Patent GB-586722-A (GB)
Title: Remote measuring device
IPC: G08B21/00
Filed: 1944-04-21
Abstract: 586,722. Automatic control. WEY, R. J. April 21, 1944, No. 7450. [Class 38 (iv)] [Also in Groups XXIX and XXXVIII] Speed.-In a remote measuring device comprising two members, one of which is intermittently rotated in accordance with impulses produced by a transmitter and the other of which is capable of steady rotation by a variable speed source of power and means for detecting any difference in the mean rates of rotation of the two members and adjusting the speed of the source of power to make the speed of the second member equal to that of the first member, a speed indicating mechanism is rotatively coupled to and affected substantially only by the rotation of the source of power. The invention is applicable to the measurement of any quantity which can cause variations in the rate at which impulses are sent out by the transmitter. As shown in Fig. 1, an electric motor A drives the input shaft C of a differential gear through reduction gearing B whilst a second input shaft D is driven contra-wise, and in a step-by-step manner by a ratchet-wheel F operating through reduction gearing E,. The ratchet-wheel F is operated by a pawl G actuated by an electromagnet I energized by a switch H closed periodically by a rotating shaft, e.g. the shaft of a flow-meter. The cage J of the differential gear operates through gearing M, N to control a rheostat P in the motor circuit so as to adjust the speed of the motor A in such manner that the mean speeds of the shafts C, D are equal. As shown, the motor A is coupled to a speed measuring device Q which may be an eddy current drag tachometer. The cage J operates the gear M through a lost-motion device such as the pin and slot K, L so that the oscillating motion is not conveyed to the gear M. The lost-motion device may be replaced by a spring and a damped inertia device arranged between the gear N and the rheostat arm O. In another modification, Fig. 3, the ratchet-wheel and pawl is replaced by an escapement device G, F. In this form, both parts of the motor speed regulator are rotatable. The winding M of the regulator is carried by, and rotates with, the shaft C driven as before by the motor A and one of its ends is connectod in the motor circuit by the slip-ring Q and brush V, a similar slipring P with a brush U being connected through a flexible connection 0 to the contact arm N. The latter can rotate relatively to the shaft C and will do so when the lost-motion between the. pin R and slot S is taken up. This will happen when the mean speed of the shaft D differs from that of the shaft C. The shaft D is operated intermittently by pawls G acting on the escapement wheel F, the torque for which is provided by a spring T on the shaft C. A damping vane V<1> is geared to the shaft D. According to the Provisional Specification, a step-by-step electric motor may drive one of the input. shafts according to the impulses originating at the transmitter. Also the speed of the receiver motor may be regulated by an adjustable centrifugal governor, or a variablespeed gear of the friction wheel and disc or other suitable type may be arranged in the drive to the differential gear. Specifications 244,096, [Class 40 (i)], and 382,526, [Group XXXVIII], are referred to.