阅读说明：本技术 内燃机的气门正时控制装置 (Valve timing control device for internal combustion engine ) 是由 山中淳史 于 2019-06-05 设计创作，主要内容包括：具备：轴承凹部(10),所述轴承凹部(10)设置于链轮主体(1a)的内周面的保持板(8)侧的一部分,且在底面形成有滑动轴承面(10a)；以及轴颈部(11),所述轴颈部(11)从圆盘状主体(9a)的外周面向径向外侧突出地设置,与轴承凹部(10)嵌合并且外周面在滑动轴承面(10a)滑动。通过所述轴承凹部(10)的内侧面(10b)和保持板(8)的内周部(8b)的内侧面(8f),在从轴向的两侧夹持轴颈部(11)的两端面(11e、11f)的状态下受到轴向载荷(F1、F2)。由此,能够抑制驱动旋转体相对于从动旋转体的倾斜并且实现装置的小型化。(The disclosed device is provided with: a bearing recess (10), wherein the bearing recess (10) is provided on a part of the inner peripheral surface of the sprocket body (1a) on the side of the holding plate (8), and a sliding bearing surface (10a) is formed on the bottom surface; and a journal portion (11), wherein the journal portion (11) is provided so as to protrude radially outward from the outer peripheral surface of the disc-shaped body (9a), and is fitted in the bearing recess (10) such that the outer peripheral surface slides on the sliding bearing surface (10 a). Axial loads (F1, F2) are applied to the inner surface (10b) of the bearing recess (10) and the inner surface (8F) of the inner peripheral portion (8b) of the holding plate (8) while the two end surfaces (11e, 11F) of the journal portion (11) are sandwiched between the two axial sides. This makes it possible to suppress the inclination of the driving rotor with respect to the driven rotor and to reduce the size of the device.)

1. A valve timing control device for an internal combustion engine, the valve timing control device comprising:

a driving rotating body that transmits a rotational force from a crankshaft;

a driven rotary body fixed to the camshaft and rotating integrally with the camshaft;

a phase changing mechanism that changes a relative rotational phase between the driving rotating body and the driven rotating body by decelerating rotation of a motor output shaft of the electric motor by a deceleration mechanism;

a sliding bearing surface provided on an inner periphery of the driving rotating body;

a journal portion that is provided so as to protrude radially outward from an outer periphery of the driven rotary body, and an outer peripheral surface of which slides on the sliding bearing surface; and

and a first axial regulating portion and a second axial regulating portion provided in the driving rotating body, and regulating movement of the journal portion in the axial direction in a state where the journal portion is sandwiched from both sides in the axial direction.

2. The valve timing control apparatus of an internal combustion engine according to claim 1,

the sliding bearing surface is offset in the direction of the rotation axis of the driving rotating body with respect to the meshing portion of the speed reducing mechanism, and is provided on the radially outer side of the rotation axis of the driving rotating body than the meshing portion.

3. The valve timing control apparatus of an internal combustion engine according to claim 2,

the engaging portion has: internal teeth provided on an inner periphery of the driving rotating body; and a transmission member that is engaged with the internal teeth and transmits the rotation of the motor output shaft to the transmission portion of the driven rotating body after being decelerated,

the sliding bearing surface is provided radially outward of the root of the internal tooth.

4. The valve timing control apparatus of an internal combustion engine according to claim 3,

the transmission portion is provided in an annular shape protruding from an end edge of the driven rotating body on the journal portion side toward an inner peripheral side of the internal teeth,

the driving rotating body has a cover covering one side of the transmission part in the rotating shaft direction of the driving rotating body,

a gap is provided between the cover and the tip end surface of the transmission part.

5. The valve timing control apparatus of an internal combustion engine according to claim 4,

the driven rotary body has an oil hole for communicating an oil passage of the lubricating oil in the camshaft with a space radially inward of the transmission portion.

6. The valve timing control apparatus of an internal combustion engine according to claim 3,

the drive rotating body has a recess portion provided on an inner periphery thereof and having the sliding bearing surface on a bottom surface thereof,

the first axial regulating portion is an end surface of the recess portion in a rotation axis direction of the driving rotating body.

7. The valve timing control apparatus of an internal combustion engine according to claim 6,

an annular plate member that covers the other end side of the recess is fixed to the other side in the direction of the rotation axis of the driving rotor,

the second axial restriction portion is formed by the plate member.

8. The valve timing control apparatus of an internal combustion engine according to claim 7,

the inner diameter of the second axial restriction portion is located radially inward of the root of the internal tooth.

9. The valve timing control apparatus of an internal combustion engine according to claim 7,

the thickness of the plate member in the direction of the rotation axis of the driving rotator is greater than the thickness of the cover in the direction of the rotation axis of the driving rotator.

10. The valve timing control apparatus of an internal combustion engine according to claim 1,

the driving rotating body has outer teeth on an outer circumference thereof to transmit a rotational force from the crankshaft,

the sliding bearing surface is located at a position overlapping with the external teeth in a rotational axis direction of the driving rotary body.

11. The valve timing control apparatus of an internal combustion engine according to claim 10,

the speed reduction mechanism includes:

an eccentric shaft fitted to the motor output shaft and having an axis eccentric with respect to an axis of the motor output shaft;

a plurality of rollers disposed between an outer periphery of the eccentric shaft and an inner periphery of the internal teeth; and

and a retainer provided on the driven rotary body and having a plurality of roller holding holes for holding the plurality of rollers.

12. The valve timing control apparatus of an internal combustion engine according to claim 1,

when the axial width between the first axial regulating portion and the second axial regulating portion is a1, the diameter of the sliding bearing surface is a2, the axial width of the journal portion is B, and the diameter of the journal portion is D, the requirements are satisfied

Ca＝A1-B

Cr＝A2-D

Ca<Cr·(D/B)

The formula (1).

13. The valve timing control apparatus of an internal combustion engine according to claim 12,

the driving rotating body has outer teeth on an outer circumference thereof to transmit a rotational force from the crankshaft,

the sliding bearing surface is located at a position offset in the direction of the rotation axis of the driving rotary body with respect to the external teeth.

14. A valve timing control device for an internal combustion engine, the valve timing control device comprising:

a driving rotating body that transmits a rotational force from a crankshaft;

a driven rotary body fixed to the camshaft and rotating integrally with the camshaft;

a phase changing mechanism that changes a relative rotational phase between the driving rotating body and the driven rotating body by decelerating rotation of a motor output shaft of the electric motor by a deceleration mechanism;

a sliding bearing surface provided on a bottom surface of a recess provided on an inner periphery of the driving rotating body;

a journal portion that is provided so as to protrude radially outward from an outer periphery of the driven rotary body and slides on the sliding bearing surface; and

a first axial regulating portion and a second axial regulating portion provided to the driving rotating body and regulating movement of the journal portion in the axial direction in a state where the journal portion is sandwiched from both sides in the axial direction,

the first axial regulating portion and the second axial regulating portion are provided on one side in the rotation axis direction with respect to the engaging portion of the speed reducing mechanism.

15. The valve timing control apparatus of an internal combustion engine according to claim 14,

the engaging portion includes a protruding portion protruding in an axial direction from the driven rotary body, to which a decelerated rotational force of the electric motor is transmitted,

the driving rotating body has a plate member that covers one end portion of the protruding portion in the direction of the rotation axis of the driving rotating body,

the protruding portion has a gap between the one end portion and the plate member so that the protruding portion does not abut against the plate member even if the driving rotating body is inclined with respect to the driven rotating body.

16. The valve timing control apparatus of an internal combustion engine according to claim 14,

a radial gap between the sliding bearing surface and the journal portion is set so that the first axial regulating portion abuts against one end surface in the axial direction of the journal portion and the second axial regulating portion abuts against the other end surface in the axial direction of the journal portion when the driving rotating body tilts with respect to the driven rotating body.

Technical Field

The present invention relates to a valve timing control device for an internal combustion engine that controls opening and closing timings of an intake valve and an exhaust valve, for example.

Background

As a valve timing control apparatus for an internal combustion engine, a valve timing control apparatus for an internal combustion engine described in patent document 1 below is known.

In the valve timing control apparatus, the drive rotating body includes: a sprocket portion having, on an outer periphery thereof, external teeth around which a chain is wound; a cylindrical housing portion disposed at a front end of the sprocket portion; and a cylindrical gear portion disposed at a front end of the housing portion. The sprocket, the housing portion and the gear portion are axially coupled by a plurality of bolts.

A bottomed cylindrical driven rotating body is disposed on an inner peripheral side of the case portion so as to be relatively rotatable. The driven rotary body has a sliding surface formed on an outer peripheral surface of the cylindrical peripheral wall so as to slide on an inner peripheral surface of the housing portion in a surface-contact state.

Further, an outer surface of the disk-shaped bottom wall of the driven rotary body is restricted by abutting against a concave bottom surface of the sprocket portion from an axial direction, and a ring-shaped distal end surface of the cylindrical peripheral wall abuts against a rear end surface of the gear portion. Thereby, the axial positioning of the driven rotary body is performed, and the driving rotary body is supported by the sliding surface of the driven rotary body. In addition, the driven rotary body suppresses the inclination of the driving rotary body in the radial direction due to the tension of the chain during driving.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-172442 (FIG. 2)

Disclosure of Invention

Problems to be solved by the invention

However, in the valve timing control apparatus described in patent document 1, since the driven rotary body is axially positioned by the sprocket portion and the gear portion of the driving rotary body as described above, the distance from the outer surface of the bottom wall to the distal end surface of the cylindrical peripheral wall, that is, the length of the sliding surface in the axial direction becomes large.

Therefore, the length of the sliding surface in the axial direction is long, and therefore, although the inclination in the radial direction of the driving rotating body during driving can be suppressed, the length of the device in the axial direction may be increased.

The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a valve timing control device for an internal combustion engine, which can suppress the inclination of a driving rotating body with respect to a driven rotating body and can reduce the size of the device.

Means for solving the problems

As one of preferable aspects, the present invention is characterized by comprising: a phase changing mechanism that changes a relative rotational phase between the driving rotating body and the driven rotating body by decelerating rotation of a motor output shaft of the electric motor by the deceleration mechanism; a sliding bearing surface provided on an inner periphery of the driving rotating body; a journal portion that is provided so as to protrude radially outward from an outer periphery of the driven rotary body, and an outer peripheral surface of which slides on the sliding bearing surface; and a first axial regulating portion and a second axial regulating portion that are provided in the driving rotating body and regulate movement of the journal portion in the axial direction in a state where the journal portion is sandwiched from both sides in the axial direction.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the preferred embodiment of the present invention, the inclination of the driving rotating body can be suppressed and the device can be miniaturized.

Drawings

Fig. 1 is a partial longitudinal cross-sectional view of a valve timing control apparatus according to an embodiment of the present invention.

Fig. 2 is an exploded view showing main components provided in the present embodiment.

Fig. 3 is an enlarged view of a main portion of fig. 1.

Fig. 4 is a view in the direction a of fig. 1.

Fig. 5 is a view from direction B of fig. 1.

Fig. 6 is a cross-sectional view C-C of fig. 1.

Fig. 7 is a cross-sectional view taken along line D-D of fig. 1.

Fig. 8 is a schematic diagram showing the relationship between the lengths of the bearing recess and the journal portion provided in the present embodiment, and is an explanatory diagram of the action of the axial load of the journal portion mainly in the axial direction when the journal portion is inclined with respect to the sprocket.

Detailed Description

Hereinafter, an embodiment of a valve timing control apparatus for an internal combustion engine according to the present invention will be described in detail with reference to the drawings. In the present embodiment, the case where the valve timing control apparatus is applied to the intake side is shown, but it may be applied to the exhaust side.

[ embodiment ]

Fig. 1 is a partial longitudinal sectional view showing a valve timing control apparatus according to the present embodiment, fig. 2 is an exploded view showing main components provided in the present embodiment, fig. 3 is an enlarged view of a main portion of the present embodiment shown in fig. 1, and fig. 4 is a view taken along direction a of fig. 1.

As shown in fig. 1 and 2, the valve timing control apparatus includes: a timing sprocket 1 (hereinafter, referred to as a sprocket 1) as a driving rotating body; a camshaft 2 rotatably supported by the cylinder head 01 via a bearing 02; and a phase changing mechanism 3 disposed between the sprocket 1 and the camshaft 2, for changing relative rotational phases of the sprocket 1 and the camshaft 2 in accordance with an engine operating state.

The sprocket 1 is integrally formed in an annular shape from an iron-based metal as a metal material, and includes: an annular sprocket body 1 a; and a gear portion 1b as external teeth, the gear portion 1b being integrally provided on an outer periphery of the sprocket main body 1a, and having a not-shown timing chain wound therearound and receiving a rotational force from a crankshaft of the internal combustion engine.

A chain case, not shown, is provided on the outer periphery of the sprocket 1 to be coupled to a cylinder block and a cylinder head 01 of the internal combustion engine.

An annular internal gear structure 5 constituting a part of a speed reduction mechanism 13 described later is integrally provided on the front end side of the sprocket body 1 a. The internal tooth structure 5 is integrally coupled to the sprocket body 1a from the rotational axis direction, and has a plurality of internal teeth 5a formed in a wave shape on the inner periphery.

The sprocket body 1a is provided with a sliding bearing mechanism 6 between an inner peripheral surface thereof and an outer peripheral surface of a driven member 9, which is a driven rotating body fixed to one end portion 2a in the rotation axis direction of the camshaft 2 and will be described later. The slide bearing mechanism 6 supports the sprocket 1 on the outer periphery of the driven member 9 (camshaft 2) so as to be relatively rotatable. A specific description of the slide bearing mechanism 6 will be described later.

A retaining plate 8 as a plate member is fixed to a rear end surface of the sprocket body 1a on the side opposite to the internal tooth structure portion 5. As shown in fig. 2 to 4, the holding plate 8 is formed in an annular shape from a plate material of an iron-based metal as a metal material, and has an outer diameter set substantially equal to the outer diameter of the sprocket body 1 a. The holding plate 8 is disposed such that an inner peripheral portion 8b formed on the central hole 8a side covers an opening at one end of a bearing recess 10 of the sliding bearing mechanism 6, which will be described later, on the camshaft 2 side. The inner peripheral portion 8b is located at a position that becomes the hole edge of the central hole 8a and is located inward of the tooth root surface of the internal teeth 5a of the internal tooth structure portion 5.

The retaining plate 8 is integrally provided with a stopper protrusion 8c protruding radially inward, i.e., in the central axis direction, at a predetermined position on the inner peripheral edge of the center hole 8 a. The stopper protrusion 8c is formed in a substantially inverted trapezoidal shape, and the distal end surface is formed in an arc shape along the circular inner peripheral surface of a stopper groove 9f of a fixing end 9b of the driven member 9, which will be described later.

Fig. 5 is a view from direction B of fig. 1.

Further, a front plate 15 as a cover is provided on the front end surface of the sprocket 1 on the internal gear structure portion 5 side. As shown in fig. 1 to 3 and 5, the front plate 15 is formed by press-forming an iron-based metal plate into an annular shape, for example, and has a thickness t set smaller than a thickness t1 of the holding plate 8. The front plate 15 has an insertion hole 15a formed at the center thereof through which an eccentric shaft 21, which will be described later, is inserted.

In the outer peripheral portions of the sprocket body 1a including the internal gear structure portion 5 and the front plate 15, 6 bolt insertion holes 1c and 15b through which a plurality of (6 in the present embodiment) bolts 7 are inserted are formed at substantially equal intervals in the circumferential direction. The holding plate 8 has 6 female screw holes 8d formed at positions corresponding to the bolt insertion holes 1c and 15b, respectively, to which the male screw portions 7a at the distal end portions of the bolts 7 are screwed.

In addition, 2 positioning small holes 1d and 8e into which 2 positioning pins 30a and 30b are inserted are provided in each side portion of the 2 bolt insertion holes 1c of the sprocket body 1a and the corresponding 2 female screw holes 8d of the retaining plate 8. Thereby, the retainer plate 8 is positioned in the circumferential direction and the axial direction with respect to the sprocket 1.

The camshaft 2 has 2 drive cams for opening an intake valve, not shown, for each cylinder in the outer periphery. Further, the camshaft 2 is integrally provided with a flange portion 2b that is axially positioned via a bearing 02 at one end portion on the phase change mechanism 3 side in the rotation axis direction. Further, the camshaft 2 has a female screw portion 2c formed in the axial direction inside the one end portion 2a, and the driven member 9 is fastened and fixed in the axial direction by a cam bolt 14 screwed into the female screw portion 2 c. A pin, not shown, for positioning in the rotational direction of the driven member 9 is press-fitted and fixed to the tip of the one end portion 2a of the camshaft 2 from the rotational axis direction. The pin is inserted into a positioning hole 9e formed on the inner peripheral side of the front end surface of the driven member 9 and positioned.

Fig. 6 is a sectional view taken along line C-C of fig. 1, and fig. 7 is a sectional view taken along line D-D of fig. 1.

The driven member 9 is integrally formed of an iron-based metal, and as shown in fig. 1 to 4 and 6, mainly includes a disk-shaped body 9a and an annular fixed end portion 9b formed on the rear end side (camshaft 2 side) of the disk-shaped body 9 a.

The disc-shaped body 9a is integrally provided with a journal portion 11 constituting a part of the sliding bearing mechanism 6 on an outer peripheral surface thereof, and has a bolt insertion hole 9c formed to penetrate therethrough a shaft portion 14b of the cam bolt 14 in an inner axial direction including the fixed end portion 9 b.

The fixed end portion 9b has a constant wall thickness, protrudes from the disc-shaped body 9a toward the camshaft 2, and has an outer diameter set substantially the same as that of the disc-shaped body 9 a. The fixed end portion 9b has an annular fitting groove 9d formed substantially at the center of the outer surface on the camshaft 2 side (on the outer peripheral side of the bolt insertion hole 9 c) and fitted to the distal end portion of the one end portion 2a of the camshaft 2. A positioning hole 9e into which a positioning pin, not shown, is inserted from the axial direction is formed in the bottom surface of the fitting groove 9 d.

The fixed end portion 9b has a stopper groove 9f formed on the outer peripheral surface thereof along the circumferential direction, into which the stopper protrusion 8c of the holding plate 8 is fitted. The stopper groove 9f is formed in a circular arc shape having a predetermined length in the circumferential direction. Both side surfaces of the stopper protrusion 8c that rotates within the arc-shaped length of the stopper groove 9f are in contact with the circumferential facing surfaces. Thereby, the relative rotational position of the camshaft 2 with respect to the most advanced side or the most retarded side of the timing sprocket 1 is mechanically restricted.

The driven member 9 is fixed to the one end portion 2a of the camshaft 2 from the axial direction by the cam bolt 14 in a state where the tip end portion of the one end portion 2a of the camshaft 2 is fitted in the fitting groove 9d from the axial direction.

As shown in fig. 3, the sliding bearing mechanism 6 includes: an annular bearing recess 10 formed in the inner peripheral surface of the sprocket body 1 a; a journal portion 11 provided on the outer peripheral surface of the disc-shaped body 9a and disposed inside the bearing recess 10; and the holding plate 8 covering one end opening of the bearing recess 10.

The bearing recess 10 is formed only on the inner peripheral surface side of the sprocket body 1a on the camshaft 2 side, and does not extend from one side surface of the sprocket body 1a on the retainer plate 8 side to the internal tooth structure portion 5. As shown in fig. 1, the cross-sectional shape of the bearing recess 10 along the radial direction from the rotation axis of the sprocket 1 is formed to be substantially rectangular, and the bearing recess 10 is disposed such that a part thereof overlaps with the formation position of each gear portion 1b in the axial direction.

The bearing recess 10 has a sliding bearing surface 10a formed on an annular bottom surface. Further, the inner side surface 10b of the bearing recess 10 on the other end side opposite to the holding plate 8 in the axial direction is cut out at a substantially right angle in the radial direction from the sliding bearing surface 10 a. As described above, the other end portion of the bearing recess 10 on the camshaft 2 side is opened to the outside, and the other end opening that is opened is covered by the inner surface 8f of the inner peripheral portion 8b of the holding plate 8.

As shown in fig. 3, the journal portion 11 protrudes radially outward from the outer peripheral surface of the disc-shaped body 9a, and is formed in a rectangular shape having a cross-sectional shape substantially similar to the cross-sectional shape of the bearing recess 10. Since the bearing recess 10 overlaps with each gear portion 1b in the axial direction, the journal portion 11 is similarly disposed to partially overlap with each gear portion 1b of the sprocket 1 in the axial direction.

The journal portion 11 has annular grooves 11b and 11c formed on both sides in the axial direction of a base portion 11a serving as a coupling portion with the disk-shaped body 9 a. The annular outer peripheral surface 11d of the journal portion 11 can slide on the entire sliding bearing surface 10a of the bearing recess 10. The annular grooves 11b and 11c prevent the journal portions from coming into contact with the inner surface 8f of the holding plate 8 and the inner surface 10b of the bearing recess 10 when the driven member 9 rotates.

An axial end surface 11e of the journal portion 11 on the front plate 15 side is slidable on the inner surface 10b of the bearing recess 10. The inner side surface 10b of the bearing recess 10 serves as a first axial regulating portion that abuts against one end surface 11e of the journal portion 11 when the sprocket 1 tilts, and regulates one thrust movement.

The other end surface 11f of the journal portion 11 on the side of the holding plate 8 in the axial direction is slidable on the inner surface 8f of the inner peripheral portion 8b of the holding plate 8. The inner side surface 8f of the holding plate 8 serves as a second axial direction regulating portion that abuts against the other end surface 11f of the journal portion 11 when the sprocket 1 tilts, and regulates the movement of the other thrust force.

Fig. 8 is a schematic diagram showing the relationship between the lengths of the bearing recess 10 and the journal portion 11, and is an explanatory view of the axial loads F1 and F2 of the journal portion 11 mainly in the axial direction when the journal portion is inclined with respect to the sprocket 1.

That is, as shown in fig. 8, when the axial width between the inner surface 10B of the bearing recess 10 as the first axial restriction portion and the inner surface 8f of the holding plate 8 as the second axial restriction portion is a1, the diameter of the inner peripheral surface of the sliding bearing surface 10a is a2, the axial width between the both end surfaces 11e and 11f of the journal portion 11 is B, and the diameter of the outer peripheral surface of the journal portion 11 is D, the following expression is satisfied.

Ca＝A1-B

Cr＝A2-D

Ca<Cr·(D/B)

Here, Ca is an axial gap (clearance) between the axial width a1 and the axial width B of the journal portion 11. Cr is a radial clearance (gap) between the outer peripheral surface (diameter D) of the journal portion 11 and the inner peripheral surface (diameter a2) of the sliding bearing surface 10a of the bearing recess 10.

In the present embodiment, the axial gap Ca is set smaller than the radial gap Cr × (diameter D/axial width B).

As shown in fig. 1, the cam bolt 14 holds the needle rollers 25a of the needle bearing 25 on the outer peripheral surface of the head 14a so as to be able to roll. Further, an external thread portion 14c that is screwed to the internal thread portion 2c of the camshaft 2 is formed on the outer periphery of the distal end portion of the shaft portion 14 b.

As shown in fig. 1 and 2, the phase changing mechanism 3 is mainly composed of an electric motor 12 disposed on the distal end side of the fixed end portion 9b of the driven member 9, and a speed reducing mechanism 13 that reduces the rotational speed of the electric motor 12 and transmits the reduced rotational speed to the camshaft 2.

The electric motor 12 is a so-called brushless DC motor, and for simplicity of explanation, includes: a bottomed cylindrical motor case 16 fixed to the chain case; a motor stator provided at a rear end portion of the motor case 16 and having a stator coil and the like accommodated therein; a motor output shaft 17 disposed on the inner peripheral side of the stator coil; a cylindrical permanent magnet fixed to the outer periphery of the motor output shaft 17; and a power supply mechanism 18 provided at a front end portion of the motor housing 16 on the side opposite to the sprocket 1.

The motor housing 16 is formed in a substantially cup shape, and a through hole through which the motor output shaft 17 passes is formed substantially at the center of the distal end portion (bottom wall). On the other hand, a flange portion 16a protruding radially outward is provided on the outer periphery of the rear end portion. The flange portion 16a is integrally provided with 3 bracket pieces 16b at about 120 ° in the circumferential direction. Further, bolt insertion holes 16c for inserting bolts to be coupled to a chain case, not shown, are formed through the 3 bracket pieces 16 b.

Further, between the bracket pieces 16b in the circumferential direction of the flange portion 16a, other 3 different bolt insertion holes through which the 3 bolts 31 are inserted are formed. The power supply mechanism 18 is coupled to the motor housing 16 by bolts 31. Note that the bolt insertion hole 16c, the bolt 31, and the like may be further increased.

The motor stator is mainly formed integrally with a resin portion made of a synthetic resin material, and a stator coil is molded and fixed therein.

The power supply mechanism 18 is formed of a synthetic resin material in a box shape. Inside the power supply mechanism 18, an energizing circuit such as a bus bar for supplying power to the electric motor 12, a rotation sensor for detecting a rotational position of the motor output shaft 17, and the like are housed and arranged. The power feeding mechanism 18 is integrally provided with a power feeding connector 18a electrically connected to the energizing circuit and a signal connector, not shown, on the outer peripheral portion.

The terminals inside the power supply connector 18a are connected to a control unit, not shown, via female terminals and are connected to a battery as a power supply. On the other hand, a terminal inside the signal connector, not shown, is connected to the control unit via a female terminal, and outputs a rotation angle signal detected by the rotation sensor to the control unit.

The motor output shaft 17 is formed in a cylindrical shape from a metal material, and an intermediate member 20 is provided on the tip end side of the speed reduction mechanism 13 side, and the intermediate member 20 constitutes a part of a oldham coupling 19 as a joint mechanism connected to the speed reduction mechanism 13. The intermediate member 20 has a cylindrical base portion 20a fixed to the distal end portion 17a of the motor output shaft 17, and 2 transmission keys 20b and 20c integrally provided on the outer peripheral surface of the cylindrical base portion 20 a.

The cylindrical base portion 20a is made of a metal material, for example, an iron-based metal, and has a fixing hole 20d in the center thereof through which the distal end portion 17a of the motor output shaft 17 is inserted and fixed. The cylindrical base portion 20a has 2 flat surface portions of a flat shape (japanese: two-side width shape) at about 180 ° of the outer peripheral surface.

Each of the transmission keys 20b and 20c is formed in a substantially rectangular block shape and protrudes radially outward from 2 flat surface portions of the cylindrical base portion 20 a.

The control unit detects a current engine operating state based on information signals from various sensors such as a crank angle sensor, an air flow meter, a water temperature sensor, and an accelerator opening degree sensor, which are not shown, and performs engine control based on the detected current engine operating state. The control unit controls the rotation of the motor output shaft 17 by energizing the coil unit based on the information signals and the rotational position detection mechanism, and controls the relative rotational phase of the camshaft 2 with respect to the timing sprocket 1 by the reduction mechanism 13.

As shown in fig. 1, the speed reduction mechanism 13 is provided separately from the electric motor 12 in the axial direction, and each component is housed and arranged inside the sprocket 1 between the holding plate 8 and the front plate 15.

Specifically, as shown in fig. 1 to 3 and 7, the speed reduction mechanism 13 mainly includes: a cylindrical eccentric shaft 21 partially disposed inside the sprocket body 1 a; a ball bearing 22 provided on the outer periphery of the eccentric shaft 21; a roller 23 as a transmission member provided on the outer periphery of the ball bearing 22 and rollably retained in each internal tooth 5a of the internal tooth structure 5; a retainer 24 as a transmitting portion (projecting portion) that retains the roller 23 in the rolling direction and allows radial movement; and the driven member 9 integrally with the holder 24.

The eccentric shaft 21 has: an eccentric shaft portion 21a disposed on the outer periphery of a needle bearing 25 provided on the outer periphery of the head portion 14a of the cam bolt 14; and a large-diameter cylindrical portion 21b provided on the electric motor 12 side of the eccentric shaft portion 21 a.

The circumferential thickness of the eccentric shaft portion 21a varies such that the axial center X is slightly eccentric with respect to the axial center Y of the cam bolt 14.

The large-diameter cylindrical portion 21b constitutes a part of the oldham ring 19, and projects from the inside of the sprocket body 1a toward the electric motor 12 through the insertion hole 15a of the front plate 15. As shown in fig. 5, the large-diameter cylindrical portion 21b has a flat fitting hole 21c formed therein, into which the flat cylindrical base portion 20a of the intermediate member 20 can be fitted in the axial direction. The large-diameter cylindrical portion 21b has 2 key grooves 21d and 21e formed therein at a position of approximately 180 ° in the circumferential direction at the distal end portion on the electric motor 12 side, into which the transmission keys 20b and 20c of the intermediate member 20 can be fitted from the rotation axis direction.

The needle roller bearing 25 has: a plurality of needle rollers 25a that roll on the outer peripheral surface of the head 14a of the cam bolt 14; and a housing 25b fixed to a stepped surface formed on an inner peripheral surface of the eccentric shaft portion 21a and having a plurality of groove portions on an inner peripheral surface thereof for holding the needle roller 25a to be capable of rolling.

The ball bearings 22 are arranged in a state where the entire portions substantially overlap at radial positions of the needle roller bearings 25. The ball bearing 22 includes an inner ring 22a, an outer ring 22b, balls 22c interposed between the inner ring 22a and the outer ring 22b, and a cage 22d for holding the balls 22 c.

The inner ring 22a is press-fitted and fixed to the outer peripheral surface of the eccentric shaft portion 21a, whereas the outer ring 22b is not fixed in the axial direction and is in a free state. That is, the one end surface of the outer ring 22b on the electric motor 12 side in the axial direction does not contact the inner surface of the front plate 15 with a slight gap therebetween. The other end surface in the axial direction of the outer ring 22b is also kept away from the back surface of the disc-shaped body 9a of the driven member 9 facing the other end surface in the axial direction of the outer ring 22b with a slight gap.

The outer peripheral surface of each roller 23 is in rolling contact with the outer peripheral surface of the outer ring 22 b. An annular gap is formed between the outer peripheral surface of the outer ring 22b and the inner surface of the retainer 24. Therefore, the ball bearing 22 can eccentrically move in the radial direction in accordance with the eccentric rotation of the eccentric shaft portion 21a through the entire gap.

The retainer 24 is formed in an annular plate shape and is integrally provided on the outer peripheral portion of the disc-shaped body 9 a. That is, the retainer 24 is formed to linearly protrude from the base 11a of the journal portion 11 of the disc-shaped body 9a toward the front plate 15. A predetermined gap C is formed between the distal end surface 24a of the holder 24 and the inner surface 15C of the front plate 15.

Further, the retainer 24 has a plurality of substantially rectangular roller holding holes 24b formed at substantially equally spaced positions in the circumferential direction for holding the plurality of rollers 23 in a rollable manner. The roller holding holes 24b are provided at equally spaced positions in the circumferential direction of the holder 24, are closed at the distal end side, are formed in a rectangular shape elongated in the front-rear direction, and have a smaller number of teeth (the number of rollers 23) as a whole than the number of teeth of the internal teeth 5a of the internal tooth structure 5 as a whole, thereby obtaining a predetermined reduction ratio.

Each roller 23 is made of an iron-based metal, and moves in the radial direction in accordance with the eccentric movement of the ball bearing 22 to be fitted into the internal teeth 5a of the internal tooth structure portion 5. Further, each roller 23 is guided in the circumferential direction by both side edges of the roller holding hole 24b of the holder 24 and oscillates in the radial direction.

As shown in fig. 3, the speed reduction mechanism 13 supplies the lubricant oil to the inside via the lubricant oil supply passage. The lubricating oil supply passage includes: an oil passage 26 branched from the main oil gallery of the internal combustion engine and formed inside the camshaft 2 from the cylinder head 01; and an oil hole 27 formed to penetrate the disc-shaped body 9a of the driven member 9 in the axial direction of the camshaft 2.

The upstream one end 27a with a large diameter of the oil hole 27 communicates with the oil passage 26, and the downstream other end 27b with a small diameter communicates with the vicinity of the side of the housing 25b of the needle bearing 25.

As shown by arrows in the figure, the lubricating oil that has flowed into the reduction mechanism 13 from the oil hole 27 passes through the inside of the ball bearing 22, the inside of the retainer 24 on the outer peripheral side, and the like, and flows from there into between the bearing recess 10 and the journal portion 11. That is, the lubricating oil passes through the space between the both end surfaces 11e and 11f and the outer peripheral surface 11d of the journal portion 11, the inner surface 10b of the bearing recess 10, and the sliding bearing surface 10a to be lubricated. And is further discharged from the insertion hole 15a of the front plate 15 to the outside.

The lubricant is pressure-fed from a discharge passage of an oil pump, not shown, to the main oil gallery.

[ Effect of the present embodiment ]

The operation of the valve timing control apparatus in the present embodiment will be described below.

First, when the timing sprocket 1 is rotated via the timing chain in accordance with rotational driving of the crankshaft of the internal combustion engine, the rotational force is transmitted to the internal-tooth structure portion 5. The rotational force of the internal gear structure 5 is transmitted from each roller 23 to the camshaft 2 via the retainer 24 and the driven member 9. Thereby, the drive cam of the camshaft 2 opens and closes each intake valve.

When a predetermined internal combustion engine is operated after the internal combustion engine is started, a control current from the control unit is supplied to the coil portion of the electric motor 12, and the motor output shaft 17 is driven to rotate forward and backward. The rotational force of the motor output shaft 17 is transmitted to the eccentric shaft 21, and the rotational force after the speed reduction is transmitted to the camshaft 2 by the operation of the speed reduction mechanism 13.

Thereby, the camshaft 2 rotates forward and backward relative to the timing sprocket 1, and the relative rotation phase is changed. Therefore, each intake valve changes the opening/closing timing to the advance side or the retard side.

By continuously changing the opening/closing timing of the intake valve to the advance side or the retard side in this way, it is possible to improve the engine performance such as the fuel efficiency and the output of the engine.

In the present embodiment, when a chain tension is applied to the gear portion 1b during rotational driving, a force (rotational moment) in an oblique direction is generated in the sprocket 1 about the rotational center O, which is the center of the journal portion 11 in the radial direction and the axial direction, as a fulcrum. With this rotary motor, the bearing recess 10 abuts against the journal portion 11 from the axial direction, and axial loads F1 and F2 are generated. The axial loads F1, F2 can be received by the both end surfaces 11e, 11F of the journal portion 11. Therefore, the tilting of the sprocket 1 can be suppressed.

That is, as described above, the length relationship between the bearing recess 10 (including the retaining plate 8) and each portion of the journal portion 11 is set to satisfy the expression Ca < Cr · (D/B). Thus, as shown in fig. 8, when the sprocket 1 is inclined in the leftward rotational direction in the drawing with respect to the driven member 9, the one end surface 11e of the journal portion 11 receives an axial load F1 (hollow arrow) from the inner surface 10b of the bearing recess 10 on the lower side in the drawing. On the other hand, at the upper side, the other end surface 11F of the journal portion 11 receives an axial load F2 (hollow arrow) from the inner surface 8F of the holding plate 8.

With this arrangement, the one end surface 11e and the other end surface 11f of the journal portion 11 come into contact with the inner surface 10b and the inner surface 8f of the bearing recess 10 in a state where one of the one end portion 11da and the other end portion 11db in the axial direction of the outer peripheral surface 11d of the journal portion 11 is separated from the sliding bearing surface 10a of the bearing recess 10 by the inclination of the sprocket 1. That is, in the tilted state of the sprocket 1, the sliding bearing surface 10a does not abut on both the one end portion 11da and the other end portion 11db of the outer peripheral surface 11d of the journal portion 11, and the axial side surfaces 10b and 8f of the bearing recess 10 abut on the journal portion 11.

In other words, when the sprocket 1 is tilted in the left rotation direction to apply the axial loads F1, F2, the axial loads F1, F2 can be received and limited by the two end surfaces 11e, 11F of the journal portion 11 via the inner surface 10b of the bearing recess 10 and the inner surface 8F of the retainer plate 8, respectively.

This effectively suppresses the inclination of the sprocket 1 with respect to the driven member 9.

The effect of suppressing the inclination of the sprocket 1 is sufficiently exhibited even when the gear portion 1b of the sprocket 1 is disposed closer to the front plate 15 side, that is, even when the point of application of the chain tension is shifted from the rotation center O of the inclination of the sprocket 1, as shown in fig. 8, for example.

Further, since the axial loads F1, F2 are received and limited by the both end surfaces 11e, 11F of the journal portion 11, the radial load F3 (hollow arrow) that is the radial load from the journal portion 11 to the sliding bearing surface 10a of the bearing recess 10 can be sufficiently reduced by the large action of the rotational moment with respect to the sprocket 1.

Therefore, the friction between the outer peripheral surface of the journal portion 11 and the sliding bearing surface 10a can be sufficiently reduced. As a result, a smooth bearing action of the sprocket 1 with respect to the driven member 9 can be obtained at all times. This improves the speed of phase change of the valve timing control device.

The friction ratio between the outer peripheral surface 11D of the journal portion 11 and the sliding bearing surface 10a in the case where both the one end portion 11da and the other end portion 11db of the outer peripheral surface 11D of the journal portion 11 are in contact with the sliding bearing surface 10a in the inclined state of the sprocket 1 and in the case where the one end surface 11e and the other end surface 11f of the journal portion 11 are in contact with the inner side surface 10B and the inner side surface 8f of the bearing recess 10 in the inclined state of the sprocket 1 is determined by the ratio of the diameter D of the journal portion 11 to the axial width B. Therefore, as shown in this embodiment, the effect is higher when B < D.

The sliding bearing surface 10a of the bearing recess 10 is formed at a position axially overlapping the gear portion 1b of the sprocket 1. Therefore, the tensile load of the chain wound around the gear portion 1b acts on the journal portion 11 via the sliding bearing surface 10a, and therefore, the inclination of the sprocket 1 can be further suppressed.

Further, since the journal portion 11 is formed to protrude radially outward from the outer peripheral surface of the disc-shaped body 9a, the axial width B of the journal portion 11 as the inclination suppressing member of the sprocket 1, that is, the length a1 between the inner side surface 8f of the retaining plate 8 and the inner side surface 10B of the bearing recess 10 can be sufficiently shortened as compared with the above-described conventional art. This can shorten the length of the entire device in the axial direction, and thus can achieve a reduction in size of the device.

Further, since the length a1 between the inner surface 8f and the inner surface 10b can be shortened, management of dimensional accuracy between the inner surface 8f and the inner surface 10b and between the journal portions 11 becomes easy. As a result, the manufacturing operation becomes easy.

Further, since the clearance C is formed between the distal end surface 24a of the holder 24 and the inner surface 15C of the front plate 15, and the axial movement of the driven member 9 is restricted by the journal portion 1 and the bearing recess 10, the generation of friction between the holder 24 (driven member 9) and the front plate 15 is suppressed. Therefore, the responsiveness of the relative rotation between the sprocket 1 and the driven member 9 is improved, and the generation of the acoustic vibration can be suppressed.

Further, the lubricating oil supplied from the oil passage 26 to the inside of the speed reducing mechanism 13 through the oil hole 27 is forcibly supplied between the sliding bearing surface 10a of the bearing recess 10 and the outer peripheral surface 11d of the journal portion 11 by a centrifugal force during driving. Therefore, the lubricity of the entire inner surface of the bearing recess 10 including the gap between the both 10a and 11d and the outer surface of the journal portion 11 is improved.

In particular, since the sliding bearing surface 10a is provided radially outward of the root surface of the internal teeth 5a of the internal tooth structure portion 5, the lubricating oil is likely to flow into the internal teeth 5a side by the centrifugal force. Therefore, the lubricity between both 10a and 11d is further improved.

In particular, since the lubricating oil that has flowed into the bearing recess 10 is in a state of being accumulated even when the internal combustion engine is stopped, a rapid lubricating action can be obtained between the entire inner surface of the bearing recess 10 and the entire outer surface of the journal portion 11 after driving.

Further, a portion of the inner peripheral portion 8b of the holding plate 8, which becomes a hole edge of the central hole 8a, is arranged at a position inside the tooth root surface of each internal tooth 5a of the internal tooth structure 5. Therefore, when the internal combustion engine is stopped, as shown in fig. 3, the inner peripheral portion 8b functions as a dam, and therefore, the lubricating oil can be sufficiently accumulated on the tooth root surfaces of the internal teeth 5a in addition to the bearing concave portions 10. Therefore, lubricity between the internal teeth 5a and the rollers 23 during driving is improved, and smooth rotation of the speed reducing mechanism 13 can be obtained.

Further, since the thickness t1 of the holding plate 8 is set to be larger than the thickness t of the front plate 15, the rigidity is increased, and therefore, the durability against the axial load received from the other end surface 11f of the journal portion 11 can be improved. On the other hand, the inner surface 15c of the front plate 15 does not directly receive the axial load from the one end surface 11e of the journal portion 11, and therefore the thickness t can be reduced as much as possible. Therefore, the entire weight can be reduced.

Further, since the front plate 15 covering the bearing recess 10 is used as the second axial restriction portion, the manufacturing operation is simple.

In the present embodiment, the bearing of the sprocket 1 with respect to the driven member 9 is not a ball bearing, but a slide bearing using the bearing recess 10 and the journal portion 11. Therefore, the structure is simplified, the manufacturing work becomes easy, and reduction in component cost can be achieved.

The present invention is not limited to the configurations of the above embodiments, and for example, the speed reduction mechanism 13 may be a planetary gear type.

Further, if the journal portion 11 is formed to have a larger axial width in the radial direction as it is, the radial length of the both end surfaces 11e and 11f becomes larger, and therefore, the effect of restricting in the axial (axial) direction by the inner surface 8f of the inner peripheral portion 8b of the holding plate 8 and the inner surface 10b of the bearing recess 10 becomes larger. This can more effectively suppress the inclination of the sprocket 1.

As the second axial regulating portion, the entire bearing recess 10 may be formed in a recessed shape on the inner peripheral surface of the sprocket 1, and the inner peripheral portion 8b of the holding plate 8 may not be used as the inclination suppressing member.

The joint mechanism may be a joint other than an oldham coupling.

As the valve timing control apparatus for an internal combustion engine according to the above-described embodiment, for example, the following can be considered.

That is, according to a preferred aspect of the present invention, a valve timing control apparatus for an internal combustion engine includes: a driving rotating body that transmits a rotational force from a crankshaft; a driven rotary body fixed to the camshaft and rotating integrally with the camshaft; a phase changing mechanism that changes a relative rotational phase between the driving rotating body and the driven rotating body by decelerating rotation of a motor output shaft of the electric motor by a deceleration mechanism; a sliding bearing surface provided on an inner periphery of the driving rotating body; a journal portion that is provided so as to protrude radially outward from an outer periphery of the driven rotary body, and an outer peripheral surface of which slides on the sliding bearing surface; and a first axial regulating portion and a second axial regulating portion that are provided in the driving rotating body and regulate movement of the journal portion in the axial direction in a state where the journal portion is sandwiched from both sides in the axial direction.

More preferably, the sliding bearing surface is offset in the direction of the rotation axis of the driving rotor with respect to the meshing portion of the speed reduction mechanism, and is provided on the radially outer side of the rotation axis of the driving rotor than the meshing portion.

According to the present invention, since the lubricating oil contained in the speed reducing mechanism is supplied between the sliding bearing surface and the journal portion by the centrifugal force, the lubrication between the two becomes excellent.

More preferably, the engaging portion has: internal teeth provided on an inner periphery of the driving rotating body; and a transmission member that is engaged with the internal teeth and transmits the rotation of the motor output shaft to the transmission portion of the driven rotating body after being decelerated,

the sliding bearing surface is provided radially outward of the root of the internal tooth.

According to the present invention, the sliding bearing surface is located radially outward of the tooth root, and therefore, the lubricity is improved.

More preferably, the transmission portion is provided in an annular shape protruding from an end edge of the driven rotating body on the journal portion side toward an inner peripheral side of the internal teeth, the driving rotating body has a cover covering one side of the transmission portion in a rotation axis direction of the driving rotating body, and a gap is provided between the cover and a distal end surface of the transmission portion.

According to the present invention, the gap is provided between the cover and the distal end surface of the transmission portion, so that the generation of friction between the cover and the driven rotating body can be suppressed. Therefore, the responsiveness of the relative rotation of the driven rotating body and the driving rotating body becomes good.

More preferably, the driven rotary body has an oil hole for communicating an oil passage of the lubricating oil in the camshaft with a space radially inward of the transmission portion.

Since the sliding bearing surface is located radially outward, lubrication performance is improved by the lubricating oil that flows radially outward from the oil hole due to centrifugal force.

More preferably, the driving rotating body has a recess portion provided on an inner periphery thereof and having the sliding bearing surface on a bottom surface,

the first axial regulating portion is an end surface of the recess portion in a rotation axis direction of the driving rotating body.

More preferably, an annular plate member that covers the other end side of the recess is fixed to the other side in the rotation axis direction of the driving rotor, and the second axial restriction portion is formed by the plate member.

More preferably, the inner diameter of the second axial restriction portion is located radially inward of the root of the internal tooth.

The lubricating oil in the speed reducing mechanism is also accumulated in the tooth bottom of the internal teeth, and therefore, the lubricating property between each internal tooth and the rolling member is also improved.

More preferably, a thickness of the plate member in a rotation axis direction of the driving rotator is larger than a thickness of the cover in the rotation axis direction of the driving rotator.

By increasing the thickness of the plate member, durability against an axial load received by the second axial restricting portion from one of the driven rotary body (journal portion) can be improved. On the other hand, since the cover is not directly subjected to the axial load from the other side of the driven rotating body, the thickness can be reduced, and therefore the weight can be reduced.

More preferably, the driving rotor has external teeth on an outer periphery thereof for transmitting the rotational force from the crankshaft, and the sliding bearing surface is located at a position overlapping with the external teeth in a rotational axis direction of the driving rotor.

Since the portion of the annular wire rope (chain) wound around the external teeth by being overlapped with the applied load overlaps the sliding bearing surface, the inclination of the driven member can be further suppressed.

More preferably, the speed reducing mechanism includes: an eccentric shaft fitted to the motor output shaft and having an axis eccentric with respect to an axis of the motor output shaft; a plurality of rollers disposed between an outer periphery of the eccentric shaft and an inner periphery of the internal teeth; and a retainer provided to the driven rotating body and having a plurality of roller holding holes for holding the plurality of rollers.

More preferably, when an axial width between the first axial regulating portion and the second axial regulating portion is a1, a diameter of the sliding bearing surface is a2, an axial width of the journal portion is B, and a diameter of the journal portion is D, the axial width satisfies

Ca＝A1-B

Cr＝A2-D

Ca<Cr·(D/B)

The formula (1).

More preferably, the driving rotor has external teeth on an outer periphery thereof for transmitting a rotational force from the crankshaft, and the sliding bearing surface is located at a position shifted in a rotational axis direction of the driving rotor with respect to the external teeth.

As another preferable aspect, the valve timing control apparatus for an internal combustion engine includes: a driving rotating body that transmits a rotational force from a crankshaft; a driven rotary body fixed to the camshaft and rotating integrally with the camshaft; a phase changing mechanism that changes a relative rotational phase between the driving rotating body and the driven rotating body by decelerating rotation of a motor output shaft of the electric motor by a deceleration mechanism; a sliding bearing surface provided on a bottom surface of a recess provided on an inner periphery of the driving rotating body; a journal portion that is provided so as to protrude radially outward from an outer periphery of the driven rotary body and slides on the sliding bearing surface; and a first axial regulating portion and a second axial regulating portion which are provided in the driving rotating body and regulate movement in the axial direction in a state where the journal portion is sandwiched from both sides in the axial direction,

the first axial regulating portion and the second axial regulating portion are provided on one side in the rotation axis direction with respect to the engaging portion of the speed reducing mechanism.

More preferably, the engagement portion includes a protruding portion protruding in an axial direction from the driven rotary body, the rotational force of the electric motor after deceleration is transmitted to the protruding portion, the driving rotary body includes a plate member covering one end portion of the protruding portion in a rotational axis direction of the driving rotary body, and the protruding portion has a gap between the one end portion and the plate member so that the protruding portion does not abut against the plate member even if the driving rotary body is inclined with respect to the driven rotary body.

More preferably, a radial gap between the sliding bearing surface and the journal portion is set so that the first axial regulating portion abuts against one end surface in the axial direction of the journal portion and the second axial regulating portion abuts against the other end surface in the axial direction of the journal portion when the driving rotating body tilts with respect to the driven rotating body.

Description of the reference numerals

1 timing sprocket (driving rotating body), 1a sprocket body, 1b gear portion (external teeth), 2 camshaft, 2a one end portion, 3 phase changing mechanism, 8 holding plate (plate member), 8b inner circumferential portion, 8f inner side surface (second axial regulating portion), 9 driven member (driven rotating body), 9a disk-shaped body, 9b fixed end portion, 10 bearing recess, 10a sliding bearing surface, 10b inner side surface (one end surface/first axial regulating portion), 11 journal portion, 11a base portion, 11d outer circumferential surface, 11e one end surface, 11f other end surface, 12 electric motor, 13 speed reducing mechanism, 15 front plate (cover), 19 cross head coupling (coupling mechanism), 20 intermediate member, 21 eccentric shaft, 22 ball bearing, 22a inner ring, 22b outer ring, 23 roller, 24 retainer (transmitting portion/protruding portion), 24b roller holding hole, 25 needle roller bearing, the axial width between the inner side surface of the a1 bearing recess and the inner side surface of the retaining plate, the diameter of the a2 sliding bearing surface, the axial width of the B journal portion, the diameter of the D journal portion, the gap (clearance) between the two end surfaces of the Ca journal portion and the inner side surfaces of the bearing recess and the retaining plate, and the gap (clearance) between the Cr sliding bearing surface and the outer peripheral surface of the journal portion.