Patent Application
20100104424
This invention is directed to a turbocharging system for an internal combustion engine and more particularly to variable turbine geometry of a turbocharging system.
Turbochargers are a type of forced induction system. They compress the air flowing into an engine, thus boosting the engine's horsepower without significantly increasing weight. Turbochargers use the exhaust flow from the engine to spin a turbine, which in turn drives an air compressor. Since the turbine spins about 30 times faster than most car engines and it is hooked up to the exhaust, the temperature in the turbine is very high. Additionally, due to the resulting high velocity of flow, turbochargers are subjected to noise and vibration. Such conditions can have a detrimental effect on the components of the turbocharger, particularly on the rotating parts such as the turbine rotor, which can lead to failure of the system.
Turbochargers are widely used on internal combustion engines and, in the past, have been particularly used with large diesel engines, especially for highway trucks and marine applications. More recently, in addition to use in connection with large diesel engines, turbochargers have become popular for use in connection with smaller, passenger car power plants. The use of a turbocharger in passenger car applications permits selection of a power plant that develops the same amount of horsepower from a smaller, lower mass engine. Using a lower mass engine has the desired effect of decreasing the overall weight of the car, increasing sporty performance, and enhancing fuel economy. Moreover, use of a turbocharger permits more complete combustion of the fuel delivered to the engine, thereby reducing the overall emissions of the engine, which contributes to the highly desirable goal of a cleaner environment. The design and function of turbochargers are described in detail in the prior art, for example, U.S. Pat. Nos. 4,705,463, 5,399,064, and 6,164,931, the disclosures of which are incorporated herein by reference.
Turbocharger units typically include a turbine operatively connected to the engine exhaust manifold, a compressor operatively connected to the engine air intake manifold, and a shaft connecting the turbine and compressor so that rotation of the turbine wheel causes rotation of the compressor impeller. The turbine is driven to rotate by the exhaust gas flowing in the exhaust manifold. The compressor impeller is driven to rotate by the turbine, and, as it rotates, it increases the air mass flow rate, airflow density and air pressure delivered to the engine cylinders.
As the use of turbochargers finds greater acceptance in passenger car applications, three design criteria have moved to the forefront. First, the market demands that all components of the power plant of either a passenger car or truck, including the turbocharger, must provide reliable operation for a much longer period than was demanded in the past. That is, while it may have been acceptable in the past to require a major engine overhaul after 80,000-100,000 miles for passenger cars, it is now necessary to design engine components for reliable operation in excess of 200,000 miles of operation. It is now necessary to design engine components in trucks for reliable operation in excess of 1,000,000 miles of operation. This means that extra care must be taken to ensure proper fabrication and cooperation of all supporting devices.
The second design criterion that has moved to the forefront is that the power plant must meet or exceed very strict requirements in the area of minimized NOx and particulate matter emissions. Third, with the mass production of turbochargers, it is highly desirable to design a turbocharger that meets the above criteria and is comprised of a minimum number of parts. Further, those parts should be easy to manufacture and easy to assemble, in order to provide a cost effective and reliable turbocharger. Due to space within the engine compartment being scarce, it is also desirable that the overall geometric package or envelope of the turbocharger be minimized.
U.S. Pat. No. 6,877,955 to Higashimori shows a turbocharger with a radial flow to the turbine. As shown in
The Higashimori radial flow system suffers from the drawback of providing only radial flow to the turbine wheel which would not operate efficiently over a wide range of incident angles. The application of only radial flow would cause a drop in efficiency at required engine operating conditions in such a design.
Thus, there is a need for a turbocharger system, and method of manufacturing such a system, that effectively and efficiently controls application of exhaust gas to the turbine wheel.
The exemplary embodiments of the turbocharger drive the turbine wheel utilizing both an axial flow component and a radial flow component of the exhaust gas in a variable turbine geometry (VTG) environment. The mixed flow can be provided by a number of techniques including extended tips of the turbine wheel, secondary flow and leakage flow.
In one aspect of the invention, a turbocharger is provided having a turbine wheel with a plurality of extended tips; and a variable turbine geometry assembly in fluid communication with the turbine wheel and having a nozzle ring with a plurality of vanes movably attached thereto. One or more of the extended tips are non-parallel with an edge of one or more of the plurality of vanes.
In another aspect, a the method is provided that involves providing an exhaust gas flow to a turbine wheel of a variable turbine geometry turbocharger, wherein the exhaust gas flow is a mixed flow having both a radial component and an axial component. The mixed flow is formed by at least one of leakage gas, secondary flow and a non-parallel incidence angle of the turbine wheel.
The present invention is illustrated by way of example and not limitation in the accompanying drawings in which like reference numbers indicate similar parts, and in which:
Embodiments of the invention are directed to mixed flow along a turbine wheel in a turbocharger for driving a compressor for delivery of a compressed fluid to an internal combustion engine. Aspects of the invention will be explained in connection with a turbine section having a particular turbine wheel geometry, but the detailed description is intended only as exemplary. Exemplary embodiments of the invention are shown in
Referring to
The exhaust gases are provided to the guide vanes 7 and rotor 4 by a supply channel 9 having an inlet 99. The exhaust gases are discharged through a central short feed pipe 10, and the rotor 4 drives the compressor wheel, impeller or rotor 21 fastened to the shaft 20 of the wheel. The present disclosure also contemplates one or more of turbine housing 2, center housing 3 and compressor housing 3a being integrally formed with each other.
In order to control the position of the guide vanes 7, an actuation device 11 can be provided having a control housing 12, which controls an actuation movement of a pestle member 14 housed therein, whose axial movement is converted into a rotational movement of an adjustment or control ring 5 situated behind the support ring 6. By this rotational movement, the guide vanes 7 may be displaced from a substantially tangential extreme position into a substantially radially extending extreme position. In this way, a larger or smaller amount of exhaust gases from a combustion motor supplied by the supply channel 9 can be fed to the turbine rotor 4, and discharged through the axial feed pipe 10.
Between the vane support ring 6 and a ring-shaped portion 15 of the turbine housing 2, there can be a relatively small space 13 to permit free movement of the vanes 7. The shape and dimensions of the vane space 13 can be chosen to increase the efficiency of the turbocharger 1, while allowing for thermal expansion due to the hot exhaust gases. To ensure the width of the vane space 13 and the distance of the vane support ring 6 from the opposite housing ring 15, the vane support ring 6 can have spacers 16 formed thereon. Various other turbocharger components can also be used with compressor wheel 21 and turbocharger 1.
Turbocharger 1 can have a mixed flow turbine wheel 4 formed by a non-zero blade inlet angle, an inlet with a varying radius from the center axis or a combination of both. The exemplary embodiment of
In a variable turbine geometry turbocharger, the vanes 7 are the predominant factor controlling the relative turbine wheel blade incidence angle. As a result, the turbocharger can be forced to operate over a much wider range of incidence angles. The use of the mixed flow turbine wheel 4 in combination with a variable turbine geometry, (i.e., vanes 7) allows the turbocharger 1 to maintain higher efficiency over a much wider range of incidence angles. In one embodiment, the variable turbine geometry can compensate for any increased inertia due to the turbine wheel geometry by throttling the inlet flow for an improved transient response.
Referring to
The VTG vanes 7 can control the flow angle into the turbine wheel 4′ and can directly affect the magnitude of the tangential and radial flow vectors. In one embodiment, where the mixed flow turbine wheel 4′ is less incidence angle sensitive, then the wheel can maintain a higher overall efficiency over a wider range of incidence angles (tangential/radial components) than a traditional radial inflow wheel.
In another embodiment, a variable turbine geometry turbocharger can have an axial component of the exhaust gas flow generated by leakage flow, secondary flow or a combination of both. This can be used in combination with the extended tips 400 and 400′. In yet another embodiment, the vane 7 can be parallel to the angle of the turbine wheel. In such an embodiment, the VTG vane trailing edge is not radial and has a matching angle to the turbine wheel inlet (or similar angle).
Although a turbine wheel has been described herein with great detail with respect to an embodiment suitable for the automobile or truck industry, it will be readily apparent that the turbine wheel and the process for production thereof are suitable for use in a number of other applications, such as fuel cell powered vehicles. Although this invention has been described in its preferred form with a certain of particularity with respect to an automotive internal combustion compressor wheel, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of structures and the composition of the combination may be resorted to without departing from the spirit and scope of the invention.
It is also contemplated by the present disclosure that the features of the turbochargers and/or housings can be used with other types of fluid impelling devices where a particular length of a diffuser is desired. Such other fluid impelling devices include, but are not limited to, the following: superchargers; centrifugal pumps; centrifugal fans; single-stage gas compressors; multistage gas compressors; and other kinds of devices which generally use one or more rotating elements to compress gases and/or induce fluid flow.
While the invention has been described by reference to a specific embodiment chosen for purposes of illustration, it should be apparent that numerous modifications could be made thereto by those skilled in the art without departing from the spirit and scope of the invention.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US08/61875 | 4/29/2008 | WO | 00 | 10/27/2009 |
| Number | Date | Country | |
|---|---|---|---|
| 60916175 | May 2007 | US |
