Valve timing control device

Abstract

To provide a valve opening / closing timing control device preventing a possibility of generation of looseness of a fastening bolt even if an Oldham coupling has been broken.SOLUTION: A valve opening / closing timing control device 100 includes: a driving side rotating body A; a driven side rotating body B disposed on an inner side of the driving side rotating body A; and a phase adjusting mechanism C for setting a relative rotation phase of the driving side rotating body A and the driven side rotating body B. The phase adjusting mechanism C includes: an output gear 25 provided in the driven side rotating body B; an input gear 30 coupled to the driving side rotating body A via an Oldham coupling Cx and engaging with the output gear 25; and a cylindrical eccentric member 26 for rotating the input gear 30. The Oldham coupling Cx includes: an annular part 41; an outer engaging arm 42; an inner engaging arm 43; and a projecting part 44 projecting from the annular part 41 between the outer engaging arm 42 and the inner engaging arm 43 that are adjacent to each other in a circumferential direction.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a valve timing control device. [Background technology]

[0002] In recent years, valve timing control devices that can change the opening and closing timings of intake valves and exhaust valves depending on the operating conditions of an internal combustion engine (hereinafter also referred to as "engine") have been put into practical use. These valve timing control devices have a mechanism that changes the opening and closing timings of the intake and exhaust valves that open and close in accordance with the rotation of the driven-side rotor, for example, by changing the relative rotational phase (hereinafter also simply referred to as "relative rotational phase") of the driven-side rotor with respect to the rotation of the driving-side rotor caused by the operation of the engine.

[0003] Patent Document 1 describes a valve timing control device that controls the opening and closing timing of intake valves in an internal combustion engine, which are opened and closed by rotating a camshaft as a result of the rotation of the crankshaft being transmitted. This valve timing control device includes a drive-side rotor that rotates synchronously with the crankshaft about its rotational axis, a driven-side rotor that is coaxial with the rotational axis and is located inside the drive-side rotor and rotates integrally with the camshaft, and a phase adjustment mechanism that changes the relative rotational phase using the driving force of a phase control motor.

[0004] The phase adjustment mechanism in this valve timing control device includes an output gear that is provided on the driven rotor and is coaxial with the rotational axis, an input gear that rotates on an eccentric axis that is parallel to the rotational axis and is connected to the drive rotor via an Oldham coupling, and a cylindrical eccentric member that supports the input gear from the inside so that the input gear rotates about the eccentric axis, and the driving force of the phase control motor rotates the eccentric member to revolve the eccentric axis, changing the meshing position between the output gear and the input gear, thereby changing the relative rotational phase.

[0005] The drive-side rotor in this valve timing control device is configured by fastening an outer case, on the outer periphery of which is formed a drive sprocket to which rotation from the crankshaft is transmitted, to a front plate using a plurality of fastening bolts. The front plate has a plurality of protrusions formed toward the driven rotor that restrict axial movement of the driven rotor. These protrusions ensure a predetermined axial gap between the Oldham coupling and the driven rotor, allowing the Oldham coupling to operate smoothly. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-17833 Summary of the Invention [Problem to be solved by the invention]

[0007] In a valve timing control device such as the one described above, if abnormal torque (e.g., cam fluctuation torque) is input from the outside (e.g., a camshaft), the abnormal torque is transmitted from the output gear via the input gear to the Oldham coupling, which may result in the Oldham coupling cracking and breaking. If the Oldham coupling breaks, it will no longer be able to regulate the movement of the input gear due to the input of cam fluctuation torque, and the movement of the input gear may cause the Oldham coupling to collide with a convex portion of the front plate. If the Oldham coupling repeatedly collides with the convex portion, the impact may loosen the fastening bolts that fasten the front plate to the outer case.

[0008] Therefore, there is a demand for a valve timing control device that does not have the risk of the fastening bolts loosening even if the Oldham coupling is damaged. [Means for solving the problem]

[0009] A characteristic configuration of a valve timing control device according to the present invention includes a drive-side rotor that rotates synchronously with a crankshaft of an internal combustion engine about a rotational axis, a driven-side rotor that is coaxial with the rotational axis and is disposed inside the drive-side rotor and rotates integrally with a camshaft for opening and closing valves of the internal combustion engine, and a phase adjustment mechanism that sets a relative rotational phase between the drive-side rotor and the driven-side rotor, the phase adjustment mechanism including an output gear that is coaxial with the rotational axis and disposed on the driven-side rotor, an input gear that rotates about an eccentric axis parallel to the rotational axis, is connected to the drive-side rotor via an Oldham coupling, and meshes with the output gear, and a bearing that supports the input gear from the inner peripheral side and supports the input gear. and a cylindrical eccentric member that rotates the output gear and the input gear, wherein rotation of the eccentric member about the rotation axis revolves the eccentric axis to change the meshing position between the output gear and the input gear, and the Oldham coupling is arranged to overlap with the drive-side rotating body when viewed in a radial direction perpendicular to the rotation axis, and the Oldham coupling has an annular portion, an external engagement arm extending radially outward from the annular portion along a first direction, an internal engagement arm extending radially outward from the annular portion along a second direction intersecting the first direction, and a protrusion protruding radially outward from the annular portion between the external engagement arm and the internal engagement arm that are adjacent to each other in the circumferential direction.

[0010] With the above configuration, if the internal engagement arm of the Oldham coupling breaks, the Oldham coupling becomes movable and the protruding portion of the Oldham coupling collides with the drive-side rotor. However, the drive-side rotor, which has a large mass, can absorb the impact caused by the collision of the protruding portion.

[0011] A further characteristic configuration of the valve timing control device according to the present invention is that the driving-side rotor has an outer case and a front plate fixed to the outer case with a fastening bolt and arranged adjacent to the Oldham coupling in the direction along the rotation axis, the Oldham coupling is arranged between the front plate and the driven-side rotor and overlaps with the outer case when viewed in the radial direction, the front plate has a convex portion that protrudes toward the driven-side rotor, and a second distance, which is the distance between the protrusion and the inner wall surface of the outer case, is shorter than a first distance, which is the distance between the internal engaging arm and the convex portion in the extension direction of the external engaging arm.

[0012] If the internal engagement arm of the Oldham coupling breaks, the two Oldham couplings will separate and become movable. This may cause the internal engagement arm to collide with the protrusion on the front plate. If the internal engagement arm repeatedly collides with the protrusion, the impact may cause the fastening bolts that fasten the front plate and outer case to loosen.

[0013] However, with the above configuration, the protrusion collides with the inner wall surface of the outer case before the broken internal engaging arm collides with the convex portion of the front plate, preventing further displacement of the internal engaging arm. Specifically, when the Oldham coupling is in a normal state with no broken internal engaging arm, the distance between the protrusion of the Oldham coupling and the inner wall surface of the outer case is shorter than the distance between the internal engaging arm and the convex portion of the front plate. This prevents the internal engaging arm from colliding with the convex portion of the front plate. Because the mass of the outer case is greater than the mass of the front plate, even if the protrusion collides with the inner wall surface of the outer case, the outer case absorbs the impact of the collision, and vibrations associated with the impact are less likely to be transmitted to the fastening bolt. As a result, there is no risk of loosening of the fastening bolt fastening the front plate to the outer case.

[0014] A further characteristic feature of the valve timing control device according to the present invention is that the protruding portion has a first reference surface and a second reference surface that are perpendicular to each other.

[0015] According to the above configuration, when manufacturing the Oldham coupling, the protruding portion can be clamped in a chuck and machined using the first reference surface and the second reference surface as references, so that the Oldham coupling can be manufactured with high precision.

[0016] A further characteristic feature of the valve timing control device according to the present invention is that the first reference surface of the protrusion is Among them, the one perpendicular to the second direction the second reference surface is parallel to the first side surface of the inter-engagement arm; Among them, the one perpendicular to the first direction Parallel to the second side The first side surface slides against a guide groove formed on an outer case of the driving-side rotor, and the second side surface slides against an engaging protrusion formed on the input gear. The point is that

[0017] According to the above configuration, the external engagement arm Of which, perpendicular to the second direction When machining the first side surface, a first reference surface parallel to the first side surface is clamped by a chuck. This allows the first side surface to be machined with high precision using the first reference surface as a reference. Of which, perpendicular to the first direction Similarly, for the second side surface, a second reference surface parallel to the second side surface is clamped by the chuck, which allows the second side surface to be machined with high precision using the second reference surface as a reference. As a result, the first side surface can be smoothly slid along the guide groove formed in the outer case of the drive-side rotor, and the second side surface can be smoothly slid along the engagement protrusion formed on the input gear. do. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 2 is a cross-sectional view of the valve timing control device. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 2 is an exploded perspective view of the valve timing control device. [Figure 6] FIG. 4 is a partially enlarged cross-sectional view of the periphery of a protrusion of the front plate. [Figure 7]FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 1, showing a state in which the Oldham coupling is broken. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0020] [Basic configuration] As shown in FIG. 1, the valve timing control device 100 according to this embodiment includes a drive-side rotor A that rotates synchronously with a crankshaft 1 of an engine E as an internal combustion engine, an intake camshaft 2 (an example of a camshaft) that opens and closes an intake valve 2B (an example of a valve), a driven-side rotor B that rotates integrally with the intake camshaft 2 around a rotation axis X, and a phase adjustment mechanism C that sets the relative rotational phase (hereinafter also simply referred to as the "relative rotational phase") between the drive-side rotor A and the driven-side rotor B using the driving force of a phase control motor M.

[0021] The engine E is a four-stroke engine in which pistons 4 are housed in multiple cylinders 3 formed in a cylinder block, and the pistons 4 are connected to a crankshaft 1 by connecting rods 5. A timing chain 6 (which may be a timing belt or the like) is wound around an output sprocket 1S of the crankshaft 1 of the engine E and a drive sprocket 11S of the drive-side rotor A.

[0022] As a result, when the engine E is running, the entire valve timing control device 100 rotates around the rotational axis X. In addition, the driving force of the phase control motor M operates the phase adjustment mechanism C, which makes it possible to displace the driven rotor B in the same direction as the rotational direction or in the opposite direction relative to the driving rotor A. This displacement by the phase adjustment mechanism C sets the relative rotational phase between the driving rotor A and the driven rotor B, thereby realizing control of the opening and closing timing of the intake valve 2B by the cam 2A of the intake camshaft 2.

[0023] The operation in which the driven-side rotor B is displaced relatively in the same direction as the rotational direction of the driving-side rotor A is called advance operation, and this advance operation increases the intake compression ratio. On the other hand, the operation in which the driven-side rotor B is displaced relatively in the opposite direction to the driving-side rotor A (operation in the opposite direction to advance operation) is called retard operation, and this retard operation reduces the intake compression ratio.

[0024] [Valve timing control device] As shown in Fig. 1, the drive-side rotating body A is configured by fastening an outer case 11, which has a drive sprocket 11S formed on its outer periphery, to a front plate 12 with a plurality of fastening bolts 13. The outer case 11 is a cylindrical type with a bottom and an opening at the bottom.

[0025] 1 to 4, an intermediate member 20 (see FIG. 2, etc.) serving as a driven rotor B and a phase adjustment mechanism C (see FIG. 3, etc.) having a hypotrochoid gear reduction mechanism are housed in the internal space of the outer case 11. The phase adjustment mechanism C also includes an Oldham coupling Cx (see FIG. 4, etc.) that reflects a phase change in the drive rotor A and the driven rotor B.

[0026] The intermediate member 20 constituting the driven-side rotor B is integrally formed with a support wall 21 connected to the intake camshaft 2 in an orientation perpendicular to the rotation axis X, and a cylindrical wall 22 that is cylindrical and centered on the rotation axis X and protrudes from the outer edge of the support wall 21 in a direction away from the intake camshaft 2.

[0027] The intermediate member 20 is fitted so as to be relatively rotatable with the outer surface of the cylindrical wall 22 in contact with the inner surface of the outer case 11, and is fixed to the end of the intake camshaft 2 by a connecting bolt 23 inserted into a through-hole in the center of the support wall 21. When fixed in this manner, the outer end of the cylindrical wall 22 (the end farther from the intake camshaft 2) is positioned inside the front plate 12.

[0028] 1 and 5, a groove 22a is formed around the entire outer periphery of the cylindrical wall 22. The groove 22a improves the oil retention between the outer surface of the cylindrical wall 22 and the inner surface of the outer case 11. This reduces the friction between the cylindrical wall 22 and the outer case 11, allowing the intermediate member 20 to rotate smoothly relative to the outer case 11.

[0029] As shown in Fig. 1, the phase control motor M is supported on the engine E by a support frame 7 so that its output shaft Ma is arranged coaxially with the rotation axis X. A pair of engagement pins 8 are formed on the output shaft Ma of the phase control motor M, and are oriented perpendicular to the rotation axis X (see also Figs. 3 and 4).

[0030] [Phase adjustment mechanism] 1 and 5, the phase adjustment mechanism C includes an intermediate member 20, an output gear 25 formed on the inner peripheral surface of the cylindrical wall 22 of the intermediate member 20, an eccentric member 26, an elastic member S, a first bearing 28, a second bearing (an example of a bearing) 29, an input gear 30, a fixed ring 31, a ring-shaped spacer 32, and an Oldham coupling Cx. Note that rolling bearings are used for the first bearing 28 and the second bearing 29, but plain bearings can also be used.

[0031] As shown in FIG. 1, a support surface 22S centered on the rotation axis X is formed on the inner periphery of the cylindrical wall 22 of the intermediate member 20 in the direction along the rotation axis X (hereinafter also referred to as the "axial direction") on the inside (at a position adjacent to the support wall 21), and an output gear 25 centered on the rotation axis X is integrally formed outside the support surface 22S (on the side farther from the intake camshaft 2).

[0032] As shown in Figures 1, 2, and 5, the eccentric member 26 is cylindrical. A circumferential support surface 26S is formed on the axially inner side (the side closer to the intake camshaft 2) of the eccentric member 26, with the outer peripheral surface being centered on the rotational axis X. As shown in Figures 1, 3, and 5, an eccentric support surface 26E is formed on the outer side (the side farther from the intake camshaft 2) of the eccentric member 26, with the outer peripheral surface being centered on an eccentric axis Y that is eccentric and parallel to the rotational axis X. Because the direction along the eccentric axis Y is the same as the axial direction, hereinafter, the direction along the eccentric axis Y will also be simply referred to as the axial direction.

[0033] 3 and 5, a recess 70 recessed inward along the radial direction of the eccentric member 26 is formed on the eccentric support surface 26E of the eccentric member 26. As will be described later, an elastic member S is fitted into the recess 70. The relationship between the recess 70 and the elastic member S will be described later together with an explanation of the elastic member S.

[0034] As shown in FIGS. 1 to 5, a pair of engagement grooves 26T (see FIGS. 3 and 4) that can engage with a pair of engagement pins 8 of a phase control motor M (see FIG. 1) are formed on the inner periphery of the eccentric member 26 parallel to the rotation axis X. Furthermore, a plurality of first lubricating oil grooves 26a (see FIG. 1) are formed on the inner side (the side of the support wall 21) of the eccentric member 26 and oriented along the radial direction, and a plurality of second lubricating oil grooves 26b are formed on the outer side (the side farther from the intake camshaft 2) and oriented along the radial direction. Note that the eccentric member 26 may be formed with only one of the first lubricating oil grooves 26a and the second lubricating oil grooves 26b. The number of first lubricating oil grooves 26a and the number of second lubricating oil grooves 26b may be set arbitrarily.

[0035] 5, tapered portions 26c (inclined portions) whose diameter decreases toward the inside (the side closer to the intake camshaft 2) are formed on both sides of the engagement groove 26T on the inner circumferential side of the open end on the outside (the side farther from the intake camshaft 2) of the eccentric member 26. When the pair of engagement pins 8 of the phase control motor M are engaged with the engagement grooves 26T of the eccentric member 26, the engagement pins 8 are guided into the engagement grooves 26T by the tapered portions 26c, which makes it easier to engage the phase control motor M with the eccentric member 26.

[0036] 1 and 2, a first bearing 28 is fitted onto the circumferential support surface 26S of the eccentric member 26, and the first bearing 28 is fitted into the support surface 22S of the cylindrical wall 22, so that the eccentric member 26 is rotatably supported about the rotation axis X with respect to the intermediate member 20. Also, as shown in FIGS. 1 and 3, the input gear 30 is supported by the eccentric support surface 26E of the eccentric member 26 via a second bearing 29 so as to be rotatable about the eccentric axis Y.

[0037] In this phase adjustment mechanism C, the number of teeth of the external teeth 30A of the input gear 30 is set to be one tooth less than the number of teeth of the internal teeth 25A of the output gear 25. Also, only a portion of the external teeth 30A of the input gear 30 is configured to mesh with a portion of the internal teeth 25A of the output gear 25.

[0038] The elastic member S applies a biasing force to the input gear 30 via the second bearing 29 so that a portion of the external teeth 30A of the input gear 30 meshes with a portion of the internal teeth 25A of the output gear 25. This prevents the backlash between the input gear 30 and the output gear 25 from increasing, thereby preventing abnormal noise. This also improves the durability of the input gear 30 and the output gear 25.

[0039] The elastic member S is configured to include a pair of spring members 71, 71. In this embodiment, the pair of spring members 71, 71 have the same shape and the same size. As shown in FIG. 5, the spring member 71 is formed by bending a spring plate material into a predetermined shape. The pair of spring members 71, 71 are combined in opposite directions (line symmetrical along the radial direction of the eccentric member 26) to form an integrated elastic member S, which is fitted into the recess 70.

[0040] As shown in FIGS. 1 and 6, the fixing ring 31 is supported in a fitted state on the outer periphery of the eccentric member 26, and prevents the second bearing 29 from coming off via the spacer 32.

[0041] [Oldham coupling] As shown in FIGS. 1, 4, and 5, the Oldham coupling Cx is composed of a plate material integrally formed with a central annular portion 41, a pair of external engagement arms 42 extending radially outward from the annular portion 41 in a first direction (left-right direction in FIG. 4), an internal engagement arm 43 extending radially outward from the annular portion 41 in a second direction (up-down direction in FIG. 4) that is perpendicular to the first direction, and multiple (four in this embodiment) protrusions 44 protruding radially outward from the annular portion 41 between the external engagement arm 42 and the internal engagement arm 43 adjacent in the circumferential direction. Each of the pair of internal engagement arms 43 is formed with an engagement recess 43a that continues to the opening of the annular portion 41. In other words, the internal engagement arm 43 is formed in a U-shape. Note that the external engagement arm 42 and the internal engagement arm 43 only need to extend in directions that intersect with each other, and do not necessarily need to extend in directions that are perpendicular to each other.

[0042] A pair of guide grooves 11a are formed in the outer case 11 at the opening edge against which the front plate 12 abuts, as through-grooves, extending from the interior space of the outer case 11 to the exterior space, radially from the rotation axis X. The groove width of these guide grooves 11a is set slightly wider than the width of the external engagement arm 42, and a pair of discharge flow paths 11b are cut out and formed in each guide groove 11a. Note that the discharge flow paths 11b may be formed to allow lubricating oil to flow radially relative to the front plate 12.

[0043] At the opening edge of the outer case 11, in a region other than the guide groove 11a, one or more pockets 11c are formed by cutting out the inner periphery along the circumferential direction. The pockets 11c collect foreign matter that moves to the outer periphery due to centrifugal force caused by the rotation of the drive-side rotor A. Figure 5 shows an example in which four pockets 11c are formed.

[0044] Furthermore, a pair of engagement protrusions 30T are integrally formed on the end surface of the input gear 30 that faces the front plate 12. The engagement width of these engagement protrusions 30T is set slightly narrower than the engagement width of the engagement recess 43a of the internal engagement arm 43.

[0045] With this configuration, the Oldham coupling Cx can be made to function by engaging the pair of outer engaging arms 42 of the Oldham coupling Cx with the pair of guide grooves 11a of the outer case 11 and engaging the pair of engaging projections 30T of the input gear 30 with the respective engaging recesses 43a of the pair of inner engaging arms 43 of the Oldham coupling Cx.

[0046] Specifically, when the meshing position of the external teeth 30A of the input gear 30 with the internal teeth 25A of the output gear 25 changes in accordance with a change in the relative rotational phase, the Oldham coupling Cx displaces in a first direction (left-right direction in FIG. 4 ) in which the external engagement arm 42 extends relative to the outer case 11, and in a second direction (up-down direction in FIG. 4 ) along the direction in which the engagement recesses 43a of the internal engagement arm 43 are formed, thereby following the displacement of the input gear 30. In other words, the Oldham coupling Cx follows the displacement of the input gear 30 and restricts excessive displacement of the input gear 30 by engaging the pair of engagement projections 30T of the input gear 30 with the pair of engagement recesses 43a. In the normal operating state of the valve timing control device 100, the projections 44 do not collide with the inner wall surface 11d of the outer case 11, even if the Oldham coupling Cx displaces in the up-down or left-right directions.

[0047] 1 and 6, the spacer 32 limits the distance of the gap through which the second bearing 29 can move in the axial direction to a predetermined set value or less. By providing the spacer 32 between the Oldham coupling Cx and the second bearing 29, the movement of the second bearing 29 in the axial direction is limited to a distance that is equal to or less than the predetermined set value. This makes it possible to prevent contact between the engaging protrusion 30T of the input gear 30 and the front plate 12.

[0048] [Layout of each part of the valve timing control device] 1, in the assembled valve timing control device 100, the support wall 21 of the intermediate member 20 is connected to the end of the intake camshaft 2 by a connecting bolt 23, and they rotate together. The eccentric member 26 is supported by a first bearing 28 so as to be rotatable relatively to the intermediate member 20 about the rotation axis X. As shown in FIGS. 1 and 3, the input gear 30 is supported by an eccentric support surface 26E of the eccentric member 26 via a second bearing 29, and a portion of the external teeth 30A of the input gear 30 meshes with a portion of the internal teeth 25A of the output gear 25.

[0049] 4, the outer engagement arms 42 of the Oldham coupling Cx engage with a pair of guide grooves 11a of the outer case 11, and the engagement projections 30T of the input gear 30 engage with the engagement recesses 43a of the inner engagement arms 43 of the Oldham coupling Cx. As shown in FIG. 1, the front plate 12 is disposed outside the Oldham coupling Cx (on the side farther from the intake camshaft 2), so that the Oldham coupling Cx can move in a direction perpendicular to the rotation axis X while contacting the inner surface of the front plate 12. With this arrangement, the Oldham coupling Cx is disposed outside both the first bearing 28 and the second bearing 29 (on the side farther from the intake camshaft 2) and inside the front plate 12 (on the side closer to the intake camshaft 2). In other words, the Oldham coupling Cx is disposed between the driven-side rotor B and the front plate 12 in the direction along the rotation axis X, and is disposed so as to overlap with the outer case 11 of the drive-side rotor A when viewed in the radial direction.

[0050] As shown in FIGS. 1 to 3, a pair of engagement pins 8 formed on the output shaft Ma of the phase control motor M are engaged with the engagement grooves 26T of the eccentric member 26.

[0051] [Operational form of phase adjustment mechanism] Although not shown in the drawings, the phase control motor M is controlled by a control device configured as an ECU. The engine E is equipped with sensors that can detect the rotational speeds (number of rotations per unit time) of the crankshaft 1 and the intake camshaft 2 and their respective rotational phases, and the detection signals of these sensors are input to the control device.

[0052] When the engine E is running, the control device maintains the relative rotational phase by driving the phase control motor M at a speed equal to the rotational speed of the intake camshaft 2. On the other hand, an advance operation is performed by reducing the rotational speed of the phase control motor M below the rotational speed of the intake camshaft 2, and conversely, a retard operation is performed by increasing the rotational speed. As described above, an advance operation increases the intake compression ratio, and a retard operation decreases the intake compression ratio.

[0053] When the phase control motor M rotates at the same speed as the outer case 11 (same speed as the intake camshaft 2), the meshing position of the external teeth 30A of the input gear 30 with the internal teeth 25A of the output gear 25 does not change, so the relative rotational phase of the driven side rotating body B with respect to the driving side rotating body A is maintained.

[0054] On the other hand, by driving and rotating the output shaft Ma of the phase control motor M at a speed higher or lower than the rotational speed of the outer case 11, the eccentric shaft Y in the phase adjustment mechanism C revolves around the rotational shaft X. This revolution displaces the meshing position of the internal teeth 25A of the output gear 25 with the external teeth 30A of the input gear 30 along the inner circumference of the output gear 25, and a rotational force acts between the input gear 30 and the output gear 25. In other words, a rotational force acts on the output gear 25 around the rotational shaft X, and a rotational force acts on the input gear 30 to rotate it around the eccentric shaft Y.

[0055] As described above, the input gear 30 does not rotate relative to the outer case 11 because its engagement projection 30T engages with the engagement recess 43a of the internal engagement arm 43 of the Oldham coupling Cx, and a rotational force acts on the output gear 25. The action of this rotational force causes the intermediate member 20, together with the output gear 25, to rotate about the rotation axis X relative to the outer case 11. As a result, the relative rotational phase between the drive-side rotor A and the driven-side rotor B is set, and the opening and closing timing of the intake camshaft 2 is set.

[0056] Furthermore, when the eccentric axis Y of the input gear 30 revolves around the rotation axis X, as the input gear 30 is displaced, the Oldham coupling Cx is displaced in the direction in which the external engagement arm 42 extends relative to the outer case 11 (first direction), and the input gear 30 is displaced in the direction in which the internal engagement arm 43 extends (second direction).

[0057] As described above, the number of teeth on the external teeth 30A of the input gear 30 is set to be one tooth less than the number of teeth on the internal teeth 25A of the output gear 25. Therefore, when the eccentric axis Y of the input gear 30 revolves around the rotation axis X by one revolution, the output gear 25 rotates by one tooth, thereby achieving a large reduction in speed.

[0058] [Lubrication of Phase Adjustment Mechanism] 1, the intake camshaft 2 is formed with a lubricating oil passage 15 to which lubricating oil is supplied from an external oil pump P via an oil passage forming member 9. Of the support wall 21 of the intermediate member 20, an opening 21a is formed in a part of the surface that abuts against the intake camshaft 2 to guide oil into the inside of the eccentric member 26.

[0059] As described above, the eccentric member 26 is formed with a plurality of first lubricating oil grooves 26a and a plurality of second lubricating oil grooves 26b (see FIGS. 1 and 5). Furthermore, the surface of the front plate 12 facing the Oldham coupling Cx is formed with a lubrication recess 12a that forms a small radial gap between the surface of the Oldham coupling Cx. Note that although this lubrication recess 12a is formed on the inner periphery of the front plate 12, it may also be formed in an area that reaches the outer periphery of the front plate 12, or the lubrication recess 12a may be omitted and lubricating oil may be supplied to the gap between the front plate 12 and the Oldham coupling Cx.

[0060] As described above, a pair of discharge flow paths 11b are formed in the guide groove 11a (see FIGS. 4 and 5). Furthermore, by making the opening diameter of the opening 12b in the front plate 12 sufficiently larger than the inner diameter of the eccentric member 26, a step G is formed between the opening edge of the front plate 12 and the inner periphery of the eccentric member 26.

[0061] With this configuration, the lubricating oil supplied from the oil pump P is supplied from the lubricating oil passage 15 of the intake camshaft 2 through the opening 21a in the support wall 21 of the intermediate member 20 to the internal space of the eccentric member 26. The lubricating oil supplied in this manner is supplied by centrifugal force from the first lubricating oil groove 26a of the eccentric member 26 to the first bearing 28, thereby allowing the first bearing 28 to operate smoothly.

[0062] At the same time, the lubricating oil in the internal space of the eccentric member 26 is supplied by centrifugal force from the second lubricating oil groove 26b to the Oldham coupling Cx, and is also supplied to the second bearing 29 and is supplied between the internal teeth 25A of the output gear 25 and the external teeth 30A of the input gear 30.

[0063] 1, the lubricating oil from the second lubricating oil groove 26b is supplied between the front plate 12 and the Oldham coupling Cx by the lubrication recess 12a, and is also supplied to the gap between the external engagement arm 42 of the Oldham coupling Cx and the guide groove 11a of the outer case 11. This allows the Oldham coupling Cx to operate smoothly. The lubricating oil supplied to the Oldham coupling Cx is then discharged to the outside from the gap between the external engagement arm 42 of the Oldham coupling Cx and the guide groove 11a of the outer case 11.

[0064] In particular, because a step G is formed between the opening edge of the front plate 12 and the inner periphery of the eccentric member 26, when the engine E is stopped, the lubricating oil in the internal space of the eccentric member 26 can be discharged through the opening 12b of the front plate 12, reducing the amount of lubricating oil remaining inside. If a large amount of lubricating oil remains inside the valve timing control device 100, the viscosity of the lubricating oil will inhibit operation of the phase adjustment mechanism C after the engine E is started in a cold environment; however, this inconvenience can be eliminated by discharging the lubricating oil when the engine E is stopped.

[0065] Furthermore, since the discharge passage 11b is formed in the guide groove 11a, when starting the engine E that has been stopped in a cold environment, the lubricating oil inside can be quickly discharged through the discharge passage 11b by centrifugal force, so that the highly viscous lubricating oil can be discharged in a short time, eliminating the influence of the viscosity of the lubricating oil and enabling the phase adjustment mechanism C to operate quickly.

[0066] As shown in FIGS. 5 and 6 , the front plate 12 has a plurality of (in this embodiment, four) protruding portions 12c (at 90-degree intervals along the circumferential direction about the rotation axis X) protruding inward on its inner surface (the side closer to the intake camshaft 2). The protruding portions 12c lightly abut against the intermediate member 20 to a degree that allows sliding contact therebetween. The intermediate member 20 abuts against the protruding portions 12c, thereby restricting movement of the intermediate member 20 toward the front plate 12. This allows the Oldham coupling Cx to operate smoothly while maintaining a predetermined gap between the front plate 12 and the intermediate member 20. In the valve timing control device 100, the protruding portions 12c are disposed radially outward of the annular portion 41 and circumferentially between the outer engagement arm 42 and the inner engagement arm 43 (see FIG. 4 ). The protruding portions 12c and the Oldham coupling Cx are disposed so as to overlap each other when viewed in the radial direction.

[0067] [Operational state when Oldham coupling breaks] In the valve timing control device 100, for example, if abnormal cam fluctuation torque (hereinafter also referred to as "abnormal torque") is repeatedly input from the intake camshaft 2, the abnormal torque may be transmitted from the output gear 25 via the input gear 30 to the Oldham coupling Cx, resulting in damage to the Oldham coupling Cx. Specifically, the input of abnormal torque causes the engaging protrusion 30T of the input gear 30 to perform abnormal movement, for example, to attempt to undergo large displacement in the up / down or left / right directions as viewed in the direction along the rotation axis X. Of this abnormal movement, movement in the second direction (the up / down direction in FIG. 4) is restricted by the biasing force of the elastic member S, and movement in the first direction (the left / right direction in FIG. 4) is restricted by the pair of internal engaging arms 43 of the Oldham coupling Cx. Therefore, if abnormal torque is input for only a short period of time, it will not affect the operation of the valve timing control device 100.

[0068] However, when this abnormal torque is repeatedly input over a long period of time, in order to restrict the abnormal operation (left-right displacement of the engaging protrusion 30T) that accompanies it, a force acts in the first direction (left-right direction in FIG. 4) on the second side surface 43c of each engaging recess 43a of the pair of internal engaging arms 43. As a result, if the second side surface 43c of the engaging recess 43a cannot fully withstand the force in the first direction due to the abnormal operation, the peripheral edge portion 43b extending in the circumferential direction of the U-shaped portion that forms the engaging recess 43a may break.

[0069] If the valve timing control device 100 is used in a state in which the peripheral portions 43b of the pair of internal engagement arms 43 of the Oldham coupling Cx are broken (hereinafter also referred to as the "broken state"), the internal engagement arms 43 of the Oldham coupling Cx cannot regulate abnormal operation of the input gear 30 due to abnormal torque transmitted to the input gear 30 via the output gear 25. This is because, in the broken state, the two opposing second side surfaces 43c of the internal engagement arm 43 are each movable, and therefore it is not possible to regulate the displacement of the engagement protrusion 30T that follows the displacement of the input gear 30. In particular, if both peripheral portions 43b of the pair of internal engagement arms 43 are broken, the two separated Oldham couplings Cx each become movable. Therefore, a large displacement of the engagement projection 30T of the input gear 30 in the first direction (left and right direction in FIG. 4) acts on the second side surface 43c, causing each of the two separated Oldham couplings Cx to be displaced outward in the first direction, and the internal engagement arm 43 may collide with the protrusion 12c of the front plate 12. If the internal engagement arm 43 repeatedly collides with the protrusion 12c, the impact may cause the fastening bolt 13 that fastens the front plate 12 and outer case 11 to loosen.

[0070] However, the Oldham coupling Cx of this embodiment has four protrusions 44, and as shown in Fig. 7, the protrusions 44 collide with the inner wall surface 11d of the outer case 11 before the broken internal engagement arm 43 displaces in the first direction and collides with the protrusion 12c of the front plate 12, so that the internal engagement arm 43 is not further displaced outward in the first direction (the left-right direction in Fig. 4). Specifically, as shown in Fig. 4, in a normal state of the Oldham coupling Cx in which neither of the two internal engagement arms 43 is broken, the distance Db (an example of the second distance) between the protrusion 44 of the Oldham coupling Cx and the inner wall surface 11d of the outer case 11 is shorter than the distance Da (an example of the first distance) in the first direction between the third side surface 43d (parallel to the second side surface 43c) of the internal engagement arm 43 of the Oldham coupling Cx and the outer peripheral surface of the protrusion 12c of the front plate 12.

[0071] 7, even if the broken internal engagement arm 43 is displaced outward in the first direction, the protrusion 44 collides with the inner wall surface 11d of the outer case 11, preventing the internal engagement arm 43 from colliding with the convex portion 12c of the front plate 12. Because the mass of the outer case 11 is greater than the mass of the front plate 12, even if the protrusion 44 collides with the inner wall surface 11d of the outer case 11, the outer case 11 absorbs the impact of the collision, and vibrations caused by the impact are less likely to be transmitted to the fastening bolt 13. As a result, the fastening bolt 13 fastening the front plate 12 and outer case 11 together can be prevented from loosening.

[0072] Furthermore, by providing the protrusion 44 on the Oldham coupling Cx, the length La in the first direction of the first side surface 42a of the external engagement arm 42 (the surface facing the guide groove 11a) can be made longer than the length of the same portion of the external engagement arm disclosed in Patent Document 1. This increases the amount of displacement of the Oldham coupling Cx in the first direction. Furthermore, when the length La is longer, the length Lb in the first direction of the guide groove 11a of the outer case 11 can also be made longer, which prevents the Oldham coupling Cx from tilting in the circumferential direction about the rotation axis X due to the gap between the guide groove 11a and the first side surface 42a of the external engagement arm 42. Furthermore, sliding noise between the first side surface 42a and the guide groove 11a and between the second side surface 43c and the engagement projection 30T can be reduced.

[0073] [Oldham coupling manufacturing process] The first side surface 42a of the external engagement arm 42 of the Oldham coupling Cx is parallel to the direction in which the external engagement arm 42 extends, and the second side surface 43c of the engagement recess 43a of the internal engagement arm 43 is parallel to the direction in which the internal engagement arm 43 extends. When the relative rotational phase changes during operation of the valve timing control device 100, the meshing position between the output gear 25 and the input gear 30 changes, so that the first side surface 42a of the external engagement arm 42 slides against the guide groove 11a of the outer case 11, and the second side surface 43c of the internal engagement arm 43 slides against the engagement protrusion 30T of the input gear 30. To ensure smooth sliding of the Oldham coupling Cx, the first side surface 42a and the second side surface 43c each require a high degree of flatness. To achieve this, the first side surface 42a and the second side surface 43c are ground during the manufacturing process of the Oldham coupling Cx.

[0074] In order to achieve the desired flatness by grinding, it is necessary to position the workpiece (in this embodiment, the first side surface 42a and the second side surface 43c) against a grinding wheel (not shown) with high precision. In the Oldham coupling Cx of this embodiment, the protrusion 44 has a first reference surface 44a, which is a plane parallel to the extension direction of the external engagement arm 42, and a second reference surface 44b, which is a plane parallel to the extension direction of the internal engagement arm 43. That is, the first side surface 42a of the external engagement arm 42 and the first reference surface 44a of the protrusion 44 are parallel. Similarly, the second side surface 43c of the internal engagement arm 43 and the second reference surface 44b of the protrusion 44 are parallel. In other words, since the external engagement arm 42 and the internal engagement arm 43 are perpendicular to each other, the first reference surface 44a and the second reference surface 44b of the protrusion 44 are also perpendicular to each other.

[0075] In this embodiment, when grinding the first side surface 42a of the external engagement arm 42, the first reference surface 44a of the protrusion 44 parallel to the first side surface 42a is clamped in a chuck. Because the first reference surface 44a is flat, clamping in the chuck is easy. As a result, the first side surface 42a can be positioned to face the grinding wheel with high precision using the first reference surface 44a as a reference, so the first side surface 42a can be ground to a high degree of flatness. Similarly, for the second side surface 43c of the internal engagement arm 43, the second reference surface 44b of the protrusion 44 parallel to the second side surface 43c is clamped in a chuck. Because the second reference surface 44b is flat, clamping in the chuck is easy. As a result, the second side surface 43c can be positioned to face the grinding wheel with high precision using the second reference surface 44b as a reference, so the second side surface 43c can be ground to a high degree of flatness. In this way, since the Oldham coupling Cx has the first reference surface 44a and the second reference surface 44b that are perpendicular to each other, when manufacturing the Oldham coupling Cx, the first side surface 42a and the second side surface 43c can be ground using the first reference surface 44a and the second reference surface 44b as references, and the Oldham coupling Cx can be manufactured with high precision.

[0076] [Actions and Effects of the Embodiments] In the Oldham coupling Cx, by providing the protrusions 44, as shown in Fig. 7, even if the peripheral edges 43b of a pair of internal engagement arms 43 are broken, the protrusions 44 will hit the inner wall surface 11d of the outer case 11 before the broken internal engagement arms 43 are displaced outward in the first direction (the left-right direction in Fig. 4) and hit the protrusions 12c of the front plate 12, and the internal engagement arms 43 will not be displaced any further outward in the first direction. As a result, the internal engagement arms 43 will no longer hit the protrusions 12c of the front plate 12, and there is no risk of the fastening bolts 13 fastening the front plate 12 and outer case 11 together becoming loose.

[0077] Furthermore, the protruding portion 44 of the Oldham coupling Cx has a first reference surface 44a that is parallel to the first side surface 42a of the external engagement arm 42 and a second reference surface 44b that is parallel to the second side surface 43c of the internal engagement arm 43. Therefore, when manufacturing the Oldham coupling Cx, by clamping the first reference surface 44a of the protruding portion 44 in a chuck, the first side surface 42a of the external engagement arm 42 can be ground to a high degree of flatness. Furthermore, by clamping the second reference surface 44b of the protruding portion 44 in a chuck, the second side surface 43c of the internal engagement arm 43 can be ground to a high degree of flatness. As a result, when the meshing position between the output gear 25 and the input gear 30 changes in accordance with a change in the relative rotational phase of the valve timing control device 100, the first side surface 42a slides smoothly against the guide groove 11a of the outer case 11, and the second side surface 43c slides smoothly against the engaging projection 30T of the input gear 30, so that the Oldham coupling Cx slides smoothly as a whole.

[0078] Other Embodiments In the above embodiment, the first reference surface 44a and the second reference surface 44b are configured to be perpendicular to each other, but they do not necessarily have to be perpendicular to each other as long as they are configured to intersect. Even in this case, it is preferable that the first reference surface 44a and the first side surface 42a, and the second reference surface 44b and the second side surface 43c are all parallel to each other. [Industrial Applicability]

[0079] The present invention can be used in a valve timing control device. [Explanation of symbols]

[0080] 1: Crankshaft 2: Intake camshaft (camshaft) 2B: Intake valve 11: Outer case 11d: Inner wall surface 12: Front plate 12c: Convex part 13: Fastening bolt 25: Output gear 26: Eccentric member 29: Second bearing (bearing) 30: Input gear 41: Annular section 42: External engagement arm 42a: First side 43: Internal engagement arm 43c:Second side 44:Protrusion 44a: First reference plane 44b: Second reference plane 100: Valve opening / closing timing control device A: Drive side rotor B: Driven rotating body C: Phase adjustment mechanism Cx: Oldham coupling Da: Distance (first distance) Db: Distance (second distance) E: Engine (internal combustion engine) X: Rotation axis Y: Eccentric shaft center

Claims

1. a drive-side rotor that rotates synchronously with the crankshaft of the internal combustion engine around a rotation axis; a driven-side rotor that is arranged coaxially with the rotation axis and inside the driving-side rotor, and that rotates integrally with a camshaft for opening and closing a valve of the internal combustion engine; a phase adjustment mechanism that sets the relative rotational phase between the drive-side rotor and the driven-side rotor, The phase adjustment mechanism includes: an output gear provided on the driven rotor coaxially with the rotation axis; an input gear that rotates about an eccentric axis parallel to the rotation axis, is connected to the drive rotor via an Oldham coupling, and meshes with the output gear; a cylindrical eccentric member that supports the input gear from an inner peripheral side via a bearing and rotates the input gear, The eccentric shaft is revolved by the rotation of the eccentric member about the rotation shaft, and the meshing position of the output gear and the input gear is changed, the Oldham coupling is disposed so as to overlap the drive-side rotor when viewed in a radial direction perpendicular to the rotation axis, The Oldham coupling is a valve timing control device having: an annular portion; an external engagement arm extending radially outward from the annular portion along a first direction; an internal engagement arm extending radially outward from the annular portion along a second direction intersecting the first direction; and a protrusion protruding radially outward from the annular portion between the external engagement arm and the internal engagement arm that are adjacent in the circumferential direction.

2. The drive-side rotating body is An outer case; a front plate fixed to the outer case by a fastening bolt and disposed adjacent to the Oldham coupling in a direction along the rotation axis, the Oldham coupling is disposed between the front plate and the driven-side rotating body and so as to overlap with the outer case as viewed in the radial direction, the front plate has a protrusion that protrudes toward the driven-side rotating body, 2. The valve opening / closing timing control device according to claim 1, wherein a second distance, which is a distance between the protrusion and an inner wall surface of the outer case, is shorter than a first distance, which is a distance between the internal engagement arm and the convex portion in the extension direction of the external engagement arm.

3. The valve timing control device according to claim 1 or 2, wherein the protrusion has a first reference surface and a second reference surface that are perpendicular to each other.

4. the first reference surface of the protrusion is parallel to a first side surface of the outer engagement arm that is perpendicular to the second direction, and the second reference surface is parallel to a second side surface of the inner engagement arm that is perpendicular to the first direction; 4. The valve timing control device according to claim 3, wherein the first side surface slides against a guide groove formed in an outer case of the drive-side rotor, and the second side surface slides against an engagement protrusion formed on the input gear.

Images