JPS61175256A - Oil cooling type piston for reciprocating piston internal combustion engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention consists of a piston upper part consisting of an outer wall with a piston ring inserted in a ring groove and a piston head, and a piston 5/lower part, and FL k oil. A cooled piston, which is connected to the crankshaft of a reciprocating piston internal combustion engine via a piston pin attached to a support hole that passes laterally through the piston pin support part in the lower part of the piston ('c). Pivotally attached to the connecting ring: 16,
The upper part of the piston is a stepped support surface from the piston head, and is supported by the end face of an annular support collar integrally molded on the upper part of the piston pin support, and is connected to the lower part of the piston through a cylindrical center positioning surface. On the other hand, the center is positioned by a center positioning surface provided at the lower part of the piston, and is connected to the piston 71 using a plurality of tightening screws. A projection is arranged which is pierced by a central cooling oil passage hole coaxial with the longitudinal axis of the piston, and which projects into the area of the upper part of the piston and whose upper edge The cooling oil filling state of the internal cooling chamber is limited by the A7 state, in which the internal cooling chamber is limited in its lower range by the inner surface of the support collar, the upper side of the piston pin support and the outer surface of the protrusion, and in its upper range by the upper part of the piston. By the recessed part in? ! i11 is limited to 1. The piston is connected to an external cooling chamber, and the external cooling chamber extends around the support collar at the piston upper part and the piston lower part 1.

Prior Art and Disadvantages An oil-cooled piston of this type is known from DE 15 26 598 A1. In this known piston, the lower part of the piston is made of aluminum, whereas the upper part of the piston is made of steel. I sostons such as 1- are not suitable for very high ignition pressures, especially because of the piston lower part made of aluminum. Na Senaraha,
In this case, the lower part of the piston deforms significantly under the action of the ignition pressure, which may cause the piston to become stuck. This drawback can be eliminated by giving the lower part of the piston a suitable elliptical and spherical shape, so that it can absorb all the deformations caused by the action of the ignition pressure. However, the deformation that occurs in the lower part of the piston having the 1c structure has an adverse effect on the consumption of lubricating oil.

This is because the circumferential surface of the lower part of the piston has a non-circular shape, so more lubricating oil than is necessary will be present at certain points on the inner surface of the cylinder.1. As a result, in the published 1-'llll sumi, there are many 1st meeting rings? However, the function of these three oil rings is limited due to extremely high wear.Furthermore, this type of cooling oil flow from the outside to the inside in this known piston is also not economical. This is not possible because a piston pin with a complicated structure is required to supply cooling oil.This piston pin requires multiple horizontal holes and vertical holes to supply one cooling oil. Due to its supporting capacity, the piston pin is not suitable for high ignition pressures.

OBJECTS OF THE INVENTION 1. The object of the invention is to improve a piston of the type mentioned at the outset as described below. That is, the piston deforms its shape very little even under the action of high ignition pressure, and in this case especially the piston ring part at the top of the male piston has its circular iJ shape k + i:1 and 1? This is achieved by completely avoiding the ovalization of the lower region relative to the upper region under the piston; in addition, the cooling oil guide of the piston reduces the oil consumption, which is especially used to optimize the working of the cooling oil flowing through it. in favor of
Furthermore, the piston avoids a large number of lubricating oil scraping rings and allows an advantageous lubricating oil adjustment even at a given low lubricating oil consumption, making the piston indispensable for lubricating oil. It is possible to provide stronger lubrication at circumferential locations, for example, on the inner surface of the cylinder within the range of the pressure force I and the counterpressure law of the piston, than at other circumferential locations of the piston.

Problem'(r fl'f) The decisive means part is made of spheroidal graphite cast iron or steel, and the lower part of the piston is made of gray cast iron or spheroidal graphite cast iron.
The piston is configured for shaker cooling, and has a cooling oil supply path for supplying cooling oil from the connecting rod to the internal cooling chamber through the cooling oil through hole 3'r, and from the communicating hole to the external cooling chamber and from the external cooling chamber. The internal cooling chamber is formed by a dome-shaped hollow chamber, and has a cooling oil return passage that returns cooling oil to the crank chamber via an outlet.
The radially outer side of the hollow chamber is shaped by the curved shape (12) of the inner wall of the support collar, then by the continuous curved shape of the inner surface of the piston upper part, and finally by the continuous curve of the inner surface of the IC piston bed. The piston pin support in the lower part of the piston is likewise constructed in the form of a dome-shaped, substantially hollow spherical section-like hemispherical roof, exhibiting an approximately circular outer contour, and has an articulation in the interior of the lower part of the piston. It slightly surrounds the small end of the rod and has bearing eyes on each side of the small end of the connecting rod for receiving the protruding piston pin ends, and the upper part of the domed piston pin support. An annular support collar disposed on the end face 1 supports the upper part of the t-stone (which rests on the annular support surface) in an area where no bending occurs in the upper part of the piston, and facilitates the assembly of the piston pin. The circumferential area of the lower edge of the lower part of the piston, which is located in the lower area when viewed in the axial direction of the notch in the outer wall that allows oil cutting, is configured at an acute angle as an oil cutter, whereas the lower part of the piston The remaining circumferential area of the lower edge of the piston in the region of the lower and counter-pressure side of the piston is chamfered or rounded as an oil-carrying surface 1'1.

Operation and Effects of the Invention Since the upper part of the piston is made of spheroidal graphite, cast iron or iron, whereas the lower part of the piston is made of gray hammer iron or spheroidal graphite cast iron, the piston according to the invention can already be made of spheroidal graphite or cast iron. Able to withstand extremely high loads applied during operation. Furthermore, the ignition pressure acting on the piston during operation is addressed by the dome-shaped configuration of the piston pin support, by the special type of support of the upper part of the piston in the lower part of the piston, and by the fact that the internal cooling chamber is likewise limited to the dome. That's helpful. Not only is a very advantageous cooling effect achieved by the type of cooling oil guide in the piston according to the invention, but also a particularly advantageous distribution of the communication holes connecting the internal and external cooling chambers By arranging these communication holes in an appropriate number, size, and inclination at different intervals, it is possible to have an advantageous effect on the uneven temperature distribution acting in the upper part of the piston. This allows non-uniform deformation of the piston head in the radial direction.This means that the upper part of the piston is supported within the area where the upper part of the piston does not bend as in the present invention. Together with this, it helps the outer wall of the upper part of the piston to maintain its circular shape even under the influence of thermal and mechanical loads.

Furthermore, because the F hoe at the bottom of the piston is constructed as in the present invention, lubricating oil is always present in the cylinder wall in sufficient quantity on the pressure side and the anti-pressure side of the piston, whereas the In the remaining circumferential region of the piston where strong lubrication is not required, lubricating oil is scraped off from the inner surface of the cylinder during one stroke of the piston.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The oil-cooled piston shown in the drawings consists of a lower piston, generally designated 1, and an upper piston, generally designated 2. The integral piston upper part 2 has an outer wall 4 with a cylindrical outer surface 5 and a plurality of ring grooves into which piston rings 6 are inserted, and a piston head 3.
It has In the piston according to the first embodiment shown in FIGS. 1 to 6, the outer wall 4 of the piston upper part 2 has a thick wall section 7 adjoining the piston head 3 and a wall thin wall section 7 adjoining the lower edge of this wall section 7. It consists of a wall portion 9. lower edge 8
An undercut 10 with a cylindrical central positioning surface 11 and a supporting surface 12 located perpendicularly to the piston axis is integrally molded into the wall section I of the wall thickness of the outer wall 4 starting from . The piston upper part 2 is supported by the support surface 12 on the outer end surface 13 of the support collar 14 .
4 is integrally molded on the upper side of a piston support portion 15 that forms a part of the piston lower portion 1. In this embodiment, the piston upper part 2 is centered relative to the piston lower part 1 via a cylindrical centering surface 11 on a cylindrical centering surface 16 integrally molded on the upper part of the support collar 4. There is.

On the other hand, in the piston shown in FIG. 4, a support collar 11 is integrally molded inside the piston head 3 and projects in the axial direction. The piston upper part 2 is supported on the end face 13 of the support collar 14 on the support surface 18, which stands at right angles to the upper part 7. The piston lower part 1 is supported on the upper edge 20 of the outer wall 21 of the piston lower part 1. In this case, the piston upper part 2 has a centering collar 2 projecting from the upper edge 20.
3, by a cylindrical outer surface 22 arranged concentrically with respect to the longitudinal axis of the piston, in which the outer wall 4 of the piston upper part 2 is centered by a cylindrical inner surface 22 in its lower region. Contacted at 24.

The piston upper part 2 is usually fastened to the piston lower part 1 by means of a plurality of tightening screws 25, which are shown only in dash-dotted lines in the figure.

The piston pin, designated 26, is mounted in a bearing hole 27 which passes laterally through the piston pin support 15 in the piston lower part 1. A 1D bearing sleeve 28 is fitted over the piston pin 26 and is supported between fastening surfaces 29, 30, 31, 32 parallel to the longitudinal axis of the piston. The piston is connected via a piston pin 20 and a bearing sleeve 28 fitted over the piston pin to a connecting rod 33 connected to a crankshaft (not shown) of a former ash-driven internal combustion engine, at the small end 34 of the connecting rod. The connection is made via a receiving hole 35 which passes laterally through the connecting rod end 34 and which surrounds the bearing sleeve 28.

The protruding portion indicated by the reference numeral 36 is the piston pin support portion 15.
It is disposed on the upper side 3γ, and is entirely constructed integrally with the piston pin support portion 15 as shown in FIGS. 1 to 6, or as shown in FIG. 4. It may be configured integrally with the piston pin support portion 15 only at the lower portion. In the latter case, the upper part of the protrusion 36 would be formed by the tubular mounting body 3B. These protruding parts (33, 38) are the piston pin support part 1.
5, it is penetrated by a central cooling oil flow hole 39 which is concentric with the longitudinal axis of the piston (arranged C).

The projection (33, 3g) normally projects into the area of the piston upper part 2 and with its upper edge 40 limits the cooling oil filling of the internal cooling chamber, designated as a whole by 41. The internal cooling chamber 41 has a lower area ([
, and by the upper side 37 of the piston pin support 15 and the outer surface 43 of the projection (36, 38), and in its upper region by four sections in the piston upper part 2.

This internal cooling chamber 41 is connected to an external cooling chamber generally designated by the reference numeral 45 via an oblique communication hole 44 formed in the piston upper portion 2.

This external wear-retaining chamber 45 extends around the supporting collar 14 for the piston upper part 2 and the piston lower part 1.

The piston upper part 2 is integrally constructed from spheroidal graphite cast iron or spheroidal graphite cast iron, whereas the piston lower part 3 is likewise integrally constructed from gray iron or spheroidal graphite cast iron.

The piston is configured for a special type of shaker cooling. That is, in this case, the cooling oil flows from the supply hole 4G of the connecting rod 33, the annular passage 47 around the bearing sleeve 28, and the spout hole 48 of the small end 34 of the connecting rod, to the cooling oil through hole 39.
It is supplied to the internal cooling chamber 41 via. From this internal cooling chamber 41, the cooling oil reaches the external cooling chamber 45 via a communication hole 44 due to the piston movement during operation, and from there again via an outlet 49 arranged in the lower region of the external cooling chamber 45. Return to the crank chamber of the reciprocating piston internal combustion engine.

The internal cooling chamber 41 is formed by a dome-shaped hollow chamber which, by virtue of the curved shape of the inner wall 42 of the radially outer supporting collar 14, is then formed by the piston shown in FIGS. 1 to 6. By the continuous curved shaping of the inner surface 50 of the wall portion 7 of the wall thickness of the outer wall 4 of the piston upper part 2 or, in the piston shown in FIG. 4, by the continuous curved shaping of the inner surface 51 of the support collar 17. , and then by a continuous curvature i]'Ii of the inner surface 52 of the piston spatula V3. On the inner surface 52 of the piston head 3 coaxially with respect to the longitudinal axis of the piston,
A ridge 53 is provided, which serves for a better introduction and distribution of cooling oil into the internal cooling chamber 41 .

In the piston shown in FIGS. 1 to 6, the external cooling chamber 45
are formed integrally with the outer wall 4 starting from the lower edge 8 of the wall thickness wall portion 7 of the outer wall 4 and are distributed over the entire circumference in the range of the upper part 2 of the piston, from the position 1 to the lower edge 8 of the wall thickness wall portion 7 of the outer wall 4, somewhat obliquely to the longitudinal axis of the piston. It is formed by a plurality of blind holes 54 and an annular chamber 55 into which these blind holes 54 open.

A communication hole 44 opens in each blind hole 54, and this communication hole 44 branches from the internal cooling chamber 41 at an inward direction 50 range +249 of the wall portion 7 of the wall thickness, and extends diagonally from the upper part of the wall thickness to the corresponding blind hole. 54 and opens near the closed end of the blind hole.

The annular chamber 55 is radially supported on the supinated side by the inner surface 56 of the thin-walled portion 9 of the outer wall 4 of the piston upper part 2, and the outer surface 5 of the collar 14 is supported on the radially inner side.
7 and is limited at the top by the lower edge 8 of the wall portion 1 of the wall thickness of the outer wall 4 of the piston upper part 2. The external cooling chamber 45 is connected to the annular chamber 55 restricted in this way.
is extended downwards inside the piston lower part 1 by an annular chamber 58 which reaches the piston pin support 15 in an ox.

In the piston according to the second exemplary embodiment shown in FIG. 4, the external cooling chamber 45 is formed in the region of the piston upper part 2 by an annular upper cooling chamber part 59, which faces outwardly. , inner surface 2 of outer wall 4 of piston upper part 2
4, it is limited by the outer surface 60 of the inner support collar 17 and is open at the bottom towards a lower cooling chamber part 61 provided in the lower part of the piston, which lower cooling chamber part 61 is shown in FIG. - As in the embodiment shown in FIG. 3, the piston pin support 15 is reached by a trench.

The piston pin support part 15 is usually constructed in the shape of a dome like the limiting wall of the internal cooling chamber 410, and in the form of a hemispherical ceiling with a hollow spherical segment.
Inside the piston lower part 1, a connecting rod small end 34, which has an approximately circular outer contour 62, is surrounded at a small distance. Furthermore, this dome-shaped piston pin support 15 has bearing eyes 63, 64 on both sides of the connecting rod small end 34, as can be seen in FIG.
64 is penetrated by the bearing hole 2γ and moves to receive the piston pin ends provided on both sides of the connecting rod small end 340. In the area in front of the outer end of each bearing eye 63; 64, the outer wall 21 of the piston lower part 1 has a respective notch 6
5;66, and this notch 65;6
6, the piston pin 26 is assembled.

The dome-shaped piston pin support 15 preferably has substantially the same wall thickness throughout, so that the part of the external cooling chamber 45 located in the piston lower part 1 is partially As can be seen from the figure, it reaches the plane of the piston via 26.

The projection 36 and the annular support collar 14, which are integrally molded on the upper side 37 of the dome-shaped piston pin support 15, are advantageously each! 7f, and has a height corresponding to the diameter of the piston pin 26.

Between the outer surface 43 of the protrusion (36, 38) and the inner side 42 of the support member 14, a plurality of reinforcing ridges 67 are extended, which are distributed over the entire circumference of the upper side 37 of the dome-shaped piston pin support 15. There is.

The annular support collar 14 has a diameter at its upper end such that it supports the piston upper part 2 resting on the support collar or its convoluted support 13 in its unbending area.

Furthermore, normally the lower edge 680 circumference range of the piston lower part 1 is the outer wall 2.
As seen in FIG. 2, the lower area of both notches 65 and 66 in the piston lower part 1 is configured at a more acute angle than the oil scraping edge 69 when viewed in the axial direction. The remaining circumferential area of 68, located in the area of the pressure side and the counter-pressure side of the piston, is beveled or rounded as an oil conveying surface 70. This special configuration of the lower edge 68 in the piston lower part 1 always ensures that there is a sufficient lubricating film between the cylindrical outer surface 71 of the piston lower part 10 and the corresponding cylinder wall in the pressure and counterpressure side areas of the piston. This is ensured by the conveying surface 70, whereas the remaining circumferential area of the piston is below the recess 65, 66, where normally very little lubricating oil is required. In this region, the lubricating oil film adhering to the cylinder wall is reduced to a minimum film thickness in each case during the downward movement of the piston by the sharp oil 3 bevel 69. This significantly reduces oil consumption during engine operation.

outer limiting surface 7 adjacent to outer contour 62 of connecting rod small end 34;
The 20 radius is advantageously somewhat larger than the radius of the outer contour 62 of the connecting rod small end 34, as shown in FIG. Furthermore, as can be seen in FIG. 1, the inlet area of the cooling oil passage hole 39 is configured to widen conically toward the small end 34 of the connecting rod. As a result, the cooling oil remaining in the injection holes 48 at the small end 26 of the connecting rod can be transferred satisfactorily to the cooling oil through-holes 39 through which the internal cooling can be reliably and advantageously carried out. can flow into chamber 41.

The outer wall 4 of the piston upper part 2 and the outer wall 21 of the piston lower part 1, in the piston shown in FIGS.
After joining the piston upper part 2 and the piston lower part 1, an annular gap 75 will be left between the flat lower edge 73 of the outer wall 4 of the piston upper part 2 and the flat upper edge 74 of the outer wall 21 of the piston lower part 1. It is harmonized with.

In this case, through the annular gap 75 the oil scraped off the cylinder wall by the lowest piston ring 6 arranged above the piston can flow into the external cooling chamber, 15.

As can be seen from FIG. 1, the dome-shaped piston pin support portion 15 is connected to the outer wall 21 of the piston lower portion 1 approximately at the height of the piston opening plane including the piston longitudinal axis.

These features according to the invention, and in particular the combination of these features in the piston, make it possible to ensure satisfactory functioning of the piston even at very high ignition pressures, for example 180 par. In particular, the fact that the piston upper support part 15 is configured in a dome shape and the internal cooling chamber 41 is restricted to a dome shape makes it difficult for the piston upper part 2 to rest in an area where no bending occurs. This ensures that the ignition pressure acting on the piston during engine operation is introduced into the connecting rod 33 in the best possible manner via the support collar 14 and the piston pin 76, and thus the outer wall 4 of the piston upper part 2 and the outer wall of the piston lower part 1. 210 Cylindrical cylindrical shape and coaxiality are always maintained. By guiding the cooling oil according to the invention, especially in the piston upper part 2, a more powerful cooling in the piston upper part 2 is ensured. The adverse influence of temperatures occurring during engine operation on the shape of the piston upper part 2 can therefore also be significantly reduced by the type of cooling oil guidance in the piston upper part 2.

[Brief explanation of drawings]

The drawings show two embodiments of an oil-cooled piston according to the present invention. Fig. 2 is a vertical sectional view of the piston shown in Fig. 1 taken along the hi plane in a plane including the longitudinal axis of the piston pin, Fig. 5 is a sectional view taken along line III-N in Fig. 1, and Fig. Second
FIG. 3 is a partial vertical cross-sectional view of a piston according to an embodiment. 1...lower part of the piston, 2...upper part of the piston, 3...
・Piston-＼rad, 4...Outer wall, 5...Outer surface, 6
... Piston ring, 1... Wall portion, 8... Lower edge, 9... Wall portion, 10... Undercut, 11.1
6... Center positioning surface, 12... Support surface, 13...
- End face, 14... Support collar, 15... Piston pin support portion, 1γ... Support collar, 18... Support surface, 19
... lower edge, 20 ... upper edge, 21 ... outer wall, 22.
...Outer surface, 23...Center positioning collar, 24...Inner surface, 25...Tightening screw, 26...Piston pin, 2
7... Bearing hole, 28... Bearing sleeve, 29-32
... Fixed surface, 33... Connecting rod, 34... Connecting rod small end, 35... Receiving hole, 36... Projection, 3γ...
Upper side, 38... Mounting body, 39... Cooling oil flow hole, 40... Upper edge, 41... Internal cooling chamber, 42...
Inner surface, 43... Outer surface, 44... Communication hole, 45...
External cooling chamber, 46... supply hole, 4γ... annular passage,
48... spout, 49... outlet, 50-52...
・Inner surface, 53... Protuberance, 54... Blind hole, 55...
- Annular chamber, 56...inner surface, 57... outer surface, 58...
- Annular chamber, 59... Upper cooling chamber portion, 60... External surface, 61... Lower cooling chamber portion, 62... Outer contour, 63
．． 64...Support "eye," 65.66...Notch, 6
DESCRIPTION OF SYMBOLS 1... Reinforcement raised part, 68... Lower edge, 69... Oil scraping edge, 70... Oil conveying surface, 71... Outer surface, 72... City II l mixed race, 73...・Lower edge, 74・
...Top edge, 75...Annular gap, (loW 1) 76...Piston pin (loW 2)

Claims (1)

[Claims] 1. An oil-cooled piston consisting of an upper piston consisting of an outer wall and a piston head having a piston ring inserted into a ring groove, and a lower piston, the piston in the lower piston being The reciprocating piston is pivotally connected to a connecting rod connected to the crankshaft of an internal combustion engine through a piston pin installed in a bearing hole that passes laterally through the pin support, and the upper part of the piston is stepped from the piston head. The support surface is supported by the end surface of an annular support collar integrally molded on the upper part of the piston pin support part, and is attached to the lower part of the piston through a cylindrical center positioning surface to the lower part of the piston. The upper side of the piston pin support is further provided with a groove that is coaxial with the longitudinal axis of the piston, as well as the piston pin support. A projection is arranged, penetrated by the central cooling oil passage hole, which projects into the area of the upper part of the piston and limits the cooling oil filling of the internal cooling chamber with its upper edge; The internal cooling chamber is delimited in its lower region by the inner surface of the support collar, the upper side of the piston pin support and the outer surface of the projection, and in its upper region by a recess in the upper part of the piston and also by an oblique recess in the upper part of the piston. In the case of a type in which the piston is connected to an external cooling chamber through a communication hole, and the external cooling chamber extends surrounding the support collar at the upper and lower parts of the piston, the upper part of the piston (2) is made of spheroidal graphite cast iron. The piston lower part (1) is manufactured in one piece from gray cast iron or spheroidal graphite cast iron, and the piston is configured for shaker cooling and has cooling oil through holes (39) from the connecting rod (33). ) and a cooling oil supply path that supplies cooling oil to the internal cooling chamber (41) from the communication hole (44) to the external cooling chamber (45) and from the external cooling chamber to the crankshaft via the outlet (49). The internal cooling chamber (41) is formed by a dome-shaped hollow chamber, and the radially outer side of the hollow chamber is connected to the support collar (14). Due to the curved shape of the inner wall (42), the inner surface (50, 51) of the piston upper part (2)
The piston pin support (15) in the piston lower part (1) likewise has a dome shape. It consists of an almost hollow spherical sectioned hemispherical ceiling, with an almost circular outer outline (
62) in the interior of the piston lower part (1), surrounding the connecting rod small end (34) with a slight spacing, and on both sides of the connecting rod small end (34) for receiving the protruding piston pin ends. It has bearing eyes (63, 64), and the annular support collar (14) disposed on the upper part of the dome-shaped piston pin support part (15) is attached to its end face (
13), the piston upper part (2) resting on the annular support part (12, 18) is supported in an area where no bending occurs in the piston upper part, making it possible to assemble the piston pin (26). The lower edge (68
) is configured at an acute angle as an oil scraping edge (69), while the lower edge (68) of the piston lower part (1) is located in the area of the pressure side and the anti-pressure side of the piston. Oil-cooled piston for a reciprocating piston internal combustion engine, characterized in that the remaining circumferential area is chamfered or rounded as an oil-conveying surface (70). 2. The outer outer surface of the dome-shaped piston pin support (15) adjacent to the outer contour (62) of the connecting rod small end (34) (
The radius of 72) is the outer contour (62) of the connecting rod small end (34).
A piston according to claim 1, wherein the piston has a radius somewhat larger than the radius of the piston. 3. The dome-shaped piston pin support part (15) is connected to the outer wall (21) of the piston lower part (1) approximately at the height of the piston transverse plane containing the piston pin longitudinal axis;
A piston according to claim 1. 4. Piston according to claim 1, characterized in that the dome-shaped piston pin support (15) has substantially the same wall thickness at all points. 5. The outer surface (43) of the central protrusion (36) and the supporting collar (
A plurality of reinforcing protuberances (
67) is extended. 67). 6. The central protrusion (36) and the annular support collar (14), which are both integrally molded on the upper side of the dome-shaped piston pin support (15), each correspond approximately to the diameter of the piston pin (26). A piston according to claim 1, having a height. 7. Cooling oil flow hole (39) penetrating the central protrusion (36) and the wall of the dome-shaped piston pin support (15)
2. Piston according to claim 1, characterized in that the inlet area of the connecting rod (26) widens towards the small end (26) of the connecting rod. 8. In the area of the piston upper part (2), an external cooling chamber (45) extends from below, somewhat obliquely to the longitudinal axis of the piston, on the one hand and has a wall thickness of the outer wall (4) of the piston upper part (2). It is formed by a plurality of blind holes (54) integrally molded in the part (7) and distributed over the entire circumference, each of which has a communicating hole (44) opening therein; (54) is formed by an open annular chamber (55), the outer side of the annular chamber being by the inner surface (56) of the wall part (9) below the thin wall of the outer wall (4) and the inner side by the supporting collar (54). Piston according to claim 1, characterized in that it is bounded on the upper side by an outer wall (57) of the wall thickness (14) and by a lower edge (8) of the wall portion (7) of the wall thickness. 9. After joining the piston upper part (2) and the piston lower part (1), the flat lower edge (7) of the outer wall (4) of the piston upper part (2)
3) and the flat upper edge (74) of the outer wall (21) of the piston lower part (1), scraped from the cylinder wall by the lowest piston ring (6) located in the piston upper part (2). Piston according to one of the claims 1 to 8, characterized in that an annular gap (75) remains for allowing oil to flow into the external cooling chamber (45). 10. An external cooling chamber (45) is formed in the area of the piston upper part (2) by an annular upper cooling chamber part (59), which on the outside is connected to the outer wall (4) of the piston upper part (2). ) inner surface (24)
is bounded by the outer surface (60) of the annular support collar (17) which has a support surface (18) on the inside and downwards towards the lower cooling chamber part (61) located in the piston lower part (1). In this case, the piston upper part (2) is not only supported by the support collar (14) via the support surface (13) provided at the lower part of the support collar (17), but also by the piston upper part (2). The lower edge of the outer wall (4) of (2) (
It is also supported on the upper edge (20) of the outer wall (21) of the piston lower part (1) via the piston lower part (19) and in this area by means of a cylindrical central positioning surface (22) provided there. ),
A piston according to claim 1.