Патент USA US2114040код для вставки
April 12,1938. V 2,114,040 M. A. BECKMANN EVEN PRESSURE PISTON Filed May 12, 1956 ' 2 Sheets-Sheet 1 v " ’ lNVENTb-R. I z , NEAHOVé/VE A 5:01am” BY '- ' V ~/, A ORNE ~ v‘ l April 12, 1938. ‘ M. A. BECKMANN 2,114,040 EVEN PRESSURE PISTON Filed May 12, 1936 2 Sheets-Sheet 2 Patented Apr. 12, 1938 2,114,040 UNITED STATES PATENT OFFICE 2,114,040 EVEN PRESSURE PISTON Melbourne A. Beckmann, Cincinnati, Ohio, as signor to Aluminum Industries, Incorporated, Cincinnati, Ohio, a corporation of Ohio Application May 12, 1936, Serial No. 79,309 5 Claims. (Cl. 309-11) This invention relates to a piston for internal combustion engines especially those of automo biles, and is especially adapted for those made from aluminum alloys. Other metals may be 5 used however. The general object of the invention is to pro vide a piston that will bear evenly on the cylinder wall at substantially all points of the piston's sur face and at substantially all times and tempera 10 tures. Another'object is to provide a construction in which the flow of heat from one part of the piston to another is unhampered altho a slot in the skirt is provided, which ordinarily would be a bar 'to heat ?ow. Another object is to provide a piston in which the skirt is reinforced against collapse in such a way that the reinforcement has the greatest strength where it is the most needed. Converse 20 ly, the greatest amount of diameter adjustment is obtained where it is most necessary. Another object is to provide a piston which is stabilized against rocking. Brie?y stated, the invention resides in the com grinding of the piston is exaggerated for purposes of illustration. Fig. 3 is a transverse sectional view taken along‘ the line 3-3 of Fig. 1. Fig. 4 is an elevation of that side of the piston on which the slot and bridge are located. As shown, i0 is the hollow head, H the skirt of the piston and I2 the usual ring grooves. Below the grooves. 90° away from the pin bosses l3 there is a T-slot comprising a short horizontal slot I4 . g and a relatively longer, slightly slanted, almost vertical slot l5. The pin bosses have the usual. hole l8. Straddling the slot l5 there is‘a hairpin bridge I6 which extends vertically from a point just under the head Hi to a distance of 1/4" to %” 5 from the bottom of the skirt on an ordinary passenger automobile piston. At the top, the bridge is considerably narrower than at the bot tom, altho its angle of dehiscence remains the same. This implies that the back ridge ll of the 20 bridge is not vertical and in fact, it slants toward the lower part of the vertical middle axis of the piston. The bridge is cast integrally with the p‘ston. It is cut by the slot M which severs the tip from the skirt portion. The upper tip 2 a “hairpin” or segment-enclosing bridge or gusset upper is solid. ' across the slot, the bridge being integral with the , By the hairpin bridge I mean a bridge having a piston body. The height of the hairpin bridge increases progressively toward the bottom of the cross-section shaped‘like the connecting portion 25 bination'of a cam ground slotted skirt piston with 30 skirt so as to obtain a gusset function of progres sive rigidity, increasing toward the piston head. Last but not least, an object of the invention is to provide these advantages in a form that will be commercially successful because it is well adapted to production by the permanent mold process. - Heretofore it has been attempted to reinforce the skirts of slotted ‘pistons with steel springs of various shapes, commonly called “expanders”. 40 These‘ press the skirt against the cylinder wall between the two arms of a conventional hairpin. ‘ The angle of dehiscence of the bridge from its ridge to the skirt is preferably 15 degrees (in cluded angle) but may range from 10° to 50°. When a 15° angle is employed, the piston is cam ground as shown in Figs. 2 and 3. That is to say, 1 the diameter thru the pin bosses is from three to ten thousandths of an inch shorter than the di ameter at 90 degrees to said pin boss. This grind— ing is employed because the piston has a greater expansion along the pin bosses than in a direction l when the piston is cold, making starting dii?cult 90° from them. and when the piston becomes hot they do not cam-grinding per se', but in combination with the No originality is claimed for promote even heat'distribution in an aluminum ‘ bridge. even pressure on the cylinder walls is pro duced over the entire piston. which is not the piston because their heat conductivity is so much less than that of aluminum. My reinforcement has no spring action nor does it diminish heat ?ow, yet it strengthens the skirt and holds it in proper working position. 'Because the skirt is so held, the piston has less tendency to rock. In the drawings, Fig. 1 is an elevation, partly in section, of my piston, the sectional part being case with a cam-ground piston that lacks my . bridge. On the other hand my bridge on a round piston produces a result that in certain cases eliminates the need for a cam-grinding to‘ obtain substantially even pressure. Such construction is disclosed in my co-pending application Serial No. 79,310 ?led May 12, 1936. Nevertheless, 'it taken along the vertical part of the slot. lies within the scope of the present invention to Fig. 2 is a plan view of the piston with portions employ the bridge of increasing height herein dis of the piston head broken away and the bridge‘ closed on a round piston because a round piston and pin bosses shown in dotted line. The cam even with no special features except the bridge 4 2 Cl 2,114,040 and slot, will give better results than any round It is of course, necessary to adopt different piston without them or with only a slot. In operation the superior e?'ects occur as will now be described in the case of the construction clearances in cam-grinding when an alloy of a shown, applied to an automobile piston 31/2" di ameter by 4" long. This piston is cam-ground to six thousandths diameter differential and has a 15° bridge. The piston alloy runs: - Per cent 10 Copper ________________________ __ 0.5 to 1.5 Silicon _________________________ __ 12.5 to 14.5v Magnesium ____________________ __ 0.75 to Iron ____________ __, ________ _.______ 1.00 Nickel _________________________ __ 2.00 to Zinc ___________________________ __ 1.05 Manganese ____________________ __ 0.05 Aluminum.a ___________________ __ 1.00 3.00 Balance This alloy has a coe?icient of expansion of 0.000011 inch per inch per degree Fahrenheit up to 500° Fahrenheit. As the engine heats, the piston expands on both diametrical axes simultaneously and reaches even pressure in both directions simultaneously. The bridge has no tendency to push the skirt against the cylinder wall as occurs in the case of steel expanders, since the bridge is made of the same metal as the skirt. A steel spring expander makes an engine hard to start and this is not the different coe?‘icient of expansion is used than the one mentioned. This is however, a matter that any competent piston designer can solve if he is acquainted with the principles herein disclosed. The operating temperatures in the engine also have some eifect but the principles are operative up to the incipient fusing points of the metals employed. 10 In the construction here shown it is easy to pull out the iron core used in the permanent mold to make the hairpin bridge hollow. This is be cause of ample draft since the bottom of the core is smaller than the top. The facility of produc ing the entire piston by the permanent mold pro cess is shown‘ in my co-pending application Se rial No. 85,946, ?led June 18, 1936. No machin ing of the bridge is required. 20 I claim as my invention:— 1. A piston for internal combustion engines which comprises a head, a skirt attached thereto, piston pin bosses within said skirt, a T slot in said skirt at substantially 90° from the axis of said bosses and an integral hairpin bridge adapt 25 ed to act as a gusset, said bridge joining the ends of the skirt across said slot, the height of said bridge increasing progressively toward the bot tom of the skirt. case with my bridge because it does not act as a 2. A piston for internal combustion engines 30 spring, but as a gusset. Some steel expanders which comprises a head, a skirt attached thereto, interrupt heat ?ow. The function of my bridge . a pair of piston pin bosses within said skirt,,a is to stabilize the piston and to keep the skirt T slot in said skirt at substantially 90° from the from collapsing. In an automobile engine, the axis of said bosses, an integral hairpin bridge greatest pressure on the piston is exerted on that adapted to act as a gusset, said bridge joining the 35 side which is on the right from the driver's seat. ends of the skirt across said slot having an angle That is the side here shown uncut vertically and experience has shown that it is the side which should so remain. The opposite side therefore is the one which should have the function of adjust '40 ing itself to the cylinder and this is the one se lected for my bridge. As is well known, the head of a'piston is the end which grows hottest in use. Since the skirt does not grow so hot, it is necessary to have small er clearances at the bottom of the skirt when the piston is put into service, than would be necessary if the piston attained the same heat all the way down. In the present invention, close attention need be paid only to head clearances because the‘ skirt will adjust itself. This is because the bridge 16 is progressively higher at the bottom of the skirt than at the top. Consequently, the skirt can be more easily compressed at the bottom while at the top it is held with greater rigidity against heat expansion. 1 The net result is that a piston built according to this invention adapts itself according to its temperature to bear on the cylinder walls with substantially equal pressure top and bottom, left and right. The bridge limits the "accordion” ac tion of the split skirt, thereby avoiding metal fatigue due to long repeated bending during op eration. At the same time, a close enough ?t of the skirt in the cylinder is maintained so that the pis ton has little or no tendency to rock’end for end. This is what'I call stabilizing action. The clear ance is always substantially the same, hot or cold in a diametrical direction across the piston pin axis. When the piston heats in operation, the diameter along the piston pin axis becomes the same as the diameter across it. So the piston is entirely round when hot due to practically com plete closing of slot l5 but both stabilized and reinforced whether hot or cold. ' of dehiscence of about 15° and increasing in height toward the bottom of the skirt. 3. A piston for internal combustion engines which comprises a head, a skirt attached there 40 to and a pair of pin bosses within the skirt; said piston being from 3 to 10 thousandths of an inch shorter across that diameter which coincides with the piston pin boss axis than that diameter which lies at 90° therefrom, a-T slot in said skirt 90° 45 from the axis of said bosses and an integral hair pin bridge joining the ends of said skirt across said slot the height of said bridge increasing to ward the bottom of the skirt. 4. A piston for internal combustion engines 50 which comprises a head, a skirt attached‘ thereto and a pair of pin bosses within the skirt, said piston being from 3 to 10 thousandths of an inch shorter across that diameter which coincides with the piston pin boss axis than that diameter 55 which lies at 90° therefrom, a T slot in said skirt 90° from the axis of said bosses and an integral hairpin bridge joining the ends of said skirt across said slot the height of said bridge increas ing toward the bottom of the skirt, the metal of 60 the piston having a coefficient of expansion of substantially 0.000011 inch per inch per degree Fahrenheit. ‘ 5. A piston for internal combustion engines which comprises a head, a skirt attached there 65 to, piston pin bosses in said skirt, a T-slot in said skirt at substantially 90° from the axis of said bosses and an integral bridge acting as a gus set and joining the ends of a skirt across said slot, said bridge comprising relatively thin and rela 70 tively high walls converging at a dihedral angle in the vicinity of 15° to a rounded connecting por tion, and said bridge increasing in height toward the bottom‘ of the skirt. MELBOURNE A. BECKMANN.