Abstract: The purge valve embodies a solenoid that has a linear force vs. current characteristic acting on the armature. Effects of hysteresis are minimized by certain constructional features and the manner of operating the valve. Several embodiments are disclosed.

Abstract: A vacuum sustaining valve (VSV) for temporarily sustaining at least some engine intake manifold vacuum to an EGR valve when engine intake manifold vacuum falls below a predetermined value. The VSV has an inlet port, an outlet port, and a flow path between the two ports. A check valve is disposed with the flow path and is selectively positioned in accordance with manifold vacuum. When manifold vacuum is above a predetermined magnitude, the check valve is positioned to allow bi-directional flow between the two ports. When manifold vacuum is below the predetermined magnitude, the check valve is positioned to function as a check that allows vacuum to pass from the inlet port to the outlet port, but not in the opposite direction.

Abstract: An on-board diagnostic system for an evaporative emission control system of an internal combustion engine powered vehicle employs a positive displacement reciprocating pump to create in evaporative emission space a pressure that differs significantly from ambient atmospheric pressure. The pump is powered by using engine intake manifold vacuum to force an intake stroke during which both an internal spring is increasingly compressed and a charge of ambient atmospheric air is created in an air pumping chamber space. Vacuum is then removed, and the spring relaxes to force a compression stroke wherein a portion of the air charge is forced into the evaporative emission space. The pump operation is under the control of a computer that contains an algorithm for operating the pump in particular modes of operation to arrive at a decision concerning integrity of the evaporative emission space against leakage.

Abstract: Differential flow sensing through respective flow path portions of a system for detecting leakage from an evaporative emission control system. A series flow path comprises a first flow sensor for sensing the entire output flow of an impeller pump used to positively pressurized the system under test, a second sensor in a portion of the series flow path that is downstream of the first flow sensor, and a calibrated orifice downstream of the second flow sensor. A branch circuit to the evaporative emission space under leakage test tees into the aforementioned series circuit between the first flow sensor and the second flow sensor. A differential amplifier receives signal from the respective sensors. Any difference in sensed flows, once the pressure has been brought to a predetermined pressure, is output by the differential amplifier to signify leakage in an amount correlated with the sensed difference in the flows.

Abstract: An on-board diagnostic system for an evaporative emission control system of an internal combustion engine powered vehicle employs a positive displacement reciprocating pump to create in evaporative emission space a pressure that differs significantly from ambient atmospheric pressure. The pump is powered by using engine intake manifold vacuum to force an intake stroke during which both an internal spring is increasingly compressed and a charge of ambient atmospheric air is created in an air pumping chamber space. Vacuum is then removed, and the spring relaxes to force a compression stroke wherein a portion of the air charge is forced into the evaporative emission space. The rate at which the pump reciprocates to alternately execute intake and compression strokes indicates the pressure and flow through a leak in the evaporative emission space. Detection of this rate serves as a measurement of leakage for the purpose of distinguishing integrity of the evaporative emission space from non-integrity.

Abstract: Leakage from a portion of a canister purge system which includes a fuel tank and a vapor collection canister is detected by closing off that portion and then positively pressurizing it by means of an air pump. The air that is pumped by the air pump is split into two separate paths, one to pressurize the closed-off portion of the system, and the other to flow through a known orifice. A differential flow meter compares the flow through one path with that through the other to determine if there is leakage.

Abstract: A heater control valve comprising: a valve body defining a chamber and a bypass passage extending therefrom. A first conduit in fluid communication with the bypass passage for defining a first inlet port and a first exit port adapted to communicate coolant to an external device. A second conduit, in communication with the chamber defining a second inlet adapted to receive flow from the external device and a second outlet. The valve body further including a first seating surface disposed about an upstream end of the bypass passage and a second seating surface disposed about the second inlet, and a bypass valve, rotatable from a first position in sealing engagement with the first seating surface to a second position in sealing engagement with the second seating surface, and an actuator, for rotating the bypass valve from the first position to the second position in response to control signals.

Abstract: A flow rate valve comprising a non-magnetic housing comprising a central cavity and a pressure chamber, first and second ports extending into the pressure chamber, the interior end of the first port forming a valve seat. A bobbin is received within the cavity including a coil and a central blind bore enclosed at one end. The bobbin and housing including opposingly situated circumferential grooves. An armature assembly comprising a cylindrical armature within the bore, and a valve element movable with the armature between first and second positions, for opening and closing the valve seat and a motion limiter for limiting armature motion to prevent same from impacting the bottom of the bore in response to a magnetic field generated by the coil.