Peter G. Berg

Vapor Canister Heater for Evaporative Emissions Systems

Automotive evaporative emissions systems use a charcoal canister to store evaporative hydrocarobn emissions. These stored vapors are later purged and burned during engine operation. Under certain conditions the engine cannot completely purge the canister of the stored fuel vapors, which results in a decreased vapor storage capacity in the canister. A self-regulating PTC (Positive Temperature Coefficient) heater has been developed to warm the purge air as it enters the canister, in order to provide thermal energy for increased release of the vapors from charcoal sites. This paper describes the construction and operation of the vapor canister heater as it relates to improved evaporative emission system performance.

High-Force Linear Actuator

A new type of electrically energized linear actuator has been developed for the appliance industry which offers high-force output from a small inexpensive package. The new linear actuator uses a single solid-state component to control the operation of the device. The actuators response is noninstantaneous, which allows it to be used in designs where time delay is required or where rapid response is unnecessary. Its size, mounting options, and cost are comparable to a low-cost solenoid. However, the force output of this device exceeds by an order of magnitude or more the force output of a solenoid of the same size. Unlike a solenoid, the actuators force output does not change with ambient or voltage variations, and its high-force output does not vary over its stroke. When compared with a solenoid of approximately the same force output capability, the actuator operates on less than one-tenth the steady-state power consumption. The actuator can be operated in the push, push-pull, or pull mode. For example, a unit 1 in in diameter and 2 in long, weighing about 1.5 oz can operate against a 12 lb external load over its entire 0.250-in stroke. Because of its unique operating parameters, it can be successfully adapted to applications where solenoids, gear motors, pneumatic actuators, and other conventional actuators will not do the job, or as a low-cost replacement for a high-force actuator.