US2689773A - Piston with cast-in ring groove insert - Google Patents

Description

Sept. 21, 1954 A. M. BRENNEKE PISTON WITH CAST-IN RING GROOVE INSERT 2 Sheets-Sheet 1 Filed Nov. 6, 1951 26 26 JNVENTOR P 1954 A. M. BRENNEKE PISTON WITH CAST-IN RING GROOVE INSERT 2 Sheets-Sheet 2 Filed Nov. 6, 1951 INVENTOR.

QrZ /LurMBren neke Patented Sept. 21, 1954 PISTON WITH CAST-IN RING GROOVE INSERT Arthur M. Brenneke, Hagerstown, Ind., assignor to Perfect Circle Corporation, Hagerstown, Ind.,

a corporation of Indiana Application November 6, 1951, Serial No. 255,001

20 Claims. l

The invention relates generally to pistons and more particularly to a piston for an internal combustion engine, made of relatively light metal such as aluminum and having a ring groove provided with a cast-in insert of relatively hard metal such as steel.

It is desirable to make pistons for internal combustion engines of aluminum or other light metal since the reduction in weight from that of a cast iron piston is advantageous in a reciprocating part. However, these light metals and particularly aluminum are relatively soft, and undue wear of the sides of the ring groove occurs because the piston rings are usually made of harder metal such as cast iron or steel. An insert providing harder wear-resistant sides for the groove, cast into the piston, has heretofore been provided but, if the insert were made of iron or steel, the difierence in the coefiicients of expansion of iron or steel on the one hand and aluminum on the other is so great that the insert would become loose from the body of .the piston after heating and cooling. To avoid this difliculty, inserts of some special alloy have been used where the alloy has substantially the same coefiicient of expansion as the aluminum, but such alloys are expensive.

The general object of the invention is therefore to provide a novel piston construction made of a light metal such as aluminum and having an insert made of steel, the insert being formed and embedded in the body of the piston in such a manner that it will not loosen from the body even after repeated heating and cooling.

Another object of the invention is to so construct the insert that at least a part of the difference in expansion between the steel insert and the body is taken up by mechanical expansion of the insert.

Still another object is to provide an insert made of steel and formed of a plurality of cirlcumferentially extending lengths or segments connected in such a manner that the diiierence in expansion for the respective lengths does not become cumulative for the entire circumference.

A further object is to provide a piston and groove insert construction in which the insert is embedded in the body of the piston in a novel manner.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawings, in which:

Fig. 1 is a perspective view of a piston of the character herein contemplated.

Fig. 2 is an enlarged fragmentary sectional view of a piston showing one of the piston ring grooves provided with an insert embodying the features of the invention.

Fig. 3 is a fragmentary elevational view of the outer periphery of the insert.

Fig. 4 is a transverse sectional view of the in sert taken on the line 4-4 of Fig. 3..

Fig. 5 is a fragmentary view of a strip of sheet metal from which the insert is made.

Fig. 6 is a fragmentary perspective View of the insert before being cast into the piston.

Fig. 7 is a view similar to Fig. 6, but showing a modified form of insert.

Fig. 8 is a fragmentary view of a strip from which the insert shown in Fig. '7 is made.

Fig. 9 is a perspective view similar to Figs. 6 and 7, but showing another modified form of insert.

Fig. 10 is a fragmentary view of the strip of sheet metal from which the insert shown in Fig. 9 is made.

An insert of the type herein contemplated is adapted to be cast into a piston made of light metal such as aluminum, to provide a hard wearresistant surface for the sides of a ring groove in such piston. Such insert is made of steel because of the relatively low cost thereof, and because of the wear-resistant qualities thereof. As heretofore stated, an insert which is continuous inlength throughout the circumference of the ring, or for a major portion thereof, will tend to break away from the body of the piston due to the difference between the coefficients of expansion of steel on the one hand and the light metals such as aluminum on the other hand. In the present description and in the claims, reference is made to a piston made of light metal, and by that term it is intended to include such metals as aluminum and others from which pistons may be made. At present, the only light metal that is used to any extent in the manufacture of pistons is aluminum. However, other light metals have been contemplated, such as magnesium or combinations of magnesium and aluminum. These metals would be subject to' undue wear at the sides of a ring groove, since they are relatively soft compared to the metal otf the piston ring, which is usually cast iron or s eel.

To avoid loosening of the insert from the body of the piston, the present invention contemplates a construction which comprises a plurality of relatively short segments so that the difference in expansion between the two metals in such a short length is relatively minor and will not tend shown in detail in Figs. 2 to 63, inclusive.

- and thus permanently secure the insert in place.

In the drawings, I have shown in Figs. 1 and 2 a piston 20 adapted to operate within a cylinder 2i and having a ring groove 22 formed in the piston adjacent the head end thereof.

Mounted in the groove 22 to provide wearresistant side surfaces therefor is an insert, in dicated generally at 23, one form of which is This form of insert comprises two axially spaced flanges formed by rows of segments 24 with the outer edges of the segments located at the outer periphery of the piston 29. The two rows of segments thus provide substantially continuous side surfaces for the groove 22. In the present instance the segments in one row are in staggered relation to the segments in the other row, and each segment in one row is connected to two segments in the opposit row by means of web members 25 which extend inwardly from the segments and thence axially to connect with the segments in the opposite row. A structure which is U shaped in radial cross section is thus provided.

The web members 25 constitute spring means which permit relative expansion and contraction between the segments in the two rows so that when the insert is located within a ring groove in a piston, the difference in expansion between any one segment and the adjacent portion of the body does not affect the relation between the adjoining segments and the body. Such difference, therefore, does not become cumulative throughout the circumference of the piston. The web members 25, when such difference in expansion occurs, are capable of flexing so that there is no tendency caused by the expansion of one segment to pull or force the segments connected thereto out of place. To firmly secure the insert in place in the piston, the web members 25 as well as the segments may be embedded in the metal of the body by placing the insert in position in the mold for the piston and then pouring the molten metal about it.

The invention also contemplates the provision of additional portions of the insert which are completely embedded in the body so as to firmly secure the insert in place. In the present instance, such additional portions are in the form of tongues 26 preferably extending from the inner portions of the segments away from the groove 22 so that they can be completely embedded in the metal of the body. As shown in the drawings, the tongues 26 extend axially away from the groove 22 and are integrally connected to the segments at the inner edges thereof. In the present form, there are two such tongues for each segment, and the tongues alternate with the web members 25. Each segment is thus rigidly held in position in the body of the piston, but because of the flexure permitted by the Web members 25, the difference in expansion for one segment does not affect the other segments.

An insert of this construction may be readily made from a strip of sheet steel. Thus, as shown in Fig. 5, a strip 3 is provided. To form the segments, transverse shears 3| are cut in the strip, extending inwardly and alternately from opposite edges of the strip. Additional transverse shears 32 are also cut in the strip intermediate the shears 31, with the shears 32 lying only in the central portion of the strip and not extending to the edges thereof. The shears 32 with adjacent shears 34 thus provide web membore 25. Longitudinal shears 33 are also cut in the strip, the shears 33 lying on the center line of the strip and connecting adjacent pairs of shears 3| and 3 2. The shears 33 together with the shears 3i and 32 thus form the tongues 26.

After the strip is thus sheared, it is bent along two longitudinally extending lines to provide a U shape in cross section. The tongues 26 are also bent outwardly. The strip then is given a circular form and is ready to be placed in the mold for casting the piston about it.

In Figs. 7 and 8, a modified form of insert is shown. In this form, a series of transverse shears All are cut in the strip to extend inwardly from the opposite edges thereof and the shears 4i) terminate in small apertures 4| which are located a short distance away from and on opposite sides of the center line of the strip. Additional transverse shears 42 are also cut in the strip on opposite sides of each pair of shears 40, the shears 42 being located in the central portion of the strip and terminating short of the edges thereof. Each pair of shears 42 are connected by a shear 43 extending longitudinally of the strip on the center line thereof, the shear 43 extending between the two holes 4| at the inner ends of the shears 40.

By shearing the strip in this manner, twoseries of segments 44 are provided along the respective edges of the strip, and the two series are connected by web members 45. Each pair of shears 42 with the connecting longitudinal shear 43 pro vides a pair of tongues 45 on opposite sides of the center line of the strip and each tongue 46 is bifurcated by the shear 40.

After the strip is thus sheared, it is bent along two longitudinally extending lines to give it a U shape in radial cross section and the tongues are bent outwardly from the planes of the two rows of segments. With this construction, the segments in one row are aligned with the segments in the opposite row and are connected by the web members. 45. Circumferential'connection between the segments is provided by the tongues 36, each of the latter being bifurcated by a shear 40 so that the two sides or arms thereof are respectively connected to adjoining segments. The tongues 46 thus provide'for expansion and contraction between the segments in each row and, since the tongues are adapted to be embedded in the metal of the piston, they rigidly hold the segments in place. The side portions or arms of each tongue are capable of flexing so that the difference in expansion between the metal of the piston body and each segment is not transmitted to the adjoining segments. The insert will thus be firmly held in the body of the piston without loosening.

The modified form of insert shown in Figs. 9 and 10 is similar to that shown in Figs. 7 and .8 and is formed by similarly placed shears cut in a strip of metal. However, in this instance the shears 42 are widened at their ends by punching, as shown at 41. The tongues thus formed by the shears 42 are separated from the main portion of the metal by these enlargements 4.1 and the metal of the piston body can" thus fill the enlargement 41 and more firmly embed the ihsert the piston body. Furthermore, the enlargements 4! reduce the size of the two sides of each tongue where the latter is bifurcated so that thetongues are more flexible.

I claim: i

l. A piston construction comprising a light metal body having a ring groove therein, and a steel insert for the groove embeddedin the body, said insert being U-shaped in cross section to provide a pair of wear-resisting flanges for the sides of the groove, each flange comprising a plurality of segments connected to adjacent segments of said flange and connected to the segments of the other flange by circumferentially spaced web members embedded in the body.

2. A piston construction comprising a light metal body having a ring groove therein, and a steel insert for the groove embedded in the body, said insert comprising a pair of axially spaced flanges for the sides of the groove, each flange comprising a plurality of segments, and circum" ferentially expansible means connecting the segments of the two flanges and embedded in the body.

3. A piston comprising a light metal body having a ring groove therein, and a steel insert for the groove, said insert comprising a pair of wear-- resisting flanges for the sides of the groove, each flange comprising a plurality of segments, and means connecting the inner edges of the segments of the two flanges and embedded in the body, said means being flexible to permit circumferential separation of the segments in accordance with the difference in expansion between the body and the insert.

4. A piston comprising a light metal body having a ring groove therein, and a steel insert for the groove, said insert comprising a pair of wearresisting flanges for the sides of the groove, each flange comprising a plurality of segments, means connecting the inner edges of the segments of the two flanges and permitting circumferential separation of the segments, and means extending from the segments and embedded in the body for securing the insert in place in the groove.

5. A piston comprising a light metal body having a ring groove therein, and a steel insert for the groove, said insert comprising a pair of flanges at the sides of the groove, each flange comprising a plurality of segments, and means embedded in said body and connected to the flanges, said means comprising a series of web members connecting the two flanges, and a series of tongue members extending from the flanges into said body, one of said series being flexible and providing for circumferential expansion be-- tween the segments.

6. A piston comprising a light metal body having a ring groove therein, and a steel insert for the groove, said insert comprising a pair of' flanges at the sides of the groove, each flange comprising a plurality of segments, and means embedded in said body and connected to the flanges, said means comprising a series of web members connecting the two flanges, and a series of tongue members extending from the flanges into said body, the web members being arranged alternately with said tongue members.

7. A piston comprising a light metal body having a ring groove therein, and a steel insert for the groove, said insert comprising a pair of flanges at the sides of the groove, each flange comprising a plurality of segments, and means embedded in said body and connected to the flanges, said means comprising a series of web members con- ,6 necting the two flanges, and two series of tongue members extending from the respective flanges into said body, one tongue member of each of said series of tongue members being located between each pair of adjoining web members.

8. A piston comprising a light metal body having a ring groove therein, and a steel insert for the groove, said insert comprising a pair of flanges at the sides of the groove, each flange comprising a plurality of segments, and means embedded in said body and connected to the flanges, said means comprising a series of web members connecting the two flanges, and a series of tongue members extending from the flanges into said body, one of said series connecting the segments circumferentially.

9. A piston comprising a light metal body having a ring groove therein, and a steel insert for the groove, said insert comprising a pair of flanges atthe sides of the groove, each flange comprising a plurality of segments, and means embedded in said body and connected to the flanges, said means comprising a series of web members connecting the two flanges, and two series of tongue members extending axially from the inner portions of the respective flanges into said body.

10. A piston comprising a light metal body having a ring groove therein, and a steel insert for the groove, said insert comprising a strip of sheet steel having transverse shears therein and having bends on longitudinal lines, the strip thereby having a U shape structure comprising two rows of segments positioned at the respective sides of the groove, and web members connecting the two rows, said strip also having longitudinally extending shears connecting pairs of transverse shears to form tongues with the latter bent to extend into the body.

11. A piston comprising a light metal body having a ring groove therein, and a steel insert for the groove, said insert comprising two axially spaced rows of segments positioned at the respective sides of the groove, web members connecting the segments of one row with the segments of the other row and providing for circumferential expansion of the insert, and tongues extending from the segments of both rows between the web members, said tongues being embedded in said body and securing the insert in place.

12. A piston comprising a light metal body having a ring groove therein, and a stee1 insert for the groove, said insert comprising two axially spaced rows of segments positioned at the respective sides of the groove, the segments in one row being-in staggered relation to the segments of the other row, each segment having a pair of web members connected to two segments in the other'row, and a pair of tongues extending from each segment and embedded in. said body.

13. A piston comprising a light metal body .having a ring groove therein, and a steel insert ance with the difference in expansion between the insert and the body.

14. A iston comprising a light metal body having a ring groove therein, and a steel insert for the groove, said insert comprising two axially spaced rows of segments positioned at the respective sides o'f'the groove, web members iconnecting the segments of one row with those of :16. A :steel insert for a ring groove of a light.

metal iston, comprising two aXi-a'lly spaced rows of segments adapted to be positioned at the sides of the groove, web members connecting the segments of the two rows and adapted to be positioned at the back of the groove, and tongues extending axially from two rows of segments and adapted to :be embedded in the piston to hold the insert in the groove.

17. A steel insert for a ring groove of a light metal piston, comprising a strip of sheet steel having transverse shears, the strip thereby having two rows of segments at the respective sides of the strip and connecting web members, said strip also having longitudinal shears connecting pairs of transverse shears to form tongues, said strip having bends on longitudinal lines with the segments and web members forming a U- shaped structure and the tongues extending axially from the sides of the U.

18. A steel insert for a ring groove of a light metal piston, comprising a strip of sheet steel having transverse shears extending alternately from .opposite' edges of the strip, the strip thereby having rows of segments at opposite sides of the strip, the strip also having other transverse shears terminating short of both edges of the strip and located between the first-mentioned shears to form web members connecting the two rows of segments, the last-mentioned shears being connected to certain ofthe'first-mentionedi shears :by longitudinal shears :at the longitudinal center line of the strip to form tongues, the strip having bends on longitudinal lines with the segments and web members forming a U-shaped structure and the tongues extending axially from the sides of the U.

19. A steel insert for a ring groove of a light metal comprising a strip of sheet steel having a series of transverse shears in the central portion of the strip, forming web members, with pairs of said shears connected by longitudinal shears at the longitudinal center-line of the strip thereby forming tongues on opposite sides of said center line, said strip also having transverse shears extending inwardly from the side edges of the strip into said tongues and forming two rows of segments along the respective sides of the strip, said strip having bends on longitudinal lines with the-segments and web members forming a LI-shaped structure and the tongues-extending axially from the sidesof the U.

20. A "steel insert for a ring groove of a light. metal piston, comprising two axially spaced rowsof segments adapted to be positioned at the'sides of the groove, and circumferentially expansible means connecting the segments and including members adapted to be embedded in the piston for holding the insert in place.

References Cited in. the file of this patent UNITED STATES PATENTS Number Name Date 2,278,958 White et al. Apr. '7, 1942 FOREIGN PATENTS Number Country Date 455,539 France May 27, 1913 251,127 Great Britain Apr. '29, 1926 548,400 Great Britain Oct. 8, 1942 OTHER REFERENCES Automotive Industries, November 1, 1951, vol. 105, No. 9, inside back cover.

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