JP2024125442A - Valve timing control device for internal combustion engine - Google Patents

Abstract

[Problem] To provide a valve timing control device for an internal combustion engine that can ensure good lubrication and dischargeability by lubricating oil supplied inside the reducer. [Solution] A reducer 13 that rotates a driven member 9 relative to a sprocket 1 by rotating an eccentric shaft member 21, a ball bearing 22 arranged on the outer periphery of the eccentric shaft member, a front plate 15 fixed to the sprocket and covering an outer ring 22b of the ball bearing from the axial direction, a lubricating oil inlet hole 28 formed on the inner periphery of a cam bolt insertion hole 9b of the driven member to supply lubricating oil into the reducer, and six lubricating oil drain holes 32 formed through the bottom wall of an annular recess 26 formed on the outer periphery of the front plate, the total cross-sectional area D of the lubricating oil drain holes being larger than the cross-sectional area D1 of the lubricating oil inlet hole. [Selected Figure] Figure 3

Description

The present invention relates to a valve timing control device for an internal combustion engine.

A conventional valve timing control device for an internal combustion engine is described in the following Patent Document 1. In this valve timing control device, a disk-shaped cover member is fixed to the front end of the sprocket with multiple bolts. This cover member is arranged to cover one end face of the rolling bearing, and multiple lubricant discharge holes are formed along the circumferential direction on the radial outside of the outer ring. In addition, an oil reservoir is formed radially outside the outer ring of the rolling bearing to collect lubricant introduced into the inside of the reducer from an oil introduction hole formed in the wall of the sprocket.

U.S. Patent US9,840,947 B2 (FIG. 4)

However, in the conventional valve timing control device described in Patent Document 1, the total cross-sectional area of the lubricating oil discharge holes is smaller than the cross-sectional area of the oil inlet hole of the sprocket. For this reason, the lubricating oil supplied to the inside of the reducer from the oil inlet hole is likely to accumulate in an oil reservoir due to centrifugal force during operation. As a result, the outer ring side of the rolling bearing and the gear meshing parts located radially outward of this outer ring are immersed in the lubricating oil.

Therefore, there is a risk that the mechanical efficiency of moving parts such as the rolling bearings and gear meshing parts will decrease due to the viscous resistance of the lubricating oil accumulated inside the reducer.

The present invention was devised in consideration of the above-mentioned conventional technical problems, and one of its objectives is to provide a valve timing control device for an internal combustion engine that can ensure good lubrication and dischargeability of each moving part by the lubricating oil supplied inside the reducer.

As one preferred embodiment, the reduction gear is characterized by comprising, inter alia, a rolling bearing disposed on the outer periphery of an input shaft inside the reduction gear, a cover member fixed to the driving rotor and covering the outer ring of the rolling bearing from the axial direction, a lubricant oil inlet hole provided radially inward of the inner ring of the rolling bearing of the driven rotor and communicating with a supply passage that supplies lubricant oil to an internal combustion engine, a plurality of lubricant oil outlet holes formed through the cover member, the plurality of lubricant oil outlet holes having a total cross-sectional area larger than the cross-sectional area of the lubricant oil inlet hole, and a lubricant oil passage that communicates the lubricant oil inlet hole and the plurality of lubricant oil outlet holes through the inner ring and outer ring of the rolling bearing.

According to a preferred embodiment of the present invention, it is possible to ensure that the lubricating oil supplied inside the reducer has good lubrication and dischargeability for the moving parts.

1 is a side view showing a vertical cross section of a reducer side of a valve timing control device according to a first embodiment of the present invention; FIG. 2 is an exploded perspective view showing the main components used in the present embodiment. FIG. 2 is an enlarged view of part A in FIG. FIG. 2 is a perspective view of a sprocket and a reducer viewed from the front plate side of the embodiment. 4 is a cross-sectional view taken along line BB in FIG. 3. FIG. 2 is a front view partially showing the sprocket and the reducer from the front plate side of the embodiment. 7 is a cross-sectional view taken along line CC of FIG. 6. FIG. 4 is a rear view of the driven member and the sprocket used in the embodiment, as viewed from the camshaft side. FIG. 9 is an enlarged view of part D in FIG. 8 .

Hereinafter, an embodiment of a valve timing control device for an internal combustion engine according to the present invention will be described in detail with reference to the drawings. In this embodiment, the valve timing control device is applied to the intake side, but it is also possible to apply it to the exhaust side.
First Embodiment
FIG. 1 is a side view showing a vertical section of the reducer side of the valve timing control device in this embodiment, FIG. 2 is an exploded perspective view showing the main components of this embodiment, FIG. 3 is an enlarged view of portion A in FIG. 1, FIG. 4 is a perspective view of the sprocket and reducer from the front plate side in this embodiment, and FIG. 5 is a cross-sectional view taken along line B-B in FIG. 3.

As shown in Figures 1 and 2, the valve timing control device includes a timing sprocket 1 (hereinafter referred to as sprocket 1), which is a driving rotor; a camshaft 2 rotatably supported on a cylinder head 01 via a bearing bracket 02; and a phase change mechanism 3 that is disposed between the sprocket 1 and the camshaft 2 and changes the relative rotational phase between the sprocket 1 and the camshaft 2 according to the engine operating state.

As shown in Figures 1 to 4, the sprocket 1 is made of sintered metal material obtained by sintering compacted metal powder, and is made of an annular sprocket body 1a with a generally L-shaped cross section, and an external tooth portion 1b, which is a gear portion, is integrally formed on the outer periphery of the sprocket body 1a.

The sprocket body 1a has six bosses 1c protruding from its outer periphery at intervals of approximately 60° in the circumferential direction. Each boss 1c has an arc-shaped outer surface and is internally formed with female threaded holes 1d into which the male threads of six bolts 7, described below, are screwed. By providing the bosses 1c on the outer periphery, the overall outer diameter of the sprocket body 1a, excluding the bosses 1c, can be reduced without increasing the overall outer diameter, allowing the sprocket body 1a to be made smaller and lighter.

The sprocket body 1a has a large diameter hole formed in the center, and a bearing recess 10, which is a sliding bearing, is provided on the inner peripheral surface of the hole. This bearing recess 10 supports the entire sprocket 1 so that it can rotate relatively between itself and a journal portion 11 on the outer periphery of a driven member 9, which is a driven rotating body (described later).

The rotational force is transmitted to each external tooth portion 1b from a timing chain (not shown) wound around a driven gear on the crankshaft of the internal combustion engine.

In this embodiment, a timing chain is used as a means for transmitting rotational force to the external teeth portion 1b, but the driven gear of the crankshaft may be directly meshed with the external teeth portion 1b, the gear portion having a modified structure, to transmit the rotational force.

In addition, the sprocket 1 can be replaced with a timing pulley with a belt wound around its outer circumference.

As shown in Figures 1 and 3, the sprocket body 1a has an annular recess 6 formed on the front end surface at one end (front end) in the axial direction.

The annular recess 6 is formed radially inward of the front end face of the sprocket body 1a and has a flat bottom surface 6a and an annular inner peripheral surface 6b formed in the axial direction from the outer peripheral edge of the bottom surface 6a.

The bottom surface 6a has a depth that is approximately half the axial depth of the external teeth portion 1b. The annular inner peripheral surface 6b has a diametric length d that is slightly larger than the outer diameter of the sprocket body 1a.

The annular recess 6 has an annular inner peripheral surface 6b to which the internal gear component 5, a circular annular member that constitutes part of the reducer 13 (described later), is inlayed (fitted) from the rotation axis direction.

The internal teeth component 5 is axially fitted into the annular recess 6 and is connected to the sprocket body 1a by bolts 7. The specific configuration of the internal teeth component 5 will be described later.

Furthermore, the sprocket body 1a is integrally provided with a first annular restricting portion 8 that constitutes part of the stopper mechanism at the other end (rear end) opposite the internal tooth component 5 in the axial direction.

As shown in Figures 1 to 3, the first annular regulating portion 8 is formed integrally with the sprocket 1 during sintering and is formed into a circular ring of a predetermined thickness from sintered metal material. This first annular regulating portion 8 is formed into a circular ring shape extending radially inward from the rear end edge of the sprocket body 1a on the camshaft 2 side. This first annular regulating portion 8 is formed with an outer diameter approximately equal to the outer diameter of the sprocket body 1a, and has a circular plate-shaped inner peripheral portion 8a. This inner peripheral portion 8a is positioned so that the annular inner surface 8g on the internal tooth component 5 side covers one end of the bearing recess 10 on the camshaft 2 side.

The first annular regulating portion 8 has two arc-shaped grooves 8b, 8c at predetermined positions on the inner peripheral surface of the inner peripheral portion 8a. The arc-shaped grooves 8b, 8c are provided at symmetrical positions of approximately 180° with respect to the center of the first annular regulating portion 8, and each arc length is formed in an angular range of approximately 90°. In addition, two first stopper protrusions 8d, 8e are provided between the two arc-shaped grooves 8b, 8c, that is, at approximately 180° positions in the circumferential direction. Each of the first stopper protrusions 8d, 8e is formed in an approximately arc shape, and each arc angle is formed at approximately 90°. As described later, each of the first stopper protrusions 8d, 8e is configured such that a second stopper protrusion 19a of one (one) of the second annular regulating portion 19 described later abuts against each edge facing in the circumferential direction from the circumferential direction to regulate the relative rotational position of the driven member 9.

The first annular restricting portion 8 has six bosses 1c arranged in succession at positions (equally spaced positions at approximately 60° in the circumferential direction) corresponding to the six bosses 1c of the sprocket body 1a on the outer peripheral surface. Inside each boss 1c on the first annular restricting portion 8 side, a through hole 8f is formed that is axially continuous with each female threaded hole 1d. This through hole 8f functions as a relief for the tip of the shaft portion 7a of the bolt 7 screwed into the female threaded hole 1d. Each bolt 7 has a male thread formed on the outer peripheral surface of the shaft portion 7a that screws into the female threaded hole 1d.

The camshaft 2 has two drive cams per cylinder on its outer circumference that open the intake valves (not shown). As shown in FIG. 1, the camshaft 2 is integrally provided with a flange portion 2b at one end 2a in the rotation axis direction, which is used to position the camshaft 2 in the axial direction via the bearing bracket 02.

The camshaft 2 has an insertion hole 2c formed along the internal axial direction from the tip surface of one end 2a. The shaft portion 14b of the cam bolt 14 described later is inserted into this insertion hole 2c, and a female thread portion 2d is formed on part of the inner peripheral surface on the tip side to fasten the male thread portion 14c of the cam bolt 14.

Figure 6 is a front view of the sprocket and reducer partially seen from the front plate side used in this embodiment, and Figure 7 is a cross-sectional view taken along line CC in Figure 6.

A front plate 15, which is a cover member, is provided on the front end surface of the internal gear component 5. As shown in Figs. 1 to 3, the front plate 15 is formed by, for example, stamping an iron-based metal plate into a disk shape by press forming, and has an outer peripheral portion 15a that is bolted to the front end surface of the internal gear component 5, a central portion 15b that is radially inward from the outer peripheral portion 15a and overlaps with a cage 24 (described later) in the axial direction, and an inner peripheral portion 15c that is radially inward from the central portion 15b and is offset and deformed in the axial direction toward the opposite side of the camshaft 2 from the central portion 15b.

Six bolt insertion holes 15d are formed through the outer peripheral portion 15a at equally spaced positions in the circumferential direction. Each bolt insertion hole 15d is formed to correspond to each female threaded hole 1d of the sprocket body 1a, and the shafts 7a of the six bolts 7 mentioned above are inserted into each of the bolt insertion holes 15d.

The central portion 15b is formed on the same plane as the outer peripheral portion 15a, and its inner surface on the camshaft 2 side faces one end surface of the outer ring 22b of the ball bearing 22 described later with a small gap C1 between them, and is also positioned opposite the tip surface of the cage portion 24b of the retainer 24 described later with a small gap C between them.

The inner peripheral portion 15c is bent from the central portion 15b toward the opposite side of the camshaft 2 in a crank-like convex shape, and a large-diameter through hole 15e is formed in the center.

At the position of the central portion 15b side of the outer peripheral portion 15a, as shown in Figs. 6 and 7, an annular recess 26 is formed on the inner peripheral surface on the camshaft 2 side. This annular recess 26 is formed together with the front plate 15 when it is press-molded, and is extruded in the axial direction opposite to the camshaft 2. The annular recess 26 is formed with a radial width W large enough to cover the tip end of the retainer 24 described later from the axial direction, and is formed with a substantially uniform width in the circumferential direction. In addition, as shown in Figs. 1 to 4, six recessed grooves 27 are formed on the outer peripheral edge of this annular recess 26 at substantially equal intervals (approximately 60° positions) in the circumferential direction of the front plate 15. These six recessed grooves 27 are formed together with the annular recess 26 when the front plate 15 is press-molded, and are formed in a semicircular arc shape with a mountain-shaped outer shape. In other words, each recessed groove 27 is formed in a semicircular arc shape that protrudes radially outward (toward the outer peripheral surface) of the front plate 15.

Furthermore, a plurality of (six in this embodiment) lubricant oil discharge holes 32 are formed through the bottom wall of the annular recess 26. Each of these lubricant oil discharge holes 32 is formed at a position corresponding to the position where each of the recessed grooves 27 is formed, and each has a uniform inner diameter. The total cross-sectional area D ( ^mm2 ) of all six of these lubricant oil discharge holes 32 is larger than the opening cross-sectional area D1 ( ^mm2 ) of a lubricant oil introduction hole 28 formed in the driven member 9 described later.

The front plate 15 also has six bolt insertion holes 15d formed through it in the outer peripheral portion 15a. Each bolt insertion hole 15d is designed to receive the shaft portion 7a of each of the six bolts 7 that connect the front plate 15 to the internal teeth component 5 and the sprocket body 1a via the internal teeth component 5. Each bolt insertion hole 15d is formed between adjacent grooves 27 in the circumferential direction of the outer peripheral portion 15a.

As shown in Figs. 1 to 5, the internal teeth component 5 is provided separately from the sprocket body 1a, and is formed as an annular integral part entirely from a metal material having a relatively high hardness, such as steel. As shown in Fig. 1, the internal teeth component 5 is formed such that its radial width L is greater than the radial width of the bottom surface 6a of the annular recess 6, so that when fitted into the annular recess 6, its inner peripheral portion protrudes inward from the inner peripheral surface of the bearing recess 10. The axial width L1 is greater than the depth to the bottom surface 6a of the annular recess 6, so that when fitted, the end opposite the camshaft 2 in the axial direction protrudes in the axial direction from the annular inner peripheral surface 6b of the annular recess 6. The internal teeth component 5 has sufficient rigidity due to the radial width L and axial width L1. In addition, the outer diameter of the internal teeth component 5 (the outer diameter of the radial fitting surface 5c described later) is formed to be approximately the same as or slightly greater than the inner diameter d of the annular inner peripheral surface 6b of the annular recess 6.

The internal tooth component 5 has multiple internal teeth 5a formed along the axial direction of the inner peripheral surface, an axial abutment surface 5b on one side facing the camshaft 2 in the axial direction that abuts against the bottom surface 6a of the annular recess 6 from the axial direction, and a radial engagement surface 5c that is radially outside the axial abutment surface 5b and engages with the annular inner peripheral surface 6b of the annular recess 6 from the axial direction.

Each of the internal teeth 5a is formed in a wavy shape on the entire inner circumferential surface, and each of the arc-shaped inner surfaces rotatably engages and holds the rollers 23, which are a plurality of engaging members described below. The internal teeth 5a are subjected to a general heat treatment such as induction hardening after cutting the internal teeth 5a.

The axial abutment surface 5b is formed as a flat control surface, and when the internal tooth component 5 is fitted into the annular recess 6 from the axial direction, it abuts in a tight contact state against the entire bottom surface 6a of the annular recess 6.

As shown in Figures 1 to 3, the radial mating surface 5c is formed in a flat annular shape on its entire outer periphery, and when the internal teeth component 5 is fitted axially into the annular recess 6, it is fitted axially into the inner periphery 6b of the annular recess 6 by intermediate fitting, which is a mechanical fit. However, the intermediate fit may be a press fit similar to an interference fit. In addition, the fit (including press fit) of the radial mating surface 5c into the inner periphery 6b of the annular recess 6 ensures coaxiality between the sprocket 1 and the internal teeth component 5.

The internal tooth component 5 has six bolt insertion holes 5e formed axially through it at positions corresponding to the female thread holes 1d of the sprocket body 1a in the circumferential direction, into which the shafts 7a of the bolts 7 are inserted. Therefore, the position where the radial mating surface 5c fits into the inner peripheral surface 6b is outside the positions where the bolt insertion holes 5e are formed.

As shown in Figs. 1 to 3, the driven member 9 is formed separately from the retainer 24 of the reducer 13. The driven member 9 is formed in a thick disk shape from sintered metal formed by compressing metal powder and sintering it. Specifically, the driven member 9 has a disk-shaped body 9a, a cam bolt insertion hole 9b formed through the center of the disk-shaped body 9a, a second annular restricting portion 19 formed on the rear end surface of the disk-shaped body 9a on the camshaft 2 side and constituting a stopper mechanism together with the first annular restricting portion 8, and a journal portion 11 provided integrally on the outer periphery of the disk-shaped body 9a and fitted into the bearing recess 10.

The disk-shaped main body 9a has a circular fitting groove 9c formed on the inner periphery of the second annular restricting portion 19, that is, on the inside surrounded by the second annular restricting portion 19, into which one end 2a of the camshaft 2 is fitted from the axial direction. A positioning pin hole 9d is formed through the bottom of the fitting groove 9c at a predetermined position, into which a positioning pin (not shown) provided on the camshaft 2 is inserted. The disk-shaped main body 9a also has an annular protrusion 9e formed on the outer periphery on the camshaft 2 side, which protrudes in the axial direction. The outer periphery of this annular protrusion 9e constitutes the other axial end of the journal portion 11, and an annular recess 9f is formed between the inner periphery and the second annular restricting portion 19.

The inner diameter of the cam bolt insertion hole 9b is smaller than the inner diameter of the insertion hole 2c of the camshaft 2, so that the shaft portion 14b (intermediate shaft portion 14g) of the cam bolt 14 can be inserted with a small gap.

Figure 8 is a front view of the reducer seen from the camshaft side, and Figure 9 is an enlarged view of part D in Figure 8.

A lubricant introduction hole 28 is formed in a part of the inner peripheral surface of the cam bolt insertion hole 9b. This lubricant introduction hole 28 constitutes a part of the lubricant supply mechanism described later, and as shown in Figures 8 and 9, the inner peripheral surface of the cam bolt insertion hole 9b is notched in an arc shape. In other words, the lubricant introduction hole 28 is provided radially inward from the inner ring 22a of the ball bearing 22 of the driven member 9, that is, on the shaft portion 14b side of the cam bolt 14, and one axial end of the driven member 9 opens into the radial passage portion 4b formed on the front end surface of one end 2a of the camshaft 2, while the other axial end opens into the inside of the reducer 13.

As shown in FIG. 2, the second annular restricting portion 19 is provided with a pair of second stopper protrusions 19a, 19b that protrude radially outward from the center of rotation P at a predetermined position on the outer circumferential edge. These second stopper protrusions 19a, 19b are provided at 180° symmetrical positions about the center of rotation P, and are disposed in the arc-shaped grooves 8b, 8c of the first annular restricting portion 8. Each of the second stopper protrusions 19a, 19b has an arc-shaped notch groove formed on both side edges of its base (root portion) to reduce stress concentration.

When the driven member 9 rotates to the maximum relative rotation in the counterclockwise direction in FIG. 2 with respect to the sprocket 1, one circumferential edge of one second stopper protrusion 19a abuts against the opposing side edge of one first stopper protrusion 8d, mechanically restricting further relative rotation. Also, when the driven member 9 rotates to the maximum relative rotation in the rightward direction in FIG. 2, the other circumferential edge of one second stopper protrusion 19a abuts against the opposing side edge of the other first stopper protrusion 8e, mechanically restricting further relative rotation.

2, when the driven member 9 rotates relatively to the left in FIG. 2 and one side edge of the second stopper protrusion 19a abuts against the opposing side edge of the first stopper protrusion 8e, the other second stopper protrusion 19b does not abut against the opposing side edge of the other first stopper protrusion 8e with a predetermined gap. Also, when the driven member 9 rotates relatively to the right in FIG. 2 and the other side edge of the second stopper protrusion 19a abuts against the opposing side edge of the other first stopper protrusion 8e, the other second stopper protrusion 19b does not abut against the opposing side edge of the first stopper protrusion 8d with a predetermined gap.

The driven member 9 is arranged so that one end 2a of the camshaft 2 is fitted axially into the fitting groove 9c, and is fastened axially to one end 2a of the camshaft 2 together with the retainer 24 by the cam bolt 14.

As shown in Figures 1 to 3, the sliding bearing mechanism is composed of an annular bearing recess 10 formed on the inner peripheral surface of the sprocket body 1a, and a journal portion 11 provided on the outer periphery of the driven member 9 and positioned inside the bearing recess 10.

The bearing recess 10 has one axial end on the camshaft 2 side covered by the first annular restricting portion 8, and the other end on the internal teeth component 5 side open. This opening is closed by the axial abutment surface 5b of the internal teeth component 5. As a result, the bearing recess 10 is formed on the entire inner circumferential surface of the sprocket body 1a from the annular inner side surface 8g to the axial abutment surface 5b. In addition, as shown in FIG. 1, the bearing recess 10 is positioned so that a portion of it axially overlaps with the formation position of each external tooth portion 1b.

The bearing recess 10 has a circular bottom surface that forms a sliding bearing surface 10a, and one end portion on the camshaft 2 side, i.e., the annular inner surface 8g of the first annular restricting portion 8, is formed at a substantially right angle in the radial direction from the sliding bearing surface 10a.

The journal portion 11 protrudes from the outer periphery of the disk-shaped body 9a toward the front plate 15, and has a rectangular cross-sectional shape that is nearly similar to the cross-sectional shape of the bearing recess 10. Since the bearing recess 10 overlaps with each of the external teeth 1b in the axial direction, the journal portion 11 is also partially overlapped with each of the external teeth 1b in the axial direction.

A disk-shaped groove 9g surrounded by a journal portion 11 is formed on the inner end surface of the driven member 9 opposite the camshaft 2. The annular outer peripheral surface of the journal portion 11 is capable of sliding over the entire plain bearing surface 10a of the bearing recess 10. This allows the journal portion 11 to function as a plain bearing that supports the entire sprocket 1 via the bearing recess 10.

The journal portion 11 is arranged such that one end face 11a on the axial front plate 15 side faces the axial abutment surface 5b of the internal tooth component 5 with a small gap C therebetween. The journal portion 11 is arranged such that the axial abutment surface 5b restricts the movement of the entire driven member 9 in the axial direction opposite the camshaft 2. In other words, the axial abutment surface 5b functions as a restricting surface for the driven member 9.

The journal portion 11 is configured so that the tip surface of the annular protrusion 9e, which is the other end portion on the axial side of the first annular restricting portion 8, can slide on the annular inner surface 8g of the first annular restricting portion 8. When the sprocket 1 tilts, the annular inner surface 8g of the first annular restricting portion 8 abuts against the tip surface of the annular protrusion 9e, which is the other end portion, to restrict the other thrust movement.

As shown in Figures 1 to 3, the cam bolt 14 has a substantially cylindrical head 14a, a shaft portion 14b that is fixed integrally to the head 14a, and a male thread portion 14c that is formed on the outer circumferential surface of the shaft portion 14b and screws into the female thread portion 2d of the camshaft 2.

The head 14a has a hexagonal tool hole 14d at the tip into which a tool such as a hexagonal wrench can be inserted. In addition, the entire outer periphery of the head 14a has been subjected to heat treatment such as induction hardening, making it harder than other parts.

The needle rollers 25a of the needle bearing 25 are supported so that they can roll on the hard outer peripheral surface of the head 14a. The seat surface 14f is designed to seat on the opposing surface that is outside the edge of the bolt hole 24c formed in the inner peripheral part of the retainer 24 when the male threaded portion 14c of the cam bolt 14 is screwed into the female threaded portion 2d of the camshaft 2 and fastened.

A large-diameter intermediate shaft portion 14g is integrally formed with the shaft portion 14b at the base of the head portion 14a, i.e., at the center of the axial seat surface 14f of the head portion 14a.

As shown in Figures 1 and 2, the phase change mechanism 3 is mainly composed of an electric motor 12 arranged on the front end side of the sprocket 1, and a reducer 13 that reduces the rotational speed transmitted from the electric motor 12 via the Oldham coupling and transmits it to the camshaft 2.

The electric motor 12 is a so-called brushless DC motor, and has a cylindrical motor housing 16 with a bottom that is fixed to a chain case (not shown), a motor stator (not shown) that is provided on the inner surface of the motor housing 16 and contains coils and the like inside, a motor shaft 17 that is positioned on the inner side of the coil, a permanent magnet (not shown) that is fixed to the outer periphery of the motor shaft 17, and a control unit 18 that is provided at the front end of the motor housing 16 on the side opposite the sprocket 1.

The motor housing 16 is formed in a roughly cup shape, with a through hole through which the motor shaft 17 is inserted formed at approximately the center of the front end (bottom wall). Meanwhile, a flange portion 16a that protrudes radially outward is integrally formed on the outer periphery of the rear end. Three bracket pieces 16b are integrally formed on this flange portion 16a at positions approximately 120° apart in the circumferential direction. In addition, each of the three bracket pieces 16b has a bolt insertion hole 16c through which a bolt is inserted to connect to a chain case (not shown).

In addition, three separate bolt insertion holes through which three bolts 29 are inserted are formed between each bracket piece 16b in the circumferential direction of the flange portion 16a. Each bolt 29 is designed to connect the control unit 18 to the motor housing 16. It is possible to further increase the number of bracket pieces 16b and bolt insertion holes 16c.

The motor stator is primarily made of synthetic resin and is integrally formed, with the coils fixed inside by molding.

The motor shaft 17 is made of a metal material and has a cylindrical shape, and the outer surface of the tip 17a on the side of the reducer 13 has a two-sided width portion (not shown) formed along the tangential direction. In addition, a pair of fitting grooves are formed on the tip edge side of the tip 17a, cut in a direction perpendicular to the two-sided width portion. Stopper members (not shown) that restrict the movement of the intermediate member 30 (described later) toward the cam bolt 14 are fitted and fixed radially into both fitting grooves.

The motor shaft 17 has a tip 17a that is positioned close to the head 14a of the cam bolt 14 with a small gap in the direction of the rotation axis. The entire tip 17a, including the stopper member, can be inserted axially into the tool hole 14d.

The stopper member is formed in a C-ring shape and can be elastically deformed in both the expanding and contracting directions by its own elastic force.

The control unit 18 has a housing 18a formed into a box shape from a synthetic resin material. Inside this housing 18a, a current-carrying circuit such as a bus bar that supplies power to the electric motor 12, a rotation sensor that detects the rotational position of the motor shaft 17, a circuit board that controls the amount of current, and other components are housed and arranged. In addition, the control unit 18 is provided integrally with a power supply connector 18b that is electrically connected to the current-carrying circuit in the housing 18a, and a signal connector (not shown).

The power supply connector 18b has an internal terminal that is connected to a battery (power source) via a female terminal to a control unit (not shown). On the other hand, the signal connector has an internal terminal that 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.

An intermediate member 30 is provided at the tip 17a of the motor shaft 17. This intermediate member 30 constitutes part of an Oldham coupling, which is a joint connected to the reducer 13, and has a cylindrical base 31 fixed to the tip 17a of the motor shaft 17, as shown in Figures 1 and 2. This cylindrical base 31 has a pair of two-sided flat portions 31a, 31b on both sides of its circular outer surface, i.e., at 180° positions in the circumferential direction, which gives it a roughly elliptical outer shape.

In addition, a through hole is formed in the center of the cylindrical base 31, into which the tip 17a of the motor shaft 17 is inserted.

This through hole has a pair of opposing surfaces with a two-sided width that run radially from the rotation axis of the motor shaft 17 formed on the circular inner peripheral surface. This results in a radially elongated oval shape similar to the outer shape of the cylindrical base 31. Therefore, the intermediate member 30 is capable of moving radially relative to the tip end 17a of the motor shaft 17 through the oval through hole.

A pair of projections, ie, two transmission keys 33a, 33b, are integrally provided at approximately the center of the pair of flat surfaces 31a, 31b in the longitudinal direction. Each transmission key 33a, 33b is formed in an approximately rectangular plate shape and projects radially outward from the two flat surfaces 31a, 31b of the cylindrical base 31.

The reducer 13 is provided axially separate and independent from the electric motor 12, and each component is housed and arranged between the driven member 9 and the front plate 15.

Specifically, as shown in Figures 1 to 3, the reducer 13 is mainly composed of a cylindrical eccentric shaft member 21 that is an input shaft with a portion disposed inside the sprocket body 1a, a ball bearing 22 fixed to the outer periphery of the eccentric shaft member 21, a number of rollers 23 provided on the outer periphery of the ball bearing 22 and held freely rolling within each internal tooth 5a of the internal tooth component member 5, and a cage 24 provided on the disk-shaped groove portion 9g side of the driven member 9 that holds the rollers 23 in the rolling direction while allowing them to move in the radial direction.

The eccentric shaft member 21 has an eccentric camshaft 21a that is arranged on the outer periphery of a needle bearing 25 that is provided on the outer periphery of the head 14a of the cam bolt 14, and a large-diameter cylindrical portion 21b that is a connecting portion on the electric motor 12 side of the eccentric camshaft 21a.

The eccentric camshaft 21a is formed in a cylindrical shape with an axial length slightly longer than the axial length of the needle bearing 25. In addition, the eccentric camshaft 21a has a wall thickness t that varies in the circumferential direction, and the axis X is slightly eccentric with respect to the axis Y of the motor shaft 17 of the electric motor 12 (see FIG. 1).

The cylindrical portion 21b is formed in a nearly perfect circle with a uniform thickness and is slightly thicker than the eccentric camshaft 21a. This cylindrical portion 21b protrudes from inside the sprocket body 1a toward the electric motor 12 through the through hole 15e of the front plate 15. This cylindrical portion 21b and the intermediate member 30 form an Oldham coupling.

In other words, the cylindrical portion 21b has a two-sided fitting hole 21d formed therein into which the cylindrical base portion 31 of the intermediate member 30 can be fitted from the axial direction. A pair of crescent-shaped protrusions (not shown) that form the two-sided width are provided at approximately 180° positions in the circumferential direction on the inner surface of the fitting hole 21d. In addition, a pair of key grooves 21c, 21c are formed at approximately the center positions in the top and bottom of the pair of protrusions in FIG. 1 into which the two transmission keys 33a, 33b of the cylindrical base portion 31 can be fitted from the rotation axis direction. Each of these key grooves 21c, 21c is formed in a rectangular shape similar to each of the transmission keys 33a, 33b, and its depth is set to be approximately the same length as the width of each of the transmission keys 33a, 33b.

The pair of protrusions function as a suppression section that suppresses excessive supply of lubricating oil supplied from the lubricating oil supply mechanism described below to the electric motor 12 (Oldham coupling).

The needle bearing 25 has a number of needle rollers 25a that roll on the outer circumferential surface 14e of the head 14a of the cam bolt 14, and a cylindrical shell 25b that is fixed to a stepped surface formed on the inner circumferential surface of the eccentric cam shaft 21a and has a number of grooves that hold the needle rollers 25a rotatably on the inner circumferential surface.

As shown in Figures 1 to 3, the ball bearing 22 is arranged so that it overlaps the needle bearing 25 in the radial direction. The ball bearing 22 is composed of 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 that holds the balls 22c.

The inner ring 22a is press-fitted and fixed to the outer peripheral surface of the eccentric camshaft 21a, while the outer ring 22b is free and not fixed in the axial direction. In other words, one end face of the outer ring 22b on the electric motor 12 side in the axial direction is in a non-contact state with the inner surface of the inner peripheral portion 15c of the front plate 15 through a small gap C1. The other axial end face of the outer ring 22b is also in a non-contact state with the back surface of the deformation portion 24d (described later) of the retainer 24 that faces it through a small gap C2. As a result, the outer ring 22b has one axial end face restricted by the inner peripheral portion 15c from moving in one axial direction, and the other axial end face is restricted by the deformation portion 24d from moving excessively in the other axial direction.

The rollers 23 rollably contact the outer peripheral surface of the outer ring 22b. A crescent-shaped clearance (not shown) is formed between the outer peripheral surface of the outer ring 22b and the outer surface of each roller 23 of the cage 24. Therefore, the entire ball bearing 22 can move eccentrically in the radial direction via the clearance in response to the eccentric rotation of the eccentric camshaft 21a.

The retainer 24 is formed into a substantially disk-like shape by press molding a metal plate, and is disposed in contact with the front end side of the disk-shaped groove 9g of the driven member 9. In other words, the retainer 24 has a disk-shaped base 24a that axially contacts the bottom surface of the disk-shaped groove 9g of the disk-shaped main body 9a of the driven member 9, and a cage portion 24b that is integrally formed on the outer periphery of the base 24a and holds a number of rollers 23, which are meshing members. The retainer 24 is made harder than the driven member 9 by, for example, induction hardening after the entire retainer is press molded.

The base 24a has a bolt hole 24c formed in the center through which the shaft 14b of the cam bolt 14 is inserted, and on the outer periphery is an annular deformation portion 24d that is bent in a concave crank shape toward the ball bearing 22.

A U-shaped oil groove 24e is formed along the radial direction on the edge of the bolt hole 24c, with the other end of the lubricating oil introduction hole 28 of the driven member 9 opening. In addition, this oil groove 24e can be connected to each lubricating oil discharge hole 32 of the front plate 15 via the inside of the ball bearing 22.

The base 24a also has a pin insertion hole formed through it, through which a positioning pin (not shown) is inserted, at a position opposite the oil groove 24e across the bolt hole 24c.

The cage portion 24b is formed in a circular ring shape extending from the outer periphery of the deformation portion 24d toward the electric motor 12, and multiple retaining holes 24h that hold each roller 23 are formed radially at equally spaced positions in the circumferential direction.

Each of the multiple retaining holes 24h is formed as an elongated rectangular hole extending from the base edge of the cage portion 24b on the deformed portion 24d side to the tip edge, with the tip side closed. Inside the retaining holes 24h, the rollers 23 are held so that they can roll, and the total number of rollers 23 is less than the total number of teeth of the internal teeth 5a of the internal teeth component 5, thereby obtaining a predetermined reduction ratio.

Each roller 23 is made of an iron-based metal, and moves radially in response to the eccentric movement of the ball bearing 22 while fitting (meshing) with each internal tooth 5a of the internal tooth component 5. Each roller 23 swings radially while being guided circumferentially by both axial side edges of each retaining hole 24h.

In addition, as shown in FIG. 3, each roller 23 is arranged to be able to roll only on the internal teeth 5a of the internal teeth component 5 within the axial length of the retaining hole 24h.

As shown in Figs. 1 and 3, the outer diameter of the retainer 24 (cage portion 24b) is smaller than the outer diameter of the journal portion 11 of the driven member 9. When the retainer 24 is axially attached to the driven member 9, the outer peripheral edge of the cage portion 24b on the driven member 9 side abuts against the inner peripheral edge of the journal portion 11 in the axial direction.

The inside of the reducer 13 is supplied with lubricating oil via a lubricating oil supply mechanism to lubricate the internal moving parts. That is, the lubricating oil supply mechanism has an oil supply passage 4 formed in one end 2a of the camshaft 2, a lubricating oil introduction hole 28 formed on the inner circumference of the bolt insertion hole 9b of the driven member 9, an oil groove 24e formed radially from the hole edge of the bolt hole 24c of the retainer 24, and an oil pump (not shown) that supplies lubricating oil to the oil supply passage 4.

The oil supply passage 4 has an axial passage section 4a formed along the axial direction within one end 2a of the camshaft 2, and a radial passage section 4b formed along the radial direction on the tip surface of the one end 2a of the camshaft and communicating with the downstream end of the axial passage section 4a. The upstream end of the axial passage section 4a is connected to a main oil gallery (not shown), which is a supply passage that supplies lubricating oil to the inside of the internal combustion engine. The radial passage section 4b has one end on the outer diameter side connected to the axial passage section 4a, and the other end on the inner diameter side communicating with the lubricating oil introduction hole 28.

As described above, the lubricant oil introduction hole 28 is formed in an arc shape on the inner circumferential surface of the bolt insertion hole 9b, and communicates with the oil groove 24e of the cage 24 and also communicates with each lubricant oil discharge hole 32 via the inside of the ball bearing 22, etc. As described above, the lubricant oil introduction hole 28 is formed so that its cross-sectional area D1 (mm ² ) is smaller than the total cross-sectional area D (mm ² ) of the six lubricant oil discharge holes 32. In other words, the total cross-sectional area D of the six lubricant oil discharge holes 32 is formed larger than the cross-sectional area D1 of the lubricant oil introduction hole 28. The cross-sectional area of the oil groove 24e is formed so as to be larger than the cross-sectional area D1 of the lubricant oil introduction hole 28.

The oil pump is a common type, such as a trochoid type, and is designed to forcibly supply lubricating oil to the main oil gallery that is connected to the inside of the internal combustion engine, and then supply lubricating oil to the reducer 13 via the oil supply passage 4 and the lubricating oil introduction hole 28, etc.

The inside of the reducer 13 from the lubricating oil inlet hole 28 to the lubricating oil outlet hole 32 is configured as a lubricating oil passage.

The control unit detects the 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, an accelerator opening sensor, etc. (not shown), and controls the engine based on this. The control unit also controls the rotation of the motor shaft 17 by energizing the coil of the electric motor 12 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 reducer 13.
[Effects of this embodiment]
The operation of the valve timing control device of this embodiment will be briefly described below. First, when the timing sprocket 1 rotates via the timing chain in accordance with the rotational drive of the engine crankshaft, this rotational force is transmitted to the internal teeth forming member 5. The rotational force of this internal teeth forming member 5 is transmitted from each roller 23 via the cage 24 and the driven member 9 to the camshaft 2. As a result, the drive cam of the camshaft 2 opens and closes each intake valve.

When the engine is operating as specified after starting, a control current from the control unit is applied to the coil of the electric motor 12, driving the motor shaft 17 to rotate forward and backward. The rotational force of this motor shaft 17 is transmitted to the eccentric shaft member 21 via the Oldham coupling, and the reduced rotational force is transmitted to the camshaft 2 by the operation of the reducer 13.

As a result, the camshaft 2 rotates forward and backward relative to the timing sprocket 1, changing the relative rotation phase. Therefore, the opening and closing timing of each intake valve is controlled to be advanced or retarded.

In this way, the intake valve opening and closing timing is continuously shifted to the advanced or retarded side, improving engine performance such as fuel economy and power output.

In this embodiment, the lubricating oil discharged from the oil pump flows from the oil supply passage 4 through the lubricating oil introduction hole 28 and the oil groove 24e into the inside of the reducer 13. As shown by the arrows in Figure 3, the lubricating oil that flows into the reducer 13 passes through the gap between the inner ring 22a and the outer ring 22b of the ball bearing 22, between the outer peripheral retainer 24 and each roller 23, and between each internal tooth 5a, due to the centrifugal force during operation, to lubricate the gap.

The lubricating oil that flows into the reducer 13 flows between the bearing recess 10 and the journal portion 11. In other words, the lubricating oil passes between both end faces and the outer peripheral surface of the journal portion 11 and the sliding bearing surface 10a of the bearing recess 10 and the annular inner surface 8g of the first annular restricting portion 8, and is used for lubrication.

After effectively lubricating the moving parts inside the reducer 13, the lubricating oil can be quickly discharged to the outside through each lubricating oil discharge hole 32.

That is, the six lubricating oil discharge holes 32 are set so that their total cross-sectional area D is larger than the cross-sectional area D1 of the lubricating oil introduction hole 28. Therefore, as described above, the lubricating oil supplied to the inside of the reducer 13 can be quickly discharged to the outside from each lubricating oil discharge hole 32 while lubricating the ball bearing 22, and the space between the internal teeth 5a and the roller 23 and the retaining hole 24h. In other words, after lubricating the ball bearing 22, etc., the supplied lubricating oil can be quickly discharged to the outside from each lubricating oil discharge hole 32 without remaining in the reducer 13.

This makes it possible to resolve the technical problem of the prior art described in the publication above, for example, that the mechanical drive speed of the valve timing control device decreases due to the viscous resistance of the lubricating oil when starting the internal combustion engine.

In particular, each lubricant discharge hole 32 is provided radially outward from the outer ring 22b of the ball bearing 22. Therefore, the lubricant supplied to the reducer 13 lubricates the ball bearing 22 by centrifugal force during operation, but is not stored there, and instead moves directly outward and is discharged to the outside from each lubricant discharge hole 32. Therefore, the ball bearing 22 is prevented from generating driving resistance due to the viscous resistance of the lubricant.

In addition, in this embodiment, the lubricating oil after lubricating the inside of the reducer 13 is quickly collected inside the annular recess 26 and is quickly discharged from this annular recess 26 directly to the outside through each lubricating oil discharge hole 32. Therefore, the lubricating oil is prevented from accumulating inside the reducer.

When the engine is running, the lubricating oil in the reducer 13 is collected in the annular recess 26, which also functions as a temporary oil reservoir. This improves the lubrication between the internal teeth 5a around the annular recess 26 and the roller 23. When the engine is stopped, a small amount of lubricating oil can be retained in the annular recess 26, improving the lubrication of the rolling bearings when the engine is started.

In other words, in the prior art described in the publication, each oil drain hole is formed in a radial position that straddles the gear meshing portion that is located radially outward of the outer ring of the ball bearing, so although it is possible to discharge contaminants, if the amount of lubricating oil supplied to the reducer is small, there is a risk that the amount of lubricating oil will be insufficient, resulting in a decrease in lubrication of the gear portion that is under heavy load.

However, in this embodiment, as described above, the annular recess 26 functions as a temporary oil reservoir, improving lubrication between the internal teeth 5a around the annular recess 26 and the roller 23, etc.

Furthermore, because a portion of the annular recess 26 is located radially outward from the gap between the bottom surface of the internal tooth 5a and the roller 23, contaminants such as metal powder generated from each component of the internal combustion engine and the reducer 13 can be collected in the annular recess 26 by the centrifugal force during operation.

The annular recess 26 is formed in the wall of the front plate 15 in a circular shape that surrounds the outer ring 22b of the ball bearing 22. This improves the lubrication of the entire ball bearing 22, including the outer ring 22b, by the lubricating oil collected in the annular recess 26.

In addition, six grooves 27 are provided on the outer periphery of the annular recess 26, and each groove 27 functions as a pocket, so that the amount of lubricating oil collected in the annular recess 26 increases. As the amount of lubricating oil stored increases, the lubrication of the ball bearings 22 of the reducer 13 and the like is further improved. Also, it becomes possible to effectively store contaminants in each groove 27 that functions as a pocket.

In addition, because each bolt 7 is disposed between adjacent grooves 27 in the circumferential direction, the space in which the bolts 7 are disposed can be effectively utilized. As a result, the entire device can be made smaller in the radial direction.

Furthermore, according to this embodiment, a minute gap C1 is formed between the front plate 15 and the end face facing the outer ring 22b of the ball bearing 22 in the direction of the rotation axis, and this minute gap C1 can be used as a flow path for lubricating oil, so that the lubricating oil introduced into the reducer 13 from the lubricating oil introduction hole 28 can be quickly supplied to the ball bearing 22, the annular recess 26, etc.

As mentioned above, centrifugal force acts on the lubricating oil during operation, so the lubricating oil moves outward from each lubricating oil discharge hole 32 and adheres to the bottom surface of each internal tooth 5a, where it is stored. This improves the lubrication between the bottom surface of each internal tooth 5a and the roller 23.

The present invention is not limited to the configuration of the above embodiment, and for example, the engaging member can be a gear other than the roller 23. In other words, the reducer can be a planetary gear reducer described in JP 2019-85910 other than a roller reducer.

1...timing sprocket (driving rotor), 1a...sprocket body, 1b...external teeth, 1c...large diameter section, 1d...female thread hole, 2...camshaft, 2a...one end, 3...phase change mechanism, 4...oil supply passage, 4a...axial passage section, 4b...radial passage section, 5...internal teeth component, 5a...internal teeth, 7...bolt, 7a...shaft section, 7b...male thread section, 9...driven member (driven rotor), 12...electric motor, 13...reduction gear, 21...eccentric shaft member (input shaft), 22...ball bearing (rolling bearing), 22a...inner ring, 22b...outer ring, 26...annular recess (recess), 27...recess groove, 28...lubricant inlet hole, 32...lubricant outlet hole, D...total cross-sectional area of lubricant outlet holes, D1...opening cross-sectional area of lubricant inlet hole.

Claims (10)

a drive rotor to which rotational force from a crankshaft is transmitted;
a driven rotor coupled to a camshaft and rotatable relative to the driving rotor;
a reducer provided between the driving rotor and the driven rotor, the reducer rotating the driven rotor relative to the driving rotor as an input shaft rotates;
A valve timing control device for an internal combustion engine having
A rolling bearing disposed on an outer periphery of the input shaft;
a cover member fixed to the driving rotor and covering an outer ring of the rolling bearing in the axial direction;
a lubricant oil introduction hole provided radially inward of an inner ring of the rolling bearing of the driven rotor and communicating with a supply passage that supplies lubricant oil to an internal combustion engine;
a plurality of lubricant oil discharge holes formed through the cover member, the plurality of lubricant oil discharge holes having a total cross-sectional area larger than a cross-sectional area of the lubricant oil introduction hole;
a lubricant oil passage that communicates the lubricant oil inlet hole and the plurality of lubricant oil outlet holes via a gap between the inner ring and the outer ring of the rolling bearing;
A valve timing control device for an internal combustion engine comprising: 2. The valve timing control device for an internal combustion engine according to claim 1,
The cover member has an inner surface on the rolling bearing side formed with a recess,
a plurality of lubricating oil drain holes formed through a bottom wall of the recess, the plurality of lubricating oil drain holes being disposed in the bottom wall of the recess. 3. The valve timing control device for an internal combustion engine according to claim 2,
The speed reducer has annular internal teeth formed on an inner periphery of the drive rotor, and a meshing member that meshes with the internal teeth,
13. A valve timing control device for an internal combustion engine, wherein at least a portion of the recess is located radially outward from a gap between a bottom surface of the internal tooth and the meshing member. 3. A valve timing control device for an internal combustion engine according to claim 2,
2. A valve timing control device for an internal combustion engine, wherein the recess is formed in a wall portion of the cover member in an annular shape so as to surround an outer ring of the rolling bearing. 5. The valve timing control device for an internal combustion engine according to claim 4,
A plurality of grooves recessed radially outward are provided at an outer circumferential edge of the annular recess at predetermined intervals in a circumferential direction,
2. A valve timing control device for an internal combustion engine, wherein the lubricant oil discharge hole is formed in a portion of the recess where each of the recessed grooves is located. 6. The valve timing control device for an internal combustion engine according to claim 5,
The cover member is fixed to the drive rotor by a plurality of bolts,
4. A valve timing control device for an internal combustion engine, wherein each of the bolts is disposed between each of the plurality of recessed grooves in the circumferential direction. 2. The valve timing control device for an internal combustion engine according to claim 1,
13. A valve timing control device for an internal combustion engine, wherein a gap is formed between the cover member and an end face facing in the axial direction of the outer ring of the rolling bearing. 2. The valve timing control device for an internal combustion engine according to claim 1,
The speed reducer has annular internal teeth formed on an inner periphery of the drive rotor and a meshing member that meshes with the internal teeth,
2. A valve timing control device for an internal combustion engine, wherein the plurality of lubricant oil discharge holes are provided radially inward of bottom surfaces of the internal teeth. 9. A valve timing control device for an internal combustion engine according to claim 8,
2. A valve timing control device for an internal combustion engine, wherein the plurality of lubricant oil drain holes are provided radially outward of an outer ring of the rolling bearing. a drive rotor to which rotational force from a crankshaft is transmitted;
a driven rotor coupled to a camshaft and rotatable relative to the driving rotor;
a reducer provided between the driving rotor and the driven rotor, the reducer rotating the driven rotor relative to the driving rotor as an input shaft rotates;
A valve timing control device for an internal combustion engine having
A rolling bearing disposed on an outer periphery of the input shaft;
a cover member fixed to the driving rotor and covering an outer ring of the rolling bearing in the axial direction;
a lubricant oil introduction hole provided radially inward of an inner ring of the rolling bearing of the driven rotor and communicating with a supply passage that supplies lubricant oil to an internal combustion engine;
A plurality of lubricant oil drain holes formed through the cover member;
a lubricant oil passage that communicates the lubricant oil inlet hole and the plurality of lubricant oil outlet holes via a gap between the inner ring and the outer ring of the rolling bearing;
Equipped with
a lubricating oil supply hole that supplies lubricating oil from the lubricating oil supply hole to an inside of the reducer while the internal combustion engine is in operation, the lubricating oil supply hole having an inner diameter that enables the lubricating oil to be quickly discharged to the outside by centrifugal force through the inside of the reducer.

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