US1877106A - Piston and ring assembly - Google Patents

Description

P 1932 J. WILLIAMS I PISTON AND RING ASSEMBLY Filed June 29, 1929 lvwcutoa (lildian T/Vzlllm' my Patented Sept. 13, 1932 ,TIQ'DSON WILLIAMS, OI PHILADELPHIA, PENNSYLVANIA PISTON AND RING" ASSEMBLY Application med June 2a, 1929. Serial no. 874,788.

This invention relates to an improved piston and ring assembly particularly designed for use in internal combustion engines, although the invention is equally applicable'for more or less general use.

The invention seeks, among other objects, to provide a piston wherein, at one side, the piston will have straight metal to metal contact throughout its length with the cylinder wall to thus be rigidly supported and guided in its movement y t e cylinder.

A further object of the invention is to provide an arrangement wherein the piston will be firmly held at its straight side against the cylinder wall so that possible rocking of the piston and consequent piston slap will 'be effectually prevented.

Another object of the invention is to pro vide an arrangement wherein the force holdin the straight side of the piston against the cy inder wall will be increased with increase in the temperature of the assembly, so that the straight line movement of the piston will be maintained under all working conditions thereof.

And the invention seeks, as a still further object to provide an assembly wherein, as compared with the ordinary plston and ring assembly, mechanical friction will be reduced.

Other objects of the invention not specificall set forth in the fore oin will appear in t e course of the following escription.

In the drawing:

Figure 1 is a vertical sectional view showing my improved piston and ring assembly in position in a conventional engine cylinder,

Figure 2 is a side elevation showing in dotted lines, the straight side of the piston,

Fi re 3 is a transverse sectional view on the line 3-3 of Figure2, looking in the direction indicated by the arrows,

Figure 4 is a detail plan view showing a typical tensioning element employed in connection with the piston rings,

Figure 5 is an elevation of the tensioning element shown in Figure 4,

Figure 6 is an elevation showing a slightly different embodiment of theinvention, Figure 7 is a sectional view of the tensioning element employed in the embodiment shown in Figure 6 and Figure 8 1s a plan view of the tensioning element of Figure 7.

Referring now more particularly to Figures 1 to 5 inclusive of the drawin the piston of the present-invention inclu es a head 10 from which depends a resilient skirt 11 preferably split at one side as indicated at 12. x A conventional wrist pin is indicated at 13 and the wrist pin bosses of the piston at 14. For convenience I have shown the piston 11; position in a conventional engine cylinder As most clearly shown in Figures 1 and 2 of the drawing, the piston is formed at one side with an external longitudinally straight face 16, best seen in dotted lines. This face extends throughout the length of the piston. and is of the same radius as the internal radius of the cylinder so that said face thus fits throughout its entire area flat against the cylinder wall. For convenience, the face 16 will be termed the straight side of the piston. At the upper end portion of the iston, the remainder of the outer circum erence thereof, or that portion of the piston not occu ied by the straight side 16, is eccentric, ing of considerably less radius than the internal radius of the cylinder. However, this eccentricity of the upper end portion of the piston gradually dlsa'ppears as the lower end portion of the piston is approached' and for an area, indicated at near the lower end portion of the piston, the skirt is concentric to the axis of the piston and to the cylinder, which causes a gradual widening of the face 16 towards its lower end. This concentric area near the lower end of the piston is substantially cylinder size and coacts with the cylinder wall for firmly centering and supporting the piston at its lower end. In the present instance, I have shownthe straight face 16 of the piston in a plane at right angles to the plane of the wrist pin 13 at the high pressure side-of the iston. However, said face. may be located in a plane with the wrist pin or at any point about the circumference ofthe piston found most desirable. Beginning at the upper hmit of the concentric area at the lower end of the piston, the piston is, with the exception of the straight face 16, externally tapered gradually to its upper end, the upper end being under cylinder size.

Formed in the head of the piston and in the lower end portion of the skirt is a plurality of concentric'ring grooves 17 having straight top walls and beveled bottom walls. These grooves are. concentric to the axis of the piston and removably fitting therein are resilient rings 18 having flat upper faces and beveled lower faces fitting the beveled bottom walls ofsaid grooves. Overlying the rings are frusto-conical tensioning elements 19, a typical one of which is shown in detail in Figures 4 and 5 of the drawing. These tensioning elements are resilient and are each split at one side. Furthermore, as will be observed, each of said tensioning elements is gradually widened from its ends towards a point diametrically opposite. Each of said elements is eccentric and may be said to have a wide side and a narrow side, the wide side being diametrically opposite the ends and the narrow side being adjacent the ends. As brought out in Figure 3, the wide sides of the elements 19 are arranged at the eccentric side of the piston so that the ends of said elements are thus disposed medially of the face 16, and fixed in the ring grooves are pins 20 which extend bet-ween the ends of said elements for locking them against creeping movement. The elements 19 are at all times compressed in the ring grooves between the upper faces of the rings and the top walls of said grooves so that said elements are constantly under tension tending to force the rings downwardly against the bottom walls of the grooves. The beveled faces of the rings and the ring grooves are thus caused to coact for expanding the rings radially in all directions into engagement with the cylinder wall. The rings will thus provide an effective seal between the piston and the cylinder.

Attention is now directed to the fact that the wide sides of the tensioning elements 19 will exert a greater downward tension on the rings 18 at the eccentric side of the piston than at the straight side thereof. Consequently, a greater radial force will be exerted on the rings at the eccentric side of the piston than at the straight side, with the result that the portions of the rings at the eccentric side of the piston will be caused to coact with the cylinder for forcing the straight side of the piston against the cylinder wall and yieldably holding the face 16 constantly in contact with said wall. Thus, since the face 16 is of the same radius as the internal radius of the cylinder, said face will coact with the cylinder wall for solidly guiding the piston in its reciprocating movement.

When the piston is heated, under working conditions, and the piston expands, the whole effect of the expansion will, since the straight side of the piston rests flat throughout its length a' ainst the cylinder wall, be communicated to %he diametrically opposite side of the piston. Thus, the expansion of the piston will tend to crowd the piston rings into the ring grooves at the wide sides of the tensioning elements 19 so as to increase the flattening of the wide portions of said elements in the grooves. The tension on the wide sides of the tensioning elements will thus be increased so that, as will be appreciated in view of the foregoing description, the pressure exerted by the wide sides of the elements and tending to force the straight side of the piston into engagement with the cylinder wall, will be correspondingly increased automatically. Consequently, rocking movement of the piston with resultant piston slap will be effectively prevented. At the same time, mechanical friction on the cylinder will, as compared with an ordinary piston and ring assembly, be reduced due to the fact that the area of the piston, in the present invention, in contact with the cylinder, is increased while radial pressure of the rings against the cylinder wall is decreased. By beveling the bottom walls of the ring grooves and correspondingly beveling the rings, the rings are solidly supported by the piston and less radial pressure on the rings is required to maintain a seal with the cylinder wall.

In Figures 6, 7 and 8 of the drawing, I have illustrated a slightly different embodinent of the invention wherein the piston is indicated at 21 and a conventional cylinder at 22. The piston is in all respects likethe piston previously described, except that the piston 21 is provided in the head thereof with ring grooves 23 which are tapered in width circumferentially of the piston. The narrow sides of these grooves are located at the straight side of the piston and the wide sides of the grooves at the diametrically opposite side of the piston. The grooves are provided with beveled bottom walls as in the prior embodiment of the invention and these bottom walls lie in planes at right angles to the straightface of the piston while the top walls lie in planes at right angles to the eccentric tapered side of the piston. Fitting in the ring grooves are rings 24 like the rings 18, and overlying said rings are frust-o-conical tensioning elements 25, one of which is shown in detail in Figures 7 and 8. These tensioning elements are resilient and are each split at one side thereof. Furthermore, as best seen in Figure 7, each of said elements is gradually thickened from its ends towards a point diametrically opposite the ends. Each of said elements may thus be said to have a thick side and a thin side, the thick side being located opposite the ends of the element and the thin side being located adjacent said ends.

brou 'ht under increased tension by the ex-,

pansion of the piston, the pressure exerted by said elements and tending to force the straight side of the piston against the cylinder wall will be automaticall Piston slap will thus be efl'ectua 1y obviated. I have shown only the head of the piston as equipped with rings. However, it will, of course, be understood, that the lower end portion of the skirt is preferabl equipped with a ring, as in the prior embo iment of the inventio Having thus described the invention, I claim:

1. The combination with a cylinder, of a piston movable therein and havlng an eccentric side, a ring carried by the piston, and an annular tensioning element acting on. the ring for forcing the piston laterally and holding the opposite side thereof in contact with the cylinder wall.

2. The combination with a cylinder, of a tapered piston movable therein and provided with a straight side of substantially the same radius as the cylinder and fitting the cylinder wall, a ring carried by the piston, and an annular tensioning element actin on the ring for forcing the piston latera ly and holding the straight side thereof in contact withthe cylinder wall.

3. The combination with a cylinder, of a piston movable therein and provided with an eccentric side and with a straight side of substantially the same radius as the cylinder and fitting the cylinder wall, and means forcing the piston laterally and holding the straight side thereof in contact with the cyl-. inder wall.

4:. The combination with a cylinder, of a tapered piston movable therein and provided near its lower end with a circumferential portion fitting the cylinder wall, the piston being provided with a straight side of sub stantially the same radius as the cylinder and fitting the cylinder wall, and means forcing the piston laterally and holding the straight side thereof in contact with the cylinder wall;

5 The combination with a cylinder, of a piston movable therein and tapered from substantially cylinder size near the lower end of the piston to under cylinder size at the upper end of the piston, the piston being provided with a straight side fitting the cylfinder wall, and means forcing the piston latan eccentric increased. 'ried by t e piston to coact erally and holdin the straight side thereof in contact with t e cylinder wall.

6. The combination with a cylinder, of a piston centered therein and provided with ortion and wit a concentric portion of substantially the same radius as the cylinder and fitting the cylinder wall, a ring carried by the piston, and an annular tensioning element actin on the ring for forcing the piston latera y and holding the concentric portion of the piston in contact with the cylinder wall.

7. The combination with a cylinder, of a tapered iston movable therein, a ring carand means acting on the ring for forci the piston laterally and holding one side t ereof in contact with the cylinder wall.

8. The combination with a cylinder, of a piston movable therein, a ring carried by the piston to coact with the cylinder, and an annular tensioning element acting on the ring for forcing the piston laterall and holding one side thereof in contact wit the cylinder wall, said element having a portion of increased dimension for increasing the lateral force on the piston as the piston ex ands.

9. The combination with a cylin er, of a piston movable therein and provided with a ring groove having abeveled bottom wall, a ring disposed in said roove and having a beveled face coac'ting wlth said wall, and a tensioning element urging the ring towards said wall for expanding the ring to coact with the cylinder, said element having a portion of increased dimension for exerting an increased pressure on aportion of the ring and forcing the piston laterally in contact with the cylinder wall.

with the cylinder,

10'. A piston ring tensioning element ineluding a split substantially frusto-conical annular member provided in the circumference thereof with a strengthened portion of increased radial dimension from upper to lower edge whereby the ring is graduated in thickness from minimum thickness at one point to maximum thickness at a diametrically opposite point.

11. The combination with a cylinder, of a tapered piston having a straight side, and 1 means forcing the piston laterally and holding the straight side thereof in contact with the cylinder wall.

12. The combination with a cylinder, of a ta ered piston movable therein and provided with a straight side and an eccentric side, and means forcing the piston laterally and holding the straight side thereof in contact with the cylinder wall.

In testimony whereof I afiix m signature.

JUDSON WILLIAM [1 s.]

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