Information
-
Patent Grant
-
6749174
-
Patent Number
6,749,174
-
Date Filed
Friday, September 6, 200221 years ago
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Date Issued
Tuesday, June 15, 200420 years ago
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Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 251 12915
- 251 214
- 123 56811
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International Classifications
-
Abstract
A pintle-type valve including a valve body enclosing a chamber having a first port surrounded by an annular valve seat in a first wall of the chamber and a second port in a second and opposite wall of the chamber for receiving a pintle bushing. A valve pintle shaft having an attached valve head is disposed in the bushing. The second port is larger in diameter than the diameter of the valve head, so that the valve head may be admitted to the chamber through the port. The bushing is radially floating in the port and has a flange extending along an outer surface of the valve body for forming a seal therewith. The pintle extends into a conventional solenoid-type actuator bolted to the valve body. A radially-floating gas seal surrounds the pintle between the retainer and the actuator. A compressed coil spring holds the bushing in place against operating pressure within the valve chamber. The bushing and gas seal are centered by the valve stem, reducing frictional drag and reducing valve leakage.
Description
TECHNICAL FIELD
The present invention relates to exhaust gas recirculation (EGR) pintle valves for internal combustion engines; more particularly, to such valves which are inwardly-opening; and most particularly, to such a valve wherein drag on the valve pintle shaft is minimized during actuation thereof.
BACKGROUND OF THE INVENTION
Pintle valves are well known for use in controlling flow of fluids, and especially gases. An important use is for recirculating a portion of the exhaust gas from an internal combustion engine into the intake manifold thereof.
Current gas flow valves wherein a valve head is inwardly withdrawn into a chamber from a valve seat typically include a valve pintle bushing pressed into a bore in a valve wall opposite the valve seat. Because of high operating pressures in the valve chamber, the wall containing the bushing is typically a removable plate which is bolted onto the valve body after the bushing and valve pintle/head are installed. Such a large plate typically is gasketed to minimize gas leakage. Due to necessary tight clearances for the pintle in the bushing and the plurality of other components common to current EGR control valves, misalignment of the pintle and head with respect to the valve seat is virtually inevitable. The valve head must center itself in the seat, thereby exerting torque on a misaligned bushing which causes frictional drag on the pintle shaft as it moves through the bushing. Further, a gas shield for preventing leakage of exhaust gas into the solenoid actuator, if not very highly aligned with the pintle shaft, causes addition drag on the shaft during actuation. Typically, such parasitic losses require that a solenoid actuator for a prior art valve be undesirably large and power-consuming.
Further, such misalignments can result in significant leakage of gases to the exterior of the valve, whereas government regulations on emission are becoming ever stricter.
What is needed in the art is a means for allowing a pintle shaft bushing and a shaft gas seal to be radially floating and therefore self-aligning to reduce the power required to actuate the valve and to reduce emissions from the valve.
It is a principal object of the present invention to reduce the power required to operate an EGR valve by reducing frictional losses of actuation within the valve mechanism.
It is a further object of the present invention to reduce exhaust leakage from an EGR valve.
It is a still further object of the present invention to reduce the number of components of an EGR valve and to simplify assembly thereof.
SUMMARY OF THE INVENTION
Briefly described, a pintle-type valve in accordance with the invention includes a valve body enclosing a chamber. A first port surrounded by an annular valve seat is provided in a first wall of the body. A second port is formed in a second and opposite wall of the body coaxially with the first port for receiving a pintle bushing from outside the valve body. A valve pintle shaft, having an attached valve head for mating with the valve seat, is disposed in a close-fitting central bore in the bushing. The second port has a diameter larger than the diameter of the valve head, so that the valve head may be admitted to the chamber through the port. The bushing is radially floating in the port, has a flange extending along an outer surface of the valve body for forming a seal therewith, and is approximately centered and retained by a bushing retainer. The pintle extends into a conventional solenoid-type actuator which is attached to the valve body. A radially-floating gas seal surrounds the pintle between the retainer and the actuator. A compressed coil spring surrounding the pintle between the gas seal and the bushing holds the bushing in place against operating pressure within the valve chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1
is an elevational cross-sectional view of a prior art pintle-type valve;
FIG. 2
is an elevational cross-sectional view of a novel pintle-type valve in accordance with the invention;
FIG. 3
is an elevational cross-sectional view of a radially-compliant gas shaft seal in accordance with the invention;
FIG. 4
is an elevational cross-sectional view of a second embodiment of a valve in accordance with the invention; and
FIG. 5
is a plan view of the valve shown in FIG.
4
.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The novelty and advantages conferred by the invention may be better appreciated by first considering a prior art pintle-type valve.
Referring to
FIG. 1
, a prior art pintle-type valve assembly
10
includes a valve body
12
comprising a first chamber
14
and having a first port
16
surrounded by an annular valve seat
18
. Chamber
14
is closed by plate
20
which is gasketed to body
12
by a resilient gasket
22
. Plate
20
is secured to body
12
via a plurality of bolts
24
acting through hollow standoffs
26
to also secure solenoid actuator
28
thereto. A second port
30
in valve body
12
is opposite to and coaxial with first port
16
and is receivable of an axially elongate pintle shaft bushing
32
which is pressed into port
30
and retained therein by plate
20
to resist its being expelled by pressure in chamber
14
. Pintle shaft
34
is disposed for reciprocating motion in an axial bore
36
in bushing
32
and extends in a first direction into actuator
28
. In a second direction, shaft
34
is provided with a valve head
38
within chamber
14
for mating coaxially with valve seat
18
. A cup-shaped gas seal
40
having a central opening
42
close-fitting to shaft
34
is disposed between plate
20
and actuator
28
and is urged against actuator
28
by a coil spring
44
disposed in compression between plate
20
and seal
40
.
As discussed above, normal manufacturing variation in the dimensions and locations of the valve body, the chamber, the ports, the bushing and its bore, and the gas seal result in some unavoidable degree of misalignment and consequent drag on the pintle shaft during actuation by the solenoid. It is a primary objective of the invention to reduce such drag by providing a bushing and a gas seal arrangement which can float radially to be centered automatically by the pintle shaft itself in response to centering of the valve head in the valve seat.
Referring to
FIG. 2
, an improved pintle-type valve assembly
10
′ includes a valve body
12
′ comprising a first chamber
14
′ and having a first port
16
′ surrounded by an annular valve seat
18
′. A second port
30
′ in valve body
12
′ is opposite to and coaxial with first port
16
′ and is receivable of a pintle shaft bushing
32
′ having a first diameter
46
which is smaller than the diameter of second port
30
′ such that bushing
32
′ may be radially displaced within port
30
′. Bushing
32
′ is provided with an equatorial flange
48
having a diameter greater than the diameter of second port
30
′. A first surface
50
of flange
48
is matable with a surface
52
of valve body
12
′ to form a seal against leakage from chamber
14
′. Annular bushing retainer
54
is disposed around flange
48
and has an inner diameter slightly greater than the outer diameter of flange
48
. Bushing retainer
54
is pressed into a shallow well
55
in valve body
12
′. Preferably, the radial clearance and axial clearance between flange
48
and retainer
54
are each about 0.3 mm to permit free movement of bushing
32
′ over a very small range of motion. Pintle shaft
34
′ is disposed for reciprocating motion in an axial bore
36
′ in bushing
32
′ and extends in a first direction into actuator
28
′. In a second direction, shaft
34
′ is provided with a valve head
38
′ within chamber
14
′ for mating coaxially with valve seat
18
′, second port
30
′ being large enough in diameter to admit valve head
38
′ to chamber
14
′. Solenoid
28
′ is secured to body
12
′ via a plurality of bolts
24
′, preferably three. Preferably, body
12
′ is formed having a plurality of threaded legs
13
, as shown in
FIGS. 2
,
4
and
5
, replacing hollow standoffs
26
.
Referring to
FIGS. 2 and 3
, a gas seal assembly
40
′ comprises a formed element
41
having a central opening
42
′ loosely retaining a grommet
56
which is close-fitting to shaft
34
′, preferably with nearly zero clearance thereto. Grommet
56
has first and second flared rims
58
a
,
58
b
extending along the respective surfaces of element
41
. Grommet
56
includes shaft opening
57
that is closely fitted axially to element
41
to minimize gas leakage therebetween but is loosely fitted radially within opening
42
′ to permit radial adjustment of grommet
56
within stationary element
41
.
Gas seal assembly
40
′ is disposed against an annular flange
60
on actuator
28
′ and is urged against actuator
28
′ by a coil spring
44
′ disposed in compression between bushing flange
48
and seal assembly
40
′. Preferably, for use of valve assembly
10
′ as an exhaust gas recirculation valve in an engine
74
, spring
44
′ has a spring force in excess of about 200 kPa, to retain bushing
32
′ within port
30
′ without leakage against a pressure within chamber
14
′ of typically about 140 kPa or less.
Preferably, a cylindrical screen element
62
is captured between seal assembly
40
′ and valve body
12
′, as shown in FIG.
2
. Preferably, element
62
comprises a wire mesh for keeping external debris out of the valve assembly but permitting ready exhaust of any gases leaking around or through bushing
32
′.
Referring to
FIGS. 4 and 5
, a portion of second embodiment
10
″ of a pintle-type valve in accordance with the invention is shown. The arrangement of a valve body
12
″, chamber
14
″, first port
16
″, seat
18
″, pintle shaft
34
″, valve head
38
″, and pintle bushing
32
″ is substantially the same as previously discussed under embodiment
10
′. However, chamber
14
″ is not formed having valve body return portions
64
(shown in FIG.
2
); rather second port
30
″ is simply an extension of the wall of chamber
14
″. Thus, a bushing adaptor
66
is required, being pressed into a shallow well
68
in body
12
″ and having the same radial clearance to bushing
32
″ as shown in embodiment
10
′. An axial seal is thus formed between bushing flange
48
″ and adaptor
66
, analogous to the seal formed in embodiment
10
′. A bushing retainer
54
′ is pressed into well
65
of adaptor
66
. Retainer
54
′ is formed having a raised rim
70
for collecting gas condensate which may leak past bushing
32
″, and having one or more slots
72
in rim
70
to allow spontaneous drainage of any such condensate.
An advantage of a valve in accordance with the present invention is a substantial reduction in exhaust gas emissions. When valve assembly
10
′ was tested against prior art valve assembly
10
, an eight-fold reduction in valve exhaust emissions was observed.
A further advantage is a substantial reduction in frictional drag on the pintle shaft during actuation thereof, thereby reducing the power required for actuation and permitting use of an actuator
28
′ smaller than actuator
28
.
A still further advantage is a reduction in total parts required. Embodiment
10
′ eliminates 3 standoffs, a gasket, and a plate, and adds a bushing retainer, metal mesh filter, and a grommet, for a net reduction of two components. Assembly is also simplified.
Further, since variations in the compressed length of spring
44
′ due to assembly tolerances has no affect on the radial forces exerted by gas shield grommet on the pintle shaft, as the variations did in the prior art, body
12
′ can be welded to solenoid actuating assembly
28
′. Thus a further reduction in total part count can be realized.
While the invention has been described by reference to various specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiments, but will have full scope defined by the language of the following claims.
Claims
- 1. A pintle type valve, comprising:a) a valve body containing at least one chamber; b) a first port in said chamber; c) a valve seat surrounding said first port; d) a second port in said chamber opposite said first port, said second port having a port diameter; e) a pintle shaft bushing disposed in said second port and having a first portion smaller in diameter than said second port diameter and having a flange portion larger in diameter than said second port diameter and extending beyond said second port outside said valve body; f) a valve pintle shaft axially disposed in said bushing and extending into said chamber; g) a valve head disposed on said shaft for mating with said valve seat; h) a solenoid actuator attached to said valve body and engaged with said pintle shaft for axial actuation thereof; i) a coil spring disposed in compression between said actuator and said bushing for retaining said bushing in said second port against operating pressure within said chamber; and j) an annular gas seal having a fixed element with a central opening for receiving a grommet having a shaft opening for close-fitting admission of said valve pintle shaft, said grommet being close-fitting to said fixed element in an axial direction and loosely fitting to said fixed element in a radial direction.
- 2. A pintle type valve in accordance with claim 1 further comprising a screen element disposed between said actuator and said valve body.
- 3. A pintle type valve in accordance with claim 1 further comprising a bushing retainer disposed in a well in said valve body and surrounding said flange portion of said bushing.
- 4. A pintle type valve in accordance with claim 3 further comprising a radial clearance between said bushing retainer and said bushing of less than about 0.5 mm.
- 5. A pintle type valve in accordance with claim 1 wherein said spring has a compressed force of at least about 200 kPa.
- 6. An internal combustion engine, comprising a pintle-type exhaust gas recirculation valve havinga valve body containing at least one chamber, a first port in said chamber, a valve seat surrounding said first port, a second port in said chamber opposite said first port, said second port having a port diameter, a pintle shaft bushing disposed in said second port and having a first portion smaller in diameter than said second port diameter and having a flange portion larger in diameter than said second port diameter and extending beyond said second port outside said valve body, a valve pintle shaft axially disposed in said bushing and extending into said chamber, a valve head disposed on said shaft for mating with said valve seat, a solenoid actuator attached to said valve body and engaged with said pintle shaft for axial actuation thereof, an annular gas seal disposed between said valve body and said actuator having a fixed element with a central opening for receiving a grommet having a shaft opening for close-fitting admission of said valve pintle shaft, said grommet being close-fitting to said fixed element in an axial direction and loosely fitting to said fixed element In a radial direction, and a coil spring disposed in compression between said gas seal and said bushing for retaining said bushing in said second port against operating pressure within said chamber.
US Referenced Citations (7)
Foreign Referenced Citations (1)
Number |
Date |
Country |
1130246 |
May 2001 |
EP |