Valve opening and closing mechanism in engines

Details Valve opening and closing mechanism in engines Valve opening and closing mechanism in engines

1999-08-09

2001-08-21

Leung, Philip H. (Department: 3742)

Internal-combustion engines

Poppet valve operating mechanism

C123S090160, C123S090170

Reexamination Certificate

active

06276315

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a valve opening and closing mechanism in engines. In particular, the present invention relates to the valve opening and closing mechanism in engines which does not require any adjustment work of tappet clearances.
2. Prior Art
In automotive engines, as shown in
FIG. 1
, there are provided with rocker arms
2
and
3
which are actuated by means of cams
1
. The rocker arms
2
and
3
are provided with through holes at each one end and through which push rods
5
,
5
are inserted, respectively. The rocker arms
2
and
3
rock consecutively as the cams
1
rotate.
For instance, when the push rod
5
in gas exhaust side advances, a valve stem
11
moves downward against the force of a valve spring
12
to open a valve
10
. Whereas, when the push rod
5
returns backward, the valve stem
11
moves upward by means of the force of the valve spring
12
to close the valve
10
. This construction of the valve mechanism is substantially same in gas intake side consisting of a valve
20
, a valve stem
21
and a valve spring
22
.
In practical operation of engines, the valve
10
of this valve opening and closing mechanism is expanded due to the heat generated in actual operation of engines. As shown in
FIG. 2A
, when the valve
10
is heat expanded, the lower end of said valve
10
moves downward by contacting the head of the valve stem
11
with the lower end portion of the push rod
5
in the rocker arm
3
and, as shown in
FIG. 2B
, a clearance B is generated between the valve
10
and a combustion chamber
30
. The gas in the combustion chamber
30
is thus leaked to disturb satisfactory operation of engines.
In order to avoid such unfavorable condition, a tappet clearance TC is formed between the valve
10
and the push rod
5
in conventional engines. This is shown in FIG.
1
B. When the valve
10
is heat expanded in actual operation of engines and a displacement due to such heat expansion is generated, it is absorbed by means of the tappet clearance TC.
Practically, when engines are assembled, an adjustment screw
41
is rotated by means of a screwdriver
42
so that a predetermined clearance of TC between the valve
10
and the push rod
5
may be attained. This adjustment work of the tappet clearance TC is achieved by a workman. Various thickness gauges and some differential.pressure gauges are applied for the adjustment work (not shown in FIG.
1
B).
However, there have been observed some defects in the adjustment work of the conventional tappet clearance TC. It always needs an extra workman to adjust the tappet clearance. There also have been observed some adjustment errors or unintentional disregarding of adjustment work. As thickness gauges are used by workman, an accurate adjustment cannot be expected. The adjustment work also requires long time.
Further, due to an existence of the tappet clearance TC, the push rod
5
hits the valve stem
11
when said valve
10
is pressed to be opened. In this occasion, the tappet noises are generated. This is also a problem inevitable.
Apart from the aforementioned tappet clearance adjustment work there has been a system called an oil tappet. This system applies a hydraulic pressure to automatically adjust tappet clearances. However, such oil tappet system requires some liquid passages. Arrangement of the liquid passages is rather complex. It is, therefore, difficult to apply said system to applicant's HONDA V-TEC engine.
The object of the present invention is to offer a valve opening and closing mechanism which is easy to be applied to somewhat complex engines like the HONDA V-TEC engine. The valve opening and closing mechanism according to the present invention does not require any adjustment work of tappet clearances. A clearance between the push rod and the valve is eliminated. Unfavorable effects due to the adjustment work by workman are eliminated.
SUMMARY OF THE INVENTION
In a valve opening and closing mechanism in engines consisting of cams, rocker arms, push rods, valves, valve springs, the present invention provides a circlip on the top portion of the push rod of the rocker arm, a head of said push rod and an end of a valve stem are contacted, a heat expansion displacement absorbing mechanism is provided, the heat expansion displacement absorbing mechanism being provided in a through hole of the rocker arm at its one end, a tapered portion having a smaller diameter as it goes away from the valve and a push rod control means which is movable along the longitudinal direction of said push rod are located between such tapered portion and the push rod.
There are provided with return springs to absorb displacement of the valve due to heat expansion to push the head of the push rod toward the valve by means of a force weaker than that of the valve springs. In this occasion said push rod control means actuate as a receiver of the force. When the valve is opened, said push rod control means moves away from the valve with respect to the rocker arms and is placed between said rocker arm and said push rod, said push rod advances integral with said rocker arm. When the valve is closed, said push rod control means approaches said valve with respect to the rocker arm and said push rod comes in uncontrolled condition. Said rocker arm contacts the circlip and then the push rod returns backward.


REFERENCES:
patent: 4539953 (1985-09-01), Sasaki et al.
patent: 4598674 (1986-07-01), Nono et al.
patent: 4617880 (1986-10-01), Yoshizaki
patent: 4676203 (1987-06-01), Nouno
patent: 4706620 (1987-11-01), Gill
patent: 4903651 (1990-02-01), Matsuura et al.
patent: 4911112 (1990-03-01), Oikawa et al.
patent: 5060605 (1991-10-01), Yamazaki
patent: 5148783 (1992-09-01), Shinkai et al.
patent: 5327860 (1994-07-01), Kruger
Patent Abstract of Japan, Pub. No. 10218353, Pub. Date Aug. 18, 1998.
Patent Abstract of Japan, Pub. No. 06310393, Pub. Date Nov. 4, 1994.

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