Valve spring retainer and a valve operating mechanism

Details Valve spring retainer and a valve operating mechanism Valve spring retainer and a valve operating mechanism

2001-08-03

2001-11-06

Lo, Weilun (Department: 3748)

Internal-combustion engines

Poppet valve operating mechanism

Spring

C123S188130, C251S337000

Reexamination Certificate

active

06311661

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates a valve spring retainer and a valve operating mechanism in an internal combustion engine.
FIG. 10
is one example of a conventional valve operating mechanism in an internal combustion engine, in which a valve spring retainer
3
is mounted at the upper end of a poppet valve
1
by a pair of cotters
2
,
2
. A valve spring
4
is provided between the lower surface of an outer flange
3
a
of the valve spring retainer
3
and a cylinder head (not shown), so that the poppet valve
1
is always energized upwards by the valve spring
4
.
The numeral
5
denotes a rocker arm which is engaged on the axial end of the poppet valve
1
and which is moved up and down by a rotary cam (not shown), so that the poppet valve
1
is opened and closed.
The flange
3
a
of the valve spring retainer
3
of the valve operating mechanism has a horizontal lower surface perpendicular to an axis of the valve spring retainer
3
, and is adapted to contact the upper surface of the valve spring
4
when the valve spring
4
is equipped.
It is inevitable to wear the lower surface of the flange
3
a
of the retainer
3
owing to relatively rotational or radial movement of the valve spring
4
caused by vibration when the poppet valve is seated.
Especially, in an automobile engine which is accelerated or decelerated frequently, as illustrated in
FIG. 11
, when the valve spring
4
is compressed, the uppermost winding is twisted outwards as shown by a downward arrow, or the flange
3
a
is bent upwards by reaction force to compression as shown by an upward arrow when the valve spring
4
is compressed.
In the conventional valve spring retainer
3
in which the lower inner surface of the flange
3
a
is horizontal, the inner upper circumference of the first winding which is horizontal at the upper end of the valve spring is engaged with the lower surface of the flange
3
a
, so that a larger surface pressure is applied.
Thus, as shown in
FIG. 12
, at the beginning of operation, the lower inner portion of the flange
3
a
locally wears, and develops outwards as shown by dotted lines. Especially, in the valve spring retainer
3
made of Al alloy for decreasing weight, wear develops rapidly.
Also, owing to vibration in opening and closing of the poppet valve
1
or surging in the valve spring
4
, the flange
3
a
of the retainer
3
is rotated with respect to the valve spring
4
, thereby causing contact surfaces to wear away. Especially, in the Al alloy valve spring retainer
3
for lightening, wear to the valve spring retainer
3
becomes larger.
As wear becomes larger, setting load of the valve spring
4
becomes smaller to decrease the maximum rotation speed of surging, thereby decreasing engine performance. Depending on degree in wear, it becomes necessary to replace the retainer
3
with a new one.
SUMMARY OF THE INVENTION
In view of the disadvantages in the prior art, it is an object of the present invention to provide a valve spring retainer in which the lower surface of a flange is modified in shape to decrease wear, thereby increasing durability and reliability.
It is another object of the present invention to provide a valve operating mechanism of an internal combustion engine in which a valve spring retainer is prevented from rotation with respect to a valve spring to keep wear of the contacting surfaces at minimum.


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patent: 4993376 (1991-02-01), Fukutome et al.
patent: 5884596 (1999-03-01), Hara et al.
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patent: 10-317926 (1998-12-01), None
patent: 2000-161029 (2000-06-01), None

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