JP3079778B2 - Valve timing adjustment device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing adjusting device for changing the opening / closing timing of an intake / exhaust valve of an internal combustion engine according to operating conditions.

[0002]

2. Description of the Related Art A camshaft is driven from a crankshaft via a rotation transmission member such as a timing belt, a chain or a gear in order to adjust the valve timing of an intake / exhaust valve in accordance with the operating conditions of an internal combustion engine. In a valve operating mechanism, for example, a relative rotation is provided between a rotation transmitting member and a camshaft. In the case of a DOHC (double overhead camshaft) type valve operating mechanism, a camshaft for an exhaust valve and a It is known to insert a valve timing adjustment device in the middle of a transmission system, such as to provide relative rotation between a driven intake valve camshaft.

One type of such a valve timing adjusting device is a cylindrical gear having a central gear, and the same number of internal teeth fitted over teeth formed on the central gear. Further, a three-layer compound gear composed of an outermost inner gear provided with the same number of internal teeth fitted so as to cover teeth formed on the outer peripheral side of the cylindrical gear is a main constituent element. There is something to do. In this case, since the three internal and external gears constituting the compound gear are fitted with each other, it can be said that these teeth have characteristics closer to spline teeth rather than ordinary gear teeth. .

In this type of valve timing adjusting device, at least one pair of the tooth profiles of the two pairs of teeth forming the inner and outer double spline-shaped fitting portions of the compound gear is formed with helical splines. By moving the cylindrical gear forming the intermediate layer in the axial direction with respect to the center gear and the outermost internal gear, the relative position between the center gear and the outermost internal gear is increased. Rotation can be caused, whereby the rotation transmitting member and the cam shaft, or the intake valve cam shaft and the exhaust valve cam shaft, which are respectively connected to the central gear and the outermost internal gear, rotate relatively. The valve timing changes continuously according to the axial position of the cylindrical gear. As described above, in this type of valve timing adjusting device, there are two spline-shaped fitting portions inside and outside the cylindrical gear of the intermediate layer in the three-layer compound gear, so that each of these fitting portions is formed. If there is a backlash between the spline-shaped teeth of the pair of gears, a striking sound is generated from those parts when the internal combustion engine is operated, which is one factor of engine noise.

Conventional techniques for addressing this problem are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 62-3111 and 62-31.
No. 12, etc. In these prior arts, among the three-layered compound gears in the valve timing adjustment device described above, an `` elongated gear '' that is long in the axial direction is used as an equivalent to a cylindrical gear forming an intermediate layer, It is cut into two or more parts arranged in the axial direction (round slice), and each of those parts is allowed to move relative to each other by a small distance in the axial direction. As a biasing device for causing relative movement, various types of elastic bodies are interposed between the respective portions. In these valve timing adjustment devices, each of the long cylindrical gears divided into a plurality of portions arranged in the axial direction relatively moves (approaches or separates) by a small distance in the axial direction. As a result, the tooth traces of the bevels (helical splines) of the respective parts are shifted from each other, and as a result, the apparent tooth thickness of the teeth of the cylindrical gear as a whole increases, and the center gear and the innermost periphery The backlash in the fitting portion with the gear teeth is absorbed.

[0006]

In the above-described valve timing adjusting apparatus according to the prior art, it is necessary to eliminate the backlash at the spline fitting portion of each layer of the compound gear and to prevent the occurrence of tapping noise during operation of the internal combustion engine. Since it is necessary to increase the length of each of the gear components divided into a plurality of parts in the axial direction and to increase the relative axial movement distance, the gear components are stacked. In addition to the fact that the total axial length of the cylindrical gear becomes considerably large, and the elastic body inserted in series between those parts further increases the axial length of the cylindrical gear as an aggregate, Since the entire valve timing adjusting device becomes longer in the axial direction and the elastic body must be accommodated in the radial thickness of the cylindrical gear, the radial size of the compound gear also increases. Reasons Rukoto like, it is difficult to combine the valve timing control apparatus compact. In addition, the compound gear in this case has a complicated structure, and it is necessary to make each of the gear components and the like with high precision. An object of the present invention is to solve these problems of the prior art.

[0007]

According to the present invention, as a means for solving the above-mentioned problems, at least a central gear connected to either a crankshaft side or one camshaft side of an internal combustion engine. And an outermost inner gear connected to the other of the crankshaft side or the camshaft side and supported so as to cover the center gear coaxially therewith, and an innermost gear of the center gear and the outermost circumference. An assembly comprising three members of a control gear for relatively rotating the center gear and the outermost inner gear by being inserted into an annular space between the gears and moving in the axial direction, The control gear has a substantially cylindrical shape, and has an internal tooth helical spline and an external tooth helical spline on the radially inner and outer surfaces, respectively, and the internal tooth helical spline is an external tooth formed on the central gear. Fits into helical splines, together with the outer tooth helical spline is fitted to the internally toothed helical splines formed on the internal gear of the outermost circumference, the
The control gear consists of a first component and a second component.
The first component and the second component are
Through an elastic body that urges them in opposite directions in the radial direction.
Are connected in the axial direction, or the control gear is
Partially changed by the bias of the elastic body loaded inside
By being formed of a resin that can be shaped, the external helical splines on the outer surface of the control gear are radially outward, and at the same time, the internal helical splines on the inner surface of the control gear are radially inward. each provides a valve timing control apparatus for an internal combustion engine, characterized by being urged by the elastic member to move by a small distance.

[0008]

In the valve timing adjusting device for an internal combustion engine according to the present invention, a control gear is inserted into an annular space between the central gear and the outermost internal gear, and is moved in the axial direction. By rotating the central gear and the outermost internal gear relatively, the rotational phase between the crankshaft and the camshaft of the internal combustion engine is changed. In this case, the control gear has a substantially cylindrical shape, and is provided with helical splines on its inner and outer surfaces in the radial direction.The helical splines are formed on the outer surface of the center gear and the inner surface of the outermost inner gear. Each spline is fitted, but the external helical spline on the outer surface of the control gear is radially outward,
Since the internal teeth helical spline on the inner surface of the control gear is urged by an elastic body to move a small distance radially inward, backlash is likely to occur at each fitting point of the helical spline. However, the helical splines on the inner and outer surfaces of the control gear move a small distance in the radial direction to fill the backlash, so that no backlash remains at each fitting point, and the backlash does not occur when the internal combustion engine is operated. There is no danger of hitting due to the rush.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a first embodiment, the present invention is applied to a DOHC type valve operating mechanism for driving a camshaft for an intake valve from a camshaft for an exhaust valve via a pair of timing gears as shown in FIG. FIG. 1 is a vertical sectional front view showing the entire configuration in a case where a valve timing adjusting device is inserted between a driven side timing gear and a camshaft for an intake valve. In FIG. 1, reference numeral 1 denotes a cam shaft for an intake valve, and reference numeral 2 denotes a cam shaft for an exhaust valve. The camshaft 2 for the exhaust valve in the illustrated example is driven to rotate directly from the crankshaft of the internal combustion engine via a timing pulley (not shown) and the like.
A camshaft 1 for the intake valve has a timing gear 4 meshing with a timing gear 3 mounted on the camshaft 2 for the exhaust valve.
Through the camshaft 2 for the exhaust valve.

The timing gear 3 is a so-called scissors gear, and its constituent gear 3a is fixed to the camshaft 2, while the constituent gear 3b is loosely fitted to the camshaft 2 and provided between the timing gear 3a and the constituent gear 3a. The elastic member is biased by the elastic member, so that the teeth of the timing gear 4 are sandwiched between the teeth of the constituent gears 3a and 3b to reduce the backlash. The teeth of the timing gear 4 meshing with the timing gear 3 are formed on the outer periphery of the cam gear housing 5, and the cam gear housing 5 is located on the right end side in FIG.
It is screwed and integrated with the flange portion 6a of the cylindrical sleeve 6 rotatably loosely inserted into the cam shaft 1 for the intake valve, and is integrated with the flange 7 on the left end side by caulking. I have.

A hollow shaft 8 having two steps therein is loosely inserted into a camshaft 1 for an intake valve and a cylindrical sleeve 6, and a cam 8 for an intake valve is formed in an axial groove 8a formed therein. The pin 9 driven into the shaft 1 is engaged so as to rotate in the same manner as the camshaft 1 for the intake valve. To position the cam gear housing 5 and the hollow shaft 8 in the axial direction, a nut 10 is provided on the left end side of the cam shaft 1 for the intake valve.
, And presses one of the steps of the hollow shaft 8 toward the step of the camshaft 1 for the intake valve with the flange 7 interposed therebetween. With this structure, the camshaft 1, the pin 9, the hollow shaft 8, and the nut 10 for the intake valve are substantially integrated, but the flange 7, the cam gear housing 5, and the cylinder separately integrated therewith. The sleeve 6 is allowed to rotate relatively around its axis.

An internal helical spline 5a is formed on a part of the inner peripheral surface of the cam gear housing 5, and an external helical spline 8b is formed on a part of the outer peripheral surface of the hollow shaft 8. The external helical spline 8b has a reverse twist angle with respect to the internal helical spline 5a, but in some cases, one of the internal helical spline 5a or the external helical spline 8b is a special form of helical spline. May be a helical spline having a twist angle of zero, that is, a linear spline parallel to the direction of the axis.

In this manner, a substantially cylindrical gap is formed between the cam gear housing 5 and the hollow shaft 8, and the gap is formed in the gap as shown in FIG. 2 and FIG. Gear 11 is inserted. Control gear 11
An external helical spline 11a is formed on a part of the outer peripheral surface of the control gear 11, and the external helical spline 11a is fitted on the internal gear helical spline 5a of the cam gear housing 5. Is the internal helical spline 11b
Which is fitted with the external tooth helical spline 8 b of the hollow shaft 8. In this case, that the helical splines are fitted with each other means that the helical splines of the fitted two pairs of internal teeth and external teeth have the same twist angle, respectively. The external helical spline 11a and the internal helical spline 11b have a twist angle in opposite directions with respect to each other, and as described above,
One of them can be a straight spline as a special form of helical spline.

The control gear 11 can move axially in and out of a substantially cylindrical gap between the cam gear housing 5 and the hollow shaft 8 while maintaining the engagement with two mating helical splines. It is inserted and urged in one direction by the spring 12 shown in FIG. In FIG. 1, a hydraulic chamber 13 is formed between the right end side of the control gear 11 and the flange portion 6a of the cylindrical sleeve 6 so that an oil pressure of an arbitrary magnitude opposing the urging force is generated. The hydraulic chamber 13 communicates with a hydraulic control valve (not shown) through the hole 6b of the cylindrical sleeve 6, the hole 1a of the camshaft 1 for the intake valve, and the through hole 1b in the axial direction.
As a result, an arbitrary amount of hydraulic pressure can be supplied. In the figure, 1c is a steel ball press-fitted to close the left end of the through hole 1b in the axial direction of the camshaft 1,
Reference numeral 7a denotes a vent hole opened in the flange 7, and 11c denotes an O-ring for sealing inserted in a groove of the control gear 11.

The hydraulic chamber 13 is controlled by a hydraulic control valve (not shown).
When a certain amount of hydraulic pressure is supplied to the control gear 11 in FIG.
The control gear 11 moves in the axial direction to a position where the biasing force of Step 2 is balanced, and stops at that position. When the control gear 11 moves in the axial direction, two pairs of helical splines having different torsion angles, that is, internal tooth helical splines 5 are formed.
a and the external tooth helical spline 11a, and the internal tooth helical spline 11b and the external tooth helical spline 8b
In response to a change in the respective mating positions of the pair of cams, a relative rotation occurs between the cam gear housing 5 and the hollow shaft 8, whereby the camshaft 1 for the intake valve and the camshaft 2 for the exhaust valve As a result, a difference in the rotation timing occurs between the intake valve and the intake valve, and a desired change in valve timing occurs between the intake valve and the exhaust valve. Regarding the above configuration and the basic operation as a valve timing adjusting device, the first embodiment does not have any special features as compared with the prior art.

The feature of the first embodiment is that, as clearly shown in FIGS. 2 and 3, the control gear 11 has an annular thick portion 11c between the external helical spline 11a and the internal helical spline 11b. A plurality of holes 11d are formed over the entire circumference. As shown in FIG. 1, the control gear 11 is inserted into an annular gap between the cam gear housing 5 and the hollow shaft 8, and two pairs of helical splines are fitted. In this state, before the flange portion 6a of the cylindrical sleeve 6 is screwed, the spring pins 14 are driven into the holes 11d to apply a biasing force in the direction in which the holes 11d expand.

The material of the control gear 11 needs to have some flexibility so that the annular thick portion 11c can be deformed in the radial direction by the biasing in the radially expanding direction by the spring pin 14. Yes, for that, for example, PPS or PB
It is preferable to use a thermoplastic resin such as T or a nylon resin. By driving the spring pin 14 into the hole 11d of the control gear 11, as shown in FIG.
The external gear helical spline 11a of the control gear 11 is slightly pushed outward to form like 11a ', and the internal gear helical spline 11b is slightly pushed inward to form like 11b'. Become.

The deformed helical splines 11a 'and 11b' are pressed radially toward the internal helical splines 5a of the cam gear housing 5 and the external helical splines 8b of the hollow shaft 8, respectively. The intervening backlash disappears, preventing the generation of a tapping sound when the internal combustion engine is operated. In addition, the control gear 1
Even if each helical spline wears, the helical spline 11 deformed by the bias of the spring pin 14
Since a 'and 11b' are always pressed against the helical spline of the other party, there is no danger of backlash increasing due to wear, and the state of zero backlash can be maintained at any time. As described above, the extremely simple structure of driving the spring pin 14 into the hole 11d of the control gear 11 can provide an effect of eliminating a tapping sound, similarly to the complicated structure in the related art. In this embodiment, a C-shaped spring pin 14 is used.
, The control gear 11 is expanded, but a leaf spring, a coil spring, or the like may be used instead of the spring pin 14 having a C-shaped cross section.

FIGS. 5 to 7 show a second embodiment of the present invention. In this embodiment, the control gear 15 is a compound gear, and in the manufacturing process, the control gear 11 and the control gear 11 in the first embodiment are combined. A material formed to have substantially the same outer shape, an outer tooth helical spline 16a and an inner tooth helical spline 16b on a part of the outer periphery and a part of the inner periphery corresponding thereto, and splines 16a and 16b as separate bodies. The ring-shaped portion 17 having the external tooth helical spline 17a and the internal tooth helical spline 17b formed so that the tooth leads coincide with each other is formed.

Next, the main part of the control gear 15 (first
Component) The pin 18 is driven into a hole 16d that is bored in the axial direction at a symmetrical position in the 16 annular thick portion 16c, and at a position substantially corresponding to the pin 18,
Ring-shaped portion of control gear 15 (second component) 17
An opening 17d having a diameter slightly larger than that of the pin 18 is formed in the annular thick portion 17c. Further, a tangential groove 16e is formed in the annular thick portion 16c of the main portion 16, and
An annular thick portion 17c of the ring-shaped portion 17 in contact therewith
Then, the positions are slightly shifted in the longitudinal direction to form tangential grooves 17e of the same size. The tangential groove 16e and the corresponding tangential groove 17e are loaded with an elastic body 19 such as a coil spring or rubber compressed at the time of assembly.

The valve timing adjusting apparatus according to the second embodiment of the present invention has an overall configuration substantially similar to that of FIG. 1, while the control gear 15 which is the main part has such a special structure. The main body portion 16 and the ring-shaped portion 17 constituting the control gear 15 are urged by the force to expand the elastic body 19 to move toward each other in the direction opposite to the radial direction. Tooth helical splines 16a, 17a and internal tooth helical splines 16b,
As shown in FIG. 7, 17 b is an internal helical spline 5 a of the cam gear housing 5 similar to that shown in FIG. The splines 8b are pressed inward and outward, and the backlash existing between them is eliminated, so that the hitting noise generated during operation of the internal combustion engine is prevented. In the second embodiment, the control gear 15 is divided into a main portion 16 and a ring-shaped portion 17, but unlike the prior art, their axial lengths may be extremely small, and are relatively small in the axial direction. Since there is no need to move the valve timing adjusting device, it does not cause an increase in the size of the valve timing adjusting device.

[0022]

According to the valve timing adjusting apparatus of the present invention, the backlash of the helical spline is eliminated by a configuration much simpler than that of the prior art, thereby preventing the occurrence of tapping noise during operation of the internal combustion engine. be able to. Further, according to the present invention, the size of the control gear of the valve timing adjusting device and the size of the entire device including the control gear can be reduced particularly in the axial direction.
This makes it possible to reduce the size of the lube timing adjusting device as compared with the conventional device .

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an overall configuration of a valve timing adjusting device as a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a main part of the first embodiment.

FIG. 3 is a side view showing a main part of the first embodiment.

FIG. 4 is a perspective view showing an operation state of a main part of the first embodiment.

FIG. 5 is a longitudinal sectional view showing a main part of a second embodiment of the present invention.

FIG. 6 is a side view showing a main part of the second embodiment.

FIG. 7 is a partially enlarged view showing an operation state of a main part of the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cam shaft for intake valve 2 ... Cam shaft for exhaust valve 3 ... Timing gear (scissors gear) 4 ... Timing gear 5 ... Cam gear housing 5a ... Internal helical spline 6 ... Cylindrical sleeve 6a ... Flange part 7 ... Flange 8 ... hollow shaft 8a ... axial groove 8b ... external tooth helical spline 11 ... control gear 11a ... external tooth helical spline 11b ... internal tooth helical spline 11c ... annular thick part 11d ... hole 12 ... spring 13 ... hydraulic chamber Reference Signs List 14 spring pin 15 control gear 16 main part 16a external helical spline 16b internal helical spline 16e tangential groove 17 ring-shaped part 17a external helical spline 17b internal helical spline 17d Large-diameter opening 17e: tangential groove 18: axial direction Down 19 ... elastic body

Claims (2)

(57) [Claims] At least one center gear connected to one of the crankshaft side and one camshaft side of the internal combustion engine, and the center gear connected to the other of the crankshaft side or the camshaft side. The outermost inner gear supported coaxially with the gear so as to cover it, and inserted into an annular space between the center gear and the outermost inner gear to move in the axial direction, thereby moving the center of the center. It has an aggregate of three members of a gear and a control gear that relatively rotates the outermost inner gear, and the control gear has a substantially cylindrical shape, and has a radially inner and outer surface. Each has an internal helical spline and an external helical spline.The internal helical spline fits into an external helical spline formed on the central gear, and the external helical spline is the outermost helical spline. Along with the internal gear helical spline formed on the peripheral internal gear, the control gear is
A first component part and a second component part, wherein the first component
Component and said second component make them halfway from each other.
Connected in the axial direction through an elastic body that urges in the opposite direction to the radial direction.
By being tied, the external helical splines on the outer surface of the control gear are radially outward, and at the same time, the internal helical splines on the inner surface of the control gear are radially inward, each having a small distance. only the valve timing control apparatus for an internal combustion engine, characterized by being urged by the <br/> elastic body to move. 2. At least a crankshaft side of an internal combustion engine or
Is the center connected to one of the camshaft sides
Gear and the other of the crankshaft side or the camshaft side
It is connected and covers it coaxially with the central gear.
Outermost inner gear and the center gear
And inserted in the annular space between the outermost internal gear
The center gear and the outermost periphery by moving
And a control gear that rotates the internal gear relatively
Wherein the control gear has a substantially cylindrical shape.
Internal helical on the inner and outer surfaces in the radial direction
Equipped with a ply line and an external helical spline
Internal helical spline is formed on the center gear
The external tooth helical spline is fitted to the external tooth helical spline.
Pline is an internal gear helicopter formed on the outermost internal gear.
And the control gear is
The bias of the elastic body loaded inside Partly strange
The control gear is formed of a resin that can be formed.
The external helical spline on the outer surface of
Sometimes, the internal gear helical spline on the inner surface of the control gear
Moves a small distance inward in the radial direction.
Characterized by being biased by the elastic body as described above.
Valve timing adjustment device for an internal combustion engine.