Drive device

A drive device includes a fluid coupling and a rotary electrical machine. The fluid coupling includes an impeller and a turbine, and is configured such that a torque is inputted thereto from one axial side and outputted therefrom to another axial side. The rotary electrical machine includes a first stator and a rotor. The first stator is disposed in a non-rotatable manner. The rotor is disposed to be rotated about a rotational axis of the fluid coupling. The first stator includes a first stator core, first and second coil ends. The first coil end protrudes from the first stator core in an axial direction. The second coil end protrudes from the first stator core to an opposite side of the first coil end in the axial direction. The first coil end is bent radially outward and located in part radially outside an outer peripheral surface of the first stator core.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2020-150310 filed Sep. 8, 2020. The entire contents of that application are incorporated by reference herein in their entirety.

TECHNICAL FIELD

The present invention relates to a drive device.

BACKGROUND ART

There has been proposed a type of drive device in which a rotary electrical machine is attached to a torque converter. For example, Japan Laid-open Patent Application Publication No. 2005-201402 describes that an electric motor is disposed between a torque converter and an engine.

When the rotary electrical machine is attached to the torque converter as described above, shortage of space is problematic compared to a well-known configuration that the rotary electrical machine is not attached to the torque converter. Because of this, it has been demanded to make the drive device axially compact.

BRIEF SUMMARY

It is an object of the present invention to make a drive device axially compact.

A drive device according to an aspect of the present invention includes a fluid coupling and a rotary electrical machine. The fluid coupling includes an impeller and a turbine. The fluid coupling is configured such that a torque is inputted thereto from a first side in an axial direction and is outputted therefrom to a second side in the axial direction. The rotary electrical machine includes a first stator and a rotor. The first stator is disposed in a non-rotatable manner. The rotor is disposed to be rotated about a rotational axis of the fluid coupling. The first stator includes a first stator core, a first coil end, and a second coil end. The first coil end protrudes from the first stator core in the axial direction. The second coil end protrudes from the first stator core to an opposite side of the first coil end in the axial direction. The first coil end is bent radially outward so as to be located in part radially outside an outer peripheral surface of the first stator core.

The drive device can be made axially compact by bending radially outward the first coil end, by which a drive force and so forth are less affected.

Preferably, the first coil end is bent radially outward from a base portion thereof.

Preferably, the first coil end overlaps a torus of the fluid coupling in a radial view. The first stator core does not overlap the torus of the fluid coupling in the radial view.

Preferably, the rotary electrical machine overlaps the fluid coupling in an axial view.

Preferably, the drive device further includes an angle sensor. The angle sensor is disposed radially inside a center of the torus of the fluid coupling. The angle sensor is disposed to overlap the torus in the radial view.

Preferably, the rotor is attached to an outer shell of the fluid coupling.

The rotor can be attached to the outer shell of the fluid coupling in a position located radially inside the center of the torus of the fluid coupling. According to the configuration, the rotor is attached to a part that is less deformable. Hence, it is possible to mitigate adverse impact on the part to which the rotor is connected.

The rotor can be attached to the outer shell of the fluid coupling in a position located radially outside the center of the torus of the fluid coupling. According to the configuration, the rotor is attached to a part that is less in amount of deformation. Hence, it is possible to inhibit axial movement of the rotor caused by deformation of the fluid coupling.

Preferably, the fluid coupling includes a second stator and a one-way clutch attached to an inner peripheral end of the second stator. The one-way clutch is disposed on the second side with respect to the center of the torus of the fluid coupling in the axial direction.

Preferably, the outer shell of the fluid coupling includes an attachment surface facing radially outward. The drive device further includes an inhibiting member having an annular shape. The inhibiting member is attached at an inner peripheral surface thereof to the attachment surface.

Preferably, the drive device further includes a starter ring gear. The starter ring gear is configured to transmit the torque to a crankshaft of an engine. The rotary electrical machine is disposed radially outside the fluid coupling. The starter ring gear is disposed radially outside the first or second coil end of the rotary electrical machine. The starter ring gear overlaps the first or second coil end in a radial view.

Preferably, the fluid coupling includes a nut fixed to a cover. The first or second coil end is disposed between the starter ring gear and the nut.

Overall, according to the present invention, a drive device can be made axially compact.

DETAILED DESCRIPTION

A drive device according to the present preferred embodiment will be hereinafter explained with reference to drawings. It should be noted that in the following explanation, the term “axial direction” refers to an extending direction of a rotational axis of the drive device. In the following embodiment, the term “first side in the axial direction” means the left side inFIG.1, whereas the term “second side in the axial direction” means the right side inFIG.1. An engine is disposed on the first side in the axial direction, whereas a transmission is disposed on the second side in the axial direction. On the other hand, the term “circumferential direction” refers to a circumferential direction of an imaginary circle about the rotational axis, whereas the term “radial direction” refers to a radial direction of the imaginary circle about the rotational axis.

As shown inFIG.1, a drive device100includes a torque converter2(exemplary fluid coupling), a rotary electrical machine3, and an angle sensor4. The drive device100is disposed in a power transmission path extending from the engine (not shown in the drawings) to the transmission.

The torque converter2is configured such that a torque is inputted thereto from the first side in the axial direction and is outputted therefrom to the second side in the axial direction. Specifically, in the present preferred embodiment, the torque converter2is configured such that a torque is inputted thereto from the engine and is outputted therefrom to the transmission.

The torque converter2includes a cover21, an impeller22, a turbine23, a second stator24, a lock-up clutch device25, and a one-way clutch26. The torque converter2is rotated about a rotational axis O. The torque converter2is configured to transmit the torque from the engine to the transmission through a fluid.

The cover21is a member to which the torque is inputted from the engine. The cover21includes a cover body21aand a tubular portion21b. The cover body21ais a disc-shaped member. The tubular portion21bextends from the outer peripheral end of the cover body21ato the second side in the axial direction. A flexible plate (not shown in the drawings) and so forth are fixed to an outer peripheral part of the cover body21a.

The impeller22is fixed to the cover21. The impeller22is unitarily rotated with the cover21. The impeller22includes an impeller shell22a, a plurality of impeller blades22b, an impeller hub22c, and an impeller core22d.

The impeller shell22aincludes an attachment surface22efacing radially outward. The attachment surface22eis provided radially inside a center C of a torus of the torque converter2. The attachment surface22eis provided radially inside the outer peripheral surface of the second stator24. It should be noted that the torus of the torque converter2means a space enclosed by the impeller shell22aand a turbine shell23a(to be described). Besides, the center C of the torus is the center of a space enclosed by the impeller core22dand a turbine core23d. It should be noted that when the torque converter2is of a coreless type, the center C of the torus is determined under the assumption that the torque converter2includes an impeller core and a turbine core.

The impeller blades22bare fixed to the inner side of the impeller shell22a. The impeller hub22cis fixed to the inner peripheral end of the impeller shell22a. The impeller hub22cextends from the inner peripheral end of the impeller shell22ato the second side in the axial direction. It should be noted that in the present preferred embodiment, the impeller hub22cis provided together with the impeller shell22aas a single member but can be provided as a member separated from the impeller shell22a. The impeller shell22a, the impeller hub22c, and the cover21compose an outer shell of the torque converter2.

The turbine23is disposed in axial opposition to the impeller22. The turbine23mainly includes the turbine shell23a, a plurality of turbine blades23b, a turbine hub23c, and the turbine core23d.

The turbine blades23bare fixed to the inner surface of the turbine shell23a. The turbine hub23cis fixed to the inner peripheral end of the turbine shell23a. The turbine hub23cis fixed to the turbine shell23aby a plurality of rivets (not shown in the drawings) and/or so forth. Besides, the turbine hub23cis provided with splines on the inner peripheral surface thereof so as to be engaged with an input shaft101of the transmission.

The second stator24is a mechanism for regulating the flow of hydraulic oil returning from the turbine23to the impeller22. The second stator24is disposed between the impeller22and the turbine23. The second stator24mainly includes a stator shell24a, a plurality of stator blades24bprovided on the outer peripheral surface of the stator shell24a, and a second stator core24c.

A first thrust bearing27ais disposed between the turbine23and the second stator24, whereas a second thrust bearing27bis disposed between the second stator24and the impeller22.

The one-way clutch26is attached to the inner peripheral end of the second stator24. The second stator24is supported by a stationary shaft102having a tubular shape through the one-way clutch26. The stationary shaft102extends between the outer peripheral surface of the input shaft101of the transmission and the inner peripheral surface of the impeller hub22c. The stationary shaft102is disposed in a non-rotatable manner.

The one-way clutch26is disposed on the second side with respect to the center C of the torus of the torque converter2in the axial direction. Besides, the one-way clutch26is disposed on the second side with respect to the stator blades24bin the axial direction.

The one-way clutch26does not overlap the stator blades24bin a radial view. By contrast, the one-way clutch26overlaps a first coil end31b(to be described) in the radial view.

The lock-up clutch device25is configured to allow and block transmission of the torque between the impeller22and the turbine23. In the present preferred embodiment, the lock-up clutch device25is configured to allow and block transmission of the torque between the impeller22and the turbine23through the cover21.

The lock-up clutch device25is disposed between the cover21and the turbine23and is configured to mechanically couple and decouple the both. The lock-up clutch device25includes a piston plate25aand a damper device25b.

The piston plate25ais supported by the turbine hub23cso as to be rotatable relative thereto and be movable in the axial direction. When moved toward the cover21, the piston plate25ais engaged by friction with the cover21and is unitarily rotated therewith.

The piston plate25ahas a disc shape and includes an opening in the middle thereof. The piston plate25ais provided with a friction material25cfixed to the cover21-side surface of the outer peripheral end thereof. The friction material25chas an annular shape. When the friction material25cis pressed against the cover21, a power is transmitted from the cover21to the piston plate25a. In other words, the friction material25cattached to the piston plate25ais provided as a clutch part.

The damper device25bincludes a plurality of elastic members25dand a driven plate25e. The driven plate25eis fixed to the turbine shell23a.

The elastic members25dare configured to elastically couple the turbine23and the piston plate25atherethrough. When described in detail, the elastic members25dare engaged with the driven plate25eand an engaging part (not shown in the drawings) provided in the piston plate25a.

The rotary electrical machine3functions as an electric motor for rotating and driving a drive wheel. Besides, the rotary electrical machine3also functions as a power generator. For example, the rotary electrical machine3functions as the power generator in deceleration.

The rotary electrical machine3is disposed to overlap the torque converter2in an axial view. When described in detail, the rotary electrical machine3is disposed in adjacent to the torque converter2in the axial direction. Besides, the rotary electrical machine3overlaps the impeller hub22cin the radial view. The rotary electrical machine3is disposed on the second side with respect to the torque converter2in the axial direction. In other words, the torque converter2, the rotary electrical machine3, and the transmission (not shown in the drawings) are disposed in the axial direction, while being aligned in this order.

The rotary electrical machine3includes a first stator31and a rotor32. Besides, the rotary electrical machine3further includes a field coil33. The rotary electrical machine3is made in shape of an annulus about the rotational axis O.

The first stator31is disposed in a non-rotatable manner. Specifically, the first stator31is attached to a housing103. The first stator31can be directly attached to the housing103, or alternatively, can be indirectly attached thereto.

The first stator31includes a first stator core31a, the first coil end31b, and a second coil end31c. The first stator31has an annular shape.

The first stator core31ahas a cylindrical shape. The first stator core31ais fixed at the outer peripheral surface thereof to the housing103. The first stator core31ais less in outer diameter than the torque converter2. The first stator core31ais formed by laminating a plurality of magnetic steel plates. A stator coil is wound about the first stator core31a. When described in detail, the stator coil is inserted into a plurality of slots produced between a plurality of teeth of the first stator core31a.

The first and second coil ends31band31ccompose part of the stator coil. Specifically, the first and second coil ends31band31care portions of the stator coil that axially protrude from the first stator core31a.

The first and second coil ends31band31cprotrude from the first stator core31ain opposite directions to each other. In the present preferred embodiment, the first coil end31bprotrudes from the first stator core31ato the first side in the axial direction, whereas the second coil end31cprotrudes from the first stator core31ato the second side in the axial direction. The first and second coil ends31band31care each made in shape of an annulus about the rotational axis O as a whole.

The first coil end31bis bent radially outward. When described in detail, the first coil end31bis bent radially outward from a base portion31d. Besides, the first coil end31bis in part located radially outside the outer peripheral surface of the first stator core31a. When described in detail, a tip portion31eof the first coil end31bis in part located radially outside the outer peripheral surface of the first stator core31a. It should be noted that the base portion31dis one of end portions of the first coil end31band is located close to the first stator core31ain the axial direction. By contrast, the tip portion31eis the other of the end portions of the first coil end31band is located apart from the first stator core31ain the axial direction.

The base portion31dof the first coil end31bis located radially inside the outer peripheral surface of the first stator core31a. On the other hand, the tip portion31eof the first coil end31bis in part located radially outside the outer peripheral surface of the first stator core31a. The first coil end31bis greater in outermost diameter than the first stator core31a.

The first coil end31bis configured to increase in outer diameter from the base portion31dto the tip portion31e. When described in detail, the base portion31dof the first coil end31bis less in outer diameter than the first stator core31a, whereas the tip portion31eof the first coil end31bis greater in outer diameter than the first stator core31a. It should be noted that the diameter of the first coil end31brefers to distance from the rotational axis O.

Besides, the first coil end31bis configured to increase in inner diameter from the base portion31dto the tip portion31e. It should be noted that the inner diameters of the base portion31dand the tip portion31eof the first coil end31bare smaller than the outer diameter of the first stator core31a.

As described above, the first coil end31bincreases in both outer diameter and inner diameter from the base portion31dto the tip portion31e. Because of this, the base portion31dand the tip portion31eof the first coil end31bare substantially equal in radial dimension.

The first coil end31boverlaps the torus of the torque converter2in the radial view. When described in detail, the first coil end31boverlaps the impeller blades22bin the radial view. On the other hand, the first stator core31adoes not overlap the torus of the torque converter2in the radial view.

Besides, the tip portion31eof the first coil end31bis disposed not to overlap the torus of the torque converter2in the axial view. It should be noted that in the present preferred embodiment, substantially the entirety of the first coil end31bdoes not overlap the torus of the torque converter2in the axial view.

Moreover, the first coil end31bsubstantially overlaps the torque converter2in the axial view. It should be noted that in the present preferred embodiment, the outer peripheral part of the tip portion31eof the first coil end31bdoes not overlap but alternatively can overlap the torque converter2in the axial view.

Unlike the first coil end31b, the second coil end31cis not bent radially outward. It should be noted that the second coil end31cis molded in part. When described in detail, the second coil end31creduces in outer diameter from a base portion31fto a tip portion31g. On the other hand, the second coil end31cis substantially constant in inner diameter from the base portion31fto the tip portion31g.

The rotor32is configured to be rotated about the rotational axis O. The rotor32is attached to the outer shell (the impeller shell22a) of the torque converter2. When described in detail, the rotor32is attached to the attachment surface22eof the impeller shell22a. In other words, the rotor32is attached to the torque converter2in a position located radially inside the center C of the torus of the torque converter2. The position, in which the rotor32is attached to the torque converter2, is located radially inside the outer peripheral surface of the second stator24. The rotor32also makes contact with the impeller shell22aat a part A so as to be radially positioned. It should be noted that the rotor32is not fixed to the impeller shell22aat the part A.

The rotor32has a cylindrical shape and is disposed radially inside the first stator31. In other words, the rotary electrical machine3according to the present preferred embodiment is of an inner rotor type. The rotor32is opposed at the outer peripheral surface thereof to the inner peripheral surface of the first stator31at an interval. The rotor32is made in form of a so-called claw pole type. Specifically, the rotor32includes a plurality of first claw poles32aand a plurality of second claw poles32b. The first claw poles32aand the second claw poles32bare alternately disposed in the circumferential direction. The first claw poles32aand the second claw poles32bare each made of a magnetic material such as iron. The first claw poles32aand the second claw poles32bare insulated from each other. For example, a non-magnetic material such as aluminum is disposed between adjacent first and second claw poles32aand32b.

The rotor32includes a support member32c(exemplary inhibiting member). The support member32csupports the first claw poles32aand the second claw poles32b. The support member32cis attached to the impeller shell22a. When described in detail, the support member32cis attached to the attachment surface22eof the impeller shell22a.

The support member32cincludes a disc portion32dhaving an annular shape and a cylindrical portion32e. The disc portion32dis attached at the inner peripheral surface thereof to the attachment surface22eof the impeller shell22a. The cylindrical portion32eextends from the outer peripheral end of the disc portion32dto the second side in the axial direction. The first and second claw poles32aand32bare supported by the cylindrical portion32e.

The field coil33is disposed radially inside the rotor32. The field coil33has a cylindrical shape. The field coil33is opposed at the outer peripheral surface thereof to the inner peripheral surface of the rotor32at an interval. The field coil33is disposed in a non-rotatable manner. For example, the field coil33is attached to the housing103in a similar manner to the first stator31.

The field coil33is configured to excite the rotor32by applying a magnetizing force to the rotor32. Electric current to be supplied to the field coil33is regulated by a current control unit (not shown in the drawings), whereby the magnetizing force applied to the rotor32can be regulated, and further, induced voltage to be generated in the first stator31can be regulated.

When electric current is supplied to the field coil33, the first and second claw poles32aand32bare excited. For example, the first claw poles32aare excited into N poles, whereas the second claw poles32bare excited into S poles. Thus, in the rotor32, N poles and S poles are alternately arranged in the circumferential direction. When the rotor32is rotated, the induced voltage (induced electromotive force) is generated in first the stator31.

The angle sensor4is configured to detect the rotational speed of the rotor32of the rotary electrical machine3. When described in detail, the angle sensor4is configured to detect the rotational speed of the outer shell of the torque converter2unitarily rotated with the rotor32.

The angle sensor4is, for instance, a resolver. For example, the angle sensor4is disposed radially inside the rotary electrical machine3. When described in detail, the angle sensor4, the field coil33, the rotor32, and the first stator31are disposed in this order from radially inside. The angle sensor4overlaps the rotary electrical machine3in the radial view. The angle sensor4overlaps the one-way clutch26in the axial view.

One preferred embodiment of the present invention has been explained above. However, the present invention is not limited to the above, and a variety of changes can be made without departing from the gist of the present invention.

In the preferred embodiment described above, the rotary electrical machine3is composed of the first stator31, the rotor32, and the field coil33. However, the composition of the rotary electrical machine3is not limited to this. For example, the rotary electrical machine3can be composed of the first stator31and the rotor32. In other words, the rotary electrical machine3may not include the field coil33. In this case, the rotor32is made of, for instance, permanent magnets.

The rotor32can be attached to the torque converter2in a position located radially outside the center C of the torus of the torque converter2. The rotor32can be attached to the torque converter2in a position located radially outside the outer peripheral surface of the second stator24of the torque converter2.

The angle sensor4can be disposed to overlap the torus in the radial view.

In the preferred embodiment described above, the first coil end31bof the first stator31protrudes from the first stator core31ato the first die in the axial direction. However, the configuration of the first coil end31bis not limited to this. For example, the first coil end31bcan protrude from the first stator core31ato the second side in the axial direction, whereas the second coil end31ccan protrude from the first stator core31ato the first side in the axial direction.

In the preferred embodiment described above, the rotary electrical machine3is disposed on the second side with respect to the torque converter2in the axial direction. However, the layout of the rotary electrical machine3is not limited to this. For example, the rotary electrical machine3can be disposed on the first side with respect to the torque converter2in the axial direction. Alternatively, as shown inFIG.2, the rotary electrical machine3can be disposed radially outside the torque converter2.

As shown inFIG.2, the drive device100can further include a starter ring gear5. The ring gear5is configured to transmit a torque to a crankshaft104of the engine. For example, the ring gear5is attached to the outer peripheral surface of a flexible plate6attached to the crankshaft104.

The torque converter2includes at least one nut28fixed to the cover21. At least one bolt is screwed into the at least one nut28, whereby the flexible plate6is attached to the cover21. The ring gear5is disposed radially outside the first coil end31bof the rotary electrical machine3. Besides, the ring gear5overlaps the first coil end31bin the radial view. The first coil end31bis disposed between the ring gear5and the at least one nut28.

In the preferred embodiment described above, the rotary electrical machine3is of an inner rotor type. Alternatively, the rotary electrical machine3can be of an outer rotor type.

In the preferred embodiment described above, the outer shell of the torque converter2is composed of the impeller shell22aand the cover21. However, the composition of the torque converter2is not limited to this. For example, the outer shell of the torque converter2can be composed of the cover21and the turbine shell23a. In this case, the impeller22and the turbine23are switched in position compared to the preferred embodiment described above. In other words, the impeller22is disposed inside the outer shell of the torque converter2. Besides, the torque outputted from the engine is transmitted to the impeller22by a transmission shaft that extends to the interior of the torque converter2while penetrating the outer shell.

In the preferred embodiment described above, the friction material25cis provided as the clutch part of the lock-up clutch device25. However, the clutch part is not limited to this. For example, as shown inFIG.3, a multi-plate clutch25fcan be provided as the clutch part of the lock-up clutch device25.

REFERENCE SIGNS LIST