GB286737A - Improvements relating to electric speed indicators - Google Patents

Abstract

286,737. Mombur, G. March 10, 1927, [Convention date]. Impulse speed indicators. - In a speedometer an electromagnetic system operating at a frequency depending on the speed to be measured is utilized to impart movement to an oscillating control member or balance wheel co-operating with a member to serve as a fly wheel to produce a constant speed, the movement of the control member being transmitted to an indicating pointer. As shown in Fig. 1 a distributer 11, operated at a speed proportional to that to be measured, is in circuit with a battery and electromagnet 10 the armature 8 of which is connected by a link 7 to an eccentric pin 6 on a spring-controlled toothed sector 5 gearing with a pinion 4 loose on a shaft 1. The pinion 4 forms part of the control member which comprises a toothed wheel 2 carrying a pin 3 and a toothed disc 25 with a notch 26. Each current impulse through the electromagnet oscillates the control wheel 2 which, on its return movement through a pawl member 12 carried by a fly wheel 13, 16, is operative to rotate the wheel, the motion of which is regulated by an oscillator 14 having pins engaging semi-circular indents on the periphery of the wheel. Co-operating with the disc 25 is a spring-controlled pawl 27 pivotally mounted on a spring-controlled pawl member 30 that engages a measuring wheel 32. The wheel is under the control of a spring 33, Figs. 2 and 4, and is connected through a slot 35 and arm 36 with an indicating pointer 37. The measuring wheel is also provided with a projecting pin 34 in the path of movement of the control pin 3. On the initial movement of the control wheel the pawl 27 is moved from the position shown in Fig. 4 to that of Fig. 5 during which time the pawl 30 is withdrawn to free the wheel 32 to permit the pin 34 to follow the pin 3 and is then operative to hold the wheel 32. The slot 35 provides a slight play for the wheel 32 to prevent movement of the pointer while the wheel is freed. At the end of the forward limit of the control pin 3 a lever 17 is operated to drive a counting-mechanism for registering distance and the notch 26 in the disc 25 at the same time permits return of the pawl 27 to its normal position ready for the next impulse. In a modification the speed measurement is made while the current is flowing by means of an electromagnet the armature of which drives a control wheel at uniform speed. In another form the armature is replaced by a vibrator which may be intermittent or continuous depending upon whether or not it is arranged in the circuit of the distributor. In still another form the control member may be actuated through a repeater device regulating the speed of the balance wheel.