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 member shaft of the waste gate valve. The coupling of the ends of the linkage to the cranks is usually accomplished by a pin and retaining clip arrangement. Thus, the crank has a pin projecting therefrom, and the outer surface of the pin near the distal end thereof defines a circular groove encircling the pin. The linkage defines a through-bore that receives the pin. A generally C-shaped or E-shaped retaining clip (often called a circlip or e-ring) is snapped into the circular groove to capture the linkage and prevent it from being removed from the pin. For example, <CIT> discloses such a crank and linkage assembly.

There are drawbacks to this conventional linkage and crank assembly. One issue is that unless additional components such as a wave spring are added to the assembly, the linkage is subject to excessive play in the direction parallel to the axis of the pin. A wave spring or the like can reduce the play, but this solution comes with additional cost and parts count. Additionally, the retaining clip can be subject to stress corrosion cracking, which can cause the clip to break and compromise the integrity of the linkage-to-crank connection.

The present disclosure describes a crank and linkage 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 linkage and the pin of the crank.

In accordance with one embodiment disclosed herein, a crank is provided having a cylindrical pin extending therefrom along a pin axis and terminating at a distal end of the pin. An outer surface of the pin defines a circular pin groove therein encircling the pin axis, the pin groove being spaced along the pin axis from the crank. The pin, distal of the pin groove, comprises a tapered end. A linkage is provided, comprising an elongate member, the linkage defining a through bore adjacent an end of the linkage, an inner surface of the through bore defining a circular linkage groove therein. To connect the linkage to the pin of the crank, there is provided a retaining ring comprising an elastically deformable wire formed into a generally polygonal non-closed configuration (i.e., having a gap between the two ends of the wire) such that the retaining ring defines a plurality of vertices and a plurality of sides. The retaining ring optionally can have three vertices and two sides, three vertices and three sides, four vertices and three sides, four vertices and four sides, five vertices and four sides, etc..

The retaining ring is installed in the linkage groove such that each of said plurality of vertices is within the linkage groove. The linkage can be assembled with the crank by pushing it onto the pin. Thus, the tapered end of the pin is inserted into the through bore of the linkage to cause the tapered end to elastically deform the sides of the retaining ring radially outwardly. Once the pin groove is aligned with the linkage groove, the sides of the retaining ring move radially inwardly, by elastic restoring force of the wire, and at least two of the sides have portions that engage the pin groove. The retaining ring restrains movement of the linkage along the pin axis, while allowing the linkage to rotate relative to the pin about the pin axis.

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> illustrate a turbocharger <NUM> in accordance with an embodiment of the invention. The turbocharger comprises a compressor <NUM> having a compressor wheel <NUM> 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 <NUM> 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 <NUM> 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> and <FIG>) arranged in a bypass passage <NUM> (<FIG>) defined by the turbine housing. The bypass passage connects between the chamber <NUM> 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> and <FIG>, regulation of the waste gate valve <NUM> 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. To this end, the first crank includes a first pin P1 mounted adjacent an opposite end of the crank from the end affixed to the valve shaft <NUM>. The corresponding end of the linkage L defines a through bore that receives the pin P1, and a retaining ring <NUM> captively connects the linkage to the pin in a manner described below. Similarly, the other end of the linkage defines a through bore that receives the second pin P2, and a retaining ring <NUM> captively connects the linkage to the second pin. Similar structures can be used for both retaining rings <NUM> and <NUM>, and therefore the remaining description will focus only on the ring <NUM> for brevity.

The installation of the retaining ring <NUM> in the end of the linkage L is now explained with reference to <FIG>. As noted, the first end of the linkage defines a through bore B1. The inner surface of the bore defines a circular linkage groove LG encircling the central axis of the bore. The retaining ring <NUM> comprises an elastically deformable wire that is formed into a generally polygonal shape that is non-closed, i.e., a gap G (<FIG>) remains between the opposite ends of the wire. The radial depth and the axial length of the linkage groove are sized in relation to the diameter of the wire so that portions of the wire can be received into the linkage groove.

With particular reference to <FIG>, 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. The ring is formed to have a plurality of vertices and a plurality of sides each of which extends between two of said vertices. In the embodiment of <FIG>, the retaining ring is generally rectangular, having four vertices V and three sides S. The gap G occupies most of what would be the fourth side of the rectangle. 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. Providing the retaining ring with vertices and sides enables the vertices of the ring to be engaged in the linkage groove while the sides remain radially inward of the radially outer wall of the linkage groove, as best seen in <FIG>. Advantageously, the retaining ring <NUM> is pre-installed in the linkage as shown in <FIG>, prior to connection to the pin of the crank C1, which will now be described with reference to <FIG>.

As depicted in <FIG>, the pin P1 of the first crank C1 extends along a pin axis PA 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. Distal of the pin groove, the pin defines a tapered end TE. Connection of the linkage having the pre-installed retaining ring to the pin of the crank 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 (compare <FIG> before deformation by the pin, and <FIG> after deformation).

Pushing the linkage further onto the pin then will cause the linkage groove LG 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 linkage groove LG as depicted in <FIG>. The retaining ring thus captively retains the linkage in connection with the pin to restrain axial movement of the linkage along the pin axis, while allowing the linkage to rotate relative to the pin about the pin axis.

<FIG> illustrate a second embodiment of the invention in which the retaining ring <NUM>' has a generally pentagonal configuration. As seen in <FIG> in which the retaining ring is pre-installed in the linkage groove LG of the linkage L (and in that state is relaxed or only slightly compressed radially inwardly by the outer wall of the groove), the retaining ring of the second embodiment is formed substantially as a pentagon, but in a non-closed form. A pentagon has five sides and five vertices, but the retaining ring <NUM>' has five sides S and only four vertices V because what would have been the fifth vertex is occupied by the gap between the ends of the wire. The retaining ring <NUM>' functions substantially like the retaining ring <NUM> of the first embodiment. The tapered end TE of the pin expands the sides of the retaining ring radially outwardly as the linkage is pushed onto the pin, and once the linkage groove LG becomes aligned with the pin groove PG, the sides return toward their original configuration and the ring's vertices V are engaged in the linkage groove while the sides S are engaged in the pin groove.

<FIG> depict a third embodiment of the invention having a retaining ring <NUM>" with a substantially triangular configuration having three vertices V and three sides S, but one of the sides is interrupted by the gap between the ends of the wire, and therefore only two sides are engaged in the pin groove when the connection is made. The retaining ring <NUM>" functions substantially like the retaining rings of the previous embodiments. The tapered end TE of the pin expands the sides of the retaining ring radially outwardly as the linkage is pushed onto the pin, and once the linkage groove LG becomes aligned with the pin groove PG, the retaining ring returns toward its original configuration and the ring's vertices V are engaged in the linkage groove while the sides S are engaged in the pin groove.

Claim 1:
A crank and linkage assembly for a turbocharger, comprising:
a first crank (C1) having a cylindrical first pin (P1) extending therefrom along a first pin axis and terminating at a distal end of the first pin, an outer surface of the first pin defining a circular first pin groove (PG) therein encircling the first pin axis, the first pin groove being spaced along the first pin axis from the first crank;
a linkage (L) comprising an elongate member and extending from a first end to a second end, the linkage defining a first through bore (B1) adjacent the first end and a second through bore adjacent the second end, an inner surface of the first through bore defining a circular first linkage groove (LG) therein, a lengthwise portion of the first pin being disposed within the first through bore of the linkage such that the first linkage groove is aligned with the first pin groove; and
a first retaining ring (<NUM>) comprising an elastically deformable wire formed into a generally polygonal non-closed configuration such that the first retaining ring defines a plurality of vertices and a plurality of sides, wherein each of said plurality of vertices is within the first linkage groove and at least two of the plurality of sides has a portion engaged in the first pin groove, thereby restraining movement of the first end of the linkage along the first pin axis while allowing rotational movement of the linkage about the first pin axis.