JPH08260918A - Control device for valve opening/closing timing - Google Patents

Abstract

PURPOSE: To control the stable opening/closing of a valve by realizing the completely zero backlash attributable to a gear of a piston in a control device of valve opening/closing timing to change the relative phase between a pulley and a cam shaft by axially moving a geared piston interposed between the pulley and cam shaft. CONSTITUTION: A geared piston 18 is constituted by assembling a scissors member 19, an intermediate member 20, and a scissors member 21, and energizing members 24, 45 are interposed between the scissors member 19 and the intermediate member 20, and between the intermediate member 20 and the scissors member 21 respectively. The scissors member 19 and the intermediate member 20 are engaged with a first external gear 13 integrated with a cam shaft 11, while the intermediate member 20 and the scissors member 21 are engaged with a second external gear 15 of different angle of twist which is rotatably provided on the cam shaft 11. The zero backlash is realized in each biting condition of the piston 18 to the respective external gear 13 and the external gear 15 by the energizing members 24, 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve opening / closing timing control device for performing opening / closing timing control of intake / exhaust valves in an internal combustion engine by means of a geared piston interposed between a cam shaft and a timing pulley.

[0002]

2. Description of the Related Art In an engine valve operating mechanism, the opening / closing timing of a valve is changed by advancing or retarding the relative phase of a camshaft with respect to a timing pulley (hereinafter abbreviated as "pulley"), thereby changing the output of the engine. And a valve opening / closing timing control device for improving idle stability and the like.

FIG. 5 shows an example of a conventional valve opening / closing timing control device. In this conventional device, a pulley 2 is attached to an end portion of the camshaft 1 so as to be capable of phase shifting in the circumferential direction of the camshaft 1.
And a piston 4 having a helical gear inside and outside is housed in an annular axial chamber 3 formed between the pulley 2 and the cam shaft 1. Specifically, the axial chamber 3
Is formed by sealing a shaft surrounding portion of the pulley 2 with a case 6 integrated with the camshaft 1 via a knock pin 5. A helical internal gear 6a is formed on the inner peripheral wall of the case 6, and a helical external gear 2a is formed on the outer peripheral wall of the pulley 2 around the shaft. Helical external gears 4a and internal gears 4b are formed on the inner and outer circumferences of the piston 4 in correspondence with the internal gears 6a and the external gears 2a.
, And the internal gear 4b of the piston 4 is engaged with the external gear 2a of the pulley 2.

On the other hand, the driving means for driving the piston 4 is
A passage 7 that extends through the camshaft 1 and communicates with one end of the axial chamber 3, and a hydraulic control unit (not shown) such as a hydraulic pump or a hydraulic control valve in which a discharge side passage is connected to the passage 7. , And a spring member 8 disposed on the other end side of the axial chamber 3 as a main component. Therefore, according to such a valve opening / closing timing control device, when the hydraulic control unit controls the operating hydraulic pressure in accordance with the operating condition of the engine, the piston 4 is moved in the axial direction by the interaction with the spring member 8, and the camshaft is moved. 1 and the pulley 2 are forcibly rotated relative to each other. Thus, for example, during high load operation, the phase of the camshaft 1 with respect to the pulley 2 is changed so as to advance the timing of closing the intake valve to obtain a high output, and during low load operation, the timing of closing the intake valve is delayed. The phase of the camshaft 1 is changed to improve the stability of combustion.

[0005]

By the way, in the above valve opening / closing timing control device, since the piston 4 is in mesh with each tooth of the pulley 2 and the camshaft 1, there is a so-called backlash in the meshing portion thereof. . Due to the presence of this backlash, the force of the valve spring acts on the camshaft 1 in an alternating load manner, causing fluctuations in the rotational torque of the camshaft 1. When fluctuating torque is generated in this camshaft 1, an impact noise at the time of meshing is generated,
In the extreme case, there is a problem that the timing of opening and closing the intake and exhaust valves becomes unstable.

Therefore, in the conventional apparatus shown in FIG. 5, the viscous damper means 9 is provided on the outer periphery of the case 6 which is provided integrally with the camshaft 1.
To absorb the fluctuating torque. However,
The viscous damper means 9 does not have zero backlash with the pulley and the camshaft. In addition, special fair 5
JP-A-77742 discloses a cylindrical gear fitted between a pulley and a camshaft, having gears on the inner and outer circumferences (piston 4
In the form of two gear components divided into two in the plane perpendicular to the axis, and the two gear components are slightly displaced from each other, and are connected via an elastic member. There is.

According to the two-divided piston described in this publication, since the tooth traces are slightly deviated with the gear components separated from each other, the meshing portion of the pulley and the camshaft with the helical gear is backlashed. It can be zero.
However, in the conventional device of the above publication, two gears having different tooth trace directions are formed in one gear structure, and the backlash is set to zero. Therefore, the internal gear with respect to the external gear of one gear structure is used as a reference. Accurately aligning the internal and external gears of the other gear structure, it is necessary to adjust the apparent tooth thickness of each tooth in the state where each gear structure is connected,
It has the drawback that it is difficult to manufacture and its processing cost rises.

In response to the recent trend of demanding low hydraulic operability, if the outer diameter is increased in order to increase the pressure receiving area of at least one of the both gear components in the conventional device of the above-mentioned publication, the pulley diameter will be reduced. There are some restrictions, and it may not be possible to increase the outer diameter beyond what is required. In view of the above-mentioned conventional circumstances, the present invention requires a technique for reducing backlash to both tooth surfaces of a tooth groove of a helical gear in which the teeth of each divided gear structure as a piston have a processing accuracy. The problem to be solved is to realize it with a simple structure.

[0009]

According to the invention of claim 1 which has solved the above-mentioned problems, a first external tooth which is formed substantially integrally with a cam shaft and which has a substantially helical shape, and an axial direction of the first external tooth. Second helical teeth, which are adjacent to each other and are rotatably provided on the cam shaft, and have different helical streaks different from the first tooth, and tooth formation of the first tooth and the second tooth. One side wall has an axial chamber formed between the cam shaft and the timing pulley, and an inner tooth engaged with the first outer tooth, while a scissor member engaged with the first outer tooth. First
An intermediate member having internal teeth and second internal teeth engaged with the second external teeth, another scissors member having internal teeth engaged with the second external teeth, and between the one scissors member and the intermediate member Each of the one scissors member and the intermediate member and the other scissors member and the intermediate member are urged in the separating direction or the pulling direction so that a slight axial gap is maintained between the other scissors member and the intermediate member. And a piston fitted to the axial chamber including a biasing means.

According to a second aspect of the present invention, at least one of the one scissors member and the other scissors member is annularly engaged with the intermediate member in two or more axially divided states,
Each of the internal teeth of the one scissors member and the other scissors member is formed at substantially the same axial position as the first internal tooth or the second internal tooth of the intermediate member. Here, the substantially helical gear includes a normal helical gear and a helical spline.

[0011]

In the invention of claim 1, the piston which is reciprocally moved linearly in the axial chamber by the driving means includes one scissors member, an intermediate member and the other scissors member which are assembled to allow mutual axial movement. On the other hand, the inner teeth of the scissors member and the first inner teeth of the intermediate member engage with the first outer teeth, and the biasing means causes the one scissors member and the intermediate member to be slightly apart from each other or in the pulling direction. By being urged to the inner teeth of the scissor member and the first member of the intermediate member.
The internal teeth have zero backlash with respect to the first external teeth.

On the other hand, the inner teeth of the other scissors member and the second inner teeth of the intermediate member engage with the second outer teeth, and the other scissors member and the intermediate member are separated from each other by a biasing means with a slight gap. By being urged in the direction
On the other hand, the inner teeth of the scissors member and the second inner teeth of the intermediate member have zero backlash with respect to the second outer teeth. Therefore, when the piston reciprocates linearly in the axial chamber, the camshaft can change the phase with respect to the pulley with zero backlash. In this case, the second outer teeth function as stoppers for the moment that the piston tries to rotate in the tooth trace direction of the first outer teeth, and rotate relatively to the cam shaft.

In the invention of claim 2, at least one of the one scissors member and the other scissors member is
Since the intermediate member is annularly engaged in two or more divided states in the axial direction, and these scissors members are formed at substantially the same positions in the axial direction as the first internal teeth or the second internal teeth of the intermediate member,
The piston stroke amount can be increased.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A valve opening / closing timing control device of the present invention will be described below with reference to the illustrated embodiments. In FIG. 1, a pulley 12 is fitted on the cam shaft 11 so as to be capable of relative phase shifting, and one end portion of the cam shaft 11 protruding from the pulley 12 has external teeth 13a whose tooth traces are substantially helical. 1
The outer tooth member 13 is integrally connected via a key pin 14. Between the pulley 12 adjacent to the first external tooth member 13, the cam shaft 11 is rotated, and the external teeth 13a are different in helical tooth trace direction from each other as shown in FIG. The second outer tooth member 15 having the outer tooth 15a is attached.

An annular space formed by the inner peripheral surface of the pulley 12 and the tooth forming surfaces of the first outer tooth member 13 and the second outer tooth member 15 is sealed by a housing 16 to form an axial chamber 17. are doing. Then, the axial chamber 17 is fitted with a piston 18 made up of the following three members that can slightly move relative to each other in their axial positions. That is, as shown in FIG. 3, the piston 18 includes a scissor member 19 having internal teeth 19a engaged with the external teeth 13a and the external teeth 13a.
an intermediate member 20 having a first inner tooth 20a engaged with a and a second inner tooth 20b engaged with the outer tooth 15a, and assembled to the intermediate member 20 so as to be slidable in the axial direction, Tooth 1
The main component is a scissor member 21 having internal teeth 21a engaged with 5a.

The assembling structure of the intermediate member 20 and the scissor member 21 has a large diameter portion 20d which is enlarged in the radial direction to enlarge the pressure receiving area of the intermediate member 20 and extends from the large diameter portion 20d in the axial direction. The scissors member 21 is configured to be slidable in the axial direction with respect to the semi-cylindrical portion 20c. Here, the first internal tooth 20a is formed in the central hole of the large-diameter portion 20d, and the second internal tooth 2
0b is formed at the end of the semi-cylindrical portion 20c.

Then, the scissors member 19 and the intermediate member 20.
Means that the mutual phase shift is regulated by the engagement of the pin 22 and the pin hole 23 in the axial direction, and a slight axial movement is allowed by the biasing means 24 such as a coil spring interposed therebetween. The gap is maintained and biased in the separating direction. In addition, the scissors member 21 and the intermediate member 20
Similarly, the biasing means 25 holds a gap to allow some axial movement, and is biased in the separating direction.

Further, the driving means for directly moving the piston 18 according to the operating condition of the engine is the camshaft 11
26 that extends through and communicates with one end of the axial chamber 17
And a passage 27 that communicates with the other end of the axial chamber 17 and a hydraulic control unit (not shown) that controls the hydraulic pressure in the passages 26 and 27.
The piston 18 is moved to one end side and the other end side of the axial chamber 17 by being operated by a control signal from the CU.

In the above structure, the engagement state between the inner teeth 19a of the scissors member 19 and the first inner teeth 20a with respect to the outer teeth 13a is as shown in FIG. 4B, and the scissors member 21 with respect to the outer teeth 15a is engaged. The engagement state of the inner teeth 21a and the second inner teeth 20b is shown in FIG. That is, the scissors teeth 19a of the scissors member 19 and the first scissors teeth 20a of the intermediate member 20 are the forces in the opposite directions indicated by the arrows A and B in FIG. For example, in one tooth groove d of the outer tooth 13a of the member 13, a state where the backlash is zero is set, which is separated in the diagonal width direction.

On the other hand, the engagement state of FIG.
The inner teeth 20b are fixed to the outer teeth 15a, and the force indicated by the arrow F acts on the inner teeth 21a of the scissors member 21 to press the one tooth surface b of the teeth c of the outer teeth 15a into zero backlash. Take the state of. In this way, the piston 18 can be held in an engagement state with zero backlash with respect to both the first outer tooth member 13 and the second outer tooth member 15.

When the piston 18 is moved from one end side to the other end side (from left to right in FIG. 1) in each engagement state as described above, mainly the end surface of the scissor member 19 and the large diameter portion of the intermediate member 20 are moved. When the piston 18 tries to move in the same direction D due to the pressure in the moving direction D that acts on the end face, the external teeth 15
“A” functions as a stopper that blocks a rightward turning moment of the external teeth 13a acting on the piston 18 following the tooth trace direction, and maintains a stationary state. Therefore, the piston 18 can forcibly rotate the camshaft 11 in the left direction (direction of arrow E) via the first external tooth member 13.

Thus, even in the valve opening / closing timing control device having such a configuration, the basic operation is the same as the conventional one, and for example, the camshaft 11 is set to the pulley 12 so that the timing of closing the intake valve is advanced during high load operation. The camshaft 11 can be retarded with respect to the pulley 12 so that the timing of closing the intake valve is delayed during low load operation. Further, it is possible to suppress the collision noise due to backlash caused by the fluctuating torque and to perform stable valve opening / closing axis control.

Further, in the valve opening / closing timing control device of the above embodiment, as can be seen from the engagement state of FIG. 4 (A), the second internal teeth 20b and the internal teeth 21a of the scissors member 21 are substantially at the same axial position. Since the backlash is zero, the intermediate member 20 and the scissors member 21 are engaged with each other as shown in FIG.
Compared with the case where the scissors member 19 and the intermediate member 20 are engaged with each other, the extension of the scissor member 21 in the axial direction can be avoided, and the axial length can be shortened with respect to the required stroke.

The configuration of this embodiment has various advantages as follows. (1) A conventional piston in which a gear is formed inside and outside because an inner tooth group on the piston side is engaged with an outer tooth group on the camshaft side and one outer tooth is rotatable with respect to the camshaft. Processing is easier than the configuration of (gear structure). (2) In particular, regarding the processing accuracy, in the case of the conventional device, it is necessary to accurately align the internal gear and the external gear of the other gear structure with the internal gear to the external gear of one gear structure as a reference. However, since one of the outer teeth is rotatable with respect to the cam shaft and a slight movement in the axial direction is allowed, there is no problem of alignment.

(3) Compared to the conventional device in which the meshing portions of the outer teeth and the inner teeth are aligned in the axial direction and have only a single meshing portion, the diameter of the entire piston is prevented from expanding in the radial direction and the pulley diameter is prevented. It is possible to cope with the constraint of. (4) In order to take advantage of the effect of avoiding the swelling of the entire piston in the radial direction, the biasing members 24 and 25 are the intermediate member 2
The large diameter portion 20d of 0, that is, the front side farther from the pulley 12 is disposed, and the diameter is not increased over the entire axial length of the piston 18. On the other hand, in the conventional device, the elastic member occupies almost the entire axial length of the piston (gear),
Since urging members such as springs are inserted radially,
The diameter increases over the entire length of the piston. In this respect as well, the embodiment can avoid the expansion of the entire piston 18 in the radial direction.

(5) The piston 1 in the radial direction as described above
Since it is possible to prevent the whole 8 from expanding, only the large system portion 20d of the intermediate member 20 can have a large diameter. By separating this large-diameter portion from the attachment position of the pulley 12, the pressure receiving area can be increased without being restricted by the pulley diameter, and it can be adapted to low hydraulic drive. (6) Further, in the case of the conventional configuration, since the gears are provided on the inner and outer circumferences, the outer gear is engaged with the inner gear of the outermost housing, and the collision sound due to the backlash tends to be heard directly. .

On the other hand, in the present invention, since the teeth are all inside, the sound is not directly transmitted to the housing. Therefore, it is possible to reduce the force that makes the backlash to zero, that is, the resistance when the gear slides, and the response required for the valve opening / closing timing control device is improved. As another embodiment, for example, the driving means is not limited to reciprocating linearly moving the piston 18 only by hydraulic pressure as in the above embodiment, and one may be replaced with a spring means such as a spring.

[0028]

As described above, according to the first aspect of the invention, the substantially helical first outer teeth and the second outer teeth having different tooth traces are alternately axially integrated with the cam shaft so as to be rotatable. Since the internal teeth of the piston are engaged with the first outer teeth and the second outer teeth, the backlash-zero engagement state is achieved with a simple structure without requiring machining accuracy.

According to the second aspect of the present invention, since the internal teeth having zero backlash are engaged at substantially the same position in the axial direction, the axial length can be shortened with respect to the required stroke.

[Brief description of drawings]

FIG. 1 is a sectional view showing a valve opening / closing timing control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing the first embodiment mounted on the camshaft in the above embodiment.
It is explanatory drawing which shows the relationship between a gear and a 2nd gear.

FIG. 3 is an exploded perspective view of a piston used in the above embodiment.

FIG. 4 is an explanatory diagram for explaining that the backlash is zero on both sides according to the above embodiment.

FIG. 5 is a sectional view showing an example of a conventional valve opening / closing timing control device of this type.

[Explanation of symbols]

11 ... Camshaft, 12 ... Pulley, 13 ... First external tooth member (first external tooth), 15 ... Second external tooth member (second external tooth), 1
7 ... Axial chamber, 18 ... Piston, 19 ... One scissors member, 20 ... Intermediate member, 21 ... Other scissors member, 24,
25 ... Energizing means.

Claims (2)

[Claims] 1. A cam shaft for opening and closing a valve, a timing pulley held by the cam shaft for relative phase shift in the circumferential direction thereof, and a cam shaft substantially integrally formed with the cam shaft. A first outer tooth having a helical shape, and a substantially helical shape that is axially adjacent to the first outer tooth and is rotatably provided on the cam shaft, and has different tooth traces from the first outer tooth. A second outer tooth, an axial chamber formed between the cam shaft and the timing pulley with the tooth forming surfaces of the first outer tooth and the second outer tooth as an inner wall, and the first outer tooth One-sided scissors member with fitted internal teeth,
An intermediate member having first internal teeth engaged with the first external teeth and second internal teeth engaged with the second external teeth, and another scissors member having internal teeth engaged with the second external teeth , The one scissors member and the intermediate member and the other scissors member and the intermediate member so that a slight axial gap is maintained between the one scissors member and the intermediate member and the other scissors member and the intermediate member. And a driving means for reciprocating the piston in the axial chamber, the piston being housed in the axial chamber including the biasing means for biasing the piston in the separating direction or the pulling direction. A characteristic valve opening / closing timing control device. 2. At least one of the one scissors member and the other scissors member is annularly engaged with the intermediate member in two or more split states in the axial direction, and the inner teeth of the one scissors member and the other scissors member are respectively engaged. The valve opening / closing timing control device according to claim 1, wherein is formed at substantially the same axial position as the first internal tooth or the second internal tooth of the intermediate member.