Crank angle detecting system for engines

[2. A crank angle detecting system for a multicylinder engine having at least three cylinders classified as groups, which comprises:

• (a) a disc rotatable with a crankshaft and formed with a first group of slits containing a large number of slits for indicating crankshaft angular positions and a second group of slits containing a small number of slits for indicating each predetermined piston stroke of each engine cylinder, the slits of said second group having at least three widths which are different from each other;
• (b) sensing means for indicating crankshaft angular positions by detecting said slits of said first group of slits and producing crank angle signals corresponding to said detected slits of said first group and for indicating each predetermined piston stroke of each engine cylinder by detecting said slits of said second group of slits and producing cylinder signals corresponding to said detected slits of said second group, each of said cylinder signals having a duration which corresponds to one of said different widths;
• and
• (c) means (17, 18) for identifying the detected cylinder signals by counting crank angle signals occurring during the duration of each said crank angle signal and classifying the cylinder signals based on the counted number of crank angle signals.]

A crank angle detecting system for a multicylinder engine, comprising:

• a) a plurality of engine cylinders in which spark plugs are installed respectively, said cylinders being classified into a plurality of groups and each group being constituted by a pair of cylinders such that while the one of the cylinders is in an explosion stroke, the other is in an exhaust stroke;
• b) indicating means disposed so as to synchronize with a rotation of an engine crankshaft and formed with a large number of slits for detecting crankshaft angular positions and a small number of slits, the large number of slits being provided for indicating crankshaft angular positions and the small number of slits being provided for indicating predetermined stroke angular positions of respective cylinder pistons and wherein respective widths of said small number of slits with respect to the crankshaft angular position are at least different between those belonging to said groups;
• c) sensing means for detecting crankshaft angular positions in cooperation with the large number of slits of the indicating means and outputting a crank angle signal representing each of the crank angular positions and for detecting the predetermined stroke angular positions in cooperation with the small number of slits of the indicating means and outputting the predetermined stroke angular signals having different widths corresponding to those of the small number of slits;
• and
• d) discriminating means for identifying each cylinder group and outputting cylinder group identification signals on the basis of the crank angle signal and the predetermined stroke angular signals derived form said sensing means.

A crank angle detecting system for a multicylinder engine, comprising:

• a) a plurality of engine cylinders in which spark plugs are installed respectively, said cylinders being classified into a plurality of groups and each group being constituted by a pair of cylinders such that while the one of the cylinders is in an explosion stroke, the other is in an exhaust stroke;
• b) indicating means disposed so as to synchronize with a rotation of an engine crankshaft and formed with a large number of slits for detecting crankshaft angular positions and a small number of slits, the large number of slits being provided for indicating crankshaft angular positions and the small number of slits being provided for indicating predetermined stroke angular positions of respective cylinder pistons and wherein respective widths of said small number of slits with respect to the crankshaft angular position are different from each other to distinguish between piston strokes of at least the groups of cylinders;
• c) sensing means for detecting crankshaft angular positions in cooperation with the large number of slits of the indicating means and outputting a crank angle signal representing each of the crank angular positions and for detecting the predetermined stroke angular positions in cooperation with the small number of slits of the indicating means and outputting the predetermined stroke angular signals having different widths corresponding to those of the small number of slits;
• and
• d) discriminating means for identifying each cylinder group and outputting cylinder group identification signals on the basis of the crank angle signal and the predetermined stroke angular signals derived from said
• sensing means.