Power transmission device

A power transmission device includes a flywheel, a torque limiter unit, and a damper unit. The torque limiter unit includes first and second side plates and a friction plate. The first side plate is attached to the flywheel. The first side plate is disposed on a first axial side to the flywheel. The friction plate is disposed axially between the first side plate and the second side plate. The damper unit includes input rotational bodies, an output plate, and an elastic member. The output plate is disposed axially between the first side plate and the flywheel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims the priority benefit of Japanese application 2022-120805 filed Jul. 28, 2022, the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a power transmission device.

Description of the Related Art

Power transmission devices are configured to absorb torque fluctuation of an engine. The power transmission devices include a flywheel, a torque limiter unit, and a damper unit (e.g., Patent Literature 1). The damper unit is attached to the flywheel via the torque limiter unit. The torque limiter unit is configured to restrict transmission of torque with a predetermined value or more, between the flywheel and the damper unit.

SUMMARY OF THE INVENTION

There is a desire to reduce the cost of the power transmission device configured as described above. In view of this, an object of the present invention is to provide a power transmission device capable of reducing the cost.

A power transmission device according to a first aspect includes a flywheel, a torque limiter unit, and a damper unit. The torque limiter unit is attached to the flywheel. The damper unit is attached to the torque limiter unit. The torque limiter unit includes a first and second side plates, and a friction plate. The first side plate is attached to the flywheel. The first side plate is disposed on a first axial side to the flywheel. The second side plate configured to rotate integrally with the first side plate. The second side plate is disposed on the second axial side with respect to the first side plate. The friction plate is disposed axially between the first side plate and the second side plate. The damper unit includes an input rotational body, an output plate, and an elastic member. The input rotational body is configured to rotate integrally with the friction plate. The output plate is disposed to be rotatable relative to the input rotational body. The output plate is disposed axially between the first side plate and the flywheel. The elastic member elastically couples the input rotational body to the output plate.

According to the above configuration, the output plate is disposed between the first side plate and the flywheel. Accordingly, the first side plate and the flywheel do not interfere with each other when rotating relative to each other. And thus, when the first side plate and the output plate are cut from a single member, a step of cutting an outer circumferential surface of the output plate can be omitted, and the cost can be reduced.

A power transmission device according to a second aspect is the power transmission device according to the first aspect that employs the following configuration. The first side plate includes an outer circumferential portion and an inner circumferential portion. The inner circumferential portion is disposed on the first axial side with respect to the outer circumferential portion.

A power transmission device according to a third aspect is the power transmission device according to the first or second aspect that employs the following configuration. The flywheel includes a body portion and an attachment portion. The attachment portion is disposed radially outward of the body portion. The attached portion protrudes toward the first axial side from the body portion. The first side plate is attached to the attachment portion. The output plate is disposed between the first side plate and the body portion.

A power transmission device according to a fourth aspect is the power transmission device according to the third aspect that employs the following configuration. The flywheel includes a protruding portion. The protruding portion is disposed radially outward of the attachment portion. The protruding portion protrudes toward the first axial side with respect to the attachment portion.

A power transmission device according to a fifth aspect is the power transmission device according to any one of the first to fourth aspects that employs the following configuration. The input rotational body includes a first input plate and a second input plate. The friction plate is attached to the first input plate. The second input plate is disposed on the second axial side with respect to the first input plate. The second input plate is configured to rotate integrally with the first input plate.

A power transmission device according to a sixth aspect is the power transmission device according to any one of the first to fifth aspects that employs the following configuration. An outer diameter of the output plate is the same as an inner diameter of the first side plate.

A power transmission device according to a seventh aspect is the power transmission device according to any one of the first to sixth aspects that employs the following configuration. The friction plate is a separate member from the first input plate.

A power transmission device according to an eighth aspect is the power transmission device according to any one of the first to seventh aspects that employs the following configuration. The first side plate is disposed such that an inner circumferential surface of the first side plate does not face an outer circumferential surface of the output plate.

According to the present invention, a power transmission device capable of reducing the cost can be provided.

DESCRIPTION OF EMBODIMENTS

Overall Configuration

FIG.1is a front, axial view of a power transmission device100according to the present embodiment, andFIG.2is a cross-sectional view taken along the staggered line II-II inFIG.1. InFIG.2, line O-O is a rotational axis of the power transmission device100. InFIG.2, an engine (not shown) is disposed on the left side with respect to the power transmission device100, and a drive unit (not shown) including a motor, a speed shifter, and the like is disposed on the right side with respect to the power transmission device100.

Note that in the following description, an “axial direction” refers to the direction in which the rotational axis O of the power transmission device100extends. A “circumferential direction” refers to the circumferential direction of a circle centered about the rotational axis O, and a “radial direction” refers to a radial direction of the circle centered about the rotational axis O. Note that, the circumferential direction need not necessarily exactly match the circumferential direction of the circle centered about the rotational axis O, and the radial direction need not necessarily exactly match the diameter direction of the circle centered about the rotational axis O.

As shown inFIGS.1and2, the power transmission device100is provided between the engine and an input shaft111of the drive unit. The power transmission device100is configured to restrict torque transmitted between the engine and the drive unit, and attenuate rotational fluctuation. The power transmission device100includes a flywheel10, a torque limiter unit5, and a damper unit2.

The flywheel10is disposed so as to be rotatable around the rotational axis O. The flywheel10includes a body portion11and an attachment portion12. The body portion11and the attachment portion12are integrally formed as a single member. Note that the body portion11may be formed as a separate member from the attachment portion12. In this case, the body portion11can be a flexible plate.

The body portion11is formed in a disc-like shape. The attachment portion12is disposed radially outward of the body portion11. The attachment portion12has an annular shape that extends in the circumferential direction. The attachment portion12protrudes toward the first axial side with respect to the body portion11.

The attachment portion12includes an attachment surface121. The attachment surface121faces toward the first axial side. The attachment surface121has an annular shape as seen in the axial direction. The attachment portion12includes a plurality of screw holes122in the attachment surface121. The plurality of screw holes122are arranged in the circumferential direction. The attachment portion12also includes a plurality of knock pins (not shown). The plurality of knock pins are arranged in the circumferential direction. The knock pins protrude from the attachment surface121toward the first axial side. By inserting the knock pins into knock pin holes formed in an outer circumferential portion of torque limiter unit5, the torque limiter unit5is positioned with respect to the flywheel10.

The torque limiter unit5is configured to be attached to the flywheel10. Specifically, an outer circumferential portion of the torque limiter unit5is attached to the attachment portion12of the flywheel10.

The torque limiter unit5is disposed radially outward of the damper unit2. The torque limiter unit5is configured to restrict torque transmitted between the flywheel10and the damper unit2. In other words, the torque limiter unit5is configured to restrict the transmission of torque with a predetermined value or more.

As shown inFIG.3, the torque limiter unit5includes a first side plate51, a second side plate52, a pressure plate53, a cone spring54, a first friction member55a, a second friction member55b, and a friction plate56.

First Side Plate

The first side plate51has an annular shape. The first side plate51is attached to the flywheel10. Specifically, the first side plate51is attached to the attachment portion12of the flywheel10. The first side plate51is disposed on the first axial side with respect to the flywheel10.

The first side plate51includes an outer circumferential portion511and an inner circumferential portion512. The inner circumferential portion512of the first side plate51is subjected to a biasing force from a cone spring54.

The outer circumferential portion511of the first side plate51is configured to be attached to the flywheel10. Specifically, the outer circumferential portion511includes a through hole513through which is passed a bolt (not shown) that is to be screwed into a screw hole122.

The inner circumferential portion512of the first side plate51is disposed on the first axial side with respect to the outer circumferential portion511. The inner circumferential portion512is linked to the outer circumferential portion511via a link portion514that extends in the axial direction.

Second Side Plate

The second side plate52is configured to rotate integrally with the first side plate51. Specifically, the second side plate52is fixed to the flywheel10together with the first side plate51using a bolt (not shown) that is screwed into the screw hole122. The second side plate52is disposed on the second axial side with respect to the first side plate51.

The second side plate52has an annular shape. The outer diameter of the second side plate52is substantially the same as the outer diameter of the first side plate51. The inner diameter of the second side plate52is larger than the inner diameter of the first side plate51.

The second side plate52includes an outer circumferential portion521and an inner circumferential portion522. The outer circumferential portion521of the second side plate52is configured to be attached to the flywheel10. Specifically, the outer circumferential portion521includes a through hole523through which is passed a bolt (not shown) that is to be screwed into the screw hole122.

The outer circumferential portion521of the second side plate52is in contact with the outer circumferential portion511of the first side plate51. On the other hand, the inner circumferential portion522of the second side plate52is disposed spaced apart from the first side plate51in the axial direction. The thickness of the second side plate52is smaller than the thickness of the first side plate51.

Friction Plate

The friction plate56has an annular shape. The friction plate56is configured to rotate integrally with first and second input plates21and22(described later). Specifically, the friction plate56is attached to the first input plate21. The friction plate56is disposed on the first axial side with respect to the first input plate21. The friction plate56is thinner than the first input plate21. The friction plate56is disposed axially between the first side plate51and the second side plate52.

Second Fastening Portion

As shown inFIG.2, the second fastening portion57fastens the friction plate56to the damper unit2. Specifically, the second fastening portion57fastens the friction plate56to the first input plate21. The second fastening portion57is disposed radially inward of the first fastening portion26(described later). Note that the second fastening portion57may be a rivet, for example.

Friction Member

As shown inFIG.3, the first and second friction members55aand55beach have an annular shape. The first friction member55ais disposed axially between the friction plate56and the first side plate51. The second friction member55bis disposed axially between the friction plate56and the second side plate52. Specifically, the second friction member is disposed axially between the friction plate56and the pressure plate53.

The first and second friction members55aand55bare attached to the friction plate56. The first friction member55ais frictionally engaged with the first side plate51. The second friction member55bis frictionally engaged with the pressure plate53. Upon receiving torque with a predetermined value or more, the first friction member55aslides against the first side plate51and the second friction member55bslides against the pressure plate53. As a result of this, the first side plate51and the friction plate56rotate relative to each other. Note that the first friction member55amay be fixed to the first side plate51, and frictionally engaged with the friction plate56. The second friction member55bmay be fixed to the pressure plate53and frictionally engaged with the friction plate56.

Pressure Plate

The pressure plate53has an annular shape. The pressure plate53is disposed axially between the first side plate51and the second side plate52. Specifically, the pressure plate53is disposed axially between the second friction member55band the cone spring54.

Cone Spring

The cone spring54is disposed axially between the second side plate52and the pressure plate53. Note that the cone spring54is in contact with an inner circumferential portion522of the second side plate52. The cone spring54biases the pressure plate53toward the first axial side. With this, the pressure plate53and the first side plate51sandwich the friction plate56and the first and second friction members55aand55b.

Damper Unit

As shown inFIG.2, the damper unit2is attached to the torque limiter unit5. The damper unit2is configured to attenuate rotational fluctuation. The damper unit2includes the first input plate21, the second input plate22, a hub flange23, and a plurality of elastic members24. The damper unit2includes a hysteresis generating mechanism25. Note that the first input plate21and the second input plate22correspond to an input rotational body of the present invention.

First and Second Input Plates

The first input plate21and the second input plate22rotate integrally with each other. The first input plate21and the second input plate22are not capable of moving relative to each other in the axial direction. The first input plate21and the second input plate22are configured to rotate integrally with the friction plate56. Specifically, the friction plate56is attached to the first input plate21. Note that the friction plate56is a separate member from the first input plate21, but the friction plate56may be configured as a single member that is formed integrally with the first input plate21. Both the first input plate21and the second input plate22are annular members having a center hole.

The first input plate21and the second input plate22are disposed spaced apart from each other in the axial direction. The second input plate22is disposed on the second axial side with respect to the first input plate21. The second input plate22is disposed on the second axial side with respect to the second side plate52.

The first input plate21includes a plurality of first window portions211. Note that in the present embodiment, the first input plate21includes four first window portions211. The first window portions211are arranged in the circumferential direction.

The second input plate22includes a plurality of second window portions221. Note that in the present embodiment, the second input plate22includes four second window portions221. The second window portions221are arranged in the circumferential direction.

The second window portions221are disposed at locations that respectively overlap the first window portions211as seen in the axial direction.

First Fastening Portion

The first fastening portions26fasten the first input plate21to the second input plate22. The first fastening portions26may be rivets, for example. The first fastening portions26are disposed on the second axial side with respect to the second side plate52. The first fastening portions26are disposed so as to overlap the first side plate51as seen in the axial direction.

Hub Flange

A hub flange23is configured to transmit torque from the first and second input plates21and22to a device on the output side. The hub flange23includes a hub231and a flange plate232(an example of the output plate). The hub231and the flange plate232are integrally formed in one piece by a plurality of teeth and a plurality of recessed portions with which the teeth are engaged.

The hub231has a tubular shape and is disposed in the center holes of the first input plate21and the second input plate22. A spline hole axially extending is formed in an inner circumferential portion of the hub231. The input shaft111that is a member on the output side can be spline-engaged with this spline hole.

The flange plate232radially extends from an outer circumferential surface of the hub231. The flange plate232has an annular shape. The flange plate232is disposed so as to be rotatable relative to the first input plate21and the second input plate22.

The flange plate232is disposed axially between the first input plate21and the second input plate22. The flange plate232is disposed axially between the first side plate51and the flywheel10. Specifically, the flange plate232is disposed axially between the first side plate51and the body portion11. In other words, the first side plate51, the flange plate232, and the body portion11of the flywheel10are disposed in this order from the first axial side.

The flange plate232is disposed such that the outer circumferential surface thereof does not face the inner circumferential surface of the first side plate51. Specifically, the outer circumferential surface of the flange plate232is disposed on the second axial side with respect to the inner circumferential surface of the first side plate51. Thus, the first side plate51and the flange plate232do not interfere with each other. Note that the inner circumferential surface is a surface facing radially inward and the outer circumferential surface is a surface facing radially outward.

FIG.4is a front, axial view of the flange plate232. As shown inFIG.4, the flange plate232has a disc-like shape. The flange plate232includes a center hole235and a plurality of housing holes233. Note that in the present embodiment, the flange plate232includes four housing holes233. The housing holes233are arranged in the circumferential direction. As seen in the axial direction, the housing holes233are disposed at locations that correspondingly overlap the first window portions211and the second window portions221.

The hub231extends inside the center hole235of the flange plate232. The plurality of teeth formed on the outer circumferential surface of the hub231are engaged with the plurality of recessed portions formed on an inner wall surface that defines the center hole235. With this, the hub231and the flange plate232integrally rotate.

The flange plate232includes a plurality of stopper portions234. In the present embodiment, the flange plate232includes four stopper portions234. The stopper portions234protrude radially outward from the outer periphery of the flange plate232. As a result of the stopper portions234coming into contact with the extended portions223of the second input plate22(seeFIG.2), rotation of the first and second input plates21and22relative to the flange plate232is restricted.

As shown inFIG.5, the outer diameter of the flange plate232is the same as the inner diameter of the first side plate51. Note that in the present embodiment, the outer diameter of the flange plate232means a length from a leading end of a stopper portion234to a leading end of another stopper portion234disposed on the opposite side thereto. Also, the thickness of the first side plate51is the same as the thickness of the flange plate232. For this reason, the first side plate51and the flange plate232can be cut from a single plate of material (e.g., metal). Further, since the inner circumferential surface of the first side plate51does not face the outer circumferential surface of the flange plate232, interference between the inner circumferential surface of the first side plate51and the outer circumferential surface of the flange plate232can be prevented without cutting the outer circumferential portion of the flange plate232. In other words, in the present embodiment, the leading end surfaces of the stopper portions234do not interfere with the inner circumferential surface of the first side plate51, even without cutting or trimming the leading end portions of the stopper portions234of the flange plate232. For this reason, the step of cutting the leading end portions of the stopper portions234can be omitted, and as a result, manufacturing costs can be reduced.

Elastic Member

As shown inFIG.1andFIG.2, elastic members24are configured to elastically couple the first and second input plates21and22and the flange plate232in the rotational direction. The elastic members24may be coil springs, for example.

The elastic members24are housed in the housing holes233of the flange plate232. Also, the elastic members24are housed in the first window portions211of the first input plate21and are also housed in the second window portions221of the second input plate22.

Operation

Torque transmitted from the engine to the flywheel10is input to the damper unit2via the torque limiter unit5. The torque is input to the first and second input plates21and22of the damper unit2, and then the torque is transmitted to the hub flange23via the elastic members24. Then, power is transmitted from the hub flange23to the motor, the power generator, the speed shifter, and the like on the output side.

Further, for example, when starting the engine, since the inertia amount on the output side is large, excessive torque may be transmitted from the output side to the engine. In such a case, the torque transmitted to the engine side is restricted to a predetermined value or less by the torque limiter unit5.

Variation

The scope of the claimed invention is not limited to the embodiment described above, and various alterations and modifications can be made without departing from the scope of the present invention.

(a) As shown inFIG.6, the flywheel10may include a first protruding portion13(an example of the protruding portion). The first protruding portion13is disposed radially outward of the attachment portion12. The first protruding portion13has an annular shape extending in the circumferential direction. The first protruding portion13protrudes toward the first axial side with respect to the attachment portion12. In other words, a leading end surface130of the first protruding portion13is located on the first axial side with respect to the attachment surface121of the attachment portion12. Note that the leading end surface130of the first protruding portion13faces toward the first axial side.

A thickness t of the first protruding portion13gradually decreases toward the first axial side. The outer diameter of the first protruding portion13gradually decreases toward the first axial side.

The first protruding portion13includes a first inner circumferential surface131and a second inner circumferential surface132. The second inner circumferential surface132is disposed on the second axial side with respect to the first inner circumferential surface131. The inner diameter of the second inner circumferential surface132is smaller than the inner diameter of the first inner circumferential surface131. The second inner circumferential surface132is in contact with the outer circumferential surface of the torque limiter unit5. Note that the first inner circumferential surface131is disposed spaced apart from the torque limiter unit5in the radial direction.

Further, the flywheel10may include a second protruding portion14. The second protruding portion14is disposed radially outward of the attachment portion12. The second protruding portion14has an annular shape extending in the circumferential direction. The second protruding portion14protrudes toward the second axial side with respect to the attachment portion12. In other words, the second protruding portion14protrudes toward the opposite side to the first protruding portion13. A leading end surface141of the second protruding portion14is located on the second axial side with respect to the body portion11. Note that the leading end surface141of the second protruding portion14faces toward the second axial side.

The outer diameter of the second protruding portion14gradually decreases toward the first axial side. The outer diameter of the flywheel10gradually decreases toward the first axial side. The inner diameter of the second protruding portion14gradually decreases toward the first axial side.

Further, the attachment portion12may include a groove portion123in an outer circumferential end portion of the attachment surface121. The groove portion123extends in the circumferential direction. As seen from the first axial side, the groove portion123has an annular shape.

(b) In the above embodiment, the hub flange23is constituted by two members, namely, the hub231and the flange plate232. However, the hub flange23may be integrally formed as a single member.

LIST OF REFERENCE NUMERALS