Rotating electric machine

Abstract

A rotating electrical machine is provided with: a rotor having a rotor core formed by laminating a plurality of electromagnetic steel sheets, and a shaft supporting the rotor core; a stator facing the rotor across a predetermined space, i.e., an air gap, on the outside in the radial direction of the rotor; and a housing that houses the rotor and the stator, the housing forming an air flow path between the rotor and the stator, the shaft having a shaft flow path communicating with the air flow path, and the rotor having a pump connected to the shaft and synchronized with rotation of the shaft, and a radial flow path communicating the shaft flow path and the air gap.

Description

Technical Field

[0001] The invention relates to a rotating electric machine. Background Art

[0002] In the manufacture of rotating electrical machines, as one of the means for achieving high output density and utilizing low-grade magnets, a direct oil cooling structure is adopted as one of the technologies for cooling rotating electrical machines. In the direct oil cooling structure, cooling oil is discharged into the motor housing, but in this way, the cooling oil will intrude into the air gap between the rotor and the stator, causing stirring loss and reducing the efficiency of the motor. Therefore, it is necessary to develop a rotating electrical machine that has both high cooling performance and high efficiency by suppressing the intrusion of cooling oil into the air gap.

[0003] The rotating electric machine described in Patent Document 1 has the following structure: fans 16 and 17 are arranged on the outer peripheries of the end plates 2B and 2C on both sides of the rotor 2, and the fan 16 on one side delivers air from the space 12A to the gap G, and the fan 17 on the other side discharges air from the gap G to the space 12B on the side of the rotor 2, thereby generating a pressure difference by utilizing the pump effect generated in the holes set in the rotor due to the rotation of the motor. Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent Application Publication No. 2003-250248. Summary of the invention Problem that the invention aims to solve

[0005] In the technology of Patent Document 1, the infiltration of cooling oil into the gap is suppressed to reduce the stirring loss. However, if the pressure required to suppress the infiltration of cooling oil is to be generated in a simple straight flow path, the stirring loss reduction effect cannot be expected in the low and medium speed range of the motor rotation, and the high-speed rotation of the motor is required. Therefore, when the motor rotates at a high speed, the flow rate of cooling oil increases, so there is a problem of increased pump loss.

[0006] In view of the above, an object of the present invention is to provide a rotating electric machine capable of suppressing the stirring loss of cooling oil generated in an air gap in a range from a low speed region to a high speed region of the electric motor. Technical means of solving problems

[0007] A rotating electric machine comprises: a rotor having a rotor core formed by stacking a plurality of electromagnetic steel plates and a shaft supporting the rotor core; a stator opposing the rotor with a predetermined space, i.e., an air gap, separated therefrom on the radially outer side of the rotor; and a housing accommodating the rotor and the stator, wherein the housing forms an air flow path between the rotor and the stator, the shaft has an axial flow path connected to the air flow path, and the rotor has: a pump connected to the shaft and synchronous with the rotation of the shaft, and a radial flow path connecting the axial flow path and the air gap. Effects of the Invention

[0008] It is possible to provide a rotating electrical machine that suppresses the occurrence of stirring loss of cooling oil in an air gap. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a diagram showing the configuration of a rotating electrical machine according to one embodiment of the present invention. Figure 2 This is an explanatory diagram of an air flow path in a casing according to one embodiment of the present invention. Figure 3 This is a diagram for explaining the oil path in the housing. Figure 4 This is the first modification example. Figure 5 This is a diagram showing the configuration of a pump according to one embodiment of the present invention. Figure 6 These are the second and third variations. Figure 7 This is the fourth variation. DETAILED DESCRIPTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following descriptions and drawings are examples for illustrating the present invention, and are appropriately omitted and simplified for clarity of the description. The present invention may also be implemented in various other ways. Unless otherwise specified, each component may be single or multiple.

[0011] In order to facilitate understanding of the present invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not limited to the position, size, shape, range, etc. disclosed in the drawings.

[0012] (One embodiment and overall structure of the present invention) ( Figure 1 ) The rotating electric machine 1 includes: a rotor having a rotor core 2 formed by laminating a plurality of electromagnetic steel sheets and a shaft 6 supporting the rotor core 2; a stator 3 (stator core 3) facing the rotor with an air gap 8 as a predetermined space interposed therebetween on the radially outer side of the rotor core 2; and a housing 4 accommodating the rotor and the stator 3. Although not shown, a gear connected to the shaft 6 is provided outside the rotating electric machine 1. In the following description, the gear side is the left side of the drawing, and the opposite side of the gear is the right side of the drawing.

[0013] The housing 4 has an air flow path 4a between the rotor and the stator 3. The air flow path 4a is formed so as to communicate from the upper part of the housing 4 to the opposite side of the gear. The shaft 6 has an axial flow path 6a communicated with the air flow path 4a, and is structured so as to flow air 10 from the opposite side of the gear of the shaft 6. In addition, the rotor has a pump 7 connected to the shaft 6 and synchronized with the rotation of the shaft, and a radial flow path 2a communicating with the axial flow path 6a and the air gap 8. In addition, in Figure 1 , an example is shown in which the pump 7 is arranged so as to be sandwiched between a plurality of electromagnetic steel sheets.

[0014] The pump 7 is connected to the shaft 6 and rotates together with the rotation of the motor, and can generate centrifugal force. As a result, a pressure difference is generated between the air gap 8 and the inside of the housing 4, and the pressure required to suppress the infiltration of the cooling oil into the air gap 8 is obtained, so that the effect of reducing the stirring loss can be obtained. In addition, by configuring such a pump 7, the infiltration of the cooling oil into the air gap 8 can be suppressed not only in the high-speed area but also in a wide speed range including the low-speed area, and the pump loss in the high-speed area can be reduced.

[0015] As air circulates in the air flow path 4a, an airflow is generated from the air gap 8 toward the inside of the housing 4 via the connected axial flow path 6a and radial flow path 2a. As a result, the cooling oil intruding into the air flow path 4a, the axial flow path 6a, and the radial flow path 2a is stirred, and the infiltration of the cooling oil into the air gap 8 can be suppressed. Indeed, when the motor speed of the rotating electrical machine 1 increases, the stirring loss also increases, but since the air volume increases, the stirring loss can be reduced as a result, so that the cooling efficiency of the rotating electrical machine 1 and the motor efficiency can be improved.

[0016] In addition, when the pump 7 is provided on the rotor, it can be arranged at any position within the range of the length of the air gap 8. In addition, the pump 7 can also be formed by laminating electromagnetic steel sheets, or by mixing resin and pressed powder cores. When the pump 7 is formed by mixing resin and pressed powder cores, the loss caused by the magnetic field of the stator when it is made of a simple metal block can be avoided.

[0017] The radial flow path 2a is formed at the axial center of the rotor core 2. The axial flow path 6a is formed from the end of the shaft 6 to the position of the radial flow path 2a in the axial direction. Thus, a flow path is formed in which air flows from the opposite side of the shaft 6 to the air gap 8. In addition, the radial flow path 2a is formed at the axial center of the rotor core 2, thereby generating air flow toward both ends of the air gap 8 with the shortest flow path, thereby suppressing the intrusion of cooling oil into the air gap 8.

[0018] A plurality of flow path holes 12 are formed inside the housing 4 and are connected to the air flow path 4a and are formed on the radially outer side of the housing 4. Among the plurality of flow path holes 12, a first flow path hole 12a is formed on a side close to a gear provided outside the rotating electrical machine 1, and a second flow path hole 12b is formed on a side farther from the gear than the first flow path hole 12a. The first flow path hole 12a and the second flow path hole 12b have different sizes. In the attached drawings, the second flow path hole 12b is formed larger than the first flow path hole 12a. In this way, the pressure loss is managed by adjusting the size of the hole so that the amount of air passing through the air gap 8 is consistent on the gear side and the opposite side of the gear, and taking into account the length of each air flow path 4a.

[0019] ( Figure 2 ) The air flow 10 is generated by the pressure difference caused by the rotation of the pump 7. As shown in the figure, the air circulating in the housing 4 first flows into the air flow path 4a formed in the upper part of the housing 4 from the flow path holes 12a and 12b, and flows into the axial flow path 6a through the air flow path 4a connected to the opposite side of the gear. The air 10 flowing into the axial flow path 6a flows into the air gap 8 between the rotor and the stator 3 through the radial flow path 2a. By having such a circulation of the air 10, it is possible to suppress the cooling oil from entering the air gap 8, and it is possible to eliminate the problem of residual cooling oil in the air flow path 4a and the air gap 8 in the prior art.

[0020] In addition, although not shown in the figure, in order to return the cooling oil flowing into the air flow path 4a to the housing 4 at a stage earlier than the axial flow path 6a, the housing 4 may also form a cooling oil flow path. Thereby, the reduction of the air flow rate caused by the cooling oil remaining in the air flow path 4a is suppressed. In addition, the inlet of the air flow path 4a may also be formed on the side of the shaft 6 or on the rotor core 2. In the case where the inlet of the air flow path 4a is set on the side of the shaft 6, the structure of the housing 4 can be simplified compared to the case where it is set at the end of the shaft 6, thereby reducing the cost and size of the rotating electrical machine 1. In addition, in the case where the inlet of the air flow path 4a is set on the rotor core 2, the residual cooling oil for cooling the rotor core 2 can be reduced.

[0021] ( Figure 3 ) The shaft 6 has a shaft oil passage 9 on the gear side. The shaft oil passage 9 is connected to the oil passage of the rotor core 2. That is, the shaft oil passage 9 for flowing the cooling oil supplied from the gear side and the shaft flow passage 6a connected to the air flow passage 4a coexist in the same shaft 6. After the cooling oil flows out of the rotor core 2 through the shaft oil passage 9 and the rotor core 2, it flows toward the oil pan 4b formed at the bottom of the housing 4 due to gravity. Since the oil pan 4b is also part of the air flow passage 4a, the cooling oil is discharged by squeezing of the air circulation and discharged to the outside of the housing 4. In this way, the rotating electric machine 1 is oil-cooled from the gear side to the opposite side of the gear. As a result, the large heat loss in the part of the rotating electric machine 1 where the magnetic field rotates can be reduced.

[0022] (First Modification) ( Figure 4 ) The air flow path 4a, for example, will form the slot 13 when the stator core 3 is manufactured by welding, and thus may be formed by a slot 13 such as a positioning slot or a welding slot of the stator core 3. Thus, the air flow path 4a provided on the housing 4 can be formed with fewer parts, thereby reducing the cost and size of the rotating electrical machine 1.

[0023] ( Figure 5 ) The structure of the pump 7 is described. The pump 7 is formed by sandwiching an impeller-shaped steel plate 7b having a plurality of oil passage holes 7c between two circular steel plates 7a having a plurality of oil passage holes 7c. In this way, the pump 7 is formed into an impeller shape by stacking three types of electromagnetic steel plates, so that iron loss does not occur and it can be manufactured at a low cost. In addition, as long as the pump 7 is a pump that rotates integrally with the shaft 6 for the purpose of miniaturization, as described later, Figure 6 As shown, it can be arranged on the radially outer side of the rotor core 2. When the pump 7 is arranged outside the magnetic circuit, since there is no iron loss, it can be made by stamping. In addition, only one pump 7 can play a centrifugal role relative to a rotating motor 1, but a structure in which multiple pumps 7 are arranged is also possible.

[0024] (Second and third variants) ( Figure 6 ) As mentioned above, the pump 7 may also be mounted at a position that does not affect the magnetic circuit, for example Figure 6 As shown in (a), a pump 7 may be provided at the end of the shaft 6 on the opposite side of the gear to introduce air from the air flow path 4a to the axial flow path 6a. In addition, although not shown, a pump 7 may be provided to replace the end plate provided on the rotor core 2 to introduce circulating air from the side of the rotor core 2.

[0025] In addition, as a measure when the rotation of the rotating electrical machine 1 is reverse rotation, Figure 6As shown in (b), pumps 7 with different discharge directions are respectively provided on the rotating shaft. In this case, in order to prevent the air from circulating between the two pumps 7, a check valve can be provided between the two pumps 7 on the air flow path 4a. In this way, by providing pumps 7 that rotate in opposite directions to each other, even when the vehicle is reversed at the fastest speed, it is possible to cope with the change of the air flow 10 in the rotating motor 1, and it is also possible to reduce the stirring loss from the low speed area to the high speed area.

[0026] (Fourth Modification) ( Figure 7 ) The stator core 3 has a stator cooling flow path 14. This is because, when the pump 7 is provided on the rotor, the magnetic path portion of the stator 3 corresponding to the pump 7 and the radial flow path 2a of the rotor core 2 is wasted, so the magnetic path portion is reduced corresponding to the position of the pump 7, and the stator cooling flow path 14 is provided as a second air flow path instead. Thus, by flowing the air 10 relative to the stator core 3 and the coil inserted in the stator core 3, the stator can be cooled.

[0027] In addition, the stator core 3 forms the stator cooling flow path 14 by, for example, stacking steel plates having different hole shapes while shifting each other and stacking them so that the air 10 passes therethrough while maintaining the inserted coil or its shape.

[0028] According to one embodiment of the present invention described above, the following effects are achieved.

[0029] (1) A rotating electric machine 1 includes: a rotor having a rotor core 2 formed by stacking a plurality of electromagnetic steel sheets and a shaft 6 supporting the rotor core 2; a stator facing the rotor with a predetermined space, i.e., an air gap 8, interposed therebetween in the radial direction outside the rotor; and a housing 4 housing the rotor and the stator. The housing 4 forms an air flow path 4a between the rotor and the stator, and the shaft 6 has an axial flow path 6a communicating with the air flow path 4a. The rotor includes: a pump 7 connected to the shaft 6 and synchronous with the rotation of the shaft 6, and a radial flow path 2a communicating with the axial flow path 6a and the air gap 8. Thus, a rotating electric machine can be provided that suppresses the stirring loss of cooling oil generated in the air gap.

[0030] (2) The pump 7 is disposed so as to be sandwiched between the plurality of electromagnetic steel sheets. This generates a pressure difference between the air gap 8 and other portions thereof, thereby reducing stirring loss.

[0031] (3) The axial flow passage 6a is formed from the end of the shaft 6 to the position of the radial flow passage 2a in the axial direction. Thus, the stirring loss of the cooling oil can be reduced by sending the air 10 to the air gap 8 via the rotor.

[0032] (4) The radial flow path 2a is formed at the axial center of the rotor core 2. This allows the air flow to be generated toward both ends of the air gap 8 with the smallest flow path, thereby suppressing the intrusion of the cooling oil into the air gap 8.

[0033] (5) The housing 4 has a cooling oil flow path for returning the cooling oil flowing into the air flow path 4a to the housing 4. This can suppress a decrease in the air flow rate due to the cooling oil remaining in the air flow path 4a.

[0034] (6) Among the plurality of flow holes 12 that communicate with the air flow path 4a and are formed on the radially outer side of the housing 4, the first flow hole 12a formed on the side close to the gear provided outside the rotary electric machine 1 has a size different from that of the second flow hole 12b formed on the side farther from the gear than the first flow hole 12a. Thus, the pressure loss can be managed in consideration of the length of the air flow path 4a from each of the flow holes 12a and 12b to the axial flow path 6a.

[0035] (7) The air flow path 4a is formed by the positioning groove or welding groove of the stator. Thus, the air flow path 4a provided in the housing 4 can be configured with a small number of parts, and the cost and size of the rotating electrical machine 1 can be reduced.

[0036] (8) The pump 7 is formed by laminating electromagnetic steel sheets or by mixing resin and a powder magnetic core. This can avoid losses caused by the magnetic field of the stator when the pump 7 is made of a simple metal block.

[0037] (9) The inlet of the air flow path 4a is formed on the side surface of the shaft 6 or the rotor core 2. This allows the air flow toward both ends of the air gap 8 to be generated with the smallest flow path, thereby suppressing the intrusion of the cooling oil into the air gap 8.

[0038] (10) The stator has the second radial flow path 14 formed corresponding to the positions of the pump 7 and the radial flow path 2a. By flowing the air 10 relative to the stator core 3 and the coil inserted in the stator core 3, the stator can be cooled.

[0039] In addition, the present invention is not limited to the above-mentioned embodiments, and various modifications or other structures can be combined within the scope of the gist thereof. In addition, the present invention is not limited to a structure having all the structures described in the above-mentioned embodiments, and also includes a structure in which a part of the structure is deleted. Explanation of symbols

[0040] 1 Rotating motor 2 Rotor core 2a Radial flow path 3. Stator core 4 Housing 4a Air flow path 4b Oil pan 5 Coil end 6 Axis 6a Axial flow path 7 Pumps 7a Round steel plate 7b Impeller-shaped steel plate 7c Oil channel hole 8 Air Gap 9-axis oil circuit 10 Air (flow) 11 Cooling oil (flow) 12a, 12b flow holes 13 slots 14. Stator cooling flow path (second radial flow path).

Claims

1. A rotating electrical machine comprising: a rotor having a rotor core formed by laminating a plurality of electromagnetic steel sheets and a shaft supporting the rotor core; a stator which is located radially outside the rotor and faces the rotor with a predetermined space, i.e., an air gap, therebetween; and a housing that accommodates the rotor and the stator, The rotating electrical machine is characterized in that The housing forms an air flow path between the rotor and the stator. The shaft has an axial flow path communicating with the air flow path, The rotor includes a pump connected to the shaft and synchronized with the rotation of the shaft, and a radial flow path connecting the axial flow path and the air gap.

2. The rotating electrical machine according to claim 1, characterized in that: The pump is disposed so as to be sandwiched between the plurality of electromagnetic steel plates.

3. The rotating electrical machine according to claim 1, characterized in that: The axial flow path is formed from the end of the shaft to the position of the radial flow path in the axial direction.

4. The rotating electrical machine according to claim 1, characterized in that: The radial flow path is formed at a central position in the axial direction of the rotor core.

5. The rotating electrical machine according to claim 1, characterized in that: The housing has a cooling oil flow path for returning cooling oil flowing into the air flow path to the inside of the housing.

6. The rotating electrical machine according to claim 1, characterized in that: Among the multiple flow path holes connected to the air flow path and formed on the radially outer side of the housing, the size of the first flow path hole formed on the side close to the gear arranged outside the rotating motor is different from the size of the second flow path hole formed on the side farther from the gear than the first flow path hole.

7. The rotating electrical machine according to claim 1, characterized in that The air flow path is formed by a positioning groove or a welding groove of the stator.

8. The rotating electrical machine according to claim 1, characterized in that The pump is formed by laminating the electromagnetic steel sheets, or by mixing a resin and a powder magnetic core.

9. The rotating electrical machine according to claim 1, characterized in that An inlet of the air flow path is formed on a side surface of the shaft or on the rotor core.

10. The rotating electrical machine according to claim 1, characterized in that The stator has a second radial flow path formed corresponding to the positions of the pump and the radial flow path.

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