Brakes – Inertia of damping mass dissipates motion – Resiliently supported damping mass
Reexamination Certificate
2002-03-28
2004-11-16
Williams, Thomas (Department: 3683)
Brakes
Inertia of damping mass dissipates motion
Resiliently supported damping mass
Reexamination Certificate
active
06817456
ABSTRACT:
INCORPORATED BY REFERENCE
The disclosures of Japanese Patent Application Nos. 2001-100769 and 2001-102301 both filed on Mar. 30, 2001 each including the specification, drawings and abstract, are incorporated herein by reference in their entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dynamic damper for use in a steering system of an automotive vehicle, which is adapted to be fixed to a steering column or a steering wheel for the purpose of absorbing vibrations excited in the steering wheel.
2. Description of the Related Art
A steering wheel of an automotive vehicle is a member for allowing an operator of the vehicle to steer the vehicle. The operator of the vehicle almost always handles directly the steering wheel during driving the vehicle, and eventually is able to sensitively feel minute vibrations excited in the steering wheel. Since the vibrations excited in the steering wheel greatly impact on a riding comfort of the vehicle as felt by the operator, there has been a great regard for absorbing the vibrations excited in the steering wheel.
In an attempt to damp or attenuate vibrations excited in the steering wheel, a dynamic damper has been mounted on the steering wheel or other members of the steering system, thereby providing a secondary vibration system for the steering system as a primary vibration system. A natural frequency of the secondary vibration system is tuned to a natural frequency of the steering system, so that the vibrations excited in the steering wheel may be damped.
An extensive study of the dynamic damper for use in the steering system conducted by the present inventors has revealed the fact that the adoption of the conventional dynamic damper does not always effectively prevent the vibrations of the steering wheel, especially in recent automotive vehicles.
SUMMARY OF THE INVENTION
It is therefore one object of this invention to provide a dynamic damper for use in a steering system, which is novel in construction and which is capable of exhibiting an excellent vibration damping effect with respect to vibrations excited in a steering wheel of the steering system in an effective and stable manner.
In order to achieve this object of the invention, the present inventors has conducted eager studies of steering systems adopted in recent automotive vehicles, and has revealed that a natural frequency of the steering system has been shifted to a high frequency band as a result of a recent tendency for steeling wheels to be made of light metals including aluminum alloy and a magnesium alloy rather than conventionally employed ferrous metals, for the purpose of improving a steeling feeling.
Further intensive studies of the steering systems carried by the present inventors has also revealed that a frequency band of idling vibrations acting on the steering wheel has been shifted to a low frequency band as a result of a recent tendency for decreasing an engine speed of an internal combustion engine during its idling state for the purpose of improving fuel economy.
Also, the present inventors has studied about automotive vehicles equipped with the conventional steeling wheel whose reinforcing member is made of ferrous metal, and has revealed that the steeling system equipped with the conventional steeling wheel generally has a natural frequency at around 20-30 Hz, which is approximately identical with the frequency band of the idling vibration excited in the general conventional automotive vehicle.
With the above-described revealed facts taken into synthetic consideration, it may be concluded that the vibrations, e.g., the idling vibration, excited in the steering wheel of the conventional steering system has been effectively damped by attaching a single dynamic damper to the steering wheel or the steering column of the steeling system, and by tuning a natural frequency of the single dynamic damper to the natural frequency band of the steeling system. However, the recent development in the automobile technology provides not only the above-indicated structural change in the steeling system but the above-indicated change in the internal combustion engine as well. Eventually, the conventional dynamic damper becomes incapable of exhibiting a desired vibration damping effect with respect to the vibrations excited in the steeling wheel. In particular, the conventional dynamic damper is tuned on the basis of the natural frequency of the steeling system, so that the use of the conventional dynamic damper in the recent automotive vehicles may cause undesirable deterioration of vibration conditions of the steeling wheel at a lower and higher frequency bands adjacent to the tuning frequency of the dynamic damper (i.e., the natural frequency of the steering system). In addition, since the frequency band of the idling vibrations is made lower than the natural frequency of the steering system in the recent vehicle, the conventional dynamic damper attached to the steeling system of the recent vehicle may conversely deteriorate the vibration conditions of the steeling wheel in comparison with the case where no dynamic damper is attached to the steeling system. For the above reasons, the present inventors could theorize the tendency of deterioration of the vibration condition in the steering system of the recent vibrations.
In addition, the present inventors has studied about a tilting type steering system that has been widely adopted in the recent automotive vehicles, and revealed that the natural frequency of the tilting type steering system sometimes changes when the position of the steering wheel is changed by means of a steering-wheel position mechanism of the tilting type steering system. That is, the natural frequency of the tilting type steering system may deviate from the tuning frequency of the dynamic damper depending upon the position of the steering wheel, inevitably deteriorating the vibration condition of the steering wheel.
The present invention has been developed on the basis of the above-described knowledge acquired by the present inventor through their eager studies of the steering system, and provides a dynamic damper to cope with the problem of vibrations in the recent steering wheel.
The above and/or other objects of this invention may be attained according to at least one of the following modes of the invention. Each of these modes of the invention is numbered like the appended claims and depending from the other mode or modes, where appropriate, to indicate possible combinations of elements or technical features of the invention. It is to be understood that the principal of the invention is not limited to these modes of the invention and combinations of the technical features, but may otherwise be recognized based on the teachings of the present invention disclosed in the entire specification and drawings or that may be recognized by those skilled in the art in the light of the present disclosure in its entirety.
(1) A dynamic damper for use in a steering system of an automotive vehicle, comprising: (a) a mounting member adapted to be fixed to a steering column or a steering wheel of the steering system; and (b) a plurality of secondary vibration systems each including a mass member and a spring member for elastically supporting the mass member with respect to the mounting member, the plurality of secondary vibration systems being independent of each other, wherein at least one of the plurality of secondary vibration systems has a natural frequency that is tuned to an idling vibration frequency band ranging from about 20 Hz to about 30 Hz, and at least an other one of the plurality of secondary vibration systems has a natural frequency that is tuned to a natural frequency band of the steering system, which is larger than 30 Hz.
As discussed above, the present inventors has studied in detail about vibrations excited in the steering system, which has not sufficiently been regarded or clarified conventionally, and theoretically and experimentally recognizes that the use of a plurality of dynamic dampers one of wh
Aoi Takahiro
Kato Rentaro
Beyer Weaver & Thomas LLP
Tokai Rubber Industries Ltd.
Williams Thomas
LandOfFree
Dynamic damper for steering system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Dynamic damper for steering system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dynamic damper for steering system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3302173