GB647005A - Improvements in and relating to vibration transmitting systems - Google Patents

Abstract

647,005. Transmission systems for mechanical vibrations. SPROULE, D. O., and HUGHES & SON, Ltd., H. Dec. 24, 1947, No. 34287. [Class 118 (ii)] [Also in Group XL (b)] In a vibration transmitting system comprising a metallic strip for transmitting mechanical vibrations, the direction of vibration being normal to the surface of the strip, the strip is supported by threads, e.g. nylon, inclined at an acute angle to the direction of vibration to minimise absorption of the vibratory energy by the supports. By suitably dimensioning the strips the velocity of propagation may be made dependent on the frequency, i.e. the system is dispersive, and the system may then be used for compressing the duration of a wave pulse in which the carrier frequency varies during the pulse as described in Specification 604,429. The strip may be straight/or spiral-shaped but in the embodiments described space is conserved by winding it into a helix H which is supported from an outer cage of bars B parallel to the axis of the helix and attached to annular members D, the support comprising nylon threads F looped round each turn of the helix and round pegs P mounted on the bars, the single continuous thread associated with any one bar forming a mesh in a plane perpendicular to the surface of the strip and the elements of the mesh being inclined at an acute angle to the direction of vibration V, i.e. the normal to the surface of the strip. In order to prevent axial movement of the helix, adhesive is applied at the points of contact of the thread and strip to prevent relative movement. Alternative arrangements of the supporting threads are illustrated in Figs. 4 and 7 (not shown), the embodiment shown in Fig. 4 providing greater axial stability. In order to prevent reflection of the transmitted energy at the points of support, each supporting mesh may be duplicated, the spacing between the individual meshes of each pair being #/4, Figs. 5 and 6 (not shown). In Fig. 8 (not shown) a plurality of coaxial helices are connected in series, the planes of the supporting meshes being equally spaced. In any of the embodiments the vibrations may be initiated and detected by electromagnetic transducers El, E2 coupled to opposite ends of the strip. If required, the supporting threads may run inwardly to frame members within the helix.