JP2001193426A - Valve system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispose each rocker arm, so as to form an engine in a compact size, in a valve system for an internal combustion engine, where rocker arms disposed on an intake valve side and an exhaust valve side are supported swingably by a pair of parallel rocker shafts, and cam-abutting parts disposed on the rocker arms disposed on the intake valve side and the exhaust valve side are brought into contact with a plurality of cams disposed on a cam shaft arranged downward between both rocker shafts. SOLUTION: An end part of the cam shaft 26 side of the first rocker arm 27 and a swing support part 41a of the second rocker arm 41 are disposed so as to overlap one part thereof in the direction along the axis of the cam shaft 26, and a cutout 49 for avoiding interference of an end part of the cam shaft 26 side of the first rocker arm 27 is disposed on the swing support part 41a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a camshaft in which a rocker arm on an intake valve side and a rocker arm on an exhaust valve side are swingably supported by a pair of rocker shafts parallel to each other, and which is disposed below the rocker shafts. The present invention relates to a valve operating device for an internal combustion engine in which a plurality of cams provided on a rocker arm on an intake valve side and a rocker arm on an exhaust valve side are brought into contact with each other.

[0002]

2. Description of the Related Art Conventionally, such a valve train is already known, for example, from Japanese Patent Publication No. 5-88364.

[0003]

In the above conventional valve train, the camshaft end of one rocker arm and the cylindrical rocking support provided on the other rocker arm to be supported by the rocker shaft. Are arranged at positions separated along the axis of the camshaft in order to avoid mutual interference, and on the layout of each rocker arm,
The distance between the rocker arms in the direction along the axis of the camshaft cannot be reduced, resulting in an increase in the size of the engine.

The present invention has been made in view of the above circumstances, and has as its object to provide a valve train for an internal combustion engine in which respective rocker arms can be arranged so as to enable downsizing of the engine. I do.

[0005]

In order to achieve the above object, an invention according to claim 1 has first and second rocker shafts which are parallel to each other, and an axis which is parallel to the rocker shafts. A camshaft disposed below between the two rocker shafts, and a first cam contact portion that is swingably supported by the first rocker shaft and contacts a first cam provided on the camshaft is provided on the camshaft side. A first rocker arm provided at an end of the camshaft, and a second cam abutment contacting a second cam provided on the camshaft, having a cylindrical swing support portion swingably supported by a second rocker shaft. And a second rocker arm provided at an end on the camshaft side, wherein the camshaft-side end of a first rocker arm and a second rocker are provided. Swing support portion of the over arm is, the disposed so as to partially overlap each other in the direction along the axis of the camshaft,
The swing support portion is provided with a notch for avoiding interference with an end of the first rocker arm on the camshaft side.

According to such a configuration, the first and second rocker arms can be arranged close to each other in the axial direction of the camshaft while avoiding mutual interference by the notch provided in the swing support portion of the second rocker arm. Since it is possible and the distance between both rocker shafts can be reduced, it is possible to contribute to downsizing of the engine.

[0007] The invention according to claim 2 provides the above-described claim 1.
In addition to the configuration of the invention described in the above, an opening that is open to the second rocker shaft side is provided at an end of the first rocker arm on the camshaft side, and the roller that is the first cam contact part is a cam. The first rocker arm is supported by the first rocker arm and accommodated in the opening so as to be rotatable about an axis parallel to the axis of the shaft. A lower extension wall for narrowing a gap between the roller and the lower end of the notch formed in an arc shape facing the outer peripheral surface of the roller is provided integrally with the swing support portion, According to this configuration, the swing support portion and the lower extension wall provided integrally with the swing support portion and the roller,
The oil scattered in the valve operating chamber can be stored and the rollers can be lubricated. In addition, the lower extension wall can contribute to the improvement of the rigidity of the swing support portion. By forming the notch into an arc shape, it is possible to further reduce the rigidity of the swing support portion and further contribute to the downsizing of the engine. it can.

According to a third aspect of the present invention, in addition to the configuration of the first aspect of the present invention, an opening opening toward the second rocker shaft is provided at an end of the first rocker arm on the camshaft side. A roller provided as the first cam contact portion is rotatable about an axis parallel to the axis of the cam shaft, is supported by the first rocker arm, is housed in the opening, and faces the outer peripheral surface of the roller. An upper extending wall extending above the roller and narrowing a distance from the roller toward the front end side is connected to an upper end of the notch formed in an arc shape facing the outer peripheral surface of the roller. An oil ejection hole provided integrally with the swing support portion and connected to an oil passage provided in the second rocker shaft is provided in the swing support portion so as to face the roller. According to formation, the oil from the oil passage in the second rocker shaft it is possible to lubricate the roller by ejected from the oil ejection hole. Moreover, it is possible to prevent the spouted oil from the oil spouting hole from being scattered into the valve operating chamber above the rocker arm by the upper extending wall, and when the breather chamber is provided above the valve operating chamber. Can prevent oil from undesirably entering the breather chamber. Further, by forming the notch into an arc shape, it is possible to further contribute to the downsizing of the engine while suppressing a decrease in rigidity of the swing support portion.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIGS. 1 and 2 show a first embodiment of the present invention. FIG. 1 is a partial longitudinal sectional view of an internal combustion engine, and is a sectional view taken along line 1-1 in FIG. FIG. 2 is a view taken in the direction of arrow 2 in FIG.

The first embodiment will be described with reference to FIGS. 1 and 2. This multi-cylinder internal combustion engine comprises a cylinder block 6 and a cylinder head 8 connected to a top of the cylinder block 6 via a gasket 7. The piston 10 is slidably fitted to a cylinder 9 provided in the cylinder block 6 for each cylinder. The cylinder block 6, the cylinder head 8, and each piston 1
With 0, a combustion chamber 11 is formed for each cylinder.

A pair of intake valve ports 12 facing one side of the ceiling surface of the combustion chamber 11 and two intake valve ports 12
, An intake port 13 that opens in one side (the right side in FIG. 1) of the cylinder head 8 is provided for each cylinder, and a pair of exhaust valve openings facing the other side of the ceiling surface of the combustion chamber 11. And an exhaust port 15 connected to both exhaust valve ports 14 in common and opened on the other side surface (the left side surface in FIG. 1) of the cylinder head 8 are provided for each cylinder.

The stems 16 of the intake valves VI, VI capable of opening and closing the respective intake valve ports 12, respectively, are slidably fitted to guide cylinders 17 provided on the cylinder head 8, and are located above the guide cylinders 17. Valve springs 19, 19 for urging the intake valves VI, VI upward, that is, in the valve closing direction, are provided between the retainers 18, 18 provided at the upper ends of the stems 16 projecting from the cylinder head 8 and the cylinder head 8. Exhaust valve port 14 ...
Exhaust valves VE, VE stems 20 that can be opened and closed respectively ...
Are slidably fitted to guide cylinders 21 provided on the cylinder head 8, and are provided between the cylinder head 8 and retainers 22, 22 provided at the upper end of the stems 20 projecting upward from the guide cylinders 21. Valve springs 23 are provided for urging the exhaust valves VE upward, that is, in the valve closing direction.

The cylinder head 8 is provided with an intake-side rocker shaft 24 as a first rocker shaft and an exhaust-side rocker shaft 25 as a second rocker shaft.
1 and VI, and are supported so as to be disposed in parallel with each other between the upper portions of the exhaust valves VE and VE, and below a middle portion between the two rocker shafts 24 and 25, a crankshaft (not shown) is provided. The camshafts 26, which are linked and connected at a reduction ratio of 1/2, are connected to the two rocker shafts 24,2.
It is arranged to have an axis parallel to 5.

The intake-side rocker shaft 24 has a free portion with respect to an intermediate portion of intake-side drive rocker arms 27 and 28 as first rocker arms individually corresponding to the pair of intake valves VI and VI, and both intake valves VI and VI. And an intermediate portion of a free rocker arm 29 sandwiched between the intake side drive rocker arms 27 and 28 is swingably supported.

The intake-side drive rocker arms 27 and 28 have valve connecting arms 27a and 28a extending from portions supported by the intake-side rocker shaft 24 to the corresponding intake valves VI and VI, respectively. At the ends of 27a and 28a,
Tappet screw 30, which contacts the upper end of intake valve VI, VI,
30 is screwed so that the advance / retreat position can be adjusted. The intake-side drive rocker arms 27 and 28 have cam connecting arms 27b and 28b extending from a portion supported by the intake-side rocker shaft 24 toward the camshaft 26. These cam connecting arms 27b and 28b include: Openings 31 and 32 are provided on the upper and lower sides and on the exhaust side rocker shaft 25 side, respectively, and serve as first cam abutting portions which are in rolling contact with low speed cams 37 and 37 provided on the camshaft 26 as first cams. The rollers 34 and 35 of the openings 31 and 32
And the rollers 34 and 35 are rotatable about an axis parallel to the axis of the camshaft 26 so that the cam connecting arms 27 of the intake side drive rocker arms 27 and 28 can rotate.
b, 28b.

The cylinder head 8 is connected between the intake valves VI and VI.
Is provided with a lost motion mechanism 40. Further, the intake side free rocker arm 29 is connected to the intake side rocker shaft 24.
The arm portion 29a extends from the portion supported by the side to the lost motion mechanism 40 side, and the spring force from the lost motion mechanism 40 acts on the end of the arm portion 29a. Further, the intake-side free rocker arm 29 has a cam connecting arm 29b extending from a portion supported by the intake-side rocker shaft 24 to the camshaft 26 side.
Is provided with an opening 33 which is open to the upper and lower and the exhaust side rocker shaft 25 side, and is rotatably supported by a cam connecting arm portion 29b so as to be in rolling contact with a high speed cam 38 provided on the cam shaft 26. Roller 36 is accommodated in the opening 33.

In addition, the intake side drive rocker arms 27, 28
Interlock switching means (not shown) capable of switching between interlocking and uncoupling of the intake side rocker arms 27 to 29 is provided between the intake side free rocker arm 29 and the interlocking switching means. At times, each of the intake side rocker arms 27 to 29 is caused to swing independently, and during high speed operation of the engine, each of the intake side rocker arms 27 to 29 is caused to swing together. Therefore, during low-speed operation of the engine, both intake-side drive rocker arms 27, 28 swing so as to open and close both intake valves VI, VI with operating characteristics corresponding to the cam profile of the low-speed cams 37, 37, thereby causing the engine to rotate. At the time of high-speed operation, both intake side drive rocker arms 27,
28 swings so as to open and close both intake valves VI, VI with operating characteristics corresponding to the cam profile of the high-speed cam 38.

On the exhaust side rocker shaft 25, intermediate portions of exhaust side rocker arms 41 and 42 as second rocker arms individually corresponding to the pair of exhaust valves VE and VE are swingably supported.

The two exhaust-side rocker arms 41, 42 are formed of swing support portions 41a, 42a which are formed in a cylindrical shape and are swingably supported by the exhaust-side rocker shaft 25, and the swing support portions 41a, 42a. Valve connecting arm portions 41b, 42b extending to the corresponding exhaust valves VE, VE side;
Cam coupling arms 41c and 42c extend from 1a and 42a to the camshaft 26 outside the cam coupling arms 27b and 28b of the intake side drive rocker arms 27 and 28.

At the ends of the valve connecting arms 41b and 42b, tappet screws 4 for abutting on the upper ends of the exhaust valves VE and VE are provided.
3, 43 are screwed together so that the advance / retreat position can be adjusted. The cam connecting arms 41c and 42c are provided with openings 44 and 45 which are open to the upper and lower sides and the intake side rocker shaft 24 side, respectively, and the exhaust side cams 39 and 39 as the second cam provided on the cam shaft 26. Rolling contact second
The rollers 46 and 47 as cam contact portions are formed in the opening 4
The rollers 46, 47 are accommodated in the cam connecting arms 41c, 42c so as to be rotatable around an axis parallel to the axis of the cam shaft 26.

The swing support portions 41a and 42a of the two exhaust side rocker arms 41 and 42 are located at positions spaced apart in the axial direction of the exhaust side rocker shaft 25.
5, which are swingably supported by the two swing support portions 4.
1a, 42a, between the inner ends of the exhaust side rocker shaft 25.
Is provided. Thus, the coil spring 48 prevents the exhaust side rocker arms 41 and 42 from moving in the direction approaching each other.
Further, the outer ends of the swing support portions 41a and 42a are in contact with regulating portions provided on the cylinder head 8, respectively.

The portion of the cam connecting arm 27b of the intake side drive rocker arm 27 including the roller 34 at the end on the cam shaft 26 side is the exhaust side rocker arm 41.
Is arranged so as to overlap with a part of the swing support portion 41a in the direction along the axis of the camshaft 26. The swing support portion 41a includes an end portion of the intake side drive rocker arm 27 on the camshaft 26 side and A notch 49 is provided to avoid interference with the roller 34, and the notch 49 is formed in an arc shape facing the outer peripheral surface of the roller 34.

On the other hand, in the intake side drive rocker arm 28,
A portion of the cam connecting arm 28b on the camshaft 26 side, which is shifted from the roller 35, is disposed so as to overlap with the swing support portion 42a of the exhaust side rocker arm 42 in a direction along the axis of the camshaft 26. The swing support portion 42a is provided with a notch 50 for avoiding interference with the end of the intake side drive rocker arm 28 on the camshaft 26 side, and the notch 50 has a circular shape in the same manner as the notch 49. It is formed in an arc shape.

Next, the operation of the first embodiment will be described. Part of the ends of the intake side drive rocker arms 27 and 28 on the camshaft 26 side and the exhaust side rocker arms 41 and 4 are described.
The two swing support portions 41a and 42a are arranged so as to overlap with each other in a direction along the axis of the camshaft 26, and the swing support portions 41a and 42a are mounted on the intake side drive rocker arms 27 and 28. Notches 49 and 50 are provided to avoid interference with the camshaft 26 end.

Therefore, the intake side drive rocker arm 27,
28 and the exhaust-side rocker arms 41 and 42 can be arranged close to each other in the axial direction of the camshaft 26 while avoiding mutual interference, and the camshafts of the intake-side drive rocker arms 27 and 28 are provided in the notches 49 and 50. The space between the rocker shafts 24 and 25 can be reduced by accommodating a part of the end on the 26 side. As a result, it is possible to contribute to downsizing of the engine. Moreover, since the notches 49 and 50 are formed in an arc shape, it is possible to further contribute to the downsizing of the engine while suppressing a decrease in the rigidity of the swing support portions 41a and 42a.

As another embodiment of the present invention, the roller 3
4 and 35, the intake side drive rocker arms 27 and 28
A cam slipper may be provided at the end on the camshaft 26 side as a cam contact portion.

FIG. 3 shows a second embodiment of the present invention. In one of the two intake-side drive rocker arms 27, 28, the cam connecting arm 27b is rotatably supported at the end of the cam connecting arm 27b on the cam shaft 26 side. The roller 34 is disposed so as to overlap a part of the swing support portion 41 a of the exhaust side rocker arm 41 along the axial direction of the camshaft 26, but faces the outer peripheral surface of the roller 34. A lower extension wall 51 connected to the lower end of the arc-shaped notch 49 provided in the swing support portion 41a is provided integrally with the swing support portion 41a.

The lower extension wall 51 extends below the roller 34 so as to face the outer peripheral surface of the roller 34, and increases the distance between the roller 34 and the tip side, that is, the side away from the exhaust side rocker shaft 25. It is formed in a narrowing shape.

According to the second embodiment, the swing support portion 41a of the exhaust side rocker arm 41 and the swing support portion 41
The oil scattered in the valve operating chamber can be stored between the lower extension wall 51 provided integrally with the roller a and the roller 34 of the intake side drive rocker arm 27, and the roller 34 is lubricated with the oil. Can be.

Further, the lower extension wall 51 is provided with the swing support portion 41a.
The rigidity of the swing support portion 51a is also improved by being provided integrally with the swing support portion 51a.

4 and 5 show a third embodiment of the present invention. FIG. 4 is a partial longitudinal sectional view of the internal combustion engine corresponding to FIG. 1, and FIG. 5 is a sectional view taken along line 5-5 in FIG. FIG.

Swing support 41 of exhaust side rocker arm 41
a shows the rollers 3 in the intake side drive rocker arm 27;
The upper extension wall 52 which extends upward from the roller 34 in opposition to the outer peripheral surface of the roller 4 and narrows the distance from the roller 34 toward the front end side is connected to the upper end of the arc-shaped notch 49. And are provided integrally.

Further, as clearly shown in FIG.
An oil ejection hole 54 is provided in the swing support portion 41a so as to face the opening. The exhaust-side rocker shaft 25 is provided with an oil passage 53 communicating with an oil supply source (not shown) and a communication passage 55 connecting the oil ejection hole 54 and the oil passage 53.

According to the third embodiment, the oil supplied from the oil passage 53 in the exhaust-side rocker shaft 25 through the communication passage 55 is ejected from the oil ejection hole 54, so that the roller of the intake-side drive rocker arm 27 is rotated. 34 can be lubricated. In addition, it is possible to prevent the spouted oil from the oil spouting hole 54 from being scattered into the valve operating chamber above the rocker arms 27 to 28, 41, and 42 by the upper extension wall 52. In the case where the breather chamber is provided, oil can be prevented from undesirably entering the breather chamber.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the appended claims. It is possible.

[0037]

As described above, according to the first aspect of the present invention, the first and second rocker arms are arranged close to each other in the axial direction of the cam shaft while avoiding mutual interference, and the distance between the two rocker shafts is reduced. It is possible to reduce the size, which can contribute to downsizing of the engine.

According to the second aspect of the present invention, it is possible to further contribute to the downsizing of the engine while contributing to the improvement of the rigidity of the swing support portion, and further, the lubrication of the roller by the oil scattered in the valve operating chamber. It becomes possible.

Further, according to the third aspect of the present invention, it is possible to further contribute to the downsizing of the engine while suppressing a decrease in the rigidity of the swing support portion, and to lubricate the rollers with oil ejected from the oil ejection holes. It is possible to prevent the spouted oil from being scattered and escaping into the valve operating chamber, and when the breather chamber is provided above the valve operating chamber, the oil is supplied to the breather chamber. Can be prevented from entering undesirably.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional view of an internal combustion engine according to a first embodiment, which is a sectional view taken along line 1-1 of FIG. 2;

FIG. 2 is a view taken in the direction of arrow 2 in FIG. 1;

FIG. 3 is a partial longitudinal sectional view of an internal combustion engine corresponding to FIG. 1 of a second embodiment.

FIG. 4 is a partial longitudinal sectional view of an internal combustion engine corresponding to FIG. 1 of a third embodiment.

FIG. 5 is a sectional view taken along line 5-5 in FIG. 4;

[Explanation of symbols]

Reference numeral 24: intake side rocker shaft as first rocker shaft 25: exhaust side rocker shaft as second rocker shaft 26: cam shaft 27, 28 ... intake side drive rocker arm 31 as first rocker arm 31 ... Opening parts 34, 35 ... Roller 37 as first cam contact part 37 ... Low speed cam 39 as first cam 39 ... Exhaust side cam 41, 42 as second cam Exhaust-side rocker arms 41a, 42a as second rocker arms ... swing support portions 46, 47 ... rollers 49, 50 as notch portions for second cam 49 ... notch 51 ... lower extension wall 52・ ・ ・ Top extension wall 53 ・ ・ ・ Oil passage 54 ・ ・ ・ Oil outlet

Claims (3)

[Claims] A first and a second rocker shaft (24, 25) parallel to each other and their rocker shafts (2, 25).
4 and 25), and both rocker shafts (2
The camshaft (26) arranged below between (4, 25)
And a first rocker shaft (24) that is swingably supported by the first rocker shaft (24) and that is provided on the camshaft (26).
First cam contact portions (34, 35) contacting cams (37)
Is provided at the end on the camshaft (26) side.
A second cam provided on the camshaft (26) having a rocker arm (27, 28) and a cylindrical rocking support portion (41a, 41b) that is rockably supported by a second rocker shaft (25). (39) Second contact
The cam abutting portion (46, 47) is provided on the camshaft (26).
Second rocker arms (41, 42) provided at the side end
In the valve train for an internal combustion engine, the end portions of the first rocker arms (27, 28) on the camshaft (26) side and the swing support portions (41a, 42a) of the second rocker arms (41, 42) are provided. The camshaft (26) of the first rocker arm (27, 28) is disposed so as to partially overlap in the direction along the axis of the camshaft (26). A valve notch (49, 50) for avoiding interference with the end on the side of the internal combustion engine. 2. A second rocker shaft (2) is provided at an end of the first rocker arm (27) on the camshaft (26) side.
5) An opening (31) opened to the side is provided,
The roller (34), which is a cam contact portion, is moved by the camshaft (2).
6) The rotation about an axis parallel to the axis of 6) is enabled and the first
The opening (31) supported by the rocker arm (27)
And a lower extension wall (51) extending downwardly of the roller (34) facing the outer peripheral surface of the roller (34) and narrowing the gap with the roller (34) toward the distal end side. The swing support portion (41a) is provided integrally with the lower end of the notch (49) formed in an arc shape facing the outer peripheral surface of the roller (34). 2. The valve train for an internal combustion engine according to claim 1. 3. A camshaft (26) side end of the first rocker arm (27) has a second rocker shaft (2).
5) An opening (31) opened to the side is provided,
The roller (34), which is a cam contact portion, is moved by the camshaft (2).
6) The rotation about an axis parallel to the axis of 6) is enabled and the first
The opening (31) supported by the rocker arm (27)
And an upper extension wall (52) that extends above the roller (34) in opposition to the outer peripheral surface of the roller (34) and narrows the distance from the roller (34) toward the distal end. A second portion is provided integrally with the swing support portion (41a) so as to be continuous with an upper end of the notch (49) formed in an arc shape facing the outer peripheral surface of the roller (34);
An oil ejection hole (54) connected to an oil passage (53) provided in the rocker shaft (25) is provided in the swing support portion (41a) so as to face the roller (34). Item 2. A valve train for an internal combustion engine according to Item 1.