Abstract:
Exhaust routing devices are disclosed that include (a) a body defining an exhaust routing chamber, the body having an intake port configured to provide fluid communication between the exhaust port of a cylinder head and the chamber, and two outlet ports configured to provide fluid communication between the chamber and first and second exhaust pipes; and (b) a gate, mounted within the chamber to pivot between a first position, in which the gate occludes one of the outlet ports, and a second position, in which the gate occludes the other outlet port. Exhaust routing systems and method of using them are also disclosed.

Description:
BACKGROUND 
     Auto enthusiasts have long produced cars known as “hot rods” by modifying the engines of American cars to increase their speed and acceleration. Hot rods used in drag racing generally have open headers, i.e., individual exhaust pipes that run directly from the engine to the atmosphere without a muffler, often referred to as “zoomies.” While this type of exhaust system provides optimal performance, due to the minimization of backpressure, the lack of a muffler generally makes such exhaust systems unacceptably loud for street use. Many hot rod owners would like their vehicles to be “street legal,” i.e., in compliance with noise and emission laws and ordinances, while still having the option of open zoomies for use at the drag strip. 
     SUMMARY 
     The exhaust routers disclosed herein allow a user to easily route exhaust from the exhaust port of each cylinder of an internal combustion engine between a first route (e.g., a header pipe to a muffler system or an exhaust pipe including a standard muffler) and a second route (e.g., an open exhaust pipe such as a zoomie.) A separate exhaust router is provided for each exhaust pipe, allowing routing of the exhaust from each exhaust port, with routing occurring right at the exhaust port in preferred implementations. Positioning the router at the exhaust port, rather than downstream in the zoomie, avoids undesirable turbulence. In some implementations, the user can adjust backpressure and noise to desired levels by routing the exhaust in only selected, individual routers through the zoomies, with exhaust from other cylinders being routed through a muffler system. 
     In one aspect, the invention features an exhaust routing device comprising: (a) a body defining an exhaust routing chamber, the body having an intake port configured to provide fluid communication between the exhaust port of an internal combustion engine and the chamber, and two outlet ports configured to provide fluid communication between the chamber and first and second exhaust pipes; and (b) a gate, mounted within the chamber to pivot between a first position, in which the gate occludes one of the outlet ports, and a second position, in which the gate occludes the other outlet port. 
     Some implementations may include one or more of the following features. The device may also include an overtravel spring assembly that is configured to bias the gate toward the first position. In such implementations, the gate is preferably mounted on a shaft in a keyed engagement with sufficient clearance between keyed surfaces to allow the shaft to continue to rotate after the gate comes to rest in the first position. The combination of the biasing action of the spring and the clearance between the keyed features allows multiple routers mounted on a common shaft to all move into a closed, sealed first position even if one of the gates is misaligned, e.g., due to carbon build-up. The clearance may, for example, be sufficient to allow at least 5 degrees of rotation of the shaft after the gate comes to rest. In some cases the clearance is selected to allow from about 5 to 10 degrees of rotation, e.g., 7 degrees. 
     In some cases, the gate has surfaces that are configured for sealing engagement with a seat portion of the body. For example, the gate may have arcuate and chamfered surfaces configured, e.g., by machining, to sealingly engage corresponding surfaces of the seat portion. 
     As noted above, the gate may be mounted on a shaft in a keyed engagement. For example, the gate may be mounted on a splined shaft, for example a hexagonal shaft, or on a round shaft with a keying feature, e.g., a groove on the shaft that engages a ridge on the gate. 
     In another aspect, the invention features an exhaust routing system that includes a plurality of such exhaust routing devices, one mounted at each exhaust port of an internal combustion engine. 
     In a further aspect, the invention features a method of routing exhaust from an internal combustion engine. The method includes rotating the gates of a plurality of exhaust routing devices between a first position, in which the exhaust takes a first route, and a second position, in which the exhaust takes a second, different route. Each exhaust routing device has the features discussed above and is mounted at an exhaust port of a cylinder of the engine. 
     In some implementations, the first route is through a muffled exhaust pipe, for example a header pipe to a muffler system or an exhaust pipe including a standard muffler, and the second route is through an open exhaust pipe such as a zoomie. All of the exhaust routing devices may be rotated substantially simultaneously, or the devices may be rotated selectively. In some cases, all of the exhaust routing devices on one side of the engine are rotated together by a common shaft that extends through each of the routers. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a simplified diagrammatic view of an engine with an exhaust routing system according to one implementation. 
         FIG. 2  is a perspective view of an exhaust router according to one embodiment. 
         FIGS. 3 and 3A  are perspective and top views, respectively, of the exhaust router shown in  FIG. 2  with the upper portion removed and the gate in a first position. 
         FIGS. 4 and 4A  are perspective and top views, respectively, of the exhaust router shown in  FIG. 2  with the upper portion removed and the gate in a second position. 
         FIG. 5  is a diagrammatic view showing multiple discrete exhaust routing devices mounted at the exhaust ports of the cylinders of an engine. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows an engine  10  having a plurality of cylinders  12 . Each cylinder  12  has an exhaust router  14  mounted at its exhaust port  16 . Each exhaust router device  14  is in fluid communication with the exhaust port and with a zoomie  18  and a header pipe  20  that sends the exhaust to a muffler system, e.g., a collector and common muffler (not shown). 
     The exhaust router  14 , shown in detail in  FIGS. 2-4A , includes a body  21  which defines an intake port  22  that is configured for fluid communication with the exhaust port of the cylinder to which it is mounted, e.g., by bolting. Body  21  also defines a first outlet  24 , the axis of which is disposed generally at a right angle to that of the intake port  22 , and a second outlet port  26 , the axis of which is disposed generally parallel to or collinear with that of the intake port  22 . Each of the outlet ports is connected to an exhaust pipe. In the embodiment shown in  FIG. 1 , the header pipe  20  would be connected to outlet port  24  and the zoomie  18  would be connected to outlet port  26 . 
     A gate  28  is mounted on a shaft  30  to pivot about a pivot axis that is generally perpendicular to the axes of the ports between a first position, shown in  FIGS. 3-3A , in which port  24  is open and port  26  is sealed off, and a second position, shown in  FIGS. 4-4A , in which port  24  is occluded and port  26  is open. Thus, in the embodiment shown in  FIG. 1 , when the gate is in the first position exhaust would be flowing to the header pipe  20  and the zoomie would be sealed off, while when the gate is in the second position exhaust would be routed to the zoomie  18  and the header pipe  20  would be closed. 
     When the gate is in each of its positions, under normal circumstances the occluded port is completely closed off, and in the case of the first position ( FIGS. 3-3A ) the gate seals against the body  21 , as will be discussed below, to prevent any flow of exhaust into the zoomie. This sealing of the zoomie is important in order to prevent the noise that is caused by flow of exhaust into the zoomie. 
     Sealing between the gate and the port is provided by intimate contact between surfaces of the gate and mating seat surfaces of the body  21 . Thus, the gate has an arcuate surface  32  on one side, a corresponding arcuate surface  39  on the other side, a chamfered surface  34  at one end, and a chamfered end surface  41  at the other end. When the gate  28  is in the first position ( FIG. 3A ), the chamfered end surface  34  of the gate sealingly contacts the corresponding chamfered surface  36  of the body, and the chamfered surface  41  contacts a corresponding chamfered surface (not shown) at the edge of portion  47  of the body ( FIG. 3 ). The arcuate surface  39  contacts a seat portion  49  of the body  21 , as best seen in  FIG. 3 . These mating surfaces may be formed in any manner that provides high tolerances for intimate contact, for example by precision machining. 
     A seal is also provided when the gate is in the second position, although this seal is not necessarily fluid-tight, since there is a less stringent requirement to prevent flow of exhaust into the header pipe  20  when the zoomie  18  is in use. In this case, the body defines a groove  29  ( FIGS. 3A and 4A ), which receives the arcuate surface  32  and the edge  31  of gate  28  in sealing engagement when the gate is in the second position ( FIG. 4A ) in which the header pipe  20  is blocked by the gate. 
     The gate  28  is mounted on the shaft  30  in a keyed engagement, such that rotation of the shaft pivots the gate. This keyed engagement may be provided by a splined shaft, e.g., having a hexagonal cross-section as shown or any other desired cross-section. In this case the gate arm  27  has a correspondingly shaped opening (not shown) in which the shaft is positioned. Alternatively, other keyed arrangements may be used, for example a round shaft having a key way, e.g., a longitudinal groove, and a corresponding key structure on the gate, e.g., a longitudinal ridge configured to be received by the groove. Bushings (not shown) are provided on either side of the gate for sealing. An actuator arm  23  ( FIGS. 3A and 4A ) is provided to allow a lever (not shown) to be used to rotate that shaft. 
     The multiple exhaust routers that are mounted on the individual cylinders of an engine can be connected so that all of the gates can be pivoted at once. For example, the routers on one side of the engine can be connected by a common shaft (shaft  30 ) such that all of their gates pivot together when the shaft is rotated. 
     A small clearance is provided between the shaft and the keyed feature(s) of the receiving opening in the gate arm  27  to allow some slack between the rotation of the shaft and the pivoting of the gate. This clearance is configured to allow rotational movement of the shaft to continue after the gate has contacted the seat as shown in  FIG. 3A . This movement is facilitated by an overtravel spring assembly  33  (best seen in  FIG. 4 ), which pulls the gate towards the position shown in  FIG. 3A . The clearance and overtravel spring assembly are provided to allow for misalignment between individual routers that are mounted on a common shaft, e.g., due to carbon build-up on one of the routers that causes the gate of that router to seat before the other gates. If this occurs, the spring assemblies of the other routers will continue to pull those gates toward their seated, sealed positions, and the necessary continued rotation of the shaft will be allowed by the clearance. In some implementations, the clearance is selected to be sufficient to provide at least 5 degrees of rotational movement of the shaft after the gate has seated, for example about 5-10 degrees, e.g., about 7 degrees. 
     The body  21  may include cooling fins  50 , as shown, to dissipate heat which could otherwise build up and transfer to the engine. Also, the body  21  is preferably formed in two halves, as shown, with an end cap  52  that is removable for servicing of the router, e.g., removal of carbon build-up or other contamination. 
     OTHER EMBODIMENTS 
     A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. 
     For example, movement of the gate may be actuated in other ways, for example using an automatic actuator. Moreover, size and or shape of the router and its components may be different from what is shown in the drawings, for example to adapt the router to use in different makes of engines. 
     Accordingly, other embodiments are within the scope of the following claims.