METHOD OF ASSEMBLING VARIABLE VALVE TIMING APPARATUS

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 U.S.C. §119 to Japanese Patent Application 2012-018682, filed on Jan. 31, 2012 the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

This disclosure generally relates to a method of assembling a variable valve timing apparatus.

BACKGROUND DISCUSSION

A variable valve timing apparatus including a lock mechanism to lock relative phase of a driving-side rotation body and a driven-side rotation body at either most retarded angle or most advanced angle is known. An example of such mechanism is provided with a lock member, which is a projecting and retracting member, on one of the driving-side rotation body and the driven-side rotation body and with a recess for engaging the lock member on the other one of the driving-side rotation body and the driven-side rotation body. A clearance is provided between the lock member and the recess for engaging the lock member so that the lock member may be inserted into the recess smoothly. In a state where the clearance is excessively large, the lock member repeatedly collides with an inner surface of the recess at a start of an engine and generates abnormal noise until an operation chamber is filled with operation oil. In order to prevent the abnormal noise, an appropriate amount of clearance is required between the projecting and retracting member and the recess for engaging the projecting and retracting member.

An example of a method of assembling a variable valve timing apparatus defined with an appropriate amount of clearance between a lock member, which is a projecting and retracting member, and a recess for engaging the lock member includes a step of locking relative phase of a driven-side rotation body and a rotor body, which is a driving-side rotation body, by making a partition member of the driven-side rotation body contact with an end surface in a direction of most advanced angle of a fluid chamber, which is formed on an inner peripheral side of the rotor body, followed by a step of inserting the lock member into the recess for engaging the lock member formed on a sprocket, which is a member of the driving-side rotation body, and rotating the sprocket relative to the driven-side rotation body so that the lock member makes contact with an inner surface of the recess for engaging the lock member, and a step that follows to fasten the sprocket of the driving-side rotation body and the rotor body in a state where clearance between the lock member and the recess for engaging the lock member is appropriately defined by providing a space between the lock member and the inner surface of the recess by rotating the sprocket and the driven-side rotation body relative to each other.

A variable valve timing apparatus disclosed in JP2001-241307A, hereinafter referred to as Reference 1, is an example of a variable valve timing apparatus provided with a lock mechanism that locks relative phase of a driving-side rotation body and a driven-side rotation body at an intermediate position, which is a position between most retarded angle and most advanced angle. The variable valve timing apparatus disclosed in Reference 1 is an example of a variable valve timing apparatus provided with restricting members, each of which is a projecting and retracting member, separately for restricting the relative phase to shift in a direction of retard angle and for restricting the relative phase to shift in a direction of advance angle. An example of a variable valve timing apparatus provided with two lock members, which are projecting and retracting members, serving as a lock mechanism that locks relative phase of a driving-side rotation body and a driven-side rotation body at most retarded angle is also known.

The variable valve timing apparatus disclosed in Reference 1 is provided with two restricting members, which are projecting and retracting members, provided on a front plate of a driving-side rotation body and arranged parallel to an axial direction of the driving-side rotation body. Grooves to restrict the restricting members are formed on a driven-side rotation body. In a configuration where each of two restricting members are provided on the front plate, clearance between one of the restricting members and the groove corresponding to the aforementioned one of the restricting members is defined in a direction of most retarded angle and clearance between the other restricting member and the groove corresponding to the aforementioned other restricting member is defined in a direction of most advanced angle. Accordingly, a variable valve timing apparatus provided with a lock mechanism having a multiple number of restricting members, which are projecting and retracting members, to lock relative phase of the driving-side rotation body and the driven-side rotation body at an intermediate position is provided with a disadvantage on defining an appropriate amount of clearance between each of the restricting members and the groove, or recesses for engagement, corresponding to the restricting member. As a result, abnormal noise, which is caused by the restricting members repeatedly colliding with the grooves to restrict the restriction members by the restricting members changing positions within the grooves, is not effectively restricted.

A need thus exists for a method of assembling a variable valve timing apparatus, which is not susceptible to the drawback mentioned above.

SUMMARY

A method of assembling a variable valve timing apparatus includes the variable timing apparatus that includes a driving-side rotation body including a base member provided with at least one supplementary member, the driving-side rotation body synchronously rotating with a crankshaft of an internal combustion engine, a driven-side rotation body coaxially arranged with the driving-side rotation body and integrally rotating with a camshaft for opening and closing valves of the internal combustion engine, a fluid pressure chamber formed between the driving-side rotation body and the driven-side rotation body, the fluid pressure chamber divided into an advance chamber and a retard chamber by a partition member provided on at least one of the driving-side rotation body and the driven-side rotation body, and a first projecting and retracting member and a second projecting and retracting member selectively engaging with the driving-side rotation body and the driven-side rotation body to lock relative rotational phase of the driving-side rotation body and the driven-side rotation body at a predetermined phase or to restrict relative rotational phase of the driving-side rotation body and the driven-side rotation body within a predetermined range. The method of assembling a variable valve timing apparatus includes steps of temporarily fixing the driven-side rotation body relative to the base member in a first rotation restricting state by a process of engaging the first projecting and retracting member with the base member and the driven-side rotation body followed by a process of rotating either the base member or the driven-side rotation body to establish a state where the driven-side rotation body rotates in one direction either in an advance direction or in a retard direction relative to the base member, providing the supplementary member to the driven-side rotation body to establish a second rotation restricting state by a process of installing the supplementary member to the base member in a state where the second projecting and retracting member engages with the supplementary member and the driven-side rotation body followed by a process of rotating either the supplementary member or the driven-side rotation body to establish a state where the supplementary member rotates in said one direction relative to the driven-side rotation body, and fastening the supplementary member and the base member by a use of a fastening member.

A method of assembling a variable valve timing apparatus includes the variable valve timing apparatus that includes a driving-side rotation body including a first driving-side rotation member and a second driving-side rotation member, the driving-side rotation body synchronously rotating with a crankshaft of an internal combustion engine, a driven-side rotation body coaxially arranged with the driving-side rotation body and integrally rotating with a camshaft for opening and closing valves of the internal combustion engine, a fluid pressure chamber formed between the driving-side rotation body and the driven-side rotation body, the fluid pressure chamber divided into an advance chamber and a retard chamber by a partition member provided on at least one of the driving-side rotation body and the driven-side rotation body, and a first projecting and retracting member and a second projecting and retracting member selectively engaging with the driving-side rotation body and the driven-side rotation body to lock relative rotational phase of the driving-side rotation body and the driven-side rotation body at a predetermined phase or to restrict relative rotational phase of the driving-side rotation body and the driven-side rotation body within a predetermined range. The method of assembling a variable valve timing apparatus includes steps of temporarily fixing the driven-side rotation body in a first rotation restricting state where rotation of the driven-side rotation body is restricted to one direction relative to the first driving-side rotation member following a process of engaging the first projecting and retracting member with the first driving-side rotation member and the driven-side rotation body, providing the driven-side rotation body to the second driving-side rotation member to establish a second rotation restricting state where rotation of the driven-side rotation body relative to the second driving-side rotation member is restricted to the aforementioned one direction or to a direction opposite to the aforementioned one direction following a process of installing the second driving-side rotation member to the first driving-side rotation member in a state where the second projecting and retracting member engages with the second driving-side rotation member and the driven-side rotation body, and fastening the first driving-side rotation member and the second driving-side rotation member by a use of a fastening member.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and additional features and characteristics of this disclosure will become more apparent from the following detailed description considered with the reference to the accompanying drawings, wherein:

FIG. 1 is a cross-sectional view of a variable valve timing apparatus according to a first embodiment installed on an engine;

FIG. 2 is a cross-sectional view of the variable valve timing apparatus according to the first embodiment in a given state taken along line II-II in FIG. 1 and viewed from a direction indicated by arrows;

FIG. 3 is a process in a method of assembling the variable valve timing apparatus according to the first embodiment;

FIG. 4 is a process in the method of assembling the variable valve timing apparatus according to the first embodiment;

FIG. 5 is a process in the method of assembling the variable valve timing apparatus according to the first embodiment;

FIG. 6 is a cross-sectional view of an outer rotor and an inner rotor of the variable valve timing apparatus according to a second embodiment;

FIG. 7 is a process in a method of assembling the variable valve timing apparatus according to the second embodiment;

FIG. 8 is a process in the method of assembling the variable valve timing apparatus according to the second embodiment; and

FIG. 9 is a process in the method of assembling the variable valve timing apparatus according to the second embodiment.

DETAILED DESCRIPTION

A method of assembling a variable valve timing apparatus 100 according to a first embodiment is described referring to drawings.

As FIGS. 1 and 2 illustrate, the variable valve timing apparatus 100 includes an outer rotor 1, which serves as an example of a driving-side rotation body. The outer rotor 1 rotates in a rotational direction S shown in FIG. 2 synchronously with a crankshaft C of an engine E, which serves as an internal combustion engine. The variable valve timing apparatus 100 also includes an inner rotor 3, which serves as an example of a driven-side rotation body. The inner rotor 3 is rotationally supported to an inner periphery of the outer rotor 1 such that the inner rotor 3 rotates relative to the outer rotor 1. The inner rotor 3 integrally rotates with a camshaft 2 that opens and closes valves of the engine E.

The outer rotor 1 includes a front plate 4 arranged at a frontward position of the outer rotor 1, which is a position in an opposite direction to where the camshaft 2 is arranged relative to the outer rotor 1. The outer rotor 1 also includes a sprocket 5 arranged at a rearward position of the outer rotor 1, which is a position in a direction of the camshaft 2. The outer rotor 1 further includes a rotor body 6 placed between the front plate 4 and the sprocket 5. The rotor body 6 serves as a base member. Each of the front plate 4 and the sprocket 5 serves as a supplementary member.

In a state where the crankshaft C is driven to rotate, rotational driving force from the crankshaft C is transmitted to the sprocket 5 via a power transmission member CH so that the outer rotor 1 is driven to rotate in the rotational direction S shown in FIG. 2. Rotation of the outer rotor 1 drives rotation of the inner rotor 3 in the rotational direction S so that the camshaft 2 rotates. Rotation of the camshaft 2 makes cams provided on the camshaft 2 to press down valves of the engine E. An example of the valves is an intake valve.

As FIG. 2 illustrates, a multiple number of first partition members 8 are provided on an inner peripheral portion of the rotor body 6. Each of the first partition members 8, which serves as a partition member, protrudes radially inward from the inner peripheral portion of the rotor body 6. The first partition members 8 are arranged such that each of the first partition members 8 is spaced apart from each other in a direction that conforms to the rotational direction S. A multiple number of second partition members 9 are provided on an outer peripheral portion of the inner rotor 3. Each of the second partition members 9, which serves as a partition member, protrudes radially outward from the outer peripheral portion of the inner rotor 3. Similarly to the first partition members 8, the second partition members 9 are arranged such that each of the second partition members 9 is spaced apart from each other in a direction that conforms to the rotational direction S. The first partition members 8 divide a space between the rotor body 6 and the inner rotor 3 into a multiple number of fluid pressure chambers 10. Each of the second partition members 9 divides each of the fluid pressure chambers 10 into an advance chamber 11 and a retard chamber 12.

As FIGS. 1 and 2 illustrate, flow paths 13 for advance angle and flow paths 14 for retard angle are formed within the inner rotor 3 and the camshaft 2. The flow paths 13 for advance angle connect each of the advance chambers 11 and a fluid supply and discharge mechanism 20 that controls supplying and discharging of operation oil and interrupting of supply and discharge of the operation oil. The flow paths 14 for retard angle connect each of the retard chambers 12 and the fluid supply and discharge mechanism 20.

The fluid supply and discharge mechanism 20 includes an oil pan, an oil pump P, fluid control valves V and an electronic control unit ECU. The fluid control valve V regulates supplying and discharging of the operation oil and interrupting of supply and discharge of the operation oil to the advance chamber 11 and the retard chamber 12. The electronic control unit ECU controls operations of the fluid control valves V. By controlling the electronic control unit ECU, relative rotational phase of the inner rotor 3 and the outer rotor 1 is shifted to an advance direction, which is a rotational direction indicated with S1 in FIG. 2, shifted to a retard direction, which is a rotational direction indicated with S2 in FIG. 2, or maintained at a selected phase.

As FIG. 1 illustrates, a torsion spring 19 is provided between the inner rotor 3 and the outer rotor 1 as a biasing mechanism that biases the relative rotational phase of the outer rotor 1 and the inner rotor 3 toward the direction of advance angle. The torsion spring 19 biases the inner rotor 3 relative to the outer rotor 1 in the rotational direction indicated as S1, which is toward the advance direction. Accordingly, the torsion spring 19 restricts relative phase of the inner rotor 3 that integrally rotates with the camshaft 2 from lagging relative to rotation of the outer rotor 1 due to a resistance force the camshaft 2 receives from valve springs.

As FIGS. 1 and 2 illustrate, a lock mechanism of the variable valve timing apparatus 100 according to the first embodiment includes a first projecting and retracting member 21 installed on one of the first partition member 8 of the rotor body 6 and a second projecting and retracting member 22 installed on the inner rotor 3 arranged such that the second projecting and retracting member 22 projects and retracts from a surface facing the sprocket 5 in a direction parallel to a rotational axis X. The lock mechanism also includes a first recess 23 for engagement formed on an outer peripheral surface of the inner rotor 3 in a state where a recessed portion, or a groove, forms an arc having a center at the rotational axis X. The first recess 23 for engagement is where the first projecting and retracting member 21 engages. The second recess 24 for engagement where the second projecting and retracting member 22 engages is formed on the sprocket 5 on a surface facing the inner rotor 3.

The first projecting and retracting member 21 is a component that projects and retracts to restrict the relative rotational phase of the outer rotor 1 and the inner rotor 3 to shift in the retard direction. The second projecting and retracting member 22 is a component that projects and retracts to restrict the relative rotational phase to shift in the advance direction. A base portion of the first projecting and retracting member 21 is arranged at a first housing portion 30 formed on the first partition member 8 of the rotor body 6. The first housing portion 30 is provided with a first spring 25 that biases the first projecting and retracting member 21 to project in a direction toward the inner rotor 3. A base portion of the second projecting and retracting member 22 is arranged at a second housing portion 31 formed on the inner rotor 3. The second housing portion 31 is provided with a second spring 26 that biases the second projecting and retracting member 22 to project in a direction toward the sprocket 5. The first projecting and retracting member 21 is a plate form locking piece or a component having a similar form. The second projecting and retracting member 22 is a stick form lock pin or a component having a similar form. A stick form lock pin may be appropriately used as the first projecting and retracting member 21 instead of the plate form locking piece.

Within the inner rotor 3 and the camshaft 2, first flow paths for disengagement, which are flow paths 14 for retard angle, and a second flow path 17 for disengagement are provided. The first flow paths for disengagement connect to the fluid supply and discharge mechanism 20 in a state where the first flow paths for disengagement and a bottom surface of the first recess 23 for engagement communicate. The second flow path 17 for disengagement connects to the fluid supply and discharge mechanism 20 in a state where the second flow path 17 for disengagement and a portion near the second projecting and retracting member 22 communicate. In a state where the first flow paths for disengagement, which is the flow paths 14 for retard angle, is provided with the operation oil, the first projecting and retracting member 21 retracts from the first recess 23 for engagement against biasing force of the first spring 25. In other words, the first projecting and retracting member 21 switches to an unlocked posture. In a state where the second flow path 17 for disengagement is provided with the operation oil, the second projecting and retracting member 22 retracts from the second recess 24 for engagement against biasing force of the second spring 26. In other words, the second projecting and retracting member 22 switches to an unlocked posture.

By engaging the first projecting and retracting member 21 to the first recess 23 for engagement, a rotation range of the inner rotor 3 relative to the outer rotor 1 from an intermediate lock phase in a direction of the retard angle, which is the rotational direction S2 in FIG. 2, is restricted. By engaging the second projecting and retracting member 22 to the second recess 24 for engagement, a rotation range of the inner rotor 3 relative to the outer rotor 1 from the intermediate lock phase in the advance direction, which is the rotational direction indicated as S1 in FIG. 2, is restricted.

The method of assembling the variable valve timing apparatus 100 according to the first embodiment is described next. The method includes a first step of temporarily fixing the inner rotor 3 relative to the rotor body 6 in a first rotation restricting state by a process of setting the sprocket 5, the rotor body 6, the inner rotor 3, and the front plate 4 on a jig and engaging the first projecting and retracting member 21 with the rotor body 6 and the inner rotor 3 followed by a process of rotating either the rotor body 6 or the inner rotor 3 relative to the other one of the rotor body 6 or the inner rotor 3 either in one direction of advance direction S1 or retard direction S2 to establish a state where the inner rotor 3 rotates in one direction either in the advance direction S1 or in the retard direction S2 relative to the rotor body 6, which serves as the base member, of the outer rotor 1. Here, the first rotation restricting state is the state where the first projecting and retracting member 21 and an end surface 23a of the first recess 23 for engagement in the direction of advance angle are in contact with each other.

The method includes a second step of providing the sprocket 5 to the inner rotor 3 to establish a second rotation restricting state, as FIG. 4 illustrates, by a process illustrated in FIG. 3 of installing the sprocket 5 to the rotor body 6 in a state where the second projecting and retracting member 22 engages with the sprocket 5 and the inner rotor 3 followed by a process of rotating the sprocket 5 relative to the inner rotor 3 either in one direction of advance direction S1 or retard direction S2 to establish a state where the sprocket 5, which serves as a supplementary member of the outer rotor 1, rotates in the aforementioned one direction described in the first step relative to the inner rotor 3. Here, the second rotation restricting state is the state where the second projecting and retracting member 22 and an end surface 24a of the second recess 24 for engagement in the direction of advance angle are in contact with each other. As an example, the second rotation restricting state may be established by rotating the sprocket 5 relative to the inner rotor 3 so that the second projecting and retracting member 22 comes into contact with the end surface 24a of the second recess 24 for engagement in the direction of advance angle.

The method includes a third step of fastening the rotor body 6, which serves as the base member of the outer rotor 1, and the front plate 4 and the sprocket 5, each of which serves as a supplementary member, by using bolts or similar fastening members 40 following a process of defining a predetermined amount of clearance L between the second projecting and retracting member 22 and the end surface 24a of the second recess 24 for engagement in the direction of advance angle, as FIG. 5 illustrates. The sprocket 5 may be easily rotated relative to the rotor body 6 and the inner rotor 3 by providing a worm gear, or a similar device, to gear with a tooth portion at the outer periphery of the sprocket 5.

The first projecting and retracting member 21 and the second projecting and retracting member 22 are assembled so that rotation of the inner rotor 3 is restricted by different members of the outer rotor 1, which are the rotor body 6 and the sprocket 5. Accordingly, a state of engagement between each of a multiple number of projecting and retracting members 21, 22 and either the outer rotor 1 or the inner rotor 3 are independently adjusted so that the outer rotor 1 and the inner rotor 3 are fastened in a state where the state of engagement is appropriately established for each of the projecting and retracting members 21, 22. As a result, noise generated at a start of the engine, which is caused by the projecting and retracting members 21, 22 colliding with the recesses 23, 24, is effectively reduced.

In the method of assembling the variable valve timing apparatus 100 according to the first embodiment, the sprocket 5 is provided to the inner rotor 3 to establish the second rotation restricting state by a process of rotating the sprocket 5 in the direction of retard angle relative to the inner rotor 3 to make the end surface 24a of the second recess 24 for engagement in the direction of advance angle and the second projecting and retracting member 22 contact with each other, followed by a process of rotating the sprocket 5 in a direction opposite to the aforementioned one direction to a predetermined amount so that clearance L is defined between the second projecting and retracting member 22 and the end surface 24a of the second recess 24 for engagement in the direction of advance angle.

Through a process of rotating the sprocket 5 relative to the inner rotor 3 in one direction to establish the second rotation restricting state followed by a process of rotating, for example, the sprocket 5 in the direction opposite to the aforementioned one direction to the predetermined amount, the appropriate amount of clearance L between the second projecting and retracting member 22 and the end surface 24a of the second recess 24 for engagement in the direction of advance angle is defined. In a state described herewith, assembling the outer rotor 1 provides appropriately defined clearances such that the first projecting and retracting member 21 and the second projecting and retracting member 22 smoothly operate. While providing smooth operations of the first projecting and retracting member 21 and the second projecting and retracting member 22, the arrangement described herewith provides the variable valve timing apparatus 100 with a state where minimum amount of allowance is available for the variable valve timing apparatus 100 that is locked in an intermediate lock position.

Furthermore, the variable valve timing apparatus 100 according to the first embodiment is provided with the first projecting and retracting member 21 formed in a key form arranged to project and retract in a radial direction of the outer rotor 1 and with the second projecting and retracting member 22 formed in a pin form arranged to project and retract in an axial direction of the outer rotor 1. With the first projecting and retracting member 21 formed in the key form arranged to project and retract in the radial direction of the outer rotor 1, the first projecting and retracting member 21 selectively engaging with the outer rotor 1 and the inner rotor 3, each of stop positions of the inner rotor 3, which are a stop position in the direction of retard angle, a stop position in the direction of advance angle and the intermediate lock position, may be defined on the rotor body 6, which is an element of the outer rotor 1 that serves as the base member. In other words, upon the arrangement described herewith, fixing the first projecting and retracting member 21 at the intermediate lock position may automatically define the stop positions in the directions of retard angle and advance angle. In addition, because the front plate 4 is a separate member independent of the first projecting and retracting member 21 and the second projecting and retracting member 22, and a process to consider the stop positions in the directions of retard angle and advance angle may be omitted at a time the first projecting and retracting member 21 is maintained in a contact state with the rotor body 6 to provide the intermediate lock position, the front plate 4 may be assembled to the rotor body 6, which is a base portion of the outer rotor 1, without considerations for positioning relative to the rotor body 6. As a result, upon the arrangement described herewith, an assembly process of the outer rotor 1 may be simplified so that the variable valve timing apparatus 100 may be economically assembled.

A method of assembling a variable valve timing apparatus 100 according to a second embodiment is described next. As FIGS. 6 to 9 illustrate, a lock mechanism of the variable valve timing apparatus 100 according to the second embodiment includes a first projecting and retracting member 21 and a second projecting and retracting member 22 provided on the inner rotor 3 arranged such that each of the first projecting and retracting member 21 and the second projecting and retracting member 22 projects and retracts in a direction parallel to a rotational axis X. On the front plate 4 on a surface facing an inner rotor 3, a first recess 23 for engagement, which is where the first projecting and retracting member 21 engages, is provided. On a sprocket 5 on a surface facing the inner rotor 3, a second recess 24 for engagement, which is where the second projecting and retracting member 22 engages, is provided.

The first recess 23 for engagement receives an end portion of the first projecting and retracting member 21 that projects in the direction of the front plate 4. The second recess 24 for engagement receives an end portion of the second projecting and retracting member 22 that projects in the direction of the sprocket 5.

As FIG. 7 illustrates, a base portion of the first projecting and retracting member 21 is arranged at a first housing portion 30 formed on the inner rotor 3. The first housing portion 30 is provided with a first spring 25 that biases the first projecting and retracting member 21 to project in a direction toward the front plate 4. A base portion of the second projecting and retracting member 22 is arranged at a second housing portion 31 formed on the inner rotor 3. The second housing portion 31 is provided with a second spring 26 that biases the second projecting and retracting member 22 to project in a direction toward the sprocket 5.

Within the inner rotor 3 and the camshaft 2, a third flow path 16 for disengagement and a second flow path 17 for disengagement are provided. The third flow path 16 for disengagement connects to the fluid supply and discharge mechanism 20 in a state where the third flow path 16 for disengagement and a portion near the first recess 23 for engagement communicate. The second flow path 17 for disengagement connects to the fluid supply and discharge mechanism 20 in a state where the second flow path 17 for disengagement and a portion near the second projecting and retracting member 22 communicate. In a state where the third flow path 16 for disengagement is provided with operation oil, the first projecting and retracting member 21 retracts from the first recess 23 for engagement against biasing force of the first spring 25. In other words, the first projecting and retracting member 21 switches to an unlocked posture. In a state where the second flow path 17 for disengagement is provided with the operation oil, the second projecting and retracting member 22 retracts from the second recess 24 for engagement against biasing force of the second spring 26. In other words, the second projecting and retracting member 22 switches to an unlocked posture.

The method of assembling the variable valve timing apparatus 100 according to the second embodiment is described next. The method includes, as FIG. 7 illustrates, a first step of temporarily fixing the inner rotor 3 in a first rotation restricting state relative to the front plate 4 by a process of setting the sprocket 5, the rotor body 6, the inner rotor 3, and the front plate 4 on a jig and engaging the first projecting and retracting member 21 with the front plate 4 and the inner rotor 3 followed by a process of rotating either one of the front plate 4 or the inner rotor 3 relative to the other one of the front plate 4 or the inner rotor 3 either in one direction of advance direction S1 or retard direction S2 to establish a state where the inner rotor 3 rotates in one direction either in the advance direction S1 or in the retard direction S2 relative to the rotor body 6, which serves as the base member of the outer rotor 1. Here, the first rotation restricting state is the state where the first projecting and retracting member 21 and an end surface 23a of the first recess 23 for engagement in the direction of retard angle, the first recess 23 formed on the front plate 4, are in contact with each other. Note that each of the rotor body 6 and the front plate 4 serves as a first driving-side rotation member and the sprocket 5 serves as a second driving-side rotation member.

The method includes, as FIG. 8 illustrates, a second step of providing the inner rotor 3 to the sprocket 5 to establish a second rotation restricting state by a process of installing the sprocket 5 to the rotor body 6 in a state where the second projecting and retracting member 22 engages with the sprocket 5 and the inner rotor 3, followed by a process of rotating the sprocket 5 relative to the inner rotor 3 either in one direction of advance direction S1 or retard direction S2 to provide a state where the sprocket 5, which serves as a supplementary member of the outer rotor 1, rotates in the aforementioned one direction described in the first step relative to the inner rotor 3. Here, the second rotation restricting state is the state where the second projecting and retracting member 22 and an end surface 24a of the second recess 24 for engagement in the direction of advance angle are in contact with each other. As an example, the second rotation restricting state may be established by rotating the sprocket 5 relative to the inner rotor 3 so that the second projecting and retracting member 22 comes into contact with the end surface 24a of the second recess 24 for engagement in the direction of advance angle.

The method includes, as FIG. 9 illustrates, a third step of fastening the rotor body 6, which serves as the base member of the outer rotor 1, and the front plate 4 and the sprocket 5, each of which serves as a supplementary member, by using bolts or similar fastening members 40 following a process of defining a predetermined amount of clearance L between the second projecting and retracting member 22 and the end surface 24a of the second recess 24 for engagement in the direction of advance angle followed by another process of defining clearance between the first projecting and retracting member 21 and an end surface 23a of the first recess 23 for engagement in the direction of retard angle as necessary.

In the method of assembling the variable valve timing apparatus 100 according to the second embodiment, the second rotation restricting state is established by providing the inner rotor 3 to the sprocket 5 by a process of rotating the sprocket 5 in the direction of retard angle relative to the inner rotor 3 to make the end surface 24a of the second recess 24 for engagement in the direction of advance angle and the second projecting and retracting member 22 contact with each other followed by a process of rotating the sprocket 5 in the opposite direction relative to the inner rotor 3 to a predetermined amount so that clearance L is defined between the second projecting and retracting member 22 and the end surface 24a of the second recess 24 for engagement in the direction of advance angle. Furthermore, the first rotation restricting state is established by providing the inner rotor 3 to the front plate 4 by a process of rotating the front plate 4 in the direction of advance angle relative to the inner rotor 3 to make the end surface 23a of the first recess 23 for engagement in the direction of retard angle and the first projecting and retracting member 21 contact with each other followed by a process of rotating the front plate 4 in the opposite direction relative to the inner rotor 3 to a predetermined amount so that clearance is defined between the first projecting and retracting member 21 and the end surface 23a of the first recess 23 for engagement in the direction of retard angle.

Through a process of rotating each of the sprocket 5 and the front plate 4 in one direction relative to the inner rotor 3 and fixing each of the sprocket 5 and the front plate 4 in a locked state where rotation is restricted relative to the inner rotor 3, followed by a process of rotating, for example, the sprocket 5 and the front plate 4 in the opposite direction relative to the inner rotor 3 by the predetermined amount, the appropriate amount of clearance between each of the projecting and retracting members 21, 22 and the recesses 23, 24 for engagement corresponding to each of the projecting and retracting members 21, 22 is defined. In a state described herewith, assembling the outer rotor 1 provides appropriately defined clearances such that the first projecting and retracting member 21 and the second projecting and retracting member 22 smoothly operate. While providing smooth operations of the first projecting and retracting member 21 and the second projecting and retracting member 22 the arrangement described herewith provides the variable valve timing apparatus 100 with a state where minimum amount of allowance is available for the variable valve timing apparatus 100 that is locked in the intermediate lock position.

Methods of assembling a variable valve timing apparatus 100 according to other embodiments are described next. The method of assembling the variable valve timing apparatus 100 according to this disclosure may include a variable valve timing apparatus 100 provided with first partition members 8 that form fluid pressure chambers 10 on an inner rotor 3, which serves as a driven-side rotation body, instead of on an inner peripheral portion of an outer rotor 1, which serves as a driving-side rotation body. Accordingly, second partition members 9 that divide the fluid pressure chambers 10 into advance chambers 11 and retard chambers 12 may be provided on the outer rotor 1, which serves as the driving-side rotation body.

The method of assembling the variable valve timing apparatus 100 according to this disclosure may include a variable valve timing apparatus 100 provided with housing portions 30, 31, each of which is where either a first projecting and retracting member 21 or a second projecting and retracting member 22 is arranged with, on either the outer rotor 1, which serves as the driving-side rotation body, or the inner rotor 3, which serves as the driven-side rotation body.

The method of assembling variable valve timing apparatus 100 according to the first embodiment may include a variable valve timing apparatus 100 provided with a second projecting and retracting member 22 arranged to engage with either a front plate 4 or the inner rotor 3. The variable valve timing apparatus 100 according to this disclosure may be provided with a rear plate instead of a sprocket 5 and a second projecting and retracting member 22 or a second recess 24 for engagement may be provided on the rear plate. In a state where the rear plate is provided as such, the sprocket 5 is provided on the outer peripheral portion of the rotor body 6.

The method of assembling the variable valve timing apparatus 100 according to the second embodiment is an example of a method of assembling a variable valve timing apparatus 100 including a process of temporarily fixing the first projecting and retracting member 21 and the first recess 23 for engagement provided in a direction of the front plate 4, followed by a process of restricting rotation of the second projecting and retracting member 22 and the second recess 24 for engagement provided in a direction of the sprocket 5. Nevertheless, the aforementioned processes may be switched so that a process of temporarily fixing the second projecting and retracting member 22 and the second recess 24 for engagement provided in the direction of the sprocket 5 is followed by a process of restricting rotation of the first projecting and retracting member 21 and the first recess 23 for engagement provided in the direction of the front plate 4.

The method of assembling the variable valve timing apparatus 100 according to this disclosure includes the variable valve timing apparatus 100 separately provided with a projecting and retracting member for restricting the relative phase of a driving-side rotation body and a driven-side rotation body at most retarded angle and a projecting and retracting member for restricting the relative phase of the driving-side rotation body and the driven-side rotation body at most advanced angle. Nevertheless, the method of assembling the variable valve timing apparatus 100 according to this disclosure may include the variable valve timing apparatus 100 provided with a lock mechanism having a multiple number of projecting and retracting members for locking the relative phase of the driving-side rotation body and the driven-side rotation body at either most retarded angle or most advanced angle.

The method of assembling the variable valve timing apparatus 100 according to this disclosure may be applied to a variable valve timing apparatus for an internal combustion engine of an automobile and other devices.

According to an aspect of this disclosure, a method of assembling the variable valve timing apparatus 100 includes the variable valve timing apparatus 100, which includes the outer rotor 1 including the rotor body 6 provided with at least one of the front plate 4 and the sprocket 5, the outer rotor 1 synchronously rotating with the crankshaft C of the internal combustion engine E, the inner rotor 3 coaxially arranged with the outer rotor 1 and integrally rotating with the camshaft 2 for opening and closing valves of the internal combustion engine E, the fluid pressure chamber 10 formed between the outer rotor 1 and the inner rotor 3, the fluid pressure chamber 10 divided into the advance chamber 11 and the retard chamber 12 by the partition member 8, 9 provided on at least one of the outer rotor 1 and the inner rotor 3, and the first projecting and retracting member 21 and the second projecting and retracting member 22 selectively engaging with the outer rotor 1 and the inner rotor 3 to lock relative rotational phase of the outer rotor 1 and the inner rotor 3 at a predetermined phase or to restrict relative rotational phase of the outer rotor 1 and the inner rotor 3 within a predetermined range. The method of assembling the variable valve timing apparatus 100 includes steps including the steps of temporarily fixing the inner rotor 3 relative to the rotor body 6 in the first rotation restricting state by a process of engaging the first projecting and retracting member 21 with the rotor body 6 and the inner rotor 3 followed by a process of rotating either the rotor body 6 or the inner rotor 3 to establish a state where the inner rotor 3 rotates in one direction either in the advance direction S1 or in the retard direction S2 relative to the rotor body 6, providing the front plate 4 or the sprocket 5 to the inner rotor 3 to establish the second rotation restricting state by a process of installing the front plate 4 or the sprocket 5 to the rotor body 6 in a state where the second projecting and retracting member 22 engages with the front plate 4 or the sprocket 5 and the inner rotor 3 followed by a process of rotating one of the inner rotor 3 and either the front plate 4 or the sprocket 5 to establish a state where the front plate 4 or the sprocket 5 rotates in the aforementioned one direction relative to the inner rotor 3, and fastening the front plate 4, the sprocket 5, and the rotor body 6 by a use of the fastening member 40.

Accordingly, each of the first projecting and retracting member 21 and the second projecting and retracting member 22 is installed such that rotation of the inner rotor 3 is independently restricted by a different member of the outer rotor 1, which is the rotor body 6, the front plate 4, or the sprocket 5. Upon the arrangement described herewith, while an amount of clearance is adjusted between one of the projecting and retracting members 21, 22 and either the outer rotor 1 or the inner rotor 3, which is where the aforementioned one of the projecting and retracting members 21, 22 is received, an amount of clearance defined between the other one of the projecting and retracting members 21, 22 and either the outer rotor 1 or the inner rotor 3, which is where the other one of the aforementioned one of the projecting and retracting members 21, 22 is received, remains unchanged. In a state where adjustment of clearance between each of a multiple number of projecting and retracting members 21, 22 and either the outer rotor 1 or the inner rotor 3 is independent of each other, the outer rotor 1 and the inner rotor 3 may be fastened in a state where clearance is appropriately defined for each of the projecting and retracting members 21, 22. As a result, noise generated at the start of the engine, which is caused by the projecting and retracting members 21, 22 colliding with the recesses 23, 24 for engagement, is effectively reduced.

According to another aspect of this disclosure, the method of assembling the variable valve timing apparatus 100 includes the variable valve timing apparatus 100 including one of the first projecting and retracting member 21 and the second projecting and retracting member 22 formed in a key form arranged to project and retract in the radial direction of the outer rotor 1 and the other one of the first projecting and retracting member 21 and the second projecting and retracting member 22 formed in a pin form arranged to project and retract in the axial direction of the outer rotor 1.

In a situation where each of the first projecting and retracting member 21 and the second projecting and retracting member 22 is formed in a pin form moving in the axial direction of the rotational axis X, the first projecting and retracting member 21 engages with the front plate 4 of the outer rotor 1 and the second projecting and retracting member 22 engages with a rear side plate of the outer rotor 1, for example the sprocket 5 or the rear plate. In most cases, a stop position in the direction of retard angle and a stop position in the direction of advance angle are formed on a base portion of the outer rotor 1 having a tubular form. The base portion may be provided as a separate component, for example as the rotor body 6, in addition to the front plate 4 and the rear side plate. On assembling components of the outer rotor 1 and the inner rotor 3 into a variable valve timing apparatus 100, assembly process includes processes of defining the intermediate lock position, the stop position in the direction of the retard angle, and the stop position in the direction of the advance angle. In order to appropriately define each of the intermediate lock position, the stop position in the direction of the retard angle, and the stop position in the direction of the advance angle, each of the front plate 4 and the rear side plate where either one of the first projecting and retracting member 21 or the second projecting and retracting member 22 engages is assembled to an appropriate position in consideration of where the inner rotor 3 makes contact with the base portion of the outer rotor 1 in each of the directions of retard angle and the advance angle. In other words, the assembly process includes careful positioning of each relating component. On the other hand, in a situation where, for example, the first projecting and retracting member 21 is formed in the key form arranged to project and retract in the radial direction of the outer rotor 1, the first projecting and retracting member 21 selectively engaging with the outer rotor 1 and the inner rotor 3, each of the stop positions of the inner rotor 3, which are the stop position in the direction of the retard angle, the stop position in the direction of the advance angle and the intermediate lock position, may be defined on the base portion alone, the base portion that is an element of the outer rotor 1. In other words, upon the arrangement described herewith, fixing the first projecting and retracting member 21 at the intermediate lock position automatically defines the stop positions in the directions of retard angle and advance angle. In addition, in a situation where a separate component independent of the first projecting and retracting member 21 and the second projecting and retracting member 22 is provided, for example a rear side plate, because such component does not require a process to consider the stop positions in the directions of retard angle and advance angle at a time the first projecting and retracting member 21 is maintained in a contact state with the rotor body 6 to provide the intermediate lock position, such component may be assembled to the base portion of the outer rotor 1 without considerations for positioning relative to the base portion. Accordingly, the assembly process of the outer rotor 1 may be simplified so that the variable valve timing apparatus 100 may be economically assembled.

According to further aspect of this disclosure, the method of assembling the variable valve timing apparatus 100 includes the step of fastening the front plate 4, the sprocket 5, and the rotor body 6 by the use of the fastening member 40, the step following a process of defining a predetermined amount of clearance L between the second projecting and retracting member 22 and either the front plate 4 or the sprocket 5.

In a state where clearance between either one of the projecting and retracting members 21, 22 and either the front plate 4 or the sprocket 5 is large, noise caused by the projecting and retracting members 21, 22 colliding with the recesses 23, 24 for engagement, increases. In a state where clearance between either one of the projecting and retracting members 21, 22 and either the front plate 4 or the sprocket 5 is small, smoothness reduces on engaging each of the projecting and retracting members 21, 22 to either the outer rotor 1 or the inner rotor 3 and on disengaging each of the projecting and retracting members 21, 22 from either the outer rotor 1 or the inner rotor 3. Upon the arrangement described herewith, fastening the front plate 4, the sprocket 5, and the rotor body 6 by the use of the fastening member 40 after defining predetermined amount of clearance L between the second projecting and retracting member 22 and either the front plate 4 or the sprocket 5 provides an appropriate amount of clearance L between the second projecting and retracting members 22 and either the front plate 4 or the sprocket 5. Accordingly, while maintaining smooth operation of the projecting and retracting members 21, 22, noise caused by the projecting and retracting members 21, 22 colliding with the recesses 23, 24 for engagement, is effectively reduced.

According to another aspect of this disclosure, the method of assembling the variable valve timing apparatus 100 includes the variable valve timing apparatus 100, which includes the outer rotor 1 including the rotor body 6, the front plate 4, and the sprocket 5, the outer rotor 1 synchronously rotating with the crankshaft C of the internal combustion engine E, the inner rotor 3 coaxially arranged with the outer rotor 1 and integrally rotating with the camshaft 2 for opening and closing valves of the internal combustion engine E, the fluid pressure chamber 10 formed between the outer rotor 1 and the inner rotor 3, the fluid pressure chamber 10 divided into the advance chamber 11 and the retard chamber 12 by the partition member 8, 9 provided on at least one of the outer rotor 1 and the inner rotor 3, and the first projecting and retracting member 21 and a second projecting and retracting member 22 selectively engaging with the outer rotor 1 and the inner rotor 3 to lock relative rotational phase of the outer rotor 1 and the inner rotor 3 at a predetermined phase or to restrict relative rotational phase of the outer rotor 1 and the inner rotor 3 within a predetermined range. The method of assembling the variable valve timing apparatus 100 includes steps including the steps of temporarily fixing the inner rotor 3 in the first rotation restricting state where rotation of the inner rotor 3 is restricted to one direction relative to either the front plate 4 or the rotor body 6 following a process of engaging the first projecting and retracting member 21 with the inner rotor 3 and either the front plate 4 or the rotor body 6, providing the inner rotor 3 to either the front plate 4 or the sprocket 5 to establish the second rotation restricting state where rotation of the inner rotor 3 relative to either the front plate 4 or the sprocket 5 is restricted to the aforementioned one direction or to a direction opposite to the aforementioned one direction following a process of installing either the front plate 4 or the sprocket 5 to the rotor body 6 in a state where the second projecting and retracting member 22 engages with the inner rotor 3 and either the front plate 4 or the sprocket 5, and fastening the rotor body 6, the front plate 4, and the sprocket 5 by a use of the fastening member 40.

Accordingly, each of the first projecting and retracting member 21 and the second projecting and retracting member 22 is installed such that rotation of the inner rotor 3 is independently restricted by a different member of the outer rotor 1, which is the rotor body 6, the front plate 4 or the sprocket 5. Upon the arrangement described herewith, while an amount of clearance is adjusted between one of the projecting and retracting members 21, 22 and either the outer rotor 1 or the inner rotor 3, which is where the aforementioned one of the projecting and retracting members 21, 22 is received, an amount of clearance defined between the other one of the projecting and retracting members 21, 22 and either the outer rotor 1 or the inner rotor 3, which is where the other one of the aforementioned one of the projecting and retracting members 21, 22 is received, remains unchanged. In a state where adjustment of clearance between each of a multiple number of projecting and retracting members 21, 22 and either the outer rotor 1 or the inner rotor 3 is independent or each other, the outer rotor 1 and the inner rotor 3 may be fastened in a state where clearance is appropriately defined for each of the projecting and retracting members 21, 22. As a result, noise generated at the start of the engine, which is caused by the projecting and retracting members 21, 22 colliding with the recesses 23, 24 for engagement, is effectively reduced.

According to further aspect of this disclosure, the method of assembling the variable valve timing apparatus 100 includes the step of fastening the rotor body 6, the front plate 4, and the sprocket 5 by the use of the fastening member 40, the step following a process of defining a predetermined amount of clearance L between the second projecting and retracting member 22 and either the front plate 4 or the sprocket 5.

In a state where clearance between either one of the projecting and retracting members 21, 22 and either the front plate 4 or the sprocket 5 is large, noise caused by the projecting and retracting members 21, 22 colliding with the recesses 23, 24 for engagement, increases. In a state where clearance between either one of the projecting and retracting members 21, 22 and either the front plate 4 or the sprocket 5 is small, smoothness reduces on engaging each of the projecting and retracting members 21, 22 to either the outer rotor 1 or the inner rotor 3 and on disengaging each of the projecting and retracting members 21, 22 from either the outer rotor 1 or the inner rotor 3. Upon the arrangement described herewith, fastening the front plate 4, the sprocket 5, and the rotor body 6 by the use of the fastening member 40 after defining predetermined amount of clearance L between the second projecting and retracting member 22 and either the front plate 4 or the sprocket 5 provides an appropriate amount of clearance L between the second projecting and retracting member 22 and either the front plate 4 or the sprocket 5. Accordingly, while maintaining smooth operation of the projecting and retracting members 21, 22, noise caused by the projecting and retracting members 21, 22 colliding with the recesses 23, 24 for engagement, is effectively reduced.

The principles, preferred embodiment and mode of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.

METHOD OF ASSEMBLING VARIABLE VALVE TIMING APPARATUS

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Priority Claims (1)