JP2020020278A - Electric pump - Google Patents

Abstract

To provide an electric pump which enables removal of foreign objects contained in a refrigerant from the refrigerant, inhibits the electric pump from being hindered from rotating by the foreign objects being caught therein, and inhibits refrigerant leakage caused by damage of a partition wall of a second housing part 120 and life deterioration caused by damage of a shaft and a bearing.SOLUTION: An electric pump 1 suctions and discharges a refrigerant and includes: a pump chamber 100a having a suction port 101 for suctioning the refrigerant and a discharge port 102 for discharging the suctioned refrigerant; a motor chamber 100b in which a motor 300 for rotating an impeller 200 disposed in the pump chamber 100a is disposed. Foreign object reservoirs 121a, 121b, 121c are provided at a second housing part 120 of a lower part of the impeller 200.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to an electric pump, and more particularly to an electric pump used for a cooling system for a vehicle.

  2. Description of the Related Art In a vehicle such as an automobile, a cooling system that cools a heat-generating device in a vehicle with a coolant (cooling water) cooled by a radiator is used. For example, in a hybrid vehicle, a cooling system that cools a power unit including an inverter, a converter, and the like by using a pipe to transmit a refrigerant cooled by a radiator is used. In such a cooling system, an electric pump is used to circulate the refrigerant in the pipe.

  As an electric pump of this type, an impeller to which a driven magnet is fixed is rotatably fixed to a shaft disposed in a pump chamber, and is driven by a magnetic force of a driving magnet fixed to a shaft to which a rotor is attached. 2. Description of the Related Art There is known a magnetic coupling pump that transmits a rotational force and rotates an impeller. The impeller to which the driven magnet is fixed rotates with respect to a shaft disposed in the pump chamber via a bearing fixed to the center of the impeller. When the electric pump circulates the refrigerant, the pump chamber is filled with the refrigerant, and the refrigerant enters between the shaft and the bearing.

  When foreign matter is mixed in the refrigerant, if foreign matter enters between the shaft and the bearing, the shaft and the bearing are damaged, and the life is shortened.

  To cope with this problem, there is known an electric pump provided with a foreign matter reservoir for removing foreign matters contained in the coolant from the coolant and collecting the foreign matters (for example, Patent Document 1).

  Further, the drive circuit unit for driving the motor has a plurality of circuit components and a circuit board on which the plurality of circuit components are mounted, and among the plurality of circuit components, a coil, a semiconductor component, etc., generates heat by itself. 2. Description of the Related Art There is known an electric pump that includes heat-generating components, and the heat-generating components contact a second housing portion that forms a pump chamber through which a refrigerant flows through a heat-conducting member, thereby releasing heat from the heat-generating components. For example, Patent Document 2).

JP 2011-17294 A JP 2015-104168 A

  In a conventional electric pump, a foreign substance reservoir for removing foreign matters contained in the refrigerant from the refrigerant and accumulating the foreign matters is provided at a side of the pump chamber or at a location larger than the outer diameter of the impeller.

  However, when foreign matter enters the lower part of the impeller, the foreign matter may bite into the gap between the rotating impeller and the second casing partition, and may not be able to rotate. In addition, leakage of the refrigerant may occur due to breakage of the second housing partition. Further, when foreign matter enters between the shaft and the bearing, the shaft and the bearing may be damaged, and the life may be shortened.

The electric pump of the present disclosure has been made in order to solve such a problem, and even when foreign matter enters the lower part of the impeller, the foreign matter is removed by the foreign matter reservoir provided at the lower part of the impeller. Aim.

  In order to achieve the above object, one embodiment of an electric pump according to the present disclosure is an electric pump that sucks and discharges a refrigerant, and includes a suction port for sucking the refrigerant, and a suction port inside a housing of the electric pump. A discharge chamber for discharging the refrigerant, a pump chamber having an impeller that sucks and discharges the refrigerant by rotating, and a motor chamber in which a motor for rotating the impeller is disposed, and a motor chamber in the pump chamber. A foreign matter reservoir for accumulating foreign matter in the refrigerant is formed on the side of the partition wall.

  According to the electric pump of the present disclosure, even when foreign matter enters the lower portion of the impeller, the foreign matter contained in the refrigerant can be removed from the refrigerant, and rotation is impossible due to the foreign matter generated by the foreign matter. It is possible to suppress the leakage of the refrigerant due to the breakage of the partition wall of the housing and the reduction in the life due to the damage to the shaft and the bearing.

Sectional view of an electric pump according to an embodiment External perspective view of an electric pump according to an embodiment Partial exploded view of an electric pump according to an embodiment FIG. 4 is a top view of a second housing portion according to the embodiment. Second housing part top view according to Modification Example 1 Top view of second housing portion according to Modification 2 Top view of second housing portion according to Modification 3 Cross section of conventional electric pump (magnet coupling pump)

  Hereinafter, embodiments will be described with reference to the drawings. Note that each of the embodiments described below is merely one of various embodiments of the present disclosure. Therefore, numerical values, shapes, materials, constituent elements, arrangement positions of constituent elements, connection forms, and the like shown in the following embodiments are merely examples, and if the object of the present disclosure can be achieved, various values may be set according to the design and the like. Changes are possible. Therefore, among the components in the following embodiments, components that are not described in the independent claims that indicate the highest concept of the present disclosure are described as arbitrary components.

  Each drawing is a schematic diagram, and is not necessarily shown exactly. Therefore, the scale and the like do not always match in each drawing. In each of the drawings, substantially the same components are denoted by the same reference numerals, and redundant description will be omitted or simplified.

(Embodiment)
Hereinafter, the electric pump 1 according to the embodiment will be described with reference to FIGS. 1 to 4 and 8. 1 to 4 are views showing a configuration of an electric pump 1 according to an embodiment. FIG. 1 is a sectional view of the electric pump, FIG. 2 is an external perspective view of the electric pump, and FIG. FIG. 4 is a partially exploded view of the electric pump from which a nut, a washer, and an impeller are removed, and FIG. 4 is a top view of a second housing portion of the electric pump. FIG. 8 is a sectional view of a conventional electric pump (magnet coupling pump).

  The electric pump 1 is an electric pump that uses a refrigerant as a working fluid and sucks and discharges the refrigerant by the power of a motor. The electric pump 1 according to the present embodiment is an electric water pump using water (cooling water) as a refrigerant.

  The electric pump 1 is a cooling pump incorporated in a circulation path connected to a heat exchanger such as a radiator. For example, in a hybrid vehicle, the electric pump 1 supplies cooling water to a power unit including an inverter and a converter or an engine (internal combustion engine) by circulating cooling water cooled by a radiator.

  As shown in FIGS. 1 to 3, the electric pump 1 includes a housing 100 having a pump chamber (pump casing) 100 a and a motor chamber (motor casing) 100 b, an impeller 200 disposed in the pump chamber 100 a, and a motor. A motor 300 and a drive circuit unit 400 are provided in the chamber 100b. The drive circuit unit 400 has a plurality of circuit components 410 and a circuit board 420 on which the plurality of circuit components 410 are mounted.

  The housing 100 is an outer member that forms an outer shell of the electric pump 1, and includes a first housing unit 110, a second housing unit 120, and a third housing unit 130 as illustrated in FIGS. 1 to 3. Have been. The first housing part 110, the second housing part 120, and the third housing part 130 are connected and fixed to each other by, for example, three screws.

  The first housing 110, the second housing 120, and the third housing 130 are made of a resin material, a metal material, or the like. In the present embodiment, the first casing 110, the second casing 120, and the third casing 130 are made of PPS (Polyphenylenesulfide) resin having relatively high thermal conductivity among resin materials. I have.

  The pump chamber 100a is an area through which the cooling water passes, and is configured by a first casing 110 and a second casing 120. In other words, the pump chamber 100a is a space area surrounded by the first housing unit 110 and the second housing unit 120, and forms a flow path using the first housing unit 110 and the second housing unit 120 as partition walls. are doing.

  The pump chamber 100a has a suction port 101 for sucking the cooling water and a discharge port 102 for discharging the sucked cooling water. In the present embodiment, the suction port 101 and the discharge port 102 are provided in the first casing 110. The suction port 101 and the discharge port 102 have a long cylindrical shape, and are provided in the first housing portion 110 in such a manner that the extending directions of the respective cylinders are in a twisted position.

  Specifically, the suction port 101 is provided so that the direction in which the cooling water flows in the suction port 101 and the rotation axis of the impeller 200 are substantially parallel. On the other hand, the discharge port 102 is provided so that the direction in which the cooling water flows in the discharge port 102 and one of the tangent directions of the tangents of the rotating circle of the impeller 200 are substantially parallel. As a result, the rotation of the impeller 200 causes the cooling water to be drawn into the pump chamber 100a from the suction port 101 and the cooling water to be discharged from the discharge port 102.

  The motor chamber 100b is a space area surrounded by the second housing part 120 and the third housing part 130, and the second housing part 120 and the third housing part 130 serve as partition walls to form a closed space. Has formed. As described above, in the present embodiment, the second casing 120 also serves as a partition between the pump chamber 100a and the motor chamber 100b.

  The motor chamber 100b houses the motor 300 and the drive circuit unit 400. That is, the motor 300 and the drive circuit unit 400 are arranged in the same internal space (motor chamber 100b). Specifically, the motor chamber 100b houses the motor 300, and also houses a plurality of circuit components 410 and a circuit board 420.

The electric pump 1 according to the present embodiment has a structure in which a pump chamber 100a, which is a liquid layer, and a motor chamber 100b, which is an air layer, are separated from each other with the second casing 120 as a boundary. That is, unlike the canned type in which the rotor of the motor is immersed in the cooling water, the motor 300 in the motor chamber 100b is not immersed in the cooling water. That is, the electric pump 1 has a structure in which the cooling water does not flow into the motor chamber 100b.

  The impeller (impeller) 200 has a disk-shaped bottom (base) 210 and a plurality of blades (blades) 220 and is arranged at a position facing the suction port 101. The plurality of blades 220 are fixed to the bottom 210. In the present embodiment, the plurality of blades 220 are open blades, and are arranged substantially radially around the center axis of impeller 200.

  The impeller 200 has a bearing 230 coaxial with the center axis (rotation axis) of the impeller 200, and a driven magnet 240 disposed on an annular side surface coaxial with the center axis on the lower surface of the bottom 210 on the motor side, And an annular back yoke 250. The bearing 230, the driven magnet 240, and the back yoke 250 are fixed to the bottom 210.

  The impeller shaft 500 is fixed to the second housing part 120 coaxially with the central axis of the second housing part 120, and is arranged in the pump chamber 100a.

  The impeller 200 is rotatably fixed to the impeller shaft 500 via a bearing 230.

  The washer 600 is fixed to the tip of the impeller shaft 500 by the tip screw portion of the impeller shaft 500 and the nut 700, and suppresses the movement of the impeller 200 in the thrust direction.

  The motor 300 is, for example, an inner rotor type DC brushless motor, and includes a stator 310 (stator) and a rotor (rotor) 320 arranged on the inner peripheral side of the stator 310.

  The stator 310 has a plurality of coils 311 (windings), and generates a magnetic flux on the inner peripheral side by energizing the coils 311. In the present embodiment, stator 310 is fixed to motor frame 330. The motor frame 330 is fixed to the third housing 130.

  The rotor 320 has a configuration in which a rotor shaft 323 is connected to a rotor frame 321. The magnetic pole part 322 is a columnar member fixed to the outer periphery of the rotor frame 321 and installed to face the inner peripheral surface of the stator 310 via a slight gap (air gap). A plurality of magnetic poles (for example, permanent magnets in which N poles and S poles are alternately arranged in the circumferential direction) are provided corresponding to the coils 311. The rotor shaft 323 is supported by a bearing provided on the motor frame 330 and a bearing provided on the second casing 120. A magnet holder 324 is fixed to the tip of the rotor shaft 323, and an annular drive magnet 325 is fixed on the outer periphery of the magnet holder 324 coaxially with the rotor shaft 323.

  The drive magnet 325 and the driven magnet 240 are provided with a plurality of magnetic poles and have the same number of magnetic poles. In the drive magnet 325 and the driven magnet 240, opposing north and south poles attract each other by magnetic force. The driving magnet 325 and the driven magnet 240 are arranged coaxially.

When the driving magnet 325 fixed to the rotor shaft 323 via the magnet holder 324 rotates, the rotating force is transmitted to the driven magnet 240 by the magnetic force, and the impeller 200 rotates. The drive magnet 325 is arranged in the motor room 100b, and the driven magnet 240 is arranged in the pump room 100a. The driving magnet 325 and the driven magnet 240 are separated by a partition wall of the second housing unit 120, and the rotational force of the driving magnet 325 is transmitted to the driven magnet 240 by a magnetic force passing through the partition wall of the second housing unit 120. . By rotating the impeller 200 disposed in the pump chamber 100a, the cooling water is drawn into the pump chamber 100a from the suction port 101 and discharged from the discharge port 102.

  The drive circuit unit 400 includes a plurality of circuit components 410 for driving the motor 300, and a circuit board 420 on which the plurality of circuit components 410 are mounted.

  The plurality of circuit components 410 constitute a drive circuit for driving the motor 300 and the like. The circuit component 410 (circuit element) is, for example, a capacitance element such as an electrolytic capacitor or a ceramic capacitor, a resistance element such as a resistor, a coil element, or a semiconductor element such as a microcomputer (integrated circuit element). The circuit component 410 may include a rotation position detection element (Hall IC) for detecting the rotation position of the rotor 320.

  In the present embodiment, most of the plurality of circuit components 410 are mounted on the surface of the circuit board 420 on the impeller 200 side.

  Further, a through hole 421 through which the rotor shaft 323 passes is formed in the circuit board 420. The through-hole 421 is, for example, circular, but is not limited to this.

  In the present embodiment, as shown in FIGS. 1, 3, and 4, the foreign matter reservoirs 121a, 121b, and 121c are formed in the second housing part 120 in a concave shape toward the motor chamber 100b, and the lower part of the impeller 200 is formed. It is provided in. Further, the foreign substance reservoirs 121a, 121b, 121c are arranged in the pump chamber 100a and are filled with cooling water. In addition, as shown in FIG. 4, when viewed from the top, the foreign material reservoirs 121a, 121b, and 121c have a narrow entrance and a wide depth.

  In the present embodiment, FIG. 1 shows the flow of cooling water. When the impeller 200 rotates clockwise (CW direction) when viewed from the suction port 101, a flow is created in which the cooling water is drawn into the pump chamber 100 a from the suction port 101 and discharged from the discharge port 102. In addition, since the upper part of the impeller 200 immediately below the suction port 101 has a low pressure, the impeller 200 wraps around the lower part of the impeller 200, and finally flows toward the upper part of the impeller 200 in the gap between the bearing 230 of the impeller 200 and the impeller shaft 500.

  Further, as shown in FIG. 4, when the impeller 200 rotates clockwise, a clockwise flow is generated around the impeller 200, and the foreign matter reservoirs 121a, 121b, and 121c respectively move counterclockwise (in the CCW direction). ). As a result, when foreign matter is mixed in the cooling water flowing into the lower surface of the impeller 200, the foreign matter accumulates in the foreign matter reservoirs 121a, 121b, and 121c due to the vortex flow generated in each of the foreign matter reservoirs 121a, 121b, and 121c. Thereby, foreign matter can be removed. In addition, foreign matter that enters the lower part of the impeller 200 from the outer periphery of the impeller 200 is carried to the lower part on the outer peripheral side of the bottom part 210 of the impeller 200 by a clockwise flow generated by rotation, and the foreign matter accumulates in the foreign matter reservoirs 121a, 121b, and 121c. By doing so, foreign matter can be removed.

As shown in FIG. 1, in particular, the foreign matter reservoir 121 c is formed in a concave shape further from the annular side surface of the impeller 200 toward the motor chamber. When the suction port 101 is mounted in the direction opposite to the direction of gravity, it is effective because foreign matters having a specific gravity higher than that of the cooling water accumulate in the direction of gravity, that is, in the motor chamber side. In addition, even when the suction port 101 is mounted in the horizontal direction with respect to the direction of gravity, if any of the foreign substance reservoirs 121a, 121b, and 121c is formed in the direction of gravity, foreign substances accumulate in the direction of gravity, effective.

  In addition, as shown in FIG. 1, the drive circuit unit 400 is disposed adjacent to the pump chamber 100a. The drive circuit unit 400 includes a plurality of circuit components 410 for driving the motor 300, and a circuit board 420 on which the plurality of circuit components 410 are mounted.

  In the present embodiment, among the plurality of circuit components 410, low heat resistant components whose heat resistant temperature is relatively low and the product life is affected by the temperature, for example, an electrolytic capacitor 411, and heat generated by itself such as coils and semiconductor components. A component, for example, a microcomputer 412 is present, and the electrolytic capacitor 411 and the microcomputer 412 are conducted to the electrolytic capacitor 411 by contacting the second casing 120 constituting the pump chamber 100a through which the cooling water flows through a heat conductive member. The heat and the self-heating of the microcomputer 412 are conducted to the cooling water of the pump chamber 100a to radiate heat.

  As shown in FIG. 8, in the conventional magnet coupling pump, a recess 1122 is provided in the second housing 1120, and the electrolytic capacitor 1411 is arranged close to the recess 1122. In addition, an extension 1123 is formed by extending a part of the second housing 1120, and is disposed close to the microcomputer 1412. In the gap between the concave portion 1122 and the electrolytic capacitor 1411 and the gap between the extending portion 1123 and the microcomputer 1412, a heat conductive member (for example, silicone RTV rubber) is interposed to connect the electrolytic capacitor 1411 and the microcomputer 1412 to the second housing 1120. Contact.

  However, by providing the concave portion 1122 and the extension portion 1123, the resin has a thick portion, and the resin thickness of the second housing portion 1120 becomes non-uniform. When the resin thickness is not uniform, the thickness of the resin is largely shrinkage due to the influence of the molding shrinkage of the resin, which causes distortion, resulting in poor resin dimensional accuracy. Further, the weight increases due to an increase in the amount of resin.

  In the present embodiment, as shown in FIG. 1, by providing foreign matter reservoirs 121 a, 121 b, and 121 c, the thickness of the thick portion of the second housing portion 120 is reduced (the waste resin in the thick portion of the resin is reduced). Removal). That is, the thick part of the second housing part 120 is lightened to provide the foreign matter reservoirs 121a, 121b, and 121c. As a result, the resin thickness can be made uniform, and the resin dimensions are stabilized without being affected by the molding shrinkage of the resin. Further, an increase in resin weight can be suppressed. Further, similarly to the conventional magnet coupling pump, the electrolytic capacitor 411 is arranged close to the concave portion 122 so as to be housed in the concave portion 122, the extending portion 123 is arranged close to the microcomputer 412, and the concave portion 122 and the electrolytic capacitor 411 are arranged. The electrolytic capacitor 411 and the microcomputer 412 are brought into contact with the second housing unit 120 with a heat conductive member interposed in the gap between the second housing unit 120 and the gap between the extension unit 123 and the microcomputer 412.

  By providing the foreign substance reservoirs 121a, 121b, 121c, the cooling water flows into the foreign substance reservoirs 121a, 121b, 121c, and the cooling water approaches the electrolytic capacitor 411 and the microcomputer 412, so that there is an effect that heat dissipation is improved.

  In the present embodiment, the foreign substance reservoirs 121a and 121b are radiating parts of the two electrolytic capacitors 411, and the foreign substance reservoir 121c is a radiating part of the microcomputer 412.

  As described above, the foreign matter reservoirs 121a, 121b, and 121c are provided in the second housing part 120 below the impeller 200, and cool foreign matter contained in the cooling water when foreign matter enters the motor 300 below the impeller 200. After being removed from the water, the foreign substances can be accumulated in the foreign substance reservoirs 121a, 121b, 121c.

  This makes it possible to remove foreign matter contained in the cooling water from the cooling water, thereby making it impossible to rotate due to the foreign matter being caught by the foreign matter, leaking the cooling water due to breakage of the partition wall of the second housing part 120, and reducing the impeller shaft. It is possible to suppress a decrease in life due to damage to the bearing 500 and the bearing 230.

  In addition, by providing the foreign material reservoirs 121a, 121b, and 121c, the thickness of the thick resin portion of the second housing portion 120 can be reduced, and the thickness of the resin can be made uniform, and the influence of molding shrinkage of the resin can be obtained. Not only stabilizes the resin dimensions but also suppresses an increase in resin weight. Further, when the cooling water flows into the foreign substance reservoirs 121a, 121b, and 121c, the heat resistance is relatively low, and the product life is affected by the temperature. Since the cooling water approaches the heat-generating component (for example, the microcomputer 412) via the heat-conducting member, there is an effect that heat dissipation is improved.

(Modifications, etc.)
As described above, the electric pump according to the present disclosure has been described based on the embodiments, but the present disclosure is not limited to the above embodiments.

  For example, in the above embodiment, as an example of the foreign material reservoir, as shown in FIG. 5, the foreign material reservoirs 121a, 121b, and 121c may be connected by an arc-shaped groove 124. In this case, the foreign matter removed in each of the foreign matter reservoirs 121a, 121b, and 121c passes through the groove 124 and is collected in the foreign matter reservoir 121c. As shown in FIG. 1, in the foreign substance reservoir 121c, since the space for the foreign substance reservoir is spread below the lower surface of the impeller 200, foreign substances having a specific gravity higher than that of the cooling water are accumulated in the foreign substance reservoir 121c.

  For example, in the above-described embodiment, as an example of the foreign matter reservoir, as shown in FIG. 6, the foreign matter reservoirs 121h, 121i, 121j on the upstream side of the flow of the cooling water provided for the circumferential partition wall. A part of the entrance may be chamfered. Foreign matter that has entered between the outer periphery of the back yoke 250 of the impeller 200 and the partition can be efficiently removed.

  For example, in the above embodiment, as an example of the foreign material reservoir, as shown in FIG. 7, the foreign material reservoirs 121a, 121b, 121c, 121d, 121e, and 121f may be arranged all around. By arranging them uniformly over the entire circumference, foreign substances can be efficiently removed.

  Further, in the above-described embodiment, the motor 300 is an inner rotor type DC brushless motor, but is not limited to this.

  In addition, a form obtained by applying various modifications that can be conceived by those skilled in the art to each of the above-described embodiments, or an arbitrary combination of components and functions in the above-described embodiments without departing from the spirit of the present disclosure. The embodiment realized by is also included in the present disclosure.

  The electric pump according to the present disclosure is a pump for circulating a refrigerant such as water (cooling water), and can be used as, for example, an electric water pump used in a vehicle cooling system or the like.

Reference Signs List 1 electric pump 100 casing 101 suction port 102 discharge port 100a pump chamber 100b motor chamber 110 first casing section 120 second casing section 121a, 121b, 121c foreign substance storage 121d, 121e, 121f foreign substance storage 121h, 121i, 121j foreign substance Reservoir 122 Recessed part 123 Extension part 124 Groove 130 Third housing part 200 Impeller 210 Bottom part 220 Blade 230 Bearing 240 Follower magnet 250 Back yoke 300 Motor 310 Stator 311 Coil 320 Rotor 321 Rotor frame 322 Magnetic pole part 323 Rotor shaft 324 Magnet holder 325 Drive magnet 330 Motor frame 400 Drive circuit unit 410 Circuit components 411 Electrolytic capacitor 412 Microcomputer 420 Circuit board 421 Through hole 500 A Perak shaft 600 washer 700 nut

Claims (9)

An electric pump that sucks and discharges a refrigerant,
Inside the housing of the electric pump,
A suction port for sucking the refrigerant, a discharge port for discharging the sucked refrigerant, and a pump chamber having an impeller that sucks and discharges the refrigerant by rotating;
A motor chamber in which a motor for rotating the impeller is arranged,
An electric pump in which a foreign matter reservoir for accumulating foreign matter in the refrigerant is formed on the partition wall side of the pump chamber and the motor chamber. Furthermore, it has a motor drive circuit,
The housing is
A first housing portion provided with the suction port and the discharge port,
A second housing section to which an impeller shaft to which the impeller is rotatably fixed is fixed,
The motor and a third housing portion in which the motor drive circuit is arranged,
The pump chamber is formed in a space surrounded by the first casing and the second casing,
The motor chamber is formed by a space surrounded by the second housing section and the third housing section,
The motor drive circuit is disposed on the partition wall side with the pump chamber in the motor chamber,
The electric pump according to claim 1, wherein the foreign matter reservoir is formed by lightening a thick portion of the second housing portion.   The said foreign material reservoir is arrange | positioned so that it may face the outer periphery of the annular side surface which becomes coaxial with the said rotation axis arrange | positioned at the surface of the said impeller by the side of the said motor chamber in the rotation axis direction of the said impeller. 3. The electric pump according to 2.   4. The electric pump according to claim 3, wherein the foreign matter reservoir is formed in a concave shape toward the motor chamber, and has a shape with a narrow entrance and a large depth. 5.   The electric pump according to claim 4, wherein the foreign matter reservoir is further formed in a concave shape from the annular side surface toward the motor chamber.   The electric pump according to claim 4, wherein a plurality of the foreign substance reservoirs are formed, and the plurality of the foreign substance reservoirs are connected to each other by grooves formed on the inner side of the plurality of foreign substance reservoirs.   5. The electric pump according to claim 4, wherein a plurality of the foreign substance reservoirs are formed, and the plurality of the foreign substance reservoirs are arranged uniformly over the entire circumference of the circumferential partition.   The electric pump according to any one of claims 3 to 7, wherein a part of an inlet of the foreign matter reservoir on an upstream side of the flow of the refrigerant has a chamfered shape. A drive magnet is provided in the motor chamber, and a driven magnet is provided in the pump chamber.
A driving force is transmitted from the motor to the impeller by a magnet coupling constituted by the driving magnet and the driven magnet,
The electric pump according to claim 3, wherein the driven magnet is arranged on the annular side surface of the impeller.

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