Abstract:
An intake device ( 1 ) for an internal combustion engine including a main body ( 2 ) and cover element ( 3; 20 ) which are securely connected to one another. Main body ( 2 ) and cover element ( 3 ) form intake pipes ( 4, 5, 6, 7 ) of in intake manifold. The cover element ( 3; 20 ) includes a plurality of individual shells ( 14, 15, 16, 17; 24, 25, 26, 27 ), which are connected to one another. Each individual shell ( 14, 15, 16, 17; 24, 25, 26, 27 ) forms a wall section of a respective intake pipe ( 4, 5, 6, 7 ) of the intake device ( 1 ). A flexible connection element ( 22 ) is arranged between two successively adjacent individual shells ( 25, 26 ) to compensate for tolerances between the cover element ( 3 ) and the main body ( 2 ).

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an air intake device for an internal combustion engine comprising a main body and a cover element which are securely joined to one another and which form at least two intake pipes. 
     British Patent no. GB 2,279,035 discloses an air intake device comprising a main body having a cover element placed thereon and attached thereto by friction welding. The cover element is formed by four partial shells of the intake manifold, which are rigidly connected to one another via a transverse section of the header pipe. In order to be able to compensate for tolerances between the main body and the cover element, the material of the cover element is more flexible than that of the main body. However, the use of a flexible material for the entire cover element leads to a lower compressive strength of the intake manifolds. In addition, the use of different materials for the cover element and the main body may lead to a lower strength of the friction weld bond. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an improved air intake device of the foregoing type. 
     Another object of the invention is to provide an air intake device having a main body and a cover element which can be joined to each other with great precision. 
     A further object of the invention is to provide an air intake device which avoids the need for parts constructed of different materials. 
     These and other objects have been achieved in accordance with the present invention by providing an intake device for an internal combustion engine comprising a main body and a cover element which are securely joined to one another and which form at least two intake pipes, in which the cover element comprises a plurality of individual shells connected to one another, each individual shell forming a wall section of an intake pipe of the intake device, and wherein the connection between at least two successively adjacent individual shells is formed by a flexible connection element arranged between them. 
     The arrangement of a flexible connecting element between neighboring individual shells allows the compensation of tolerances between the main body and the cover element, such as those which may occur through contraction during injection molding, for example. The individual shells of the cover element are connected to one another as in prior devices, so that the number of individual parts is not increased. The cover element and the main body may be made of the same material. 
     The connection element is advantageously flexible in all three spatial directions, so that tolerances may be compensated for in all directions. For this purpose, the connection element has a flexible section, which is particularly positioned centrally between two individual shells. The flexible section may, for example, be produced easily in the injection molding method and has elastic properties, through which the tolerances may be compensated. In order to achieve approximately constant stress ratios, the flexible section has an approximately constant width over its length. The flexible section may advantageously be constructed, for example, as V-shaped, horseshoe or omega-shaped, circular, elliptical, or zig-zag shaped. Other configurations may also be advantageous. 
     To facilitate the ability, of the cover to accept and withstand applied forces, additional sections, which are thicker the flexible section, are provided between the individual shells and the flexible section. 
     The cover element is advantageously manufactured in one piece. The main body and the cover element may be connected to one another by a material bond, in particular by a vibration-welded joint. For this purpose, the main body and the cover element advantageously contact each other through peripheral flanges which can be welded together. 
     The connection element advantageously extends essentially in the plane of the flange of the cover element. The connection element is preferably fixed on the flange. In order to achieve good elasticity of the connection element, the thickness of the connection element is less than the thickness of the flange. Particularly in intake devices for internal combustion engines having large piston displacements, it may be advantageous for the individual shells to be rigidly connected to one another at one end, via a section of a collecting chamber, for example, and for at least one flexible connection element to be arranged at their other ends. In order to compensate for larger tolerances, it is particularly advantageous to arrange a flexible connection element between each pair of individual shells. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described in further detail hereinafter with reference to illustrative preferred embodiments shown in the accompanying drawings, in which: 
     FIG. 1 is a perspective representation of an intake device according to the invention; 
     FIG. 2 is a perspective view of a cover element according to the invention; 
     FIG. 3 is a top view of the cover element; 
     FIG. 4 is an enlarged detail view of detail area IV of FIG. 3; and 
     FIGS. 5 to  8  show variant embodiments of the connection element in enlarged views corresponding to FIG.  4 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 shows an intake device or manifold  1  for an internal combustion engine, which includes four intake pipes  4 ,  5 ,  6 ,  7 . Each intake pipe  4 ,  5 ,  6 ,  7  supplies air to one cylinder of the internal combustion engine. For this purpose, the intake pipes  4 ,  5 ,  6 ,  7  are connected to the collecting chamber  10 , which is supplied with air through an air filter (not shown). The intake pipes  4 ,  5 ,  6 ,  7  discharge at attachment flange  8 , which may be fastened with screws onto the internal combustion engine. Holes  11  for the passage of screws or bolts are provided through attachment flange  8  for this purpose. Recesses  9  for the fuel injectors are positioned on the attachment flange  8  above the intake pipes  4 ,  5 ,  6 ,  7 . 
     The intake pipes  4 ,  5 ,  6 ,  7  are formed by a main body  2  and a cover element  3 . The cover element  3  comprises four individual shells  14 ,  15 ,  16 ,  17 , which are connected together and which each form a wall section of a respective intake pipe  4 ,  5 ,  6 ,  7 . The individual shells are connected to one another via webs, which are preferably elastic, so that the individual shells  14 ,  15 ,  16 ,  17  of the cover element  3  may be adjusted in every direction to match the configuration of the contact surface  18  of the main body. In this way, all tolerances arising during production may be compensated for. 
     Cover element  3  and main body  2  are preferably produced from synthetic resin material, i.e., a plastic. The same material is advantageously used for both the cover element and for the main body. 
     To connect main body  2  and cover element  3 , along the contact surface  18 , a peripheral flange  12  is constructed on main body  2  and a flange  13  is constructed on cover element  3 . Flanges  12  and  13  are joined to one another at the contact surface  18 , preferably by vibration welding. However, other joining methods, for example gluing, may also be advantageous. The contact surface  18  is laid out in such a way that main body  2  and cover element  3  both have geometries which can be produced easily by injection molding. 
     An embodiment of a cover element  20  is illustrated in FIG.  2 . The cover element  20  includes individual shells  24 ,  25 ,  26  and  27 , which are connected to one another. The flange  23 , which is used to join the cover shells to a main body, is provided with lengthwise grooves  28  on the contact surface which contacts the main body. These lengthwise grooves  28  extend next to the actual welding surface and are used as a welding burr accumulator, in which any molten material exiting laterally from the welding surface collects. This is advantageous for producing a burr-free friction-welded joint which is clean toward the intake manifold and the outside. 
     The outer pairs of individual shells  24 ,  25  and  26 ,  27  are each connected substantially non-elastically to one another by a connection web  21 . A flexible connection element  22 , which is molded onto the flanges  23  of the center pair of individual shells  25  and  26 , is arranged between central shells  25  and  26 . The thickness a of the connection element  22  is substantially constant, and the thickness b of the flange  23  is greater than the thickness a of the connection element  22 . 
     A top plan view of the cover element  20  is shown in FIG.  3 . The individual shells  25  and  26  are provided with brackets  29  and  30  for mounting adjacent components. The connection webs  21  between the individual shells  24 ,  25  and  26 ,  27  have a wide construction. In particular, the width d of the connection webs  21  is greater than the spacing of the individual shells to be connected. In contrast, the width of the flexible connection element  22  is significantly smaller than the spacing of the individual shells  25 ,  26 . 
     The connection webs  21  and the flexible connection element  22  connect the oblong individual shells  24 ,  25 ,  26 ,  27  approximately in the middle of their lengthwise extension. However, it may in particular be advantageous to position the flexible connection element  22  at one end of the individual shells. This is particularly desirable if the individual shells are rigidly connected to one another at one end, for example, by a section of a collecting chamber. For large individual shells, it may be advantageous to provide multiple connection webs and flexible connection elements spaced along the length of the individual shells. 
     The positioning of the flexible connection element and the connection webs may also vary as a function of the necessary tolerance compensation. For example, it may be desirable to position flexible connection elements between the outer individual shells and to connect the middle shells with a substantially rigid (i.e., inelastic) connection web. It may also be advantageous to provide flexible connection elements between all individual shells. Further arrangements may arise in intake devices having a different number of intake pipes, for example, six or eight intake pipes. 
     The connection element  22  of FIG. 3 is illustrated in an enlarged view in FIG.  4 . The connection element  22  comprises a flexible section  31 , which is constructed with a V-shape and which is positioned approximately centrally between the individual shells  25  and  26 . The flexible section  31  has a width c, which is small in comparison to the distance between the individual shells  25  and  26 . Due to the small width c of the flexible section  31 , the connection element  22  is flexible in all three spatial directions. It is also possible to tilt the individual shells relative to one another. 
     The tip  33  of the V-shaped section  31  has a rounded construction, which minimizes the danger of breakage at this point. The flexible section  31  is connected to the flanges  23  of the individual shells  25 ,  26  via connection sections  32 . The connection sections  32  are constructed broader in width relative to the flexible section  31 , so that a strong connection between the connection element and the individual shells is assured. 
     Another variant embodiment of the flexible section  31  is illustrated in FIG.  5 . The flexible section  31  arranged between the connection sections  32  has a zig-zag configuration, each tip  33  having a rounded construction. In the illustrated embodiment, the flexible section  31  has five tips  33 , however, flexible sections with a greater or lesser number of bights or tips  33  may be advantageous in some cases. 
     In the illustrative embodiment depicted in FIG. 6, the flexible section  31  has a circular construction. The flexible section  31 , having a width c, is connected directly to the flanges  23  of the shells  25 ,  26 . 
     In FIG. 7, an elliptical flexible section  31  is illustrated, which is connected to the flanges  23  via connection sections  32 . 
     The connection section  32  illustrated in FIG. 8 has a horseshoe or omega-shaped construction. In addition to the variant embodiments shown, other embodiments of the flexible section  31  may also be advantageous. 
     The foregoing description and examples have been set forth merely to illustrate the invention and are not intended to be limiting. Since modifications of the described embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed broadly to include all variations falling within the scope of the appended claims and equivalents thereof.