Abstract: This invention relates to an apparatus for sensing a vehicle steering wheel position. A permanent magnet target wheel having a global axial magnetic field normal to a first surface is attached to a steering shaft which is rotated by the steering wheel. Multiple regions equally spaced along a common radius on the first surface are magnetically altered and sensed by magnetically responsive sensors positioned adjacent the first radius. A single region positioned within a finite radius along a second radius on the first surface is magnetically altered and sensed by a magnetically responsive sensor positioned adjacent the second radius. The magnetic sensors are responsive to passage of the multiple regions and single region as the target wheel is rotated. Detection of each of the multiple regions corresponds to rotation of the target wheel by an incremental number of degrees.

Abstract: The present invention is directed to an electrical circuit for detecting the presence of combustion within a catalytic converter preheater. Combustion of an air/fuel mixture within the preheater results in a wide-band high voltage RF signal across a spark plug gap disposed within the preheater, which is trapped by an ignition coil coupled to the spark plug for energizing the spark plug gap. The presence of combustion will effectuate an elimination or absorption of one or more specific frequencies within the RF voltage band. By coupling a combustion detection circuit comprising an inductor-capacitor (L-C) or resistor-inductor-capacitor (R-L-C) network between ground and a low voltage output terminal of a secondary winding of the ignition coil, and properly tuning the network components to one of the specific absorption frequencies, an output voltage of the combustion detection circuit during discharge of the spark plug will be responsive to the absence or presence of combustion in the burner.

Abstract: A distributorless ignition system for an internal combustion engine which discharges only one spark plug at a time. A high-level reversible voltage potential in selectively induced in the secondary winding of an ignition coil. Opposing diodes connected to the secondary winding permit application of the induced voltage across only one of two spark plug gaps, the central electrode of the spark plug being negatively charged with respect to ground to effectuate discharge with reduced power requirements and electrode erosion.

Abstract: An idle air control system diagnostic for an internal combustion engine which utilizes RPM, engine timing and intake airflow measurements to detect the presence of idle RPM faults and eliminate or verify the idle air control system as the fault source. Engine idle RPM is measured and compared with a commanded idle RPM, and if within a predetermined range, an idle RPM fault exists and one of two additional tests (non-intrusive and intrusive) is conducted to determine whether the idle air control system is the source of the fault. In the non-intrusive test, intake airflow is measured and compared to a predetermined intake airflow value, and if not within a predetermined range, the idle air control system is determined to be the fault source. In the intrusive test, variations in intake airflow (or intake manifold pressure) are measured in response to variations in the movement of the engine throttle-bypass airway pintle.

Abstract: A method and apparatus for electrically exciting a magneto-resistor (MR) device that is adapted to sense variations in a magnetic field. Electric current is delivered to flow through the MR device and produce a voltage drop across the resistance the MR device, where the voltage drop varies in accordance with changes in the flux density of the sensed magnetic field. The current flowing through the MR device is limited to a predetermined maximum current value to prevent damage to the MR device due to self heating at elevated operating temperatures. When the delivered current is less than the predetermined maximum current value, the current flowing through the MR device is controlled to maintain a measured characteristic of the voltage drop appearing across the MR device at a desired value. This increases the sensitivity of the MR device over its operating temperature range to variations in the sensed magnetic field.