U.S. patent application number 10/236738 was filed with the patent office on 2003-01-09 for apparatus for preventing coking in a gas management valve.
Invention is credited to Bircann, Raul A., Geib, Todd P., Marlowe, Christopher B., Smith, Craig D..
Application Number | 20030006390 10/236738 |
Document ID | / |
Family ID | 25113696 |
Filed Date | 2003-01-09 |
United States Patent
Application |
20030006390 |
Kind Code |
A1 |
Smith, Craig D. ; et
al. |
January 9, 2003 |
Apparatus for preventing coking in a gas management valve
Abstract
An integral pintle shield and annular scraper for protecting and
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 scraper surrounds the shaft,
making contact with the shaft surface with sufficient force to
dislodge incipient coke deposits but with insufficient force to
inhibit the axial motion of the pintle shaft in actuation. The
scraper is mounted within a radial shield surrounding the pintle
shaft and pintle bushing for preventing exposure of the shaft and
bushing to combustion products. The scraper is disposed in such a
way that the shaft is scraped in both directions during each
actuative cycle of the valve.
Inventors: |
Smith, Craig D.; (Penfield,
NY) ; Geib, Todd P.; (Fairport, NY) ; Marlowe,
Christopher B.; (Henrietta, NY) ; Bircann, Raul
A.; (Penfield, NY) |
Correspondence
Address: |
Delphi Technologies, Inc.
P.O. Box 5052
Mail Code 480410202
Troy
MI
48007
US
|
Family ID: |
25113696 |
Appl. No.: |
10/236738 |
Filed: |
September 6, 2002 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10236738 |
Sep 6, 2002 |
|
|
|
09778538 |
Feb 7, 2001 |
|
|
|
6453934 |
|
|
|
|
Current U.S.
Class: |
251/129.15 |
Current CPC
Class: |
F02M 26/67 20160201;
F02M 26/53 20160201; Y10T 137/4273 20150401; F16J 15/3288 20130101;
F02M 26/50 20160201; F16K 51/00 20130101; F02M 26/74 20160201 |
Class at
Publication: |
251/129.15 |
International
Class: |
F16K 031/02 |
Claims
What is claimed is:
1. An anti-coking apparatus for a valve pintle disposed for axial
reciprocation in a linear bearing in a valve body of an exhaust gas
recirculation valve, comprising: a) shield means surrounding said
bearing and extending between said valve pintle and said valve
body; and b) scraper means disposed within said shield means and
surrounding said valve pintle for removing deposits therefrom and
preventing particulates from reaching said bearing.
2. An apparatus in accordance with claim 1 wherein said shield
means is a formed element having an inwardly extending flange for
closely surrounding said pintle and an outwardly extending flange
for retention against said valve body.
3. An apparatus in accordance with claim 2 wherein a portion of
said element is captured between said bearing and said valve
body.
4. An apparatus in accordance with claim 1 wherein said scraper
means is a cylindrical, annular element.
5. An apparatus in accordance with claim 4 wherein said scraper
means is attached to said shield.
6. An apparatus in accordance with claim 4 wherein said element is
formed of a material selected from the group consisting of woven
metal mesh, stainless steel "wool", polymer fiber such as Teflon,
ceramic fiber, glass fiber, sintered ceramics, and combinations
thereof.
7. An apparatus in accordance with claim 4 wherein shield
containing said scraper extend into a region of said valve
containing exhaust gas.
8. An exhaust gas recirculation valve for an internal combustion
engine, comprising: a) a valve body; b) a valve pintle disposed for
axial reciprocation in a linear bearing in said valve body; c)
shield means surrounding said bearing and extending between said
valve pintle and said valve body; and d) scraper means disposed
within said shield means and surrounding said valve pintle for
removing deposits therefrom and preventing particulates from
reaching said bearing.
9. An internal combustion engine, comprising an exhaust gas
recirculation valve, including a valve body, a valve pintle
disposed for axial reciprocation in a linear bearing in said valve
body, shield means surrounding said bearing and extending between
said valve pintle and said valve body, and scraper means disposed
within said shield means and surrounding said valve pintle for
removing deposits therefrom and preventing particulates from
reaching said bearing.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a Continuation-In-Part of a
pending U.S. patent application Ser. No. 09/778,538, having a
common inventor and filed Feb. 7, 2001.
TECHNICAL FIELD
[0002] 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 shield and
scraper 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
[0003] 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.
[0004] 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;
and a solenoid actuator mounted on the exterior of the valve body
and operationally connected to the outer end of the valve
pintle.
[0005] 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 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.
[0006] 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
[0007] The present invention is directed to an integral pintle
shield and annular scraper for protecting and 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 scraper surrounds the shaft, 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. The scraper is mounted within a radial shield
surrounding the pintle shaft and pintle bushing for preventing
exposure of the shaft and bushing to combustion products. The
scraper is disposed in such a way that the shaft is scraped in both
directions during each actuative cycle of the valve.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The present invention will now be described, by way of
example, with reference to the accompanying drawings, in which:
[0009] FIG. 1 is an elevational cross-sectional view of a prior art
EGR valve assembly; and
[0010] FIG. 2 is an elevational cross-sectional view of an improved
exhaust gas recirculation valve assembly incorporating anti-coking
apparatus in accordance with the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0011] The benefits afforded by the present invention will become
more readily apparent by first considering a prior art EGR pintle
valve assembly. Referring to FIG. 1, a prior art EGR valve assembly
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 15 in which the valve is installed,
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 for conventional
actuation by a solenoid actuator (not shown). Bearing 26 is
disposed in a bore 27 in a wall of valve body 12 and guides pintle
shaft 22 in reciprocating motion to open and close the valve when
the solenoid is energized and de-energized, respectively. During
operation of the valve, pintle 22 where it enters and exits bearing
26 at the lower end thereof is fully and undesirably vulnerable to
coking and fouling by the exhaust gases present in chamber 16.
[0012] Referring to FIG. 2, improved EGR valve assembly 10' is
similar to prior art assembly 10, including a valve body 12', valve
seat 14', first chamber 16', second chamber 18', and may
communicate with the exhaust and intake systems of an internal
combustion engine 15 in which the valve is installed. Valve pintle
22' extends from head 20' through an axial bore 24' in bearing 26'
for conventional actuation by a solenoid actuator (not shown).
Bearing 26' is press-fit into a bore 27' in a wall of valve body
12' and guides pintle 22' in reciprocating motion to open and close
the valve when the solenoid is energized and de-energized.
[0013] Surrounding bearing 26' is a cup-shaped bearing shield 28
having an inward-extending flange 30 with a central aperture 32 for
passage of pintle 22', preferably with minimal contact
therebetween, and an outward-extending flange 34. Bore 27' and
bearing 26' are radially sized to snugly capture shield 28
therebetween when bearing 26' is fully entered into bore 27'.
Further, bearing flange 36 simultaneously captures shield flange 34
against abutment 38 in valve body 12'. Pintle 22' is thus shielded
beyond aperture 32 from materials in chamber 16', except for
materials which may enter the shielded space via aperture 32.
[0014] Within shield 28, and preferably secured to the inner wall
of flange 30 and inner wall 40 of shield 28 as by adhesives or
other retaining means, is a pintle scraper 42 surrounding pintle
22'. Scraper 42 is a cylindrical, annular element sized to fit
closely to pintle 22', without impeding significantly the
reciprocal action thereof, to remove incipient coking deposits from
the surface 44 of pintle 22' as the pintle is actuated by the
solenoid actuator. The adhesion of scraper 42 to flange 30 and wall
40 prevents leakage of exhaust gases around scraper 42. Further,
unlike radial wire brushes, scraper 42 is not readily permeable by
gases and particulates in the axial direction. Scraper 42 may be
formed of various materials, for example, woven metal mesh,
stainless steel "wool", polymer fiber such as Teflon, ceramic or
glass fiber, sintered ceramics, and similar packing-type materials.
Common to all such materials is a long, tortuous path for gases and
particulates to permeate through the scraper.
[0015] The combination of shield 28 and scraper 42 provides
superior protection against entry of particulates into bore 24' of
bearing 26', and against coking of surface 44 of pintle 22'.
[0016] 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.
* * * * *