Abstract: An air management valve in the exhaust emission control system for the engine of an automotive vehicle is operative to selectively control secondary air flow to the exhaust manifold next adjacent to the exhaust ports of the engine, to the center of a dual bed catalytic converter and to the atmosphere.

Abstract: A fluidized bed has an aperture plate which is inclined to the horizontal, to cause excessively large or dense particles to migrate to a collection point from which they may be removed from the particulate mass. Disruption of fluid flow through the aperture plate due to settled out particles is thus avoided. Preferably the aperture plate is made of a material which has the same permeability as the fluidized mass, thus inherently providing flow regulation necessary for even fluidization above the slope plate. To make investment casting molds, a gravity "rainsander" device is coupled with a fluidized bed. When slurry used in the mold making process drips from a pattern it falls into the fluidized bed thereby converting the errant drops into particulate balls which are conveniently removed.

Abstract: A power brake system has a brake booster operable by differential air pressure provided by a source of vacuum and a source of compressed air pressure. The differential air pressure control valve assembly of the invention maintains a substantially constant available differential of air pressure between the vacuum and compressed air pressures available to the brake booster for booster operation. In the charging mode it directs air pressure from an air pressure pump to an accumulator connected to the pressure inlet side of the booster, charging until the desired pressure differential is attained. In the storage mode, the air pressure from the pump is permitted to flow in its usual manner to another device or circuit utilizing the air pressure. This may be, for example, a part of the vehicle engine emission control system. In the pressure relief mode, the control valve vents excess accumulated pressure to exhaust.

Abstract: A transducer modifies a subatmospheric pressure signal to create an operating pressure which positions an exhaust gas recirculation control valve. A regulating unit senses subatmospheric induction passage pressure to provide the pressure signal and prevents the pressure signal from dropping below a lower limit to thereby establish the maximum exhaust gas recirculation area produced by the control valve.

Abstract: Disclosed is an improved method for making molds and mold components for use in casting single crystal articles. According to the improved method, a preformed and reusable replica of a mold growth cavity and crystal selector passage is provided, the replica including a cylinder in the form of the desired growth cavity and a helical strand in the form of the desired crystal selector passage, one end of the strand being attached to an end of the cylinder such that their axes are coincident. In one embodiment, the replica is coated with a thin layer of wax or other removable material and then utilized in a variety of mold making processes, including investment molding, to form a growth zone and helical crystal selector in the mold.

Abstract: The present invention provides an improved method for making ceramic slurries useful in forming casting molds. The method involves placing the slurry ingredients in a mixing container, removing sufficient air from the container to prevent subsequent air entrapment, mixing the slurry ingredients by epicyclic agitation to effect rapid particle wetting and homogenization and removing the slurry from the container after agitation is terminated, the ceramic slurry being ready for immediate use. Total slurry preparation time is generally one hour or less, as compared to the 24 to 36 or more hours required for prior art slurry preparation techniques.

Abstract: An enclosure designed to maintain the purity and physical characteristics of a slurry within a preferred range during the manufacture of shell molds is disclosed. The tank is in the form of a trough with flat side walls and a curved member forming the front, bottom and back of the trough. The entire trough is water cooled and a cover along the top completes the enclosure. The enclosure is fitted with means for circulating the slurry and a liner having an airfoil member. Various sensing and control means are interconnected through a feedback system which continuously monitors and controls the conditions of the slurry.