FIELD OF THE INVENTION

[0001] The present invention relates to an emergency disc brake assembly and, in particular, to a combined emergency brake assembly including a first mechanically or electrically operated emergency brake assembly fitted to a wheel hub of a vehicle for the purpose of providing a first emergency braking function, and a second electrically operated disc brake assembly configured to be fitted to a disc rotor associated with the vehicle wheel hub to provide a secondary emergency braking function, thereby improving the overall hold capability of the vehicle.

BACKGROUND OF THE INVENTION

[0002] Emergency brake assemblies in vehicles, also known as park brakes, parking brakes, and handbrakes, are assemblies used to lock one or more vehicle wheels to secure the vehicle in a parked (i.e. motionless) state. Such assemblies are typically operated by drivers after a vehicle has been parked (i.e. when a shift lever of the vehicle is in the “Park” position, thereby causing a parking pawl fitted to an automatic transmission of the vehicle to lock the transmission). A driver would typically utilise an emergency brake when the driver prefers to utilise an additional wheel lock mechanism to ensure that their vehicle is prevented from moving whilst in the parked state (i.e. in addition to locking the transmission using the parking pawl).

[0003] In an example, a driver may elect to operate an emergency brake assembly after parking their vehicle on a sloping surface. However, even when a vehicle is parked on a flat surface, it is generally considered good practice to operate the emergency braking system in view of the potential for the parking pawl to fail, e.g. due to stress, another vehicle colliding with the parked vehicle, etc. Emergency brakes can also be used in emergency situations whilst a vehicle is in motion, e.g. when regular brakes fail.

[0004] Conventional emergency brake assemblies are typically associated with the regular brake system of the vehicle (i.e. the brake system used to slow or stop the vehicle when the vehicle is in motion), although they operate to bypass the regular brake system. For example, a vehicle may include a drum brake on each rear wheel where each drum brake includes a drum that rotates together with the wheel, and two brake shoes of heat resistant material located inside the drum. Operation of the regular brake system causes the shoes to be compressed (e.g. moved in opposite radial directions towards the inner surface of the drum) until the shoes frictionally contact the drum inner surface to an extent that slows the rate of rotation of the drum (and hence the wheel and vehicle).

[0005] The emergency brake may be a mechanism incorporated into the drum brakes. In an example, the emergency brake includes a lever operatively positioned inside the drum that when actuated compresses the brake shoes and locks the brake shoes in their compressed position. A mechanical actuator, such as a manually operated handbrake or a park brake pedal, is used to trigger the lever from within the vehicle cab, which in turn causes the necessary force to be transm itted through the cables to the lever. In particular, when the cables are tightened, the lever is triggered, and the brake shoes are compressed as described above.

[0006] Another existing form of vehicle brake is a disc brake, which is an example of a hydraulic brake system typically used in vehicles. When a mechanical actuator inside the vehicle is operated, a caliper which contains a piston is operated to squeeze (compress) two brake pads towards one another and against the wheel rotor, which is positioned between the two brake pads. Friction between the pads and the rotor slows the rotor (and hence the wheel and vehicle) down. Similar to the mechanical actuator used in drum brake assemblies, disk brake assemblies may also utilise a mechanical actuator in order to lock the two brake pads in their compressed positions. For example, an emergency brake may involve the use of a piston configured to be pushed into the brake pads and thereby lock the brake pads in their compressed state.

[0007] Emergency brakes also typically utilise a self-locking system which ensures that the emergency brakes are not released unless the above-described mechanical actuator is released.

[0008] Electrical actuators for activating emergency brakes are also used in more modern vehicles where, rather than a mechanical actuator being used (such as a hand brake or foot pedal) to operate the emergency brakes, an electrical switch typically positioned on the vehicle dashboard is activated. [0009] Irrespective of the type of emergency brake assembly used in vehicles, a common problem exists, particularly in emergency brake assemblies used in 4WD and similar sized vehicles which regularly tow and/or carry heavy loads. The emergency brake assemblies fitted to such vehicles at the time of manufacture tend to underperform (i.e. fail to provide a sufficiently strong holding capability). This is mainly due to the factory fitted emergency brake assembly, which is typically associated with a drum or disc brake as described above, being undersized as compared with the size I weight of the vehicle.

[0010] The Applicant has recognised a need for an improved emergency brake system that is capable of providing sufficiently strong holding capability for vehicles such as 4WD and similar sized vehicles. The Applicant has further recognised a need to be able to increase the holding capability of an existing factory-fitted emergency brake system without the need to remove or replace the factory fitted emergency brake system.

[0011] It is an object of the present invention to overcome at least some of the aforementioned problems or to provide the public with a useful alternative.

[0012] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any suggestion, that the prior art forms part of the common general knowledge.

SUMMARY OF THE INVENTION

[0013] In a first aspect, the present invention provides an emergency brake assembly for locking a wheel hub of a stationary vehicle in a substantially motionless state, the wheel hub of the type having an associated disc rotor, the emergency brake assembly including a first emergency brake mechanically or electrically configured to, apply a radial pressing force on an inner surface of a drum that rotates correspondingly with the wheel hub for the purpose of substantially preventing rotation of the drum relative to the first emergency brake and hence substantially preventing rotation of the wheel hub, or apply an axial clamping force on an external surface of the disc rotor associated with the wheel hub for the purpose of substantially preventing rotation of the disc rotor relative to the first emergency brake and hence substantially preventing rotation of the wheel hub, and a second emergency brake that is electrically configured to apply an axial clamping force on an external surface of the disc rotor associated with the wheel hub for the purpose of substantially preventing rotation of the disc rotor relative to the second emergency brake and hence contributing further to substantially preventing rotation of the wheel hub, wherein the combination of forces applied by the first and second emergency brakes ensures that a sufficient force is applied to lock the wheel hub and thereby maintain the wheel hub in said substantially motionless state.

[0014] In an embodiment, the second emergency brake includes a main body positioned adjacent the disc rotor associated with the wheel hub.

[0015] In an embodiment, the second emergency brake further includes two brake pads associated with the main body, wherein the main body is positioned such that a portion of the disc rotor is positioned between the two brake pads.

[0016] In an embodiment, the second emergency brake further includes a piston moveable between a first position in which the two brake pads are spaced apart from one another and avoid contact with the rotor, and a second position wherein movement from the first to the second position causes the two brake pads to be compressed and make frictional contact with the rotor.

[0017] In an embodiment, the second emergency brake further includes an electrical activation means operatively connected to the piston to provide an electrical signal to activate the piston and thereby cause the piston to move from the first position to the second position, or from the second position to the first position to cause the two brake pads to release the rotor.

[0018] In an embodiment, the electrical activation means includes a solenoid operated valve configured when energized to activate the piston and thereby cause the piston to move from the first to the second position, and configured when de-energized to cause the piston to move from the second to the first position.

[0019] In an embodiment, the solenoid is energized when the activation signal is received from an associated control module.

[0020] In an embodiment, the control module transmits the activation signal to the solenoid when an activation switch located inside a cabin of the vehicle is operated.

[0021] In an embodiment, the control module is further configured to control the clamping pressure of the piston and a run time of the solenoid according to predefined parameters.

[0022] In an embodiment, the control module is further configured to monitor a vehicle ignition status and operate the emergency disc brake assembly based upon the vehicle ignition status.

[0023] In an embodiment, when the vehicle ignition is cycled to off, the emergency disc brake assembly will automatically operate to provide an electrical signal that activates the piston to move from the first to the second position.

[0024] In an embodiment, when the vehicle ignition is cycled to on, the emergency disc brake assembly will automatically operate to provide an electrical signal that activates the piston to move from the second to the first position.

[0025] In an embodiment, the second emergency brake is further configured to perform regular braking functions in addition to emergency braking functions, by causing the rotating rotor to reduce its rate of rotation when the emergency disc brake assembly is operated to cause the two brake pads to frictional ly engage the rotor. [0026] In an embodiment, when the first emergency brake is configured to apply a radial pressing force on the inner surface of the drum, the drum forms part of a drum brake assembly that includes one or more brake shoes disposed inside the drum, the brake shoe(s) configured to be moved radially outwardly until the shoe(s) frictionally engage the inner surface of the drum to an extent that slows a rate of rotation of the drum .

[0027] In an embodiment, the drum brake assembly further includes a lever operatively positioned inside the drum brake assembly that when actuated, when the vehicle is stationary and the wheel hub is substantially motionless, causes the brake shoe(s) to be moved radially outwardly until the shoe(s) frictionally engage the inner surface of the drum to an extent that maintains the wheel hub in said motionless state.

[0028] In an embodiment, when the first emergency brake is configured to apply an axial clamping force on an external surface of the disc rotor, the disc rotor forms part of a disk brake assembly that includes a caliper containing a piston that is configured to compress two brake pads towards one another and against the wheel rotor which is positioned between the two brake pads to an extent that slows a rate of rotation of the drum.

[0029] In an embodiment, activation of the first emergency brake, when the vehicle is stationary and the wheel hub is substantially motionless, causes the two brake pads to be compressed until they frictionally engage the disc rotor to an extent that maintains the wheel hub in said motionless state.

[0030] In an embodiment, the first emergency brake is operable independently of the second emergency brake.

[0031] According to a second aspect, the present invention provides an emergency brake assembly for use in maintaining a vehicle wheel hub in a substantially motionless state, the assembly including, a first emergency brake including, a mechanically or electrically operated drum brake assembly associated with the wheel hub, the drum brake assembly including a drum that rotates together with the wheel hub, and one or more brake shoes disposed inside the drum configured to be moved radially outwardly until the shoe(s) frictionally engage an internal surface of the drum, wherein the force exerted by the brake shoe(s) represents a first contribution towards maintaining the wheel hub in said substantially motionless state, and a second emergency brake including, a main body positioned adjacent a rotor associated with the wheel hub, the wheel rotor being rotatable together with the wheel hub such that when the wheel hub is rotated, the rotor is also caused to rotate, two brake pads associated with the main body, wherein the main body is positioned such that a portion of the wheel rotor is positioned between the two brake pads, a piston moveable between a first position in which the two brake pads are spaced apart from one another and avoid contact with the rotor, and a second position in which the two brake pads are compressed and make frictional contact with the rotor, an electrical activation means operatively connected to the piston to provide an electrical signal to activate the piston and thereby cause the piston to move from the first position to the second position to cause the two brake pads to compress and substantially prevent the rotor from rotating, wherein the force exerted by the two brake pads represents a further contribution towards maintaining the wheel hub in said motionless state, or from the second position to the first position to cause the two brake pads to release the rotor, and wherein the combined force of the first and second emergency brakes is sufficient to lock the wheel hub and maintain the wheel hub in the substantially motionless state.

[0032] In a third aspect, the present invention provides an emergency brake assembly for use in maintaining a vehicle wheel hub in a substantially motionless state, the assembly including, a first emergency brake including, an electrically operated disk brake associated with the wheel hub, the disk brake including a caliper containing a piston that is configured to compress two brake pads towards one another and against the wheel rotor which is positioned between the two brake pads, wherein the force exerted by the brake shoe(s) represents a first contribution towards maintaining the wheel hub in said substantially motionless state, and a second emergency brake including, a main body positioned adjacent a rotor associated with the wheel hub, the wheel rotor being rotatable together with the wheel hub such that when the wheel hub is rotated, the rotor is also caused to rotate, two brake pads associated with the main body, wherein the main body is positioned such that a portion of the wheel rotor is positioned between the two brake pads, a piston moveable between a first position in which the two brake pads are spaced apart from one another and avoid contact with the rotor, and a second position in which the two brake pads are compressed and make frictional contact with the rotor, an electrical activation means operatively connected to the piston to provide an electrical signal to activate the piston and thereby cause the piston to move from the first position to the second position to cause the two brake pads to compress and substantially prevent the rotor from rotating, wherein the force exerted by the two brake pads represents a further contribution towards maintaining the wheel hub in said motionless state, or from the second position to the first position to cause the two brake pads to release the rotor, and wherein the combined force of the first and second emergency brakes is sufficient to lock the wheel hub and maintain the wheel hub in the substantially motionless state.

[0033] In a fourth aspect, the present invention provides an electrically operated emergency disc brake assembly for use in locking a vehicle wheel hub in a substantially motionless state, the wheel hub having a first emergency brake configured to maintain the vehicle wheel hub in said substantially motionless state, the assembly including, a main body positioned adjacent a rotor associated with the wheel hub, the wheel rotor being rotatable together with the wheel hub such that when the wheel hub is rotated, the rotor is also caused to rotate, two brake pads associated with the main body, wherein the main body is positioned such that a portion of the wheel rotor is positioned between the two brake pads, a piston moveable between a first position in which the two brake pads are spaced apart from one another and avoid contact with the rotor, and a second position in which the two brake pads are compressed and make frictional contact with the rotor, an electrical means operatively connected to the piston to provide an electrical signal to activate the piston and thereby cause the piston to move from the first position to the second position to cause the two brake pads to substantially prevent the rotor from rotating and thereby lock the wheel hub in said motionless state, or from the second position to the first position to cause the two brake pads to release the rotor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Features of the present disclosure are illustrated by way of example and not limited in the following figure(s), in which like numerals indicate like elements, in which:

[0035] Figure 1 illustrates a perspective view of a vehicle wheel hub including an emergency brake assembly configured in accordance with an embodiment of the present invention, the assembly including first emergency drum brake and a second electronic emergency disk brake fitted to work in combination.

[0036] Figure 2 illustrates a side view of the vehicle wheel hub and emergency brake assemblies of Figure 1.

[0037] Figure 3 illustrates a rear perspective view of the second electronic emergency disk brake of Figure 1 in a partially disassembled state, the second emergency disk brake including an electric solenoid.

[0038] Figure 4 illustrates a front perspective view of the second electronic emergency disc brake of Figure 1 in a partially disassembled state, the second emergency disk brake including a piston that is activated by the electric solenoid shown in Figure 3.

[0039] Figure 5 illustrates a cross-sectional view of the second electronic emergency disc brake forming part of the emergency brake assembly of Figures 1 and 2.

[0040] Figure 6 illustrates a schematic diagram of an exemplary emergency brake system including a controller and associated control switch for activating the second electronic emergency disk brake which forms part of the emergency brake assembly of Figures 1 and 2.

DETAILED DESCRIPTION OF EMBODIMENT(S) OF THE INVENTION

[0041] For simplicity and illustrative purposes, the present disclosure is described by referring to embodiment(s) thereof. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the disclosure. It will be readily apparent, however, that the current disclosure may be practised without limitation to the specific details disclosed herein. In other instances, some methods and structures have not been described in detail to avoid obscuring the disclosure.

[0042] The present invention relates to an emergency brake assembly 10 for a vehicle (not shown), including a first emergency brake 40 which in the embodiment shown is in the form of a drum brake assembly 40, and a second emergency brake in the form of an electronic disk brake assembly 11. The emergency brake assembly 10 is configured to maintain a vehicle wheel hub 12 in a substantially motionless state when the vehicle is parked. In particular, the assembly 10 provides improved emergency braking capability by combining the braking force of the first emergency brake (e.g. the emergency brake associated with the drum brake assembly 40) with the second electronic emergency disk brake assembly 11 which is configured to apply an axial clamping force on an external surface 14 of a wheel rotor 16 associated with the wheel hub 12, when the wheel hub 12 is substantially motionless. The clamping force combined with the existing braking force of the first emergency brake associated with assembly 40 is sufficient to substantially prevent rotation of the rotor 16 relative to the assembly 11 , even when the vehicle has an attached heavy load (e.g. carrying or towing a heavy load), thereby providing superior holding capability.

[0043] The skilled addressee will appreciate that the wheel rotor 16 rotates together with the wheel hub 12 such that when the wheel axle and associated hub 12 are rotated, the rotor 16 is also caused to rotate. By locking the rotor 16 through the use of the first 40 and the second 11 emergency brakes, the wheel hub 12 and hence the vehicle will be substantially prevented from moving.

[0044] The emergency brake assembly 10 is shown mounted to a wheel hub 12 in Figures 1 and 2, whilst the second emergency brake (in the form of an electronic emergency disk brake 11 ) is shown in isolation in Figures 3 to 5. [0045] In the embodiments shown, the first emergency brake is in the form of a factory installed emergency brake associated with a regular drum brake assembly 40 of the vehicle, such that only the second emergency brake needs to be integrated in order to provide the benefits described herein. However, it is to be understood that whilst the embodiment illustrated and described herein relates to a vehicle wheel hub 12 having a factory fitted first emergency brake installed, and wherein a second emergency brake is integrated in order to improve the total hold capability of the vehicle, the present invention is not intended to be limited solely to this application.

[0046] For example, a vehicle may have the emergency brake assembly 10 of the present invention, including both the first and second emergency brakes, fitted to one or more wheels of the vehicle as standard. In another example, the emergency brake assembly 10 including both the first and second emergency brakes, may be provided as a replacement assembly to an existing emergency brake system associated with a vehicle such that the existing emergency brake system is removed and replaced in its entirety.

[0047] In the example where the first emergency brake is a drum brake, it will be known that the drum brake assembly 40 typically includes an emergency brake component in the form of a lever (not shown) which is mechanically activated via cable 42. The cable 42 may, for example, be triggered by operation of a manual actuator in the driver cabin such as a hand brake or foot pedal, as previously described. Operation of the lever causes one or more brake shoes 44 to apply a radial pressing force against an internal surface of the drum 46 that rotates together with the wheel hub 12. The lever is operatively positioned inside the drum 46 such that when actuated, i.e. when the vehicle is not moving and the wheel hub is substantially motionless, the lever causes the brake shoes 44 to be moved radially outwardly until the shoe(s) fictionally engage the internal surface of the drum 46 to an extent that maintains the wheel hub in the motionless state, and hence locks the wheel hub(s) 12 preventing movement of the vehicle. Drum brakes and their associated emergency braking components will be known by persons skilled in the art and hence will not be described in detail in the interest of brevity.

[0048] In the embodiments shown, the second emergency brake assembly 11 includes a main caliper body 18 mounted adjacent the rotor 16 of the wheel hub 12, and two brake pads 20 associated with the main body 18, wherein the main body 18 is positioned such that a portion of the wheel rotor 16 is positioned in the space 21 between the two brake pads 20. The assembly 11 further includes a piston 22 (shown in Figures 4 and 5) moveable between a first position in which the two brake pads 20 are spaced apart from one another and avoid contact with the rotor 16, in the direction of arrows 24 to a second position in which the two brake pads 20 are caused to be compressed in opposite directions 25 to make frictional contact with the rotor 16. The working of the caliper mechanism, and in particular the ability of the caliper to cause two brake pads 20 to move in opposite directions 25 towards one another based on a force being applied only to one brake pad, is generally known in the art and hence will not be described in greater detail.

[0049] The emergency disc brake 11 is electrically operated and includes an electrical means of activating the piston 22. For example, an electric solenoid operated valve 26 may be operatively connected to the piston 22 to provide an electrical signal to activate the piston 22, and thereby cause the piston 22 to move from the first position to the second position to cause the two brake pads 20 to substantially prevent the rotor 16 from rotating (i.e. in addition to operation of the first emergency brake whose purpose is also to prevent the rotor 16 from rotating) and thereby maintaining the wheel hub 12 in a motionless state, or from the second position to the first position to cause the two brake pads 20 to release the rotor 16.

[0050] The skilled addressee would understand that the solenoid operated valve 26 is configured to be energized to activate the piston 22 and thereby cause the piston 22 to move from the first to the second position, and configured when de-energized to cause the piston 22 to move from the second to the first position.

[0051] The solenoid 26 may be energized when an activation signal is received from an associated control module 28 via wiring 29, as shown in Figure 6. In this regard, the control module 28 may transmit the activation signal to the solenoid 26 when a driver of the vehicle operates an activation switch 30 located inside a cabin of the vehicle. The control module 28 may also be used to control the clamping pressure of the piston 22 and a run time of the solenoid 26 according to predefined parameters that are programmed into the control module 28.

[0052] The control module 28 may also be used to monitor a vehicle ignition status, and operate the emergency disc brake 11 automatically when appropriate. For example, when the vehicle ignition is cycled to off, the control module 28 may be programmed to automatically provide an electrical signal that activates the piston 22 to move in the direction of arrows 24 from the first to the second position (and thereby engage the second emergency brake 11 ). Similarly, when the vehicle ignition is cycled to on, the control module 28 may automatically provide an electrical signal that activates the piston 22 to move in an opposite direction to arrows 24 from the second to the first position.

[0053] Accordingly, in the embodiment shown in Figures 1 and 2, it will be appreciated that the wheel hub 12 includes a combination of two emergency brakes that are working together to improve the hold capability of the vehicle when parked. In the embodiment shown, the first brake is a mechanically operated emergency brake configured to cause one or more brake shoes 44 to apply a radial pressing force against an internal surface of a drum 46 that rotates together with the wheel hub 12, and the second is the electrically operated emergency disc brake 11 also shown in isolation in Figures 3 to 5.

[0054] In summary, the embodiment shown in Figures 1 and 2 represents an example in which the first drum brake 40 (and incorporated additional emergency brake assembly) is an existing emergency brake assembly incorporated into the wheel hub 12 at the time of manufacture (i.e. factory installed), where the second emergency disc brake 11 (together with control module 28 and control switch 30) are installed as an aftermarket option, e.g. as a kit, in order to improve the holding capability of the vehicle. In the alternative embodiment, the first emergency brake may be installed together with the second emergency brake 11 such that both are installed together as a new vehicle or an aftermarket offering. Irrespective, significant holding capability improvements are achievable when using the combination of emergency brakes in the described manner.

[0055] It is to be understood that the first emergency brake need not be of the brake drum or mechanically operable types. For example, a brake drum assembly could equally well be electrically operable, and a regular disc brake assembly (not shown) could equally be used instead of the brake drum assembly 40 illustrated and described herein. In this regard, a regular disc brake assembly may include a caliper which contains a piston that is configured to compress two brake pads towards one another and against the wheel rotor positioned between the two brake pads to an extent that slows a rate of rotation of the drum when the vehicle is braking. The disc brake assembly may incorporate an emergency brake assembly that when actuated, i.e. when the vehicle is not moving and each wheel hub is substantially motionless, causes the two brake pads to fictionally engage the rotor to an extent that maintains the wheel hub in said motionless state.

[0056] The second emergency brake 11 may be operated independently of the first emergency brake 40 associated with the same wheel hub 12. However, in order to make use of the combined holding capability of the emergency disc brake assembly 10, both emergency brakes mounted on the same wheel hub 12 will be operating simultaneously to substantially prevent rotation of the wheel hub 12, as shown in Figures 1 -2.

[0057] There are various different means by which the first and emergency brakes may be operated. For example, if the first emergency brake forms part of an existing manual drum brake, as illustrated and described herein, then the first emergency brake may be operated as a first step using the existing mechanical activation (e.g. park brake lever), and the second emergency brake may be activated as a second step (e.g. by pressing an electronic switch in the cabin). In another example where both emergency brakes are electrically operable, then a single switch may exist in the vehicle cabin that when pressed activates both emergency brakes simultaneously. The present invention is not intended to be limited to any one sequence or means by which to operate the two (or more) emergency brakes that form part of the emergency brake assembly 10 of the present invention.

[0058] The skilled addressee will appreciate the advantages of using an emergency disc brake assembly 10 in the manner described herein. The use of the second emergency disc brake assembly 11 , in addition to and in combination with an additional (e.g. factory fitted) emergency brake, significantly improves the hold capability when the vehicle emergency brakes are engaged. This reduces stress on the gearbox parking pawl, which is very important given that when the parking pawl is stressed to a point that it fails, the vehicle (particularly when parked on a sloping surface) may begin to roll. A heavy vehicle such as a 4WD that is rolling uncontrollably is likely to cause significant damage not only to the vehicle itself, but to anything and anyone located in the path of the moving vehicle. In extreme cases, vehicles parked on steep slopes (such as steep driveways) whose emergency brakes fail and are therefore no longer capable of holding the vehicle, have been known to cause significant injury and even death due to the vehicle rolling backwards without warning. [0059] Throughout this specification and claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to mean the inclusion of a stated feature or step, or group of features or steps, but not the exclusion of any other feature or step, or group of features or steps.

[0060] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any suggestion that the prior art forms part of the common general knowledge.