Information
-
Patent Grant
-
6634346
-
Patent Number
6,634,346
-
Date Filed
Tuesday, September 18, 200122 years ago
-
Date Issued
Tuesday, October 21, 200320 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Yuen; Henry C.
- Castro; Arnold
Agents
-
CPC
-
US Classifications
Field of Search
US
- 251 12911
- 251 12903
- 251 12907
- 251 12908
- 251 12915
- 251 12916
- 123 56811
- 123 56821
- 123 56827
- 123 9037
- 123 9011
-
International Classifications
-
Abstract
A subassembly module including a pintle bearing, bearing retaining spring, and bearing splash shield for an exhaust gas recirculation (EGR) valve for an internal combustion engine. The bearing is provided with a circumferential flange for sealing with an outer surface of the valve body, and with an annular step in the flange for receiving the rolled or crimped skirt of the bearing splash shield. The bearing retaining spring surrounding the valve pintle is compressed and captured within the splash shield as the skirt is formed onto the annular step to form the module. The axial length of the module is slightly greater than the assembled distance between the valve body and the actuator of the EGR valve, such that the module is compressed by installation of the actuator onto the valve body, allowing the compressed spring to urge the bearing face sealingly against the valve body. Advantageously, the subassembly module may be pre-assembled offline by known methods to reduce complexity during assembly of the valve.
Description
TECHNICAL FIELD
The present invention relates to pintle valves for permitting the controlled admission of exhaust gases into the fuel intake manifold of an internal combustion engine; more particularly, to the pintle bearing, bearing retaining spring, and bearing splash shield of such a valve; and most particularly to a modular subassembly which may be pre-assembled and which combines these three components for ease of manufacture of the valve, reduction in assembly errors, and reduced cost of manufacture.
BACKGROUND OF THE INVENTION
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. 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 pintle valve having a valve head fitted to the valve seat and a valve stem or pintle 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 stem. Because exhaust gas may leak along the valve stem, the actuator typically is mounted on standoffs to vent such leaking exhaust gas and thereby prevent it from entering and corroding the solenoid. The bearing has a circumferential flange for sealing against an outer surface of the valve body and may be urged to seal by a spring which is compressed and captured between the valve body and the actuator, such as a compressed coil spring surrounding the valve stem. An EGR valve having such a standoff configuration may be exposed to various environmental hazards, such as mud and salt from roadways, which can corrode the exposed valve stem and spring or accumulate on the bearing, eventually fouling the stem and disabling the valve. Therefore, a cup-shaped bearing splash shield extending axially over the spring and bearing typically is provided to protect the bearing, stem, and spring from external contamination.
During assembly of such a prior art valve, after the valve head is inserted into the chamber via the third port, the bearing is threaded onto the pintle and seated against the valve body, then the spring is installed onto the pintle, then the splash shield is installed over the spring, and then the actuator pole piece is attached to the outer end of the pintle and the actuator is bolted to the valve body through a plurality of hollow standoffs, thus capturing the spring against the underside of the shield and compressing the spring to the proper degree. This procedure requires manual alignment of the various parts, which are loose and which must be mutually aligned for proper assembly; thus, the valve is easily subject to misassembly.
What is needed is a modular subassembly of the bearing, spring, and shield which is readily pre-assembled offline, which is self-aligned by the pintle; in which the spring is preloaded to a predetermined and repeatable compression; and which is readily installed as a single component on the valve pintle by an assembly operator.
SUMMARY OF THE INVENTION
The present invention is directed to a subassembly module comprising a pintle bearing, bearing retaining spring, and bearing splash shield for an exhaust gas recirculation valve for an internal combustion engine. The bearing is provided with a circumferential flange for sealing on an axial face thereof with an outer surface of the valve body, and with an annular step for receiving the rolled or crimped skirt of the bearing splash shield. The bearing retaining spring surrounding the valve pintle is compressed and captured within the splash shield as the skirt is formed onto the annular step to form the module. The axial length of the module between the outer end of the shield and the axial face of the bearing flange is slightly greater than the assembled distance between the valve body and the actuator of the EGR valve, such that the spring is further compressed by installation of the actuator onto the valve body to urge the first circumferential bearing face sealingly against the valve body. Advantageously, the subassembly may be pre-assembled offline by known methods to reduce complexity during assembly of the valve.
BRIEF DESCRIPTION OF THE DRAWINGS
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:
FIG. 1
is an elevational cross-sectional view of a prior art EGR valve;
FIG. 2
is an enlarged and detailed view of area
2
in
FIG. 1
, showing the bearing, bearing spring, and bearing splash shield as separate components;
FIG. 3
is an elevational cross-sectional view of a first embodiment of a bearing subassembly module in accordance with the invention;
FIG. 4
is an elevational cross-sectional view like that shown in
FIG. 3
, showing venting provisions for a second embodiment of a bearing subassembly module;
FIG. 5
is an elevational cross-sectional view showing the subassembly module shown in
FIG. 3
installed in a partial and idealized EGR valve; and
FIG. 6
is an elevational cross-sectional view of a third embodiment of a bearing subassembly module in accordance with the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The benefits afforded by the present invention will become more readily apparent by first considering a prior art 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 stem
22
in reciprocating motion to open and close the valve when actuator
30
is energized and de-energized, respectively. 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 actuator
30
to prevent dust intrusion into the actuator.
As noted above, the stem, bearing, spring, shield, standoffs, bolts, and actuator are all loose components which must be manually and simultaneously accommodated during assembly of the valve, which can be a complex and difficult task for an assembly operator. It is a primary objective of the invention to simplify the final assembly of the valve by reducing the number of individual components to be assembled, by combining the spring and a modified bearing and modified splash shield into a pre-assemblable subassembly module. An additional benefit of the invention is that the subassembly module is axially self-adjusting to accommodate the stack-up of axial manufacturing variation in lengths of the standoff, thus relaxing the manufacturing tolerance for each component.
Referring to
FIGS. 3-6
, a subassembly module
54
is intended for direct replacement of the assembly of loose parts
26
,
38
,
50
shown in
FIG. 2
to provide an improved EGR valve
10
′, shown partially in FIG.
5
. Bearing
26
′ is modified over bearing
26
to include an annular step
58
in flange
32
, and also preferably an annular well
56
in flange
32
for more positive seating and centering of spring
50
. Skirt
44
′ on splash shield
38
′ (which is formed as by stamping from sheet metal) is axially longer than skirt
44
. Flange
40
′ is formed such that an axial clearance
41
exists between the inner edge
43
of flange
40
′ and bearing
26
′.
To pre-assemble module
54
, bearing
26
′, spring
50
, and shield
38
′ are positioned, for example, in a conventional jig, wherein spring
50
is compressed and the axial length
57
of module
54
between face
34
and upper surface
60
of shield
38
′ is fixed. The free edge
62
of skirt
44
′ is then rolled or staked radially inwards into step
58
and against axial face
55
to lock the module components together. After removal from the jig, the module is ready for assembly into valve
10
′. Preferably, length
57
is slightly greater than the assembled spacing
64
between actuator
30
and the valve surface
36
, as shown in
FIG. 5
, so that module
54
is compressed, edge
62
is lifted off of face
55
, and the compressed force of spring
50
is directed through flange
32
against valve surface
36
to form the seal. It should be noted that the configuration of skirt
44
′ in the subassembly module provides complete enclosure of the interior chamber
68
of the splash shield, thus providing a significant improvement in bearing splash protection over the prior art shield.
Preferably, the diameter
66
of the portion
67
of bearing
26
′ extending into port
27
is slightly less than the diameter
69
of port
27
to permit the bearing to float radially as may be required for valve head
20
to seat conformably in seat
14
.
Referring to
FIG. 4
, during use of the valve some exhaust gases, especially moisture-laden gases, may be found to leak along bore
24
into chamber
68
. In alternate module embodiment
70
, skirt
44
′ of shield
38
′ is provided with a plurality of vents
72
, which may be formed for example as by stamping or punching in skirt
44
′. Vents formed as bent flaps, as shown in
FIG. 4
, can provide adequate venting of gases while not compromising the shielding function of shield
38
′.
Referring to
FIG. 6
, in mating with some known actuators, it may be desirable for flange
40
′ to be flared axially toward the actuator, as shown as flange
40
″ on embodiment
54
′. Alternative shapes for flange
40
′ are fully within the scope of the invention.
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.
Claims
- 1. A subassembly module for use in a pintle valve having a valve body and a valve pintle extending from the valve body, comprising:a) a bearing mountable on said body and having an axial bore for receiving and guiding said pintle; b) a bearing splash shield having an axial opening for receiving said pintle and having a skirt surrounding said bearing, said skirt having a free edge formed to slidably retain said shield on said bearing; and c) a spring disposed between said bearing and said splash shield for urging said bearing against said valve body during operation of said valve.
- 2. A subassembly module in accordance with claim 1 wherein said bearing has a circumferential flange having a first axial face for sealably mating with said valve body, means for receiving said formed free edge of said skirt, and means for receiving said spring.
- 3. A subassembly module in accordance with claim 1 wherein said splash shield has an inwardly- and axially-extending radial flange surrounding said axial opening.
- 4. A subassembly module in accordance with claim 3 wherein said radial flange extends axially towards said valve body when said valve is fully assembled.
- 5. A subassembly module in accordance with claim 3 wherein said radial flange extends axially away from said valve body when said valve is fully assembled.
- 6. A subassembly module in accordance with claim 1 wherein said free edge of said skirt is turned radially inwards to engage said bearing.
- 7. An exhaust gas recirculation valve for use in an internal combustion engine, said valve having a valve body and a valve pintle extending from said valve body, comprising a bearing module having a bearing mountable on said valve body for receiving and guiding said pintle, a bearing splash shield having an axial opening for receiving said pintle and having a skirt surrounding a portion of said bearing and having a free edge formed to be slidably retained on said bearing, and a spring disposed between said bearing and said splash shield for urging said bearing against said valve body during operation of said valve.
- 8. An internal combustion engine, comprising:a) an intake manifold having a first port therein; b) an exhaust manifold having a second port therein; and c) an exhaust gas recirculation valve connected between said first and second ports, said valve having a valve body and a valve pintle extending from said valve body, comprising a bearing module having a bearing mountable on said valve body for receiving and guiding said pintle, a bearing splash shield having an axial opening for receiving said pintle and having a skirt surrounding a portion of said bearing and having a free edge formed to be slidably retained on said bearing, and a spring disposed between said bearing and said splash shield for urging said bearing against said valve body during operation of said valve.
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Number |
Name |
Date |
Kind |
4497335 |
Masuda |
Feb 1985 |
A |
4998707 |
Meyer et al. |
Mar 1991 |
A |
6062536 |
Bircann |
May 2000 |
A |
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Number |
Date |
Country |
19950871 |
Apr 2001 |
DE |
1126186 |
Aug 2001 |
EP |
WO 9525883 |
Sep 1995 |
WO |