JPH08260916A - Control device for valve opening/closing timing - Google Patents

Abstract

PURPOSE: To eliminate the effect on the movability of a piston by the energizing force in the separating direction when the piston is moved in the axial direction in the condition of the zero backlash relative to the gear on a pulley side and a cam shaft side by energizing first and second gear members constituting the piston in the separating direction from each other in the axial direction. CONSTITUTION: Oscillating members 20, 21 to be energized by an energizing member outwardly in the radial direction are interposed between a first gear member 18 and second gear members 19A, 19B, relatively small resistance is produced against the movement of a piston 17 because no members to directly energize the first and second gear members 18, 19A, 19B in the separating direction from each other in the axial direction is used, and the smooth movement of the piston 17 can be secured.

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.

The structure of a typical valve opening / closing timing control device is as described in Japanese Patent Publication No. 5-77843.
A cylindrical gear with teeth on the inner and outer circumferences is installed between the pulley and the camshaft, with the outer teeth of the pulley meshing with the inner teeth of the camshaft and the rotation of the pulley can be transmitted to the camshaft. In addition, a gear drive mechanism is known that moves the gear in the axial direction of the camshaft.

Therefore, according to such a valve opening / closing timing control device, when the gear drive mechanism controls the operating hydraulic pressure in accordance with the operating condition of the engine, the gear is moved in the axial direction to rotate the pulley and the cam shaft relative to each other. It is possible to change the opening and closing timing of the valve by moving the valve. For example, during high load operation, the timing of closing the intake valve is advanced to obtain a high output, and during low load operation, the timing of closing the intake valve is delayed to improve combustion stability, fuel efficiency, and the like.

[0005]

The valve opening / closing timing control device has a structure in which the gear meshes with the gears of the pulley and the camshaft, so that there is a so-called backlash at the meshing parts. Due to the presence of this backlash, the force of the valve spring acts on the camshaft in an alternating load manner, causing fluctuations in the rotational torque of the camshaft. When fluctuating torque is generated on the camshaft, there is a problem that an impulsive sound is generated at the time of meshing, and in extreme cases, the timing of opening and closing the intake and exhaust valves becomes unstable.

In view of the above, in the conventional device of the above publication, the gears are interposed between a plurality of gear components whose tooth traces are slightly displaced from each other and the gear components are separated from each other. And a coil spring that biases in the axial direction. The gear composed of the plurality of gear components and the coil spring has a structure in which each gear component has its tooth trace slightly displaced and is biased in the axial direction away from each other by the coil spring, so that Since the backlash with the helical gear of (1) is filled and the backlash is zero on the pulley and the camshaft, the valve opening / closing timing control is performed by suppressing the fluctuation torque of the camshaft.

However, the conventional valve opening / closing timing control device using the plurality of gear components has the following problems. First, the coil spring in the conventional device needs an appropriate spring load capable of overcoming the fluctuation torque of the camshaft. Here, if the fluctuating torque is large, the spring load of the coil spring has to be increased accordingly, but there is a limit in increasing the spring load. Therefore, it is necessary to deal with this by increasing the man-hours of the coil spring, and in this case, the number of component negative products increases.

Secondly, the camshaft rotated by the engine receives a large load torque that counteracts the rotational direction from immediately after the cam presses the valve spring until it passes the pressed portion. In the case of a normal engine, the direction of the load torque is the right rotation direction when viewed from the gear side, that is, the front side of the engine. For this reason, the gear requires a larger hydraulic pressure when moving from the front side to the rear side (usually when the phase advances) than when moving from the rear side to the front side in the axial direction.

However, in the gear of the above-mentioned conventional device, the portion receiving the hydraulic pressure is on the rear side, and when the hydraulic pressure is applied during the phase advance, a force is applied in the direction in which the urging force that reduces the backlash to zero becomes stronger, so the front side This is a cause of deterioration in operability when moving from the rear to the rear side. The present invention has been made in view of the above-mentioned conventional circumstances, and when the backlash is set to zero by a gear as a piston composed of a plurality of gear components, the load torque applied to the camshaft and the gear components are mutually different. An object of the present invention is to make it possible to smoothly move a piston without being affected by the axial force of separation.

[0010]

In order to solve the above-mentioned problems, the present invention according to claim 1 is formed axially between a camshaft and a timing pulley, and an inner wall integral with the camshaft and an inner wall integral with the timing pulley. And a gear on the camshaft side, which is a compound gear member that is composed of an axial chamber in which at least one of the gears formed in and has a substantially helical shape, and a next element fitted in the axial chamber. A first member that has internal teeth that are engaged and external teeth that are engaged with the gear on the timing pulley side, and that is fitted to the front side in the axial direction.
A gear member and a second gear member fitted on the rear side in the coaxial direction, and two or more swinging members held between the first gear member and the second gear member so as to be displaceable in the radial direction, A piston including a biasing member that biases the two or more swinging members in the centrifugal direction to move the first gear member and the second gear member in the axial direction away from each other.

According to a second aspect of the present invention, at least one of the first and second gear members is formed with a guide groove for narrowing the two or more swinging members while guiding them in the radial direction. Characterize. A third aspect of the present invention is characterized in that the first gear member on the front side has a pressure receiving portion for the hydraulic oil.

Here, the substantially helical gear includes a normal helical gear and a helical spline. On the other hand, the inner and outer teeth of the first gear member and the second gear member are
It is formed by a means such as making the tooth thickness smaller than the tooth groove of the helical gear, or shifting the tooth trace.

[0013]

In the invention of claim 1, the first gear member and the second gear member of the composite gear member forming the piston are:
The two or more swinging members held between the two are moved in the axial direction away from each other by being biased in the radial direction by the biasing member. Therefore, the teeth of the first gear member and the teeth of the second gear member engage with the helical gear formed on either the camshaft side or the timing pulley side with zero backlash.

The urging member for urging the oscillating member also acts on the oscillating member due to the centrifugal force, so that the spring constant can be reduced accordingly, and the piston can be easily assembled. As described above, according to the first aspect of the invention, the engagement state with zero backlash can be secured without deteriorating the responsiveness of the valve opening / closing timing control device and the workability. In the invention of claim 2 subordinate to claim 1, the two or more rocking members are guided in radial or centrifugal guide grooves formed in at least one of the first and second gear members. Since the guide groove is narrowed along the moving direction of the swinging member, the two or more swinging members move the first and second gear members in the axial direction away from each other.

According to the second aspect of the present invention, in particular, since the guide grooves regulate the moving directions of the two or more swinging members, the two or more swinging members are not unevenly concentrated, and the zero backlash state is reliably achieved. It In the invention of claim 3 subordinate to claim 1, since the first gear member on the front side has a pressure receiving portion for hydraulic oil, the hydraulic oil weakens the urging force of the urging member when the phase advances. Since it works, the movement from the front side to the rear side is performed with good responsiveness.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The 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 onto the cam shaft 11 so as to be capable of relative phase shift, and one end portion of the cam shaft 11 protruding from the pulley 12 to the front side has an outer portion (outer ring) where tooth traces are substantially helical (outer ring). ) A gear member 13 having a gear 13a is integrally connected via a key pin 14. Further, the pulley 12 is
A cylindrical portion 12 'extending in the same end portion direction is provided, and a helical inner gear 12a in the same direction as the gear member 13 is formed on the inner peripheral surface of the cylindrical portion 12'. A space 15a surrounded by the inner gear 12a of the pulley 12 and the outer gear 13a on the camshaft side extends to the front side similarly to the inner peripheral sliding surface 12b of the cylindrical portion 12 'that further extends to the front side. It communicates with a space 15b surrounded by the outer peripheral sliding surface 13b of the gear member 13, and both spaces 15a and 15b are sealed by a housing 16 to form an axial chamber 15. Here, the space 15b on the front side projects more radially than the space 15a on the rear side.

By the way, the piston 17 made of the following members is fitted in the axial chamber 15. That is, as shown in FIGS. 2 and 3, the piston 17 includes a cylindrical first gear member 18 having a flange portion 18c located in the space 15b on the front side and a second gear in the space 15a on the rear side. The members 19A and 19B, the two rocking members 20 and 21 held between the first gear member 18 and the second gear members 19A and 19B, and the rocking members 20 and 21 radially outward. It is composed of a biasing member 23 such as a coil spring for biasing.

The first gear member 18 has outer teeth 18a formed on the outer circumference of the rear side cylindrical portion and inner teeth 18b formed on the inner circumference of the rear side cylindrical portion with respect to the flange portion 18a. Engages with the inner gear 12a of the pulley 12, and the inner teeth 18b engage with the outer gear 13a on the camshaft side. Here, the internal teeth 18b, 19b and the external teeth 18a, 19
The a is formed by means such as making the tooth thickness smaller than the tooth space of the helical gears (12a, 13a) or shifting the tooth trace.

The second gear members 19A and 19B may be integrally formed, but in this case, they are composed of two semi-circular annular pieces, each of which has outer teeth 19a on its outer circumference and inner teeth on its inner circumference. 1
9b are formed on the pulley 12 and the outer teeth 19a are formed on the pulley 12
Of the internal gear 12a, and each of the internal teeth 19b is engaged with the external gear 13a on the camshaft side. Further, the front end surfaces of the second gear members 19A and 19B are formed as tapered smooth surfaces 19c and 19c that are concave toward the axis.

Corresponding to the tapered smooth surfaces 19c, 19c, the semicircular rear end surfaces of the two rocking members 20, 21 are convexed toward the axial center.
c, 21c, the tapered smooth surface 19c, 1
9c and the tapered smooth surfaces 20c and 21c as sliding contact portions,
The two rocking members 20 and 21 are movable in the radial direction. Then, as described above, the two rocking members 20, 21
Since the biasing member 23 is interposed between the two rocking members 20, 21, the two rocking members 20 and 21 are constantly biased radially outward (see arrow A in FIG. 2).

Two rocking members 20, respectively, are also provided at the sliding contact portions 24 (here, the end faces perpendicular to the axis) opposite to the sliding contact portions between the tapered smooth surfaces 19c, 19c and the tapered smooth surfaces 20c, 21c. 21 and the first gear member 18 are formed as a smooth surface. Next, the drive means for directly moving the piston 17 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 15
And a passage 27 that communicates with the other end of the axial chamber 15 and a hydraulic control unit (not shown) that controls the hydraulic pressure in each of the passages 26 and 27.
The piston 17 is moved in the axial direction of the axial chamber 15 by being operated by a control signal from the CU.

In the valve opening / closing timing control device having the above structure, the rotation of the camshaft 11 causes a centrifugal force to be generated in the rocking members 20 and 21, and the rocking members 20 and 21 receive the force of the biasing member 23. Move radially outward. As a result, the oscillating members 20 and 21 urge and move the first gear member 18 and the second gear member 19 in the axial directions shown in FIG. Thus, a slight gap is generated between the first gear member 18 and the second gear member 19, and the outer teeth 18a of the first gear member 18 and the outer teeth of the second gear member 19 meshed with the inner gear 12a on the pulley side. 19a serves as scissors teeth and engages with the pulley 12 with zero backlash.
Similarly, the first gear meshed with the outer gear 13a on the camshaft side.
Inner teeth 18b of the gear member 18 and inner teeth 1 of the second gear member 19
9b becomes a scissors tooth and engages with the camshaft 11 with zero backlash.

Therefore, the hydraulic pressure by the driving means is applied to the axial chamber 1
5, when the piston 17 is applied to the front side, the piston 17 moves from the front side to the rear side in an engagement state with zero backlash, and the camshaft 11 can be phase-shifted with respect to the pulley 12. Further, since the urging member 23 for urging the oscillating members 20 and 21 also exerts a centrifugal force on the oscillating members 20 and 21, the spring constant can be reduced accordingly, and the piston can be easily assembled.

In addition, as a result of the increase of the centrifugal force due to the rotation of the cam shuff 11, the rocking members 20 and 21 are subjected to the increase of the hydraulic pressure of the driving means which increases when the engine rotates at a high speed, the spring constant of the biasing member 23 is reduced. However, the engagement state with zero backlash is stable. Thus, in the first embodiment, it is possible to prevent the noise due to the backlash caused by the fluctuation torque of the camshaft 11 and to perform the stable valve opening / closing timing control.

A further unique point of the first embodiment is that the first gear member 18 on the front side has the flange portion 18
By having c, the pressure receiving area can be made large even at low hydraulic pressure, the responsiveness when moving from the front side to the rear side is improved, and smooth reciprocating while balancing with the movement from the rear side to the front side. It is possible to move. Next, FIG. 4 showing the second embodiment shows only the piston 17. In this embodiment, the first gear member 18 has the same shape as that of the embodiment of FIG. 1 and also has outer teeth 18a and inner teeth 18b. The second gear member 19 is formed as a single piece in a cylindrical shape, and has an outer tooth 19a and an inner tooth 19b that make one round. As in FIG. 1, the outer teeth 18a and the outer teeth 19a are the inner gear 12a on the pulley side.
, And the inner teeth 18b and the inner teeth 19b are engaged with the outer gear 13a on the camshaft side.

In the construction in which the engagement is zero backlash, a plurality of guide grooves 2 are formed in the front end face of the second gear member 19 in the centrifugal direction and are narrowed radially outward.
..., the guide grooves 28, 28 ... and the rear side end surface of the first gear member 18, respectively, and the spheres 25, 25. It is composed of urging members 29, 29, ...

That is, the second embodiment realizes the aspect of claim 4, and the spheres 25, 25 ... Are constantly urged in the centrifugal direction by the urging member 29, so that the first gear member 18 is formed.
The second gear member 19 is moved in the axial direction away from each other. Therefore, the outer gear 13a on the camshaft side has a first
The inner teeth 18b of the gear member 18 and the inner teeth 19b of the second gear member 19 are attached to the inner gear 12a on the pulley side by the first gear member 18b.
The outer teeth 18a of the second gear member 19 and the outer teeth 19a of the second gear member 19 are engaged with each other with zero backlash, so that the sound due to the backlash due to the varying torque of the camshaft 11 is prevented as in the above embodiment.

In the second embodiment, the guide groove 2
Since the moving directions of the spheres 25, 25 ... Are regulated by 8, 28 ..., Uneven concentration is prevented and an accurate zero backlash state is achieved. In each embodiment, the piston 17
Although it is reciprocally moved linearly only by hydraulic pressure, one may be replaced with a spring means such as a spring.

Further, the engagement of the piston 17 with the cam shaft side and the pulley side may be any one of gears having a helical shape.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a valve opening / closing timing control device according to an embodiment of the present invention, in which an upper half shows a state where a piston is located on a front side and a lower half shows a state where a piston is located on a rear side. Is represented.

FIG. 2 is a sectional view showing the piston of the above embodiment.

FIG. 3 is a side view of FIG. 2 viewed from the left side.

FIG. 4 is a sectional view showing a piston according to a second embodiment.

[Explanation of symbols]

11 is a camshaft, 12 is a pulley, 13 is a gear member,
15 is an axial chamber, 17 is a piston, 18 is a first gear member, 18c is a flange portion, 19 is a second gear member, 20,
21 is a swing member, 23 is a biasing member, 28 is a guide groove, 2
Reference numeral 9 denotes an urging member, and members having the same function are denoted by the same reference numerals in each drawing.

Claims (3)

[Claims] 1. A camshaft for opening and closing a valve, a timing pulley held by the camshaft for relative phase shift in the circumferential direction, and a shaft between the camshaft and the timing pulley. In the axial direction, at least one of gears formed respectively on the inner wall integral with the cam shaft and the inner wall integral with the timing pulley has an axial chamber that is substantially helical, and is fitted in the axial chamber. A composite gear member comprising the following elements, each having internal teeth engaged with the gear on the camshaft side and external teeth engaged with the gear on the timing pulley side, and fitted on the front side in the axial direction. First gear member and a second gear member fitted on the rear side in the coaxial direction,
The two or more swinging members that are held between the first gear member and the second gear member so as to be displaceable in the radial direction, and the two or more swinging members are urged in the centrifugal direction, A piston composed of a first gear member and a second gear member that move in the axial direction so as to separate from each other, and the axial chamber from at least one side in the axial direction to reciprocate the piston in the axial chamber. A valve opening / closing timing control device comprising: a drive means for feeding hydraulic oil to the. 2. A guide groove is formed in at least one of the first and second gear members, the guide groove narrowing while guiding the two or more rocking members in a radial direction. 1. The valve opening / closing timing control device described in 1. 3. The valve opening / closing timing control device according to claim 1, wherein the first gear member on the front side has a pressure receiving portion for the hydraulic oil.