JPH0213121B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a valve train for an overhead cam (OHC) type engine using a center pivot type hydraulic latch adjuster structure.

(Prior Art) In general, when providing so-called valve clearance in the valve train of an engine, if the valve clearance is not maintained properly, noise will increase. It is known that noise can be reduced by automatically absorbing changes in valve clearance due to thermal expansion, wear, etc., using a valve body.

As a valve train using such a hydraulic lash adjuster structure, for example, Japanese Patent Application Laid-Open No. 57-165613
As described in the above publication, there is a center pivot type rocker arm in which a hydraulic pivot is provided above the rocker arm as a fulcrum, and the rocker arm is hydraulically adjusted for latch adjustment.

(Problem to be Solved by the Invention) However, in such a valve train, it is necessary to fit the hydraulic pivot into the holding frame and then assemble it, and at the same time, it is necessary to assemble the hydraulic pivot inside the valve in a lifted state. Since the holding frame, which is difficult to assemble, is attached to the camshaft bearing with bolts, it is weak in strength and has problems in terms of installation accuracy.

The present invention has been made in view of the above points, and provides a hydraulic latch adjuster structure with excellent assembly ease.
The object of the present invention is to provide an engine valve train that has sufficient strength and can be mounted with high precision.

(Means for Solving the Problems) The present invention includes a cylinder head rotatably provided with a camshaft, the movement of the cam of the camshaft being transmitted to the intake and exhaust valves via a rocker arm,
The rocker arm is supported by a hydraulic latch adjuster structure having a fulcrum member that presses the back surface of the rocker arm opposite to the cam and valve contact portion, and the hydraulic latch adjuster structure is supported by a support member. This invention relates to improvements to the valve train for engines supported by

In order to achieve the above object, the present invention provides that the support member includes a support part that is integrally formed with a cam cap of a camshaft and has a storage hole for storing a hydraulic lash adjuster structure therein; The storage hole is characterized by comprising a lid member which is mounted and fixed and closes the upper opening of the storage hole.

(Function) By dividing the support member into a support portion having a storage hole and a lid member that closes the upper opening of the storage hole,
The hydraulic lash adjuster structure can be easily attached to the storage hole through the upper opening, and the mounting strength and accuracy are improved by forming the support portion integrally with the cam cap.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

In FIGS. 1 to 6, cylinder head 1
A combustion chamber 2 for each cylinder is formed in the combustion chamber 2, and an intake port 3 and an exhaust port 4 are opened in the combustion chamber 2. The opening of the intake port 3 has an intake valve 5 that opens and closes the intake port 3 at predetermined timing.
However, exhaust valves 6 for opening and closing the exhaust ports 4 at predetermined timings are disposed at the openings of the exhaust ports 4, respectively.

A valve operating mechanism 7 consisting of a rocker arm type overhead cam mechanism for opening and closing an intake valve 5 and an exhaust valve 6 is provided above the cylinder head 1. This valve train 7 extends in the direction of the center line of the cylinder head 1 and connects to the engine crankshaft (not shown).
It has a single camshaft 8 which is rotationally driven by the camshaft 8, and the camshaft 8 has intake and exhaust valves 5,
Cam surfaces 8a corresponding to 6 are formed. Further, a valve spring 10 is provided for each valve 5, 6, which urges each valve 5, 6 slidably supported by a valve guide 9 in the valve closing direction (upward in FIG. 1).
Then, one end (cam) abuts the cam surface 8a of the corresponding camshaft 8, and the other end (cam contact portion) abuts the valve stems 5a, 6a of each valve 5, 6, so that the cam surface 8a of the camshaft 8 abuts. The rocker arm 1 includes a rocker arm 11 that can be oscillated to transmit movement to each valve 5, 6, and a hemispherical tip 12a that is fitted and held in a supporting member 13 (described later) so as to be slidable in the vertical direction.
A fulcrum member 12 is provided which fits into and abuts on the spherical recess 11a in the intermediate portion of the rocker arm 11, thereby forming a fulcrum of the rocker arm 11.
Due to the rotation of the rocker arm 11, the fulcrum member 12
Each valve 5, 6 swings around the tip 12a as a fulcrum.
is now open and closed. This fulcrum member 1
A hydraulic tappet 15 is housed inside the hydraulic tappet 2, and the hydraulic tappet 15 is moved through a return member 20 by a spring 19 interposed between the fulcrum member 12 and the hydraulic tappet 15 (movable member 22 to be described later). A hydraulic latch adjuster structure A is configured which is always urged upward and thereby absorbs valve clearance.

Reference numeral 13 denotes a support member, which includes a plurality of cam caps 14 that constitute bearings for the camshaft 8 together with the concave portion of the cylinder head 1, and a hydraulic latch adjuster structure A for intake and exhaust of each cylinder that is formed integrally with the support member. Support part 16 having storage hole 16a
and a lid member 18 that is fixed to the support portion 16 with bolts 17, 17, . . . and closes the upper opening 16b of each storage hole 16a.

The hydraulic tappet 15 includes an outer cylindrical member 21 that is fitted into the fulcrum member 12 and whose upper end surface is in contact with the lid member 18, and an outer cylindrical member 21 which is slidably fitted into the outer cylindrical member 21 and whose lower end surface is the fulcrum member. The movable member 22 is in contact with the rod portion 12b of 12, and the inner cylinder member 24 is fitted into the movable member 22 and abuts the outer cylinder member 21 at one end, forming an oil reservoir chamber 23 therewith. Therefore, the oil chamber 2 is formed between the movable member 22 and the inner cylinder member 24.
5 is formed. The inner cylindrical member 24 includes a check ball 26 and springs 27, 28 at a position facing the communication hole 24a below the lower wall thereof, and oil flows from the oil chamber 25 into the oil reservoir chamber 23 through the communication hole 24a. A check valve B is provided to prevent this from happening.

Further, a communication hole 12c is formed in the peripheral wall of the fulcrum member 12 at a position corresponding to an opening 29a of an oil passage 29 formed in the support member 13 and communicating with an oil pump (not shown). Another communication hole 21a is also formed in the peripheral wall of the outer cylinder member 21 at a position corresponding to the communication hole 12a. Furthermore, the upper part of the movable member 22 has a circumferential recess 22a that communicates with the communication hole 21a, and the upper part of the inner cylinder member 24 has a notch 24 that communicates the circumferential recess 22a with the oil chamber 23.
b are formed respectively.

Therefore, the oil passage 29 is smaller than the oil pump.
The oil pumped through the opening 29a, the communication holes 12a, 21a, the circumferential recess 22a, and the notch 24
b. The oil is supplied into the oil chamber 25 through the oil reservoir chamber 23 and check valve B. As a result, the distance between the outer cylindrical member 21 and the inner cylindrical member 24 and the movable member 22 becomes larger, and the fulcrum member 12 is pressed and slid toward the rocker arm 11 with good followability.
Valve clearance is prevented from occurring.

Note that 30 is a support member 13 attached to the cylinder head 1.
Bolts 31 are for attaching and fixing the head cover 32.
Attachment hole 1 of the lid member 18 with the bolt that attaches and fixes the
8a and is screwed into the support member 13.

With the above structure, after the support part 16 of the support member 13 is attached to the cylinder head 1, the hydraulic latch adjuster structure A is inserted into the storage hole 16a of the support part 16, and the cover member 18 is inserted. It can be assembled with the simple operation of mounting, eliminating the need to assemble it all at once as in the past, and for cylinders that need to be assembled with the valve lifted, the lid member can be easily assembled without using a special lifting device. 18
It can be lifted during assembly, improving assembly work efficiency.

Further, since the support part 16 of the support member 13 that supports the hydraulic lash adjuster structure A is formed integrally with the cam cap 14 of the camshaft 8, the strength of the support part 16 is compatible with the strength of the cam cap 14. In addition, since the relative position between the support portion 16 and the cap 14 is constant, the fulcrum member 12 and the rocker arm 11 (which constitute the hydraulic latch adjuster structure A) are The positional relationship with the spherical recess 11a) can also be accurately mounted, and the mounting accuracy is also improved.

Further, by configuring the lid member 18 separately from the support portion 16, it becomes possible to easily form the oil passage 29 by inserting a drill through the opening 16b.

In the embodiment described above, the lid member 18 and the head cover 32 are formed separately, but as shown in FIG. 7, it is also possible to form a head cover member 33 in which they are formed integrally.

(Effects of the Invention) Since the present invention is configured as described above, the ease of assembling the hydraulic lash adjuster structure is improved, and the mounting strength and mounting accuracy of the structure are also improved.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is an overall configuration diagram of an engine valve train, FIGS. 2 and 3 are sectional views of essential parts in the camshaft axis direction, and FIG. 4 is a camshaft axis diagram. 5 is a plan view of the support portion of the support member, FIG. 6 is a plan view of the lid member, and FIG. 7 is an explanatory view of a modified example. 1... Cylinder head, 7... Valve mechanism, 8...
...Camshaft, 11...Rotzker arm, 12
...Fullin member, 13...Support member, 14...Cam cap, 15...Hydraulic tappet, 16...Support portion, 16a...Storage hole, 18...Lid member, 33...
...Head cover member, A...Hydraulic latch adjuster structure.

Claims (1)

[Claims] 1 A camshaft is rotatably provided in the cylinder head, and the movement of the cam of the camshaft is transmitted to the intake and exhaust valves via a rocker arm, and the rocker arm presses the back surface of the rocker arm on the opposite side from the cam and valve contact portion. In the engine, the engine is supported by a hydraulic latch adjuster structure having a fulcrum member, and the hydraulic latch adjuster structure is supported by a support member, and the support member is integrated with a cam cap of a camshaft. It is characterized by being composed of a support part formed therein and having a storage hole therein for storing a hydraulic lash adjuster structure, and a lid member that is attached and fixed to the support part and closes the upper opening of the storage hole. Valve gear of the engine.