VALVE UNIT, SUCH AS AN EXHAUST VALVE UNIT FOR MOTOR VEHICLES

Abstract

The invention relates to an exhaust system, in particular with an exhaust valve device especially usable in motor vehicles.

Description

[0001] The invention relates generally to the bearing arrangement of a shaft; it is therefore not limited to the application described and claimed below by way of example, although it is particularly advantageously applicable there, namely in the example of a valve unit for motor vehicles. The invention further relates to a method for forming such a bearing arrangement. Such a valve unit can consist of a pipe section and have a valve shaft which is supported by at least one bearing point provided on the pipe section. A valve body, such as a valve plate, is attached to the valve shaft, and the valve shaft can be rotated or pivoted by means of an actuating device.

[0002] Such devices are used in motor vehicles, particularly in the intake or exhaust system, and in the latter case, for example, in connection with cylinder deactivation, exhaust gas recirculation, in exhaust catalysts, or to influence combustion or exhaust noise.

[0003] Cables, connecting rods, or motors, such as electric motors, are used as actuating means. In the latter case, such motors can be mounted on the pipe section and form a pre-assembled unit with the valve assembly. The valve shaft is generally rotatable or pivotable, either directly with the motor output shaft or indirectly via the output shaft of a gearbox downstream of the motor, by means of an intermediate coupling, which can be designed as a spring element, and thus the flow rate of the corresponding fluid can be controlled.

[0004] The valve shaft can be supported "floating", i.e., via only a single bearing point, wherein a bushing tightly connected to the pipe section is provided on the exhaust pipe for the passage of the valve shaft, in which a sliding bearing sleeve for supporting the valve shaft is received. Such an embodiment is shown, for example, in DE 195 26 143.

[0005] In devices such as those disclosed in DE 10 2009 052 423, the exhaust flap is additionally mounted in a conical recess in the area opposite the bearing bushing within the exhaust pipe. The single bearing and sealing point is designed to be relatively complex.

[0006] However, more precise bearing arrangements for the valve or exhaust flap shaft are achieved by means of two bearing points with two plain bearings for the valve shaft, as is known, for example, from DE 20 2008 005 992 U1 and DE 10 2006 048 713 A1, which, however, require two openings in the walls of the exhaust pipe and thus two seals. In DE 20 2008 005 992 U1, one bearing point is also designed as a seal, which additionally has spring elements and is therefore more complex. The other bearing point is surrounded by a separate bearing housing that is gas-tightly connected to the pipe section. DE 10 2006 048 713 A1 has two spring-loaded bearings or seals. Such bearing and sealing points are very complex due to their self-adjusting design.

[0007] The higher the requirements for tightness, service life and temperature resistance become, or the greater and faster such temperature changes occur, the greater and more complex and therefore more expensive the expenditures for the bearing points are, in particular for the materials to be used and the accuracy of the fits between shaft and sliding bearing and for the design of the seals.

[0008] The present invention was based on the objective of designing bearings for shafts or axles, e.g., for valve units for motor vehicles, and thus valve units that are characterized by inexpensive and simple manufacturing, high sealing between the shaft and the sliding bearing, long service life, and cost-effective production. Furthermore, assembly should be simplified and made less expensive.

[0009] According to the present invention, this is achieved by providing a sliding bearing between the shaft and the bushing receiving the sliding bearing sleeve, wherein the sliding bearing sleeve is at least elastically deformed.

[0010] In some applications, particularly in connection with the design of a valve unit for motor vehicles, such as exhaust flaps, it may be advantageous and sufficient if the bearing sleeve is only elastically deformed by applying an axial force to the sliding bearing sleeve and, if necessary, maintaining a minimum pressure. The resulting radial expansion of the bearing in the direction radially inward toward the shaft and radially outward toward the bushing can, by selecting a suitable bearing material, create a bearing with sufficient sealing.

[0011] In other cases, however, a bearing arrangement in which the bearing sleeve is permanently deformed or compressed, in the sense of a forming process, may prove advantageous. In other words, a controlled change of the bearing sleeve to a different geometry takes place, beyond the elastic limit of the material used, but within the deformation capacity and before shear or separation fractures occur. This can be achieved in a particularly simple manner by inserting the bearing sleeve into the bushing and the shaft into the bearing sleeve—or the bearing and shaft together into the bushing—and by deforming the bearing sleeve within the bushing. This can be achieved simply by applying a controlled pressure to the sleeve in the axial direction and / or by methods such as...A pressure ram is used to deform the bearing sleeve by a specific axial path, the degree of deformation being determined by the deformation capacity of the bearing sleeve, the differences in diameter or volume to be bridged between the bushing, bearing sleeve, and shaft, the required sealing of the bearing (i.e., the permissible leakage when using such a bearing or seal, for example, in a valve unit for motor vehicles, such as an exhaust flap), and the required ease or stiffness of operation of the device. It can be advantageous if the sleeve is deformed by between 40 and 80%, preferably between 55 and 70%, and particularly preferably between 68 and 65% of its deformation capacity.

[0012] It has proven advantageous to use a bearing sleeve that contains at least some porous material, in particular porous bearing material such as graphite, especially soft graphite. It has also proven particularly advantageous to provide the graphite body with a kind of corset to give the inherently soft components a certain degree of support or dimensional stability. For this purpose, an insert or support made of a mesh is particularly suitable, for which a fabric, fleece, or similar structure, e.g., made of wire, can be provided—or conversely, the bearing material can also be incorporated into such a structure. The inherently non-dimensionally stable graphite is thereby brought into a constant shape, and this composite body is plastically deformed, as described above, and this deformation is maintained by the insert or support.In the vast majority of cases, it will be advantageous to carry out the deformation in a targeted manner, dependent on displacement and pressure, within such limits that disintegration, breaking apart or crumbling of the graphite structure is avoided.

[0013] Although such a valve unit with a bearing formed in this way by forming the bearing with a sealing function - or seal with bearing function - already offers considerable advantages over previously known designs when configured with only one bearing point for the valve shaft, those with two bearing points, at least one of which is designed according to the invention, offer further advantages over comparable designs according to the prior art, in particular simpler assembly if, according to a further feature of the invention, the bearing point having the compressed bearing is provided on the side of the valve unit facing the actuating means.In this case, the other bearing point can be formed by a plain bearing – which also provides axial support for the shaft – and which, after the shaft is inserted from below, i.e., from the side facing away from the actuator, is sealed – before or after the formation of the deformed bearing – by sealing, brazing, or similar means with a sealing cap. This can be advantageous for designs where the shaft is pulled or pushed towards the actuator by springs. Alternatively, the bearing point formed by deformation can also additionally serve as an axial bearing, whereby the shaft, with a molded shoulder, collar, or similar feature, can bear against an edge or collar of the bearing sleeve inside the valve unit, facing towards the actuator. The shaft can also be axially supported on the outside of the valve unit by means of a washer or similar feature.provided, is spring-loaded against the edge area of ​​the sliding bearing.

[0014] In individual cases, it may also be advantageous to form the sliding bearing by deforming the bearing sleeve beyond the plastic deformation, i.e., by destroying the geometric shape even further than described above.

[0015] The invention further relates to a method for manufacturing a bearing according to one of the claims and units or assemblies equipped therewith, in which the geometric shape of the bearing body is changed, permanently deformed, i.e. transformed, in particular cold-worked or cold-formed or even destroyed in a receptacle and in the presence of a shaft.

[0016] The invention will be explained in more detail with reference to Figures 1-3.

[0017] In this section 1, the invention is shown in connection with an exhaust flap in a view,

[0018] 2 the exhaust flap in a section according to line II-II,

[0019] 3 an enlarged section III from 2 before the production of the bearing location according to the invention.

[0020] The exhaust flap A is shown in the form of a prefabricated unit with an exhaust pipe 1, which is inserted into an exhaust system, e.g., welded in. A lower and an upper bearing point 2, 3 with bearing bushings 2a, 3a and bearing elements 4, 5 received therein serve to support the valve flap shaft 6. Both bushings are gas-tightly connected to the pipe 1, e.g., welded.

[0021] The bearing element 4 of the lower bearing point 2a is a sliding bearing with axial bearing function, for which the shaft 6 with a collar 6a rests against the lower end face of the bearing 4 under the action of an axial spring force.

[0022] The lower bearing point is sealed gas-tight to the outside by a cover 7.

[0023] A bracket 8, which is welded to the tube 1 by means of U-shaped legs 8a, serves, together with a retaining plate 9 attached to it, to support the actuating device B, here a cable pull. A coil spring 10 is supported at one end 10a against an upwardly directed extension 9a of the retaining plate 9 and at the other end 10b against a downwardly directed extension 12a of a lower disc 12. The disc 12, which is rotationally fixed to the shaft 6, together with a disc 13 on which it is attached, forms the pulley for the inner tube of the cable pull B.

[0024] The spring 10 is designed such that it holds the valve flap, which is attached to the shaft 6, in an open position when the cable is released by a drive motor. In this position, the spring pushes the extension 12b of the disk 12 against the extension 9b of the retaining plate 9, which acts as a stop. The spring 10, a compression spring, exerts an axial preload on the end face of the bearing element 4 via the disk 12, the shaft 6, and the collar 6a provided thereon.

[0025] The open position of the aperture 11, i.e., the rest position, is shown in a highly emphasized position in both Figures 1 and 2. According to a further feature of the invention, the aperture 11 is flatter than the tube 2, i.e., elliptical. It has a shape that deviates from the usual circular shape; in the present embodiment, it is arranged with its major semi-axis horizontally. Such a design is particularly advantageous—but not exclusively—in connection with flap actuators that are self-locking and in which the energy supply is switched off when no energy is required for adjustment, in order to save energy. The drive motors themselves can be self-locking, e.g., braked or blocked, or the like, or a component downstream of the drive motor, such as a self-locking gearbox, like a worm gear, can be provided in the power transmission path.However, such drives have the disadvantage that in the event of a power failure, if the baffle happens to be in the closed position, it cannot be moved from this position, and the internal combustion engine comes to an uncontrolled standstill. This can also occur if, while the baffle is closed—which, because it is directly in the hot gas stream, experiences faster and greater thermal expansion than the exhaust pipe—a sudden cooling of the exhaust pipe occurs, for example, due to the action of splashing water, causing the baffle to jam—particularly in motorcycles, with catastrophic consequences.

[0026] As can be seen from Figure 1, the aperture 11, shown with dashed lines in the closed position 11a, is flatter than the tube 1, at least approximately elliptical, with its minor semi-axis pointing towards the shaft 6, so that even if the actuator fails, a minimum flow rate or controlled leakage is still ensured. It has been found that a minimum leakage of up to 30% can be advantageous; preferably, this is between 20% and 30%, and particularly advantageously between 20% and 25%.

[0027] This effect can also be achieved by having the pipe and / or the flap have a shape that deviates from a circular shape and by providing a targeted minimum leakage between them that is (significantly) greater than the gap resulting from the usual manufacturing tolerances. In embodiments where flap jamming can occur due to shock cooling of the exhaust pipe when the flap is thermally expanded, it is advantageous to make the gap between the pipe and the flap sufficiently large in the areas of the orifice that are adjacent to the shaft or axis. The flap can then be made to contact the pipe in the closed valve position by abutting it against at least one area further away from the shaft.

[0028] The design of the bearing point 3 will be explained in more detail in connection with Figure 3, which shows a section III of Figure 2. After inserting the shaft 6 together with the sliding bearing 4 from below through the bearing bushing 2a and with its upper portion through the bearing bushing 3a, and inserting the bearing body 5, shown in dashed lines, which lies relatively loosely between the shaft 6 and the bushing 3a, it is compressed by applying a predetermined force F, e.g., by means of an annular punch, until it has assumed the shape 5a shown in gray, whereby a plastic displacement of material has taken place and the bearing element 5 now seals both the shaft 6 and the sleeve 3a and the shaft 6 is also supported.The degree of deformation is determined not only by the pressure to be applied but also by the axial distance by which the bearing sleeve is compressed by the punch; both of these factors must be taken into account to ensure sufficient permanent deformation of the bearing body, which is made of soft graphite and reinforced with a wire mesh, without jeopardizing the cohesion of the bearing body. QUOTES INCLUDED IN THE DESCRIPTION

[0030] This list of documents cited by the applicant was generated automatically and is included solely for the convenience of the reader. The list does not form part of the German patent or utility model application. The DPMA accepts no liability whatsoever for any errors or omissions. Cited patent literature

[0032] DE 19526143 DE 102009052423 DE 202008005992 U1 DE 102006048713 A1

Claims

Claims 1. Valve unit, consisting of a pipe segment, a valve shaft (6) mounted thereon with at least one fulcrum (3) and dipping therein, on which a valve flap present in the pipe segment is provided and the valve shaft (6) being operatively connected to an output shaft of a drive means for moving the valve flap back and forth between an open position and a closed position, characterized in that a gap remains between the inner contour of the pipe segment and the valve flap in the closed position, and in that said at least one fulcrum (3) is produced by introducing into the bearing shell (3a) a bearing body (5), preferably made of a soft graphite material reinforced by braided metal wires,leading to compression of the bearing body (5) with plastic deformation of the material to ensure the sealing of both the shaft (6) and the bearing shell (3a) as well as the housing of the shaft (6)., 2. Valve unit according to claim 1, characterized in that the valve flap and / or the pipe segment have a cross-section other than an at least substantially circular cross-section.

3. Valve unit according to claim 1 or 2, characterized in that the valve flap is flatter in shape than the pipe.

4. Unit of valve according to 1 ' a of the Claims 1 to 3, characterized in that the valve flap is at least substantially elliptical in shape.

5. Unit of valve according to 1 ' a of the Claims 1 to 4, characterized in that the large half-axis of the valve flap is oriented at least substantially perpendicular to the valve shaft (6).

6. Unit of valve according to of the Claims 1 to 5, characterized in that the valve flap has on its outer periphery at least one flattening, a cutout, a recess or the like.

7. Valve unit according to one of claims 1 to 6, for use in connection with a direct or indirect drive by means of an electric motor with a drive motor or gear mounted downstream, self-locking or braked.

8. Valve unit according to one of claims 1 to 6, characterized in that it is attached to the end of the exhaust system in the form of an exhaust pipe.

9. Valve unit according to one of claims 1 to 6, characterized in that it is arranged at the end of the exhaust system in the form of at least two exhaust pipes.

10. Exhaust system using a valve unit, as defined in one of claims 1 to 9, characterized in that the exhaust system has a predetermined targeted leak at the valve flap, greater than the leak obtained by usual manufacturing techniques. 5 11. Exhaust system using a unit of valve, as defined in one of claims 1 to 9, characterized in that the exhaust system has at the valve flap a predetermined targeted leak, greater than the leak obtained by the usual manufacturing tolerances.

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