Patent Application
20180363532
This invention relates to exhaust systems, and more particularly to an exhaust gas aspirator that cools exhaust gas prior to exiting the exhaust system.
Environmental regulations are becoming increasingly strict with regard to engine exhaust emissions such as nitrogen oxides (NOx) and particulate matter, More stringent environmental regulations with regard to diesel engine particulate emissions has warranted the need for diesel particulate filters and/or other exhaust aftertreatment devices, such as NOx adsorbers, to be placed in the exhaust gas stream for removing or reducing harmful exhaust emissions before the exhaust is permitted to enter the atmosphere.
Typically, exhaust aftertreatment systems must initiate and control regeneration of the particulate filters, NOx adsorbers, and other exhaust treatment devices from time to time as the devices fill up with soot, NOx, or the like. Regenerating the devices removes some or all of the particulates built up on the devices by oxidizing the particles. As an example, regeneration of a particulate filter is done by increasing the temperature of the filter to a level where the soot is oxidized, e.g., above 400° C., and maintaining that temperature for a desired period of time, e.g., several minutes or longer, depending on circumstances including the size of the filter, the amount of soot on the filter, the uniformity level of the soot, etc.
The temperature of the filter is increased by increasing the temperature of the exhaust gas passing through the filter by any of various techniques known in the art. Although increasing the exhaust gas temperatures can effectuate the positive and desirable result of regenerating an exhaust aftertreatment device, exhaust gas temperatures during such regenerating events can reach extreme levels, e.g., 650° C. or more, possibly causing undesirable side effects. For example, the high exhaust temperatures required for filter regenerations usually means the exhaust leaving the tailpipe of the vehicle is much hotter than it would be during normal operation, particularly at stationary or low-speed operation. This creates a potential safety hazard with regard to the heat flux of the gases leaving the tailpipe and creating discomfort or injury to humans, animals, or plants in proximity. Moreover, extreme exhaust gas temperatures resulting from regeneration events can increase the surface temperature of exhaust train components, increase the risk of fire hazards, and cause damage to street surfaces and other objects. Additionally, extreme exhaust gas temperatures can discolor, e.g., blacken, tailpipe components, especially tailpipes with chromed outer surfaces.
Several approaches have been employed for mitigating heat from an exhaust gas stream to reduce the temperature of the exhaust as it exits the tailpipe. For example, some fire trucks are equipped with a water spray device at the exhaust outlet for exhaust cooling, but such a scheme is limited to a situation where there is a ready water supply as well as experienced firefighters. Other approaches include exhaust diffusion devices coupled to the outlet of the tailpipe. The diffusion devices are configured to cool the exhaust gas leaving the tailpipe by diluting and dispersing the exhaust gas. However, such diffusion devices are not designed to cool the exhaust gas at the tailpipe outlet, but rather to reduce the temperature of the exhaust gas at a regulated distance, e.g., six inches, away from the outlet of the tailpipe to a temperature below a regulated maximum temperature. Although some conventional diffusion devices are successful at achieving a desirable mitigation of exhaust gas heat outside of the tailpipe, e.g., at a distance away from the tailpipe outlet, such devices do not achieve cooler exhaust gas temperatures at the tailpipe outlet. Accordingly, the temperature of exhaust at the tailpipe outlet is still extremely high, which can be dangerous to people and objects near the tailpipe and cause bluing or blackening of the tailpipe itself.
To achieve cooler exhaust gas temperatures at the tailpipe outlet before, during, or after regeneration events, exhaust aspirators positioned upstream of the tailpipe outlet have been developed to entrain ambient air into the exhaust gas stream before the exhaust gas exits the tailpipe. Ambient air is entrained into the exhaust gas stream by creating an exhaust pressure drop within the aspirator that causes a vacuum effect to suck in the ambient air. The pressure drop is created by accelerating the exhaust gas through a nozzle and allowing the exhaust gas to expand upon exiting the nozzle. Typically, the pressure drop must be below a certain threshold (e.g., below 1 inch Hg) to prevent harmful levels of engine backpressure. The ambient air is mixed with the exhaust gas stream and, being cooler than the exhaust gas, reduces the temperature of the exhaust gas before it exits the tailpipe. Accordingly, the temperature of the exhaust gas is cooled within the tailpipe.
Conventional exhaust aspirators suffer from several drawbacks however. Generally, the less the ambient air and exhaust gas is mixed within the aspirator or tailpipe, the higher the radial temperature gradient, and the lower the exhaust gas temperature uniformity at the tailpipe outlet. Typically, inadequate mixing results in some portions of exhaust gas being at a generally uniform lower exhaust gas temperature at the tailpipe outlet and some concentrated pockets of exhaust gas remaining at extremely high temperatures. The concentrated pockets can be harmful and cause bluing of the tailpipe. Conventional exhaust aspirators, such as those with a single nozzle, may not adequately mix the entrained ambient air with the exhaust gas to achieve a suitable radial temperature gradient for a given exhaust pressure drop threshold. To achieve better mixing and exhaust uniformity at the aspirator outlet, some conventional exhaust aspirators are lengthened. However, longer aspirators can be more expensive to manufacture due to additional material and can occupy more valuable space within the exhaust system that could be used for other components.
Accordingly, an exhaust aspirator is desired that more adequately mixes entrained air with exhaust gas within a tailpipe to achieve a lower exhaust gas radial temperature gradient and greater exhaust gas uniformity at the tailpipe outlet.
The present disclosure provides an exhaust gas system which reduces the risk of injury from hot exhaust gases from a vehicle by achieving a lower exhaust gas radial temperature gradient and greater exhaust gas uniformity at the tailpipe outlet (or exhaust end of the secondary exhaust pipe). The exhaust gas system includes a catalytic converter having an inlet and an outlet, a primary exhaust pipe, an exhaust nozzle and a secondary exhaust pipe. The primary exhaust pipe includes a proximate end and a distal end. The primary exhaust pipe may be affixed to the outlet of the catalytic converter at the proximate end of the primary exhaust pipe. The secondary exhaust pipe or tailpipe may be coupled to the distal end of the primary exhaust pipe via the exhaust nozzle. The exhaust nozzle includes a body region which is integral to a frustoconical defined region. The body region of the exhaust nozzle may be engaged to the distal end of the primary exhaust pipe. The frustoconical defined region of the exhaust nozzle may be engaged to the secondary exhaust pipe.
It is understood that the secondary exhaust pipe or tailpipe may include a nozzle end and an exhaust end. The secondary exhaust pipe also defines plurality of apertures proximate to the nozzle end of the exhaust pipe wherein these apertures are configured to allow ambient air to mix in with the hot exhaust gas which is flowing through the exhaust nozzle. Moreover, the plurality of apertures in the secondary exhaust pipe and the frustoconical defined region of the exhaust nozzle may be configured to work together to disperse a hot exhaust gas flow from the catalytic converter into a coder ambient air flow from the plurality of apertures defined in the secondary exhaust pipe or tailpipe.
With respect to the exhaust nozzle, the frustoconical defined region includes a first end diameter and a second end diameter which is less than the first end diameter. Moreover, the body region of the exhaust nozzle includes a primary diameter which is approximately equal to the first end diameter of the frustoconical defined region. As shown in the present disclosure, the exhaust nozzle is a hollow member, and the frustoconical defined region is operatively configured to disrupt the hot exhaust flow from the catalytic converter before the hot exhaust gas flow contacts the ambient air flow which enters the exhaust system through the plurality of apertures. It is also understood that the frustoconical defined region is operatively configured to also disrupt the hot exhaust flow from the catalytic converter when (and while) the hot exhaust gas flow contacts the ambient air flow.
The frustoconical defined region may, but not necessarily, be substantially formed by a curvy surface. The frustoconical defined region may also include at least two outer recesses which are formed in the curvy surface. The two or more outer recesses may, but not necessarily, also be offset from one another. It is also understood that one outer recess may also be implemented in the frustoconical defined region.
It is also understood that, alternative to the aforementioned curvy surface with outer recesses, the frustoconical defined region may include a plurality of notches at a second end of the frustoconical defined region. It is understood that each notch in the plurality of notches may, but not necessarily, be a splayed notch where the opposite sides of each notch are not parallel to each other.
The present disclosure and its particular features and advantages will become more apparent from the following detailed description considered with reference to the accompanying drawings.
These and other features and advantages of the present disclosure will be apparent from the following detailed description, best mode, claims, and accompanying drawings in which:
Like reference numerals refer to like parts throughout the description of several views of the drawings.
Reference will now be made in detail to presently preferred compositions, embodiments and methods of the present disclosure, which constitute the best modes of practicing the present disclosure presently known to the inventors. The figures are not necessarily to scale. However, it is to be understood that the disclosed embodiments are merely exemplary of the present disclosure that may be embodied in various and alternative forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for any aspect of the present disclosure and/or as a representative basis for teaching one skilled in the art to variously employ the present disclosure.
Except in the examples, or where otherwise expressly indicated, all numerical quantities in this description indicating amounts of material or conditions of reaction and/or use are to be understood as modified by the word “about” in describing the broadest scope of the present disclosure. Practice within the numerical limits stated is generally preferred. Also, unless expressly stated to the contrary: percent, “parts of,” and ratio values are by weight; the description of a group or class of materials as suitable or preferred for a given purpose in connection with the present disclosure implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred; the first definition of an acronym or other abbreviation applies to all subsequent uses herein of the same abbreviation and applies mutatis mutandis to normal grammatical variations of the initially defined abbreviation; and, unless expressly stated to the contrary, measurement of a property is determined by the same technique as previously or later referenced for the same property.
It is also to be understood that this present disclosure is not limited to the specific embodiments and methods described below, as specific components and/or conditions may, of course, vary. Furthermore, the terminology used herein is used only for the purpose of describing particular embodiments of the present disclosure and is not intended to be limiting in any way.
It must also be noted that, as used in the specification and the appended claims, the singular form “a,” “an,” and “the” comprise plural referents unless the context clearly indicates otherwise. For example, reference to a component in the singular is intended to comprise a plurality of components.
The term “comprising” is synonymous with “including,” “having,” “containing,” or “characterized by.” These terms are inclusive and open-ended and do not exclude additional, un-recited elements or method steps.
The phrase “consisting of” excludes any element, step, or ingredient not specified in the claim. When this phrase appears in a clause of the body 14 of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole.
The phrase “consisting essentially of” limits the scope of a claim to the specified materials or steps, plus those that do not materially affect the basic and novel characteristic(s) of the claimed subject matter.
The terms “comprising”, “consisting of,” and “consisting essentially of” can be alternatively used. Where one of these three terms is used, the presently disclosed and claimed subject matter can include the use of either of the other two terms.
Throughout this application, where publications are referenced, the disclosures of these publications in their entireties are hereby incorporated by reference into this application to more fully describe the state of the art to which this present disclosure pertains.
The following detailed description is merely exemplary in nature and is not intended to limit the present disclosure or the application and uses of the present disclosure. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description.
As shown in
It is understood that the secondary exhaust pipe 22 (or tailpipe 22) may include a nozzle end 40 and an exhaust end 42. As shown in
With respect to the exhaust nozzle 20 shown in
In one embodiment, the frustoconical defined region 32 may, but not necessarily, be substantially formed by a curvy surface 46. As shown in
As shown in
With respect to the temperature distribution plots of
While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the disclosure as set forth in the appended claims and the legal equivalents thereof.
