AU463598B2

AU463598B2 - Mechanical lash adjuster for overhead cam engines

Info

Publication number: AU463598B2
Application number: AU50056/72A
Authority: AU
Inventors: F. Bergmann And David L. Coates Paul
Original assignee: Johnson Products Inc
Current assignee: Johnson Products Inc
Priority date: 1972-02-24
Filing date: 1972-12-14
Publication date: 1975-07-31
Also published as: DE2300459A1; CA973043A; JPS4898211A; FR2173525A5; US3791355A; IT972667B; BR7300865D0; AU5005672A; GB1366979A

Description

50,056/72 In the conversion of a "stock" or conventional overhead cam automobile engine to a "high-performance" engine, in addition to the replacement of the cam shaft; boring to increase valve opening, cylinders, and like parts; it is additionally sometimes advisable to replace the conventional hydraulic lash adjusters with a mechanical or "solid" adjuster. Solid adjusters are generally threadably received directly in the engine cylinder head and it is therefore necessary to completely replace the cylinder head to accommodate the solid adjuster. This, of course, adds considerably to the expense involved in such conversion. There are, additionally, those individuals who while not seeking a high-performance engine, are desirous, for one reason or another, to replace the conventional hydraulic lash adjuster with a solid adjustment mechanism. In either event, it is necessary and desirable to provide a means for quickly and simply making such replacement without unnecessary expense.

The present invention therefore provides a mechanical lash adjuster for replacing a hydraulic lash adjuster in an internal combustion engine having an overhead cam, a rocker arm forming a socket, and a lash adjuster mounted in a cylindrical opening formed in the cylinder head of the engine supporting said rocker arm at said socket, said replacement mechanical lash adjuster comprising:

a free-fitting insert axially slidable into and freely rotatable in said cylinder head opening, said insert having a threaded opening therein;

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a screw member threadably received in said insert;

said screw member having means at one end thereof for

supporting said rocker arm; said insert and said screw

member forming cooperative adjustment means for varying

the effective length of said lash adjuster to take up

slack in the valve train of said engine; and

locking means for said insert to prevent rotation

of said insert during adjustment of the valve lash.

Other important objects, advantages, and features

of the present invention will become readily apparent to

those skilled in the art upon reading the following

specification and with reference to the accompanying

drawings.

The invention will now be described with reference

to the accompanying drawings in which:

Fig. 1 is a cross-sectional, somewhat schematic,

representation of an overhead cam valve train

incorporating a lash adjuster according to the

invention;

Fig. 2 is a partial top plan view of the apparatus

as shown in Figure 1 with the rocker arm removed;

Fig. 3 is a view illustrating a pair of adjacent

lash adjustment mechanisms having retaining means for

preventing movement of the adjuster in the cylinder

head;

Fig. 4 is a side view of the retaining means

shown

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50,0 5 6n2 in Fig. 3; Fig. 5 is a view similar to Figure 3 illustrating an alternate retaining means; and

Fig. 6 is a partial side view of the retaining means shown in Fig.

Referring now to Figures 1 and 2 of the drawings, a valve 2 having a spring 4 and a retainer 6 is actuated by rocker arm 8 through a cam shaft 10 and cam 12. The rocker arm 8 pivots about a socket 14 on a lash adjuster 16. A- cross sectional portion of the cylinder head of a conven-

tional engine is illustrated by the numeral 20. An opening 22 is provided in the cylinder head 20 and normally accommo- dates a hydraulic lash adjuster (not shown). Oil is con- ventionally supplied to the hydraulic lash adjuster through

an oil gallery 24 opening into one of the side walls of the

recess 22 for operation in a conventional manner well known to those skilled in the art.

The adjuster assembly 16 of the present invention includes a threaded sleeve member or insert 26 adapted for

insertion in the opening 22 in the cylinder head 20. The sleeve member 26 has a diameter slightly less than the

diameter of the opening 22 such that the sleeve may be

easily slipped into place. The sleeve is internally threaded throughout the greatest portion of its length 28 to receive an adjusting screw 30, preferably a self-locking

screw. The lower end of the screw 30 is threaded as indicated at 32 for adjustable setting within the threaded

portion 28 of the sleeve 26. The upper portion of the screw is provided with a rounded head 34 for rotational

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engagement with the socket 14 on the rocker arm 8. Below the head and above the threaded portion 32, the screw has

machined flat surfaces 36 preferably in the shape of a

hexagon for engagement with an open-end wrench during the

adjustment thereof. A flat surface 38 is also machined in the outer diam-

eter of the sleeve 26 near the top or opened end portion

for engagement with retaining means as will be more fully

described hereinafter.

Referring now to Figures 3 and 4, a pair of adjacent

adjusters are illustrated. The sleeve members 26 are turned

within the opening 22 such that flat areas 38 of each sleeve

extend along one side thereof in alignment with the flat

areas on the adjacent sleeve. A retaining member 42 having

outwardly extending U-shaped arm members 46 thereon is

secured to the cylinder head between the adjacent sleeves

26 by means of a screw 44. The arm members 46 extend out-

wardly and slightly upwardly from the screw 44 and are

adapted to engage the machined flat surface 38 on the

sleeves 26. Rotational movement of the sleeves within the

openings 22 is prevented because of the abutting relation-

ship between the machined flat surfaces 38 and the arm

members 46.

Referring briefly to Figures 5 and 6, an alternate

retaining means 50 is shown positioned between a pair of

adjacent sleeve members 26. In this embodiment, a machined

flat surface 38 need only be provided at one side of the

sleeve 26 and the sleeves are positioned so that the flat

areas are parallel to each other. The retaining member

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50,0 5 6n2

in the shape of a is positioned centrally between the sleeves 26 such that its outer surfaces contact the

machined flat areas 38 of each sleeve to prevent rotation of the sleeve 26 while adjustments are made.

Lash adjustment of the rocker arm with respect to

the valve stem 2 is accomplished in a conventional manner

by utilizing a feeler gauge between the rocker arm 8 and

the cam shaft 12. The adjustment itself is accomplished by placing a wrench over the hexagon-shaped portion 36 and

turning the screw within the sleeve to change the effective

length of the screw 30 to thereby adjust the valve lash

between the rocker arm 8 and the cam shaft 12. The retain- ing means illustrated in Figures 3 through 6 prevents

rotation of the sleeve 26 within the opening 22 while

adjustment is made. The threaded portion of the screw 16 is preferably self-locking so that a lock-nut is not re-

quired to keep the screw from changing its setting and to

require the use of only one wrench.

From the foregoing description and drawings, it will

become readily apparent to those skilled in the art that

the present invention provides an extremely simple yet

effective replacement mechanical lash adjuster for use in

overhead cam shaft engines. The mechanical lash adjuster is particularly adaptable for the replacement of a conven-

tional hydraulic lash adjuster in the construction of and

conversion to a high-performance engine. In addition, the present invention provides a unique retaining means for a lash adjuster wherein relative movement will not occur

between the sleeve or insert portion of the adjuster and

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the cylinder head of the engine. The lash adjuster of the present invention is simple in its construction, inexpensive to manufacture, and consequently, relatively inexpensive to the consumer. Its ease of assembly and insertion within an existing engine effects even greater savings in labor,

costs alone. While the preferred embodiment of the invention has been illustrated in detail, it will be recognized by those skilled in the art that other modifications incor- porating the teachings hereof may be readily made in light of this disclosure. Accordingly, all modifications embody- ing the principles thereof are to be considered as included in the appended claims unless these claims by their lan- guate expressly state otherwise.

Claims

50,0566n2 THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:-- 1. A mechanical lash adjuster for replacing a

.hydraulic lash adjuster in an internal combustion engine

having an overhead cam, a rocker arm forming a socket,

and a lash adjuster mounted in a cylindrical opening

formed in the cylinder head of the engine supporting

said rocker arm at said socket, said replacement mechani-

cal lash adjuster comprising:

a free-fitting insert axially slidable into and

freely rotatable in said cylinder head opening,

said insert having.a threaded opening therein;

a screw member threadably received in said insert,

said screw member having means at one end thereof

for supporting said rocker arm; said insert and

said screw member forming cooperative adjustment

means for varying the effective length of said

lash adjuster to take up slack in the valve

train of said engine; and

locking means for said insert to prevent rotation

of said insert during adjustment of the valve lash.
2. The lash adjuster as defined in claim 1 and

further including self-locking thread means on one of said

screw and said insert.
3. The apparatus as defined in claim 1 wherein

said insert has a flat area on an outer peripheral surface

thereof and said locking means includesmeans secured to said cylinder head abutting said flat area to prevent

rotation of said insert in said cylinder opening. 463.598

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4. Mechanical lash adjuster for overhead cam engines substantially as hereinbefore described with

reference to the accompanying drawings.

DATED this 3rd day of July, 1975.

JOHNSON PRODUCTS INC. By its Patent Attorneys

CLEMENT HACK CO.,

Fellows Institute of Patent Attorneys of Australia.

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