Patent GB-190505369-A (GB)
Title: Improvements in Electric Motor Meters and other Measuring Instruments more especially Designed for Reducing the Effects of Friction in such Instruments.
Inventor: DAVIS ALBERT GOULD
Filed: 1905-03-14
Granted: 1905-08-24
Abstract: 5369. Davis, A. G., and Haskins, C. D. March 15, 1904, [date applied for under Patents Act, 1901]. Registering observations by instruments; counting- apparatus.-In any measuring instrument having a part 7 which should revolve with as little friction as possible, this part is carried by a flexible suspension 13 from the vertical shaft 15 of a motor 19, which runs at the same average speed as the revolving part 7. In the arrangement shown in Fig. 2, the motor 19 tends to run at a higher speed than that revolving part 7 when an electric circuit is completed through two contacts 33, 34 on the shaft 15 and the revolving part 7 respectively, the contact being thus immediately broken again. The motor thus runs at the same average speed as the revolving part 7, their relative motion being limited by the contacts. Revolutions may be counted by an ordinary counting-apparatus geared to the shaft 15. The invention is shown as applied to an electric meter, the motor 19 being a series electric motor. The revolving armature 7 of the meter is carried by a tubular spindle 6, made in two parts connected by a screw coupling 12, preferably above the centre of gravity of the whole of the revolving portion of the meter ; the suspension 13 is a fibre or wire secured to a plug fitting in the coupling 12 and passing through the tubular spindle 6. The lower end of the meter spindle 6 may be guided by a steel pin 17 in a perforated jewel ; or the upper end of the spindle may nearly fit the suspension 13. The commutator 10 of the meter is shown carried by the meter spindle 6, but it may be carried by the motor shaft 15 and connected by flexible conductors to the armature 7, so that the meter spindle is relieved of the friction of the brushes. Current is supplied to the contacts 33, 34 by brushes touching collars which carry these contacts, the motor and contacts being thus placed in series with a resistance between the supply mains. The armature of the motor is enclosed in a conductive casing 24 which serves as a magnetic brake. The motor shaft may run on a ball bearing. Instead of electric contact being made between the parts 33, 34, the upper of these may be free to turn on the motor shaft 15, and thus to operate a spring-pressed switch carried by a disk on this shaft, with platinum and carbon contacts. Or otherwise, the motor shaft 15 may carry two insulated cam disks, connected in the circuit, the meter spindle 6 being provided with a fork carrying two brushes to touch the projecting parts of the cams and thus to contact them electrically together. In another arrangement, instead of an independent motor 19 and contacts being used, the motor has a straight magnetic bar revolving in a stationary multipolar open-coil armature, each winding of which is separately connected to one end to a segment of a stationary commutator, over which a single brush is carried by the meter spindle 6, so that the motor runs synchronously with the meter.