Abstract: A gas control unit for a gas-assisted injection molding system, wherein a quantity of gas is introduced into a mold cavity in combination with a quantity of plastic material during the molding process. The gas control unit operates on the basis of regulating the mass of gas within the system, as opposed to the final hold pressure. Because the mass of the gas is constant within the gas control unit throughout an injection cycle, a preferred initial-to-final (hold) pressure ratio can be determined through mathematical computations for a particular molding system. As a result, once the required mass of gas has been isolated from a suitable source, releasing the gas to the mold cavity results in a predictable pressure. This capability permits the gas control unit to determine whether the gas has fully expanded and, therefore, whether the gas has properly filled the mold cavity so as to produce a properly molded article.

Abstract: An automated trash compaction system having an hydraulic cylinder displacing a ram to compact trash in a mobile trash container and having an electronic control unit controlling the displacement of the ram. The electronic control unit generates a ram forward signal in response to a start signal, generates a part-full signal in response to electrical current being supplied to an electric motor driving a fluid pump exceeding a part-full value, and generates a full signal in response to the current being supplied to the electric motor exceeding a full value. After a predetermined full stroke time or upon the generation of the full signal, the electronic control unit terminates the ram forward signal and generates a ram return signal returning the ram to a retracted position. The ram return signal is terminated when the current to the electric motor exceeds a predetermined value.