Patent GB-828570-A (GB)
Title: Improvements in or relating to accelerometers
IPC: G01P15/135
Filed: 1957-06-11
Abstract: 828,570. Accelerometers. GIANNINI & CO. Inc., G. M. June 11, 1957 [June 22, 1956], No. 18436/57. Class 106 (3). [Also in Group XXXVII] An accelerometer comprises two inertial elements journalled on parallel axes with their centres of mass offset from the axes in opposite directions, and the elements are joined by an elongated transversely flexible coupling member connected at its ends to the elements on opposite sides of the plane of the axes, so as to prevent rotation of the elements in the same direction while allowing it in opposite directions, which latter rotation is opposed by the force due to resilient bending of the coupling member. The amount of rotation is thus proportional to the acceleration in a direction at right-angles to the axes. The rotary inertial elements 40, 50, Figs. 2, 3, 4 and 6 are mounted on shafts 46, 56 rotatable in bearings 44, 45, 54, 55. The shafts 46, 56 and spacing members 63 are of material having the same coefficient of expansion as the material of the frame 20. The bearings are adjustable with respect to end play by screws 36. The elements are surrounded by stationary damping sleeves 48, 58, in the small space between which the elements is a viscous liquid. The elements have diametral bores 65, 75, in which are threadedly received masses 66, 76 adjusted by screw-driver in slots 67, 77 so that the centres of mass of the elements 40, 50 are respectively below and above the plane of the axes as viewed in Fig. 3. The elements are joined by a coupling member 92, the ends of which are clamped between members 95, 97 and screwed to flat surfaces of the elements. Mounted on the shaft 46 and electrically insulated therefrom is an arm 116 to which is connected a flexible insulated wire, the arm 116 having a flexible support 123 carrying a contact rod or wire 122, which constitutes one contact of an electric switch. The other contact 124 is mounted on an insulating ring on a pin 140 mounted eccentrically on a hub 130 rotatable to adjust the acceleration at which the switch is actuated. Pivoted on a sleeve 172 is a carrierplate 170 carrying pins 175, 176 by which it is moved by the pin 140 as the hub 130 is adjusted. At the other end, the plate carries adjustable abutments 164, 165 which engage a stop-pin 160 on the element 40 to limit the range of movement of the latter and to vary the position of the range according to the setting of the switch. Fixed abutments 184, 185 may be used to limit the range independently of the switch. Similar abutments 204 for engaging a stop-pin 190 carried on a bracket 192 secured to the element 50 are carried on the plate 170, and corresponding fixed abutments are mounted in the frame top plate 22. Another form of stop mechanism, Fig. 10, comprises a stop member 150 mounted by a clamp screw 151 on the arm 116 and having a vertical face 152 which engages a coaxial extension 155 of the pin 140 after the wire 122 has engaged the contact 124 and become slightly deflected. Actuation of the switch produces a signal to indicate the particlar acceleration for which the hub 130 is set.