Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
1999-07-27
2001-07-31
Oberleitner, Robert J. (Department: 3613)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
C267S219000
Reexamination Certificate
active
06267362
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid sealed type elastic mount such as an engine mount for an automotive vehicle.
2. Description of the Prior Art
Such a liquid sealed type elastic mount is disclosed for example in Japanese Patent Publication (Kokoku) No. Sho 62-23178, comprising a first support member for attachment to a vibration source, a cylindrical shaped second support member for attachment to a vehicle body, a conical shaped rubber body interposed between the two support members, and a liquid chamber formed within the rubber body to receive buffering liquid therein, wherein a disk shaped member is provided projecting from the first support member into the second support member, a partition member is arranged to divide the second support member into two chambers, an annular passage is formed between an outer peripheral portion thereof and an inner wall of the second support member, and a thin wall portion is partially provided on the rubber body to function as a diaphragm or a diaphragm is provided on a bottom portion of the second support member. In the present invention, we mean a frequency below 400 Hz by a low frequency range, a frequency of 40 to 500 Hz by a medium frequency range, a frequency above 500 Hz by a high frequency range, and especially a frequency of 500 to 1000 Hz in the high frequency range by a medium to high frequency range.
According to an above-described construction, since it is aimed to damp vibrations by means of flow resistance of the disk shaped member, the mount can deal with vibrations merely in the region of 10 Hz. However, it starts to have a high dynamic spring characteristic in a medium frequency range of for example 100 to 500 Hz and in a medium to high frequency range of for example 500 to 1000 Hz. On the other hand, it is known that an open and close type idle orifice passage, which communicates only when it is in a state of engine idling, is provided, whereby a low dynamic spring characteristic is realized. In this case also however, the mount has a low dynamic spring characteristic only in the idling range and it can not contribute for lowering the dynamic spring characteristic in other frequency range where the idle orifice passage is closed.
Further, it is known that the rubber wall of the liquid chamber is formed with a uniform thickness in a circumferential direction and a disk shaped member, which is connected to the first support member and projects into the liquid chamber, whereby a low dynamic characteristic is realized in the medium to high frequency range. In such a liquid sealed type mount, the disk shaped member acts as a medium to high frequency device and liquid column resonance is generated at a specified frequency in the medium to high frequency range, accompanied by a flow of liquid in a gap between the peripheral rubber wall and the disk shaped member.
However, even if the dynamic spring constant becomes low in the medium to high frequency range through liquid column resonance by means of the medium to high frequency device, since a peak appears by a reaction of the low dynamic spring constant in a somewhat higher frequency, which results in a high dynamic spring constant in the high frequency range. In recent years, it is a requirement that if there is a low dynamic spring constant in a low frequency range, it is also required that the dynamic spring characteristic is made lower not only in the medium to high frequency range but also in the high frequency range, and a low dynamic spring characteristic is thus realized in a wide frequency range.
SUMMARY OF THE INVENTION
In order to solve the above subject, there is provided a liquid sealed type elastic mount comprising: a first support member for attachment to a vibration source; a second support member for attachment to a vehicle body; an elastic member of substantially conical shape interposed between the first and second support members, the first support member and second support member being adapted to form a liquid chamber therebetween with at least a part of a wall thereof; a partition wall dividing the liquid chamber into a main liquid chamber and an auxiliary liquid chamber; an orifice passage formed within the partition wall for normally communicating the two liquid chambers; wherein a part of the orifice passage is formed of an elastic membrane portion which deforms elastically by rising of an inner pressure of the sealed liquid.
Since a elastic membrane is provided at a part of the orifice passage, a low dynamic characteristic is realized by means of elastic deformation of the elastic membrane portion when inner pressure of liquid increases. In addition, it is not required that the elastic membrane portion is provided at a remote position from the orifice passage, since a part of the orifice passage is constructed by the elastic membrane portion. Constitution of a liquid sealed mount thus becomes simple and miniaturization of the mount becomes possible.
The elastic membrane portion may be provided close to an inlet of the orifice passage, whereby it is possible to flow a higher pressure part of the liquid flowing into the orifice passage to the elastic membrane portion. This makes elastic deformation of the elastic membrane large to effectively absorb an increasing amount of inner pressure.
The elastic membrane portion may .be formed integrally with the orifice passage or as a separated body therefrom. When the elastic membrane portion is formed integrally with the orifice passage, it becomes easy to form the elastic membrane because it is not required to form especially the same alone. Whereby it can be achieved to decrease the number of parts, to reduce working cost, and to stabilize quality of products. On the contrary when the elastic membrane portion is formed as a separated body from the orifice passage, since material property of the elastic membrane portion can be changed from that of an orifice passage, it is easy to change a characteristic of the elastic membrane portion.
The elastic membrane portion may be made to show a nonlinear spring characteristic for magnitude of vibration input. When a small vibration is inputted, the spring constant is lowered, whereby an increasing amount of liquid pressure is effectively absorbed and the dynamic spring constant is made to be low. On the other hand, when a large vibration is inputted, the spring constant is made higher, whereby it can be prevented for the elastic membrane portion to largely deform.
At the same time, even if displacement increases by the vibration input, since it is possible to control reduction of liquid flow through the orifice passage, an effect by means of the orifice can be steadily achieved.
Hereupon, by a non-linear spring characteristic in the present invention, we mean a characteristic in which a spring constant of the elastic membrane portion does not change in proportion to magnitude of a vibration input in such a way that the spring constant suddenly rises when the vibration input increases to a certain extent.
A large deformation-controlling portion may be formed on a part of the elastic membrane portion. Thereby when a large vibration is inputted, deformation of the elastic membrane portion can be restrained by the large deformation controlling portion. Hence large deformation of the elastic membrane portion can be effectively prevented and durability of the device can be improved.
The orifice passage may comprise a plurality of the passages including a damping orifice passage usually communicating the two liquid chambers and an open and close type idle orifice passage communicating only when it is in an engine idling condition, and the elastic membrane portion may be formed on at least one of the orifice passages.
Thereby even in a condition that the idle orifice is closed, a low dynamic spring constant can be realized and lowering of the spring constant is remarkably achieved especially in the low frequency range.
The elastic membrane portion formed on at least one of the orifice passages may be arranged to sho
Sakamoto Toru
Satori Kazutoshi
Birch & Stewart Kolasch & Birch, LLP
Oberleitner Robert J.
Torres Melanie
Yamashita Rubber Kabushiki Kaisha
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