Power plants – Internal combustion engine with treatment or handling of... – Pulsed – timed – tuned or resonating exhaust
Reexamination Certificate
1999-01-27
2001-01-30
Denion, Thomas (Department: 3748)
Power plants
Internal combustion engine with treatment or handling of...
Pulsed, timed, tuned or resonating exhaust
C060S324000, C181S241000, C181S253000, C181S254000
Reexamination Certificate
active
06178745
ABSTRACT:
The invention relates to an exhaust assembly of the type described in the preamble of the main claim. Such assembly is known from U.S. Pat. No. 4,901,528.
The known assembly comprises a first exhaust manifold and a second exhaust manifold, joined at a predetermined portion and having different fluid flow paths in length down to said predetermined portion, a silencer being connected to said first and second exhaust manifolds at said portion. The silencer includes selector valve means for altering the exhaust resistance thereof. Furthermore means are provided for detecting engine revolution speed and engine load, which can each send a signal to control means responsive to said signals for normally closing said selector valve, but opening said valve when the engine revolution speed and load exceeds a first predetermined level. A controller is provided for automatically opening said valve for reducing the noise and resonance created by the motor.
This known exhaust assembly has the disadvantage that the noise characteristics of the exhaust assembly will be automatically regulated. The driver of the motor vehicle cannot influence the characteristics of the sound made by the vehicle at will. Thus with such known exhaust assembly it will not be possible to for example set the sound characteristics based on legal noise standards or personal preferences.
A further exhaust assembly is known from practice and is supplied in the Netherlands by the firm Dreyson of Uden.
This known assembly comprises an exhaust connectable to an engine of, in particular, a motorbike, which exhaust consists of a pipe having a muffler included therein. Adjacent the end of the exhaust which, during use, is remote from the engine, a series of disks is included. During use of the engine, the exhaust gases are guided along the disks, creating a particular damping characteristic, depending on the number of disks arranged one behind the other. In order to adjust the damping characteristic, disks can be added or removed, both of which influence in particular the noise produced during use and the back pressure of the exhaust. In order to change the number of disks in this exhaust assembly, a series of fastening screws should be unscrewed, after which disks can be removed or added. Then, the fastening screws should be placed back again, possibly after replacement by screws of a different length. Next, the engine can be started again for checking the change of the damping characteristic, after which, if necessary, the number of disks should be adjusted once again. In this manner, the suitable number of disks can iteratively be determined. A major drawback of this assembly is that each time when the damping characteristic is to be adjusted, the engine should be switched off and the above series of operations should be performed, usually a number of times in succession, while, moreover, replacement parts and tools are necessary. As a consequence, the means for adjusting the damping characteristic are unsuitable for quickly and readily adjusting the damping characteristic. In particular, this cannot be performed with a switched-on engine, as the pressure and temperature of the combustion gases are so high that handling the exhaust assembly, in particular the inside thereof, is not possible without the danger of burning oneself.
The object of the invention is to provide an assembly of the type described in the preamble of the main claim, in which the drawbacks mentioned are avoided and the advantages thereof are retained. To that end, an exhaust assembly according to the invention is characterized by the features of the characterizing part of claim
1
.
An exhaust assembly according to the invention comprises at least a first and a second combustion gas flow route. During use, when two different combustion gas flow routes are present, the combustion gases are selectively guided via the first, partly via the first and partly via the second, or, possibly, entirely via the second combustion gas flow route. By operating the control means, the ratio between the amount of combustion gases flowing via each of the combustion gas flow routes can be set, during use. If for instance 100% of the combustion gases is guided via the first combustion gas flow route, the damping characteristic of the exhaust assembly is determined by the damping characteristic of the first combustion gas flow route. However, if a portion of the combustion gases is guided along the second combustion gas flow route, a damping characteristic is created which is a combination of the damping characteristics of the two combustion gas flow routes. In this manner, the exhaust noise can for instance be controlled by operating the control means.
As the combustion gas flow routes in the exhaust assembly are defined and can be switched on selectively without requiring disassembly and assembly operations and the like, the noise produced by a vehicle in which the exhaust assembly is used can, during use, in each case be adjusted as desired or as necessary, in respect of pitch and key as well as volume. This is in particular very advantageous if the vehicle is for instance used in areas where different or changing noise standards prevail for the allowed noise production by a vehicle, such as a border region where the border is passed. Further, an exhaust assembly according to the invention offers the advantage that if different users of a vehicle have different noise preferences or if users have different noise preferences at different moments and in different situations, the noise can readily be adjusted during use. Moreover, with an exhaust assembly according to the invention, adjustment of the back pressure provided by the exhaust assembly can be effected in a simple manner and during use. All this can be realized while retaining the possibility of getting back without any difficulty the noise that is considered authentic, if so desired.
In an advantageous embodiment, an exhaust assembly according to the invention is characterized by the features of claim
2
.
In such assembly, different exhausts can be used that can selectively be actuated, for processing the complete flow of combustion gases or a portion thereof. This for instance involves the first combustion gas flow route comprising a first exhaust and the second combustion as flow route comprising another exhaust. One of the exhausts may for instance be the officially allowed standard exhaust and the other exhaust a custom exhaust.
In a further advantageous elaboration, an assembly according to the invention is characterized by the features of claims
3
and
4
.
The valve means provide the advantage that in a simple manner, a suitable choice between the exhausts present can in each case be made. By means of the valve means, the complete flow of combustion gases can be guided through one of the exhausts or be distributed over a series of exhausts. By providing the manifold with passages having different flow resistances, the advantage is achieved that the valve means need only be arranged in the passage having the lowest flow resistance. After all, if both passages are released, the combustion gases will in each case at least substantially choose the passage having the lowest resistance. Only when that passage is closed will the combustion gases be guided via the second or further passage. As a result, constructionally simple, robust and readily operable valve means can be used that are little susceptible to, for instance, deposit formation and damage.
In an alternative embodiment, an exhaust assembly according to the invention is characterized by the features of claim
6
.
During use, the covering means release a portion of a muffler for being flown through by the combustion gases. Upon the release of a larger portion of the muffler, at least a greater damping, less noise and a change of the back pressure will be created. Accordingly, a variation in the damping characteristic of the exhaust assembly can already be obtained with one exhaust, which variation can be controlled during use.
In a further embodiment,
Denion Thomas
Michaelson Peter L.
Michaelson & Wallace
Nguyen Tu M.
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