MONITORING APPARATUS FOR MONITORING AMOUNT OF STATE CAUSED BY TORSIONAL VIBRATION OF DRIVING APPARATUS

PURPOSE: To enable the continuous monitoring of the quantity of state by the torsional vibration of a drive unit with reliability by comparing the actual value with the stress limit value of torsion alternating stress and the difference of measurement values between the inner part and the outer part of an attenuator with the stroke limit value of a spring. CONSTITUTION: A torsional vibration attenuator 1 is comprised of an inner part 2 held on a crank axis W with a flange so as not to turn relatively and an outer part 3 supported so as to be twistable relatively to the inner part 2. A spring element 4 is provided between them, and the oil in a chamber 5 formed between the parts 2 and 3 and the element 4 achieves preferable attenuation by a drain in the case of the relative torsion of the parts 2 and 3 and the bending of the element 4 involved in this. A calculator 7 reads an absolute torsion value obtained by each of sensors 8 and 9 attached to the parts 2 and 3 respectively, obtains the torsion alternating stress of the axis W from the torsion value of the sensor 8 and compares it with the limit value. The calculator simultaneously obtains the difference of the values of the parts 2 and 3, which is also the scale of the twist of the element 4, and compares it with the limit value. In either of the cases, when the limit value is exceeded, a warning is given.