GB1365054A - Methods of and devices for ascertaining the tension of belts - Google Patents

Abstract

1365054 Determining tension of belts ROBERT BOSCH GmbH 11 Jan 1973 [12 Jan 1972] 1446/73 Heading G1N In a method for determining whether the tension of a belt, which transmits rotary movement from a drive shaft to a driven shaft, is sufficient, a first load is applied to the driven shaft and a first signal representing the slip of the belt is derived from tachometer signals representing the speeds of the drive and driven shafts, a second load is applied to the driven shaft and a second signal is derived from the tachometer signals, the first and second signals are compared and the resluts are indicated. The belt may be that between the crank-shaft and generator shaft of an I.C. engine, and the load may be varied by driving the engine at different speeds, or the engine may be driven at a constant speed and a resistance used as a load for the generator. As shown in Fig. 2, a tachometer 17 provides a signal representing the speed of the generator shaft and a tachometer 18 provides a signal representing the speed of the crank-shaft through the ignition system 19, 20, 21. The outputs of the tachometers are applied to a dividing circuit 22. When the generator is under the first load, a switch 23 is closed and the signal from dividing circuit 22 is stored in a capacitor 24. A switch 26 and capacitor 25 act in the same manner for the second load. The switches may be manual or automatic. A comparator 27 compares the signals stored in capacitors 24, 25 and an indicator 28, which may have a scale calibrated in terms of tension, indicates the resulting difference. In an alternative embodiment, Fig. 3 (not shown) the outputs of the tachometers are applied to a subtracting circuit, and the output of the subtracting circuit is applied to a dividing circuit where it is divided by the output of tachometer 18. The output of the dividing circuit is then connected to the switches 23, 26 and capacitors 24, 25 as shown in Fig. 2.