TECHNICAL FIELD

[0001] The subject invention relates to an adaptive valve assembly that defines a valve stop position using a spring retainer.

BACKGROUND OF THE INVENTION

[0002] Exhaust systems are widely known and used with combustion engines. Typically, an exhaust system includes exhaust tubes or pipes that convey hot exhaust gases from the engine to other exhaust system components, such as mufflers, resonators, etc. Mufflers and resonators include acoustic chambers that cancel out sound waves carried by the exhaust gases. Although effective, these components are often relatively large in size and provide limited nose attenuation.

[0003] One solution for reducing low frequency noise is to use a passive valve assembly. The passive valve assembly includes a flapper valve body or vane that is positioned within an exhaust pipe, with the vane being pivotable between an open position and a closed position. The passive valve is spring biased toward the closed position, and when exhaust gas pressure is sufficient to overcome this spring bias, the vane is pivoted toward the open position. When the exhaust gas pressure falls, the spring causes the vane to return to the closed position.

[0004] With the use of the spring, it is difficult to return the vane to a consistent closed position within the exhaust pipe. Further, while effective at attenuating low frequency noise, the introduction of the passive valve into the exhaust system presents additional noise challenges. For example, when the spring returns the vane to the closed position, closing noise is generated, which is undesirable.

SUMMARY OF THE INVENTION

[0005] An adaptive valve assembly includes a pipe defining a passageway for conducting engine exhaust gases, a pivot shaft supported by the pipe, and a valve body coupled to the pivot shaft. The valve body is moveable between an open position where exhaust gas flow through the passageway is increased and a closed position where exhaust gas flow through the passageway is reduced. A resilient member biases the valve body toward the closed position. A retainer cooperates with the resilient member to define a valve stop for the valve body when in the closed position.

[0006] In one example, the retainer comprises a first retainer piece fixed to a non- rotating structure and a second retainer pieced fixed to the pivot shaft. The first retainer piece provides the valve stop.

[0007] In one example, the resilient member comprises a spring having a first spring end configured to be fixed to the non-rotating structure and a second spring end configured to be rotatable with the shaft. The second spring end engages the first retainer piece to define the valve stop. The second spring end moves out of engagement with the first retainer piece as the valve body moves toward the open position.

[0008] In one example, the adaptive valve assembly comprises a passive valve where the valve body is solely moveable from the closed position toward the open position in response to an increase in exhaust gas pressure flow against the valve body.

[0009] One exemplary method of controlling movement of the adaptive valve assembly comprising the steps of: providing a valve body moveable between an open and closed position within an exhaust gas passageway; resiliently biasing the valve body toward the closed position with a resilient member; and defining a valve stop position for the valve body in the closed position with a retainer that supports the resilient member.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic view of a vehicle exhaust component incorporating a passive valve assembly.

[0011] Figure 2 is a schematic top view of Figure 1.

[0012] Figure 3A is a perspective view of a spring retainer assembly from Figure 1 showing the valve assembly in a fully closed position.

[0013] Figure 3B is a magnified view of Figure 3A.

[0014] Figure 4 is a perspective view of the spring retainer assembly from Figure 3A showing the valve assembly moving toward a fully open position.

[0015] Figure 5 is a front view of the spring retainer assembly of Figure 3A.

[0016] Figure 6 is a side view of one example of a spring in an uncompressed position. [0017] Figure 7 is a perspective view of the spring of Figure 6 in a compressed position.

[0018] Figure 8 is another example of a spring retainer assembly as used with the spring of Figure 6.

DETAILED DESCRIPTION

[0019] Figure 1 is a schematic view of an exhaust component 10 that includes an exhaust valve assembly 12 that is movable between an open position and a closed position. In the example shown, the exhaust component 10 comprises pipe or a tube body 14 that defines an exhaust gas flow path 16 that conducts heated exhaust gases from an internal combustion engine (not shown) to downstream exhaust components. The exhaust valve assembly 12 includes a valve body 18 that blocks at least a substantial portion of the exhaust gas flow path 16 when in the closed position and is pivoted toward the open position to minimize blockage.

[0020] The valve body 18 is fixed to a pivot shaft 20 with a connecting member 22. In one example, a slot 24 is formed within an outer surface of the tube body 14. A housing 26, shown in this example as a square metal structure, is received within this slot 24 and is welded to the tube body 14. Other housing configurations with other shapes and mounting configurations could also be used. The shaft 20 is rotatably supported within the housing 26 by first 28 and second 30 bushings.

[0021] In the example shown, the connecting member 22 comprises a piece of sheet metal that has one portion welded to the shaft 20 and another portion that extends outwardly from the housing 26 and is welded to the valve body 18. Thus, the valve body 18 and the shaft 20 pivot together about an axis A. The connecting member 22 is just one example of how the shaft 20 can be attached to the valve body 18, it should be understood that other attachment mechanisms could also be used, or the shaft and the valve body could be formed together as a single-piece component.

[0022] The first bushing 28 is positioned generally at a first shaft end 32 as shown in Figure 2. The first bushing 28 comprises a sealed interface for the first shaft end 32. The shaft 20 includes a shaft body 34 with a first collar 36 near the first shaft end 32. The first bushing 28 includes a first bore 38 that receives the first shaft end 32 such that the first shaft end 32 does not extend axially beyond the first bushing 28. The first collar 36 abuts directly against an end face 40 of the first bushing 28 such that exhaust gas cannot leak out of the first bushing 28 along a path between the shaft 20 and first bushing 28.

[0023] The second bushing 30 includes a second bore 44 through which the shaft body 34 extends to a second shaft end 46. The shaft 20 includes a second collar 48 that is located axially inboard of the second bushing 30.

[0024] The shaft 20 extends through the second bore 44 to an axially outboard position relative to the second bushing 30. A resilient member, such as a spring 50 for example, is coupled to the second shaft end 46 with a retainer 52. The retainer 52 includes a first retainer piece 54 that is fixed to the housing 26 or pipe body 14 and a second retainer piece 56 that rotates with the shaft 20. One spring end 58 is fixed to a non-rotating structure and a second spring end 60 is configured to rotate with the shaft 20.

[0025] In the example shown, the spring 50 comprises a coil spring that is configured to be compressed both in an axial direction along axis A and in a torsional direction about axis A during installation. Torsional loading creates a preload force that biases the shaft 20 and the valve body 18 toward the closed position. As gas flow increases, this torsional force is overcome to move the valve body 18 toward the open position. The axial force serves to positively seat and seal the second collar 48 against an end face 66 of the second bushing 30. This prevents any exhaust gas from leaking out of the second bushing 30 by sealing off a passage between an outer surface of the shaft 20 and a bore surface of the second bushing 30. Thus, a single spring is used to provide both axial and torsional loading, resulting in a configuration that can both hold the exhaust valve assembly 12 in a desired operational position as well as preventing exhaust gas leakage.

[0026] The valve body 18 can only move toward the open position in response to an exhaust gas pressure force that overcomes the biasing force of the spring 50. In other words, the valve comprises a passive valve as opposed to an actively controlled valve where a controller is used to actively move the valve body to a desired valve position.

[0027] As discussed above, the spring 50 is associated with a retainer 52. The retainer 52 cooperates with the spring 50 to define a valve stop for the valve body 18 when in the closed position, i.e. interaction of the spring 50 with the retainer 52 defines the closed position for the valve body 18.

[0028] The retainer 52 includes a first retainer piece 54 that is fixed to a non- rotating structure such as the housing 26 or tube body 14, for example, and a second retainer piece 56 that is fixed to the second shaft end 46. In one example, the first retainer piece 54 is secured to the non-rotating structure by welding; however, other attachment methods could also be used. In one example, a fastener 70 is used to secure the second retainer piece 56 to the shaft 20; however, other methods could also be used. A first spring end 58 is fixed relative to the first retainer piece 54, i.e. the spring end 58 and first retainer piece 54 comprise non-rotating components, and a second spring end 60 is configured to rotate with the shaft 20.

[0029] The first retainer piece 54 provides a valve stop 72 (Figures 3A-3B). The second spring end 60 engages the first retainer piece 54 to define the valve stop 72 in the closed position. The second spring end 60 moves out of engagement with the first retainer piece 54, i.e. rotates with the shaft 20 away from the first retainer piece 54, as the valve body 18 moves toward the open position (Figure 4).

[0030] In one example, the first retainer piece 54 comprises a first end plate 80 having an opening 82 through which the pivot shaft 20 extends (Figure 5) such that the shaft 20 can rotate relative to the end plate 80. The first end plate 80 is fixed to the non-rotating structure as described above. The first retainer piece 54 includes at least one extension portion 84 extending transversely relative to the first end plate 80 and toward the second retainer piece 56. In the example shown, the extension portion 84 comprises a generally flat plate that extends over the spring 50. The second spring end 60 engages the extension portion 84 to define the valve stop 72 (Figure 3B).

[0031] In one example, second retainer piece 56 comprises a second end plate 90 that is fixed to the pivot shaft 20. The second end plate 90 includes at least one extension portion 92 extending transversely relative to the second end plate 90 and toward the first retainer piece 54. In the example shown, the extension portion 92 comprises a generally flat plate that extends over the spring 50. The extension portions 84, 92 of the first 80 and second 90 end plates are positioned in an overlapping relationship with each other and are located radially outwardly of the spring 50 relative to the axis A.

[0032] In the example, shown the spring 50 comprises a coil spring that surrounds the pivot shaft 20. The first retainer piece 54 includes an abutment surface 94 (Figure 5) to hold the first spring end 58 fixed relative to the pivot shaft 20. The second retainer piece 56 and the second spring end 60 are coupled for rotation together with the pivot shaft 20. [0033] One example of the spring 50 is shown in Figures 6-7. Figure 6 shows the spring 50 in an uncompressed position, while Figure 7 shows the spring 50 in a compressed position. The spring 50 is centered around axis A. In this example, the first spring end 58 extends in an axial direction that is spaced apart from and generally parallel to axis A, and the second spring end 60 extends in a direction that is transverse to axis A. In one example, the second spring end 60 is orientated at approximately a ninety degree angle relative to the first spring end 58.

[0034] Figure 8 shows another example of a retainer 52'. Similarly to the example shown in Figure 1, the retainer 52' cooperates with the spring 50 to define a valve stop for the valve body 18 when in the closed position. The retainer 52' includes a first retainer piece 54' that is fixed to the tube body 14 and a second retainer piece 56' that is fixed to the shaft 20. The first spring end 58 is fixed relative to the first retainer piece 54', i.e. the spring end 58 and first retainer piece 54' comprise non-rotating components, and the second spring end 60 is configured to rotate with the shaft 20.

[0035] The first retainer piece 54' provides a valve stop 72' (Figure 8). The second spring end 60 engages the first retainer piece 54' to define the valve stop 72' in the closed position. The second spring end 60 moves out of engagement with the first retainer piece 54', i.e. rotates with the shaft 20 away from the first retainer piece 54', as the valve body 18 moves toward the open position.

[0036] In this example, the first retainer piece 54' includes a base portion 100 that is positioned adjacent to the tube body 14 and a plurality of discrete arcuate portions 102 that extend outwardly from the base portion 100 and are circumferentially spaced apart from each other about the axis A. The second retainer piece 56' includes a base portion 104 that is fixed to the shaft 20 and a plurality of discrete arcuate portions 106 that extend outwardly from the base portion 104 and are circumferentially spaced apart from each other about the axis A.

[0037] In this example, the spring 50 has a first spring portion 108 at the second spring end 60 that has a diameter D4 (Figure 6) which is less than a diameter D5 along the remaining portion 110 of the spring 50. When installed within the retainer 52', the first portion 108 of the spring 50 abuts against radially inner surfaces of the arcuate portions 106 of the second retainer piece 56' and the remaining portion 110 abuts against radially inner surfaces of the first retainer piece 54'. The second spring end 60 extends radially outward relative to the axis A through a gap between adjacent arcuate portions 106 of the second retainer piece 56' and through a gap between corresponding adjacent arcuate portions 102 of the first retainer piece 54'. A base portion 112 of the second spring end 60 abuts against one edge 114 of the arcuate portion 106. When in a valve closed position (Figure 8), a distal end 116 of the second spring end 60 abuts against one edge 118 of the arcuate portion 102 of the first retainer piece 54' to define the valve stop 72'. When moving toward a valve open position, as the second retainer piece 56' rotates, the second retainer piece 56'moves the second spring end 60 out of engagement with the edge 118 of the arcuate portion 102. When returning to the valve closed position, the second retainer piece 56' rotates the second spring end 60 until contact is made at the valve stop 72'.

[0038] As discussed above, the valve body 18 is solely moveable from the closed position toward the open position in response to an increase in exhaust gas pressure flow against the valve body 18. As this force increases to overcome the biasing force of the spring 50. The second retainer piece 56, 56' and pivot shaft 20 rotate to move the second spring end 60 away from the valve stop 72 of the first retainer piece 54, 54'. When the exhaust gas pressure falls below the biasing force of the spring 50, the spring 50 causes the valve body 18 to return to the closed position where the second spring end 60 engages the first retainer piece 54, 54' at the valve stop 72, 72'.

[0039] As such, a method of controlling movement of the adaptive valve assembly comprises the following steps. A valve body 18 is provided that is moveable between an open and closed position within an exhaust gas passageway. The valve body is resiliently biased toward the closed position with a resilient member 50. A valve stop 72, 72' position is defined for the valve body 18 in the closed position with a retainer 52, 52' that is associated with the resilient member 50.

[0040] Additional steps include providing the retainer 52, 52' with a first retainer piece 54, 54' and a second retainer piece 56, 56', fixing the first retainer piece 54, 54' to a non-rotating structure that defines the exhaust gas passageway, fixing the second retainer piece 56, 56' for rotation with a pivot shaft 20 that supports the valve body 18, and defining the valve stop position on the first retainer piece 54, 54'. The first spring end 58 is associated with the first retainer piece 54, 54' , the second spring end 60 is configured to move with the pivot shaft 20, and the second spring end 60 is abutted against the first retainer piece 54, 54' to define the valve stop 72, 72' position. [0041] As such, the spring itself is used as a resilient stop, i.e. a soft stop, to minimize impact noise when the valve closes. Further, the spring comprises a hardened component such that wear due to contact is minimized.

[0042] Although an embodiment embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.