WO2005021993A1 - Fluid cooled drum brake system - Google Patents
Fluid cooled drum brake system Download PDFInfo
- Publication number
- WO2005021993A1 WO2005021993A1 PCT/AU2004/001159 AU2004001159W WO2005021993A1 WO 2005021993 A1 WO2005021993 A1 WO 2005021993A1 AU 2004001159 W AU2004001159 W AU 2004001159W WO 2005021993 A1 WO2005021993 A1 WO 2005021993A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- friction material
- fluid
- drum
- inner circumferential
- brake
- Prior art date
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D51/00—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like
- F16D51/10—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as exclusively radially-movable brake-shoes
- F16D51/14—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as exclusively radially-movable brake-shoes fluid actuated
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D51/00—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like
- F16D51/10—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as exclusively radially-movable brake-shoes
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D65/00—Parts or details
- F16D65/02—Braking members; Mounting thereof
- F16D65/04—Bands, shoes or pads; Pivots or supporting members therefor
- F16D65/08—Bands, shoes or pads; Pivots or supporting members therefor for internally-engaging brakes
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D65/00—Parts or details
- F16D65/78—Features relating to cooling
- F16D65/82—Features relating to cooling for internally-engaging brakes
- F16D65/833—Features relating to cooling for internally-engaging brakes with closed cooling system
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D65/00—Parts or details
- F16D65/78—Features relating to cooling
- F16D2065/784—Features relating to cooling the coolant not being in direct contact with the braking surface
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D69/00—Friction linings; Attachment thereof; Selection of coacting friction substances or surfaces
- F16D2069/004—Profiled friction surfaces, e.g. grooves, dimples
Definitions
- the present invention relates to a drum brake system.
- a conventional drum brake system comprises a drum which is fixed to a rotating body such as a hub, and a pair of brake shoes each of which is rotationally fixed and pivotally coupled at one end to a stationary support located within the drum.
- Each shoe has an outer circumferential surface to which is attached a lining of friction material.
- a double acting piston is located between adjacent opposite ends of the shoes for the purposes of causing the shoes to pivot outwardly to bring the friction material into contact with a braking surface on the drum.
- a wet drum brake system is of the same basic design as the conventional dry drum brake system but with the inclusion of a sealed housing which encloses the drum and the shoes, and contains a volume of lubricating fluid such as oil.
- the temperature at the braking drum and shoe interface (the "braking interface") in the region of 70°C to 80°C.
- the temperature generated at the braking interface typically reaches 350°C to 400°C although this range can be exceeded in some instances .
- the present invention relates to a drum brake system.
- a conventional drum brake system comprises a drum which is fixed to a rotating body such as a hub, and a pair of brake shoes each of which is rotationally fixed and pivotally coupled at one end to a stationary support located within the drum.
- Each shoe has an outer circumferential surface to which is attached a lining of friction material.
- a double acting piston is located between adjacent opposite ends of the shoes for the purposes of causing the shoes to pivot outwardly to bring the friction material into contact with a braking surface on the drum.
- a wet drum brake system is of the same basic design as the conventional dry drum brake system but with the inclusion of a sealed housing which encloses the drum and the shoes, and contains a volume of lubricating fluid such as oil .
- the temperature at the braking drum and shoe interface (the "braking interface") in the region of 70°C to 80°C.
- the temperature generated at the braking interface typically reaches 350°C to 400°C although this range can be exceeded in some instances .
- the lubricating oil in the conventional wet braking system does not reduce the temperature at the braking interface to the above-mentioned desired range.
- a seemingly obvious way to address this would be to pump the - 2 - oil of the wet brake system through a radiator or other heat exchanger.
- the volume of oil within the wet brake system is only a fraction of the volume defined by the housing containing the braking system. The remainder of the volume is occupied by air.
- the presence of air creates enormous difficulties in pumping oil through a heat exchanger. In theory, this could be rectified by completely filling the housing with oil. However were this to occur, then it would not be possible to expel the oil between the brake shoes and braking surface during a braking operation thereby drastically reducing stopping power .
- a fluid cooled drum brake system comprising:
- a brake drum having an inner circumferential surface
- each shoe in the set having an outer surface facing the inner circumferential surface, a fluid inlet, a fluid outlet, and one or more fluid flow paths in fluid - 3 - communication between the fluid inlet and the outlet and extending beneath at least a portion of the outer surface and through which a cooling fluid flows;
- an actuator for selectively applying a force to the set of brake shoes to force respective braking surfaces against the friction material .
- a fluid cooled wet drum brake system comprising:
- a drum brake disposed in the housing and having an inner circumferential surface
- each shoe in the set having an outer surface facing the inner circumferential surface, a fluid inlet, a fluid outlet, and one or more fluid flow paths in fluid communication between the inlet and the outlet and extending beneath at least a portion of the outer curved surface through which a cooling fluid flows;
- a layer of friction material attached to one of tge inner circumferential surface and the outer curved surface, the other of the inner circumferential surface and the outer curved surface forming a braking surface; and, - 4 - an actuator for selectively applying a force to the brake shoes to force respective braking surfaces against the friction material .
- the layer of friction material is attached to the inner circumferential surface and the outer surface forms the braking surface.
- the friction material comprises a plurality of pads of friction material disposed about the inner circumferential surface.
- the pads are circumferentially spaced apart from each other.
- the friction material comprises a single ring of friction material attached to the inner circumferential surface.
- a surface of said friction material facing the braking surface is provided with a plurality of grooves .
- the grooves open onto axially opposite edges of the friction material .
- the grooves follow a spiroidal path.
- the set of brake shoes comprises two brake shoes and the actuator selectively applies a force to each of the two brake shoes to urge the braking surfaces into contact with the friction material .
- each brake shoe comprises a first curved plate provided with a plurality of channels on one side and a second curved plate attached to the first curved plate for covering the channels, the covered channels forming the internal fluid flow paths . - 5 -
- each brake shoe is mounted in the drum to slide linearly toward said friction material when the actuator is operated to urge the braking surface into contact with the friction material .
- the actuator operates simultaneously at opposite ends on the brake shoes .
- the actuator comprises a pair of pistons each piston acting between the ends of the brake shoes at respective opposite ends of the brake shoes.
- Figure 1 is a front view of a fluid cooled drum brake system in accordance with the present invention
- Figure 2 is a representation of a pair of brake shoes incorporated in the fluid cooled drum brake system
- Figure 2A is a view of section A-A of the brake shoes depicted in Figure 2;
- Figure 2B is a view of section B-B of the brake shoes depicted in Figure 2 ;
- Figure 3 is a section view of a wet drum brake incorporated in an embodiment of the fluid cooled drum brake system.
- Figure 4 is a front view of a second embodiment of the fluid cooled drum brake system.
- - 6 - Detailed Description of Preferred Embodiments
- an embodiment of the fluid cooled drum brake system 10 in accordance with the present invention comprises a brake drum 12 (see Figure 3) having an inner circumferential surface 14 to which is attached a layer of friction material formed as three circumferentially spaced arcuate sections of friction material 16a-16c (hereinafter referred to generally as “friction material 16") .
- a set of two brake shoes 18a and 18b (hereinafter referred to in general as “brake shoes 18") is rotationally fixed within the drum 12.
- Each brake shoe 18 has: an outer (convexly curved) surface which forms a braking surface 20 facing the friction material 16; a fluid inlet 22 (see Figures 2 and 2A) ; fluid outlet 24; and, a number of fluid flow paths 26 in fluid communication between the fluid inlet 22 and fluid outlet 24 and extending beneath at least a portion of the braking surface 20.
- An actuator 27 in the form of a pair of double-acting hydraulic pistons 28 is provided for selectively applying force to the brake shoes 18 to urge their respective braking surfaces 20 against the friction material 16.
- Each brake shoe 18 is formed with first and second curved plates 30 and 32 of a curvature which is coaxial with the inner surface 14 of the drum 12.
- the curved plate 32 has an outer surface which constitutes the braking surface 20.
- the curved plate 30 is radially inside of the plate 32 and has a radially inner surface 34 to which is coupled the brake shoe web 36.
- the fluid inlet 22 and fluid outlet 24 are formed through the surface 34 of the plate 30 and provide fluid communication to the fluid flow paths 26 which are confined between the curved plates 30 and 32.
- the fluid flow paths 26 are formed as a plurality of parallel channels 38, machine, cast or otherwise formed on - 7 - a radially outer surface 40 of the curved plate 30.
- the channels 38 are separated by parallel spaced-apart walls or ridges 41 that are created in the process of forming the channels 38.
- Opposite ends of the channels 38 lead to common feed channels 42 and 44 which provide fluid communication with the inlet 22 and outlet 24 respectively.
- the fluid flow paths 26 are effectively created by covering the channels 38 with the curved plate 32 and sealing the plate 32 to the plate 30.
- Scrapers 46 typically made from PTFE are provided on each brake shoe 18 at opposite ends of the curved plates 30 and 32.
- the purpose of the scrapers 46 is to wipe lubricating oil from the surface of the friction material 16 when the brake shoes 18 are used in a wet brake system.
- the scrapers 46 are resiliently biased so as to protrude radially beyond the braking surface 20.
- the scrapers 46 will initially contact the friction material 16 to wipe off the lubricating oil.
- the scrapers 46 retract radially inwardly. Further details of the operation and structure of the scrapers 46 can be derived from Applicant's International Publication No. WO 02/23060, the contents of which are incorporated herein by way of reference.
- the shoes 18 and actuator 27 are arranged to ensure that the shoes 18 move linearly toward the friction material 16 rather than move in an arcuate path.
- the webs 36 of the shoes 18 are provided with elongated slots 47 through which guide pins 48 extend.
- the pins 48 are on a stationary mounting plate (not shown, but of a form similar to the stationary plate used in conventional drum brakes to support the brake - 8 - shoes) located within or adjacent the drum 12.
- the actuator 27 operates at opposite ends of the shoes 18 to cause the shoe to slide linearly into contact with the friction material 16. More particularly, respective pistons 28 act between the ends of adjacent shoes 18.
- springs 50 which are coupled between the webs 36 of the shoes 18, slide the shoes 18 linearly toward each other and out of contact with the friction material 16 thereby releasing the brake.
- the springs 50 may be coupled to the webs 36 in any conventional manner including by the provision of hooks 52 on opposite ends of the springs 50 which engage pins 54 extending axially from one side of the webs 36.
- hoses can be attached to the inlet 22 and outlet 24 to couple the fluid flow paths 26 to a cooling circuit which can include a reservoir of cooling fluid such as water or glycol, a pump and if desired or required, a radiator or heat exchanger.
- a cooling circuit which can include a reservoir of cooling fluid such as water or glycol, a pump and if desired or required, a radiator or heat exchanger.
- Embodiment of the drum brake system 10 may be utilised as either a dry brake system or alternately as part of a wet brake system.
- FIG 3 depicts an embodiment of a wet brake system 56 in which the fluid cooled from brake system 10 may be incorporated.
- the wet brake system 56 is in substance the same as the dry brake system illustrated in Figures 1 and 2 but with the addition of an outer sealed housing 58 which contains the drum 12, friction material 16 and brake shoes 18 (not shown) .
- the housing 58 is a stationary - 9 - component and is provided with an opening 60 at one end through which a rotating body in the form of a mounting hub 62 passes .
- the drum 12 is attached to the mounting hub by mounting bolts 64. Thus the drum 12 rotates with the mounting hub 62.
- " Circumferential seals 65 are provided within the housing 58 to form a fluid seal against an outer surface of the hub 62.
- the housing 58 includes a circumferential wall 66 which extends about the outside of the drum 12, and a cover plate 68 which is attached about its outer circumferential edge to the wall 66 and defines a central opening 70 through which a mounting plate 72 extends .
- a rotary seal (not shown) is provided between the cover plate 68 and mounting plate 72.
- the mounting plate 72 rotates with the drum 12 and hub 62.
- a wheel (not shown) can be fastened to the mounting plate 72 via axially extending studs 74.
- the housing 58 contains a volume of lubricating oil which acts to reduce wear of the friction material 16 and the braking surfaces 20.
- the friction material 16 can be provided with a plurality of grooves, and in particular spiroidal grooves 76 on their surface. Opposite ends of the grooves 76 open onto opposite axial edges of the friction material 16 to channel the oil across the face of the friction material 16.
- the friction material 16 is supported on a steel backing 78 which is attached by screws or bolts 80 to the drum 12.
- FIG. 4 A minor variation of the fluid cooled drum brake system 10 is depicted in Figure 4.
- the system in Figure 4 differs from that depicted in Figure 1 solely by the provision of friction material 16 as a single continuous layer about the entire circumference of the inner circumferential surface 14 of the drum 12. - 10 -
Abstract
A fluid cooled drum brake system (10) comprises a drum (12) having an inner circumferential surface (14) to which is attached a layer of friction material. Two sets of brake shoes (18a, 18b) are rotationally fixed within the drum (12). Each shoe (18a, 18b) has an outer surface which forms a braking surface (20) facing the friction material, a fluid inlet, a fluid outlet, and a number of fluid flow paths in fluid communication between the fluid inlet and the fluid outlet, and extending beneath the braking surface (20). A pair of double acting hydraulic piston (28) applies force to the brake shoes (18a, 18b) to urge their respective braking surfaces (20) against the friction material. A cooling fluid circulates through the fluid flow paths to extract heat from the shoes (18a, 18b) and the braking system (10).
Description
FLUID COOLED DRUM BRAKE SYSTEM
Field of the Invention
The present invention relates to a drum brake system.
Background of the Invention
A conventional drum brake system comprises a drum which is fixed to a rotating body such as a hub, and a pair of brake shoes each of which is rotationally fixed and pivotally coupled at one end to a stationary support located within the drum. Each shoe has an outer circumferential surface to which is attached a lining of friction material. A double acting piston is located between adjacent opposite ends of the shoes for the purposes of causing the shoes to pivot outwardly to bring the friction material into contact with a braking surface on the drum.
A wet drum brake system is of the same basic design as the conventional dry drum brake system but with the inclusion of a sealed housing which encloses the drum and the shoes, and contains a volume of lubricating fluid such as oil.
To maintain effective braking it is desirable to maintain the temperature at the braking drum and shoe interface (the "braking interface") in the region of 70°C to 80°C. In existing dry drum brake systems, the temperature generated at the braking interface typically reaches 350°C to 400°C although this range can be exceeded in some instances .
Surprisingly the lubricating oil in the conventional wet braking system does not reduce the temperature at the braking interface to the above-mentioned desired range. A seemingly obvious way to address this would be to pump the
- 1 - FLUID COOLED DRUM BRAKE SYSTEM
Field of the Invention
The present invention relates to a drum brake system.
Background of the Invention
A conventional drum brake system comprises a drum which is fixed to a rotating body such as a hub, and a pair of brake shoes each of which is rotationally fixed and pivotally coupled at one end to a stationary support located within the drum. Each shoe has an outer circumferential surface to which is attached a lining of friction material. A double acting piston is located between adjacent opposite ends of the shoes for the purposes of causing the shoes to pivot outwardly to bring the friction material into contact with a braking surface on the drum.
A wet drum brake system is of the same basic design as the conventional dry drum brake system but with the inclusion of a sealed housing which encloses the drum and the shoes, and contains a volume of lubricating fluid such as oil .
To maintain effective braking it is desirable to maintain the temperature at the braking drum and shoe interface (the "braking interface") in the region of 70°C to 80°C. In existing dry drum brake systems, the temperature generated at the braking interface typically reaches 350°C to 400°C although this range can be exceeded in some instances .
Surprisingly the lubricating oil in the conventional wet braking system does not reduce the temperature at the braking interface to the above-mentioned desired range. A seemingly obvious way to address this would be to pump the
- 2 - oil of the wet brake system through a radiator or other heat exchanger. However in order to provide optimum performance, the volume of oil within the wet brake system is only a fraction of the volume defined by the housing containing the braking system. The remainder of the volume is occupied by air. The presence of air creates enormous difficulties in pumping oil through a heat exchanger. In theory, this could be rectified by completely filling the housing with oil. However were this to occur, then it would not be possible to expel the oil between the brake shoes and braking surface during a braking operation thereby drastically reducing stopping power .
Throughout this specification, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.
Summary of the Invention
It is an- object of the present invention to provide a drum brake system in which heat is more effectively transferred from the braking interface.
According to one aspect of the present invention there is provided, a fluid cooled drum brake system comprising:
a brake drum having an inner circumferential surface;
a set of brake shoes rotationally fixed within the drum each shoe in the set having an outer surface facing the inner circumferential surface, a fluid inlet, a fluid outlet, and one or more fluid flow paths in fluid
- 3 - communication between the fluid inlet and the outlet and extending beneath at least a portion of the outer surface and through which a cooling fluid flows;
a layer of friction material attached to one of the inner circumferential surface and the outer surface, the other of the inner circumferential surface and outer surface forming a braking surface; and,
an actuator for selectively applying a force to the set of brake shoes to force respective braking surfaces against the friction material .
According to a further aspect of the present invention there is provided a fluid cooled wet drum brake system comprising:
a sealed housing containing a volume of lubricating liquid;
a drum brake disposed in the housing and having an inner circumferential surface;
a set of brake shoes rotationally fixed within the drum, each shoe in the set having an outer surface facing the inner circumferential surface, a fluid inlet, a fluid outlet, and one or more fluid flow paths in fluid communication between the inlet and the outlet and extending beneath at least a portion of the outer curved surface through which a cooling fluid flows;
a layer of friction material attached to one of tge inner circumferential surface and the outer curved surface, the other of the inner circumferential surface and the outer curved surface forming a braking surface; and,
- 4 - an actuator for selectively applying a force to the brake shoes to force respective braking surfaces against the friction material .
Preferably the layer of friction material is attached to the inner circumferential surface and the outer surface forms the braking surface.
Preferably the friction material comprises a plurality of pads of friction material disposed about the inner circumferential surface.
Preferably the pads are circumferentially spaced apart from each other.
However in an alternate embodiment, the friction material comprises a single ring of friction material attached to the inner circumferential surface.
Preferably a surface of said friction material facing the braking surface is provided with a plurality of grooves .
Preferably the grooves open onto axially opposite edges of the friction material .
Preferably the grooves follow a spiroidal path.
Preferably the set of brake shoes comprises two brake shoes and the actuator selectively applies a force to each of the two brake shoes to urge the braking surfaces into contact with the friction material .
Preferably each brake shoe comprises a first curved plate provided with a plurality of channels on one side and a second curved plate attached to the first curved plate for covering the channels, the covered channels forming the internal fluid flow paths .
- 5 -
Preferably each brake shoe is mounted in the drum to slide linearly toward said friction material when the actuator is operated to urge the braking surface into contact with the friction material .
Preferably the actuator operates simultaneously at opposite ends on the brake shoes .
Preferably the actuator comprises a pair of pistons each piston acting between the ends of the brake shoes at respective opposite ends of the brake shoes.
Brief Description of the Drawings
An embodiment of the present inventions will now be described by way of example only with reference to the accompanying drawings in which:
Figure 1 is a front view of a fluid cooled drum brake system in accordance with the present invention;
Figure 2 is a representation of a pair of brake shoes incorporated in the fluid cooled drum brake system;
Figure 2A is a view of section A-A of the brake shoes depicted in Figure 2;
Figure 2B is a view of section B-B of the brake shoes depicted in Figure 2 ;
Figure 3 is a section view of a wet drum brake incorporated in an embodiment of the fluid cooled drum brake system; and,
Figure 4 is a front view of a second embodiment of the fluid cooled drum brake system.
- 6 - Detailed Description of Preferred Embodiments
With reference to the accompanying drawings an embodiment of the fluid cooled drum brake system 10 in accordance with the present invention comprises a brake drum 12 (see Figure 3) having an inner circumferential surface 14 to which is attached a layer of friction material formed as three circumferentially spaced arcuate sections of friction material 16a-16c (hereinafter referred to generally as "friction material 16") . A set of two brake shoes 18a and 18b (hereinafter referred to in general as "brake shoes 18") is rotationally fixed within the drum 12. Each brake shoe 18 has: an outer (convexly curved) surface which forms a braking surface 20 facing the friction material 16; a fluid inlet 22 (see Figures 2 and 2A) ; fluid outlet 24; and, a number of fluid flow paths 26 in fluid communication between the fluid inlet 22 and fluid outlet 24 and extending beneath at least a portion of the braking surface 20. An actuator 27 in the form of a pair of double-acting hydraulic pistons 28 is provided for selectively applying force to the brake shoes 18 to urge their respective braking surfaces 20 against the friction material 16.
Each brake shoe 18 is formed with first and second curved plates 30 and 32 of a curvature which is coaxial with the inner surface 14 of the drum 12. The curved plate 32 has an outer surface which constitutes the braking surface 20. The curved plate 30 is radially inside of the plate 32 and has a radially inner surface 34 to which is coupled the brake shoe web 36. The fluid inlet 22 and fluid outlet 24 are formed through the surface 34 of the plate 30 and provide fluid communication to the fluid flow paths 26 which are confined between the curved plates 30 and 32.
The fluid flow paths 26 are formed as a plurality of parallel channels 38, machine, cast or otherwise formed on
- 7 - a radially outer surface 40 of the curved plate 30. The channels 38 are separated by parallel spaced-apart walls or ridges 41 that are created in the process of forming the channels 38. Opposite ends of the channels 38 lead to common feed channels 42 and 44 which provide fluid communication with the inlet 22 and outlet 24 respectively. The fluid flow paths 26 are effectively created by covering the channels 38 with the curved plate 32 and sealing the plate 32 to the plate 30.
Scrapers 46, typically made from PTFE are provided on each brake shoe 18 at opposite ends of the curved plates 30 and 32. The purpose of the scrapers 46 is to wipe lubricating oil from the surface of the friction material 16 when the brake shoes 18 are used in a wet brake system. The scrapers 46 are resiliently biased so as to protrude radially beyond the braking surface 20. As the shoes 18 are advanced toward the friction material 16, the scrapers 46 will initially contact the friction material 16 to wipe off the lubricating oil. As the pistons 28 continue to advance the shoes 18 toward and into contact with the friction material 16, the scrapers 46 retract radially inwardly. Further details of the operation and structure of the scrapers 46 can be derived from Applicant's International Publication No. WO 02/23060, the contents of which are incorporated herein by way of reference.
A substantial departure in the structure of the brake system 10 in comparison with conventional drum brakes is that the shoes 18 and actuator 27 (ie pistons 28) are arranged to ensure that the shoes 18 move linearly toward the friction material 16 rather than move in an arcuate path. To this end, the webs 36 of the shoes 18 are provided with elongated slots 47 through which guide pins 48 extend. The pins 48 are on a stationary mounting plate (not shown, but of a form similar to the stationary plate used in conventional drum brakes to support the brake
- 8 - shoes) located within or adjacent the drum 12. The actuator 27 operates at opposite ends of the shoes 18 to cause the shoe to slide linearly into contact with the friction material 16. More particularly, respective pistons 28 act between the ends of adjacent shoes 18. Upon release of an associated brake pedal, springs 50 which are coupled between the webs 36 of the shoes 18, slide the shoes 18 linearly toward each other and out of contact with the friction material 16 thereby releasing the brake. The springs 50 may be coupled to the webs 36 in any conventional manner including by the provision of hooks 52 on opposite ends of the springs 50 which engage pins 54 extending axially from one side of the webs 36.
Since the shoes 18 are rotationally fixed and move linearly only a short distance, hoses (now shown) can be attached to the inlet 22 and outlet 24 to couple the fluid flow paths 26 to a cooling circuit which can include a reservoir of cooling fluid such as water or glycol, a pump and if desired or required, a radiator or heat exchanger. By flowing fluid through the fluid flow path 26 heat is transferred from the immediate vicinity of the braking interface thereby providing a mechanism to maintain temperature at the locking interface in the region of 70°C to 80°C.
Embodiment of the drum brake system 10 may be utilised as either a dry brake system or alternately as part of a wet brake system.
Figure 3 depicts an embodiment of a wet brake system 56 in which the fluid cooled from brake system 10 may be incorporated. The wet brake system 56 is in substance the same as the dry brake system illustrated in Figures 1 and 2 but with the addition of an outer sealed housing 58 which contains the drum 12, friction material 16 and brake shoes 18 (not shown) . The housing 58 is a stationary
- 9 - component and is provided with an opening 60 at one end through which a rotating body in the form of a mounting hub 62 passes . The drum 12 is attached to the mounting hub by mounting bolts 64. Thus the drum 12 rotates with the mounting hub 62." Circumferential seals 65 are provided within the housing 58 to form a fluid seal against an outer surface of the hub 62. The housing 58 includes a circumferential wall 66 which extends about the outside of the drum 12, and a cover plate 68 which is attached about its outer circumferential edge to the wall 66 and defines a central opening 70 through which a mounting plate 72 extends . A rotary seal (not shown) is provided between the cover plate 68 and mounting plate 72. The mounting plate 72 rotates with the drum 12 and hub 62. A wheel (not shown) can be fastened to the mounting plate 72 via axially extending studs 74. The housing 58 contains a volume of lubricating oil which acts to reduce wear of the friction material 16 and the braking surfaces 20.
To assist in the dispersion of lubricating fluid during a braking action, the friction material 16 can be provided with a plurality of grooves, and in particular spiroidal grooves 76 on their surface. Opposite ends of the grooves 76 open onto opposite axial edges of the friction material 16 to channel the oil across the face of the friction material 16. The friction material 16 is supported on a steel backing 78 which is attached by screws or bolts 80 to the drum 12.
A minor variation of the fluid cooled drum brake system 10 is depicted in Figure 4. The system in Figure 4 differs from that depicted in Figure 1 solely by the provision of friction material 16 as a single continuous layer about the entire circumference of the inner circumferential surface 14 of the drum 12.
- 10 -
Now that embodiments of the present invention have been described in detail it will be apparent to those skilled in the relevant arts that numerous modifications and variations may be made without departing from the basic inventive concepts. For example, while the set of brake shoes is depicted as comprising two brake shoes 18a and 18b, the set may contain different numbers of shoes.
All such modifications and variations are deemed to be within the scope of the present invention the nature of which is to be determined from the above description and the appended claims .
Claims
1. A fluid cooled drum brake system comprising:
a brake drum having an inner circumferential surface;
a set of brake shoes rotationally fixed within the drum each shoe in the set having an outer surface facing the inner circumferential surface, a fluid inlet, a fluid outlet, and one or more fluid flow paths in fluid communication between the fluid inlet and the outlet and extending beneath at least a portion of the outer surface and through which a cooling fluid flows;
a layer of friction material attached to one of the inner circumferential surface and the outer surface, the other of the inner circumferential surface and outer surface forming a braking surface; and,
an actuator for selectively applying a force to the set of brake shoes to force respective braking surfaces against the friction material .
2. A fluid cooled wet drum brake system comprising:
a sealed housing containing a volume of lubricating liquid;
a drum brake disposed in the housing and having an inner circumferential surface;
a set of brake shoes rotationally fixed within the drum, each shoe in the set having an outer surface facing the inner circumferential surface, a fluid inlet, a fluid outlet, and one or more fluid flow paths in fluid communication between the inlet and the outlet and - 12 - extending beneath at least a portion of the outer curved surface through which a cooling fluid flows;
a layer of friction material attached to one of the inner circumferential surface and the outer curved surface, the other of the inner circumferential surface and the outer curved surface forming a braking surface; and,
an actuator for selectively applying a force to the brake shoes to force respective braking surfaces against the friction material.
3. The system according to claim 1 or 2 wherein the layer of friction material is attached to the inner circumferential surface and the outer surface forms the braking surface.
4. The system according to claim 3 wherein the friction material comprises a plurality of pads of friction material disposed about the inner circumferential surface.
5. The system according to claim 4 wherein the pads are circumferentially spaced apart .
6. The system according to claim 3 wherein the friction material comprises a single ring of friction material attached to the inner circumferential surface.
7. The system according to any one of claims 1-6 wherein a surface of said friction material facing the braking surface is provided with a plurality of grooves .
8. The system according to claim 7 wherein the grooves open onto axially opposite edges of the friction material . - 13 -
9. The system according to claim 7 or 8 wherein the grooves follow a spiroidal path.
10. The system according to any one of claims 1-9 wherein the set of brake shoes comprises two brake shoes and the actuator selectively applies a force to each of the two brake shoes to urge the braking surfaces into contact with the friction material.
11. The system according to claim 10 wherein each brake shoe is mounted in the drum to slide linearly toward said friction material when the actuator is operated to urge the braking surface into contact with the friction material .
12. The system according to claim 11 wherein the actuator operates simultaneously at opposite ends on the brake shoes .
13. The system according to claim 12 wherein the actuator comprises a pair of pistons each piston acting between the ends of the brake shoes at respective opposite ends of the brake shoes .
14. The system according to any one of claims 1-13 wherein each brake shoe comprises a first curved plate provided with a plurality of channels on one side and a second curved plate attached to the first curved plate for covering the channels , the covered channels forming the internal fluid flow paths.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2003904669A AU2003904669A0 (en) | 2003-08-29 | Fluid cooled drum brake system | |
AU2003904669 | 2003-08-29 |
Publications (1)
Publication Number | Publication Date |
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WO2005021993A1 true WO2005021993A1 (en) | 2005-03-10 |
Family
ID=34230053
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/AU2004/001159 WO2005021993A1 (en) | 2003-08-29 | 2004-08-27 | Fluid cooled drum brake system |
Country Status (1)
Country | Link |
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WO (1) | WO2005021993A1 (en) |
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN100567057C (en) * | 2008-04-23 | 2009-12-09 | 张春 | Water-cooled vehicle brake |
CN102155506A (en) * | 2011-03-16 | 2011-08-17 | 湖南运达机械制造有限公司 | Self-regulation clearance hydraulic drum-type front brake with temperature compensation function |
RU2459986C2 (en) * | 2010-02-26 | 2012-08-27 | Ивано-Франковский национальный технический университет нефти и газа | Method of defining directions of electric current components in friction pairs ''polymer-metal'' of drum shoe brake at its heating at test bench (versions) |
RU2462628C2 (en) * | 2010-04-19 | 2012-09-27 | Ивано-Франковский национальный технический университет нефти и газа | Method to detect directions of electric current components in friction pairs "polymer-metal" of drum-block brake during their heating in bench conditions |
RU2514385C2 (en) * | 2012-03-01 | 2014-04-27 | Ивано-Франковский национальный технический университет нефти и газа | Device and method for determination of thermal conditions of drum-shoe brake metal-polymer friction pairs at loading under test bench conditions |
RU2525347C2 (en) * | 2012-03-21 | 2014-08-10 | Ивано-Франковский национальный технический университет нефти и газа | Method of heating and cooling of brake drums of carrier drum-shoe brake for evaluation of their thermal balance |
RU2533864C2 (en) * | 2012-11-15 | 2014-11-20 | Ивано-Франковский национальный технический университет нефти и газа | System of thermoelectric polarisation of drum-shoe brake friction pad surfaces in test conditions |
CN108071715A (en) * | 2017-12-27 | 2018-05-25 | 朱宗华 | A kind of on-deformable drum brake lining of city of adstante febre |
CN108087451A (en) * | 2017-12-27 | 2018-05-29 | 朱宗华 | A kind of big drum brake lining of city of frictional force |
CN108105283A (en) * | 2017-12-27 | 2018-06-01 | 朱宗华 | A kind of easy heat radiation drum brake lining of city |
CN110142599A (en) * | 2019-02-22 | 2019-08-20 | 江苏汤臣汽车零部件有限公司 | A kind of brake assembly processing Intelligent assembly system |
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Publication number | Priority date | Publication date | Assignee | Title |
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CN100567057C (en) * | 2008-04-23 | 2009-12-09 | 张春 | Water-cooled vehicle brake |
RU2459986C2 (en) * | 2010-02-26 | 2012-08-27 | Ивано-Франковский национальный технический университет нефти и газа | Method of defining directions of electric current components in friction pairs ''polymer-metal'' of drum shoe brake at its heating at test bench (versions) |
RU2462628C2 (en) * | 2010-04-19 | 2012-09-27 | Ивано-Франковский национальный технический университет нефти и газа | Method to detect directions of electric current components in friction pairs "polymer-metal" of drum-block brake during their heating in bench conditions |
CN102155506A (en) * | 2011-03-16 | 2011-08-17 | 湖南运达机械制造有限公司 | Self-regulation clearance hydraulic drum-type front brake with temperature compensation function |
RU2514385C2 (en) * | 2012-03-01 | 2014-04-27 | Ивано-Франковский национальный технический университет нефти и газа | Device and method for determination of thermal conditions of drum-shoe brake metal-polymer friction pairs at loading under test bench conditions |
RU2525347C2 (en) * | 2012-03-21 | 2014-08-10 | Ивано-Франковский национальный технический университет нефти и газа | Method of heating and cooling of brake drums of carrier drum-shoe brake for evaluation of their thermal balance |
RU2533864C2 (en) * | 2012-11-15 | 2014-11-20 | Ивано-Франковский национальный технический университет нефти и газа | System of thermoelectric polarisation of drum-shoe brake friction pad surfaces in test conditions |
CN108071715A (en) * | 2017-12-27 | 2018-05-25 | 朱宗华 | A kind of on-deformable drum brake lining of city of adstante febre |
CN108087451A (en) * | 2017-12-27 | 2018-05-29 | 朱宗华 | A kind of big drum brake lining of city of frictional force |
CN108105283A (en) * | 2017-12-27 | 2018-06-01 | 朱宗华 | A kind of easy heat radiation drum brake lining of city |
CN110142599A (en) * | 2019-02-22 | 2019-08-20 | 江苏汤臣汽车零部件有限公司 | A kind of brake assembly processing Intelligent assembly system |
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