Electric supercharger

Abstract

An electric supercharger (1) is provided with a motor (20) having a stator (22) and a diffusion plate (40) that is thermally connected to a stator main surface (22a) of the stator (22). The diffusion plate (40) has a main surface side cooling flow path (F1) through which a heat medium flows.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an electric supercharger. BACKGROUND

[0002] An electric supercharger is heated from compressed air. The electric supercharger is provided with a motor that rotates an impeller, but the motor also becomes a heat source. If the temperature of a component that constitutes the electric supercharger rises due to the heat of the compressed air and the heat of the motor and the like, a case in which the electric supercharger cannot exert the intended performance occurs. Therefore, as disclosed in Patent Documents 1 and 2, the electric supercharger is provided with a cooling structure for cooling the constituent component. The cooling structure of Patent Document 1 is directed to the cooling of the motor and the impeller. The cooling structure of Patent Document 2 is directed to the cooling of the impeller.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2010-196478

[0004] Patent Document 2: Japanese Patent Application Publication No. 2017-150339

[0005] It is desired that the electric supercharger further improve the performance. In order to improve the performance of the electric supercharger, it is necessary to increase the output of the motor. In order to increase the output of the motor, a large current is supplied to the motor. The motor to which the large current is supplied further generates heat. If the temperature of the motor rises due to the heat, the output of the motor can decrease. Therefore, it is necessary to further improve the cooling performance. SUMMARY

[0006] The present disclosure describes an electric supercharger that can further improve the cooling performance.

[0007] The electric supercharger of the present disclosure is provided with a motor having a stator, and a diffusion plate that is thermally connected to an end surface of the stator. The diffusion plate has a flow path through which a heat medium flows.

[0008] The electric supercharger of the present disclosure can further improve the cooling performance. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 is a cross-sectional view that schematically shows the structure of the electric supercharger of the present disclosure.

[0010] Figure 2 is Figure 1 is an exploded perspective view of the diffusion plate shown in

[0011] Figure 3 is a front view showing the relationship between the diffusion plate and the stator. DETAILED DESCRIPTION

[0012] The electric supercharger of the present disclosure is provided with a motor having a stator, and a diffusion plate that is thermally connected to an end surface of the stator. The diffusion plate has a flow path through which a heat medium flows.

[0013] The thermal resistance from the portion of the stator that generates heat to the end surface of the stator is small. Therefore, by thermally connecting the diffusion plate to the end surface of the stator and circulating the heat medium in the flow path of the diffusion plate, heat can be efficiently absorbed from the stator. Therefore, the cooling efficiency can be further improved.

[0014] The electric supercharger of the present disclosure can also have an impeller that rotates by being attached to a rotating shaft of the motor, and a compressor housing that houses the impeller and has a scroll flow path that surrounds the impeller. The diffusion plate can also be a circular plate having a first end surface and a second end surface. The first end surface can also be thermally connected to the end surface of the stator. The second end surface can also cooperate with the compressor housing to form a diffusion flow path that guides fluid discharged from the impeller from the impeller to the scroll flow path. According to such a structure, good cooling efficiency can also be obtained.

[0015] In the electric supercharger of the present disclosure, the diffusion plate can also have a first plate member including the first end surface, and a second plate member including the second end surface. The thermal conductivity of the first plate member can also be different from the thermal conductivity of the second plate member. According to this structure, heat can be moved from the side of the first plate member having a high thermal conductivity to the heat medium. Therefore, the stator can be efficiently cooled.

[0016] In the electric supercharger of the present disclosure, the thermal conductivity of the first plate member can also be higher than the thermal conductivity of the second plate member. According to this structure, heat can be more efficiently moved from the side of the first plate member having a high thermal conductivity to the heat medium. Therefore, the stator can be more efficiently cooled.

[0017] In the electric supercharger of the present disclosure, the temperature to which the first plate member is subjected can also be lower than the temperature to which the second plate member is subjected. According to this method, the electric supercharger can also efficiently extract heat from the stator. Therefore, the stator can be more efficiently cooled.

[0018] Hereinafter, a method for implementing the electric supercharger of the present disclosure will be described in detail with reference to the drawings. In the description of the drawings, the same reference numerals are assigned to the same elements, and repetitive descriptions will be omitted.

[0019] Figure 1 is a cross-sectional view of the electric supercharger 1 of the present disclosure. As shown in Figure 1 The electric supercharger 1 has a compressor 10 and a motor 20. The electric supercharger 1 drives the compressor 10 by the motor 20 that uses electric power as a power source. The compressor 10 receives power from the motor 20 via a rotating shaft 30. The electric supercharger 1 discharges compressed air.

[0020] The compressor 10 has an impeller 11 and a compressor housing 12. The compressor housing 12 has a suction inlet 13 and a vortex flow path 14. The suction inlet 13 is an opening coaxial with the rotation shaft 30. The vortex flow path 14 surrounds the rotation shaft RL. The impeller 11 is disposed inside the suction inlet 13. The vortex flow path 14 surrounds the impeller 11. According to the above configuration, air drawn in from the suction inlet 13 reaches the vortex flow path 14 via the impeller 11. A diffuser flow path 15 is formed between the impeller 11 and the vortex flow path 14. The diffuser flow path 15 receives air from the impeller 11. The diffuser flow path 15 transfers the received air to the vortex flow path 14. The diffuser flow path 15 is formed by the outer wall surface 12a of the compressor housing 12 and the diffuser plate 40 described later.

[0021] Motor 20 has a rotor 21 and a stator 22. The rotor 21 is fixed to a rotating shaft 30. The rotor 21 rotates together with the rotating shaft 30. The rotor 21 includes, for example, a plurality of permanent magnets. The stator 22 is a component arranged to surround the rotor 21. The stator 22 includes coils.

[0022] The motor 20 also includes a stator housing 23, a passage block 24, and a motor outer casing 25. The stator housing 23 houses the stator 22 and the rotor 21. The stator housing 23 is cylindrical. The stator 22 is fixed inside the stator housing 23. One end of the stator housing 23 forms a housing opening 23a (see reference). Figure 2 The other end of the stator housing 23 is closed by the housing end face 23b. The housing end face 23b cooperates with the motor housing 25 (described later) to form the rear side cooling flow path F2.

[0023] like Figure 2 As shown, a housing rib 23d is disposed on the outer peripheral surface 23c of the stator housing 23. A passage block 24 is mounted on the housing rib 23d. The passage block 24 is a separate component from the stator housing 23. The passage block 24 has a back surface 24a and a main surface 24b. The back surface 24a abuts against the housing rib 23d. The main surface 24b abuts against the diffuser plate 40. The passage block 24 has a connecting flow path 24F. The connecting flow path 24F is a hole extending from the back surface 24a to the main surface 24b. The connecting flow path 24F connects the back surface cooling flow path F2 to the main surface cooling flow path F1 of the diffuser plate 40, which will be described later.

[0024] The housing opening 23a is closed by the diffusion plate 40. As described above, the diffusion plate 40 cooperates with the compressor housing 12 to constitute the diffusion flow path 15. The diffusion plate 40 separates the compressor 10 from the motor 20. The diffusion plate 40 has a motor-side circular plate 41 (first plate member) and a compressor-side circular plate 42 (second plate member). The motor-side circular plate 41 is a thin plate that is circular in plan view. In other words, the motor-side circular plate 41 is a thin plate that is circular in view from the direction of the rotation axis RL. The compressor-side circular plate 42 is also a thin plate that is circular in plan view. In other words, the compressor-side circular plate 42 is also a thin plate that is circular in view from the direction of the rotation axis RL. The diffusion plate 40 is constituted by the main surface of the motor-side circular plate 41 abutting against the back surface of the compressor-side circular plate 42. The motor-side circular plate 41 has a motor-side hole 41H as a through hole. The compressor-side circular plate 42 also has a compressor-side hole 42H as a through hole. The centers of the motor-side hole 41H and the compressor-side hole 42H coincide with the rotation axis RL. The motor-side hole 41H and the compressor-side hole 42H are coaxial.

[0025] The material constituting the motor-side circular plate 41 is different from the material constituting the compressor-side circular plate 42. The thermal conductivity of the material constituting the motor-side circular plate 41 is different from the thermal conductivity of the material constituting the compressor-side circular plate 42. The thermal conductivity of the motor-side circular plate 41 is higher than the thermal conductivity of the compressor-side circular plate 42. For example, as the material constituting the motor-side circular plate 41, a metal material such as an aluminum alloy can be used. As the material constituting the compressor-side circular plate 42, a heat-resistant resin material such as a polyphenylene sulfide resin or a phenol resin can be used.

[0026] By selecting materials having different thermal conductivities, it is possible to cause the heat movement from the motor 20 to the diffusion plate 40 and the heat movement from the compressor 10 to the diffusion plate 40 to have a bias. The diffusion plate 40 actively receives heat from the motor-side circular plate 41 having a high thermal conductivity. By selecting a resin material having a low thermal conductivity, it is possible to suppress the heat movement from the compressor 10 side to the motor 20 side.

[0027] The motor-side circular plate 41 has a motor-side back surface 41a (first end surface) and a motor-side main surface 41b. The motor-side back surface 41a also contacts the motor 20. The motor-side back surface 41a abuts against the passage block 24. The motor-side back surface 41a also connects with the stator main surface 22a of the stator 22 housed in the stator housing 23.

[0028] The term "connection" as used here refers to a thermal connection. A thermal connection is assumed to exist as a gap between the motor-side back surface 41a and the stator main surface 22a. Based on this assumption, a state where the thermal resistance from the motor-side back surface 41a to the stator main surface 22a is less than the thermal resistance in a state where the gap is filled with air can also be defined as a "thermal connection." An example of a "thermal connection" is a state where the motor-side back surface 41a and the stator main surface 22a are in physical contact. In a state of physical contact, no substantial air layer affecting thermal movement is formed between the stator main surface 22a and the motor-side back surface 41a. Therefore, heat moves well from the stator main surface 22a to the motor-side back surface 41a. Another example of a "thermal connection" is a state where, although a gap exists between the stator main surface 22a and the motor-side back surface 41a, this gap is filled with a thermally conductive material such as thermally conductive grease. Since the thermal conductivity of the thermally conductive material is higher than that of air, heat moves well from the motor-side back surface 41a to the stator main surface 22a.

[0029] A flow path groove 41G is formed on the motor-side main surface 41b. The flow path groove 41G is a recess carved into the motor-side main surface 41b. The flow path groove 41G includes a through hole 41G1, an annular groove 41G2, and a connecting groove 41G3. The through hole 41G1 extends from the motor-side main surface 41b to the motor-side back surface 41a. The through hole 41G1 connects to the connecting flow path 24F of the passage block 24 at the motor-side back surface 41a. Therefore, the motor-side back surface 41a is watertightly connected to the passage block 24.

[0030] like Figure 3 As shown, the annular groove 41G2 is annular in shape, surrounding the rotation axis RL. The annular groove 41G2 can also overlap with the stator main surface 22a when viewed from above the rotation axis RL. For example, the entire annular groove 41G2 can overlap with the stator main surface 22a, or only a portion of the annular groove 41G2 can overlap with the stator main surface 22a. The manner of overlap with the stator main surface 22a can be adjusted by the diameter of the annular groove 41G2. The manner of overlap with the stator main surface 22a can also be adjusted by the groove width of the annular groove 41G2. The annular groove 41G2 is formed with a central angle of 180 degrees or more around the rotation axis RL. This angle can be set according to the position of the connecting flow path 24F of the passage block 24.

[0031] When the through hole 41G1, which serves as the connection portion to the connecting flow path 24F, is positioned further outward than the annular groove 41G2, a connecting groove 41G3 is provided to connect the through hole 41G1 and the annular groove 41G2. The connecting groove 41G3 can be provided as needed based on the positional relationship between the annular groove 41G2 and the through hole 41G1. For example, if the through hole 41G1 overlaps with the annular groove 41G2, the connecting groove 41G3 can be omitted.

[0032] Again Figure 2 As shown, the compressor-side circular plate 42 has a compressor-side back surface 42a and a compressor-side main surface 42b (second end face). The compressor-side back surface 42a abuts against the motor-side main surface 41b. The compressor-side back surface 42a closes the openings of the through hole 41G1, the annular groove 41G2, and the connecting groove 41G3 formed on the motor-side main surface 41b. Therefore, the compressor-side main surface 42b, together with the through hole 41G1, the annular groove 41G2, and the connecting groove 41G3, constitutes the main surface-side cooling flow path F1. The compressor-side main surface 42b includes an impeller region 42b1 and a diffusion region 42b2. The impeller region 42b1 is opposite to the impeller 11. The diffusion region 42b2 constitutes the diffusion flow path 15. The diffusion region 42b2 surrounds the impeller region 42b1.

[0033] The various components of the electric supercharger 1 have been described in detail. Next, we will focus on the cooling mechanism of the electric supercharger 1. The cooling mechanism cools the motor 20. An increase in the temperature of the motor 20 affects its characteristics. Specifically, if the temperature of the motor 20 rises too much, there is a tendency for the output of the motor 20 to decrease. Therefore, the motor 20 needs to operate at a temperature not exceeding a preset value. On the other hand, in the motor 20, current is supplied to the coil as a power source. Heat is generated due to resistance when the current flows through the coil. The higher the output of the motor 20, the larger the current flows, and therefore the greater the degree of heat generation. Furthermore, if air is compressed in the compressor 10, the compressed air becomes very hot. For example, the temperature of the compressed air can reach 280 degrees Celsius or higher. That is, heat is generated during the operation of the electric supercharger 1 due to various factors. Therefore, it is necessary to actively dissipate the heat so that the temperature of the motor 20 does not exceed the set value due to this heat. Therefore, the electric supercharger 1 has a cooling mechanism including a rear-side cooling flow path F2 and a main surface-side cooling flow path F1.

[0034] The main heat source of the motor 20 is the stator 22, which includes coils. The coils of the stator 22 are wound around a component such as teeth. The gaps between the wires constituting the coils are filled with resin material. The cooling mechanism efficiently absorbs heat from the stator 22.

[0035] The cooling mechanism uses both end surfaces of the stator 22 as a heat path. The cooling mechanism sandwiches the stator 22 along the rotation axis RL. A back surface side cooling flow path F2 is provided on the stator back surface side. The back surface side cooling flow path F2 is constituted by the motor housing 25 and the stator case 23. The grooves constituting the back surface side cooling flow path F2 can also be provided to the motor housing 25. The grooves constituting the back surface side cooling flow path F2 can also be provided to the stator case 23. A main surface side cooling flow path Fl is provided on the stator main surface 22a side. The main surface side cooling flow path Fl is constituted by the diffusion plate 40. The main surface side cooling flow path Fl and the back surface side cooling flow path F2 are connected to each other by the passage block 24. The back surface side cooling flow path F2, the main surface side cooling flow path Fl, and the connecting flow path 24F are in communication with each other. The back surface side cooling flow path F2, the main surface side cooling flow path Fl, and the connecting flow path 24F constitute one flow path.

[0036] The electric supercharger 1 is provided with the motor 20 having the stator 22, and the diffusion plate 40 thermally connected to the stator main surface 22a. The diffusion plate 40 has the main surface side cooling flow path Fl through which a heat medium flows. The thermal resistance from the heat generating portion of the stator 22 to the stator main surface 22a is small. Therefore, by thermally connecting the diffusion plate 40 to the stator main surface 22a and causing the heat medium to flow through the main surface side cooling flow path Fl of the diffusion plate 40, heat can be efficiently absorbed from the stator 22. Therefore, the cooling efficiency can be further improved.

[0037] The diffusion plate 40 is a circular plate. The diffusion plate 40 has a motor side back surface 41a and a compressor side main surface 42b. The motor side back surface 41a is thermally connected to the stator main surface 22a. The compressor side main surface 42b cooperates with the compressor housing 12 to form a diffusion flow path 15 that guides the fluid discharged from the impeller 11 from the impeller 11 to the scroll flow path 14. In the electric supercharger 1, the diffusion plate 40 has a motor side circular plate 41 including the motor side back surface 41a, and a compressor side circular plate 42 including the compressor side main surface 42b. The thermal conductivity coefficient of the motor side circular plate 41 is different from the thermal conductivity coefficient of the compressor side circular plate 42. More specifically, the thermal conductivity coefficient of the motor side circular plate 41 is higher than the thermal conductivity coefficient of the compressor side circular plate 42. Furthermore, in the electric supercharger 1, the temperature to which the motor side circular plate 41 is subjected is lower than the temperature to which the compressor side circular plate 42 is subjected.

[0038] In addition, it has been described that the back surface side of the diffusion plate 40 is thermally connected to the motor 20, and the main surface side of the diffusion plate 40 forms the diffusion flow path 15.

[0039] The temperature on the motor 20 side is lower than the temperature on the compressor 10 side. In other words, when viewed based on the temperature of the heat medium flowing in the diffusion plate 40, the temperature difference between the temperature of the heat medium and the temperature on the motor 20 side is smaller than the temperature difference between the temperature of the heat medium and the temperature on the diffusion flow path 15 side. The easiness of heat movement is proportional to the temperature difference. The greater the temperature difference, the easier the heat movement. If only the temperature relationship is considered, for the heat movement toward the diffusion plate 40, the heat movement from the compressor 10 side tends to become dominant. As a result, the heat absorption from the motor 20, which is the cooling target, becomes insufficient, and it can not be possible to sufficiently cool the stator 22.

[0040] Therefore, the diffusion plate 40 of the embodiment is composed of materials having different thermal conductivities from each other. Specifically, for the components on the motor 20 side, which are intended to actively absorb heat, a material having a higher thermal conductivity than the material of the components on the compressor 10 side, which are intended to suppress the inflow of heat, is applied. On the other hand, for the components on the compressor 10 side, which are intended to suppress the inflow of heat, a material having a lower thermal conductivity than the material of the components on the motor 20 side, which are intended to actively absorb heat, is applied. The components having a high thermal conductivity are arranged on the side where the temperature is low, and the components having a low thermal conductivity are arranged on the side where the temperature is high. According to such a structure, it is possible to cause the heat to move well from the motor 20 side, which is relatively low in temperature, to the heat medium.

[0041] The electric supercharger of the present disclosure is not limited to the structure and method of the above-described embodiment.

[0042] Explanation of Reference Numerals:

[0043] 1… electric supercharger; 10… compressor; 11… impeller; 12… compressor housing; 12a… housing wall surface; 13… suction port; 14… scroll flow path; 15… diffusion flow path; 20… motor; 21… rotor; 22… stator; 22a… stator main surface; 23… stator housing; 23a… housing opening; 23b… housing end surface; 23c… housing peripheral surface; 23d… housing rib; 24… passage block; 24a… block back surface; 24b… block main surface; 24F… link flow path; 25… motor housing; 30… rotary shaft; 40… diffusion plate; 41… motor-side circular plate (first plate member); 41a… motor-side back surface (first end surface); 41b… motor-side main surface; 41G… flow path groove; 41G1… through hole; 41G2… circular ring groove portion; 41G3… link groove portion; 41H… motor-side hole; 42… compressor-side circular plate (second plate member); 42a… compressor-side back surface; 42b… compressor-side main surface (second end surface); 42b1… impeller region; 42b2… diffusion region; 42H… compressor-side hole; F1… main surface-side cooling flow path; F2… back surface-side cooling flow path; RL… rotary shaft line.

Claims

1. An electric supercharger characterized by, Possessing: a motor having a stator; and a diffusion plate thermally connected to an end surface of the stator; an impeller that rotates by a rotating shaft installed to the motor; and a compressor housing that houses the impeller and has a scroll flow path that surrounds the impeller, the diffusion plate has a cooling flow path through which a heat medium flows, the diffusion plate is a circular plate having a first plate member including a first end surface that is thermally connected to an end surface of the stator, and a second plate member including a second end surface that cooperates with the compressor housing to form a diffusion flow path that guides fluid discharged from the impeller from the impeller to the scroll flow path, a thermal conductivity of the first plate member is higher than a thermal conductivity of the second plate member.

2. The electric supercharger according to claim 1, wherein a temperature to which the first plate member is subjected is lower than a temperature to which the second plate member is subjected. ​

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