane. Is longer than the length of the core 244b (the portion constituted by the first core plate 248a) extending along the outer peripheral surface 42a. In this configuration, when the electric pump 10 is operated, the magnetic force toward the core 244a side between the core 244a and the rotor 42, that is, the low pressure region LP side at the end portion of the rotor 42 opposite to the impeller 26 is the same as the core 244b. It is larger than the magnetic force toward the core 244b side with respect to the rotor 42, that is, toward the high pressure region HP side. That is, the resultant magnetic force applied to the end of the rotor 42 opposite to the impeller 26 is directed from the high pressure region HP side to the low pressure region LP side. According to this configuration, the force for reducing the displacement of the rotating body 60 (that is, the rotation due to the pressure difference of the cooling water), that is, the force for reducing the moment of the rotating body 60 due to the pressure difference is applied to the rotating body 60. Can be properly loaded. According to this configuration, it is possible to further reduce the displacement of the rotating body 60 due to the pressure difference of the cooling water in the cooling water passage 24.

  In the modified example, either of the two cores 244a and 244b may include only the second core plate 248b.

(Fourth embodiment)
In the electric pump 10 of this embodiment, the shape of the first core plate 348a provided in the two cores 344a and 344b is the same as that of the electric pump 10 of the third embodiment. The shape is different. The shape of the second core plate 348b is the same as the shape of the second core plate 248b.

  In the second core plate 348 b, the portions constituting the three teeth 370 a to 370 c have portions that extend along the outer periphery of the rotor 42. On the other hand, in the first core plate 348a, of the portions constituting the three teeth 370a to 370c, the end portion on the rotor 42 side does not extend along the outer periphery of the rotor 42, and the second core plate 348b. Compared to the outer periphery of the rotor 42.

  In this configuration, at the end portion of the rotor 42 on the impeller 26 side, the core 344b (part constituted by the second core plate 348b) extending along the outer peripheral surface 42a when viewed in a cross section parallel to the XY plane. The length is longer than the length of the core 344a (the portion constituted by the first core plate 348a) extending along the outer peripheral surface 42a. Further, at the end portion of the rotor 42 opposite to the impeller 26, the core 344a (a portion constituted by the second core plate 348b) extending along the outer peripheral surface 42a when viewed in a cross section parallel to the XY plane. The length is longer than the length of the core 344b (portion constituted by the first core plate 348a) extending along the outer peripheral surface 42a. According to this configuration, the electric pump 10 of the fourth embodiment can achieve the same effects as the electric pump 10 of the third embodiment. In the modified example, either of the two cores 344a and 344b may include only the second core plate 348b.

(5th Example)
As shown in FIG. 7, in the electric pump 10 of this embodiment, the shape of the first core plate 448a provided on the two cores 444a and 444b is different from that of the electric pump 10 of the third embodiment. , Different from the shape of the first core plate 248a. The shape of the second core plate 448b is the same as the shape of the second core plate 248b.

  Each of the first core plate 448a and the second core plate 448b has a portion extending along the outer peripheral surface 42a in a portion constituting the three teeth 470a to 470c. The portion extending along the outer peripheral surface 42a of the first core plate 448a is farther from the outer peripheral surface 42a than the portion extending along the outer peripheral surface 42a of the second core plate 448b.

  In this configuration, as shown in FIG. 8, at the end of the rotor 42 on the impeller 26 side, the gap between the core 444b (the portion formed by the second core plate 448b) and the rotor 42 is the core 444a (first Of the core plate 448 a) and the rotor 42. In this configuration, when the teeth of the cores 444a and 444b are magnetized during the operation of the electric pump 10, at the end portion on the impeller 26 side of the rotor 42, the core 444b side between the core 444b and the rotor 42, that is, the high pressure region HP. The magnetic force toward the side is larger than the magnetic force toward the core 444b side between the core 244a and the rotor 42, that is, toward the low pressure region LP side. That is, the resultant magnetic force applied to the end of the rotor 42 on the impeller 26 side is directed from the low pressure region LP side to the high pressure region HP side.

  In addition, at the end of the rotor 42 opposite to the impeller 26, the gap between the core 444a (the portion constituted by the second core plate 448b) and the rotor 42 is constituted by the core 444b (the first core plate 448a). Smaller than the gap between the rotor 42 and the rotor 42. For this reason, when the teeth of the cores 444a and 444b are magnetized during the operation of the electric pump 10, the core 444a side between the core 444a and the rotor 42, that is, the low-pressure region, at the end opposite to the impeller 26 of the rotor 42. The magnetic force toward the LP side is larger than the magnetic force toward the core 444b side between the core 444b and the rotor 42, that is, toward the high pressure region HP side. That is, the resultant magnetic force applied to the end of the rotor 42 opposite to the impeller 26 is directed from the high pressure region HP side to the low pressure region LP side. According to these configurations, the electric pump 10 of the fifth embodiment can achieve the same effects as the electric pump 10 of the third embodiment.

  In the above embodiment, the gap between the first core plate 448a and the rotor 42 is constant. However, the gap between the first core plate 448a and the rotor 42 may not be constant. In this case, the average gap size between the first core plate 448 a and the rotor 42 is made larger than the average gap size between the second core plate 448 b and the rotor 42. In another modification, either of the two cores 444a and 444b may include only the second core plate.

(Sixth embodiment)
With reference to FIG. 9, a difference from the electric pump 10 of the first embodiment will be described. In the electric pump 10 of the present embodiment, two boosting recesses 500 and 502 are formed on the peripheral wall 46a. The step-up recess 500 extends from the end of the peripheral wall 46 a on the impeller 26 side through the end of the rotor 42 on the impeller 26 side and extends to the intermediate position of the rotor 42 along the Z-axis direction. The boosting recess 500 is formed in a partial circular shape along the outer peripheral surface 42b on the low pressure region LP side. The peripheral wall 46a is a portion where the boost recess 500 is formed, and is separated from the rotor 42 than the other portions of the peripheral wall 46a. That is, at the end of the rotor 42 on the impeller 26 side, the gap between the rotor 42 and the peripheral wall 46a on the low pressure region LP side is larger than the gap between the rotor 42 and the peripheral wall 46a on the high pressure region HP side.

  The step-up recess 502 extends from the end of the peripheral wall 46 a opposite to the impeller 26 through the end of the rotor 42 opposite to the impeller 26 and extends to the intermediate position of the rotor 42 along the Z-axis direction. The two boost recesses 500 and 502 partially overlap in the Z-axis direction. The step-up recess 502 is formed in a partial circular shape along the outer periphery of the rotor 42 on the high-pressure region HP side. The peripheral wall 46a is a portion where the pressure-increasing recess 502 is formed, and is separated from the rotor 42 more than other portions of the peripheral wall 46a. That is, at the end of the rotor 42 opposite to the impeller 26, the gap between the rotor 42 and the peripheral wall 46a on the high pressure region HP side is larger than the gap between the rotor 42 and the peripheral wall 46a on the low pressure region LP side.

  When the electric pump 10 is operated, a part of the cooling water in the cooling water passage 24 flows into the gap between the rotor 42 and the peripheral wall 46a. The cooling water that has flowed into the gap between the rotor 42 and the peripheral wall 46 a flows along the rotational direction R through the gap between the rotor 42 and the peripheral wall 46 a as the rotor 42 rotates. In the portion where the boosting recesses 500 and 502 are formed, the gap between the rotor 42 and the peripheral wall 46a is larger than the other portions. That is, the flow path area of the cooling water flowing through the gap between the rotor 42 and the peripheral wall 46a is larger in the portion where the boosting recesses 500 and 502 are formed than in other portions. As a result, when the cooling water flows into the portion where the pressurizing recesses 500 and 502 are formed, the pressure of the cooling water becomes higher than the pressure in the other portion of the gap between the rotor 42 and the peripheral wall 46a.

  According to this configuration, a force directed from the low pressure region LP side to the high pressure region HP side is applied to the end portion of the rotor 42 on the impeller 26 side by the cooling water flowing through the gap between the rotor 42 and the peripheral wall 46a. On the other hand, a force from the high pressure region HP side to the low pressure region LP side is applied to the end of the rotor 42 opposite to the impeller 26 by the cooling water flowing through the gap between the rotor 42 and the peripheral wall 46a. According to this configuration, it is possible to reduce the displacement of the rotating body 60 due to the pressure difference of the cooling water in the cooling water passage 24. Thereby, contact with the rotary body 60 and the casing 12 is suppressed, and the fall of the pump efficiency of the electric pump 10 is suppressed.

  In the modified example, only one of the boost recesses 500 and 502 may be formed. Moreover, the shape of the pressure | voltage rise recessed part 500,502 is not limited to the shape of a present Example. For example, the pressure increasing recess 500 may be formed such that the peripheral wall 46a is gradually separated from the outer peripheral surface 42a. In general, the pressurizing recesses 500 and 502 may be formed so that the peripheral wall 46a is separated from the outer peripheral surface 42a.

(Seventh embodiment)
A difference from the electric pump 10 of the first embodiment will be described with reference to FIG. In the electric pump 10 of the present embodiment, the shape of the facing wall 46b is different from that of the electric pump 10 of the first embodiment. A boosting recess 600 is formed on the opposing wall 46b on the low pressure region LP side. The boosting recess 600 extends in an arc shape along the rotation direction R on the low pressure region LP side. The facing wall 46b is a portion where the pressure-increasing recess 600 is formed, and is separated from the end face 42b than the other portions of the facing wall 46b. For this reason, the clearance gap between the end surface 42b and the opposing wall 46b in the low voltage | pressure area | region LP side is larger than the clearance gap between the end surface 42b and the opposing wall 46b in the high voltage | pressure area | region HP side.

  During the operation of the electric pump 10, a part of the cooling water in the cooling water passage 24 flows into the gap between the end face 42b and the opposing wall 46b. The cooling water that has flowed into the gap between the end surface 42b and the opposing wall 46b flows along the rotational direction R through the gap between the end surface 42b and the opposing wall 46b as the rotor 42 rotates. In the portion where the boost recess 600 is formed, the gap between the end face 42b and the opposing wall 46b is larger than the other portions. For this reason, the flow path area of the cooling water flowing through the gap between the end face 42b and the facing wall 46b is larger in the portion where the pressure-increasing recess 600 is formed than in other portions. As a result, when the cooling water flows into the portion where the pressurizing recess 600 is formed, the pressure of the cooling water becomes higher than the pressure in the other portion of the gap between the end surface 42b and the facing wall 46b.

  According to this configuration, a force toward the impeller 26 is applied to the end surface 42b of the rotor 42 by the cooling water flowing through the portion where the boosting recess 600 is formed. According to this configuration, it is possible to reduce the displacement of the rotating body 60 due to the pressure difference of the cooling water in the cooling water passage 24. Thereby, contact with the rotary body 60 and the casing 12 is suppressed, and the fall of the pump efficiency of the electric pump 10 is suppressed.

  In addition, the shape of the pressure | voltage rise recessed part 600 is not limited to the shape of a present Example. For example, the pressurizing recess 600 may be formed such that the opposing wall 46b is gradually separated from the end face 42b. In general, the pressurizing recess 600 may be formed so that the facing wall 46b is separated from the end face 42b.

(Eighth embodiment)
A difference from the electric pump 10 of the first embodiment will be described with reference to FIG. In FIG. 11, the rotating body 60 is deleted for explanation. In the electric pump 10 of the present embodiment, two boost grooves 700 are formed in the peripheral wall 46a. Each boost groove 700 is curved from a position facing the impeller 26 side end of the rotor 42 on the low pressure region LP side to a position facing the end opposite to the impeller 26 of the rotor 42 on the high pressure region HP side. It is growing. The two boost grooves 700 are formed symmetrically with respect to the XZ plane passing through the rotation axis.

  In this configuration, the cooling water flowing through the gap between the rotor 42 and the opposing wall 46 a is boosted by the boost groove 700. The boosted cooling water passes through the boost groove 700 and reaches the end of the rotor 42 opposite to the impeller 26 on the high pressure region HP side. Further, the pressurized cooling water passes through the boosting groove 700 and reaches the end of the rotor 42 on the impeller 26 side on the low pressure region LP side. According to this configuration, the rotor 42 is loaded with a force due to a pressure difference between the cooling water flowing through the portion where the boosting groove 700 is formed and the cooling water flowing through the other portion. According to this configuration, it is possible to reduce the displacement of the rotating body 60 due to the pressure difference of the cooling water in the cooling water passage 24. Thereby, contact with the rotary body 60 and the casing 12 is suppressed, and the fall of the pump efficiency of the electric pump 10 is suppressed.

(Ninth embodiment)
A difference from the electric pump 10 of the first embodiment will be described with reference to FIG. In the electric pump 10 of this embodiment, a permanent magnet 804 that makes a round of the impeller 26 is attached to the outer peripheral surface of the impeller 26. The outer surface of the permanent magnet 804 is an N pole. Two permanent magnets 800 and 802 are arranged inside the upper casing 28. The permanent magnet 800 is provided on the high pressure region HP side. The permanent magnet 800 faces the outer surface of the permanent magnet 804, and the facing surface is an S pole. The permanent magnet 802 is provided on the low pressure region LP side. The permanent magnet 802 faces the outer surface of the permanent magnet 804, and the facing surface is an N pole. In addition, the magnetic pole of a permanent magnet is not restricted to said structure, The magnetic pole of each permanent magnet 800-804 may be reverse.

  The permanent magnet 800 and the permanent magnet 804 load the impeller 26 with a magnetic force from the low pressure region LP toward the high pressure region HP. Similarly, the permanent magnet 802 and the permanent magnet 804 apply a magnetic force to the impeller 26 from the low pressure region LP to the high pressure region HP. That is, the permanent magnets 800 to 804 always apply a magnetic force from the low pressure region LP to the high pressure region HP when the electric pump 10 is operated. According to this configuration, it is possible to reduce the displacement of the rotating body 60 due to the pressure difference of the cooling water in the cooling water passage 24. Thereby, contact with the rotary body 60 and the casing 12 is suppressed, and the fall of the pump efficiency of the electric pump 10 is suppressed.

  In the modified example, only one of the two permanent magnets 800 and 802 may be provided. When only the permanent magnet 800 is provided, the impeller 26 may be provided with a magnetic body (for example, an iron part or the like) that goes around the outer periphery of the impeller 26 instead of the permanent magnet 804. In this configuration, the permanent magnet 800 and the magnetic material load the impeller 26 with a magnetic force from the low pressure region LP toward the high pressure region HP.

  Alternatively, a magnetic material may be disposed instead of the permanent magnet 800. In this configuration, the permanent magnet 804 and the magnetic material load the impeller 26 with a magnetic force from the low pressure region LP to the high pressure region HP.

(Tenth embodiment)
The difference from the electric pump 10 of the first embodiment will be described with reference to FIG. In the electric pump 10 of this embodiment, the rotor 42 includes a permanent magnet 904 that makes a round of the shaft 16 on the end surface 42b. The lower surface of the permanent magnet 904 is an N pole. Two permanent magnets 900 and 902 are disposed on the facing wall 46b. The permanent magnet 900 is provided on the high pressure region HP side. The permanent magnet 900 faces the lower surface of the permanent magnet 904, and the facing surface is an S pole. The permanent magnet 902 is provided on the low pressure region LP side. The permanent magnet 902 faces the lower surface of the permanent magnet 904, and the facing surface is an N pole.

According to this configuration, similarly to the ninth embodiment, it is possible to reduce the displacement of the rotating body 60 due to the pressure difference of the cooling water in the cooling water passage 24 due to the magnetic force of the permanent magnets 900 to 904. Thereby, contact with the rotary body 60 and the casing 12 is suppressed, and the fall of the pump efficiency of the electric pump 10 is suppressed.

  In the modification, only one of the two permanent magnets 900 and 902 may be provided. When only the permanent magnet 900 is provided, the rotor 42 may include a magnetic body that makes a round of the outer periphery of the impeller 26 instead of the permanent magnet 904. In this configuration, the permanent magnet 900 and the magnetic body load the impeller 26 with a magnetic force from the low pressure region LP toward the high pressure region HP.

  Alternatively, a magnetic material may be disposed instead of the permanent magnet 900. In this configuration, the permanent magnet 804 and the magnetic material load the impeller 26 with a magnetic force from the low pressure region LP to the high pressure region HP.

(Eleventh embodiment)
A difference from the electric pump 10 of the first embodiment will be described with reference to FIG. In the electric pump 10 of the present embodiment, a permanent magnet 1004 that makes a round of the impeller 26 is attached to the outer edge of the surface of the impeller 26 on the rotor 42 side. The surface of the permanent magnet 1004 on the rotor 42 side is an N pole. A permanent magnet 1002 is disposed in the lower casing 46. The permanent magnet 1002 is provided on the low pressure region LP side. The permanent magnet 1002 faces the surface of the permanent magnet 1004 on the rotor 42 side, and the facing surface is an N pole. The magnetic poles of the permanent magnets are not limited to the above configuration, and the permanent magnets 1002 and 1004 may be reverse magnetic poles.

  On the low-pressure region LP side, a magnetic force that presses the surface of the impeller 26 on the rotor 42 side upward is loaded by the permanent magnet 1002 and the permanent magnet 1004. According to this configuration, it is possible to reduce the displacement of the rotating body 60 due to the pressure difference of the cooling water in the cooling water passage 24. Thereby, contact with the rotary body 60 and the casing 12 is suppressed, and the fall of the pump efficiency of the electric pump 10 is suppressed.

  In the modification, the lower casing 46 is provided on the high pressure region HP side, and may include a permanent magnet facing the permanent magnet 1004. In this case, the magnetic pole of the facing surface of the permanent magnet facing the permanent magnet 1004 may be a magnetic pole opposite to the surface of the permanent magnet 1004 on the rotor 42 side. In this case, the impeller 26 may be provided with a magnetic body (for example, an iron part or the like) that goes around the outer periphery of the impeller 26 instead of the permanent magnet 1004. Alternatively, a magnetic body may be disposed on the high pressure region HP side of the lower casing 46 instead of the permanent magnet.

  As mentioned above, although embodiment of this invention was described in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

(Modification)
(1) The electric pump 10 may include two or more configurations among a plurality of configurations disclosed in the first to tenth embodiments. For example, the electric pump 10 includes the configuration disclosed in the second embodiment (that is, the configuration of the two cores 144a and 144b) and the configuration of the third embodiment (that is, the first core plate 248a and the second core). Plate 248b) and the configuration of the sixth embodiment (that is, the boosting recesses 500 and 502) may be provided.

(2) The technique disclosed in this specification is also useful for an electric pump in which the cores 44a and 44b of the stator 44 are integrally formed. For example, as shown in FIG. 15, the stator may include one core 1144. The core 1144 may include three first teeth 1170a and three second teeth 1170b. The three first teeth 1170a may be arranged on the low pressure region LP side. The tips of the three teeth 1170a may face the outer peripheral surface 42a of the rotor 42. In each first tooth 1170 a, the portion of the rotor 42 that faces the end portion on the impeller 26 side may be separated from the outer peripheral surface 42 a of the rotor 42 than the portion that faces the other portion of the rotor 42. The three second teeth 1170b may be arranged on the high pressure region HP side. The tips of the three teeth 1170b may face the outer peripheral surface 42a of the rotor 42. In each of the second teeth 1170b, the portion of the rotor 42 that faces the end opposite to the impeller 26 may be farther from the outer peripheral surface 42a of the rotor 42 than the portion that faces the other portion of the rotor 42. Good. According to this configuration, the same effects as those of the fifth embodiment can be obtained.

(3) In each of the above embodiments, the core 44a and the like are configured by laminating a plurality of core plates 48 and the like. However, the core 44a and the like may be integrally formed.

(4) In the sixth to eleventh embodiments described above, the electric pump 10 includes the same stator 44 as that of the first embodiment, but instead of this, the two are provided symmetrically across the rotor 42 2. A stator 44 having a single core may be provided.

(5) The technique disclosed in this specification can also be used for an electric pump for fluids other than cooling water (for example, liquid fuel, hot water, etc.).

  The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

10: Electric pump 12: Casing 24: Cooling water path 26: Impeller 42: Rotor 44: Stator 44a, 44b: Core 46: Lower casing 48: Core plate 60: Rotating body HP: High pressure region LP: Low pressure region

Claims (11)

A rotating body including a rotor and an impeller arranged side by side with the rotor in the rotation axis direction of the rotor;
A stator disposed on the outer peripheral side of the rotor;
A casing having a fluid path formed along the outer periphery of the impeller, and housing the rotating body and the stator;
An electric pump comprising:
When operating the electric pump, the force to reduce the displacement of the rotating body caused by the pressure difference between the low pressure side where the fluid pressure in the fluid path is low and the high pressure side where the fluid pressure is high is rotated during the operation of the electric pump. An electric pump having a load part that constantly loads the body.   The load portion has the first composition in which the magnetic force applied to the impeller side end of the rotor is directed from the low pressure side to the high pressure side, and the resultant magnetic force applied to the end opposite to the rotor impeller. The electric pump according to claim 1, comprising at least one of a second configuration from the high pressure side toward the low pressure side. The load portion includes a stator and a rotor,
The first configuration includes a configuration in which the area of the stator extending along the impeller side end of the rotor on the high pressure side is larger than the area of the stator extending along the impeller side end of the rotor on the low pressure side,
In the second configuration, the area of the stator extending along the end opposite to the rotor impeller on the low pressure side is larger than the area of the stator extending along the end opposite to the rotor impeller on the high pressure side. The electric pump according to claim 2, comprising: In the first configuration, the impeller side end of the high-pressure side stator portion located on the high-pressure side of the stator is closer to the rotational axis direction than the impeller-side end portion of the low-pressure side stator portion located on the low-pressure side of the stator. Including the structure extending to the impeller side,
In the second configuration, the end portion on the opposite side of the impeller of the low-pressure side stator portion extends to the opposite side of the impeller along the rotational axis direction from the end portion on the opposite side of the impeller of the high-pressure side stator portion. The electric pump according to claim 3, comprising a configuration. In the first configuration, the length of the high-pressure side stator portion extending along the outer peripheral surface of the rotor is along the outer peripheral surface of the rotor when the cross section orthogonal to the rotation axis is viewed at the end portion on the impeller side of the rotor. Including a configuration that is longer than the length of the low-pressure side stator portion that extends,
In the second configuration, the length of the low-pressure side stator portion extending along the outer peripheral surface of the rotor is the outer peripheral surface of the rotor when viewed in a cross section perpendicular to the rotation axis of the opposite end of the rotor impeller. 5. The electric pump according to claim 3, comprising a configuration that is longer than a length of the high-pressure side stator portion that extends along the electric pump. The load portion includes a stator and a rotor,
The first configuration is such that, at the impeller side end of the rotor, the size of the average gap between the high pressure side stator portion located on the high pressure side of the stator and the rotor is low pressure side stator portion located on the low pressure side of the stator. Including a configuration smaller than the average gap size with the rotor,
In the second configuration, the average clearance between the low-pressure side stator portion and the rotor is smaller than the average clearance between the high-pressure side stator portion and the rotor at the end opposite to the impeller of the rotor. The electric pump according to claim 2, comprising: The load section includes a first magnetic body that is attached to the rotating body and makes a circuit in the circumferential direction of the rotating body, and a second magnetic body that is attached to a region of the casing facing the first magnetic body. ,
The second magnetic body is disposed on the high-pressure side, and generates a magnetic force in a direction to draw the first magnetic body to the second magnetic body side between the first magnetic body and the low-pressure side. And at least one magnetic body that generates a magnetic force in a direction of pressing the first magnetic body to the opposite side of the second magnetic body with the first magnetic body. The electric pump according to any one of claims 1 to 6.   The electric pump according to claim 7, wherein the first magnetic body is attached to the impeller.   The electric pump according to claim 7 or 8, wherein the first magnetic body is attached to an end surface of the rotor opposite to the impeller. The load portion covers a stator and includes a peripheral wall surrounding the rotor,
The fluid path communicates with the gap between the rotor and the peripheral wall,
The load section is
At the impeller side end of the rotor, the gap between the low pressure side rotor and the peripheral wall is larger than the gap between the high pressure side rotor and the peripheral wall;
At the end of the rotor opposite to the impeller, the gap between the high pressure side rotor and the peripheral wall is larger than the gap between the low pressure side rotor and the peripheral wall;
The electric pump according to any one of claims 1 to 9, comprising at least one of the configurations. The load portion includes an opposing wall facing an end surface on the opposite side of the rotor impeller,
The fluid path communicates with the gap between the rotor and the opposing wall,
The load portion includes a configuration in which a gap between an end surface opposite to the impeller of the low-pressure side rotor and the opposing wall is larger than a gap between the end surface opposite to the impeller of the high-pressure side and the opposing wall. To 10. The electric pump according to any one of 10 to 10.

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