JPH04116208A - Valve clearance regulating device of engine - Google Patents

Abstract

PURPOSE:To facilitate the valve clearance regulating work by providing a plurality of sequentially changing two-plane distances of a polyhedron shim, thereby providing the function of a plurality of cylindrical shims. CONSTITUTION:A valve stem end 1a of a discharge valve 1 is pushingly pressed against the back side of a tappet 7 through a polyhedron shin 6, and lets the surface of the tappet 7 to follow up the rotation of a can 3. A polyhedron shim 6 has three two-plane distances A, B and C. These distances are made different and thin design is equivalent to preparation of three kinds of cylindrical shim. In the valve clearance regulating work, it thus is only necessary to select the direction of the polyhedron shim 6 appropriately which is grasped by the valve stem end 1a and the tappet 7. The valve clearance regulating work can be easily achieved.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a valve clearance adjustment device for a valve system installed in a four-stroke automobile engine or the like.

[Conventional technology]

As a palf system for automobile 4-stroke engines,
The so-called DOHC type is becoming popular, in which two camshafts for intake and exhaust are placed above the cylinder, and the intake and exhaust valves are opened and closed via tappets by cams installed on each camshaft. . In such an OHC type valve system, as a device for adjusting the valve clearance, a shim is interposed between the tappet that follows the cam and the valve stem end, or the device disclosed in JP-A-57-179313 It is conventionally known that an adjustment screw is interposed between the tappet and the valve stem end as described in . [Problems to be Solved by the Invention] Incidentally, the shim interposed between the tappet and the valve stem end is generally cylindrical, and its thickness, that is, the dimension between both end surfaces, is determined to be a predetermined dimension. . Therefore, when adjusting the valve clearance, it is necessary to prepare a plurality of cylindrical shims having slightly different end-to-end dimensions, and the adjustment work is troublesome. In addition, as described in the above-mentioned publication, the equivalent inertia mass is thicker (and the limit rotation speed of the valve system Therefore, it is an object of the present invention to provide an engine valve clearance adjustment device that allows adjustment work to be easily performed without reducing the critical rotational speed of the valve system.

[Means to solve problems] For this purpose, the present invention provides an engine valve clearance adjustment device in which a shim is interposed between a tappet that follows an overhead cam and a valve stem end. It is characterized by a polyhedral shim in which the dimensions between each two sides are different in sequence. [For production]

In such a means, the - polyhedral shims have a plurality of sequentially different inter-plane dimensions and have the functions of a plurality of cylindrical shims. Therefore, the valve clearance can be easily adjusted by appropriately selecting the dimensions between the two faces of the - polyhedral gyms. Furthermore, since the polyhedral shim can have a smaller equivalent inertial mass than a conventional adjustment screw, the critical rotational speed of the valve system will not be reduced.

【Example】

Hereinafter, one embodiment of the present invention will be specifically described with reference to the accompanying drawings. In FIG. 1 showing, for example, an exhaust valve system of a four-stroke engine having a DOHC type valve system, reference numeral l indicates an exhaust valve that opens and closes an exhaust boat 2 of the cylinder head, and reference number 3 indicates the valve stem end la side of the exhaust valve l. This is a cam placed in the The exhaust valve 1 is biased so that the exhaust boat 2 is always closed by a spring retainer 4 mounted near the valve stem end la engaging the moving end of the valve spring 5. The pulp stem end Ia of the ft exhaust valve l presses against the back surface of the tappet 7 via the polyhedral shim 6, causing the surface of the tappet 7 to follow the rotation of the cam 3. Here, the polyhedral shim 6 is, for example, a dice-shaped hexahedron as shown in FIG. 2, and is fitted into a square recess 7a formed on the back surface of the tappet 7 to prevent displacement. ing. This polyhedral shim 6 has three sets of two parallel faces, and the dimensions A and B between the two faces of each set.
, C are different by minute dimensions, for example, A=B+0.02m, C=BO,02m when B is the reference dimension. In the above configuration, the - polyhedral shims 6 have, for example, three dimensions A, B, and C, and each dimension is, for example, 0.02w.
Since each shim is different, it is equivalent to preparing three cylindrical shims. Therefore, when adjusting the valve clearance,
It is only necessary to appropriately select the direction of the polyhedral shim 6 held between the pulp stem end 1a and the tappet 7, and the valve clearance adjustment work is easily performed. In the above embodiment, the polyhedral shim 6 was shaped like a dice, but as shown in FIG. Alternatively, E, F, and G may be made to differ by minute dimensions.

【Effect of the invention】

As explained above, according to the present invention, the - polyhedral shims have a plurality of sequentially different inter-plane dimensions and have the functions of a plurality of cylindrical shims. Therefore, the valve clearance can be easily adjusted by appropriately selecting the dimension between the two faces of each polyhedral shim. Furthermore, since the polyhedral shim can have a smaller equivalent inertial mass than a conventional adjustment screw, the critical rotational speed of the valve system will not be reduced.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a valve clearance adjustment device according to an embodiment of the present invention, FIG. 2 is a perspective view of a polyhedral shim in one embodiment, and FIG. 3 is a perspective view showing a modified example of the polyhedral shim. l...Exhaust valve, la...Valve stem end, 2...Exhaust port, 3...Cam, 4...Spring retainer, 5...Pulp spring, 6...Polyhedral shim, 7 ... Tappet, 7a... Recess, 8... Polyhedral shim.

Claims (1)

[Claims] In an engine valve clearance adjustment device in which a shim is interposed between a tappet that follows an overhead cam and a valve stem end, the two opposing surfaces of the shim are parallel and the dimensions between each two surfaces are sequential. An engine valve clearance adjustment device characterized by having different polyhedral shims.