JPH0518216A - Variable valve timing device - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] A variable valve timing device that changes the phase between the timing pulley and the cam shaft that moves the ring gear interposed between the timing pulley and the cam shaft in the axial direction. The meshing noise is reduced and a large resistance to the movement of the ring gear is prevented. [Structure] First and second transmissions of rotation from the timing pulley to the camshaft via a ring gear 15 provided with helical splines 11a and 11b between the camshaft 1 and the timing pulley 3 and the ring gears separated from each other in the axial direction.
To change the phase between the timing pulley and the cam shaft. Stoppers 30, 3 are provided in the first and second operating positions of the sleeve 5 and the housing 11, respectively.
2, 34, 36 are provided, and when the ring gear is in the first and second operating positions, the ring gear is elastically pressed in the circumferential direction via the blocks 31, 33, 35, 37, and the timing pulley and Prevents relative rotation with the camshaft.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve timing device for switching the opening / closing timing of intake and exhaust valves of an internal combustion engine during operation.

[0002]

2. Description of the Related Art Between a camshaft of an internal combustion engine and a timing pulley for driving the camshaft, a ring gear having at least one of the splines provided on the inner and outer circumferences a helical spline is interposed. A variable valve timing device is known in which a camshaft and a timing pulley are relatively rotated along a tooth trace of a helical spline by moving the camshaft in the axial direction of the camshaft.

Generally, in this type of variable valve timing device, when there is backlash in the spline meshing portion between the camshaft or the timing pulley and the ring gear, there is a problem that so-called meshing noise such as tapping noise occurs due to torque fluctuation of the camshaft. is there. That is, a torque reaction force that alternately changes in the rotation direction and the counter rotation direction is generated on the camshaft by the opening / closing operation of the intake / exhaust valve. The fluctuations cause fluctuations, which causes a tapping sound due to the collision of the tooth surfaces.

In order to prevent the generation of this meshing noise, it is effective to reduce the backlash at the spline meshing portion to zero. An example of a variable valve timing device that reduces meshing noise by eliminating backlash in the spline meshing portion is disclosed in, for example, Japanese Patent Laid-Open No. 61-279713.

In the device of the above publication, the ring gear is divided into two parts on a plane perpendicular to the axis, and the two parts thus divided are connected via an elastic body so that the tooth traces are displaced from each other. As a result, the tooth surface of the spline of the ring gear in which the tooth trace of the spline is deviated has a shape in which the engaging spline tooth surface is elastically sandwiched from both sides, so that backlash can always be kept at zero.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention JP-A-61-279713
The device of the publication is effective in reducing the meshing noise, but has a drawback that the structure of the ring gear becomes complicated. Also, in order to overcome the rapidly changing camshaft torque and maintain contact with the spline tooth surface, it is necessary to constantly press the tooth surface with a strong force. There is a problem that the sliding resistance on the spline tooth surface is large and the switching time is long.

In view of the above problems, the present invention can reduce meshing noise in a variable valve timing device that moves a ring gear in the axial direction to change the phase without increasing the sliding resistance of the spline portion during the switching operation. It is intended to provide a means.

[0008]

According to the present invention, a ring gear having at least one of the splines provided on the inner and outer circumferences as a helical spline is interposed between the camshaft and the timing pulley, and the camshaft is provided. And a timing pulley are meshed with splines respectively provided on the timing pulley and the cam pulley is driven to rotate from the timing pulley, and the ring gear is moved between a first operating position and a second operating position that are separated from each other in the cam shaft axial direction. In the variable valve timing device that relatively rotates the timing pulley and the cam shaft along the tooth trace of the helical spline to change the phase of the timing pulley and the cam shaft, the timing pulley and the cam shaft are respectively The phosphorus is in the first and second operating positions. It includes a stopper member which gears engage, each of said stopper member variable valve timing device is provided, characterized in that elastically presses along the ring gear when engaged in the circumferential direction.

[0009]

In the first and second operating positions, the ring gear engages with the timing pulley and the stopper member of the camshaft, respectively. At the engaging position, the stopper member presses and urges the ring gear in the circumferential direction, so that the timing pulley spline and the ring gear spline tooth surface, and the ring gear spline and the camshaft spline tooth surface are respectively the timing pulley and the camshaft. The stopper members are pressed against each other to keep the tooth surfaces in contact with each other.

Rotational torque is transmitted between the ring gear and the stopper member, or between the spline of the ring gear and the spline of the timing pulley or camshaft. Also, since the stopper member is elastically pressed,
Even if the torque fluctuates, the contact between the spline tooth surfaces is maintained, and the initial resistance during the switching operation is reduced.

Furthermore, since the stopper member engages with the ring gear only in the first and second operating positions, the sliding resistance against the movement of the ring gear during the switching operation does not increase.

[0012]

1 is a sectional view of an embodiment of a variable valve timing device according to the present invention. In the figure, 1 is a camshaft, 3
Is a timing pulley, and 5 is a sleeve formed at the center of the timing pulley 3. The camshaft 1 is inserted into the sleeve 5 of the timing pulley 3 so that the pulley 3 and the camshaft 1 can rotate relative to each other.

Reference numeral 11 in the drawing denotes a cylindrical housing. The housing 11 is fixed to the end surface of the cam shaft 1 by a mounting bolt 13 and rotates integrally with the cam shaft 1. Helical splines 5a and 11a are formed on the outer circumference of the sleeve 5 of the timing pulley 3 and the inner circumference of the housing 11, respectively, and have helical twist angles opposite to the axial direction.

A cylindrical ring gear 15 concentric with the housing 11 and the sleeve 5 is arranged between the housing 11 and the sleeve 5, and an outer peripheral surface of the ring gear 15 has a helical spline 11a formed on an inner peripheral surface of the housing 11. A helical spline 11b that meshes with the helical spline 5b that meshes with the helical spline 5a on the outer circumferential surface of the sleeve 5 is provided on the inner peripheral surface of the ring gear 15. Therefore, the timing pulley 3 rotates from the sleeve 5 to the ring gear 15 via the splines 5a and 5b, and from the ring gear 15 to the housing via the splines 11b and 11a.
11 and the timing pulley 3 and the camshaft 1 rotate integrally.

Oil seals 17a and 17b such as O-rings are provided between the outer peripheral surface of the ring gear 15 and the inner peripheral surface of the housing 11 and between the inner peripheral surface of the ring gear 15 and the outer peripheral surface of the sleeve 5, and An annular hydraulic chamber 19 is formed between the end surface on the shaft end side and the housing 11. The hydraulic chamber 19 is connected to a hydraulic circuit (not shown) via a hydraulic passage 21 formed in the camshaft 1.

Reference numeral 27 in the drawing denotes a compression spring for biasing the ring gear 15 toward the hydraulic chamber 19 side. As shown in FIG. 1, the compression spring 27 presses the ring gear 15 to the left in the drawing when the hydraulic oil pressure is not supplied to the hydraulic chamber, and holds the ring gear 15 at the left end position (first operating position) of the housing. There is.

In addition, a hydraulic passage 21 is provided from a hydraulic circuit (not shown).
When hydraulic oil is supplied to the hydraulic chamber 19 via the ring gear 15, the ring gear 15 moves to the right in the figure while compressing the spring 27 by the hydraulic oil pressure in the hydraulic chamber 19. When the ring gear 15 moves in the axial direction, the sleeve 5 and the housing 11 move to the ring gear 15 respectively.
On the other hand, since the helical splines 5a, 5b and 11a, 11b relatively rotate along the tooth traces, the rotational phases of the timing pulley 3 and the camshaft 1 relatively change. Since the timing pulley 3 is synchronously driven from the engine crankshaft by a toothed belt or the like, the valve timing of the intake valve and / or the exhaust valve driven by the camshaft 1 by changing the rotational phase of the timing pulley 3 and the camshaft 1. Can be changed while driving. When the hydraulic pressure is continuously supplied to the hydraulic chamber 19, the ring gear continues to move to the right in the drawing, is pressed to the right end position (second operating position) of the housing 11, and is held in this state. In this embodiment, the ring gear is held in either the first or second operating position under normal operating conditions and is not used in the intermediate position.

In this embodiment, four stoppers 30, 32, 34, 36 are provided to engage the ring gear in the first and second operating positions. As shown, the stoppers 30 and 32 are the first and second stoppers on the outer peripheral surface of the sleeve 5.
The stoppers 34 and 36 are arranged near the first and second operating positions on the inner peripheral surface of the housing 11. Further, blocks 31, 33, 35, 37 engaging with these stoppers are projected at both ends of the ring gear 15, respectively.

FIG. 2 shows the mutual positional relationship between the stopper 30, the block 31, the spline 5a of the ring gear and the spline 5b of the housing. The stopper 30 is held by a support portion 30a fixed on the outer circumference of the sleeve via an elastic member 30b (spring or synthetic rubber), and its movement in the axial direction of the camshaft is restricted by a locking member (not shown), but the circumference of the circumference is limited. In the direction, the elastic member 30b can be slightly displaced by elastic deformation.

Further, the stopper 30 is provided with a tapered engagement surface 30c inclined with respect to a plane passing through the cam shaft axis, and when the ring gear 15 is in the first operating position, the engagement surface 30c serves as a ring gear. Abut the block 31 of 15. In FIG. 2, the ring gear 15 is a spring when the hydraulic pressure in the hydraulic chamber 19 is released.
27 shows a state of being pressed to the first operating position by 27.
Further, the solid line in the figure shows the spline 5b of the sleeve 5, and the dotted line shows the spline 5a of the ring gear,
The arrow D in the figure indicates the rotation direction of the sleeve 5. Since the torque is transmitted from the spline 5b side of the sleeve 5 to the spline 5a of the ring gear 15, in the conventional ring gear without the stopper 30 and the block 31, the tooth surface B of the spline 5b of the sleeve 5 is the spline 5 of the ring gear 15.
The torque is transmitted by contacting the tooth surface C of a. However, if there is a torque fluctuation, the tooth surface C of the ring gear is the tooth surface B of the sleeve.
And A, and a meshing noise was generated due to the collision with the tooth surfaces B and A.

In the present invention, the stopper 30, the block 31, and the elastic member 30b prevent the ring gear 15 from swinging at the operating position shown in the figure, thereby preventing the generation of mesh noise.
Next, the operation of the stopper 30 of this embodiment will be described with reference to FIG. When the hydraulic pressure is not supplied to the hydraulic chamber 19, the ring gear 15 is urged toward the stopper 30 by the reaction force of the spring 27. Therefore, the block 30 of the ring gear 15 contacts the engaging surface 30c of the stopper 30. When the ring gear 15 is pushed by the spring 27 and moves to the left side in the figure, the block 31
Moves along the inclination of the engaging surface 30c, so that the ring gear 15
The tooth flank C is separated from the tooth flank B of the sleeve and pressed against the tooth flank A.

That is, the tooth flank C is pushed by the spring 27 between the stopper 30 and the tooth flank A to be bitten, and is sandwiched between the stopper 30 and the tooth flank A. As described above, since the driving torque is transmitted from the sleeve 5 side to the ring gear 15,
The driving torque is transmitted from the stopper 30 to the ring gear via the block 31. Therefore, when the driving torque increases, the elastic member supporting the stopper 30 is slightly compressed, and the contact pressure acting between the tooth surface A of the sleeve and the tooth surface C of the ring gear decreases, so that the ring gear 15 is pushed by the spring 27. Along the tooth flank A, the tooth flanks A and C are not separated from each other by further advancing to the stopper 30 side.

On the other hand, when the driving torque fluctuates to the negative side and the torque transmission direction is reversed, that is, the ring gear 15
(When the torque is transmitted from the shaft to the sleeve 5), the tooth surface C of the ring gear 15 is pressed against the tooth surface A by the negative transmission torque, and the force of the stopper 30 pressing the block 31 decreases. .. However, the stopper 30 has an elastic member 30b.
Since the block 31 is pressed by the reaction force due to the bending, the pressing force does not become zero even if the driving torque becomes negative, and the stopper 30 and the block 31 are not separated from each other. Therefore, in the first operating position, the tooth flank C of the ring gear 15 and the block 31 are respectively in the sleeve 5 even if the driving torque fluctuates.
Since the tooth surface A of the sleeve 5 rotates while keeping contact with the stopper 30, the ring gear 15 can be prevented from swinging in the backlash of the teeth of the sleeve 5, and the above-mentioned meshing noise does not occur.

When the stopper 30 is rigidly supported, the force with which the stopper 30 presses the block 31 becomes excessive and the ring gear 15 is pushed from the first operating position toward the second operating position. Although the initial pressing force may increase and smooth operation may not be obtained, the pressing force of the stopper 30 is prevented from becoming excessive by elastically supporting the stopper 30 via the elastic member 30b as in this embodiment. As a result, the increase in initial pressing force is suppressed.

Further, as described above, the stopper 30 is used to prevent the tooth flank from swinging. As a result, no meshing noise is generated even if the backlash of the spline tooth meshing portion is set to a large value. A large sliding resistance does not occur in the ring gear 15, and the switching time is shortened. Next, FIG. 3 shows the positional relationship between the stopper 32 of the sleeve 5, the block 33 of the ring gear 15 and the same tooth flanks A, B and C as in FIG. 2 when the ring gear 15 is in the second operating position.

In the second operating position, the ring gear 15 is pressed by the hydraulic pressure supplied to the hydraulic chamber 19 and is blocked.
33 is pressed by the stopper 32. Therefore, the tooth flank C is held between the stopper 32 and the tooth flank B, contrary to FIG. In this case, the driving torque is transmitted from the tooth flank B to the tooth flank C, which is elastic member of the stopper 32 via the block 33.
It is pressed against the tooth surface B by 32b, and the contact is maintained even when the driving torque is negatively changed as in the case of FIG.

Further, the point that the initial pressing force at the time of switching can be suppressed is the same as in the case of FIG. In the above, the prevention of the meshing noise between the sleeve 5 and the ring gear 15 was explained, but in this embodiment, as shown in FIG. 1, it is elastically supported in the first and second operating positions on the inner circumference of the housing 11 as well. Stopper 34,
36 is provided so as to engage with the blocks 35 and 37 of the ring gear 15, respectively, and the meshing noise between the ring gear 15 and the housing 11 is also prevented.
The actions of the stoppers 34 and 36 are similar to those of the stoppers 30 and 32, and therefore their explanation is omitted here.

The positions of the stoppers 30 to 36 in the circumferential direction must be accurately set in relation to the spline tooth surface, and the positional relationship between the sleeve 5 at each operating position and the stopper of the housing 11 is also accurate. Is required. However, in this embodiment, the engaging surface of the stopper with the block (FIGS. 2 and 30c) is inclined, and the elastic member (FIGS.
Since the stopper is supported in b), the degree of freedom of the stopper installation position is increased, and the required function can be exhibited without increasing the processing accuracy and assembly accuracy of the stopper.

Similarly, the elastic member can absorb the difference in the shake amount due to the difference in radius between the housing 11 and the sleeve 5.

[0030]

As described above, according to the present invention, the stoppers for elastically pressing the ring gear along the rotational direction are provided on the timing pulley and the cam shaft at the respective operating positions of the ring gear as described above. It is possible to reduce the meshing noise during operation without increasing the spline sliding resistance.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a structure of an embodiment of a variable valve timing device of the present invention.

FIG. 2 is a diagram for explaining the operation of the embodiment of FIG.

FIG. 3 is a diagram for explaining the operation of the embodiment of FIG.

[Explanation of symbols]

 1 ... Cam shaft 3 ... Timing pulley 5 ... Sleeve 5a, 5b ... Helical spline 11 ... Housing 11a, 11b ... Helical spline 15 ... Ring gear 19 ... Hydraulic chamber 27 ... Compression spring 30, 32, 34, 36 ... Stopper 30a ... Supporting part 30b ... Elastic member 30c ... Engaging surface 31, 33, 35, 37 ... Block

Claims (1)

Claim: What is claimed is: 1. A ring gear having at least one of the splines provided on the inner and outer circumferences a helical spline is interposed between the camshaft and the timing pulley,
The camshaft is rotationally driven from the timing pulley by meshing with splines provided on the camshaft and the timing pulley, and the ring gear is moved between a first operating position and a second operating position that are separated from each other in the camshaft axial direction. In the variable valve timing device, which moves the timing pulley and the cam shaft to relatively rotate the timing pulley and the cam shaft along the tooth trace of the helical spline to change the phase of the timing pulley and the cam shaft.
The timing pulley and the cam shaft each include a stopper member that engages with the ring gear in the first and second operating positions, and each of the stopper members elastically moves the ring gear along the circumferential direction when engaged. A variable valve timing device characterized by pressing.