Abstract: A system and method for monitoring engine performance characteristics such as knock and misfire. The system includes a pressure sensor coupled to an exhaust manifold of an engine being monitored by the system, a motion sensor operatively coupled to the engine's block, an engine position sensor, a load sensor and a processor adapted to independently process the outputs of the pressure sensor and the motion sensor to determine an occurrence of a knock event. The outputs of the pressure sensor and engine position sensor are processed to identify which cylinders are knocking. The outputs of the pressure sensor, load sensor and engine position sensor are processed to determine an occurrence of a misfire condition and to identify which cylinders are misfiring.

Abstract: A high-sensitivity capacitive oil deterioration and level sensor includes a conductive housing member with an inner surface defining a ground electrode and conductive inner member with an outer surface defining a measuring electrode. The housing member is adapted to provide a fluidic connection between an oil container and a gap between the ground electrode and the measuring electrode. The sensor also includes electronics adapted to employ this capacitor geometry to generate signals indicative of a degree of deterioration and a level of the oil within the gap.

Abstract: A sensor assembly for measuring characteristics of motor oil in a vehicle includes a housing adapted to be mechanically coupled to a vehicle for receiving motor oil of the vehicle and at least one capacitive sensor including sensing electrodes positioned relative to the housing to measure characteristics of motor oil between the sensing electrodes. The sensing electrodes are coated with a soot build-up inhibiting coating which, in a preferred embodiment, is a silicone coating. The at least one capacitive sensor include an oil level sensor and an oil deterioration sensor in a preferred embodiment.

Abstract: A sensor assembly includes a tilt sensor, an oil level sensor, an oil temperature sensor and an oil deterioration sensor, as well as associated output signal conditioning electronics integrated within a common assembly. The sensor assembly is configured to receive a volume of motor oil proportional to a total volume of oil in an engine. The oil level sensor, oil temperature sensor and oil deterioration sensors include electrodes which are completely or partially immersed in the volume of motor oil depending upon the total volume of oil in the engine. The tilt sensor includes only two electrodes both of which are at least partially immersed within a controlled volume of dielectric fluid which is physically and electrically isolated from the volume of motor oil. One of the electrodes of the tilt sensor is completely immersed in the controlled volume of dielectric fluid independent of an angle of the tilt sensor relative to a vector representing forces such as gravity applied to the tilt sensor.

Abstract: An oil deterioration and contamination sensor includes a housing, a substrate with a first capacitive plate mounted within the housing, a second capacitive plate mounted to the housing close to the first capacitive plate, and a total reference capacitor which includes an external fixed reference capacitor. The second capacitive plate is mounted to the housing such that at least one fluid including oil freely circulates within a gap between the first and second capacitive plates thereby defining an oil deterioration and contamination sensor capacitor. The respective capacitances of the oil deterioration and contamination capacitor and the total reference capacitor provide an indication of a dielectric constant of the at least one fluid including oil within the gap.

Abstract: A simplified capacitive pressure transducer includes a conductive surface, a portion of which is a surface of a flexible diaphragm in direct contact with a pressure to be measured, and an insulating substrate defining a plurality of capacitor electrodes sized to accommodate the measurement of pressures within a particular pressure range. The pressure transducer includes a front housing and a rear housing which are fitted together to provide a transducer chamber within which a hybrid circuit is secured. The insulating substrate includes a reference capacitor electrode, a variable capacitor electrode and vias. The insulating substrate is mechanically coupled to the front housing such that the conductive surface of the front housing and the reference capacitor electrode form a reference capacitor, and the conductive surface and the variable capacitor electrode form a variable capacitor.

Abstract: An oil deterioration sensor includes a housing, a substrate with a first capacitive plate mounted within the housing, a second capacitive plate mounted to the housing close to the first capacitive plate, and a total reference capacitor which includes an external fixed reference capacitor. The second capacitive plate is mounted to the housing such that oil freely circulates within a gap between the first and second capacitive plates thereby defining an oil deterioration sensor capacitor. The respective capacitances of the oil deterioration capacitor and the total reference capacitor provide an engine oil deterioration indication for the oil within the gap. The first capacitive plate is divided into a major sensing area, and a minor sensing area covering a relatively small portion of the total area of the first capacitive plate. The major sensing area and the second capacitive plate form the oil deterioration sensor capacitor.

Abstract: An engine misfire detection system and method for successfully detecting and identifying misfiring engine cylinders over varying engine cycle rates and under varying engine load conditions in real time are embodied in a manifold absolute pressure sensor, an engine position (CID) sensor, a misfire sensor and misfire detection system electronics. The system utilizes empirical misfire signal signatures of misfire sensor signal range values over different engine cycle rates and under varying engine load conditions to detect a misfire condition. The system further utilizes an index ratio, which is determined from a number of samples of the misfire sensor signal taken during an engine cycle and from the engine's rate of operation, to identify which cylinder of the engine has misfired.

Abstract: An automobile engine has a pressure transducer in its exhaust system, and misfires are identified by the pressure drop accompanying the misfire, and the timing of the pressure drop relative to the cylinder identification signal. This may be accomplished digitally, sampling the pressure level at a rate of 1,000 cycles per second or more, and statistically analyzing the samples representing relative pressure. The sharp pressure drop and the range of pressures are important parameters in identifying the misfiring cylinder.

Abstract: A simple, reliable, compact and inexpensive automobile engine misfiring detection system includes a basic capacitive pressure transducer, attached to a bleeder pipeline equidistantly from each point where the exhaust manifold is attached to the engine, and made of two closely spaced insulating plates whose opposed faces contain conductive layers, and one of which plates is a flexible diaphragm of low mechanical hysteresis. The transducer is thus coupled to a variable exhaust gas pressure source which under normal operating conditions remains at a substantially constant pressure level. The output signal from the transducer has its high-frequency AC component attenuated by a low-pass filter, whose output in turn has its DC component substantially removed by capacitive blocking, after which the remaining AC output is then amplified by a circuit including an operational amplifier.

Abstract: A resistive pressure transducer wherein a flexible diaphragm is mounted in a spaced apart relationship to the upper surface of a base member. A conductive path is deposited on one surface of the diaphragm. A resistive configuration is also deposited on the same surface of the diaphragm. The resistive configuration includes four separate resistive patterns. The first and third resistive patterns are deposited in close proximity to the outer edge of the diaphragm. The first and third resistive patterns are each comprised of three radially extending resistors, spaced apart along the periphery of the diaphragm, and interconnected by conductive material. The second and fourth resistive patterns are deposited in close proximity to the center of the diaphragm. The first and third resistive patterns measure radial strain, while the second and fourth resistive patterns measure tangential strain. The four resistive patterns each forms a separate leg of a Wheatstone bridge configuration.

Abstract: A simple, reliable, compact and inexpensive fluid pressure discontinuity analysis system includes a basic capacitive pressure transducer, made of two closely spaced insulating plates whose opposed faces contain conductive layers, and one of which plates is a flexible diaphragm of low mechanical hysteresis. The transducer is coupled to a variable pressure source which under normal operating conditions remains at a substantially constant pressure level. The output signal from the transducer has its high-frequency AC component attenuated by a low-pass filter, whose output in turn has its DC component substantially removed by capacitive blocking, after which the remaining AC output is then amplified by a circuit including an operational amplifier. This AC-amplified signal is then compared with a "reduced-magnitude average" reference signal (produced by an AC-to-DC conversion side-circuit followed by magnitude-level adjustment).

Abstract: A radically simple, reliable, inherently accurate, intrinsically wide-pressure-range adaptable, low to ultra-high pressure capable capacitive transducer is made from a reference capacitor and a variable capacitor, one electrode of each of which is formed of a flat conductive layer on a circular insulating plate. The reference capacitor electrode is a peripheral annulus surrounding the central disk constituting the variable capacitor electrode. The insulating plate is rigidly held slightly spaced apart from a flat, flexible metal diaphragm which provides the opposing electrode for each capacitor. The diaphragm is an integral part of a pressure fitting which includes a fluid pressure input coupling and a pressure chamber adjacent to the diaphragm.

Abstract: A simple, reliable and inexpensive ultra high pressure transducer includes a basic capacitive transducer, made of two closely spaced insulating plates whose opposed faces contain conductive layers, and one of which plates is a thin and flexible diaphragm of low mechanical hysteresis. In mechanical coupling proximity with this insulating diaphragm is a thick metal diaphragm which is a part of the ultra high pressure coupling component. The flexure of this thick metal diaphragm under ultra high pressures, which are applied only on the side opposite the insulating diaphragm, determines the magnitude of the deflection of both diaphragms, and, corresponding to the resultant output capacitance level, provides a measure of the ultra high pressure level.

Abstract: A versatile low cost capacitive type of electrical pressure transducer includes a sensor module providing an output signal indicative of fluid pressure effective thereon, and an elongate cylindrical housing receiving the module and providing for communication thereto of a first fluid pressure (which may have a high pressure level), and of a second fluid pressure (which may range from a vacuum through atmospheric pressure to a pressure level of a few hundred pounds). Consequently the transducer may operate as a gauge pressure sensor or as a differential pressure sensor. Alternatively, other types of sensor modules may also be employed in housings of the same or substantially the same design to fulfill other types of pressure measurement tasks. The commonality of component parts of the various sensors contributes to a reduces cost. Also, the components of the housing are economical to manufacture and assemble, and provide for testing and calibration of the sensors at an intermediate step of manufacture.

Abstract: A pressure transducer includes two plates of insulating, high strength low hysteresis material. At least one of the plates is thin so as to form a flexible diaphragm at the pressure levels to be measured. Both plates have a thin layer of conductive material on their facing surfaces. The diaphragm plate has a thin metallized layer fired onto its periphery on the opposite side from the conductive layer. The plates are bonded together and spaced apart by a peripheral layer of frit. This combination forms a capacitor which varies in capacitance as the diaphragm deflects. The capacitor is peripherally mounted to a shoulder within a plated fitting in a manner which allows fluid to enter a pressure chamber which applies fluid across the surface of the diaphragm. The peripheral mounting is accomplished by soldering the metallized layer to a shoulder on the fitting extending around the pressure chamber.

Abstract: A pressure transducer for measuring the difference in pressures between two liquids, includes two very closely spaced plates, at least one of which is a diaphragm, and opposed conductive coatings on these two closely spaced plates. The space between the two plates is evacuated, and a low viscosity silicon oil is drawn in through a conduit to completely fill the space between the two plates. The conduit leading to the space between the plates is filled up to a certain point with the low viscosity fluid, and a thin membrane or bellows tightly seals this conduit. One of the two liquids, the pressure of which is to be measured, is channelled to the outer side of the membrane or bellows; and the other of the two liquids is conducted to the outer surface of the diaphragm of the pressure transducer.