| Exhaust pipe structure -> Monitor Keywords |
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Exhaust pipe structureExhaust pipe structure description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20090159147, Exhaust pipe structure. Brief Patent Description - Full Patent Description - Patent Application Claims
1. Field of the Invention The present invention relates to a structure of an exhaust pipe connected to an internal combustion engine. 2. Description of the Related Art Generally, vibrations generated by the internal combustion engine in operation are transmitted to the exhaust pipe connected to the internal combustion engine. A load caused by these vibrations is thus imposed on the exhaust pipe, which disadvantageously lowers durability and reliability of the exhaust pipe. In addition, the vibrations are transmitted through a support member for the exhaust pipe to a vehicle body, causing undesirable noise and vibrations in the vehicle interior. Therefore, in order to suppress transmission of exhaust pipe vibrations or absorb the vibrations, a widely used exhaust pipe structure has: an exhaust pipe including plural separate exhaust pipes connecting in series to join an exhaust manifold of the internal combustion engine; and a universal joint, such as spherical joint, used for connecting the separate exhaust pipes to allow them to bend flexibly at the joint. An example of this type of exhaust pipe structure is shown in Japanese patent application publication JP-A-2002-160536. The exhaust pipe includes a first exhaust pipe, a second exhaust pipe, and a tail pipe, the first and second exhaust pipes being joined by a spherical joint. The exhaust pipe thus formed inhibits transmission of vibrations from the internal combustion engine to the exhaust pipe. This improves durability and reliability of the exhaust pipe, while suppressing undesirable noise or vibrations in the vehicle interior. The aforementioned exhaust pipe structure is designed such that the exhaust pipe is provided with heavy components, such as a muffler and a catalytic converter, imposing a load on the universal joint connecting the separate exhaust pipes. This can cause the exhaust pipe to be displaced from its normal position in the static state. When the vehicle travels off-road or over an uneven road surface, the exhaust pipe, supported at the position out of the normal mounting position, can be excessively displaced beyond the allowance range. Thus, the exhaust pipe tends to interfere with peripheral components. Preferably, the exhaust pipe is supported at a position adjacent to the universal joint, so that the exhaust pipe is prevented from being displaced from the normal position. Nonetheless, supporting the exhaust pipe in this preferred manner is sometimes difficult mainly due to insufficient body strength at the position adjacent to the universal joint. As described above, which part of the exhaust pipe to be supported and where to locate the universal joint depend on constraints of the vehicle body, such as body structure. This could result in difficulty in supporting the exhaust pipe at its normal position in the static state. The present invention provides an exhaust pipe structure, which ensures that an exhaust pipe is supported at its normal mounting position. A first aspect of the invention is directed to an exhaust pipe structure having: an exhaust pipe that includes plural separate exhaust pipes, connected in series to an internal combustion engine; and a universal joint that connects the separate exhaust pipes to allow these exhaust pipes to bend flexibly at the joints. The exhaust pipe structure is designed such that loads from the weight of the separate exhaust pipes, which act on the universal joint, combine to be almost zero. According to the first aspect, the loads from the weight of the separate exhaust pipes that act on the universal joint, combine to be almost zero. Therefore, the universal joint is prevented from being displaced from its normal position in the static sate, thereby supporting the exhaust pipe at the normal mounting position. This prevents the exhaust pipe from being excessively displaced beyond the allowable range despite vibrations when the vehicle travels off-road or over an uneven road. Consequently, the exhaust pipe is precluded from interfering with peripheral components. This also reduces the displacement of the exhaust pipe, thereby preventing an excessive increase in load on a spring member that applies a restoring force to the bending universal joint. Exhaust gas is thus prevented from leaking due to overload on the spring member. The exhaust pipe is supported at its normal position by controlling the resultant load on the universal joint. This eliminates the necessity to provide an additional support member adjacent to the universal joint, for the exhaust pipe. Hence, the first aspect of the invention gives more flexibility in determining where to locate the support member for the exhaust pipe and the universal joint. This facilitates appropriate positioning of the support member and the universal joint, even if there are some constraints of a vehicle body structure, such as body strength for the location of the support member. The exhaust pipe may include: a first exhaust pipe connected to the internal combustion engine in a fixed manner; a second exhaust pipe connected to the first exhaust pipe via a first flexible universal joint; and a third exhaust pipe connected to the second exhaust pipe via a second flexible universal joint. A first load from weight of the second exhaust pipe and a second load from weight of the third exhaust pipe, which are of approximately the same magnitude, may act on the second universal joint in opposite directions. The exhaust pipe thus constructed includes: the first exhaust pipe connected to the internal combustion engine in a fixed manner; the second exhaust pipe connected to the first exhaust pipe via the first flexible universal joint; and the third exhaust pipe connected to the second exhaust pipe via the second flexible universal joint. The first load from the weight of the second exhaust pipe and the second load from the weight of the third exhaust pipe, which are of approximately the same magnitude, act on the second universal joint in opposite directions. Thus, almost zero-load results on the second universal joint. This prevents the second universal joint from being displaced from its normal position in the static state, thereby supporting the second exhaust pipe and the third exhaust pipe connecting in a displaceable manner at their respective normal mounting positions. The first load from the weight of the second exhaust pipe and the second load from the weight of the third exhaust pipe are cancelled out on the second universal joint. This results in almost zero-load acting on the first universal joint for connecting the first exhaust pipe and the second exhaust pipe. A load is thus prevented from being applied to the first exhaust pipe connected to the internal combustion engine in a fixed manner, thereby minimizing the adverse effects of the load on the internal combustion engine and other components. The second exhaust pipe and the third exhaust pipe may be individually supported by two associated support members. A center of gravity of the second exhaust pipe may be located on the side of the second universal joint with respect to an axis connecting the two associated support members for the second exhaust pipe. A center of gravity of the third exhaust pipe may be located on the side opposite to the second universal joint with respect to an axis connecting the two associated support members for the third exhaust pipe. The second exhaust pipe is supported by the two associated support members, and the center of gravity of the second exhaust pipe is located on the side of the second universal joint with respect to the axis connecting the two associated support members. This results in a load that presses down on the second universal joint. In turn, the third exhaust pipe is supported by the two associated support members, and the center of gravity of the third exhaust pipe is located on the side opposite to the second universal joint with respect to the axis connecting the two associated support members. This results in a load that presses up on the second universal joint. The thus-constructed support members for the second exhaust pipe and the third exhaust pipe help the resultant load, acting on the second universal joint, to be almost zero. The second exhaust pipe and the third exhaust pipe may be individually supported by two associated support members. The center of gravity of the second exhaust pipe may be located on the side opposite to the second universal joint with respect to the axis connecting the two associated support members for the second exhaust pipe. The center of gravity of the third exhaust pipe may be located on the side of the second universal joint with respect to the axis connecting the two associated support members for the third exhaust pipe. The second exhaust pipe is supported by the two associated support members, and the center of gravity of the second exhaust pipe is located on the side opposite to the second universal joint with respect to the axis connecting the two associated support members. This results in a load that presses up on the second universal joint. In turn, the third exhaust pipe is supported by the two associated support members, and the center of gravity of the third exhaust pipe is located on the side of the second universal joint with respect to the axis connecting the two associated support members. This results in a load acting on the second universal joint to press it down. The thus constructed support members for the second exhaust pipe and the third exhaust pipe help the resultant load, acting on the second universal joint, to be almost zero. The third exhaust pipe may be constructed such that one of the two associated support members supports a part of the third exhaust pipe further from the second universal joint, while the other support member supports another part of the third exhaust pipe furthest from a phantom line connecting the one support member and the second universal joint. The third exhaust pipe is supported by the other support member at the part furthest from the phantom line, which connects the one support member and the second universal joint, the one support member supporting the part of the third exhaust pipe further from the second universal joint. This minimizes turning motion of the third exhaust pipe about the phantom line, although the third exhaust pipe tends to vibrate intensively due to its location at a free end on the downstream side of exhaust gas flow. This reduces vibrations of the exhaust pipe when the vehicle travels off-road or over an uneven road surface, while suppressing undesirable noise and vibrations in the vehicle interior. Continue reading about Exhaust pipe structure... Full patent description for Exhaust pipe structure Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Exhaust pipe structure patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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