Patent Description:
An exhaust gas-driven turbocharger is a device used in conjunction with an internal combustion engine for increasing the power output of the engine by compressing the air that is delivered to the air intake of the engine to be mixed with fuel and burned in the engine. A turbocharger comprises a compressor wheel mounted on one end of a shaft in a compressor housing and a turbine wheel mounted on the other end of the shaft in a turbine housing. The turbine housing defines a generally annular chamber that surrounds the turbine wheel and that receives exhaust gas from an engine. The turbine assembly includes a nozzle that leads from the chamber into the turbine wheel. The exhaust gas flows from the chamber through the nozzle to the turbine wheel and the turbine wheel is driven by the exhaust gas, which is then discharged into an exhaust conduit that may be connected to further treatment devices such as a catalytic device and/or sound-attenuating muffler. The turbine thus extracts power from the exhaust gas and drives the compressor. The compressor receives ambient air through an inlet of the compressor housing and the air is compressed by the compressor wheel and is then discharged from the housing to the engine air intake.

The turbine of the turbocharger typically includes a valve (often called a waste gate valve) arranged in the turbine housing in a location such that opening the valve causes the majority of exhaust gases coming from the engine to bypass the turbine wheel and proceed directly into the exhaust conduit. The waste gate valve enables the power-extraction of the turbine to be controlled, thereby controlling the amount of boost provided by the compressor. Thus, the waste gate valve can be either closed, partially opened to various degrees, or fully open, depending upon the operating condition of the engine and the amount of boost desired from the turbocharger.

The waste gate valve is typically actuated by a rotary actuator whose output shaft is connected to a crank. The actuator crank is rotatably coupled to one end of a linkage, and the opposite end of the linkage is rotatably coupled to a crank affixed to the valve shaft of the waste gate valve. An arm on the distal end of the valve shaft is connected to the poppet of the valve, typically by a pin projecting from the poppet and received through a bore in the arm. A disc washer is riveted to a distal end of the pin, with a spring washer disposed between the disc washer and the arm. There are drawbacks to this conventional linkage assembly, such as the difficulty of controlling the quality of the connection between the poppet and the arm. Documents cited during prosecution include <CIT>; <CIT>; <CIT>; and <CIT>.

The present disclosure describes a waste gate assembly for a turbocharger that can mitigate or eliminate the drawbacks noted above, and achieve further advantages noted herein. In particular, the disclosed assembly can simplify the assembly process by facilitating a push-to-connect process between the valve member arm and the pin of the poppet.

Aspects and preferred embodiments of the invention are defined in the appended claims. Disclosed herein is a waste gate assembly comprising:.

a retaining ring comprising an elastically deformable wire formed into a generally polygonal non-closed configuration such that the retaining ring defines a plurality of vertices and a plurality of sides and two ends, wherein each of said plurality of vertices is within the arm groove and at least two of the plurality of sides has a portion engaged in the pin groove, thereby restraining movement of the arm along the pin axis, wherein the retaining ring has a non-planar free shape such that the retaining ring is configured to exert a biasing force on the poppet and further comprising an anti-rotation feature preventing rotational movement of the poppet relative to the arm about the pin axis, whereby rotation of the valve shaft about the shaft axis causes the arm to move the poppet along an arc about the valve axis.

The retaining ring not only effects a connection between the arm and the poppet in a simple and repeatable fashion, but the retaining ring also provides a biasing force on the poppet (i.e., a pre-load force) urging the poppet away from the arm and toward the valve seat when the valve is closed. Additionally, the retaining ring allows a small amount of movement of the poppet relative to the arm in the direction of the through-bore's axis. These characteristics allow the poppet to form a secure seal against the valve seat.

The anti-rotation feature in one embodiment is formed by shape-locking between the pin having a non-round cross-sectional shape and the through bore in the arm having a corresponding non-round cross-sectional shape.

In another embodiment, the anti-rotation feature comprises a recess defined in the arm and a projection or key formed on the poppet, the key being received into the recess to prevent rotation of the poppet.

In some embodiments, the two ends of the retaining ring extend into the recess defined in the arm.

In other embodiments, the arm defines a slot extending from an outer surface of the arm to the through bore, and the two ends of the retaining ring extend through the slot.

Having described the present disclosure in general terms, reference will now be made to the accompanying drawing(s), which are not necessarily drawn to scale, and wherein:.

The present disclosure will now be described in fuller detail with reference to the above-described drawings, which depict some but not all embodiments of the invention(s) to which the present disclosure pertains. These inventions may be embodied in various forms, including forms not expressly described herein, and should not be construed as limited to the particular exemplary embodiments described herein. In the following description, like numbers refer to like elements throughout.

<FIG> illustrates a turbocharger <NUM>. The turbocharger comprises a compressor <NUM> having a compressor wheel (not visible) mounted within a compressor housing <NUM> defining an air inlet <NUM> for the compressor, and a turbine <NUM> comprising a turbine wheel <NUM> (<FIG>) mounted within a turbine housing <NUM> and connected to a shaft (not visible) that also connects with the compressor wheel. A center housing <NUM> is disposed between and secured to the compressor housing and turbine housing, and contains bearings for the shaft.

The turbine housing <NUM> defines an annular chamber surrounding the turbine wheel <NUM> for receiving exhaust gas from an internal combustion engine (not shown). Exhaust gas is directed from the chamber via a turbine nozzle onto the turbine wheel. In some operating conditions, it is desirable to cause some of the exhaust gas to bypass the turbine wheel and proceed directly into the downstream exhaust conduit, and to this end, turbochargers typically include a waste gate valve <NUM> (<FIG>) arranged for opening and closing a bypass passage <NUM> (<FIG>) defined by the turbine housing. The bypass passage connects between the exhaust gas chamber and the discharge bore of the turbine housing downstream of the turbine wheel. Thus, when the waste gate valve is opened, some of the exhaust gas passes through the valve and thereby bypasses the turbine wheel.

With reference to <FIG>, regulation of the waste gate valve is accomplished by an actuator <NUM> connected to the valve via a kinematic linkage arrangement comprising a first crank C1, a linkage L, and a second crank C2. The valve <NUM> has a rotary valve shaft <NUM>, and one end of the first crank C1 is rigidly affixed to the valve shaft. The actuator <NUM> has a rotary output shaft <NUM>, and one end of the second crank C2 is rigidly affixed to the output shaft. A first end of the linkage L is rotatably coupled to the first crank C1, and the opposite second end of the linkage is rotatably coupled to the second crank C2. Accordingly, rotation of the actuator shaft <NUM> causes two cranks and the linkage to impart rotation to the valve shaft <NUM>.

As best seen in <FIG> and <FIG>, the turbine housing defines a bearing hole <NUM> in which a bushing <NUM> is installed, and the valve shaft <NUM> of the waste gate valve extends through the bushing, which allows the shaft to rotate about its axis and thereby cause the valve to open or close the bypass passage <NUM>. To this end, the turbine housing defines valve seat <NUM> the surrounds the open end of the bypass passage. The waste gate valve includes a poppet <NUM> having a disc shape and being sized and configured to abut the valve seat <NUM> so that the poppet closes the bypass passage. The poppet includes an integral pin P projecting from the center of the poppet normal to the plane of the disc. The pin is received into a through bore <NUM> formed at a distal end of an arm <NUM> that is affixed to the end of the valve shaft <NUM>, the arm extending at an oblique angle to the valve shaft axis. The connection of the pin to the arm is accomplished by a retaining ring <NUM> in a manner described below.

The retaining ring <NUM> is formed from elastically deformable wire by any suitable process such as a rolling process as commonly used for rolling springs and the like, so that the retaining ring has a generally polygonal shape that is non-closed, i.e., a gap remains between the opposite ends of the wire. As shown in <FIG>, the ring is formed to have a plurality of vertices V and a plurality of sides S each of which extends between two of said vertices. In <FIG>, the retaining ring is generally U-shaped, having two vertices V and three sides S. The terms "vertex" and "vertices" do not require or imply that they must be sharp corners, which in practice would be impossible, it always being necessary to have a non-zero radius of curvature of the wire at each vertex. Also, the term "side" does not require or imply that the sides must be linear, although linear sides can be used as shown in the drawings.

As noted, the arm <NUM> defines a through bore <NUM>. The inner surface of the bore defines an arm groove AG at least partially encircling the central axis of the bore. The radial depth and the axial length of the arm groove are sized in relation to the diameter of the wire so that portions of the wire can be received into the arm groove.

Providing the retaining ring with vertices and sides enables the vertices V of the ring to be engaged in the arm groove AG while the sides S remain radially inward of the radially outer wall of the arm groove, as best seen in <FIG>. Advantageously, the retaining ring <NUM> is pre-installed in the arm <NUM> as shown in <FIG>, prior to connection to the pin of the poppet. To facilitate the installation of the retaining ring into the arm, the arm includes a slot <NUM> that extends from an outer face of the arm into the through bore <NUM>. The retaining ring is pushed through this slot until the vertices of the retaining ring are seated into the arm groove. The two ends of the retaining ring wire are flared away from each other with a spacing that exceeds the width of the slot <NUM>. When the retaining ring is fully installed into the arm, the two ends of the wire project out from the slot and are compressed toward each other by the side walls of the slot (compare <FIG> and <FIG>).

With respect to <FIG>, the through bore <NUM> in the arm <NUM> of the valve member is non-round. In the illustrated example, the shape of the bore comprises a circle with a flat on one side. As shown in <FIG>, the pin P on the poppet <NUM> correspondingly has a non-round cross-sectional shape consisting of a circle with a flat F on one side, complementing the non-round bore <NUM> in the arm. Accordingly, shape-locking occurs between these complementary shapes such that the poppet is prevented from rotating about the pin axis relative to the arm, thus comprising a non-rotation feature for the valve arrangement.

With respect to now to <FIG>, a push-to-connect process for connecting the poppet to the arm of the valve member is described. In these figures, a portion of the arm <NUM> has been removed so that the retaining ring <NUM> can be seen. <FIG> shows the unconnected assembly prior to the push-to-connect process. The pin P of the poppet <NUM> extends along a pin axis and terminates at a distal end. The generally cylindrical outer surface of the pin defines a pin groove PG therein. The radial depth and axial length of the pin groove are selected in relation to the diameter of the wire forming the retaining ring <NUM>. Distal of the pin groove, the pin defines a tapered end TE. Connection of the arm <NUM> having the pre-installed retaining ring <NUM> to the pin of the poppet is a simple push-to-connect process in which the tapered end of the pin contacts and urges the retaining ring to radially expand. More particularly, it is the sides S of the ring that are resiliently deformed radially outwardly (see <FIG>).

Pushing the arm further onto the pin then will cause the arm groove AG to become aligned with the pin groove PG as best seen in <FIG>. Once these grooves become aligned, the retaining ring <NUM> resiliently returns toward its relaxed state, under the restoring force of the wire, and as a result, the sides S of the ring become engaged in the pin groove PG of the pin. At the same time, the vertices V of the retaining ring are engaged in the arm groove AG as depicted in <FIG>. The retaining ring thus captively retains the arm in connection with the pin to restrain axial movement of the arm along the pin axis. As previously noted, the arm is prevented from rotating relative to the pin by the shape-locking between the pin and the arm bore. The retaining ring allows a small amount of movement of the poppet <NUM> relative to the arm <NUM> along the axial direction of the through-bore <NUM>. Furthermore, when the retaining ring has a non-planar free shape (as in the embodiments of <FIG>, for example), it also exerts a biasing force on the poppet tending to urge the poppet against the valve seat when the valve is closed.

<FIG> illustrate a second example in which the retaining ring <NUM>' has a different configuration and the anti-rotation feature also differs from that of the first example. As seen in <FIG>, the modified arm <NUM>' has a through bore <NUM>' that is generally circular but connects with a further recess R in the arm to form a keyhole shape. The poppet <NUM>' includes a key K comprising a short post or projection on one side of and extending parallel to the pin P'. When the poppet is connected to the arm <NUM>', the key fits into the bottom side of the recess R and thereby prevents the poppet from rotating about the pin. The retaining ring <NUM>' (<FIG>) is generally Omega-shaped, having four vertices V and three sides S. <FIG> shows the retaining ring pre-installed in the arm groove AG of the arm <NUM>' (and in that state is relaxed or only slightly compressed radially inwardly by the outer wall of the groove). The two ends of the wire extend into the recess R. The retaining ring <NUM>' functions substantially like the retaining ring <NUM> of the first example. The tapered end TE of the pin expands the sides of the retaining ring radially outwardly as the arm is pushed onto the pin (<FIG>), and once the arm groove AG becomes aligned with the pin groove PG, the sides return toward their original configuration and the ring's vertices V are engaged in the arm groove while the sides S are engaged in the pin groove (<FIG>).

Claim 1:
A waste gate assembly for a turbocharger, comprising:
a valve member comprising a poppet (<NUM>, <NUM>') having a pin extending therefrom along a pin axis and terminating at a distal end of the pin, an outer surface of the pin defining a pin groove therein at least partially encircling the pin axis, the pin groove being spaced along the pin axis from the poppet;
a valve shaft (<NUM>, <NUM>') extending along a shaft axis;
an arm (<NUM>, <NUM>') affixed to one end of the valve shaft and extending therefrom at an oblique angle relative to the shaft axis and terminating at a distal end, the distal end defining a through bore (<NUM>, <NUM>') adjacent the distal end, an inner surface of the through bore defining an arm groove therein, a lengthwise portion of the pin being disposed within the through bore of the arm such that the arm groove is aligned with the pin groove; and
a retaining ring (<NUM>, <NUM>', <NUM>, <NUM>) comprising an elastically deformable wire formed into a substantially polygonal non-closed configuration such that the retaining ring defines a plurality of vertices and a plurality of sides and two ends, wherein each of said plurality of vertices is within the arm groove and at least two of the plurality of sides has a portion engaged in the pin groove to thereby restrain movement of the arm along the pin axis, wherein the retaining ring has a non-planar free shape such that the retaining ring is configured to exert a biasing force on the poppet, and;
an anti-rotation feature preventing rotational movement of the poppet relative to the arm about the pin axis, whereby rotation of the valve shaft about the shaft axis causes the arm to move the poppet along an arc about the valve axis.