Abstract: The accumulator chamber communicates with the atmosphere through a passage which is formed therein with a restriction for restricting the cross sectional area of the passage or which is provided therein with a pressure control valve for opening the passage in response to a difference between the atmospheric pressure and the vacuum in the accumulator chamber which difference is above a predetermined value to maintain the vacuum differential between the accumulator and vacuum chambers above a predetermined value when the engine suction vacuum is above a predetermined value.

Abstract: A valve regulates the pressure of secondary air discharged from a pump to a constant value. A second valve then meters the flow in accordance with the amount of air taken into the engine.

Abstract: A fuel vaporizer for internal combustion engines employs a chamber exposed to and directly below the underside of the engine carburetor and a heater wall at the bottom of the chamber to receive drops of fuel released from the engine carburetor into the intake manifold. It also includes an apertured wall having an upperside forming the bottom of the intake manifold riser and an underside forming the top of the chamber. The heater wall may be heated by exhaust gases or bypassed water from the cooling system of the engine. The chamber is shallow so that surface of the heater wall of volume of the chamber will be high enough for rapid evaporation of fuel. The drops of fuel released from the engine carburetor drop down directly onto the heater wall and fuel vapor flows out of the chamber into the intake manifold. The apertured wall is not formed with holes in the peripheral area thereof to prevent the drops of fuel from splashing and/or spilling out of the chamber into the intake manifold.

Abstract: A pressure control valve for venting excess air pressure in a secondary air supply conduit opening to an exhaust system of an internal combustion engine has a relief valve member to close a vent port through which excess air pressure in the secondary air supply conduit is vented. The valve member is directly operable in response to excess pressure in the secondary air supply conduit. This valve member is fixedly secured to one end of a stem slidably extending through a spring seat. The stem has at its opposite end a flange and a coil spring is compressed between the spring seat and the flange to urge the relief valve to its vent port closing position. The spring seat is spring biased in a direction toward the flange to increase compression of the coil spring and it is also moved in the opposite direction in response to intake manifold vacuum by means of a vacuum servo to reduce compression of the coil spring.