Abstract: The present disclosure discloses a fast and simple expansion bolt, including an expansion bolt main body, an expansion bolt locating line formed in an outer wall of a front end of the expansion bolt main body; a locating slot formed in the expansion bolt locating line; a rubber ring located on an outer wall of the expansion bolt main body; a tail seat and a locating ring located and mounted at a rear end of the expansion bolt main body; a pressing seat located in the tail seat; a locating column located on the pressing seat; a pressing handle movably arranged on the locating column; an adjustment pin arranged between the pressing handle and the locating column; and the expansion bolt main body is integrally formed with the expansion bolt locating line, the locating slot, the locating ring, and the tail seat through casting.

Abstract: A method for measuring speed of a permanent magnet synchronous motor includes: acquiring a number K of pulse signals received in a current measuring period and outputted by an incremental encoder; acquiring a first duration Sn-1 between a time point when a pulse is last received in a previous measuring period and a time point when the previous measuring period ends, and a second duration Sn between a time point when a pulse is last received in the current measuring period and a time point when the current measuring period ends; calculating a third duration T0, measured between the time point when the pulse is last received in the previous measuring period and the time point when the pulse is last received in the current measuring period, according to the length T of the current, measuring period, the first duration Sn-1 and the second duration Sn; and calculating a motor speed v according to formula: v = K K 0 × 1 T ? ? 0 .

Abstract: A method for measuring speed of a permanent magnet synchronous motor includes: acquiring a number K of pulse signals received in a current measuring period and outputted by an incremental encoder; acquiring a first duration Sn?1 between a time point when a pulse is last received in a previous measuring period and a time point when the previous measuring period ends, and a second duration Sn between a time point when a pulse is last received in the current measuring period and a time point when the current measuring period ends; calculating a third duration T0, measured between the time point when the pulse is last received in the previous measuring period and the time point when the pulse is last received in the current measuring period, according to the length T of the measuring period, the first duration Sn?1 and the second duration Sn; and calculating a motor speed v according to formula: v = K K 0 × 1 T ? ? 0 .