Internal-combustion engines – Charge forming device – Exhaust gas used with the combustible mixture
Reexamination Certificate
1999-04-23
2001-06-19
Dolinar, Andrew M. (Department: 3747)
Internal-combustion engines
Charge forming device
Exhaust gas used with the combustible mixture
C123S568210, C251S129070, C251S129150
Reexamination Certificate
active
06247461
ABSTRACT:
TECHNICAL FIELD
This invention relates to high flow balanced pressure gas management valves and, in a particular embodiment, to high flow balanced pressure exhaust gas recirculation (EGR) valves for automotive vehicles.
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 exhaust to the intake or to modulate the flow of EGR by manipulating the pressure differential.
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 or close the EGR valve, which is returned 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.
SUMMARY OF THE INVENTION
The present invention provides relatively simple pressure balanced high flow exhaust gas recirculation (EGR) valves having various features. A particular embodiment includes a solenoid actuator and an attached valve assembly. The actuator includes a housing enclosing a coil actuated armature and having a lower mounting recess. The valve assembly includes a valve body having a mounting portion, a connecting portion and a control portion, which may, for example, be formed as a single machined casting, an extruded tube or be integrated as part of an engine manifold. A valve member includes a shaft reciprocably mounted in the body and carrying a pair of axially spaced valve heads engagable with spaced valve seats in the control portion of the body to control gas flow through control ports associated with the valve seats.
At least the control portion of the valve body and the portion of the shaft between the valve heads are preferably made from materials having similar coefficients of thermal expansion. Thereby, axial thermal expansion and contraction of these portions of the valve member and the valve body will be essentially equalized so that substantially equal seating contact of the spaced heads with their respective seats will be effectively maintained.
The valve body may be generally cylindrical with passage openings through the walls between the valve seats in the control portion and in the connecting portion to provide for a flow of gas when the valve is open. The valve seats define the control ports and comprise annular ends of the control portion which have thickened wall portions to resist distortion of the seats. The mounting portion also includes a thickened wall connected with a mounting flange that is received in the mounting recess of the actuator housing and is retained therein by deformed retaining means, such as a lip on the housing. The valve body is configured for installation in a cylindrical bore or recess of an associated manifold or other gas passage defining member. Seal rings of elastomeric or metallic material, are carried in annular grooves of the thickened wall portions and seal the controlled flow passages as well as maintaining a small gap between the valve body walls and the passage defining member to minimize heat transfer and assist equalization of the body and valve shaft expansion rates.
One or both of the valve heads may be attached to the shaft by a press and spin or crimping process to promote ease of assembly. The valve shaft may be supported by a single bushing carried in the mounting portion. A shaft seal in the bushing may include a lip that is responsive to gas pressures to vary the sealing force, for example, under turbocharged conditions.
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.
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Gluchowski Paul Ludwig
Palmer Dwight Orman
Reeves Mark A.
Smith Craig Daniel
Castro Arnold
Delphi Technologies Inc.
Dolinar Andrew M.
VanOphem John
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