US2046196A - Piston - Google Patents

Description

June 30, 1936. c w TRUXELL JR 2,046,196

PISTON Filed Jan. 19, 1955 Patented June 30, 1936 UNITED STATES PATENT OFFICE PISTON Application January 19, 1935, Serial No. 2,478

4 Claims.

This invention has to do with internal combustion engines and more particularly with the transfer of heat from the piston head to the piston skirt and the dissipation of excess heat.

In the conventional engine, the cylinder wall is provided with water or air cooling means and the heat from the piston is transferred to the cylinder wall through the piston rings and skirt sliding in the cylinder. The piston skirt, therefore, runs comparatively cool while the piston head being directly exposed to the heat of combustion remains quite hot. The resulting troubles from unequal expansion, cooking and sticking of the rings and the like, are well known and appreciated and many efforts to avoid these difiiculties have been made heretofore. These usually are in the nature of special piston designs intended to throw off heat rapidly from the head.

The present invention follows a somewhat similar line of thought but contemplates according to a specific embodiment, the transfer of heat from the head to the skirt through the use of a heat exchanging medium which is thrown into contact with both the skirt and head during engine operation, absorbing heat from the normally hot head for transfer quickly into the normally cool skirt, so that not only is the head cooled but also the temperature of the whole and consequent expansion is maintained substantially uniform throughout.

For this purpose a pocket is provided interiorly of the piston for collecting and dashing a quam tity of engine lubricating oil back and forth against the head and skirt during piston reciprocation. For convenience and economy of manufacture the pocket can be afforded through the use of a separate sheet metal shell fitted into the hollow piston for cooperation with the piston walls and provided near the bottom with one or more bleed holes for the return to the crankcase of oil supplied to the pocket from the engine lubricating system through a discharge nozzle carried by the connecting rod and arranged to throw fresh oil directly against the head. Major cooling will take place through the engine cylinder walls but the returning oil will carry some heat with it for dissipation in the engine lubricating system. In case of excessive oil temperatures a cooler for the oil may be used as a matter of choice and engineering technique, but ordinarily this should not be necessary as most modern engines have a temperature regulator incorporated in the lubricating system.

For a better understanding of the invention, reference may be made to the accompanying drawing wherein Figure 1 is a longitudinal sectional view of an engine cylinder having a piston and connecting rod assembly therein; Figure 2 is a detail perspective view of the sheet metal shell to be fitted into the piston, and Figure 3 is a detail perspective view of the discharge nozzle.

In the drawing the numeral l indicates the wall of an engine cylinder which is provided with a water jacket 2 for cooling purposes. Neither the crankcase nor the cylinder head and combustion chamber are illustrated in the drawing, since they form no part of the present invention. The hollow piston which is reciprocable within the cylinder includes a head 3 and a skirt 4 and is provided with suitable pin bosses 5 to receive the pin 6 by which the upper end of the connecting rod 7 is journaled within the piston. The journal hearing is shown as including two groups of rollers 8 and 9 retained within the opening in the rod by end rings llll keyed or otherwise anchored in place. Lubricating oil under pressure is supplied to the bearing through the passageway II in the shank of the rod and passes around the bearing through a distributing recess l 2. A threaded passageway l3 in the end of the rod communicates with the annular recess I2 and receives a discharge nozzle which is provided with a series of angularly arranged jet openings l for spraying the oil on the underside of the piston head 3. Increased radiating surface is provided by a series of fins I6.

To trap the oil falling from the-head use is made of the hollow shell I! shown in Figure 2 and which may be formed easily from sheet metal. This shell fits over and receives therein the piston pin end of the connecting rod and at the top thereof is provided with an elongated opening l8 to receive the nozzle 14 and accommodate its relative movement with the rocking of the piston rod, which rocking incidentally causes the direction of flow through the jets against the underside of the head 3 to undergo constant change. The opposite side walls IQ of the shell fitting between the piston pin bosses 5 are provided with alined openings 20 for the passage therethrough of the piston pin 6. Near its bottom, the shell flares outwardly as at 2 I, and terminates in an annular rim 22 which has a tight fit against the Wall of the skirt at its lower end. If desired, the rim may be welded or otherwise secured to the skirt.

The pocket thus provided by the shell in cooperation with the skirt will store a quantity of the oil, which acting as a heat exchanging medium, will be agitated during piston action and continuously bathe the wall and skirt surfaces and thus transfer heat quickly from the head to the normally cooler portions of the skirt and tend to maintain the whole at a substantially constant and uniform temperature. One or more drain holes 23 are provided at a suitable height in the shell to enable circulation of oil through the pocket and return of heated OH to the crankcase. Such drain holes 23 are so arranged with respect to the quantity of oil discharged into the pocket through the nozzle l4, that an ample supply is available within the pocket at all times for heat exchange purposes.

That is to say the drain holes pass a lesser amount of oil than is supplied to the pocket so that during operation a body of oil will. be retained within the pocket with the holes insuring circulation. The body of oil, however, does not build up in the pocket beyond as near as can be determined approximately half the volume ofthe pocket for the reason that the oil is continually in motion due to its inertia and piston reciprocation and on being splashed back and forth between the head and skirt a part of the agitated oil pours through the elongated top opening l8. Even in the absence of the drain holes 231 a continuous circulation occurs and the pocket never becomes filled with a dead body of liquid.

I claim:

1. The combination with a hollow piston having a pair of interiorly disposed pin bosses integral therewith and a connecting rod adapted to be journaled on a pin supported by said bosses and provided with a passage for lubricant under pressure, of a cupped baiile member extending into the hollow piston between the pin bosses to receive therein the end of the connecting rod and having its rim engaging the bottom of the piston wall for cooperation with the wall of the piston to provide a cooling pocket adapted to contain a supply of lubricant, said pocket being closed to the outside of the piston by reason of the piston wall being imperforate with regard to the pocket and said pocket being open to the interior of the cuppedbaiile through a discharge opening in the bailie and means for supplying lubricant to the pocket for circulation therethrough including a nozzle carried by the connecting rod in communication with said passage and projected through an elongated opening in the top wall of the cupped baflle.

2. For use with a hollow piston and connectint rod assembly in which a journal pin projecting through the end of the connecting rod is supported by a pair of pin bosses integral with the piston and wherein the journal bearing is supplied 5 with lubricant under pressure through a passageway in the connecting rod, means to provide said piston with a cooling pocket for the circulation of lubricant, including a cupped bame projected into the hollow piston and between the pin bosses 10 to receive the end of the connecting rod therein,

a nozzle mounted on the end of the connecting rod in communication with said passage and extended for oscillation with the rod through an opening in the top of said cupped baflle to direct 15 lubricant against the interior surface of the piston, said baflie at its lower end engaging the wall of the piston for cooperation therewith to entrap lubricant supplied through the nozzle and having a discharge opening therein for the discharge inwardly thereof of lubricant from the pocket.

3. As an article of manufacture, a baflle device to be fitted interiorly of a hollow piston to aiford, in cooperation with the pisto skirt and head, a cooling pocket adapted to con am a body of cool- 2 ing liquid to be splashed back and forth against the head and skirt for the exchange of heat upon piston reciprocation, .said baflie device comprising a cupped member having a rim to engage the bottom of the piston skirt, a skirt provided with a discharge opening adjacent said rim and a top portion to overlie the end of a connecting rod and provided with an entrance opening for cooling liquid discharged from the end of the connecting rod.

, 4. In combination, a reciprocatory piston having a head and a double walled skirt with an imperforate bearing wall cooperating with an inner wall to provide a pocket to contain a body of cool-

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