JPH10141025A - Valve system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress oscillation of a cam shaft arranged at a valve timing varying mechanism and in its turn, suppress the generation of noise due to defective engagement between gears for drive coupling, in a valve system for an internal combustion engine. SOLUTION: In a valve system for an internal combustion engine, since constitution thereof is simplified and the whole of an engine is formed in a compact manner, a cam shaft 12 on the side where a VVT mechanism 11 is arranged is structured in a manner to be supported in a cantilever state by the upper surface of a cylinder head 17 and a bearing part 17a. In this case, the VVT mechanism 11 having high weight is arranged on the cam shaft 12 between a gear 22 and a bearing part 17a and this constitution suppresses whirling of the cam shaft 12 and in its turn, suppresses the generation of noise due to defective engagement between the gears 22 and 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve gear for an internal combustion engine having a valve timing changing mechanism for changing the opening / closing timing of intake / exhaust valves provided in a cylinder of the internal combustion engine during operation of the engine. is there.

[0002]

2. Description of the Related Art Conventionally, as a valve gear having a valve timing changing mechanism for changing the opening / closing timing of intake / exhaust valves provided in a cylinder of an internal combustion engine, for example, an apparatus described in JP-A-8-121122 is known. It has been known. Such a valve train, including the device described in this publication, is generally configured as illustrated in FIGS.

That is, as shown in FIG. 8, this valve train has an intake-side camshaft 112 and an exhaust-side camshaft 123 which are rotatably supported in parallel with the upper part of a cylinder head of an internal combustion engine. You. The cam 20 is provided on the intake camshaft 112, and the camshaft 1 is provided on the exhaust camshaft 1.
23 are provided with cams 25, respectively.
, 25, the intake valve and the exhaust valve (not shown) provided in each cylinder of the engine are opened and closed, respectively.

The journal of the intake camshaft 112 is rotatably supported by the upper surface of the cylinder head and the bearing 17a, and the exhaust camshaft 123 is similarly journaled by the upper surface of the cylinder head and the bearing 17b. The part is rotatably supported.

On the other hand, a cam pulley 26 is fixed to the base end side (the right side in FIG. 8) of the exhaust side camshaft 123, and a timing belt 27 is mounted on the pulley 26. The timing belt 27 is mounted on a crank pulley (not shown) attached to a crankshaft (not shown) serving as an engine output shaft.

[0006] A drive gear 124 is fixed to the tip side (left side in FIG. 8) of the exhaust side camshaft 123. The drive gear 124 is a driven gear 1 provided on the tip end side of the intake camshaft 112.
The driven gear 122 and the drive gear 124 are integrally rotated by this connection. That is, when the operation of the internal combustion engine is started, the cam pulley 26
The rotational driving force of the crankshaft is transmitted via the drive gear 124 and the rotational driving force is transmitted through the drive gear 124 and the driven gear 122.
Is transmitted to

[0007] Further, on the tip side (left side in FIG. 8) of the intake side camshaft 112, there is provided the driven gear 122 and a valve timing changing mechanism 111 integrally assembled with the camshaft 112. FIG.
7 shows a schematic structure of the valve timing changing mechanism 111.

That is, as shown in FIG. 6, the valve timing changing mechanism 111 is roughly housed in a housing 128 integrally connected to the driven gear 122 by a bolt 53, and is rotatably accommodated in the housing 128. , And a vane 129 integrally connected to the tip end of the intake camshaft 112 by a bolt 54. The relative rotational phase between the housing 128 and the vane 129 is changed based on the hydraulic control, so that the relative rotational phase between the intake camshaft 112 and the driven gear 122 is changed. The relative rotation phase with the side camshaft 123 (that is, the crankshaft) is changed.

FIG. 7 is a sectional view taken along the line 7-7 in FIG. 6. In the valve timing changing mechanism 111, as shown in FIG. Hydraulic chambers 113 and 114 are defined by the respective pressure receiving portions 132 of the vanes 129. The vane 129 is connected to each of the hydraulic chambers 113,
In accordance with the magnitude of the hydraulic pressure supplied to 114, the shaft 114 rotates rightward or leftward about its axis.

Here, when the intake camshaft is rotating clockwise as shown in FIG.
When a high oil pressure is supplied to the thirteenth side and the vane 129 rotates rightward, the rotational phase of the intake side camshaft 112 to which the vane 129 is fixed is advanced with respect to the driven gear 122, and the opening and closing timing of the intake side valve is adjusted. Is advanced (advance angle control).

On the other hand, when it is assumed that the intake camshaft 112 is rotating rightward, the hydraulic chamber 1
When a high oil pressure is supplied to the 14 side and the vane 129 rotates in the reverse direction (left direction), the rotation phase of the intake camshaft 112 is delayed with respect to the driven gear 122, and the opening / closing timing of the intake valve is delayed. (Retard control).

The valve timing changing mechanism 11
For FIG. 1, FIG. 6 is shown as a cross-sectional view along line 6-6 of FIG. 6 and 7, oil holes or oil grooves 140, 141, 142, 143, 144 are shown.
Constitutes an advanced hydraulic passage P1 for supplying hydraulic pressure to the hydraulic chamber 113, and includes oil holes or oil grooves 145, 14
6, 147, 148, 149, 150, and 151 are retard-side hydraulic passages P for supplying hydraulic pressure to the hydraulic chamber 114.
Constituting No. 2.

[0013]

In order to simplify the structure of such a valve train or to make the engine as a whole compact, as shown in FIG. 6 or FIG. In many cases, the camshaft on which the change mechanism 111 is provided has a cantilever support structure. Therefore, in the intake-side camshaft 112 provided with the heaviest valve timing changing mechanism 111 at the forefront (left side in FIG. 6), the whirling amount increases, and the rotation becomes non-uniform. Things are inevitable. As a result, the driven gear 12
The center pitch between the drive gear 2 and the drive gear 124 is displaced, and noise due to poor meshing between the two gears 122 and 124 may occur.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a valve train for an internal combustion engine.
An object of the present invention is to suppress whirling of a camshaft provided with a valve timing changing mechanism, and further suppress occurrence of noise due to the above-described poor gear engagement.

[0015]

SUMMARY OF THE INVENTION In order to achieve the above object, an invention according to claim 1 is provided by a first camshaft rotatably supported by a bearing and having a first gear at one end, and a bearing. A second camshaft rotatably supported and having at one end a second gear meshed with the first gear; and a second camshaft disposed on at least one of the first and second camshafts. A valve timing change mechanism for changing a rotation phase of a camshaft and a gear provided on the camshaft, wherein the valve timing change mechanism is provided at one end of a camshaft in which the valve timing change mechanism is disposed. The gist is to be cantilevered inside the corresponding gear.

According to the first aspect of the invention, the valve timing changing mechanism having a large weight is provided with the first or second valve timing changing mechanism.
Is provided between the first gear and the bearing at one end of the camshaft, thereby suppressing the whirling of the camshaft provided with the valve timing changing mechanism, and eventually resulting from poor meshing of the first and second gears. Generation of noise can be suppressed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 to 3, a valve timing change mechanism (hereinafter, referred to as a "VVT mechanism") for changing the opening / closing timing of an intake valve provided in an engine as an internal combustion engine will be described below. An embodiment embodied in a valve gear having the following will be described.

First, an outline of the valve gear according to the embodiment will be described with reference to FIG. As shown in FIG. 3, the valve gear of this embodiment also has an intake camshaft 12 and an exhaust gas, which are supported in a freely rotatable manner in parallel to the upper part of the cylinder head of the engine, similarly to the conventional device. It has a side camshaft 23. A cam 20 is provided on the intake side camshaft 12, and a cam 25 is provided on the exhaust side camshaft 23, respectively.
As the cams 20 and 25 rotate with the rotation of the camshafts 12 and 23, intake valves and exhaust valves (not shown) provided in each cylinder of the engine are opened and closed, respectively.

The journal of the intake camshaft 12 is rotatably supported by an upper surface of a cylinder head and a bearing 17a, and the exhaust camshaft 23 is similarly journaled by an upper surface of the cylinder head and a bearing 17b. The point that the part is rotatably supported is the same as in the case of the above-described conventional valve train.

On the other hand, a cam pulley 26 is fixed to the base end side (the right side in FIG. 3) of the exhaust side camshaft 23, and a timing belt 27 is mounted on the pulley 26. The timing belt 27 is mounted on a crank pulley (not shown) attached to a crankshaft (not shown) serving as an engine output shaft. Such a structure is the same as that of the conventional device.

A drive gear 24 is fixed to the distal end side (left side in FIG. 3) of the exhaust side camshaft 23. The drive gear 24 is meshed and connected to a driven gear 22 provided on the same front end side of the intake camshaft 12.
And the drive gear 24 are integrally rotated. That is, when the operation of the internal combustion engine is started, the rotational driving force of the crankshaft is transmitted to the exhaust-side camshaft 23 via the cam pulley 26, and the rotational driving force is transmitted to the drive gear 24 and the driven gear 2.
2 to the intake camshaft 12.

Also in the apparatus of the embodiment, the driven gear 22 and the VVT integrally mounted on the camshaft 12 are attached to the intake-side camshaft 12.
Although the mechanism 11 is provided, especially in the case of the device of the embodiment, the VVT mechanism 11 is located inside the driven gear 22, that is, at the most distal end with the driven gear 22, as shown in FIG. It is provided between the bearing part (17a).

Hereinafter, referring to FIG. 1 and FIG.
The structure of the T mechanism 11 and its peripheral structure will be described. FIG. 1 shows a VVT mechanism 11, a driven gear 22 provided with the VVT mechanism 11, and an intake camshaft 1.
2 shows a cross-sectional structure.

As described above, the intake side camshaft 12
It is rotatably supported by the upper end surface of the cylinder head 17 and the bearing 17a. Further, in the camshaft 12 on the intake side, an annular member 21 is provided at a tip portion thereof, and the driven gear 22 is fitted on an outer periphery of the annular member 21. In addition, this annular member 21
While being inserted through the camshaft 12,
Accordingly, the movement of the camshaft 12 in the axial direction is restricted.

On the other hand, the VVT mechanism 11 also basically has a housing 28 integrally connected to the driven gear 22 by bolts 52, and is rotatably housed in the housing 28, and has an appropriate fitting (not shown). A vane 29 is integrally connected to the intake camshaft 12 through a joint mechanism.

Here, the housing 28 has its cover 3
Both of them have a bottomed cylindrical shape, and the base side surface of the vane 29 slides on the side surface of the cover 30 serving as the bottom surface with a predetermined clearance. The housing 28 and the driven gear 22 are connected to each other by the bolts 52 to form the intake-side camshaft 1.
2 can be integrally rotated with the rotation axis.

The vane 29 rotates inside the housing 28 together with the camshaft 12 by hydraulic control. In the present embodiment, the vane 29 is rotated.
9 is provided with a locking pin 43 so that the relative rotation between the vane 29 and the housing 28 is prohibited by the locking pin 43 when the hydraulic control is not performed, such as when starting the engine. .

The locking pin 43 and its peripheral structure will be described below. As shown in FIG. 1, a pin hole 42 having a circular cross section extending in the axial direction of the intake camshaft 12 is formed in a part of the vane 29. This pin hole 42
Has a step portion 42a in the middle thereof,
The portion on the tip side (left side in FIG. 1) from 2a has an enlarged diameter. The locking pin 43 has a substantially cylindrical shape with a bottom, and an enlarged-diameter portion 43a is formed on the outer peripheral side surface on the distal end side. The locking pin 43 has an enlarged diameter portion 43a on the outer peripheral side surface.
Is in sliding contact with the inner peripheral side surface of the pin hole 42 whose diameter has been increased,
The intake camshaft 12 is movable in the axial direction.

An inner hole 45 extending in the axial direction is formed inside the locking pin 43, and a spring 46 is provided in the hole 45. The locking pin 43 is urged by the spring 46 toward the base end of the intake camshaft 12. A back pressure chamber 42b is formed by an inner peripheral wall surface of the inner hole 45, an inner peripheral side surface of the pin hole 42, and a space covered by a bottom 42c of the pin hole 42.

On the other hand, the engagement of the locking pin 43 is defined by an annular space surrounded by the inner peripheral side surface of the enlarged diameter portion of the pin hole 42 and the enlarged diameter portion 43a on the outer peripheral side surface of the locking pin 43. A hydraulic chamber 44 for releasing the stop state is formed. The hydraulic chamber 44 is provided with a VVT as described later.
The oil is communicated with one of the retard hydraulic chambers of the mechanism 11, and a part of the oil in the retard hydraulic chamber moves and can be supplied into the hydraulic chamber 44.

An engaging hole 41 is formed at a position facing the base end surface of the engaging pin 43 on the front end side surface of the cover 30 constituting a part of the housing 28.
The relative rotation between the vane 29 and the housing 28, that is, the driven gear 22, is restricted by the base end portion of the locking pin 43 being fitted and locked in the locking hole 41. As a result, the intake camshaft 12 rotates integrally with the driven gear 22. And by providing such a locking pin 43, when starting the engine, etc.
The occurrence of abnormal noise and the like due to the unstable operation of the VVT mechanism 11 is also avoided.

FIG. 2 is a sectional view taken along line 2-2 of FIG. 1 (FIG. 1 corresponds to a sectional view taken along line 1-1 of FIG. 2). Next, the structure of the housing 28 and the vane 29 will be described in further detail with reference to FIG.

As shown in FIG. 2, a vane 29 of the VVT mechanism 11 is formed in an annular shape located at the center of the vane 29 and is fixed to the intake-side camshaft 12 by a fixing portion 31.
And three pressure receiving portions 3 formed on the outer peripheral portion of the fixed portion 31.
2 is provided. Each of the pressure receiving portions 32 radially extends in the radial direction of the intake-side camshaft 12, and has a substantially Y-shape as a whole.

On the other hand, inside the housing 28, three projecting portions 33 projecting toward the axis of the camshaft 12 at predetermined intervals in the circumferential direction of the intake-side camshaft 12.
Are formed. The inner peripheral surface of each of the projections 33 comes into sliding contact with the outer peripheral surface of the fixed portion 31. A groove 34 is formed between the projections 33, and the pressure receiving portions 32 are arranged in the grooves 34. The outer peripheral surface of each pressure receiving portion 32 comes into sliding contact with the inner peripheral surface of the housing 28. As described above, three spaces surrounded by the side surfaces of the cover 30 and the fixing portion 31 and the inner peripheral wall of each groove portion 34 are formed inside the housing 28. Furthermore, each space is further divided into two pressure chambers by each pressure receiving portion 32 arranged in the groove portion 34. The pressure chamber formed in the same direction as the rotation direction of the intake side camshaft 12 is a retard side hydraulic chamber 14, and the pressure chamber formed in the direction opposite to the rotation direction is an advance angle The side hydraulic chamber 13 is provided.

The inside of each of the hydraulic chambers 13 and 14 is supplied with oil through hydraulic passages P1 and P2, which will be described later. Is rotatable bidirectionally around the axis of the intake-side camshaft 12 in accordance with the magnitude of the hydraulic pressure.

Here, when the vane 29 is rotated in the same direction as the rotation direction of the intake side camshaft 12 (hereinafter, this rotation direction is referred to as “advanced rotation direction”), the vane 29 is fixed to the intake side. The rotation phase of the camshaft 12 is advanced with respect to the driven gear 22, and the opening / closing timing of the intake valve (hereinafter, referred to as "valve timing") is advanced.

On the other hand, when the vane 29 rotates in the direction opposite to the rotation direction of the intake-side camshaft 12 (hereinafter, this rotation direction is referred to as “retarded rotation direction”), the rotation of the intake-side camshaft 12 The phase is delayed with respect to the driven gear 22, and the valve timing is delayed.

Next, with reference to FIGS. 1 and 2, the advance side and the retard side which constitute a hydraulic passage for supplying oil to the advance side hydraulic chamber 13 and the retard side hydraulic chamber 14 will be described. Hydraulic passage P
, P2, an oil pump 15 for supplying oil through the hydraulic passages P1 and P2, and the hydraulic passage P
An oil control valve (hereinafter, referred to as “OCV”) 16 provided in the middle of P1, P2 will be described.

An advance-side head oil passage and a retard-side head oil passage (not shown) are formed inside the cylinder head 17, and each head oil passage is provided with an oil through an OCV 16, an oil pump 15, and an oil strainer 56. It can be connected to the pan 57. When the oil pump 15 is driven with the operation of the engine, the oil stored in the oil pan 57 is discharged through the oil strainer 56 through the oil pump 15.
While being pumped from the pump 15 and discharged. The discharged oil is selectively pumped to each of the head oil passages by the OCV 16.

The upper end portion of the cylinder head 17 and the most advanced bearing portion (17a) of the intake side camshaft 12 correspond to the opening positions of the head oil passages.
Oil grooves 58, 59 extending in the circumferential direction of the intake camshaft journal 12a are surrounded by the oil grooves 58, 59, respectively.

A retard-side shaft oil passage 61 extending in the axial direction is formed inside the intake-side camshaft 12. The distal end side of the retard side shaft oil passage 61 is closed by a shaft oil passage cover 71. Further, inside the camshaft 12, three retardation-side oil passages 62 extending from the retardation-side shaft oil passages 61 to the respective retard-side hydraulic chambers 14 are formed. Square shaft oil passage 6
1 and the retard side hydraulic chamber 14 communicate with each other.

A retard-side oil hole 60 extending in the radial direction of the intake-side camshaft 12 is formed inside the journal 12a. The retard side shaft oil passage 61 is provided with the retard side oil hole 6.
0, the oil groove 59 and the retard oil hole 60 are provided in the retard shaft oil passage 61.
The oil in the retard-side head oil passage is supplied via the.

Further, an advanced shaft oil passage 64 extending in the axial direction is formed inside the intake camshaft 12. The leading end side of the advance shaft oil passage 64 is closed by a shaft oil passage cover 72. The advance shaft oil passage 6 is provided inside the camshaft 12.
4 to each advance-side hydraulic chamber 13
The oil passage 65 communicates the advance shaft oil passage 64 with the advance hydraulic chamber 13.

An advance-side oil hole 63 extending in the radial direction of the intake-side camshaft 12 is formed inside the journal 12a. The advance shaft oil passage 64 is provided with the advance oil hole 6.
3 communicates with the other oil groove 58, and an oil groove 58 and an advance oil hole 63 are provided in the advance shaft oil passage 64.
The oil in the advance-side head oil passage is supplied via the.

In the same VVT mechanism 11,
The advance-side oil passage P1, the oil groove 58, the advance-side oil hole 63, the advance-side shaft oil passage 64, and the advance-side oil passage 65 constitute an advance-side hydraulic passage P1. The retard side hydraulic passage P2 is constituted by the passage, the oil groove 59, the retard side oil hole 60, the retard side shaft oil passage 61, and the retard side oil passage 62. In this embodiment, oil is supplied from the oil pump 15 into the hydraulic chambers 13 and 14 by switching the communication state between the hydraulic passages P1 and P2 and the oil pump 15 and the oil pan 57 by the OCV 16. Alternatively, the oil is discharged from the hydraulic chambers 13 and 14 and returned to the oil pan 57. In addition, OCV
Reference numeral 16 denotes a well-known hydraulic control valve for controlling the hydraulic pressure supplied to the advance-side and retard-side hydraulic chambers 13 and 14 by duty control of the opening degree through a control device (not shown).

A hydraulic chamber 44 (FIG. 1) formed for releasing the locking state of the locking pin 43 is provided in FIG.
As shown in the figure, the vane 29 communicates with one of the retard hydraulic chambers 14 by a pressure oil passage 66 formed on the side of the pressure receiving portion 32. Some of the oil can be supplied.

As shown in FIG. 1, a groove 3 having a rectangular cross section is formed on the outer peripheral portion of each pressure receiving portion 32 of the vane 29.
A seal member 36 urged toward the outer periphery by a leaf spring 37 is provided in the groove 35. The seal member 36 seals between the outer peripheral surface of the pressure receiving portion 32 and the inner peripheral surface of the housing 28,
The movement of oil between the advance hydraulic chamber 13 and the retard hydraulic chamber 14 is restricted.

The operation and effect of the present embodiment configured as described above will be summarized below. (A) In the present embodiment, the intake side camshaft 12 is rotatably supported by the upper end surface of the cylinder head 17 and the bearing 17a. It is provided between the bearing (17a) at the forefront.

Therefore, according to the present embodiment, the following effects can be obtained as compared with a conventional valve train in which the VVT mechanism 11 is provided outside the driven gear 22, that is, on the tip side of the driven gear 22.

First, the heavy VVT mechanism 11 is
By providing the inner side of the driven gear 22, that is, on the side near the support position of the intake-side camshaft 12, the amount of whirling of the intake-side camshaft 12 can be reduced. Therefore, whirling of the driven gear 22 during rotation is reduced, and generation of noise due to poor meshing between the driven gear 22 and the drive gear 24 is also suppressed.

Second, wear between the driven gear 22 and the drive gear 24 due to collision between the gears 22 and 24 is also reduced. Therefore, the life of both gears 22 and 24 naturally becomes longer.

(B) In addition to the above configuration, in this embodiment, the rotation of the vane 29 is restricted by the locking pin 43 at the time of starting the operation of the engine or the like. Therefore, the operation of the VVT mechanism 11 does not become unstable immediately after the start of the engine, and abnormal noise or the like generated due to the unstable operation of the VVT mechanism 11 is also preferably avoided.

(C) In this embodiment, the VVT mechanism 1
In 1, the outer peripheral surface of each pressure receiving portion of the vane 29 and the inner peripheral surface of the housing 28 are sealed by a seal member 36. For this reason, the movement of oil between the advance side hydraulic chamber 13 and the retard side hydraulic chamber 14 is also suitably restricted, and more stable valve timing control as a valve train is realized.

The embodiment described above can be implemented by changing the configuration as follows. (1) In the above embodiment, the hydraulic chambers are provided on both sides of the pressure receiving portion 32 in the rotation direction of the vane 29.
A configuration in which the hydraulic chamber is provided only on one side can be changed.

This includes, for example, the retard side hydraulic chamber 14,
The retard side hydraulic passage P for supplying oil to the hydraulic chamber 14
2. The lock pin 43 and its peripheral structure are omitted, and the vane 2 is installed in a corresponding space of the retard side hydraulic chamber 14.
An urging member, such as a coil spring or a leaf spring, for urging 9 in the direction of retarded rotation is provided.

When the valve timing is advanced, the vane 29 is rotated in the advance rotation direction by the hydraulic pressure in the advance hydraulic chamber 13. Conversely, when delaying the valve timing, the supply of oil into the advance side hydraulic chamber 13 is stopped, and the urging member rotates the vane 29 in the retard rotation direction.

(2) In the above embodiment, a groove 35 having a rectangular cross section is formed in the outer peripheral portion of each pressure receiving portion 32 of the vane 29, and a sealing member 36 is disposed in the groove 35, and this is formed by a plate. The spring 37 urges the outer periphery of the vane 29.
Alternatively, the pressure receiving portion 32 and the fixing portion 31 may be provided on both sides.

(3) In the above-described embodiment, the pin hole 42 is formed in one of the pressure receiving portions 32 of the vane 29, and the locking hole 41 of the locking pin 43 is formed in the front end side surface of the cover 30 facing the pin hole 42.
Was formed. Instead, as shown in FIG. 4, a pin hole 42 'is formed in one of the pressure receiving portions 32 so that the driven gear 2
The locking hole 41 ′ of the locking pin 43 may be formed on the side surface on the base end side of 2. Even with such a configuration, the same operation and effect as those of the above embodiment can be obtained.

(4) In the above embodiment, the housing 28
The valve timing was changed by integrally rotating the vane 29 and the driven gear 22, and the vane 29 and the driven gear 22 were integrally rotated. The valve timing was changed by integrally rotating the housing 28 and the driven cam 22 and the vane 29 and the driven gear 22 respectively. It is good also as a structure which changes timing. Also in this case, the VVT mechanism 11 is moved inside the driven gear 22, that is, the driven gear 22.
And the bearing part (17
By providing the gap between a and a), the whirling of the camshaft 12 can be suppressed, and the generation of noise due to poor meshing between the drive gear 24 and the driven gear 22 can be suppressed.

(5) In the above embodiment, the case where the VVT mechanism 11 is provided on the intake side camshaft 12 has been described. However, as shown in FIG.
A configuration in which the VT mechanism 11 is provided may be employed. Also in this case, the VVT mechanism 11 is provided inside the drive gear 24, that is, between the drive gear 24 and the bearing portion (17 b) on the most front side of the exhaust-side camshaft 23, so that the cam shaft 23 whirls , And the generation of noise due to poor meshing between the drive gear 24 and the driven gear 22 can be suppressed.

(6) Not only the structure for changing the opening / closing timing of one of the intake side valve or the exhaust side valve but also the VVT
The mechanism 11 may be provided on both the intake side camshaft 12 and the exhaust side camshaft 23 to change the valve opening / closing timing of both the intake valve and the exhaust valve. Also in this case, the VVT mechanism 11 is connected to the inside of the driven gear 22 and the drive gear 24, that is, between the driven gear 22 and the most advanced bearing portion (17a) of the intake camshaft 12, and between the drive gear 24 and the exhaust cam. By providing the shaft between the shaft 23 and the bearing (17b) on the most front side, the whirling of the camshafts 12 and 23 is suppressed, and furthermore, the generation of noise due to poor meshing between the drive gear 24 and the driven gear 22 is suppressed. can do.

(7) In the above embodiment, three vanes 29
Although the configuration in which one pressure receiving portion 32 is formed is adopted, a configuration having two or less or four or more pressure receiving portions 32 may be employed. When the number of the pressure receiving portions 32 is smaller than in the above-described embodiment, the configuration of each of the hydraulic passages P1 and P2 can be simplified. A rotating torque can be applied.

(8) In the above embodiment, the VVT mechanism 11 having a configuration in which the cam pulley 26 is changed to a timing sprocket and the timing belt 27 is changed to a timing chain may be adopted.

(9) In each of the above embodiments, the protruding portion 33 of the housing 28 is formed in a fan-shaped solid. However, in order to reduce the weight, the protruding portion 33 is formed by hollowing out the inside of the fan-shaped solid. May be.

(10) The VVT mechanism is not limited to the vane type but may be a ring gear type.

[0066]

According to the first aspect of the present invention, there is provided a valve timing changing mechanism which is cantilevered with the first or second gear at a bearing at one end of the camshaft provided with the valve timing changing mechanism. In a valve operating device for an internal combustion engine, a heavy valve timing changing mechanism is provided between the first or second gear and a bearing at one end of the camshaft, so that the camshaft provided with the valve timing changing mechanism is provided. Of the first gear and the second gear can be suppressed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a valve train according to the present invention.

FIG. 2 is a sectional view taken along the line 2-2 in FIG. 1;

FIG. 3 is an exemplary plan view showing the planar structure of the valve gear according to the embodiment;

FIG. 4 is a partial cross-sectional view showing another configuration example of the VVT mechanism.

FIG. 5 is a plan view showing another configuration example of the valve train according to the present invention.

FIG. 6 is a partial sectional view showing a configuration example of a conventional valve train.

FIG. 7 is a sectional view taken along the line 7-7 in FIG. 6;

FIG. 8 is a plan view showing a planar structure of a conventional valve train.

[Explanation of symbols]

11 VVT mechanism, 12 intake camshaft, 13
Advance side hydraulic chamber, 14 ... retard side hydraulic chamber, 15 ... oil pump, 16 ... OCV, 17 ... cylinder head, 17a, 1
7b: Bearing, 22: Driven gear, 24: Drive gear, 28: Housing, 29: Vane, 30: Housing cover, 57: Oil pan, P1: Advance hydraulic pressure passage,
P2: retard side hydraulic passage.

Claims (1)

[Claims] 1. A first camshaft rotatably supported by a bearing and having a first gear at one end, and a second camshaft rotatably supported by a bearing and meshed at one end with the first gear. A second camshaft having gears;
A valve timing changing mechanism disposed on at least one of the first and second camshafts, the valve timing changing mechanism for changing a rotational phase of the camshaft and a gear provided on the camshaft; The valve gear of an internal combustion engine according to any one of claims 1 to 3, wherein the valve timing changing mechanism is provided at one end of a camshaft where the mechanism is disposed and cantilevered inside a corresponding gear.