Patent Application
20140265069
This application is directed to a axial visco-elastic mount/support for a device or apparatus, the mount providing a low static spring rate, but further configured in order to provide a significantly higher dynamic spring rate to dampen specifically applied loads imparted to the device or apparatus.
With regard to certain devices that are supported, such as hydro-electric generators, there is a need in terms of providing a mount which enables a low static spring rate for reasons of thermal stability and nominal support, among others. In the course of operation, low amplitude cyclic loads can also be imparted. There is a need to be able to provide greater dynamic stiffness of these mounts in order to buffer or dampen these vibratory loads. It would be very desirable to provide such discrete isolation in a single integrated device.
To that end and according to one aspect, there is described a visco-elastic mount comprising a housing and a piston assembly axially disposed within said housing. The piston assembly includes a piston rod and a piston head, the piston rod extending substantially through the piston head and having a first end with a first diameter and a second opposing end with a second diameter that is substantially larger than the diameter of the first piston rod, the piston assembly being axially movable relative to a visco-elastic spring disposed within said housing. According to one version, the visco-elastic spring is defined by a reservoir containing elastomeric fluid under high pressure, the mount further including a charging valve assembly that admits and maintains fluid under high pressure within the reservoir.
According to another aspect, there is provided a method for manufacturing a visco-elastic mount with increased dynamic stiffness, said method comprising:
providing a housing;
disposing a piston assembly within said housing, said piston assembly including a piston head and a piston rod extending through the piston head;
providing a visco-elastic spring within said housing wherein said piston assembly is movable axially within said housing, said piston rod including a first axial end having a first diameter and an opposite axial second end having a larger diameter than the first end, such that axial loads applied to the second end of the piston assembly cause movement of said piston assembly against said visco-elastic spring, enabling a first static spring rate while further enabling a second higher dynamic spring rate.
One advantage provided by the herein described visco-elastic mount such as for use in hydro-electric generators is that a relatively low static spring rate can be maintained, allowing for thermal stability, but in which the larger diameter portion of the piston rod further enables a significantly higher dynamic spring rate relative to the visco-elastic spring to increase low amplitude cyclic loads and thereby providing enhanced damping.
Yet another advantage realized herein is that increased dynamic stiffness is realized in a single mount assembly.
These and other features and advantages will be readily apparent from the following Detailed Description, which should be read in accordance with the accompanying drawings.
a) is a front perspective view of a charging valve assembly of the visco-elastic mount of
b) is a side sectional view of the charging valve assembly of
a) is a front perspective view of a bearing assembly of the visco-elastic mount of
b) is a side sectional view of the bearing assembly of
The following relates to an exemplary embodiment of a visco-elastic mount for use with an apparatus, for example, supporting a hydro-electric generator apparatus. It will be readily apparent, however, that the principles applied to the exemplary mount herein described mount can be used and adjusted to provide different static and dynamic spring rates for other types of supported apparatus, depending on load characteristics. In addition and throughout the course of this discussion, several terms are frequently used in order to provide a suitable frame of reference with regard to the accompanying drawings, including “top”, “bottom”, “upper”, “lower”, “distal”, “proximal”, “first”, second” and the like. These terms, however, are not intended to limit the overall scope of the invention, as described and claimed herein.
The drawings provided herein are intended only to show salient features of the exemplary visco-elastic mount apparatus. To that end, these drawings are not necessarily drawn to scale and should not be relied upon for scaling and similar purposes.
As defined herein, the term “visco-elastic” refers to any material which is viscous but which also exhibits certain elastic properties, such as the ability to store energy of deformation, and in which the application of a stress gives rise to a strain that approaches its equilibrium value slowly.
As defined herein, the terms “a”, “an”, “the”, and “said” means one or more than one.
As used herein, the terms “comprising”, “comprises” and “comprise” are open-ended transitional terms used to transition from a subject recited before the term to one or more elements recited after the term, where the element or elements listed after the term are not necessarily the only elements that make up the subject.
As used herein, the terms “containing”, “contains” and “contain” have the same open ended meaning as “comprising”, “comprises” and “comprise.
As used herein, the terms “including”, “includes” and “include” have the same open-ended meaning as “comprising”, “comprises” and “comprise”.
Referring to the figures and more specifically to
As discussed herein, a plurality of components are retained within the hollow interior of the cylindrical housing 104 that enable static load and dynamic vibratory damping with regard to a load output that is coupled hereto.
These retained components are shown in exploded form in
The third or distal axial section 130 of the piston rod 120 is defined by an outer diameter that is substantially larger than the outer diameter of the first axial section 124. According to this exemplary embodiment, the outer diameter of the first axial section 124 is about 58 mm and the outer diameter of the third axial section 130 is about 70 mm. The piston rod 120 is substantially a solid component with the exception of a pair of tubular cavities provided in the first axial section 124, as discussed herein. When assembled and as shown in
As most clearly shown in
An exemplary charging valve assembly 140, shown in greater detail in
As shown in the assembled view of
An exploded view of the front bearing assembly 156 is depicted in
The remaining rear bearing assembly 152 is substantially a mirror image of the front bearing assembly 156, although assembled in reverse order, as shown in
In terms of assembly, the piston assembly 114 is placed within the interior of the mount housing 104 with the third axial section 130 facing the first end 106 of the housing 104 and the first axial section 124 facing the second end 108. The front and rear bearing assemblies 156, 152 can then be threadingly attached onto the first and second ends 106, 108 of the housing 104, respectively utilizing spanner wrench holes in the corresponding retainer assemblies 184 of each assembly 152, 156. When finally assembled within the housing 104 and prior to loading, the third axial section 130 of the piston rod 120 extends approximately 6.3 mm from the first end 106 of the housing 104 and the first axial section 124 is slightly inset within the second end 108 of the housing 104.
The mounting plate 112 secures the second end 108 of the housing 104 of the herein described visco-elastic mount 100 to a fixed support (not shown) using threaded fasteners (not shown) secured to each of the mounting holes 112.
Prior to mounting, the set screw 170 of the charging valve assembly 140 is loosened and removed from the valve body 160 and a quantity of a hydraulic elastomer is admitted into the axial tubular cavity 134 of the piston rod 120 under pressure sufficient to move the check ball 172 relative to the ball seat 176 and permit the fluid, such as a silicone elastomer, to flow through the internal center cavity 162 of the valve body 160 and into the axial and transverse tubular cavities 134, 138 defined within the first axial section 124 of the piston rod 120, in the defined annular spacing 150, and around the piston head 116. When admission of hydraulic fluid pressure ceases, the check ball 172 is reseated with the fluid being retained within the tubular cavities 134, 138 of the piston rod 120, in the annular spacing 150, and around the piston head 116, which combine to form a high pressure fluidic reservoir. Fluid is retained within the spacing 150, around the piston head 116, and cavities 134, 138 based on the various sealing elements (e.g., 204, 208, 192) of the bearing assemblies 152, 156.
Loads are transferred to the visco-elastic mount 100 from the front end 106 of the piston rod 120, and more particularly against the slightly extending third axial section 130 of the piston assembly 114. Initially, a relatively low static spring rate is realized wherein the initial static load causes axial movement of the piston assembly 114, and more particularly the differential volume created by the two different diameters 124, 130 of the piston rod 120 as the piston rod is compressed. The rod volume entering the mount housing 104 is greater than the rod volume leaving the mount housing 104. This differential causes the fluid to compress, thus providing a low static spring rate. During faster dynamic cycle movement, the fluid pressure created in the annular spacing 150 as the fluid flows around the piston head 116, and the increased structural stiffness provided by the third axial section 130 of the piston rod 120, provides a high dynamic spring rate that permits damping of certain low amplitude loads imparted to the mount 100 such as those, for example, created by hydroelectric power generators. Damping these latter vibrations produces increased life for the mounting structure, as well as overall smoother operation.
Referring to
The preferred forms of the invention described above are to be used for illustration only, and should not be used in a limiting sense to interpret the scope of the present invention. Obvious modifications to the exemplary embodiments set forth above could be readily made by those skilled in the art and without departing from the described present invention, including the following claims.
