This application is based on Japanese Patent Application No. 2006-139468 filed on May 18, 2006, the disclosures of which is incorporated herein by reference.
The present invention relates to a valve timing controller which adjusts valve timing of at least one of an intake valve and an exhaust valve.
JP-2005-048706A shows a valve timing controller which includes a guide rotation member provided with guide grooves, a plurality of movable bodies sliding in the guide grooves, and a bearing rotation member radially supporting the guide rotation member. A plurality of link mechanisms connects the moveable bodies with the guide rotation member. Since each element in a motion transfer system from the guide rotation member to the bearing rotation member constructs a constrained chain, operational conditions of each element are defined according to its valve timing.
Between the guide rotation member and the bearing rotation member, a radial clearance gap is formed to permit a relative rotation. A radial displacement may be arouse due to a manufacturing tolerance between the guide rotation member and the bearing rotation member. In a case that the clearance gap is excessively small, each rotation member collides with each other, so that the guide rotation member may stick on the bearing rotation member, and an operation lock and a reduction in strength may be arouse. Besides, a clearance gap is formed in width direction between an inner surface of the guide groove and the movable member. Even if one of the movable bodies is engaged with the guide groove, the other movable body may not be engaged with the guide groove. In this case, operation load is concentrated on the movable members or the link mechanisms, which may cause a reduction in strength.
The present invention has been made in view of the foregoing problem. It is an object of the present invention to provide a valve timing controller which avoids an operation lock and a reduction in strength.
According to the present invention, the valve timing controller includes a guide rotation member provided with a guide groove, a bearing rotation member radially supporting the guide rotation member, and a plurality of movable bodies sliding in the guide groove in accordance with a rotation of the guide rotation member. A plurality of link mechanisms connects the bearing rotation member with each one of movable bodies respectively, and rotates the bearing rotation member in accordance with a movement of the movable bodies. The valve timing of at least one of the intake valve and the exhaust valve is adjusted in accordance with a rotation of the bearing rotation body. A clearance gap is provided between the guide rotation member and the bearing rotation member in order to permit a relative radial movement of the guide rotation member with respect to the bearing rotation member.
Embodiments of the present invention will be described hereinafter. The same parts and components as those in each embodiment are indicated with the same reference numerals and the same descriptions will not be reiterated.
The electric control system 4 is provided with an electric motor 21 and an electric current control circuit 22. The electric motor 21 is a brushless motor which has a motor case 23 and a motor shaft 24. The motor case 23 is fixed to the engine through a stay (not shown), and the motor shaft 24 is supported by the motor case 23. The electric current control circuit 22 includes an operation driver and a microcomputer, and is electrically connected with the electric motor 21. The electric current control circuit 22 controls electric current applied to the motor 21 according to a driving condition of the engine. The electric motor 21 generates a magnetic filed around the motor shaft 24 to generate rotation torque in X direction or Y direction (refer to
The phase change mechanism 6 is provided with the driving rotation member 10, the driven rotation member 18, a reduction gear unit 30, and a link unit 50.
As shown in
As shown in
The connecting portions 19 are integrally connected to the fix portion 17 at 1800 rotationally symmetrical points with respect the center “O”. The cylindrical bearing portion 20 is arranged opposite to the camshaft 2 with respect to the fix portion 17.
As shown in
The external gear 31 has an addendum circle outside of a dedendum circle and is coaxially connected to the cover 12 by rivets, whereby the external gear 31 integrally rotates with the driving rotation member 10.
The planetary carrier 32 is cylindrical as a whole, and its inner surface 35 is coaxially arranged with the driving rotation member 10 and the motor shaft 24. A groove 36 is provided on the inner surface 35 to receive a joint 37 so that the planetary carrier 32 is connected to the motor shaft 24. Thereby, the planetary carrier 32 rotates around the center “O” in connection with the motor shaft 24, and is able to relatively rotate with respect to the driving rotation member 10. The planetary carrier 32 is provided with an eccentric portion 38 on its outer surface.
The internal gear 33 is a planetary gear having teeth portion 39 of which addendum circle is inside of a dedendum circle. The dedendum circle of the teeth portion 39 is larger than the addendum circle of the external gear 31. The number of teeth of the teeth portion 39 is larger than that of the external gear 31 by one tooth. The teeth portion 39 is arranged outside of the external gear 31 in such a manner as to be eccentric with respect to the external gear 31, and engages with the external gear 31 at side opposite to the eccentric direction. A center bore 41 of the internal gear 33 is coaxially arranged with the teeth portion 39. The eccentric portion 38 is engaged with the center bore 41 through a bearing 40. The internal gear 33 rotates around an eccentric center E of the eccentric portion 38 while performing a planetary motion in a rotation direction of the eccentric portion 38. A plate spring 43 having U-shape is received in a hole 42 formed in the eccentric portion 38. The plate spring 43 biases the internal gear 33 via the bearing 40 so that the internal gear 33 engages with the external gear 31 sufficiently.
As shown in
In the reduction gear unit 30, when the planetary carrier 32 does not rotate relative to the driving rotation member 10, the internal gear 33 does not perform the planetary motion and rotates with the driving rotation member 10. The engaging pins 49 biases the engaging holes 48 in a rotation direction. As the result, the guide rotation member 34 rotates in a clockwise direction in
When the planetary carrier 32 rotates in the direction “X” with respect to the driving rotation member 10, the internal gear 33 performs the planetary motion, engaging with the external gear 31. The biasing force of the engaging pins 49 increases so that the guide rotation member 34 relatively rotates in the direction “X” with respect to the driving rotation member 10.
When the planetary carrier 32 rotates in the direction “Y” with respect to the driving rotation member 10, the internal gear 33 performs the planetary motion, engaging with the external gear 31. The biasing force of the engaging pins 49 increases so that the guide rotation member 34 relatively rotates in the direction “Y” with respect to the driving rotation member 10.
According to the reduction gear unit 30 described above, by increasing the motor torque to be transmitted to the guide rotation member 34, the guide rotation member 34 is able to relatively rotate with respect to the driving rotation member 10.
As shown in
As shown in
As shown in
As shown in
While the guide rotation member 34 maintains the same rotational phase as the driving rotation member 10, the movable shaft 56 does not slide in the guide groove 58 to rotate with the guide rotation member 10. The relative position between the first link 52 and the second link 53 is unchanged, so that the driven rotation member 18 rotates in a clockwise direction in
When the guide rotation member 34 rotates in the “X” direction relative to the driving rotation member 10, each of movable shafts 56 slides in the guide groove 58 in such a manner as to come close to the center “O”. At this time, each of the movable shafts 56 rotates the first link 52 in the corresponding link mechanism 51 and moves so that a distance between the movable shaft 56 and the center “O” decreases. As the result, the second link 53 and the connecting portion 19 are rotated in the direction “X” by a biasing force of the movable shaft 56, so tat the driven rotation member 18 is advanced with respect to the driving rotation member 10. Hence, the valve timing is advanced.
When the guide rotation member 34 rotates in the “Y” direction relative to the driving rotation member 10, each of movable shafts 56 slides in the guide groove 58 in such a manner as to be apart from the center “O”. At this time, each of the movable shafts 56 rotates the first link 52 in the corresponding link mechanism 51 and moves so that a distance between the movable shaft 56 and the center “O” increase. As the result, the second link 53 and the connecting portion 19 are rotated in the direction “Y” by a retracting force of the movable shaft 56, so tat the driven rotation member 18 is retarded with respect to the driving rotation member 10. Hence, the valve timing is retarded.
In the link unit 50 described above, the rotation of the driven rotation member 18 relative to the driving rotation member 10 is generated in each link mechanism 51 according to the movement of the movable shaft 56 which follows the relative rotation of the guide rotation member 34.
As shown in
As shown in
As shown in
As shown in
As shown in
The connecting member 60 and the bearing member 61 are fasted to the camshaft 2 by a bolt 7. Thus, fasten force of the joint member 62 is enough to avoid deviation between the connecting member 60 and the bearing member 61 before the bolt 7 is screwed.
As schematically shown in
Next, a method of assembling the valve timing controller will be described hereinafter. First, a pair of link mechanisms 51 are provided.
Then, the guide rotation member 34 is arranged inside of the sprocket 11, and the movable shaft 56 is engaged with the guide groove 58 on the line R as shown in
After the bearing member 61 is press-fitted inside of the O-ring 82, the small-diameter portion 63 is inserted into the insert groove 66 and is press-inserted into the engagement hole 65. At this time, a press-insert amount of the small-diameter portion 63 is less than that of perfect engagement condition shown in
Then, the bearing member 61 is moved along the line R while the joint member 62 slides along the side surfaces 67, 68 of the insert groove 66, whereby the center of bearing portion 20 and the center of the guide rotation member 34 are precisely consistent with each other. The O-ring 82 generates alignment effect by its resilient deform.
After the alignment is completed, the small-diameter portion 63 is further press-inserted into the engagement hole 65 and the large-diameter portion 64 is press-inserted fitted into the insert groove 66. Thereby, the connecting member 60 and the bearing member 61 are coupled to each other by a joint member 62, so that the driven rotation member 18 is structured.
Then, the timing chain (not shown) is wound around the sprocket 11, and the connecting member 60 and the bearing member 61 are fasted by the bolt 70 to be connected to the camshaft 2. Since the joint member 62 is press-inserted into the insert groove 66 along the line R, it is restricted that the bearing member 61 relatively rotates with respect to the connecting member 60 and deviates from the center of the guide rotation member 34.
Finally, the reduction gear unit 30 is provided inside of the driving rotation member 10, and the cover 12 is secured to the sprocket 11 by the screws. The motor shaft 24 is connected to the planetary carrier 32, and the electric motor 21 is electrically connected to the circuit 22.
A method of defining the clearance gap 80 will be described hereinafter. In this method, a displacement of the guide rotation member 34 due to a manufacturing tolerance of the driving rotation member 10, the driven rotation member 18, the link mechanism 51, the movable shaft 56 and the guide groove 58 is considered.
The position of the movable shaft 56 at the most retarded ends A1, A2, the most advanced ends B1, B2, and the center points C1, C2 varies as shown in
The variation ranges of the shaft body position which should be assured are represented by rhombus areas Da, Db, and Dc in
σa<σc<σb (1)
The alignment of the bearing member 61 and the guide rotation member 34 is conducted under the condition where the movable shaft 56 is engaged with the guide groove 58 on the radial line R passing through the center C1, C2. The assured amount σi of the guide rotation member displacement due to the variation in the shaft body position is expressed by the following equation (2).
±σi=±(σb−σc) (2)
where σc denotes an absolute value of the assured variation amount at the center points C1, C2, and σb denoted an absolute value of the assured variation amount at the most advanced ends B1, B2.
In a case that the guide groove 58 deviates leftward or rightward from the design position shown in
When the guide groove 58 deviates rightward in the maximum amount, the center of groove is varied as shown in
On the other hand, when the guide groove 58 deviates leftward in the maximum amount, the center of groove is varied as shown in
As described above, the alignment of the bearing member 61 and the guide rotation member 34 is conducted under the condition where the movable shaft 56 is engaged with the guide groove 58 on the radial line R passing through the center C1, C2. The assured amount σii of the guide rotation member displacement due to the variation in the groove center position is expressed by the following equation (3).
±σii=±Δ/2 (3)
In the first embodiment, the width δ of the clearance gap 80 in the radial direction is defined by the following equation (4).
δ=2(σi+σii)=2(σb−σc)+Δ (4)
The clearance gap 80 having the width δ allows any displacement of the guide rotation member 34 in the radial direction. Hence, even if the guide rotation member 34 is displaced due to the manufacturing tolerance, this displacement is absorbed by the clearance gap 80, whereby the guide rotation member 34 does not stick on the bearing member 61 and a concentration of the load on one of the movable shafts 56 and the link mechanisms 51 is avoided. An operation lock and a reduction in strength can be avoided in the valve timing controller 1 according to the embodiment.
Besides, the assurance amounts ±σi, ±σii of the displacement can be made small value by the alignment of the bearing member 61 and the guide rotation member 34. Thus, the width δ of the clearance gap 80 is made very small, so that the bearing member 61 effectively supports the guide rotation member 34.
As shown in
After the bearing member 61 is press-inserted inside of the O-ring 82, the small-diameter portion 63 is inserted into the engagement hole 100 and the insert groove 110, and then the large-diameter portion 64 is press-inserted into the engagement hole 100 as shown in
Then, the bearing member 61 is moved along the line R while the joint member 62 slides along the side surfaces 111, 112 of the insert groove 110, whereby the center of bearing portion 20 and the center of the guide rotation member 34 are precisely consistent with each other. After the alignment is completed, the small-diameter portion 63 is further press-inserted into the engagement hole 65 and the large-diameter portion 64 is press-inserted fitted into the insert groove 110. Thereby, the connecting member 60 and the bearing member 61 are coupled to each other by the joint member 62, so that the driven rotation member 18 is structured.
The clearance gap 80 is defined in the same manner as the first embodiment to achieve the same advantage.
With respect to the displacement amount of the guide rotation member 34 due to the manufacturing tolerance of the elements 10, 11, 51, 56, the assured variation amount ±σb, which is largest in the assured variation amounts ±σa, ±σb, and ±σc shown in
±σii=±Δ (5)
δ=2(σi+σii)=2σb+2Δ (6)
The clearance gap 80 having the width δ allows any displacement of the guide rotation member 34 in the radial direction.
(Modifications)
The guide groove 58 can be inclined in such a manner that the distance from the center “O” increases along the direction Y. Alternatively, the guide groove 58 can be made straight groove. A common single guide groove 58 can be provided to a plurality of movable shaft 56. The movable shaft 56 can be slidably engaged with the intermediate portion 15 without providing the first link 52 and the shaft body 55.
Furthermore, as shown in
The valve timing controller can adjust a valve timing of an exhaust valve or both of an intake valve and an exhaust valve.
Number | Date | Country | Kind |
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2006-139468 | May 2006 | JP | national |
Number | Name | Date | Kind |
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6883482 | Takenaka et al. | Apr 2005 | B2 |
7395791 | Isobe | Jul 2008 | B2 |
Number | Date | Country |
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2005-48706 | Feb 2005 | JP |
Number | Date | Country | |
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20070266977 A1 | Nov 2007 | US |