Patent GB-337552-A (GB)
Title: Improvements in and relating to electrically-driven mechanism for operating indicating, recording and other relay apparatus
IPC: G01L7/04
Filed: 1929-10-04
Abstract: 337,552. Cambridge Instrument Co., Ltd., and Stallon, W. J. Oct. 4, 1929. Relay devices.-In mechanical relay devices in which use is made of a continuously oscillating mechanism, the latter comprises a rocking member of two similar magnetic pieces whose centre of oscillation coincides with that of a fixed magnetic member, the mid-position of the rocking member also coinciding with the axis of the fixed member, and known hit and miss mechanism which depresses a member to close electric contacts controlling a circuit associated with one or more of the magnetic members. The oscillations of the electro magnets 1, 2, having cores 3, 4, about the pivot 6, which is also the centre of the fixed soft iron armature 5, is maintained in the usual manner by means of the trip pin 9 allowing the rod 7, hinged at 8 to the rocking magnet frame, to pass it at each oscillation until these become so small that the rod 7 can no longer pass, when the return swing of the rod 7 causes depression of the member 12, 13 to close contacts 15 carried on resilient arms 14, 16. This energizes the magnets 1, 2, again restoring the amplitude of the oscillations. These approximately uniformly timed depressions of the members 12, 13 are used to indicate by means of a pointer 29 any small movement, in this case, that of the end 27 of a Bowden tube 22. The pointer 29 is integral with a cam 33 and a rim 28, engaged by the pawls 31, 32 of two similar lever systems 32, 38, 35, 18, and 31, 39, 34, 17, pivoted at points 36, 40, 41. The cam 33 is engaged by the upper end of a lever 30 pivoted at the point 23 and under the action of a spring 37. A light member 21 is pivoted at its upper end 26 to a link 25 pivoted at 24 to the member 30 and lower down to the end 27 of the Bowden tube and carries at its lower end a pin member 20 projecting between the chopper bar 19 and the ends 44, 45 of the lever 18, 17, respectively. Operation. Normally with the pin 20 in the central position, as shown, the depressions of the member 12 do not operate either of the lever ends 44, 45 (the pin 20 may be arranged to just pass between the ends 44, 45 or the dimensions of the parts made such that no depression of the lever ends. takes place when the pin is in the central position). When the pressure alters in the Bowden tube the pivot 27 moves to the left, say, causing an amplified movement to the lift of the pin 20. The next depression of the chopper bar 12 then depresses the end 44 of the lever 18, the pawl 32 rotating the rim 28 and hence the pointer 29 in a clockwise direction. The cam 33 also rotates clockwise and its contour is such that it causes the end 26 to move to the left thus bringing the pin 20 back to its normal central position. If this restoring movement does not bring the pin 20 quite to its central position the next and if necessary following depressions of the bar 12 operate on the rim until equilibrium is again established. Each variation in the pressure in the Bowden tube thus results in an inching movement of the pointer 29 to a corresponding position. The apparatus may be used to move large pointers at a considerable distance by means of gearing, to indicate on dials at the top of a tower variations in temperature pressure or the like, or to control automatically, say, a valve in a pressure system. A record might also be made using the timed oscillations as a time base. The fixed armature and rocking electro magnets may be replaced by a fixed magnet and rocking pieces of soft iron and the pivot points 26, 27 may be reversed. By raising the pin 9 the mechanism may be made to give a power stroke every alternate swing.