Abstract: An electromagnetic fluid flow control valve mechanism has a hollow slide valve linearly movable on and along a core in response to energization of a coil disposed around the slide valve for selective fluid communication between a inlet port and first and second outlet ports through a chamber in a casing. The ratio of a cross-sectional area of the inlet port to that of each of the first and second outlet ports is selected such that the chamber will develop a relatively small vacuum such as of 20 mmAg at maximum. Preferably, the ratio is 6.5 or greater. This arrangement prevents a fluid, typically air, from flowing from the second outlet port back into the chamber.

Abstract: A motor-driven proportional fluid flow control valve has a linear motor including a slide valve body slidably mounted on a hollow iron core and an electromagnetic coil wound around the iron core. After a drive circuit has been energized, a constant current is passed through the electromagnetic coil to keep the slide valve body spaced from a stop surface while cutting off fluid communication between an inlet port and an outlet port. With the slide valve body out of contact with the stop surface, the slide valve does not produce noise which would otherwise be given off due to a fluctuating current flowing, through or vibrations of, the electromagnetic coil.

Abstract: An exhaust gas recirculating control system for internal combustion engines including an engine vacuum operated exhaust gas recirculating valve which allows recirculation of the engine exhaust when a high vacuum is applied, an engine vacuum operated vacuum control valve which allows air pressure to be applied to the exhaust gas recirculation valve when the engine vacuum exceeds a predetermined level, and a vacuum transmitting valve which delays in time the application of engine vacuum to the vacuum control valve. In this way, exhaust gas recirculation occurs during a fixed period after acceleration of the vehicle occurs.