JP2001193420A - Valve system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispose a cam shaft in the vicinity of a rocker arm, and form the whole of an engine into a compact size, in a valve system for an internal combustion engine wherein a cam-abutting part disposed between both support walls is arranged on the rocker arm having a swing support part swingably supported at an arm support part disposed on a cylinder head and a pair of support walls arranged extendedly from the swing support part, and a cam shaft provided with a cam which is brought into contact with the cam abutting part is disposed on either one upper or lower side of the rocker arm. SOLUTION: A recessed part 50 is formed on the cam shaft 38 side between both support walls 34b of a rocker arm 34, and a part of the cam 46 which is brought into contact with the cam-abutting part 56 which is disposed on a center part of the recessed part 50 is housed in the recessed part 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rocker arm having a rocking support portion pivotally supported by an arm support portion provided on a cylinder head and a pair of support walls extending from the rocking support portion. A valve abutting portion disposed between the two support walls, and a camshaft having a cam contacting the cam abutting portion is disposed on one of upper and lower sides of the rocker arm. Related to the device.

[0002]

2. Description of the Related Art Conventionally, such a valve train is already known, for example, from Japanese Utility Model Publication No. 6-10103.

[0003]

However, in the above-mentioned conventional valve train, the cam contact portion protrudes above the rocker arm, and the position of the cam shaft with respect to the rocker arm is restricted. It cannot be arranged, and the degree of freedom in the layout of the rocker arm and the camshaft is small, leading to an increase in the size of the entire engine.

The present invention has been made in view of the above circumstances, and provides a valve train for an internal combustion engine that enables a camshaft to be disposed closer to a rocker arm and that allows the entire engine to be downsized. The purpose is to do.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a swing support portion swingably supported by an arm support portion provided on a cylinder head, and the swing support portion. A rocker arm having a pair of support walls extending from the support portion is provided with a cam contact portion disposed between the two support walls, and one of upper and lower sides of the rocker arm contacts the cam contact portion. In a valve train for an internal combustion engine in which a camshaft having a cam is disposed, a concave portion is formed on the camshaft side between the two support walls of the rocker arm, and the cam contact portion disposed in the center of the concave portion A part of the contacting cam is housed in the recess.

According to such a configuration, the camshaft can be made to approach the rocker arm by accommodating a part of the cam in the recess on the upper surface of the rocker arm.
By increasing the degree of freedom in the layout of the rocker arm and the camshaft, the overall size of the engine can be reduced. In addition, both support walls function as reinforcing ribs, so that the support rigidity of the swing support portion to the arm support portion can be increased.

[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, the cam contact portion is rotatable about an axis parallel to a rocking axis of the rocker arm, is supported by the rocker arm, and is disposed above the rocker arm. A roller that is in rolling contact with the roller, wherein the concave portion is formed on the upper surface of the rocker arm so as to allow oil to accumulate and to guide oil toward the roller, and according to such a configuration, Oil can be stored in the concave portion on the upper surface of the rocker arm to lubricate the roller.

[0008]

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

FIGS. 1 to 7 show an embodiment of the present invention. FIG. 1 is a partial longitudinal sectional view of an internal combustion engine, FIG. 2 is a plan view of FIG. FIG. 4 is an enlarged view taken along line 3-3 of FIG.
3 is a sectional view taken along line 4-4 of FIG. 3, FIG. 5 is an enlarged sectional view taken along line 5-5 of FIG. 1, FIG. 6 is an enlarged sectional view taken along line 6-6 of FIG. 3, and FIG. FIG. 6 is a cross-sectional view for explaining the method.

Referring first to FIGS. 1 and 2, the multi-cylinder internal combustion engine includes a cylinder block 11 and a cylinder head 13 connected to a top of the cylinder block 11 via a gasket 12, and a cylinder is provided for each cylinder. A piston 15 is slidably fitted to a cylinder 14 provided in the block 11. Also cylinder block 1
1, by the cylinder head 13 and each piston 15,
A combustion chamber 16 is formed for each cylinder.

The cylinder head 13 has a pair of intake valve ports 17 facing one side of the ceiling surface of the combustion chamber 16 and two intake valve ports 1.
Each of the cylinders 13 is provided with an intake port 18 that opens to one side surface (the right side surface in FIG. 1) of each cylinder head 13 and a pair of exhaust valves facing the other side of the ceiling surface of the combustion chamber 16. Each of the cylinders is provided with a port 19 and an exhaust port 20 which is connected to both exhaust valve ports 19 and opens to the other side surface (the left side surface in FIG. 1) of the cylinder head 13.

The stems 21 of the intake valves VI, VI capable of opening and closing the respective intake valve ports 17, respectively, are slidably fitted to guide cylinders 22 provided on the cylinder head 13, and are located above the guide cylinders 22. 23, 23 provided at the upper end of stems 21 projecting from
Between the three, there are provided valve springs 24 for urging the intake valves VI, VI upward, that is, in the valve closing direction. Exhaust valve port 19 ...
Valves VE, VE as engine valves capable of opening and closing the respective valves
Of the stems 25 are slidably fitted to guide cylinders 26 provided on the cylinder head 13, and retainers 27, 27 and cylinder heads provided on upper ends of the stems 25 projecting upward from the guide cylinders 26. 13, a valve spring 2 for urging the exhaust valves VE, VE upward, that is, in the valve closing direction.
8 are provided.

The two intake valves VI, VI are connected to the intake-side valve gear 30.
The two exhaust valves VE, VE are driven to open and close by an exhaust-side valve operating device 31.
1, a plug insertion tube 33 for inserting a spark plug 32 attached to the cylinder head 13 facing the center of the combustion chamber 16 is arranged so as to extend vertically, and the lower end of the plug insertion tube 33 is It is attached to the cylinder head 13.

The intake-side valve train 30 includes a pair of intake valves V
First and second drive rocker arms 34 and 35 individually corresponding to I and VI, and drive rocker arms 34 and 3
5, a free rocker arm 36 which can be free with respect to each of the intake valves VI, VI;
An intake-side rocker shaft 37 as an arm supporting portion for swingably supporting the motor 6 is provided, and an intake-side camshaft 38 rotatable about an axis parallel to the rocker shaft 37.

The exhaust-side valve train 31 includes a pair of exhaust valves V
First and second drive rocker arms 39 and 40 individually corresponding to E and VE, and drive rocker arms 39 and 4 thereof.
0, that is, a free rocker arm 41 that can be free with respect to each of the exhaust valves VE, VE, and each rocker arm 39-4.
An exhaust-side rocker shaft 42 for swingably supporting 1;
An exhaust camshaft 43 rotatable about an axis parallel to the rocker shaft 42 is provided.

The intake and exhaust rocker shafts 37,
Reference numeral 42 is fixedly supported by holder walls 44 provided on the cylinder head 13 between the cylinders. The intake-side and exhaust-side camshafts 38, 43 are linked and connected to a crankshaft (not shown) at a reduction ratio of 1/2, and the holder walls 44, 44,. , A cam holder 45 fastened to the upper end of
It is supported rotatably at 45 ...

Incidentally, the intake-side and exhaust-side valve trains 3
Reference numerals 0 and 31 basically have the same configuration. Hereinafter, the configuration and operation of the intake-side valve train will be described in detail, but the description of the exhaust-side valve train 31 will be omitted.

The intake-side camshaft 38 is provided with a high-speed cam 47 and low-speed cams 46, 46 disposed on both sides of the high-speed cam 47 in correspondence with the two intake valves VI.

In FIG. 3, the first drive rocker arm 3
4. The second drive rocker arm 35 and the free rocker arm 36 are made of, for example, an aluminum alloy and are subjected to alumite treatment to reduce the weight, and the first and second drive rocker arms 34, 3 are provided.
5 are arranged adjacent to each other so as to sandwich the free rocker arm 36, and are commonly and slidably supported by the intake side rocker shaft 37.

First and second drive rocker arms 34, 3
The free rocker arm 5 and the free rocker arm 36 are supported by a rocker shaft 37 on the intake side.
a, 35a, 36a are provided at the base end, and extend from the swing support portions 34a, 35a, 36a at positions spaced apart in a direction along the axis of the intake side rocker shaft 37, and oppose each other. And the second support walls 34b, 34
c; 35b, 35c; 36b, 36c, and the first and second drive rocker arms 34, 35
The ends of the second support walls 34b, 34c; 35b, 35c are connected to each other by connecting portions 34d, 35d.

Referring also to FIG. 4, the connecting portion 3 at the tip of the first and second drive rocker arms 34, 35
Tappet screws 48, 48 abutting on the upper ends of the stems 21 of the intake valves VI, VI are threadably engaged with 4d, 35d.

The swing support 3 of the free rocker arm 36
In a portion corresponding to the plug insertion tube 33 in 6a, an arc-shaped notch 49 for allowing the plug insertion tube 33 to approach the free rocker arm 36 side is recessed on the opposite side to the plug insertion tube 33. It is provided in such a way.

With further reference to FIGS. 5 and 6,
Both support walls 34b, 3 on the upper surface of the first drive rocker arm 34
4c, a recess 51 is formed between the support walls 35b, 35c on the upper surface of the second drive rocker arm 35, and both support walls 36b, 3 of the free rocker arm 36 are formed.
A concave portion 52 is formed between 6c. Moreover, the recesses 50, in the first and second drive rocker arms 34, 35,
Openings 53 and 54 are provided in the center of the upper and lower portions of the free rocker arm 36. An opening 55 is provided in the center of the concave portion 52 of the free rocker arm 36 on the side opposite to the intake side rocker shaft 37 and upward. .

First and second drive rocker arms 34, 3
5 are rollers 56, 57 as cam contact portions which are in rolling contact with the low speed cams 46, 46.
4 and rotatably supported on the free rocker arm 36. A roller 58 serving as a cam contact portion that is in rolling contact with the high-speed cam 47 is disposed in the opening 55 so as to be rotatable. It is supported by The recesses 50, 51, 5 of the rocker arms 34, 35, 36
2 can store oil, and each recess 50,
Each of the rollers 51 and 52 is formed so as to be able to guide oil toward the corresponding one of the rollers 56, 57 and 58, and is provided with a passage for smoothly guiding the oil from the concave portions 50, 51 and 52 to the respective rollers 56 to 58. ~ 58 can be effectively lubricated.

Further, the width of the low speed cams 46, 46 in the direction along the axis of the intake side rocker shaft 37 is limited to the first and second support walls 34b, 34c; 35b, 35b, of the first and second drive rocker arms 34, 35. The width of the high-speed cam 47 in the direction along the axis of the intake side rocker shaft 37 is set to be equal to or less than the interval between the first and second support walls 36b and 36c of the free rocker arm 36. The lower part of the low speed cams 46, 46
The points of contact with the rollers 56 and 57 are defined by the first and second support
4b, 34c; accommodated below the upper ends of 35b, 35c in the recesses 50, 51, and the lower part of the high-speed cam 47 defines the contact point with the roller 58 with the first and second support walls 36b, 3;
6c is accommodated in the recess 52 below the upper end.

On the first and second support walls 34b and 34c of the first drive rocker arm 34, the intake side rocker shaft 3 is provided.
7 are provided coaxially, and the first support wall 3 of the second drive rocker arm 35
5b is provided with a through hole 61 having an axis parallel to the axis of the intake side rocker shaft 37, and the second support wall 35c has a bottomed hole 6 closed on the side opposite to the free rocker arm 36.
2 is provided coaxially with the through hole 61. Furthermore, the first and second support walls 36b, 36c of the free rocker arm 36
Are provided coaxially with through holes 63 and 64 having an axis parallel to the axis of the intake side rocker shaft 37.

When the first drive rocker arm 34 is made of a material harder than the first drive rocker arm 34, that is, when the first drive rocker arm 34 is made of an aluminum alloy, for example, a cylindrical roller shaft 65 made of an iron-based material is used. When the second drive rocker arm 35 is made of a material harder than the second drive rocker arm 35, that is, when the second drive rocker arm 35 is made of an aluminum alloy, for example, Cylindrical roller shaft 66 made of iron-based material
Are fixed by press-fitting into the through hole 61 and the bottomed hole 62, and the free rocker arm 36 is
When the free rocker arm 36 is made of an aluminum alloy, the cylindrical roller shaft 67 made of, for example, an iron-based material is provided with the through-hole 6.
It is fixed by press-fitting to 3,64.

Each of the roller shafts 65, 66, 67 is formed in a cylindrical shape with the same inner diameter, and each of the roller shafts 65, 66, 67 and each of the rollers 56, 57, 5
Needle bearings 68, 69, 70 are interposed between the eight.

In FIG. 7, when the roller shaft 67 is pressed into the through holes 63 and 64 of the free rocker arm 36,
The press-fit allowance δ1 of the roller shaft 67 into the through hole 63 of the first support wall 36b is determined by the penetration of the second support wall 36c, which is disposed on the second drive rocker arm 36 side among the first and second support walls 36b and 36c. It is set to be larger than the maximum value of the press allowance δ2 of the roller shaft 67 into the hole 64. Moreover, the second support wall 36
c, the press-fit allowance δ2 of the roller shaft 67 into the through hole 64 is such that the inner end side of the through hole 64, that is, the roller 58 side has the through hole 6
4 is set to be larger than the outer end side, that is, the second drive rocker arm 35 side, and in the range W set to the second drive rocker arm 35 side of the through hole 64, the through hole 6
4, that is, the press-fitting margin δ2 is set to be smaller as it approaches the second drive rocker arm 35. The reason why the press-fitting allowance in the second support wall 36b is changed in the axial direction of the through hole 64 is that, for example, the outer periphery of the end of the roller shaft 67 on the side of the second drive rocker arm 35 is formed into a curved shape that bulges outward. Is achieved by The outer edge of the through hole 64 is chamfered in a tapered shape, and an annular gap 71 is formed between the outer end of the through hole 64 and the roller shaft 67.

At least the end face on the second drive rocker arm 35 side of the both end faces in the axial direction of the roller shaft 67 projects from the side face on the second drive rocker arm 35 side of the free rocker arm 36 by an amount of protrusion L1.

Both through holes 5 of the first drive rocker arm 34
The press-fitting of the roller shaft 65 into the roller shaft 65 into the roller shaft 65 is the same as the press-fitting of the roller shaft 67 into the through holes 63 and 64 of the free rocker arm 36. The end surface on the 36 side protrudes from the side surface of the first drive rocker arm 34 on the free rocker arm 36 side by an amount of protrusion L1.

Referring to FIG. 6, the free rocker arm 36 is attached to the cylinder head 13 below the free rocker arm 36.
A lost motion mechanism 72 is provided for applying a spring force to the free rocker arm 36 in a direction that causes the roller 58 to make rolling contact with the high-speed cam 47. The lost motion mechanism 72 is provided on the cylinder head 13 with its upper part opened. A spring 74 housed in the bottom sliding hole 73 and receiving one end at a lower end closed portion of the sliding hole 73;
And a lifter 75 connected to the other end of the lifter.

On the other hand, the free rocker arm 36 receives the spring force from the lost motion mechanism 72 to
The receiving portion 76 contacts the upper end of the free rocker arm 36. The receiving portion 76 is connected to a connecting wall 77 connecting the lower ends of the first and second supporting wall portions 36b and 36c of the free rocker arm 36 to the free rocker arm. The roller 58 is provided so as to substantially correspond to the axial center of the roller 58 supported by the roller 36. In this embodiment, since the free rocker arm 36 is made of a relatively soft aluminum alloy, the receiving portion 76 is formed by fixing a member made of a hard material such as an iron-based material to the connecting wall 77. , Whereby wear can be reduced while maintaining rigidity. However, when the free rocker arm 36 is made of a hard material, the receiving portion 76 is formed integrally with the connecting wall 77. It may be. The receiving portion 76 is provided with an oil passage 78 extending between the inner and outer surfaces.

Further, the connecting wall 77 extends below the roller 58, and the distance L2 between the tip of the connecting wall 77 and the roller 58 is smaller than the distance between the intermediate portion of the connecting wall 77 and the roller 58. Is set. That is, the connecting wall 77 extending below the roller 58 is formed so as to narrow the interval with the roller 58 toward the lowermost side of the roller 58.

Interlocking switching means 80 for switching between the first drive rocker arm 34, the second drive rocker arm 35, and the free rocker arm 36, a state in which the rocker arms 34 to 36 are interlocked, and a state in which the interlocking of the rocker arms 34 to 36 is released. This interlocking switching means 80 is connected to the second drive rocker arm 3 adjacent to each other.
5 and a first switching pin 81 that can switch between interlocking and releasing the interlocking of the free rocker arm 36, and a cylindrical second switching pin that can switch between interlocking and releasing the interlocking between the free rocker arm 36 and the first drive rocker arm 34 adjacent to each other. 82
A regulating member 83 that contacts the second switching pin 82 on the side opposite to the first switching pin 81; and a coil-shaped return spring 84 that urges the regulating member 83 toward the second switching pin 82. The switching pins 81 and 82 and the regulating member 83 are connected to the roller shaft 65.
Formed of the same hard material as that of No.-67.

The first switching pin 81 is slidably fitted to the roller shaft 66 of the second drive rocker arm 35. The first switching pin 81 is connected to the closed end of the bottomed hole 62 into which the roller shaft 66 is press-fitted. A hydraulic chamber 85 is defined between the pin 81 and the hydraulic chamber 85. An oil passage 86 connected to a hydraulic pressure source via a control valve (not shown) is provided, for example, coaxially in the intake-side rocker shaft 37. Communication path 8 provided in support wall 35c
7, an annular path 88 is provided between the second drive rocker arm 35 and the intake side rocker shaft 37.
A communication hole 89 communicating between the oil passage 8 and the oil passage 86 is provided in the intake side rocker shaft 37.

The second switching pin 82 is connected to the free rocker arm 36.
The first and second roller shafts 67 are slidably fitted to each other.
The switching pins 81 and 82 are brought into contact with each other so that they can slide with each other.

The restricting member 83 is formed in a cylindrical shape with a bottom and is slidably fitted to the roller shaft 65 of the first drive rocker arm 34. The closed end of the restricting member 83 has a second switching pin. 82 are brought into contact with each other to allow them to slide on each other. A regulating member 83 is provided on the inner surface of the roller shaft 65.
, A retaining ring 90 for preventing the regulating member 83 from falling off the roller shaft 65 is attached.

A ring-shaped washer 91 is inserted into the outer end of the roller shaft 65, and a retaining ring 92 that engages with the outer surface of the washer 91 is fitted on the inner surface of the roller shaft 65. Thus, the return spring 84 is provided between the regulating member 83 and the washer 91.

In such an interlocking switching means 80, in the low speed operation range of the engine, the hydraulic pressure in the hydraulic chamber 85 is relatively low, and the contact surfaces of the first and second switching pins 81 and 82 are in contact with the second drive rocker arm 35. And the contact surface between the second switching pin 82 and the restricting member 83 is located at a position corresponding to between the free rocker arm 36 and the first drive rocker arm 34. Therefore, each rocker arm 34, 35, 36 is in a state of relative swinging, and both intake valves VI, VI are driven to open and close at the timing and the lift amount corresponding to the low speed cams 46, 46.

In the high-speed operation range of the engine, a relatively high hydraulic pressure is applied to the hydraulic chamber 85, and the first switching pin 81 slides on the roller shaft 67 of the free rocker arm 36 while pressing the second switching pin 82. And the second switching pin 82 presses the regulating member 83 while the first drive rocker arm 34
Is slidably fitted to the roller shaft 65. Therefore, the respective rocker arms 34, 35, 36 are integrally connected, and both intake valves VI, VI are driven to open and close at the timing and the lift amount corresponding to the high-speed cam 47.

Next, the operation of this embodiment will be described. Each rocker arm 34,
35, 36 are provided with swing support portions 34a, 35a, 36a that are swingably supported by the intake side rocker shaft 37, and are provided with first and second swing support portions 34a, 35a, 36a. 2 support walls 34b, 34c; 35
b, 35c; 36b, 36c, respectively, and both support walls 34b, 34 on the upper surface of each rocker arm 34-36.
c; 35b, 35c; recess 50 between 36b, 36c.
51 and 52 are respectively formed. Moreover, each recess 50 ~
Rollers 56, 57, 58 that are in rolling contact with the low-speed cams 46, 46 and the high-speed cam 47 of the intake-side camshaft 38 are disposed at the center of the cam 52.
6, 46, 47 are the two support walls 34b, 34c;
b, 35c; 36b, 36c, so as to be in contact with the rollers 56, 57, 58 below the upper ends thereof.
A part is stored in 0-52.

Therefore, it is possible to bring the intake side camshaft 38 close to each of the rocker arms 34 to 36,
Each rocker arm 34-36 and intake side camshaft 3
8, the degree of freedom in layout can be increased, and the size of the entire engine can be reduced. 35b, 35c; 36b, 36c function as reinforcing ribs, and support the swing support portions 34a, 35a, 36a on the intake side rocker shaft 37. The rigidity can be increased. Moreover, each concave portion 50-52
The rollers 56 to 58 can be lubricated by guiding the oil stored in the rollers to the rollers 56 to 58.

Incidentally, each of the rocker arms 34 to 36
Of these, the spring force that presses toward the high-speed cam 47 corresponding to the free rocker arm 36 by the lost motion mechanism 72 acts on the free rocker arm 36 that can be free with respect to the intake valves VI and VI. A connecting wall 77 is provided between the support walls 36b and 36c of the free rocker arm 36.
And the lifter 7 of the lost motion mechanism 72
5 is provided on the connection wall 77 substantially corresponding to the axial center of the roller 58 supported by the free rocker arm 36.

Therefore, the load point acting on the free rocker arm 36 from the high-speed cam 47 and the pressing point acting from the lost motion mechanism 72 do not significantly deviate in the axial direction of the roller 58.
Stable swing support is possible. Further, since the first and second support walls 36b and 36c are connected by the connecting wall 77,
Roller 58 rotatably supported between support walls 36b and 36c
Support rigidity can be increased.

Further, since the connecting wall 77 is formed below the roller 58 so as to narrow the space between the roller 58 and the lower end of the roller 58 and is disposed below the roller 58, the space between the roller 58 and the connecting wall 77 is reduced. And the oil can be used to lubricate the roller 58. The receiving portion 76 is provided with an oil passage 78 extending between the inner and outer surfaces thereof, and guides the oil held between the roller 58 and the connecting wall 77 to a contact portion between the lifter 75 of the lost motion mechanism 72 and the receiving portion 76. This can contribute to a reduction in wear at the contact portion.

Low speed cam 4 of intake side camshaft 38
Rollers 56, 57, and 58 that are in rolling contact with the high-speed cam 47 and the low-speed cam 47, respectively.
6 are rotatably supported by cylindrical roller shafts 65, 66, 67 via needle bearings 68, 69, 70, respectively. Are slidably fitted to the roller shaft 67 of the free rocker arm 36 and the roller shaft 65 of the first drive rocker arm 34, respectively, when the interlocking switching means 80 operates from the interlocking release state to the interlocking state.
That is, the second drive rocker arm 35 and the free rocker arm 36 are connected by the first switching pin 81 that spans between the second drive rocker arm 35 and the free rocker arm 36, and the second switch bridges between the free rocker arm 36 and the second drive rocker arm 34. The free rocker arm 36 and the second drive rocker arm 34 are connected by the switching pin 82.

The roller shafts 67 and 65 are made of a material harder than the free rocker arm 36 and the first drive rocker arm 34.
In 5, at least one end face of the both end faces in the axial direction that receives the first and second switching pins 81 and 82 protrudes from the rocker arms 36 and 34. That is, in the free rocker arm 36, the end face of the roller shaft 67 on the second drive rocker arm 35 side protrudes from the side surface of the free rocker arm 36 toward the second drive rocker arm 35, and in the first drive rocker arm 34, the roller shaft 65 Of the first drive rocker arm 34 protrudes from the side surface of the first drive rocker arm 34.

Therefore, the interlocking switching means 80 is set to the interlocking release state, and the rocker arms 36, 35;
Even when the hydraulic pressure in the hydraulic chamber 85 fluctuates during the relative swinging movement of the rockers 4 and 36, the end surfaces of the first and second switching pins 81 and 82 do not slide on the side surfaces of the free rocker arm 36 and the first drive rocker arm 34. The roller shafts 67 and 65 remain in sliding contact with the end surfaces. Further, since the roller shafts 67 and 65 are made of a material harder than the free rocker arm 36 and the first drive rocker arm 34, the roller shafts 67 and 65 are made of a material harder than the free rocker arm 36 and the first drive rocker arm 34.
The generation of abrasion powder due to sliding contact between the roller shaft 67 and the switching pins 81 and 82 can be minimized.
65 so as not to enter the switching pin 8.
1, 82, that is, the smooth switching operation of the interlocking switching means 80 can be guaranteed.

Further, the free rocker arm 36 and the first drive rocker arm 34 formed of an aluminum alloy
The outer surface of the switch is anodized, and the switching pin 8
Since it is not necessary to consider the sliding contact with the first and second rockers 1, 82, it is possible to contribute to the prevention of corrosion of the free rocker arm 36 and the first drive rocker arm 34 while retaining the film formed by the alumite treatment. The second drive rocker arm 35 has no possibility of contact with the switching pins 81 and 82 from the beginning, and even if the alumite treatment is performed, there is no problem in preventing corrosion.

Further, each of the roller shafts 65, 66, 67 is provided with the first and second support walls 34b, 34c, 35b, 35c, 36 provided in the rocker arms 34, 35, 36, respectively.
b and 36c, and in this embodiment, both are press-fitted. Therefore, parts other than the roller shafts 65 to 67 are not required for fixing the roller shafts 65 to 67, and the roller shafts 65 to 67 can be easily attached to the rocker arms 34 to 36 while avoiding an increase in the number of parts and an increase in the number of processing steps. Can be fixed.

The roller shaft 6 in the free rocker arm 36
7 on the side of the second support wall 36c, and the second drive wall 34c of the roller shaft 65 in the first drive rocker arm 34.
The side portion receives the first and second switching pins 81 and 82 of the interlocking switching means 80 from the first drive rocker arm 35 and the free rocker arm 36 side, but receives the first drive rocker arm 35 and the free rocker arm 36 side. The amount of press-fitting of the roller shafts 67, 65 into the second support walls 36c, 34c is based on the second support walls 36c, 34 on the rollers 58, 56 side.
It is set smaller than the press-fitting allowance of the roller shafts 67 and 65 to c.

Therefore, the first and second switching pins 81,
The deformation of the ends of the roller shafts 67, 65 on the side of receiving the roller shaft 82 due to press-fitting can be reduced, and the first and second switching pins 81, 82 can be smoothly fitted into the roller shafts 67, 65 so that the adjacent rocker arms 35 can be formed. , 36; switching between interlocking and uncoupling by the switching pins 81, 82 of 36, 34 becomes smooth.

In addition, of the press-fitting portions of the roller shafts 67 and 65 into the second support walls 36c and 34c, the press-fitting allowance on the second drive rocker arm 35 and the free rocker arm 36 side is the second.
Since it is set to be smaller as it approaches the drive rocker arm 35 and the free rocker arm 36,
The deformation of the ends of the roller shafts 67, 65 due to press-fitting decreases toward the second drive rocker arm 35 and the free rocker arm 36, and the switching pins 81, 82 can be more smoothly fitted into the roller shafts 67, 65, and can be interlocked. Further, switching of the interlock release can be performed more smoothly.

Further, in this embodiment, the second
The end face of the drive rocker arm 35 and the end face of the roller shaft 65 on the free rocker arm 36 side are free rocker arms 36.
And the outer ends of the second support walls 36c, 34c and the roller shaft 6 protruding from the first drive rocker arm 34.
Since the annular gaps 71 are formed between the rollers 7 and 65, stress is prevented from acting on the ends of the roller shafts 67 and 65 on the side of the second drive rocker arm 35 and the free rocker arm 36, and the deformation is further reduced. Thus, the switching between the interlock and the release of the interlock by the switching pins 81 and 82 can be further smoothly performed.

Further, by making the press-fit allowance for the first support walls 36b, 34b larger than the press-fit allowance for the second support walls 36c, 34c, the roller shafts 67, 65 are provided with the first and second support walls 36.
b, 36c; press-fitted into 34b, 34c, whereby the deformation of the ends of the roller shafts 67, 65 on the side receiving the switching pins 81, 82 due to press-fitting is suppressed to a small extent, and switching between interlocking and interlocking release is performed. The roller shafts 67, 65 are press-fitted from outside of the second support walls 36c, 34c, so that the roller shafts 67, 65 can be smoothly pressed.
Press-fitting work becomes easy.

The first drive rocker arm 34 disposed at one end of the rocker arms 34, 35, 36 along the arrangement direction.
In the first embodiment, through holes 59 and 60 for press-fitting both ends of the roller shaft 65 are provided coaxially in the first and second support walls 34b and 34c provided in the first drive rocker arm 34. A washer 91 for receiving the spring 84 is mounted on the roller shaft 65.

Therefore, it is not necessary to perform a relief process on the closed end side of the bottomed hole, as compared with the case where the bottomed hole must be drilled in the first support wall 34b. Support wall 3 while enabling
4b can be facilitated, and the weight of the first drive rocker arm 34 can be reduced by the amount that the end wall becomes unnecessary. Further, as in this embodiment, when the intake side rocker shaft 37 and the roller shaft 65 are parallel to each other, the distance between the axes of the intake side rocker shaft 37 and the roller shaft 65 at the first and second support walls 34b and 34c. Can be accurately determined.

Further, since the washer 91 is inserted into the roller shaft 65 such that the outer surface of the washer 91 is engaged with the retaining ring 92 fitted on the inner surface of the roller shaft 65, the washer 91 can be easily mounted on the roller shaft 65. It is. In addition, by setting the inner diameter of the washer 91 to be relatively large, the inside of the roller shaft 65 can be visually recognized from the outside, and whether or not the return spring 84 is correctly accommodated in the roller shaft 65 can be confirmed from the outside. .

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.

For example, the present invention is also applicable to a valve train of an internal combustion engine in which a camshaft is arranged below a rocker arm.

[0062]

As described above, according to the first aspect of the present invention, the camshaft can be brought close to the rocker arm, and the degree of freedom in the layout of the rocker arm and the camshaft is increased to reduce the size of the entire engine. In addition, the support rigidity of the swing support portion to the arm support portion can be increased.

According to the second aspect of the present invention, it is possible to lubricate the roller by storing oil in the concave portion on the upper surface of the rocker arm.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional view of an internal combustion engine.

FIG. 2 is a plan view as viewed in the direction of arrow 2 in FIG.

FIG. 3 is an enlarged view taken along line 3-3 of FIG. 1;

FIG. 4 is a sectional view taken along line 4-4 of FIG. 3;

FIG. 5 is an enlarged sectional view taken along line 5-5 of FIG. 1;

FIG. 6 is an enlarged sectional view taken along line 6-6 of FIG. 3;

FIG. 7 is a cross-sectional view for explaining a press-fit margin of a roller shaft into a rocker arm.

[Explanation of symbols]

13: Cylinder head 30, 31, Valve operating device 34, 35, 36 ... Rocker arm 34a, 35a, 36a ... Swing support portion 34b, 34c, 35b, 35c, 36b, 36c ...
· Support wall 37 ··· Rocker shaft as arm support portion 38 ··· Camshaft 46, 47 ··· Cam 50, 51, 52 ··· Recess 56, 57, 58 ··· As cam contact portion roller

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Noriyuki Yamada 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3G013 AA06 AA07 BA01 BA06 BC12 BD35 3G016 AA08 AA12 AA19 BA49 BB22 CA04 CA13 CA21 CA27 CA29 CA41 CA44 CA52 CA57 EA03 FA18 GA01

Claims (2)

[Claims] An oscillating support (34a, 35a, 36a) supported oscillatably by an arm support (37) provided on a cylinder head (13), and the oscillating support (3).
4a, 35a, 36a) and a pair of support walls (34b, 34c; 35b, 35c; 36b, 36c).
And the support walls (34b, 34c; 35b, 35c; 36b, 3).
6c) Cam contact portions (56, 57, 58) arranged between them
And a camshaft (3) provided with a cam (46, 47) at one of the upper and lower sides of the rocker arm (34, 35, 36) to come into contact with the cam contact portion (56-58).
8) In the valve gear of an internal combustion engine in which the rocker arms (34 to 36) are arranged, the support walls (34b, 34) of the rocker arms (34 to 36) are arranged.
c; 35b, 35c; 36b, 36c), a concave portion (50, 51, 52) is formed on the camshaft (38) side, and the cam abutment disposed at the center of the concave portion (50 to 52). Cams (46, 47) that contact the parts (56-58)
A part of which is accommodated in the concave portion (50 to 52). 2. The rocker arm (34-36), wherein the cam contact portion is rotatable about an axis parallel to a swing axis of the rocker arm (34-36) and is supported by the rocker arm (34-36). ) Are rollers (56-58) that are in rolling contact with the cams (46, 47) of the camshaft (38) disposed above the recesses (50-52). The valve train for an internal combustion engine according to claim 1, wherein the valve train is formed on an upper surface of the rocker arm (34-36) so as to guide oil toward a roller (56-58).