US3014771A

US3014771A - Pistons

Info

Publication number: US3014771A
Application number: US736789A
Authority: US
Inventors: William M Nichols
Original assignee: Alco Products Inc
Current assignee: Alco Products Inc
Priority date: 1958-05-21
Filing date: 1958-05-21
Publication date: 1961-12-26
Anticipated expiration: 1978-12-26

Description

Dec. 26, 1961 w. M. NICHOLS PISTONS Filed May 21, 1958 FlG.6

INVENTOR.

WILLIAM M- NIC HOLS ATTORNEY United Stats 3,014,771 PISTONS William M. Nichols, Schenectady, N.Y., assignor to Alco Products, Incorporated, New York, N.Y., a corporation of New York Filed May 21, 1958, Ser. No. 736,789 Claims. (Cl. 309-14) This invention relates to pistons for internal combustion engines and particularly to heavy duty diesel engine pistons of the class in which a piston body of light alloy is equipped with a ring carrying insert of heavy wear resistant material such as iron.

A serious problem arises in the case of light bodyheavy ring insert combinations in a piston because of the disparity of thermal expansion between the aluminum of the piston body and the ferrous alloy of the carrier. As a result of such unequal expansion, the piston ring carriers work loose and damage is caused to the piston and cylinders. Nickel or the like has been added to the ferrous alloy of the insert so that its coeflicient of thermal expansion will match or closely match the coefiicient of the piston aluminum alloy. But, even with such an expedient, it has been found that there is still a difference in the thermal coeflicients to cause minute upsetting of the aluminum alloy of the base when it grows against the restraining ferrous hand during the heating cycle. Such upsetting results in a looseness of the insert in relation to the piston body.

Molecular bonding of the ferrous alloy insert to the aluminum alloy piston has also been tried as a solution to the problem. This has been accomplished by coating the insert with a thin film of molten aluminum overlying a ferro-aluminum alloy layer at the interface and then, while the surface film is maintained at a temperature sufiicient to keep it molten or plastic, placing the carrier in a permanent mold and casting the aluminum alloy body around it. A fusion union is thus created between the plastic film on the insert and the molten casting metal; and it has been found that a union so formed is strong enough to hold the parts in proper relation during engine operation. The piston body however, is thus limited to a casting and castings have disadvantageous characteristics on heavy duty operations.

The principal object of the invention, therefore, is to provide a piston for an internal combustion engine hav ing a body of light material such as an aluminum alloy, and an insert which includes a durable wear resistant material such as a ferrous alloy, the combination having a novel arrangement such that the insert will not work loose from the body under operating conditions. An-

other object is to provide such a piston which will have a body of an aluminum or light alloy and an insert which includes a durable wear resistant material formed as a weld deposited in an annular receiving groove in the piston body. Another object is to provide such a piston which includes an insert in the form of a weld which has a matrix of an aluminum alloy molecularly bonded to the aluminum alloy of the piston body, the weld having particles of iron or the like dispersed throughout the matrix to provide it with desired wearability. Another object is to provide such a piston having a body of an aluminum or light alloy and a ring insert formed as a weld deposited in an annular receiving groove in the piston body, the weld consisting of a composition having a matrix of the same alloy as contained in the piston body and ferrous alloy or other wear resistant particles dispersed throughout the matrix to provide the composition with desired hardness and wearability.

In the drawings, FIG. 1 shows a portion of a piston having a plurality of ring grooves, the top groove being formed in the periphery of an insert deposited as a weld Patented Dec. 26 196i in an annular recess in the piston body. In FIG, 2 the piston is of the oil cooled type with a band shrunk on to the piston body, the ring grooves being formed in the band and the top groove being located in an insert in the form of a weld. In FIGS. 3, 4, 5, and 6, the steps in the formation of the top groove are illustrated; FIG. 3 showing the portion of the piston with the weld recess formed therein, FIG. 5 showing the weld deposit machined 0E flush with the outer wall of the piston, and FIG. 6 showing the weld with the ring groove machined therein.

Referring now to the drawings, numeral 10 indicates the body of a piston of an internal combustion engine; It is of a light alloy composition, such as an aluminum alloy. Conventional ring grooves 11 are formed in the body wall for the reception of compression rings of a heavy durable material such as a ferrous alloy. Such combinations of a light alloy piston body and a heavy durable compression ring are well known in the diesel engine field. As here illustrated, piston body 10 is provided with a recess 12 adjacent its top face. Within recess 12 a weld is deposited thus forming insert 13 having particles 14 of a Wear resistant metal dispersed therein, such particles 14 providing a wearing surface for top I ring groove 15 machined in insert 13. The weld may be deposited by gas welding or by electric arc welding with a filler rod having a matrix of an alloy that will bond securely to the material of the body. In the case of an aluminum alloy piston, the rod matrix is a'related aluminum alloy. Mixed into the matrix is even dispersion are particles 14 of a hard durable material such as a ferrous alloy. Desired durability is imparted to the weld by the ferrous or other suitable particles. The machining of the groove 15 into the weld can be done by conventional means.

In FIG. 2 the piston is of the oil cooled type in which a passage 16 transmits cooling oil through the piston body from the lubricating system of the engine. For convenience in manufacture, the piston body 10 is fabricated with an annular recess 17 at its upper end with the oil cooling passage 16 open at the peripheral surface of the body. An annular band 10a is shrunk on to the body to close the oil passage. In the construction shown, the band 10a is slotted adjacent its top face so that the top cooling passage 18 is located closer to vertical alignment with the ring grooves for more effective cooling. In such a construction the piston body may be cast or forged and the band may be forged.

The term piston body or body portion is intended to include not only body 10 as illustrated in FIG. 1 but also body 10 and band 10a as illustrated in FIG. 2.

While there has been hereinbefore described an approved embodiment of this invention, it will be understood that many and various changes and modifications may be made without departing from the spirit of the invention, and that all such changes and modifications as fall withinthe scope of the appended claims are contemplated as a part of this invention.

What I claim is:

1. A piston for an internal combustion engine comprising a cylindrical body portion of a light metal alloy of relatively low strength, said body portion having an annular recess adjacent its top face; a weld in the recess having a matrix of an alloy bondable to the alloy of the body portion and particles of a heavier metal alloy dispersed throughout the matrix; and recess means in the periphery of the weld adapted to carry a compression ring.

2. A piston for an internal combustion engine comprising a cylindrical body portion of an aluminum alloy, said body portion having an annular recess adjacent its top face; a weld in said recess, said weld having a matrix of aluminum. alloy and particles of ferrous alloy dispersed throughout the matrix, and recess means inthe periphery of the weld adapted to carry a compression ring. I

3. A piston for an internal combustion engine comprising a cylindrical body portion of a relatively low strength light metal alloy of the class consisting of alumimum and aluminum alloys, said body having an annular recess adjacent its top face; a weld in said recess, said weld having a matrix of light metal of the class consisting of aluminum and aluminum alloys and particles of ferrous alloy dispersed throughout the matrix; and recess means in the periphery of the Weld adapted to carry a compression ring.

4. A piston, according to claim. 3, in which the ferrous alloy particles comprise substantially 25 of the surface of the recess means.

5. A ring carrier for a piston comprising a band 4? band and particles of a heavier metal alloy dispersed throughout the matrix, and recess means in the periphery of the Weld adapted to carry a compression ring.

References Cited in the tile of this patent UNITED STATES PATENTS 2,818,841 Nichols Jan. 7, 1958 OTHER REFERENCES Diesel Power, vol. No. 33, Issue No. 4 pages 54-55,

adapted to be secured to the upper portion of a piston, bli April 1955 an annular groove in said band, a weld in the groove having a matrix of an alloy bondable to the alloy of the