WO2013044397A1

WO2013044397A1 - Arrangement for automatically compensating brake pad wear in an annular disk brake

Info

Publication number: WO2013044397A1
Application number: PCT/CA2012/050690
Authority: WO
Inventors: Alain Constans
Original assignee: Asteria Performance Inc
Current assignee: Asteria Performance Inc
Priority date: 2011-09-30
Filing date: 2012-10-01
Publication date: 2013-04-04
Anticipated expiration: 2014-03-30

Abstract

The arrangement includes an inboard annular section (200) and an outboard annular section (202), both coaxially disposed with reference to a central axis (5) of the annular disk brake (10). The annular sections (200, 202) are pivotable with reference one another. The arrangement has a positioning system (210) interposed between the annular sections (200, 202). The positioning system (210) includes two torque-transmitting mechanisms (224, 226) allowing an incremental and irreversible offset of the relative angular position between the annular sections (200, 202) to compensate for the brake pad wear.

Description

ARRANGEMENT FOR AUTOMATICALLY COMPENSATING BRAKE PAD WEAR

IN AN ANNULAR DISK BRAKE

CROSS-REFERENCE TO PRIOR APPLICATION

The present case claims priority over a patent application filed in the United States on 30 September 2011 under Serial No. 61/541,598 and entitled "ARRANGEMENT FOR AUTOMATICALLY COMPENSATING BRAKE PAD WEAR IN AN ANNULAR DISK BRAKE", the entire contents of which is hereby incorporated by reference.

TECHNICAL FIELD

The technical field relates generally to annular disk brakes, and more particularly to arrangements for automatically compensating brake pad wear.

BACKGROUND

An annular disk brake includes at least one rotor disk that is axially movable with reference to a fixed component. The rotor disk is in a torque-transmitting engagement with a rotating element, such as the wheel of a vehicle for instance. The rotor disk is axially movable between a set of fixed braking pads on one side, and a set of axially-movable braking pads on the opposite side of the rotor disk. The set of movable brake pads is axially pushed against the corresponding side of the rotor disk using an actuator assembly, for instance a pneumatic, hydraulic or electric actuator. A braking friction and heat are generated when the brake pads are in a clamping engagement with the opposite sides of the rotor disk. An example of an annular disk brake is described in PCT application published on 4 June 2009 under publication number WO 2009/067801, the content of which is hereby incorporated by reference in its entirety.

Over time, the intense friction between brake pads and the rotor disk causes wear and inevitably, a progressive decrease in thickness. This decrease in thickness, although relatively small, can increase the travel stroke of the brake pedal of the vehicle because movable parts must move over a greater distance to achieve the same result. A wear compensation system is thus often required in order to maintain a relatively constant travel stroke of the brake pedal. An example of such system is described in PCT application published on 28 April 2005 under publication number WO 2005/038287. Other systems also exist.

Although many of prior systems can be suitable in some designs, they are not completely satisfactory in others, especially for a brake where the braking force is transmitted through pivoting parts and compactness of the brake is an issue. Thus, room for improvements still exists in this area.

SUMMARY

In one aspect, there is provided an arrangement for automatically compensating brake pad wear in an annular disk brake, the brake having a casing, an inboard side, an outboard side and a central axis, the arrangement including: an inboard annular section and an outboard annular section, both coaxially disposed with reference to the central axis, the annular sections being pivotally engaged to one another; and a positioning system interposed between the annular sections, the positioning system including: a first torque-transmitting mechanism establishing a torque-transmitting engagement between the annular sections through a pinion when the inboard annular section is urged to pivot in a forward angular direction during braking to generate a braking force inside the brake, the first mechanism including a cam unit having one end operatively connected to a fixed location in the casing, the cam unit being configured to pivot the pinion during at least an initial portion of an angular movement of the inboard annular section in the forward angular direction and from an initial angular position, thereby pivoting the outboard annular section in the forward angular direction ahead of the inboard annular section during braking; and a second torque-transmitting mechanism establishing a torque-transmitting engagement between the annular sections when the outboard annular section is urged to pivot in a backward angular direction upon releasing the braking force, the second mechanism triggering an incremental and irreversible offset of an initial angular position of the outboard annular section with reference to the initial angular position of the inboard annular section to compensate for the brake pad wear when the outboard annular section is pivoted by the cam unit ahead of the inboard annular section during braking over at least a threshold relative angle.

In another aspect, there is provided a method for automatically compensating brake pad wear in an annular disk brake, the method including: from a non-braking position of the brake, establishing a first torque-transmitting engagement between first and second coaxially- disposed annular sections to apply a braking force at a rotor disk provided within the brake and pivoting the annular sections in a forward angular direction to increase the braking force; while the annular sections are pivoted in the forward angular direction to increase the braking force, pivoting the second annular section in the forward angular direction ahead of the first annular section over at least an initial range of angular positions of the first annular section; incrementally offsetting the relative angular position between the annular sections when the brake will be back at the non-braking position if, when pivoted in the forward angular direction, the second annular section pivots of more than a threshold relative angle with reference to the first annular section; and establishing a second torque-transmitting engagement between the annular sections when the braking force is released and pivoting the annular sections in a backward angular direction to set the brake back to the non-braking position.

Further details on theses aspects as well as other aspects of the proposed concept will be apparent from the following detailed description and the appended figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a partially-exploded isometric view illustrating an example of an annular disk brake incorporating the concept as suggested herein;

FIG. 2 is an isometric view of the brake shown in FIG. 1 once assembled, as viewed from the inboard side;

FIG. 3 is a view similar to FIG. 2 but showing the actuator assembly being detached from the rest of the brake;

FIG. 4 is a partially-exploded isometric view illustrating the brake pad carrier and the intermediary member of the brake in FIG. 1; FIG. 5 is an isometric view illustrating the brake pad carrier and the intermediary member shown in FIG. 4 when they are in engagement with one another;

FIG. 6 is a partially-exploded isometric view showing the intermediary member and the brake pad wear compensating arrangement of the brake in FIG. 1;

FIG. 7 is an exploded isometric view of the outboard annular section of the intermediary member shown in FIG. 6;

FIG. 8 is an enlarged isometric view illustrating a portion of the brake pad wear compensating arrangement shown in FIG. 6;

FIG. 9 is a further enlarged isometric view of the brake pad wear compensating arrangement in FIG. 8;

FIGS. 10 to 13 are schematic views of the junction between the first rack segment and the pinion, as viewed by an observer standing on the outboard side of the brake in FIG. 1 and looking towards the inboard side;

FIGS. 14 and 15 are schematic views of the junction between the second rack segment and the toothed element, as viewed by an observer standing on the outboard side of the brake in FIG. 1 and looking towards the inboard side;

FIG. 16 is an enlarged isometric view of the inboard side of the brake pad wear compensating arrangement shown in FIG. 9; FIG. 17 is a view similar to FIG. 16 showing the intermediary member in a position where no braking force is applied;

FIG. 18 is a view similar to FIG. 17 showing the intermediary member when a braking force is being applied; and FIG. 19 is a view similar to FIG. 9 but showing the brake pad wear compensating arrangement being manually rewound to its original position during the installation of new brake pads.

DETAILED DESCRIPTION

FIG. 1 is a partially-exploded isometric view illustrating an example of an annular disk brake 10 incorporating the concept as suggested herein. The illustrated brake 10 is designed to be used on a large vehicle, such as a truck or a bus. The brake 10 can also be designed for other kinds of vehicles. The brake 10 can also be designed for other kinds of vehicles. FIG. 1 shows a right side brake. The left side brake would be substantially a mirror image thereof.

It should be noted that the words "outboard" and "inboard" in the present context refer to the relative position with reference to the longitudinal axis at the center of the vehicle. The brake 10 can be constructed as disclosed in PCT application published on 4 June 2009 under publication number WO 2009/067801. Variants are also possible as well.

The brake 10 of the illustrated example includes a main support 12 to which the wheel (not shown) of the vehicle is attached. The main support 12 is bearing-mounted and can rotate around an internal central spindle (not shown) that is coaxially located with reference to the central axis 5 of the brake 10. Thus, the rotation axis of the wheel is coincident with the central axis 5 of the brake 10.

The main support 12 has a plurality of axisymmetric mounting bolts 16 outwardly projecting from a substantially radial portion of the main support 12. Ten mounting bolts 16 are shown in the illustrated example. Such configuration is common for large trucks. Variants are possible as well.

Most internal of the components of the brake 10 are located within a space generally defined by a casing 18. The casing 18 of the illustrated example includes an outboard casing part 20 and an inboard casing part 22. The outboard casing part 20 is connected to the inboard casing part 22 using a plurality of spaced-apart bolts 26 located on the periphery of the brake 10. The bolts 26 extend in a direction that is substantially parallel to the central axis. The outboard casing part 20 and the inboard casing part 22 are fixed components, i.e. components that are not rotating with the main support 12 when the vehicle is in movement.

FIG. 1 shows the outboard casing part 20 and the inboard casing part 22 detached from one another for the sake of illustration. FIG. 2 is an isometric view of the brake 10 shown in FIG. 1, as viewed from the inboard side, once the two casing parts 20, 22 are assembled.

The brake 10 includes an actuator assembly 40 to generate the braking force inside the brake 10. In the illustrated example, the actuator assembly 40 has a generally annular configuration and is connected to the inboard side of the inboard casing part 22. The inboard casing part 22 is thus positioned between the outboard casing part 20 and the actuator assembly 40. Bolts are used to attach the actuator assembly 40 to the inboard casing part 22. The actuator assembly 40 can be connected differently to the casing 18. Other variants are also possible.

As can be appreciated, mounting the actuator assembly 40 on the inboard side of the inboard casing part 22 can increase the compactness of the brake 10 compared to designs where an actuator assembly is provided inside the casing 18.

The actuator assembly 40 can be pneumatic, hydraulic or even electric. FIG. 1 shows a pneumatic actuator assembly.

FIG. 1 also shows the rotor disk 60 of the brake 10. The rotor disk 60 is coaxially positioned with reference to the central axis 5. The rotor disk 60 has opposite side surfaces against which brake pads will be engaged. In the illustrated example, the rotor disk 60 has two parallel annular walls. These walls are connected together through a plurality of axisymmetric and spaced-apart ribs 61 forming air channels 63 between them. In use, the heated air will escape radially outwards through the air channels 63 while cooler air is admitted at a radially inner side of the rotor disk 60. The various parts of the rotor disk 60 are made integral with one another. Variants are possible as well.

The rotor disk 60 can move in the axial direction with reference to the central axis 5 because the interior of the rotor disk 60 is designed to slide over the main support 12. However, the rotor disk 60 is also in a torque-transmitting engagement with the main support 12. In the illustrated example, the outboard wall surface of the rotor disk 60 is designed to engage a first set of axisymmetric brake pads 62 mounted inside the outboard casing part 20. The inboard wall surface of the rotor disk 60 is designed to be engaged by a second set of axisymmetric brake pads 64 mounted on a substantially axially-guided brake pad carrier 66. Variants are possible as well.

The illustrated brake pad carrier 66 includes a ring member 68 to which the second brake pads 64 are connected to its outboard side. The brake pad carrier 66 is designed to move along a substantially axial direction and it is in a torque-transmitting engagement with the inboard casing part 22.

In use, when the inboard brake pads 64 are urged against the inboard wall surface of the rotor disk 60, its outboard wall surface will be forced to move closer to the outboard brake pads 62 and will engage them if not already engaged. Increasing the force by which the inboard brake pads 64 are engaged against the inboard wall surface of the rotor disk 60 will increase the brake pad clamping force, thus the friction with the braking pads 62, 64 on both sides of the rotor disk 60. The kinetic energy resulting from the motion of the vehicle and/or being supplied by the vehicle's engine is then transformed into heat in the brake 10 until a full stop of the vehicle or until the braking force is discontinued. Heat in the brake 10 eventually dissipates in the atmosphere.

A part called an intermediary member 100 is located between the brake pad carrier 66 and the actuator assembly 40 of the illustrated brake 10. The intermediary member 100 includes a plurality of axisymmetric and axially-projecting helical ramp surfaces 102. The ramp surfaces 102 face the outboard side of the brake 10. These ramp surfaces 102 are engaged by corresponding rollers 104 provided on the inboard side of the brake pad carrier 66. Four pairs of ramp surface 102 / roller 104 are provided in the illustrated example. Variants are also possible.

The intermediary member 100 is coaxially disposed with reference to the central axis 5. It can pivot in a radial plane within the inboard casing part 22. The intermediary member 100 does not rotate with the main support 12 and is not movable in the axial direction.

FIG. 3 is a view similar to FIG. 2 but showing the actuator assembly 40 being detached from the rest of the brake 10. As can be seen, the actuator assembly 40 of the illustrated example is provided as a removable unit incorporating the various components. Variants are also possible.

FIG. 4 is a partially-exploded isometric view illustrating the brake pad carrier 66 and the intermediary member 100 of the brake 10 in FIG. 1. As can be seen, the intermediary member 100 of the illustrated example includes a plurality of axisymmetric rollers 108 on its outer periphery. These rollers 108 are mounted around radially-oriented axles 110 and are part of a first cam interface of the brake 10. The rollers 108 cause an axial movement from an axially-actuated member (not shown) to pivot the intermediary member 100. The axially- actuated member is moved towards the outboard side by the actuator assembly 40.

FIG. 4 also shows the plurality of axisymmetric rollers 120 provided to guide the intermediate member 100 during its pivot motion within a radial plane. The rollers 120 are mounted around radially-oriented axles 122 that are connected inside the inboard casing part 22 and extending inwards. In use, the actuator assembly 40 creates a first force moving the axially-actuated member, which then urges the intermediary member 100 to pivot around the central axis 5 through the first cam interface. The first force is in a direction that is substantially parallel to the central axis 5 and will be used to create the braking force pushing the second brake pads 64 against the rotor disk 60. The torque generated at the intermediary member 100 causes the ramp surfaces 102 mounted thereon to move the brake pad carrier 66 in an axial direction towards the rotor disk 60. Rollers 94 (FIG. 4), mounted on radially-extending axles 96 provided on the inboard side of the brake pad carrier 66, guide it into a substantially axial movement.

The torque required at the intermediary member 100 to generate the braking force at the brake pad carrier 66 is in an angular direction depicted in the figures using a double-line arrow 150. This angular direction is referred to herein as the "forward angular direction" in reference to the braking force being applied, i.e. the force required to have the inboard brake pads 64 being urged against the rotor disk 60. The opposite direction is the "backward angular direction".

FIG. 5 is an isometric view illustrating the brake pad carrier 66 and the intermediary member 100 when they are in engagement with one another.

FIG. 6 is a partially-exploded isometric view illustrating the intermediary member 100 and the brake pad wear compensating arrangement for which more details will be given later. As can be seen, the illustrated intermediary member 100 includes an inboard annular section 200 and an outboard annular section 202. Both are juxtaposed and coaxially disposed with reference to one another. They are also coaxially disposed with reference to the central axis 5 of the brake 10 and are pivotally engaged to one another. The ramp surfaces 102 of the intermediary member 100 are provided on the outboard side of the outboard annular section 202. The inboard annular section 200 is made slightly larger than the outboard annular section 202 to provide space for an annular track 204 to which the inboard side of the outboard annular section 202 is engaged. The engagement between the annular sections 200, 202 is only through mating surfaces, thus metal on metal. No bearings are provided between them. Variants are possible as well.

Also in the illustrated example, the rollers 120 provided to guide the intermediary member 100 are located within corresponding tracks formed by recessed portions 205 in the inboard annular section 200.

FIG. 7 is an exploded isometric view of the outboard annular section 202 of the intermediary member 100. As can be seen, the outboard annular section 202 of the illustrated example includes a first curved and toothed rack segment 206 having a plurality of substantially radially-projecting teeth on its interior side, and a second curved and toothed rack segment 208 having a plurality of substantially radially-projecting teeth on its interior side. Both segments 206, 208 are rigidly connected to the inboard side of the outboard annular section 202, for instance using bolts, screws or the like. The rack segments 206, 208 have a curvature that is concentric with the central axis 5 and a radius similar to that to the annular sections 200, 202. They extend in a circumferential direction. Their teeth are also circumferentially disposed. In the illustrated example, the teeth of the first rack segment 206 are relatively large in size for maximizing strength while the teeth of the second rack segment 208 are relatively small in size, especially when compared to the teeth of the first rack segment 206, for a precise positioning. Variants are also possible. For instance, the rack segments 206, 208 could be provided as fully annular parts, thus spanning over 360 degrees in some implementations. However, the rack segments 206, 208 are not rotating parts, only pivoting parts. They are not rotating for instance with the wheel of the vehicle and accordingly, the design can be eccentric. In the present context, the word "segment" does not necessarily exclude the parts being fully annular. Other variants are also possible.

FIG. 8 is an enlarged isometric view illustrating a portion of the brake pad wear compensating arrangement shown in FIG. 6. It shows a positioning system 210 that is interposed between the annular sections 200, 202. In the illustrated example, the positioning system 210 includes a holder 212 that is rigidly connected to two corresponding spaced-apart and radially-extending flanges 200a, 200b inwardly projecting from the inboard annular section 200. Variants are possible as well. For instance, in some implementations, the holder 212 could be mounted on the inboard annular section 200 while the rack segments 206, 208 are mounted on the outboard annular section 202.

Also in the illustrated example, the holder 212 encloses a pinion 214 that partially extends from the radially-outer side of the holder 212. The pinion 214 is configured and disposed to mesh with the teeth on the interior side of the first rack segment 206. The pinion 214 is mounted around an axle 220 supported by the holder 212. The pinion 214 and the axle 220 cooperate with a ratchet device 222 and also with a torque limiting device 216 interposed between them. The axle 220 extends substantially parallel to the central axis 5. The pinion 214 thus rotates within a plane that is perpendicular to the central axis 5. In the illustrated example, the first rack segment 206, the pinion 214, the ratchet device 222 and the torque limiting device 216 are part of a first torque-transmitting mechanism 224 of the positioning system 210. Variants are also possible. The ratchet device 222 is schematically illustrated in FIGS. 10 to 13. The ratchet device 222 is configured and disposed to prevent a relative rotation between the pinion 214 and the axle 220 during braking, i.e. when a torque is provided by the actuator assembly 40 to pivot the intermediary member 100 in the forward angular direction. A relative rotation in the opposite direction is still possible. In the illustrated example, the ratchet device 222 is located in the holder 212. The ratchet device 222 can be in the form a conventional ratchet-type mechanism or be any other mechanism suitable for this function.

FIG. 9 is a further enlarged isometric view of the brake pad wear compensating arrangement in FIG. 8. It shows the positioning system 210 as viewed from the outboard side of the intermediary member 100. Over time, the brake pads 62, 64 will wear and their respective thicknesses will decrease. If no compensation is provided, the intermediary member 100 will need to reach to a progressively increased angular position for applying the same braking force against the rotor disk 60. The travel distance of the brake pedal operated by the driver of the vehicle will generally be increased as well. The brake pad wear compensating arrangement automatically offsets the relative angular position between the inboard annular section 200 and the outboard annular section 202 when needed. As depicted in FIG. 6, this will move progressively the ramp surfaces 102 over a distance Δ with reference to the rollers 104. It should be noted at this point that the distance Δ shown in FIG. 6 is only for the sake of illustration. The actual distance may vary from one implementation to another.

The positioning system 210 of the illustrated example also includes a toothed element 230 in engagement with the second rack segment 208. The toothed element 230 includes a plurality of corresponding teeth located on its radially-outer side. They are configured and disposed to slide in one direction over the second rack segment 208 but not in the other. Among other things, this unidirectional engagement keeps the precise positioning of the relative angular position between the inboard annular section 200 and the outboard annular section 202 when the intermediary member 100 pivots backward as the braking force is released.

The toothed element 230 is biased radially outwards against the interior of the second rack segment 208. In the illustrated example, as shown for instance in FIG. 8, this is done using a spring 232, in particular a torsion spring. The toothed element 230 is pivotally connected to the holder 212 at the pivot point 234. The toothed element 230 pivots around an axis that is substantially parallel to the central axis 5. Variants are possible as well.

The second rack segment 208 and the toothed element 230 are the basic parts of a second torque-transmitting mechanism 226. This second torque-transmitting mechanism 226 establishes a torque-transmitting engagement between the annular sections 200, 202 when the outboard annular section 202 is urged to pivot in the backward angular direction as the braking force is released. It prevents the outboard annular section 202 to pivot backwards with reference to the inboard annular section 200 so that once an incremental compensation is triggered, it does not go back by itself.

The torque urging the pivot motion in the backward angular direction can be provided by one or more springs in other parts of the brake 10, for instance springs acting on the brake part carrier 66 and forcing it to move in the inboard direction. Variants are possible as well.

To help better understand how the positioning system 210 functions, reference is now made to FIG. 13, which schematically depicts what happens when the inboard and outboard annular sections 200, 202 are pivoted backward once the braking torque is released, i.e. as the braking force decreases or is removed within the brake 10. The return force is applied first on the outboard annular section 202. Arrow 158 in FIG. 13 shows the direction of the return force. The first rack segment 206 will then tend to rotate the pinion 214 in direction of arrow 160 and because the torque now comes from the first rack segment 206 in the backward direction, the ratchet device 222 will not prevent the rotation of the pinion 214. The second torque- transmitting mechanism 226 will establish the required torque-transmitting engagement between the inboard and outboard annular sections 200, 202 to keep them in alignment.

FIGS. 14 and 15 are schematic views of the junction between the second rack segment 208 and the toothed element 230, as viewed by an observer standing on the outboard side of the brake 10 in FIG. 1 and looking towards the inboard side.

FIG. 14 shows how the teeth of the toothed element 230 and the teeth of the second rack segment 208 are configured relative to one another. As can be appreciated, moving the second rack segment 208 in the direction of arrow 158, i.e. the backward angular direction, will provide a positive engagement between the teeth of the second rack segment 208 and the teeth of the corresponding toothed element 230. Thus, the torque in direction of arrow 158 will also move the inboard annular section 200 in the backward angular direction.

FIG. 15 shows what happens when the outboard annular section 202 is offset with reference to the inboard annular section 200 over more than a threshold relative angle. As can be seen, moving the second rack segment 208 in direction of the arrow 152 changes the relative position of the corresponding teeth and if the position is shifted over a distance that is more than the width of a tooth, the crests of the teeth between the second rack segment 208 and those of the toothed element 230 will cross. This relative movement between the teeth is schematically depicted in FIG. 15 using arrow 228. The ramp surfaces 102 provided on the outboard annular section 202 will be slightly irreversibly repositioned with reference to the rollers 104 on the inboard side of the brake pad carrier 66 to compensate for the wear of the brake pads 62, 64. Meanwhile, the non-braking angular position of the inboard annular section 200 with reference to the casing 18 has not changed. The inboard annular section 200 will return to the exact same position shown in FIG. 17. The compensation, however, will not be triggered if the distance is less than the width of a tooth. The second torque-transmitting mechanism 226 thus also acts as a trigger mechanism for the positioning system 210.

FIG. 16 is an enlarged isometric view of the inboard side of the brake pad wear compensating arrangement shown in FIG. 9. It shows the second rack segment 208 and the tooted element 230 in engagement with one another. It should be noted that FIG. 16 also shows some of the parts of the bearing units 130 provided on the inboard side of the intermediary member 100. These bearing units 130 facilitate the pivot movement of the inboard annular section 200 within the inboard casing part 22. Variants are possible as well. FIG. 17 is a view similar to FIG. 16 showing the inboard side of the intermediary member 100 when no braking torque is applied. The inner wall 24 of the inboard casing part 22 over which the intermediary member 100 pivots is shown as being truncated for the sake of illustration.

FIG. 17 also illustrates a fixed pin 250 projecting from the inner wall 24 of the inboard casing part 22. This pin 250 is part of the positioning system 210. It is rigidly connected to the inner wall 24 and provides a connection to a fixed location in the casing 18, namely the inner wall 24 in the illustrated example. The pin 250 extends substantially parallel to the central axis 5. It is configured and disposed so that a portion of the pin 250 engages the interior of a slot 252 made in a slotted positioning member 254. This positioning member 254 is always in a torque-transmitted engagement with the axle 220 supporting the pinion 214. For instance, the positioning member 254 can include a non-circular hole fitting over a corresponding non- circular end portion of the axle 220, which end portion extends out of the holder 212. The positioning member 254 can be secured to the axle 220 using a nut or the like. Also in the illustrated example, the slot 252 extends from a bottom periphery of the positioning member 254 towards the axle 220. Variants are possible as well. A second example of the positioning member 254 is shown in FIGS. 17 and 18. It should be noted that although the positioning member 254 in FIG. 16 has a slightly different shape than that of the example shown in FIGS. 17 and 18, both examples have an identical function. The stippled lines in FIG. 16 show the variant of FIGS. 17 and 18. Other variants are possible as well.

FIG. 18 is a view similar to FIG. 17 showing the intermediary member 100 when a braking force is being applied.

The pin 250 and the positioning member 254 are the basic parts of a cam unit 256 of the illustrated example. The cam unit 256 is itself a part of the first torque-transmitting mechanism 224 and is designed for pivoting the outboard annular section 202 in the forward angular direction ahead of the inboard annular section 200 during braking. In use, when no braking force is applied, as in FIG. 17, the left side of the slot 252 simply abuts on the left side of the pin 250. Then, when the intermediary member 100 pivots in the forward angular direction during braking, the pin 250 and the slot 252 will force the axle 220 to pivot.

FIGS. 10 to 13 are schematic views of the junction between the first rack segment 206 and the pinion 214, as viewed by an observer standing on the outboard side of the brake 10 in FIG. 1 and looking towards the inboard side.

FIG. 10 illustrates the positioning system 210 when the vehicle is not braking. This is referred to as the non-braking position. The position of the pin 250 is shown.

FIG. 11 is a view similar to FIG. 10 but depicts the situation where the intermediary member 100 is being pivoted to apply a braking force within the brake 10. This ratchet device 222 is configured and disposed to lock the pinion 214 in position when the braking torque is being applied in direction of the double-lined arrow 150, thus in the forward angular direction of this specific example. As a result, the pinion 214 cannot rotate counterclockwise around the axle 220. The cam unit 256 of the first torque-transmitting mechanism 224 will also force the pinion 214 to rotate clockwise so as to move the outboard annular section 202 ahead of the inboard annular section 200 in direction of arrow 152.

Normally, if no compensation is required, the maximum relative angle over which the outboard annular section 202 is advanced ahead of the inboard annular section 200 is less than the width of a tooth at the second torque-transmitting mechanism 226. At a certain angular position, the braking force will become very high. The relative angular movement between the annular sections 200, 202 may reach a point where the pinion 214 cannot move the outboard annular section 202 ahead of the inboard annular section 200 anymore. The friction in-between the annular sections 200, 202 may also create a torque- transmitting engagement when the braking force is very high. Nevertheless, moving the intermediary member 100 in the forward angular direction to generate an even higher braking force may still be possible. This will cause the cam unit 256 to pivot the axle 220 even more. In the illustrated example, the torque limiting device 216 is provided so that the axle 220 is allowed to pivot even more at these maximum angles without further pivoting the pinion 214. Thus, the torque limiting device 216 prevents the torque applied on the pinion 214 to go beyond a maximum value. The mechanical stress of the components can be reduced with such feature. Variants are possible as well. As can be appreciated, the suggested concept provides a simple and practical way of automatically compensating wear of the brake pads 62, 64 in the annular disk brake 10 while still keeping the brake compact and efficient.

FIG. 16 further illustrates a manually-opened rewind mechanism 240 used in the illustrated example. The rewind mechanism 240 is provided to reset the positioning system 210 to or near its original position, for instance when new brake pads 62, 64 are installed during a maintenance operation. In other words, the rewind mechanism 240 removes the accumulated brake pad wear compensation of the previous sets of brake pads 62, 64. Accordingly, in the context, it should be noted that the word "irreversible" and other related words used herein are related to the configuration of the brake 10 in operation, not during maintenance.

The illustrated rewind mechanism 240 includes a gear 242 in mesh with the first rack segment 206. The gear 242 is supported by an axle 244 and a bearing or bushing 246 provided in a hole through the inner wall 24. A nut 260 is rigidly connected to the axle 244. Variations are possible as well. The gear 242, the axle 244 and the nut 260 form a unit that can freely rotate when the intermediary member 100 pivots while the brake 10 is in operation. Thus, this unit does not interfere with the normal operation of the brake 10.

FIG. 19 is a view similar to FIG. 9 but showing the brake pad wear compensating arrangement being manually rewound to its original position during the installation of new brake pads 62, 64. In other words, it will allow the outboard annular section 202 to be pivoted counter-clockwise with reference to the inboard annular section 200 in the example depicted in FIG. 6. The rewind mechanism 240 of the illustrated example includes a release mechanism to temporarily lift the toothed element 230 away from the second rack segment 208. The release mechanism is manually activated by a maintenance technician using a handheld tool, for instance a screwdriver. This release mechanism includes a rod 247 provided inside an axially- extending cavity of the axle 244. It also includes an eccentric cam element 248 attached at the outboard end of the rod 247. The inboard end 247a of the rod 247 includes a notch for receiving the tool. The rod 247 is longitudinally movable within the axle 244 and a compression spring 249 normally keeps the cam element 248 away from the toothed element 230. Variants are possible. In use, pressing the end 247a of the rod 247 with a tool brings the cam in registry with a flange 236 of the toothed element 230 and rotating the rod 247 brings the cam element 248 in engagement with the flange 236, thereby moving the toothed element 230 away from the second rack segment 208 against the action of the torsion spring 232. Keeping the toothed element 230 temporarily unengaged allows the maintenance technician to rotate the axle 244 in direction 154 using another handheld tool, for instance, a wench, upon rotating the nut 260 that is rigidly attached to the axle 244 on the inboard side of the inner wall 24. The rewind movement will not be blocked by the ratchet device 222 since it provides a free movement in direction 154.

Variants of the rewind mechanism are also possible. The present detailed description and the appended figures are meant to be exemplary only, and a skilled person will recognize that many changes can be made while still remaining within the proposed concept. For instance, the exact shape, number and/or configuration of some of the parts can be different compared to what was shown and/or described herein. More than one positioning system can be used on the brake, if desired.

The brake as illustrated can also be modified for use on many different kinds of vehicles, including vehicles that are not intended for road traveling, such as airplanes. Furthermore, using the brake in a machine that is not a vehicle is possible as well. Such machine can have, for instance, a pulley or another rotating element to which the brake is connected. The uses of the word "vehicle" or its equivalents in the present text only refer to the illustrated example and do not necessarily exclude using the brake in other environments.

In some implementations, some of the sets of rollers could be replaced by low-friction sliding elements or the like.

Still, many other variants of the proposed concept will be apparent to a skilled person, in light of a review of the present disclosure.

REFERENCE NUMERALS

5 brake central axis

10 annular disk brake

12 main support

16 mounting bolts

18 casing

20 outboard casing part 22 inboard casing part

24 inner wall

26 bolts

40 actuator assembly

60 rotor disk

61 radially-extending ribs

62 brake pads (first set)

63 air channels

64 brake pads (second set)

66 brake pad carrier

94 rollers

96 axles

100 intermediary member

102 ramp surfaces

104 rollers

108 rollers

1 10 axles

120 rollers

122 axles

130 bearings

150 braking-torque/force direction

152 relative motion direction repositioning direction angular direction

return torque direction

rotation direction

inboard annular section

a flange

b flange

outboard annular section

annular track

recesses portion of inboard annular section first rack segment

second rack segment

second portion of positioning system holder

pinion

torque limiting device

axle

ratchet device

first torque-transmitting mechanism second torque-transmitting mechanism relative movement between the teeth toothed element 232 torque spring

234 pivot point

236 flange

240 rewind mechanism

242 gear

244 axle

246 bearing / bushing

247 rod

247a inboard end (of rod) 248 cam element

249 spring

250 pin

252 slot

254 slotted positioning member 256 cam unit

Claims

CLAIMS:

1. An arrangement for automatically compensating brake pad wear in an annular disk brake (10), the brake (10) having a casing (18), an inboard side, an outboard side and a central axis (5), the arrangement including:

an inboard annular section (200) and an outboard annular section (202), both coaxially disposed with reference to the central axis (5), the annular sections (200, 202) being pivotally engaged to one another; and

a positioning system (210) interposed between the annular sections (200, 202), the positioning system (210) including:

a first torque-transmitting mechanism (224) establishing a torque- transmitting engagement between the annular sections (200, 202) through a pinion (214) when the inboard annular section (200) is urged to pivot in a forward angular direction during braking to generate a braking force inside the brake (10), the first mechanism (224) including a cam unit (256) having one end operatively connected to a fixed location (24) in the casing (18), the cam unit (256) being configured to pivot the pinion (214) during at least an initial portion of an angular movement of the inboard annular section (200) in the forward angular direction and from an initial angular position, thereby pivoting the outboard annular section (202) in the forward angular direction ahead of the inboard annular section (200) during braking; and

a second torque-transmitting mechanism (226) establishing a torque- transmitting engagement between the annular sections (200, 202) when the outboard annular section (202) is urged to pivot in a backward angular direction upon releasing the braking force, the second mechanism (226) triggering an incremental and irreversible offset of an initial angular position of the outboard annular section (202) with reference to the initial angular position of the inboard annular section (200) to compensate for the brake pad wear when the outboard annular section (202) is pivoted by the cam unit (256) ahead of the inboard annular section (200) during braking over at least a threshold relative angle.

The arrangement as defined in claim 1, characterized in that the outboard annular section (202) includes a plurality of axisymmetric helical ramp surfaces (102) on a side that is opposite the inboard annular section (200).

The arrangement as defined in claim 1 or 2, characterized in that the first torque- transmitting mechanism (224) includes a first curved and toothed rack segment (206) to which is engaged a corresponding pinion (214), the pinion (214) being mounted around an axle (220) and having ratchet device (222) interposed between the pinion (214) and the axle (220).

The arrangement as defined in claim 3, characterized in that the axle (220) extends substantially parallel to the central axis (5) and the first rack segment (206) circumferentially extends with reference to the central axis (5), the pinion (214) having teeth engaging corresponding teeth on an interior side of the first rack segment (206).

The arrangement as defined in claim 3 or 4, characterized in that the first rack segment (206) is rigidly connected to the outboard annular section (202) and the axle (220) is supported by a holder (212), the holder (212) being rigidly connected to the inboard annular section (200).

The arrangement as defined in any one of claims 3 to 5, characterized in that the cam unit (256) includes a pin (250) and a slotted positioning member (254), the pin (250) being connected to the fixed location (24) in the casing (18), the slotted positioning member (254) being in a torque-transmitting engagement with the axle (220) and including a slot (252) that extends from a bottom periphery of the slotted positioning member (254) towards the axle (220), the slot (252) receiving a portion of the pin (250), the pin (250) being positioned radially closer to the central axis (5) than the axle (220).

The arrangement as defined in claim 6, characterized in that the first torque- transmitting mechanism (224) includes a torque limiting device (216) between the axle (220) and the pinion (214).

The arrangement as defined in any one of claims 1 to 7, characterized in that the second torque-transmitting mechanism (226) includes a second curved and toothed rack segment (208) and a corresponding toothed element (230) engaging the second rack segment (208).

The arrangement as defined in claim 8, characterized in that the second rack segment (208) circumferentially extends with reference to the central axis (5), the toothed element (230) having teeth engaging corresponding teeth on an interior side of the second rack segment (208).

10. The arrangement as defined in claim 8 or 9, characterized in that the second rack segment (208) is rigidly connected to the outboard annular section (202) and the toothed element (230) is pivotally connected to the inboard annular section (200), the toothed element (230) pivoting around an axis that is substantially parallel to the central axis (5).

11. The arrangement as defined in claim 10, characterized in that the toothed element (230) is outwardly spring-biased against the second rack segment (208), preferably by a torsion spring (232).

12. The arrangement as defined in any one of claims 1 to 11, characterized in that the arrangement further includes a manually-operated rewind mechanism (240), the rewind mechanism (240) having a first portion engaging the outboard annular section (202) and a second portion temporarily disabling the second torque-transmitting mechanism (226) while the relative angular position between the annular sections (200, 202) is reset.

13. The arrangement as defined in claim 12, characterized in that the second portion of the rewind mechanism (240) includes an eccentric cam element (248) selectively lifting a portion of the second torque-transmitting mechanism (226) to remove the torque- transmitting engagement provided by the second torque-transmitting mechanism (226).

A method for automatically compensating brake pad wear in an annular disk brake (10), the method including:

from a non-braking position of the brake (10), establishing a first torque-transmitting engagement between first and second coaxially-disposed annular sections (200, 202) to apply a braking force at a rotor disk (60) provided within the brake (10) and pivoting the annular sections (200, 202) in a forward angular direction to increase the braking force;

while the annular sections (200, 202) are pivoted in the forward angular direction to increase the braking force, pivoting the second annular section (202) in the forward angular direction ahead of the first annular section (200) over at least an initial range of angular positions of the first annular section (200);

incrementally offsetting the relative angular position between the annular sections (200, 202) when the brake (10) will be back at the non-braking position if, when pivoted in the forward angular direction, the second annular section (202) pivoted of more than a threshold relative angle with reference to the first annular section (200); and

establishing a second torque-transmitting engagement between the annular sections (200, 202) when the braking force is released and pivoting the annular sections (200, 202) in a backward angular direction to set the brake (10) back to the non- braking position.

15. The method as defined in claim 14, characterized in that the second annular section (202) is moved ahead of the first annular section (200) until the torque provided to move the second annular section (202) ahead reaches a maximum value.

16. The method as defined in claim 14 or 15, further including:

rewinding the relative angular position between the annular sections (200, 202) during a maintenance operation using a manually-operated rewind mechanism (240) provided within the brake (10).

17. The method as defined in any one of claims 14 to 16, characterized in that the first annular section (200) is located on an inboard side of the brake (10) with reference to the second annular section (202).