Patent ID: 11905902
Assignee: BRP-ROTAX GMBH & CO. KG
Field: Engines, pumps, turbines (Mechanical engineering)
Classification: CPC F | IPC F

Claim 0:
1. A method for managing start up of a four-stroke engine, the method being performed by a controller communicatively connected to the engine, the method comprising:
determining, using a crankshaft sensor communicatively connected to the controller, an angular orientation of the crankshaft, the crankshaft being rotated by a starter motor operatively connected to the crankshaft prior to ignition of the engine;
determining, using the crankshaft sensor, at least one engine speed variation as the crankshaft rotates through at least one measurement window, determining the at least one engine speed variation including:
determining at least one first rotational speed indication of the crankshaft as the crankshaft rotates through a first portion of the at least one measurement window by:
sensing, by the crankshaft sensor, passage of a first given tooth (n) through the crankshaft sensor, the first given tooth (n) being one of a plurality of regularly spaced teeth of a gear connected to and rotationally fixed on the crankshaft,
sensing, by the crankshaft sensor, passage of a first subsequent tooth (n+1) disposed immediately adjacent to the first given tooth (n) through the crankshaft sensor, and
determining a first tooth time between passage of the first given tooth (n) and passage of the first subsequent tooth (n+1);

determining at least one second rotational speed indication of the crankshaft as the crankshaft rotates through a second portion of the at least one measurement window, by:
sensing, by the crankshaft sensor, passage of a second given tooth (m) through the crankshaft sensor,
sensing, by the crankshaft sensor, passage of a second subsequent tooth (m+1) disposed immediately adjacent to the second given tooth (m) through the crankshaft sensor, and
determining a second tooth time between passage of the second given tooth (m) and passage of the second subsequent tooth (m+1); and

calculating a difference of the at least one first rotation speed indication and the at least one second rotational speed indication; and

identifying a working cycle phase of the crankshaft comprising:
in response to an absolute value of the at least one engine speed variation being above a threshold, determining that the crankshaft is in an ignition revolution of a two revolution working cycle of the engine in the at least one measurement window,

subsequent ignition of the engine being based on determination of the angular orientation of the crankshaft and identification of the working cycle phase of the crankshaft.