Rotating electric machine

Abstract

Provided is a rotary electrical machine comprising: a rotor which has a rotor core that is configured by stacking a plurality of electromagnetic steel sheets and a shaft that supports the rotor core; a stator which, on the radially outward side of the rotor, is opposite from the rotor with an air gap therebetween, said air gap being a prescribed space; and a housing which houses the rotor and the stator. The housing forms an air flow path between the rotor and the stator. The shaft has a shaft flow path that is in communication with the air flow path. The rotor has a pump which is connected to the shaft and which is synchronized with rotation of the shaft, and a radial flow path which is in communication with the shaft flow path and the air gap.

Description

Technical Field

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

Background Art

[0002] In the manufacture of rotating electric machines, as one of the means for realizing higher output density and utilization of low-grade magnets, a direct oil cooling structure, which is one of the technologies for cooling rotating electric machines, is adopted. In the direct oil cooling structure, cooling oil is discharged into the motor housing. However, when this is done, the cooling oil enters the air gap between the rotor and the stator, causing stirring loss and a decrease in motor efficiency. Therefore, there is a need to develop a rotating electric machine that suppresses the intrusion of cooling oil into the air gap and achieves both high cooling performance and high efficiency.

[0003] The rotating electric machine described in Patent Document 1 is provided with fans 16 and 17 on the outer peripheries of end plates 2B and 2C on both sides of the rotor 2. One fan 16 sends air from the space 12A into the gap G, and the other fan 17 discharges air from the gap G to the space 12B on the side of the rotor 2, so that a differential pressure is generated by the pump effect generated in the holes provided in the rotor when the motor rotates.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The technology described in Patent Document 1 reduces agitation losses by suppressing the intrusion of cooling oil into the gap. However, in a simple straight flow path, generating the pressure necessary to suppress cooling oil intrusion requires high-speed motor rotation, as the reduction in agitation losses cannot be expected at low to medium motor speeds. Therefore, when the motor rotates at high speeds, the flow rate of cooling oil increases, leading to the problem of increased pump losses.

[0006] In view of this, the present invention aims to provide a rotating electric machine that suppresses the occurrence of cooling oil agitation losses in the air gap from the low-speed range to the high-speed range of the motor rotation speed. [Means for solving the problem]

[0007] A rotating electric machine comprising: a rotor having a rotor core formed by laminating multiple electromagnetic steel sheets and a shaft supporting the rotor core; a stator facing the rotor radially outward from the rotor via a predetermined space, which is an air gap; and a housing that houses the rotor and the stator, wherein the housing forms an air passage between the rotor and the stator, the shaft has a shaft passage communicating with the air passage, and the rotor has a pump connected to the shaft and synchronized with the rotation of the shaft, and a radial passage communicating the shaft passage and the air gap. Furthermore, among the multiple flow path holes that communicate with the air passage and are formed on the radially outer side of the housing, the first flow path hole formed on the side closer to the gear provided on the outside of the rotating electric machine and the second flow path hole formed on the side further away from the gear than the first flow path hole are of different sizes. . [Effects of the Invention]

[0008] This invention provides a rotating electric machine that suppresses the agitation loss of the cooling oil in the air gap. [Brief explanation of the drawing]

[0009] [Figure 1] Configuration diagram of a rotating electric machine according to one embodiment of the present invention. [Figure 2] Diagram illustrating the airflow path within the housing in one embodiment of the present invention. [Figure 3] Diagram illustrating the oil passages within the housing. [Figure 4] First variation [Figure 5] Configuration diagram of a pump according to one embodiment of the present invention. [Figure 6] Second and third variations [Figure 7] Fourth variation

[0010] Embodiments of the present invention will be described below with reference to the drawings. The following description and drawings are illustrative for illustrating the present invention, and have been omitted and simplified as appropriate for clarity of explanation. The present invention can also be carried out in various other forms. Unless otherwise specified, each component may be singular or plural.

[0011] The positions, sizes, shapes, and ranges of the components shown in the drawings may not represent their actual positions, sizes, shapes, and ranges in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the positions, sizes, shapes, and ranges disclosed in the drawings.

[0012] (One embodiment of the present invention and its overall configuration) (Figure 1) The rotating electric machine 1 comprises a rotor having a rotor core 2 formed by laminating multiple electromagnetic steel sheets and a shaft 6 supporting the rotor core 2; a stator 3 (stator core 3) facing the rotor radially outward from the rotor core 2 via a predetermined space, which is an air gap 8; and a housing 4 that houses the rotor and the stator 3. Although not shown, a gear connected to the shaft 6 is provided on the outside of the rotating electric machine 1. In the following explanation, the gear side will be referred to as the left side of the drawing and the non-gear side as the right side of the drawing.

[0013] The housing 4 has an air passage 4a between the rotor and the stator 3. The air passage 4a is formed to communicate from the top of the housing 4 to the side opposite the gear. The shaft 6 has a shaft passage 6a that communicates with this air passage 4a, and is configured to draw in air 10 from the side opposite the gear of the shaft 6. The rotor also has a pump 7 connected to the shaft 6 and synchronized with the rotation of the shaft, and a radial passage 2a that connects the shaft passage 6a and the air gap 8. In Figure 1, an example is shown in which the pump 7 is sandwiched between multiple electrical steel sheets.

[0014] The pump 7, connected to the shaft 6, rotates with the motor, generating centrifugal force. This creates a differential pressure between the air gap 8 and the rest of the housing 4, providing the pressure necessary to suppress the ingress of cooling oil into the air gap 8, thereby reducing stirring losses. Furthermore, by arranging the pump 7 in this way, it becomes possible to suppress the ingress of cooling oil into the air gap 8 over a wide speed range, including both high and low speeds, while also reducing pump losses at high speeds.

[0015] As air circulates within the air passage 4a, an airflow is generated that flows from the air gap 8 into the housing 4 via the connecting shaft passage 6a and radial passage 2a. In this way, the cooling oil that has entered the air passage 4a, shaft passage 6a, and radial passage 2a is agitated, suppressing the intrusion of cooling oil into the air gap 8. While it is true that agitation losses increase as the motor speed of the rotating electric machine 1 increases, the agitation losses are reduced as a result of the increased airflow, thus improving the cooling efficiency and motor efficiency of the rotating electric machine 1.

[0016] Regarding the position of the pump 7, when it is provided on the rotor, it may be arranged at any position within the range of the length of the air gap 8. Also, the pump 7 may be formed by laminating electromagnetic steel sheets or by mixing resin and dust core. By forming the pump 7 by mixing resin and dust core, the occurrence of loss due to the field magnet of the stator when made of a simple lump of metal is avoided.

[0017] The radial flow path 2a is formed at the axial center of the rotor core 2. The shaft flow path 6a is formed in the axial direction from the end of the shaft 6 to the position of the radial flow path 2a. Thus, it forms a flow path through which air flows in communication from the non-gear side of the shaft 6 to the air gap 8. Also, by forming the radial flow path 2a at the axial center position of the rotor core 2, the flow of air toward both ends of the air gap 8 is generated with a minimum flow path, and the intrusion of cooling oil into the air gap 8 can be suppressed.

[0018] Inside the housing 4, a plurality of flow path holes 12 are formed that communicate with the air flow path 4a and are formed on the radially outer side in the housing 4. Among these plurality of flow path holes 12, a first flow path hole 12a formed on the side closer to the gear provided outside the rotating electrical machine 1 and a second flow path hole 12b formed on the side farther from the gear than the first flow path hole 12a are defined. The first flow path hole 12a and the second flow path hole 12b have different sizes. In the drawing, the second flow path hole 12b is formed larger than the first flow path hole 12a. In this way, by adjusting the size of the holes so that the amount of air passing through the air gap 8 is the same on the gear side and the non-gear side and considering the length of each air flow path 4a, the pressure loss is managed.

[0019] (Figure 2) The air flow 10 is generated by the differential pressure created by the rotation of the aforementioned pump 7. As shown in the figure, the air circulating inside the housing 4 first flows into the air flow path 4a formed at the upper part of the housing 4 from the flow path holes 12a and 12b, and then flows into the shaft flow path 6a via the air flow path 4a communicating with the counter gear side. The air 10 that has flowed into the shaft flow path 6a flows into the air gap 8 between the rotor and the stator 3 via the radial flow path 2a. Due to such circulation of the air 10, the intrusion of the cooling oil into the air gap 8 can be suppressed, and the conventional problem of the cooling oil remaining in the air flow path 4a and the air gap 8 can be solved.

[0020] Although not shown in the figure, the housing 4 may form a cooling oil flow path in order to return the cooling oil that has flowed into the air flow path 4a back into the housing 4 at a stage prior to the shaft flow path 6a. Thereby, the decrease in the air flow rate due to the remaining cooling oil in the air flow path 4a can be suppressed. Also, the inlet of the air flow path 4a may be formed on the side surface of the shaft 6 or on the rotor core 2. When the inlet of the air flow path 4a is provided on the side surface of the shaft 6, compared with the case where it is provided at the end of the shaft 6, the structure of the housing 4 can be simplified, and the cost and size of the rotating electric machine 1 can be reduced. Also, when the inlet of the air flow path 4a is provided on the rotor core 2, the remaining of the 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 communicates with the oil passage in the rotor core 2. In other words, the shaft oil passage 9, which carries the cooling oil supplied from the gear side, and the shaft passage 6a, which communicates with the air passage 4a, are both located within the same shaft 6. The cooling oil that passes through the shaft oil passage 9 and the rotor core 2 flows, following gravity, towards the oil pan 4b formed at the bottom of the housing 4 after leaving the rotor core 2. Since the oil pan 4b is also part of the air passage 4a, the cooling oil is discharged to the outside of the housing 4 by being pushed out by the circulation of air. In this way, the rotating electric machine 1 is oil-cooled from the gear side to the opposite side. This reduces the large heat loss in the part of the rotating electric machine 1 where the magnetic field is rotating.

[0022] (First variation) (Figure 4) The air passage 4a may be formed by grooves 13 such as positioning grooves or welding grooves in the stator core 3, since grooves 13 will inevitably be formed as long as the stator core 3 is created by welding. This allows the air passage 4a provided in the housing 4 to be constructed with fewer parts, thereby reducing the cost and size of the rotating electric machine 1.

[0023] (Figure 5) The configuration of the pump 7 will now be described. The pump 7 is formed by sandwiching an impeller-shaped steel plate 7b having multiple oil passage holes 7c between two circular steel plates 7a, each having multiple oil passage holes 7c. In this way, the pump 7 can be manufactured inexpensively and without iron loss by laminating three types of electromagnetic steel plates to form an impeller shape. If the pump 7 is to rotate integrally with the shaft 6 for the purpose of miniaturization, it may be installed on the radially outer side of the rotor core 2, as shown in Figure 6 below. If the pump 7 is installed outside the magnetic circuit, there is no risk of iron loss, and it can be manufactured by pressing. Although one pump 7 is sufficient to perform the role of centrifugal force for a single rotating electric machine 1, a configuration with multiple pumps 7 is also possible.

[0024] (Second and third variations) (Figure 6) As mentioned above, the pump 7 may be mounted in a position that does not affect the magnetic circuit. For example, as shown in Figure 6(a), the pump 7 may be installed at the end of the shaft 6 on the side opposite the gear, and air may be introduced from the air passage 4a to the shaft passage 6a. Although not shown, the pump 7 may also be installed in place of the end plate on the rotor core 2, and circulating air may be introduced from the side of the rotor core 2.

[0025] Furthermore, to address the situation when the rotating electric machine 1 rotates in the opposite direction, two pumps 7 with different discharge directions are provided on the rotating shaft, as shown in Figure 6(b). In this case, a backflow prevention valve may be provided in the air passage 4a at a position between the two pumps 7 to prevent air from circulating between them. By providing pumps 7 that rotate in opposite directions in this way, it is possible to respond to changes in the airflow 10 inside the rotating electric machine 1 even at the maximum speed when the car is driving in reverse, and similarly, stirring losses can be reduced from low speeds to high speeds.

[0026] (Fourth variation) (Figure 7) The stator core 3 has a stator cooling passage 14. This is because, when the pump 7 is installed on the rotor, the magnetic circuit portion of the stator 3 corresponding to the radial passage 2a of the pump 7 and rotor core 2 becomes wasted. Therefore, the magnetic circuit portion corresponding to the position of the pump 7 is reduced, and instead, the stator cooling passage 14 is provided as a second air passage. This allows the stator to be cooled by flowing air 10 over the stator core 3 and the coils inserted in the stator core 3.

[0027] Furthermore, the stator core 3 forms a stator cooling channel 14 by overlapping laminated steel plates with different hole shapes, for example, while offsetting them, so that air 10 can pass through while maintaining the inserted coils and their shape.

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

[0029] (1) The rotating electric machine 1 comprises 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 facing the rotor radially outward from the rotor via a predetermined space, which is an air gap 8; and a housing 4 that houses the rotor and the stator. The housing 4 forms an air passage 4a between the rotor and the stator, and the shaft 6 has a shaft passage 6a that communicates with the air passage 4a. The rotor has a pump 7 connected to the shaft 6 and synchronized with the rotation of the shaft 6, and a radial passage 2a that connects the shaft passage 6a and the air gap 8. In this way, a rotating electric machine can be provided that suppresses the agitation loss of the cooling oil in the air gap.

[0030] (2) The pump 7 is positioned between multiple electrical steel sheets. This arrangement creates a pressure difference between the air gap 8 and the rest of the sheet, thereby reducing stirring losses.

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

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

[0033] (5) The housing 4 has a coolant passage for returning the coolant that has flowed into the air passage 4a back into the housing 4. This suppresses the reduction in airflow rate due to the coolant remaining in the air passage 4a.

[0034] (6) Of the multiple flow path holes 12 that communicate with the air passage 4a and are formed on the radially outer side of the housing 4, the first flow path hole 12a, which is formed on the side closer to the gear provided on the outside of the rotating electric machine 1, and the second flow path hole 12b, which is formed on the side further from the gear than the first flow path hole 12a, are of different sizes. This allows for pressure loss to be managed by taking into account the length of the air passage 4a from each of the flow path holes 12a and 12b to the shaft passage 6a.

[0035] (7) The air passage 4a is formed by a positioning groove or weld groove in the stator. In this way, the air passage 4a provided in the housing 4 can be constructed with fewer parts, thereby reducing the cost and size of the rotating electric machine 1.

[0036] (8) The pump 7 is formed by laminating electromagnetic steel sheets or by mixing resin and compacted magnetic core. This avoids the loss caused by the stator field that would occur if it were made from a simple block of metal.

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

[0038] (10) The stator has a second radial channel 14 formed in correspondence with the positions of the pump 7 and the radial channel 2a. The stator can be cooled by flowing air 10 over the stator core 3 and the coil inserted into the stator core 3.

[0039] It should be noted that the present invention is not limited to the embodiments described above, and various modifications and combinations of other configurations can be made without departing from the spirit of the invention. Furthermore, the present invention is not limited to having all the configurations described in the embodiments described above, and may also include configurations in which some of those configurations are omitted. [Explanation of Symbols]

[0040] 1. Rotating electric machine 2 rotor cores 2a Radial flow path 3 Stator core 4 Housing 4a Airflow channel 4b Oil pan 5 coil ends 6 shafts 6a Shaft flow path 7 Pumps 7a Circular steel plate 7b Impeller-shaped steel plate 7c Oil passage hole 8 Air gap 9 Shaft oil passage 10 Air (flow) 11 Coolant (flow) 12a, 12b flow path holes 13 Groove 14. Stator cooling channel (second radial channel)

Claims

1. A rotor having a rotor core formed by laminating multiple electromagnetic steel sheets, and a shaft that supports the rotor core, A stator is located radially outward from the rotor, with a predetermined space, which is an air gap, between it and the rotor. A rotating electric machine comprising a housing for housing the rotor and the stator, The housing forms an air passage between the rotor and the stator. The shaft has a shaft passage that communicates with the air passage, The rotor has a pump connected to the shaft and synchronized with the rotation of the shaft, and a radial passage that connects the shaft passage and the air gap. Of the multiple flow path holes that communicate with the aforementioned air passage and are formed on the radially outer side of the housing, the first flow path hole formed on the side closer to the gear provided on the outside of the rotating electric machine and the second flow path hole formed on the side further away from the gear than the first flow path hole are of different sizes. Rotating electric machine.

2. A rotating electric machine according to claim 1, The pump is positioned sandwiched between a plurality of the electromagnetic steel sheets. Rotating electric machine.

3. A rotating electric machine according to claim 1, The shaft flow path is formed in the axial direction from the end of the shaft to the position of the radial flow path. Rotating electric machine.

4. A rotating electric machine according to claim 1, The radial flow channel is formed at the axial center of the rotor core. Rotating electric machine.

5. A rotating electric machine according to claim 1, The housing has a cooling oil passage for returning the cooling oil that has flowed into the air passage back into the housing. Rotating electric machine.

6. A rotating electric machine according to claim 1, The air passage is formed by a positioning groove or weld groove in the stator. Rotating electric machine.

7. A rotating electric machine according to claim 1, The pump is formed by laminating the electromagnetic steel sheets or by mixing resin and compacted magnetic core. Rotating electric machine.

8. A rotating electric machine according to claim 1, The inlet of the air passage is formed on the side of the shaft or on the rotor core. Rotating electric machine.

9. A rotating electric machine according to claim 1, The stator has a second radial channel formed in correspondence with the positions of the pump and the radial channel. Rotating electric machine.

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