PRIORITY DOCUMENTS

[0001 ] The present application claims priority from Australian Provisional Patent Application No. 2020900467 titled “VEHICLE DRUM BRAKE IMPROVEMENTS” and filed on 19 February 2020, the content of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

[0002] The present disclosure relates generally to drum brake systems for vehicles and, in particular, to brake drums of such brake systems.

BACKGROUND

[0003] Drum brakes are commonly employed on trucks and trailers, including heavy trucks and trailers, because they are considered to be more durable than disc brakes, requiring fewer lining replacements in a given period. What is more, replacement parts for drums are typically cheaper due to a larger economy of scale.

[0004] In such brake systems, a brake drum is used to generate braking torque by serving as a friction couple with a lining of a brake shoe. A brake drum typically comprises a cylindrical main body comprising an open end, an interior braking surface and a mounting or flange plate connected to the cylindrical main body by a wraparound, and encases the actuating brake components and brake shoes.

The flange plate is bolted to the wheel and wheel hub and connects the braking surface of the drum to the rotating system through the wraparound.

[0005] When braking occurs, the brake shoes are actuated and move outward away from the centre of the vehicle wheel rotation As the shoes are actuated, they press against the inner diameter of the rotating drum's braking surface, converting kinetic energy to heat energy by means of friction.

[0006] Over time, brake operations create loose friction (or lining) material from the brake shoes and loose iron material from the brake drums. Ordinarily, the intent is that this material finds its way out of the open end of the drum, which may be mostly closed off via a backing plate in any case. After a period of use, a lip is formed at the edge of braking surface near this open side of the drum by the brake shoe wearing into the drum, and this lip causes this material to be trapped inside of the drum, where it may have an adverse effect on brake performance and wear. Moreover, any dirt or debris, including rocks or stones, which may find its way inside of a brake drum in use, is typically then also trapped in the drum, where it will likely contribute to misalignment (of brake shoes in particular) and premature wear of brake components, and possibly even cause mechanical failure of these. This problem is exacerbated in cases where the vehicle operates on unsealed roads.

[0007] It is against this background and the problems and difficulties associated therewith that the present invention has been developed.

[0008] Certain objects and advantages of the present invention will become apparent from the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed.

SUMMARY

[0009] According to a first aspect, there is provided a vehicle brake drum comprising a cylindrical body portion and an internal cylindrical breaking surface, the brake drum further comprising at least one of a first type of through apertures extending between an interior and an exterior of the drum, and at least one of a second type of apertures extending between the interior and the exterior of the drum, wherein the or each of the first type of apertures is larger than the or each of the second type of apertures, and wherein the or each of first type of apertures is positioned adjacent to the internal cylindrical breaking surface, and the or each of the second type of apertures is positioned within the internal cylindrical braking surface at least.

[0010] Each of the second type of apertures is sized to pass dust and small debris therethrough

[001 1] Each of the first type of apertures is sized to pass pebbles, stones and rocks therethrough.

[0012] In one form, each of the first type of apertures may have a minimum dimension in the range of 10mm to 100mm across. In one form, each of the first type of apertures may have a minimum dimension in the range of 15mm to 80mm across. In one form, each of the first type of apertures may have a minimum dimension in the range of 20mm to 70mm across. In one form, each of the first type of apertures may have a minimum dimension in the range of 20mm to 60mm across. In one form, each of the first type of apertures may have a minimum dimension in the range of 20mm to 50mm across. In one form, each of the first type of apertures may have a minimum dimension in the range of 20mm to 40mm across. In one form, each of the first type of apertures may have a minimum dimension in the range of 20mm to 30mm across.

[0013] In one form, each of the second type of apertures may have a minimum dimension in the range of 1mm to 10mm across. In one form, each of the second type of apertures may have a minimum dimension in the range of 2mm to 9mm across. In one form, each of the second type of apertures may have a minimum dimension in the range of 2mm to 8mm across. In one form, each of the second type of apertures may have a minimum dimension in the range of 2mm to 7mm across In one form, each of the second type of apertures may have a minimum dimension in the range of 2mm to 6mm across. In one form, each of the second type of apertures may have a minimum dimension in the range of 2mm to 5mm across. In one form, each of the second type of apertures may have a minimum dimension in the range of 2mm to 4mm across.

[0014] In one form, the vehicle brake drum comprises a plurality or group of the first type of apertures.

[0015] In one form, each of the plurality of the first type of apertures is radially spaced apart around the drain.

[0016] In one form, each of the plurality of the first type of apertures is substantially equispaced around the brake drum.

[0017] In one form, the vehicle brake drum comprises a plurality or group of the second type of apertures.

[0018] In one form, each of the plurality of the second type of apertures is spaced apart across the braking surface.

[0019] In one form, each of the plurality of the second type of apertures is spaced apart around the braking surface.

[0020] In one form, for the or each of the first type of apertures, the interior of the drum comprises a means for directing any dust, dirt and debris in the drum towards the aperture.

[0021] In one form, the or each means for directing dirt and debris towards the or each of the first type of apertures comprises a projecting feature.

[0022] In one form, the means for directing dirt and debris towards the or each of the first type of apertures comprises a wall, a blade or a vane.

[0023] In one form, the means for directing dirt and debris towards the or each of the first type of apertures comprises a wall formed by an internal shoulder.

[0024] In one form, the internal shoulder reduces the internal diameter of the drum relative to an internal diameter of the braking surface. [0025] In one form, the wall faces toward the braking surface.

[0026] In one form, the wall is positioned adjacent to the braking surface.

[0027] In one form, the or each of the first type of apertures intersects the wall.

[0028] In one form, the wall extends around the or each of the first type of apertures.

[0029] In one form, the internal shoulder tapers or curves toward and to either side of the or each of the first type of apertures.

[0030] In one form, the means for directing dirt and debris towards the or each of the first type of apertures comprises a recessed feature.

[0031] In one form, the means for directing dirt and debris towards the or each of the first type of apertures comprises a groove or a channel.

[0032] According to a further aspect, there is provided a vehicle brake drum comprising at least one through aperture extending between an interior and an exterior thereof, and wherein for the or each through aperture, the interior of the drum comprises a means for directing dust, dirt and debris in the drum towards the aperture.

[0033] In one form, there is a single groove or channel for all apertures.

[0034] In one form, there is a separate groove or channel for each aperture.

[0035] In one form, there is a single blade or vane for all apertures.

[0036] In one form, there is a separate blade or vane for each aperture.

[0037] In one form, the brake drum comprises a flange plate portion and a wraparound portion between the cylindrical body and the flange plate.

[0038] The wraparound portion comprises a transition between the cylindrical body portion and the flange plate portion.

[0039] In one form, the or each of the first type of apertures extends through the wraparound portion.

[0040] The second group of apertures are sized to pass dust and small debris therethrough. [0041] In one form, the or each of the second type of apertures is located in the cylindrical body portion of the brake drum.

[0042] In one form, the brake drum comprises a squealer band, and some of the second type of apertures pass through the squealer band.

[0043] In one form, the second type of apertures are arranged in a row extending around the drum.

[0044] In one form, the second type of apertures are arranged into two or more rows, which are spaced apart across the braking surface.

[0045] In one form, the drum further comprises a squealer band.

[0046] In one form, some of the second type of apertures extend through the squealer band.

[0047] In one form, the or each of the first type of apertures is circular.

[0048] In one form, the or each of the first type of apertures is elongate.

[0049] In one form, the or each elongate aperture extends around a portion of the cylindrical portion of the drum.

[0050] In one form, the or each elongate aperture extends across a portion of the cylindrical portion of the drum.

[0051] In one form, the brake drum is formed by casting, In one form, the brake drum is fabricated, and thus formed by rolling and welding.

[0052] In one form, the or each of the first type of apertures is formed by cutting. In an alternative they are machined.

[0053] In one form, the or each of the second type of apertures is formed by drilling.

[0054] According to a further aspect, there is provided a brake drum assembly comprising the above- described brake drum.

[0055] According to a further aspect, there is provided a vehicle axle comprising the above-described brake drum assembly. [0056] For ease of description, a vehicle brake drum embodying the present invention is described below in its usual assembled position as shown in the accompanying drawings and terms such as front, rear, upper, lower, horizontal, longitudinal, etc. may be used with reference to this usual position. However, the vehicle brake drum may be manufactured, transported, sold, or used in orientations other than that described and shown here.

BRIEF DESCRIPTION OF DRAWINGS

[0057] Embodiments of the present disclosure will be discussed with reference to the accompanying drawings wherein:

[0058] Figure 1 is an isometric view of a brake drum viewed from an outer end thereof;

[0059] Figure 2 is a side view of the brake drum of Figure 1 ;

[0060] Figure 3 is an isometric view of the brake drum of Figures 1 and 2, viewed from an inner end thereof;

[0061] Figure 4 is an end view of the brake drum of Figures 1 through 3, viewed from the inner end thereof;

[0062] Figure 5 is a cross-sectional view taken through the brake drum at B-B;

[0063] Figure 6 is a detail view taken at C in Figure 5;

[0064] Figure 7 is a cross-sectional view through a wheel hub assembly comprising a brake drum according to a further embodiment;

[0065] Figure 8 is a side view of the brake drum from the wheel hub assembly of Figure 7;

[0066] Figure 9 is a cross-sectional view through the brake drum of Figure 8;

[0067] Figure 10 is a side view of a brake drum according to a further embodiment; and

[0068] Figure 11 is a cross-sectional view through the brake drum of Figure 10.

[0069] In the following description, like reference characters designate like or corresponding parts throughout the figures. DESCRIPTION OF EMBODIMENTS

[0070] Referring now to Figure 1 , there is shown a vehicle brake drum 1. The vehicle brake drum 1 illustrated is one intended for use on an axle of a heavy vehicle such as a prime mover or its trailer, but the invention is not so limited in application, being of potential use on smaller vehicles equipped with drum brakes.

[0071] The brake drum 1 comprises a cylindrical main body portion 2, a flange plate portion 4, a squealer band 5, and a wraparound portion 6 joining and transitioning between the body 2 and the flange plate portion 4. The cylindrical main body portion 2 features an open end 2a providing access to an interior of the brake drum 1 , and an internal, cylindrical braking surface 8 against which the brake shoes act. Typically, the open end 2a of the drum 1 is closed by fitment of a backing plate (not illustrated) which is removable for maintenance purposes.

[0072] The flange plate portion 4 comprises a large central aperture 10, for receiving a portion of a wheel hub therethrough, and a circular array of smaller holes 12 extends around the central aperture 10, each for the purpose of receiving a wheel stud that depends from the hub.

[0073] The brake drum 1 further comprises a plurality of a first type of through apertures 20 extending through the wraparound portion 6 between an interior and an exterior of the drum 1. The apertures 20 are radially spaced apart around the drum 1 , in a substantially equispaced manner.

[0074] Each of the first type of through apertures 20 extends through the wraparound portion 6 at a position adjacent to the braking surface 8. More specifically, in this case, each of the apertures 20 is circular, and tangentially bounds the braking surface 8.

[0075] For each through aperture 20, the interior of the drum 1 comprises a means for directing dust, dirt and debris towards the aperture 20.

[0076] In the case of the brake drum 1 illustrated, the means for directing dust, dirt and debris towards the aperture 20 comprises, in part, an internal shoulder comprising a wall 30 positioned adjacent to and facing the braking surface 8 so as to reduce the internal diameter of the drum 1 relative to an internal diameter of the braking surface 8. More specifically, in this case, the wall 30 bounds the braking surface 8

[0077] It can be seen that in this embodiment, each through aperture 20 intersects the wall 30. [0078] The wall 30 extends around each through aperture 20 on the wraparound 6 (and flange plate 4) side thereof. On each side of each aperture 20, the wall 30 tapers (alternatively it may curve) toward the aperture 20, before passing behind the aperture 20 on the wraparound 6 side thereof. In this case, the taper of the wall 30 is provided by a chamfer 32 extending from the shoulder 30 to the aperture 20.

[0079] Additional to the above, an internal face 33 of the drum 1 subtended between the chamfers 32 tapers outwardly (increasing the internal diameter) as it extends from the braking surface 8 toward each of the apertures 20.

[0080] In this embodiment, the wall 30, chamfers 32 and faces 33 collectively form the means for directing dust, dirt and debris in the drum 1 towards the apertures 20. In use, any dust, dirt and debris (such as rocks or stones) will roll around in the drum 1 as it rotates, eventually running against the wall 30 imtil it meets one of the chamfers 32, which will then co-operate with the faces 33 to direct this material to its respective aperture 20, through which aperture 20 the dust, dirt and debris may pass out of the drum 1.

[0081] In a non-illustrated embodiment, the internal shoulder might be replaced with a continuous channel, and the chamfers might be replaced with one or more angled (or curved) channels extending from the continuous channel to an aperture 20.

[0082] Advantageously, the present disclosure provides not only an outlet for dust, dirt and debris within a brake drum, but a means for directing this material towards this outlet. This will aid in keeping an interior of the drum clean, reducing the likelihood that this material will contribute to any of reduced brake performance, premature wear or mechanical failure.

[0083] The cylindrical main body 2 further comprises a plurality of a second type of through apertures 40 extending between the internal cylindrical braking surface 8 and an exterior of the cylindrical body 2 (including through the squealer band 5), for releasing dust (particularly brake or friction material dust), dirt and smaller debris in the drum 1 therefrom.

[0084] In this embodiment, each of the second type of apertures 40 (for dirt and dust to pass through) are smaller than the first type of apertures 20. Each of the first type of apertures 20 is sized for stones and rocks to pass therethrough. Each of the second type of apertures are sized for dirt and dust to pass through. In this embodiment, the second type of apertures 40 are arranged into a plurality of rows, which are spaced apart across the braking surface 8 so as to provide relatively uniform coverage across the braking surface 8. The apertures 40 in each row are spaced apart around the braking surface 8. [0085] Referring now to Figure 7, where there is illustrated a cross-sectional view through a wheel hub assembly comprising a brake drum la according to a further embodiment. Those parts of the brake drum 1a which are identical to those of brake drum 1 of Figures 1 through 6, will be denoted by the same reference numbers, and will not be described in detail again here.

[0086] As before, the brake drum la comprises a cylindrical main body 2, a flange plate 4, a squealer band 5, and a wraparound 6 joining the body 2 and the flange plate 4. The cylindrical main body 2 comprises an internal, cylindrical braking surface 8 against which the brake shoes 200 act.

[0087] The flange plate 4 comprises a large central aperture 10, for receiving a portion of a wheel hub 210 therethrough, and a circular array of smaller holes 12 extends around the central aperture 10, each for the purpose of receiving a wheel stud 212 that depends from the hub 210.

[0088] In this embodiment, each of the first type of through apertures 20a is elongated, with a direction of elongation extending in a direction around the drum 1a, and terminating at a pair of ends 21 .

[0089] Each of the apertures 20a intersects the internal shoulder 30. The ends 21 of each of the apertures 20a intersects the internal shoulder wall 30 and curves to blend into the aperture 20a.

[0090] In this embodiment, the internal shoulder wall 30, and curved aperture ends 21 collectively form the means for directing dust, dirt and debris in the drum 1 towards the apertures 20a. In use, any dust, dirt and debris will roll around in the drum 1 as it rotates, eventually running against the internal shoulder wall 30 until it meets one of the curved aperture ends 21 , which will then direct this material into its respective aperture 20a, through which aperture 20a the dust, dirt and debris may pass out of the drum la.

[0091] Referring now to Figure 10, where there is illustrated a brake drum 1b according to a further embodiment. Those parts of the brake drum 1b which are identical to those of brake drum 1 of Figures 1 through 6, will be denoted by the same reference numbers, and will not be described in detail again here.

[0092] In this embodiment, each of first type of through apertures 20b is elongated, with a direction of elongation extending in a direction around the drum 1b, and terminating at a pair of ends 23.

[0093] The ends 23 of each of the apertures 20b are rounded with a semi-circular shape that intersects the internal shoulder 30 tangentially so that each of the apertures 20b bounds and intersects the internal shoulder wall 30 along an edge thereof.

[0094] In this embodiment, the internal shoulder 30, and curved rounded ends 23 collectively form the means for directing dust, dirt and debris in the drum 1 towards the apertures 20b. In use, any dust, dirt and debris will roll around in the drum 1 as it rotates, eventually running against the internal shoulder wall 30 until it meets one of the rounded aperture ends 23, which will then direct this material into its respective aperture 20b, through which aperture 20b the dust, dirt and debris may pass out of the drum 1b.

[0095] Advantageously, the present disclosure provides a vehicle brake drum provided with means for clearing itself of dust and debris of varying sizes, ranging from brake lining material dust particles right through to rocks and stones, thereby aiding brake system performance, reducing brake system wear, and reducing the likelihood of brake system component failures.

[0096] Throughout the specification and the claims that follow, unless the context requires otherwise, the words “comprise” and “include” and variations such as “comprising” and “including” will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers.

[0097] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement of any form of suggestion that such prior art forms part of the common general knowledge.

[0098] It will be appreciated by those skilled in the art that the invention is not restricted in its use to the particular application described. Neither is the present invention restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein. It will be appreciated that the invention is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the invention as set forth and defined by the following claims.