Abstract:
A method of filling a brake system for a motorcycle including a brake system having a master cylinder assembly and a caliper assembly. The master cylinder assembly includes a housing and a cover coupled to the housing to define an enclosed reservoir. The caliper assembly includes a fluid passageway and a fitting adjustable to selectively provide fluid communication with the fluid passageway. The motorcycle also includes a brake line coupled between the master cylinder assembly and the caliper assembly to fluidly connect the reservoir and the fluid passageway. The method also includes substantially evacuating the reservoir, brake line and fluid passageway, coupling a fluid source to the fitting, passing fluid from the fluid source through the fitting, and filling the reservoir, brake line, and fluid passageway with the fluid passed through the fitting from the fluid reservoir.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a divisional application of co-pending U.S. patent application Ser. No. 11/169,324, filed Jun. 28, 2005, the entire contents of which are hereby incorporated by reference herein. 
     
    
     BACKGROUND  
       [0002]     The present invention relates to brake systems for motorcycles, and more particularly to methods of filling brake systems for motorcycles.  
         [0003]     Typical motorcycle brake systems include a master cylinder assembly, a caliper assembly, and a brake line coupling the master cylinder assembly to the caliper assembly. Actuation of a hand lever of the master cylinder assembly pressurizes brake fluid through the brake lines and into the caliper assembly to press brake pads of the caliper assembly against a wheel rotor to slow or stop the rotation of the wheel. The master cylinder assembly includes a reservoir that contains the brake fluid supplied to the brake system.  
         [0004]     For the brake system to work properly, the entire brake system must be filled with the brake fluid, except for some allowable air at the top of the reservoir. It is known to fill the brake system with fluid by removing a cover of the master cylinder assembly, filling the reservoir with brake fluid, opening a bleeder fitting located on the caliper assembly, pumping the brake lever until the fluid exits the bleeder fitting, and adding fluid to the reservoir as needed. When full, the cover is replaced and the bleeder fitting is closed. This process is time consuming and is not desirable for mass production.  
         [0005]     In production, the fill process is performed after the brake system is attached to the motorcycle. Another known fill process used in this environment is to remove the cover, attached an adapter to the reservoir, use the adapter to evacuate the air from the brake system through the reservoir, use the adapter to fill the brake system with brake fluid through the reservoir, remove the adapter exposing the fluid within the reservoir, and replacing the cover onto the housing to seal the reservoir. The bleeder fitting remains closed throughout the entire process.  
         [0006]     Other processes fill brake fluid from the bleeder fitting. In this process, the cover is removed, the bleeder fitting is opened, an adapter is attached to the bleeder fitting, the adapter passes brake fluid through the bleeder fitting to fill the brake system, the cover is replaced, the adapter is removed, and the bleeder fitting is closed.  
         [0007]     These known fill processes generally have used either Dot 3, Dot 4, or Dot 5 brake fluid. Due to fluid characteristics required by modern antilock braking systems, Dot 4 brake fluid is becoming more common. Dot 4 brake fluid is more corrosive than Dot 5 brake fluid and has the potential to damage the cosmetic appearance of certain components of the motorcycle, such as the painted tank, if spilled or splashed. Because of this potential for cosmetic damage, the known fill processes that fill the brake system with the cover removed from the housing are disadvantageous. In addition, it is time consuming to remove and replace the cover during the fill process increasing process cycle times and the manufacturing expense of the motorcycle.  
       SUMMARY  
       [0008]     The present invention provides a method of filling a motorcycle brake system having a master cylinder assembly and a caliper assembly. The master cylinder assembly includes a housing and a cover coupled to the housing to define an enclosed reservoir. The caliper assembly includes a fluid passageway and a bleeder fitting adjustable to selectively provide fluid communication with the fluid passageway. The motorcycle also includes a brake line coupled between the master cylinder assembly and the caliper assembly to fluidly connect the reservoir and the fluid passageway. The method includes substantially evacuating the reservoir, brake line and fluid passageway, coupling a fluid source to the fitting, passing fluid from the fluid source through the fitting, and filling the reservoir, brake line, and fluid passageway with the fluid passed through the fitting from the fluid reservoir.  
         [0009]     The present invention also provides a master cylinder assembly for a brake system of a motorcycle. The master cylinder assembly includes a housing, a cover, and a sight glass. The cover is coupled to the housing to define a reservoir adapted to contain a fluid. The sight glass is received within an aperture of the cover and is adapted to indicate the level of the fluid within the reservoir. The sight glass includes a top portion, a bottom portion, and a middle portion between the top and bottom portions. The top and bottom portions each include a perimeter sized to be received within the aperture and to seal the reservoir, and the middle portion includes a reduced perimeter relative to the top and bottom portions. The sight glass is movable between raised and lowered positions. The bottom portion is received within the aperture and seals the reservoir in the raised position. The top portion is received within the aperture and seals the reservoir in the lowered position. The middle portion allows fluid flow through the aperture when the sight glass is moved from the raised position to the lowered position.  
         [0010]     Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a perspective view of a motorcycle, illustrating a brake system of the motorcycle embodying the present invention.  
         [0012]      FIG. 2  is a partially exploded view of a portion of a steering assembly of the motorcycle shown in  FIG. 1 , illustrating a master cylinder assembly and brake line of the brake system.  
         [0013]      FIG. 3  is a partially exploded view of another portion of the steering assembly shown in  FIG. 1 , illustrating a caliper assembly of the brake system.  
         [0014]      FIG. 4  is an exploded view of the master cylinder assembly shown in  FIG. 2 .  
         [0015]      FIG. 5  is a cross section view of the master cylinder assembly taken along line  5 - 5  of  FIG. 4 , illustrating the master cylinder assembly in the assembled condition with a sight glass of the master cylinder assembly in the raised position.  
         [0016]      FIG. 6  is a view similar to  FIG. 5 , illustrating a reservoir of the master cylinder assembly filled with a fluid.  
         [0017]      FIG. 7  is a view similar to  FIG. 6 , illustrating the sight glass between the raised and lowered positions.  
         [0018]      FIG. 8  is a view similar to  FIG. 7 , illustrating the sight glass in the lowered position.  
         [0019]      FIG. 9  is a cross section view of an adapter used to couple to a bleeder fitting of the caliper assembly of  FIG. 3 , illustrating the adapter in an unclamped position.  
         [0020]      FIG. 10  is a view similar to  FIG. 9 , illustrating the adapter in a clamped position. 
     
    
       [0021]     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.  
       DETAILED DESCRIPTION  
       [0022]      FIG. 1  illustrates a motorcycle  10  including a frame  12 , a steering assembly  14  pivotably mounted to a forward portion of the frame  12 , a front wheel  16  rotatably mounted to an end of the steering assembly  14 , a rear wheel  18  rotatably mounted to a swing arm  20  that is pivotably connected to a rearward portion of the frame  12 , and an engine/transmission assembly  22  mounted to the frame  12  and operably coupled to the rear wheel  18 . The front wheel  16  includes a front rotor  24  and the rear wheel  18  includes a rear rotor  26 . A seat  28  is coupled to the frame  12  above the rear wheel  18  to support an operator. The steering assembly  14  includes a fork  30 , handlebars  32 , and controls, such as a throttle grip  34 , coupled to the handlebars  32 . The operator manipulates the controls to power the engine/transmission assembly  22 , drive the rear wheel  18 , and propel the motorcycle  10 . The operator maneuvers the handlebars  32  to pivot the steering assembly  14  and front wheel  16  to steer the motorcycle  10  while the motorcycle  10  is moving.  
         [0023]     The motorcycle  10  also includes a braking system  36  including a front braking assembly and a rear braking assembly. The front braking assembly includes a master cylinder assembly  42  coupled to the handlebars  32 , a caliper assembly  44  coupled to the fork  30 , and a brake line  46  coupled between the master cylinder assembly  42  and caliper assembly  44 . The rear braking assembly includes a master cylinder assembly coupled to a lower portion of the frame  12 , a caliper assembly  50  coupled to the swing arm  20 , and a brake line (not shown) coupled between the master cylinder assembly and caliper assembly  50 .  
         [0024]     With respect to the applicability of this invention, the front and rear braking assemblies are substantially similar to each other and therefore, only the front braking assembly will be discussed below in detail. It should be noted that one of ordinary skill in the art would readily understand how the invention, as described below with respect to the front braking assembly, could also be applied to the rear braking assembly.  
         [0025]     With reference to  FIGS. 2 and 4 , the master cylinder assembly  42  includes a housing  52  and a cover  54  coupled to the housing  52  that together define a reservoir  56  for brake fluid  58 . Typically, Dot 4 or Dot 5 brake fluid is used. The cover  54  includes a central aperture  60  and a flat annular top surface  62  around the aperture  60 . The annular surface  62  provides a mounting location for an annular warning label  64  indicating proper care instructions and the contents of the reservoir  56 .  
         [0026]     The master cylinder assembly  42  also includes a hourglass-shaped sight glass  66  that provides an external indication of the level of brake fluid  58  within the reservoir  56 . The sight glass  66  includes a top portion  68 , a bottom portion  70 , and a middle portion  72  between the top and bottom portions  68 ,  70 . The top and bottom portions  68 ,  70  each include a larger perimeter than the perimeter of the middle portion  72 . The sight glass  66  is movable between a raised position ( FIGS. 5 and 6 ) where the bottom portion  70  is received within the aperture  60  and seals the reservoir  56  and a lowered position ( FIG. 8 ) where the top portion  68  is received within the aperture  60  and seals the reservoir  56 . The middle portion  72  allows fluid flow through the aperture  60  when the sight glass  66  is moved from the raised position to the lowered position. The top portion  68  includes a top flange  74  that has an increased perimeter from the top portion  68  and that has a tapered top edge  76 . The bottom portion  70  includes a bottom flange  78  that has an increased perimeter from the bottom portion  70 .  
         [0027]     The housing  52  includes a clamp portion  80  that surrounds a portion of the handlebar  32 . A clamp  82  surrounds the opposite portion of the handlebar  32  and is fastened to the clamp portion  80  to secure the housing  52  to the handlebar  32 . The housing  52  also includes a clevis portion  84  including apertures  86 . A hand lever  88  is pivotally connected to the housing  52  by positioning an apertured portion (not shown) of the hand lever  88  within the clevis  84  and inserting a pivot pin  90  through the apertures  86 .  
         [0028]     The master cylinder assembly  42  includes a gasket  92  positioned between the housing  52  and the cover  54 . The gasket  42  includes a perimeter  94 , a central aperture  96 , and a raised boss portion  98  surrounding the aperture  96 . The perimeter  94  is compressed between the cover  54  and the housing  52 , and the raised boss portion  98  extends through the aperture  60  of the cover  54  when the cover  54  and housing  52  are fastened together (See  FIG. 5 ). The gasket  92  also defines a baffled or ribbed portion  100  between the perimeter  94  and the central aperture  96 . The ribbed portion  100  allows the gasket  92  to flex when acted upon by varying pressure differences between the opposite sides of the gasket  92 .  
         [0029]     The housing  52  includes a cavity (not shown) that is in fluid communication with the reservoir  56 , which supplies fluid  58  to the cavity. The housing  52  also includes a brake line port  102  that is in fluid communication with the cavity. One end of the brake line  46  is fluidly coupled to the brake line port  102  to be in fluid communication with the cavity and the reservoir  56 . The master cylinder assembly  42  includes a piston (not shown) that is positioned within the cavity and that is actuable upon pivoting of the hand lever  88 . When the hand lever  88  is pivoted, the piston moves within the cavity to pressurize the fluid  58  and move the fluid  58  through the port  102  and through the brake line  46 .  
         [0030]     As shown in  FIG. 3 , the caliper assembly  44  includes a caliper housing  104  that includes a brake line port  106 , a fitting or bleeder fitting  108 , and an internal fluid passageway (not shown) that fluidly connects the brake line port  106  and the bleeder fitting  108 . The bleeder fitting  108  is selectively adjustable to provide access to the fluid passageway. The fluid passageway is also fluidly connected to multiple cavities (not shown) within the caliper housing  104 . Each cavity houses a caliper piston for movement within the cavity. The caliper assembly  44  also includes two opposite facing brake pads (not shown) that are slidably mounted to the housing  104 . The caliper assembly  44  is mounted to the fork  30  by bolts  110  such that a portion of the front rotor  24  is received within the housing  104  and between the brake pads. The opposite end of the brake line  46  is fluidly coupled to the brake line port  106  to be in fluid communication with the fluid passageways and the cavities. When the fluid  58  is pressurized by the piston in the master cylinder assembly  42 , the pressurized fluid  58  moves through the brake line  46  and fluid passageway to fill the cavities and thereby move the pistons inwardly. This movement of the pistons causes the brake pads to be pressed against the rotor  24  to thereby slow the rotation of the rotor  24  and the front wheel  16  or resist rotation of the rotor  24  and the front wheel  16 .  
         [0031]     The master cylinder assembly  42  is described with reference to  FIGS. 4 and 5 . The warning label  64  is adhered to the annular surface  62  of the cover  54 . Next, the raised boss portion  98  of the gasket  92  is inserted through the aperture  60  of the cover  54 . The sight glass  66  is then inserted through the apertures  60 ,  96  in the cover  54  and the gasket  92  from the bottom side of the cover  54  to a raised position. The tapered edge  76  of the sight glass  66  provides a leading end to facilitate the entrance of the sight glass  66  through the apertures  60 ,  96 . In the raised position, the middle and top portions  72 ,  68  of the sight glass  66  are exposed above the surface of the cover  54 . To protect the sight glass  66  from debris and damage while in the raised position, a cap  112  is pressed over the sight glass  66  and held in place by the interference between the top flange  74  and the inner wall of the cap  112 . The cover  54  and gasket  92  are then fastened to the empty housing  52  by inserting screws (not shown) through the respective apertures in each component. The housing  52  is then attached to the handlebars  32  by fastening the clamp  82  to the clamp portion  80  around the handlebars  32 .  
         [0032]     The filling process of the brake system  36  is described with reference to  FIGS. 5-8 .  FIG. 5  illustrates the assembled master cylinder assembly  42  without brake fluid. The sight glass  66  is in the raised position and the bottom portion  70  creates a seal with the gasket  92  to seal the reservoir  56 . To fill the brake system  36  with brake fluid  58 , an adapter  40  is sealed to the bleeder fitting  108 . The adapter  40 , as shown in  FIGS. 9 and 10 , includes clamped and unclamped positions, and also may be selectively coupled to a vacuum source and a source of brake fluid. The bleeder fitting  108  is then opened, and the adapter  40  is connected to the vacuum source and evacuates fluid (air, moisture, liquid, etc.) from the reservoir  56 , cavity of the housing  52 , brake line  46 , passageway and cavities of the caliper assembly  44 . The sight glass  66  includes a rib  114  between the middle portion  72  and the bottom portion  70 . The rib  114  along with the interference fit between the bottom portion  70  and the gasket  92  resist movement of the sight glass  66  into the reservoir  56  when the system is being evacuated. In other embodiments, the sight glass  66  may not include rib  114 , and the interference fit between the bottom portion  70  and the gasket  92  is sufficient to resist movement of the sight glass  66  into the reservoir. The vacuum can be held and monitored for a period of time to determine if there is any decay over the period of time, which could indicate a leak within the brake system  36 . When the brake system  36  is evacuated, the ribbed portion  100  of the gasket  92  flexes downward caused by the pressure of the air remaining on the top side of the gasket  92 .  
         [0033]     If no decay is detected, the adapter  40  is connected to a source of brake fluid  58  and the fluid  58  is directed from the adapter  40  and into the brake system  36  through the bleeder fitting  108 . The fluid  58  can be introduced for a specific period of time or until a specific pressure is surpassed. The bottom flange  78  and the interference fit between the bottom portion  70  and the gasket  92  resist movement of the sight glass  66  out of the reservoir  56  when the system  36  is being filled. The fluid  58  fills the entire reservoir  56  below the gasket  92 , and the ribbed portion  100  of the gasket  92  returns to approximately its original position ( FIG. 5 ). At this time, the adapter  40  goes into a scavenge mode drawing back a portion of the fluid  58  in the brake system  36  to set the desired level of fluid  58 . The ribbed portion  100  of the gasket  92  again flexes downward slightly as shown in  FIG. 6 .  
         [0034]     Next, the cap  112  is removed from the sight glass  66 , and the sight glass  66  is moved from the raised position to the lowered position. The pushing of the sight glass  66  to the lowered position introduces air into the reservoir  56 . The introduction of air is important because it allows the proper refractory characteristics for the sight glass  66  to properly indicate the level of the fluid  58  within the reservoir  56 . Without the introduction of the air into the reservoir  56 , the sight glass  66  may provide an inaccurate indication of the fluid level. As shown in  FIG. 7 , as the middle portion  72  passes through the apertures  60 ,  96 , a gap  116  is created between the gasket  92  and the middle portion  72  allowing air to vent into the reservoir  56  under the gasket  92 . The air pressure below the gasket  92  equalizes with the air pressure above the gasket  92  and the ribbed portion  100  of the gasket  92  is allowed to return to its original position.  
         [0035]     As shown in  FIG. 8 , the sight glass  66  is moved to the lowered position where the top portion  68  seals against the gasket  92  and seals the reservoir  56 . The top flange  74  resists movement of the sight glass  66  further into the reservoir  56 , and the interference between the top portion  68  and the gasket  92  resists movement of the sight glass  66  out of the reservoir  56 . In this position, the top  118  of the sight glass  66  is exposed and provides a visual indication of the level of the fluid  58  within the reservoir  56 . When full, the entire circular top surface  118  of the sight glass  66  will be darkened. As the fluid level decreases, the circular darkened area of the top surface  118  will become concentrically smaller.  
         [0036]     After the sight glass  66  is moved to the lowered position, the bleeder fitting  108  is closed and the adapter  40  is removed from the bleeder fitting  108 .  
         [0037]     Thus, the invention provides, among other things, a brake system fill process that can fill the brake system without removing the cover of the master cylinder assembly. The ability to fill the brake system while maintaining the cover connected reduces the likelihood of cosmetic damage to the motorcycle caused by spillage of the brake fluid and decreases the process cycle times thereby reducing the cost to manufacture the motorcycle. Various features and advantages of the invention are set forth in the following claims.