Information
-
Patent Grant
-
6217001
-
Patent Number
6,217,001
-
Date Filed
Tuesday, June 29, 199925 years ago
-
Date Issued
Tuesday, April 17, 200123 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Shaver; Kevin
- Keasel; Eric
Agents
-
CPC
-
US Classifications
Field of Search
-
International Classifications
-
Abstract
Relatively simple partially or completely pressure balanced valves are disclosed having relatively low friction and gas forces to be overcome by a solenoid actuator. Various devices are provided for sealing of the valve members to maintain low leakage of gases through the valve or into the actuator. Movable members of the valve and actuator are engaged but physically separate so they may be separately replaced. Various actuators may by applied with various valve assemblies for flexibility in meeting the requirements of alternative applications.
Description
TECHNICAL FIELD
This invention relates to gas valves.
BACKGROUND OF THE INVENTION
It is known in the art relating to vehicle engines to provide selective recirculation of engine exhaust gases into the intake manifold under certain operating conditions in order to maintain controlled exhaust emissions within desired limits. For controlling such exhaust gas recirculation, an EGR valve may be provided which includes a valve assembly mountable or connectable to associated intake and exhaust manifolds or systems of the engine to meter the flow of exhaust gas from the intake to the exhaust.
The EGR valve may include a valve assembly operable to close or open a passage between the intake and exhaust manifolds. An actuator assembly may be mounted on or connected with the valve assembly and include a solenoid coil and an armature actuated by the coil to open the EGR valve, which is closed by a spring when the coil is deenergized. Pressure differentials between the intake and exhaust of naturally aspirated engines with manifold fuel injection require substantial solenoid energy to open the valve. With potential application to other engines, such as turbocharged engines, direct injection gasoline engines and diesel engines, where even larger gas flows may be required, reduction of solenoid energy for valve opening is desired to allow use of available solenoid actuators with valves for various engine applications. In addition, it is desirable to reduce or eliminate the effects of intake or exhaust pressure pulsations on the armature, solenoid and closing spring mass system to improve positional stability.
SUMMARY OF THE INVENTION
The present invention provides relatively simple partially or completely pressure balanced exhaust gas recirculation (EGR) valves having relatively low friction and gas forces to be overcome by the actuator. Pressure balancing reduces the solenoid and spring energy needed to actuate the valves and balances out the effects of intake or exhaust pressure pulsations on the armature, solenoid, and closing spring mass system. Various means are provided for sealing of the valve members to maintain low leakage of gases through the valve or into the actuator. The valve and actuator may be mounted together for drop in installation into an engine assembly or they may be separately mounted for use in various engine installations. Movable members of the valve and actuator are engaged but physically separate so they may be separately replaced. Various actuators may by applied with various valve assemblies for flexibility in meeting the requirements of a alternative engine applications.
These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1
is a cross-sectional view of a first embodiment of a partially balanced valve according to the invention as applied as an EGR valve in an engine;
FIG. 2
is a view similar to
FIG. 1
showing a second embodiment of an EGR valve mounted in an attached base;
FIG. 3
is a fragmentary cross-sectional view of a third embodiment with full balancing and modified seals;
FIG. 4
is a fragmentary cross-sectional view of a fourth embodiment modified from that of
FIG. 3
FIG. 5
is a cross-sectional view of a fifth embodiment with a specific seal arrangement;
FIG. 6
is a cross-sectional view similar to
FIG. 5
of a sixth embodiment with an alternative seal arrangement;
FIG. 7
is a cross-sectional view similar to
FIGS. 5 and 6
of a seventh embodiment with another seal arrangement;
FIG. 8
is a cross-sectional view similar to
FIG. 5
but showing an alternative piston arrangement; and
FIG. 9
is a cross-sectional view similar to
FIGS. 5-7
but including various alternative features.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring first to
FIG. 1
of the drawings in detail, numeral
10
generally indicates an internal combustion engine having an exhaust manifold
12
or other exhaust gas carrying component. Manifold
12
includes a cylindrical mounting recess
14
connecting through an inlet opening
16
at one end with an exhaust gas passage
18
in the manifold
12
. An outlet port
20
in the side of the recess
14
connects with an associated intake manifold, not shown, or another portion of an engine induction system. The recess
14
is open to a generally planar surface
22
of the manifold
12
with an annular counterbore
24
surrounding the opening. A coolant passage
26
in the manifold extends adjacent the recess
14
below the surface
22
.
Mounted on the manifold
12
is a first embodiment of exhaust gas recirculation (EGR) valve
28
according to the invention. EGR valve
28
includes a solenoid actuator
30
mounted on the manifold surface
22
by fasteners, such as screws
31
, and a valve assembly
32
associated with the actuator and mounted in the manifold recess
14
. Actuator
30
includes a housing
34
enclosing a solenoid coil
36
and including upper and lower magnetic poles
38
,
40
in which a hollow cylindrical armature
42
is reciprocably movable. A nonmagnetic sheath
44
surrounds the armature and provides a low friction surface on which the armature is slidable. A spring
46
biases the armature upwardly and seats against the sheath
44
near a bottom
48
of the housing seated on the upper surface
22
of the exhaust manifold
12
.
The valve assembly
32
includes a valve body in the form of a generally cylindrical seat tube
50
having an upper end received within a flange
52
on the bottom
48
of the housing and extending into the counterbore
24
of the exhaust manifold. The seat tube
50
extends downward into the mounting recess
14
of the exhaust manifold and engages a seal ring
54
seated on a flange defining the inlet opening
16
into the mounting recess
14
. The lower end of the seat tube
50
defines an annular valve seat
56
with which the head
58
of a valve member or pintle
60
is engagable. The pintle
60
also has a shaft or stem
62
which extends upward through the seat tube, spring and armature to engagement with a linear position sensor drive arm
64
. Means, such as a spring seat and cap
66
crimped onto the stem
62
, removably engages and connects the pintle with the spring
46
and the armature
42
, allowing the spring to bias the armature and pintle upwardly to seat the head
58
and close the valve. The seat tube
50
has a hollow interior which defines, in part, a passage
68
connecting the valve seat
56
with a side opening
70
communicating with the outlet port
20
of the exhaust manifold.
The pintle or valve member
60
further includes a balance piston
72
axially spaced from the valve head
58
above the side opening
70
and having an axially projected area approximately equal to that of the valve head
58
when it is seated. Piston
72
is slidable within and sealingly engages an internal cylinder
74
of a pintle shaft bushing
76
. Bushing
76
includes an annular flange
78
which is biased by a spring
80
into sealing engagement with a planar annular surface
82
of the seat tube
50
. The bushing
76
is self-aligned laterally on the surface
82
, so that alignment of the piston
72
with the cylinder
74
is inherent and the valve head
58
is allowed to center itself in the valve seat
56
. Thus, good sealing contact of the valve head and seat as well as the piston and cylinder are maintained.
In operation, the solenoid actuator
30
is connected to an outside controller or power source, not shown, in order to energize the coil
36
and open the valve
32
. The power source may have a constant voltage for full opening or closing of the valve or the power may be modulated in order to vary the valve opening in accordance with desired operating parameters.
When the valve is closed, valve head
58
engages valve seat
56
, blocking exhaust gas flow from the manifold passage
18
into the valve body formed by the seat tube
50
. During this time, variations in intake manifold pressure acting in the passage
68
within the seat tube
50
, are balanced by the relatively equal axially projected areas of the valve head
58
and piston
72
on which the varying pressures act. When the solenoid coil
36
is energized, the armature
42
is actuated downwardly against the bias of spring
46
, opening the valve and allowing exhaust gas to flow from the manifold passage
18
through the inlet opening
16
into the transfer passage
68
and out the side opening
70
to the manifold outlet port
20
which connects with the engine intake manifold, not shown.
The close fitting of the piston
72
within the cylinder
74
and the floating seal provided by engagement of the pintle shaft bushing flange
78
against the annular surface
82
of the seat tube, which is maintained by the force of the spring
80
, minimizes the leakage of gases between the passage
68
and the exterior of the valve. A vent passage
84
is provided in the lower portion of the solenoid housing
34
to relieve any gas pressure which might otherwise develop in this location and prevent the escape of exhaust gas into the solenoid housing. The coolant passage
26
in the exhaust manifold is positioned to protect the solenoid actuator mounted on the manifold from the high exhaust gas temperatures passing through the valve assembly
32
of the EGR valve.
FIG. 2
of the drawings illustrates a second embodiment of EGR valve according to the invention which is generally indicated by numeral
90
. In general, valve
90
operates in much the same manner as the valve
28
previously described and, where appropriate, like numerals indicate similar parts as to which further description is thought to be unnecessary. There are, however, a number of differences in construction which are described below.
In valve
90
, the valve body
92
is formed as a base having a mounting face
94
that is attachable against an associated surface of an internal combustion engine, not shown. Alternatively, the valve body could be part of a manifold or other component of the engine as in the embodiment of FIG.
1
. The valve body
92
includes dual passages
96
,
98
which extend through the base or body
94
and are connectable with associated passages in the induction system and exhaust system of the associated engine. Internally, passages
96
,
98
are joined through a pressed in and staked valve seat
100
which defines an orifice connecting the two passages whenever the valve is open. Varying induction system pressures which exist in passage
96
act, as in EGR valve
28
, upon approximately equal axially projected areas of the head
58
and piston
72
of valve member
60
so as to balance out the effect of varying induction system pressures in the same manner as in valve
28
.
The piston
72
is movable within a floating bushing
76
, as before, however, the bushing is urged downward by a wave spring
102
instead of the coil spring of valve
28
. The flange
78
is slidable on an annular surface
82
of the valve body to seal against leakage around the exterior of the bushing. A thin walled gas shield
104
is applied between the valve body
92
and solenoid actuator
106
to minimize the escape of exhaust gases into the solenoid actuator. Vents
108
,
109
, located above and below the gas shield, communicate the opposite sides of the gas shield separately with atmosphere and, thus, minimize the transfer of gases between the actuator and the valve body. The diameter of the pintle shaft
62
as it passes through the floating bushing
76
is sized to provide a clearance
110
between the bushing and the shaft
62
. This allows communication of ambient pressures to the upper side of the balance piston
72
for balancing the forces and opposing the leakage of exhaust gases past the piston.
A coolant passage
26
is provided in the valve body to limit the transfer of exhaust gas temperatures to the solenoid actuator, as before. The actuator
106
is mounted to the valve body
92
as by screws
31
to form the complete EGR valve ready for mounting on an associated engine.
FIG. 3
illustrates a third embodiment of EGR valve
116
which represents the first of several embodiments to be described which are suitable for use in diesel or gasoline direct injection engines, where both exhaust and intake manifold pressures may significantly vary.
In these embodiments, both intake and exhaust system pressures are approximately balanced on the valve so that variations in either one will have little effect on the opening and closing forces required to actuate the valve. In addition, the direction of exhaust gas flow can be reversed so that he exhaust gas flows from a side port into a central chamber and then, when the valve is open, out past the valve head to the intake manifold or engine induction system which is connected to a lower opening or orifice of the valve that is controlled by a valve head. The valve can also be operated with a gas flow direction as described with respect to
FIGS. 1 and 2
.
EGR valve
116
is exemplary in that the pintle or valve member
118
has a stem or shaft
120
which includes a hollow or tubular lower portion
122
attached to a solid upper portion
124
. A head
126
is mounted on the lower end of the tubular portion while a balance piston
128
is mounted near the upper end of the tubular portion. The balance piston is retained axially by staking the tubular portion
122
where it interfaces the balance piston
128
. The valve head
126
engages a valve seat
130
, formed at the lower end of a seat tube
132
which forms the valve housing or valve body.
Exhaust gas enters through a side opening
134
in the seat tube into a transfer chamber
136
where exhaust system pressures are exerted in opposite directions on the approximately equal axially projected areas of the valve head and the piston, thereby balancing exhaust pressures in the same manner as the intake or induction system pressures were balanced in the previous embodiments. Induction system pressures are also balanced, in that intake pressure acting on the lower surface of the valve head
126
is also conducted through the tubular lower portion
122
of the shaft through an opening
138
to a balance chamber
140
located above the balance piston
128
and below a floating shaft seal
142
. Thus, intake pressures are exerted on the outer ends of the valve head and piston leading to approximate balancing of the intake forces on the valve.
The floating shaft seal
142
engages outwardly the upper end of a floating bushing
144
which defines a cylinder in which the piston
128
reciprocates. Bushing
144
also includes a flange
145
which engages a planar annular surface
146
of the seat tube or valve housing
132
. Thus, gas pressures within the intake and exhaust gas exposed chambers are sealed to minimize leakage from these chambers. A wave spring
102
is provided to maintain sealing pressure on the floating shaft seal
142
and floating bushing
144
. A seal
148
, such as GARPHOIL or TEFLON, engages the shaft
120
to block gas leakage into the actuator and direct it out a vent
149
. Piston
128
can be allowed to float radially or rock slightly on the tubular portion
122
of shaft
120
which allows the piston to be self aligned with the inner cylinder surface of the floating bushing
144
. It may also enhance alignment of the pintle valve head
126
and seat
130
. This floating piston feature may also be applied in all of the balance pistons subsequently discussed.
FIG. 4
discloses a fourth embodiment of EGR valve
150
which represents a modification of the embodiment of FIG.
3
. In valve
150
, an optional lip seal
152
is provided that engages an upper end of the balance piston
154
to more positively seal against leakage between intake and exhaust portions when the valve is closed. In other respects, valve
150
in
FIG. 4
is similar to valve
116
in
FIG. 3
, wherein like numerals indicate like or similar parts.
Referring now to
FIGS. 5-7
, there are shown three additional embodiments of EGR valves
160
,
162
and
164
. These valves are similar in that they each include a solenoid actuator
106
which bolts directly onto an engine component in which a valve assembly is received.
EGR valve
160
, shown in
FIG. 5
, has a valve assembly
165
that includes a seat tube
166
forming the valve body. A valve member
168
is received in the seat tube and includes a formed tubular lower portion
170
which holds together a separate head
172
, tubular shaft
174
and balance piston
176
. The piston
176
reciprocates in a cylinder
177
formed by an inner surface of the seat tube
166
. The balance piston
176
is hollow and open at an upper end. In the closed position of the valve
160
, an annular upper edge of the piston
176
engages a lip seal
178
which prevents gas transfer between the intake and exhaust systems through the valve when the valve is closed. The lip seal
178
is carried by a floating shaft seal
179
having a flange
180
which is urged downwardly against a sealing surface
181
, as before, by a wave spring
102
seated against a gas shield
182
. A floating actuator seal
183
is seated on the shaft seal
179
and surrounds the shaft upper portion
124
to limit the passage of gases up into the solenoid actuator
106
. Vents
184
,
185
are provided above and below the gas shield
182
to minimize gas transmission between the valve body or seat tube
166
and the solenoid actuator
106
.
EGR valve
162
, shown in
FIG. 6
, is generally similar to valve
160
but the valve assembly
186
differs in details of the seat tube
187
which carries a radial piston seal
188
that engages an outer surface of the balance piston
176
when the valve is closed. The radial piston seal
188
is also engaged by the lower edge of a modified floating shaft seal
190
which is urged downwardly by the wave spring
102
, as before. The construction is otherwise similar to that of valve
160
.
EGR valve
164
, shown in
FIG. 7
, is again similar to valves
160
and
162
but the valve assembly
191
differs in the modified form of the seat tube
192
which carries a floating face and radial piston seal
194
. Seal
194
is biased by a spring
196
against the upper end of the balance piston
176
when the valve is closed. The spring
196
acts between the seal
194
and a modified floating shaft seal
198
. Seal
194
also radially contacts a cylinder surface within the seat tube
192
, thus preventing gas leakage either along the cylinder wall or past the end of the piston when the valve is closed. The axial travel of the seal
194
and its engagement with the balance piston
176
is controlled by a step
200
in the seat tube
192
. The step
200
limits downward motion so the seal
194
is engaged by the balance piston for only a short distance near the top of its travel near and in the valve closed position. In other respects, the embodiment of valve
164
is similar to valves
160
and
162
, previously described.
FIG. 8
illustrates an EGR valve
201
having a valve assembly
202
similar to assembly
165
of FIG.
5
. In valve assembly
202
, a balance piston
204
is modified to include external grooves
206
. The groove edges scrape off any carbon build up from the cylinder
177
of the seat tube
166
and thus minimize frictional changes that might otherwise occur over time in the valve operation.
FIG. 9
shows another EGR valve
210
similar to those of
FIGS. 3-8
but having certain modified features. A solenoid actuator
212
is provided having internal structure generally like those of the previously described embodiments. However, the housing
214
is modified to include a separate base plate
216
which is attached to the lower magnetic pole
218
by rivets
220
. The base plate
216
is then attached to the associated valve body, manifold or other engine component
222
by screws
31
in a conventional manner.
The valve assembly
224
includes a seat tube
226
having a cylinder with internal grooves
228
that scrape off carbon buildup as do the piston grooves
206
of FIG.
9
. The upper end of the seat tube
226
is radially enlarged with a cylindrical flange
230
that is received in circular recesses
232
,
234
of the engine component
222
and the actuator base plate
216
respectively. A large floating bushing
236
is mounted on the solid upper portion of the pintle shaft
237
and is urged against an annular surface of the seat tube by a wave spring
102
to seal against exhaust gas leakage as before. The pintle shaft
237
is one piece with the solid and hollow portions formed integrally. At the lower end, the seat tube
226
has a seat ring
238
that engages a separate valve seat
240
to hold it in place in a counterbore
242
of the engine component
222
.
In all of the previously described embodiments, the valve member or pintle is in contact with, but not attached to, the armature in the solenoid actuator. Thus, with appropriate component design, a solenoid actuator may be replaced without disturbing the valve assembly of any of the EGR valves illustrated. Further, this feature allows interchange of varying forms of actuators with various arrangements of valve assemblies to provide numerous variations in the EGR valves with a minimum of differing component parts.
While the invention has been described by reference to EGR applications and certain preferred embodiments thereof, it should be understood that numerous other applications and changes could be made within the spirit and scope of the inventive concepts described. Accordingly it is intended that the invention not be limited to the disclosed EGR application or embodiments, but that it have the full scope permitted by the language of the following claims.
Claims
- 1. A valve for metering gas, said valve comprising:a valve body including a passage, the valve body having a valve seat internally defining a flow orifice that is closable to cut off gas flow through the passage; a cylinder open to the passage and axially aligned with the valve seat orifice; a valve member in the passage and including a valve head engagable with the valve seat to close the orifice; a piston on the valve member and slidable in the cylinder, the piston and the valve head having, when the valve is closed, opposing approximately equal axially projected cross-sectional areas exposed to the passage for balancing the effects of varying pressure in the passage on the valve member; and seal means between the piston and the valve body for limiting leakage past the piston and cylinder; wherein said seal means includes a floating bushing defining said cylinder and slidably receiving said piston, said bushing having a flange slidably engagable with a sealing surface of the valve body and allowing limited lateral motion of the bushing for alignment with the piston; and a biasing member urging the floating bushing axially to force the flange of the bushing against the sealing surface of the valve body for preventing leakage of fluid past the piston between the cylinder and the valve body. body.
- 2. A valve as in claim 1 wherein said biasing member is a coil spring acting between the flange and a wall of the solenoid actuator.
- 3. A valve as in claim 1 wherein said biasing member is a wave spring acting between the bushing and a wall of the solenoid actuator.
- 4. A valve as in claim 1 including a floating shaft seal surrounding the valve member and extending laterally into engagement with said bushing, said biasing member acting against the shaft seal to urge the bushing axially.
- 5. A valve for metering gas, said valve comprising:a valve body including a passage, the valve body having a valve seat internally defining a flow orifice that is closable to cut off gas flow through the passage; a cylinder open to the passage and axially aligned with the valve seat orifice; a valve member in the passage and including a valve head engagable with the valve seat to close the orifice; a piston on the valve member and slidable in the cylinder, the piston and the valve head having, when the valve is closed, opposing approximately equal axially projected cross-sectional areas exposed to the passage for balancing the effects of varying pressure in the passage on the valve member; and seal means between the piston and the valve body for limiting leakage past the piston and cylinder; wherein said cylinder is formed in the valve body and said seal means includes: a floating shaft seal slidably surrounding said valve member and having a flange slidably engagable with a sealing surface of the valve body and allowing limited lateral motion of the shaft seal for alignment with the valve member; and a biasing member urging the floating shaft seal axially to force the flange of the shaft seal against the sealing surface of the valve body for preventing leakage of fluid past the piston in the cylinder of the valve body.
- 6. A valve as in claim 5 including:a solenoid actuator having a coil and an armature engagable with the valve member and operative to open the valve when the coil is energized; a second biasing member urging the valve member in a closing direction and operative to close the valve when the coil is deenergized; second seal means supported in part by said floating shaft seal and having a tubular portion closely surrounding said valve member in an adjacent portion of the actuator; and vent means communicating with said valve member on both sides of said seal means minimize the transmission of gas between the valve body and the solenoid actuator.
- 7. A valve for metering gas, said valve comprising:a valve body including a passage, the valve body having a valve seat internally defining a flow orifice that is closable to cut off gas flow through the passage; a cylinder open to the passage and axially aligned with the valve seat orifice; a valve member in the passage and including a valve head engagable with the valve seat to close the orifice; a piston on the valve member and slidable in the cylinder, the piston and the valve head having, when the valve is closed, opposing approximately equal axially projected cross-sectional areas exposed to the passage for balancing the effects of varying pressure in the passage on the valve member; seal means between the piston and the valve body for limiting leakage past the piston and cylinder; a solenoid actuator having a coil and an armature engagable with the valve member and operative to open the valve when the coil is energized; and a biasing member urging the valve member against the armature in a closing direction and operative to close the valve when the coil is deenergized; said armature and said valve member being operatively engaged but detached so that the solenoid actuator may be replaced without disturbing the valve member in the valve body.
- 8. A valve for metering gas, said valve comprising:a valve body including a passage, the valve body having a valve seat internally defining a flow orifice that is closable to cut off gas flow through the passage; a cylinder open to the passage and axially aligned with the valve seat orifice; a valve member in the passage and including a valve head engagable with the valve seat to close the orifice; a piston on the valve member and slidable in the cylinder, the piston and the valve head having, when the valve is closed, opposing approximately equal axially projected cross-sectional areas exposed to the passage for balancing the effects of varying pressure in the passage on the valve member; seal means between the piston and the valve body for limiting leakage past the piston and cylinder wherein the cylinder is formed in the valve body and the seal means includes: a floating shaft seal slidably surrounding the valve member and having a flange slidably engagable with a sealing surface of the valve body and allowing limited lateral motion of the shaft seal for alignment with the valve member; and a biasing member urging the floating shaft seal axially to force the flange of the shaft seal against the sealing surface of the valve body for preventing leakage of fluid past the piston in the cylinder of the valve body; wherein said piston has a hollow interior with an open end facing axially away from said valve head; said valve member includes a hollow stem extending through said valve head to said piston interior; and said valve includes a contact seal engagable with said piston when said valve is closed to enclose the open end of the piston whereby to equalize pressures on said piston interior and on the exterior of the valve head when the valve is closed.
- 9. A valve as claimed in claim 8 wherein said valve member further comprises a tubular shaft surrounding said hollow stem and extending between said valve head and said piston.
- 10. A valve as claimed in claim 9 wherein said tubular shaft is integral with said valve head.
- 11. A valve as in claim 8 wherein said contact seal is carried on said floating shaft seal and engages the open end of the piston when the valve is closed.
- 12. A valve as in claim 8 wherein said contact seal is carried in the valve body and is engaged by an outer periphery of the piston adjacent the open end when the valve is closed.
- 13. A valve as in claim 12 wherein the floating shaft seal has a hollow interior and an open end also engaging the contact seal, the hollow interiors of the piston and the floating shaft seal being joined as a sealed volume when the valve is closed.
- 14. A valve as in claim 8 wherein said contact seal is a floating annulus including both face and radial seal surfaces, said radial seal surface slidingly engaging cylindrical portion of the valve body;and a second member urging the face seal surface of said annulus axially against the open end of the piston when the valve is closed.
- 15. A valve as in claim 14 wherein floating shaft seal has a hollow interior that communicates with the hollow interior of the piston through the contact seal annulus to form a sealed volume when the valve is closed.
US Referenced Citations (5)