Rotary electric machine and vehicle drive device

Abstract

A rotary electric machine (1) comprises: a regulation member (8) that is disposed between a stator coil end part (17e) and a rotor coil end part (13e) in the radial direction (R) and regulates the flow of oil in the radial direction (R) between the stator coil end part (17e) and the rotor coil end part (13e); a first oil supply part (81) that supplies oil to the stator coil end part (17e) from the outer side in the radial direction (R2) as compared to the regulation member (8); and a second oil supply part (82) that supplies oil to the rotor coil end part (13e) from the outer side in the axial direction (L) as compared to the rotor coil end part (13e).

Description

Rotating electric machine and vehicle drive device

[0001] The present invention relates to a rotating electric machine and a vehicle drive device.

[0002] International Publication No. WO 2023 / 074705 discloses an electrically excited synchronous motor (EESM) that serves as a driving force source for wheels. Hereinafter, in the Background Art, reference numerals in parentheses refer to the referenced document. In an EESM, both the stator and the rotor have coils through which current flows. Because both the stator coil and the rotor coil generate heat when current flows through them, cooling means are often provided. This publication describes supplying oil to rotor coil end portions (3161, 3162), which are the axial (X) ends of the rotor coil (316), and stator coil end portions (3221, 3222), which are the axial (X) ends of the stator coil (322) (see Figures 8 to 10, etc. in this publication).

[0003] Specifically, the rotor coil end portions (3161, 3162) are supplied with oil guided radially outward from the hollow interior (3145) of the rotor shaft (314) radially inward of the rotor coil end portions (3161, 3162) by centrifugal force accompanying the rotation of the rotor (310), and oil ejected axially from an oil passage formed in the case. The stator coil end portions (3221, 3222) are supplied with oil that has cooled the rotor coil end portions (3161, 3162) and oil that is further guided radially outward by centrifugal force.

[0004] International Publication No. 2023 / 074705

[0005] When oil is supplied as described above, the oil supplied to the stator coil end portion has a reduced heat capacity that can be absorbed by the stator coil end portion due to heat exchange with the rotor coil end portion. This may result in a decrease in the cooling capacity for the stator coil. For example, as rotating electrical machines become smaller and the amount of oil used for cooling decreases, the heat capacity of the oil also decreases, making the cooling capacity more likely to decrease.

[0006] In view of the above background, it is desirable to provide a technique that can appropriately cool both the rotor and stator coils of a wound-field type rotating electric machine.

[0007] In view of the above, a rotating electric machine is provided which comprises a stator having a stator coil, a rotor having a rotor coil, and a case that houses the stator and the rotor, wherein the direction along the rotation axis of the rotor is defined as the axial direction and the direction perpendicular to the axial direction is defined as the radial direction, and the rotor is disposed radially inside the stator, wherein the axial end of the stator coil is defined as a stator coil end portion, the axial end of the rotor coil is defined as a rotor coil end portion, and a regulating member that regulates the flow of oil in the radial direction between the stator coil end portion and the rotor coil end portion is disposed radially between the stator coil end portion and the rotor coil end portion, and the rotating electric machine is provided with a first oil supply unit that supplies oil to the stator coil end portion from the radial outside of the regulating member, and a second oil supply unit that supplies oil to the rotor coil end portion from the axial outside of the rotor coil end portion.

[0008] According to this configuration, cooling oil can be supplied separately to the coil end portions of both the rotor and the stator of a wound-field rotating electric machine. Furthermore, according to this configuration, a restricting member is disposed radially between the stator coil end portion and the rotor coil end portion, thereby restricting oil that has cooled the stator coil end portion and become hot from flowing toward the rotor coil end portion, and restricting oil that has cooled the rotor coil end portion and become hot from flowing toward the stator coil end portion. Therefore, according to this configuration, the stator coil end portion and the rotor coil end portion can be effectively cooled separately, making it easier to improve the cooling performance of the stator coil and the rotor coil. In other words, according to this configuration, a technology can be provided that can appropriately cool both the rotor and the stator coils of a wound-field rotating electric machine.

[0009] Further features and advantages of the rotating electrical machine will become apparent from the following description of exemplary, non-limiting embodiments which are given with reference to the drawings.

[0010] Schematic exploded perspective view of a vehicle drive device Skeleton diagram of a vehicle drive device Side view (front view) of a vehicle drive device from a first side in the front-rear direction

[0011] Hereinafter, embodiments of a rotating electric machine and a vehicle drive device including the rotating electric machine will be described with reference to the drawings. Fig. 1 is a schematic exploded perspective view of a vehicle drive device 10. Note that some components, such as a portion of a cover member that configures a case 9, are omitted from this exploded perspective view. Fig. 2 is a skeleton diagram of the vehicle drive device 10.

[0012] In the following description, the term "driving connection" refers to a state in which two rotating elements are connected so as to be able to transmit a driving force, and includes a state in which the two rotating elements are connected so as to rotate integrally, or a state in which the two rotating elements are connected so as to be able to transmit a driving force via one or more transmission members. Such transmission members include various members that transmit rotation at the same speed or at a variable speed, such as shafts, gear mechanisms, belts, and chains. Note that transmission members may also include engagement devices that selectively transmit rotation and driving force, such as friction engagement devices and meshing engagement devices. However, when the term "driving connection" is used to refer to each rotating element of a planetary gear mechanism, it refers to a state in which multiple rotating elements in the planetary gear mechanism are connected to each other without passing through other rotating elements.

[0013] As shown in FIGS. 1 and 2 , a vehicle drive device 10 includes a rotating electric machine 1, an input member 2, a counter gear mechanism 3, a differential gear mechanism 4, and a case 9. The case 9 houses the rotating electric machine 1, the input member 2, the counter gear mechanism 3, and the differential gear mechanism 4. The input member 2 is connected to the rotor 11 of the rotating electric machine 1 so as to rotate integrally with the rotor 11. In this embodiment, the input member 2 is spline-coupled to a rotor shaft 20 connected to the rotor 11, and rotates integrally with the rotor 11 and the rotor shaft 20. Note that the rotor shaft 20 and the input member 2 may be the same member. The differential gear mechanism 4 distributes the driving force transmitted from the rotating electric machine 1 to a pair of output members drivingly connected to a pair of wheels W. As will be described in detail later, in this embodiment, a pair of differential side gears 45 of the differential gear mechanism 4 correspond to the output members.

[0014] The vehicle drive system 10 includes a speed reduction mechanism that reduces the rotation of the input member 2 and transmits the reduced rotation to a differential case 42 of the differential gear mechanism 4. As shown in FIG. 2 , in this embodiment, the speed reduction mechanism includes an input gear 21, a counter gear mechanism 3, and a differential input gear 41. The input gear 21 is connected to the input member 2 so as to rotate integrally with the input member 2. The input gear 21 may be formed integrally with the input member 2, which is a shaft member, using the same member, or may be formed using a member separate from the input member 2 and integrated with the input member 2 by welding or the like. Similarly, a first counter gear 31 and a second counter gear 32, which will be described later, may be formed using the same member as the shaft member (counter shaft 30) or may be separate members, and the differential input gear 41 may be formed using the same member as the differential case 42 or may be separate members.

[0015] The counter gear mechanism 3 includes a first counter gear 31 and a second counter gear 32. The first counter gear 31 and the second counter gear 32 are both connected to the counter shaft 30 so as to rotate integrally. The first counter gear 31 meshes with the input gear 21, and the second counter gear 32 meshes with a differential input gear 41. The differential input gear 41 is connected to the differential case 42 so as to rotate integrally therewith.

[0016] As shown in FIG. 2 , the rotating electric machine 1 (rotor 11) and the input member 2 are disposed on a first axis A1. The counter gear mechanism 3 is disposed on a second axis A2, which is a separate axis parallel to the first axis A1. The differential gear mechanism 4, including the output member, is disposed on a third axis A3, which is a separate axis parallel to the first axis A1 and the second axis A2. In this embodiment, as shown in FIG. 1 , the first axis A1 is disposed on a side V1 above the second axis A2 and the third axis A3. Note that, although the present embodiment illustrates a configuration in which the second axis A2 is disposed on the side V1 above the third axis A3, the second axis A2 and the third axis A3 may be disposed at the same position in the vertical direction V, or the third axis A3 may be disposed on the side V1 above the second axis A2.

[0017] In the following description, a direction parallel to the first axis A1, the second axis A2, and the third axis A3 is referred to as the "axial direction L" of the vehicle drive device 10. One side of the axial direction L is referred to as the "axial first side L1," and the other side of the axial direction L is referred to as the "axial second side L2." The direction in which the rotating members revolve around their respective rotational axes is referred to as the "circumferential direction C" (see FIG. 1). The directions perpendicular to the first axis A1, the second axis A2, and the third axis A3 are referred to as the "radial direction R" based on each axis (see FIG. 1). The side closer to the axis in the radial direction R is referred to as the "radial inner side R1," and the side farther from the axis is referred to as the "radial outer side R2." Note that when it is not necessary to distinguish which axis is used as the reference or when it is clear which axis is used as the reference, the term "radial direction R" may be used simply.

[0018] Furthermore, in a state in which the vehicle drive device 10 is mounted on a vehicle, the direction along the vertical direction is referred to as the up-down direction V, and the upper side along the up-down direction V is referred to as the upper side V1, and the lower side along the up-down direction V is referred to as the lower side V2. In this embodiment, in a state in which the vehicle is mounted, the axial direction L is along the horizontal direction, and the axial direction L and the up-down direction V are orthogonal. In this state, the direction orthogonal to the axial direction L and the up-down direction V is referred to as the fore-aft direction X, and one side of the fore-aft direction X is referred to as the "first fore-aft side X1," and the other side of the fore-aft direction X is referred to as the "second fore-aft side X2."

[0019] In this embodiment, the rotating electric machine 1 is exemplified as an electrically excited synchronous motor (EESM) having a stator 15 with a plurality of phases (N phases, e.g., three phases, where N is an arbitrary natural number) of stator coils 17 arranged thereon, and a wound-field rotor 11. A wound-field synchronous rotating electric machine has a rotor structure with an electromagnet using a field winding (rotor coil 13) instead of a permanent magnet as a field source. The field magnetic flux generated by the electromagnet can be adjusted by a field current supplied to the rotor winding 13 from an excitation circuit (both of which are included in an electric circuit unit EU, described later) controlled by a control device via a wireless power supply 18 and a rectifier circuit 19 (see FIG. 2 ). The excitation circuit includes, for example, a DC-DC converter and adjusts a DC voltage supplied from a DC power source (not shown) so that a set field current flows through the rotor winding 13. The power generated by the excitation circuit is transmitted as AC via the non-contact power supply unit 18 , converted to DC by the rectifier circuit 19 , and supplied to the rotor coil 13 .

[0020] Wound-field synchronous rotating electric machines have the following advantages over permanent magnet synchronous motors (PMSMs): (1) variable field flux can be expected to improve efficiency in the medium-to-high speed, low torque operating range, and the constant output range can be expanded, and (2) they are not affected by supply instability of permanent magnets that use rare earths, etc. For these reasons, they have recently been increasingly used as a driving force source for the wheels of electric and hybrid vehicles.

[0021] As shown in Figure 2 and Figures 4 and 5 referenced below, the rotating electric machine 1 of this embodiment is an inner rotor type rotating electric machine in which the rotor 11 is disposed radially inward R1 with respect to the stator 15. Furthermore, the end of the stator coil 17 in the axial direction L is referred to as a stator coil end portion 17e, and the end of the rotor coil 13 in the axial direction L is referred to as a rotor coil end portion 13e. In this embodiment, the stator 15 is configured by winding the stator coil 17 around the stator core 16, and the portion protruding in the axial direction L from the stator core 16 corresponds to the stator coil end portion 17e. Similarly, in this embodiment, the rotor 11 is configured by winding the rotor coil 13 around the rotor core 12, and the portion protruding in the axial direction L from the rotor core 12 corresponds to the rotor coil end portion 13e. In this embodiment, as shown in Figure 2, an example is shown in which the rotating electric machine 1 has a stator coil end portion 17e and a rotor coil end portion 13e on both sides in the axial direction L, but it may also be a form in which the stator coil end portion 17e and the rotor coil end portion 13e are provided on only one side in the axial direction L.

[0022] 1 and 2 , the input member 2, input gear 21, counter gear mechanism 3, and differential gear mechanism 4 are disposed on the first axial side L1 with respect to the rotary electric machine 1. As described above, the input member 2, which rotates integrally with the input gear 21, is connected to the rotor shaft 20 so as to rotate integrally with the rotor shaft 20. The input member 2 is rotatably supported on the case 9 via input bearings B2. The input bearings B2 are disposed on both sides of the input gear 21 in the axial direction L. When distinguishing between the input bearings B2, the bearing disposed on the first axial side L1 with respect to the input gear 21 will be referred to as the first input bearing B21, and the bearing disposed on the second axial side L2 with respect to the input gear 21 will be referred to as the second input bearing B22.

[0023] The counter gear mechanism 3 is rotatably supported relative to the case 9 via a counter bearing B3. Specifically, the counter shaft 30, to which the first counter gear 31 and the second counter gear 32 are connected, is rotatably supported relative to the case 9 by counter bearings B3 arranged at two locations in the axial direction L. The first counter gear 31 is arranged on a first axial side L1 relative to the second counter gear 32. The counter shaft 30 is rotatably supported relative to the case 9 by a first counter bearing B31 arranged on the first axial side L1 relative to the first counter gear 31, and a second counter bearing B32 arranged on the second axial side L2 relative to the second counter gear 32.

[0024] The differential gear mechanism 4 is rotatably supported relative to the case 9 via a differential bearing B4. Specifically, the differential case 42 is rotatably supported relative to the case 9 by a first differential bearing B41 disposed on a first axial side L1 relative to the differential case 42 and a second differential bearing B42 disposed on a second axial side L2 relative to the differential case 42. In this embodiment, the differential input gear 41 that meshes with the second counter gear 32 has a larger diameter than the second counter gear 32. As a result, the rotational speed is further reduced compared to the counter shaft 30, and power is transmitted to the differential case 42 that rotates integrally with the differential input gear 41.

[0025] In this embodiment, a bevel gear type differential gear mechanism 4 is illustrated. The differential gear mechanism 4 includes a plurality of differential pinion gears 44 housed in a differential case 42 and a pair of differential side gears 45. The differential pinion gears 44 are rotatably supported by differential pinion shafts 43 that are fixed to the differential case 42 and rotate integrally with the differential case 42. A plurality of differential pinion shafts 43 are provided radially (e.g., in a cross shape) along a radial direction R based on the third axis A3, and a plurality of differential pinion gears 44 are also arranged at intervals in the radial direction R. The pair of differential side gears 45 mesh with the plurality of differential pinion gears. The differential side gears 45 are arranged to rotate about the third axis A3. Of the pair of differential side gears 45, the first differential side gear 45 is arranged on a first axial side L1 relative to the differential pinion shaft 43, and the second differential side gear 45 is arranged on a second axial side L2 relative to the differential pinion shaft 43.

[0026] In this embodiment, the first differential side gear 45 arranged on the first axial side L1 is connected to a first drive shaft DS, and the first drive shaft DS is connected to a first wheel W. The second differential side gear 45 arranged on the second axial side L2 is connected to a connecting shaft JS, which is connected to a second drive shaft DS, and the second drive shaft DS is connected to a second wheel W. Since the pair of drive shafts DS and connecting shaft JS rotate integrally with the respective differential side gears 45, the pair of drive shafts DS and connecting shaft JS can also be considered a pair of output members.

[0027] Although a bevel gear type differential gear mechanism 4 has been exemplified here, the differential gear mechanism 4 may also be a planetary gear mechanism. For example, if the differential gear mechanism 4 is a double pinion type planetary gear mechanism, a member that rotates integrally with the carrier and a member that rotates integrally with the sun gear correspond to the output member.

[0028] The case 9 has a first storage chamber E1 that houses the power transmission mechanism TA, such as the rotating electric machine 1, input member 2, input gear 21, counter gear mechanism 3, and differential gear mechanism 4, and a second storage chamber E2 that is partitioned from the first storage chamber E1 and houses an electric circuit unit EU that includes a control device that drives and controls the rotating electric machine 1, an inverter, an excitation circuit, a smoothing capacitor, etc.

[0029] The case 9 includes a case body 90, which is the core of the first and second storage chambers E1 and E2, a first cover 91, a second cover 92, and a third cover (not shown). The case body 90 includes a cylindrical portion having openings on both sides in the axial direction L, and a box-shaped portion having a side wall portion forming a rectangular opening extending from the peripheral wall of the cylindrical portion to one side in the front-rear direction X (here, the second front-rear direction side X2). The first cover 91 is a lid member that closes the opening on the first axial side L1 of the cylindrical portion of the case body 90 from the first axial side L1 (see FIG. 1). The second cover 92 is a lid member that closes the opening on the second axial side L2 of the cylindrical portion of the case body 90 from the second axial side L2 (see FIG. 3). The third cover is a lid member that closes the opening on the second front-rear direction side X2 of the box-shaped portion of the case body 90. A first storage chamber E1 is formed in a space surrounded by the inner wall of the cylindrical portion of the case body 90, the first cover 91, and the second cover 92. A second storage chamber E2 is formed in a space surrounded by the outer wall of the cylindrical portion of the case body 90, the side wall of the box-shaped portion, and the third cover.

[0030] Because the electric circuit unit EU is accommodated in the second accommodation chamber E2 of the case 9, the case 9 is also provided with a first connector CN1 to which power wiring from a high-voltage DC power supply (not shown) with a rated voltage of 200 volts or more is connected (see FIG. 3 ). The case 9 is also provided with a second connector CN2 to which power wiring of about 12 volts is connected to supply drive power to the control devices in the electric circuit unit EU and signal wiring connected to control devices higher than the electric circuit unit EU, such as a vehicle control device (not shown) that controls the entire vehicle, various sensors, etc. As will be described in detail later, a coolant supply port Wi, which serves as an inlet for coolant for cooling the inverter and smoothing capacitor of the electric circuit unit EU and the power transmission mechanism TA, and a coolant discharge port Wo, which serves as an outlet for coolant, are also provided on the case 9 or on a component (e.g., an oil cooler) attached to the case 9.

[0031] The case 9 is provided with oil passages for circulating oil so that lubricating oil can be appropriately supplied to the input bearing B2, counter bearing B3, and differential bearing B4. For example, an oil passage for supplying oil to the input bearing B2, an oil passage for supplying oil to the counter bearing B3, and an oil passage for supplying oil to the differential bearing B4 are formed inside a protrusion 99 formed on the first cover 91 shown in FIG.

[0032] The oil also cools the rotor coil 13 and the stator coil 17, which become overheated due to the flow of current. Specifically, the rotor coil 13 and the stator coil 17 are cooled by pouring oil onto the rotor coil end portions 13e protruding from the end of the rotor 11 in the axial direction L and the stator coil end portions 17e protruding from the end of the stator 15 in the axial direction L.

[0033] The oil that has been used to lubricate the bearings, cool the coils, etc. is released into the case 9 and is stored in an oil reservoir P (see FIG. 3) provided at the bottom of the case 9. The oil stored in the oil reservoir P is sucked in and discharged by an oil pump (not shown) and supplied to the first oil supply unit 81, the second oil supply unit 82, and other oil passages. In this embodiment, the oil discharged from the oil pump is cooled by heat exchange with cooling water in the oil cooler OC.

[0034] The cooling structure for the stator coil 17 and the rotor coil 13, and the lubrication structure for the power transmission mechanism TA related to the cooling structure will be described below with reference to Figures 4 to 7. First, the cooling structure for the stator coil 17 and the rotor coil 13 will be described with reference to Figures 4 and 5. Figure 4 is a schematic cross-sectional view of the vicinity of the rotor coil end 13e and the stator coil end 17e on the first axial side L1, and Figure 5 is a schematic perspective view of the vicinity of the rotor coil end 13e and the stator coil end 17e on the first axial side L1.

[0035] 4 and 5 , the case 9 is provided with a first oil supply unit 81 that supplies oil to the stator coil end portions 17e from the radial outside R2 of the stator coil end portions 17e, and a second oil supply unit 82 that supplies oil to the rotor coil end portions 13e from the outside in the axial direction L (in this case, the first axial side L1) of the rotor coil end portions 13e. When coil end portions are provided on both sides in the axial direction L as in this embodiment, the rotor coil end portion 13e on the second axial side L2 is also provided with the second oil supply unit 82 so as to supply oil to the rotor coil end portion 13e from the second axial side L2, which is outside the rotor coil end portion 13e in the axial direction L. In this way, in this embodiment, cooling oil can be individually supplied to the rotor coil end portions 13e and the stator coil end portions 17e of the wound-field rotating electric machine 1 via the first oil supply unit 81 and the second oil supply unit 82.

[0036] Oil is injected into the rotor coil end portions 13e from a second oil supply portion 82 arranged outside the rotor coil end portions 13e in the axial direction L. Note that, as shown in Figures 4 and 5, this embodiment illustrates an example in which the second oil supply portion 82 is provided so as to have an opening on the diagonally upper side V1 of the rotor coil end portions 13e, but the second oil supply portion 82 may also open at a position adjacent to the rotor coil end portions 13e in the axial direction L. Furthermore, this does not preclude a configuration in which a tubular second oil supply portion 82 that is thinner than shown is provided and extends in the axial direction L, and oil drips from an opening of the second oil supply portion 82 arranged on the radially outer side R2 of the rotor coil end portions 13e.

[0037] Oil is dripped or sprayed onto the stator coil end portion 17e from a first oil supply portion 81 disposed on the radially outer side R2 of the stator coil end portion 17e. Figures 4 and 5 show an example in which the opening of the first oil supply portion 81 is located on the radially outer side R2 of the stator coil end portion 17e. However, like the second oil supply portion 82, the first oil supply portion 81 may be configured to have an opening provided on the axially outer side L of the stator coil end portion 17e and to spray oil from that opening.

[0038] Because the rotor 11 is a rotating member, oil supplied to the rotor coil end portion 13e and heated by heat exchange with the rotor coil 13 is scattered radially outward R2 by centrifugal force. Because the stator coil end portion 17e is located radially outward R2 of the rotor coil end portion 13e, heated oil is scattered from the rotor coil end portion 13e to the stator coil end portion 17e. As a result, even if oil is supplied from the first oil supply portion 81, the cooling effect of the stator coil end portion 17e may be reduced. Similarly, heated oil may fall from the stator coil end portion 17e located above the rotor coil end portion 13e on the upper side V1 to the rotor coil end portion 13e due to gravity, potentially reducing the cooling effect of the rotor coil end portion 13e.

[0039] 4 and 5 , in this embodiment, a regulating member 8 is disposed between the stator coil end portion 17e and the rotor coil end portion 13e in the radial direction R, to regulate the flow of oil in the radial direction R between the stator coil end portion 17e and the rotor coil end portion 13e. The first oil supply portion 81 that supplies oil to the stator coil end portion 17e from the radial outside R2 of the stator coil end portion 17e can also be said to be an oil supply portion that supplies oil to the stator coil end portion 17e from the radial outside R2 of the regulating member 8. Note that even if the first oil supply portion 81 is provided with an opening on the outside in the axial direction L of the stator coil end portion 17e and is configured to inject oil from this opening, there is no problem as long as the opening is located on the radial outside R2 of the regulating member 8.

[0040] The provision of such a restricting member 8 makes it possible to restrict oil that has cooled the rotor coil end portion 13e and become hot from flowing toward the stator coil end portion 17e, and restricts oil that has cooled the stator coil end portion 17e and become hot from flowing toward the rotor coil end portion 13e. Therefore, in this embodiment, the rotor coil end portion 13e and the stator coil end portion 17e can be effectively cooled separately, making it easy to improve the cooling performance of the rotor coil 13 and the stator coil 17.

[0041] As described above, the temperature of the oil increases after heat exchange with the coil end portions. Therefore, it is preferable that the restricting member 8 be made of a material with high heat resistance and low thermal conductivity. The restricting member 8 may be made of, for example, carbon fiber reinforced plastics (CFRP), fiber reinforced plastics (FRP), other synthetic materials, ceramics, or other insulating materials. In this embodiment, the restricting member 8 is formed in a cylindrical shape so as to cover the rotor coil end portions 13e from the circumferential direction C. Resin materials are easy to use for forming such a cylindrical restricting member 8. As shown in FIGS. 4 and 5 , the end of the restricting member 8 opposite the side from which the rotor coil end portions 13e protrude in the axial direction L abuts against the rotor core 12, and the end on the side from which the rotor coil end portions 13e protrudes beyond the end of the rotor coil end portions 13e, thereby covering the rotor coil end portions 13e from the radially outer side R2 to the entire circumferential direction C.

[0042] The rotor coil 13 is wound around a rotor coil holding member 14 (so-called bobbin) that holds the rotor coil 13. In this embodiment, the rotor coil holding member 14, around which the rotor coil 13 is wound, is fixed to the rotor core 12 to form the rotor 11. The restricting member 8 is formed in a cylindrical shape extending in the axial direction L and the circumferential direction C. As described above, the end of the restricting member 8 opposite the end from which the rotor coil end portion 13e protrudes in the axial direction L abuts against the rotor core 12. In this embodiment, the restricting member 8 is also fixed to the rotor core 12, and the restricting member 8 also rotates integrally with the rotor 11. Of course, the restricting member 8 may be fixed to the stator 15. For example, the restricting member 8 may be fixed to the stator core 16. As shown in FIGS. 4 and 5 , in this embodiment, the restricting member 8, formed in a cylindrical shape extending in the axial direction L and the circumferential direction C, is attached to cover the entire outer circumferential surface 14a of the rotor coil holding member 14. In other words, the restricting member 8 is disposed so as to overlap the entire stator coil end portion 17e and the entire rotor coil end portion 13e when viewed in the radial direction R.

[0043] As shown in FIG. 1 , the rotating electric machine 1 is disposed on an upper side V1 of the power transmission mechanism TA constituting the vehicle drive device 10. Therefore, the oil that has cooled the stator coil end portions 17e and the rotor coil end portions 13e moves due to gravity to a lower side V2 within the case 9 and reaches the oil reservoir P. The oil path includes rotating members that constitute the counter gear mechanism 3, the differential gear mechanism 4, and the like, as well as bearings that support the rotating members. Therefore, it is preferable that the oil that has cooled the stator coil end portions 17e and the rotor coil end portions 13e be used to lubricate these rotating members and bearings. In this embodiment, a drain path is provided to discharge the oil so that the oil that has cooled the stator coil end portions 17e and the rotor coil end portions 13e can be appropriately guided to the oil reservoir P and other locations to be lubricated.

[0044] Fig. 6 is an explanatory diagram of the vehicle drive device 10 viewed from the first side X1 in the front-rear direction, and schematically shows the positions of the first oil discharge passage 88 and the second oil discharge passage 89. Fig. 7 is an explanatory diagram of the vehicle drive device 10 viewed from the second axial side L2, and schematically shows the positions of the first oil discharge passage 88 and the second oil discharge passage 89.

[0045] The case 9 has an inner wall surface 9a that radially surrounds the stator 15, which is disposed on the radially outer side R2 of the inner rotor type rotating electric machine 1. This inner wall surface 9a also surrounds the stator coil end portion 17e from the radially outer side R2. As shown in FIG. 7 , the inner wall surface 9a has an upper facing region 9u, which is a region located relatively on the upper side V1 and faces the stator coil end portion 17e from the upper side V1, and a lower facing region 9d, which is a region located relatively on the upper side V1 and faces the stator coil end portion 17e from the lower side V2. The inner wall surface 9a also has openings through which oil flows into the first oil discharge passage 88 and the second oil discharge passage 89. The openings of the first oil discharge passage 88 and the second oil discharge passage 89 are both located in the lower facing region 9d. In consideration of oil discharge, the opening is preferably located at the lowest side V2 of the lower opposing region 9 d, but does not have to be located at the lowest position as long as it is within the range of the lower opposing region 9 d. Note that the inner wall surface 9 a may cover the entire area of ​​the stator core 16 and the stator coil end portion 17 e in the circumferential direction C, or may cover only a part of it.

[0046] An oil storage space E18 capable of storing oil is formed in the lower part of the case 9. A portion of the oil storage space E18 may be configured as the oil storage portion P, or the oil storage portion P may be provided so as to communicate with the oil storage space E18. The first oil discharge passage 88 connects the lower opposing region 9d to the oil storage space E18 formed in the lower part of the case 9. As described above, the oil storage space E18 doubles as the oil storage portion P or is connected to the oil storage portion P. Therefore, it can be said that the first oil discharge passage 88 connects the lower opposing region 9d to the oil storage portion P. As shown in FIG. 6 , for example, oil that has cooled the stator coil end portion 17e and the rotor coil end portion 13e lubricates the counter bearing B3 and is then discharged to the oil storage portion P through the first oil discharge passage 88.

[0047] The second oil discharge passage 89 is provided to connect the lower opposing region 9d with the differential gear mechanism 4. As shown in Figures 6 and 7, the oil that has cooled the stator coil end portion 17e and the rotor coil end portion 13e passes through the second oil discharge passage 89 and is supplied to the differential bearing B4 and the meshing portions of the gears housed inside the differential case 42.

[0048] The oil supplied to the stator coil end portion 17e and the rotor coil end portion 13e is distributed to a first oil discharge passage 88 and a second oil discharge passage 89. If an excessive amount of oil is supplied to the differential gear mechanism 4, there is a risk that the drag resistance caused by the gears will increase. However, in this embodiment, by distributing the oil after cooling the coils of the rotating electric machine 1 to two oil discharge passages, an appropriate amount of oil can be supplied to the differential gear mechanism 4, thereby enabling the differential gear mechanism 4 to be properly lubricated.

[0049] The above description has been given using a three-axis vehicle drive system 10 in which the rotating electric machine 1 is disposed on the first axis A1, the counter gear mechanism 3 functioning as a reduction mechanism is disposed on the second axis A2, and the differential gear mechanism 4 is disposed on the third axis A3. However, the configuration in which the restricting member 8 is disposed between the stator coil end portion 17e and the rotor coil end portion 13e in the radial direction R in the EESM is not limited to the three-axis vehicle drive system 10. It can also be applied to a single-axis vehicle drive system including the rotating electric machine 1, a reduction mechanism using a planetary gear mechanism, and a differential gear mechanism using a planetary gear mechanism or a bevel gear mechanism. Naturally, it can also be applied to a vehicle drive system (i.e., the rotating electric machine 1) having only the rotating electric machine 1. Naturally, it can also be applied to a two-axis vehicle drive system and an EESM in a vehicle drive system with four or more axes. Similarly, the first oil drain passage 88 and the second oil drain passage 89 can be provided regardless of the number of axes constituting the vehicle drive system.

[0050] As described above, in the rotating electric machine 1 and vehicle drive device 10 of this embodiment, it is possible to appropriately cool the coils of both the rotor 11 and the stator 15 of the wound-field rotating electric machine 1. In other words, it is also possible to appropriately recover heat from the rotor coil 13 and the stator coil 17. Furthermore, the oil that has cooled the rotor coil 13 and the stator coil 17 is also supplied to the bearings and the meshing portions of the gears, so that heat can also be recovered from the power transmission mechanism TA.

[0051] Unlike conventional vehicles that use an internal combustion engine as the primary driving force for the wheels W, this type of heat recovery is extremely useful in electric vehicles, which cannot utilize the exhaust heat of the internal combustion engine for heating. In conventional vehicles powered by an internal combustion engine, the cooling water, whose temperature has been increased by heat exchange with the internal combustion engine, is used as a heating source. However, in vehicles without an internal combustion engine, such as electric vehicles, or vehicles that have an internal combustion engine but are sometimes stopped, such as hybrid vehicles, the number of heat sources that can utilize the exhaust heat for heating is fewer than in conventional vehicles. For this reason, electric vehicles and hybrid vehicles are increasingly being equipped with electric heaters for heating or using heat pump systems for heating as well as cooling. Naturally, using an electric heater increases power consumption. Furthermore, even in the case of a heat pump system, when the outside temperature is low, the amount of heat pumped from the outside air decreases, which can increase the load on the air conditioner compressor and other components, resulting in increased power consumption.

[0052] As described above, in the rotating electric machine 1 and the vehicle drive device 10 of this embodiment, the rotor coil 13 and the stator coil 17 are cooled separately. Therefore, the heat recovered from the rotor coil 13 and the heat recovered from the stator coil 17 can be transferred to the coolant in the oil cooler OC, which is a heat exchanger with the coolant, via the oil reservoir P without losing heat. The coolant corresponds to the heat medium in the heat exchanger (oil cooler OC).

[0053] In this embodiment, as shown in FIG. 3 , the oil cooler OC is attached to the outside of the case 9. Coolant is supplied from a coolant supply port Wi shown in FIG. 3 and cools the electric circuit unit EU (inverter, DC-DC converter, smoothing capacitor, etc.) and the rotating electric machine 1 (e.g., the stator 15) before being supplied to the oil cooler OC. The coolant recovers heat from the oil in the oil cooler OC. That is, oil and coolant are supplied from the inside of the case 9 to the oil cooler OC, and the oil that has exchanged heat with the coolant is supplied back into the case 9. The coolant is discharged to the outside of the vehicle drive system 10 through a coolant discharge port Wo of the oil cooler OC. The discharged coolant can exchange heat with the air conditioner refrigerant in an air conditioner heat exchanger (chiller or water-cooled condenser, not shown). The coolant can also exchange heat with the battery cooler coolant in a battery cooler of a DC power supply. Since the performance of a DC power supply decreases in a low-temperature environment, it is preferable to be able to heat the DC power supply to an appropriate temperature when the temperature of the DC power supply is low, such as when starting a vehicle.

[0054] In this way, the rotating electric machine 1 and vehicle drive device 10 of this embodiment can appropriately cool both the rotor 11 and the stator 15 of the wound field type rotating electric machine 1, and when a heat source is required, not only can the recovered heat be discarded, but also the exhaust heat can be effectively utilized.

[0055] Summary of the embodiment The rotating electric machine (1) and the vehicle drive device (10) described above will be briefly summarized below.

[0056] In one aspect, the rotating electric machine (1) comprises a stator (15) having a stator coil (17), a rotor (11) having a rotor coil (13), and a case (9) that houses the stator (15) and the rotor (11), wherein a direction along a rotation axis (first axis A1) of the rotor (11) is defined as an axial direction (L), a direction perpendicular to the axial direction (L) is defined as a radial direction (R), and the rotor (11) is disposed on the inside (R1) of the radial direction (R) with respect to the stator (15), and an end of the stator coil (17) in the axial direction (L) is defined as a stator coil end portion (17e), and the axial direction (R) of the rotor coil (13) is defined as a stator coil end portion (17e). The rotor coil end portion (13e) has an end in the axial direction (L) as a rotor coil end portion (13e), and a regulating member (8) that regulates the flow of oil in the radial direction (R) between the stator coil end portion (17e) and the rotor coil end portion (13e) is arranged between the stator coil end portion (17e) and the rotor coil end portion (13e) in the radial direction (R), and the regulating member (81) supplies oil to the stator coil end portion (17e) from the outside (R2) in the radial direction (R) with respect to the regulating member (8), and a second oil supply portion (82) that supplies oil to the rotor coil end portion (13e) from the outside in the axial direction (L) with respect to the rotor coil end portion (13e).

[0057] According to this configuration, cooling oil can be supplied individually to the coil end portions (13e, 17e) of both the rotor (11) and the stator (15) of the wound-field rotating electric machine (1). Furthermore, according to this configuration, a restricting member (8) is disposed between the stator coil end portion (17e) and the rotor coil end portion (13e) in the radial direction (R). This restricts oil that has cooled the stator coil end portion (17e) and become hotter from flowing toward the rotor coil end portion (13e), and restricts oil that has cooled the rotor coil end portion (13e) and become hotter from flowing toward the stator coil end portion (17e). Therefore, according to this configuration, the stator coil end portion (17e) and the rotor coil end portion (13e) can be effectively cooled individually, which facilitates improving the cooling performance of the stator coil (17) and the rotor coil (13). That is, this configuration provides a technique for appropriately cooling the rotor (11) and stator (15) of a wound-field type rotating electric machine (1), as well as the coils (13, 17) of both.

[0058] Here, it is preferable that the regulating member (8) is made of a heat insulating material.

[0059] If the regulating member (8) has high thermal conductivity, heat exchange between the oil supplied to the stator coil end portion (17e) and the oil supplied to the rotor coil end portion (13e) can be facilitated via the regulating member (8). If the regulating member (8) is made of a heat insulating material, heat transfer between the stator coil end portion (17e) and the rotor coil end portion (13e) can be further reduced. Therefore, the cooling performance of the stator coil end portion (17e) and the rotor coil end portion (13e) can be easily improved.

[0060] Furthermore, it is preferable that the rotor (11) of the rotating electric machine (1) further comprises a rotor coil holding member (14) that holds the rotor coil (13), and that the regulating member (8) is formed in a cylindrical shape extending in the axial direction (L) and the circumferential direction (C), with the direction circumferentially circumferential around the rotation axis (first axis A1) of the rotor (11) being the circumferential direction (C), and is attached so as to cover the outer peripheral surface (14a) of the rotor coil holding member (14).

[0061] The cylindrical configuration of the restricting member (8) facilitates restricting the flow of oil between the stator coil end portion (17e) and the rotor coil end portion (13e), and effectively limits heat transfer between the stator coil end portion (17e) and the rotor coil end portion (13e), thereby facilitating improved cooling performance of the stator coil end portion (17e) and the rotor coil end portion (13e).

[0062] In one aspect, a vehicle drive device (10) includes the above-described rotating electric machine (1), a pair of output members (differential side gears 45, drive shafts DS) each of which is drivingly connected to a wheel (W), and a power transmission mechanism (TA) housed in the case (9) and transmitting power between the rotor (11) and the pair of output members (differential side gears 45, drive shafts DS), wherein the power transmission mechanism (TA) includes a differential gear mechanism (4) that distributes the driving force transmitted from the rotating electric machine (1) to the pair of output members (differential side gears 45, drive shafts DS), and the case The case (9) preferably has an inner wall surface (9a) surrounding the stator coil end portion (17e) from the outside (R2) in the radial direction (R), and also has a first oil discharge passage (88) and a second oil discharge passage (89), the first oil discharge passage (88) being provided so as to communicate between a lower opposing region (9d) which is a region on the inner wall surface (9a) facing the stator coil end portion (17e) from the lower side (V2) and an oil reservoir portion (P, E18) formed in the lower part of the case (9), and the second oil discharge passage (89) being provided so as to communicate between the lower opposing region (9d) and the differential gear mechanism (4).

[0063] According to this configuration, by providing two oil discharge passages, the first oil discharge passage and the second oil discharge passage, oil supplied to the stator coil end portion and the rotor coil end portion via the first supply portion and the second supply portion can be appropriately discharged from the space surrounded by the inner wall surface of the case. Furthermore, according to this configuration, oil discharged from the space surrounded by the inner wall surface of the case can be distributed to the differential gear mechanism and the oil reservoir. Therefore, the oil after cooling the stator coil end portion or the rotor coil end portion can be used to supply an appropriate amount of oil to the differential gear mechanism, thereby appropriately lubricating the differential gear mechanism. While excessive oil supply to the differential gear mechanism increases drag resistance due to the gears, this configuration makes it easy to set the appropriate amount of oil for lubrication of the differential gear mechanism.

[0064] 1: rotating electric machine, 4: differential gear mechanism, 8: restricting member, 9: case, 9a: inner wall surface, 9d: lower opposing area, 10: vehicle drive device, 11: rotor, 13: rotor coil, 13e: rotor coil end portion, 14: rotor coil holding member, 14a: outer circumferential surface, 15: stator, 17: stator coil, 17e: stator coil end portion, 45: differential side gear (output member), 81: first oil supply portion, 82: second oil supply portion, 88: first discharge oil passage, 89: second discharge oil passage, A1: first shaft (rotational axis of rotor), C: circumferential direction, DS: drive shaft (output member), E18: oil storage space (oil storage portion), JS: connecting shaft (output member), L: axial direction, P: oil storage portion, R: radial direction, R2: radially outer side (radially outer side), TA: power transmission mechanism, V2: lower side, W: wheel

Claims

1. A rotating electric machine comprising: a stator having a stator coil; a rotor having a rotor coil; and a case that houses the stator and the rotor, wherein the direction along the rotational axis of the rotor is defined as the axial direction and the direction perpendicular to the axial direction is defined as the radial direction, and the rotor is arranged radially inside the stator, wherein the axial end of the stator coil is defined as a stator coil end portion, and the axial end of the rotor coil is defined as a rotor coil end portion, and a regulating member that regulates the flow of oil in the radial direction between the stator coil end portion and the rotor coil end portion is arranged radially between the stator coil end portion and the rotor coil end portion, and the rotating electric machine comprises: a first oil supply unit that supplies oil to the stator coil end portion from the radial outside of the regulating member, and a second oil supply unit that supplies oil to the rotor coil end portion from the axial outside of the rotor coil end portion.

2. The rotating electric machine according to claim 1, wherein the restricting member is made of a heat insulating material.

3. A rotating electric machine as described in claim 1, wherein the rotor further comprises a rotor coil holding member that holds the rotor coil, and the direction around the rotational axis of the rotor is the circumferential direction, and the restricting member is formed in a cylindrical shape extending in the axial direction and the circumferential direction, and is attached so as to cover the outer peripheral surface of the rotor coil holding member.

4. A vehicle drive device comprising: a rotating electric machine according to any one of claims 1 to 3; a pair of output members each drivingly connected to a wheel; and a power transmission mechanism housed in the case and transmitting power between the rotor and the pair of output members, wherein the power transmission mechanism comprises a differential gear mechanism which distributes the driving force transmitted from the rotating electric machine to the pair of output members, the case having an inner wall surface which surrounds the stator coil end portion from the outside in the radial direction, and comprising a first discharge oil passage and a second discharge oil passage, the first discharge oil passage being arranged to communicate between a lower opposing region, which is an area on the inner wall surface facing the stator coil end portion from below, and an oil reservoir formed in the lower part of the case, and the second discharge oil passage being arranged to communicate between the lower opposing region and the differential gear mechanism.

Images