Valve operating mechanism of an internal combustion engine

Details Valve operating mechanism of an internal combustion engine Valve operating mechanism of an internal combustion engine

2000-08-17

2002-01-15

Lo, Weilun (Department: 3748)

Internal-combustion engines

Poppet valve operating mechanism

Spring

C123S188130

Reexamination Certificate

active

06338325

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a valve operating mechanism for a poppet valve of an internal combustion engine, said mechanism comprising a spring retainer made of light alloy such as Al alloy which is mounted to the poppet valve via steel cotters, thereby increasing load of falling the cotters out of the lower end of the spring retainer.
FIG. 6
illustrates an example of a known valve operating mechanism of an internal combustion engine, in which an A
1
alloy valve spring retainer
23
which has a taper bore
22
and a spring-retaining flange
23
a
is engaged with the upper end of a poppet valve
21
via a pair of steel cotters
24
. An annular bead
24
a
of each of the cotters
24
is engaged in an annular groove
21
a
of the poppet valve
22
so that the valve spring retainer
23
may not come out upwards.
Between the lower surface of the spring-retaining flange
23
a
and a cylinder head (not shown), a valve spring
25
is provided, and the poppet valve
21
is always urged upwards by the valve spring retainer
23
.
The numeral
26
denotes a rocker arm which is engageable on the upper end of the poppet valve
21
, and is moved up and down by a rotary cam (not shown) to open and close the poppet valve
21
. In the valve operating mechanism, the cotters
22
and the valve spring retainer
23
are integrally secured to the poppet valve
21
by wedge-like engagement of the cotters
24
with the bore
22
. To increase securing force, taper angle of the bore is decreased, and roughness of contact surface between the bore
22
and the cotters
24
is decreased to decrease frictional resistance, thereby strengthening wedge-like engagement.
However, in a valve operating mechanism which has a relatively low mechanical strength Al alloy valve spring retainer
23
, when the bore
22
is plastically deformed and expanded owing to increase in wedge-like engagement, the cotters
24
fall gradually owing to low frictional resistance of the contact surface between the bore
22
and the cotters
24
. The valve spring retainer
23
moves up gradually, so that load to the valve spring
25
is decreased to decrease the maximum rotation number of surging, so that engine performance is deteriorated.
When the cotters
24
fall deeply, the lower end of the valve spring retainer
23
is liable to cause cracking and to be damaged,. so that the cotters
24
come out. To solve the problem, the valve spring retainer
23
or the lower portion thereof increases in external diameter to increase rigidity and load of the cotters
24
.
However, the valve spring retainer
23
becomes larger to increase its weight. For Al alloy valve spring retainer made to lighten its weight, it will not be advantageous.
SUMMARY OF THE INVENTION
In view of the disadvantages as above, it is an object of the present invention to provide a valve operating mechanism for a poppet valve of an internal combustion engine to prevent a pair of cotters from falling out of a bore of a valve spring retainer.


REFERENCES:
patent: 4515346 (1985-05-01), Gaterman, III
patent: 4838218 (1989-06-01), Sato et al.
patent: 5357918 (1994-10-01), Hemmerlein et al.
patent: 5619961 (1997-04-01), Diggs
patent: 61-136106 (1986-08-01), None
patent: 63-52906 (1988-04-01), None
patent: 1-95502 (1989-06-01), None
patent: 2-87909 (1990-07-01), None
patent: 8-61026 (1996-03-01), None

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