JPH0749008A - Rocker arm supporting structure - Google Patents

Abstract

PURPOSE:To provide a rocker arm supporting structure making possible the common use of a cam shaft holder and the like between an engine with valve opening/closing timing changing mechanism and an engine provided further with valve actuating/stopping mechanism. CONSTITUTION:The axial direction length is made the same between a rocker arm assembly with valve opening/closing timing changing mechanism formed by fitting a rocker arm 5 and a high speed rocker arm 6 onto a rocker shaft 3 supported by the journal part of a cam shaft holder and a rocker shaft cap, and a rocker arm assembly 2 with valve actuating/stopping mechanism by fitting a rocker arm 10, a low speed rocker arm 11 and a high speed rocker arm 12 onto the rocker shaft 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rocker arm support structure in which an engine having a valve opening / closing timing changing mechanism and an engine having a valve operation stopping mechanism can share a camshaft holder and the like. .

[0002]

2. Description of the Related Art Generally, in opening / closing control of an intake valve and an exhaust valve in an automobile engine, an opening / closing timing is set according to an operating state obtained from an engine speed, an accelerator depression amount, and the like. Then, in such a valve operating device, there has been proposed one in which the cam profile is changed in order to reduce fuel consumption at a low speed and to perform efficient intake and exhaust at a high speed according to the operating state. . This is done by changing the opening / closing timing of the intake valve and the exhaust valve, the lift amount, the opening period, etc. at low speed or high speed.

That is, in an automobile engine, a high speed cam and a low speed cam are provided on a cam shaft, and the high speed cam has a cam profile capable of obtaining a valve opening / closing timing corresponding to high speed operation. The cam has a cam profile capable of obtaining the valve opening / closing timing corresponding to the low speed operation. By selectively using the high-speed cam or the low-speed cam according to the operating condition while the engine is operating, it is possible to obtain the optimum opening / closing timing of the intake valve and the exhaust valve. There is.

Specifically, for example, a base end of a rocker arm is fixed to a rocker shaft and a rocker arm for high speed is provided so as to be connectable and separable. The cam and the high speed cam are engaged with the low speed rocker arm and the high speed rocker arm. That is, at low speeds, the low speed cam swings the rocker arm to open and close the valve.At high speeds, the high speed rocker arm is coupled to the rocker shaft, and the high speed cam swings the rocker arm to open the valve. Is opened and closed.

In addition, in such an automobile engine, a cylinder deactivation mechanism which reduces fuel consumption by stopping two cylinders of a four-cylinder engine during idle operation or low load operation is conventionally used. Proposed. That is,
In the valve train, the piston operates during idle operation or low load operation, but the operation of the intake valve and the exhaust valve is stopped so that fuel is not supplied.

As a concrete structure example, the base end of the rocker arm is fixed to the rocker shaft, the low speed rocker arm and the high speed rocker arm are provided so as to be coupled and separable, and the rocking end of the rocker arm contacts the upper end portion of the valve. It has a structure in which the low speed cam and the high speed cam are connected to the corresponding low speed rocker arm and high speed rocker arm respectively. With this structure, at low speed,
The low speed rocker arm is connected to the rocker shaft, the low speed cam opens and closes the valve, the high speed rocker arm is connected to the rocker shaft at high speed, the high speed cam opens and closes the low speed rocker arm and the high speed rocker arm. By separating them, a stop state of the valve operation, that is, a cylinder deactivation state is achieved.

[0007]

By the way, when an engine having the valve opening / closing timing changing mechanism and an engine further having a valve operation stopping mechanism are manufactured,
In particular, because the rocker arms have different layouts, the cylinder heads had to be manufactured separately, and they could not be shared.

[0008]

In order to solve the above-mentioned problems, according to the present invention, a rocker shaft is provided by a plurality of journal portions provided on a camshaft holder attached to a cylinder head and a rocker shaft cap fitted over these journal portions. In the structure for holding both ends of the rocker arm, a rocker arm and a rocker arm for high speed, or a rocker arm and a rocker arm for low speed, and a rocker arm for high speed are formed on the rocker shaft according to the dimension between the journal portions.

[0009]

According to this structure, the same camshaft holder and the like can be used in an engine having only a valve opening / closing timing changing mechanism and also in an engine having a valve operation stopping mechanism.

[0010]

FIG. 1 shows a rocker arm assembly in a rocker arm support structure according to an embodiment of the present invention.
FIG. 1 (A) shows a rocker arm assembly 1 including only a valve opening / closing timing changing mechanism, and FIG. 1 (B) shows
Further, a rocker arm assembly 2 having a valve deactivation mechanism is shown.

The rocker arm assembly 1 is constructed by integrally mounting a base end portion of a rocker arm 5 having a collar portion 4 on a rocker shaft 3 and adjoining to it a high speed rocker arm 6 so that they can be coupled and separated. The other end of the rocker arm 5 is a portion that comes into contact with the stem end of the valve, and an adjust nut 7 for that purpose is provided. The rocker arm 5 is operated at a low speed and the like, and includes a roller bearing 8 that is engaged with a low speed cam. The high speed rocker arm 6 is provided with a roller bearing 9 that contacts the high speed cam. The length from the end surface of the collar portion 4 of the rocker arm assembly 1 to the end surface of the high speed rocker arm 6 is "L".

In the rocker arm assembly 2 with a valve operation stopping mechanism, the base end of the rocker arm 10 is integrally mounted on the rocker shaft 3, and the rocker arm 11 for low speed and the rocker arm 12 for high speed are mounted on the rocker shaft 3 on both sides thereof. It is attached so that it can be connected and separated. Rocker arm 10
The other end is a portion that abuts on the stem end of the valve and is provided with an adjusting nut 7. Low speed rocker arm 1
1. The high-speed rocker arm 12 is equipped with roller bearings 13 and 14 at its tip.
Is contacted with the low speed cam and the high speed cam. Like the rocker arm assembly 1, the length from the end surface of the low speed rocker arm 11 to the end surface of the high speed rocker arm 12 of the rocker arm assembly 2 is “L”.

On the other hand, FIGS. 2 to 5 show a camshaft holder and the like on which the rocker arm assemblies 1 and 2 are supported.
Reference numeral 15 is a cylinder head, on which a camshaft holder 16 is attached. Rocker shaft journal portions 17 are formed on the lower surface of the camshaft holder 16 at regular intervals along the crankshaft direction of the engine, and the adjacent journal portions 17 have rocker shaft journals 3 of the rocker arm assembly 1 or 2. Both ends of are fitted and held by attaching the rocker shaft cap 18 to the camshaft holder 16.

The camshafts 19 and 20 are assembled on the upper surface of the camshaft holder 16 and held by the cam cap 21. The camshafts 19 and 20 include a rocker arm 5 on the camshaft 3 of the rocker arm assemblies 1 and 2, roller bearings 8 and 9 of a rocker arm 6 for high speed, or a rocker arm 1 for low speed and high speed.
Low speed and high speed cams 22 and 23 that contact the roller bearings 1 and 12 are formed.

2 and 3 show a state in which only the rocker arm assembly 1 having no valve operation stopping mechanism is assembled. In FIG. 2, the right side shows the intake side and the left side shows the exhaust side. In FIG. 2, reference numeral 24 denotes the high-speed rocker arm 6 when the high-speed rocker arm 6 is separated from the camshaft 3.
It is a lost motion mechanism for keeping it in contact with the cam cap 21. Rocker arm 6 for high speed
The connection and disconnection with the camshaft 3 are made by, for example, hydraulic pressure and spring force, and an oil control valve 25 for that purpose is attached to the end of the camshaft holder 16. FIG. 3 shows the plane of the rocker arm assembly 1 and also the adjust nut 7 and the valve 26 at the end of the rocker arm 5.
The contact state with the stem end of is shown.

FIGS. 5 and 6 show an engine in which the rocker arm assembly is changed to the one having the valve operation stopping mechanism so that the first and fourth cylinders can be deactivated.
Camshaft holder 16, rocker shaft cap 18
Etc. can be shared as they are. However, when the cylinder is inactive, the lost motion mechanism 24 is applied to the low-speed rocker arm 11 as well.
Therefore, it is necessary to replace the two cam caps 21 with the one having the lost motion mechanism holding portion and the one having another set 21a.
Further, since the oil control valve 27 for the cylinder deactivation is necessary, it is mounted on the end portion of the camshaft holder 16 or the like.

FIG. 6 is a plan view of the rocker arm assembly 2 and also the adjust nut 7 at the end of the rocker arm 10.
Shows a contact state between the stem end of the valve and. In this embodiment, as shown in the figure, in the rocker arm assembly 2 with the valve operation stopping mechanism, the contact point between the adjust nut 7 and the stem end is the center of the stem end without the valve operation stopping mechanism. D on the opposite side of the thing
_{3 It is} shifted. This is because the wall thickness of the low speed rocker arm 11 is increased by shifting the rocker arm 11 to the opposite side to improve the rigidity. Of course, there is no difference in the valve opening / closing function.

[0018]

According to the rocker arm support structure of the present invention, since the rocker arm assembly has the same axial dimension as the rocker arm assembly with and without the valve operation stopping mechanism, the camshaft holder and the like can be shared. This is advantageous in terms of production and cost.

[Brief description of drawings]

FIG. 1 is a plan view of a rocker arm assembly according to an embodiment.

FIG. 2 is a plan view of a cylinder head of an engine having no valve deactivation mechanism.

FIG. 3 is an explanatory view of an arrangement of rocker arms and the like in an assembled state and a relationship with a valve.

4 is a cross-sectional view taken along the line AA of FIG.

FIG. 5 is a plan view of a cylinder head of an engine having a valve deactivation mechanism.

FIG. 6 is an explanatory diagram showing an arrangement of rocker arms and the like in an assembled state and a relationship with a valve.

[Explanation of symbols]

1 rocker arm assembly having a valve opening / closing timing changing mechanism 2 rocker arm assembly having a valve operation stopping mechanism 3 rocker shaft 5 rocker arm 6 high speed rocker arm 8, 9 roller bearing 10 rocker arm 11 low speed rocker arm 12 high speed rocker arm 13, 14 roller Bearing 15 Cylinder head 16 Camshaft holder 17 Rocker shaft journal 18 Rocker shaft cap 19,20 Camshaft 21 Cam cap 22 Low speed cam 23 High speed cam

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Claims (1)

[Claims] 1. A structure in which both end portions of a rocker shaft are held by a plurality of journal portions provided on a camshaft holder attached to a cylinder head and rocker shaft caps fitted over these journal portions,
A rocker arm support structure comprising a rocker arm and a high speed rocker arm, or a rocker arm, a low speed rocker arm, and a high speed rocker arm on a rocker shaft according to the dimension between the journal portions.