US1956328A - Piston expander - Google Patents

Description

W" 24, 1934- A. w. MORTON 1,956,328

PI STON EXPANDER Filed Dec. 16 {1933 2 Sheets-Sheet 1 SK 5 I E ,4 132+, f i

3uventor;

" mum w. mlozkon/ (Ittornegs April 1934a A. w. MORTON 1,956,328

' PISTON EXPANDER Filed Dec. 16, 1933 2 Sheets-Sheet 2 Ismaentor BB k (Ittornegs Patented Apr. 24, 1934 PISTON EXPANDER Allen W. Morton, Baltimore, Md., assignor to The American Hammered Piston Ring Company, Baltimore, Md., a corporation of Maryland Application December 16, 1933, Serial No. 702,775.

9 Claims.

This invention pertains to expanders for pis-- tons of the split skirt type, which are now commonly employed in explosive engines, and more particularly those designed for automotive purposes.

The main object of the invention is to produce a simple and yet withal effective expander, the same being produced from spring wire and so shaped or bent to form as to produce the necessary or requisite outward pressure upon the inner face of the skirt, to expand the same.

The structure is such that the expander may be readily positioned within the piston, and, when fully positioned, will automatically pass into the slots or openings normally existing in pistons of the type above referred to, and thus lock the parts against relative endwise movement while still permitting the expander to act v to force the sections of the piston skirt outwardly.

Another advantage of this type of expander, owing to its contour, is that it can be made to exert the greatest amount of expansion at the lower portion or near the end of the piston skirt, and a secondary or less amount of expansion at the upper portion of thelskirt, or that portion opposite or slightly above the piston pin bosses. Collapse at the bottom of the piston is frequehtly caused by the rocking action of thepiston, but this may be corrected to a large extent by the use of an expander such as hereinafterdescribed.

Yet another advantage is that the expander mary or maximum pressure may be obtained at the top portion of the piston skirt, or nearly in the plane of the piston pin, and the secondary pressure at the lower portion, or near the end of the piston skirt.

Still another advantage of the type of expander herein set forth is that the length of the main body portion, which serves to exert or impart the bulk of the spring action to the structure,. can be so varied as to exert the desired degree of pressure against the piston skirt.

With theseand other objects and advantages in view, reference will be had to the annexed drawings, wherein:

Figure 1 is a perspective view of the preferred form of expander;

Fig. 2 is a top plan view thereof with the expander shown as partially compressed prior to its introduction into a piston;

Fig. 3 is a vertical sectional view of a split skirt piston with the expander of Fig. 1 fu11y posican be positioned within a piston so that a pri-.

tioned therein, the section being taken on the line III-III of Fig. 4;

Fig. 4 is a like view taken on the line IVIV of Fig. 3;

Fig. 5 is a perspective view of a portion of a piston and the closed looped end of the expander, and illustrating the manner of engagement of said end with the piston;

Fig. 6 is a perspective view of a modified form of the expander;

Fig. 7 is a vertical sectional view on the line VIIVII of Fig. 8, of a piston with the expander of Fig. 6 shown as positioned therein; and

Fig. 8 is a like view on the line VIII-V1II of Fig. 7, looking toward the left of said figure. Under both forms, it will be seen that the expander is shaped from a single piece of wire, such as spring wire produced from a suitable heat resisting alloy, so that the expander will retain its resiliency notwithstanding the high and varying temperatures to which it is subjected when in use.

In a broad sense, the expander may be said to comprise two arcuate or substantially bowshaped body members which stand in approximate parallelism, and which are connected at one end by a loop-like pressure applying element, while at the opposite end of each loop there is 7 formed a bearing or pressure arm, the various parts being formed integrally. 35

In the drawings, Figs. 1 to 5, 10 and 11 indicate the main arcuate body elements or bows which, when the expander is positioned within a piston skirt, extend transversely thereof with the bows directed upwardly. 90

The members 10 and 11 at the lower portion of one end thereof are curved inwardly, as at 12 and 12 and from such portions there extends upwardly a closed loop formed bythe members 13 and 14, connected by the cross baror element.15.

As will be seen upon reference more particularly to Figs. 1, 3 and 5, the upper ends of the members 13 and 14 where they merge into the bar-like element 15 are bent outwardly to a slight extent (see Figs. 1 and 2). Said bar-like member 15 is slightly curved in outline and provided with a flat upper face 16 which, when theexpander is positioned within the piston skirt, permits the bar to pass into a slot, such as 17, formed in the skirt 18 of the piston which is split longitudinally at least at one side, as at 19.

The thickness of bar 15 is such that its upper flattened face bears directly against the upper no wall of slot 17, and likewise by reason of the curvatures above mentioned, the bar also contacts the lower wall as well. In other words, the bar may be said to have a wedging connection with the piston by reason of the formation just described.

As will be seen upon reference to Fig. 3, the bar-like member 15 does not extend out beyond the face of the skirt, and is so positioned beneath the ring belt of the piston that there is no outward projection at this point.

At the opposite end of the expander and extending upwardly from the lower end of the member 10 is a bearing arm or element 21, formed by recurving or bending the wire upon itself, as at 22. At its upper end, the member 21 is provided with a single lateral projection 23 extending outwardly therefrom, the upper face whereof is flattened at 24. A similar arm is formed upon the member 11, and like parts are indicated by the same reference numerals with the exponent a added thereto. The fingers 23 and 23 will, when the expander is positioned within the piston skirt, extend into a second slot 17, which is ordinarily present in the commercial pistons of today, the fingers being so proportioned as to make a tight or close fit with the walls of the slot.

To position the expander, it is only necessary to compress the same by forcing the arms 21 and 21 toward the bearing members or arms 13 and 14. This collapses the expander to a sufficient extent to permit it to be moved upwardly into the piston, in the position shown in Fig. 3, when the cross bar 15 will enter, or may be forced into the slot 17 and the fingers 23 and 23 will be positioned in the slot 1'7, in a like manner.

The upper and lower portions of the members 13, 14, 21 and 21 move out into contact with the inner wall of the piston, and at the same time, the bar-like element 15 and the fingers 23 and 23 will enter the slots 17 and 1'7 in wedging relation therewith.

The structure is thus locked against endwise movement relative to the piston, and this condition obtains under all operations of the engine. The bearing portions of members 13, 14 and the interconnecting cross bar 15, together with the bearing portions of arms 21 and 21 will at all times exert an outward pressure upon the piston skirt.

It is preferable to have the arms 21 and 21- positioned to either side of the vertically disposed slot 19, as best shown in Fig. 4. Under this arrangement, a direct pressure is exerted upon the skirt to either side of the slot and expansion of the piston skirt, therefore, is more readily obtained.

The expander, of course, may be turned end for end and installed in the piston so that the members 13 and 14 straddle the slot 19 of the piston.

In the broader aspect of the invention, the structure shown in Figs. 6, '7 and 8 may be employed, and the same principle of utilizing the arcuate expanding members carrying at each end bearing members, is present. The expander is automatically locked in position by engagement of portions thereof with the walls of the usual horizontally disposed slots, as in the structure above described.

As will be seen upon reference to Fig. 6, there are two inverted arcuate or bow- shaped members 30 and 31, said members at one end being bent or turned inwardly as at 32 and 33, and from the inner ends of these inturned portions there 5X- tends downwardly an integrally formed loopshaped bearing element 34.

The upper ends of the inturned portions 32 and 33 are flattened as at 35 and 36, respectively, in order that the inturned or bar-like portions formed at this point may enter the horizontally disposed slot 17 formed between the piston skirt and the ring belt of the piston. In other words, this slot is the same as the slot 17 in the structure above described.

The arcuate member 30 is provided with a downwardly extending arm 3'? at that end opposite the loop-shaped element 34, the connection between the upper portion of the arm and the upper end of the arcuate member 30 being defined by a bend or cross bar 38, which is flattened upon its upper face as at 39.

Member 31 is also provided with an arm formed in the same manner as that just described for the arcuate member 30. Similar reference numerals appear upon the same parts, with the exponent a added thereto.

It will be noted upon reference to Figs. 6 and 8, that the arms 3'1 and 38 are spaced apart and when the expander is positioned within the piston, they bear against the skirt to each side of the longitudinally extending piston slot 19. So, too, the recurved or inwardly extending portions 32 and 33 do not contact each other, and this separation of the arms and the elements just mentioned affords a flexibility to the structure which might not otherwise obtain.

When positioned within a piston, the flattened faces 39 and 39 formed upon the bars 38 and 38 extend into the horizontally disposed slot 17 By utilizing the ordinary slots 17 and 17 commonly found in pistons of the split skirt type, in which the locking elements of the expander may enter and wedge, all relative movement of the parts, when the engine is in operation, is obviated.

Hence, there is no wear imposed upon either the piston or the expander, and the expander always exerts the necessary and requisite pressure through the bearing members formed at each end of the arcuate or bow-shaped elements.

Under both forms, as shown and described, there is no contact between the incurved portions which connect the members forming the loopshaped bearing element, nor is there any contact between the arms 21 and 21 and the corresponding elements 37 and 3'7 of Fig. 6.

By reason of the separation of the arms at the free ends of the arcuate members, not only do the arms act to force or-expand the piston skirt outwardly in the direct line of contact, but there is also a slight tendency for the arms to move over the inner face of the piston away from each other. Thus it may be said that a pressure exists which is the component of the direct pressure and the pressure which obtains by the movement of the arms away from each other, as the piston is expanded.

It is to be noted that the main supporting or bow- shaped elements 10 and 11, 30 and 31 do not come into direct contact with any portion of the piston and, consequently, the only heat which reaches the spring portion of the expander is that transmitted through the skirt and the ends of the expander to the central portion or bowshaped members. Hence, the liability of the spring losing its tension due to heat is greatly diminished. The expander can also be used in a greater number of different pistons than most expanders of commercial success, only five sizes of the expander being necessary to take care of practically all of the automotive piston sizes now currently in use.

I am aware of U. S. Letters Patent No. 1,428,492 to Page, dated September 5, 1922, which patent is now owned by the assignee of this case.

What is claimed is:

1. An expander for pistons of the split skirt type, the same being produced from a single piece of spring wire bent to form a pair of laterally displaced bowed or arcuate elements;'a pressure applying loop formed at and connecting adjacent ends of said elements; and an arm extending from the opposite free end portion of each bowed element, said loop and arm being adapted to bear against the inner surface of the piston skirt when I the expander is positioned therein under compression.

2. A structure as set forth in claim 1, wherein those portions of the expander which align with the usual slots which are present between the piston ring belt and the upper portion of the skirt in a divided skirt piston, are so shaped that they pass into said slots, into contact with the upper and lower surfaces which define the slots, when the expander is fully positioned within the skirt.

3. An expander for pistons of the split skirt type, said expander being produced from spring wire, comprising in combination two arcuate members, each of which is provided at its ends with a bearing member for contacting the inner face of the piston skirt, said members being produced by bending the wire of which the arcuate members are formed back upon itself; and one pair of adjacent bearing members being integral with each other and the arcuate members, and serving to position the two arcuate resilient members with reference to each other.

4. In combination with a piston having a divided skirt and the usual openings extending between the skirt and the piston ring' belt, an expander for the skirt, comprising a pair of arcuate members, said members at one end being interconnected by a loop which bears directly against the piston skirt, while the other end of each of said members is provided with a bearing arm, said arms being spaced apart and bearing upon the inner face of the piston to each side of the longitudinally extending dividing slot formed in the piston skirt.

5. A structure as set forth in claim 4, wherein the loop and the arms are provided with projections adapted to pass into the slots formed between the piston skirt and the ring belt of the piston and into contact with the upper and lower walls of the slots, whereby the expander is held against longitudinal movement relative to the piston, while still permitting the expander to act to enlarge the skirt diameter.

6. In combination with a piston having a ring I belt, a divided skirt and slots formed between the upper edges of said skirt and the ring belt; an expander for the piston skirt, said expander comprising two arcuate shaped elements; formed at one end of said arcuate members, said loop at its upper portion being curved slightly in an outward direction and having its upper face flattened, the opposite end of the arcuate members being inwardly curved and terminating in pressure arms'extending upwardly from said curved portion, said arms being free of any connection with each other, and provided at their ends with outwardly extending projections, said projections and the flattened portion on the loop aforesaid being adapted to enter and wedge in the slots which underlie the head above the skirt.

7. An expander for pistons of the split skirt type, comprising a loop shaped member; means thereon for interlocking it with such a piston; a pair of upwardly extending arcuate shaped members interconnected with the lower ends of said loop by incurved portions at the bottom of the loop; and a pair of spaced arms extending upwardly from the opposite ends of said arcuate shaped members, said arms having means on the ends thereof for attaching them to the piston.

8. An expander for pistons of the divided skirt type, the same being produced from a single piece of spring wire bent to form a pair of laterally disposed, downwardly extending bowed or arcuate elements; a pressure applying loop formed at and connecting a pair of adjacent ends of said elements, the interconnecting portions of the loop to the arcuate members being flattened upon their upper faces; a pair of pressure arms extending downwardly from the other end of the arcuate members, the portion which connects each arm to its arcuate member being flattened upon its upper face, said arms being out of contact with each other and' the connecting portions of the loop aforesaid likewise being out of contact with each other.

9. In expanders for pistons of the divided skirt type, the same being produced from a single piece of wire bent to form a pair of arcuate shaped members; piston-contacting elements carried at the opposite end of each of said arcuate members, said piston-contacting members bearing at their upper and lower ends only against the inner face of the skirt; and means formed upon the expander for entering openings normally found in the piston beneath the ring belt for locking the expander in place within the piston.

ALLEN W. MORTON.

a loop-

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