EP2207950B1 - Exhaust gas manifold for internal combustion engines - Google Patents

Abstract

The invention relates to an airgap-insulated exhaust gas manifold (10) for internal combustion engines. The exhaust gas manifold (10) according to the invention comprises three components: an outer shell (20), an inner shell (30), and a flange (11) joined to the internal combustion engine. The outer shell (20) and the inner shell (30) are each designed in the shape of a hood and each comprise a circumferential collar (22, 32), wherein the outer shell collar (22'') is connected to the flange (11) and the inner shell collar (32) is in turn clamped between the outer shell collar (22') and the flange (11). In order to effect said clamping, a plurality of knob- or wave-shaped bulges (33) are formed on the inner shell collar (32) that rest in points against the outer shell collar (22') or the flange (11). Said clamping does not interfere with the heat expansion of the inner shell (30) parallel to the flange (11) when in the operational state.

Description

Technical area:

The invention relates to air gap-insulated exhaust manifolds for internal combustion engines according to the preamble of claim 1.

State of the art:

Air gap insulated exhaust manifolds essentially comprise a manifold for the engine exhaust, consisting of an inner and an outer shell construction, which are isolated from each other by an air gap. This collecting housing is also provided with a plurality of flanges, which connect to the corresponding outlets of the cylinder head of the internal combustion engine. Air gap insulated exhaust manifolds are prior art, especially in motor vehicles equipped with catalytic converters. This is where air gap insulated exhaust manifolds set out DE 101 02 637 are known, with their inherent advantages: on the one hand with their low "thermal mass" by a thin-walled as possible design of the gas-conducting inner shell (less than 1 mm), on the other hand with their low heat losses, due to acting as additional heat insulation air gap between indoor and outer shell.

A catalyst requires a relatively high minimum temperature in order to efficiently carry out the exhaust gas conversion. This so-called light-off temperature is about 250 ° C. Thus, the hot exhaust gases flowing from the cylinder chamber into the exhaust manifold after engine starting, which are then forwarded for conversion into the catalyst, are themselves the only heat source for activating the catalyst. Advantageously, the thin-walled wall panel of the inner shell structure in the exhaust manifold quickly reaches the exhaust gas temperature of up to 900 ° C, without withdrawing the exhaust gas flow significantly heat. Furthermore, advantageously, the heat losses to the outer shell and thus finally kept small in the engine compartment by the insulating acting air gap. The outer shell of the exhaust manifold does not exceed a temperature of 500 ° C even during prolonged engine operation.

Critical areas for unwanted heat losses on the inner shell and thus also heat losses of the exhaust gas flow are the areas where the inner shell in direct contact with the colder outer shell and especially the considerable colder flanges, which are approximately the temperature of the water-cooled cylinder head of max. 120 ° C is located. The reason for this is that in these areas the heat transfer takes place by heat conduction. From the warmer inner shell, the heat flows by transferring the kinetic energy of the atoms to the colder outer shell, or to the colder flanges. This way of heat transfer between solids by heat conduction is considerably (about a factor of 1000) stronger than the heat transfer by convection (= transition to the flowing medium) and by thermal radiation, which are responsible for the heat losses in the other areas of the inner shell surrounded by the air gap , On the other hand, such contact areas are unavoidable because you have to fix the inner shell structure for stability reasons and they can not use loosely in the outer shell structure. In this case, an attachment of the inner shell without rattling noises and without play important to eliminate unwanted vibrations, which will become an additional noise emission source. Consequently, care must be taken to effectively fix the inner shell in the exhaust manifold.

This fixation happens as in the DE 100 01 287 A1 described and illustrated in the accompanying Fig. 13, characterized in that the inner shell between the outer shell and the connection flange is clamped, wherein the clamping force is applied by the fastening elements, which are responsible for the attachment of outer shell and flange on the cylinder head. In the EP 0 671 551 A1 the clamping of the inner shell in the flange is effected by the inherent elasticity of the inner shell, the edge of which bears against the outer shell under pressure.

1. 1. Ein Abgassammelgehäuse zur Aufnahme von Abgas aus dem Zylinderkopf.
2. 2. Einen innerhalb des Abgassammelgehäuses angeordneten Gasführungskanal.
3. 3. Zwischen dem Abgassammelgehäuse und dem Gasführungskanal befindet sich ein Luftspalt.
4. 4. Zwischen dem Abgassammelgehäuse und dem Zylinderkopf ist eine Dichtung angeordnet.
5. 5. Das Abgassammelgehäuse weist Öffnungen auf, durch welche es mit dem Zylinderkopf verschraubt wird.
6. 6. Der Gasführungskanal ist an seiner dem Zylinderkopf zugewandten Seite mit einem über wenigstens annähernd seinen gesamten Umfang umlaufenden Bund versehen, welcher zumindest mittelbar zwischen dem Abgassammelgehäuse und der Dichtungseinrichtung oder dem Zylinderkopf eingeklemmt ist.
7. 7. Das Abgassammelgehäuse oder ein gegebenenfalls zwischen dem Abgassammelgehäuse und der Dichtungseinrichtung angeordnetes Niederhalterelement weist einen umlaufenden Rücksprung auf, in welchem der umlaufende Bund des Gasführungskanals derart geführt ist, dass zwischen dem Gasführungskanal und der Dichtungseinrichtung und/oder zwischen dem Gasführungskanal und dem Abgassammelgehäuse durch Wärmeeinwirkung hervorgerufene Bewegungen möglich sind.

From the WO02 / 07301 A2 an exhaust manifold for attachment to a cylinder head of an internal combustion engine is known, which has the following features:

1. 1. An exhaust manifold for receiving exhaust gas from the cylinder head.
2. 2. An arranged within the exhaust gas collection housing gas guide channel.
3. 3. There is an air gap between the exhaust manifold housing and the gas duct.
4. 4. Between the exhaust manifold and the cylinder head, a seal is arranged.
5. 5. The exhaust manifold has openings through which it is bolted to the cylinder head.
6. 6. The gas guide channel is provided on its side facing the cylinder head with a circumferential over at least approximately its entire circumference collar, which is at least indirectly clamped between the exhaust gas collecting housing and the sealing device or the cylinder head.
7. 7. The exhaust manifold or optionally disposed between the exhaust manifold and the sealing device hold-down element has a circumferential recess in which the circumferential collar of the gas duct is guided such that between the gas duct and the sealing device and / or between the gas duct and the exhaust manifold by heat caused movements are possible.

All three constructions have the disadvantage that the movements of the inner shell structure caused by the effect of heat are granted no clearance or no clearance which can be controlled efficiently. In the DE 100 01 287 A1 it is assumed that the clamping can be controlled by different tightening the screws so that the thermal expansion of the inner shell is not hindered. This does not seem practical, because the torque of the cylinder head bolts must be chosen so large in any case, that the exhaust manifold sits on the engine block with absolute exhaust gas tightness. In the EP 0 671 551 A1 the thermal expansion of the inner shell is not taken into account. During the heating and cooling phases at engine start and stop voltages are induced in the inner shell structure, which could affect the tightness of the clamp in this construction, since here virtually self-locking the inherent elasticity of the inner shell is responsible for the pressure against the outer shell and thus for the Gas-tightness of the inner shell structure.

The situation is similar with the construction of the WO02 / 073010 A2 , As here made of stable sheet metal inner gas duct between the also made of sturdy sheet metal outer exhaust manifold and the cylinder head is clamped, whereby the clamping force as in the DE 100 01 287 A1 depends on the accuracy of the sheet metal processing in the manufacture of exhaust manifold and gas duct. In addition, the inner gas duct is composed of two shell parts, whereby the manufacturing cost increases and the weight can be increased. That is undesirable.

Presentation of the invention:

The present invention has for its object to construct an exhaust manifold so that the inner shell for a fixed, that is stored vibration-free and that on the other hand, the thermal expansion of the inner shell relative to the flange and outer shell, especially in the temperature changes in the phase shortly after Start and stop of the engine, is made possible without these thermal expansions have a negative impact on the vibration-free mounting of the inner shell.

According to the invention, this object is achieved by the features mentioned in claim 1.

Advantageous developments emerge from the subclaims.

An essential advantage of the exhaust manifold according to the invention is that it consists of only three components: the flange, a hood-shaped outer shell, which is connected via its peripheral collar with the flange, and an inner shell, which has the same hood-shaped shell shape as the outer shell and with her Collar between the collar of the outer shell and the flange is clamped. Characteristic feature of the present invention is that the inner shell is clamped by bulges along its collar surface between the outer shell and the flange in a fixed, defined position. So there are no other parts such as fasteners or sealing devices necessary. The outer shell is welded or soldered to the flange. In the case of soldering the flange is formed as a sheet metal part, which is crimped at the edges around the edge of the outer shell.

Brief description of the drawings:

Fig. 1

eine Isometrieansicht des Abgaskrümmers,

Fig. 2

einen Querschnitt durch den Abgaskrümmer der Fig. 1,

Fig. 3

einen Querschnitt durch den Abgaskrümmer der Fig. 1 gemäß einer zweiten Ausführungsform,

Fig. 4

einen Querschnitt durch den Abgaskrümmer der Fig. 1 gemäß einer dritten Ausführungsform,

Fig. 5

einen Längsschnitt durch den Abgaskrümmer der Fig. 4 entlang der Linie IV-IV in Fig. 4,

Fig. 6

einen Querschnitt durch den Abgaskrümmer der Fig. 1 gemäß einer vierten Ausführungsform,

Fig. 7

einen Querschnitt durch eine fünfte Ausführungsform,

Fig. 8

einen Querschnitt durch eine sechste Ausführungsform,

Fig. 9

einen Längsschnitt durch den Abgaskrümmer der Fig. 8 entlang der Linie IX-IX der Fig. 8 und

Fig. 10

einen Querschnitt durch eine siebte Ausführungsform.

Reference to the drawings, the invention will be explained in more detail in the form of various embodiments. Show it

Fig. 1

an isometric view of the exhaust manifold,

Fig. 2

a cross section through the exhaust manifold of Fig. 1 .

Fig. 3

a cross section through the exhaust manifold of Fig. 1 according to a second embodiment,

Fig. 4

a cross section through the exhaust manifold of Fig. 1 according to a third embodiment,

Fig. 5

a longitudinal section through the exhaust manifold of Fig. 4 along the line IV-IV in Fig. 4 .

Fig. 6

a cross section through the exhaust manifold of Fig. 1 according to a fourth embodiment,

Fig. 7

a cross section through a fifth embodiment,

Fig. 8

a cross section through a sixth embodiment,

Fig. 9

a longitudinal section through the exhaust manifold of Fig. 8 along the line IX-IX of Fig. 8 and

Fig. 10

a cross section through a seventh embodiment.

Ways to carry out the invention and industrial applicability:

The Fig. 1 shows an isometric view of an exhaust manifold, the Fig. 2 to 8 show in each case in the form of longitudinal or cross sections different embodiments of the positionally fixed attachment of the inner shell in the region between the outer shell and the flange.

At all in the Fig. 2 to 10 In the illustrated embodiments, the basic structure of three basic components is always the same: A flange 11, which is attached to a cylinder head, not shown, of the internal combustion engine is covered on the gas outlet side with a gas-tight outer shell 20, in turn, an inner shell 30 is introduced. The design of the outer shell 20 does not change. It is formed of sheet metal (eg 2 mm wall thickness) and consists of a hood-shaped upper part 21, to which a circumferential collar 22 connects, which is connected to the flange 11. The design of the outer shell collar 22 is also a characteristic feature of the present invention: it consists of a directly adjacent to the hood-shaped sheet metal upper part 21, inner collar segment 22 ', which extends parallel to the surface of the flange 11, and from a via an oblique Sheet segment 23 subsequent, outer collar segment 22 ", which rests on the flange 11, and is connected to it by welding or soldering.

The inner shell 30 has in its hood-shaped upper part 31 the same contour as the upper part 21 of the outer shell 20, with the obvious difference that it is due to their smaller dimensions at a distance of an air gap within the upper part 21 of the outer shell 20. The inner shell collar 32 lies in all embodiments according to the FIGS. 2 to 10 in the air gap between inner outer shell collar 22 'and flange 11. The embodiments in the Fig. 2 to 10 differ only in the geometry of the inner shell collar 22, the design of the flange 11 and in the introduction of additional clamping or guide elements in the waistband area (wire rings 40 and additional sheet 50).

These embodiments will now be explicitly addressed:

Fig. 2 shows an exhaust manifold 10 in cross-section, which has an inner shell 30, the collar 32 rests on the flange 11 and projects into the air gap between the inner outer shell collar 22 'and flange 11. The firm clamping of the inner shell is achieved in that the inner shell collar 32 on its outer edge from the collar surface upwards in the direction of the inner outer shell collar 22 'exiting bulges 33 which rest on the inner outer shell collar 22' punctiform under pressure. In this way, the inner shell 30 between the outer shell 20 and flange 11 is firmly clamped punctiform. The hot gases emerging through the flange opening 13 from the cylinder, not shown, cause a thermal expansion of the gas-carrying inner shell 30. This thermal expansion remains advantageous in a flange-parallel direction between the inner outer shell collar 22 'and flange 11 continues to be possible without deteriorating the dimensionally stable clamping of the inner shell , The bulges are not formed as a continuous gutter / bead, but knob-shaped with individual elevations that press against the outer shell 20, but these touch only selectively, so that the contact surfaces and the heat loss flowing through heat losses of the inner shell 20 are kept as small as possible.

Fig. 3 shows a modification of the in Fig. 2 illustrated inner shell construction. The inner shell collar 32 rests against the inner outer shell collar 22 'and the bulges 33 on the edge of the inner shell collar 32 are consequently formed on the lower side, the flange side, in the form of a nub in punctiform contact with the flange 11. In this construction, it should be mentioned that exhaust gas could flow into the air gap between the inner outer shell collar 22 'and the flange 11 from the gas-carrying inner shell 30 through the intermediate space between the bulges 33. However, there is no pressure gradient and therefore these flow and heat losses are negligible.

Advantage of this design but is the small contact area between the inner shell 30 and outer shell 20 and flange eleventh

Fig. 4 shows an embodiment in which the inner shell collar 32, without an unfavorable wide bearing surface with outer shell 30 or flange 11 to form, is placed centrally in the air gap between the inner outer shell collar 22 'and flange 11. The positionally fixed support of the inner shell 30 is achieved in that the bulges 33 are formed on both sides of the edge of the inner shell collar 32 and so fix the inner shell 30 by punctiform support on the inner outer shell collar 22 'and the flange 11. This design is particularly loss, because here surface-like bearing surfaces between inner shell collar 32 and flange 11 and inner outer shell collar 22 'are not present, but the inner shell 30 is fixed only by punctiform support pads on the bulges 33 at the edge of the inner shell collar 32. Again, in principle, a passage of the exhaust gases from the gas-carrying inner shell 30 in the air gap between the inner 30 and outer shell 20 is possible. However, this passage will be negligible due to the lack of or low pressure gradient in relation to the pressure difference prevailing along the secondary exhaust pipe.

Fig. 5 shows a longitudinal section along the line IV-IV through the bulges 33 of the inner shell collar of Fig. 4 , The bulges 33 are distributed uniformly wave-shaped at the edge of the inner shell collar 32 and are supported at the top of the outer shell collar 22 'and at the bottom of the flange 11.

Fig. 6 shows the cross section of another embodiment of the exhaust manifold 10. The inner shell collar 32 is as in the embodiment in Fig. 3 represented on the inner outer shell collar 22 'on. The bulges 33 of the inner shell collar 32 are as in Fig. 3 nubbed down, formed against the surface of the flange 11, but not at the edge of the inner shell collar 32 but slightly indented, so that the bulges 33 still follows a straight, undeformed collar segment, the inner outer shell collar 22 'is applied. However, between the outer end of the inner shell collar 32 and the outer outer shell collar 22 'is still enough space to allow the thermal expansion of the inner shell 30 in this area unhindered.

Fig. 7 shows a structure similar to that in FIG Fig. 6 illustrated embodiment. However, the bulges 33 do not extend to the surface of the flange 11. The fixed clamping of the inner shell 30 is achieved by wire rings 40 which are inserted between inner shell collar 32 and flange 11. The wire rings 40 are like this inserted, that the bulges 33 of the inner shell collar 32 are located between them, so that the wire rings 40 are thereby fixed in the transverse direction. The inner shell 30 is thus not clamped directly between the flange 11 and outer shell collar 22, but indirectly between the resting on the flange 11 wire rings 40 and the outer shell collar 22. The bulges 33 of the inner shell collar 32 act in this embodiment as guides for the wire rings 40th Die Drahtringe 40 serve not only as Verklemmungselemente for the inner shell 30 but also as guide elements along which the inner shell 30 can slide in thermal expansion. Another advantage is that the contact surface and consequently also the associated heat losses between wire rings 40 and gas-carrying inner shell 32 is small.

Fig. 8 shows the cross section of another embodiment, according to the embodiment according to Fig. 4 the protrusions 33 unfolding the clamping action of the inner shell collar 32 are formed on both sides. However, in this embodiment, the bulges 33 are formed at a distance from the edge of the inner shell collar 32 and the bulges 32 is still followed by a straight undeformed part of the inner shell collar 32. The flange 11 is here as the shells 20, 30 of the exhaust manifold 10 formed as a sheet metal part. The sheet metal of the flange 11 is crimped at its edges around the outer collar 22 'of the outer shell 20. This flanging has the advantage that flange 11 and outer shell 20 are held together, and that a soldering of the outer shell 20 with the flange 11 along the outer outer shell collar 22 'is possible. In addition, the sheet metal design of the flange 11 offers the advantage that the opening 13 of the flange 11 can be bent upwards into the exhaust manifold 10, wherein the diameter of the flange opening 13 easily merges, similar to a nozzle. This nozzle-like shape of the flange opening 13 offers the advantage that the heat of the exhaust gas is quickly led away from the flange 11. This causes a reduction of the heat losses, because the flange temperature is considerably lower than the exhaust gas temperature of up to 900 ° C at about 120 ° C, because the flange 11 is mounted on the (not shown) cylinder head. This is like the entire engine block water cooled and exceeds temperatures of max. 120 ° C not.

Fig. 9 represents a longitudinal section along the line IX-IX through the bulges 33 of the inner shell collar 32 in Fig. 8 The bulges 33 of the inner shell collar 32 are designed here uniformly wave-shaped and are supported alternately upwards against the inner outer shell collar 22 'and down against the sheet-formed Flange 11 from. These protrusions 33 are always in contact only via small, almost punctiform zones with outer shell 20 and flange 11. Consequently, the heat losses by heat conduction remain low.

Fig. 10 shows the cross section of a further embodiment in which the bulges of the inner shell collar 32 at a distance from the edge and on one side up against the inner outer shell collar 22 'are formed. However, the inner shell collar 32 is not on the underside on the flange 11, but is guided centrally in the air gap between the inner outer shell collar 22 'and flange 11. The fixed position clamping is achieved by an additional plate 50 which is inserted between inner shell collar 32 and flange 11. However, this additional sheet 50 is also not over its entire surface on the relatively cold flange 11, but is by a similar shape design as the inner shell collar 32 only in punktförmigem contact with the flange 11. For this purpose, the additional sheet 50 everywhere, where the Inner shell collar 32 bulges 33, also bulges 52, which are opposite in mirror image. The additional sheet 50 has an opening 51 which coincides with the nozzle diameter of the flange opening 13. Thus, the edge surface of the opening 51 of the additional sheet 50 is flush with the inwardly tapered plate of the flange opening 13. The position-resistant clamping of the inner shell 30 thus takes place between the contact points of the bulges 33 of the inner shell collar 32 on the inner outer shell collar 22 'and the support of the inner shell collar 32 on the additional sheet 50. Although the inner shell collar 32 rests almost entirely on the additional sheet 50, the heat losses are still low because the additional sheet 50 in turn is only about its bulges 52 and the edge surface of its inner opening 51 with the cooler flange 11 in touch. A further advantage of this embodiment is that between additional sheet 50 and flange 11, a further air gap 60 is formed, which isolates the flowing through the flange opening 13 hot exhaust gas stream (temperature at about 900 ° C) from the surface of the flange 11. This is particularly advantageous because the flange 11 remains relatively cool even in the operating condition of the engine, as it is flatly mounted on the water-cooled cylinder block (temperature up to 120 ° C). As a result, the undesired heat losses of the exhaust gas flow are further reduced by this embodiment.

Claims (14)

1. An air-gap insulated exhaust gas manifold (10) for internal combustion engines,
   at least comprising

   - a flange (11) with

   - openings (12) for fastening elements

   - and cylinder ports (13) which are in alignment with the cylinder exhaust ports of the internal combustion engine,

   - a gas-tight outer shell (20) with

   - a hood-shaped upper part (21)

   - and a circumferential outer shell collar (22) arranged parallel to the flange (11), which outer shell collar is connected to the flange (11),

   - and an inner shell (30) with

   - a hood-shaped upper part (31)

   - and a circumferential inner shell collar (32) arranged parallel to the flange (11), which inner shell collar is clamped between the outer shell collar (22) and the flange (11),

   characterised in that

   - the circumferential outer shell collar (22) is formed of two collar segments which are offset parallel to one another:

   - an internal outer shell collar (22') directly extending from the hood-shaped upper part (21) of the outer shell (20), which internal outer shell collar extends at a parallel distance from the surface of the flange (11),

   - and an external outer shell collar (22") which rests on the surface of the flange (11),

   - wherein internal and external outer shell collars (22', 22") are connected via a slope (23),

   - and that the circumferential inner shell collar (32)

   - is arranged between the internal outer shell collar (22') and the flange (11)

   - and has bulges (33) emerging from its collar surface extending parallel to the flange, which bulges rest in points against the surface of the internal outer shell collar (22') and/or against the surface of the flange (11) under elastic pressing and thus effect a fixed clamping of the inner shell (30) without any additional fastening means, wherein the thermal expansion of the inner shell collar (32) in the plane parallel to the flange (11) is not restricted by the clamping.
2. An exhaust gas manifold according to claim 1, characterised in that the bulges (33) of the inner shell collar (32) are formed on one side.
3. An exhaust gas manifold according to claim 1, characterised in that the bulges (33) of the inner shell collar (32) are formed on both sides.
4. An exhaust gas manifold according to claim 1 or 3, characterised in that the bulges (33) have a uniform wave-like shape, as seen in the longitudinal section, and, under elastic pressing, the inner shell collar (32) rests in points alternately upwardly against the internal outer shell collar (22') and downwardly against the flange (11).
5. An exhaust gas manifold according to any one of claims 1 to 4, characterised in that the bulges (33) of the inner shell collar (32) are at its outer edge.
6. An exhaust gas manifold according to any one of claims 1 to 4, characterised in that the bulges (33) of the inner shell collar (32) are at a distance from its outer edge.
7. An exhaust gas manifold according to claim 6, characterised in that wire rings (40) are placed between inner shell collar (32) and flange (11) and/or between inner shell collar (32) and internal outer shell collar (22'), wherein the bulges (33) of the inner shell collar (32) are within the wire rings (40).
8. An exhaust gas manifold according to claim 6, characterised in that an additional sheet metal (50) is placed between inner shell collar (32) and flange (11), with:

   - openings (51) which match the openings (13) of the flange (11)

   - and bulges (52) which are formed as mirror images of the bulges (33) of the inner shell collar (32),

   such that, under elastic pressing, the bulges (52) of the additional sheet metal (50) rest in points against the flange (11) and the opposite bulges (33) of the inner shell collar (32) rest in points against the internal outer shell collar (22').
9. An exhaust gas manifold according to claim 8, characterised in that the bulges (52) of the additional sheet metal (50) correspond to the bulges (33) of the inner shell collar (32) in number and position.
10. An exhaust gas manifold according to claim 8 or 9, characterised in that an air-gap (60) exists between additional sheet metal (50) and flange (11), which air-gap insulates the flange (11) from the hot exhaust gases.
11. An exhaust gas manifold according to any one of claims 1 to 10, characterised in that the flange (11) is formed as a cast part and the connection between the outer shell (20) and the flange (11) is welded along the external outer shell collar (22").
12. An exhaust gas manifold according to any one of claims 1 to 10, characterised in that the flange (11) is formed as a sheet metal part and flanged around the rim of the external outer shell collar (22").
13. An exhaust gas manifold according to claim 12, characterised in that the flange (11) is brazed to the external outer shell collar (22").
14. An exhaust gas manifold according to claim 12 or 13, characterised in that the rims of the cylinder ports (13) of the flange (11) are bent into the exhaust gas manifold (10) in the manner of a nozzle.

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