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The field of the present invention generally relates to vibration isolation systems and, more particularly, to vibration isolation systems for rooftop mounted equipment.
Heating ventilating and air conditioning equipment (HVAC), particularly air conditioning condensers, is often mounted on building rooftops. Because this HVAC equipment is a vibration source, it can transfer vibration to the building structure. In some cases the building can noticeably move and shake. As a result, it is desirable to mount the HVAC equipment in a manner to isolate the building from the shocks and vibration produced by the HVAC equipment.
There are many means for isolating objects from shocks and vibration. Rooftop mounted condensers are often mounted on stands with springs located between the condenser and the stand so that the springs isolate the building from the shock and vibration produced by the condenser. While these springs are somewhat effective, they often do not completely isolate the condenser because they cannot be broadly applied across a wide spectrum of applications. One unique means of isolating objects from shocks and vibration has a flexible member supported on knife edge supports. For example, see U.S. Pat. Nos. 6,220,563, 6,595,483, and 7,086,509, the disclosures of which are expressly incorporated herein in their entireties by reference. These vibration isolation systems can be broadly applied across a wide spectrum of applications such as, for example, motors, marine engines, HVAC equipment such as compressors, house hold appliances such as clothes washing machines, and architectural applications such as buildings and bridges. While these systems are excellent for isolating objects from shock and vibration they may have limitations in rooftop applications where there are high winds and/or hurricanes because the wind loads must be carried through the flexible members.
In high wind and/or hurricane zones, it is important to mount rooftop equipment against dislodgement because of not only damage that can be caused to the roof and the HVAC equipment but also because the dislodged HVAC equipment can create an unprotected opening through which significant amounts of water can enter the building and the dislodged HVAC equipment can become air bourn debris that causes further damage and/or injury. Some states which frequently have high wind and/or hurricanes have building codes to address these issues. For example, the state of Florida has statewide building code ASCE 7-05. Accordingly, there is a need in the art for improved vibration isolation systems for use in rooftop applications.
Disclosed are vibration isolation systems that overcome at least one of the disadvantages of the prior art described above. Disclosed is a vibration isolation assembly for mounting a vibration source that comprises, in combination, a bottom tray and having a pair of flanges, a top tray adapted to support the vibration source thereon and having a pair of flanges, and at least one vibration isolator located between the top and bottom trays and secured to the top and bottom trays to isolate vibration produced by the vibration source. The flanges of the bottom tray and the flanges of the top tray are spaced apart when loaded by the vibration source to permit movement of the top tray relative to the bottom tray during normal operation of the vibration source and engage when wind loads are applied to the vibration source so that the wind loads transfer through the flanges of the top tray to the flanges of the bottom tray rather than through the vibration isolator.
Also disclosed is a vibration isolation assembly for mounting a vibration source which comprises, in combination, an elongate bottom tray which is channel-shaped in cross-section and includes a horizontally extending base wall, side walls upwardly extending from lateral edges the base wall, and flanges extending from upper ends of the side walls, and an elongate top tray which is channel-shaped in cross-section and includes a horizontally extending base wall, side walls downwardly extending from lateral edges the base wall, and flanges extending from lower ends of the side walls. The base wall of the top tray is adapted to support the vibration source. A pair of longitudinally spaced-apart vibration isolators are located between the top and bottom trays and secured to the top and bottom trays to isolate vibration produced by the vibration source. The flanges of the bottom tray and the flanges of the top tray are spaced apart when loaded by the vibration source to permit movement of the top tray relative to the bottom tray during normal operation of the vibration source and engage when wind loads engage the vibration source so that the wind loads transfer through the flanges of the top tray to the flanges of the bottom tray rather than through the vibration isolators.
Also disclosed is a vibration isolation system comprising, in combination, a pair of laterally spaced-apart vibration isolation assemblies. Each of the vibration isolation assemblies comprise an elongate bottom tray which is channel-shaped in cross-section and includes a horizontally extending base wall, side walls upwardly extending from lateral edges the base wall, and flanges extending from upper ends of the side walls, an elongate top tray which is channel-shaped in cross-section and includes a horizontally extending base wall, side walls downwardly extending from lateral edges the base wall, and flanges extending from lower ends of the side walls, and a pair of longitudinally spaced-apart vibration isolators located between the top and bottom trays and secured to the top and bottom trays to isolate vibration produced by the vibration source. The vibration source supported on the top trays of the vibration isolation assemblies. The flanges of the bottom trays and the flanges of the top trays are spaced apart when loaded by the vibration source to permit movement of the top trays relative to the bottom trays during normal operation of the vibration source and engage when wind loads engage the vibration source so that the wind loads transfer through the flanges of the top trays to the flanges of the bottom trays rather than through the vibration isolators.
From the foregoing disclosure and the following more detailed description of various preferred embodiments it will be apparent to those skilled in the art that the present invention provides a significant advance in the technology and art of vibration isolation systems. Particularly significant in this regard is the potential the invention affords for a device that isolates shock and vibration but locks under high wind load and is relatively inexpensive to produce and maintain. Additional features and advantages of various preferred embodiments will be better understood in view of the detailed description provided below.
These and further features of the present invention will be apparent with reference to the following description and drawing, wherein:
It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the invention. The specific design features of the vibration isolation systems as disclosed herein, including, for example, specific dimensions and shapes of the various components will be determined in part by the particular intended application and use environment. Certain features of the illustrated embodiments have been enlarged or distorted relative to others to facilitate visualization and clear understanding. In particular, thin features may be thickened, for example, for clarity or illustration. All references to direction and position, unless otherwise indicated, refer to the orientation of the vibration isolation systems illustrated in the drawings. In general, up or upward refers to an upward direction within the plane of the paper in
It will be apparent to those skilled in the art, that is, to those who have knowledge or experience in this area of technology, that many uses and design variations are possible for the improved vibration isolation systems disclosed herein. The following detailed discussion of various alternative and preferred embodiments will illustrate the general principles of the invention with regard to the specific application of a rooftop mounted air conditioning compressor. Other embodiments suitable for other applications will be apparent to those skilled in the art given the benefit of this disclosure.
The illustrated vibration isolation assemblies 18 are identical and each include a top tray 26 to which the vibration source 12 is secured with the attachment brackets 20, a bottom tray 28 located below the top tray 26 and is secured to the stand 14 or other support structure, and at least one vibration isolator 30 located between the top and bottom trays 26, 28 and operably connected to the top and bottom trays 26, 28. The illustrated vibration isolation assembly 18 includes two of the vibration isolators 30 which are longitudinally spaced apart. It is noted however that a fewer or greater quantity of the vibration isolators 30 can be utilized depending on the requirements of the particular application.
The illustrated vibration isolators 30 each include a pair of longitudinally spaced-apart bearing supports 56 secured to the bottom tray 28, an elongate elastic member 58 having end portions supported by the pair of supports 56 and capable of bending in response to a load applied to a midportion of the elastic member 58 intermediate the pair of bearing supports 56 to allow oscillation of the elastic member 58 in response to a vibrating load in communication with the elastic member 58, and a connector 60 operably connecting the top tray 26 to the midportion of the flexible member 58 to transfer loads of the vibration source 12 and the top tray 26 to the flexible member 58. The illustrated elastic member 58 is supported solely by the bearing supports 56. The elastic member 58 is capable of deflecting from an original position to a more or less bowed position in response to changes in load in communication with the midportion of the elastic member 58 intermediate its ends, with the amount of the deflection being dependent on the magnitude of the applied force within the load bearing capacity of the elastic member 58. The elastic member 58 is also capable of returning to its original position when the original force acting on the elastic member 58 is restored. See U.S. Pat. Nos. 6,220,563, 6,595,483, and 7,086,509, the disclosures of which are expressly incorporated herein in their entireties by reference, for examples of possible variations of the vibration isolators 30.
The elastic member 58 may comprise any suitable material which allows it to deflect in response to changes in the applied load and return essentially to its original position when the original load is restored. The material of the elastic member 58 can be any suitable metal, plastic, elastomer, composite materials, or the like. The elastic member 58 should be selected to have a static deflection appropriate for the anticipated load, with greater static deflection being required to isolate lower frequency vibrations. The illustrated elastic member 58 is a unitary member of solid round cross-section of any suitable shape can be utilized, including but not limited to hollow tubes, I-beams, or the like. The elastic member 58 can alternatively be a composite member comprising a bundle of continuous elastic subunits held together by any suitable means.
The illustrated bearing supports 56 engage the elastic member 58 at a distance spaced from longitudinal, unrestrained ends of the elastic member 58. Each of the illustrated bearing supports 58 include a sleeve bearing 64 sized and shaped to accommodate the shape and dimensions of the elastic member 58 and reduce friction between the bearing 64 and the elastic member 58 and a mounting bracket 66 for securing the bearing 64 to the bottom tray 28. The illustrated bearing 64 is a discrete element attached to the mounting bracket 66 but alternatively can be formed unitary therewith to form a one-piece component. The illustrated bearing 64 is an ABS bushing but it is noted that it can alternatively comprise any other suitable material and/or form.
The illustrated connector 60 engages the elastic member 58 at the midportion of the elastic member 58 between the bearing supports 56. The illustrated connector 60 includes a sleeve bearing 76 sized and shaped to accommodate the shape and dimensions of the elastic member 58 and a mounting bracket 78 for securing the bearing 76 to the top tray 26. The illustrated bearing 76 is a discrete element attached to the mounting bracket 78 but alternatively can be formed unitary therewith to form a one-piece component. The illustrated bearing 76 is an ABS bushing but it is noted that it can alternatively comprise any other suitable material and/or form.
The illustrated vibration source 12 is secured to the top trays 26 at each end of the top trays 26 with the attachment brackets 20.
With the vibration source 12 secured to the top tray 26, the vibration source 12 is placed in communication with the midportion of the elastic member 58. The elastic member 58 bends in response to vibration loads transmitted to it from the vibration source 12. Variations in the load applied to the elastic member 58 cause the elastic member 58 to bear on its bearing supports 56 at different positions along the ends of the elastic member 58. As the load on the elastic member 58 exerts a downward force and the elastic member 58 bows downwardly in response to this load, the length of the midportion of the elastic member 58 extending between the bearing supports 56 increases beyond any dimension caused solely by thermal expansion and contraction. The length of the midportion correspondingly decreases when the downwardly directed force associated with the load decreases. Thus the elastic member 58 oscillates in response to the vibrating load of the vibration source 12 which is transferred to the elastic member 58.
The top and bottom trays 26, 28 are configured so that the flanges 48 of the top tray 26 are adjacent and or engaged with the flanges 36 of the bottom tray 28 and below the flanges 36 of the bottom tray 28 prior to applying the static load of the condenser 12 to the top tray 26 (best seen in
The illustrated vibration isolation system 10 has four parallel elastic members 58 in communication with the vibration source 12. However, the vibration source 12 can alternatively be in communication with any other quantity of the elastic members 58 and/or configuration of elastic members 58 depending on the desired requirements for the particular application.
Any of the features or attributes of the above the above described embodiments and variations can be used in combination with any of the other features and attributes of the above described embodiments and variations as desired.
From the foregoing disclosure it will be apparent that the vibration isolation systems 10 according to the present invention provide improved means for isolating vibrations and withstanding high wind loads.
From the foregoing disclosure and detailed description of certain preferred embodiments, it will be apparent that various modifications, additions and other alternative embodiments are possible without departing from the true scope and spirit of the present invention. The embodiments discussed were chosen and described to provide the best illustration of the principles of the present invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the present invention as determined by the appended claims when interpreted in accordance with the benefit to which they are fairly, legally, and equitably entitled.