JPH085288Y2 - Engine valve mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an engine valve operating mechanism that can be suitably adopted when adjusting a valve clearance by using hydraulic pressure of an engine lubricating system.

[Prior Art] As a valve operating mechanism of this type, as a prior art of the present invention, for example, as shown in Japanese Utility Model Laid-Open No. 63-36605, a cylinder is formed at one end of a valve rocker arm.
It is known that the cylinder has a built-in valve lash adjuster. A valve lash adjuster is usually a cylindrical body mounted in a cylinder, a plunger fitted in the body so as to be able to move forward and backward, a hydraulic chamber provided between the body and the plunger, and a direction in which the plunger protrudes. The hydraulic chamber communicates with a pressure guiding passage in the valve rocker shaft via a check valve. When the valve is opened, the plunger is prevented from retracting due to the hydraulic pressure introduced from the pressure guiding passage into the hydraulic chamber, and when a valve clearance is generated when the valve is closed, the spring pushes out the plunger and the valve is pushed. It is designed to eliminate clearance.

Thus, with such a configuration, it is not necessary to adjust the valve clearance, maintenance-free operation can be performed, and noise generated from the valve train can be reduced.

[Problems to be Solved by the Invention] However, this type of lash adjuster has a complicated structure and a large number of parts, so that the cost is relatively high. Moreover, if such a structure is provided at the end portion of the valve rocker arm, the end portion becomes large and the weight is increased. For this reason,
The inertial weight of the valve rocker arm increases and the followability decreases.

The present invention aims to eliminate such a problem.

[Means for Solving the Problems] In order to achieve such an object, the present invention is directed to a valve rocker arm for converting a rotational movement of a cam into a forward / backward movement of a valve, and a valve rocker inserted through a bearing portion of the valve rocker arm. In an engine valve operating mechanism including a shaft, the bearing portion is formed in an elongated hole in a direction orthogonal to the axis, and sealing materials are arranged on both sides of the bearing portion to form a hydraulic chamber in one half of the cam side and the valve side. However, the hydraulic chamber is communicated with a pressure passage in the valve rocker shaft via a check valve.

[Operation] With such a structure, one half of the bearing portion on the cam side and the valve side, the outer peripheral surface of the valve rocker shaft facing the one half, and the seals arranged on both sides of the bearing portion. A hydraulic chamber is formed by the material, and the hydraulic pressure introduced into the hydraulic chamber during engine operation acts on the bearing portion. For this reason, if a valve clearance occurs when the valve is closed, the valve rocker arm moves to the cam side and the valve side due to the hydraulic pressure acting on one half of the bearing portion, thereby closing the valve clearance. Further, when the valve lift is started, the check valve closes the hydraulic chamber and prevents the valve rocker arm from moving to the side opposite to the cam and the valve.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

This valve operating mechanism includes a valve rocker arm 3 that converts the rotational movement of the cam 1 into an advancing and retracting movement of the valve 2, and a valve rocker shaft 4 that holds the valve rocker arm 3 swingably. A hydraulic chamber 5 for adjusting the valve clearance is provided between the valve rocker shaft 4 and the valve rocker shaft 4.

The valve rocker arm 3 has a slipper surface 3a formed in an arc at one end in sliding contact with the cam 1, and a valve pressing surface 3b formed in an arc at the other end in sliding contact with the stem head 2a of the valve 2. The valve rocker shaft 4 penetrates a bearing portion 3c provided approximately at the middle of both ends. The bearing portion 3c is formed as an elongated hole in a direction orthogonal to the valve rocker shaft 4, and the diameter of the narrowest portion is set to be slightly larger than the outer diameter of the valve rocker shaft 4.

The valve rocker shaft 4 is a hollow one having a perfect circular outer periphery, and a pressure guiding passage 4a communicating with a high pressure path of an engine lubrication system is provided inside thereof.

The hydraulic chamber 5 includes a half half 3d on the cam 1 side and the valve 2 side of the bearing 3c, an outer peripheral surface 4b of the valve rocker shaft 4 facing the half half 3d, and seals for closing both sides of the bearing 3c. It is composed of a seal ring 6 as a material, and is set to a dimension capable of obtaining an appropriate leakdown characteristic in the direction orthogonal to the axis. The seal ring 6 is
The valve rocker shaft 4 is mounted on the outer periphery of the valve rocker shaft 4 and is fixed to grooves 3e provided on both sides of the valve rocker arm 3. The hydraulic chamber 5 is communicated with the pressure guide passage 4a through an oil supply hole 4c provided in the valve rocker shaft 4. The oil supply hole 4c is formed in an inwardly tapered surface that widens toward the outer peripheral surface 4b of the valve rocker shaft 4, and a check ball 7 serving as a check valve is arranged in the middle thereof. Also, one half of the bearing 3c of the valve rocker arm 3 that does not form the hydraulic chamber 5, that is, the valve 2
In the other half on the opposite side, a sufficient clearance is provided between the seal ring 6 and the valve rocker arm 3, and the hydraulic chamber 5
The leaked oil is made easier to flow out.

According to such a configuration, the half half 3d on the cam 1 side and the valve 2 side of the bearing portion 3c of the valve rocker arm 3 is formed.
A hydraulic chamber 5 is formed by the outer peripheral surface 4b of the valve rocker shaft 4 facing the one-half half 3d and the seal rings 6 closing both sides of the bearing portion 3c, and a check ball 7 is formed in the hydraulic chamber 5. The hydraulic pressure is introduced from the pressure guide passage 4a via the pressure guide passage 4a. And the slipper surface of the valve rocker arm 3
When 3a is located on the base circle 1a of cam 1,
That is, when a valve clearance is generated when the valve 2 is closed, the valve rocker arm 3 is urged downward by the hydraulic pressure acting on the one half 3d of the bearing portion 3c facing the hydraulic chamber 5, and the valve clearance is adjusted to zero. . Further, when the valve 2 is opened, the check ball 7 closes the oil supply hole 4c and closes the hydraulic chamber 5 due to the friction caused by the reverse flow at the start of the valve lift. Therefore, when the valve is opened, the valve rocker arm 3 is prevented from moving to the side opposite to the cam 1 and the valve 2, and the valve lift is started at a predetermined timing.

Therefore, with such a structure, the structure of the valve rocker arm 3 can be made simple, and the number of parts can be surely reduced as compared with the conventional one having the adjusting function of this kind. . As a result, the cost can be reduced and the compact valve rocker arm 3 can be provided. Also,
Even when compared with a valve adjust screw, the number of parts is increased by one, and the valve clearance can be maintained free.

Moreover, according to such a structure, the valve rocker arm 3 can be made lighter in weight and the inertial performance rate about the shaft center can be reduced. Therefore, compared to the conventional one,
The inertial weight of the valve rocker arm 3 can be reliably reduced, and the followability can be improved.

Further, if the bearing portion 3c of the valve rocker arm 3 is formed in an oval long hole and the hydraulic chamber 5 is provided in one half 3d thereof, the sliding contact portion with the valve rocker shaft 4 can be reduced, It is possible to effectively suppress the occurrence of wear between them and improve the durability. Moreover, if the hydraulic chamber 5 is provided at the above-mentioned location, the valve rocker arm 3 can be swung so that the slipper surface 3a becomes uniform in the axial direction, and it is possible to prevent one-sided contact of the slipper surface 3a. Therefore, it is possible to prevent uneven wear of the cam 1 and the slipper surface 3a, and to loosen the parallelism of the slipper surface 3a, which has conventionally required a precise parallelism in the axial direction.

Furthermore, if a function to adjust the valve clearance is added to the axial center of the valve rocker arm 3, the valve pressing surface
The valve pressing surface 3b and the stem head 2a of the valve 2 can be in line contact with each other by making 3b an arc surface. For this reason, it is possible to prevent uneven wear due to point contact that tends to occur between the spherical valve pressing surface and the stem head of the valve, like the conventional rocker adjuster and valve rocker arm having the valve adjust screw, and improve wear resistance. You can also

Although one embodiment of the present invention has been described above, it goes without saying that the present invention is not limited to the above embodiment. For example, collars may be provided on both sides of the valve rocker arm, and the collar may form a seal member that closes both sides of the hydraulic chamber.

[Effect of the Invention] Since the present invention is configured as described above, the structure of the valve rocker arm having the function of adjusting the valve clearance by hydraulic pressure can be made simpler than the conventional one, and the number of parts can be ensured. Can be reduced.
As a result, it is possible to reduce costs and
A compact engine valve operating mechanism can be provided.

Moreover, according to the engine valve mechanism of the present invention,
It is possible to reduce the weight of the valve rocker arm and reduce the inertial performance rate about its axis. Therefore, the inertial weight of the valve rocker arm can be reliably reduced, and the followability can be effectively improved, as compared with the conventional one.

In addition, it is possible to reduce the portion where the valve rocker arm and the valve rocker shaft are in sliding contact with each other, and it is possible to effectively avoid one-sided contact between the cam and the valve rocker arm, so that it is possible to improve the wear resistance of these sliding portions. The durability can be improved.

[Brief description of drawings]

The drawings show one embodiment of the present invention, FIG. 1 is a partial sectional view of the entire structure, and FIG. 2 is a sectional view taken along the line II-II in FIG. 1 ... Cam 2 ... Valve 3 ... Valve rocker arm 3c ... Bearing part 3d ... One half 4 ... Valve rocker shaft 4a ... Pressure passage 5 ... Hydraulic chamber 6 ... Seal material (seal ring) 7 ... Check material (check ball)

Claims (1)

[Scope of utility model registration request] 1. A valve operating mechanism for an engine, comprising: a valve rocker arm for converting a rotational movement of a cam into a forward / backward movement of a valve; and a valve rocker shaft inserted through a bearing portion of the valve rocker arm. Is formed into a long hole, and seal materials are arranged on both sides thereof to form a hydraulic chamber in one half of the cam side and the valve side, and the hydraulic chamber is provided in the valve rocker shaft through a check valve. An engine valve mechanism characterized by being connected to a pressure guiding passage.