GB268399A - Pistons - Google Patents

Abstract

268,399. Nelson, A. L. Oct. 7, 1925. Pistons.-A piston comprises a head 26, Fig. 1, with one or two extensions 16 carrying gudgeonpin bosses 13, and a skirt connected to the head or bosses by steel struts cast with the bosses and slipper portions of the skirts transversely to the gudgeon pin, and having tongues 18 and dovetails 18<1> to effect a firm connection and openings 19. The struts may be made single or of two or more stampings, tubes, or bars, and have a relatively low coefficient of expansion, may be made of material known under the Trade Mark " Invar " steel, and may be non-parallel. The piston head and skirt are cast in one and separated by machining, or one or both parts 20 of the skirt my be left intact with the head. The head and skirt are made of an aluminium alloy. The struts may be formed from part of the sides of a thin steel cylinder forming the skirt. The struts may be shaped as shown in Fig. 7 to bring the skirt towards the centre of the piston when heated. Transverse strengthening ridges may be provided on the bosses. The struts may be made in two pieces connected by the metal of the head and bosses. The construction may be modified for use with a single gudgeon-pin and forked connecting-rod. The gudgeon-pin bosses need not be integral with the head; the metal of the head may be cast about the struts independently of the bosses. The boss or bosses may be integral with the struts and the skirt, the lower parts of which would be left undivided when using metal of low thermal expansion. In lieu of casting, the component parts of the piston may be secured by welding, bolts, screws, &c. In the construction shown in Fig. 8, the head has webbed extensions which carry the bosses 27 which are connected to the skirt by webs 29, 32. The skirt has upward extensions 33 at opposite sides connected by dove-tailed struts 34 the upper parts of which are embedded in the bosses. In lieu of dovetails, the struts may be bent at their ends or otherwise formed to increase the anchorage, and may be made of separate single flat bars. The webs 29, 32 may be omitted, the skirt being entirely supported by the struts. The rim may be slit or slotted for expansion.