US2432687A - Piston expander - Google Patents

Description

Dec. 16, 1947. M SIPE 2,432,687

PISTON EXPANDER Filed Aug. 8, 1946 f" 3 1X I H mmvrox. MART/N t. 51 15.

A TTORNE Y.

Patented Dec. 16, 1947 UNITED STATES PATENT ()FFICE PISTON EXPANDER Martin E. Sipe, Denver, Colo.

Application August 8, 1946, Serial No. 689,121

3 Claims. 1

This invention relates to improvements in means for expanding a split piston skirt to compensate for Wear and eliminate piston slap, excess oil consumption, blow by and other objections due to excess wear.

It is well known that split skirt pistons, especially those made from aluminum and aluminum alloys wear rapidly and soon develop piston slapfiexcessive leakage of oil and gas, etc.

In order to automatically compensate for such weanvarious specifically different devices have been invented for exerting a constant expandng force on the piston skirts. Piston skirt expanders are, as a rule, made from rather thin steel that is bent into the desired shape and then hardened and tempered.

Piston skirt expanders must be constructed in such a manner that they are held in deformed position by suitable means in which condition they may be introduced into the piston'after which the restraining means is removed allowing the device to expand into engagement with the inner surface of the piston. skirt.

One specific form of piston skirt expander is shown in my pending application Serial No. 642,- 287 filed January 19, 1946, now Patent No. 2,418,053.

It is the object of this invention to produce a piston skirt expander of the general shape shown in the above identified application, which shall be so constructed that it can be more readily manufactured and assembled and in which the restrainin means can be more readily rendered inoperative.

Having thus described the invention in a general way and some of its objects, the invention will now be described in detail and for this purpose reference will be had to the accompanying drawing in which the invention has been illustrated, and in which:

Figure 1 is an end view of a split skirt piston, looking through plane l--i in Figure 2 and shows the expander in position and before it has been released;

Figure 2 is a side elevation of a piston, partly broken away to show an end view of the expander;

Figure 3 is a section taken on line 3-3, Figure 2;

Figure 4 is a plan view of the expander; and

Figure 5 is a perspective view of one-half of the expander.

In the drawing reference numeral 5 designates an ordinary automobile piston of the split skirt numeral 6 and the cut in the skirt wall by reference numeral 1. The specific type of piston illustrated has openings 8 at opposite sides and is provided with aligned bearings 9 for the piston pin ill. The piston pin bosses have inward extensions which have been designated by reference numerals l The expander is positioned between the bosses l I in the manner shown in Figure 1 and will now be described in detail.

The expander consists of two identical pieces like the one shown in perspective in Figure 5, each half of the expander has a straight center portion i2 that is provided with an opening l3 through which th piston pin may pass. At the ends of the straight portion i2, the material is bent inwardly at an angle of substantially degrees forming inclined walls l4 that terminate in out-' wardly convex reverse curves l5 that again terminate in reversely extending end portions I B which are tapered as shown in Figure 4 and have narrow ends I! that lap the straight portion l2 and are bent sothat they are parallel with the straight portions when in contact therewith. Ends it normally occupy positions like that designated by reference numerals [8 shown by dot-- ted lines in Figures land 4 and must be forced into the full line positions by means of suitable bending tools which have not been shown in the drawing. After ends it have been forced into the full line position shown in Figure 5, ends I1 are spot-welded to the straight sides I2 and in Figure 4 the welding electrodes have been shown by broken lines. The spotweld holds the ends IS in full line position until it is broken by means of a suitable tool. In Figure 4 the piston skirt has been indicated by dotted lines and it will be seen that when the expander is in full line position, some space is left between the ends of the expander and the inner surface of the skirt so as to permit the expander to be freely inserted. After it has been inserted, the spotwelds are broken, as above intimated, and the curved ends is moved outwardly into engagement with the inner surface of the skirt exerting on the piston skirt a strong expanding force that moves the parts outwardly to compensate for wear.

In order to facilitate the distribution and also the insertion of the expanders, each expander part is provided with arms i9 that overlap as shown in Figure l and which are spotwelded in overlapped position. The interconnection between arms l9 facilitates the handling of the expander and its insertion into the piston. After the expander is type. The skirt has been designated by reference, is; in posit o a s 9 form no particular useful function and the connection between them may then be broken, if desired.

It will be observed that the expander that forms the subject of this invention is of a very similar construction to the one described and claimed in the above identified application and patent. The main, and almost the only distinction between the two structures, is that in the application above identified, the resilient ends l6 are secured to the remainder of the expanders by means of a releasable mechanical latch such as a hook, whereas, in the present embodiment, the ends are secured to the straight portions by means of spotweld.

In order to make it practical to spotweld the parts in the manner shown in the drawing, the ends H must be so bent or curved that they will be parallel with the surface to which they are spotwelded. If the parts are not so related as to effect this, very powerful strains are set up that will break the spotweld. In the embodiment i1- lustrated, ends ll overlap straight sides l2, but it is possible and may, at times, be preferable to spotweld the ends of members it to the outer surface of the inclined walls [4, in which case ends I! must be bent in such away as to make them parallel with the surface to which they are to be spotwelded, and such a construction has been indicated by dotted lines in Figure 4.

The construction described above has several advantages over the construction shown in the application above identified, some of which pertaln to the manufacture of the expander making it possible to efiect the entire manufacture and assembly by means of suitable tools and another advantage derived from this is that the ends Hi can be released by means of a screwdriver or chisel with less effort than necessary to release the interconnection employing a hook.

The construction above described can also be made with simpler and cheaper dies than a construction employing a hook interconnection.

In the above description the invention has been explained in connection with a split skirt piston. Some pistons do not have split skirts, but have very thin skirts instead and the expander, when used with such thin skirts, deforms the piston forcing it out of round and efiects the same re* sult as with a split piston.

Having described the invention what is claimed as new is:

1. A piston skirt expander of generally elongated hexagon shape, provided at each end with outwardly and rearwardly curved resilient portions lying wholly on the outside of the hexagon, said rearwardly curved portions being biased with their ends away from the outside of the hexagon but movable into contact therewith, in response to a sufficient force, the ends being shaped to present a flat surface parallel with the surface of the hexagon surface, the ends being connected with the hexagon by a spotweld of suilicient strength to resist the force exerted by the resiliency of the reversely curved portions.

A piston skirt expander of generally elongated hexagon shape, provided at each end with outwardly and rearwardly curved resilient portions lying wholly on the outside of the hexagon, said rearwardly curved portions being biased with their ends away from the outside of the hexagon but movable into contact therewith in response to a suflicient force, the ends being shaped to lap the central flat sides of the hexagon and to present a flat surface parallel therewith, the ends being connected with the central fiat portion by a spotweld of sufficient strength to resist the force exerted by the rearwardly bent resilient ends.

3. A piston skirt expander of generally elongated hexagon shape, provided at each end with outwardly and rearwardly curved resilient portions lying wholly on the outsidt of the hexagon, said rearwardly curved portions being biased With their ends away from the outside of the hexagon but movable into contact therewith in response to a suflicient force, the ends being shaped to lap the central fiat sides of the hexagon and to be moved into parallelism therewith, the ends being connected with the central flat portion by a spotweld of sufficient strength to resist the force exerted by the rearwardly bent resilient ends.

MARTIN E. SIPE.

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