Patent GB-806136-A (GB)
Title: Maximum demand metering mechanism, more especially for electricity meters
IPC: G01R11/60
Filed: 1957-04-17
Abstract: 806,136. Maximum demand meters. LANDIS & GYR A.G. April 17, 1957 [April 21, 1956; Feb. 14, 1957], No. 12558/57. Class 106 (3). [Also in Group XXXII] In a maximum demand meter the rotatable shaft 13 is axially displaceable and can be decoupled from the meter drive and reset through a roller 24 pressing on a helical edge 20 cut round a cylinder 19 rigidly mounted on the shaft which is rotatable and axially displaceable. The meter drives the pointer 14 on the shaft 13 through bevel gears 11, 12 which are held in engagement by an arm 32, Fig. 2, mounted on a leaf spring 23 bearing against the end of the shaft 13. To reset the pointer 14 periodically, a relay 39 is de-energized through a time-controlled switch, allowing a spring 41 to turn the armature shaft 38 and lever 34, so that its arm 44 runs on to a cranked portion 45 of the arm 32, which releases the shaft 13 for axial displacement by the roller 24 bearing on the helical edge 20. As soon as the bevel gears 11, 12 disengage, the action of the roller 24 on the helical edge 20 causes rotation of the shaft 13, resetting being complete when the roller 24 encounters the edge 21 along a generatrix of the cylinder 19. The roller 24 is carried by a lever 33 rocking on the lever 34 in a fork 35, 36 against the tension of a spring 37. When the pointer 14 has been reset, the edge 21 reacts on the roller 24 as the arm 44 continues its turn causing the lever 33 to rock over to the prong 36 clear of the edge 19. By now the arm 44 has ridden over the crank 45 so that the arm 32 influenced by the spring 23 bears on the shaft 13 to re-engage the bevel gears 11, 12 so that the meter drives the pointer 14 again. When the relay 39 is reenergized after a short interval the armature shaft 38 swings the lever 34 back again, the lever 33 strikes an abutment 46 and snaps over to the prong 35 again and the lever 34 is arrested by an abutment 43. In a modification, Fig. 3, a cam 53 is driven one complete revolution by a synchronous motor 57 during each metering period, the roller 24 performing its decoupling and resetting action when a spring-urged follower 51 slips down the radial step 54 of the cam 53. When the pointer 14 has been reset, the roller 24 still bears axially on the cylinder 19 and rocks the lever 48 against the spring 69 causing a projection 67 of the lever 48 to release a latch 63, 64 which is freely mounted on the cam shaft 56 and so shaped that, influenced by a spring 65, it rocks the follower 51 back against the spring 52 and moves the roller 24 free from the cylinder 19 so that the spring 47 can urge the bevel gear 12 back into engagement with the bevel gear 11 for the meter to drive the pointer 14 again. During the continued rotation of the cam 53 a pin 66 thereon picks up the latch 63 turning it to wind the spring 65 until the projection 67 relocks the arm 64 of the latch. To avoid impact upon the movement of the follower 51 in either direction it is coupled to an inertia mass 75 through a sector 72 and pinion 73, the mass 75 being fixed on its shaft 74 or coupled by sliding friction. To reduce inertia in the transmission to the pointer 14 unwanted parts of the cylinder 19 are cut away and also appropriate parts of the bevel gear 12 to maintain rotary balance. When the pointer 14 moves further in a measuring period than in any previous period it engages a lateral arm 15a on a maximum demand pointer 15 and drives it to register a new maximum value, where it is frictionally retained when the pointer 14 is reset. If the arm 15a is set at an obtuse angle to the pointer 15 there will be a reaction tending to decouple the gears 11, 12 when the pointers engage, but it will only be effective to effect decoupling when a positive resetting movement is applied to the pointer 15.