Abstract:
A mount has an inner metal and an outer metal with an elastomeric bushing disposed between them. The elastomeric bushing includes a first pair of interconnected passages to control the damping rate during axial motion and a second, separate pair of interconnected passages to control the damping rate during motion orthogonal to the axial direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional Application of U.S. patent application Ser. No. 11/340,208 filed on Jan. 26, 2006 now U.S. Pat. No. 7,584,944. The entire disclosure of the above application is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a hydraulically damped mount. More particularly, the present invention relates to a hydraulically damped mount having a bolt through construction which has axial damping at one frequency and radial damping at another frequency. 
     BACKGROUND OF THE INVENTION 
     There are numerous applications that exist where two members are attached to each other through a vibration damping device. These applications include automobile body mounts, subframe mounts, cradle mounts, engine mounts and the like. The vibration damping devices dampen or isolate vibrations (including noises induced by the vibrations) between the two members. 
     A fluid filled active vibration damping device has been proposed as one type of such vibration damping devices. The fluid filled device includes a first mounting member adapted to be attached to one of the two members; a second mounting member adapted to be attached to the other of the two members; an elastic body connecting the first and the second mounting members; a pressure-receiving chamber partially defined by the elastic body and filled with a non-compressible fluid; an equilibrium chamber partially defined by a flexible layer and filled with the non-compressible fluid; and an orifice passage permitting fluid communication between the pressure-receiving chamber and the equilibrium chamber. This fluid filled damping device is capable of exhibiting a desired vibration-damping effect on the basis of flows of the fluid through the orifice passage. 
     Generally, a fluid filled vibration-damping device is capable of damping vibrations in one direction which is generally in an axial direction with respect to the device. While this may be acceptable for a vibration-damping device when it is used as an engine mount, when these vibration-damping devices are used elsewhere in the vehicle, additional damping characteristics are needed for tuning the “noise, vibration and harshness” of the vehicle, especially when mounting a cab or a body on a frame. 
     SUMMARY OF THE INVENTION 
     The present invention provides the art with a hydraulically damped mount which makes it possible to have high damping at one particular frequency in the axial direction and also to have high damping at a different frequency in one direction orthogonal to the axial direction. 
     The vibration-damping device of the present invention utilizes two sets of chambers which act independently in pairs to provide the desired damping characteristics in directions that are generally perpendicular to each other. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a side view of the hydraulically damped mount in accordance with the present invention; 
         FIG. 2  is an end view of the mount illustrated in  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of the mount illustrated in  FIGS. 1 and 2  taken in the direction of arrows  3 - 3  in  FIG. 2 ; 
         FIG. 4  is a cross-sectional view of the mount illustrated in  FIGS. 1 and 2  taken in the direction of arrows  4 - 4  in  FIG. 2 ; 
         FIG. 5  is a cutaway perspective view illustrating the passages interconnecting the various chambers; 
         FIG. 6  is a cross-sectional view similar to  FIG. 3  but illustrating a mount in accordance with another embodiment of the present invention in its as molded condition; 
         FIG. 7  is a cross-sectional view of the mount illustrated in  FIG. 6  but showing the mount in its operating position; 
         FIG. 8  is a cross-sectional view of a bushing in accordance with another embodiment of the present invention; 
         FIG. 9  is a cross-sectional view of the bushing illustrated in  FIG. 8  but showing the mount in its operating position; 
         FIG. 10  is a cross-sectional view of a hydraulically damped mount in accordance with another embodiment of the present invention; and 
         FIG. 11  is a cross-sectional view of a hydraulically damped mount in accordance with another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
     There is illustrated in  FIGS. 1-5  a hydraulically damped mount in accordance with the present invention and which is designated generally by the reference numeral  10 . Mount  10  comprises an outer metal  12 , an inner metal  14  and a bushing assembly  16 . 
     Outer metal  12  is a cup-shaped component which is adapted to be secured to one of the two members (not shown) attached together by mount  10 . Outer metal  12  defines an open end  18  and a closed end  20 . Closed end  20  defines a circular aperture  22 . 
     Inner metal  14  is a cylindrical component that includes a circular cylindrical portion  24  extending through aperture  22  of outer metal  12  and a frusto-conical cylindrical portion  26  which extends out of open end  18  of outer metal  12 . A flange  28  extends radially outwardly from the end of portion  26  to form a mounting surface  30  which is designed to engage the other of the two members being attached by mount  10 . 
     Bushing assembly  16  is located between outer metal  12  and inner metal  14 . Bushing assembly  16  comprises an elastomeric bushing  32 , an internal tube  34 , a support disc  36  and a support ring  38 . Inner metal  14 , elastomeric bushing  32 , internal tube  34 , support disc  36  and support ring  38  are molded into a single component with inner metal  14 , internal tube  34 , support disc  36  and support ring  38  being bonded to elastomeric bushing  32 . Once molded, bushing assembly  16  is inserted into outer metal  12  and open end  18  of outer metal  12  is crimped or formed over support ring  38  to retain bushing assembly  16  within outer metal  12 . Support disc  36  provides support for the interface between outer metal  12  and elastomeric bushing  32 . 
     An angular wall  50  of elastomeric bushing  32  and outer metal  12  define a first or lower annular chamber  52 . In addition, elastomeric bushing  32  and outer metal  12  also define a second or upper annular chamber  54  and a fluid passageway  56  extending between chambers  52  and  54 . Fluid passageway  56  extends through one leg of internal tube  34  as shown in  FIG. 5 . Lower annular chamber  52 , upper annular chamber  54  and fluid passageway  56  are all filled with a non-compressible fluid which in the preferred embodiment is a mixture of glycol and water. Internal tube  34  provides support for upper annular chamber  54  and fluid passageway  56  during the damping movement of mount  10 . 
     During axial movement of inner metal  14  with respect to outer metal  12  or an axial movement of outer metal  12  with respect to inner metal  14 , (up and down in  FIGS. 3 and 4 ) angular wall  50  of elastomeric bushing  32  deflects such that the volume of lower annular chamber  52  increases or decreases. The change in volume of lower annular chamber  52  causes the non-compressible fluid to flow through fluid passageway  56  between lower annular chamber  52  and upper annular chamber  54 . The direction of the non-compressible fluid flow will be determined by whether lower annular chamber  52  is increasing or decreasing in volume. In order to accommodate an increase or decrease in the volume of upper annular chamber  54  when lower annular chamber  52  decreases or increases, respectively, in volume, an upper annular wall  58  of elastomeric bushing  32  forms a diaphragm which will deflect or bulge out or in. The support and attachment of support ring  38  maintains the integrity of upper annular chamber  54 . The design of fluid passageway  56 , lower annular chamber  52  and upper annular chamber  54  will determine the damping characteristics for axial movement of mount  10 . 
     Elastomeric bushing  32  and outer metal  12  define a third fluid chamber  60 , a fourth fluid chamber  62  located diametrically opposite to third fluid chamber  60  and a fluid passageway  64  extending between third and fourth fluid chambers  60  and  62 . Fluid passageway  64  extends through one leg of internal tube  34  as illustrated in  FIG. 4 . Third fluid chamber  60 , fourth fluid chamber  62  and fluid passageway  64  are filled with a non-compressible fluid which in the preferred embodiment is a mixture of glycol and water. Internal tube  34  provides support for third fluid chamber  60 , fourth fluid chamber  62  and fluid passageway  64 , during the damping movement of mount  10 . 
     During a translational movement of inner metal  14  with respect to outer metal  12  or translational movement of outer metal  12  with respect to inner metal  14 , (right and left directions in  FIG. 4 ), elastomeric bushing  32  will deflect to decrease the volume of either third fluid chamber  60  or fourth fluid chamber  62  depending on the direction of the movement. The decrease in volume of third fluid chamber  60  will cause the non-compressible fluid to flow from third fluid chamber  60  to fourth fluid chamber  62  through fluid passageway  64 . In a similar manner, the decrease in volume of fourth fluid chamber  62  will cause the non-compressible fluid to flow from fourth fluid chamber  62  to third fluid chamber  60  through fluid passageway  64 . The design for fluid passageway  64  and third and fourth fluid chambers  60  and  62  will determine the damping characteristics for translational movement (orthogonal to the axial movement) for mount  10 . Third fluid chamber  60  and fourth fluid chamber  62  are located diametrically opposite to each other. Thus, the damping characteristics for mount  10  in a direction orthogonal to the axial direction will be at a maximum in the right and left directions illustrated in  FIG. 4  and they will be at a minimum in the right and left directions illustrated in  FIG. 3 . Mount  10  also includes a rebound bumper or stop  66  as is well known in the art. A bolt  68  secures the two members being attached and mount  10  as an assembly. 
     Referring now to  FIGS. 6 and 7 , a hydraulically damped mount  110  in accordance with another embodiment of the present invention is illustrated. Mount  110  is the same as mount  10  except that an integrated dirt or heat shield  170  has been integrally molded with elastomeric bushing  32 . Shield  170  comprises a generally horizontal or disc shaped portion  172  and an upwardly angled frusto-conical section  174  as illustrated in  FIG. 6 . Once molded, as illustrated in  FIG. 6 , shield  170  can be reversed to its working position illustrated in  FIG. 7 . Elastomeric shield  170  will flip through the middle position and into its working or mirror position as illustrated in  FIG. 7  due to what is known as tin-lidding. Once reversed into its working position, shield  170  protects mount  110  from both heat and dirt contamination. 
     Referring now to  FIGS. 8 and 9 , an elastomeric mount  210  in accordance with another embodiment of the present invention is illustrated. Mount  210  comprises a tubular outer metal  212 , a tubular inner metal  214  and an annular bushing assembly  216 . Bushing assembly  216  is a cylindrical component comprising an elastomeric bushing  232  having a plurality of voids  234  and an outer housing  236 . 
     Inner metal  214 , elastomeric bushing  232  and outer housing  236  are molded with elastomeric bushing  232  being bonded to both inner metal  214  and outer housing  236 . This assembly is then press-fit within outer metal  212  to complete the assembly of elastomeric mount  210 . Mount  210  dampens the movement between outer metal  212  and inner metal  214  due to the deflection of elastomeric bushing  232 . The design for elastomeric bushing  232  including the design of voids  234  will determine the damping characteristic for mount  210 . 
     Similar to mount  110 , mount  210  includes an integrated dirt or heat shield  270  integrally molded with elastomeric bushing  232 . Shield  270  includes an upwardly angled wall  274  as illustrated in  FIG. 8 . Once molded, as illustrated in  FIG. 8 , shield  270  can be reversed to its working position illustrated in  FIG. 9 . Elastomeric shield  270  will flip through the middle position and into its working or mirror position as illustrated in  FIG. 9  due to what is known as tin-lidding. Once reversed into its working position, shield  270  protects mount  210  from both heat and dirt contamination. 
     Referring now to  FIG. 10 , a hydraulically damped mount in accordance with another embodiment of the present invention is illustrated and is designated generally by the reference numeral  310 . Mount  310  comprises a die-cast case  312 , an inner metal  314  and a bushing assembly  316 . 
     Die-cast case  312  is an annular member which is adapted to be secured to one of the two members (not shown) attached together by mount  310 . Die-cast case  312  defines an open end  318 ; a closed end  320  defining a circular aperture  322  and a channel  324 . 
     Inner metal  314  is a cylindrical component that includes a circular cylindrical portion  326  extending through aperture  322  of die-cast case  312 . A flange  328  extends radially outwardly from the end of portion  326  to form a mounting surface  330  which is designed to engage the other of the two members being attached by mount  310 . 
     Bushing assembly  316  is located between die-cast case  312  and inner metal  314 . Bushing assembly  316  comprises an elastomeric bushing  332 , an internal tube  334  and a die-cast tube  336 . Inner metal  314 , elastomeric bushing  332 , internal tube  334  and die-cast tube  336  are molded into a single component with inner metal  314 , internal tube  334  and die-cast tube  336  being bonded to elastomeric bushing  332 . Once molded, bushing assembly  316  is inserted into die-cast case  312  and internal tube  334  is press fit within open end  318  of die-cast case  312  and die-cast tube  336  is press fit within aperture  322  of die-cast case  312 . While being described as being press-fit within aperture  322  of die-cast case  312 , other method of attaching these two components is possible including but not limited to the method described below for  FIG. 11 . 
     Once assembled to die-cast case  312 , elastomeric bushing  332  sealingly engages die-cast  312  at an inner surface  340  due to an O-ring style seal  342  being formed into elastomeric bushing  332  and at an outer surface  344  due to a rubber band type seal  346  also formed into elastomeric bushing  332 . 
     An angular wall  350  of elastomeric bushing  332  and die-cast case  312  define a first or lower chamber  352 . In addition, elastomeric bushing  332  and die-cast case  312  form a second or upper chamber  354 . Channel  324  and a fluid passageway  356  in die-cast case  312  connects chambers  352  and  354 . Fluid passageway  356  extends through internal tube  334 . Lower annular chamber  352 , upper annular chamber  354 , channel  324  and fluid passageway  356  are all filled with a non-compressible fluid which in the preferred embodiment is a mixture of glycol and water. 
     During axial movement of inner metal  314  with respect to die-cast case  312 , (up and down in  FIG. 10 ), angular wall  350  of elastomeric bushing  332  deflects such that the volume of lower annular chambers  352  increases or decreases. The change in volume in lower annular chamber  352  causes the non-compressible fluid to flow through fluid passageway  356 , through channel  324 , between lower annular chamber  352  and upper annular chamber  354 . The direction of fluid flow will be determined by whether lower annular chamber  352  is increasing or decreasing in volume. In order to accommodate an increase or decrease in volume of upper annular chamber  354 , an upper annular wall  358  of elastomeric bushing  332  forms a diaphragm which will deflect or bulge in or out. The design of channel  324 , fluid passageway  356  and chambers  352  and  354  will determine the damping characteristics for axial movement of mount  310 . 
     Referring now to  FIG. 11 , a hydraulically damped mount in accordance with another embodiment of the present invention is illustrated and is designated generally by the reference numeral  410 . Mount  410  comprises a die-cast case  412 , an inner metal  414  and a bushing assembly  416 . 
     Die-cast case  412  is an annular member which is adapted to be secured to one of the two members (only one shown) attached together by mount  410 . Die-cast case  412  defines an open end  418 ; a closed end  420  defining a circular aperture  422  and a channel  424 . 
     Inner metal  414  is a cylindrical component that includes a circular cylindrical portion  426  extending through aperture  422  of die-cast case  412 . A flange  428  extends radially outwardly from the end of portion  426  to form a mounting surface  430  which is designed to engage the other of the two members being attached by mount  410 . 
     Bushing assembly  416  is located between die-cast case  412  and inner metal  414 . Bushing assembly  416  comprises an elastomeric bushing  432 , an internal tube  434  and a die-cast tube  436 . Inner metal  414 , elastomeric bushing  432 , internal tube  434  and die-cast tube  436  are molded into a single component with inner metal  414 , internal tube  434  and die-cast tube  436  being bonded to elastomeric bushing  432 . Once molded, bushing assembly  416  is inserted into die-cast case  412  and internal tube  434  is press fit within open end  418  of die-cast case  412  and die-cast tube  436  extends through aperture  422  of die-cast case  412  and is attached to die-cast case  412  by being pop-riveted or by other methods know well in the art. 
     Once assembled to die-cast case  412 , elastomeric bushing  432  sealingly engages die-cast case  412  at an inner surface  440  due to an O-ring style seal  442  being formed into elastomeric bushing  432  and at an outer surface  444  due to a rubber band type seal  446  also formed into elastomeric bushing  432 . 
     An angular wall  450  of elastomeric bushing  432  and die-cast case  412  define a first or lower chamber  452 . In addition, elastomeric bushing  432  and die-cast case  412  form a second or upper chamber  454 . Channel  424  and a fluid passageway  456  in die-cast case  412  connects chambers  452  and  454 . Fluid passageway  456  extends through internal tube  434 . Lower annular chamber  452 , upper annular chamber  454 , channel  424  and fluid passageway  456  are all filled with a non-compressible fluid which in the preferred embodiment is a mixture of glycol and water. 
     During axial movement of inner metal  414  with respect to die-cast case  412 , (up and down in  FIG. 11 ), angular wall  450  of elastomeric bushing  432  deflects such that the volume of lower annular chambers  452  increases or decreases. The change in volume in lower annular chamber  452  causes the non-compressible fluid to flow through fluid passageway  456 , through channel  424 , between lower annular chamber  452  and upper annular chamber  454 . The direction of fluid flow will be determined by whether lower annular chamber  452  is increasing or decreasing in volume. In order to accommodate an increase or decrease in volume of upper annular chamber  454 , an upper annular wall  458  of elastomeric bushing  432  forms a diaphragm which will deflect or bulge in or out. The design of channel  424 , fluid passageway  456  and chambers  452  and  454  will determine the damping characteristics for axial movement of mount  410 . 
     A rebound mount  460  is also attached to mount  410 . Rebound mount  460  comprises an outer metal  462 , an end cap  464  and a bushing assembly  466 . Outer metal  462  is a cup-shaped component which defines an open end  468  and a closed end  470 . Closed end  470  defines an outer flange  472  which is received within the internal diameter of die-cast tube  436  of bushing assembly  416 . 
     End cap  464  is an annular member which defines a central aperture  474 . Bolt  68  (not shown) extends through the two members being attached, inner metal  414  and end cap  464  to secure the mounting system. 
     Bushing assembly  466  is located between outer metal  462  and inner metal  414 . Bushing assembly  466  comprises an elastomeric bushing  482  and an internal tube  484 . Elastomeric bushing  482  and internal tube  484  are molded into a single component with internal tube  484  being bonded to elastomeric bushing  482 . Once molded, bushing assembly  466  is inserted into outer metal  462  and the outer end of internal tube  484  is crimped or formed over open end  468  of outer metal  462  to retain bushing assembly  466  within outer metal  462 . This assembly is then attached to mount  410  by assembling elastomeric bushing  482  over inner metal  414  and by engaging outer flange  472  with die-cast tube  436 . Elastomeric bushing  482  can form an interference fit with inner metal  414  or elastomeric bushing  482  can be bonded to inner metal  414 . When assembled to the vehicle, bolt  68  (not shown) extends through the two components being joined, inner metal  414  and end cap  464  to secure the mounting system. The gap between end cap  464  and inner metal  414  in conjunction with elastomeric bushing  482  acts as a rebound stop for the mounting system. 
     Elastomeric bushing  482  and outer metal  462  define a third fluid chamber  490 , a fourth fluid chamber  492  located diametrically opposite to third fluid chamber  490  and a fluid passageway  494  extending between third and fourth fluid chambers  490  and  492 . Fluid passageway  494  extends through one leg of internal tube  484 . Third fluid chamber  490 , fourth fluid chamber  492  and fluid passageway  494  are filled with a non-compressible fluid which in the preferred embodiment is a mixture of glycol and water. Internal tube  484  provides support for third fluid chamber  490 , fourth fluid chamber  492  and fluid passageway  494 , during the damping movement of rebound mount  460 . 
     During a translational movement of inner metal  414  with respect to outer metal  462  or translational movement of outer metal  462  with respect to inner metal  414 , (right and left directions in  FIG. 11 ), elastomeric bushing  482  will deflect to decrease the volume of either third fluid chamber  490  or fourth fluid chamber  492  depending on the direction of the movement. The decrease in volume of third fluid chamber  490  will cause the non-compressible fluid to flow from third fluid chamber  490  to fourth fluid chamber  492  through fluid passageway  494 . In a similar manner, the decrease in volume of fourth fluid chamber  492  will cause the non-compressible fluid to flow from fourth fluid chamber  492  to third fluid chamber  490  through fluid passageway  494 . The design for fluid passageway  494  and third and fourth fluid chambers  490  and  492  will determine the damping characteristics for translational movement (orthogonal to the axial movement) for rebound mount  460 . Third fluid chamber  490  and fourth fluid chamber  492  are located diametrically opposite to each other. Thus, the damping characteristics for rebound mount  460  in a direction orthogonal to the axial direction will be at a maximum in the right and left directions illustrated in  FIG. 11  and they will be at a minimum in directions perpendicular to those shown in  FIG. 11 . 
     The description of the invention is merely exemplary in nature and, thus, 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.