Abstract:
A damper mass damper assembly includes a rod, and a casing disposed annularly about the rod and defining a primary fluid chamber therebetween. The rod includes an annular wall that defines a first and a second expansion chamber disposed at a first and a second end of the rod respectively. The rod further defines a first and a second expansion port connecting the first and the second expansion chambers respectively with the primary fluid chamber in fluid communication. As fluid within the primary fluid chamber expands from heating, the fluid may weep into the first and/or second expansion chambers through the first and/or second expansion ports respectively to maintain the integrity of a first and second cap bearing seal, which seal the fluid within the primary fluid chamber.

Description:
TECHNICAL FIELD 
       [0001]    The invention generally relates to a wheel assembly for a vehicle, and more specifically to a damper assembly for damping vertical movement of the wheel assembly. 
       BACKGROUND 
       [0002]    Vehicular wheel assemblies are generally rotatably supported by and attached to a knuckle. The knuckle is pivotably attached to a frame of a vehicle. Other suspension components, such as a lower control arm, may also connect the knuckle to the frame, and are pivotably moveable relative to the frame and with the knuckle to accommodate vertical travel of the wheel assembly during operation. A primary damper, i.e., a shock absorber, typically interconnects one of the knuckle or the control arm to the frame and operates to attenuate vertical travel of the knuckle and the control arm. In addition to the shock absorber, a wheel damper assembly may be attached to the knuckle to further attenuate vertical vibration and/or movement of the wheel assembly. 
       SUMMARY 
       [0003]    A damper assembly for damping movement of a damper mass is provided. The damper assembly includes a rod that extends along a longitudinal axis between a first end and a second end. A casing is disposed annularly about and in sealing engagement with the rod. The casing defines a primary fluid chamber between an interior surface of the casing and the rod. A piston is fixedly attached to the rod. The piston is disposed within and divides the primary fluid chamber. The rod includes an annular wall that extends along the longitudinal axis. The annular wall defines a first expansion chamber that also extends along the longitudinal axis. The rod further defines a first expansion port that extends radially through the annular wall of the rod. The first expansion port connects the first expansion chamber and the primary fluid chamber in fluid communication. 
         [0004]    A suspension system for a vehicle is also provided. The suspension system includes a knuckle, a wheel assembly rotatably supported by the knuckle, and a damper assembly coupled to the knuckle. The damper assembly is configured for damping vertical movement of the wheel assembly. The damper assembly includes a rod. The rod extends along a longitudinal axis between a first end and a second end. Each of the first end and the second end of the rod are fixedly attached to the knuckle. A casing is disposed annularly about and in sealing engagement with the rod. The casing defines a primary fluid chamber between an interior surface of the casing and the rod. A fluid is disposed within the primary fluid chamber. The casing is moveable relative to the rod along the longitudinal axis. A mass is attached to and moveable with the casing. A first spring is coupled to the rod. The first spring is configured for opposing movement of the casing and the mass relative to the rod in a first direction along the longitudinal axis. A second spring is coupled to the rod. The second spring is configured for opposing movement of the casing and the mass in a second direction along the longitudinal axis. The first direction is opposite the second direction. A piston is fixedly attached to the rod. The piston is disposed within and divides the primary fluid chamber to define a first portion of the primary fluid chamber and a second portion of the primary fluid chamber. The piston includes at least one fluid passage extending therethrough along the longitudinal axis. The fluid passage connects the first portion and the second portion of the primary fluid chamber in fluid communication. The rod includes an annular wall that extends along the longitudinal axis. The annular wall defines a first expansion chamber and a second expansion chamber. The first expansion chamber extends along the longitudinal axis between the first end of the rod and the piston. The second expansion chamber extends along the longitudinal axis between the second end of the rod and the piston. The rod defines a first expansion port and a second expansion port. The first expansion port extends radially through the annular wall of the rod to connect the first expansion chamber and the first portion of the primary fluid chamber in fluid communication. The second expansion port extends radially through the annular wall of the rod to connect the second expansion chamber and the second portion of the primary fluid chamber in fluid communication. A first pressurized gas device is disposed within the first expansion chamber. The first pressurized gas device is compressible in response to an increase in pressure within the first expansion chamber. A second pressurized gas device is disposed within the second expansion chamber. The second pressurized gas device is compressible in response to an increase in pressure within the second expansion chamber. 
         [0005]    Accordingly, as the fluid within the primary fluid chamber expands, due to an increase in temperature for example, the fluid may flow through the first expansion port and/or the second expansion port into the first expansion chamber and/or the second expansion chamber respectively, thereby allowing the expansion of the fluid without damaging the first and/or second cap bearing seal and leaking from the primary fluid chamber. The pressurized air devices within the first expansion chamber and the second expansion chamber provide a compressible cushion to allow the fluid to expand. 
         [0006]    The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a schematic perspective view of a suspension system for a vehicle. 
           [0008]      FIG. 2  is a schematic cross sectional view of a damper assembly. 
           [0009]      FIG. 3  is a schematic cross sectional view of an alternative embodiment of the damper assembly. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    Those having ordinary skill in the art will recognize that terms such as “above,” “below,” “upward,” “downward,” “top,” “bottom,” etc., are used descriptively for the figures, and do not represent limitations on the scope of the invention, as defined by the appended claims. 
         [0011]    Referring to the Figures, wherein like numerals indicate like parts throughout the several views, a suspension system is generally shown at  20 . The suspension system  20  is for a vehicle (not shown). Referring to  FIG. 1 , the suspension system  20  includes a knuckle  22  that rotatably supports a wheel assembly  24  relative to a frame (not shown) of the vehicle. The knuckle  22  is rotatably attached to the frame for rotation about a first axis  26 . A control arm  28  includes a ball joint  29  that pivotably attaches the control arm  28  to the knuckle  22 . The control arm  28  is rotatably attached to the frame for rotation about a second axis  30 . The control arm  28  supports the knuckle  22  relative to the frame, and cooperates with the knuckle  22  to allow vertical movement of the wheel assembly  24  relative to the frame. The wheel assembly  24  is rotatably attached to the knuckle  22  in any suitable manner, and may include but is not limited to a spindle (not shown), a brake rotor  32  and a brake caliper  34 . A tie rod  36  may be attached to the knuckle  22  and connected to a steering system (not shown) of the vehicle. It should be appreciated that the suspension system  20  shown in  FIG. 1  is exemplary, and that the knuckle  22 , control arm  28  and the wheel assembly  24  may be shaped, sized and/or configured in some other manner not shown or described herein. 
         [0012]    The suspension system  20  further includes a damping system  38  coupled to the knuckle  22 . The damping system  38  includes a damper mass  40  and a damper assembly  42 . The damper assembly  42  is configured for damping vertical movement of the damper mass  40 , and thereby for damping vertical movement and/or vibration of the wheel assembly  24 . 
         [0013]    Referring also to  FIG. 2 , the damper assembly  42  includes a rod  44 . The rod  44  extends along a longitudinal axis  46  between a first end  48  and a second end  50 . The rod  44  is attached to the knuckle  22  at each of the first end  48  and the second end  50 . The rod  44  and the longitudinal axis  46  thereof are disposed in a generally vertical orientation. 
         [0014]    A casing  52  is disposed annularly about and in sealing engagement with the rod  44 . The casing  52  is moveable relative to the rod  44  along the longitudinal axis  46 . The casing  52  defines a primary fluid chamber  54  between an interior surface  56  of the casing  52  and the rod  44 . The casing  52  includes a first cap bearing seal  58  and a second cap bearing seal  60 . The first cap bearing seal  58  is disposed approximate, i.e., near, the first end  48  of the rod  44 . The first cap bearing seal  58  is configured for slideably supporting and sealing the casing  52  relative to the rod  44 . The second cap bearing seal  60  is disposed approximate, i.e., near, the second end  50  of the rod  44 . The second cap bearing seal  60  is also configured for slideably supporting and sealing the casing  52  relative to the rod  44 . The first cap bearing seal  58  and the second cap bearing seal  60  may include any sealing and bearing components necessary to seal the primary fluid chamber  54  relative to the rod  44  and moveably support the casing  52  relative to the rod  44 . A fluid  62  is disposed within the primary fluid chamber  54 . The fluid  62  may include but is not limited to a high viscosity oil suitable for damping movement between two components. 
         [0015]    The damper mass  40  is attached to and moveable with the casing  52 . The damper mass  40  may be attached to the casing  52  in any suitable manner. The damper mass  40  may include any suitable weight sufficient to offset vertical movement of the wheel assembly  24 . For example, the damper mass  40  may include but is not limited to a weight of approximately 35 Kg. However, the weight of the damper mass  40  may vary for each different application. Vertical movement and/or vibration of the knuckle  22  imparts a vertical movement in the damper mass  40 , which transmits the vertical movement to the casing  52 . However, because the casing  52  and the damper mass  40  are moveable relative to the rod  44 , which supports the damper mass  40  and the casing  52  relative to the knuckle  22 , the damper mass  40  and the casing  52  may move vertically relative to the knuckle  22 . The damper assembly  42  dampens the vertical movement of the damper mass  40  and the casing  52  to reduce the vibration and/or vertical movement of the knuckle  22 , thereby improving driving performance and/or handling of the vehicle. 
         [0016]    Referring to  FIG. 2 , the damper assembly  42  includes a first spring  64  and a second spring  66 . The first spring  64  is coupled to the rod  44  near the first end  48  of the rod  44 . The first spring  64  is configured for opposing movement of the casing  52  relative to the rod  44  in a first direction along the longitudinal axis  46 . The first direction is generally indicated by direction arrow  68 . The second spring  66  is coupled to the rod  44  near the second end  50  of the rod  44 . The second spring  66  is configured for opposing movement of the casing  52  in a second direction along the longitudinal axis  46 . The second direction is generally indicated by direction arrow  70 . The first direction  68  is opposite the second direction  70 . Accordingly, when the damper mass  40  moves toward the first end  48  of the rod  44 , the first spring  64  resists the movement of the damper mass  40  and the casing  52 . Similarly, when the damper mass  40  moves toward the second end  50  of the rod  44 , the second spring  66  resists the movement of the damper mass  40  and the casing  52 . As shown in  FIG. 2 , the first spring  64  and the second spring  66  may be disposed externally of and concentric with the casing  52 , i.e., outside the casing  52 . However, as shown in  FIG. 3 , the first spring  64  and the second spring  66  may alternatively be disposed internally of and concentric with the casing  52 , i.e., inside the casing  52  within the primary fluid chamber  54  of the casing  52 . 
         [0017]    A piston  72  is fixedly attached to the rod  44 . The piston  72  is disposed within and divides the primary fluid chamber  54 . The piston  72  divides the primary fluid chamber  54  to define a first portion  74  of the primary fluid chamber  54  and a second portion  76  of the primary fluid chamber  54 . The piston  72  includes at least one fluid passage  78  extending therethrough. The fluid passage  78  extends along the longitudinal axis  46  to connect the first portion  74  and the second portion  76  of the primary fluid chamber  54  in fluid communication. The fluid passage  78  may be configured in any suitable manner, and may include a valve (not shown) and/or other components capable of regulating the flow of the fluid  62  between the first portion  74  and the second portion  76  of the primary fluid chamber  54 . It should be appreciated that as the casing  52  moves toward the first end  48  of the rod  44 , the first portion  74  of the primary fluid chamber  54  increases in volume and the second portion  76  of the primary fluid chamber  54  decreases in volume. As this change in volume occurs, the fluid  62  is forced from the second portion  76  into the first portion  74  through the fluid passage  78 . Similarly, as the casing  52  moves toward the second end  50  of the rod  44 , the second portion  76  of the primary fluid chamber  54  increases in volume and the first portion  74  of the primary fluid chamber  54  decreases in volume. As this change in volume occurs, the fluid  62  is forced from the first portion  74  into the second portion  76  through the fluid passage  78 . The flow rate of the fluid  62  through the fluid passage  78  regulates the damping capacity of the damper assembly  42 . 
         [0018]    The rod  44  includes an annular wall  80 . The annular wall  80  extends along the longitudinal axis  46 , and defines a first expansion chamber  82  and a second expansion chamber  84 . Both of the first expansion chamber  82  and the second expansion chamber  84  extend along the longitudinal axis  46 . The first expansion chamber  82  extends between the first end  48  of the rod  44  and the piston  72 . The second expansion chamber  84  extends between the second end  50  of the rod  44  and the piston  72 . The first expansion chamber  82  is generally disposed within the first portion  74  of the primary fluid chamber  54 , and the second expansion chamber  84  is generally disposed within the second portion  76  of the primary fluid chamber  54 . However, it should be appreciated that a portion of the first expansion chamber  82  and the second expansion chamber  84  may extend outward beyond the first portion  74  and the second portion  76  of the primary fluid chamber  54  respectively. 
         [0019]    The annular wall  80  of the rod  44  further defines a first expansion port  86  and a second expansion port  88 . The first expansion port  86  extends radially through the annular wall  80  of the rod  44  to connect the first expansion chamber  82  and the primary fluid chamber  54  in fluid communication. The second expansion port  88  extends radially through the annular wall  80  of the rod  44  to connect the second expansion chamber  84  and the primary fluid chamber  54  in fluid communication. As shown in  FIG. 2 , the first expansion port  86  connects the first portion  74  of the primary fluid chamber  54  and the first expansion chamber  82  in fluid communication, and the second expansion port  88  connects the second portion  76  of the primary fluid chamber  54  and the second expansion chamber  84  in fluid communication. However, as shown in  FIG. 3 , the first expansion port  86  may alternatively connect the first portion  74  of the primary fluid chamber  54  and the second expansion chamber  84  in fluid communication, and the second expansion port  88  may alternatively connect the second portion  76  of the primary fluid chamber  54  and the first expansion chamber  82  in fluid communication. 
         [0020]    A first pressurized gas device  90  is disposed within the first expansion chamber  82 , and a second pressurized gas device  92  is disposed within the second expansion chamber  84 . The first pressurized gas device  90  is compressible in response to an increase in pressure within the first expansion chamber  82 . The second pressurized gas device  92  is compressible in response to an increase in pressure within the second expansion chamber  84 . The first pressurized gas device  90  and the second pressurized gas device  92  may each include any suitable compressed gas device capable of compressing in response to an increase in fluid pressure of the fluid  62  and expanding in response to a decrease in fluid pressure of the fluid  62 , while maintaining separation between the compressed gas and the fluid  62 . 
         [0021]    As the fluid  62  heats during use, the fluid pressure of the fluid  62  within the primary fluid chamber  54  increases. As the fluid pressure increases, the fluid  62  may seep into the first expansion chamber  82  and/or the second expansion chamber  84  through the first expansion port  86  and the second expansion port  88 , thereby compressing the first pressurized gas device  90  and/or the second pressurized gas device  92 . Accordingly, the first expansion chamber  82  and the second expansion chamber  84  act as an overflow chamber to accommodate expansion of the fluid  62  during use, thereby preventing damage to the first cap bearing seal  58  and/or the second cap bearing seal  60 , and leakage of the fluid  62  from the primary fluid chamber  54 . As the fluid  62  cools, thereby decreasing the fluid pressure, the first pressurized gas device  90  and/or the second pressurized gas device  92  may then expand, forcing the fluid  62  within the first expansion chamber  82  and the second expansion chamber  84  back into the first portion  74  and the second portion  76  of the primary fluid chamber  54 . 
         [0022]    As shown in  FIG. 2 , the first pressurized gas device  90  and the second pressurized gas device  92  may include any suitable device. For example, as shown in  FIG. 2 , the first pressurized gas device  90  includes a first seal  94  moveably disposed within the first expansion chamber  82 . The first seal  94  divides the first expansion chamber  82  to define a first gas portion  96  and a first fluid portion  98 . The first seal  94  is configured for sealing between the first gas portion  96  and the first fluid portion  98 . The first pressurized gas device  90  further includes a valve  100  disposed at the first end  48  of the rod  44 , and configured for controlling a pressurized gas within the first gas portion  96  of the first expansion chamber  82 . The valve  100  may include but is not limited to a shcrader valve or other similar device. Accordingly, pressurized gas may be injected into the first gas portion  96  through the valve  100  to pressurize the first gas portion  96  between the valve  100  and the first seal  94 , thereby forming the first pressurized gas device  90 . 
         [0023]    As shown in  FIG. 2 , the second pressurized gas device  92  includes a second seal  102  moveably disposed within the second expansion chamber  84 . The second seal  102  divides the second expansion chamber  84  to define a second gas portion  104  and a second fluid portion  106 . The second seal  102  is configured for sealing between the second gas portion  104  and the second fluid portion  106 . The second pressurized gas device  92  further includes a valve  100  disposed at the second end  50  of the rod  44 , and configured for controlling a pressurized gas within the second gas portion  104  of the first expansion chamber  82 . The valve  100  may include but is not limited to a shcrader valve or other similar device. Accordingly, pressurized gas may be injected into the second gas portion  104  through the valve  100  to pressurize the second gas portion  104  between the valve  100  and the second seal  102 , thereby forming the second pressurized gas device  92 . 
         [0024]    Referring to  FIG. 3 , the first pressurized gas device  90  and the second pressurized gas device  92  are shown each including a plurality of pressurized gas filled spheres  108 . A first end plug  110  is disposed within the first expansion chamber  82  at the first end  48  of the rod  44  to seal the first expansion chamber  82  and secure the gas filled spheres  108  within the first expansion chamber  82 . A second end plug  112  is disposed within the second expansion chamber  84  at the second end  50  of the rod  44  to seal the second expansion chamber  84  and secure the gas filled spheres  108  within the second expansion chamber  84 . It should be appreciated that the first pressurized gas device  90  and the second pressurized gas device  92  may include other embodiments, including but not limited to gas filled flexible cylindrical tubes or some other similar structure. 
         [0025]    While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.