This invention relates to internal combustion engines, and in particular to a device for increasing the power and gasoline mileage of an internal combustion engine, while reducing emissions of harmful substances, such as carbon monoxide and uncombusted hydrocarbons, caused by incomplete combustion of gasoline.
The need for making internal combustion engines more highly efficient has long been obvious. The need for reducing toxic emissions, such as carbon monoxide, oxides of nitrogen and hydrocarbons has now also been widely recognized.
One of the early suggestions for increasing engine efficiency was to add a "secondary carburetor" to vary the relative amount of air admitted to the engine intake manifold in accordance with the manifold vacuum. An example of such a system is shown in U.S. Pat. No. 3,039,449 (1962), to Mokrzycki. The system described therein is designed to increase air flow into the intake manifold as its vacuum becomes greater.
In recent years, positive crankcase ventilation (PCV) systems have regularly been installed on automobiles in the United States. In these systems, engine crankcase fumes are carried by a line to the intake manifold (either directly or through the base of the carburetor), rather than being vented to the atmosphere. The conduit includes a valve (PCV valve) which is intended to regulate the flow of fume-laden air to the engine intake manifold in such a way as to provide good engine performance under varying conditions of engine speed and load. The PCV valve typically is spring biased open and becomes increasingly restricted in response to increasing pressure differential across it. The PCV valve is generally located at or near the crankcase. Examples of PCV systems are shown, for example, in Pittsley, U.S. Pat. No. 3,359,960 (1967), in Sweeney, U.S. Pat. No. 3,664,368 (1972), and in Billiet, Automotive Engines--Maintenance and Repair (4th ed. 1973), at pages 280-288.
Because the PCV line offers ready access to the manifold, it has been widely used as a point of attachment for secondary carburetors. A commercial version of the Mokrzycki device was attached by cutting into the PCV line rather than into a vacuum-powered windshield wiper motor line as shown in that patent. Other systems, such as those shown in Winton, U.S. Pat. No. 3,809,035 (1974) and Dabrio, U.S. Pat. No. 3,923,024 (1975) have also been attached in the PCV line. These systems decrease auxiliary air flow as intake manifold vacuum increases.
Neither the PCV systems nor the secondary carburetor systems have been entirely successful in attaining their aims.