Valve assembly and exhaust gas recirculation system including the same

A valve assembly includes a valve housing defining a flow passage configured to receive exhaust gas from an internal combustion engine, and defining a bore extending along a bore axis and fluidly coupled to said flow passage. The valve assembly also includes a valve body for controlling the flow of exhaust gas through the bore, and a shaft coupled to the valve body. The valve body is moveable between a closed position and an open position when the shaft rotates about the axis. The vale assembly additionally includes a first biasing member coupled to the shaft and configured to bias the shaft along the shaft axis in a first direction, and a second biasing member coupled to the shaft and configured to bias the valve body in the first direction along the shaft axis.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a valve assembly and, more specifically, to a valve assembly for use in an exhaust gas recirculation system of a vehicle.

2. Description of the Related Art

Conventional valve assemblies for use in an exhaust gas recirculation system typically include a valve housing defining a flow passage and a bore for receiving exhaust gas from an internal combustion engine. Typical valve assemblies also include a valve body disposed in the bore for controlling the flow of exhaust gas through the bore. Conventional valve assemblies further include a shaft extending along a shaft axis and coupled to the valve body for moving the valve body between a closed position and an open position. To move the valve body between the open and closed positions, typical valve assemblies also include an actuator coupled to the shaft.

Because valve assemblies are used to control the flow of exhaust gas through the exhaust gas recirculation system, various components of the valve assembly are subjected to temperature changes. For example, when the valve assembly is not in use, various components of the valve assembly are subjected to ambient air temperature. On the other hand, during use of the valve assembly, the valve assembly is subjected to exhaust gas, which, in turn, subjects various components to thermal expansion.

To reduce movement of the shaft during operation of the valve assembly, typical valve assemblies include a biasing member coupled to the shaft to bias the shaft along the shaft axis both to reduce vibration of the shaft and to attempt to minimize the effect of thermal expansion of the shaft. However, typical biasing members do not account for the thermal expansion of the valve body with respect to the shaft axis, which leads to a reduction in efficiency and effectiveness of the valve assembly.

As such, there remains a need for an improved valve assembly for use in an exhaust gas recirculation system.

SUMMARY OF THE INVENTION AND ADVANTAGES

A valve assembly includes a valve housing defining a flow passage configured to receive exhaust gas from an internal combustion engine, and defining a bore extending along a bore axis and fluidly coupled to said flow passage. The valve assembly also includes a valve body disposed in the bore for controlling the flow of exhaust gas through the bore. The valve assembly further includes a shaft extending along a shaft axis perpendicularly oriented with respect to the bore axis. The shaft is coupled to the valve body. The valve body is moveable between a closed position and an open position when the shaft rotates about the axis. The valve body restricts flow of exhaust through the bore when in the closed position, and the valve body allows the flow of exhaust through the bore when in the open position. The valve assembly additionally includes a first biasing member coupled to the shaft and configured to bias the shaft along the shaft axis in a first direction. The valve assembly also includes a second biasing member coupled to the shaft and configured to bias the valve body in the first direction along the shaft axis.

Accordingly, the valve assembly having the second biasing member configured to bias the valve body in the first direction along the shaft axis reduces axial movement of the valve body along the shaft axis during operation of the valve assembly, which leads to improved efficiency and effectiveness of the valve assembly.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the Figures, wherein like numerals indicate like parts throughout the several views, a valve assembly10is shown inFIGS. 1-4. The valve assembly10is typically used in an exhaust gas recirculation system12of a vehicle including an internal combustion engine. The exhaust gas recirculation system12typically includes an exhaust manifold14configured to receive exhaust gas from the internal combustion engine, and an intake manifold16configured to deliver exhaust gas to the internal combustion engine. The valve assembly10may also be used as a bypass valve, air control valves such as for a hydrogen engine, an exhaust tuning valve, and the like. The valve assembly10includes a valve housing18defining a flow passage20configured to receive exhaust gas from the internal combustion engine. The valve housing18defines a bore22extending along a bore axis BA. The bore axis BA is fluidly coupled to the flow passage20.

With reference toFIG. 1, the valve assembly10also includes a valve body24disposed in the bore for controlling the flow of exhaust gas through the bore22. The valve body24may be any suitable configuration for controlling the flow of exhaust gas through the bore22. By way of non-limiting example, the valve body24may be a plate. When the valve body24is a plate, the plate may have a circular or oval configuration. Additionally, when the valve body24is a plate, the valve assembly10may be referred to as a butterfly valve assembly.

The valve assembly10further includes a shaft26extending along a shaft axis SA perpendicularly oriented with respect to the bore axis BA. The shaft26is coupled to the valve body24. The valve body24is moveable between a closed position and an open position when the shaft26rotates about the shaft axis SA. The valve body24restricts flow of exhaust through the bore22when in the closed position, and the valve body24allows the flow of exhaust through the bore22when in the open position. To rotate the shaft26about the shaft axis SA, the valve assembly10may include an actuator28coupled to and configured to actuate the shaft26to move the valve body24between the open and closed positions.

As best shown inFIGS. 2-4, the valve assembly10includes a first biasing member30coupled to the shaft26and configured to bias the shaft26along the shaft axis SA in a first direction FD. The first biasing member30is typically configured to apply a first biasing force to the shaft26for biasing the shaft26in along the shaft axis SA in the first direction FD. Typically, the first biasing member30biases the shaft26by pulling the shaft26along the shaft axis SA in the first direction FD. Although the first biasing member30is not explicitly shown inFIG. 1, it is to be appreciated that the valve assembly10ofFIG. 1also includes the first biasing member30, which biases the shaft26along the shaft axis SA in the first direction FD. The first biasing member30biases the shaft26along the shaft axis SA in the first direction FD to position the shaft26and to reduce vibration of the shaft26and other components of the valve assembly.

With continued reference toFIG. 1, the valve assembly10includes a second biasing member32coupled to the shaft26and configured to bias the valve body24in the first direction FD along the shaft axis SA. The second biasing member32is typically configured to apply a second biasing force to the valve body24for biasing the valve body24in the first direction FD along the shaft axis SA, which reduces axial movement of the valve body24along the shaft axis SA. The second biasing member32may be a coil spring, spring plunger, wave washer, a bent metal beam, and the like.

Having the second biasing member32coupled to the shaft26and configured to bias the valve body24in the first direction FD along the shaft axis SA reduces axial movement of the valve body24along the shaft axis SA. Specially, thermal expansion of various components of the valve assembly10during operation of the valve assembly10, such as the shaft26and the valve body24, would cause the valve body24to move axially along the shaft axis SA in a second direction SD opposite the first direction FD due to thermal expansion of the shaft26if the second biasing member32was not present. In other words, during operation of the valve assembly10, the shaft26thermally expands in the second direction SD, which moves the valve body24in the second direction SD as well. However, having the second biasing member32coupled to the shaft26and biasing the valve body24in the first direction FD reduces axial movement of the valve body24along the shaft axis SA. Specifically, the second biasing member32may bias the valve body24into engagement with the valve housing18or a component coupled to the valve housing18that is stationary with respect to the shaft axis SA. The valve housing18or a component coupled to the valve housing18acts as a datum plane DP for the valve body24by determining where the valve body24is disposed in the bore22. Typically, the second biasing force applied to the valve body24by the second biasing member32is less then the first biasing force applied to the shaft26by the first biasing member30. The second biasing force may be less than the first biasing force because the second biasing member32typically only biases the valve body24, which is a smaller component than the shaft26, whereas the first biasing member30biases the shaft26for reducing vibration of the shaft26and other components of the valve assembly10.

The component of the valve assembly10coupled to the valve housing18may be a washer34disposed about the shaft26. In another embodiment, the component of the valve assembly10coupled to the valve housing18and disposed about the shaft26may be a bushing36. When the washer34and/or bushing is present, the valve body24is engageable with the washer34and/or bushing36when the second biasing member32biases the valve body24in the first direction FD such that the washer34and/or bushing36restricts movement of the valve body24in the first direction FD. To this end, despite the thermal expansion of various components of the valve assembly10during operation, such as the shaft26and the valve body24, which naturally expand with respect to the shaft axis SA in the second direction SD, the second biasing member32biases the valve body24in the first direction FD toward the washer34and/or bushing36such that the valve body24is limited in movement along the shaft axis SA in the first direction FD. As such, regardless of the thermal expansion of the shaft26with respect to the shaft axis SA, the valve body24remains centered in the bore22. Depending on where the valve body24is coupled to the shaft26with respect to the shaft axis SA, the washer34and/or bushing36may be placed such that when the valve body24is engaged with the washer34and/or bushing36, the valve body24is centered in the bore22with respect to the shaft axis SA. This ensures adequate sealing of the valve body24in the bore22because the valve body24is centered with respect to the bore22regardless of the thermal expansion of the shaft26and the valve body24.

The shaft26may define a shaft cavity38, such as a counterbore. When the shaft cavity38is present, the second biasing member32may be disposed in the shaft cavity38. The valve assembly10may include a biasing seat40disposed in the shaft cavity38for supporting the second biasing member32. To secure the biasing seat40, the shaft cavity38may have threads. Typically, the biasing seat40is stationary with respect to the shaft26. In one embodiment, the biasing seat40is a set screw.

The shaft26may define a shaft slot42extending away from the shaft axis SA, and the valve assembly10may also include a fastener44disposed in the shaft slot42and extending toward and coupled to the valve body24. When present, the second biasing member32biases the valve body24, through the fastener44, in the first direction FD. In other words, the second biasing member32biases against the fastener44, which, in turn, biases the valve body24in the first direction FD. The fastener44may be a screw, pin, rivet, bolt, and the like. The valve assembly10may include a ball, pin, or the like biased by the second biasing member32into engagement with the fastener44. As shown inFIG. 1, the valve assembly10includes a ball33.

The fastener44may be moveable along the shaft axis SA within the shaft slot42and the shaft cavity38. Typically, the fastener44is rigidly coupled to the valve body24such that the fastener44and the valve body24are moveable in unison with one another along the shaft axis SA independent of axial movement from the shaft26. To move within the shaft slot42with respect to the shaft axis SA, a diameter of the fastener44may be smaller than a diameter of the shaft slot42.

With particular reference toFIGS. 2-4, in one embodiment, the bore22is further defined as a first bore46extending along a first bore axis BA1, and the valve housing18defines a second bore48extending along a second bore axis BA2. In such embodiments, the valve housing18has a partitioning wall50separating and defining the first and second bores46,48. The valve body24is further defined as a first valve body52, and the valve assembly10further includes a second valve body54disposed in the second bore48for controlling the flow of exhaust through the second bore48. When present, the second valve body54is disposed between the first valve body52and the first biasing member30with respect to the shaft axis SA. The second valve body54is moveable between a closed position and an open position when the shaft26rotates about the shaft axis SA. When in the closed position, the second valve body54restricts flow of exhaust through the second bore48. When in the open position, the second valve body54allows the flow of exhaust through the second bore48. Typically, the first and second valve bodies52,54move in unison with one another between the open and closed positions when the shaft26rotates.

As described above, the valve assembly10may include the washer34disposed about the shaft26. In embodiments where the valve housing18defines the first and second bores46,48, the valve assembly10may include the bushing36be disposed between the first valve body52and the second valve body54with respect to the shaft axis SA. In such embodiments, the first valve body52is engageable with the washer34when the second biasing member32biases the first valve body52in the first direction FD such that the washer34restricts movement of the first valve body52in the first direction FD. Alternatively, the first valve body52may be engageable with the partitioning wall50. Alternatively, the first valve body52may be engageable with the bushing36. When the bushing36and the washer34are present, the bushing36may be disposed between the washer34and the second valve body54.

In embodiments where the valve assembly10includes the first and second valve bodies52,54, having the second biasing member32coupled to the shaft26and configured to bias the first valve body52in the first direction FD along the shaft axis SA reduces axial movement of the first valve body52along the shaft axis SA. In such embodiments, thermal expansion of various components of the valve assembly10during operation of the valve assembly10, such as the shaft26, would cause the first valve body52to move axially along the shaft axis SA in the second direction SD due to thermal expansion of the shaft26if the second biasing member32was not present. Even further, in such embodiments, the shaft26may have a longer length than when the valve assembly10only includes a single valve body24, as shown inFIG. 1. As such, thermal expansion of the shaft26would move the first valve body52further along the shaft axis SA in the second direction SD than the second valve body54. To this end, having the second biasing member32configured to bias the first valve body52in the first direction FD allows the first valve body52to be movable along the shaft axis independent from the shaft26.

In one embodiment, the second valve body54and the shaft26are rigidly coupled to one another such that the second valve body54and the shaft26are moveable in unison with one another along the shaft axis SA. In such embodiments, the second biasing member32biases the first valve body52in the first direction FD independent from movement of the second valve body54in the second direction SD during operation of the valve assembly10.

In embodiments where the valve assembly10includes the first and second valve bodies52,54, the second biasing member32may bias the second valve body54into engagement with the valve housing18, such as the partitioning wall50, or a component coupled to the valve housing18that is stationary with respect to the shaft axis SA. The valve housing18or a component coupled to the valve housing18acts as the datum plane DP for the first valve body52by determining where the first valve body52is disposed and positioned in the first bore46. As such, the first valve body52, due to the biasing of the second biasing member32, may stay stationary with respect to the shaft axis SA as components of the valve assembly10, such as the shaft26, expand and contract during operation of the valve assembly10.

As described above, the component of the valve assembly10coupled to the valve housing18in the embodiment where the valve assembly10includes the first and second valve bodies52,54similarly may be the washer34disposed about the shaft26. In another embodiment, the component of the valve assembly10coupled to the valve housing18may be the bushing36. When the washer34and/or bushing36is present, the first valve body52is engageable with the washer34and/or bushing36when the second biasing member32biases the first valve body52in the first direction FD such that the washer34and/or bushing36restricts movement of the first valve body52in the first direction FD. To this end, despite the thermal expansion of various components of the valve assembly10, such as the shaft26and the first valve body52, which expand with respect to the shaft axis SA, the second biasing member32biases the first valve body52in the first direction FD toward the washer34and/or bushing36such that the first valve body52is limited in movement along the shaft axis SA in the first direction FD. As such, regardless of the thermal expansion of the shaft26with respect to the shaft axis SA, the first valve body52remains centered in the first bore46. Depending on where the first valve body52is coupled to the shaft26with respect to the shaft axis SA, the washer34and/or bushing36may be placed such that when the first valve body52is engaged with the washer34, the first valve body52is centered in the first bore46with respect to the shaft axis SA. This ensures adequate sealing of the first valve body52in the first bore46because the first valve body52is centered with respect to the first bore46regardless of the thermal expansion of the shaft26and the first valve body52.