US2128451A - Internal combustion engine piston - Google Patents

Description

n Aug. 30; `1938. c. BURTON y INTERNAL COMBUSTION ENGINE PISTON Filed March l, 1932 L. B U RTO In/vento@ Patented Aug. 30,

mzsssi Y PATE INTERNAL ooMnUsn'oN ENGINE Pls'roN 'i A Lawrence C. Burton, Houston, Tex., assigner of t y twenty-live percent toilester. Clark, Houston.;1r I

Tex. Application March 1,

` 3 Claims.

The invention relates to an improvement in pistons particularly of the type adapted for use in internal combustion engin.

due to heat during the operation of the engine there is no provision ior relative resiliency in the piston construction so that scoring of the cylinder l wall will be avoided. When the cylinder wall becomes worn and is rebored it is then necessary -1 to replace the piston with others o1' larger diameter. It is understood thatlvarious types of pistons adapted to be enlarged by the action of bolts l or wedges have been devised but even in such pistons the construction is still rigid and does I not permit of relative spring-like action of the piston with respect to the cylinder wall.. In thisy vide a piston having an independent skirt which*v 25 is adapted for relative expansion and contraction.

Another object of the invention is to provide 'a skirt portionfor pistons wherein the segments of the skirt are connectedy with an extensible poro tion formed integral with the segments of the skirt." 1

Another object of the invention is to provide f 'a splitsldrt for pistons wherein the portions of the skirt are connected together with anintegralv spring-like arch soA that there can be relativey vexpansion and contraction oi the skirt.

connection with the skirt portion. Another object of the inventionk is to provide a bearing support for pistons which bearing l and the skirt.

Another object o1' the invention is to provide a piston having a bearingy construction which is 50 indirectly connected to the skirt so that the skirt can be 'relatively moved with respect to the bear-y ing.

f Other and further objects of the invention will be readily 'apparent to those skilleddn the art Another object of the invention 1s to vprovidel Another object of the invention is to provide a`- piston wherein ythe head portion has no direct serves as the sole connection between the head connection lwith the -y accompanying drawin/g/l whereinl w Flg. 1 is a side elevation of the piston embodying the invention;

Fig. 2 is a central vertical section te ken through the bearing and wrist pin\illustrated in Fig. 1V

and illustrating the structure'along4 the sectionr line 2--2 of Fig. 4; f

Fig. Si` is a section taken at right angles to the section illustrated in Fig. 2 and illustrating the construction along the line 3--2101' Fig. 4; Fig. 4 is a'section taken on the line 4-4 of` Fig. Zand looking in the directionof the arrows. The inventionas here disclosed embodies the piston head 2 and the skirt I, which is composed of the segments 4 and 5. While two of these segi mentsl have been illustrated, the piston may be made up with a different number. Viewing the i section of Fig. 2, the head 2 is comprised oi' the side wall 6 and the top l. These portions are preferably formed integral and provided with the annular grooves 8 to receive the usual piston'ring. It is intended that any number of these grooves 8 will be provided and three have been illustrated in the present construction.

lIn order that the-piston will be suitably connected to the wrist pin and connecting'rod. two spaced bearings l0 andy Il have been provided. These bearings serve as a support i'or the struts I2 and i3, respectively. These struts are seen ilat, narrow bar which servesas the sole connection between the head *and the remaining parts of the piston. The skirt is thus free of the head and has no direct connection therewith,

in-horizontal section in Fig. 4 and comprise a because the connectionof the skirt segments I `and 5 to the bearings lil and Il is accomplished through the provision of bridges or varches l! vand it which are "illustrated as being formed integral with each oi the bearings I0 and il and connected to each o1' the skirt` segments I and l.

Fig. 3 and in section in Fig. 2', while Fig. 4 shows atop plan view illustrating the manner in which the bridge arches over the bearings lll and ll and is connected to the segments f'and 5 intermediate their ends. The bridge I5 is connected to the bearing Il while the opposite" bridge is indicated' at |67.

It should be noted, as seen in Fig. 2, that;y the struts l2 and I3 are connected to one edge of the bearings Ill and Il, respectively, whereas the bridges I5 and I6 are connected to theopposite ends of the bearings. In this manner additional ilexibilitywill behad so thatboth the headand Oneof these bridges is seen in front elevation in the skirt segments can have relative movement with respect to each other and vwith respect to Y the bearing supports by which ,they are carried..

In order that the thrust applied to the piston head 2 by the explosion in theenginecarrbe transmitted properly to the bearing; a reenfo'rcing rib iB has been formed which tends ,to back up zthe" struts I2 and I3 and blends ,itselfi in withvthe bearing IIJ and terminates' as at. |19 a'gairistthe inside face 4of the bridge.. A'similar flange 2| is provided beneath the bearings lto lend` rigidity to the single, line of contact of, the bridge with the bearing. AV suitable liner 22 may or may not be inserted in the bearing. Each of the skirt seging `provided by these' areas .and properly positioned within the bearings III and II. The wrist pin is shown in dotted lines at 24 in Fig. 2, The circular skirt segments or sections form a com- 'plete .circle and are adapted tol contact the'cyl- 'inder wall over their entire area; Such a piston is generally termed a barrel type piston as distinguished from those pistons wherein parts oi the skirt are set radially inward so that the skirt does not form a barrel or circle. y

From the foregoing description it will be readily apparent that a piston has been provided wherein the heat transfer from the head of the piston to the skirt segments is indirect, in that it must pass through the bearing portions. There is a considerable area, as at 25, between the piston head and the top of the skirt. and the only portion through which the heat may pass is through the struts I2 and I3. These are of such small cross section that a very small amount of heat will b e transferred and the skirt segments 4 and 5 will be practically independent of any influence due to excessive heating of the piston head.

' One of the particular advantages of the present invention is the formation of the bridges I5 and i6. ,-These bridges or arches serve as a more or less flexible or spring-like connection between the two segments or sections 4 and 5.V This bridge is of a material which is suitable vto be deformed and to maintain at all times a resilient pressure upon the respective segments. ,y

With a solid piston construction it is necessary to leave a clearance when assembling the engine of .003 or .004 of an inch due to the fact that the piston is rigid and when subjected to heat will expand in `the cylinder. Suilcient area is required to accommodatethis expansion and if a relatively snug t is provided on the piston the cylinder will be scored when the piston expands. With the present invention it vhas been found that the piston can be fitted to the cylinder with a clearance of only .001 or .002 of an inch because of the springlike or resilient connection between the segments 4 and 5. Thus, if desired, va ring clamp can be placed about the skirt of the piston and it can be inserted in the cylinder. This ring clamp will tend to arch the bridges I5 and i6 to cause a slight reduction inthe diameter of the piston. There is no unyielding force, however, created against the cylinder wall because the bridges I5 and IS will be arched in accordance with the pressure against the cylinder wall. When the piston is heated, if the pressure against the cylinder wall is increased, the bridges I5 and I5 will absorb any excess pressure and in this manner no scoring of the cylinderwall will occur.

The bridges I5 and I5 are of such construction that when the piston isv properly fitted in the cylformation of the arch willrepresent the amount finder and under working temperatures 'they will normallyexert an outward pressure on the segmentsA 4 v'and 5 and maintain the segments in engagement with the cylinder wall to obtain a perfect lit of' the 4piston at all times. The resilient 5 j mountingof these segments 4 and 5 is, one of the" essential features of theinvention.

After the' piston has been in use for some time` or if it is rdesired to lit lthe piston to a slightly yIingIylengthened. Any lengthening of the arch or bridge tends to move the segments 4 and 5 away from each other and in this manner increase 20 the size of the piston; No adjusting bolts or rivets are required to obtain a larger diameter piston in the present invention. When itis desired to 'extend the diameter of 'the piston it is only necessary to attach a lsuitable clamp to the'segments' 4 and 5 and apply a pressure which will tend to flatten the bridges I5 and I5. Obviously when thesebridges are flattened, the ends where theyL are joined to the skirt will be spacedfurther apart and the span of the bridge lengthened. One

manner of accomplishing this extending movement is to pla'ce a wedgevor block between the surfaces 30 and 3I of the bearings I0 and VII and to then apply pressure at the points 32` and 33. This pressure'will be axial with respect to the bearings and toward the center of the piston'so that the bridges or arches will vbe flattened or elongated sufficiently-to take a set after the pressure is released. The amount of permanent deof enlargement of thepiston.`

In order that a clamp may be suitably attached at this point the indentations or clamp seats 35 have been provided. If the bearings I0 and II are suitably braced and pressure is 45 applied at the points 32 and 33, the bridges I5 and I5 will be flattened so that the points 3l and 38 on each of the'slzirts will be 1nri'o'ved radially outward. It should be recalled that it is only intended to increase the diameter of the piston by a distance of several thousandths of an inch in order that it will be available to properly fit the worn bore of the engine or a rebored cylinderl or to t a bore which is slightly larger thany the original diameter ci the piston.

In enlarging the diameter of the piston it may be necessary to insert `a wedge in the space 45 between the flanges di and 42 of the segments 4 and 5, respectively." Such a wedge would be driven in between the end 45 of the bearing and the strut I3, so that the flanges 4I and 42 would be moved radially outward. After the clamping vaction and expansion'of the flanges, if necessary l may.result in springing the parts slightly beyond their original elastic limit it has been found in practice to adapt the piston for a larger bore. In

view of the very slight increase in size it has been yfound to be not detrimental to the piston. The

resilient construction of the piston will avoid piston slap and prolong the service to be obtained.

As'stated heretoforel the present piston may 75 be tted to the cylinder with a lesser clearance than pistons having a solid skirt, or with pistons having a split skirt whose adjustment is accomplished by means of extensible bolts due to the fact that the skirt segments are resiliently mounted with respect to the bearing. It should be noted that the arches i! and it extend substantially theglength of the skirt portion so that they will insure a proper support for the skirt and provide a sturdy construction. The action of the skirt in its resilientmovement is entirely independent of the head which carries the piston rings and due tothe springlike action of the bridges II and it the skirt segments will be pressed against the cylinder wall with a very small clearance at all times. In other words, the segments 4 and I will be permitted .to have a relative movement with respect` to the bearing supports so that they will ilt themselves to the cylinder wall. It is believed that such a construction is oi' advantage because the segments I and I are capable of blending themselves into the contour of the cylinder wall regardless o! whether such.

cylinder is a perfect circle or not.

While a specific form of the invention has been here shown and described it is contemplated that the relative resiliency of the skirt segments can be accomplished by other forms of construction and that the invention will only be limited by the scope of the appended claims.

What I claim as new is:

l. A piston includinga head and a skirt, two

spaced wrist pin bearings having struts extending from the outer ends thereof and connected to said head. said skirt being split into two sections along the axis of the wrist pin bearings and encircling said struts and bearings, and arcuate bridges having their arches attached to the inner ends of said bearings and one end of each bridge being attached to each section whereby said skirt may have relative movement with respect to said head or said bearings.

2. A barrel type piston havinga separated head and skirt, two struts disposed within theconnes of the head and skirt. a wrist pin bearing on each strut and extending inwardly therefrom, an arch bridge connected to the inner end of each bearing and curved with its ends connected on a radius on each side of the bearing to the skirt, and a. split in the skirt radially outward from each bearing whereby expansion of LAWRENCE C. BURTON.

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