Abstract:
A damper for a linear element of a motor vehicle drivetrain such as a cable, a transmission oil fill tube or an engine oil dipstick tube constitutes a loose fitting sleeve or annulus disposed about the linear component. The damper may be positioned on a substantially vertical tube by a stop which may be any device such as a sleeve of material having an outside diameter larger than the inside diameter of the damper that is clamped or secured to the tube. Alternatively, the damper may be of sufficient length that one end may be clamped to the tube while the other end, which loosely fits on the tube, acts as a damper. The damper may be fabricated of a material such as closed cell foam or other relatively lightweight, resilient and compressible material.

Description:
FIELD 
       [0001]    The present disclosure relates to damper assemblies and more particularly to sleeve damper assemblies for damping sympathetic vibrations in motor vehicle engine components. 
       BACKGROUND 
       [0002]    The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
         [0003]    The impact of unwanted, sympathetic vibration or resonances of elements in mechanical systems ranges from inconsequential, through annoying and service life limiting to problematic and catastrophic. Certainly the extent or magnitude of such sympathetic vibration plays a role in locating a particular activity along the foregoing spectrum. Additionally, the type of product, i.e., whether it is a refrigerator, an air compressor, an electric generator, a motor vehicle powertrain, an airplane or a suspension bridge determines whether the vibration is a nuisance, the source of consumer complaints or a safety issue. 
         [0004]    The most complex consumer products, at least from a mechanical standpoint, are clearly motor vehicles. With thousands of components, frequent new and re-designed mechanical components, an emphasis on weight reduction, lengthy service lives and vehicle service and care ranging from virtually total neglect to careful and complete, sympathetic vibration or resonance of components is a constant and constantly addressed engineering issue. 
         [0005]    In motor vehicles, the drive or powertrain tends to be the situs of most sympathetic vibration problems and thus the focus of the most attention. A common area of difficulty typically involves a linear component, such as a cable or tubing, that extends unsupported between two points. The most difficult problems arise when a linear element includes an unsupported length that is free standing, such as a transmission oil fill tube or engine oil dipstick tube. 
         [0006]    Various solutions have been heretofore proposed. Perhaps the most common involves strengthening the linear element. Such a solution adds to the weight and cost of the component and it still may be subject to sympathetic vibration or resonance—just at a different frequency. Adding additional braces or points of attachment is also a common solution but, once again, it not only adds weight and cost but also increases the time and cost of assembly. 
         [0007]    The present invention is directed to reducing or eliminating sympathetic vibration of linear components in mechanical systems such as vehicle powertrains. 
       SUMMARY 
       [0008]    The present invention provides a damper assembly for a linear element of a motor vehicle such as a cable, tube, transmission oil fill tube or engine oil dipstick tube. A first embodiment of the damper assembly constitutes a loose fitting sleeve or annulus disposed about a linear component such as a cable, a cooler pipe or line, a transmission oil fill tube or engine dipstick tube. The sleeve damper assembly may be positioned on a substantially vertical tube by a stop which may be any device such as a sleeve of material having an outside diameter larger than the inside diameter of the damper that is clamped or secured to the tube. In a second embodiment, the damper sleeve is of sufficient length that one end may be clamped to the tube while the other end, which loosely fits on the tube, acts as a damper. The damper sleeve may be fabricated of a material such as closed cell foam or other relatively lightweight, resilient and compressible material. The damper moves or “rattles” in random, chaotic manner to absorb energy and interfere with and thus minimize or eliminate resonance or harmonic vibration of the associated linear element. 
         [0009]    Thus it is an aspect of the present invention to provide a damper assembly for a linear mechanical element such as a cable, a cooler pipe or line, a transmission fill tube or an engine dipstick tube. 
         [0010]    It is a further aspect of the present invention to provide a damper sleeve which fits loosely about a linear mechanical element. 
         [0011]    It is a still further aspect of the present invention to provide a damper sleeve having at least a portion which fits loosely about a linear mechanical element. 
         [0012]    It is a still further aspect of the present invention to provide a damper assembly which moves or “rattles” in a random, chaotic manner. 
         [0013]    It is a still further aspect of the present invention to provide a damper assembly which absorbs energy and interferes with and thus minimizes or eliminates unwanted harmonic vibration of an associated mechanical element. 
         [0014]    Further aspects, advantages and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0015]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0016]      FIG. 1  is a perspective view of a transmission fill tube having a first embodiment of a sleeve damper assembly according to the present invention installed thereon; 
           [0017]      FIG. 2  is an enlarged, fragmentary, perspective view of a first embodiment of a sleeve damper assembly according to the present invention on a transmission fill tube; 
           [0018]      FIG. 3  is a perspective view of a transmission fill tube having a second embodiment of a sleeve damper assembly according to the present invention installed thereon; and 
           [0019]      FIG. 4  is an enlarged, fragmentary, perspective view of a second embodiment of a sleeve damper assembly according to the present invention on a transmission fill tube. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
         [0021]    With reference to  FIG. 1 , a transmission fill tube upon which a sleeve damper assembly according to the present invention is mounted is illustrated and generally designated by the reference number  10 . The transmission fill tube  10  is typically an elongate, hollow tube that is secured to and extends upwardly from a transmission housing  12 . The transmission housing  12  receives, locates and protects various components (not illustrated) of the transmission  14 . The transmission fill tube  10  is typically between one foot and four feet in length (30.5 cm. to 122 cm.) in a typical passenger car, light truck or sport utility vehicle and extends from the transmission housing  12  upwardly to a location of convenient access within the engine compartment to a terminus  16 . Depending upon the length of the transmission fill tube  10 , it may include one or more brackets or straps  18  which are secured or attached to the transmission housing  12  and/or an engine  20  by, for example, suitable fasteners such as bolts or machine screws  22 . The transmission fill tube  12  facilitates addition of transmission fluid (not illustrated) to the transmission  14  as needed. In addition to facilitating addition of fluid to the transmission  14 , the transmission fill tube  10  receives a removable flexible, typically flat shaft or dipstick  24  that facilitates determining the level of fluid in the transmission  14 . The dipstick  24  preferably includes a top seal, cap or grommet  26  that closes off the terminus  16  of the transmission fill tube  10 . 
         [0022]    A significant portion of the transmission fill tube  10 , especially that portion most distant from the transmission housing  12  and adjacent the terminus  16 , may be unsupported. As noted above, such unsupported lengths of a tubular, elongate component such as the transmission fill tube  10  may permit or encourage resonance or sympathetic vibration of the component. 
         [0023]    Referring now to  FIGS. 1 and 2 , a first embodiment of a sleeve damper assembly according to the present invention is illustrated and generally designated by the reference number  30 . The sleeve damper assembly  30  is typically and preferably installed on an unsupported portion of the transmission fill tube  10 . The sleeve damper assembly  30  includes a tubular damper sleeve  32  which defines a through, axial passageway  34 . The damper sleeve  32  is preferably fabricated of conventional closed cell polyurethane foam satisfying ASTM D1056 2D2 and having a UL 94 V-O coating. Other relatively lightweight, softly resilient materials such as foam rubber and materials having different densities are also suitable. 
         [0024]    The damper sleeve  32  is preferably between about 3 inches (76.2 mm.) to 6 inches (152.4 mm.) in length, preferably has a wall thickness of between about 0.20 inches (5.1 mm.) and 0.35 inches (9.0 mm.) and preferably an inside diameter (the diameter of the axial passageway  34 ) of between 0.75 inches (19.05 mm.) and 1.25 inches (31.75 mm.). Preferably, as well, the outside diameter of the transmission fill tube  10  will be at least one-half of the diameter of the axial passageway  34 . The foregoing dimensions are approximate only and it should be understood that they will vary (even outside the stated ranges) depending upon the density of the material of which the damper sleeve  32  is fabricated, the outside diameter of the transmission fill tube  10 , the particular frequency or band of frequencies desired to be attenuated by the sleeve damper assembly  30  and other design variables. 
         [0025]    Below the damper sleeve  32  and disposed in supporting relationship with it is a fixed collar, stop or support  36 . The collar, stop or support  36  has an outer diameter that is slightly larger than the diameter of the axial passageway  34  such that the damper sleeve  32  cannot slide along or down the transmission fill tube  10  beyond the location at which the upper edge of the collar, stop or support  36  engages the lower edge of the damper sleeve  32 . The stop or support  36  may be of any suitable material such as the closed cell foam described above or other reasonably durable and lightweight material. If fabricated of closed cell foam or other, similar resilient material, the stop or support  36  may be readily secured to the transmission fill tube  10  by, for example, a strap, cable tie  38  or a similar tensioning device. Alternatively, a suitable adhesive may be utilized. 
         [0026]    Referring now to  FIG. 3 , a second embodiment of a sleeve damper assembly according to the present invention is illustrated and generally designated by the reference number  50 . The second embodiment of the sleeve damper assembly  50  is shown in place on a transmission fill tube  10 ′. The transmission fill tube  10 ′ extends from a transmission housing  12 ′ and may include one or more mounting brackets or straps  18 ′. Typically, the transmission fill tube  10 ′ receives a removable flexible, typically flat shaft or dipstick  24 ′ that facilitates determining the level of fluid in the transmission  14 . The dipstick  24  preferably includes a top seal, cap or grommet  26 ′ that closes off the fill tube  10 ′. Proximate the upper terminus  16 ′ of the transmission fill tube  10 ′, typically in an unsupported region, is disposed the sleeve damper assembly  50 . The sleeve damper assembly  50  includes a single, elongate tubular damper sleeve  52  which defines a through, axial passageway  54 . The damper sleeve  52  is preferably fabricated of conventional closed cell polyurethane foam satisfying ASTM D1056 2D2 and having a UL 94 V-O coating. Other softly resilient materials such as foam rubber and materials having different densities are also suitable. 
         [0027]    The damper sleeve  52  is preferably between about 4 inches (101.6 mm.) to 7 inches (177.8 mm.) in length, preferably has a wall thickness of between about 0.20 inches (5.1 mm.) and 0.35 inches (9.0 mm.) and preferably an inside diameter (the diameter of the axial passageway  54 ) of between 0.75 inches (19.05 mm.) and 1.25 inches (31.75 mm.). Preferably, as well, the outside diameter of the transmission fill tube  10 ′ will be at least one-half of the diameter of the axial passageway  54 . The foregoing dimensions are approximate only and it should be understood that they will vary (even outside the stated ranges) depending upon the density of the material of which the damper sleeve  52  is fabricated, the outside diameter of the transmission fill tube  10 ′, the particular frequency or band of frequencies desired to be attenuated by the sleeve damper assembly  50  and other design variables. 
         [0028]    Referring now to  FIGS. 3 and 4 , the damper sleeve  52  includes a pair of radially aligned, that is, diametrically opposed, axially extending cuts or slits  56 A and  56 B at the lower end of the damper sleeve  52 , that is, the end most distant from the terminus  16 ′ of the transmission fill tube  10 ′. The damper sleeve  52  is preferably disposed on the transmission fill tube  10 ′ with the cuts or slits  56 A and  56 B aligned horizontally. Threaded through the cuts or slits  56 A and  56 B, around the lower half of the transmission fill tube  10 ′ and over the upper, outside surface of the damper sleeve  52  is a strap or cable tie  58  or similar tensioning or securement device. Positioning the strap or cable tie  58  proximate one end of the damper sleeve  52  (the lower end) allows a maximum length of the damper sleeve  52  to move and vibrate to interfere with and cancel out vibrations and to absorb energy. Fastening the cable tie  58  around the lower half of the transmission fill tube  10 ′ and the upper surface of the damper sleeve  52  maintains an open region  62  within and at the lower portion of the axial passageway  54  to allow dirt and debris to pass through the damper sleeve  52  and thereby prevent the accumulation of dirt and debris within the axial passageway  54  of the damper sleeve  52  which would interfere with its operation. 
         [0029]    In operation, both the first embodiment of the sleeve damper assembly  30  and the second embodiment of the sleeve damper assembly  50  function in essentially the same way: as untuned, i.e., chaotic, dampers or energy absorbing and dissipating devices to damp unwanted resonances or sympathetic vibrations in unsupported portions of linear elements such as cables, and engine and transmission fill tubes in motor vehicles. Thus, they be readily and easily fitted about and secured to such elements and, without extensive tuning and matching of source and damper fundamental and harmonic frequencies, they function as untuned, chaotic dampers to attenuate the motion of the linear element and to absorb and dissipate vibratory energy over a broad frequency spectrum. 
         [0030]    The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.