Electromechanical timer with improved short interval accuracy

Abstract

An improved electromechanical timer for accurately controlling relatively short time intervals, such as fill time intervals for washing appliances. A cam-actuated switch includes a first cam-following member rigidly supported from a first contact arm and a second cam-following member movably, preferably pivotally, supported from the first cam-following member. The switch actuating control cam is of the circumferential edge track type rotatably driven by a timer motor. The first cam-following member is biased into cam-following engagement with the cam track by the resiliency of the contact arm. The second cam-following member extends between the cam track and a second contact arm and is biased into cam-following engagement with the track by the second contact arm. The cam track includes a plurality of arcuate segments of different fixed radii. The first and second contact arms are held out of electrical contact with each other by the cam-following members when the cam-following members concurrently engage segments of equal radii and are permitted to move into electrical contact with each other when the second cam-following member engages an arcuate segment of lesser radius than that concurrently engaged by the first cam-following member. The time period during which the cam-actuated switch remains closed is a function of the distance between trailing edges of the cam-following members.