Internal-combustion engines – Charge forming device – Having fuel vapor recovery and storage system
Reexamination Certificate
1999-03-29
2001-03-20
Miller, Carl S. (Department: 3747)
Internal-combustion engines
Charge forming device
Having fuel vapor recovery and storage system
C123S519000
Reexamination Certificate
active
06202632
ABSTRACT:
FIELD OF INVENTION
The present invention pertains to controllable canister purge valves and a method for their operation.
BACKGROUND OF THE INVENTION
Canister purge valves are used to prevent evaporated fuel, in particular hydrocarbons, from escaping into the atmosphere. For this reason, an activated carbon canister is connected to the fuel tank. The canister is able to retain the fuel that has evaporated from the tank. For this reason the fuel tank is ventilated only through the filter. However, the activated carbon container provides only a limited holding volume. Consequently, the activated carbon must be continuously purged. To this end, the running engine takes air through the filter that is supplied as a combustion mixture to the motor. To maintain the exhaust emissions within statutory limits and to ensure favorable engine running conditions, the supply of the regenerating mixture of air and fuel vapor from the activated carbon filter to the engine is controlled. The canister purge valve is thus opened or closed by the purge valve so that the desired purge is timed through an adjustment of the engine characteristics, for example, according to the load and rotational speed parameters. Usually, the purging of the active carbon filter is deactivated in specific operating ranges. This, for example, occurs during idle time and under full load. The latter results from the lack of vacuum in an intake manifold of the motor, so that no regenerating mixture of air and fuel vapor can be drawn off from the activated carbon. Furthermore, a lambda control can be engaged to adjust the flow volume of the regenerating mixture of air and fuel vapor to the desired exhaust emission performance of the engine.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a canister purge valve and a process for operating the canister purge valve that is suitable for varying operating conditions and for large flow volumes of a mixture of air and fuel vapor.
This and other objects are achieved according to the present invention by an adjustable canister purge valve. The purge valve comprises a first connection for an intake pipe of an engine; a second connection for a filter; a first, adjustable valve; and a second valve. The first and second connections are interconnected through the first and second valves and the valves are arranged in parallel.
The above and other objects are also achieved according to thc present invention by a method of operating a canister purge valve. The method comprises the steps of providing a first controllable valve having a first flow cross-section and arranged between a first and a second connection through which a regenerating mixture of air and fuel-vapor flows and which can be opened for regenerating an activated carbon filter; and providing a second valve between the first and second connections and connected in parallel with the first valve.
Further advantageous characteristic features of a preferred embodiment of the present invention are explained in detail in the attached drawing. Additional developments of the invention are provided by combining these developments and the characteristic features referred to above.
REFERENCES:
patent: 4127097 (1978-11-01), Takimoto
patent: 5060621 (1991-10-01), Cook
patent: 5216998 (1993-06-01), Hosoda
patent: 5289811 (1994-03-01), Covert
patent: 5353220 (1994-10-01), Osanai
patent: 5375579 (1994-12-01), Murai
patent: 5396873 (1995-03-01), Yamanaka
patent: 5456238 (1995-10-01), Horiuchi
Geiger Ulrich
Kloda Martin
Schmidt Christof
Miller Carl S.
Siemens Canada Ltd.
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