Abstract:
A fluid cooled vehicle brake includes a fluid flow passageway disposed in fluid communication with a brake shoe rim carrying a layer of friction material. High thermal conductive members may be disposed within the layer of friction material to conduct heat to the rim. Heat radiator members are mounted within the coolant passageway. A brake fluid flow control includes a diverter valve responsive to brake pedal activation to divert fluid flow from the vehicle heater fluid flow loop to the brake shoe.

Description:
[0001]    This application claims priority benefit to the filing date of co-pending U.S. Provisional Patent Application Ser. No. 61/224,711, for “Liquid Cooled Brake”, filed Jul. 10, 2009 in the name of Darrel Sand, the entire contents of which are incorporated herein in its entirety. 
     
    
     BACKGROUND 
       [0002]    It is known in the field of vehicle brakes to provide liquid cooling of the brake lining in order to minimize the brake wear and to maintain maximum braking power. Numerous attempts have been made to provide liquid coolant flow to the vehicle brake shoe. It is believed that further improvements can be made to liquid cooled brakes. 
       SUMMARY 
       [0003]    A vehicle brake includes a brake shoe having an annular rim carrying a layer of a brake friction material on a radially outer surface. A fluid flow passage is carried on a radially inner surface of the rim for circulating fluid past the rim to remove heat from the layer of brake friction material when the layer of brake friction material engages a rotating brake member. 
         [0004]    The fluid passage includes a web extending radially inward from the inner surface of the rim, with the fluid flow passage formed through the web. 
         [0005]    The fluid flow passage may include a pair of spaced webs, each extending radially inward from the inner surface of the rim and a wall closing radially inner ends of the first and second webs to form a closed interior defining the fluid flow passage between opposite ends of the web. 
         [0006]    The fluid flow passage may be integrally formed with the rim. 
         [0007]    In one aspect, substantially all of the annular rim and the fluid flow passage can be formed of the friction material. 
         [0008]    In another aspect, a heat conductive member is disposed within the layer of brake friction material and coupled in heat transfer relationship with the rim. 
         [0009]    A plurality of heat conductive members maybe disposed within the layer of brake friction material and coupled in heat transfer relationship with the rim. The heat conductive member is at least one body formed of a high thermal conductive material. 
         [0010]    A heat radiator member can be coupled in heat transfer relationship with the rim, and disposed in the fluid flow passageway. A heat conductive member can be disposed with the layer of brake friction material, and axially aligned with the heat radiator. 
         [0011]    In another aspect, a vehicle has an engine having a coolant flow passage, a radiator, and a brake having a brake shoe. The radiator has an inlet and outlet. The engine and the radiator are coupled in a first coolant flow loop between a coolant passage in the engine and the radiator. A second fluid flow loop couples the engine to a vehicle passenger compartment heater having an inlet and an outlet. The brake shoe has an annular rim carrying a layer of a brake friction material on a radially outer surface, and a fluid flow passage carried on a radially inner surface of the rim for circulating fluid past the rim to remove heat from the layer of brake friction material when the layer friction material engages a rotating brake member. 
         [0012]    A brake fluid flow loop is fluidically coupled with the second fluid flow loop and a valve is coupled between the second fluid flow loop and the brake fluid flow loop to selectively divert fluid from the second loop through the fluid flow passage in the brake shoe. 
         [0013]    The valve can be responsive to activation of a vehicle pedal to divert fluid to the brake shoe. 
         [0014]    A pressure switch can be coupled to the brake fluid flow loop, the pressure switch closing the brake fluid flow loop to fluid flow at a selected pressure to prevent over-pressure in the brake fluid flow loop. 
         [0015]    Alternately, the valve can be fluidically coupled in parallel with the passenger compartment heater 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0016]    The various features, advantages and other uses of the present liquid cool brake will become more apparent by referring to the following detailed description and drawing in which: 
           [0017]      FIG. 1  is a side elevational view of one aspect of a liquid cooled vehicle brake; 
           [0018]      FIG. 2  is a cross-sectional view generally taken along line  2 - 2  in  FIG. 1 ; 
           [0019]      FIG. 3  is a diagrammatic side elevational view of another aspect of a liquid cooled brake; 
           [0020]      FIG. 4  is a cross-sectional view generally taken line  4 - 4  in  FIG. 3 ; 
           [0021]      FIG. 5  is a perspective view of another aspect of a liquid cooled brake; 
           [0022]      FIG. 6  is a cross-sectional view generally taken along  6 - 6  in  FIG. 5 ; 
           [0023]      FIG. 7  is a cross-sectional view, similar to  FIG. 6 , but depicting another aspect of a liquid cooled brake; 
           [0024]      FIG. 8  is a cross-sectional view, similar to  FIGS. 6 and 7 , but depicting yet another aspect of a liquid cooled brake; 
           [0025]      FIG. 9  is a side elevational view of another aspect of a liquid cooled vehicle brake; 
           [0026]      FIG. 10  is a cross sectional view generally taken along line  10 - 10  in  FIG. 9 ; 
           [0027]      FIG. 11  is a partial front perspective view of the liquid cooled vehicle brake shown in  FIG. 9 ; 
           [0028]      FIG. 12  is a partial front elevational view of a modification to the liquid brake shown in  FIG. 11 ; 
           [0029]      FIG. 13  is a cross sectional view, similar to  FIG. 10 , but showing another aspect of a liquid cooled vehicle brake; 
           [0030]      FIG. 14  is a pictorial representation of one aspect of a liquid cooled brake control system; and 
           [0031]      FIG. 15  is pictorial representation of another aspect of a liquid cooled brake control system. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    Referring now to the  FIGS. 1-15  of the drawing, various aspects of a liquid cooled vehicle brake system are depicted. 
         [0033]    Generally, as shown in  FIGS. 1 and 2 , a typical vehicle brake assembly, such as a vehicle brake assembly used in automobiles and trucks, includes at least one moveable brake member, such as a brake shoe  20 , which engages a rotating brake member, such as a brake drum  29 . The brake shoe  20  is formed with an arcuate rim  22 , typically of metal, which has a radially inward facing surface  24  and a radially outward facing surface  26 . A layer of a brake friction material  28  is securely fixed or bonded to the outer surface  26  of the rim  22 . The layer of friction material  28  is designed to engage the brake drum  29 . 
         [0034]    A coolant fluid flow passageway  31  includes an arcuate web  30  extending intermediately between opposed side edges of the radially inward facing surface  24  of the rim  22 . The web  30  has a thin, flange-like shape and can be integrally formed as part of the rim  22  or fixedly joined to the rim  22  by welding, mechanical fasteners, etc. The web  30  adds stiffness to the arcuate rim  22  to resist the forces encountered during movement of the brake shoe  20  into frictional engagement with the rotating vehicle brake drum  29 . 
         [0035]    According to a first aspect, a coolant passage  40  is formed in fluid flow contact or communication with the inner surface  24  of the rim  22  at a location on the inner surface  24  where the maximum temperature during braking is encountered. The coolant passage  40  extends completely through the web  30  between one side of the web  30  and the opposite side of the web  30 . The coolant passage  40  may have any arcuate length and can be centered at the arcuate center of the rim  22  where maximum braking temperatures are typically encountered. For example, the passage  40  is in the form of a lateral bore  41  formed intermediately between the arcuate ends of the web  30 . 
         [0036]    Connections to a fluid flow system are provided to the coolant passage  40  as described hereafter. 
         [0037]    Another aspect of the liquid cooled brake is shown in  FIGS. 3 and 4 . In this aspect, the brake shoe  20  and coolant passage  40  are constructed in the same manner as described above and shown in  FIG. 1 . In this aspect, the opposite side edges of the coolant passage  40  are closed off and covered by the gussets  42  and  44 . Each gusset  42  and  44  has an overall length, width and shape to close off one entire exposed surface or opening of the coolant passage  40  when the gusset  42  or  44  is fixedly mounted to the brake shoe web  30  by means of welding, mechanical fasteners, such as rivets for example, etc. 
         [0038]    At least one of the gussets  42  or  44 , with gusset  42  being shown by way of example, has a first, inlet aperture  46  and a second, outlet aperture  48  typically located at opposite ends of the gusset  42 . Fluid connectors are fixedly mounted in each aperture  46  and  48  to provide fluid flow through the inlet  46  into and through the fluid passage  40  to the outlet  46  for maximum heat transfer from the brake shoe  20 . The fluid connectors can be any connection suitable for fluidically coupling flexible hoses or rigid pipes to the inlet and outlet ends of the passageway  40 , such as pipe unions, quick connectors, etc. 
         [0039]    Referring now to  FIGS. 5 and 6 , there is depicted yet another aspect of a brake shoe  50  which is constructed similarly to the brake shoe  20  described above and shown in  FIGS. 1-4  in that brake shoe  50  includes an arcuate rim  52  having a first radially inward extending inner surface  54  and an opposed, second radially outward facing, outer surface  56 . A layer of brake friction material  58  is fixedly mounted on the outer surface  56 . 
         [0040]    The brake shoe  50  includes two spaced webs  60  and  62 . Radial inward edges  64  and  66  of the first and second web  60  and  62 , respectively, are closed off by an inner wall or gusset  68  which can be joined to the webs  60  and  62  by welding, mechanical fasteners, or any other joining technique suitable for use in a vehicle brake application. 
         [0041]    The webs  60  and  62  and the inner wall  68  form a coolant passage  70  adjacent to the rim  52  which extends from an inlet  67  at one end of the webs  60  and  62  to an outlet  69  at the opposite end of the webs  60  and  62 . Fluid connectors are mounted to the inlet  67  and the outlet  69 . The coolant passage  70  places the liquid coolant flow at the longitudinal center of the rim  52  and the brake friction lining material  58  which is exposed to the highest braking temperature. The distance between the outer surface of the layer of braking material  58  and the liquid coolant in the passage  70  is minimized so as to maximize heat transfer efficiency. 
         [0042]    The dual webs  60  and  62  and the inner endwall  68  may also be implemented as an integral part of a cast or molded brake shoe  76  are shown in  FIG. 7 . In this aspect, the brake shoe  70  is formed of a one piece molded or cast body having a rim portion  78  and first and second webs  80  and  82  extending radially inward from an inner surface  84  of the rim portion  78 . A brake lining  86  formed of a friction material is fixedly mounted on an outer surface  88  of the rim portion  78 . An inner wall  90  is fixed to the radial inner ends of the ribs  80  and  82  to close off the interior space between the webs  80  and  82  and the rim portion  78  to form a coolant passage  82  extending between opposite ends of the webs  80  and  82 . Fluid connectors are coupled to the opposite ends of the coolant passage  82 . 
         [0043]    In the aspect shown in  FIG. 8 , the brake shoe  100  is a one piece cast brake shoe which includes an integral one piece unitary body formed of a brake friction material thereby combining a rim portion  102 , an outer portion of brake friction material  104 , and first and second inner webs  106  and  108  into a unitary body. The radial inner ends of the webs  106  and  108  are again closed off by an inner wall  110  to form a coolant passage  112  extending between opposite ends of the webs  106  and  108 . Fluid connectors are coupled to the opposite ends of the coolant passage  112 . 
         [0044]    A brake shoe  110  shown in  FIGS. 9 ,  10 , and  11  includes an arcuate rim  112  having a layer  114  of a brake lining or friction material bonded or otherwise securely mounted on an outer surface  116  of the rim  112 . A closed web  118  similar to the webs shown in any of  FIGS. 1-8 , extends radially inward from an inner surface  120  of the rim  112 . 
         [0045]    In this aspect, heat conductive means in the form of one or more heat conductive members, with three circumferentially spaced heat conductive members  124 ,  126 , and  128  being shown by way of example only, are mounted within the layer  114  of brake friction material. The heat conductive members  124 ,  126 , and  128  may be sintered or integrally cast as part of the friction material layer  114  or fixedly mounted in the layer  114  after the layer  114  has been bonded or otherwise mounted to the outer surface  116  of the rim  112  by forming bores in the layer  114  and then inserting and fixedly securing each of the heat conductive members  124 ,  126  and  128  in the layer  114 . 
         [0046]    The heat conductive members  124 ,  126 , and  128  are preferably formed of a highly thermal or heat conductive material, such as copper, copper alloy, etc. 
         [0047]    The radially outer end or surface of each of the heat conductive members  124 ,  126 , and  128  may be covered by an outer portion of the layer  114  of brake friction material or exposed through the outer surface of the layer  114  as shown in  FIGS. 9 ,  10 , and  11 . 
         [0048]    The heat conductive members  124 ,  126 , and  128  function to rapidly transfer heat generated during vehicle braking in the surrounding wheel drum, not shown, and in the brake friction lining or layer  114  to the rim  112  where the heat is transferred to the liquid coolant flowing through the flow passage  121  formed between the one or more webs, with two webs  118  and an inner wall  119  being shown in  FIG. 10  by way of example only. 
         [0049]      FIGS. 9 and 10  also depict another feature of this aspect of the liquid cooled brake in which one or more heat radiators or fins  134  are fixed in thermal flow communication with the rim  122  by means of welding, integral casting, etc. Each heat radiator or fin  134  projects into the coolant flow passage  121  so as to expose a large surface area for the heat transferred through the heat conductive members  124 ,  126 , and  128  in the rim  122  to the coolant flow in the passage  121  for efficient heat removal and brake cooling. 
         [0050]    The heat radiator or fin  134  is shown in  FIG. 9 , may have any shape or length. It is desirable for efficient heat transfer for the heat radiator or fin  134  to have a length that extends at least across the entire arcuate expanse of the heat conductive members  124 ,  126 , and  128 . 
         [0051]    The heat conductive members  124 ,  126 , and  128  may have other shapes, lengths, and widths as shown, by way of example only, in  FIG. 12 . In this modification, a single heat conductive member  138  is provided in the form of an elongated strip substantially centered about the circumferential center of the brake lining  114  where breaking temperatures are at a maximum. 
         [0052]    It will be understood that the heat conductive members  124 ,  126  and  128  or the heat conductive member  138  may be used independently and separately from the heat radiator or fin  134 . As shown in  FIG. 13 , the heat radiator or fin  134  may also be used independently of the heat conductive members  124 ,  126  and  128  or  138 . 
         [0053]    A brake coolant flow control system is depicted in  FIG. 14 . An internal combustion engine  210  is coupled to a radiator  212  by means of a first coolant flow loop formed of a first conduit  214  coupling the engine coolant flow passage to the top portion of the radiator  212  and a second conduit  216  connecting the bottom of the radiator  216  to the engine coolant flow passage through the water pump  218 . 
         [0054]    The engine  210  is also fluidically coupled by a second fluid flow loop to a passenger compartment heater  220 . The second fluid flow loop includes a first conduit  222  coupled between the engine  210  and an inlet of the heater  220 , and a second conduit  224  coupled between an outlet of the heater  220  and a second conduit  216  of the engine/radiator fluid flow loop. 
         [0055]    A brake coolant flow loop is formed of a first conduit  230  branching off of the first heater conduit  222 . The first conduit  230  is coupled to a diverter valve  232 , such as a normally closed solenoid operated valve. A solenoid coil receives an input signal, as described hereafter, to cause the diverter valve,  232  to open thereby allowing a coolant flow through the brake coolant flow passages  40 ,  70 ,  92 ,  212  or  221  as shown in various aspects of the liquid cooled brake described above. 
         [0056]    The input signal to the coil of the diverter valve  232  maybe a 12 volt D.C. signal from the vehicle brake stoplight or the brake pedal actuation switch as shown by a signal line  234 . 
         [0057]    The outlet of the diverter valve  232  is coupled to an inlet conduit  236  which is coupled to the inlet of the brake coolant passages  40 ,  70 ,  92 ,  112 , or  221  shown in the various aspects described above. 
         [0058]    The outlet of the liquid brake cooling passage is coupled to a conduit  238  which is connected to the first conduit  214  of the engine/radiator coolant flow loop so as to return the heated coolant fluid from the brakes to the top portion of the radiator  212 . 
         [0059]    A safety feature is also provided in the brake coolant flow circuit shown in  FIG. 14 . A pressure switch  240  is coupled to the brake fluid flow conduit  236 . The pressure switch  240  can be a normally opened pressure switch which is adapted to move to a closed position at a certain detected fluid pressure, such as 10 psi, for example. When the pressure switch  240  is open, since the fluid pressure is under 10 psi indicative of good coolant flow, an output signal from the pressure switch  240  can be used to turn on a coolant supply indicator, such as a light  242  located on the vehicle instrument panel, to provide an indication to the vehicle driver that the brake coolant system is operating. When the pressure switch  240  detects a coolant flow pressure in the conduit  236  greater than the set pressure, such as greater than 10 psi, the output signal from the pressure switch  240  can be used to generate an error signal depicted by reference number  244  which can be supplied to the vehicle instrument panel or the vehicle control computer to provide an operational warning that the brake coolant is experiencing an overpressure condition. 
         [0060]    Referring now to  FIG. 15 , there is depicted another aspect of a liquid cooled brake coolant flow control circuit. The normally closed diverter valve  232 , in this aspect, is fluidically coupled in parallel with the passenger heater core  220  in the event that the heater core  220  becomes plugged or experiences reduced fluid flow over time. The conduit  222  from the engine branches into sub-conduits  222 A and  222 B which respectively flow to the diverter valve  232  and the heater core  220 . 
         [0061]    The outlets of the diverter valve  232  and heater core  220  are coupled to sub-conduit  236 A and  236 B, respectively which tee together then flow into the brake line fluid flow conduit  236 .