JPS6131294B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a piston crown section that is exposed to the combustion heat of an engine, and a guide section that handles only side thrust, which is separate from the piston crown section. - A support part articulated via a pin and further connected to the piston crown part via a thin wall part provided at the top of the piston crown part, and holding the seal ring and the scraper ring. a piston ring holding part, the support part being bifurcated at the end opposite to the piston crown part; The supporting legs are provided symmetrically with respect to a plane including the center line of the piston, and a piston pin connects the legs and the guide part in an articulated manner. The present invention relates to a piston for a reciprocating piston internal combustion engine, in particular for a diesel engine, having a hole for passage therethrough.

Prior art and its problems In reciprocating piston internal combustion engines that rotate at high speed, such as diesel engines and engine engines, the reciprocating part is There is a growing trend to reduce weight as much as possible. One possibility for reducing the weight of such reciprocating parts lies in the design of the piston and its associated power transmission, and every effort is directed to reducing the weight of these parts.

However, when reducing the weight of such parts, it is necessary to maintain sufficient strength and mechanical stability even under harsh operating conditions based on the high temperature combustion heat and high speed rotation of the engine. Care must be taken to ensure sufficient durability against wear.

One way to meet these demands is to reduce the piston crown area of the piston, which is exposed to high-temperature combustion heat, and the side surface that occurs between the piston and the cylinder wall due to the inclination of the engine's connecting rod.・Several piston designs have already been proposed in which the piston and skirt part are divided into thrust parts. For example, German Patent Application No. 2 625 191 proposes a design in which the piston ring holding part and the piston skirt part of the piston are separated; however, in this design, the two parts are simply separated in position. However, it is constructed as an integral structure, and cannot be said to meet the above requirements. In addition, U.S. Patent No. 3,516,335 proposes a piston in which the piston crown portion including the piston ring retaining portion and the piston skirt portion are constructed as separate parts, but in this case as well, these two parts are fixed to each other. The two pistons are joined together to form an integral whole piston, which cannot be said to satisfy the above requirements. Further, in West German Patent Publication No. 2016386, the piston crown part including the piston ring holding part and the piston skirt part are constructed as separate parts, and furthermore, these parts are articulated via a piston pin. A piston structure has been proposed that is connected to the piston. However, in this proposal, the piston crown and the piston pin are connected by bolting, so that the end of the engine connecting rod that is connected to the piston by the piston pin is bifurcated. Therefore, it is not guaranteed that the force exerted on the piston crown due to fuel combustion will be transmitted to the center of the connecting rod, and there is a risk of a lack of mechanical stability. Furthermore, the method of connecting the piston crown and the piston pin with bolts also has the disadvantage of preventing the free articulation of the two and making the piston pin prone to defects. I can't say I'm satisfied.

Further, in West German Patent Publication No. 2543478, the piston crown is exposed to the combustion heat of the engine, and the piston crown is connected to a separate guide part that handles only side thrust via a piston pin. the piston crown, which is connected to the piston crown via a thin-walled part on the top of the piston crown, and which retains the seal ring and the scraper ring; a ring holding part, and the support part, at its end opposite to the piston crown part, transitions into a leg part consisting of two supporting legs made in a bifurcated form. The support legs are provided symmetrically across a plane including the center line of the piston, and a hole for passing a piston pin that articulates the legs and the guide part is provided. A piston for reciprocating piston internal combustion engines, in particular for diesel engines, has been proposed, having the following characteristics: This type of piston makes it possible to equalize the temperature in the combustion chamber according to a heat distribution pattern that is well adapted to the current combustion process, thus optimizing the combustion process between the fuel and the combustion air. On the other hand, the load on the sealing ring or scraper ring on the piston ring holder can be reduced. This type of piston has traditionally been used for combustion process aspects as well as seals and
Although it is recognized that the ring or scraper ring has excellent characteristics in terms of stress applied to it, it is necessary to improve its mechanical stability in view of the significant increase in the output of internal combustion engines. There was found.

Purpose of the Invention Therefore, the purpose of the present invention is to eliminate the drawbacks of the conventional techniques as described above, maintain sufficient mechanical strength, heat resistance, wear resistance, and mechanical stability, and yet A piston with a new structure that allows the structure of its component parts to be changed relatively easily according to the need for optimizing the piston, and further reduces the weight of the reciprocating part. It is about providing.

Structure of the Invention According to the present invention, the above-mentioned object can be achieved by the structure as described below. In other words, the piston crown part, which includes the piston ring holding part and is exposed to high-temperature combustion heat, is articulated via a piston pin to a separate guide part that is in charge of only the side thrust applied to the piston. The body is formed into a trapezoidal shape with the longitudinal centerline of the piston as the axis of rotational symmetry, and a space is provided inside the body, and the space is defined by the longitudinal centerline of the piston (rotationally symmetrical). The structure is such that at least one of the base surface and the top surface of the trapezoid is closed in the direction of the trapezoidal axis (axis).

Effects of the invention By adopting such a structure, not only the mission assigned to the present invention is fully accomplished, but also
Furthermore, a piston is provided which has the excellent feature that it can be produced by an extremely simple manufacturing method. The piston of this new design can not only be manufactured by automatic machine tools, but also by casting, with only the surfaces corresponding to the cylinder wall and the piston pin being machined. It is also possible to finish by twisting, and by adopting this manufacturing method, the amount of machining work can be reduced to a minimum,
As a result, a highly reliable piston with sufficient strength and mechanical stability can be provided at extremely low manufacturing costs.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, features of the present invention will be described in more detail regarding one embodiment of the present invention with reference to the drawings.

FIG. 1 is a longitudinal cross-sectional view of a piston according to the present invention taken along a plane including its longitudinal centerline and the centerline of the piston pin (the plane indicated by - in FIG. 2). The right half shows that the space provided in the piston crown is closed at one end of its longitudinal central axis, and the left half shows that it is closed at both ends of its longitudinal central axis.

2 is a top plan view of the piston of FIG. 1; FIG.

The piston 1 according to the invention basically consists of two separate components, one of which is directly exposed to the heat of combustion and the other located after this first part. This is the part that serves to guide the first part. The first component directly exposed to this combustion heat is furthermore the sealing ring 4.
Also, from the piston crown part 2 which is connected to the piston ring holding part 3 in which the scraper ring 5 is fitted, and the support part 7 which connects this piston crown part 2 and the leg part 6 of the piston 1. and this first component has its leg 6 as well as a piston, shown in phantom in the figure, for connecting it with the other component described above. It is articulated as a whole with the second component via a pin. Further, this second component is made as a guide part 9, which in this case has an annular form, and whose outer cylindrical surface corresponds to the inner wall surface of the cylinder 10 and which extends in the radial direction. The position is maintained. This guide part 9 has the role of taking care of the side thrust that occurs because the connecting rod assumes an inclined position when it moves up and down inside the cylinder 10, and is different from the above-mentioned first component. Since it is connected in such a way that it can perform a pendulum movement, the result is that this first component is not subjected to any side thrusts and that the piston ring retaining part 3 and thus also the piston crown part 2 and the cylinder 10 All it has to do is to maintain an airtight seal between them. Support part 7 connecting piston crown part 2 and leg part 6
is made into a conical shape in this embodiment, and has one space 11 inside, but this space 11 is not the same as the leg part in the right half of the piston 1 in FIG. 6 is open to the atmosphere through an opening 12. In the right half of FIG.
In contrast, in the left half of FIG. 1, the lid 14 has a structure that is closed by a single lid 14. In the structure of the piston 1 having such a lid 14 for closing the space 11 provided inside the support body part 7, in order to finish the piston 1 as an integral piece, it is necessary to close the peripheral edge of the lid 14. 15 is suitably attached to the piston crown 2 by friction welding or electron beam welding in such a way that it cannot be disassembled again. In the left half of Figure 1,
For clarity, there is one gap 1 between the peripheral edge 15 of the lid 14 and the piston crown 2.
6 is drawn, which is the part to be filled with welding material. In order to fit the lid 14, the piston crown 2 has a peripheral edge 1 of the lid.
A counterbore 17 is machined within the range of 5. In addition, in order to give the piston crown part 2 enough strength to withstand the combustion gas pressure,
Regardless of whether the piston crown part 2 is constructed as a ceiling part 3 or as a lid 14, it is possible to extend it from the periphery towards the axis of rotational symmetry Y, i.e. from the outside, as shown in FIG. It is effective to gradually increase the thickness of the cross section from the center inward, but in this case, the thickness naturally reaches its maximum at the axis of rotational symmetry.

Just as the support part 7 is made conical, the space 11 provided inside it is also made conical. The base surface of the space 11 facing the piston crown part 2 has a diameter 18, and this diameter 18 is an equal circle dividing the surface area of the upper surface of the piston crown part 2 into inner and outer parts. The size can be approximately equal to 19. This equally divided circle 19 can be considered to be approximately 0.7 times the outer diameter of the piston crown portion 2.

The support portion 7 that connects the piston crown portion 2 and the leg portion 6 is formed into a conical shape as a whole, as shown in the figure, but its both ends, that is, its base surface 20 and the cut of the truncated cone, are formed into a conical shape as a whole. head 21
The piston crown 2 and the support legs 22 and 23 adjacent to the legs 6 are connected via their respective support surfaces. This support body part 7
The cross-sectional areas of all cross-sections perpendicular to the axis of rotational symmetry Y must be as equal as possible. This can be achieved by making it a reality.

In addition, if there are any special circumstances, this space 11 is closed not only at the piston crown section 2 but also at the leg section 6 with another lid 25, and the space 11 itself is closed. It is not inconceivable to try to form a complete sky. In this case, the space 11 is closed by
This can be done by the lid 25 mentioned above, or by leaving a wall at the leg 6 if the piston crown 2 has an opening. If the lid 25 is provided at the leg 6, it is also necessary to provide a counterbore 26 at the end of the support 7 that contacts the leg 6, that is, at the truncated surface 21 of the conical pedestal. Attaching the lid 25 to the support portion 7 involves attaching the lid 14 to the piston.
As with the case of attaching to the crown part 2, it can be done by electron beam welding or other methods.

As the previous practical examples of piston 1 show,
The piston 1 is usually made integrally with the entire surface of the piston crown part 2 as a ceiling part 13, and the space part 11 is left open at the leg part 6. When the piston 1 has such a structure, if cooling is necessary for the heat load applied to the piston, droplets of lubricating oil can be sent into the inside of the space 11 to cool the piston. is also possible.

In such a case, the support leg 2 following the leg 6
2, 23 are not merely arranged symmetrically on either side of the longitudinal central plane During this time, so that the lubricating oil splashes sufficiently reach the inside of the space 11,
It is also possible to provide a sufficiently wide gap. In the case of a piston having a structure in which the space 11 is closed at the leg portion 6, it is possible to sufficiently cool the area around the leg portion 6 by splashing lubricating oil.

According to the results of research on pistons with such high thermal loads, a thin wall portion 2 is formed at the boundary between the piston crown portion 2 and the piston ring holding portion 3.
8 makes it possible to significantly reduce the effect of heat on the sealing ring 4 and the scraper ring 5 fitted in the piston ring holder 3, thus extending the service life of these rings. Not only can these rings be made of relatively less heat resistant materials, but also more inexpensively. A thin wall portion 28 between the piston crown portion 2 and the piston ring holding portion 3 is provided at the top of the piston crown portion 2.

In this way, the piston 1 can not only be provided with a space 11 inside its support part 7, but also this space 11 can be formed in some cases depending on the choice of the combustion process and in some cases. In order to reduce the weight of the piston, at least one of the upper and lower sides can be closed in the direction of the longitudinal axis, that is, the axis of rotational symmetry Y. By taking this approach, the piston 1 can be very easily modified, if necessary, so that it can also be used for different combustion processes (for example, the combustion chamber is also located inside the piston, etc.) Even if the product is available only externally), it is only necessary to prepare a single basic design in terms of manufacturing and parts stock.

[Brief explanation of the drawing]

1 is a longitudinal sectional view of the piston along the plane - of FIG. 2, and FIG. 2 is a plan view of the piston of FIG. 1 viewed from above. 1... Piston, 2... Piston crown part, 3
...Piston ring holding part, 4...Seal ring, 5...Scraper ring, 6...Legs, 7...Support part, 9...Guide part, 10...Cylinder, 11...
Space part, 13... Ceiling part, 14... Lid, 19... Equally divided circles, 22, 23... Support leg part, 25... Lid, 28... Thin wall part.

Claims (1)

[Scope of Claims] 1. A piston crown exposed to the combustion heat of the engine, and a separate guide portion that is in charge of only side thrust, articulated through a piston pin. a supporting body part to be connected; and a piston ring holding part which is connected to the piston crown part through a thin wall part provided at the top of the piston crown part and which holds a seal ring and a scraper ring. , and the support part, at its end opposite to the piston crown part, transitions into a leg part consisting of two support legs made in a bifurcated form, and The support legs are provided symmetrically across a plane including the centerline of the piston, and have holes for passing piston pins that articulate the legs and the guide part. In the reciprocating piston type internal combustion engine piston, the support body part 7 is made in the shape of one rotationally symmetrical truncated cone, and one space part 11 is formed inside thereof, and this space part 11 is used for the piston. 1. A piston characterized in that at least one of a base surface and a truncated surface of the truncated cone is closed in the direction of a longitudinal center axis (rotation center axis Y) of the cone. 2. The piston according to claim 1, wherein the space 11 is closed by the piston crown 2 itself at approximately the position of the piston crown 2 of the piston 1. 3. In the piston according to claim 1 or 2, the wall thickness of the piston crown portion 2 is directed toward the center of the space portion 11 in a region surrounding the rotation center axis Y of the space portion 11. A piston that grows into a conical shape. 4. In the piston according to claim 3, the increasing wall thickness in a conical shape extends from the edge of the base surface 18 of the space 11 to the rotation center axis Y.
A piston that has been extended to. 5. In the piston according to claim 1, the cross-sectional area of the wall surface forming the support body part 7 in all cross sections taken by cutting the support body part 7 along a plane perpendicular to the axis of rotational symmetry is Equal pistons. 6. Claims 1, 3, and 4 all provide that in the piston according to claim 1, the space 11 provided inside the support portion 7 of the piston 1 is a piston crown portion. 2 and which is closed off by a single lid 14 which at the same time forms part of the piston crown 2. 7. In the piston according to claim 6, the lid 14 covers the piston crown within a region of an equal circle 19 that equally divides the surface area of the upper surface of the piston crown portion 2 into inner and outer parts. Piston fixed to part 2. 8. In the piston according to claim 1, the space portion 11 is located in the leg portion 6,
The piston is closed by a single lid 25. 9. In the piston according to claim 6 or 8, the lid 14 at the piston crown portion or the lid 25 at the leg portion
However, the piston 1 part (piston crown part 2
A piston which is permanently connected to the support part 7). 10 In the piston according to claim 6 or 8, the lid 14 at the piston crown portion or the lid 25 at the leg portion
However, the piston 1 part (piston crown part 2
A piston which is removably connected to the support part 7).