JPH0586818A - Roller rocker arm - Google Patents

Abstract

PURPOSE:To enhance a following characteristic of a roller to a cam at the time of high speed rotation so as to increase an allowable engine speed by driving the roller by power different from that applied to the cam. CONSTITUTION:An impeller is provided with a plurality of projections 18a projecting at predetermined intervals at the side surface of a roller 11. The impeller is driven forward by hydraulic power different from that applied to a camshaft 23 so that rotating auxiliary force is exerted on the impeller. Consequently, a load applied to the camshaft at the time of rotation of the roller can be reduced. Moreover, the roller 11 and a rotary cam 24 cannot be idly slidden until they reach a high speed rotating region. Accordingly, it is possible to enhance a following characteristic at the time of high speed rotation so as to increase an allowable engine speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roller rocker arm used in a valve operating mechanism of an internal combustion engine, and more particularly to a roller rocker arm designed to reduce the load on a camshaft.

[0002]

2. Description of the Related Art Among OHC type valve operating mechanisms, one end of a rocker arm is supported by a pivot shaft, a rocker arm is vertically swung by a cam disposed above an intermediate portion of the rocker arm, and the other end of the rocker arm causes an engine to move. There is an end pivot (swing arm) type that opens and closes the valve.

In this end pivot type valve operating mechanism, the rocker arm and the cam are generally in sliding contact, so that mechanical loss due to friction is relatively large and the load on the cam shaft is increased. As a result, fuel efficiency and output are reduced.

Recently, as a solution to this problem,
Various roller rocker arms have been proposed in which a rotatable roller is provided at a sliding contact portion of a rocker arm with a cam so as to make a rolling contact, thereby reducing friction loss.

[0005]

Recent automobile engines have a tendency to achieve high output and high speed by mounting a supercharger or adopting a multi-valve mechanism. It is effective to increase the permissible rotation speed in order to obtain a high output with an engine of the same displacement. To increase the permissible rotation speed, devise the valve operating system components such as valves and rocker arms. It is necessary to improve the follow-up performance for the cam.

The roller rocker arm has a drawback that the weight is increased by the addition of the roller as compared with the ordinary sliding contact type rocker arm, and the rotation of the cam follows the rotation of the cam without slipping in the high rotation range. It is difficult to do so, which is an obstacle to increasing the allowable engine speed.

That is, in general, as the engine speed of the roller of the roller rocker arm increases, the followability to the cam is impaired, and slippage occurs and sliding contact occurs, and the advantage of the roller rocker arm is lost.

In this case, as in the case of the above-mentioned ordinary rocker arm, the mechanical loss due to friction becomes large,
Since the load on the camshaft increases, it is necessary to set the allowable engine speed to a low value.

The present invention has been made to solve the above problems, and an object thereof is to apply a rotation assisting force to a roller in a system different from that of a camshaft to reduce a load on the camshaft. Another object of the present invention is to provide a roller rocker arm in which the followability of the roller to the cam is improved and the allowable rotation speed of the engine can be increased.

[0010]

In order to achieve the above object, the present invention is directed in the front-back direction supported by the rocker arm body in a vertically oriented fitting hole formed in a substantially central portion of the rocker arm body. In a roller rocker arm that accommodates a roller that rotates around an axis such that its upper end surface contacts a rotating cam, a plurality of ridges are radially formed on at least one of the side surfaces of the roller that faces the axial direction. A forward rotation assisting force is applied to the roller by providing a protruding impeller, communicating with an appropriate hydraulic pressure generation source at an appropriate position of the rocker arm body, and discharging lubricating oil toward the impeller. It is characterized by the provision of such a discharge nozzle.

[0011]

Since the roller receives the rotation assisting force in the forward direction by the hydraulic power different from that of the camshaft, the load on the camshaft is reduced and the slippage between the roller and the cam is eliminated even in the high rotation range. Therefore, the followability at the time of high-speed rotation is improved, and the allowable rotation speed of the engine can be increased.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show an end pivot (swing arm) including a roller rocker arm (R) according to an embodiment of the present invention.
It is a schematic representation of a valve actuation mechanism of the rocker arm body (1)
One end of the pivot shaft (3) of the known hydraulic valve lash adjuster (3) incorporated in the cylinder head (2).
It is pivotally supported by fitting it from above into the spherical portion (3b) at the upper end of a), and the other end is also a pair of cotters (4) (4), spring retainer (5), and valve spring (6). It is in contact with the stem end (7a) of the engine valve (7) assembled to the cylinder head (2) by each member such as.

As shown in FIGS. 2 and 3, the rocker arm main body (1) is provided with a pivot receiving block (9) on one end side in the longitudinal direction between the left and right long side plates (8) and (8). Similarly, attach the stem contact block (10) to the other end, and further attach both side plates (8).
Surrounded by (8) and both blocks (9) and (10), the rollers (11) are respectively sandwiched in the central portion where a vertically fitting hole (1a) is formed, and a pair of left and right fixing members are provided. The entire rivet (12) is integrally connected by penetrating both side plates (8) and both blocks (9), (10) and caulking the insertion ends thereof.

The both side plates (8) and the blocks (9) and (10) are provided with through holes (13a) and (13b) through which the rivets (12) pass, and the blocks (9) and (10) are further provided with Small-diameter through holes that engage with inwardly protruding projections (14) on both ends of both side plates (8)
(15) is provided. When both blocks (9) and (10) are sandwiched by both side plates (8), the blocks (9) and (10)
Engages the side plate (8) at two places of the through holes (13b) (15),
Rotation around the axis is suppressed.

A fitting hole (1) which is formed by being surrounded by both side plates (8) and both blocks (9) and (10) and which faces in the vertical direction.
The roller (11) provided in the central part of (a) is a shaft hole (17) in which a small-diameter rotary shaft (16) protruding in the longitudinal direction of the axis is provided in both side plates (8).
It is rotatably supported by being loosely fitted to.

When both rotary shafts (16) are pivotally supported by the side plate (8), the roller (11) has the upper end of the outer periphery of the large diameter part of the side plate (8).
(8) The roller body (11a) located above the upper side (8a) and the front and rear side surfaces of the roller body (11a) facing the axial direction are provided with a plurality of protrusions (18a) at regular intervals. It consists of an impeller (18) that projects radially from each other.

A distance (a) between the impeller (18) projecting on the front side surface of the roller (11) in the axial direction and the tips of the projecting ridges (18a) of the impeller (18) similarly provided on the rear side surface. Is
It is slightly smaller than the front-rear length (b) of both blocks (9) and (10), and can easily rotate even if the roller (11) is sandwiched between the side plates (8). However, the difference (ba) is calculated by the roller (11).
It is not a big thing that rattles back and forth.

A hemispherical pivot bearing hole (19) is formed on the lower surface of the pivot receiving block (9) so as to be fitted into the spherical portion (3b) at the upper end of the pivot shaft (3a) from above. A through hole (20) penetrating in the front-back direction is provided above the bearing hole (19), and the center of the through hole (20) has a through hole (20).
It communicates with the pivot bearing hole (19) directly below via a).

Furthermore, the side plate of the pivot receiving block (9)
The front and rear surfaces (9a) and (9a) that come into contact with (8) have through holes (20) at one end.
A groove (21) communicating with the roller is engraved, and the other end of the groove (21) is
At the block end surface (9b) close to the outer peripheral surface of (11),
The tip is slightly narrowed to open as a lubricating oil discharge nozzle (22).

The direction in which the lubricating oil is radiated from the discharge nozzle (22) is rotated by a rotating cam (24) fixed to a cam shaft (23) provided directly above the roller (11).
In order to give a rotation assisting force in the same direction as the rotation direction of (11) (forward direction), it is oriented in a direction approximately similar to the tangential direction of the outer periphery of the roller body (11a), and the pressurized lubricating oil is impeller.
It can radiate toward (18).

The lubricating oil radiated toward the impeller (18) is the oil provided in the through hole (25) passing through the pivot shaft (3a) of the valve lash adjuster (3) and the cylinder head (2). It is sent from an appropriate hydraulic pressure generation source through a through hole (26) communicating with the gallery.

When the pressurized lubricating oil is radiated to the impeller (18), a rotational force is generated in the roller body (11a), and this rotational force is brought into sliding contact with the rotating cam (24) to rotate the roller (11). Since it acts as a rotation assisting force in the forward direction, the load on the camshaft (23) is reduced.

This means that the operation resistance of the roller rocker arm (R) is reduced when viewed from the camshaft (23) side. That is, the same effect as that when the apparent rotational inertia mass of the roller (11) is reduced is obtained. As a result, the resistance force of the rotating cam (24) for rotating the roller (11) becomes small, and the limit rotational speed at which slippage between the rotating cam (24) and the roller (11) occurs becomes large.

Further, the pressure of the lubricating oil is made to correspond to the rotational speed of the engine so that the lubricating oil has a high pressure when the engine is at a high rotation speed, so that the roller ( The rotation of 11) can be made to follow the rotation of the rotating cam (24).

In the embodiment, the lubricating oil is supplied from the valve lash adjuster (3), but a separate hydraulic system passage may be provided to radiate the lubricating oil to the impeller (18). Good.

Further, the rocker arm body (1) is pivotally supported by a hollow rocker shaft instead of the valve lash adjuster (3), and the lubricating oil supplied to the hollow hole is impeller.
You may make it radiate to (18). The roller (11) may be a bearing type roller using a needle roller or the like.

[0027]

According to the present invention, the roller receives a rotation assisting force in the forward direction by the hydraulic power different from the camshaft, so that the load on the camshaft is reduced,
The slippage between the roller and the cam is eliminated even in the high rotation range, the followability at high speed rotation is improved, and the allowable rotation speed of the engine can be increased.

Further, since the slippage between the roller and the cam is eliminated even in the high rotation range, frictional heat is less generated and the amount of change in valve clearance due to thermal expansion of the roller or the like can be reduced.

[Brief description of drawings]

FIG. 1 is a central vertical sectional front view showing an embodiment of the present invention and an example of mounting the same.

FIG. 2 is a plan view taken along the line AA in FIG.

3 is an exploded perspective view of the roller lock arm of FIG. 1. FIG.

[Explanation of symbols]

(1) Rocker arm body (1a) Fitting hole (2) Cylinder head (3) Valve lash adjuster (3a) Pivot shaft (3b) Spherical part (4) Cotter (5) Spring retainer (6) Valve spring (7) Engine Valve (8) Side plate (8a) Upper side (9) Pivot receiving block (9a) (9a) Surface (9b) Block end surface (10) Stem contact block (11) Roller (11a) Roller body (12) Rivet (13a) ( 13b) Through hole (14) Projection (15) Through hole (16) Rotating shaft (17) Shaft hole (18) Impeller (18a) Projection (19) Bearing hole (20) Through hole (20a) Through hole (21) Groove (22) Discharge nozzle (23) Cam shaft (24) Rotating cam (25) Through hole (26) Through hole (R) Roller rocker arm

Claims (1)

[Claims] 1. A roller that is supported by the rocker arm body and that rotates around an axis that extends in the front-rear direction is provided in a fitting hole that is formed in a substantially central portion of the rocker arm body and that has an upper end surface serving as a rotating cam. In a roller rocker arm that is housed so as to make contact, at least one of the side surfaces of the roller facing the axial direction is provided with an impeller having a plurality of radially projecting projections, and at a suitable position of the rocker arm body. A roller rocker arm provided with a discharge nozzle that is connected to an appropriate hydraulic pressure source and that applies a rotation assisting force in the forward direction to the roller by discharging lubricating oil toward the impeller. .