Abstract:
A valve assembly may include a valve body, a valve member, and a valve shaft. The valve body may include an inlet, an outlet, and first and second fluid paths in fluid communication with the inlet. The first fluid path may extend axially through at least a portion of the valve body. The second fluid path may be defined by first and second annular walls and may at least partially surround the first fluid path. The valve member is disposed in the valve body and may be movable between a first position preventing fluid flow through the first fluid path and a second position allowing fluid flow through the first fluid path. The valve shaft may be fixed to the valve member and mounted to the valve body for rotation relative to the valve body.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     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. 
    
    
     FIELD 
     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. 
     BACKGROUND 
     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&#39;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&#39;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&#39;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. 
     SUMMARY 
     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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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. 
         FIG. 1  is a break-away cross section view of an exhaust valve assembly in accordance with the teachings of the present disclosure; 
         FIG. 2  is a break-away cross section view of a second embodiment of the diverter and valve body; 
         FIGS. 3   a  and  3   b  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); 
         FIGS. 4   a  and  4   b  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); 
         FIG. 5  is a section view in perspective of a third embodiment of an exhaust valve assembly; and 
         FIGS. 6   a  and  6   b  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. 
     DETAILED DESCRIPTION 
     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&#39;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. 
       FIG. 1  shows an exhaust valve assembly  20  that may include a valve body  10  housing a valve shaft  1  and a diverter  4 . In this embodiment, the diverter  4  is an assembly of a butterfly-type diverter plate  2 , and a ring shaped diverter  3 . The valve body  10  is preferably, but not necessarily, manufactured by a casting process using a temperature-resistant material such as stainless steel. The valve body  10  has an outer wall  8  and an inner wall  7  that create two separate flow paths. A primary axial flow path  5  is centrally located within the valve body  10 . A second flow path  6  is disposed in an annular fashion around the axial flow path  5 . The exhaust valve assembly  20  allows for the selective regulation of exhaust gases through the primary and secondary flow paths  5 ,  6  by altering the position of the diverter  4  by controlling the angular position of the valve shaft  1 . 
     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  FIG. 1  contains a coolant passage  11  which may be connected with the engine/vehicle cooling system. The coolant passage  11  is located in close proximity to the valve shaft  1 , to keep the bearing surfaces of the valve shaft  1  and the valve body  10  within a relatively small temperature range. By isolating the bearing surfaces of the valve shaft  1  and valve body  10  from the large temperature excursions that would be otherwise encountered in a valve without cooling, the durability of these components is greatly enhanced and lower cost materials can be used. The cooling effect also helps to prevent spalling at the mating surfaces between the valve shaft  1  and the valve body  10 . Contact between the main sealing surfaces of the valve shaft  1  and the valve body  10  may be maintained by a spring  18  which is held in place by a retainer  19 . Additionally, an o-ring  21  on the valve shaft  1  prevents leakage of gases outside of the exhaust valve assembly  20 . A coolant connection may be made with the heat exchanger through a coolant tube (not shown) between the valve body coolant outlet nipple  14  and the heat exchanger coolant inlet nipple  12 . Similarly, coolant connections with the exterior coolant system are accomplished by hose connections at the valve body coolant inlet nipple  15  and the heat exchanger coolant outlet nipple (not shown). The coolant nipples  14  and  15  are generally brazed or welded into the valve body  10 . 
     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  FIG. 2 , another embodiment of an exhaust valve assembly  30  is provided and may be similar to the exhaust valve assembly  20  described above with two major exceptions. The first is that the diverter is comprised of only the valve plate  32 . The second major difference is that the valve body  31  contains two coolant passages  33  and  34  for coolant travelling to the heat exchanger ( 33   a ) and returning from the heat exchanger ( 34   a ). The coolant passages  33  and  34  are located in close proximity to the valve shaft  35 , and may be located to keep the bearing surfaces of the valve shaft  35  and the valve body  31  at a relatively low temperature. Coolant connections with the heat exchanger are made by sliding the heat exchanger coolant tubes  36  and  37  into the coolant passages  33  and  34  and sealing them with an o-ring  38 . Similarly, coolant connections with the exterior coolant system are accomplished by hose connections  39  that are usually brazed or welded into the valve body  31 . 
       FIGS. 3   a  and  3   b  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  FIG. 3   a , the diverter  4  is in a first position that allows the exhaust gases to pass through the central flow path  5 , along the valve plate  2 . In this position the diverter ring  3  blocks off the secondary flow passage  6 . When maximum heat extraction is desired, the diverter  4  is rotated 90 degrees into a second position ( FIG. 3   b ) so that the valve plate  2  forces the exhaust gas to be routed in an annular manner through a heat exchanger  51  and finally out the secondary flow path  6  of the valve body  10 . For intermediate levels of heat extraction, the diverter  4  may be positioned in an intermediate position between the first and second positions to regulate partial flow to each of the flow passages. 
     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. 
       FIG. 4   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 ( FIG. 4   a ). Similarly, in the full heat exchange mode of  FIG. 4   b , the inner wall  71  is shaped to aid the dispersion of the exhaust gases to achieve good flow uniformity for gases entering the emissions component  74  such as a catalytic converter. 
     An alternative valve body  80  and valve plate  81  arrangement is shown in  FIG. 5 . In this embodiment, the valve plate  81  is an unbalanced design that selectively closes off one of two flow paths and can be positioned in an intermediate position that will regulate partial flow to each of the flow paths. A coolant passage  82  connects to a water jacket  83  that surrounds and cools the valve shaft  84 . 
       FIGS. 6   a  and  6   b  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  FIG. 6   a , the exhaust gas is directed through the primary flow path  92  to the emissions component  93  (e.g. catalytic converter substrate). When the emissions component needs thermal protection or thermal energy is desired to be extracted for other purposes, the valve plate  81  changes positions to allow some or all of the exhaust gases to pass through the secondary flow path  94  and into the heat exchanger  95 , as shown in  FIG. 6   b , to cool the exhaust gases prior to entering the emissions component  93 . 
     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.