Driving device

Abstract

To realize a technology in which a support bearing that supports a rotor shaft on a first axial side relative to the rotor is supported by a case from the radial outside and the first axial side, a rotation sensor is arranged axially between the rotor and the support bearing, and further, even in a configuration in which the inner diameter of a sensor stator is smaller than the outer diameter of the support bearing, the support bearing and rotor shaft can be assembled to the case while the support bearing can be appropriately biased in the axial direction.SOLUTION: A driving device includes a rotating electric machine, a rotor shaft 12, a rotation sensor 2, and a case. An inner ring 51b of a support bearing 51 is biased toward a first axial side L1 by a biasing mechanism 4. The biasing mechanism 4 includes a first support 41, a second support 42, and an elastic body 43 that biases the first support 41 and the second support 42 in a direction of separating them from each other in the axial direction L, and an inner diameter D3 of the elastic body 43 is larger than an outer diameter D4 of the inner ring 51b.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a drive device including a rotating electric machine having a rotor, a rotor shaft fixed to the rotor, a rotation sensor that detects the rotation of the rotor, and a case that houses the rotating electric machine and the rotation sensor. [Background technology]

[0002] An example of such a drive device is disclosed in Japanese Patent Application Laid-Open No. 2020-156279 (Patent Document 1). Hereinafter, in the description of the background art, the reference numerals in parentheses refer to those in Patent Document 1. The drive device of Patent Document 1 includes a rotating electric machine (100), a rotor shaft (3B) as a rotor shaft, a resolver (7) as a rotation sensor, and a housing (1) as a case. The rotor shaft (3B) is rotatably supported relative to the housing (1) via a rear ball bearing (6) on a first axial side (the left side in Figure 1 of Patent Document 1), which is one axial side of the rotor (3).

[0003] As shown in FIG. 1 of Patent Document 1, the rear ball bearing 6 is supported by the housing 1 from the radially outer side and the first axial side (the left side in FIG. 1). As described in paragraph 0020 of Patent Document 1, the rear ball bearing 6 has an inner ring 6B fixed to the rotor shaft 3B by an interference fit, and an outer ring 6A fixed to the housing 1 by a clearance fit. Therefore, during manufacture of this drive unit, it is understood that the rotor shaft 3B to which the rear ball bearing 6 is fixed by an interference fit is assembled to the housing 1 from the other axial side, i.e., the second axial side (the right side in FIG. 1 of Patent Document 1). For the purpose described in paragraph 0043 of Patent Document 1, the rear ball bearing 6 is biased in the axial direction by a wave washer 9. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-156279 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, in the drive device of Patent Document 1, the support bearing (rear ball bearing in Patent Document 1) that supports the rotor shaft on the first axial side (left side in Figure 1 of Patent Document 1) of the rotor is supported by the case (housing in Patent Document 1) from the radial outside and the first axial side, and the rotation sensor (resolver in Patent Document 1) is disposed on the first axial side of the support bearing. Although not described in Patent Document 1, it is also possible to configure the rotation sensor to be disposed axially between the rotor and the support bearing. Even when such a configuration is adopted, it is desirable to be able to assemble the support bearing and rotor shaft to the case while appropriately biasing the support bearing in the axial direction. In this regard, in the drive device of Patent Document 1, as shown in Figure 1 of Patent Document 1, the inner diameter of the sensor stator, which is a member of the rotation sensor fixed to the case, is smaller than the outer diameter of the support bearing. Therefore, if the rotation sensor were configured to be positioned axially between the rotor and the support bearing, interference between the sensor stator and the support bearing could prevent the rotor shaft, to which the support bearing is fixed by an interference fit as described above, from being assembled to the case from the second axial side (the right side in Figure 1 of Patent Document 1).

[0006] Therefore, it is desirable to realize a technology that allows the support bearing and rotor shaft to be assembled to the case while appropriately biasing the support bearing in the axial direction, even if the support bearing that supports the rotor shaft on the first axial side relative to the rotor is supported by the case from the radial outside and the first axial side, and the rotation sensor is positioned axially between the rotor and the support bearing, and the inner diameter of the sensor stator is smaller than the outer diameter of the support bearing. [Means for solving the problem]

[0007] A drive device according to the present disclosure is a drive device comprising: a rotating electric machine having a rotor; a rotor shaft fixed to the rotor so as to rotate integrally with the rotor; a rotation sensor that detects rotation of the rotor; and a case that houses the rotating electric machine and the rotation sensor, wherein a direction along the rotation axis of the rotor shaft is defined as an axial direction, a direction perpendicular to the rotation axis is defined as a radial direction, one side in the axial direction is defined as an axial first side, and the other side in the axial direction is defined as an axial second side, and the rotor shaft is rotatably supported relative to the case via a support bearing on the axial first side relative to the rotor, and the rotation sensor comprises a sensor rotor that rotates integrally with the rotor and a sensor stator fixed to the case, and is disposed axially between the rotor and the support bearing, and an inner diameter of the sensor stator is larger than an outer diameter of the support bearing. the support bearing comprises an outer ring, an inner ring, and rolling elements that roll between the outer ring and the inner ring; the case comprises a case-side support portion that supports the outer ring from the outside in the radial direction and from the first axial side; the inner ring is fitted onto an outer peripheral surface of the rotor shaft and is urged toward the first axial side by a urging mechanism that is arranged between the inner ring and a support surface of the rotor shaft that faces the first axial side; the urging mechanism comprises a first support body that is arranged to contact the support surface from the first axial side, a second support body that is arranged to contact the inner ring from the second axial side without contacting the outer ring; and an elastic body that is arranged between the first support body and the second support body and urges the first support body and the second support body in a direction that separates them from each other in the axial direction, and the inner diameter of the elastic body is larger than the outer diameter of the inner ring.

[0008] According to this configuration, the inner ring of the support bearing is biased in the axial direction by the biasing mechanism, so the fit gap between the outer ring and the case support part can be made smaller than the fit gap between the inner ring and the rotor shaft. This allows for an assembly sequence in which the support bearing, which supports the rotor shaft on the first axial side of the rotor, is first assembled to the case support part, and then the rotor shaft is assembled to the case. Therefore, even if the support bearing is supported by the case from the radial outside and the first axial side, the rotation sensor is disposed axially between the rotor and the support bearing, and the inner diameter of the sensor stator is smaller than the outer diameter of the support bearing, it is possible to assemble the support bearing and the rotor shaft to the case while avoiding interference with the sensor stator.

[0009] Furthermore, with this configuration, because the support bearing is axially biased by the biasing mechanism, axial rattle of the rotor and rotor shaft can be minimized. Furthermore, with this configuration, the first support is arranged to contact the support surface of the rotor shaft from the first axial side, the second support is arranged to contact the inner ring from the second axial side, and the elastic body is arranged between the first support and the second support, so the inner ring can be biased in the axial direction by the elastic body while the inner diameter of the elastic body is made larger than the outer diameter of the inner ring. Therefore, it is easy to ensure a large diameter for the elastic body, and as a result, it is easy to ensure an elastic force of the elastic body that can appropriately bias the support bearing in the axial direction.

[0010] As described above, with this configuration, the support bearing that supports the rotor shaft on the first axial side relative to the rotor is supported by the case from the radial outside and the first axial side, and the rotation sensor is arranged axially between the rotor and the support bearing.Furthermore, even if the inner diameter of the sensor stator is smaller than the outer diameter of the support bearing, it is possible to assemble the support bearing and rotor shaft to the case and to appropriately bias the support bearing.

[0011] Further features and advantages of the drive device will become apparent from the following description of an embodiment thereof, which is given with reference to the drawings. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view of a drive device according to an embodiment taken along an axial direction; [Figure 2] Enlarged view of part of Figure 1 [Figure 3] 10A and 10B are diagrams illustrating a method for manufacturing a drive device according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] An embodiment of a drive device will be described with reference to the drawings. In this embodiment, it is assumed that the drive device is a vehicle drive device that drives a vehicle (wheels), but the drive device is not limited to a vehicle, and the drive device may also drive a machine tool, a pump, an air conditioner compressor, etc.

[0014] In this specification, the term "rotating electric machine" is used as a concept that includes motors, generators, and motor-generators that function as both motors and generators as needed. Furthermore, in this specification, with regard to the arrangement of two elements, "overlapping when viewed from a specific direction" means that when an imaginary line parallel to the line of sight is moved in each direction perpendicular to the imaginary line, there is at least a partial area where the imaginary line intersects both of the two elements.

[0015] As shown in FIG. 1, the drive device 100 includes a rotating electric machine 1, a rotor shaft 12, a rotation sensor 2, and a case 3. In the example shown in FIG. 1, the drive device 100 is configured to output the driving force of the rotating electric machine 1 to an output shaft 6. In this embodiment, it is assumed that the drive device 100 is a vehicle drive device, and therefore the output shaft 6 is drivingly connected to wheels (connected so as to be able to transmit driving force). The drive device 100 transmits the driving force of the rotating electric machine 1 to the wheels to run the vehicle. The output shaft 6 is connected to the wheels via a gear mechanism, such as a counter gear mechanism or a differential gear mechanism, for example.

[0016] The rotating electric machine 1 is electrically connected to an electricity storage device such as a battery or a capacitor. The rotating electric machine 1 is electrically connected to the electricity storage device, for example, via an inverter. The rotating electric machine 1 generates driving force by powering using the electric power stored in the electricity storage device. The rotating electric machine 1 also generates electricity using driving force transmitted to the rotating electric machine 1 (for example, driving force transmitted from the wheels), and charges the electricity storage device.

[0017] As shown in FIG. 1, a rotating electric machine 1 includes a rotor 10. A rotor shaft 12 is fixed to the rotor 10 so as to rotate integrally with the rotor 10. Here, the direction along the rotation axis X of the rotor shaft 12 is referred to as the "axial direction L," one side of the axial direction L is referred to as the "first axial side L1," and the other side of the axial direction L is referred to as the "second axial side L2." Furthermore, the direction perpendicular to the rotation axis X is referred to as the "radial direction R," and the side of the rotation axis X in the radial direction R (i.e., the inside of the radial direction R) is referred to as the "radial inner side R1," and the opposite side (i.e., the outside of the radial direction R) is referred to as the "radial outer side R2."

[0018] The rotating electric machine 1 further includes a stator 11. The stator 11 is fixed to a case 3 (specifically, a first case portion 31 described later). The rotor 10 is supported by the case 3 so as to be rotatable relative to the stator 11. The rotor 10 is supported by the case 3 via a rotor shaft 12. In this embodiment, the rotating electric machine 1 is a rotating field type rotating electric machine, in which a permanent magnet is provided in the rotor 10 (specifically, a rotor core that is the core of the rotor 10), and a coil is wound around the stator 11 (specifically, a stator core that is the core of the stator 11). In addition, in this embodiment, the rotating electric machine 1 is an inner rotor type rotating electric machine, in which the rotor 10 is disposed radially inward R1 of the stator 11.

[0019] The rotation sensor 2 detects the rotation of the rotor 10. As shown in FIG. 2, the rotation sensor 2 includes a sensor rotor 20 that rotates integrally with the rotor 10, and a sensor stator 21 fixed to the case 3. In this embodiment, the rotation sensor 2 detects the rotation of the rotor 10 by detecting the rotation of a rotor shaft 12 that rotates integrally with the rotor 10. For this reason, the sensor rotor 20 is fixed to the rotor shaft 12. In addition, in this embodiment, the sensor stator 21 is fixed to a case-side support portion 30 (described later) that is provided on the case 3. Here, a case where a resolver is used as the rotation sensor 2 is exemplified, but various types of rotation sensors such as an inductive position sensor can be used.

[0020] As shown in FIG. 1 , the case 3 accommodates the rotating electric machine 1 and the rotation sensor 2. The case 3 also accommodates the rotor shaft 12. In this embodiment, the case 3 includes a first case portion 31 and a second case portion 32. The first case portion 31 is formed in a cylindrical shape extending in the axial direction L, and the stator 11 is fixed to the inner circumferential surface of the first case portion 31. The first case portion 31 has an opening at least on a second axial side L2, and the second case portion 32 is fixed to the first case portion 31 so as to close the opening of the first case portion 31 on the second axial side L2.

[0021] The rotor shaft 12 is rotatably supported on the case 3 via a first bearing 51 on a first axial side L1 relative to the rotor 10. Specifically, the rotor shaft 12 is fixed to the rotor 10 so as to have a portion that protrudes from the rotor 10 on the first axial side L1. The portion of the rotor shaft 12 that protrudes from the rotor 10 on the first axial side L1 is supported on the case 3 via the first bearing 51. The first bearing 51 is disposed between the rotor shaft 12 and the case 3 (specifically, a case-side support portion 30, which will be described later) in the radial direction R. The first bearing 51 supports the rotor shaft 12 from the radial outer side R2. In this embodiment, the first bearing 51 corresponds to the "support bearing."

[0022] In this embodiment, the rotor shaft 12 is rotatably supported on the second axial side L2 relative to the rotor 10 via the second bearing 52 relative to the case 3. Specifically, the rotor shaft 12 is fixed to the rotor 10 so as to have a portion that protrudes from the rotor 10 toward the second axial side L2. The portion of the rotor shaft 12 that protrudes from the rotor 10 toward the second axial side L2 is supported by the case 3 via the second bearing 52. The second bearing 52 is disposed between the rotor shaft 12 and the case 3 (specifically, the second case portion 32) in the radial direction R. In this embodiment, the second bearing 52 supports the rotor shaft 12 from the radially outer side R2.

[0023] The first bearing 51 is a rolling bearing such as a ball bearing or a roller bearing. In this embodiment, the second bearing 52 is also a rolling bearing. The first bearing 51 is arranged to contact the case 3 (specifically, the case-side support portion 30) from the second axial side L2, and movement of the rotor shaft 12 toward the first axial side L1 is restricted by the first bearing 51. The second bearing 52 is arranged to contact the case 3 (specifically, the second case portion 32) from the first axial side L1, and movement of the rotor shaft 12 toward the second axial side L2 is restricted by the second bearing 52.

[0024] As shown in FIG. 2, the first bearing 51 includes an outer ring 51a, an inner ring 51b, and rolling elements 51c that roll between the outer ring 51a and the inner ring 51b. In this embodiment, the first bearing 51 is a ball bearing that includes spherical rolling elements 51c. The case 3 includes a case-side support portion 30 that supports the outer ring 51a from the radially outer side R2 and the axially first side L1. Specifically, the case-side support portion 30 includes a cylindrical inner circumferential surface extending in the axial direction L. A stepped portion is formed on this inner circumferential surface, with the diameter of the portion on the axially first side L1 being smaller than that of the portion on the axially second side L2. The outer ring 51a is supported from the radially outer side R2 by the inner circumferential surface of the case-side support portion 30, and is supported from the axially first side L1 by a stepped surface (annular surface) formed on the stepped portion that faces the axially second side L2. The case side support portion 30 is formed, for example, on the first case portion 31, or on a member fixed to the first case portion 31 (for example, a support wall or another case portion).

[0025] An inner ring 51b of the first bearing 51 is fitted onto the outer peripheral surface of the rotor shaft 12. The inner ring 51b is biased toward the first axial side L1 by a biasing mechanism 4 disposed between the inner ring 51b and a support surface 12a of the rotor shaft 12 facing the first axial side L1. In this embodiment, a stepped portion is formed on the outer peripheral surface of the rotor shaft 12, where the portion on the first axial side L1 has a smaller diameter than the portion on the second axial side L2, and the surface (annular surface) formed on this stepped portion facing the first axial side L1 constitutes the support surface 12a. The biasing mechanism 4 will be described in detail later.

[0026] In this embodiment, the linear expansion coefficient of the material making up the case side support part 30 is greater than the linear expansion coefficient of the material making up the outer ring 51a of the first bearing 51. For example, if the material making up at least the case side support part 30 of the case 3 is aluminum and the material making up at least the outer ring 51a of the first bearing 51 is iron such as steel, the linear expansion coefficient of the material making up the case side support part 30 will be greater than the linear expansion coefficient of the material making up the outer ring 51a. In this embodiment, the fit gap in the radial direction R between the outer ring 51a of the first bearing 51 and the case side support part 30 is smaller than the fit gap in the radial direction R between the inner ring 51b of the first bearing 51 and the rotor shaft 12. For example, if the outer ring 51a is fitted to the case side support portion 30 (specifically, the inner surface of the case side support portion 30) by an interference fit, and the inner ring 51b is fitted to the rotor shaft 12 (specifically, the outer surface of the rotor shaft 12) by a clearance fit, the fitting gap in the radial direction R between the outer ring 51a and the case side support portion 30 will be smaller than the fitting gap in the radial direction R between the inner ring 51b and the rotor shaft 12.

[0027] The sensor stator 21 of the rotation sensor 2 is fixed to the case-side support part 30. Specifically, the case-side support part 30 has a mounting surface facing the second axial side L2, radially outwardly R2 from the position where the first bearing 51 is arranged, on the second axial side L2, and the sensor stator 21 is fixed to the mounting surface. Here, the sensor stator 21 is fastened and fixed to the mounting surface by bolts 5.

[0028] As shown in FIG. 1, the rotation sensor 2 is disposed between the rotor 10 and the first bearing 51 in the axial direction L. Specifically, as shown in FIG. 2, the sensor rotor 20 is disposed between the support surface 12a and a portion of the rotor shaft 12 to which the rotor 10 is fixed, in the axial direction L. The sensor stator 21 is disposed radially outwardly R2 from the sensor rotor 20, overlapping with the sensor rotor 20 as viewed in the radial direction R. A first diameter D1, which is the inner diameter of the sensor stator 21, is smaller than a second diameter D2, which is the outer diameter of the first bearing 51. The second diameter D2 is equal to the outer diameter of the outer ring 51a of the first bearing 51. In this embodiment, the first diameter D1 is smaller than the outer diameter of the biasing mechanism 4 (here, the outer diameter of the second support 42, which will be described later). In this embodiment, the first diameter D1 is larger than the inner diameter of the outer ring 51a of the first bearing 51. In this embodiment, the first diameter D1 corresponds to the "inner diameter of the sensor stator", and the second diameter D2 corresponds to the "outer diameter of the first bearing".

[0029] Thus, in this drive device 100, the first bearing 51, which supports the rotor shaft 12 on the first axial side L1 relative to the rotor 10, is supported by the case 3 (specifically, the case-side support part 30) from the radially outer side R2 and the first axial side L1, the rotation sensor 2 is disposed between the rotor 10 and the first bearing 51 in the axial direction L, and further, the first diameter D1 is smaller than the second diameter D2. Such a drive device 100 can be manufactured, for example, by assembling the first bearing 51 and the rotor shaft 12 to the case 3 in the assembly order described below.

[0030] Specifically, as shown in FIG. 3 , after the first bearing 51 (and in this embodiment, the biasing mechanism 4) is assembled to the case 3 (specifically, the case-side support portion 30), the sensor stator 21 is assembled to the case 3. In this embodiment, the sensor stator 21 is fixed to the case-side support portion 30 with bolts 5. Thereafter, the rotor shaft 12 is assembled to the case 3 (specifically, the first case portion 31) from the second axial side L2 to the sensor stator 21 through the radially inner side R1 of the sensor stator 21 so that the inner ring 51b of the first bearing 51 fits onto the outer peripheral surface of the rotor shaft 12. In the example shown in FIG. 3 , the rotor shaft 12, to which the rotor 10 and the sensor rotor 20 (and in this case, the second bearing 52) are fixed, is assembled to the first case portion 31 to which the stator 11 is fixed. In this way, by sequentially performing the steps of assembling the first bearing 51 (and in this embodiment, the biasing mechanism 4) to the case 3, the step of assembling the sensor stator 21 to the case 3, and the step of assembling the rotor shaft 12 to the case 3, it is possible to assemble the first bearing 51 and the rotor shaft 12 to the case 3 while avoiding interference with the sensor stator 21.

[0031] As described above, inner ring 51b of first bearing 51 is biased toward first axial side L1 by biasing mechanism 4 disposed between inner ring 51b and support surface 12a facing first axial side L1 of rotor shaft 12. Details of biasing mechanism 4 will be described below.

[0032] 2, the biasing mechanism 4 includes a first support 41, a second support 42, and an elastic body 43. The first support 41 is disposed so as to contact the support surface 12a of the rotor shaft 12 from a first axial side L1. The second support 42 is disposed on the first axial side L1 relative to the first support 41. The second support 42 is disposed so as to contact the inner ring 51b of the first bearing 51 from a second axial side L2 without contacting the outer ring 51a of the first bearing 51.

[0033] The elastic body 43 is disposed between the first support 41 and the second support 42 (specifically, between them in the axial direction L). The elastic body 43 biases the first support 41 and the second support 42 in a direction separating them from each other in the axial direction L. The first support 41 and the second support 42 are configured to be relatively movable in the axial direction L while being biased by the elastic body 43. As the rotor shaft 12 moves toward the first axial side L1 relative to the first bearing 51, the first support 41 and the second support 42 approach each other in the axial direction L against the biasing force of the elastic body 43. As the rotor shaft 12 moves toward the second axial side L2 relative to the first bearing 51, the first support 41 and the second support 42 move away from each other in the axial direction L due to the biasing force of the elastic body 43. Any elastic member can be used as the elastic body 43. For example, the elastic body 43 may be a wave washer or a disc spring. In this case, the elastic body 43 may be formed by stacking wave washers or disc springs in the axial direction L.

[0034] The first support body 41 and the second support body 42 are formed in the shape of an annular plate along a plane perpendicular to the axial direction L. The first support body 41 and the second support body 42 are fitted to a portion of the outer peripheral surface of the rotor shaft 12 between the support surface 12a and the first bearing 51 in the axial direction L. In this embodiment, the first support body 41 and the second support body 42 are fitted to the rotor shaft 12 by a clearance fit.

[0035] In the example shown in FIG. 2 , a step portion is formed on the end face of the first axial side L1 of the first support 41, where a portion of the radially outer side R2 is closer to the axially second side L2 than a portion of the radially inner side R1. The elastic body 43 is disposed in a space formed on the radially outer side R2 of a step surface (cylindrical surface) formed on the step portion and facing the radially outer side R2, between the end face of the first axial side L1 of the first support 41 and the end face of the second axial side L2 of the second support 42. As described above, in the example shown in FIG. 2 , the step portion formed on the end face of the first axial side L1 of the first support 41 forms a space for disposing the elastic body 43. However, the present invention is not limited to this. Alternatively, the space may be formed by a step portion formed on the end face of the second axial side L2 of the second support 42, or by step portions formed on each of the first support 41 and the second support 42.

[0036] In this embodiment, the end face of the second support 42 on the first axial side L1 is formed flat, and the end face of the inner ring 51b on the second axial side L2 is positioned closer to the second axial side L2 than the end face of the outer ring 51a on the second axial side L2. As a result, the second support 42 is positioned so that it contacts the inner ring 51b from the second axial side L2 without contacting the outer ring 51a. Alternatively, a configuration may be adopted in which the end face of the inner ring 51b on the second axial side L2 is positioned at the same position in the axial direction L as the end face of the outer ring 51a on the second axial side L2. Even in this case, for example, by forming the end face of the second support 42 on the first axial side L1 so that the radially inner portion R1 protrudes toward the first axial side L1 relative to the radially outer portion R2, the second support 42 can be positioned so that it contacts the inner ring 51b from the second axial side L2 without contacting the outer ring 51a.

[0037] 2, the third diameter D3, which is the inner diameter of the elastic body 43, is larger than the fourth diameter D4, which is the outer diameter of the inner ring 51b of the first bearing 51. Therefore, the configuration in which the biasing mechanism 4 biases the inner ring 51b of the first bearing 51 toward the first axial side L1 can be realized while ensuring a large diameter of the elastic body 43, which makes it easier to ensure that the elastic force of the elastic body 43 is sufficient to appropriately bias the first bearing 51 in the axial direction L. In this embodiment, the third diameter D3 corresponds to the "inner diameter of the elastic body," and the fourth diameter D4 corresponds to the "outer diameter of the inner ring."

[0038] In this embodiment, the biasing mechanism 4 includes a locking mechanism 44. The locking mechanism 44 is a mechanism that locks the first support 41 and the second support 42 in the axial direction L so that the first support 41 and the second support 42 do not separate outside a predetermined range. This predetermined range can be, for example, a range in which a biasing force is generated by the elastic body 43 to separate the first support 41 and the second support 42 from each other in the axial direction L (the maximum range in which the biasing force is generated, or a range narrower than the maximum range).

[0039] In the example shown in FIG. 2 , a bent portion formed on the second support 42 constitutes the locking mechanism 44. This bent portion is formed so that an end portion of the second support 42 on the radially outer side R2 is bent toward the axial second side L2 and then bent toward the radially inner side R1 (i.e., so that the axial second side L2 is folded back toward the radially inner side R1). This bent portion is disposed so as to surround the end portion of the first support 41 on the radially outer side R2 from both sides in the axial direction L and from the radially outer side R2. By contacting the first support 41 from the axial second side L2, the bent portion restricts movement of the first support 41 toward the axial second side L2 relative to the second support 42. In this case, the position where the first support 41 contacts this bent portion from the axial first side L1 is the upper limit of the above-mentioned “predetermined range,” and movement of the first support 41 beyond this position toward the axial second side L2 relative to the second support 42 is restricted by the bent portion serving as the locking mechanism 44. 2, a configuration may be adopted in which the first support body 41 is formed with a bent portion that constitutes the locking mechanism 44. Also, a configuration may be adopted in which the first support body 41 and the second support body 42 are formed with an engaging portion (for example, an anchor and a hole) that engages them with each other.

[0040] 2, in this embodiment, the case side support portion 30 is configured to support the biasing mechanism 4 (specifically, at least one of the first support body 41 and the second support body 42) from the radially outer side R2. With this configuration, the component of the elastic force of the elastic body 43 that is directed toward the radially outer side R2 can restrict the biasing mechanism 4 (the second support body 42 in the example shown in FIG. 2) from bending toward the radially outer side R2, and the elastic force of the elastic body 43 can be efficiently applied to the inner ring 51b of the first bearing 51.

[0041] 2, the case-side support part 30 supports the second support 42 (specifically, the bent part constituting the locking mechanism 44 in the second support part 42) from the radially outer side R2. In addition, in the example shown in FIG. 2, the support surface that supports the locking mechanism 44 in the case-side support part 30 from the radially outer side R2 is formed with a larger diameter than the support surface that supports the outer ring 51a of the first bearing 51 in the case-side support part 30 from the radially outer side R2, but these two support surfaces may be formed with the same diameter. In this embodiment, the outer peripheral surface of the biasing mechanism 4 (here, the outer peripheral surface of the bent part constituting the locking mechanism 44) is fitted with the outer peripheral surface of the case-side support part 30 by a clearance fit, but the outer peripheral surface of the biasing mechanism 4 may also be configured to fit with the outer peripheral surface of the case-side support part 30 by an interference fit. Unlike the example shown in Figure 2, when the bent portion constituting the locking mechanism 44 is formed in the first support body 41, the case side support portion 30 can be configured to support the first support body 41 from the radially outer side R2.

[0042] Other Embodiments (1) In the above embodiment, the case-side support portion 30 supports at least one of the first support 41 and the second support 42 from the radially outer side R2. However, the present disclosure is not limited to such a configuration, and a configuration in which neither the first support 41 nor the second support 42 is supported from the radially outer side R2 by the case-side support portion 30 is also possible. Unlike the above embodiment, if the outer diameter of the biasing mechanism 4 is smaller than the first diameter D1, which is the inner diameter of the sensor stator 21, the rotor shaft 12 with the biasing mechanism 4 attached can be assembled to the case 3. In such a case, for example, a configuration in which neither the first support 41 nor the second support 42 is supported from the radially outer side R2 by the case-side support portion 30 is also possible.

[0043] (2) In the above embodiment, the biasing mechanism 4 includes the locking mechanism 44. However, the present disclosure is not limited to such a configuration, and the biasing mechanism 4 may not include the locking mechanism 44.

[0044] (3) In the above embodiment, a configuration has been described as an example in which the linear expansion coefficient of the material making up the case side support part 30 is greater than the linear expansion coefficient of the material making up the outer ring 51a of the first bearing 51. However, the present disclosure is not limited to such a configuration, and a configuration in which the linear expansion coefficient of the material making up the case side support part 30 is equal to or less than the linear expansion coefficient of the material making up the outer ring 51a of the first bearing 51 may also be used.

[0045] (4) Note that the configurations disclosed in the above-described embodiments can be applied in combination with configurations disclosed in other embodiments (including combinations of embodiments described as other embodiments) as long as no contradictions arise. Regarding other configurations, the embodiments disclosed in this specification are merely examples in all respects. Therefore, various modifications can be made as appropriate within the scope of the present disclosure.

[0046] [Summary of this embodiment] The above-described embodiments of the drive device will be summarized below.

[0047] The drive device (100) includes a rotating electric machine (1) having a rotor (10), a rotor shaft (12) fixed to the rotor (10) so as to rotate integrally with the rotor (10), a rotation sensor (2) that detects the rotation of the rotor (10), and a case (3) that houses the rotating electric machine (1) and the rotation sensor (2), and the drive device (100) includes a case (3) that houses the rotating electric machine (1) and the rotation sensor (2), and the case (3) includes a case (3) that houses the case (3) and the rotor shaft (12) and the drive device (100) and the case (3) that houses the case (3) and the rotor shaft (12) and the drive device (100) and the case (3) that houses the case (3) and the rotor shaft (12) and the drive device (100) and the drive device (100) and the case (3) that houses the case (3 ... case (3) that houses the case (3) and the drive device (100) and the drive device (100) The rotor shaft (12) is rotatably supported on the case (3) via a support bearing (51) on the first axial side (L1) of the rotor (10), with the other side of the rotor shaft (12) being a second axial side (L2), and the rotation sensor (2) includes a sensor rotor (20) that rotates integrally with the rotor (10) and a sensor stator (21) fixed to the case (3), and is disposed between the rotor (10) and the support bearing (51) in the axial direction (L). An inner diameter (D1) of the sensor stator (21) is equal to or larger than the inner diameter (D1) of the support bearing (51). The support bearing (51) has an outer diameter (D2) smaller than the outer diameter (D2), and the support bearing (51) includes an outer ring (51a), an inner ring (51b), and a rolling element (51c) that rolls between the outer ring (51a) and the inner ring (51b). The case (3) includes a case-side support part (30) that supports the outer ring (51a) from the outside (R2) in the radial direction (R) and the first axial side (L1). The inner ring (51b) is fitted onto the outer peripheral surface of the rotor shaft (12), and includes an attachment part (30) that is disposed between the inner ring (51b) and a support surface (12a) of the rotor shaft (12) facing the first axial side (L1). the inner ring (51 b) is biased toward the first axial side (L1) by a biasing mechanism (4), the biasing mechanism (4) including: a first support (41) arranged to contact the support surface (12 a) from the first axial side (L1); a second support (42) arranged to contact the inner ring (51 b) from the second axial side (L2) without contacting the outer ring (51 a); and an elastic body (43) arranged between the first support (41) and the second support (42) to bias the first support (41) and the second support (42) in a direction separating them from each other in the axial direction (L);The inner diameter (D3) of the elastic body (43) is larger than the outer diameter (D4) of the inner ring (51b).

[0048] According to this configuration, the inner ring (51b) of the support bearing (51) is biased in the axial direction (L) by the biasing mechanism (4), and therefore the fit gap between the outer ring (51a) and the case-side support portion (30) can be easily made smaller than the fit gap between the inner ring (51b) and the rotor shaft (12). This allows for an assembly order in which the support bearing (51), which supports the rotor shaft (12) on the first axial side (L1) with respect to the rotor (10), is first assembled to the case-side support portion (30), and then the rotor shaft (12) is assembled to the case (3). Therefore, the support bearing (51) is supported by the case (3) from the outside (R2) in the radial direction (R) and the first axial side (L1), and the rotation sensor (2) is arranged between the rotor (10) and the support bearing (51) in the axial direction (L). Furthermore, even if the inner diameter (D1) of the sensor stator (21) is smaller than the outer diameter (D2) of the support bearing (51), it is possible to assemble the support bearing (51) and the rotor shaft (12) to the case (3) while avoiding interference with the sensor stator (21).

[0049] Furthermore, according to this configuration, since the support bearing (51) is biased in the axial direction (L) by the biasing mechanism (4), it is possible to reduce rattle of the rotor (10) and the rotor shaft (12) in the axial direction (L). Furthermore, according to this configuration, since the first support (41) is arranged to contact the support surface (12a) of the rotor shaft (12) from the first axial side (L1), the second support (42) is arranged to contact the inner ring (51b) from the second axial side (L2), and the elastic body (43) is arranged between the first support (41) and the second support (42), it is possible to bias the inner ring (51b) in the axial direction (L) by the elastic body (43) while making the inner diameter (D3) of the elastic body (43) larger than the outer diameter (D4) of the inner ring (51b). This makes it easy to ensure that the diameter of the elastic body (43) is large, and as a result, it is easy to ensure that the elastic force of the elastic body (43) is large enough to properly bias the support bearing (51) in the axial direction (L).

[0050] As described above, according to this configuration, the support bearing (51), which supports the rotor shaft (12) on the first axial side (L1) relative to the rotor (10), is supported by the case (3) from the outer side (R2) in the radial direction (R) and the first axial side (L1), and the rotation sensor (2) is arranged between the rotor (10) and the support bearing (51) in the axial direction (L). Furthermore, even if the inner diameter (D1) of the sensor stator (21) is smaller than the outer diameter (D2) of the support bearing (51), it is possible to assemble the support bearing (51) and the rotor shaft (12) to the case (3) and to appropriately bias the support bearing (51).

[0051] Here, it is preferable that the linear expansion coefficient of the material constituting the case side support portion (30) is larger than the linear expansion coefficient of the material constituting the outer ring (51 a), and that the fitting gap in the radial direction (R) between the outer ring (51 a) and the case side support portion (30) is smaller than the fitting gap in the radial direction (R) between the inner ring (51 b) and the rotor shaft (12).

[0052] According to this configuration, the fit gap between the outer ring (51 a) and the case support portion (30) in the radial direction (R) is smaller than the fit gap between the inner ring (51 b) and the rotor shaft (12) in the radial direction (R). Therefore, even when the linear expansion coefficient of the material constituting the case support portion (30) is larger than the linear expansion coefficient of the material constituting the outer ring (51 a), such as when the case (3) is made of aluminum and the outer ring (51 a) is made of iron, the gap between the case support portion (30) and the outer ring (51 a) in the radial direction (R) is unlikely to become large. Therefore, even when the case (3) becomes hot, the gap between the case support portion (30) and the support bearing (51) in the radial direction (R) can be kept small. As a result, rattle of the rotor (10) and the rotor shaft (12) in the axial direction (L) can be kept small.

[0053] In addition, it is preferable that the biasing mechanism (4) is configured to include a locking mechanism (44) that locks the first support body (41) and the second support body (42) in the axial direction (L) so that the first support body (41) and the second support body (42) do not separate outside a predetermined range.

[0054] According to this configuration, even when the biasing mechanism (4) is not attached to the rotor shaft (12) and the support bearing (51), the first support (41), the second support (42), and the elastic body (43) can be prevented from separating from each other by the axial locking mechanism (44) in the axial direction (L). This facilitates the assembly of the biasing mechanism (4) to the rotor shaft (12) and the support bearing (51).

[0055] Furthermore, it is preferable that the elastic body (43) is a wave washer or a disc spring, and the case side support portion (30) is configured to support at least one of the first support body (41) and the second support body (42) from the outside (R2) in the radial direction (R).

[0056] According to this configuration, the biasing mechanism (4) can be supported at an appropriate position in the radial direction (R) by the case-side support portion (30). Therefore, when assembling the rotor shaft (12) with the biasing mechanism (4) attached to the case-side support portion (30), the assembling work can be easily facilitated.

[0057] It is sufficient for the drive device according to the present disclosure to achieve at least one of the above-described effects. [Explanation of symbols]

[0058] 1: rotating electrical machine, 2: rotation sensor, 3: case, 4: biasing mechanism, 10: rotor, 12: rotor shaft, 12a: support surface, 20: sensor rotor, 21: sensor stator, 30: case side support portion, 41: first support, 42: second support, 43: elastic body, 44: locking mechanism, 51: first bearing (support bearing), 51a: outer ring, 51b: inner ring, 51c: rolling element, 100: driving device, D1: first diameter (inner diameter of sensor stator), D2: second diameter (outer diameter of support bearing), D3: third diameter (inner diameter of elastic body), D4: fourth diameter (outer diameter of inner ring), L: axial direction, L1: first axial side, L2: second axial side, R: radial direction, R2: radial outer side (outer side in the radial direction), X: rotation axis

Claims

1. A drive device comprising: a rotating electric machine having a rotor; a rotor shaft fixed to the rotor so as to rotate integrally with the rotor; a rotation sensor that detects rotation of the rotor; and a case that houses the rotating electric machine and the rotation sensor, a direction along the rotation axis of the rotor shaft is defined as an axial direction, a direction perpendicular to the rotation axis is defined as a radial direction, one side in the axial direction is defined as an axial first side, and the other side in the axial direction is defined as an axial second side, the rotor shaft is rotatably supported on the case via a support bearing on the first axial side of the rotor, the rotation sensor includes a sensor rotor that rotates integrally with the rotor, and a sensor stator that is fixed to the case, and is disposed between the rotor and the support bearing in the axial direction; an inner diameter of the sensor stator is smaller than an outer diameter of the support bearing; the support bearing includes an outer ring, an inner ring, and a rolling element that rolls between the outer ring and the inner ring, the case includes a case-side support portion that supports the outer ring from an outer side in the radial direction and from the first axial side, the inner ring is fitted to an outer peripheral surface of the rotor shaft and is biased toward the first axial side by a biasing mechanism disposed between the inner ring and a support surface of the rotor shaft facing the first axial side, the urging mechanism includes a first support body arranged to contact the support surface from a first side in the axial direction, a second support body arranged to contact the inner ring from a second side in the axial direction without contacting the outer ring, and an elastic body arranged between the first support body and the second support body to urge the first support body and the second support body in a direction to separate them from each other in the axial direction, The inner diameter of the elastic body is larger than the outer diameter of the inner ring.

2. a linear expansion coefficient of a material constituting the case side support portion is greater than a linear expansion coefficient of a material constituting the outer ring, 2. The drive unit according to claim 1, wherein the radial fit gap between the outer ring and the case side support portion is smaller than the radial fit gap between the inner ring and the rotor shaft.

3. 3. The drive device according to claim 1, wherein the biasing mechanism includes a locking mechanism that locks the first support body and the second support body in the axial direction so that the first support body and the second support body do not separate outside a predetermined range.

4. the elastic body is a wave washer or a disc spring, The drive device according to claim 1 or 2, wherein the case-side support portion is configured to support at least one of the first support body and the second support body from the outside in the radial direction.

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