LIQUID COOLED BRAKE

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

BACKGROUND

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

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.

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.

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.

The fluid flow passage may be integrally formed with the rim.

In one aspect, substantially all of the annular rim and the fluid flow passage can be formed of the friction material.

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.

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.

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.

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.

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.

The valve can be responsive to activation of a vehicle pedal to divert fluid to the brake shoe.

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.

Alternately, the valve can be fluidically coupled in parallel with the passenger compartment heater

BRIEF DESCRIPTION OF THE DRAWING

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:

FIG. 1 is a side elevational view of one aspect of a liquid cooled vehicle brake;

FIG. 2 is a cross-sectional view generally taken along line 2-2 in FIG. 1;

FIG. 3 is a diagrammatic side elevational view of another aspect of a liquid cooled brake;

FIG. 4 is a cross-sectional view generally taken line 4-4 in FIG. 3;

FIG. 5 is a perspective view of another aspect of a liquid cooled brake;

FIG. 6 is a cross-sectional view generally taken along 6-6 in FIG. 5;

FIG. 7 is a cross-sectional view, similar to FIG. 6, but depicting another aspect of a liquid cooled brake;

FIG. 8 is a cross-sectional view, similar to FIGS. 6 and 7, but depicting yet another aspect of a liquid cooled brake;

FIG. 9 is a side elevational view of another aspect of a liquid cooled vehicle brake;

FIG. 10 is a cross sectional view generally taken along line 10-10 in FIG. 9;

FIG. 11 is a partial front perspective view of the liquid cooled vehicle brake shown in FIG. 9;

FIG. 12 is a partial front elevational view of a modification to the liquid brake shown in FIG. 11;

FIG. 13 is a cross sectional view, similar to FIG. 10, but showing another aspect of a liquid cooled vehicle brake;

FIG. 14 is a pictorial representation of one aspect of a liquid cooled brake control system; and

FIG. 15 is pictorial representation of another aspect of a liquid cooled brake control system.

DETAILED DESCRIPTION

Referring now to the FIGS. 1-15 of the drawing, various aspects of a liquid cooled vehicle brake system are depicted.

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.

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.

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.

Connections to a fluid flow system are provided to the coolant passage 40 as described hereafter.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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 222A and 222B which respectively flow to the diverter valve 232 and the heater core 220.

The outlets of the diverter valve 232 and heater core 220 are coupled to sub-conduit 236A and 236B, respectively which tee together then flow into the brake line fluid flow conduit 236.

Claims

1. A vehicle brake comprising: a brake shoe having an annual rim carrying a layer of a brake friction material on a radially outer surface; anda 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 of brake friction material engages a rotating brake member.

2. The brake of claim 1 wherein the fluid passage comprises: a web extending radially inward from the inner surface of the rim; andthe fluid flow passage formed through the web.

3. The brake of claim 1 wherein the fluid flow passage comprises: a pair of spaced webs, each extending radially inward from the inner surface of the rim; anda 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.

4. The brake of claim 1 wherein: the fluid flow passage is integrally formed with the rim.

5. The brake of claim 1 wherein substantially all of the annular rim and the fluid flow passage are formed of the brake friction material.

6. The brake of claim 1 further comprising: a heat conductive member disposed within the layer of brake friction material and coupled in heat transfer relationship with the rim.

7. The brake of claim 1 further comprising: a plurality of heat conductive members disposed within the layer of brake friction material and coupled in heat transfer relationship with the rim.

8. The brake of claim 6 wherein the heat conductive member comprises: at least one body formed of a high thermal conductive material.

9. The brake of claim 8 further comprising: a heat radiator member coupled in heat transfer relationship with the rim, the heat radiator member disposed in the fluid flow passageway.

10. The brake of claim 9 further comprising: a heat conductive member disposed with the layer of brake friction material, the heat conductive member axially aligned with the heat radiator member.

11. In a vehicle having an engine having a coolant flow passage, a radiator, and the brake having a brake shoe, the improvement comprising: radiator having an inlet and outlet;the engine and the radiator coupled in a first coolant flow loop between a coolant passage in the engine and the radiator;a second fluid flow loop coupling the engine to a vehicle passenger compartment heater having an inlet and an outlet;the brake shoe having an annual 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 of brake friction material engages a rotating brake member;a brake fluid flow loop fluidically coupled with the second fluid flow loop; anda valve 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.

12. The improvement of claim 11 wherein: the valve is responsive to activation of a vehicle brake pedal.

13. The improvement of claim 11 further comprising: a pressure switch 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.

14. The improvement of claim 11 further comprising: the valve fluidically coupled in parallel with the passenger compartment heater.