Valve actuation linkage mechanism

Details Valve actuation linkage mechanism Valve actuation linkage mechanism

2001-10-30

2004-12-14

Denion, Thomas (Department: 3748)

Internal-combustion engines

Poppet valve operating mechanism

Rocker

C123S090400, C123S090410, C074S559000

Reexamination Certificate

active

06830022

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to valve trains in internal combustion engines. More particularly, this invention relates to valve actuation mechanisms using rocker arms and valve bridges to actuate intake and exhaust valves in a diesel engine.
BACKGROUND OF THE INVENTION
Internal combustion engines typically have rocker arms to actuate intake and exhaust valves, which permit air to enter and exit each cylinder. Commonly there are separate rocker arms to actuate a valve or pair of valves. Push rods cause the rocker arms to rotate or pivot and thereby actuate the valves. The push rods extend through the engine to connect to a camshaft. As the camshaft rotates, the push rods move the rocker arms to open and close the valves. The camshaft is designed to open and close the valves in conjunction with the cycling of the piston in the cylinder.
Recent valve actuation mechanism designs use rocker carriers and rocker arm assemblies with rocker arms made of plate material. For example, those disclosed in patent application Ser. No. 09/768,520 filed on Jan. 24, 2001, by Martin Zielke for a Rocker Carrier, and Ser. No. 09/769,610 filed on Jan. 25, 2001 by Danesh et al. for a Rocker Arm Assembly, which are hereby incorporated by reference. These patent applications are both assigned to the assignee of the present patent application, International Truck and Engine Corporation. The recent designs though improved over earlier designs have some drawbacks.
FIG. 1
illustrates a perspective view of a partial prior art valve actuation mechanism. There is shown a valve actuation linkage mechanism
100
generally comprising a valve bridge
10
, a pivot foot
20
, a pivot foot fastener
30
and a rocker arm
40
.
FIG. 2
shows how the partial valve actuation mechanism of
FIG. 1
, without the valve bridge, mounted on a rocker carrier
200
which will be mounted on a cylinder head (not shown) in an internal combustion engine. The rocker arms
40
and
240
are cooperatively mounted on the rocker carrier
200
through a corresponding rocker arm pedestal or fulcrum plate
220
and fastened to the rocker carrier
200
by hold down bolts
210
. The hold down bolts
210
allow the rocker arms
40
and rocker arm fulcrum plate
220
to be pre-installed to the rocker carrier
200
thereby decreasing engine manufacturing time and costs. The rocker carrier
200
shown would be mounted on one side or bank of a V-8 type engine. The rockers arms
40
and
240
shown in
FIG. 2
typically have the same configuration but differ in size.
FIG. 2
shows the exhaust rocker arm
40
longer and larger than the intake rocker arm
240
. However, length and size of the rocker arms
40
and
240
is determined by the location of the intake and exhaust valves in relation to the rocker arm assembly. The rocker arms could be the same or different sizes depending on a particular engine application.
Referring again to
FIG. 1
, the valve actuation linkage mechanism
100
could be used in an engine application having four valves per cylinder. The valve bridge
10
when actuated by the rocker arm
40
via the pivot foot
25
will act on a pair of valves, e.g., a pair of intake or exhaust valves (not shown). The rocker arm generally comprises a push rod cup
60
, a pivot ball cup
70
, a rocker arm aperture
80
, and a pivot foot end
55
having a pivot foot cup
50
. The pivot foot cup
50
accepts a pivot foot
20
secured by a pivot foot fastener
30
. The pivot foot fastener
30
secures the pivot foot
20
to the pivot foot cup
50
via a set of opposing pivot foot clamps
37
which are clamp or crimped on to the exterior surface of the pivot foot cup
50
.
During engine operation, a push rod (not shown) actuates the rocker arm
40
via the push rod cup
60
. The rocker arm
40
will pivot via a gage or pivot ball (not shown) in the pivot ball cup
70
. The pivot foot
20
will in turn actuate the valves (not shown) via the Valve Bridge
10
. The pivot foot
20
contacts and acts on the valve bridge
10
to actuate valve movement (not shown) in a particular cylinder. In particular, the pivot foot bottom
25
contacts the valve bridge
10
at a top bridge contact surface area
15
to actuate valve movement. The physical makeup and positioning of the valve actuation linkage mechanism
100
is such that the of the pivot foot bottom
25
is continuously sitting on or contacting the valve bridge
10
top contact surface area
15
. In this manner, rocker arm
40
movement and force is immediately translated, via the pivot foot
20
, to the valve bridge
10
.
As the rocker arm
40
moves and pivots during engine operation, the attached pivot foot pivot travels or cycles upward or downward in an arc motion. The pivot foot's
25
arcing motion and simultaneous mechanical contact on the valve bridge
10
results in friction wear between the pivot foot
20
and the bridge contact area
15
. In essence, the pivot foot bottom surface
25
travels on the bridge contact area
15
and exerts a force with both vertical
13
and horizontal
17
elements. As the rocker arm
40
pivots during engine operation, the pivot foot bottom surface
25
exerts both a vertical force
13
and a back and forth horizontal force
17
. The mechanical action between the pivot foot
20
and the valve bridge
10
results in excessive friction wear between the pivot foot contact surface
27
and the bridge contact area
15
. Additionally, the pivot foot fastener
30
encounters vertical
13
and horizontal
17
forces. This degrades and loosens the connection securing the pivot foot
20
to the rocker arm
40
pivot foot cup
50
. Moreover, the physical orientation and configuration of the rocker arm
40
, pivot foot
20
, pivot foot fastener
30
and valve bridge
10
prevent adequate oil lubrication of these interconnected and interactive parts, adding to the friction wear drawback of this design.
Thus, existing valve actuation linkage mechanisms suffer from excessive wear between the pivot foot and valve bridge at the point of contact or contact area. Accordingly, there is a need for a valve actuation linkage mechanism that can be pre-assembled and that reduces friction wear on the valve assembly during operation.
SUMMARY OF THE INVENTION
The present invention provides a valve actuation linkage mechanism for use in an internal combustion engine that reduces friction wear on the valve assembly during engine operation and can be pre-assembled resulting in decreased manufacturing time and cost. The valve actuation linkage mechanism comprises a rocker arm having a pivot rod cup, a pivot rod, a valve bridge having a pivot rod chamber, and a pivot rod retainer. The pivot rod comprises a pivot rod head, a pivot rod neck, a pivot rod body, and a pivot rod bottom. The valve bridge comprises a middle valve bridge section having the pivot rod chamber and at least one adjacent pivot rod retainer securing bore, a bottom valve bridge section, and a lubricant dimple in the pivot rod chamber. The pivot rod retainer is comprised of a pivot rod orifice having at least one pivot rod prong and at least one securing orifice.
The following drawings and description set forth additional advantages and benefits of the invention. More advantages and benefits are obvious from the description and may be learned by practice of the invention.


REFERENCES:
patent: 1438937 (1922-12-01), Arnold
patent: 4850315 (1989-07-01), Mallas
patent: 4856468 (1989-08-01), Speil et al.
patent: 5632237 (1997-05-01), Cornell et al.
patent: 5706771 (1998-01-01), Van Heyningen et al.
patent: 6138626 (2000-10-01), Speil
patent: 6273042 (2001-08-01), Perez et al.
patent: 6397805 (2002-06-01), Knickerbocker
patent: 6463898 (2002-10-01), Yates
patent: 6484682 (2002-11-01), Danesh et al.
patent: 6484683 (2002-11-01), Zielke

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