Bear Automotive Service Equipment Co.

Spx Corporation

Peter A Puetz

Joseph A Marino

Michael J Kling

Surender K Makhija

Gary R Kercheck

Michael P Alusick

John M Surwillo

Robert T Braun

John C Pendell

Dennis L Hechel

John Hintz

Michael C Crawford

Majid Taghikhani

Michael J Kling, Iii

Curtis A Finn

An input protection circuit protects a multiplexer used in an automotive breakout box for coupling to an electronic control module (ECM) of an automotive vehicle. The input protection circuit includes resistors connected between the input and the multiplexer and a negative feedback amplifier connected to the output of the multiplexer. The negative feedback amplifier provides a virtual ground. Additionally, the inputs to the multiplexer are clamped to within one diode forward voltage drop of electrical ground by diode pairs.

Automotive test system with input protection

A wheel alignment system uses head units attached to each of the four wheels of an automotive vehicle. Angle measurements are taken using light sources and light sensors. Pitch sensors measure the pitch of the head units with respect to a horizontal plane. The head units are connected to the left and right front wheels of the automotive vehicle. The pitch information is used to compensate for errors in left and right cross-toe measurements between the left and right front wheels of the automotive vehicle.

Method and apparatus for measuring cross-toe

A cross toe zero calibration system for use in an automotive vehicle wheel alignment system uses a calibration bar for receiving cross toe measuring head units. A first set of cross toe measurements are taken with the bar in a first position and a second set of cross toe measurements are taken with the bar in a second position. In the second position, the bar is rotated 180.degree. from the first position. The two sets of measurements are averaged to yield zone cross toe angle calibration factors. The combination of rotating the bar and averaging the two sets of measurements nulls out errors introduced into the calibration measurements due to deformities in the bar. The calibration bar is mounted on the main console of an automotive vehicle wheel alignment system. Switches are included which indicate the position of the bar. A computer in the automotive vehicle wheel alignment system prompts an operator through the steps of calibration, accepts the calibration measurements and calculates the calibration factors.

Calibration bar

A wheel alignment system measures caster and steering axis inclination (SAI) by positioning the wheels at a right turn position and a left turn position. Toe, camber and inclination angle measurements are made for both wheels at both the left turn position and the right turn position. Based upon these measurements, caster and SAI are calculated either directly or through an iterative technique.

Caster and steering axis inclination measurement technique

A signal representing the RPM of an internal combustion engine is produced by a signal processor connected to the battery of the vehicle. The signal processor derives an electrical signal from the battery which contains signal components produced by operation of the vehicle ignition system, as well as components from a multitude of other sources such as the voltage regulator, fans, air conditioning and other electrical systems of the vehicle. The signal processor filters and signal processes the signal derived from the vehicle battery to produce a signal having a frequency which is related to the RPM of the engine.

Battery tach

A wheel alignment system uses head units attached to each of the four wheels. The front head units contain photodetector arrays which view across the front of the vehicle and to the rear. The rear units carry photodetector arrays which look forward. Each photodetector array views a target on one of the other head units. A microcomputer in each head unit determines an angular value based upon the position of the target image on the photodetector array. The angle values determined by the microcomputers of the individual head units are supplied to a master computer in a main console which determines individual toe angles with respect to a tread centerline for either the front two wheels or for all four wheels. The master computer controls a display at the main console, as well as a remote display to guide the mechanic in making alignment adjustments.

Growing community of inventors

Waukesha, WI, United States of America

Peter A Puetz