US1791280A - Internal-combustion engine - Google Patents

Description

Feb. 3, 1931. MQQRHQUSE 1,791,280

INTERNAL COMBUSTION ENGINE Filed Jan. '7, 1929 gwuwntoz Flu-"n31: MEJDHHUUSE.

Patented Feb. 3, 1931 ALFRED MOORHOUSE, OF DETROIT, MICHIGAN, ASSIGNOR T PACKARD MOTOR CAR COMPANY, OF DETROIT, MICHIGAN,

A CORPORATION 0 1 MICHIGAN INTERNAL-COMBUSTION ENGINE Application filed January 7, 1929. Serial No. 330,741. v

This invention relates to internal combus-.

tion engines and more particularly to the pistons used therein. I

In order to reduce the reciprocating mass 5 and improve the performance of such engines and particularly of engines used to propel motor vehicles and aircraft, it is common practice to employ pistons composed of light metals or metal alloys, such as aluminum and compositions of aluminum.- On the other hand the cylinders of such engines are usually made of iron or steel, or arelined with suc metals, and these metals-expand under heat much more slowly than aluminum, so that the 1 use of the lighter alloy pistons has been attended with certain difficulties in manufacture and operation. One of the principal difficulties is that if such an aluminum piston is a good fit in its cylinder when cold, it will ex-.

pand sufliciently to stick in the cylinder when thoroughly warmed up from operation of the engine. For this reason such pistons are usually made a good fit at the higher engine temperatures, and consequently when operat-,

ing at the lower engine temperatures they are loose and noisy, and subject to all the disadvantages of poorly fitted pistons; Moreover, such light pistons are relatively soft and are therefore easily scratched and scufi'ed.

One of the objects of this invention is to provide a piston which will obviate these difficulties and which shall secure the advantages of lightness of the aluminum piston to gether with the closer fit and bettenwearmg qualities of pistons made of cast 1ron an other harder materials.

Another object of the invention is to provide a piston having a body of light metal which shall operate at all times out of contact with the cylinder wall, the contact andv wear of the cylinder wall being taken by wearing elements or shoes ofa material having a rate of expansion closer to that of the cylinder block than therate of expansion of the piston.

' Other objects of the invention will appear from the following description taken in connection with the drawings, which form a part of this specification, and in which:

\ Fig. 1 is a view in vertical section through a piston constructed in accordance with this invention, taken on planes at right angles as indicated by the line 11 of Fig. 2;

. Fig. 2 is a transverse sectional view, the sections being taken in diiferent planes as indicated by the line 2-2 of Fig. 1, and

Fig. .3 is a perspective view of the spacing means for the ends of the shoes. 1

Referring to the drawing, the piston consists of a shell or body 10 of generally cylindrical shape, closed at one end by an integral head 11. This head lland body portion 10 are preferably formed of aluminum, or any of the well known aluminum alloys, in any convement manner, usually by casting. It is provided with the usual bosses 12 in Which are formed aligned holes 13 for the reception of the piston pin (not shown) by which the piston is operatively secured to the connecting rod of the engine in the well known manner. The bosses 12 may be provided with any suitable means for retainlng the piston pin, such as grooves 14 near the ends of the holes 13, for the reception of a locking ring, not shown in this drawing. The bosses.12 may also be provided with conduits 16 by which lubricant may be conducted from the interior of the piston into'the piston pin bearing.

Above the pin bosses 12 the body of the piston is provided With a number of circumferential grooves 17 for the reception of the usual piston rings 18, which vare adapted to provide a sliding seal between the piston and the cylinder wall to retain the cylinder compression and to prevent the passage of lubricating oil in the well known manner. One or more of these rings maybe provided with scraping edges to remove excess oil from the cylinder wall as will be readily understood. As construction of this nature is well known inthe art to which this invention relates, further description thereof is unnecessary.

In the present invention the piston body 10 is intended to operate at all times out of contact with the cylinder wall, and for this purpose it is formed of a diameter somewhat less than the bore of the cylinder, so that when fully expanded under its maximum temperature. it will not. touch the cylinder at any point. To properly guide the piston in body 10.

' its reciprocating motion in the cylinder, and

to prevent undue wear, suitable wearing membus or shoes are carried by the piston body tion thereof being adapted to slide in contact with the cylinder wall to guide the piston and to take the wear. These shoes 22 are preferably formed of material having a rate of expansion no greater than the rate of expansion of the cylinder block and preferably much less. A material suitable for this purpose, consisting of an alloy of iron and nickel, is well known under the name of invar steel, and has a coefficient of expansion considerably less than the coefficient of expansion of iron and steel.

To take the axial thrust of the piston body 10 on the shoes 22, the body is provided with spaced circumferential grooves 24 arranged' in pairs above .and below the pin boss 12, and preferably near the upper and lower ends of the piston respectively- These grooves 24 are adapted to receive the flanges 26 of the channel shaped section respectively, the upper flange of each pair being a relatively close fit with its corresponding flange 26, while the a lower groove is wider than its cooperating flange to provide for axial expansion and contlraction of the body 10 with respect to the s me.

Each of the shoes 22 forms a nearly complete semi-circular segment so that each pair of these shoes constitutes a nearly complete bearing ring for the piston. The ends of the segmental shoes 22 are spaced in any suitable manner, but preferably by means of T-shaped spacing members 27 as illustrated. These members comprise a T-head of sub-- stantially rectangular section disposed between the upper and lower grooves 24 of each pair and adapted toseparate the adjacent ends of the semi-circular segments 22. These spacing members are provided with integral shank portions 28 adapted to seat in suitable holes 29 In assembling these pistons in an engine, the shoes 22 are placed in position in their respective grooves 26. The shanks 28 are inserted in the holes 29 until the head por-, tions of the spacers 2'? are located between the ends of the shoes, and in this condition the piston is inserted into its cylinder. After insertion in the cylinder radial movement of the shoes and the spacer members is limited by the cylinder wall which thus acts to retain all the parts in position.

It will be observed that the only portions of the piston assembly in operative contact with the cylinder wall. at any time are the outer surfaces 23 of the shoes 22, and the outer wearing surfaces of the piston ring 18. As

provided in lugs 31 on the piston meaaao these members are relatively small they add but little to the total massof the piston. Atthe same time by reason of the slight expansion of the shoe members 22, all danger of sticking or binding of these wearing elements in the cylinder bore is obviated, while relative movement is permitted between the flanges 26 and the grooves 24, to accomodate the expansion of the light metal piston body 10.

While a specific embodiment of the invention has been herein described, which is deemed to be. new and advantageous and may 7.

be specifically claimed, it is not to be understood that the invention is limited to the exact details of the construction, as it will be apparent that changes may be. made, therein. without departing from the spirit or scope of the invention.

Having thus described the invention, What is claimed and desired to be secured by Letters Patent is:

1. A. pistonfor internal combustion engine comprising a body of light expansible alloy of less diameter than the engine cylinder, and segmental metallic shoes having a rate of expansion less than that of the engine cylinder, supported. on said body at the upper and lower edges thereof. I

2. A piston comprising an integral head and body portion of'light metallic alloy of less diameter than the cylinder bore to opcrate out of contact with the cylinder wall, wearing shoes of less expansibility than the cylinder walls comprising channel shaped segments carried by the body portion and engaging the cylinder walls, and means circumferentially spacing said segments.

mg grooves and adapted to operate out of contact with its cylinder wall, segmental shoe members slidable on the cylinder Wall and having flanges adapted to seat in said grooves, and means carried by said piston to space the ends of said segments.

4:. A piston comprising a body portion having grooves and adapted to operate out of contact with its cylinder wall, segmental shoe members slidable on the cylinder wall and having flanges adapted to seat in said grooves, and means including T-shaped members having shanks carried by the body portion and having heads spacing the ends of the segments.

5. A piston comprising a head portion and an integral body portion adapted to support a piston pin, of substantially ineapansible ALFRED lltIUQlPLHUUSl-E.

title" ice 3. A piston comprising a body portion havlllli llitl

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