JP2015089748A - Cooling structure for motor drive unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sufficient oil flow rate to a motor shaft center without increasing stirring friction caused by scooping up.SOLUTION: A motor shaft cooling mechanism 8 for cooling a motor shaft 31 by using oil scooped up by an output gear 42 is arranged in an in-wheel motor drive unit A. The motor shaft cooling mechanism 8 includes: a motor shaft center oil passage 81 in which an oil inlet 81a and an oil outlet are opened at positions adjacent to each other on an input gear 41 side of the motor shaft 31; a supply oil passage structure 82 for supplying oil scooped up by the output gear 42 to the oil inlet 81a; an oil guide 83 for receiving oil from the oil outlet; an oil scooping up structure 84 for scooping up oil from the oil guide 83; and a resupply oil passage structure for supplying again the scooped-up oil to the oil inlet 81a.

Description

  The present invention relates to a cooling structure for a motor drive unit provided with a motor shaft cooling structure for supplying oil scraped up by an output gear to a motor shaft.

  2. Description of the Related Art Conventionally, there is known a rotor bearing lubrication structure for an electric motor that is configured to supply oil to a motor shaft center by raising the oil at the lower part of the unit to the gear shaft (see, for example, Patent Document 1).

JP 2001-190042 A

  However, in the conventional rotor bearing lubrication structure, there is a problem that a sufficient oil flow rate cannot be supplied to the motor shaft center because the oil at the lower part of the unit is merely scraped up by the gear. Further, when the oil flow rate is increased, there is a problem that the stirring friction due to the gear scraping increases.

  The present invention has been made paying attention to the above problem, and provides a cooling structure for a motor drive unit that can supply a sufficient oil flow rate to a motor shaft without increasing stirring friction due to scraping. With the goal.

In order to achieve the above object, the present invention meshes with a motor having a motor shaft, an input gear provided at an end of the motor shaft of the motor, and the input gear inside a unit case supported by the vehicle body. An output gear, and a tire shaft provided coaxially with the output gear.
The motor shaft center line of the motor shaft is offset from the tire shaft center line of the tire shaft above the vehicle, and a parallel shaft gear pair is configured by the input gear and the output gear.
In this motor drive unit, the output gear is arranged so as to be partially immersed in oil in an oil tank formed below the tire axis center line in the unit case, and the oil that is scraped up by the output gear A motor shaft cooling structure for cooling the motor shaft is provided.
The motor shaft cooling structure supplies a motor shaft center oil passage having an oil inlet and an oil outlet at adjacent positions on the input gear side of the motor shaft, and oil scraped up by the output gear to the oil inlet. A supply oil passage structure, an oil guide for receiving oil from the oil outlet, an oil scooping mechanism for scooping up the oil from the oil guide, and a resupply oil passage for supplying the scooped up oil to the oil inlet again And having a structure.

Therefore, the oil scraped up by the rotating output gear is supplied to the oil inlet of the motor shaft oil passage through the supply oil passage structure. Then, the oil discharged from the oil outlet of the motor shaft oil passage is received by the oil guide and supplied again to the oil inlet of the motor shaft oil passage through the oil scooping mechanism and the resupply oil passage structure.
In other words, the oil discharged from the oil outlet of the motor shaft oil passage can be received by the oil guide before falling into the oil tank below the unit, and supplied again to the motor shaft oil passage. For this reason, the oil flow rate supplied to the motor shaft center oil passage becomes a total flow rate obtained by adding the oil flow rate by re-supply to the oil flow rate scraped by the output gear, and the oil flow rate by re-supply can be increased. In addition, when securing a sufficient oil flow rate, the output gear agitation friction due to the scooping resistance is not increased because the oil flow rate does not depend on the output gear.
As a result, a sufficient oil flow rate can be supplied to the motor shaft without increasing the stirring friction due to the scraping.

It is a whole sectional view showing an in-wheel motor drive unit provided with a motor shaft cooling structure of Example 1. FIG. 3 is an enlarged cross-sectional view of a main part illustrating a motor shaft cooling structure according to Embodiment 1. FIG. 4 is a longitudinal sectional perspective view showing an oil guide and an input gear in the motor shaft cooling structure according to the first embodiment. It is a perspective view which shows the relationship between the rotation direction of the input gear in the motor shaft cooling structure of Example 1, and the twist direction of a gear tooth. FIG. 3 is a longitudinal sectional view of an oil guide portion illustrating a flow of oil in a radial oil passage (oil output) and an oil guide in the motor shaft cooling structure according to the first embodiment. It is a perspective view which shows the positional relationship of two catchers by the reduction gear case, a parallel shaft gear pair, and the reduction gear case side in the motor shaft cooling structure of Example 1. FIG. It is a perspective view which shows the motor shaft cooling structure of Example 1 provided in the reduction gear case. It is a partially cutaway perspective view showing a motor shaft cooling structure of Example 1 provided in a reduction gear case and a motor case. It is a perspective view which shows the motor shaft cooling structure of Example 1 seen from the angle different from FIG. It is a perspective view which shows the motor shaft cooling structure of Example 1 seen from the angle different from FIG.8 and FIG.9. It is a principal part expanded sectional view which shows the motor shaft cooling structure of Example 2. FIG. FIG. 6 is a perspective view (a) viewed from the motor side and an oblique view (b) viewed from the input gear side showing the oil guide in the motor shaft cooling structure of the second embodiment. FIG. 6 is a cross-sectional view illustrating a second oil tank in a motor shaft cooling structure according to a third embodiment. FIG. 10 is an operation explanatory diagram illustrating an oil flow in a second oil tank in the motor shaft cooling structure according to the third embodiment. It is a perspective view which shows the oil guide of the motor shaft cooling structure of Example 4. FIG. 10 is a longitudinal sectional view of an oil guide portion showing a flow of oil in a radial oil passage (oil output) and an oil guide in a motor shaft cooling structure of a fourth embodiment. It is a perspective view which shows other examples other than Examples 1-4 about the oil guide in a motor shaft cooling structure.

  Hereinafter, the best mode for realizing the cooling structure of the motor drive unit of the present invention will be described based on Examples 1 to 4 shown in the drawings.

First, the configuration will be described.
The configuration of the in-wheel motor drive unit provided with the motor shaft cooling structure according to the first embodiment will be described separately for [the entire configuration of the in-wheel motor drive unit] and [the detailed configuration of the motor shaft cooling structure].

[Overall configuration of in-wheel motor drive unit]
FIG. 1 shows an in-wheel motor drive unit A having the motor shaft cooling structure of the first embodiment. Hereinafter, based on FIG. 1, the whole structure of the in-wheel motor drive unit A is demonstrated.

  As shown in FIG. 1, the in-wheel motor drive unit A includes a unit case 1, a motor control unit 2, a motor / generator 3, a parallel shaft gear pair 4, a reduction planetary gear 5, and a tire shaft 6. It is equipped with. The motor shaft center line CLm of the motor shaft 31 of the motor / generator 3 by natural air cooling is offset from the tire shaft center line CLt of the tire shaft 6 above the vehicle (arrow UP in FIG. 1).

  The unit case 1 is supported via a knuckle arm 71 so as to be steerable with respect to a vehicle body not shown. This unit case 1 is configured by bolting a control unit cover 11, a control unit case 12, a partition wall case 13, a motor case 14, and a speed reducer case 15. In the unit case 1, air cooling fins 11 a, 12 a, and 14 a that are cooled by running air are provided on the outer peripheral surfaces of the control unit cover 11, the control unit case 12, and the motor case 14. The knuckle arm 71 is fixed to the speed reducer case 15, and a lower arm is connected to the lower end of the knuckle arm 71, an upper arm is connected to the upper end of the knuckle arm 71. 1 is supported. The internal chamber of the unit case 1 is defined by a control unit chamber 16, a motor chamber 17, and a gear chamber 18.

  The motor control unit 2 is set in a control unit chamber 16 (dry space) surrounded by a control unit cover 11, a control unit case 12 and a partition wall case 13. The motor control unit 2 includes control devices that control the motor / generator 3 such as a motor controller, an inverter, and a converter. The control unit chamber 16 in which the motor control unit 2 is set is naturally air-cooled by the air-cooling fins 11 a and 12 a and is disposed adjacent to the motor chamber 17 via the partition wall case 13.

  The motor / generator 3 is set in a motor chamber 17 (dry space) surrounded by a partition wall case 13 and a motor case 14. The motor / generator 3 includes a motor shaft 31, a rotor 32, a stator 33, and a stator coil 34. The motor shaft 31 is rotatably supported with respect to the partition wall case 13 and the motor case 14 by bearings 35 and 36. The rotor 32 is fixed to the outer periphery of the motor shaft 31 and is constituted by a laminated steel plate in which a permanent magnet is embedded. The stator 33 is fixed to the motor case 14, is disposed through the rotor 32 and an air gap, and includes a laminated stator tooth around which the stator coil 34 is wound. That is, the motor shaft 31 is rotated by applying a three-phase alternating current to the stator coil 34 (power running), or the three-phase alternating current is generated in the stator coil 34 by the rotation of the motor shaft 31 (regeneration). A resolver 37 for detecting the motor rotation angle is provided at the end position of the motor shaft 31 on the motor control unit 2 side.

  The parallel shaft gear pair 4 is set at a position of a bolt connecting portion between the motor case 14 and the speed reducer case 15 in a gear chamber 18 (wet space) surrounded by a part of the motor case 14 and the speed reducer case 15. The The parallel shaft gear pair 4 includes an input gear 41 formed at the end of the motor shaft 31, an output gear 42 that meshes with the input gear 41 and has a larger diameter than the input gear 41, and an output gear 42 that integrally includes the output gear 42. A reduction gear having a gear shaft 43. The output gear 42 is disposed so as to be partially immersed in oil in an oil tank 44 formed at a position below the tire axis center line CLt in the unit case 1. The output gear shaft 43 is rotatably supported at the motor side shaft end portion via the bearing 45 with respect to the motor case 14, and the wheel side shaft end portion is rotatably supported at the tire shaft 6 via the bearing 46. . The output gear shaft 43 is formed with a through-shaft oil passage 47 at the axial center position.

  The reduction planetary gear 5 is set at a position on the reduction gear case 15 side adjacent to the parallel shaft gear pair 4 in a gear chamber 18 (wet space) surrounded by a part of the motor case 14 and the reduction gear case 15. The The reduction planetary gear 5 is engaged with the sun gear 51 integrated with the output gear shaft 43, a plurality of pinions 52 that mesh with the sun gear 51, a pinion carrier 53 that supports the pinion 52, and meshes with the pinion 52 and is fixed to the speed reducer case 15. Ring gear 54. That is, it is a reduction gear mechanism that decelerates the input rotation from the sun gear 51 and outputs it to the pinion carrier 53 by fixing the ring gear 54 to the case. The rotation center axis of the reduction planetary gear 5 is coaxial with the output gear 42 and the rotation center axis of the tire shaft 6 (tire axis center line CLt).

  The tire shaft 6 is a unit output shaft that is formed integrally with the pinion carrier 53 of the reduction planetary gear 5 and has a shaft end projecting from the reduction gear case 15 to the outside (OUT). One end portion of the tire shaft 6 on the reduction planetary gear 5 side is rotatably supported in an oil-tight state by a bearing 61 and a mechanical seal 62 with respect to the reduction gear case 15. A wheel hub shaft 72 is serrated to the other end of the tire shaft 6 that protrudes to the outside. The wheel hub shaft 72 is rotatably supported by a hub bearing 74 having a double-row angular bearing structure with respect to a knuckle case 73 bolted to the knuckle 71. A brake disc and a tire wheel (not shown) are fixed to the flange portion 72 a of the wheel hub shaft 72.

[Detailed configuration of motor shaft cooling structure]
FIG. 2 shows the motor shaft cooling structure 8 of the first embodiment, and FIGS. 3 to 10 show components of the motor shaft cooling structure 8 of the first embodiment. Hereinafter, based on FIGS. 2-10, the detailed structure of the motor shaft cooling structure 8 is demonstrated.

  In the motor shaft cooling structure 8, the output gear 42 is partly immersed in the oil in an oil tank 44 formed below the tire axis center line CLt in the unit case 1, and is scraped up by the output gear 42. The structure is such that the motor shaft 31 is cooled by the oil thus produced (FIG. 1). 2 to 10, the motor shaft cooling structure 8 includes a motor shaft center oil passage 81, a supply oil passage structure 82, an oil guide 83, an oil scooping mechanism 84, and a resupply oil passage structure. 85.

  The motor shaft oil passage 81 is an oil passage that cools the motor shaft 31 with an oil flow rate, and includes an oil inlet 81a, an inner shaft oil passage 81b, an outer shaft oil passage 81c, and an oil outlet 81d. Have.

  As shown in FIG. 2, the oil inlet 81a is a hole that guides oil to the inner shaft oil passage 81b, and is an oil passage portion at the end of the motor shaft of the inner shaft oil passage 81b formed in the axial direction. . 2 and 8, the oil inlet 81a is formed in a cylindrical shape at a position facing the motor shaft end face of the speed reducer case 15, and protrudes from the motor shaft end face to a position overlapping with the oil inlet 81a. An oil inlet cylinder 81g is arranged.

  The inner shaft oil passage 81b allows oil flowing in from the oil inlet 81a to pass through the bottom of the rotor 32 in the direction of arrow B in FIG. 2 along the bottomed shaft hole 81e formed in the motor shaft 31. It is an oil passage that flows up to.

  The outer shaft center oil passage 81c causes the oil that makes a U-turn from the bottom of the bottomed shaft center hole 81e to flow along the outer side of the inner shaft center oil passage 81b in the direction of arrow C (the direction opposite to the direction of arrow B). This is an oil passage returning toward the input gear 41. That is, by fixing the concentric cylindrical partition wall 81f having an outer diameter smaller than the inner diameter of the bottomed shaft center hole 81e to the bottomed shaft center hole 81e formed in the rotor shaft 31, the inner surface side of the concentric cylindrical partition wall 81f is set to the inner side. An axial gap formed in the outer side of the concentric cylindrical partition wall 81f is defined as an outer axis oil path 81c.

  The oil outlet 81d is a hole formed in a plurality of radial directions so as to communicate the outer shaft center oil passage 81c and the tooth bottom of the input gear 41. The oil that has passed through the outer shaft center oil passage 81c is shown in FIG. Is discharged in the direction of arrow D (radial direction). The oil outlet 81d and the oil inlet 81a are opened at adjacent positions on the input gear 41 side of the motor shaft 31.

  The supply oil passage structure 82 is an oil passage structure that supplies the oil scraped up by the output gear 42 to the oil inlet 81a. As shown in FIGS. 6 to 8, the supply oil passage structure 82 is received by the first catcher 82a and the first catcher 82a that receive the oil (in the direction of arrow H in FIG. 6) scraped up by the output gear 42. And a first oil passage 82b for guiding the oil to the oil inlet 81a. The first catcher 82a and the first oil passage 82b are integrally formed with the speed reducer case 15.

  The oil guide 83 is a guide member that receives oil discharged from the oil outlet 81d and guides it to the oil scooping mechanism 84, and includes a base plate 83a and a guide plate 83b. As shown in FIGS. 2 to 5, the base plate 83 a is fixed to the motor case 14 and extends to a seal groove 83 c formed in the motor shaft 31. The guide plate 83b protrudes in the axial direction from the middle of the base plate 83a to the input gear 41 side, and is bent in the radial direction so that the end portion is close to the tooth crest of the input gear 41 (an arrow F in FIG. The gap between the guide 83 and the input gear 41 is shown.) As shown in FIG. 5, the oil guide 83 covers about 3/4 of the entire circumference of the input gear 41 so as to receive the oil scooped up by the oil scooping mechanism 84. In order to guide oil toward 85 in the direction of arrow G in FIG.

  The oil scooping mechanism 84 is a mechanism for scooping up oil from the oil guide 83. As shown in FIG. 2, the oil scooping mechanism 84 makes the tooth width W of the input gear 41 wider than the tooth width w of the output gear 42, and extends the driving force transmission portion due to the engagement between the input gear 41 and the output gear 42. The input gear tooth extension portion. 3 and 4, when viewed from the gear side toward the motor / generator 3 side (arrow L direction), the input gear 41 is closer to the motor / generator 3 side than the input gear rotation direction. The torsion direction of the gear teeth is set so that the tooth groove is delayed from the rotation direction.

  The resupply oil passage structure 85 is an oil passage structure that supplies the oil scraped up by the oil scooping mechanism 84 to the oil inlet 81a again. As shown in FIGS. 8 to 10, the resupply oil passage structure 85 includes second catcher portions 85 a and 85 b and a second oil passage 85 c. The second catchers 85 a and 85 b receive the oil that has been scraped up by the oil scraping mechanism 84. As shown by an arrow E in FIG. 2, the second oil passage 85c guides the oil received by the second catcher portions 85a and 85b to the oil inlet 81a. Here, the second catcher portion 85 a and the second oil passage 85 c are formed integrally with the reduction gear case 15, and the second catcher portion 85 b is formed integrally with the motor case 14. And the 2nd catcher part 85a and the 2nd catcher part 85b comprise the 2nd oil tank 48 used as the oil sump separately from the oil tank 44 of the unit lower part by aligning an end face mutually in a case assembly state. .

Next, the operation will be described.
First, the motor / generator 3 according to the first embodiment is naturally air-cooled, and the speed reduction mechanism using the parallel shaft gear pair 4 and the reduction planetary gear 5 is oil-up lubrication. Thus, when the motor / generator 3 is an air-cooled motor, the temperature of the rotor 32 is likely to rise during high rotation, and it is necessary to flow oil through the motor shaft to promote cooling. Hereinafter, the motor shaft cooling action by the motor shaft cooling structure 8 will be described.

  The oil accumulated in the oil tank 44 at the lower part of the speed reducer case 15 is scraped up with the rotation of the output gear 42 arranged on the tire axis center line CLt, as indicated by an arrow H in FIG. The oil scooped up at the top is received and collected by a first catcher 82a provided in the vicinity of the motor shaft center line CLm, and guided to the oil inlet 81a through the first oil passage 82b. And the oil which flows in from the oil inlet 81a flows into the hole bottom part of the bottomed axial center hole 81e through the inner side axial center oil path 81b in the arrow B direction of FIG. Further, the oil that makes a U-turn from the bottom position of the bottomed shaft center hole 81e is returned to the input gear 41 side through the outer shaft center oil passage 81c in the direction of arrow C in FIG. The motor shaft 31 can be cooled by the flow of oil passing through the inner shaft oil passage 81b and the outer shaft oil passage 81c formed in the motor shaft 31.

  At this time, the oil discharged in the radial direction (in the direction of arrow D in FIG. 2) through the oil outlet 81d normally returns to the oil tank 44 below the reducer, but is discharged from the oil outlet 81d by the oil guide 83. Part of the oil is received and guided to the oil scooping mechanism 84. The oil scooped up by the oil scooping mechanism 84 (the gear tooth extension portion of the input gear 41) is received by the second catcher portions 85a and 85b that constitute the second oil tank. Then, the oil that is received by the second catchers 85a and 85b (second oil tank 48) and temporarily stays in the second oil tank 48 passes through the second oil passage 85c as shown by an arrow E in FIG. It is supplied again to the oil inlet 81a.

  That is, the oil scraped up by the output gear 42 guided through the first oil passage 82b and the re-supply oil guided through the second oil passage 85c merged at the position of the oil inlet 81a. The oil is repeatedly returned to the input gear 41 side through the inner axial oil passage 81b in the arrow B direction in FIG. 2 and then through the outer axial oil passage 81c in the arrow C direction in FIG. For this reason, the oil flow rate for cooling the motor shaft 31 through the inner shaft oil passage 81b and the outer shaft oil passage 81c is added to the scraping flow rate by the output gear 42 and the return flow rate from the second oil passage 85c. The motor shaft 31 can be cooled more effectively.

As described above, in the first embodiment, the oil scraped up by the rotating output gear 42 is supplied to the oil inlet 81 a of the motor shaft oil passage 81 through the supply oil passage structure 82. Then, the oil discharged from the oil outlet 81d of the motor shaft oil passage 81 is received by the oil guide 83, and the oil inlet 81a of the motor shaft oil passage 81 is received via the oil scooping mechanism 84 and the resupply oil passage structure 85. It was set as the structure supplied again.
That is, the oil discharged from the oil outlet 81d of the motor shaft oil passage 81 can be received by the oil guide 83 before falling into the oil tank 44 below the unit, and can be supplied again to the motor shaft oil passage 81. For this reason, the oil flow rate supplied to the motor shaft oil passage 81 is the sum of the oil flow rate picked up by the output gear 42 and the oil flow rate due to resupply, and the oil flow rate due to resupply may be increased. it can. Further, when a sufficient oil flow rate is ensured, the stirring friction of the output gear 42 due to the scraping resistance is not increased because the oil flow rate does not depend on the output gear 42.
As a result, a sufficient oil flow rate can be supplied to the motor shaft center of the motor shaft 31 without increasing the stirring friction due to the scraping, and the cooling of the rotor 32 whose temperature rises at the time of high rotation can be promoted. .

In the first embodiment, the oil scraping mechanism 84 has an input gear 41 in which the tooth width W of the input gear 41 is made wider than the tooth width w of the output gear 42 and the driving force transmission portion by the engagement of the input gear 41 and the output gear 42 is extended. It consisted of a tooth extension part.
That is, no new additional parts are required as the oil scooping mechanism 84. For this reason, an increase in cost due to an increase in the number of parts can be suppressed.

In the first embodiment, when the input gear 41 is viewed from the gear side to the motor / generator 3 side, the tooth groove is delayed from the rotation direction as it goes to the motor / generator 3 side with respect to the input gear rotation direction. Thus, it was set as the structure which sets the twist direction of a gear tooth.
For example, when the input gear 41 is rotating clockwise as viewed from the shaft end side, the input gear 41 is left-twisted so that oil is pushed in the direction opposite to the shaft end. The amount of oil leakage from the tooth gap portion between 41 is reduced.
Therefore, the recovery rate of the oil discharged from the oil outlet 81d by the oil guide 83 can be improved.

In the first embodiment, the resupply oil passage structure 85 from the oil outlet 81d to the oil inlet 81a of the motor shaft center oil passage 61 is provided with the second oil tank 44 separately from the oil tank 44 formed below the tire axis center line CLt. An oil tank 48 is provided.
For example, when the resupply oil path structure 85 is an oil path structure that returns from the oil outlet 81d to the oil inlet 81a, the oil that has been warmed through the motor shaft oil path 61 is resupplied as it is. On the other hand, since the second oil tank 48 functions as a cooling unit for the oil that has been warmed through the motor shaft oil passage 61, when the oil flows again into the motor shaft oil passage 61, a cooler oil is supplied. Can do.
Therefore, the motor shaft 31 can be cooled more effectively by providing the second oil tank 48 that functions as an oil cooling section.

Next, the effect will be described.
In the cooling structure of the in-wheel motor drive unit A of the first embodiment, the effects listed below can be obtained.

(1) A motor (motor / generator 3) having a motor shaft 31 in the unit case 1 supported by the vehicle body, and an input gear provided at an end of the motor shaft 31 of the motor (motor / generator 3). 41, an output gear 42 meshing with the input gear 41, and a tire shaft 6 provided coaxially with the output gear 42,
The motor shaft center line CLm of the motor shaft 31 is offset from the tire shaft center line CLt of the tire shaft 6 above the vehicle, and the input gear 41 and the output gear 42 constitute a parallel shaft gear pair 4. In the motor drive unit (in-wheel motor drive unit A),
The output gear 42 is partially immersed in oil in an oil tank 44 formed at a position below the tire axis center line CLt in the unit case 1, and the oil swept up by the output gear 42 is used. A motor shaft cooling structure 8 for cooling the motor shaft 31 is provided;
The motor shaft cooling structure 8 includes a motor shaft center oil passage 81 having an oil inlet 81a and an oil outlet 82d opened at adjacent positions on the input gear 41 side of the motor shaft 31, and oil scraped up by the output gear 42. Oil supply structure 82 for supplying oil to the oil inlet 81a, an oil guide 83 for receiving oil from the oil outlet 82d, an oil scooping mechanism 84 for scooping up the oil from the oil guide 83, and the oil guide 83 A re-supply oil passage structure 85 for supplying oil to the oil inlet 81a again (FIG. 2).
For this reason, it is possible to supply a sufficient oil flow rate to the motor shaft without increasing the stirring friction due to the scraping.

(2) The oil scraping mechanism 84 has a tooth width W of the input gear 41 wider than a tooth width w of the output gear 42, and extends a driving force transmission portion due to the meshing of the input gear 41 and the output gear 42. The input gear teeth are extended (FIG. 2).
For this reason, in addition to the effect of (1), a new additional part becomes unnecessary as the oil scraping mechanism 84, and an increase in cost due to an increase in the number of parts can be suppressed.

(3) When the input gear 41 is viewed from the gear side toward the motor side (motor / generator 3 side), the tooth gap increases toward the motor side (motor / generator 3 side) with respect to the input gear rotation direction. The direction of twisting of the gear teeth was set so that is in a direction delayed from the rotation direction (FIG. 3).
For this reason, in addition to the effect of (2), the recovery rate of the oil discharged from the oil outlet 81d by the oil guide 83 can be improved.

(4) The second oil is separated from the oil tank 44 formed below the tire axis center line CLt between the oil outlet 81d and the oil inlet 81a of the motor shaft oil passage 81. A tank (second oil tank 48) was provided (FIGS. 8 to 10).
For this reason, in addition to the effects (1) to (3), the second oil tank (second oil tank 48) that temporarily stores oil functions as an oil cooling unit, so that the motor shaft 31 is more effectively used. Can be cooled.

  The second embodiment is an example in which the oil guide 83 is provided with an oil seal function, and the amount of oil leakage from the input gear tooth extension portion which is the oil scraping mechanism 84 is reduced.

First, the configuration will be described.
FIG. 11 shows the motor shaft cooling structure 8 of the second embodiment, and FIG. 12 shows an oil guide in the motor shaft cooling structure 8 of the second embodiment. Hereinafter, based on FIG.11 and FIG.12, the detailed structure of the motor shaft cooling structure 8 of Example 2 is demonstrated.

  As shown in FIG. 11, the motor shaft cooling structure 8 includes a motor shaft center oil passage 81, a supply oil passage structure 82, an oil guide 83, an oil scooping mechanism 84, a resupply oil passage structure 85, Have

  As shown in FIG. 11, the oil guide 83 includes a base plate 83a, a guide plate 83b extending from the base plate 83a to the input gear 41 side, a seal plate 83d extending from the base plate 83a to the motor / generator 3 side, Have The base plate 83a is fixed to the motor case 14 and extends to a position close to the surface of the motor shaft 31 (gap indicated by an arrow I in FIG. 11). The guide plate 83 b protrudes in the axial direction from the middle of the base plate 83 a toward the input gear 41, and is bent in the radial direction so that the end thereof is close to the tooth crest of the input gear 41. As shown in FIGS. 11 and 12, the seal plate 83d protrudes in the axial direction from the middle of the base plate 83a toward the motor / generator 3, and is bent in the radial direction so that the end portion is close to the surface of the motor shaft 31. ing. Here, on the surface of the motor shaft 31 between the guide plate 83b and the seal plate 83d, a protrusion 83e protruding in the radial direction is formed, and the labyrinth seal structure is formed by the guide plate 83b, the seal plate 83d, and the protrusion 83e. Is formed. The base plate 83a and the seal plate 83d are formed in an annular shape that is continuous over the entire circumference. The guide plate 83b covers about 3/4 of the entire circumference of the input gear 41 and opens about 1/4 of the circumference.

As shown in FIG. 11, the oil scooping mechanism 84 is composed of an input gear tooth extension portion obtained by extending a driving force transmission portion by meshing between the input gear 41 and the output gear 42, and on the motor / generator 3 side. The shape is set such that the depth of the tooth gap becomes shallower. Here, the setting of the twist direction of the gear teeth of the input gear 41 is the same as in the first embodiment.
Since other configurations are the same as those of the first embodiment, illustration and description thereof are omitted.

Next, the operation will be described.
In the second embodiment, the oil scraping mechanism 84 constituted by the input gear tooth extension portion is set to a shape in which the depth of the tooth gap becomes shallower toward the motor / generator 3 side.
That is, since the oil in the tooth gap can be pushed out in the radial direction by using the cut-up of the input gear 41 (the portion cut by the tool at the time of gear manufacture), the gap between the oil guide 83 and the gear shaft (= motor shaft 31) The amount of oil leakage can be suppressed.

  Further, when hobbing the input gear 41 (hobbing is the most common and the production cost is low), it is necessary to secure a space for the raised portion, but by forming the scraping mechanism 84 at that portion, The space required for rounding up can be used efficiently. That is, it is not necessary to provide a new space for the scraping mechanism 84.

In the second embodiment, the oil guide 83 has a seal plate 83d extending from the base plate 83a to the motor / generator 3 side.
That is, since the oil guide 83 having a function of receiving oil also functions as a labyrinth oil seal, an oil seal between the input gear 41 and the motor / generator 3 becomes unnecessary, and the number of parts and seal space can be reduced. Since other operations are the same as those of the first embodiment, description thereof is omitted.

Next, the effect will be described.
In the cooling structure of the in-wheel motor drive unit according to the second embodiment, the following effects can be obtained.

(5) The input gear tooth extension portion of the input gear 41 is set to have a shape in which the depth of the tooth groove becomes shallower toward the motor side (motor / generator 3 side) (FIG. 11).
For this reason, in addition to the effects of (1) to (4), it is possible to perform oil scooping using the necessary space effectively and reduce the amount of oil leakage from the gap between the oil guide 83 and the motor shaft 31. Can do.

(6) The oil guide 83 includes a base plate 83a, a guide plate 83b extending from the base plate 83a toward the input gear 41, and a seal plate 83d extending from the base plate 83a toward the motor / generator 3 ( 11 and 12).
For this reason, in addition to the effects (1) to (5), the oil guide 83 is added with a function as an oil seal, so that an oil seal between the input gear 41 and the motor (motor / generator 3) becomes unnecessary. The score can be reduced.

  Example 3 is an example in which the structure of the second oil tank is improved.

First, the configuration will be described.
FIG. 13 shows a second oil tank 48 ′ in the motor shaft cooling structure 8 of the third embodiment. Hereinafter, based on FIG. 13, the detailed structure of the motor shaft cooling structure 8 of Example 3 is demonstrated.

  The motor shaft cooling structure 8 has a motor shaft oil passage 81, a supply oil passage structure 82, an oil guide 83, an oil scooping mechanism 84, and a resupply oil passage structure 85.

As shown in FIG. 13, the resupply oil passage structure 85 includes a second catcher portion 85a formed in the reduction gear case 15, a second catcher portion 85b formed in the motor case 14, and a second oil passage 85c. And is configured. The second oil tank 48 ′ is configured by aligning the end surfaces with each other in the case assembled state of the second catcher portion 85a and the second catcher portion 85b. As shown in FIG. 13, the second catcher portion 85b constituting the second oil tank 48 'sets the height of the oil inflow portion to a position lower than the motor shaft center line CLm. A through hole 48a connected to the oil tank 44 formed at a position below the tire axis center line CLt is provided at the lower portion of the second catcher portion 85a constituting the second oil tank 48 ′.
Since other configurations are the same as those in the first embodiment or the second embodiment, illustration and description thereof are omitted.

Next, the operation will be described.
FIG. 14 shows an oil flow in the second oil tank 48 ′ in the motor shaft cooling structure 8 of the third embodiment. The oil scooped up by the oil scooping mechanism 84 flows into the second catcher portion 85b in which the height of the oil inflow portion is set at a position lower than the motor axis center line CLm, as shown by the arrow in FIG. The oil that has flowed in is provided with a slope along the speed reducer case 15 side from the oil inflow portion so that the oil tends to accumulate on the second catcher portion 85a side. The oil accumulated in the second oil tank 48 ′ is guided to the second oil path 85c using vibration from the road surface.

  That is, since the in-wheel motor drive unit is mounted under the spring, it is easy for road surface vibration to occur, and therefore the oil also moves up and down. The oil can be lifted up to the second oil passage 85c by effectively utilizing the feature of the in-wheel motor drive unit mounted under the spring. Thereby, since the momentum of the oil by the oil scooping mechanism 84 can be reduced, stirring friction can be reduced. In addition, by adding a slope, the oil in the second oil tank 48 ′ is easy to flow and the oil cooling property is improved.

Thus, in Example 3, the height of the oil inflow portion of the second oil tank 48 ′ is set to a position lower than the motor shaft center line CLm.
Therefore, since the amount of oil splashed by the oil scooping mechanism 84 can be kept small, the stirring friction by the oil scooping mechanism 84 can be reduced. In addition, since the amount of oil flowing into the second oil tank 48 ′ increases and the oil in the second oil tank 48 ′ becomes easy to circulate, the cooling performance of the oil in the second oil tank 48 ′ can be further improved. it can.

In the third embodiment, the second oil tank 48 ′ is provided with a through port 48a connected to the oil tank 44 formed at a position below the tire axis center line CLt.
That is, the motor shaft 31 is likely to generate heat at a high vehicle speed (because the motor / generator 3 is at a high rotation speed), and it is not necessary to cool the motor shaft center at a low vehicle speed or when stopped. Therefore, it is not necessary to store oil in the second oil tank 48 ′ at a low vehicle speed or when stopped. This makes it easy to manage the oil level because only the oil level of the oil tank 44 needs to be managed when the oil is sucked when the unit is shipped or when the oil is changed.
As described above, during the stop of the vehicle where there is no oil inflow from the oil scooping mechanism 84, the oil is discharged from the through port 48a to the oil tank 44. For this reason, the oil level of the oil tank 44 can be easily managed when the oil is changed. Since other operations are the same as those of the first embodiment or the second embodiment, the description thereof is omitted.

Next, the effect will be described.
In the cooling structure of the in-wheel motor drive unit according to the third embodiment, the following effects can be obtained.

(7) In the second oil tank (second oil tank 48 ′), the height of the oil inflow portion into the tank is set at a position lower than the motor shaft center line CLm (FIG. 13).
For this reason, in addition to the effect (4) of the first embodiment, it is possible to reduce the stirring friction by the oil scooping mechanism 84 and to cool the oil in the second oil tank (second oil tank 48 ′). Can be further improved.

(8) A through port 48a connected to the oil tank 44 formed at a position below the tire axis center line CLt is provided in the lower portion of the second oil tank (second oil tank 48 ′) (FIG. 13).
For this reason, in addition to the effect of (7), the oil level of the oil tank 44 can be easily managed at the time of oil exchange or the like.

  The fourth embodiment is an example in which the structure of the oil guide 83 is improved.

First, the configuration will be described.
FIG. 15 shows an oil guide 83 of the motor shaft cooling structure 8 according to the fourth embodiment. Hereinafter, based on FIG. 15, the detailed structure of the motor shaft cooling structure 8 of Example 4 is demonstrated.

  The motor shaft cooling structure 8 has a motor shaft oil passage 81, a supply oil passage structure 82, an oil guide 83, an oil scooping mechanism 84, and a resupply oil passage structure 85.

As shown in FIG. 15, the oil guide 83 includes a base plate 83a and a guide plate 83b extending from the base plate 83a to the input gear 41 side. The guide plate 83b sets a gap amount with the input gear 41 to be wide on the inlet side in the rotational direction and narrow on the outlet side in the rotational direction.
Since other configurations are the same as those of the first embodiment, the second embodiment, or the third embodiment, illustration and description thereof are omitted.

Next, the operation will be described.
FIG. 16 shows the oil flow in the radial oil passage (oil output) and the oil guide 83 in the motor shaft cooling structure 8 of the fourth embodiment. When the input gear 41 rotates, the oil is mainly scooped up at a portion where the gap amount is narrow on the outlet side in the rotation direction, and the oil is difficult to scoop up at a portion where the gap amount is wide on the inlet side in the rotation direction. For this reason, stirring friction in the oil scooping mechanism 84 can be minimized.

  That is, the oil ejected in the radial direction from the oil outlet 81 d hits the oil guide 83. In the upper part of the oil guide 83 (the inlet side in the rotation direction), the oil is guided to the lower part along the guide plate 83b of the oil guide 83. On the outlet side in the rotational direction from the lower part, the amount of gap with the guide plate 83b is narrowed so that the oil is scraped up. Thereby, since it scrapes up only by the minimum necessary part, stirring friction can be reduced. In addition, since another effect | action is the same as that of Example 1, Example 2, or Example 3, description is abbreviate | omitted.

Next, the effect will be described.
In the cooling structure of the in-wheel motor drive unit according to the fourth embodiment, the following effects can be obtained.

(9) The gap between the oil guide 83 and the input gear 41 is set wide on the inlet side in the rotational direction and narrow on the outlet side in the rotational direction (FIG. 15).
For this reason, in addition to the effects (1) to (8), the stirring friction in the oil scraping mechanism 84 can be minimized.

  As mentioned above, although the cooling structure of the motor drive unit of this invention has been demonstrated based on Example 1-Example 4, it is not restricted to these Examples about a concrete structure, Each of Claims Design changes and additions are permitted without departing from the scope of the claimed invention.

  In Examples 1-4, the example which uses a plate member as oil guide 83 was shown. However, the oil guide may be an example in which a case wall surface is used for a part of the oil guide.

  In the first to fourth embodiments, an example in which the oil guide 83 is provided in the input gear tooth extension portion obtained by extending the driving force transmission portion by the engagement of the input gear 41 and the output gear 42 has been described. However, as the oil guide, as shown in FIG. 17, in the gear driving force transmission portion, the oil guide is extended to avoid the gear engagement (upper part of the input gear). The oil may be caught by the guide plate 83b ′.

A In-wheel motor drive unit (motor drive unit)
1 Unit case 14 Motor case 15 Reducer case 3 Motor / generator (motor)
31 Motor shaft 4 Parallel shaft gear pair 41 Input gear 42 Output gear 44 Oil tank 48, 48 'Second oil tank (second oil tank)
48a Through-hole 6 Tire shaft 8 Motor shaft cooling structure 81 Motor shaft center oil passage 81a Oil inlet 81d Oil outlet 82 Supply oil passage structure 82a First catcher portion 82b First oil passage 83 Oil guide 83a Base plate 83b Guide plate 83d Seal plate 84 Oil scraping mechanism 85 Re-supply oil passage structure 85a, 85b Second catcher portion 85c Second oil passage
CLm Motor shaft center line
CLt Tire axis center line W Tooth width of input gear 41 Tooth width of output gear 42

Claims (9)

Inside the unit case supported by the vehicle body, a motor having a motor shaft, an input gear provided at an end of the motor shaft of the motor, an output gear meshing with the input gear, and coaxially with the output gear A tire shaft provided,
In the motor drive unit in which the motor shaft center line of the motor shaft is offset from the tire shaft center line of the tire shaft above the vehicle, and a parallel shaft gear pair is configured by the input gear and the output gear.
The output gear is arranged so as to be partially immersed in oil in an oil tank formed below the tire shaft center line in the unit case, and the motor shaft is cooled by the oil scooped up by the output gear. To provide a motor shaft cooling structure
The motor shaft cooling structure supplies a motor shaft center oil passage having an oil inlet and an oil outlet at adjacent positions on the input gear side of the motor shaft, and oil scraped up by the output gear to the oil inlet. A supply oil passage structure, an oil guide for receiving oil from the oil outlet, an oil scooping mechanism for scooping up the oil from the oil guide, and a resupply oil passage for supplying the scooped up oil to the oil inlet again And a structure for cooling the motor drive unit. In the cooling structure of the motor drive unit according to claim 1,
The oil scooping mechanism is configured by an input gear tooth extension portion in which a tooth width of the input gear is wider than a tooth width of the output gear and a driving force transmission portion is extended by meshing of the input gear and the output gear. A cooling structure for a motor drive unit. In the cooling structure of the motor drive unit according to claim 2,
When the input gear is viewed from the gear side toward the motor side, the gear tooth twist direction is set so that the tooth groove is delayed from the rotation direction toward the motor side with respect to the input gear rotation direction. A motor drive unit cooling structure characterized by this. In the cooling structure of the motor drive unit according to claim 3,
The motor drive unit cooling structure, wherein the input gear tooth extension portion of the input gear is set to have a shape in which the depth of the tooth groove becomes shallower toward the motor side. In the cooling structure of the motor drive unit according to any one of claims 1 to 4,
A second oil tank is provided between the oil passage from the oil outlet to the oil inlet of the motor shaft center oil passage, in addition to the oil tank formed at a position below the tire shaft center line. Motor drive unit cooling structure. In the cooling structure of the motor drive unit according to claim 5,
In the second oil tank, the height of the oil inflow portion into the tank is set to a position lower than the motor shaft center line. In the cooling structure of the motor drive unit according to claim 5 or 6,
A cooling structure for a motor drive unit, characterized in that a through-hole connected to an oil tank formed below the tire axis center line is provided in a lower part of the second oil tank. In the cooling structure of the motor drive unit according to any one of claims 1 to 5,
The oil guide includes a base plate, a guide plate extending from the base plate to the input gear side, and a seal plate extending from the base plate to the motor side. In the cooling structure of the motor drive unit according to any one of claims 1 to 8,
The cooling structure for the motor drive unit, wherein the oil guide has a gap amount with the input gear set to be wide on the inlet side in the rotational direction and narrow on the outlet side in the rotational direction.