Snap-on Tools Corporation

Snap-on Technologies, Inc.

Daniel Mieczkowski

Steven E Michalski

Thomas P Becker

Matthew M Crass

Larry D Pacetti

Mark J Hasenberg

Donald J Caldwell

Robert D Braun

Edward T Gisske

David R Ellingen

Robert J Holmen

John E Stanley

Robert D Johnson

Kevin M Andrews

An evaporative emission tester is used to evaluate the integrity of a vehicle's evaporative emission control system, including determining the system's purge capability. The emission tester performs a purge flow test to determine whether fuel vapor stored in the vehicle's evaporative canister and present in the fuel tank is being drawn into the engine for combustion at a minimum amount. The emission tester also performs a pressure test of the vehicle's evaporative canister purge system, which includes the fuel tank and lines. The emission tester can function as a stand-alone unit or as an integrated product with a host computer.

Evaporative emission tester

A hand-held contact tachometer includes an elongated hollow handle comprising two interconnected members defining a clevis at one end thereof and carrying therewithin a magnetic sensor disposed adjacent to the clevis and conditioning circuitry coupled to the output of the sensor. The clevis has hub portions defining an axle on which is rotatably mounted a contact wheel of molded construction including a body of non-magnetic material in which is embedded a toothed magnetic wheel and a bearing. The wheel is provided with a frictional ribbed surface on its outer periphery to facilitate engagement with an associated moving surface, thereby rotating the wheel to generate a pulsating signal having a frequency proportional to the speed of the moving surface.

Hand-held magnetic contact tachometer with toothed rotatable wheel

Combined automotive electrical testing module and holder/display therefor

The modular electronic device includes a main unit and at least one plug-in module adapted to be removably slid on to and mounted on the main unit. There are first and second interfitting connectors respectively on the main unit and the module which automatically interfit when the module is mounted. First and second interfitting track structure are respectively on the module and main unit to facilitate sliding the module onto the main unit. Finally, there is first and second interfitting latching elements respectively on the main unit and the module to hold the module latched in place.

Modular electronic device

A sensor is periodically energized and the sensor output is amplified, the amplified signal being applied to two sample-and-hold circuits which are alternately activated in response to the sensor drive, one being activated only when the sensor is energized and the other being activated when the sensor is not energized. One of the samples is subtracted from the other in a summer for cancelling the amplifier offset. The summer output may be buffered, and there is also applied to the summer an offset correction signal for cancelling sensor offset and buffer offset inaccuracies.

Method and apparatus for low power offset correction of amplified sensor

Growing community of inventors

Kenosha, WI, United States of America

Daniel Mieczkowski