Electric pump

Abstract

To provide an electric pump which can improve a possibility of discharging heat generated by a circuit board and a motor.SOLUTION: An electric pump includes: a motor having a rotor that rotates about a rotational axis and a stator arranged opposite to the rotor; a metal housing for storing the motor therein; a pump part arranged on one side of the rotational axis with reference to the motor and rotated by a drive force of the motor to pressure-feed a coolant; and a circuit board arranged on the other side of the rotational axis with reference to the motor and driving the motor. The housing comes into contact with the stator, and comes into contact with the circuit board via a heat discharge member.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electric pump.

Background Art

[0002] Conventionally, an electric pump driven by a motor has been known (for example, Patent Document 1). The electric pump described in Patent Document 1 includes a pump unit, a motor unit that drives the pump unit, and a circuit board that drives the motor unit, and is configured to dissipate heat generated by the circuit board (including electronic components) to an aluminum alloy motor housing that houses the motor unit via a heat dissipation member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Heat generated by a heat source such as a circuit board including electronic components needs to be dissipated, and as described above, for example, it is known to dissipate heat to a motor housing via a heat dissipation member. On the other hand, in addition to the circuit board, components such as a motor also serve as heat sources. However, in the electric pump of Patent Document 1, the configuration for dissipating heat generated by the motor is insufficient. For example, in the electric pump described in Patent Document 1, among the components constituting the motor, heat is generated in the stator provided with a coil, and the stator is supported by a resin stator housing, making it difficult to dissipate the heat generated in the stator.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide an electric pump capable of increasing the possibility of dissipating heat generated by a circuit board and a motor.

Means for Solving the Problems

[0006] To achieve the above object, an electric pump includes a motor having a rotor that rotates about a rotation axis and a stator disposed opposite to the rotor, a metallic housing that houses the motor, a pump unit that is disposed on one side of the rotation axis with reference to the motor and rotates by the driving force of the motor to pump refrigerant, and a circuit board that is disposed on the other side of the rotation axis with reference to the motor and drives the motor. The housing contacts the stator and contacts the circuit board via a heat dissipation member.

[0007] That is, the stator is in contact with the metallic housing. Therefore, by transferring the heat generated in the stator to the housing, the heat generated in the stator can be dissipated. Further, the circuit board is in contact with the metallic housing via a heat dissipation member (for example, heat dissipation grease). Therefore, by transferring the heat generated in the circuit board to the housing, the heat generated in the circuit board can be dissipated. That is, the stator and the circuit board are configured to be able to dissipate heat to the metallic housing, respectively. As a result, the possibility of dissipating the heat generated in the circuit board and the motor can be increased.

Brief Description of the Drawings

[0008]

Figure 1

Embodiments for Carrying Out the Invention

[0009] Here, embodiments of the present invention will be described in the following order with reference to the drawings. Note that the embodiments shown below are merely examples of embodying the present invention and do not limit the present invention. (1) Configuration of the electric pump: (2) Other embodiments, etc.:

[0010] (1) Configuration of the electric pump: In this embodiment, the electric pump 1 is an electric water pump (hereinafter simply referred to as "electric pump") that circulates cooling water (an example of a refrigerant) for cooling, for example, an engine, a motor, or an inverter mounted on a vehicle. Note that the electric pump 1 can be used in any posture. In the example shown in FIG. 1, with the rotation axis X (the vertical direction of the paper surface) as a reference, the impeller 9 is arranged on the upper side of the paper surface, and the circuit board 6 is arranged on the lower side of the paper surface (i.e., on the side opposite to the impeller 9). In this specification, the direction along the rotation axis X is referred to as the "axial direction", and the direction perpendicular to the rotation axis X is referred to as the "radial direction".

[0011] FIG. 1 shows a cross-sectional view of the electric pump 1 according to this embodiment. The electric pump 1 includes a motor 4 having a rotor 2 that rotates about the rotation axis X and a stator 3 arranged to face the rotor 2, a motor housing 5 that is a metallic housing for housing the motor 4, a circuit board 6 for driving the motor 4, a shaft 7 whose end is fixed to the motor housing 5, a cylindrical bush 8 inserted outside the shaft 7 and rotating integrally with the rotor 2, and an impeller 9 that rotates by the driving force of the motor 4 and pumps the cooling water. Note that the motor housing 5 corresponds to the "housing" in this embodiment, and the impeller 9 corresponds to the "pump section" in this embodiment.

[0012] The electric pump 1 includes a resin cover member 10 for housing the circuit board 6 and a metallic (e.g., aluminum) impeller housing 11 for housing the impeller 9. These cover member 10 and impeller housing 11 are fixed to the motor housing 5 by bolts, welding, or the like. The electric pump 1 is configured such that the impeller 9 sucks and discharges the cooling water when the rotor 2 rotates by the driving force of the motor 4, and for example, flows the cooling water through the motor 4 and an inverter (not shown), or circulates the cooling water between the engine and a radiator (both not shown).

[0013] The rotor 2 is made of, for example, PPS (polyphenylene sulfide) as a resin material for insert molding the bush 8. The rotor 2 includes a back yoke and a plurality of permanent magnets 12. The stator 3 includes a stator core formed by laminating a plurality of thin electromagnetic steel sheets, and a stator coil 13 is wound around the stator core. The motor 4 is configured as a three-phase brushless motor that generates a rotating magnetic field in the rotor 2 by energizing the stator 3.

[0014] The motor housing 5 is a metal housing as described above, for example, made of aluminum die-cast. The stator 3 is in contact with and fixed to the motor housing 5. Specifically, on the outer side in the radial direction (the side away from the rotation axis X in the radial direction), the stator 3 is in contact with and fixed to the motor housing 5. In the present embodiment, the stator 3 is fixed to the motor housing 5 by, for example, press-fitting or shrink-fitting. In this way, by fixing the stator 3 to the metallic motor housing 5 such as made of aluminum die-cast, the heat generated in the stator 3 can be transferred (i.e., dissipated) to the motor housing 5. And in the example shown in FIG. 1, a support portion 14 for supporting the shaft 7 is formed at the bottom 5a of the motor housing 5 in the axial direction, and the end portion 7a of the shaft 7 is press-fitted and fixed to the support portion 14 from the impeller 9 side toward the circuit board 6 side.

[0015] In the present embodiment, as described above, by fixing the stator 3 to the motor housing 5 by press-fitting or shrink-fitting or the like, a space is formed on the circuit board 6 side. That is, a space is generated below the stator 3 in FIG. 1. In the present embodiment, a substantially L-shaped bus bar 15 is disposed in this space. One end of the bus bar 15 is attached to the stator coil 13 wound around the stator 3, and the other end is connected to a terminal provided on the circuit board 6 (more specifically, a terminal in the electronic component 19), and the circuit board 6 and the motor 4 are electrically connected via the terminal. Note that the bus bar 15 is provided in the number corresponding to the number of phases of the motor 4 (here, three phases of U phase, V phase, and W phase).

[0016] Furthermore, as described above, a cover member 10 is attached to the motor housing 5, and a circuit board 6 for controlling (i.e., driving) the motor 4 is accommodated in an accommodation space 16 formed between the cover member 10 and the motor housing 5. And a heat dissipation member 17 is provided between the circuit board 6 and the motor housing 5. That is, the circuit board 6 is in contact with the motor housing 5 via the heat dissipation member 17. As the heat dissipation member 17, for example, heat dissipation grease, heat dissipation adhesive, heat dissipation pad, heat dissipation sheet, etc. are assumed, but in order to dissipate the heat generated by the circuit board 6, the heat dissipation member 17 is preferably a member with low thermal resistance. Therefore, in the present embodiment, for example, heat dissipation grease or heat dissipation adhesive with relatively low thermal resistance is used.

[0017] The circuit board 6 is arranged axially on the side opposite to the impeller 9 with respect to the motor 4 (corresponding to the other side of the rotation axis X with respect to the motor 4). Electronic components 19 such as an inverter circuit, a coil, and a capacitor that are driven by receiving power supply from the power terminal 18 are mounted on this circuit board 6. In the example shown in FIG. 1, the electronic components 19 are provided on the cover member 10 side in the axial direction with respect to the circuit board 6. Terminals (not shown) are electrically connected to the electronic components 19. And, through holes (not shown) that function as connection parts to which the terminals are electrically connected are formed in the circuit board 6. That is, in the present embodiment, the terminals are inserted into the through holes and soldered using pads (or lands) existing around the through holes, thereby being electrically connected to the circuit board 6. Further, a plurality of wirings are formed on both surfaces of the circuit board 6 with copper or the like. The wirings formed on both surfaces of the circuit board 6 are electrically connected through through holes formed at a plurality of positions of the circuit board 6. Therefore, the heat generated in the electronic components 19 mounted on one surface of the circuit board 6 is also transmitted to the surface on the opposite side of the surface on which the electronic components 19 are mounted in the circuit board 6 through the plurality of wirings. Therefore, the heat generated in the electronic components 19 is also transmitted to the contact surface side of the circuit board 6 and the motor housing 5. The power terminal 18 is provided outside the motor housing 5 in the vicinity of the circuit board 6 as shown in FIG. 1. And the circuit board 6 is fastened to the motor housing 5 with screws or the like. That is, in the present embodiment, the circuit board 6 and the motor housing 5 are arranged in the order of the heat dissipation member 17, the wiring, and the circuit board 6 when viewed from the motor housing 5 side. In other words, the motor housing 5 is in contact with and fastened to the circuit board 6 through the heat dissipation member 17 and the wiring in order.

[0018] Since the bush 8 slides with the shaft 7, a material with high wear resistance and heat resistance is used. For example, it is composed of a carbon bearing such as carbon fiber. The bush 8 is not particularly limited as long as it is a material with high wear resistance and heat resistance, and may be composed of a metal such as aluminum or a resin, for example.

[0019] The impeller 9 is arranged axially on the side opposite to the circuit board 6 with respect to the motor 4 (corresponding to one side of the rotation axis X with respect to the motor 4). The impeller 9 has a plurality of blade members 21 curved inside the shroud 20 and is covered with an impeller housing 11. These blade members 21 are welded (for example, vibration welding) to one end 2a of the rotor 2 on the impeller 9 side. In the example shown in FIG. 1, among the plurality of blade members 21, two representative blade members are labeled. The electric pump 1 is configured such that the current to the stator coil 13 wound around the stator 3 is controlled via the circuit board 6 by an ECU of a vehicle (not shown), so that the permanent magnet 12 in the rotor 2 receives a magnetic field and the bush 8 and the rotor 2 rotate integrally. When the bush 8 and the rotor 2 rotate integrally, the impeller 9 fixed to one end 2a of the rotor 2 also rotates.

[0020] The impeller housing 11 has a suction port 11a for sucking cooling water into the pump chamber and a discharge port (not shown) for discharging the cooling water from the pump chamber. A water chamber 22 is formed between the impeller housing 11 and the motor housing 5. As the impeller 9 rotates in the water chamber 22 as the rotor 2 rotates, the cooling water flows spirally from the suction port 11a to the outer peripheral side of the impeller 9. At this time, most of the cooling water is sent out to the outside from the discharge port, but a part of the cooling water flows out from the outer peripheral side of the impeller 9, circulates inside the motor housing 5, and is discharged from the discharge port. In this way, by circulating a part of the cooling water inside the motor housing 5, the rotor 2, the stator 3, etc. are cooled and foreign matters mixed in the cooling water are discharged. As shown in FIG. 1, seal members (for example, O-rings) 23 for preventing the leakage of the cooling water are provided at each part in contact with the motor housing 5. In the example shown in FIG. 1, there are a plurality of seal members 23, and two representative seal members are labeled.

[0021] Next, the effects of the electric pump 1 in the present embodiment will be described. When the electric pump 1 is driven, current flows through the electronic components 19 on the circuit board 6 and the stator coil 13 of the stator 3, generating heat. Due to this heat generation, for example, if the circuit board 6 and the stator 3 are exposed to high temperatures, the electronic components 19 may be damaged or the performance of the motor 4 may deteriorate. Therefore, a configuration capable of dissipating the heat generated in this way is required. Thus, in the present embodiment, as described above, the motor housing 5 is formed of an aluminum die-cast housing as an example of a metal housing. And the stator 3 is in contact with this motor housing 5. Thereby, the heat generated in the stator 3 can be transferred to the motor housing 5, and the heat generated in the stator 3 can be dissipated. In other words, the heat generated in the stator 3 can be absorbed by the motor housing 5. As a result, for example, the temperature of the motor 4 exposed to high temperatures can be lowered, and thus the deterioration of the performance of the motor 4 can be suppressed.

[0022] Also, in the present embodiment, the motor housing 5 is in contact with the circuit board 6 via the heat dissipation member 17. That is, the heat generated in the circuit board 6 can be transferred (i.e., dissipated) to the motor housing 5 via the heat dissipation member 17. In other words, the heat generated in the circuit board 6 can be absorbed by the motor housing 5. Also, as described above, cooling water is flowing inside the motor housing 5. Therefore, it becomes possible to cool the heat absorbed from the circuit board 6 with the cooling water. And by being able to dissipate the heat generated in the circuit board 6 in this way, for example, the temperature of the circuit board 6 exposed to high temperatures can be lowered, and thus the damage to the circuit board 6 and the deterioration of the performance of the circuit board 6 can be suppressed. In this way, in the present embodiment, the stator 3 and the circuit board 6 are each configured to be able to dissipate heat to the metal motor housing 5, and as a result, the possibility of dissipating the heat generated in the circuit board 6 and the motor 4 can be increased.

[0023] Also, in the present embodiment, the water chamber 22 is formed so as to be in contact with the motor housing 5. As the rotor 2 rotates, the impeller 9 rotates, and a part of the cooling water flows out from the outer peripheral side of the impeller 9 and circulates inside the motor housing 5. As a result, it is possible to effectively cool portions such as the rotor 2, the stator 3, and the shaft 7 that are likely to become hot.

[0024] Also, in the present embodiment, as described above, the stator 3 is brought into contact with the motor housing 5 disposed on the radially outer side, and is fixed to the motor housing 5 by press-fitting, shrink-fitting, or the like. Thereby, for example, compared with the case where the stator is fixed to a resinous stator housing as in the electric pump described in the above-mentioned Patent Document 1, the heat dissipation property (that is, the heat transfer property) can be enhanced. Further, in the present embodiment, since there is no stator housing as in the electric pump described in Patent Document 1, the number of components constituting the motor can be reduced, and as a result, the cost of the entire electric pump can be reduced.

[0025] Also, in the present embodiment, as described above, the terminal is inserted into the through-hole formed in the circuit board 6 and soldered using the pads (or lands) existing around the through-hole, whereby the terminal is electrically connected to the circuit board 6. By configuring in this way, for example, compared with the case where the electronic component 19 and the pads are provided on the same surface of the circuit board (for example, the surface on the cover member 10 side in FIG. 1), the heat generated in the circuit board 6 can be induced to the motor housing 5 side, and as a result, the heat dissipation property of the heat generated in the circuit board 6 can be enhanced.

[0026] In addition, in the present embodiment, a plurality of wirings are formed on both surfaces of the circuit board 6, and are electrically connected via through-holes formed at a plurality of positions on the circuit board 6. Therefore, the heat generated in the electronic component 19 mounted on one surface of the circuit board 6 is also transmitted to the surface on the opposite side of the surface of the circuit board 6 where the electronic component 19 is mounted via the plurality of wirings. That is, the motor housing 5 is in contact with the circuit board 6 via the heat radiating member 17 and the wiring in this order. As a result, the heat generated in the electronic component 19 can also be transmitted to the contact surface side between the circuit board 6 and the motor housing 5, and the heat dissipation of the heat generated in the circuit board 6 can be further enhanced.

[0027] Also, in the present embodiment, as described above, by fixing the stator 3 to the motor housing 5 by press-fitting, shrink-fitting, or the like, a space is created below the stator 3. In the present embodiment, the bus bar 15 is housed in that space. By adopting such a fixing means for the stator 3, the space can be effectively utilized. As a result, for example, compared with the case of fixing the stator to the stator housing as in the electric pump of Patent Document 1 cited above, the size of the motor can be reduced, and the size of the entire electric pump can be reduced.

[0028] Also, in the present embodiment, as described above, the motor housing 5 is made of aluminum die-cast. As the metal housing, in addition to aluminum die-cast, for example, zinc die-cast (zinc alloy) or the like is assumed. However, aluminum die-cast is advantageous in that it is lighter and stronger than, for example, zinc die-cast, and is less likely to deteriorate over time. In addition, aluminum die-cast has higher thermal conductivity than zinc die-cast. Therefore, it is also advantageous from the viewpoint of heat dissipation. That is, by adopting the aluminum die-cast motor housing 5, the durability and heat dissipation can be improved.

[0029] (2) Other embodiments, etc.: The above embodiments are examples for implementing the present invention and are not limited thereto, and various other embodiments can be adopted. For example, although the motor housing 5 was described as an example of a metallic housing made of aluminum die-cast, it is not limited thereto as long as it is metallic. For example, instead of being made of aluminum die-cast, it may be made of the above-mentioned zinc die-cast. Zinc die-cast is advantageous in terms of high workability compared to, for example, aluminum die-cast etc.

[0030] The heat dissipation member 17 may be any member interposed between the motor housing 5 and the circuit board 6. That is, the circuit board 6 is fixed to the motor housing 5 with the heat dissipation member 17 present between the circuit board 6 and the motor housing 5. In the above-described embodiment, an example using a heat dissipation grease or a heat dissipation adhesive was described from the viewpoint of thermal resistance. However, for example, when the shape of the circuit board 6 is complicated, etc., a heat dissipation sheet etc. whose shape is more stable than the heat dissipation grease or the heat dissipation adhesive may be used. Also, the shape, size, etc. of the heat dissipation member 17 are not limited. For example, if the heat dissipation member 17 is a heat dissipation grease, it is applied to cover the entire surface of the circuit board 6.

[0031] The circuit board 6 only needs to include a drive circuit for the electronic component 19. That is, the electronic component 19 is driven by the drive circuit on the board. The connection part on the circuit board 6 is a part where a terminal is connected in order to electrically connect the drive circuit on the board and the electronic component via the terminal, and in addition to through holes, various connectors etc. may be used, or it may be a part where the terminal is soldered, and it may have various configurations.

Explanation of reference numerals

[0032] 1... Electric pump, 2... Rotor, 2a... One end of the rotor, 3... Stator, 4... Motor, 5... Motor housing, 5a... Bottom (of the motor housing), 6... Circuit board, 7... Shaft, 7a... End (of the shaft), 8... Bush, 9... Impeller (pump section), 10... Cover member, 11... Impeller housing, 11a... Suction port, 12... Permanent magnet, 13... Stator coil, 14... Support portion, 15... Bus bar, 16... Accommodation space, 17... Heat dissipation member, 18... Power supply terminal, 19... Electronic component, 20... Shroud, 21... Vane member, 22... Water chamber, 23... Seal member.

Claims

1. A motor having a rotor that rotates about a rotation axis and a stator disposed opposite to the rotor, a metallic housing that houses the motor, a pump unit disposed on one side of the rotation axis with respect to the motor and that rotates by the driving force of the motor to pump a refrigerant, a circuit board disposed on the other side of the rotation axis with respect to the motor and that drives the motor, an electric pump comprising: the housing contacts the stator and contacts the circuit board via a heat dissipation member, the electric pump.

2. The stator is fixed in contact with the housing, The electric pump according to claim 1.

3. Electronic components are provided on the circuit board, wiring is electrically connected to the electronic components, the housing contacts the circuit board via the heat dissipation member and the wiring in that order, The electric pump according to claim 1.

4. A bus bar is disposed in the space on the circuit board side formed by fixing the stator to the housing, The electric pump according to claim 2.

5. The metallic housing is made of aluminum die-cast, The electric pump according to claim 1.

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