Abstract:
Devices are provided for regulating the pressure pulses and flow pulses that are emitted in the exhausts of apparatus and equipment such as internal combustion engines, compressors and poppet valves. The pressure pulses are reflected from a reflecting member to their source as expansion waves that create a reduced pressure zone that allows subsequently emitted flow pulses to be more easily emitted, thereby enhancing the operational efficiency of the apparatus and equipment. Flow pulses that contain exhaust products such as the products of combustion from an internal combustion engine are regulated so that the exhaust flow they generate is not unduly restricted within the device and an undesirable back pressure that resists the emission of flow pulses from their source created. In regulating the pressure and flow pulses, the devices attenuate the noise generated by the pressure and flow pulses.

Description:
[0001]     The benefit of provisional application Ser. No. 60/487,404, filed on Jul. 14, 2003, and incorporated herein by reference is claimed for this application. 
     
    
       [0002]     The present invention relates to devices for regulating pressure pulses and flow pulses that are emitted in the exhausts of various apparatus and equipment.  
       BACKGROUND OF THE INVENTION  
       [0003]     Apparatus and equipment such as, for example, internal combustion engines, compressors and poppet valves emit pressure pulses and flow pulses in their exhausts. In certain of the apparatus and equipment, such as the internal combustion engines, products of combustion comprise the flow pulses. The pressure and flow pulses are sources of noise, and the flow pulses can create a back pressure that adversely affects the operational efficiency of the apparatus and equipment.  
         [0004]     The known exhaust systems that are employed with the aforementioned sources of pressure and flow pulses for the purpose of receiving and conveying away from the sources the pressure pulses and exhaust products that are emitted as flow pulses are varied. In many cases the designs of such exhaust systems do not adequately account for the back pressure that can be created by the flow pulses nor do the systems regulate the pressure pulses in a manner to improve the operational efficiency of the sources of the pressure pulses.  
         [0005]     In particular, it is often the case that the known exhaust systems are intended to muffle, or attenuate, the undesirable noise generated by the operation of the sources of pressure and flow pulses. The energy of the pressure pulses is the primary source of such noise. Not only are the pressure pulses audible in and of themselves, in addition, pressure pulses reflect off obstructions and surfaces generating additional frequencies, often sinusoidal in nature, which are perceived as secondary noise. Also, should flow pulses pass over an obstruction, an intensified pressure field is formed on the upstream side of the obstruction and a reduced pressure field is formed on the downstream side of the obstruction. These pressure fields cause the generation of additional secondary noise of a generally sinusoidal nature having differing frequencies. Numerous devices are known to those skilled in the art for attenuating the secondary noise. However, the wave lengths of the secondary noise typically are such that the attenuating devices necessarily contain multiple chambers and passages, particularly where wave cancellation techniques are employed to attenuate the noise, and, as a result, are undesirably large and cumbersome. Such devices, as well as noise muffling devices that employ baffling or expansion techniques, often restrict exhaust flow by not adequately taking into account the flow pulses that are generated and, consequently, an undesirable back pressure is created at the location where the exhaust products are emitted. As a result, the operational efficiency of the source of the flow pulses is negatively affected. Additionally, the known devices do not regulate the pressure pulses in way that improves the operational efficiency of the sources of the pressure pulses.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention regulates the pressure pulses and flow pulses emitted in the exhausts of apparatus and equipment of the types referred to above. Specifically, the pressure and flow pulses are directed to a reflecting member where at least a portion of each of the pressure pulses is reflected. This feature and the arrangement of other components of the device of the invention serve to attenuate the noise generated by the pressure and flow pulses. Also, because the pressure pulses are reflected as expansion waves back to the location where the pressure and flow pulses are emitted, the expansion waves create a reduced pressure zone at that location. As a result, the flow pulses can be more easily emitted from the source, thereby enhancing the operational efficiency of the source. This procedure is referred to herein as “tuning”. The flow pulses are made up of the exhaust products, such as the products of combustion from an internal combustion engine, and generate an exhaust flow which, if not efficiently conveyed away from the source, will create a back pressure that will resist the emission of flow pulses from the source and adversely affect the operational efficiency of the source. The failure to efficiently convey away from the source the exhaust flow results in an increased pressure differential between the internal and external pressures of the regulating device. This pressure differential is referred to herein as “flow loss”.  
         [0007]     According to a first aspect, a device is provided in accordance with the present invention so as to be adapted for connection to a source of pressure and flow pulses and receive and regulate the pressure and flow pulses that are generated by the source. The device has an entry end with an opening therein that is adapted to be placed in fluid communication with one or more outlets in the source from which the pressure pulses and any flow pulses are emitted. The device also has an exit end with an opening therein in fluid communication with the opening in the entry end of the device so as to allow for the discharge from the device of the pressure pulses and flow pulses generated by the source after the pressure pulses and flow pulses generated by the source have passed through the device. Additionally, a reflecting member is located in the device so as to reflect at least a portion of each pressure pulse, whereby the noise generated by the pressure pulses is attenuated. According to another aspect, the reflecting member is adapted to be spaced from at least one of the one or more outlets a distance such that the at least a portion of each of the pressure pulses that is reflected by the reflecting member is reflected as an expansion wave back through the opening in the entry end of the device to the one or more outlets in the source such that the expansion wave arrives at the one or more outlets while at least a portion of a flow pulse is being emitted from the one or more outlets.  
         [0008]     According to further aspects, the devices referred to in the previous paragraph include means defining a first passageway for a first portion of each pressure and flow pulse. The first passageway extends between the opening in the entry end of the devices and a location adjacent the opening in the exit end of the devices. The devices also include means defining at least one second passageway for a second portion of each pressure and flow pulse. The at least one second passageway extends between the opening in the entry end of the devices and a location adjacent the opening in the exit end of the devices. Additionally, the at least one second passageway is longer than the first passageway whereby the first portion of each pressure pulse that enters the first passageway arrives at the opening in the exit end of the device before any fraction of the second portion of that same pressure pulse that enters the second passageway arrives at the opening in the exit end of the device and the first portion of each flow pulse that enters the first passageway arrives at the opening in the exit end of the device before the second portion of that same flow pulse that enters the second passageway arrives at the opening in the exit end of the device. In a specific aspect, the means defining a first passageway comprises a first enclosure and the first passageway has the configuration of a cylinder. Additionally, the means defining at least one second passageway includes a second enclosure that is arranged concentrically around and spaced from the first enclosure to create an annular space between the exterior of the first enclosure and the interior of the second enclosure and means that are located in the annular space between the first and second enclosures for establishing in the annular space at least one second passageway in the form of a helical passageway. Also, the reflecting member may comprise an annulus having an outer circumference and an inner circumference. The annulus is attached along its outer circumference to the second enclosure at the exit end of the device whereby the inner circumference of the annulus comprises the opening in the exit end of the device. Various dimensional relationships may be incorporated into the devices. Specifically, the total cross-sectional area of the at least one second passageway can be approximately three times the cross-sectional area of the first passageway; the total flow area of the at least one second passageway can be approximately equal to the flow area of the first passageway; and the cross-sectional area of the first passageway can be equal to or less than the cross-sectional area of the opening in the exit end of the device. Additionally, the first passageway and the at least one second passageway may terminate and merge short of the annulus. In such a case, the first passageway and the at least one second passageway would, preferably, terminate short of the annulus by a distance at least sufficiently great so as not to impede flow from the at least one second passageway to the opening in the exit of the device.  
         [0009]     Each of the further aspects of the invention described in the previous paragraph may also include as a modification a third enclosure that defines a third passageway that has the configuration of a truncated cone. The third passageway has a truncated end and a base end with the cross-sectional area of the base end of the third passageway being approximately equal to the cross-sectional area of the opening in the entry end of the device. The second enclosure and the third enclosure at the base end of the third passageway are connected to one another so that the base end of the third passageway adjoins the opening in the entry end of the device in a face-to-face relationship. A fourth enclosure defines a fourth passageway that has the configuration of a cylinder. One end of the fourth enclosure is connected to the third enclosure at the truncated end of the fourth passageway so that the fourth passageway and the truncated end of the third passageway adjoin one another in a face-to-face relationship. The other end of the fourth enclosure is adapted to be put into fluid communication with the source whereby the outlets in the source are placed into fluid communication with the opening in the entry end of the device. A fifth enclosure defining a fifth passageway that has the configuration of a truncated cone may also be included. The fifth passageway has a truncated end and a base end. The second enclosure and the fifth enclosure at the base end of the fifth passageway are connected to one another so that the base end of the fifth passageway adjoins the opening in the exit end of the device in a face-to-face relationship. There also may be included a sixth enclosure that defines a sixth passageway that has the configuration of a cylinder. One end of the sixth enclosure is connected to the fifth enclosure at the truncated end of the fifth passageway so that the sixth passageway and the truncated end of the fifth passageway adjoin one another in a face-to-face relationship. Dimensional relationships that may be maintained in the modification of the second aspect of the invention are as follows; the cross-sectional area of the sixth passageway may be the same as or larger than the cross-sectional area of the opening in the exit end of the device.  
         [0010]     According to other aspects, devices as described in the third previous paragraph include means defining a first passageway for a first portion of each pressure and flow pulse. The first passageway extends from the opening in the entry end of the device to the exit end of the device and forms the opening in the exit end of the device. The devices also include means defining at least one second passageway for a second portion of each pressure and flow pulse. The at least one second passageway extends between the opening in the entry end of the device and the reflecting member. In these aspects, the reflecting member closes off entirely the at least one second passageway from the passage of pressure and flow pulses past the reflecting member. In a specific aspect, the means defining a first passageway comprises a first enclosure and the first passageway has the configuration of a cylinder. The means defining the at least one second passageway includes a second enclosure that is arranged concentrically around and is spaced from the first enclosure to create an annular space between the exterior of the first enclosure and the interior of the second enclosure and means that are located in the annular space between the first and second enclosures for establishing at least one second passageway in the form of a helical passageway in the annular space. A third enclosure that defines a third passageway having the configuration of a truncated cone that has a truncated end and a base end may be provided. The cross-sectional area of the base end of the third passageway is approximately equal to the cross-sectional area of the opening in the entry end of the device. The second enclosure and the third enclosure at the base end of the third passageway are connected to one another so that the base end of the third passageway adjoins the opening in the entry end of the device in a face-to-face relationship. A fourth enclosure that defines a fourth passageway that has the configuration of a cylinder also may be provided. One end of the fourth enclosure is connected to the third enclosure at the truncated end of the third passageway so that the fourth passageway and the truncated end of the third passageway adjoin one another in a face-to-face relationship. The other end of the fourth enclosure is adapted to be placed into fluid communication with the source whereby the outlets in the source are placed into fluid communication with the opening in the entry end of the device. Dimensionally, the cross-sectional area of the first passageway may be approximately equal to the cross-sectional area of the fourth passageway.  
         [0011]     According to additional aspects, the devices as described in the fourth previous paragraph include a first enclosure that defines a first passageway that has the configuration of a truncated cone with a base end and a truncated end. The truncated end of the passageway comprises the opening in the entry end of the device. Additionally, the reflecting member of the device comprises an annulus that has an outer circumference and an inner circumference. The annulus is attached along its outer circumference to the enclosure at the base end of the first passageway and the inner circumference of the annulus forms the opening in the exit end of the device. The device may further include a second enclosure defining a second passageway having the configuration of a cylinder with a cross-sectional area approximately equal to the cross-sectional area of the opening in the entry end of the device. The second enclosure is connected to the entry end of the device so that the second passageway provides for fluid communication between the source and the opening in the entry end of the device. There also may be provided in that case a third enclosure defining a third passageway. The third passageway also has the configuration of a cylinder with a cross-sectional area approximately equal to the cross-sectional area of the opening in the exit end of the device. The third enclosure is connected to the inner circumference of the annulus so that the third passageway provides for fluid communication from the opening in the exit end of the device away from the device. In a particular case, the first passageway has a central axis that extends from the center of the opening in the entry end of the device to the center of the opening in the exit end of the device and the annulus is arranged at right angles around the central axis. From a dimensional standpoint, the cross-sectional area of the opening in the entry end of the device may be approximately equal to the cross-sectional area of the opening in the exit of the device and the diameter of the base end of the first passageway may be allow for the full expansion of the pressure pulses. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The foregoing and other features of the present invention will be apparent from the description below with reference to the drawings wherein:  
         [0013]      FIG. 1  is an end view a first embodiment of the invention;  
         [0014]      FIG. 2  is a longitudinal view, partly in section, of the embodiment of the invention shown in  FIG. 1 ;  
         [0015]      FIG. 3  is an end view of a second embodiment of the invention;  
         [0016]      FIG. 4  is a longitudinal view, partly in section, of the embodiment of the invention shown in  FIG. 3 ;  
         [0017]      FIG. 5  is an end view, partly in section, of a third embodiment of the invention;  
         [0018]      FIG. 6  is a longitudinal view, partly in section, of the embodiment of the invention shown in  FIG. 5 ;  
         [0019]      FIG. 7  is an end view of a fourth embodiment of the invention; and  
         [0020]      FIG. 8  is a longitudinal cross-sectional view of the embodiment of the invention shown in  FIG. 7 .  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     Referring first to  FIGS. 1 and 2  of the drawings, there is shown a first embodiment of the invention that comprises a device, indicated generally at  10 , that is adapted to be connected to a source of pressure pulses and flow pulses so as to receive and regulate the pressure and flow pulses generated by the source. The first embodiment of the invention and the other embodiments described below may be used with any apparatus or equipment that is a source of pressure and flow pulses such as, for example, internal combustion engines, compressors and poppet valves. However, for purposes of providing a detailed description of the several embodiments of the invention, reference is made herein to the application of the embodiments of the invention to an internal combustion engine that emits pressure pulses as well as flow pulses that contain the products of combustion, or exhaust products, that are generated in the engine as the engine burns fuel in its several cylinders.  
         [0022]     The device  10  includes a first enclosure  11  that comprises a generally cylindrical shell and a second enclosure  17  that also comprises a generally cylindrical shell that is arranged concentrically around and is spaced from the first enclosure  11  so as to create an annular space  18  between the exterior of the first enclosure  11  and the interior of the second enclosure  17 . An opening  13  in the entry end  14  of the device extends across the entire cross-sectional area that is defined by the internal diameter of the second enclosure  17 . The enclosure  11  defines a first passageway  12  that extends between the opening  13  in the entry end  14  of the device and a location short of but adjacent to the opening  15  in the exit end  16  of the device. The first passageway  12  has the general configuration of a cylinder.  
         [0023]     The entry end  14  of the device is adapted to be placed in fluid communication with one or more outlets of an internal combustion engine, not shown, from which pressure pulses and flow pulses are emitted during the operation of the engine. As will be understood by those having ordinary skill in the art, the engine will have a plurality of combustion cylinders and each will have an outlet. Pressure pulses and flow pulses that contain products of combustion are emitted through these outlets to a common exhaust port. The common exhaust port and the entry end  14  of the device are connected to one another in any suitable fashion, such as by welding, thereby placing the opening  13  in the entry end  14  of the device in fluid communication with the outlets in the engine. The opening  15  in the exit end  16  of the device is in fluid communication with the opening  13  in the entry end  14  of the device and as further explained below allows for the discharge from the device of the pressure pulses and flow pulses generated by the engine after the pressure pulses and flow pulses have passed through the device.  
         [0024]     Means are located in the annular space  18  between the first and second enclosures  11  and  17 , respectively, for establishing in the annular space at least one second passageway in the form of a helical passageway that extends between the opening  13  in the entry end  14  of the device and a location short of the opening  15  in the exit end  16  of the device. In the first embodiment of the invention illustrated in  FIGS. 1 and 2 , the means for establishing at least one second passageway comprises three vanes  19 , each of which is helically wound around the exterior of the cylindrical shell  11  along the entire length of the shell. Adjacent ones of the vanes  19  are spaced apart an equal distance so as to form three substantially identical helical passageways  20  in the annular space  18 , each helical passageway having a length greater than the first passageway. It will be understood by those skilled in the art based on the description herein that less than or more than three vanes can be used and the passageways they form need not be identical. Further, the second or helical passageway can be formed other than by the use of vanes. For example, a pack of conduits helically wound around enclosure  11  can be used to form the second passageways. Further, it is not necessary that the second passageways be helical. It is only required that they be longer than the first passageway  12  by an amount discussed below and that they be in fluid communication with opening  13  and the reflecting member  21 .  
         [0025]     It will be understood from the foregoing description that as each pressure and flow pulse from the engine enters opening  13  a first portion of the pressure and flow pulse will enter the first passageway  12  and a second portion of the same pressure and flow pulse will enter the helical passageways  20 . The first portion of each pressure and flow pulse that enters the passageway  12  will continue through passageway  12  and be discharged from the device through the opening  15  in the exit end  16  of the device. The second portion of each pressure pulse that enters the helical passageways  20  will continue through the passageways  20  until it reaches reflecting member  21 . At that point, most of the second portion of each pressure pulse will be reflected from the reflecting member  21  but a fraction of the second portion of each pressure pulse will pass through gap  24  and exit the device through opening  15 . The second portion of each flow pulse that enters the helical passageways  20  will continue through the passageways past reflecting member  21  through gap  24  and will exit the device through opening  15 .  
         [0026]     The reflecting member  21  located in the device comprises an annulus having an inner circumference  22  and an outer circumference  23 . The annulus is attached along its outer circumference  23  to the second enclosure  17  at the end of the device in the embodiment shown in  FIGS. 1 and 3 , whereby the inner circumference  22  of the annulus comprises the opening  15  in the exit end  16  of the device. The reflecting member  21  serves to reflect at least a portion of each pressure pulse and, thereby,. attenuate the noise generated by the pressure pulses. The portion of the pressure pulses that the reflecting member  21  reflects are reflected as expansion waves back through the helical passageways  20 . Thus, as fuel is combusted in the combustion cylinders of the engine, pressure pulses and flow pulses are generated and emitted from the cylinder outlets and travel through the engine&#39;s exhaust port to the opening  13  in the entry end  14  of the device. A portion of the pressure pulses will pass through the helical passageways  20  and impinge on reflecting member  21  whereupon the pressure pulses will be reflected as expansion waves back through the helical passageways  20  and out opening  13 . Where tuning of the engine is to be optimized, the reflecting member  21  is spaced from at least one of the one or more cylinder outlets in the engine a distance such that at least a portion of each of the pressure pulses that is reflected as an expansion wave back through the opening  13  in the entry end  14  of the device to the one or more outlets in the engine arrives at the one or more outlets while at least a portion of a flow pulse is being emitted from the one or more outlets. This results in the easier emission of the flow pulse, thereby tuning the engine exhaust system and enhancing the engine&#39;s operational efficiency. The precise location of the reflecting member  21  in relation to the cylinder outlets can be determined empirically or through calculations applying formulas that govern the speed of travel of the pressure pulses and the corresponding reflected expansion waves.  
         [0027]     The flow pulses that are emitted from the engine contain the products of combustion, or exhaust products, generated by the combustion of fuel in the cylinders of the engine. These flow pulses develop an exhaust flow that must be conveyed away from the in a minimally restrictive fashion. Otherwise a differential pressure is created between the pressure in the device and the pressure outside the device resulting in a flow loss and a back pressure that is deleterious to efficient engine operation. The present invention effectively regulates and deals with the exhaust flow so as to minimize flow losses as explained in more detail below.  
         [0028]     In order to achieve a collection of performance characteristics that are presently preferred insofar as (a) operational efficiency, or tuning, of the engine (b) attenuation of noise generated by the pressure and flow pulses and (c) control of flow losses are concerned, certain dimensional relationships are maintained among the various components of the first embodiment of the device of the invention. Dimensional relationships that are important in this regard are: the ratio of the internal diameter of the shell  11  to the internal diameter of the shell  17 ; the ratio of the diameter of the opening  15  in the exit end  16  of the device to the diameter of the passageway  12 ; the length of the gap, or the distance  24 , between the terminating points of the first passageway  12  and the helical passageways  20  and the annulus  21 ; the difference between the length of the first passageway  12  and the length of the helical passageways  20 ; and the ratio between the flow area of the first passageway  12  and the total flow area of the helical passageways  20 .  
         [0029]     As presently preferred, the internal diameter of the shell  11  is approximately one-half the internal diameter of the shell  17 . As a result, the total cross-sectional area of the helical passageways  20  is approximately three times the cross-sectional area of the first passageway  12  so that approximately 25% of the energy of a pressure pulse entering the device will travel through first passageway  12  and 75% of the energy of the pressure pulse will travel through the helical passageways  20 . With this relationship and with the reflecting member  21  properly spaced from the outlets in the engine, most of the energy of the pressure pulses will be reflected back to the engine&#39;s cylinder outlets so that effective tuning of the engine can be accomplished. To the extent that tuning does occur, the reflected pressure pulse returns to opening  13  as a weaker pressure pulse. With respect to the ratio of the diameter of the opening  15  of the passageway  12 , the diameter of the opening  15  is equal to or greater than the diameter of the first passageway  12  so that the cross-sectional area of the opening  15  is equal to or greater than the cross-sectional area of the first passageway. As far as the length of gap  24  is concerned, as can best be seen in  FIG. 2 , the helical passageways  20  and the first passageway  12  terminate and merge short of the annulus  21 . The length of the gap or distance  24  between the termination of the helical passageways  20  and the first passageway  12  and the annulus  21  is such that the flow area through the gap is approximately equal to the flow area of the larger of the flow area through the first passageway  12  and the total flow area through the helical passageways  20  and is, thus, sufficiently great so as not to impede the flow of exhaust products from the helical passageways  20  to the opening  15 . With respect to the relationship between the flow area of the first passageway  12  and the total flow area of the helical passageways, the vanes  19  are placed at such an angle in annular space  18  that the flow area of the first passageway  12  and the total flow area of the helical passageways  20  are equal. In other words, even thought the total cross-sectional area of the helical passageways is three times the cross-sectional area of the first passageway  12 , the ability of the flow pulses to pass through the helical passageways is no greater than the ability of the flow pulses to pass through the first passageway  12 . Consequently, 50% of a flow pulse will pass through helical passageways  20  and 50% will pass through first passageway  12 . This is in distinction to the pressure pulses which are of a different character than the flow pulses. These latter three dimensional relationships that have been mentioned minimize flow losses in the device and the creation of back-pressure at the engine.  
         [0030]     With respect to the lengths of the helical passageways  20  and the first passageway  12 , the helical passageways are of a length, compared to the length of the first passageway, such that pressure and flow pulses are not reinforced at the exit end  16  of the device. In other words, a fraction of the 75% component of each pressure pulse reaching annulus  21  will not be reflected but will pass through gap  24  and out opening  15 . By maintaining the length of the first passageway  12  shorter than the lengths of the helical passageways  20 , the fraction of the 75% component of the pressure pulse passing through gap  24  will be discharged through opening  15  at a different time than the 25% component of the pressure pulse that passes directly through passageway  12 . This is also the case with the flow pulses wherein about one-half of each flow pulse will pass through the helical passageways  20  and one-half will pass directly through passageway  12  because the flow areas of the helical passageways and the passageway  12  are approximately the same. Attenuation is thereby enhanced.  
         [0031]     By maintaining the foregoing relationships as described, the tuning effect, flow losses and attenuation are optimized. It will be understood that any one of these operational characteristics can be preferentially optimized at the potential expense of one or both of the other operational characteristics if desired. For example, by decreasing to less than 1 to 1 the ratio of the diameter of the opening  15  to the internal diameter of the first passageway  12 , acoustic attenuation is increased with little effect on tuning but flow losses are increased. In order to produce a collection of operational characteristics that are presently preferred, the dimensional relationships set forth above are preferred.  
         [0032]     From the foregoing description it will be understood that the first enclosure  11  comprises a means defining a first passageway  12  for a first portion of each pressure and flow pulse, the first passageway  12  extending between the opening  13  in the entry end of the device  12  and a location adjacent the opening  15  in the exit end  16  of the device  12 . It will also be understood from the description that the second enclosure  17  arranged concentrically around and spaced from the first enclosure  11  to create an annular space  18  between the exterior of the first enclosure  11  and the interior of the second enclosure  17  together with the means in the form of vanes  19  that are located in the annular space  18  between the first and second enclosures for establishing in the annular space at least one second passageway in the form of a helical passageway comprise means defining at least one second passageway extending between the opening  13  in the entry end  14  of the device and a location adjacent the opening  15  in the exit end  16  of the device. It will also be understood that at least one second passageway is longer than the first passageway, whereby the first portion of each pressure pulse that enters the first passageway arrives at the opening in the exit end of the device before any fraction of the second portion of that same pressure pulse that enters the second passageway arrives at the opening in the exit end of the device and the first portion of each flow pulse that enters the first passageway arrives at the opening in the exit end of the device before the second portion of that same flow pulse that enters the second passageway arrives at the opening in the exit end of the device.  
         [0033]     In the second embodiment of the invention shown in  FIGS. 3 and 4 , the device  10 , as described above, includes, in addition, an inlet end, indicated generally at  30 , and an outlet end, indicated generally at  31 . The inlet end  30  includes a third enclosure  35  that defines a third passageway  32  that has the configuration of a truncated cone with a truncated end  33  and a base end  34 . The cross-sectional area of the base end  34  of the third passageway  32  is approximately equal to the cross-sectional area of the opening  13  in the entry end  14 . The third enclosure  35  at the base end  34  of the third passageway  32  is connected to the second enclosure  17  so that the base end  34  of the third passageway  32  adjoins the opening  13  in the entry end  14  in a face-to-face relationship. The inlet end  30  also includes a fourth enclosure  36  that defines a fourth passageway  37  having the configuration of a cylinder. One end  38  of the fourth enclosure  36  is connected to the third enclosure  35  at the truncated end  33  of the third passageway  32  so that the fourth passageway  37  and the truncated end of the third passageway adjoin one another in a face-to-face relationship. The other end  39  of the fourth enclosure  36  is adapted to be connected to the engine, such as by the use of ring clamps, for example, whereby the outlets in the engine are placed into fluid communication with the opening  13  in the entry end  14  of the device.  
         [0034]     The outlet end  31  of the second embodiment of the invention includes a fifth enclosure  40  that defines a fifth passageway  41  that has the configuration of a truncated cone with a truncated end  42  and a base end  43 . The second enclosure  17  and the fifth enclosure  40  at the base end  43  of the fifth passageway  41  are connected to one another so that the base end  43  of the fifth passageway  41  adjoins the opening  15  in the exit end  16  of the device in a face-to-face relationship. A sixth enclosure  44  defines a sixth passageway  45  having the configuration of a cylinder. One end  46  of the sixth enclosure  44  is connected to the fifth enclosure  40  at the truncated end  42  of the fifth passageway  41  so that the sixth passageway  45  and the truncated end  42  of the fifth passageway  41  adjoin one another in a face-to-face relationship.  
         [0035]     The dimensional relationships described above with respect to the first embodiment of the invention shown in  FIGS. 1 and 2  are also applicable to the second embodiment of the invention shown in  FIGS. 3 and 4 . Other considerations that are relevant because of the incorporation into the device of the inlet end  30  and the outlet end  31  are as follows: The conical passageway  32  allows for the smooth expansion of the exhaust flow generated by the flow pulses, thereby reducing flow losses, and efficiently focuses reflected pressure pulses back to the outlets in the engine. In this connection, a conical passageway having a large included angle at the connecting points of the enclosures  17  and  35  is preferred, although the environment in which the device is installed may not be large enough to allow for such an arrangement. The conical passageways  32  and  41  at the inlet end  30  and the outlet end  31 , respectively, also provide for physically strong joints where they are connected to other components of the device of the invention. By providing an inlet end  30 , full expansion of the flow and pressure pulses are encouraged before the pulses reach the opening  13  in the entry end  14  of the device.  
         [0036]     As will be understood, the inlet end  30  serves, essentially, as an adapter for attaching the device to the engine and can take other forms. For example, the third enclosure  35  having a conical passageway  32  can be replaced with an enclosure that has a cylindrical passageway that is of approximately the same diameter as the diameter of the opening  13 . This type of structure can facilitate the installation of the device of the invention on an internal combustion engine used in certain environments. Additionally, the outlet end  31  can be of a different configuration then as shown in  FIGS. 3 and 4 .  
         [0037]     Referring now to  FIGS. 5 and 6  of the drawings, there is shown a third embodiment of the invention. In this third embodiment, as with the first and second embodiments, there is a first enclosure  51  that defines a first passageway  52  that has the configuration of a cylinder with one end  53  located at the opening  54  in the entry end  59  of the device and the other end forming the opening  50  in the exit end  61  of the device. Also, as with the first and second embodiments, the third embodiment includes a second enclosure  55  arranged concentrically around and spaced from the first enclosure to create an annular space  56  between the exterior of the first enclosure  51  and the interior of the second enclosure  55 . Additionally, means in the form of vanes  57  are located in the annular space  56  for establishing at least one second passageway in the form of a helical passageway in the annular space  56 . In the third embodiment of the invention, as illustrated in  FIGS. 5 and 6 , three substantially identical helical passageways  58  are provided. The helical passageways extend between the opening  54  in the entry end  59  of the device and the reflecting member in the form of the annulus  60 .  
         [0038]     In the third embodiment, shown in  FIGS. 5 and 6 , unlike the first and second embodiments, the reflecting member  60  closes off entirely the second passageways  58  at the exit end  61  of the device from the passage of pressure and flow pulses past the reflecting member. Thus, as can be seen in  FIGS. 5 and 6 , the annulus  60  is attached to the enclosure  55  along its entire outer circumference and to the enclosure  51  along its entire inner circumference. At the same time, the enclosure  51  extends at least to the annulus  60  and, preferably, the enclosure  51  extends beyond the annulus  60  as shown in  FIG. 6 . As a result, the first passageway  52  forms the opening  50  in the exit end  61  of the device through which all the energy and exhaust products generated by the engine pass.  
         [0039]     The third embodiment of the invention also includes an inlet end, indicated generally at  63 . The inlet end  63  is similar to the inlet end  30  of the second embodiment of the invention. In other words, the inlet end  63  includes a third enclosure  64  that defines a third passageway  65  that has the configuration of a truncated cone with a truncated end  66  and a base end  67 . The cross-sectional area of the base end  67  is approximately equal to the cross-sectional area of the opening  54  in the entry end  59  of the device, and the third enclosure  64  at the base end  67  of the third passageway  65  and the second enclosure are connected to one another so that the base end  67  of the third passageway  65  adjoins the opening  54  in the entry end  59  of the device in a face-to-face relationship. A fourth enclosure  68  defines a fourth passageway  69  having the configuration of a cylinder. One end  70  of the fourth enclosure  68  is connected to the third enclosure  64  at the truncated end  66  of the third passageway  65  so that the fourth passageway  69  and the truncated end  66  of the third passageway  65  adjoin one another in a face-to-face relationship. The other end  71  of the fourth enclosure  68  is adapted to be placed into fluid communication with the engine whereby the cylinder outlets in the engine are placed into fluid communication with the opening  54  in the entry end  59  of the device. The cross-sectional areas of the fourth passageway  69  and the first passageway  52 , preferably, are approximately equal so that the exhaust flow is no more than minimally restricted and the creation of and undesirably large back pressure is avoided.  
         [0040]     As illustrated in  FIG. 6 , the enclosure  64  has an extended length compared to the length of the enclosure  35  of the second embodiment of the invention illustrated in  FIG. 4 . As was noted in the discussion above concerning the second embodiment, a longer conical section in the inlet end of the device allows for a smoother and more complete expansion of the pressure pulses before they reach the entry end of the device. Additionally, the longer conical passageway can more efficiently focus to the outlets in the engine, for tuning purposes, the pressure pulses reflected from the reflecting member  60 . However, as has been noted, space limitations may preclude providing a conical passageway of the ideal length.  
         [0041]     It will be understood from the foregoing description that the first enclosure  51  comprises means defining a first passageway  52  for a first portion of each pressure and flow pulse extending from the opening  54  in the entry end  59  of the device to the exit end of the device and forming the opening  50  in the exit end of the device. It will also be understood that the second enclosure  55  arranged concentrically around and spaced from the first enclosure  51  to create an annular space  56  between the exterior of the first enclosure  51  and the interior of the second enclosure  55  together with the means in the form of vanes  57  located in the annular space  56  between the first and second enclosures for establishing in the annular space at least one second passageway in the form of a helical passageway comprise means defining at least one second passageway for a second portion of each pressure pulse, the at least one second passageway extending between the opening in the entry end of the device and the reflecting member  60 .  
         [0042]     A fourth embodiment of the invention is shown in  FIGS. 7 and 8 . In the fourth embodiment, the device includes a first enclosure  80  that defines a first passageway  81  that has the configuration of a truncated cone with a base end  82  and a truncated end  83 . The truncated end  83  of the passageway  81  comprises the opening  81  for the entry end  94  of the device. The reflecting member for the fourth embodiment comprises an annulus  85  that has an outer circumference  86  and an inner circumference  87 . The annulus  85 , along its outer circumference  86 , is attached to the enclosure  80  at the base end  82  of the first passageway  81 , and the inner circumference  87  of the annulus  85  forms the opening  88  in the exit end  59  of the device.  
         [0043]     The fourth embodiment of the invention, as illustrated in  FIGS. 7 and 8 , also includes a second enclosure  89  that defines a second passageway  90  that has the configuration of a cylinder with a cross-sectional area that is preferably equal to the cross-sectional area of the opening  84  in the entry end  94  of the device. The second enclosure  89  is connected at one end to the first enclosure at the truncated end  83  of the first passageway  81  so that the second passageway  90  provides for fluid communication between the engine and the opening  84  in the entry end  94  of the device. A third enclosure  91  defines a third passageway  92  that has the configuration of a cylinder with a cross-sectional area that is preferably equal to the cross-sectional area of the opening  88  in the exit end  95  of the device. The third enclosure  91  is connected to the inner circumference  87  of the annulus  85  so that the third passageway  92  provides for fluid communication from the opening  88  in the exit end  95  of the device away from the device.  
         [0044]     As best seen in  FIG. 8 , the first passageway  81  has a central axis  93  that extends between the center of the opening  84  in the entry end of the device  94  and the center of the opening  88  in the exit end  95  of the device. Although the annulus  85  may be arranged so as to be slightly inclined to the central axis  93 , in the embodiment illustrated in  FIGS. 7 and 8 , the annulus is arranged at right angles around the central axis  93 .  
         [0045]     In a preferred embodiment, the diameter of the base end  82  of the first passageway  81  is large enough to allow for the full expansion of the pressure pulses. Also in a preferred embodiment, the cross-sectional area of the opening  84  in the entry end  94  of the device is equal to the cross-sectional area of the opening  88  in the exit end  95  of the device.  
         [0046]     The foregoing descriptions of the invention are intended to enable a person skilled in the art to practice the invention. It is not intended to detail herein all possible modifications and variations of the invention that will be apparent to those skilled in the art upon reading the description. It is intended, however, that all modifications and variations be included within the scope of the invention as defined in the claims below.