Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
1999-12-20
2002-10-15
Lavinder, Jack (Department: 3683)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
C267S140150, C188S267000
Reexamination Certificate
active
06464213
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vibration isolating apparatus for suppressing vibration transmitted from a vibration generating portion such as an engine or the like to a vibration receiving portion such as a vehicle body or the like, which is applicable to automobiles, construction machinery, general industrial machinery, and the like.
2. Description of the Related Art
A vibration isolating apparatus is provided between the engine of a vehicle which is a vibration generating portion and the vehicle body which is a vibration receiving portion. The vibration isolating apparatus is constructed so as to absorb vibration generated by the engine and thereby suppress the amount of vibration transmitted to the vehicle body. Vibration from the engine can here generally be considered to be a compound of pitch, which is vibration substantially in the vertical direction, and roll, which is vibration substantially in the horizontal direction. The amplitude and frequency of both the pitch and roll change according to the number of engine revolutions, the size of the engine load, and the like. Moreover, the amplitude and frequency of the vibration transmitted from the engine change according to changes in the number of engine revolutions, namely, according to changes in the vehicle running speed. Specifically, when a vehicle is travelling at between 70-80 km/h, shaking vibration in a comparatively low frequency range (less than 15 Hz) is generated. Alternatively, when the vehicle is idling or is travelling at less than 5 km/h, idling vibration in a comparatively high frequency range (20-40 Hz) is generated. Therefore, when considering the vibration absorbing performance of a vibration isolating apparatus, when shaking vibration is being generated, a high spring constant relative to the input vibration is able to effectively absorb the shaking vibration. When idling vibration is being generated, a low spring constant relative to the input vibration is able to effectively absorb the idling vibration.
Known examples of vibration isolating apparatuses used as engine mounts include hydraulic types having a rubber elastic body, a pressure receiving fluid compartment, and a plurality of fluid sub-compartments in which the pressure receiving fluid compartment and fluid sub-compartments are connected to each other by restricting passages each having a different length and cross-sectional area. In this type of vibration isolating apparatus, the aims are that vibration be absorbed by the fluid resonance and the like of the fluid present in the restricting passage and to reduce the dynamic spring constant (dynamic stiffness) relative to the vibration in each frequency range by switching which fluid sub-compartment is connected to the pressure receiving fluid compartment according to the frequency range of the input vibration.
However, in a hydraulic-type vibration isolating apparatus, when the fluid sub-compartment connected to the pressure receiving fluid compartment is switched according to the frequency range of the input vibration, it is possible to effectively reduce the dynamic spring constant relative to the pitch acting mainly as a vertical load on the elastic body. However, has not been possible to sufficiently reduce the dynamic spring constant relative to the roll acting mainly as a shear load on the elastic body. Therefore, in a hydraulic type vibration isolating apparatus, normally the static spring constant in the direction of the shear load of the elastic body is set at a somewhat high level so that the shaking vibration can be effectively absorbed. Because of this, when conventional hydraulic vibration isolating apparatuses have been used as engine mounts, they have not always been able to sufficiently absorb the roll when idling vibration is generated.
In consideration of the above, the aim of the present invention is to provide a vibration isolating apparatus capable of adjusting both a static spring constant relative to the vertical load of an elastic body and a static spring constant relative to the shear load of the elastic body to suitable values according to the characteristics of the input vibration.
SUMMARY OF THE INVENTION
The first aspect of the present invention is a vibration isolating apparatus comprising: a first mounting member connected to one of a vibration generating portion and a vibration receiving portion; a second mounting member connected to the other one of the vibration generating portion and the vibration receiving portion; an elastic body capable of elastic deformation which is provided between the first mounting member and the second mounting member; an intermediate plate for partitioning the elastic body into a first elastic piece and a second elastic piece cross-sectionally relative to a vertical load from the first mounting member or second mounting member; and restraining means provided together with the first elastic piece between the first mounting member and the intermediate plate, which restrains movement of the intermediate plate relative to the first mounting means when operated, and allows movement of the intermediate plate relative to the first mounting means when not operated.
According to this vibration isolating apparatus, an intermediate plate partitions an elastic body into a first elastic piece and a second elastic piece cross-sectionally relative to a vertical load applied from a first mounting member or a second mounting member. The restraining means prevents movement of the intermediate plate relative to the first mounting member when operated, and allows movement of the intermediate plate relative to the first mounting means when not operated. Thus elastic deformation of the first elastic piece is prevented when the restraining means is operated, and elastic deformation of the first elastic piece caused by the load transmitted from the first mounting member or the second mounting member is allowed when the restraining means is operated.
As a result, when the restraining means is operated, only the second elastic piece is able to elastically deform and function as a main absorption body. Therefore, the static spring constants of the elastic body relative to the vertical load and shear load transmitted from the first mounting member or the second mounting member are each able to be made larger than when the restricting means is not being operated. Moreover, when the restraining means is not operated, both the first elastic piece and the second elastic piece become elastically deformable and function as two main absorption bodies arranged serially to each other. Therefore, the static spring constants of the elastic body relative to the vertical load and shear load transmitted from the first mounting member or the second mounting member are each able to be made smaller than when the restraining means is being operated.
The term “vertical load” used here refers to a load which generates a deformation by compressing an elastic body or a deformation by stretching the elastic body. The term “shear load” used here refers to a load which generates shear stress relative to the vertical load in the first elastic piece and second elastic piece.
The second aspect of the vibration isolating apparatus of the present invention is a vibration isolating apparatus according to the first aspect of the present invention further having a pressure receiving fluid compartment provided between the second mounting member and the intermediate plate, at least a portion of the interior wall of the pressure receiving fluid compartment being formed by the second elastic piece, wherein the content volume of the pressure receiving fluid compartment is changed by elastic deformation of the second elastic piece, the vibration isolating apparatus also having a fluid sub-compartment connected to the pressure receiving fluid compartment by a restricting passage.
According to this vibration isolating device, the pressure receiving fluid chamber is made to expand and contract by the deformation of the second elastic pie
Lavinder Jack
Siconolfi Robert A.
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