US2069594A - Engine piston - Google Patents

Description

Feb. 2, 1937. R. SCHNEIDER ENGINE PISTON Filed July 15, 195o 1 f, lllllflllx u nlmlll 9 Patented Feb.' 2, 1937 UNITED STATES PATENT oFF'Ic-E 2,069,594 ENGINE PIs'roN Rudolph schneider', st. Louis, Mo., asngnor to Busch-Sulzer BrosfDiesel Engine Company, St. Louis, Mo., a corporation of Missouri Application July 15, 1930, Serial No. 468,079

2 Claims.

In the accompanying drawing, Fig. 1 is an axial section, through the piston pin axis, of a trunk piston incorporating one form oi the invention.

Fig. 2 Ia similar section on line II-II f Fig. 3. Fig. 3 is a crosssection of the piston at the piston pin axis. I

'I'he piston head, marked I in Figs. 1 and 2, is made hollow and its interior chamber forms part of the circuit of a cooling liquid system, presently referred to; its exterior cylindrical wall carries the usual piston rings. The piston trunk or skirt 2 is separately made, in the present case, and rigidly secured to the piston head but 'it could be made in one piece with the head i! desired, and vas will later appear. .The connecting rod 3 is connected to the piston by means of an intermediate'structure, herein f or convenience termed a 4false trunk, and indicated in its several parts by the reference numerals 4, I, 6, 1, l, I4 and I5. This structure is shaped to it the piston proper at or near its head part and also at an intermediate point of the piston trunk and has a continuous circular contact therewith at each point, viz. at its top shoulder 5', where, in the present case, it clamps thetop ilangeoi the-trunk 2' against the bottom flange of the piston head I. and atvits upper cylindricalcorner 6, where it bears on the corresponding cylindrical surface at the top part of the'trunk 2, and iinally, at its lower cylindrical surface 1 where it bears against bolts 9 in -diametrlcally `opposite positions,n as.

shown In Fig. a, and by two threaded nippIes In, also diametrically located, which serve both as bolts and as ducts for conducting the cooling liquid to and from the piston head chamber.' Both the b olts 9 and the nipples I0 are threaded into 'the base of the piston head and extend irom'top pressure 'on the piston pin, which of course is 55 to bottom of the false trunk, their heads or nuts thus being low downand near to the open end of the trunk and hence easily accessible. The lower ends of the nipples I0 will be understood to be designed for appropriate connection with 4the 5 fixed parts of the piston cooling system.

The. piston pin is held in a bearingbox 4 iny the false trunk, which in the present case is a crossbore' through the structure of the false trunk,

lined with a bearing bushing I2. -The pin rotates l0 relatively to the cross bore and bushinginstead of being fast to the piston according to conventional engine design. The connecting red is connected to the pin by means of its head ange 3a,

which is rbated into a. recess cut in the lower side l5 of the piston pin, midway of its ends, and bolted thereto by the four bolts I3. 'I'he bushing I2 and the lower part of the integral false trunk structure are cutaway to accommodate this connection. Except for' the recess which accommodates 20 the diameter of the piston and helclagainstend- A 25 wise displacement in the cross bore by the connecting rod. The recessed face by which it is attached to the connecting rod is within the cylindrical contour of the pin so that the pin may be readily produced by simple manufacturing proc-30 endwise into-the esses and can also be inserted cross-bore.

As will be observed from the drawing, the false trunk structure is of skeletonized internal construction being made strong by its internal strut 35 webs I4, which converge downwardly from the annular shoulder 5 to the bearing box 4 and by the tubularcasings I 5 through which the' bolt members 9 and I0 are passed. f

f In the assembly oi the pms, the bushing I2, 40

when one isemployed, is introduced into' the box 4 of the false trunk and desirably keyed to it by the keys I6 and the keys are locked by set screws I1, thus to guard vagainst any movement of the bushing, rotary or endwise, in the piston structure. The piston pin II is next introduced, being inserted endwise into the bushing andthe connecting rod is then adjusted to the piston pin re- 1cess and bolted therein. vThe false 'trunk with these parts connected toit then receives the real 5 trunk 2 over it and the piston head I on top of that and the bolt members 9 and IB-are then inserted and set up, thus completing the operation. By the construction described the downward the maximum in an internal combustion engine, is taken over the whole top surface of the piston pin, from end to end thereof, being thus of the maximum possible area. Such pressure is symmetrically transmitted to the pin from the annular shoulder 5 through the internal strut mem-I bers already referred to. 'I'he area of bearing contact of the cross bore or bushing upon the underside of thev piston pin is reduced by the cut-out for the connecting rod connection, but this is notl objectionable as the maximum pressure on this surface is only that due to the inertia of the piston at topldead center and therefore small as compared to 'the combustion pressure on the top. It is adequately taken by the end pory tions of the pin at either side of the connecting rod joint which portions are symmetrical and of equal lengtn and area and of` equal bearing contact on the box or on the bearing bushing therein, so that there is no tendency for the bearing to wear more at one end than at the other which would skew the pin in the piston and set up lateral strains in the connecting rod, such strains being particularly objectionable in combustion engines because of the sudden pressures to which such apparatus is subjected. Moreover, the piston pin being retained against displacement by virtue of its connection to the connecting rod, as above stated, is also free to adjust itself longitudinally within the limits of the cut-out portion of the cross bore, which is an important feature in that-it not only makes Afor symmetry of pressure transmission and equality of piston pin wear but in thatiit also relieves the other parts or any straineincident to the change of length of the piston pin from'thermal causes and also of such distortion as occurs or is likely'to occur in other .types of pistons from such causes or the operation of pressing the pin into the piston walls.

'I'he piston pin bearing is lubricated by oil grooves as usual, supplied through the connecting rod bore I8 and the oil used for this purpose is effectively kept out of the combustion space,

since it is confined within the trunk 2.`

I claim:

1. A combustion enginepiston comprising a head, .a separately formed trunk, a false trunk, and bolt means for attaching fthe trunk to the head and the false trunk to both of said parts,

said false trunk having an annular bearing near its lower end upon the inner surface of the real j trunk and formed with a bearing box and having a. cylindrical piston-pin in said box, said box providing a substantially continuous bearing surface for the piston-pin against its top side and a

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