US 12,421,929 B2
Ignition circuit for a combustion engine
Florian Schumann, Fellbach (DE)
Assigned to Andreas Stihl AG & Co. KG, Waiblingen (DE)
Filed by Andreas Stihl AG & Co. KG, Waiblingen (DE)
Filed on Feb. 7, 2023, as Appl. No. 18/165,763.
Claims priority of application No. 22155636 (EP), filed on Feb. 8, 2022.
Prior Publication US 2023/0250789 A1, Aug. 10, 2023
Int. Cl. F02P 5/15 (2006.01)
CPC F02P 5/1504 (2013.01) [F02P 5/1508 (2013.01)] 13 Claims
OG exemplary drawing
 
1. An ignition circuit for a combustion engine defining a combustion chamber, said combustion engine including:
a spark plug arranged in said combustion chamber and a piston delimiting said combustion chamber;
said piston being movable in a reciprocating manner between top dead center and bottom dead center;
a crankshaft and a connecting rod connecting said piston to said crankshaft to facilitate rotation of said crankshaft via said connecting rod; and,
an intake channel having a control element for apportioning combustion air for an idle situation and an acceleration situation of said combustion engine;
said ignition circuit comprising:
an electronic control circuit configured to trigger an ignition spark at said spark plug in dependence upon a crankshaft angle (CA) of said crankshaft at an ignition time (IT);
said control circuit being provided with at least one ignition time point (IT) for said idle situation and at least one ignition time point (ITA) for said acceleration situation;
said control circuit being configured, in said idle situation, to set the predetermined idle time point (IT) for said idle situation; and,
said control circuit being further configured, in said idle situation, to monitor the course of a rotational speed (N) of said crankshaft over at least one predetermined crankshaft angle range, wherein a compression stroke of said combustion engine at least partially lies in said at least one predetermined crankshaft angle range, and, in said idle situation, to detect a drop in rotational speed (Δn), occurring within said at least one predetermined crankshaft angle range, in said rotational speed (N) of said crankshaft as a value, and being configured to compare said value of said detected drop in rotational speed (Δn) with a predetermined value of a drop in rotational speed (ΔnL) and, when said predetermined value (ΔnL) of said drop in rotational speed (Δn) is exceeded, to switch over to said ignition time point (ITA) for said acceleration situation.