VALVE TIMING ADJUSTING APPARATUS

Abstract

A valve timing adjusting apparatus includes a driving-side rotor, a driven-side rotor, a sun gear, and a planet gear. The driving-side rotor is rotatable synchronously with the crankshaft. The driven-side rotor is received in the driving-side rotor and rotatable synchronously with a camshaft. The sun gear is rotatable integrally with the driving-side rotor. The planet gear moves epicyclically relative to the sun gear. The driving-side rotor includes a peripheral wall member and a bottom wall member. One of the sun gear and the bottom wall member is fitted with an inner peripheral side of one axial end portion of the peripheral wall member. The other one is fitted with an outer peripheral side of the other axial end portion of the peripheral wall member.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is based on and incorporates herein by reference Japanese Patent Application No. 2008-29433 filed on Feb. 8, 2008.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a valve timing adjusting apparatus capable of adjusting timing of a valve that is opened and closed by a camshaft through transmission of an engine torque from a crankshaft of an internal combustion engine.

2. Description of Related Art

A conventional valve timing adjusting apparatus is known to obtain a required valve timing by changing a relative phase relation between a driving-side rotor and a driven-side rotor. In the above, the driving-side rotor is rotatable synchronously with a crankshaft, and the driven-side rotor is rotatable synchronously with a camshaft. The above relative phase relation between the rotors is named as an “inter-rotor phase” in the present specification.

For example, FIG. 10 in JP-A-2007-255412 (corresponding to FIG. 10 in US20070199531) discloses a valve timing adjusting apparatus that has a driving-side rotor, a driven-side rotor having a planet gear, and a sun gear. The driving-side rotor has a hollow cylindrical shape with a bottom and receives the driven-side rotor within a peripheral wall portion thereof. The sun gear is fixed coaxially with the driving-side rotor on a side of the driving-side rotor opposite from the bottom wall portion of the driving-side rotor. Also, the sun gear is rotatable integrally with the driving-side rotor. The planet gear of the driven-side rotor is in mesh with the sun gear. In the above configuration, an epicyclic motion of the planet gear changes the inter-rotor phase between the rotors.

In the apparatus shown in JP-A-2007-255412 (FIG. 10), the driving-side rotor serving as a sprocket is engaged with or is in mesh with an annular timing chain that is engaged with the crankshaft such that the timing chain extends between and drivingly connects the driving-side rotor and the crankshaft. As a result, the timing chain transmits an engine torque between the driving-side rotor and the crankshaft. The driving-side rotor has a tubular shape with a bottom, and a bottom wall portion of the driving-side rotor has multiple teeth that are engaged with the timing chain. As a result, the driving-side rotor has a complex shape as a whole. In order to produce the above complicated driving-side rotor, for example, it is required to perform a complicated operation, such as extensively machining a column-molded blank, and thereby productivity may deteriorate disadvantageously.

In order to improve the productivity of the driving-side rotor, the inventors of the present invention have studied a technique, in which the driving-side rotor is made of separate two components (a peripheral wall portion and a bottom wall portion) that are coaxially fixed with each other. The driving-side rotor made as above has a tubular shape. Because each of the two components are separate from one another in the formation process, the formation of each component is effectively facilitated. However, it is found that the bottom wall portion and the sun gear may be displaced from each other when the engine torque is transmitted thereto because of a certain configuration, in which the sun gear, which is in mesh with the planet gear, and the bottom wall portion, which is engaged with the timing chain, are coaxially with each other with the peripheral wall portion interposed therebetween. The above possible displacement of the bottom wall portion and the sun gear may twist the peripheral wall portion interposed therebetween, and thereby the peripheral wall portion may deform in the radial direction. As a result, the unwanted change of the inter-rotor phase between the rotors may occur, and thereby the unwanted change in valve timing may occur disadvantageously.

SUMMARY OF THE INVENTION

The present invention is made in view of the above disadvantages. Thus, it is an objective of the present invention to address at least one of the above disadvantages.

To achieve the objective of the present invention, there is provided a valve timing adjusting apparatus for adjusting timing of a valve that is opened and closed by a camshaft through transmission of an engine torque from a crankshaft of an the internal combustion engine, the valve timing adjusting apparatus including a driving-side rotor, a driven-side rotor, a sun gear, and a planet gear. The driving-side rotor is rotatable synchronously with the crankshaft by transmission of the engine torque through an annular torque transmission member that extends between the crankshaft and the driving-side rotor. The driving-side rotor includes a peripheral wail member and a bottom wall member. The bottom wall member is fastened coaxially to the peripheral wall member and connected with the torque transmission member. The driven-side rotor is received in the driving-side rotor and rotatable synchronously with the camshaft. The sun gear is fastened coaxially to the peripheral wall member and rotatable integrally with the driving-side rotor. The planet gear is in mesh with the sun gear and moves epicyclically with respect to the sun gear such that a relative phase between the driving-side rotor and the driven-side rotor is changed. One of the sun gear and the bottom wall member is fitted with an inner peripheral side of one axial end portion of the peripheral wall member. The other one of the sun gear and the bottom wall member is fitted with an outer peripheral side of the other axial end portion of the peripheral wall member.

To achieve the objective of the present invention, there is also provided a valve timing adjusting apparatus for adjusting timing of a valve that is opened and closed by a camshaft through transmission of an engine torque from a crankshaft of an the internal combustion engine, the valve timing adjusting apparatus including a driving-side rotor, a driven-side rotor, a sun gear, and a planet gear. The driving-side rotor is rotatable synchronously with the crankshaft. The driving-side rotor includes a peripheral wall member and a bottom wall member that is fastened coaxially to the peripheral wall member. The bottom wall member is coupled with a torque transmission member that extends between the crankshaft and the driving-side rotor. The bottom wall member receives the engine torque transmitted through the torque transmission member. The driven-side rotor is received in the driving-side rotor and rotatable synchronously with the camshaft. The sun gear is fastened coaxially to the peripheral wall member and rotatable integrally with the driving-side rotor. The planet gear is in mesh with the sun near and moves epicyclically with respect to the sun gear such that a relative phase between the driving-side rotor and the driven-side rotor is changed. The peripheral wall member includes one axial end portion that extends in a longitudinal direction of the driving-side rotor, and the one axial end portion defines a first fitting hole therein that has a radially inner contact surface. One of the sun gear and the bottom wall member has a first fitting projection that extends in the longitudinal direction of the driving-side rotor, and the first fitting projection has a radially outer contact surface. The first fitting projection is fitted into the first fitting hole such that the radially inner contact surface of the first fitting hole is opposed to the radially outer contact surface of the first fitting projection in a radial direction of the driving-side rotor. The peripheral wall member includes the other axial end portion that serves as a second fitting projection extending in the longitudinal direction of the driving-side rotor, and the second fitting projection has a radially outer contact surface. The other one of the sun gear and the bottom wall member defines a second fitting hole therein that has a radially inner contact surface. The second fitting projection is fitted into the second fitting hole such that the radially inner contact surface of the second fitting hole is opposed to the radially outer contact surface of the second fitting projection in the radial direction of the driving-side rotor

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with additional objectives, features and advantages thereof, will be best understood from the following description, the appended claims and the accompanying drawings in which:

FIG. 1 is a cross-sectional view taken along line I-I in FIG. 2 illustrating a basic configuration of a valve timing adjusting apparatus according to the first embodiment of the present invention;

FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1;

FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1;

FIG. 4 is a cross-sectional view illustrating an enlarged phase adjustment mechanism in FIG. 1;

FIG. 5 is a cross-sectional view illustrating an enlarged phase adjustment mechanism of a valve timing adjusting apparatus according to the second embodiment of the present invention; and

FIG. 6 is a cross-sectional view illustrating a phase adjustment mechanism of a valve timing adjusting apparatus according to the third embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Multiple embodiments of the present invention will be described with reference to accompanying drawings. Note that, components in one of the embodiments that are similar to components in the other embodiment will be indicated by the same numerals, and thereby the overlapped explanation thereof will be omitted.

First Embodiment

FIG. 1 shows a valve timing adjusting apparatus 1 according to the first embodiment of the present invention. The valve timing adjusting apparatus 1 is mounted on a vehicle, and more specifically, the valve timing adjusting apparatus 1 is mounted on a transmission system that transmits an engine torque to a camshaft 2 from a crankshaft (not shown) of an internal combustion engine. It should be noted that in the present embodiment the camshaft 2 opens and closes an intake valve (not shown) that serves as a “valve” of the internal combustion engine through transmission of the engine torque, and thereby the valve timing adjusting apparatus 1 adjusts valve timing of the intake valve.

(Basic Configuration)

A basic configuration of the valve timing adjusting apparatus 1 of the first embodiment will be described below. The valve timing adjusting apparatus 1 includes an electric motor 4, an energization control circuit unit 7, and a phase adjustment mechanism 8.

The electric motor 4 is, for example, a brushless motor, and includes a motor case 5 and a motor shaft 6. The motor case 5 is fixed to a fixation part of an internal combustion engine, which is immovable relative to the engine, and the motor shaft 6 is supported by the motor case 5 rotatably in normal and reverse directions. The energization control circuit unit 7 includes a driver and a microcomputer that controls the driver. The energization control circuit unit 7 is provided outside and/or inside the motor case 5, and is electrically connected with the electric motor 4. The energization control circuit unit 7 controls energization of the motor 4 in order to rotate the motor shaft 6.

The phase adjustment mechanism 8 includes a driving-side rotor 10, a sun gear 12, a driven-side rotor 20, a planet gear carrier 40, and a planet gear 50.

As shown in FIGS. 1 to 3, the driving-side rotor 10 has a hollow cylindrical shape with a bottom, and the sun gear 12 has a hollow cylindrical shape with a bottom. The driving-side rotor 10 and the sun gear 12 are fixed coaxially with each other in a state where opening portions of the driving-side rotor 10 and the sun gear 12 overlap with each other in an axial direction. In the above way, the driving-side rotor 10 and the sun gear 12 define therebetween a reception space 14 that receives the other components 20, 40, 50 of the phase adjustment mechanism 8.

The driving-side rotor 10 has multiple teeth 15 that are arranged one after another in a rotational direction, and the multiple teeth 15 projects radially outwardly. An annular timing chain 16 is engaged with the teeth 15 of the driving-side rotor 10 and with multiple teeth (not shown) of the crankshaft, and thereby the timing chain 16 extends between and drivingly connects the driving-side rotor 10 and the crankshaft. The above coupling enables the transmission of the engine torque of the crankshaft to the driving-side rotor 10 through the timing chain 16 and causes the driving-side rotor 10 to rotate integrally with the sun gear 12 and synchronously with the crankshaft. The rotational direction of the driving-side rotor 10 and the sun gear 12 corresponds to a clockwise direction in FIGS. 2, 3.

As shown in FIGS. 1, 2, the sun gear 12 includes a driving-side internal gear 18 on a radially inner side of a peripheral wall portion of the sun gear 12, and the driving-side internal gear 18 defines an addendum circle located on a radially inner side of a root circle.

As shown in FIGS. 1, 3, the driven-side rotor 20 has a hollow cylindrical shape with a bottom, and is concentrically fitted with the driving-side rotor 10 on an inner peripheral side of the driving-side rotor 10. The driven-side rotor 20 has a connection member 21 on a bottom wall portion of the driven-side rotor 20, and the connection member 21 is coaxially coupled with the camshaft 2 through a threaded member. The above coupling enables the driven-side rotor 20 to rotate synchronously with the camshaft 2 and to rotate with respect to the driving-side rotor 10. The rotational direction of the driven-side rotor 20 corresponds to the clockwise direction in FIG. 3 similar to the driving-side rotor 10.

The driven-side rotor 20 includes a driven-side internal gear 22 on a radially inner side of the peripheral wall portion, and the driven-side internal gear 22 defines an addendum circle on a radially inner side of a root circle. The driven-side internal gear 22 has an inner diameter smaller than an inner diameter of the driving-side internal gear 18, and the number of teeth of the driven-side internal gear 22 is smaller than the number of teeth of the driving-side internal gear 18. The driven-side internal gear 22 is positioned away from the driving-side internal gear 18 in a longitudinal direction.

As shown in FIGS. 1 to 3, the planet gear carrier 40 generally has a tubular shape and has an inner peripheral surface that serves as an input portion 41. The input portion 41 is concentrically provided relative to the rotors 10, 20 and the motor shaft 6. The input portion 41 has a fitting groove 42 that is configured to be fitted with a coupling joint 43. The coupling joint 43 connects the motor shaft 6 with the planet gear carrier 40. The coupling enables the planet gear carrier 40 to rotate together with the motor shaft 6, and also to rotate with respect to the driving-side rotor 10 and the sun gear 12.

The planet gear carrier 40 has an outer peripheral surface, which is eccentric with respect to the input portion 41, and which serves as an eccentric portion 44. The eccentric portion 44 is concentrically fitted into a central hole 51 of the planet gear 50 through a bearing 45. Due to the above configuration, the eccentric portion 44 supports the planet gear 50 in order to enable an epicyclic motion of the planet gear 50 in accordance with a rotation of the planet gear carrier 40 with respect to the sun gear 12. In the epicyclic motion of the present embodiment, the planet gear 50 rotates about an eccentric axis of the eccentric portion 44, and also the planet gear 50 revolves relative to the sun gear 12 in the rotational direction of the planet gear carrier 40. In other words, the planet gear 50 rotates epicyclically with respect to the sun gear 12.

The planet gear 50 has a shouldered hollow cylindrical shape, and more specifically, the planet gear 50 has a large-diameter section and a small-diameter section that has a diameter smaller than that of the large-diameter section. Thus, the planet gear 50 defines a driving-side external gear 52 at the large-diameter section and a driven-side external gear 54 at the small-diameter section. Each of the driving-side external gear 52 and driven-side external gear 54 defines an addendum circle on a radially outer side of a root circle. The driving-side external gear 52 has the number of teeth that is smaller than the number of teeth of the driving-side internal gear 18 by a certain number. Also, the number of teeth of the driven-side external gear 54 is smaller than the number of teeth of the driven-side internal gear 22 by the number identical with the above certain number. The driving-side external gear 52 is provided on a radially inner side of the driving-side internal gear 18 and in mesh with the driving-side internal gear 18 Also, the driven-side external gear 54 is displaced from the driving-side external gear 52 toward the connection member 21. The driven-side external gear 54 is provided on a radially inner side of the driven-side internal gear 22 and in mesh with the driven-side internal gear 22.

The phase adjustment mechanism 8 gears to the rotors 10, 20 as above and adjusts an inter-rotor phase, which is a relative phase relation of the driven-side rotor 20 with respect to the driving-side rotor 10, in accordance with a rotational state of the motor shaft 6.

Specifically, in a case, where the planet gear carrier 40 is not rotated with respect to the sun gear 12 because the motor shaft 6 rotates at the speed that is equivalent to the rotational speed of the driving-side rotor 10, the epicyclic motion of the planet gear 50 is not caused. Accordingly, the planet gear 50 rotates together with the rotors 10, 20. As a result, the inter-rotor phase is not changed, and accordingly, the valve timing is held.

In contrast, in a case, where the planet gear carrier 40 rotates relative to the sun gear 12 in an advance direction because the motor shaft 6 rotates at a speed higher than the rotational speed of the driving-side rotor 10, the epicyclic motion of the planet gear 50 is caused. Accordingly, the driven-side rotor 20 rotates relative to the driving-side rotor 10 in the advance direction. As a result, the inter-rotor phase is changed in the advance direction, and accordingly the valve timing is advanced.

Also, in another case, where the planet gear carrier 40 rotates relative to the sun gear 12 in a retard direction because the motor shaft 6 rotates in a reverse direction or rotates at a speed lower than the rotational speed of the driving-side rotor 10, the epicyclic motion of the planet gear 50 is caused. Accordingly, the driven-side rotor 20 rotates relative to the driving-side rotor 10 in the retard direction. As a result, the inter-rotor phase is changed in the retard direction, and accordingly the valve timing is retarded.

(Characteristic Part)

Characteristic part of the first embodiment will be described.

(Fastening Structure of Driving-Side Rotor and Sun Gear)

As shown in FIG. 1, the driving-side rotor 10 includes a metal bottom wall member 100, a metal peripheral wall member 110, and threaded members 120.

As shown in FIG. 4, the bottom wall member 100 has an annular plate shape and has a thick wall. The bottom wall member 100 constitutes a sprocket that has the teeth 15 engaged with the timing chain 16. The bottom wall member 100 has a fitting hole 102 defined at a radial center thereof. The fitting hole 102 is a hole having a bottom surface 104 and opens at one axial end surface 101 of the bottom wall member 100. Also, the bottom wall member 100 has a through hole 105 defined at the radial center thereof. The through hole 105 opens at the other axial end surface 103 of the bottom wall member 100 and at the bottom surface 104 of the fitting hole 102 and receives the camshaft 2.

The peripheral wall member 110 has a shouldered or stepped hollow cylindrical shape that has a different diameter at a different position in the longitudinal direction. The peripheral wall member 110 has one axial end portion 111 having a smaller diameter than the other part of the peripheral wall member 110, and the one axial end portion 111 is press-fitted into the fitting hole 102 of the bottom wall member 100. The one axial end portion 111 has a radially outer contact surface, and the fitting hole 102 has a radially inner contact surface. Thus, in a state, where the one axial end portion 111 is press-fitted into the fitting hole 102 of the bottom wall member 100, the radially inner contact surface of the fitting hole 102 is opposed to the radially outer contact surface of the axial end portion 111 in a radial direction of the driving-side rotor 10. In other words, the one axial end portion 111 of the peripheral wall member 110 has an outer peripheral side that is press-fitted with the bottom wall member 100. Due to the above fitting, the peripheral wall member 110 defines therein a space 14a, which is a part of the reception space 14, as shown in FIGS. 3, 4. The space 14a receives an entirety of the driven-side rotor 20 and part of each of the planet gear carrier 40 and the planet gear 50. Also, as shown in FIGS. 2, 4, the peripheral wall member 110 has a fitting hole 114 defined at a radial center thereof. The fitting hole 114 is a hole with a bottom and opens at an end surface 113 of the other axial end portion 112. The other axial end portion 112 has a diameter greater than that of the one axial end portion 111, and is located on a side of the peripheral wall member 110 opposite from the one axial end portion 111 in the longitudinal direction.

As shown in FIGS. 3, 4, each of the threaded members 120 is made of a metal bolt, and the threaded members 120 are provided at multiple positions. The bottom wall member 100 and the peripheral wall member 110 are arranged coaxial with each other, and the threaded members 120 are provided at predetermined positions of the wall members 100, 110 in the rotational direction in order to fasten the bottom wall member 100 with the peripheral wall member 110 in the above coaxial state. As above, the bottom wall member 100, the peripheral wall member 110, and the threaded members 120 constitute the driving-side rotor 10 having a hollow cylindrical shape with a bottom.

As shown in FIGS. 2, 4, the sun gear 12 includes a fitting projection 130 having a hollow cylindrical shape at an opening portion thereof and the fitting projection 130 is press-fitted into the fitting hole 114 of the peripheral wall member 110. The fitting projection 130 has a radially outer contact surface, and the fitting hole 114 has a radially inner contact surface. Thus, in a state, where the fitting projection 130 of the sun gear 12 is press-fitted into the fitting hole 114 of the other axial end portion 112 of the peripheral wall member 110, the radially inner contact surface of the fitting hole 114 is opposed to the radially outer contact surface of the fitting projection 130 in the radial direction of the driving-side rotor 10. In other words, the sun gear 12 is press-fitted with an inner peripheral side of the other axial end portion 112 of the peripheral wall member 110. Due to the above fitting, the sun gear 12 defines a space 14b, which is another part of the reception space 14, at an inner peripheral side of the driving-side internal gear 18. The space 14b is configured to receive the remaining of each of the planet gear carrier 40 and the planet gear 50, which is not received by the space 14a. The sun gear 12 is fastened together with the bottom wall member 100 and the peripheral wall member 110 by the multiple threaded members 120 at multiple positions in the rotational direction. Thus, the sun gear 12 is fastened coaxially with the peripheral wall member 110. In other words, in the present embodiment, the sun gear 12 is arranged coaxially with the bottom wall member 100, and the peripheral wall member 110 is provided between the sun gear 12 and the bottom wall member 100 in the longitudinal direction.

(Stopper Structure)

As shown in FIG. 3, the peripheral wall member 110 is provided with advance stopper surfaces 140 to 143 extending from an inner peripheral surface 116 of the peripheral wall member 110 in a generally radially inward direction and arranged circumferentially or in the rotational direction one after another at multiple positions of the inner peripheral surface 116. Thus, each of the advance stopper surfaces 140 to 143 has a step surface shape as shown in FIG. 3. Also, the peripheral wall member 110 has retard stopper surfaces 150 to 153 extending from the inner peripheral surface 116 in the generally radially inward direction and arranged in the rotational direction one after another at multiple positions of the inner peripheral surface 116. Thus, each of the retard stopper surfaces 150 to 153 has a step surface shape. Each of the retard stopper surfaces 150 to 153 is spaced apart in the rotational direction from a corresponding one of the advance stopper surfaces 140 to 143. As shown in FIG. 3, the retard stopper surface 150 is opposed to the advance stopper surface 140, the retard stopper surface 151 is opposed to the advance stopper surface 141, the retard stopper surface 152 is opposed to the advance stopper surface 142, and the retard stopper surface 153 is opposed to the advance stopper surface 143.

As shown in FIGS. 1, 3, the driven-side rotor 20 is provided with stopper projections 160 to 163 that projects from the peripheral wall portion of the driven-side rotor 20 in the radially outward direction of the driven-side internal gear 22. Also, the stopper projections 160 to 163 are arranged at multiple positions of the peripheral wall portion in the rotational direction. Each of the stopper projections 160 to 163 is positioned between the corresponding one of pairs of the advance stopper surfaces 140 to 143 and the retard stopper surfaces 150 to 153. More specifically, the stopper projection 160 is provided between the advance stopper surface 140 and the retard stopper surface 150, for example.

In the present embodiment, in a state, where the stopper projection 160 contacts the advance stopper surface 140 that is positioned on an advance side of the stopper projection 160 in the rotational direction, the driven-side rotor 20 is limited from rotating relative to the driving-side rotor 10 in the advance direction. In other words, the change of the inter-rotor phase in the advance direction is restricted. In contrast, in a state, where the stopper projection 160 contacts the retard stopper surface 150 that is positioned on a retard side of the stopper projection 160 in the rotational direction, the driven-side rotor 20 is limited from rotating relative to the driving-side rotor 10 in the retard direction. In other words, the change of the inter-rotor phase in the retard direction is restricted. As above, the group of the advance stopper surface 140, the retard stopper surface 150, and the stopper projection 160 function as a phase change restriction in a normal operation.

In an abnormal case, where there is a failure in the above normal group of components 140, 150, 160, a first alternative group including the stopper surfaces 141, 151 and the stopper projection 161, a second alternative group including the stopper surfaces 142, 152 and the stopper projection 162, and a third alternative group including the stopper surfaces 143, 153 and the stopper projection 163 may alternatively function as the above phase change restriction of the normal group.

(Method for Manufacturing Bottom Wall Member and Peripheral Wall Member)

Each of the bottom wall member 100 and the peripheral wall member 110 of the driving-side rotor 10 is formed by a cutting operation (machining operation) of a molded body made through a near net shape technique.

More specifically, in the formation process of the bottom wall member 100, firstly, a powder metallurgy material is molded and sintered such that the sintered body has a annular plate shape similar to the final shape of the finished product of the bottom wall member 100. As above, a bottom wall member blank is formed to serve as the near net shape molded body. Then, the cutting operation is performed to a peripheral surface and a end surface of the bottom wall member blank, and thereby the bottom wall member 100 having the multiple teeth 15 and the holes 102, 105 is completed.

Also, in the forming process of the peripheral wall member 110, firstly, a powder metallurgy material is molded and sintered such that the sintered body has a hollow cylindrical shape similar to the final shape of the finished product of the peripheral wall member 110. As above, a peripheral wall member blank is formed to serve as the near net shape molded body. Then, a peripheral surface and an end surface of the peripheral wall member blank is cut, and thereby the peripheral wall member 110 having the hole 114 and the stopper surfaces 140 to 143, 150 to 153 is completed.

The powder metallurgy material used for forming the bottom wall member 100 and the peripheral wall member 110 may be selected from various metal materials in accordance with specifications. For example, in the present embodiment, alloy steel powder including copper is employed as the powder metallurgy material. Also, in the present embodiment, the sun gear 12, the driven-side rotor 20, the planet gear carrier 40, and the planet gear 50 may be also formed by the cutting operation of the near net shape molded body similar to the case for the bottom wall member 100 and the peripheral wall member 110.

In the above described first embodiment, the bottom wall member 100 and the peripheral wall member 110 are separate bodies and are fastened to each other to constitute the driving-side rotor 10. It is possible to easily form the bottom wall member 100 and the peripheral wall member 110 by the cutting of the near net shape molded body. More specifically, the stopper surfaces 140 to 143, 150 to 153 having the step surface shape are provided on the inner peripheral surface 116 of the peripheral wall member 110. Because the peripheral wall member 110 is separate from the bottom wall member 100, the above stopper surfaces 140 to 143, 150 to 153 are further easily made by the cutting operation. Furthermore, in the first embodiment, the threaded member 120 fastens the bottom wall member 100 with the peripheral wall member 110 in order to form the driving-side rotor 10. Because the above threaded member 120 is also used to fasten the sun gear 12 with the driving-side rotor 10, a fastening structure of the driving-side rotor 10 and the sun gear 12 is easily realized or obtained. In the first embodiment, productivity of the valve timing adjusting apparatus 1 is effectively improved.

Also, according to the first embodiment, the sun gear 12, which is in mesh with the planet gear 50, and the bottom wall member 100, which is engaged with the timing chain 16 transmitting the engine torque, are provided coaxially with each other on opposite axial sides of the peripheral wall member 110. As a result, the sun gear 12 may be displaced relative to the bottom wall member 100 while transmitting the engine torque in the conventional art. However, the sun gear 12 is fitted with the inner peripheral side of the other axial end portion 112 of the peripheral wall member 110, and the bottom wall member 100 is fitted with the outer peripheral side of the one axial end portion 111 of the peripheral wall member 110. In other words, the sun gear 12 is fitted into the other axial end portion 112, and the one axial end portion 111 is fitted into the bottom wall member 100. As a result, even when the peripheral wall member 110 receives a torsional force caused by the displacement of the sun gear 12 relative to the bottom wall member 100, one of the axial end portions 111, 112 is urged radially inwardly by the other one of the axial end portions 111, 112, and thereby the peripheral wall member 110 is limited from deforming in the radial direction. Furthermore, in the first embodiment, boundary surfaces between the sun gear 12 and the peripheral wall member 110 are press fitted with each other. Also, the other boundary surfaces between the bottom wall member 100 and the peripheral wall member 110 are press fitted with each other. Due to the above configuration, clearances that otherwise allow the deformation of the axial end portions 112, 111 of the peripheral wall member 110 in the radial direction are substantially eliminated. Still more, in the first embodiment, because the components 12, 100, 110 are fastened to each other commonly by the threaded members 120, torsion of the peripheral wall member 110 cased by the displacement of the components 12, 100 is restricted by the threaded members 120. According to the first embodiment, even in a condition, where the displacement of the components 12, 100 from each other is prone to occur because of the engine torque highly efficiently transmitted through the multiple teeth 15 engaged with the timing chain 16, the unwanted change of the inter-rotor phase caused by the deformation of the peripheral wall member 110 is effectively restricted as above, and thereby accuracy in adjustment of the valve timing is effectively improved.

In addition to the above, according to the first embodiment, when the stopper projection 160 of the driven-side rotor 20 contacts, in the rotational direction, one of the stopper surfaces 140, 150 defined on the inner peripheral surface 116 of the peripheral wall member 110, deformation of the peripheral wall member 110 in the radial direction may occur in the conventional art. However, in the first embodiment, the peripheral wall member 110 is limited from deforming in the radial direction as above, and thereby even when the stopper projection 160 contacts either one of the stopper surfaces 140, 150, the unwanted change of the inter-rotor phase is restricted. As a result, accuracy in adjustment of the valve timing is effectively improved.

It should be noted that in the first embodiment, the timing chain 16 serves as a “torque transmission member”, and the threaded member 120 serves as a “fastening member”. The fitting hole 114 serves as “first fitting hole”, and the fitting projection 130 serves as “first fitting projection”. Also, the fitting hole 102 serves as “second fitting hole”, and the axial end portion 111 serves as “second fitting projection”.

Second Embodiment

As shown in FIG. 5, the second embodiment of the present invention is modification of the first embodiment. In the second embodiment, a metal bottom wall member 2100 constituting a driving-side rotor 2010 includes a fitting projection 2102 instead of the fitting hole 102. The fitting projection 2102 has a hollow cylindrical shape defining therein a central hole. The central hole corresponds to a part of the through hole 105.

Also, a metal peripheral wall member 2110 constituting the driving-side rotor 2010 has a shouldered or stepped hollow cylindrical shape. The shouldered hollow cylindrical shape has a different diameter at a different position of the shouldered hollow cylindrical shape in the longitudinal direction. The peripheral wall member 2110 has one axial end portion 2111 and the other axial end portion 2112, and the one axial end portion 2111 has a diameter greater than that of the other axial end portion 2112. The peripheral wall member 2110 defines a fitting hole 2114 with a bottom at a generally central part thereof, and the fitting hole 2114 opens at an end surface 2113 of the one axial end portion 2111. The fitting projection 2102 of the bottom wall member 2100 is press-fitted into the fitting hole 2114. In other words, the bottom wall member 2100 is press-fitted with an inner peripheral side of the one axial end portion 2111 of the peripheral wall member 2110.

A sun gear 2012 defines a fitting hole 2014 with a bottom at a generally central part thereof. The fitting hole 2014 opens at one end surface 2013 of the sun gear 2012. The fitting hole 2014 is press-fitted with the other axial end portion 2112 of the peripheral wall member 2110. In other words, the sun gear 2012 is press-fitted with an outer peripheral side of the other axial end portion 2112 of the peripheral wall member 2110.

As above, in the second embodiment, in a state, where the peripheral wall member 2110 is provided between the bottom wall member 2100 and the sun gear 2012 in the longitudinal direction, the above components 2012, 2100, 2110 are fastened coaxial with each other by the threaded member 120 of the driving-side rotor 2010. Thus, the above components 2012, 2100, 2110 are integral with each other. The bottom wall member 2100 is fitted with the inner peripheral side of the one axial end portion 2111 of the peripheral wall member 2110, and the sun gear 2012 is fitted with the outer peripheral side of the other axial end portion 2112 of the peripheral wall member 2110. Even when the peripheral wall member 2110 receives a torsion force caused by the components 2100, 2012 that tend to be displaced from each other, the peripheral wall member 2110 is limited from deforming in the radial direction due to the mechanism similar to the first embodiment. Also, because the boundary surfaces of the components are pressed fitted with each other as above, a clearance that otherwise enables the deformation of the peripheral wall member 2110 is substantially eliminated similar to the first embodiment. Also, the threaded member 120 is capable of restricting the twist of the peripheral wall member 2110 similar to the first embodiment. As a result, also in the second embodiment, the unwanted change of the inter-rotor phase caused by deformation of the peripheral wall member 2110 is limited, and thereby it is possible to accurately adjust the valve timing. In addition to the above, in the second embodiment, the bottom wall member 2100 and the peripheral wall member 2110 are separately formed by the cutting operation of cutting the near net shape molded body similar to the first embodiment. As a result, the extensive cutting operation is effectively avoided, and thereby productivity is effectively improved. In the present embodiment, the fitting projection 2102 serves as “first fitting projection”, and the fitting hole 2114 serves as “first fitting hole”. Also, the axial end portion 2112 serves as “second fitting projection”, and the fitting hole 2014 serves as “second fitting hole”.

Third Embodiment

As shown in FIG. 6, the third embodiment of the present invention is modification of the second embodiment. In the third embodiment, a metal peripheral wall member 3110 constituting a driving-side rotor 3010 has a straight hollow cylindrical shape that has a substantially constant diameter over a length or in a longitudinal direction of the driving-side rotor 3010. In other words, the peripheral wall member 3110 has a hollow cylindrical shape extending straight in the longitudinal direction of the peripheral wall member 3110. It should be noted that the peripheral wall member 3110 has the stopper surfaces 140 to 143, 150 to 153 (not shown) at an inner peripheral surface of the peripheral wall member 3110, and each of the stopper surfaces 140 to 143, 150 to 153 has a step surface shape. In the present embodiment, for example, each of the above stopper surfaces 140 to 143, 150 to 153 has a shape that extends straight in the longitudinal direction from one axial end to the other axial end of each stopper surface. Also, the inner peripheral surface between the adjacent stopper surfaces has a shape that extends straight in the longitudinal direction from one axial end to the other axial end of the inner peripheral surface. Thus, the driving-side rotor 3010 extends straight from the one axial end portion 2111 to the other axial end portion 2112 in the longitudinal direction of the driving-side rotor 3010.

According to the peripheral wall member 3110 having the above straight shape, it is more easy to execute the near net shape molding operation for forming the peripheral wall member blank and the cutting operation of cutting the peripheral wall member blank compared with the case of molding or machining the shouldered member bank. As a result, productivity is substantially effectively improved.

Other Embodiment

Although the multiple embodiments of the present invention have been described as above, the interpretation of the present invention is not limited to the above embodiments. Thus, the present invention is applicable to various embodiments provided that the various embodiments do not deviate from the gist of the present invention.

More specifically, “torque transmission member” that transmits the engine torque to the driving-side the rotors 10, 2010, 3010 may employ, for example, a timing belt that is engaged with the bottom wall member 100, 2100 and with the multiple teeth 15, in place of the timing chain 16.

In place of the above described press fitting, the fitting of the bottom wall member 100, 2100 with the peripheral wall member 110, 2110, 3110, and the fitting of the sun gear 12, 2012 with the peripheral wall member 110, 2110, 3110 may be realized even when the boundary surfaces of the above components are fitted with each other with a clearance defined therebetween. Also, at least the bottom wall member 100, 2100 and the peripheral wall member 110, 2110, 3110 may be formed by cutting a alternative near net shape molded body formed by the other process other than the sintering of the powder metallurgy material. For example, the alternative near net shape molded body may be alternatively formed by forging a metal material.

The “fastening member” that fastens at least the bottom wall member 100, 2100 and the peripheral wall member 110, 2110, 3110 may alternatively employ, for example, a rivet, or a pin in place of the threaded member 120. Also, the sun gear 12, 2012 may be alternatively fastened to the peripheral wall member 110, 2110, 3110 by another “fastening member” in addition to the “fastening member” that fastens the bottom wall member 100, 2100 with the peripheral wall member 110, 2110, 3110.

In the above, the planet gear 50 gears to the sun gear 12, 2012 and to the gear 22 of the driven-side rotor 20 in the phase adjustment mechanism 8. However, the phase adjustment mechanism 8 may alternatively have another configuration, in which, an alternative planet gear gears only to a sun gear that is fastened to the driving-side the rotors 10, 2010, 3010, for example. In the above alternative case, the driven-side rotor 20 is rotated relative to the driving-side the rotors 10, 2010, 3010 in accordance with the epicyclic motion of the alternative planet gear. Also, the sun gear that is fastened to the driving-side the rotors 10, 2010, 3010 is meshed with the planet gear through the internal gear 18 as above. However, the sun gear may alternatively be meshed with the external gear of the planet gear.

In the above embodiments, the apparatus adjusts valve timing of the intake valve. However, the present invention may be applicable to an apparatus that adjusts valve timing of an exhaust valve serving as a “valve” and to an apparatus that adjusts valve timing of both the intake valve and the exhaust valve.

Additional advantages and modifications will readily occur to those skilled in the art. The invention in its broader terms is therefore not limited to the specific details, representative apparatus, and illustrative examples shown and described.

Claims

1. A valve timing adjusting apparatus for adjusting timing of a valve that is opened and closed by a camshaft through transmission of an engine torque from a crankshaft of an the internal combustion engine, the valve timing adjusting apparatus comprising: a driving-side rotor that is rotatable synchronously with the crankshaft by transmission of the engine torque through an annular torque transmission member that extends between the crankshaft and the driving-side rotor, wherein: the driving-side rotor includes a peripheral wall member and a bottom wall member; andthe bottom wall member is fastened coaxially to the peripheral wall member and connected with the torque transmission member;a driven-side rotor that is received in the driving-side rotor and rotatable synchronously with the camshaft;a sun gear that is fastened coaxially to the peripheral wall member and rotatable integrally with the driving-side rotor; anda planet gear that is in mesh with the sun gear and moves epicyclically with respect to the sun gear such that a relative phase between the driving-side rotor and the driven-side rotor is changed, wherein:one of the sun gear and the bottom wall member is fitted with an inner peripheral side of one axial end portion of the peripheral wall member; andthe other one of the sun gear and the bottom wall member is fitted with an outer peripheral side of the other axial end portion of the peripheral wall member.

2. The valve timing adjusting apparatus according to claim 1, wherein: the one of the sun gear and the bottom wall member is press fitted with the inner peripheral side of the one axial end portion of the peripheral wall member such that the one of the sun gear and the bottom wall member is press fitted into the one axial end portion; andthe other one of the sun gear and the bottom wall member is press fitted with the outer peripheral side of the other axial end portion of the peripheral wall member such that the other axial end portion is press fitted into the other one of the sun gear and the bottom wall member.

3. The valve timing adjusting apparatus according to claim 1, wherein: the driving-side rotor includes at least one fastening member that fastens the peripheral wall member with the bottom wall member; andthe at least one fastening member fastens the sun gear together with the peripheral wall member and the bottom wall member.

4. The valve timing adjusting apparatus according to claim 1, wherein: the bottom wall member is a sprocket having a plurality of teeth that are engaged with the torque transmission member.

5. The valve timing adjusting apparatus according to claim 1, wherein: the peripheral wall member includes a stopper surface at an inner peripheral surface of the peripheral wall member; andthe stopper surface has a step surface shape that contacts the driven-side rotor in a rotational direction such that change of the relative phase is limited.

6. The valve timing adjusting apparatus according to claim 1, wherein: the peripheral wall member has a tubular shape extending straight in a longitudinal direction of the peripheral wall member.

7. The valve timing adjusting apparatus according to claim 1, wherein: each of the peripheral wall member and the bottom wall member is formed by cutting a corresponding near net shape molded body.

8. A valve timing adjusting apparatus for adjusting timing of a valve that is opened and closed by a camshaft through transmission of an engine torque from a crankshaft of an the internal combustion engine, the valve timing adjusting apparatus comprising: a driving-side rotor that is rotatable synchronously with the crankshaft, wherein: the driving-side rotor includes a peripheral wall member and a bottom wall member that is fastened coaxially to the peripheral wall member;the bottom wall member is coupled with a torque transmission member that extends between the crankshaft and the driving-side rotor; andthe bottom wall member receives the engine torque transmitted through the torque transmission member;a driven-side rotor that is received in the driving-side rotor and rotatable synchronously with the camshaft;a sun gear that is fastened coaxially to the peripheral wall member and rotatable integrally with the driving-side rotor; anda planet gear that is in mesh with the sun gear and moves epicyclically with respect to the sun gear such that a relative phase between the driving-side rotor and the driven-side rotor is changed, wherein:the peripheral wall member includes one axial end portion that extends in a longitudinal direction of the driving-side rotor, the one axial end portion defining a first fitting hole therein that has a radially inner contact surface;one of the sun gear and the bottom wall member has a first fitting projection that extends in the longitudinal direction of the driving-side rotor, the first fitting projection having a radially outer contact surface;the first fitting projection is fitted into the first fitting hole such that the radially inner contact surface of the first fitting hole is opposed to the radially outer contact surface of the first fitting projection in a radial direction of the driving-side rotor;the peripheral wall member includes the other axial end portion that serves as a second fitting projection extending in the longitudinal direction of the driving-side rotor, the second fitting projection having a radially outer contact surface;the other one of the sun gear and the bottom wall member defines a second fitting hole therein that has a radially inner contact surface; andthe second fitting projection is fitted into the second fitting hole such that the radially inner contact surface of the second fitting hole is opposed to the radially outer contact surface of the second fitting projection in the radial direction of the driving-side rotor.

9. The valve timing adjusting apparatus according to claim 8, wherein: the first fitting projection is press fitted into the first fitting hole; andthe second fitting projection is press fitted into the second fitting hole.

10. The valve timing adjusting apparatus according to claim 8, wherein: the driving-side rotor includes at least one fastening member that fastens the peripheral wall member with the bottom wall member; andthe at least one fastening member fastens the sun gear together with the peripheral wall member and the bottom wall member.

11. The valve timing adjusting apparatus according to claim 8, wherein: the bottom wall member is a sprocket having a plurality of teeth that are engaged with the torque transmission member.

12. The valve timing adjusting apparatus according to claim 8, wherein: the peripheral wall member includes a stopper surface at an inner peripheral surface of the peripheral wall member; andthe stopper surface has a step surface shape that contacts the driven-side rotor in a rotational direction such that change of the relative phase is limited.

13. The valve timing adjusting apparatus according to claim 8, wherein: the peripheral wall member has a tubular shape extending straight from the one axial end portion to the other axial end portion in a longitudinal direction of the peripheral wall member.

14. The valve timing adjusting apparatus according to claim 8, wherein: each of the peripheral wall member and the bottom wall member is formed by cutting a corresponding near net shape molded body.