WO2010018821A1 - Variable valve timing device - Google Patents

Abstract

A variable valve timing device uses only a reduction mechanism to transmit rotation of an electric motor to a camshaft.  A reduction mechanism (5) for transmitting rotation of an output shaft (4) of an electric motor (3) to a camshaft (1) is configured such that rollers (9) held in pockets (10a) are made to be in rolling contact with an eccentric shaft section (4a) provided to the output shaft (4) and with an inner gear (8) provided to a circular tube section of a housing (7) integrated with a sprocket (2), and the above pockets (10a) are formed in a retainer section (10b) of an intermediate shaft (10) by dividing the retainer section (10b) at equal intervals at split points the number of which is less by one than the number of cam crests (8a) of the inner gear (8).  The construction above allows, when the output shaft (4) is rotated one time, the rollers (9) to revolve by one pitch of the cam crests (8a) along the outer diameter surface of the eccentric shaft section (4a), and the revolution of the rollers (9) is transmitted to the camshaft (1) through the intermediate shaft (10).

Description

Variable valve timing device

The present invention relates to a variable valve timing device that changes the opening and closing timing of an intake valve and an exhaust valve of an engine.

A variable valve timing device that changes the opening / closing timing of one or both of the intake valve and exhaust valve of an engine according to the driving situation of an automobile uses an oil pressure as a drive source of the rotation of the engine and the camshaft that drives the valve. There are many hydraulic types that change the phase with rotation, but the hydraulic type has variable valve timing control accuracy due to lack of hydraulic pressure at cold or engine start, or reduced responsiveness of hydraulic control Therefore, an electric type using an electric motor as an actuator has been proposed.

As such an electric variable valve timing device, as shown in FIGS. 24A and 24B, the camshaft 51 that drives the valve of the engine and the rotation transmitted from the engine rotate the camshaft 51. The sprocket 52 to be driven is arranged coaxially so as to be relatively rotatable, and the rotation of the output shaft 54 of the electric motor 53 arranged coaxially with the camshaft 51 is rotated via the speed reduction mechanism 55 and the link mechanism 56. And the camshaft 51 is rotated relative to the sprocket 52 to change the rotational phase difference between the two and change the valve opening and closing timing (see, for example, Patent Document 1).

The speed reduction mechanism 55 includes an external gear provided in a housing 58 in which a part of teeth of an internal gear 57 rotatably supported by a bearing on an eccentric shaft portion 54 a of an output shaft 54 of an electric motor 53 is integrated with a sprocket 52. 59, when the output shaft 54 is rotated relative to the sprocket 52 so as to mesh with the gear 59, the internal gear 57 is rotated around the eccentric shaft portion 54a. Further, the rotation of the guide plate 60 is transmitted to the cam plate 51a that rotates integrally with the camshaft 51 via the link mechanism 56 constituted by the arms 56a and 56b, and the camshaft 51 is sprocketed. Rotate relative to 52.

JP 2008-57349 A

The electric variable valve timing apparatus described in Patent Document 1 has a problem that the mechanism for transmitting the rotation of the electric motor to the camshaft has a complicated structure combining a speed reduction mechanism and a link mechanism, and the apparatus cannot be designed compactly. is there.

Therefore, an object of the present invention is to provide a variable valve timing device capable of transmitting the rotation of an electric motor to a camshaft only by a speed reduction mechanism.

In order to solve the above problems, the present invention provides a camshaft that drives at least one of an intake valve and an exhaust valve of an engine, and a sprocket that receives rotation from the engine and drives the camshaft to rotate. A rotation phase difference of the camshaft with respect to the sprocket is transmitted to the camshaft through a speed reduction mechanism by rotating the output shaft of the electric motor arranged coaxially with the camshaft so as to be relatively rotatable. In the variable valve timing apparatus that changes the opening / closing timing of the valve by changing the valve, the speed reduction mechanism is provided with an eccentric shaft portion having a circular cross section on the output shaft of the electric motor, and a housing integrated with the sprocket An internal gear having a plurality of cam ridges formed at equal pitches in the circumferential direction on the inner diameter surface of the cylindrical portion of the cylindrical portion An intermediate shaft having an annular cage portion provided with a pocket for holding a plurality of rollers that are in rolling contact with the outer diameter surfaces of the opposed eccentric shaft portions and the internal gear is coaxial with the camshaft. The number of division points when the annular cage portion is divided at equal pitches in the circumferential direction is thinned out at all or a part of the division points that differ from the number of the cam crests by one. When the pocket for holding the roller is provided at a position where the shape of one pitch of the cam crest is rotated and the output shaft of the electric motor is rotated, the roller held in the pocket becomes the eccentric shaft portion. A configuration is adopted in which the revolutions of these rollers are transmitted to the camshaft via the intermediate shaft so as to coincide with the outer diameter side envelope of the trajectory revolving along the outer diameter surface.

That is, a speed reduction mechanism for transmitting the rotation of the output shaft of the electric motor to the camshaft is provided with an eccentric shaft portion having a circular cross section on the output shaft of the electric motor, and a plurality of inner diameter surfaces of the cylindrical portion of the housing integrated with the sprocket An internal gear having cam ridges formed at equal pitches in the circumferential direction is provided to face the eccentric shaft portion, and a pocket for holding a plurality of rollers that are in rolling contact with the outer diameter surface of the opposed eccentric shaft portion and the internal gear. The number of dividing points when the intermediate shaft having the annular retainer portion provided is coaxially arranged with the cam shaft and the annular retainer portion is divided at an equal pitch in the circumferential direction is the number of cam peaks. When a pocket for holding a roller is provided at all or a part of a part where only one different dividing point is thinned out, and the shape of one pitch of the cam crest is rotated when the output shaft of the electric motor is rotated, Roller held in pocket By matching the outer diameter side envelope of the trajectory that revolves along the outer diameter surface of the shaft portion, the revolution of these rollers is transmitted to the camshaft via the intermediate shaft, so that only the speed reduction mechanism can be used. The rotation of the motor can be transmitted to the camshaft.

Rotation unevenness due to the unbalance of the weight of the eccentric shaft around the axis of the output shaft by providing a balance adjusting unit for adjusting the weight balance around the output shaft at the eccentric shaft of the output shaft of the electric motor. Can be suppressed, and there is no possibility of vibrations occurring in the speed reduction mechanism.

The balance adjusting portion may be an axial through hole provided on the eccentric side of the eccentric shaft portion.

When a rolling bearing is externally fitted to the eccentric shaft portion and the roller is brought into rolling contact with the outer diameter surface of the outer ring, the balance adjusting portion is cut by an outer diameter portion provided on the eccentric side of the eccentric shaft portion. It can be a lack.

The notch in the outer diameter part of the eccentric shaft part may be a part in which the outer diameter part is notched flat with a string.

The notch in the outer diameter part of the eccentric shaft part may be a part of the outer diameter part notched in a concave shape.

When the balance adjusting portion has the same cross-sectional dimension in the axial direction of the eccentric shaft portion, the balance adjusting portion can be easily formed by pressing or forging.

By providing crowning on at least both ends of the body of the roller, the occurrence of edge load of the roller that is in rolling contact with the outer diameter surface of the eccentric shaft portion and the internal gear, and seizure or wear on the rolling contact surface of the roller. It is possible to prevent the transmission efficiency from being lowered and the durability life from being shortened.

An infinite number of minute recesses are randomly formed on the surface of at least the body of the roller, and the parameter SK value of the surface roughness is set to −1.6 or less, whereby the outer diameter surface of the eccentric shaft portion and the internal gear A sufficient oil film is formed on the rolling contact surface of the roller, and seizure and wear on the rolling contact surface of the roller can be prevented.

The parameter SK value of the surface roughness is a value representing the relativity of the amplitude distribution curve with respect to the average line of the surface roughness, as shown in FIGS. It is defined in 1).
SK = ∫ (x−x ₀ ) ³ · P (x) dx / σ ³ (1)
Here, x: height of roughness, x ₀ : average height of roughness, P (x): probability density function of amplitude of roughness, and σ: mean square roughness.

The parameter SK value is positive when there are many peaks in the amplitude distribution curve with respect to the average line of the surface roughness as shown in FIG. 23A, and the peaks and valleys are equal as shown in FIG. When the number of valleys is large as shown in FIG. Therefore, by setting the parameter SK value to negative −1.6 or less, a sufficient oil film can be formed on the rolling contact surface of the roller.

The roller is first quenched after carbonitriding and cooled to a temperature lower than the A1 transformation point, and then subjected to a secondary quenching at a lower temperature than the primary quenching to refine the austenite crystal grains of the roller. Thus, the rolling fatigue strength of the roller can be increased. Therefore, the roller can be shortened to be more compact, and the friction torque can be reduced to improve the transmission efficiency.

¡Use of extreme pressure grease or oil for lubrication of the roller can more reliably prevent seizure and wear on the rolling contact surface of the roller.

By providing a film with a low coefficient of friction on at least the inner surface of the pocket of the cage portion, torque loss due to sliding contact with the inner surface of the pocket of the roller can be reduced. As the film having a low coefficient of friction, a phosphate film, a resin film, or the like can be employed.

A cylindrical portion is provided on the output shaft of the electric motor, the eccentric shaft portion is provided on the outer peripheral portion of the output shaft cylindrical portion, and a camshaft coaxial with the output shaft is fitted inside the output shaft cylindrical portion. By mounting a bearing that supports the output shaft between the outer diameter surface of the inserted cam shaft and the cylindrical portion of the output shaft, the axial dimension of the output shaft of the electric motor and the cam shaft can be shortened. Thus, the axial length of the entire apparatus can be designed compactly.

When the outer diameter surface of the eccentric shaft portion provided on the outer peripheral portion of the output shaft cylindrical portion is formed by the outer diameter surface of the outer ring of the rolling bearing fitted on the eccentric shaft portion, the shaft of the bearing that supports the output shaft The center position in the direction may be set within the range of the bearing width of the rolling bearing that is externally fitted to the eccentric shaft portion.

The intermediate shaft is provided with a cylindrical portion, the output shaft of the electric motor is fitted inside the intermediate shaft cylindrical portion, and the output shaft is interposed between the outer diameter surface of the inserted output shaft and the intermediate shaft cylindrical portion. By mounting the bearing that supports the shaft, the axial dimension of the output shaft of the electric motor and the intermediate shaft can be shortened, and the axial length of the entire apparatus can be designed to be compact.

When the bearing that supports the intermediate shaft is mounted on the outer diameter surface of the intermediate shaft cylindrical portion, the axial center position of the bearing that supports the output shaft is mounted on the outer diameter surface of the intermediate shaft cylindrical portion. It is good to set within the range of the bearing width.

By forming the outer diameter surface of the eccentric shaft portion to which the roller is in rolling contact with the outer diameter surface of the outer ring of the rolling bearing fitted on the eccentric shaft portion, slippage between the roller and the outer diameter surface of the eccentric shaft portion is suppressed. be able to.

こ と By making the rolling bearing fitted around the eccentric shaft portion into a roller bearing without a cage, the number of rollers can be increased and the load capacity can be increased.

The number of parts can be reduced by forming the inner ring of the roller bearing at the outer periphery of the eccentric shaft portion.

It is possible to prevent the occurrence of edge load by providing crowning at both ends of the roller of the roller bearing.

Wear resistance can be improved by subjecting the raceway surface of the roller bearing to induction hardening.

By forming the eccentric shaft portion with an eccentric ring fitted around the output shaft, the eccentric shaft portion can be easily provided on the output shaft.

By forming the annular cage portion into a comb shape that protrudes in the axial direction and opens at the tip side, and a space formed between the comb shapes that opens at the tip side is a pocket that holds the roller, The length of the cage portion can be shortened to further reduce the axial length of the entire apparatus. Moreover, the roller hold | maintained at the pocket of a holder | retainer part can be inserted from an axial direction, and the integration to the pocket of a roller can also be made easy.

¡By providing chamfers on both sides of the opening at the tip end in the axial direction of the pocket formed between the combs, the roller can be easily incorporated into the pocket.

By providing a fillet at the comb-shaped base corner of the pocket formed between the combs, the strength of the cage-shaped cage part can be ensured.

By providing an inward flange that faces the opening of the pocket in the axial direction on one side of the cylindrical portion of the housing, it is possible to prevent the roller held in the pocket by this flange from coming off in the axial direction. it can.

By forming the cage portion of the intermediate shaft from a resin material, it is possible to prevent damage to the roller due to sliding contact with the pocket surface of the cage portion.

</ RTI> By forming the intermediate shaft having the cage portion by pressing a metal plate, the intermediate shaft can be manufactured at low cost.

When the roller passes the top of the cam crest of the internal gear by forming a gap at the top of the cam crest of the internal gear between the outer diameter surface of the eccentric shaft portion and the roller that is in rolling contact with the roller. It is possible to prevent an excessive contact pressure from being generated.

The means for forming a gap with the roller at the top of the cam crest of the internal gear can be easily formed with the roller by notching the top of the cam crest. . In addition, it is possible to easily make a tool shape such as a broach for processing a cam crest in an internal gear, or a die shape such as press punching or die forging. When processing by press punching, the life of the mold can be extended.

The notch shape at the top of the cam mountain can be a flat shape.

The notch shape at the top of the cam crest may be an R shape that is convex or concave toward the inner diameter side.

The shock and vibration due to the collision of the roller can be absorbed by coating a buffer material on the portion where a gap is formed between the top of the cam crest of the internal gear and the roller.

The internal gear on the inner diameter surface of the cylindrical portion of the housing is formed by a separate internal gear that is internally fitted and fixed to the inner diameter surface of the cylindrical portion, so that the processing of the internal gear can be facilitated.

The cam gear of the separate internal gear can be formed by broach grinding, press punching or die forging.

The strength and wear resistance of the cam crest can be improved by induction hardening of the cam crest portion of the internal gear.

By providing an elastic member for pressing the roller held in the pocket from both sides in the circumferential direction in the cage portion of the intermediate shaft, the roller can be reliably held in the pocket and the behavior can be stabilized.

The elastic member that presses the roller from both sides in the circumferential direction may be housed in a recess formed on the inner surface facing in the circumferential direction of the pocket of the cage portion.

The elastic member can be a coil spring.

The variable valve timing device of the present invention is a cylindrical portion of a housing in which a speed reduction mechanism for transmitting rotation of an output shaft of an electric motor to a camshaft is provided, an eccentric shaft portion having a circular cross section is provided on the output shaft of the electric motor, and integrated with a sprocket. An inner gear having a plurality of cam ridges formed at equal pitches in the circumferential direction is provided opposite to the eccentric shaft portion on the inner diameter surface of the inner surface, and a plurality of rollers that are in rolling contact with the outer diameter surface of the opposed eccentric shaft portion and the inner gear. The number of dividing points when an intermediate shaft having an annular cage portion provided with a pocket for holding the roller is coaxially arranged with the camshaft and the annular cage portion is divided at equal pitches in the circumferential direction. However, a pocket for holding the roller is provided at all or a part of the dividing points that differ by one from the number of cam peaks, and the shape of one pitch of the cam peaks is set to the output shaft of the electric motor. When you rotate the The rollers held by the roller are aligned with the outer diameter side envelope of the trajectory of revolving along the outer diameter surface of the eccentric shaft portion, and the revolution of these rollers is transmitted to the camshaft via the intermediate shaft. Therefore, the rotation of the electric motor can be transmitted to the camshaft only with the speed reduction mechanism, and the design can be made compact.

1 is a longitudinal sectional view showing a variable valve timing device according to a first embodiment. Sectional view along the line II-II in FIG. a is a front view showing the roller of FIG. 1, b is an expanded plan view showing an enlarged surface of the body of a Schematic diagram showing the heat treatment pattern of the roller of FIG. The longitudinal cross-sectional view which shows the variable valve timing apparatus of 2nd Embodiment Sectional view along line VI-VI in FIG. Sectional drawing which shows the modification of the notch of FIG. A cross-sectional view showing a speed reduction mechanism of a variable valve timing device according to a third embodiment FIG. 8 is an enlarged cutaway sectional view showing the main part of FIG. a and b are sectional views showing modifications of the notch shape of the cam crest in FIG. a is an enlarged cross-sectional view of the main part of FIG. 8, and b is an arrow view from the XIb-XIb line of a. A longitudinal section showing a variable valve timing device of a 4th embodiment The perspective view which shows the intermediate shaft which has a holder | retainer part of FIG. A longitudinal section showing a variable valve timing device of a 5th embodiment A longitudinal section showing a variable valve timing device of a 6th embodiment The longitudinal cross-sectional view which shows the variable valve timing apparatus of 7th Embodiment Sectional view along line XVII-XVII in FIG. A longitudinal section showing a variable valve timing device of an 8th embodiment Sectional view along line XIX-XIX in FIG. The longitudinal cross-sectional view which shows the variable valve timing apparatus of 9th Embodiment a and b are longitudinal sectional views showing modifications of FIG. A longitudinal section showing a variable valve timing device of a 10th embodiment a to c are conceptual diagrams for explaining the definition of the parameter SK value of the surface roughness. a is a longitudinal sectional view showing a conventional variable valve timing device, and b is a sectional view taken along line XXIVb-XXIVb of a.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 4 show a first embodiment. As shown in FIG. 1, the variable valve timing device is configured to relatively connect a camshaft 1 that drives an intake valve (not shown) of an engine and a sprocket 2 that receives rotation from the engine and drives the camshaft 1 to rotate. The rotation of the output shaft 4 of the electric motor 3 arranged coaxially so as to be rotatable and coaxial with the camshaft 1 is transmitted to the camshaft 1 via the speed reduction mechanism 5, and the rotational position of the camshaft 1 relative to the sprocket 2 is transmitted. The opening / closing timing of the intake valve is changed by changing the phase difference.

As shown in FIGS. 1 and 2, the speed reduction mechanism 5 is provided with an eccentric shaft portion 4a having a circular cross section on the output shaft 4 of the electric motor 3, and a ball bearing rolling bearing 6 is fitted on the eccentric shaft portion 4a. A separate internal gear 8 having a plurality of cam ridges 8 a formed on the inner surface of the cylindrical portion 7 a of the housing 7 fixed and integrated with the sprocket 2 is opposed to the outer surface of the outer ring 6 a of the rolling bearing 6. The intermediate shaft 10 having an annular retainer portion 10b provided with a pocket 10a for holding a plurality of rollers 9 that are in rolling contact with the outer diameter surfaces of the opposed outer rings 6a and the internal gear 8 is cammed. The intermediate shaft 10 is arranged coaxially with the shaft 1 and the intermediate shaft 10 is connected to the camshaft 1 by a spline 11, and the rotation of the output shaft 4 of the electric motor 3 is rotated via the intermediate shaft 10 by a mechanism described later. Communicate to 1 .

On the eccentric side of the eccentric shaft portion 4a, a through hole 4b is provided as a balance adjusting portion for adjusting the weight balance around the shaft center of the output shaft 4. The through hole 4b has the same cross-sectional dimension in the axial direction of the output shaft 4 including the eccentric shaft portion 4a. The output shaft 4 of the electric motor 3 is supported by the housing 7 by a ball bearing 12, and the intermediate shaft 10 is supported by the ball bearing 13 on the cylindrical portion 7 a of the housing 7 via the extended cylindrical portion of the internal gear 8.

The portion of the cam crest 8a of the internal gear 8 is processed by broach grinding and subjected to induction hardening. The cam peak 8a can be processed by press punching or die forging. 29 cam ridges 8a are formed at equal pitches in the circumferential direction, and pockets 10a holding the rollers 9 are divided with respect to the dividing points when the annular cage portion 10b is divided into 30 at equal pitches in the circumferential direction. It is provided at 15 positions thinned out every other one, and the number of division points is one more than the cam crest 8a. Further, the shape of one pitch of the cam crest 8a is such that when the output shaft 4 is rotated, the outer diameter of the outer ring 6a of the rolling bearing 6 in which the roller 9 held in the pocket 10a is externally fitted to the eccentric shaft portion 4a. It coincides with the outer envelope of the trajectory revolving along the surface.

As shown in FIG. 3A, the roller 9 is provided with crowning 9a at both ends of the body. Therefore, it is possible to prevent the edge load of the roller 9 that is in rolling contact with the outer diameter surface of the outer ring 6 a and the inner gear 8. The crowning 9a may be provided over the entire length of the trunk.

As shown in an enlarged view in FIG. 3B, innumerable minute recesses 9b are randomly formed on the surface of the body portion of the roller 9, and the parameter SK value of the surface roughness is −1.6 or less. It is said that. In addition, an oil having extreme pressure is used for lubricating the roller 9. Accordingly, a sufficient oil film is formed on the rolling contact surface of the roller 9 between the outer diameter surface of the outer ring 6a and the internal gear 8, and seizure and wear on the rolling contact surface of the roller 9 are prevented.

The roller 9 is made of high carbon chromium bearing steel SUJ2 as a raw material, as shown in FIG. 4, after first quenching at a temperature T1 after carbonitriding and cooling to a temperature below the A1 transformation point, rather than the primary quenching. The austenite crystal grain of the microstructure is refined | miniaturized by the heat processing which secondary quenches in oil at low temperature T2, and is tempered.

Although not shown, the cage portion 10b is subjected to a phosphate coating treatment as a low friction coefficient coating including the inner surface of the pocket 10a that holds the roller 9.

Hereinafter, the deceleration mechanism of the deceleration mechanism 5 will be described. As indicated by the arrows in FIG. 2, the output shaft 4 rotates clockwise, and the minimum portion A of the annular space between the outer diameter surface of the eccentric outer ring 6a and the internal gear 8 on which the cam ridge 8a is formed is clockwise. If the output angle is 0 ° and the maximum portion B is 180 °, the minimum portion A and the maximum portion B move clockwise as the output shaft 4 rotates, and the right half of the annular space becomes narrower. Tendency, the left half of the annular space tends to widen. For this reason, the roller 9 present in the right half of the annular space moves in the outer diameter direction down the cam peak 8a of the internal gear 8, and the roller 9 present in the left half of the annular space moves in the inner diameter direction above the cam peak 8a. As indicated by the arrows in the figure, the cage portion 10 b of the intermediate shaft 10 that holds the roller 9 rotates in the same clockwise direction as the output shaft 4.

In this embodiment, since the number N of the dividing points of the cage portion 10b is one more than the number of the cam peaks 8a, each roller 9 rotates clockwise by one pitch of the cam peaks 8a when the output shaft 4 rotates once. And the reduction ratio between the output shaft 4 and the intermediate shaft 10 is equal to the number N of division points. When the number N of division points is one less than the number of cam peaks 8a, each roller 9 revolves counterclockwise, and the intermediate shaft 10 rotates in the direction opposite to the output shaft 4.

5 and 6 show a second embodiment. This variable valve timing device has the same basic configuration as that of the first embodiment, and the balance adjusting unit that adjusts the weight balance around the axis of the output shaft 4 is the eccentric of the eccentric shaft 4a. The difference is that a part of the outer diameter portion is formed into a notch 4c that is notched flat with a string. The notch 4c has the same cross-sectional dimension in the axial direction of the eccentric shaft portion 4a. Other parts are the same as those of the first embodiment.

FIG. 7 shows a modification of the notch 4c as the balance adjusting portion. The notch 4c is formed by notching the outer diameter portion on the eccentric side of the eccentric shaft portion 4a in a concave shape, and has the same cross-sectional dimension in the axial direction of the eccentric shaft portion 4a.

8 to 11 show a third embodiment. The basic structure of this variable valve timing device is the same as that of the first embodiment. As shown in an enlarged view in FIG. 9, the top of the cam crest 8a of the internal gear 8 is cut out into a flat shape. However, the difference is that when the roller 9 held in the pocket 10a and in rolling contact with the outer ring 6a of the rolling bearing 6 passes through the top of the cam crest 8a, a gap δ is formed between them. Therefore, an excessive contact pressure does not occur when the roller 9 passes the top of the cam peak 8a. Further, the notched portion of the top of the cam crest 8a is coated with a buffer material 14 so as to absorb the impact and vibration caused by the collision of the roller 9. As the buffer material 14, urethane resin, synthetic rubber, or the like can be used.

10 (a) and 10 (b) show a modification of the notch shape at the top of the cam crest 8a. FIG. 10A shows an R shape that is concave toward the inner diameter side, and FIG. 10B shows an R shape that is convex toward the inner diameter side.

Further, in this embodiment, as shown in FIGS. 11A and 11B in an enlarged manner, a recess 15 is formed on the inner surface facing the circumferential direction of the pocket 10a of the cage portion 10b of the intermediate shaft 10, A coil spring 16 as an elastic member that presses the roller 9 from both sides in the circumferential direction is accommodated in these recesses 15. Therefore, the roller 9 can be reliably held in the pocket 10a and the behavior can be stabilized.

Since the concave portion 15 is also opened on the outer diameter side of the cage portion 10b, the coil spring 16 can be easily accommodated from the outer side in the radial direction while the roller 9 is held in the pocket 10a. Further, an R-shaped fillet 15a is provided at the bottom corner of the recess 15 to prevent stress concentration, and an R-shaped fillet 15a is provided at the opening edge of the recess 15 to prevent the roller 9 from being damaged. A chamfer 15b is provided.

12 and 13 show a fourth embodiment. The basic configuration of the variable valve timing device is the same as that of the first embodiment. As shown in FIG. 13, the cage portion 10b of the intermediate shaft 10 projects in the axial direction and the tip side is open. The difference is that the shape is a comb shape, and the space formed between the comb shapes having an opening at the front end side is a pocket 10 a for holding the roller 9. A chamfer 17 is provided on both sides of the opening at the tip end side in the axial direction of the pocket 10a formed between the combs, and an R-shaped fillet 18 is provided at the comb-shaped base corner of the pocket 10a. As shown in FIG. 12, the opening of the pocket 10a faces the inner surface of the flange 7b of the housing 7, and the roller 9 held in the pocket 10a is prevented from coming off in the axial direction.

FIG. 14 shows a fifth embodiment. This variable valve timing device has the same basic configuration as that of the fourth embodiment, except that the cage portion 10b of the intermediate shaft 10 is insert-molded with a resin material. The other portions are the same as those of the fourth embodiment, and the opening of the pocket 10a of the cage portion 10b having a comb shape is opposed to the inner side surface of the flange portion 7b of the housing 7.

FIG. 15 shows a sixth embodiment. This variable valve timing device also has the same basic configuration as that of the fourth embodiment, except that the intermediate shaft 10 having the cage portion 10b is formed by pressing a steel plate. The other portions are the same as those of the fourth embodiment, and the opening of the pocket 10a of the cage portion 10b having a comb shape is opposed to the inner side surface of the flange portion 7b of the housing 7.

16 and 17 show a seventh embodiment. This variable valve timing device has the same basic structure as that of the first embodiment, and a rolling bearing 6 fitted on the eccentric shaft portion 4a includes a roller 6b arranged in a full roller state. The difference is that the inner ring is formed on the outer peripheral portion of the eccentric shaft portion 4a. On both end sides of the outer ring 6a of the rolling bearing 6, there are provided flanges for restricting the axial movement of the rollers 6b, and on the outer peripheral part of the eccentric shaft part 4a serving as the inner ring, a flange is provided on one end side, and the other end side. A collar 19 is externally fitted on the outer side. Although enlarged illustration is omitted, both ends of each roller 6b are provided with a crowning for preventing the occurrence of edge load, and the raceway surface of the outer ring 6a of the roller bearing and the eccentric shaft portion 4a serving as the raceway surface of the inner ring are provided. The outer diameter surface is subjected to induction hardening.

18 and 19 show an eighth embodiment. This variable valve timing device has the same basic configuration as that of the seventh embodiment, and the eccentric shaft portion 4a is formed by an eccentric ring 20 fitted on the output shaft 4, and this eccentric ring 20 Is the inner ring of the rolling bearing 6 as the roller bearing. An eccentric ring 20 that is an inner ring is provided with a flange on one end side and an outer ring 19 that is eccentric to the output shaft 4 on the other end side. The other parts are the same as those of the seventh embodiment, and flanges are provided on both end sides of the outer ring 6a, and the raceway surface of the outer ring 6a and the raceway surface of the inner ring formed by the eccentric ring 20 are induction hardened. Is given.

FIG. 20 shows a ninth embodiment. In this variable valve timing device, the eccentric shaft portion 4a of the output shaft 4 is a cylindrical portion, and an extension portion 1a provided at the tip of the spline 11 of the camshaft 1 is provided on the eccentric shaft portion 4a. A ball bearing 12 that supports the output shaft 4 is mounted between the extended portion 1a and the inner diameter surface of the eccentric shaft portion 4a that is a cylindrical portion. Accordingly, the axial length of the entire apparatus is designed to be compact. Further, the intermediate shaft 10 is directly supported by the cylindrical portion 7a of the housing 7 by the ball bearing 13, and the rolling bearing 6 of the ball bearing is fitted and fixed to the outer diameter surface of the eccentric shaft portion 4a, and the outer diameter of the outer ring 6a. The roller 9 is in rolling contact with the surface, and the axial position of the ball bearing 12 is set within the range of the bearing width of the rolling bearing 6. Other basic configurations are the same as those of the first embodiment.

FIGS. 21A and 21B show a modification of the ninth embodiment. The modified example of (a) is similar to that of the seventh embodiment, in which the rolling bearing 6 is a roller bearing without a cage, and the inner ring is formed by the outer peripheral part of the eccentric shaft part 4a, (b) As in the case of the eighth embodiment, the modified example is that the rolling bearing 6 is a roller bearing without a cage, the eccentric shaft portion 4a is formed by the eccentric ring 20, and the eccentric ring 20 is the inner ring of the rolling bearing 6. It is what.

FIG. 22 shows a tenth embodiment. In the variable valve timing device, a cylindrical portion 10c is provided on the intermediate shaft 10, and an extension portion 4d provided at the tip of the eccentric shaft portion 4a of the output shaft 4 is fitted into the cylindrical portion 10c. A ball bearing 12 that supports the output shaft 4 is mounted between the portion 4 d and the inner diameter surface of the cylindrical portion 10 c of the intermediate shaft 10. Even in this embodiment, the axial length of the entire apparatus is designed to be compact. Further, the intermediate shaft 10 is directly supported by the cylindrical portion 7a of the housing 7 by the ball bearing 13, and the rolling bearing 6 of the ball bearing is fitted and fixed to the outer diameter surface of the eccentric shaft portion 4a, and the outer diameter of the outer ring 6a. The roller 9 is in rolling contact with the surface, and the axial position of the ball bearing 12 is set within the range of the bearing width of the ball bearing 13. Other basic configurations are the same as those of the first embodiment.

DESCRIPTION OF SYMBOLS 1 Cam shaft 1a Extension part 2 Sprocket 3 Electric motor 4 Output shaft 4a Eccentric shaft part 4b Through-hole 4c Notch 4d Extension part 5 Reduction mechanism 6 Rolling bearing 6a Outer ring 6b Roller 7 Housing 7a Cylindrical part 7b Eave part 8 Internal gear 8a Cam Mountain 9 Roller 9a Crowning 9b Recess 10 Intermediate shaft 10a Pocket 10b Cage 10c Cylindrical part 11 Spline 12, 13 Ball bearing 14 Buffer material 15 Recess 15a Fillet 15b Chamfer 16 Coil spring 17 Chamfer 18 Fillet 19 Heel ring 20 Eccentric ring

Claims (39)

A camshaft that drives at least one of an intake valve and an exhaust valve of an engine, and a sprocket that receives rotation from the engine and drives the camshaft to rotate are arranged coaxially so as to be relatively rotatable, and the cam The rotation of the output shaft of the electric motor arranged coaxially with the shaft is transmitted to the camshaft through a reduction mechanism, and the opening / closing timing of the valve is changed by changing the rotational phase difference of the camshaft with respect to the sprocket. In the variable valve timing device thus configured, the speed reduction mechanism is provided with an eccentric shaft portion having a circular cross section on the output shaft of the electric motor, and a plurality of cam peaks are formed on the inner diameter surface of the cylindrical portion of the housing integrated with the sprocket. An internal gear formed at an equal pitch in the circumferential direction is provided so as to face the eccentric shaft portion. An intermediate shaft having an annular cage portion provided with a pocket for holding a plurality of rollers that are in rolling contact with the outer diameter surface of the shaft portion and the internal gear is arranged coaxially with the camshaft, and the annular cage portion Pockets for holding the rollers at positions where the number of dividing points when the number of dividing points is different from the number of the cam crests by one is thinned out. Providing a shape corresponding to one pitch of the cam crest, when a roller held in the pocket revolves along the outer diameter surface of the eccentric shaft portion when the output shaft of the electric motor is rotated. A variable valve timing device characterized in that the revolution of these rollers is transmitted to the camshaft via the intermediate shaft in conformity with an outer diameter side envelope. 2. The variable valve timing device according to claim 1, wherein a balance adjusting unit for adjusting a weight balance around the output shaft is provided at an eccentric shaft portion of the output shaft of the electric motor. 3. The variable valve timing device according to claim 2, wherein the balance adjusting portion is an axial through hole provided on an eccentric side of the eccentric shaft portion. A rolling bearing is externally fitted to the eccentric shaft portion, the roller is brought into rolling contact with the outer diameter surface of the outer ring, and the balance adjusting portion is provided with a notch in the outer diameter portion provided on the eccentric side of the eccentric shaft portion. The variable valve timing apparatus according to claim 2. 5. The variable valve timing device according to claim 4, wherein a notch in the outer diameter portion of the eccentric shaft portion is formed by cutting a part of the outer diameter portion into a flat shape with a string. 5. The variable valve timing device according to claim 4, wherein a notch in the outer diameter portion of the eccentric shaft portion is formed by notching a part of the outer diameter portion in a concave shape. The variable valve timing device according to any one of claims 2 to 6, wherein the balance adjusting portion has the same cross-sectional dimension in the axial direction of the eccentric shaft portion. The variable valve timing device according to any one of claims 1 to 7, wherein crowning is provided on at least both ends of the body of the roller. 9. The variable valve according to claim 1, wherein an infinite number of minute recesses are randomly formed on at least the surface of the body of the roller, and the parameter SK value of the surface roughness is −1.6 or less. Timing device. 10. The roller according to any one of claims 1 to 9, wherein after the carbonitriding treatment, the roller is first quenched and cooled to a temperature lower than the A1 transformation point, and then subjected to a second quench at a lower temperature than the first quench. Variable valve timing device. The variable valve timing device according to any one of claims 1 to 10, wherein grease or oil having extreme pressure is used for lubricating the roller. The variable valve timing device according to any one of claims 1 to 11, wherein a film having a low coefficient of friction is provided on at least an inner surface of the pocket of the cage portion. A cylindrical portion is provided on the output shaft of the electric motor, the eccentric shaft portion is provided on the outer peripheral portion of the output shaft cylindrical portion, and a camshaft coaxial with the output shaft is fitted inside the output shaft cylindrical portion. The variable valve timing device according to any one of claims 1 to 12, wherein a bearing that supports the output shaft is mounted between an outer diameter surface of the inserted camshaft and the output shaft cylindrical portion. The outer diameter surface of the eccentric shaft portion provided on the outer peripheral portion of the output shaft cylindrical portion is formed by the outer diameter surface of the outer ring of the rolling bearing fitted on the eccentric shaft portion, and the axial center of the bearing that supports the output shaft The variable valve timing device according to claim 13, wherein the position is set within a range of a bearing width of a rolling bearing fitted on the eccentric shaft portion. The intermediate shaft is provided with a cylindrical portion, the output shaft of the electric motor is fitted inside the intermediate shaft cylindrical portion, and the output shaft is interposed between the outer diameter surface of the inserted output shaft and the intermediate shaft cylindrical portion. The variable valve timing device according to any one of claims 1 to 12, further comprising a bearing that supports the shaft. A bearing that supports the intermediate shaft is mounted on the outer diameter surface of the intermediate shaft cylindrical portion, and the axial center position of the bearing that supports the output shaft is mounted on the outer diameter surface of the intermediate shaft cylindrical portion. The variable valve timing device according to claim 15, wherein the variable valve timing device is set within a width range. The variable valve timing device according to any one of claims 1 to 16, wherein an outer diameter surface of an eccentric shaft portion in contact with the roller is formed by an outer diameter surface of an outer ring of a rolling bearing fitted on the eccentric shaft portion. The variable valve timing device according to claim 17, wherein the rolling bearing externally fitted to the eccentric shaft portion is a roller bearing without a cage. The variable valve timing device according to claim 18, wherein an inner ring of the roller bearing is formed by an outer peripheral portion of the eccentric shaft portion. The variable valve timing device according to claim 18 or 19, wherein crowning is provided at both ends of the roller of the roller bearing. 21. The variable valve timing device according to claim 18, wherein the raceway surface of the roller bearing is subjected to induction hardening. The variable valve timing device according to any one of claims 1 to 21, wherein the eccentric shaft portion is formed by an eccentric ring that is externally fitted to the output shaft. The annular retainer portion has a comb shape that projects in the axial direction and opens at the tip end side, and a space formed between the comb shapes that opens at the tip end side is a pocket that holds the roller. 23. The variable valve timing device according to any one of items 1 to 22. 24. The variable valve timing device according to claim 23, wherein chamfers are provided on both sides of the opening at the tip end in the axial direction of the pocket formed between the combs. 25. The variable valve timing device according to claim 23 or 24, wherein a fillet is provided on a comb-shaped base corner of a pocket formed between the combs. 23. An inward flange that is axially opposed to the opening of the pocket is provided on one side of the cylindrical portion of the housing, and a roller held in the pocket is prevented from coming off in the axial direction by the flange. 26. The variable valve timing device according to any one of 25. 27. The variable valve timing device according to claim 1, wherein the cage portion of the intermediate shaft is formed of a resin material. The variable valve timing device according to any one of claims 1 to 26, wherein an intermediate shaft having the cage portion is formed by pressing a metal plate. 29. The variable valve timing device according to any one of claims 1 to 28, wherein a gap is formed between an outer diameter surface of the eccentric shaft portion and a roller that is in rolling contact with a top portion of a cam crest of the internal gear. 30. The variable valve timing device according to claim 29, wherein the means for forming a gap between the top of the cam crest of the internal gear and the roller cuts out the top of the cam crest. The variable valve timing device according to claim 30, wherein a cutout shape of the top of the cam mountain is a flat shape. The variable valve timing device according to claim 30, wherein the notch shape of the top of the cam crest is an R shape that is convex or concave toward the inner diameter side. The variable valve timing device according to any one of claims 29 to 32, wherein a buffer material is coated on a portion where a gap is formed between the top of the cam crest of the internal gear and the roller. The variable valve timing device according to any one of claims 1 to 33, wherein the internal gear on the inner diameter surface of the cylindrical portion of the housing is formed of a separate internal gear that is fitted and fixed to the inner diameter surface of the cylindrical portion. The variable valve timing device according to claim 34, wherein the cam cam of the separate internal gear is formed by broach grinding, press punching or die forging. 36. The variable valve timing device according to claim 1, wherein a cam crest portion of the internal gear is induction-hardened. The variable valve timing device according to any one of claims 1 to 36, wherein an elastic member that presses the roller held in the pocket from both sides in the circumferential direction is provided in the cage portion of the intermediate shaft. 38. The variable valve timing device according to claim 37, wherein an elastic member that presses the roller from both sides in the circumferential direction is housed in a recess formed in an inner side surface facing the circumferential direction of the pocket of the cage portion. The variable valve timing apparatus according to claim 37 or 38, wherein the elastic member is a coil spring.

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