Ignition devices for internal combustion engines

Claim 1

An ignition device for an internal combustion engine in which the combustion chamber is periodically placed in communication with the induction pipe before being isolated from the exhaust pipe, said device comprising means sensitive only to the rotary speed of the engine adapted to act when the engine speed exceeds a lower limit NS, and modifying means adapted to ensure, on one hand, a substantially constant value of the ignition advance on starting and on slow-running speed of the engine, up to a speed NL r.p.m., on the other hand a rapid reduction in the advance for rotary speeds of the engine comprised between NL and the speed NS, NS being greater or equal to NL and, finally on the other hand, an increase of the advance when the rotary speed exceeds NS, and wherein the modifying means are electro-mechanical means and comprise a centrifugal element rotated by the engine and acting on an electrical switching device so as to place in circuit, for rotary speeds less than NL, a first breaker and, for speeds greater than NL which is equal to NS, a second breaker angularly displaced from the first by a predetermined angle, a conventional centrifugal assembly being provided to ensure an increasing advance as a function of the rotary speed when the latter is greater than NL and the second breaker is in circuit.