Patent GB-380116-A (GB)
Title: Improvements in and relating to prepayment meters
IPC: G07F15/08
Filed: 1931-06-09
Abstract: 380,116. Prepayment mechanism for electricity meters. FAWSSETT, E., Overdene, Riding Mill, PARNALL, E. J., Como, Lilburn Gardens, South Gosforth, both in Northumberland. June 9, 1931, No. 16792. [Class 27.] Price - changing mechanism. - In order to vary automatically in a prepayment meter the quantity of commodity supplied for a coin when the rate of consumption reaches a predetermined value, and as applied to an electricity meter, two parallel shafts 31, 34, Fig. 1, are permanently geared through wheels 30, 35, with the meter-driven commodity shaft and the commodity side of the usual prepayment differential respectively. The wheel 30, slidably mounted on the shaft 31, is in constant mesh with a wheel 32 carried by a sleeve 33 loose on the shaft 34 to which the pinion 35 is fixed. The wheel 32 has a pawl 36 engaging in ratchet wheel 37 fixed to the shaft 34, on which is also secured a wheel 38 meshing with a wheel 39 loose on the shaft 31 and carrying a clutch member 41. The wheel 30 carries the other clutch member 42 which is normally in engagement with the member 41 so that the commodity shaft drives the differential through the clutch 42, 41 and the gear train 39, 38, the pawl '36 riding over the teeth of the ratchet wheel 37. When the rate of consumption reaches a predetermined value, a bimetallic element 44 of a bimetallic device 45 expands under the action of a heating element 46 and, by a stirrup 43, moves the wheel 30 on the shaft 31 to separate the clutch members, so that the differential is driven through the wheels 30, 32, the pawl and ratchet 36, 37, and the wheel 35. The velocity ratios of the different drives are such that commodity is supplied at a lower price when the rate of consumption is high. Instead of by a bimetallic thermal device, the clutch elements may be operated from an electromagnet the winding of which is traversed by the load current or a current proportional thereto. In a modification, Fig. 3, the drive from the commodity shaft normally is through a shaft 60, planet wheels 75, 76 secured to the shaft, and a loose sun-wheel 71 carrying a wheel 72 meshing with a wheel 73 fixed to a parallel shaft 64 which has a wheel 65 geared to the commodity side of the differential. The other loose sun-wheel 69 is prevented from rotation by the engagement with an attached wheel 68 of an abutment 77 connected to the armature 78 of an electromagnet 80 and controlled by a spring 81. When the rate of consumption is above a certain value, the drive from the shaft 60 takes place through a wheel 61, and a wheel 62 loose on the shaft 64 but driving the shaft through a pawl and ratchet 66, 67. In a further form, Fig. 4, a shaft 100 geared to the commodity shaft and a parallel shaft 101 geared to the differential carry each an epicyclic gear 104, 111 the planet wheels 105, 112 of which are fixed to their respective shafts while the sun wheels are loose thereon, corresponding sun wheels being in constant mesh through gear trains 107, 108 and 102, 115. Wheels 109, 114 rigid with the sun wheels on the shaft 101 are engaged alternatively by stops 118, 119 on a lever 116 biased by a spring 120 and controlled by an electromagnet 122 subject to the load current. Normally the stop 118 engages the wheel 109 to prevent rotation of its connected sun wheels and the drive from the shaft 100 occurs through the train 102, 115 and planet wheel 112 to the shaft 100. When the rate of current consumption is above a certain value, the stop 118 is disengaged and the stop 119 engaged with their respective wheels, so that the drive occurs through the train 107, 108. A preferred construction and its arrangement in a meter is illustrated in Figs. 5 and 6 (not shown). The constant mesh gearing between the parallel shafts is similar to that shown in Fig. 1, the clutch being controlled by an electromagnet, the armature of which is pivoted so as to rotate about an axis parallel to the poles of the magnet.