U.S. patent application number 09/778538 was filed with the patent office on 2002-08-08 for shaft brush for preventing coking in a gas management valve.
Invention is credited to Bircann, Raul A., Palmer, Dwight O..
Application Number | 20020104978 09/778538 |
Document ID | / |
Family ID | 25113696 |
Filed Date | 2002-08-08 |
United States Patent
Application |
20020104978 |
Kind Code |
A1 |
Bircann, Raul A. ; et
al. |
August 8, 2002 |
SHAFT BRUSH FOR PREVENTING COKING IN A GAS MANAGEMENT VALVE
Abstract
The present invention is directed to an annular metal-bristled
brush for cleaning the pintle shaft of a pintle valve, such as an
exhaust gas recirculation valve for an internal combustion engine,
to prevent coking and failure of the valve. The brush surrounds the
shaft, the tips of the bristles making contact with the shaft with
sufficient force to dislodge incipient coke deposits but with
insufficient force to inhibit the axial motion of the pintle shaft
in actuation. Preferably, the brush is disposed in an annular space
in the valve body between the pintle shaft bearing and the
gas-metering chamber such that the shaft is brushed in both
directions during each actuative cycle of the valve. Preferably,
the annular space is slightly larger both axially and radially than
the corresponding dimensions of the brush so that the brush is free
to float without binding the pintle shaft.
Inventors: |
Bircann, Raul A.; (Penfield,
NY) ; Palmer, Dwight O.; (Rochester, NY) |
Correspondence
Address: |
Delphi Technologies, Inc.
P.O. Box 5052
Mail Code 480414420
Troy
MI
48007
US
|
Family ID: |
25113696 |
Appl. No.: |
09/778538 |
Filed: |
February 7, 2001 |
Current U.S.
Class: |
251/129.15 |
Current CPC
Class: |
F02M 26/50 20160201;
F02M 26/67 20160201; F16J 15/3288 20130101; F02M 26/53 20160201;
Y10T 137/4273 20150401; F02M 26/74 20160201; F16K 51/00
20130101 |
Class at
Publication: |
251/129.15 |
International
Class: |
F16K 031/02 |
Claims
What is claimed is:
1. An anti-coking apparatus for a pintle shaft in a valve,
comprising an annular brush disposed in said valve and surrounding
said pintle shaft and having bristles disposed radially inwards
into contact with said pintle shaft to brush coking deposits from
said pintle shaft during axial actuation of said shaft in said
valve.
2. An anti-coking apparatus in accordance with claim 1 wherein said
valve includes an internal chamber from which said pintle shaft
extends and a shaft bearing disposed in a wall of said valve, and
wherein said brush is disposed between said chamber and said
bearing.
3. An anti-coking apparatus in accordance with claim 1 wherein said
brush comprises metallic bristles.
4. An anti-coking apparatus in accordance with claim 3 wherein said
metal is selected from the group consisting of stainless steel,
mild steel, and brass.
5. An exhaust gas recirculation valve for an internal combustion
engine, comprising an anti-coking apparatus for a pintle shaft in
said valve including an annular brush surrounding said pintle shaft
and having bristles disposed radially inwards into contact with
said pintle shaft to brush coking deposits from said pintle shaft
during axial actuation of said shaft in said valve.
6. An internal combustion engine, comprising an exhaust gas
recirculation valve for an internal combustion engine, said valve
having an anti-coking apparatus for a pintle shaft of said valve
including an annular brush surrounding said pintle shaft and having
bristles disposed radially inwards into contact with said pintle
shaft to brush coking deposits from said pintle shaft during axial
actuation of said shaft in said valve.
Description
TECHNICAL FIELD
[0001] The present invention relates to pintle-type valves; more
particularly to axially-operative pintle shaft valves for
permitting the controlled admission of exhaust gases into the fuel
intake manifold of an internal combustion engine; and most
particularly to such a valve having an annular shaft brush for
preventing coking of the portion of the pintle shaft which engages
the shaft bearing, thereby preventing coking product from entering
the bearing and causing seizure of the shaft.
BACKGROUND OF THE INVENTION
[0002] It is well known in the automotive art to provide a variable
valve connecting the exhaust manifold with the intake manifold of
an internal combustion engine to permit selective and controlled
recirculation of a portion of an engine's exhaust gas into the fuel
intake stream. Such recirculation is beneficial for reducing the
burn temperature of the fuel mix in the engine to reduce formation
of nitrogen and sulfur oxides which are significant components of
smog. Such a valve is known in the art as an exhaust gas
recirculation (EGR) valve.
[0003] Typically, an EGR valve has a valve body enclosing a chamber
disposed between a first port in the exhaust manifold and a second
port in the intake manifold; a valve seat dividing the chamber
between the two ports; a valve pintle shaft having a valve head
fitted to the valve seat and extending from the valve head through
a bearing mounted in a third port in a sidewall of the valve body;
a spring-retained bearing splash shield; and a solenoid actuator
mounted on the exterior of the valve body and operationally
connected to the outer end of the valve pintle.
[0004] A problem inherent to EGR valve applications is that the
managed fluid (exhaust gas) is moisture-laden, corrosive, and dirty
with particulates. Especially in diesel engines, the exhaust gas
can form coke-like deposits, known generally as coking, on surfaces
exposed to these materials including the valve chamber walls and
the head-actuating pintle shaft. The pintle shaft typically passes
through a journal bearing disposed in a wall of the valve body
which provides radial support and axial guidance to the shaft. To
minimize gas leakage along the shaft, the clearance between the
bore in the bearing and the pintle shaft typically is made as small
as is practical without causing significant drag on the axial
actuation of the pintle by the external actuator. If the valve is
normally closed, as is typical, a protected and clean portion of
the pintle shaft within the bearing bore must become extended into
the valve chamber when the pintle is actuated to open the valve and
admit exhaust gas into the valve chamber. The clean portion of the
pintle shaft may become coked, which coking material will be drawn
into the bearing bore when the valve is closed. Thus, a typical EGR
valve is undesirably vulnerable to becoming seized and inoperative
by coking of the pintle shaft during operation.
[0005] What is needed is a device which may be fitted to an EGR
valve that significantly reduces or eliminates coking of the valve
shaft without impairing efficiency, size, and performance of the
valve and actuator. Preferably, such a device is simple and
inexpensive to fabricate and install.
SUMMARY OF THE INVENTION
[0006] The present invention is directed to an annular
metal-bristled brush for cleaning the pintle shaft of a pintle
valve, such as an exhaust gas recirculation valve for an internal
combustion engine, to prevent coking and failure of the valve. The
brush surrounds the shaft, the tips of the bristles making contact
with the shaft with sufficient force to dislodge incipient coke
deposits but with insufficient force to inhibit the axial motion of
the pintle shaft in actuation. Preferably, the brush is disposed in
an annular space in the valve body between the pintle shaft bearing
and the gas-metering chamber such that the shaft is brushed in both
directions during each actuative cycle of the valve. Preferably,
the annular space is slight larger both axially and radially than
the corresponding dimensions of the brush so that the brush is free
to float without binding the pintle shaft.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The foregoing and other objects, features, and advantages of
the invention, as well as presently preferred embodiments thereof,
will become more apparent from a reading of the following
description in connection with the accompanying drawings, in
which:
[0008] FIG. 1 is an elevational cross-sectionai view of a prior art
EGR valve;
[0009] FIG. 2 is an enlarged and detailed view of area 2 in FIG.
1;
[0010] FIG. 3 is an elevational cross-sectional view of a portion
of a valve, like that shown in FIG. 2, equipped with an anti-coking
shaft brush in accordance with the invention; and
[0011] FIG. 4 is an elevational cross-sectional view of an improved
exhaust gas recirculation valve assembly incorporating an
anti-coking shaft brush in accordance with the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0012] The benefits afforded by the present invention will become
more readily apparent by first considering a prior art EGR pintle
valve. Referring to FIGS. 1 and 2, a prior art EGR valve 10
includes a valve body 12 having a valve seat 14 separating a first
chamber 16 from a second chamber 18, which chambers may communicate
with the exhaust and intake systems, respectively, of an internal
combustion engine (not shown) or the reverse. Valve head 20 is
disposed adjacent to seat 14 for selectively mating therewith to
open or to close communication between chambers 16 and 18. Valve
stem, or pintle, 22 extends from head 20 through an axial bore 24
in bearing 26 and is captured within armature 28 of solenoid
actuator 30. Bearing 26 is disposed in a port 27 in a wall of valve
body 12 and guides pintle shaft 22 in reciprocating motion to open
and close the valve when actuator 30 is energized and de-energized,
respectively.
[0013] Bearing 26 is provided with a circumferential flange 32
having a first axial face 34 for sealing against axial outer
surface 36 of valve body 12 to prevent leakage of gases
therebetween. A cup-shaped bearing splash shield 38 has an
inward-extending flange 40 with a central aperture 42 for passage
of stem 22, preferably without contact therebetween, and a
cylindrical skirt 44 extending axially to shield a substantial
portion of bearing 26 from external contaminants. Shield 38 is open
in a downwards direction to permit venting of any gases which may
leak along bore 24 during operation of the valve. Actuator 30 is
connected to valve body 12 via a plurality of bolts 46 extending
through a plurality of standoffs 48. A coil spring 50 surrounding
stem 22 is disposed within shield 38, being compressed between
actuator 30 and a second surface 52 on flange 32 for urging flange
32 to seal against surface 36 under all operating conditions.
Spring 50 also serves to urge shield 38 against surface 49 of
primary polepiece 51 of actuator 30 to prevent dust intrusion into
the actuator.
[0014] Referring to FIG. 3, a portion of an improved pintle-type
valve 60 is shown incorporating an annular pintle shaft brush 62 in
accordance with the invention. Valve body 12' is provided with a
stepped axial bore 27' for coaxially receiving bearing 26, brush
62, and shaft 22. The depth of bore 27' from surface 36 to step 64
is greater than the axial length of portion 66 of bearing 26 such
that a first annular space 68 is created surrounding shaft 22
between bearing 26 and valve chamber 18. Within space 68 is
disposed an annular brush 62 comprising metallic bristles 72
disposed radially inwards and retained by a folded metallic
retainer 74. A line of such brushes, in various sizes and having
bristles formed of various materials, is available, for example,
from Sealeze, a unit of Jason, Inc., Richmond, Va., USA. The
bristles preferably are formed of metal, for example, stainless
steel, mild steel, or brass. Other materials may be suitable in
some applications. The brush is disposed such that the bristles are
generally orthogonal to and radial of shaft 22. Preferably, the
outer diameter of brush 62 is slightly less than the diameter of
space 68 and the axial length of brush 62 is slightly less than the
axial depth of space 68, as shown in FIG. 3, such that brush 62 is
free to float slightly, both axially and radially, within space 68.
Preferably, the inner diameter of the annulus formed by the bristle
ends is substantially the same as the diameter of pintle shaft 22
to provide effective brushing action of the shaft while creating
minimal axial drag thereupon.
[0015] In operation, shaft 22 is forced into brushing contact with
the tips of bristles 72, allowing the shaft to be pulled through
the brush in both axial directions. In the retractive direction,
wherein the shaft is retracted from chamber 18 into the bearing,
any deposits on shaft 22 are brushed off. Preferably, bore 27" in
valve body 12' is somewhat larger than the diameter of shaft 22
creating a second annular space 75 therebetween such that deposits
brushed off of shaft 22 can fall by gravity back into chamber 18.
Thus, shaft 22 is kept free of deposits during actuation thereof,
and impairment of movement of the shaft in the bearing caused by
coke deposits on the shaft is prevented.
[0016] Depending upon bristle density, brush 62 can have a
secondary action as a shaft seal against particles being drawn
directly into bearing 26. However, for optimal scraping
effectiveness, a relatively low bristle density is preferred.
[0017] Referring to FIG. 4, an improved EGR valve 10' is shown
including anti-coking shaft brush 62. Valve 10' is shown connected
between the exhaust and intake manifolds 76 and 78, respectively,
of an internal combustion engine 80 for metering of exhaust gases
therebetween.
[0018] The foregoing description of the preferred embodiment of the
invention has been presented for the purpose of illustration and
description. It is not intended to be exhaustive nor is it intended
to limit the invention to the precise form disclosed. It will be
apparent to those skilled in the art that the disclosed embodiments
may be modified in light of the above teachings. The embodiments
described are chosen to provide an illustration of principles of
the invention and its practical application to enable thereby one
of ordinary skill in the art to utilize the invention in various
embodiments and with various modifications as are suited to the
particular use contemplated. Therefore, the foregoing description
is to be considered exemplary, rather than limiting, and the true
scope of the invention is that described in the following
claims.
* * * * *