CN111691961A

CN111691961A - Air gap isolated exhaust elbow

Info

Publication number: CN111691961A
Application number: CN202010175944.8A
Authority: CN
Inventors: I.帕帕迪米特里乌; C.格拉芙; K.特拉克
Original assignee: George Fischer Metal Forming Technology AG
Current assignee: George Fischer Metal Forming Technology AG; GF Casting Solutions AG
Priority date: 2019-03-13
Filing date: 2020-03-13
Publication date: 2020-09-22
Also published as: EP3708798A1

Abstract

The invention relates to an air-gap-insulated exhaust manifold for an internal combustion engine in a motor vehicle, comprising an inner element and an outer element, wherein the inner element has at least two tubular hollow bodies made of sheet metal, wherein the hollow bodies are connected to one another in a movable manner, wherein the outer element is separated from the inner element by an air gap, wherein the outer element is designed as a one-piece casting, wherein no direct contact is present between the inner element and the outer element, and to a method for producing the same.

Description

Air gap isolated exhaust elbow

Technical Field

The invention relates to an air-gap-insulated exhaust manifold for an internal combustion engine in a motor vehicle, comprising an inner element and an outer element, wherein the inner element has at least two tubular hollow bodies made of sheet metal, wherein the hollow bodies are connected to one another in a movable manner, wherein the outer element is separated from the inner element by an air gap, and wherein the outer element is designed as a one-piece casting, and to a method for producing the same.

Background

The tubes in the exhaust manifold are subjected to a great thermal load, in particular in gasoline motors, since the exhaust gas flowing through the exhaust manifold may have a temperature of more than 1050 ℃. Therefore, air-gap-insulated exhaust gas manifolds are known from the prior art, which are mostly welded together from a plurality of high-alloy sheet metal parts, whereby such exhaust gas manifolds are expensive in terms of their production costs.

WO 2006/097187 discloses such an air-gap insulated exhaust elbow made of sheet metal.

The following exhaust manifolds are also known from the prior art: the exhaust manifold has an inner pipe made of sheet metal, which withstands the high temperatures of the exhaust gases and is surrounded by a casting. Although the production time in such exhaust manifolds is shorter than in the case of a completely thin-plate design and is therefore better suited to mass production, high demands are placed on the cast material, since the high temperatures acting on the inner pipe from the exhaust gas are transmitted directly by heat conduction or conduction via the contact points between the inner pipe and the cast housing, and therefore the cast housing is also subjected to high temperatures.

One such solution is disclosed in US 2008/0083216 a1, in which it can be clearly seen in the drawing that the cast outer shell is in contact with the inner pipe in the region of the adapter and with the hot inflowing exhaust gas. This solution presupposes that the casting material used can withstand high requirements and, therefore, also high-quality, correspondingly expensive casting materials must be used.

If the solutions known from the prior art are to meet the temperature requirements for gasoline motors, these solutions are correspondingly expensive either because of the high-alloy steel castings that have to be used or because of the plate structures that require welding which takes a lot of time.

Disclosure of Invention

The object of the present invention is to propose a device and a method associated therewith, which provides an air-gap-isolated exhaust manifold that, by virtue of its design, allows a cost-effective embodiment to be implemented, which can be used both for the materials to be used and in the production method, and which can still be used for gasoline motors with high exhaust gas temperatures.

According to the invention, this object is achieved by: there is no direct contact between the inner element and the outer element. The air-gap-insulated exhaust manifold has an inner element, wherein the inner element is formed by at least two tubular hollow bodies made of sheet metal. The tubular hollow body preferably has a plurality of connections, wherein an inlet connection and/or an outlet connection is provided here. The hollow bodies connected to one another to form the inner element preferably have different designs of the course of the connecting piece, in order to be able to achieve an optimum design or course with regard to the available installation space in the motor of the exhaust manifold. The tubular hollow bodies connected to one another to form the inner element are arranged so as to be movable relative to one another, preferably in the axial direction, as a function of the connection points of the hollow bodies connected to one another, which enable the inner element to react to temperature changes in the exhaust manifold and to expand or contract accordingly, or the sleeve connection to allow axial movement of the hollow bodies relative to one another. Furthermore, the exhaust manifold has an outer element which is separated from an inner element by an air gap, wherein the outer element is formed as a one-piece cast part. In order to achieve as effective an insulation as possible by means of the air gap between the inner element and the outer element, there is no direct contact between the inner element and the outer element. The outer element does not touch the inner element at any point, whereby heat conduction or conduction is avoided and the air gap between them ensures optimum insulation.

Preferably, in the case of the inventive air-gap-insulated exhaust manifold, there is no direct contact between the outer surface of the cast-in inner element and the inner surface of the cast-in outer element, i.e. there is an air gap everywhere between them. This results in a significantly lower temperature acting on the outer element consisting of the cast part, as a result of which it is possible to use a casting material suitable for lower temperatures and to dispense with high-alloy steel castings, as a result of which greater costs can be saved.

It has proven advantageous if the exhaust gas flowing through the exhaust manifold, which is isolated by an air gap, is in contact exclusively with the inner surface of the inner element. It is also avoided here that the exhaust gas comes into direct contact with the outer element made of cast parts and, as a result, the outer element is directly exposed to extremely high temperatures. Thus, there is a continuous air gap between the outer surface of the inner element and the inner surface of the outer element.

In a further embodiment of the invention, the tubular hollow body is made of a steel plate.

Advantageously, the inventive air-gap-insulated exhaust manifold has an outer element made of cast iron, preferably nodular cast iron. This material is well suited for automotive construction.

The invention is characterized in that the tubular hollow bodies of the inner element are connected to one another in a movable manner by means of a sleeve connection. The sleeve connection is distinguished in that the pipe end which has not been deformed and therefore corresponds to the pipe diameter of the hollow body is inserted into the expanded pipe end. The pipe ends are arranged concentrically with respect to one another and can be displaced axially with respect to one another, since the expanded pipe ends guide the inserted pipe ends over the length of the sleeve connection, as a result of which expansion or displacement of the hollow body due to the high temperatures acting on the exhaust manifold or relative to one another and contraction during cooling can be carried out without problems by means of the sleeve connection.

According to a preferred embodiment, the inventive air-gap-insulated exhaust manifold has a spacer element on the outer surface of the inner element. The spacer element should ensure that the inner element is not tangent to the outer element at any position.

Furthermore, the present object is achieved with a method according to the invention for producing an air-gap-insulated exhaust manifold, having the following steps:

producing an inner element, wherein at least two tubular hollow bodies made of sheet metal are connected to each other in a movable manner,

the core is produced by applying the core sand on the outer surface of the inner element, preferably by inserting the inner element into a core sleeve and shooting the core sand,

-placing the core in a casting mould, preferably a sand casting mould,

-encapsulating the core with a melt,

-finally forming and removing the core sand, wherein the core sand is between the outer surface of the inner element and the inner surface of the outer element made of casting.

The tubular hollow bodies connected to one another to form the inner element preferably have a sleeve connection and are preferably plugged together. Whereby they have the possibility to move axially relative to each other in dependence of temperature changes.

Preferably, a core sand is arranged on the outer surface of the inner element, which makes it possible to form an air gap between the inner element and the outer element made of cast material.

The core consisting of the inner element and the surrounding core sand is placed in a casting mould, preferably a sand casting mould. Subsequently, the casting mold is filled with melt and the core is encapsulated, wherein the melt does not contact the internal components at any point.

After cooling, the casting or the vent pipe according to the invention is finally shaped and the core sand is removed.

The core sand is preferably shaken out by an annular gap on the connection piece, which is formed by an air gap between the inner element and the outer element. Thus, no additional openings are required in the outer element consisting of a casting.

Preferably, the inner element has, after the final shaping, the end of the connecting piece of the inner element projecting beyond the outer element, wherein the projecting connecting piece is separated after the final shaping and cooling.

As an advantageous embodiment of the method and device according to the invention, it has been found that an adapter flange is fastened to each connection piece. Advantageously, the adapter flange is welded to the socket of the inner element. For increased stability, the outer element preferably has a cast flange, against which the adapter flange rests and in turn serves to ensure an air gap between the inner element and the outer element.

All possible designs can be freely combined with one another and the features mentioned with respect to the device can be freely combined with the features mentioned with respect to the method or vice versa.

Drawings

An embodiment of the invention will be described with the aid of the accompanying drawings, wherein the invention is not limited to the embodiment described. Wherein:

figure 1 shows a three-dimensional view of an air-gap insulated vent elbow according to the present invention,

figure 2 shows a plan view of an air-gap insulated exhaust elbow according to the present invention,

figure 3 shows a longitudinal section through an air-gap-insulated vent elbow according to the invention,

figure 4 shows a three-dimensional view of the internal components of the exhaust elbow according to the invention,

figure 5 shows a plan view of the inner element of the vent elbow according to the invention in a sectioned core sleeve,

figure 6 shows a plan view of the core,

figure 7 shows a longitudinal section through the core,

figure 8 shows a longitudinal section through a mould with a core placed in,

FIG. 9 shows a longitudinal cross-section of the vent elbow after final forming and core sand removal, and

FIG. 10 shows a three-dimensional view of the vent elbow after final forming and removal of the core sand.

List of reference numerals:

1 air-gap isolated exhaust elbow;

2 internal components;

3 an external element;

4 a tubular hollow body;

5, an air gap;

6 the outer surface of the inner element;

7 an inner surface of the outer element;

8, a sleeve connecting piece;

9 an inlet connecting pipe;

10 an outlet connecting pipe;

11, a flange;

12 an adaptor flange;

13 a spacer element;

14 an annular gap;

15 core sleeve/mold for core sand;

16 female moulds for core sand;

17 a core;

18-core sand;

19 a negative mold for casting the material;

20, casting a mould;

21 the projecting end of the nipple;

22 inner surface of the inner element.

Detailed Description

Fig. 1 to 3 show an air-gap-insulated exhaust manifold 1 according to the invention. The illustrated exhaust manifold 1 has a plurality of inlet connection pieces 9 and an outlet connection piece 10, wherein the illustrated embodiment can only be seen as a possible embodiment and the exhaust manifold according to the invention can also have other embodiments. The air-gap-insulated exhaust manifold 1 has an inner element 2, wherein the inner element 2 is formed by at least two tubular hollow bodies 4. The hollow body 4 is a tube preferably having a plurality of branches. The hollow bodies 4 connected to one another to form the inner element 2 are preferably not of identical design but have different branching. The tubular hollow body 4 is made of sheet metal, preferably steel sheet. The hollow bodies 4 preferably have a sleeve connection 8 for their mutual displaceability, which sleeve connection is visible in fig. 3. The sleeve connection 8 is preferably formed by an expanded pipe end on one end of the hollow body 4 and an undeformed pipe end inserted into the expanded pipe end. Furthermore, the exhaust manifold 1 has an outer element 3, wherein the outer element 3 is separated from the inner element 2 by an air gap 5. The outer element 3 is formed as a one-piece casting and surrounds the inner element 2. As can be clearly seen in fig. 3, the outer element 3, which is made of a casting, does not touch the inner element 2 anywhere. The adapter flange 12, which is preferably mounted only after the end of the casting process, serves to achieve a separation between the inner element 2 and the outer element 3 and to keep the air gap 5 constant. Since direct contact between the inner element 2 and the outer element 3 is avoided, no direct heat transfer takes place from the hot inner element 2 through which the hot exhaust gas flows to the outer element 3. Thus, there is no direct contact between the outer surface 6 of the encapsulated or cast-in inner element and the inner surface 7 of the outer element consisting of the casting. That is, the hot exhaust gases flowing through the inner element 2 only contact the inner surface 22 of the inner element 2, thereby avoiding direct contact between the hot exhaust gases and the outer element 3, whereby said outer element 3 is heated less. Preferably, a spacer element 13 can be arranged between the outer surface 6 of the inner element 2 and the inner surface 7 of the outer element 3 for ensuring an air gap 5 between the

elements

2, 3.

Fig. 4 shows the inner element 2 before further processing into the exhaust manifold 1 according to the invention. The inner element 2 has at least two tubular hollow bodies 4, which are made of sheet metal. The tubular hollow bodies 4 are connected to one another in a movable manner, wherein they are preferably connected to one another in an axially movable manner in order to thereby take into account heating and cooling of the exhaust manifold, and they can expand and contract or move relative to one another accordingly. The connection of the hollow bodies 4 is preferably effected by a sleeve connection 8, wherein other types of connections which allow an elongation or a shortening of the inner element 2 or of the hollow body 4 can also be considered. The inner element 2 is then placed into a mould or core sleeve 15, which can be seen in fig. 5. The core sleeve 15 has a negative shape or negative Form of the core, into which core sand 18 is filled and which forms the core 17 together with the inner element 2. Fig. 6 shows the shaped core 17 together with the surrounding core sand 18, which acts as a seat for the air gap 5. The core sand 18 surrounds the outer surface 6 of the inner element 2, as can be clearly seen in fig. 7.

As a further step, the core 17 is placed in a casting mould 20. As can be seen in fig. 8, the female shape 19 of the outer element 3 in the mould 20 is depicted and thus a gap is formed between the outer surface of the core 17 and the sand in the mould 20, which gap is filled with casting material and thus forms the outer element 3. A cast melt is then injected into the casting mould 20, which spreads around the core 17 and thus forms the outer element 3. After the melt has solidified, the vent elbow is finally formed or demolded from the mold 20. The core sand 18, which is still located between the outer element 3 and the inner element 2, is preferably shaken or shaken out of the exhaust manifold 1. As can be seen in fig. 9, the core sand 18 can flow out through the annular gap 14. An air gap 5 is then present between the inner element 2 and the outer element 3 as a result of the removal of the core sand 18, which air gap ensures the insulation of the exhaust manifold 1. Subsequently, the projecting ends 21 of the

nipples

9, 10 of the inner element 2 are separated. Also visible in fig. 10 are possible spacer elements 13 which have been placed on the core 17 when they are needed. The adapter flange 12 is fixed to the

connection piece

9, 10. The adapter flange 12 is preferably welded to the

connection pieces

9, 10 of the inner element 2. Advantageously, the outer element 3 is designed in such a way that it has flanges formed on the

connection pieces

9, 10, which are integral parts of the one-piece outer element 3 made of a cast part, so that the adapter flange 12 can be placed thereon and a high stability of the vent pipe according to the invention is ensured, as can be seen clearly from fig. 1 to 3.

Claims

1. Air-gap-insulated exhaust manifold (1) for an internal combustion engine in a motor vehicle, comprising an inner element (2) and an outer element (3), wherein the inner element (2) has at least two tubular hollow bodies (4) made of sheet metal, wherein the hollow bodies (4) are movably connected to one another, wherein the outer element (3) is spaced apart from the inner element (2) by an air gap (5), wherein the outer element (3) is designed as a one-piece casting, characterized in that no direct contact exists between the inner element (2) and the outer element (3).

2. Air-gap insulated exhaust elbow (1) according to claim 1, characterized in that there is no direct contact between the outer surface (6) of the encapsulated/cast-in inner element (2) and the inner surface (7) of the outer element (3) consisting of a casting.

3. Air-gap insulated exhaust elbow (1) according to any one of claims 1 or 2, characterized in that exhaust gases flowing through the exhaust elbow (1) are in contact with the inner surface (22) of the inner element (2) only.

4. The air-gap-insulated exhaust manifold (1) according to one of claims 1 to 3, characterized in that the tubular hollow body (4) is made of steel sheet.

5. The air-gap-insulated exhaust manifold (1) according to one of claims 1 to 4, characterized in that the outer element (3) is composed of cast iron, preferably ductile cast iron.

6. The air-gap-insulated exhaust manifold (1) according to one of claims 1 to 5, characterized in that the tubular hollow bodies (4) of the inner element (2) are connected to one another in a movable manner by means of a sleeve connection (8).

7. Air-gap-insulated exhaust elbow (1) according to one of the claims 1 to 6, characterized in that a spacer element (13) is arranged on the outer surface (6) of the inner element (2).

8. Method for manufacturing an air-gap insulated vent elbow (1), preferably according to any of claims 1 to 7, wherein the method has the following steps:

-manufacturing an inner element (2), wherein for this purpose at least two tubular hollow bodies (4) made of sheet metal are movably connected to each other,

-producing a core (17) by applying a core sand (18) on the outer surface (6) of the inner element (2), preferably by placing the inner element (2) into a core sleeve (15) and shooting the core sand (18),

-placing the core (17) in a casting mould (20), preferably a sand casting mould,

-encapsulating the core (17) with a melt,

-finally forming and removing the core sand (18), wherein the core sand (18) is between the outer surface (6) of the inner element (2) and the inner surface (7) of the outer element (3) consisting of a casting.

9. Method for manufacturing an air-gap-insulated exhaust manifold (1) according to claim 8, characterized in that the core sand (18) is shaken out by an annular gap (14) on the connection piece (9, 10) which is formed by the air gap (5) between the inner element (2) and the outer element (3).

10. Method for producing an air-gap-insulated vent bend (1) according to one of claims 8 or 9, characterized in that the ends (21) of the connecting pieces (9, 10) of the inner element (2) which protrude beyond the outer element (3) are separated.

11. Method for producing an air-gap-insulated vent bend (1) according to one of claims 8 to 10, characterized in that a respective adapter flange (12) is fastened to each adapter tube (9, 10).