Patent Application
20160319744
The present disclosure relates to a turbocharged internal combustion engine and more particularly to an improved thrust bearing design for improved lubrication.
This section provides background information related to the present disclosure which is not necessarily prior art.
Internal combustion engines are used to generate considerable levels of power for prolonged periods of time on a dependable basis. Many such engine assemblies employ a supercharging device, such as an exhaust gas turbine driven turbocharger, to compress the airflow before it enters the intake manifold of the engine in order to increase power and efficiency.
Specifically, a turbocharger utilizes a centrifugal gas compressor that forces more air and, thus, more oxygen into the combustion chambers of the engine than is otherwise achievable with ambient atmospheric pressure. The additional mass of oxygen-containing air that is forced into the engine improves the engine's volumetric efficiency, allowing it to burn more fuel in a given cycle, and thereby produce more power.
A typical turbocharger employs a central shaft that is supported by one or more bearings and transmits rotational motion between an exhaust-driven turbine wheel and an air compressor wheel. Both the turbine and compressor wheels are fixed to the shaft, which in combination with various bearing components constitute the turbocharger's rotating assembly. It is important to maintain lubrication of the turbocharger thrust bearing. Test results show that low lubrication flow upstream and high flow at the outlet due to large centrifugal force at high speed cause a mist lubrication condition in the thrust bearing cavity. The mist lubrication condition in the bearing cavity in current thrust plate designs can starve the thrust pads and reduce the thrust bearing's load capacity.
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
A turbocharger is provided including a turbine wheel and a compressor wheel attached to one another by a shaft. A thrust plate includes a plate body having an aperture there through and defining a plurality of circumferentially spaced pad regions that define a land region that is perpendicular to a rotational axis of the shaft. The pad regions further define a plurality of two-stage slope regions adjacent to each of the land regions. The two stage slope regions include a steep slope portion and a gradual slope portion disposed between the steep slope portion and the land regions. The rotary assembly of the turbocharger includes a thrust surface that engages the land regions. The two-stage slope regions provide improved loading capacity by the combination of better lubricant oil availability due to the steep slope region and optimized tribological performance due to the gradual slope region.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Example embodiments will now be described more fully with reference to the accompanying drawings.
Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.
When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
An engine assembly 10 is illustrated in
As shown in
As further shown in
With continued reference to
As shown in
The thrust bearing assembly 56 counteracts the net thrust force developed within the turbocharger 26, when such a force is acting towards the compressor wheel 42. As shown, the thrust bearing assembly 56 is positioned on the shaft 28, between the journal bearing 48 and the compressor wheel 42. The bearing assembly 56 is lubricated and cooled by the supply of pressurized engine oil supplied via a pump (not shown). During operation of the turbocharger 26, i.e., when the turbine wheel 36 is energized by the combustion exhaust gases, the thrust washer 62 transmits thrust forces developed by the turbine wheel to the thrust plate 64. Although the thrust washer 62 is shown, it should be understood that alternative thrust surfaces can be otherwise formed on the shaft 28 such as an integrally formed or separately formed shoulder.
With reference to
The land regions 72 and two-stage slope regions 74 are designed so that the steep slope region 74A provides a larger area to take more lubricant oil from the cavity, which is particularly favorable when the cavity is at mist lubrication condition. Meanwhile, the bearing loading capacity is still optimized by the gradual slope region 74B. The loading capacity is improved significantly by the combination of better lubricant oil availability due to the steep slope region 74A and optimized tribological performance due to the gradual slope region 74B.
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
