Patent GB-692716-A (GB)
Title: An improved switch mechanism for electrical supervision or control equipment
IPC: G05B1/08
Filed: 1950-06-12
Abstract: 692,716. Mechanical relay and follow-up devices. JOENS, W., and JOENS, L., [trading as JOENS & CO., W. H. [Firm of],] June 12, 1950 [June 15, 1949]. No. 14557/50. Class 118 (ii). [Also in Group XXXVII] A switch mechanism for supervision or control equipment of the type having a drop stirrup 1 or like scanning or contact member to periodically ascertain by touch the position of an indicator pointer 8 comprises a multi-position mercury switch 9 mounted on a tipping axle 20 whose tilt is determined by periodic coupling with the said drop stirrup 1, and a rotating stop-segment 15 which retains the tipping axle 20 in position in between coupling occurrences. A cam 2 on a shaft 14, preferably driven by a small synchronous electric motor (not shown), periodically raises the drop stirrup 1 and with it a member 4 adjustable horizontally along the front part of the stirrup 1 simultaneously with the carrier 3 of an indicator 21 which is set to a nominal or desired value of the function being supervised or controlled. The member 4 carries a stepped plate 5 and when the cam 2 allows the stirrup 1 to drop it will fall an amount dependent upon whether the pointer 8 is to the left as in Fig. 1, to the right, under step 7, as in Fig. 3 (not shown), or intermediate, under step 6, as in Fig. 2. At the same time as the cam 2 allows the drop stirrup 1 to fall the stop-segment 15, which is also mounted on shaft 14, frees the tipping axle 20 by ceasing to obstruct two rollers 16 mounted on a switch-operating plate 11 rigid with the axle 20. Thus, under influence of a weight 13 and a peg 10 secured to the drop stirrup 1, the plate 11 tilts the switch 9 to one of three pbsitions dependent upon the amount the drop stirrup 1 and hence the peg 10 falls, as determined by the position of the pointer 8. On further rotation of shaft 14 the stop-segment 15 co-operates with the rollers 16 to maintain the switch in this position whilst the cam 2 lifts the drop stirrups 1 prior to a subsequent feeling operation. If the switch 9 is of the star-delta type wherein the extreme positions must not be reached without pausing in the intermediate (star) stage a small angle plate 17 (Fig. 2) is attached to the plate 11 between the rollers 16 so that the stop-segment 15 delays the axle in its intermediate position when the pointer 8 would otherwise allow it to pass directly to the other extreme. A counter-weight 19 is secured to the shaft 14 such that it acts as a storer of energy to assist the motor when lifting the drop stirrup 1. In a modification Fig. 4 (not shown) two switches are controlled by one pointer by mounting a second switch with its operating plate on a hollow shaft co-axial with the tipping axle of the first switch, the stop-segment being eccentrically mounted so as to push first one and then the other operating plate into engaging position with regard to respective pegs on the drop-stirrups. The pointer in this case has a central zero position and left and right carriers and stepped plates are provided, the measuring device being alternately connected for the respective functions by a commutator synchronised with the stop-segment.