Land vehicles: wheels and axles – Wheel – With drive or brake attachment
Reexamination Certificate
1999-09-03
2001-10-30
Morano, S. Joseph (Department: 3617)
Land vehicles: wheels and axles
Wheel
With drive or brake attachment
C152S209200, C152S339100, C181S286000, C074S443000
Reexamination Certificate
active
06309026
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method and an arrangement for sound-suppression in wheels in accordance.
A person who is in the passenger compartment in a motor vehicle often experiences that he/she is in a noisy environment. The noise level, however, varies depending on the size and manufacture of the vehicle one is sitting in. It is also obvious that noise increases when the vehicle accelerates. A common inference is therefore that the noise principally comes from the engine. However, it is so that a relatively large amount of the noise inside the passenger compartment originates from road noise. In modern cars a great deal of effort has been applied to minimize the engine noise which penetrates into the passenger compartment and also road noise but there still remains a lot when it is a question of the latter. Minimizing the noise from the road and the wheels is moreover becoming more important as the engine noise decreases because the noise from the road and wheels in this case, relatively seen, forms a larger part of the total noise in the passenger compartment.
The noise which is usually attributed to the wheels of the vehicle comprises partly the external noise which is produced when a wheel meets the road surface and partly the sound which is produced in the air cavity inside the wheel because of a standing wave being excited which is based on the natural frequency (resonance frequency) of the wheel. Thus there occurs what can be described as a resonance tone inside the wheel. The natural frequency of the wheel is determined by the circumference in such a way that the circumference of the internal air cavity is equal to one wave length. The bigger the wheel, i.e. the bigger the circumference, the longer the wave length and therewith the lower the natural frequency. A 15″ wheel has a natural frequency of approximately 230 Hz. The frequency interval which is of interest in this connection is from approximately 250 Hz down to just under 100 Hz, where the latter corresponds to a truck wheel. The external noise which belongs to the meeting of the tire with the road surface depends e.g. on the appearance of the tire, the pattern of the tread and the material of the tire, as well as the road surface. This noise is airborne. The noise which occurs inside the wheel as a result of resonance vibration is to a certain degree airborne but to the greatest part it is a sound body, i.e. the sound propagates via the wheel suspension and further into the passenger compartment of the car.
The object of the present invention is to suppress there so-called natural frequency sounds in wheels which originate in the air cavity inside the wheel.
Devices for suppressing sound inside wheels are known from EP-A-0 663 306 and JP-A-07 052 616. From these documents it is known in the prior art to suppress sound inside wheel cavities by quite simply placing a sound-absorbing material there. The effect of this must be considered to be extremely limited. In EP-A-0 663 306 is mentioned e.g. that the invention is to suppress noise which originates from the natural vibrations in the wheel cavity and, as an example, natural frequencies from 150 to 250 Hz are mentioned. In the last mentioned document it is also shown how resonators can be arranged in connection to the sound absorbers inside the tire. These resonators are, however, intended to absorb sounds other than natural frequency sound, as their design is such that their dimensions limit sound suppression to frequencies of the order of 1000 Hz, which greatly exceed the natural frequency of a vehicle wheel. As mentioned, the natural frequency is determined by the circumference of the wheel. A natural frequency of 1000 Hz would correspond to a wheel with a diameter of approximately 11 cm.
The use of resonators for sound suppression in wheels is in itself also known from EP-B-0 041 127 and EP-A-0 665 529. In the first of these documents the resonator is on a sound shield which is placed on the outside of the wheel. In the second of these documents resonators are placed in the wheel housing. Both these documents therefore show sound suppression of external airborne sound originating from the wheel's contact with the ground. Neither of these documents treat the problem of body-transmitted sound depending on the natural vibrations inside the wheel.
Finally, in order to illustrate the prior art, JP-A-487 803 is mentioned, from which document it is known to half the wave length and thereby double the resonance frequency inside a wheel by producing an intermediate wall inside the wheel. The resulting double frequency is not experienced to be equally noisy as the original frequency. Here, however, it is not a question of sound suppression in a strict sense.
SUMMARY OF THE INVENTION
The problem of suppression of natural frequency is solved according to the present invention by a method and arrangement which includes providing at least one resonator inside the wheel, the resonator being designed for suppression of second resulting from the natural frequency of the wheel.
The advantage of the present invention as it is defined in the independent claims is that a considerably more effective suppression of noise originating from the wheel cavity is obtained than is the case according to the prior art. By using resonators, sound with the frequency which the resonators are tuned to is in principle completely extinguished. Through this sound suppression, the comfort for the driver and the passengers who are in the cabin space of the vehicle is improved. A lower sound level has also the advantage that it leads to improved safety because one quite simply becomes tired from being in a noisy environment.
Consequently, by means of the invention, a sound-suppression device is obtained which is effective and easily can be adapted to different wheel dimensions. The invention has furthermore the advantage that also several frequencies can be suppressed by using several resonators, tuned to different frequencies. In this way, there is the possibility to use the same arrangement for several wheel dimensions without requiring individual adaptation. There is also the possibility of integrating the sound-suppression device in the wheel on or in the tire itself. No loose devices are needed in this case, which signifies a further advantage.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.
REFERENCES:
patent: 1897789 (1933-02-01), Brooke
patent: 2901290 (1959-08-01), Loofbourrow
patent: 3270794 (1966-09-01), Skidmore
patent: 3414036 (1968-12-01), Skidmore
patent: 3866977 (1975-02-01), Rice
patent: 4896921 (1990-01-01), Sato et al.
patent: 5092192 (1992-03-01), Pelzer
patent: 5598479 (1997-01-01), Dodt et al.
patent: 5899253 (1999-05-01), Marron et al.
patent: 5959265 (1999-09-01), Van Ligten
patent: 6009705 (2000-01-01), Arnott et al.
patent: 6074015 (2000-06-01), Renard et al.
patent: 6106075 (2000-08-01), Suenaga
patent: 6167985 (2001-01-01), Van Ligten
patent: 0041127 (1981-12-01), None
patent: 0663306 (1995-07-01), None
patent: 0665529 (1995-08-01), None
Patent Abstracts of Japan 07052616 dated Feb. 28, 1995.
Patent Abstracts of Japan 4-87801 dated Mar. 19, 1992.
Patent Abstracts of Japan 4-87802 dated Mar. 19, 1992.
Patent Abstracts of Japan 4-87803 dated Mar. 19, 1992.
Bellinger Jason R.
Morano S. Joseph
Ostrolenk Faber Gerb & Soffen, LLP
Saab Automobile AB
LandOfFree
Method and arrangement for sound-suppression in wheels does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and arrangement for sound-suppression in wheels, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and arrangement for sound-suppression in wheels will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2583894