Internal-combustion engines – Accessories – Covers – trays – vibrators – corrosion inhibitors – air filters
Reexamination Certificate
2000-03-29
2001-05-29
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Accessories
Covers, trays, vibrators, corrosion inhibitors, air filters
Reexamination Certificate
active
06237559
ABSTRACT:
FIELD OF THE INVENTION
The field of the present invention is that of automotive engines, in particularly automotive engines having cylinder deactivation.
BACKGROUND OF THE INVENTION
Four stroke cylinder multi-cylinder reciprocating internal combustion engines used in automobiles are capable of being operated over great speed and load ranges. Those skilled in the art have recognized for years that lower specific fuel consumption is usually achieved when an engine is operated at relatively high load. This is particularly true for spark ignition engines because throttling losses are minimized when the engine is operated at or near wide-open throttle at full load conditions. Unfortunately, in automotive usage, engines are frequently required to operate at less than maximum load. While an engine operates at part load, fuel economy suffers because of the pumping loss. Therefore, it is desirable to avoid partial load operation of the engine.
Engines have been designed that avoid part-load operation by deactivating some of the cylinder combustion chambers so as to allow the remaining active cylinders to be operated at higher loads. For example, it is noted to deactivate both the intake and outlet valves of one or more cylinders in an engine, which traps air in the deactivated cylinders. The trapped air is alternately compressed and expanded and acts as a pneumatic spring (See FIG.
3
). This method of cylinder deactivation is highly efficient however, a small problem can occur at low pressures at bottom dead center piston position with oil pumping into the cylinder. More significantly, prior art systems which deactivate both the intake and exhaust poppet valves of an engine cylinder are quite expensive and are therefore unattractive because vehicles in which fuel economy is most important are frequently sold in a lower price range.
Stockhausen et al., U.S. Pat. No. 5,642,703 commonly assigned, provides an internal combustion engine wherein the operation of the intake and exhaust poppet valves are phase retarded in equal amount to produce valve lift events which are approximately symmetric with respect to the bottom dead and the top dead center positions of the piston motion, respectively. The phase retardation of the intake and exhaust poppet valves results in gas being expelled during the exhaust stroke back into the manifold to be reintroduced into the cylinder during the start of the intake stroke and gas being introduced into the cylinder at the end of the intake stroke being pushed back out of the cylinder during the start of the compression stroke. The engine of Stockhausen et al. has a slight pump working penalty. Additionally, controlling the transition between actuated cylinder condition and deactivated cylinder condition can sometimes be difficult. It is also difficult to determine the point of no net flow. Lastly, the internal combustion engine according to Stockhausen et al. requires increased exhaust valve to piston clearance (needs nearly a free wheeling engine) and a very wide range (90 degrees) cam retard phase shifter with rapid response is required.
SUMMARY OF THE INVENTION
The present invention provides a four-cycle internal combustion engine with cylinder combustion chamber deactivation with very low pumping losses. The deactivated cylinder of the present invention has an exhaust poppet valve which can be selectively disabled. The intake poppet valve or valves of the deactivated cylinders are not disabled but are opened and closed generally symmetrically about a top dead center or bottom dead end center position of the piston. The change from normal operation of the intake poppet valve is achieved by a phase variable cam. Often the phase variable cam is already provided as a method of reducing fuel gas emissions and improving fuel economy. In one preferred embodiment of the invention, the opening and closing of the inlet valve is retarded approximately 65 degrees. Accordingly, the intake event is symmetric about the piston bottom dead center position. Equal amounts of flow are pulled into the deactivated cylinder during the intake cycle and expelled from the cylinder during the first part of the compression stroke thereby minimizing pumping work. The present inventive internal combustion engine is highly adaptable to deactivate one bank of cylinders in any bank-to-bank firing engine. The level of intake cam retard required by one preferred embodiment of the present invention is only slightly more than typical for part-load dual cam equal cam phasing engines which already require approximately 50 degrees of retard. The internal combustion engine of the phase retarded version of the present invention does not require any additional exhaust valve-to-piston clearance. The present invention provides cylinder deactivation at a much lower cost in engines that already incorporate dual equal or intake-only cam phasers. In engines where there is dual variable cam timing, the engine only requires valve disablement for the exhaust valves on one bank of the engine. No valve disablement will be required for any of the intake valves.
It is an object of the present invention to provide a four-cycle internal combustion engine that has cylinder deactivation by disabling the exhaust poppet valve on the deactivated cylinder to a closed position and phase varying the operation of the inlet poppet valve so that pumping losses are significantly reduced.
The above noted object and other features of the present invention will become better known to one skilled in the art from a review of the accompanying drawings and detailed description of the invention.
REFERENCES:
patent: 3441009 (1969-04-01), Rafanelli
patent: 4516542 (1985-05-01), Aoyoma et al.
patent: 4862845 (1989-09-01), Butterfield et al.
patent: 5467748 (1995-11-01), Stockhausen
patent: 5642703 (1997-07-01), Stockhausen
patent: 59-201911 (1984-11-01), None
Russ Stephen George
Stein Robert Albert
Stockhausen William Francis
Drouillard Jerome R.
Ford Global Technologies Inc.
Kamen Noah P.
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