Patent Application
20100146954
The present disclosure relates to exhaust components employing valves to regulate exhaust flows. While the following examples and discussion generally relate to exhaust gas heat recovery applications, it should be understood by those skilled in the art that the general concepts discussed herein are also applicable to other “exhaust applications” such as thermal protection of exhaust components, or EGR (exhaust gas recirculation) systems, by way of non-limiting examples.
This section provides background information related to the present disclosure which is not necessarily prior art.
Automobile manufacturers and the entire transportation sector are facing an increasingly stringent set of governmental regulations. For example, mandates for ever lower pollutant emissions levels, as well as ever higher fuel efficiency requirements (now often expressed as ever lower carbon dioxide emissions levels) are constantly tightening. However, automobile systems which have been used successfully in the past are proving to be no longer adequate for automakers in this new environment. Therefore, to meet the new laws, mandates and requirements, automakers must adopt new technologies and systems and/or modify existing technologies and systems.
One of the automotive systems which affects both fuel economy and pollutant emissions levels is the exhaust system. Automotive engineers are discovering new ways for the exhaust system to help meet governmental mandates in these areas. For example, heat from the engine exhaust can be recovered and be used to warm the vehicle's working fluids (e.g. engine, transmission, and transaxle oil) under start-up and cold operating conditions to reduce friction, thus improving efficiency and increasing fuel economy. Improved warm-up of the engine coolant is also desirable for driver and passenger comfort because this can be used to warm up the vehicle cabin more rapidly and defrost the windshield in less time in cold start-up conditions. And because of new engine technologies, certain new exhaust components such as lean NOx traps are included in some exhaust systems to reduce smog generating nitrous oxides. These emissions components often require careful thermal regulation to maintain peak efficiency; otherwise large additions of expensive precious metals would be required to maintain conversion efficiency.
For these reasons and more, automakers are considering the addition of non-standard exhaust system components to their vehicles to achieve their goals. Specifically, controlling the flow and routing of exhaust gases to achieve thermal goals is becoming a new requirement. Heat exchangers and exhaust valves to control the flow of gases in the exhaust system are enablers for new exhaust system designs. Heat exchangers in exhaust systems can also be used, for example, to recover heat which would otherwise be lost through the tailpipe, and used in other forms to boost the overall efficiency of the vehicle systems. An example of this would be the generation of steam from the waste exhaust gas energy, which is then used to generate electricity or converted into motive power for direct vehicle propulsion.
It is often the case that the function of the exhaust gas heat exchanger is not required for the entire time that the engine is running, and therefore may require a shutoff function; likewise, the level of heat exchange may need to be controlled to a certain level below 100% of function. In cases like these, some method of controlling exhaust flow through the heat exchanger may be required. An exhaust valve is a typical technology which is used to achieve this control, as it is usually not practical to control the flow of coolant through the heat exchanger when it forms part of the engine cooling system.
Many modern gasoline engines can achieve exhaust gas temperatures between 950° C. and 1050° C. Most of today's exhaust valve designs reflect the extreme thermal environment in which this component spends its service life. While there are many types of exhaust valves, expensive, temperature-resistant materials are invariably used, and designs can be relatively complex for manufacturing. Additionally, if the exhaust valve conducts high temperatures externally, the valve's actuator may require shielding or the use of more expensive, high temperature materials.
The present disclosure provides a low-cost exhaust valve that is actively cooled by a working fluid, which may be the same fluid that flows through an associated heat exchanger. The valve does not experience the temperatures typically endured by other exhaust valves, therefore allowing for cheaper component materials having less complicated and lighter weight designs.
Exhaust systems may contain features or components which necessitate the regulation of exhaust flow through all or a portion of the exhaust system. The regulation of exhaust flow may include the re-routing of exhaust gases into a secondary path or exhaust channel, which may include a heat exchanger through which engine coolant or other heat transfer fluid passes. The routing of exhaust gas may be controlled in such a way that it is throttled or adjusted to a certain percentage of full flow and it may or may not involve a complete stoppage of flow through the first channel.
According to the present disclosure, an exhaust valve assembly may be used to achieve the regulation of exhaust flows, and this exhaust valve may be located before or after the aforementioned heat exchanger. The valve assembly may include a valve shaft, a valve body, and a diverter. The component that houses the shaft and diverter and through which coolant passes may be referred to as the valve body. According to the present disclosure, the passages in the valve body through which the engine coolant or other cooling fluid pass, either into or out of the heat exchanger, may be routed in close proximity to the valve shaft. This keeps the valve components relatively cool and allows for lower cost construction and more reliable operation of the valve assembly.
According to the present disclosure, the valve may be a butterfly type (proceeding in both directions from the shaft) or the valve may be “bimodal,” that is, a “flap” type, proceeding from only one side of the shaft. The valve may be supported by bearing surfaces on both ends or may be cantilevered, that is, supported on only one end.
Additionally, the valve body may be shaped so as to create separate channels for the control and regulation of the exhaust flow. These channels may be: arranged independently beside each other; arranged with a shared wall to create bifurcated channels; or arranged with one channel inside the other.
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.
a and 3b illustrate section views of the first embodiment of the exhaust valve assembly assembled with a heat exchanger downstream of an emissions component, showing the exhaust gas routing with the valve open (bypass mode) and closed (heat exchange mode);
a and 4b illustrate section views of the second embodiment of the exhaust valve assembly assembled with a heat exchanger upstream of an emissions component, showing the exhaust gas routing with the valve open (bypass mode) and closed (heat exchange mode);
a and 6b are sectional views showing the operation of the third exhaust valve embodiment.
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, and devices, 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.
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.
Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
Rotation of the valve shaft 1 is accomplished by the attachment of an actuator (not shown) to the end of the valve shaft in location 13. The valve plate 2 and diverter ring 3 may be manufactured from relatively thin (approximately 2-3 millimeters) heat resistant material. The material may depend on the application temperature. For example, austenitic stainless steel may be used for high temperature gasoline engines. The valve plate 2 may be cut or stamped from flat sheet and may or may not be round. The diverter 4 may be welded, brazed, pressed onto, or otherwise attached to the valve shaft 1. The valve shaft 1 may be formed from a high temperature stainless steel. Corresponding recesses in the valve plate 2, diverter ring 3, and valve shaft 1 allow the components to be reliably located and mated together.
The valve body 10 shown in
The valve body assembly 20 is assembled with the associated heat exchanger and/or emissions components, using the edge 16 of the outer wall 8 and the edge 22 of the inner wall 7. Additionally, components may be attached in the central flow path by means of a series of small stand-offs 9. The valve assembly 20 attaches to the overall exhaust system by means of a welded or bolt-together flange 17.
Referring now to
a and 3b illustrate how the exhaust valve assembly 20, 30 can be integrated into an exhaust system sub-assembly. In this figure, the exhaust valve assembly 20 is located downstream of a standard three way automotive catalyst 50. In the heat exchanger bypass mode of
The heat exchanger 51 may include an inner flow path 52 and an outer flow path 53, which are separated by a dividing wall 55. A heat exchange element 56 is placed in the outer flow path 53 and may be surrounded by a coolant jacket 57. The inner flow path 52 may be left as an empty space to allow for variations in manufacturing and assembly, such as the variable diameter of a catalyst can 58 due to the need to calibrate the catalyst can 58 to account for variations in a catalyst substrate 59 and mat 60. In some embodiments, the flow path 52 may contain a heat exchange element to facilitate a desired thermal performance.
a shows an alternative embodiment for a valve body 70 shown in a position upstream of an emissions component 74 and/or heat exchanger 75. An inner valve body wall 71 and an outer valve body wall 72 may be shaped to aid in directing the exhaust gases through a central flow path 73 in a heat exchanger bypass mode (
An alternative valve body 80 and valve plate 81 arrangement is shown in
a and 6b illustrate how the valve body 80 can be used in a larger assembly. When the valve plate 81 is in the heat exchanger bypass mode of
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 invention. 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 invention, and all such modifications are intended to be included within the scope of the invention.
This application claims the benefit of U.S. Provisional Application No. 61/121,936, filed on Dec. 12, 2008. The entire disclosure of the above application is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61121936 | Dec 2008 | US |
