Apparatus for measuring engine timing independent of speed

Claim 1

Engine timing measuring apparatus for an engine having a chamber, a member movable in the chamber, combustion means for creating the combustion of fuel in the chamber so that the member is driven with respect to the chamber and an indicia to indicate the relative position of the chamber and the member, said apparatus comprising: lamp means for illuminating the indicia in response to a strobe signal; trigger means for generating a trigger signal in response to the operation of the combustion means to create the combustion of fuel in the chamber; means for storing a variable timing voltage; reference means for generating a reference voltage, said reference voltage being fixed during normal operation; control means responsive to each trigger signal for altering the timing voltage in a first direction at a first predetermined rate until the timing voltage attains a predetermined relationship with respect to the reference voltage, for generating a strobe signal each time the timing voltage attains the predetermined relationship with respect to the reference voltage, and for altering the timing voltage in a second direction opposite the first direction at a second predetermined rate from the time the timing voltage attains the predetermined relationship with respect to the reference voltage until the next trigger signal is generated; adjustment means for altering the first predetermined rate until the lamp means illuminates the indicia in a predetermined position; and scale means connected to the adjustment means for displaying the degree of movement of the member relative to the chamber between the time the trigger signal is generated and the time the lamp means is illuminated, whereby the degree of movement is accurately displayed irrespective of changes in speed of the member relative to the chamber.