DE2411840A1 - PISTONS FOR COMBUSTION ENGINES - Google Patents

Description

2411840 OUR SIGN:

Associated Engineering France S.A., Chasseneuil-du-Poitou (France)

Pistons for internal combustion engines

The invention relates to pistons for connecting engines and to methods of making such pistons. In particular, the one according to the invention is mainly composed of aluminum Piston suitable for diesel engines.

It is known, pistons for internal combustion engines !! with. Ring grooves to accommodate piston rings, the piston head is exposed to elevated temperatures during operation and a serious one In particular, the use of the ring groove closest to the head is expected to result in loads being exerted on the sides of the groove are exerted by the ring that is inserted into the groove, in particular the inertial forces and consequent! the reciprocating movement of the piston occurring forces.

Numerous attempts have been made to alleviate this wear and tear to reduce, in particular an annular insert made of steel or other resistant material in the Shape was provided and the metal of the piston was poured around this insert. The ring groove was then in the insert body Machined so that the loads to which the groove was subjected by the piston ring, from the resistant Surface of the insert body were added. It has been found that it is difficult to test the piston to ensure that that the entire surface of the insert body during the

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Casting process was connected to the cast body. Since the different materials for the insert body and piston, i.e. steel or aluminum alloy, require different heat treatments in order to achieve their optimal properties obtained, the heat treatment of the composite cast body is difficult.

According to a feature of the invention is the annular groove of a piston reinforced at least on one side with a reinforcing body which is welded to the piston body, the reinforcing body made of a material resistant to wear, and several segments around the ring of the piston has around.

According to a further feature of the invention, a method for manufacturing a piston is carried out in such a way that a piston body with a piston ring groove larger than that required for inserting the piston ring is produced, that several reinforcing bodies are made of wear-resistant material, each of which the Has the shape of a ring segment that the reinforcing body is then welded to at least one side of the piston ring groove that they extend over the circumference of the piston, and that finally the reinforcing body by cutting machined to provide the groove width required for inserting the piston ring.

Preferably the piston is made of an aluminum alloy and the reinforcing material is made of steel and preferably the reinforcement bodies are attached to one or both sixths of the groove by electron beam welding.

Exemplary embodiments of the invention are described below with reference to the drawing. In the drawing show:

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Fig. 1 is a partially cut-away view of a piston according to the invention;

2 shows a longitudinal section of a piston section in the area of an annular groove formed according to the invention

3 shows a sectional view corresponding to FIG second embodiment;

Fig. 4 is a cross section showing various shapes of reinforcing bodies.

FIG. 1 shows a typical diesel engine piston with several piston ring grooves 11 which are arranged in the piston body 12, which consists of an aluminum alloy. It can for example consist of an aluminum alloy that contains 12 % Si, 1% Cu, 1% Mg and 1% Ni. The groove HA closest to the combustion chamber is exposed to the greatest stress and accordingly the greatest wear, because this is where the highest temperatures prevail and the gas pressure is greatest. In addition, the groove is loaded by inertia forces that are exerted by the piston ring that is inserted into the groove. According to the invention, this groove is reinforced by reinforcing body 1J> by the method described below. The thickness of the reinforcement parts 13 is shown exaggerated in FIG.

According to Figure 2, the piston body 12 and the material of the reinforcement body I3 is designed so that they are directly against one another can be welded, the reinforcing body 13 incisions 14 inserted in the side surface 15 of the piston ring groove HA and attached by electron welding l6, the jet being directed substantially radially with respect to the piston.

Reference is made below to FIG. 3 of the drawing.

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The piston body 12 and the material for the reinforcing body 13 are chosen so that they are not directly with one another can be welded. Therefore, the reinforcement body 13 is first placed on a layer 17 made of a material set that can be welded to the piston body. The connection of the reinforcement bodies I3 with the laminated bodies 17 can be done either by plating, by rolling, or by any other method. The layer 17 can instead also deposited by spraying on the reinforcing bodies I3 will. The reinforcement bodies are then placed with the layers 17 against the side surfaces 15 of the groove HA and the layers 17 are welded to the piston body 12 in the manner described by electron beam welding as shown at 16. In this case, a radius 18 is preferably made at each corner of the base of the groove for resistance to improve against a breaking off of the inner edge of the reinforcing body 13 under the influence of hot fuel gases.

Each side surface 15 of the piston ring groove is preferably provided with several reinforcement bodies 13 *, e.g. with eight reinforcement bodies equipped, and these can be interlocked with one another in various ways as shown in FIG. at Given the design of the piston, the same connections are expediently used. Figure 4 only shows various alternatives Solutions that can be used with different flasks. For example, the connection between the parts can be radial like shown at 19, or in a diagonal direction as shown at 20, or it can be a tongue-shaped groove connection 21 can be used, or an overlapped connection 22 can be used, or finally a gradation can be used in accordance with 23 apply.

If the piston body is made of an aluminum alloy, the reinforcing bodies can be made of steel, but if the piston body is made of cast iron, reinforcement bodies made of even more resistant material should be used, which withstands wear and tear even better.

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The invention can be applied to new pistons, or to the renewal of pistons in which the grooves are in operation have been worn out.

In one embodiment according to FIG 3, the reinforcing body are made of mild steel (for example, with O, 1% or 0,3p% carbon steel). These reinforcement bodies are rolled onto an aluminum alloy layer 17. This aluminum alloy can be an A-G5 alloy containing nominally $ 5 Mg and the balance aluminum, or an A-S12UN alloy containing nominally $ 12 silicon, small percentages of copper and nickel and the balance Contains aluminum. This aluminum alloy layer is in turn fixed by electron beam welding on the piston 12, which consists of the aforementioned 12 $ silicon-aluminum alloy,

Examples of materials that can be used for the individual workpieces are explained below.

I. Materials for the piston 12

Example 1.

Alloy A-S 12 UN (AFNOR) nominal composition: - silicon 12 $

Copper _ $ 1.2

Nickel $ 1

Aluminum - rest

aluminum

Example 2. Alloy A-S 1OU (AFNOR) nominal composition: - Silicon $ 10

Copper $ 1

Magnesium) and nickel) ^traces

rest

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6 - 24118.

Example ^. Alloy A-U4NT (AFNOR) nominal composition: - copper k%

Nickel 2%

Titanium Q.1%

Aluminum - rest

II, For the reinforcement body 13

(a) Iron alloys that cannot be welded directly to the piston, but only by means of an intermediate layer according to FIG

Example 1. XC ^ 5 steel, i.e. O.J5 ^ carbon steel. Example 2. XClO steel, i.e. $ 0.10 carbon steel.

(b) Copper alloys, which may not be directly can be welded to the piston, but only in connection with an intermediate layer according to Figure 3

Example 1. Alloy UZ23A4

Nominal composition zinc 27)%

Aluminum -jfo

Nickel,)

Iron,) <2.5 ^

Manganese)

Copper - rest

(e) Aluminum alloys that can be welded directly to the piston

Example: Alloy A-S22UNK (AFNOR) nominal composition

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silicon 22 ^ copper 1.5% nickel 1.2 YEARS Kobalö 1.2 yrs aluminum rest

III. For the intermediate layer YJ, which is first attached to the iron or copper alloy body

(a) Any of the aluminum alloys according to Example 1, 2 or 3 can be used which are suitable for the Pistons 12 are used,

(b) Alloy A-G5: 5% magnesium, balance aluminum or

(c) Alloy A-G6: 6% magnesium, balance aluminum.

The most important cases in practice are those according to FIG. 2, with reinforcement body IJ made of an aluminum alloy A-S 22UNK (see FIG. 2c above) were used, which were attached to the piston 12, which consists of an alloy A-S 12UN (See Example 1 for the piston).

With reference to Figure j5 has proven to be an important embodiment such a result in which the reinforcing body 13 from Xc35 steel passed (see 2 (a) Example 1 above), with a Layer 17 from AS 1OU was used (see example 2 for the Piston body above) and the piston 12 consisted of A-S 12UN (example 1 for the piston).

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Ansnrur-hf =?

Claims (12)

Claims 1.) Pistons for internal combustion engines with a piston ring groove, which is reinforced on at least one side with a reinforcement body which is welded to the piston, thereby gekennzei chnet that the reinforcing body as flat ring sections wear-resistant material are formed, each extend over a segment section together over the circumference of the piston. 2. piston according to claim 1, characterized in that the reinforcing body directly on the Seirenfläche the Piston ring groove are welded. 3. piston according to claim 1, characterized, that the reinforcing bodies are each connected to a layer of weldable material, and that the layers in turn are welded to the groove side walls. 4. piston according to claim 3, characterized in that the reinforcing bodies are weldable on one layer Material are applied by plating or by rolling or by spray deposition. 5. Piston according to claims 1 to 4, characterized in that that the reinforcing bodies are fixed on the piston by electron beam welding. 409839/0734 6. piston according to claims 1 to 5,
characterized in that the individual segment sections of the reinforcement bodies are connected to one another in a form-fitting manner. 7. piston according to claim 6, characterized, that the individual segment sections are locked by an overlap connection, a toothing or a step connection are. 8. Piston according to Claims 1 to 7 >
characterized in that the piston is made of an aluminum alloy and that the reinforcing bodies are made of steel. 9. piston according to claim 8, characterized in that the piston is made of an aluminum alloy, at least 10 $ contains silicon, and that the reinforcing bodies are made of steel, and that they are covered with a layer of aluminum alloy are connected. 10. piston according to claim 9, characterized, that the reinforcing bodies are rolled onto the layer made of aluminum alloy. 11. piston according to claim 10, characterized in that the alloy forming the aluminum layer is about 5 $ Contains manganese and the remainder aluminum. 12. piston according to claim 10, characterized by the fact that the aluminum alloy of the layer is about 12 $ silicon, Contains small amounts of copper and nickel and the remainder aluminum. 409839/0734 Le e rs e it