DE2321420A1 - PISTON - Google Patents

Description

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Howard James Eaterson April 26, 1973

57 Second Avenue

Klemzig, State of South Australia

Commonwealth of Australia

Pistons

The invention relates to a piston of the type commonly used in internal combustion engines.

A well-known problem with such pistons is that of the one currently in use and cast pistons can seize in the cylinder of an engine block.

The reason for this is an increased thermal expansion of the piston opposite that of the cylinder so that those exerted by the opposite sides of the piston Sufficient forces to bring about the pressing between the two metals of the piston and cylinder.

Usually the stabilizing piston skirt parts and the cylinder are mounted with play so that the different Thermal expansion of the piston and cylinder through this play can be absorbed before a significant amount Pressure is exerted on the cylinder walls.

However, the possible play is limited by the fact that the Piston skirt acts as a stabilizer for the piston if Now the play is too big, the piston can become in the

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Cylinder - during the back and forth movement "tilt" and cause a strong piston "hit" that is not only in terms of noise, but also under the aspect of material fatigue is undesirable due to the impact.

This problem is usually solved by Kolbei and cylinders are mounted with so much play that a piston will indeed eat at extremely high temperatures can, but the emergence of pistons "hit" as possible is restricted. ,

The object of the invention is to provide a piston with only small The tendency to seize within the cylinder is extraordinary to create high temperatures and at the same time not to allow too much clearance between the piston and cylinder so that the possibility of piston "sawing" is reduced or completely excluded.

One embodiment of the invention is that a piston with opposing piston pin bearings is created, between which piston skirt parts on the circumference lie, this arrangement being characterized in that between the piston pin bearings and the piston skirt parts Thermal expansion compensators lie.

The thermal expansion compensation members are preferably wave-shaped with at least one turn or curvature in the course the piston skirt wall formed.

Each of these turns is preferably located parallel to the piston axis, so that a yielding q; outside the piston axis can be achieved.

Preferably there are several such turns in each parallel alignment to the piston axis, with one turn between each side of each

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Piston pin bearing and each piston skirt wall provided is.

In the case of herkOTmn1.icb.en baskets, the heat would expand a stretching force occurs, whereby the metal of the vand only exerts this pressure due to the compression forces within of the metal.

. The thermal expansion compensation members, in particular the one turn of the wall, reduce the by one given different thermal expansion forces resulting from the fact that a part of the load-bearing due to the expansion Metal is not compressed, but bent, which allows a much greater deflection without the Forces are much greater.

In this way, the load-bearing capacity can be behind the stabilizing Piston skirt wall are adequately designed and at the same time when larger forces occur in allow greater deflection of a given order of magnitude.

Therefore, with different thermal expansion of the opposing stabilizing piston skirt parts exerted pressure can be kept lower than with conventional pistons, so that there is a risk of seizure of the piston in the cylinder can be reduced significantly while leaving less clearance between them could.

It is also possible to have the pistons in their desired design with turns running paailel to the piston axis manufacture in forging technology.

By forging the piston, especially using it of the concept of this invention can advantageously a material can be used which has a greater strength than is possible with standard casting techniques

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j would be possible while earlier when using forged Piston extraordinarily large clearances had to be provided, it is now possible to keep the clearances narrow, thereby reducing the risk of piston hits, whereby At the same time, the great advantage that high-strength material can be used.

Another advantage of forging over standard pistons is that each piston is allowed to have tolerances in standard weight, thus making the problems related with the subsequent balancing of the piston weights, which was required for pistons made of cast iron. .

By using the forging technique, the weight of the piston due to the higher material strength whereby the performance of an engine can be increased through the use of such pistons.

Further details, features and advantages of the invention result from the following description of a Embodiment based on the drawing.

Show it .

Jfig. 1 shows a bottom view of a piston according to the invention, Pig. 2 shows a side view of the same piston, and FIG. 3 shows a section along section line 3-3 in FIG.

From the drawing it can be seen that the piston 1 has a head 2, piston pin bearing 3 and on the circumference between the Has bearings 3 extending piston skirt parts 4.

Conventionally on the piston are the grooves 5 for the sealing rings and a groove 6 for the oil ring or oil control ring.

The opposing arrangement of the piston pin bearings 3 for fastening the piston pins and a connecting rod or the like.

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Oil reaches Uut 6 through opening / 8.

Between the piston pin bearing 3 and each piston skirt part 4, thermal expansion compensation members 9 are provided in a wave-shaped configuration transversely to the course of the piston skirt parts. The wave-shaped part extends parallel to the axis of the piston 1.

The wall thickness of the piston skirt is wavy during its Course 9 and also at the connection with the Piston pin bearing 3 essentially the same.

Between the head 2 and one of the piston skirt parts 4 is a slot 12 is provided to reduce direct heat transfer from the head to the piston skirt part, where this with the reference number 13 to distinguish it is designated.

The piston pin bearing has a greater metal concentration next to the opening and between the opening and the head on, like in Jig. 3 is shown and denoted by 14j this iOrm allows the piston to be cast or forged as a whole using a single insert will.

The oil holes 8 can either be through the forging die be formed or poured directly, and in the formation of the groove 6 spark oil ring overlaps them the holes that make the connection.

From the description it can be seen that the piston skirt parts 4 held by the wave-shaped leil 9 below the effect of thermal expansion is the ultimate pressure exerted by the constraining cylinder from the bending of the wave-shaped metal part 9, whereby the applied pressure can be kept lower than this

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for fa.erko-mm1icfa.ep pistons under given thermal expansion conditions would have been possible.

In operation, the piston skirt parts 4 have a stabilizing effect on the movement of the piston, and the part of the piston skirt with the greatest effect is that of the piston pin bearings most distant afeil- accordingly Various forms of construction are possible, whereby different miter surfaces can be provided, however Internally, Pail's preferred feature is that between the effective guide surface and the piston pin bearings a wave-shaped part is provided to thereby pressure differences with given head differences compared to previous ones Reduce embodiments.

The advantage of slot 12 is to prevent part of the heat transfer to the piston skirt part 13, and this is particularly desirable because it increases, to some extent, the temperature of the piston skirt is lowered. The resulting reduction in temperature corresponds to general practice.

The illustrated embodiment is a piston from an aluminum alloy casting, and the wave-shaped parts are integrally cast parts of the piston skirt wall, the is also cast in one piece together with the remaining parts of the piston.

The term "winding" or "undulating part" denotes a wall with an essentially consistent cross-section that is folded or shaped like an accordion so that Compression or stretching over the winding causes the wall material to bend, which results in a deflection will.

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Claims (5)

Howard James Paterson April 26, 1973 57 Second Avenue, Klemzig Patent claims: (^, / Pistons with opposing piston pin bearings and in substantial piston skirt parts running on the circumference between the piston pin bearings, characterized in that that between the piston pin bearings (3) and the piston skirt (4) there are thermal expansion compensation members (9). 2. Piston according to claim 1, characterized in that the thermal expansion compensation members (9) each consist of at least consist of a turn. 3.) Piston according to claim 2, characterized in that each turn is parallel to the piston axis. 4. Piston according to claim 2, characterized in that one next to each side of each piston pin bearing Winding (9) is provided in the piston skirt wall. 5. Piston according to claim 1, characterized in that the thermal expansion compensator consists of a design of either the piston skirt or the piston pin bearing, so that the yielding necessary to compensate for the thermal expansion is achieved by a bend of the metal a * larger. Ifaoh & ebe'ä ■ ". Is reached · 309846/0884 Blank page