EP0395540A1 - Modular silencer - Google Patents

Abstract

The silencer according to the invention comprises an outer casing (1) formed by assembling a first casing element (14) and a second casing element (15), each formed from a continuous wall comprising a tubular axial part and a radial end part (3, 4). The elements (14, 15) are obtained by deep drawing. They are assembled together axially by peripheral welding (33) on the intermediate peripheral connecting zone (30) formed by their two edges (17, 32) laid against one another and bearing on an inner supporting piece (13). <IMAGE>

Description

The present invention relates to a range of silencers for internal combustion engines, usable in particular on vehicles such as cars and motorcycles.

A large number of silencers for internal combustion engines are already known. They generally comprise an outer envelope forming a closed enclosure, pierced with at least two orifices allowing respectively the entry and exit of the exhaust gases and suitable for the connection of an inlet tube and an outlet tube leading gas. The closed envelope contains means for the expansion of the exhaust gases and their conduction between the inlet and outlet orifices.

The most commonly used envelope structure, described for example in document US-A-3 337 939, comprises a tubular peripheral side wall developing longitudinally along a longitudinal axis, said peripheral side wall connecting at its ends to two transverse end walls to which it is connected by a peripheral crimp forming a bead. Such a structure has the drawback of a relatively short service life, due in particular to the presence of the peripheral crimp connection between the side wall and the end walls, which crimping is provided in an area forming a corner in which develop chemical reactions gradually attacking the metal forming the envelopes. On the other hand, the external profile of such a silencer, having peripheral beads, leads to an increase in the overall diameter of the silencer, at given internal volume, and this results in a reduction in the useful volume compared to the total external volume. , and a decrease in efficiency. Also, this silencer structure is not suitable for the production of a range of silencers of different sizes: to produce two silencers of different lengths, it is necessary to provide longitudinal tubular peripheral casings of different lengths.

Another silencer structure is described in document FR-A-2 467 974. In this document, the silencer is made up of an outer protective casing comprising two semi-cylindrical half-shells connecting according to two flattened terminal generators, the corresponding generators being assembled by crimping and thus forming two diametrically opposite beads occupying the entire length of the silencer. The external lateral beads increase the size of the silencer, with equal internal volume. In addition, to make a range of silencers of different lengths, it is necessary to provide each time with half-shells of the total length of each silencer. This structure is therefore not suitable for producing a range of silencers of different lengths.

The object of the present invention is in particular to avoid the drawbacks of these traditional silencer structures, by proposing a new structure which, using a limited number of standard elements, makes it possible to produce silencers whose lengths are different. We seek, for this, to adapt axially end to end a greater or lesser number of different unit elements, to produce silencers whose diameters are substantially identical but whose lengths depend on the number and structure of the assembled elements.

Silencer structures are already known which are produced by axial end-to-end assembly of at least two unit elements, each unit element being formed by an axial peripheral side wall limited at its first end by a sharp annular edge and connecting to its second. end to a radial part constituting a transverse end wall of the silencer. These structures are described in particular in documents US-A-2 205 024, DE-C-402 357, DE-A-2 623 153, US-A-3 670 845.

It turns out that a structure as described in document US-A-2 205 024 is difficult to produce, because the two straight edges of the two parts to be assembled are not guided by any guide means during their assembly. This results in welding defects, and a great complexity of manufacturing.

The documents DE-C-402 357, DE-A-2 623 153 and US-A-3 670 845 teach an assembly by means of an external sleeve coming to cap externally the two edges of the elements to be assembled. This structure is not suitable for assembly by welding, increases the external dimensions of the silencer, and complicates manufacture, without giving satisfactory results from a sealing and mechanical resistance point of view of the assembly.

The object of the invention is therefore to avoid these drawbacks, by proposing a particular structure allowing the edge-to-edge welding of the muffler elements connected axially end to end with respect to each other, the structure of the elements ensuring by itself the guiding of the edges of elements one with respect to the other when welding, so that the edges to be welded to each other are correctly and automatically centered. The weld obtained is of good quality and easy to perform, and the seal is improved.

The invention also makes it possible to internally maintain the two edges to be welded, allowing the application of centripetal forces on the edges during welding, without these forces displacing or deforming them.

The edge guide means according to the invention allow a significant increase in the shape tolerances of the respective edges of the envelope elements, and in particular make it possible to compensate for certain deformations or ovalizations of these edges.

According to certain embodiments of the invention, the means for guiding the edges of elements with respect to one another during welding provide in themselves other functions, such as a function of separating two compartments, or a function of interior maintenance of other elements in the silencer.

The new silencer structure also makes it possible to increase the volume of the envelope with constant external dimensions, in particular by eliminating the peripheral or longitudinal beads which are encountered in traditional structures.

The invention further aims to increase the efficiency of the muffler, and in particular to reduce the noises of expansion of the gases.

An important object of the invention is the increase in the longevity of the silencer, this increase in longevity being obtained by a particular structure reducing the risks of attack of the metal forming the envelope, improving the resistance to vibration, and formed of materials which are susceptible to corrosion.

To achieve these and other objects, the silencer structure according to the invention comprises an outer envelope forming a closed enclosure, comprising:
- At least a first envelope element formed by a continuous wall in which there is a tubular axial part and a radial part, the tubular axial part being limited to its first end by a first frank annular edge, defining a plane substantially perpendicular to the longitudinal axis of the silencer, connecting at its second end to the radial part constituting a first transverse end wall of the silencer,
- At least one second casing element, formed of a continuous wall comprising a tubular axial part constituting a portion of the axial peripheral lateral wall of muffler, the axial part being limited at its first end by a second frank annular edge defining a plane substantially perpendicular to the longitudinal axis of the silencer, of the same shape as said first straight edge, and connecting at its second end to a radial part constituting a transverse wall,
- Said first and second envelope elements being assembled axially to each other in opposition, according to an intermediate peripheral annular connection zone formed by said first and second free edges axially pressed one against the other edge to edge , said envelope elements being secured to one another in a sealed manner along the entire periphery of their connection zone.

The joining of the two envelope elements is preferably carried out by a joining means such as a weld. In line with the intermediate peripheral annular connection zone, an internal part with a cylindrical periphery forms a connection support against which the two internal faces of the closed annular axial parts of the first and second envelope elements are pressed simultaneously in the vicinity of said edges.

The securing means such as a weld can advantageously simultaneously secure the two edges of the first and of the second envelope element and the inner piece forming a support.

According to a preferred embodiment, the first and the second envelope element each constitute a part produced separately by axial forming of a plate material, for example by flow spinning, or embossing, or deep drawing.

The tubular axial part of at least one of the first and second envelope elements comprises an annular constriction in the zone of connection to the radial part. This constriction defines a tubular axial zone of smaller section on which the first open end of another can fit together with little play. envelope element.

• - la figure 1 représente une vue en coupe longitudinale d'un silencieux complet selon un mode de réalisation de l'invention ;
• - la figure 2 est une coupe longitudinale d'un élément d'enveloppe selon la présente invention ;
• - la figure 3 est une coupe longitudinale schématique d'un silencieux selon l'invention, dans un mode de réalisation à deux éléments d'enveloppe ;
• - la figure 4 est un autre mode de réalisation, vu en coupe longitudinale, d'un silencieux selon l'invention à deux éléments d'enveloppe ;
• - les figures 5, 6 et 7 illustrent trois autres modes de réalisation de silencieux selon l'invention à deux éléments d'enveloppe ;
• - la figure 8 illustre un mode de réalisation de l'invention à trois éléments d'enveloppe ;
• - la figure 9 illustre un mode de réalisation de silencieux comprenant un premier élément d'enveloppe de grande longueur, et un second élément d'enveloppe de faible longueur ; et
• - la figure 10 illustre un mode de réalisation de silencieux selon l'invention à quatre éléments d'enveloppe.

Other objects, characteristics and advantages of the present invention will emerge from the following description of particular embodiments, given in relation to the attached figures, among which:

• - Figure 1 shows a longitudinal sectional view of a complete silencer according to an embodiment of the invention;
• - Figure 2 is a longitudinal section of an envelope element according to the present invention;
• - Figure 3 is a schematic longitudinal section of a silencer according to the invention, in an embodiment with two envelope elements;
• - Figure 4 is another embodiment, seen in longitudinal section, of a silencer according to the invention with two envelope elements;
• - Figures 5, 6 and 7 illustrate three other embodiments of the silencer according to the invention with two envelope elements;
• - Figure 8 illustrates an embodiment of the invention with three envelope elements;
• - Figure 9 illustrates an embodiment of muffler comprising a first casing element of great length, and a second casing element of short length; and
• - Figure 10 illustrates an embodiment of muffler according to the invention with four envelope elements.

In the embodiment shown in FIG. 1, the exhaust silencer according to the invention comprises an outer casing 1 forming a closed enclosure, delimited by an axial peripheral side wall 2 developing along a longitudinal axis II. The enclosure is closed at a first end by a first transverse end wall 3, and is closed at its second end by a second transverse end wall 4. In the embodiment shown, the first transverse end wall 3 is pierced with a first orifice 5, and the second transverse end wall 4 is pierced with a second orifice 6. A first end tube 7 fits into the first orifice 5. A perforated inner longitudinal tube 8 adapts, by its first end, in the first end tube 7, and adapts by its second end in the second orifice 6. A second end tube 9 fits into the second end of the inner perforated longitudinal tube 8. Thus, the inner perforated longitudinal tube 8 passes right through the casing 1. The space between the longitudinal tube perforated interior 8 and the outer casing 1 of the silencer is filled with material usually used in the manufacture of silencers, for example a fibrous material 10 such as basalt wool, stainless steel wool, or another fibrous material.

The interior space of the external envelope 1 is divided into two compartments, a first compartment 11 and a second compartment 12, separated by a transverse intermediate wall 13. The transverse intermediate wall 13 connects an intermediate zone of the external envelope 1 and an intermediate zone of the perforated inner longitudinal tube 8, as shown in the figure.

The present invention relates in particular to the structure and shape of the outer casing 1 and the transverse inner wall 13, to fulfill the aims of the invention.

To this end, it can be seen in FIG. 1 that the outer casing 1 is made up of two main parts, namely a first casing element 14 constituting substantially the casing of the first compartment 11, and a second element envelope 15 constituting substantially the envelope of the second compartment 12. The two envelope elements 14 and 15 have the same shape, and this shape is shown in more detail in FIG. 2.

Referring now to this FIG. 2, representing an envelope element 14 according to the invention, it can be seen that the envelope element consists of a continuous wall comprising an axial tubular part 16, intended to form a part of the peripheral wall 2 of the silencer, the axial part 16 being limited at its first end by a frank annular edge 17 situated in a plane 18 substantially perpendicular to the longitudinal axis II of the envelope element. The axial part 16 is connected at its second end to a radial part 19 intended to constitute one of the transverse end walls of the silencer. In the zone of connection to the radial part 19, the tubular axial part 16 comprises an annular constriction 20, as shown in FIG. 2, defining a tubular axial zone 21 of smaller section than the rest of the part axial 16. The tubular axial zone 21 has a section such that another envelope element identical to the element shown in FIG. 2 can come to fit on said tubular axial zone 21 by its open end corresponding to its annular edge 17, the adaptation taking place at low clearance. In other words, the constriction 20 corresponds substantially to the thickness of the wall forming the axial part 16.

The radial part 19 is pseudo-spherical with outwardly convexity, and, in the embodiment shown, comprises an orifice 22 for adapting a gas passage tube. The orifice 22 comprises a protruding tubular lip 23, forming a cylinder with an axis substantially parallel to the longitudinal axis 11. The tubular lip 23 is connected to the radial part 19 by a peripheral zone of particular shape: on at least one portion from its periphery, said peripheral zone forms an external groove 24, formed by the curvature of the wall forming the radial part, as shown in FIG. 2. For example, the groove 24 may have a semicircular section, of equal radius about 5 millimeters. In the embodiment shown, the orifice 22 is off-center with respect to the longitudinal axis I-I of the envelope element. In this case, the groove 24 occupies only part of the periphery of the tubular lip 23, namely the portion close to the longitudinal axis I-I. The outer portion 25, further from the longitudinal axis I-I, is connected by a simple rounding as shown in the figure. The groove 24 constitutes an intermediate deformation zone between the tubular lip 23 and the radial part 19, and allows slight variations in axial orientation of the tubular lip 23 relative to the longitudinal axis I-I. This possibility allows the orientation, over a relatively small but nevertheless sufficient range, of the gas passage tubes with respect to the silencer. These orientation variations make it possible to follow the variations in dimensions due to the heating of the materials during use, heating caused by the hot gases leaving the internal combustion engine.

The presence of the groove 24 makes it possible to use curved end walls 3 and 4, favorable to aerodynamics and to resistance to corrosion, without appreciable loss of volume compared to a form of cylindrical envelope with ends. flat.

The presence of the groove 24 also makes it possible to increase the useful length of the tubular lip 23, for a correct adaptation of a gas passage tube in said lip 23, without increasing the overall length of the envelope element.

The radial part 19, in the embodiment presented, consists of an intermediate portion 26 with a relatively large radius, for example 120 millimeters, connecting to the tubular axial zone 21 by an annular rounding 27 with a smaller radius, for example 15 millimeters. The tubular axial zone 21 has a sufficient length, for example ten millimeters, for the correct adaptation of one envelope element to the other.

The wall of the envelope element advantageously consists of several thin sheets in contact with each other and formed together by axial forming. In the embodiment shown in Figure 2, there is an outer sheet 28 and an inner sheet 29. The forming of the outer 28 and inner 29 sheets is performed at the same time, for example by deep drawing, by spinning or embossing. These techniques make it possible, for example, to produce a blind tubular casing element having a diameter of approximately 150 millimeters, for a length of approximately 220 millimeters. One can advantageously use two sheets 28 and 29 of austenitic type stainless steel, shade 304. The two sheets 28 and 29 produce a double skin substantially reducing the transmission of sound waves to the outside of the enclosure. According to other embodiments, it is advantageous to use other multilayer materials, for example a pair of stainless steel sheet-stainless steel fabric, or for example a stack of stainless steel sheet-elastomer-steel sheet. It is also possible to envisage making a non-metallic molded technical plastic material, a carbon fiber-based composite or other composites which support thermal stresses.

To make the silencer shown in FIG. 1, two envelope elements are used such as the element shown in FIG. 2, namely the first envelope element 14 and the second envelope element 15. The two elements envelope 14 and 15 are oriented in opposite directions and assembled axially to each other in opposition, as shown in FIG. 1, according to an intermediate peripheral connection zone 30 formed by the annular edge 17 of the first element 14 and the annular edge 32 of the second element 15 axially pressed one against the other edge to edge. A joining means 33 such as laser or plasma welding ensures the tight joining of the two edges 17 and 32 to each other along the entire periphery of their connection zone 30. It can also be secured by means 33 such as bonding, welding, bonding.

In the embodiment shown, the axial tubular parts of the first and second casing elements are cylindrical and of the same sections, to form a cylindrical axial peripheral side wall of muffler. The term "cylindrical" must be understood in the broad mathematical sense: the section can be circular, oval or arbitrary.

In line with the intermediate peripheral connection zone 30, there is an internal support part, formed, in the embodiment shown, by the transverse intermediate wall 13. Said internal part forming a transverse intermediate wall 13 is shaped to produce a connection support , against which the two inner faces of the tubular axial parts of the first casing element 14 and the second casing element 15 are in simultaneous abutment in the vicinity of their respective edges 17 and 32. For this, the inner part forming a transverse intermediate wall 13 comprises a peripheral surface 34, the shape of which corresponds to the shape of the inner periphery of the edges 17 and 32 to ensure close contact.

The transverse intermediate wall 13 can advantageously be constituted by a part having the same shape as the radial part 19 and the tubular axial zone 21 of an envelope element shown in FIG. 2. Thus, this intermediate part 13 can be produced with the same tools as those used to form the end of the envelope element of Figure 2. We understand the advantages that can be drawn from this solution for the standardization of production. The attachment means 33 advantageously ensures the simultaneous attachment of the two edges 17 and 32, and of the cylindrical peripheral portion 34 of the transverse inner wall 13.

According to another possibility, at the level of the intermediate peripheral connection zone 30, an internal support piece formed of a simple ferrule, or cylindrical annular element, can be arranged. The ferrule has a sufficient length to form a connecting support, against which the two inner faces of the edges of tubular axial parts of the first casing element 14 and of the second casing element 15 are pressed simultaneously. The ferrule comprises a surface device 34 whose shape corresponds to the inner periphery of edges 17 and 32, to ensure close contact. Thus, the shell does not divide the muffler into two compartments, but only fulfills the support and guiding functions of the respective two edges 17 and 32 of the envelope elements.

The following figures illustrate the modular nature of the silencer structure according to the invention. They show how, from a very small number of elementary parts, it is possible to design a varied range of silencers, having various lengths, and in which the outer casing has the general structure shown in FIG. 2.

Thus, in FIG. 3, the structure of the silencer of FIG. 1 is shown schematically, with a first casing element 14, a second casing element 15, a transverse intermediate wall 13, a perforated inner longitudinal tube 8 , and two end tubes 7 and 9.

The silencer shown in FIG. 4 takes up substantially the same structure, with one difference: the orifice corresponding to the first end tube 7 is offset on one side relative to the longitudinal axis 2-5 of the silencer, then that the orifice corresponding to the second end tube 9 is offset in the other direction. In this case, a first perforated inner longitudinal tube 8 is held on the one hand by the first end tube 7 and on the other hand by an intermediate wall 130, inverted with respect to the intermediate wall 13, and of the same shape. A second perforated inner longitudinal tube 80 is held on the one hand by the second end tube 9 and on the other hand by the transverse inner wall 13.

In FIG. 5, the external appearance of a silencer has been shown, in the embodiment of FIG. 1. A distinction is thus made between the first orifice 5, the second orifice 6, and the intermediate peripheral connection zone 30 between the first casing element 14 and the second casing element 15. The tubular axial zone 21 of the first casing element 14 and the axial zone corresponding tubular 210 of the second envelope member 15 constitute two end zones of smaller diameter. These two zones can advantageously receive marking collars so that the said collars, when they are in position on the zones 21 and 210, do not exceed the outside diameter of the envelope.

In FIG. 6, a variant is shown in which the first casing element 14 comprises, on its first transverse end wall 3, two orifices 35 and 36 allowing the inlet and the outlet of the combustion gases respectively, so that the second envelope element 15 comprises a second transverse end wall 4 closed.

In the embodiment of FIG. 7, the first casing element 14 is identical to that of FIG. 5 while the second casing element 15 has a second orifice 6 arranged not in the second transverse end wall 4, which is closed, but in the lateral peripheral wall.

In the embodiment of FIG. 8, the silencer comprises a first casing element 14 and a second casing element 15 associated in the same manner as in the embodiment of FIG. 5, with a weld formed in the intermediate peripheral connection zone 30. In addition, a third casing element 37, identical to that shown in FIG. 2, is fitted on the axial zone 210 of the second casing element 15 by its open end, thereby extending the assembly formed by the first two envelope elements 14 and 15. A weld makes it possible to secure the third envelope element 37 to the second envelope element 15, along the entire periphery of the end edge 38 of said third element envelope 37.

In FIG. 9, the silencer is formed of a first casing element 39 identical to that shown in FIG. 2, of relatively great length, associated with a second casing element 40 of much shorter length. For example, the second envelope element 40 may consist of a part of the same shape as the transverse intermediate wall 13 shown in FIG. 1, that is to say comprising a radial part 19 of FIG. 2 and a zone tubular axial 21.

In Figure 10, there is shown an embodiment to four casing elements associated longitudinally with one another, namely: a first casing element 14, a second casing element 15 respectively forming the two ends of the silencer, and adapted to end tubes 7 and 9. The first casing element 14 is adapted by its edge 17 to the tubular axial zone of smaller section of a third casing element 41 itself welded edge to edge according to the peripheral weld zone 44 to a fourth element d envelope 42, itself receiving, on its axial tubular zone of smaller section, the edge 32 of the second envelope element 15. A lateral orifice 43 for gas passage is provided in the weld zone 44 of the elements envelope 41 and 42.

It will be understood that other variants can be produced, for example by providing casing elements of different lengths which can be associated with each other and produce silencers whose lengths can be chosen from a relatively continuous range of lengths.

It will be understood that the invention is compatible not only with internal structures of muffler with a perforated tube passing through, as shown in the figures, but also with any other internal structure of muffler. One can, for example, use an internal structure comprising a HELMOLTZ resonator, allowing a strong sound attenuation around a nominal frequency, for example between 80 and 100 Hertz.

The present invention is not limited to the embodiments which have been explicitly described, but it includes the various variants and generalizations thereof contained in the field of claims below.

Claims (11)

1 - Exhaust silencer, comprising an outer casing (1) forming a closed enclosure delimited by an axial peripheral side wall (2) developing along a longitudinal axis (II) and by first and second walls of transverse ends (3,4), the casing being pierced with at least two orifices (5,6) respectively allowing the entry and exit of the exhaust gases and suitable for the connection of an inlet tube ( 7) and an outlet tube (9), the casing (1) containing means (8) for the expansion of the exhaust gases and their conduction between the inlet and outlet orifices, the casing comprising :
- at least a first envelope element (14) formed of a continuous wall comprising an axial tubular part (16) constituting a portion of said axial peripheral side wall (2), the axial part (16) being limited to its first end by a first frank annular edge (17) and connecting at its second end to a radial part (19) constituting said first transverse end wall (3),
- at least one second casing element (15), formed of a continuous wall comprising a tubular axial part constituting a portion of said axial peripheral side wall (2), the axial part being limited at its first end by a second edge frank annular (32) of the same shape as said first edge (17), and connecting at its second end to a radial part constituting a transverse wall,
- said first (14) and second (15) envelope elements being assembled axially to each other in opposition according to an intermediate peripheral annular connection zone (30) formed by said first (17) and second (32) edges axially pressed one against the other edge to edge, said envelope elements (14,15) being secured to one another in leaktight fashion along the entire periphery of their connection zone (30),
characterized in that it comprises, in line with the intermediate peripheral annular connection zone (30), an internal part (13) with a cylindrical peripheral surface (34) forming a connection support against which the two internal faces of the tubular axial parts of the first (14) and second (15) envelope elements in the vicinity of said annular edges (17,32). 2 - Muffler according to claim 1, characterized in that a securing means (33) such as welding, bonding, weld-bonding, crimping, simultaneously secures the two edges (17,32) of the first (14) and the second (15) envelope element and the interior part (13). 3 - Muffler according to one of claims 1 or 2, characterized in that the first (14) and the second (15) envelope elements each constitute a part produced separately by axial forming of a plate material. 4 - Muffler according to one of claims 1 or 2, characterized in that the inner part (13) forms transverse wall separating two compartments (11,12) distinct from mufflers. 5 - Muffler according to any one of claims 1 to 4, characterized in that the tubular axial part (16) of at least one of the first or second envelope elements (14,15) comprises an annular constriction (20 ) in the zone of connection to the radial part (19), defining a tubular axial zone (21) of smaller section on which the first open end of an envelope element can fit together with little play. 6 - Muffler according to claims 4 and 5, characterized in that the inner part (13) forming a transverse wall comprises a tubular axial zone (34) and a radial part identical respectively to the tubular axial zone of reduced section (21) and to the radial part (19) of an envelope element, said axial tubular zone of internal part constituting the connection support. 7 - Muffler according to any one of claims 1 to 6, characterized in that the end walls (3,4) of the silencer are pseudo-spherical, with convexity facing outwards, and comprise at least one orifice d adaptation of the gas passage tube, and in that each orifice (22) comprises a protruding tubular lip (23) connecting to the end wall (19) by a recess zone forming an external groove (24) at rounded section formed on said end wall on at least a portion of the periphery of said lip (23), so that said recess zone constitutes an intermediate zone of deformation between the tubular lip (23) and the end wall ( 19) and allows slight variations in axial orientation between the muffler and a gas passage tube engaged in said lip (23). 8 - Muffler according to any one of claims 1 to 7, characterized in that the wall of the envelope elements consists of two thin sheets (28,29) of stainless steel in contact with one another and formed together by deep drawing. 9 - Muffler according to any one of claims 1 to 8, characterized in that it comprises two identical envelope elements (14,15) assembled in opposition and with an intermediate wall (13). 10 - Muffler according to any one of claims 1 to 8, characterized in that it comprises a first casing element (39) comprising an elongated tubular part and a second casing element (40) comprising a more tubular part short. 11 - Muffler according to claims 5 and 9, characterized in that it further comprises a third casing element (37) connecting via the open end (38) of its tubular part to the tubular axial section of more section reduced (210) by one (15) of the other two elements (14,15).

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