Patent GB-502820-A (GB)
Title: Methods of and means for the multiplication of two or more factors or quantities
IPC: G01F15/02
Filed: 1937-09-24
Abstract: 502,820. Fluid-pressure servomotor-control systems. ASKANIA-WERKE AKT.-GES. VORM. CENTRALWERKSTATT DESSAU UND C. BAMBERG-FRIEDENAU. Sept. 24, 1937, No. 25992. Convention date, Oct. 29, 1936. [Class 135] [Also in Group XIX] The product of two or more factors is computed with the aid of a transmission system comprising two substantially parallel members which are pivoted about spaced axes and are in motion or force transmitting relationship with an intermediate member displaceable relatively to said members to vary the transmission ratio therebetween, the intermediate member being displaced proportionately to the algebraic sum of the logarithms of the factors and the transmission ratio being directly proportional to the product of the factors. In the simple form shown in Fig. 1, the product of two or three factors is computed by a force transmitting system comprising parallel levers 10, 13 ,pivoted at 11, 14, respectively, and connected by a slidable fulcrum 16. If colinear forces A, B, having a ratio R, be applied to the upper and lower lever, respectively, at a distance c from each pivot, and the distance of the fulcrum from the line of the forces by y, then the condition for equilibrium may be proved to be such that y=c.1-R/1+R. For values of R ranging between 0À5 and 2À0, this equation approximates closely to y=log R x a constant. Hence, if two factors p, q be set up by adjustment of slides 20, 21 relatively to logarithmic scales 24, 25, and these settings summed by an equiarmed lever 18 and transmitted to the fulcrum 16, then, if the dimensions of the apparatus are properly chosen.-log p + log q=log R. Whence A/B=p.q, and in the special case in B which B is unity, A=p.q. By increasing the number of setting slides and connecting levers the product of any number of factors may be obtained, the direction of setting of each factor determining whether it shall act as a multiplier or divisor. The algebraic sum of the settings may be read from a scale 27. Application to gas meters. As shown in Fig. 3, the invention is applied to an integrating device connected to a gas meter to compensate for changes in pressure and temperature. The gas in a conduit 30 passes through a volumetric meter 31 which drives a disc 33 proportionately to the rate of flow. The disc is connected by a friction wheel 34 to a disc 37 mounted on a parallel axis and adapted to actuate a counter 39 giving true readings. The friction wheel is adjustable radially of both discs under the combined control of a pressure-responsive device 46 and a temperature responsive device 48, 49, each acting through a logarithmic cam 44, 45. The theory of the device is the same as that already expounded, the pressure and temperature being the factors p, q., the revolutions of the meter disc 33 being the factor B, and the revolutions of the counter disc 37 giving the resultant A. Application to gas flow-regulators. As shown in Fig. 4, the invention is applied to a device for regularing a constant-weight flow of gas in a conduit 51. The flow is regulated by a valve 63 connected to a servomotor piston 61 controlled by a jet-pipe 55 pivoted at 56 and acted upon by a diaphragm 54 responsive to the differential pressure at a constriction 52 in the conduit. An adjustable fulcrum connects the jet-pipe to a lever 64 urged to the right by a spring 66. The fulcrmn is adjusted manually by a wheel 73, connected to a setting-indicator comprising an index 77 graduated logarithmically in terms of barometric pressure and movable over a. scale 7S carrying a number of logarithmic curves representing temperature. In this embodiment, the factors p, q are set by the indicator 77, 78 in accordance with the pressure and temperature, the pressure on the diaphragm 54 gives the factor B in accordance with the rate of flow, while the resultant A is given by the spring 66 which determines the position of the jet-pipe 55 and hence of the' valve 63. A modified form of setting-indicator is shown in Fig. 6, for use when the apparatus is applied to combustion regulators. A rotatable scale 80 is graduated logarithmically in terms of temperature. A double pointer 81 is adjusted relatively to the scale 80 and fixed thereto, its long index moving over a stationary scale 78<1> graduated logarithmically in terms of the ratio of air to fuel.