STEERING ANGLE DETECTION SENSOR

PCT No. PCT/DE95/00343 Sec. 371 Date Oct. 23, 1995 Sec. 102(e) Date Oct. 23, 1995 PCT Filed Mar. 14, 1995 PCT Pub. No. WO95/25660 PCT Pub. Date Sep. 28, 1995The apparatus for determination of absolute angular position of a steering wheel (w) rotatable through several revolutions includes a fine code disk(2) nonrotatably attached to the steering column (c) and provided with circumferentially distributed code elements (2',2'', 2''', . . . ) and circumferentially distributed code element sensors (5) for sensing the code elements (2'', 2'', 2''', . . . ) to generate fine signals which repeat after each revolution of the steering wheel and are indicative of a relative steering wheel angular position during each revolution; and a coarse code disk (7) provided with at least three code tracks (A,B,C, . . . ) and at least three code track sensors (8a, 8b, 8c , . . . ) for sensing respective code tracks (A,B,C, . . . ) to generate a progressive 3-bit coded signal indicative of the absolute steering wheel angular position over the several revolutions. The apparatus also includes a gear device (11,7') for rotatably driving the coarse code disk (7) with the fine code disk(2) having a predetermined gear reduction ratio and a microcontroller (13) for logically combining and evaluating the coarse and fine signals to determine the absolute steering wheel angular position, so that the absolute steering wheel angular position can be determined with a precision according to the finer angular tolerances of the device for generating the fine signals.