BACKGROUND TO THE INVENTION

This invention relates to the field of motorcycles. More particularly, the present invention relates to wheel lift angle control system, with which a so-called “wheelie” manoeuvre is controlled.

A “wheelie” is a well-known manoeuvre in the field of motorcycling (both conventional two-wheel motorcycles and quadbikes (the term “vehicle” used herein will be taken to refer to either, or further suitable types of vehicles, cars or the like)) and relates to driving the vehicle on the rear wheel(s) only, with the front wheel(s) lifted off the ground.

A certain amount of skill on the part of the rider is required to perform a wheelie. Generally, power to the rear wheel(s) is provided to lift the front wheel(s) from the ground, while the rear brake is modulated to prevent the vehicle from tipping over backwards. The balance between power and brake modulation, coupled with physically balancing the vehicle in an upright position, while driving in a forwards direction, requires practice and dexterity.

Becoming adept with performing a wheelie is often a time-consuming process. Often, a rider will not successfully modulate the brakes in time, causing the vehicle to tip over backwards, potentially resulting in damage to the vehicle, or injury to the driver.

It is accordingly an object of the invention to provide lift angle control system and a method of controlling a lift angle of a vehicle that will, at least partially, address the above disadvantages, or to assist a rider in becoming adept with performing a wheelie manoeuvre.

It is also an object of the invention to provide a lift angle control system and a method of controlling a lift angle of a vehicle which will provide useful alternatives to existing lift angle control systems and/or methods. SUMMARY OF THE INVENTION

In accordance with a first aspect of the invention there is provided a lift angle control system for a vehicle, the lift angle control system comprising: a measuring unit operatively fitted to the vehicle and configured to measure a variable; a controller, configured operatively to receive data relating to the measured variable from the measuring unit, and to provide an output based on a predetermined rule; and an actuator used to modulate a brake system associated with a rear wheel of the vehicle, in accordance with the output of the controller.

The measuring unit may comprises one of a gyroscope and an accelerometer, and may be configured to measure a lift angle of the vehicle. The variable may there be, or be related to, the lift angle. Further variables may be measured.

The predetermined rule may relate to a braking force to be applied via the actuator based on the measured lift angle of the vehicle. The predetermined rule may comprise a stepwise function including: a first step of applying no braking force when the lift angle is within a first range of angles; and a second step of applying a first amount of braking force when the lift angle is within a second range of angles.

The first amount of braking force is between 20% and 50% of a maximum braking force, such as about 30% of the maximum braking force.

The first range of angles may be between zero degrees and a first threshold angle, which may typically be between 60 and 70 degrees (such as about 65 degrees), while the second range of angles may be between the first threshold angle and a second threshold angle, which may typically be between 70 and 80 degrees (such as 75 degrees). Other threshold angles and ranges may be possible.

The predetermined rule may furthermore comprise: a third step of applying a second amount of braking force when the lift angle is within a third range of angles; and a fourth step of applying a third amount of braking force when the lift angle is within a fourth range of angles.

The second amount of braking force may be between 40% and 80% of a maximum braking force, such as about 70% of a maximum braking force.

The third amount of braking force may be above 90% of the maximum braking force and may typically be about 100% of the maximum braking force.

The third range of angles may be between the second threshold angle and a third threshold angle, which may be between 80 and 90 degrees (such as 85 degrees) while the fourth range may be any angle exceeding the third threshold angle. In some cases, the third threshold angle may exceed 90 degrees.

The predetermined rule may further comprise a step of activating a kill switch or a clutch mechanism when the lift angle is within a predetermined range of angles. This will typically be associated with the third threshold angle, (or in cases where there are more or fewer than three threshold angles, the last threshold angle).

In one example, the actuator may comprise a digital servo mounted relative to a master cylinder unit associated with the rear brake of the vehicle. The digital servo may be provided in data communication with the controller.

Furthermore, the digital servo may comprise an actuating arm which may be interconnected with a lever arm of the master cylinder unit by means of a connection rod. The connection rod may operatively transfer or translate actuation of the actuating arm of the digital servo to the lever arm of the master cylinder unit.

The master cylinder unit may be provided in fluid flow communication with a brake calliper arrangement of the rear brake of the vehicle.

In an alternative example, the actuator may comprise an actuator assembly including a stepper motor, a piston and a cylinder housing comprising a cylinder within which the piston is at least partially received. The stepper motor may comprise a shaft with a threaded portion acting as a power screw and the piston may have a threaded hole for receiving the threaded portion of the shaft. The configuration may be such that operative rotation of the shaft relative to the piston causes the piston to be actuated linearly.

The cylinder may comprise a longitudinally extending locating slot. The piston may be associated with a locating pin operatively received within the locating slot. Operative interaction between the locating slot and locating pin may inhibit rotation of the piston relative to the cylinder.

The cylinder may be provided in fluid flow communication with a brake calliper arrangement of the rear brake of the vehicle.

The cylinder housing may comprise an internal compartment within which the controller and/or other hardware, such as the measuring unit, may be received.

The system may further comprise an input module for adjusting variables associated with the predetermined rule. The controller may comprise means for communicating with the input module in the form of a wireless communication module, such as a Bluetooth communication module, WiFi communication module or GSM communication module.

In accordance with a second aspect of the invention there is provided a method of controlling a lift angle of a vehicle, the method comprising: measuring a lift angle of the vehicle while the vehicle is moving; controlling, based on the measured lift angle and in accordance with a predetermined rule, an actuator, thereby to modulate a brake system associated with a rear wheel of the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a schematic layout of a lift angle control system for a vehicle in accordance with a first example embodiment of the invention;

Figure 2 shows a schematic layout of a lift angle control system for a vehicle in accordance with a second example embodiment of the invention;

Figure 3 shows a perspective view of a stepper motor and piston arrangement forming part of an actuator assembly of the lift angle control system of Figure 2;

Figure 4 shows a perspective view of a cylinder housing arrangement forming part of the actuator assembly of the lift angle control system of Figure 2;

Figure 5 shows a side view of a motorcycle fitted with the lift angle control system of Figure 1 or 2, while performing a “wheelie” manoeuvre; and

Figure 6 shows a schematic representation of threshold angles and ranges of angles used when calculating outputs in accordance with a predetermined rule, when using the lift angle control system of Figure 1 or 2.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "mounted", "connected", "engaged" and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings and are thus intended to include direct connections between two members without any other members interposed therebetween and indirect connections between members in which one or more other members are interposed therebetween. Further, "connected" and "engaged" are not restricted to physical or mechanical connections or couplings. Additionally, the words "lower", "upper", "upward", "down" and "downward" designate directions in the drawings to which reference is made. The terminology includes the words specifically mentioned above, derivatives thereof, and words or similar import. It is noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the," and any singular use of any word, include plural referents unless expressly and unequivocally limited to one referent. As used herein, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.

Referring to the drawings, in which like numerals indicate like features, a non-limiting example of a lift angle control system for a vehicle (hereinafter simply referred to as “system”) in accordance with the invention is generally indicated by reference numeral 10. A first example embodiment of the system 10 is shown in figure 1 while a second example embodiment of the system 10 is shown in figure 2.

The vehicle shown in the example is a conventional motorcycle 12. It will however be understood that the system 10 can find application with vehicles of other types as well, such as quad bikes or even other motorised vehicles such as cars, trucks or the like. Any features described with reference to the motorcycle 12 will therefore be understood to be applicable when the system is used with such other type of vehicle.

For the purpose hereof, a “lift angle” will be designated by reference numeral 14 and will be understood to refer to an angle, measured from a rear wheel 16, by which front wheel 18 is lifted from a surface 20 on which the motorcycle 12 is supported. The lift angle 14 therefore also relates generally to the angle of the body the motorcycle 12 relative to the surface 20.

The system 10 comprises a measuring unit 22 which is fitted to the motorcycle 12, and which is configured to measure a variable when the motorcycle 12 is used. Typically, the variable relates to the lift angle 14. It will be understood, however, that other variables, such as acceleration of the motorcycle 12 and the like may also be measured by the measuring unit 22. The measuring unit 22 typically comprises a gyroscope and/or an accelerometer.

The measuring unit 22 provides inputs and data to a controller 24. It will be understood that the measuring unit 22 and the controller 24 may be provided as a single, integrated unit, which may be provided in a sealed housing to protect same from elements typically encountered during use of the motorcycle 12 (such as dust, water, mud, and the like). Alternatively, the measuring unit 22 and controller 24 may constitute separate units.

The controller 24 is configured to provide an output to an actuator 26. The output is derived by utilising the data relating to the measured variable and calculated in accordance with a predetermined rule. More is said about this below.

The actuator 26, on the other hand, is provided to modulate a brake system 28 of the motorcycle 12, and more particularly, a rear wheel 16 brake system of the motorcycle 12, in accordance with the output received from the controller 24.

In the first example embodiment of the system 10 shown in figure 1 , the actuator 26 takes the form of a servo, such as a digital servo 30, which is mounted relative to a master cylinder unit 32 of the brake system 28. A communication line or cable 34 is provided between the controller 24 and the digital servo 30, with which the outputs of the controller 24 are communicated to the digital servo 30.

The digital servo 30 actuating arm 36 is interconnected with a lever arm 38 of the master cylinder unit 32, via a connection rod 40. Therefore, displacement of the actuating arm 36 is translated to the lever arm 38, by means of the connection rod 40. Therefore, the digital servo 30 can be used, mechanically and physically, to control the master cylinder unit 32 and therefore the brake system 28 associated with the rear wheel 16 of the motorcycle 12.

A hydraulic line 42 connects the master cylinder unit 32 to a rear brake master cylinder 44, in known fashion.

In the second example embodiment of the system 10 shown in figure 2, the actuator 26 takes the form of an actuator assembly 72 including a stepper motor 74 and a cylinder housing 76. The stepper motor 74 comprises a shaft 78 with a threaded portion 80 acting as a power screw. The assembly 72 includes a piston 82 associated with seals 84 and a threaded hole 86 for receiving the threaded portion 80 of the shaft 78. The piston 82 also has a locating pin 88. The controller 24 communicates with the stepper motor 74 by means of a communication line 90.

The cylinder housing 76 comprises a cylinder 92 which is provided with a longitudinally extending locating slot 94. Typically, the slot does not extend the whole length or depth of the cylinder. The piston 82 is received within the cylinder 92, with the locating pin 88 located within the slot 94. Interaction between the locating pin 88 and the slot inhibits rotation of the piston 82 within the cylinder 92.

Rotation of the shaft 78 therefore causes interaction between the threaded portion 80 and the threaded hole 86 in turn resulting in linear actuation of the piston 82 within the cylinder, which causes hydraulic pressure to be exerted on the rear brake master cylinder 44.

By using a stepper motor 74, the position of the piston 82 and therefore the amount of braking provided to the rear wheel 16 can very carefully be controlled. The actuator assembly 72 is also relatively compact and may even be integrally formed with the rear brake master cylinder (this is not shown).

The cylinder housing 76 comprises an internal compartment 96 within which some components of the system 10, such as the measuring unit 22 and/or the controller may be located.

It will be appreciated that the predetermined rule relates to a lift angle 14 which a rider of the motorcycle 12 is comfortable with, given its level of expertise. Therefore, the predetermined rule may be determined or adjusted by the rider. Values provided below are examples only.

In general terms, the predetermined rule determines an amount of braking force that needs to be applied by the brakes of the rear wheel 16 of the motorcycle 12 to inhibit the motorcycle from exceeding a predetermined lift angle or even to inhibit the motorcycle from tipping over backwards and depends on the measured lift angle 14. It will be appreciated that the amount of braking force applied by the braking system 28, relates directly to the amount by which the actuating arm 36 and therefore the lever arm 38 or piston 82, as the case may be depending on the embodiment used, is displaced or actuated. Typically, the predetermined rule is defined by various ranges of lift angles 14.

In the example provided below, the predetermined rule comprises a step function, in which the braking force associated with each specific step is kept constant. However, it will be appreciated that the braking force during each specific step of the step function may be variable and may furthermore be influenced by variables other than the lift angle 14. For example, acceleration, the speed at which the motorcycle is travelling, the rate of change of the lift angle 14, and the like, may all serve as inputs to or variables of the predetermined rule.

It will be appreciated that the surface 20 on which the motorcycle 12 is supported will be assumed to be horizontal, though in practice, the surface need not necessarily be horizontal. Relevant adjustments may be made to account for non-horizontal surfaces, should the need arise.

In the example, the step function of the predetermined rule comprises the following: applying no braking force when the lift angle 14 is within a first range of angles 46 (in the example between zero degrees 54 and a first threshold angle 56, which may typically be between 60 degrees and 70 degrees, and more specifically, may be 65 degrees); applying a first amount of braking force when the lift angle 14 is within a second range of angles 48 (in the example between the first threshold angle 56 and a second threshold angle 58, which may typically be between 70 degrees and 80 degrees, and more specifically, may be 75 degrees); applying a second amount of braking force when the lift angle is within a third range of angles 50 (in the example between the second threshold angle 58 and a third threshold angle 60, which may typically be between 80 degrees and 90 degrees, and more specifically, may be 85 degrees); applying a third amount of braking force when the lift angle is within a fourth range of angles 52 (in the example any angle exceeding the third threshold angle 60).

When the lift angle 14 is in the first range of angles 46, it is assumed that the rider has control over the motorcycle 12, and no intervention by the system 10 is required.

When the lift angle 14 is in the second range of angles 48, it is assumed that the rider still has control over the motorcycle 12 but is moving closer to a position where control may be lost or where the motorcycle 12 may tip over backwards. Therefore, a little intervention is provided by the system 10. When the lift angle 14 is in the third range of angles 50, it is assumed that the rider is very close to losing control over the motorcycle 12, and more intervention is provided by the system 10.

When the lift angle 14 is in the fourth range of angles 52, it is assumed that the rider has lost control over the motorcycle 12, and the system 10 applies a maximum braking force to immediately force the front wheel back to the surface 20.

Furthermore, when the lift angle 14 is in the fourth range of angles 52 the controller 24 may utilise an electronic relay (not shown) to engage a kill switch or a clutch to kill the motor or inhibit power to be transmitted to the rear wheel 16 of the motorcycle 12.

The predetermined rule may comprise fewer or further steps, and it will be appreciated that the last step (irrespective of the number of steps) will typically be a step associated with a maximum braking force and/or activation of a kill switch or clutch.

The first amount of braking force may be between 20% and 50% of a maximum braking force and may, typically, be about 30% of a maximum braking force. It will be appreciated though, that this need not be constant, and may vary in some cases, typically depending on further changes of the lift angle 14.

The second amount of braking force may be between 40% and 80% of a maximum braking force and may, typically, be about 70% of the maximum braking force.

The third amount of braking force may be 100% of the maximum braking force.

The system 10 may be calibrated by a user, and therefore, the first to third threshold angles (56, 58, 60) may be adjusted by the user.

T ypically, as a user becomes more adept with mastering the manoeuvre, the first to third threshold angles (56, 58, 60) may be increased, and may be adjusted to be closer to each other, such that the second and third ranges of angles (48, 50) may be smaller ranges.

The system 10 may comprise an input module 62 with which the user may adjust the first to third threshold angles (56, 58, 60). The input module 62 may be a mobile device, such as a mobile phone, tablet, or the like, which may communicate with the controller 24 by means of a wired or wireless communication protocol 64, such as Bluetooth, WiFi, or GSM. The controller 24 may be adapted to facilitate such communication.

The system may be powered by an on-board battery 66 of the motorcycle 12.

The system may be switched “on” by means of a switch (not shown) and may comprise an LED indicator light indicating the status of the system 10. The system 10 may also be provided in a “standby” mode. In this way, the system 10 will not interfere during normal operation of the motorcycle 12 but may be switched on when a wheelie manoeuvre will be attempted.

In use, a user will set the first to third threshold angles (56, 58, 60), and activate the system 10. Power to the rear wheel 16 of the motorcycle is increased rapidly, to cause the front wheel 18 to lift from the surface 20. The measuring unit 22 measures the lift angle (and any other variable throughout operation).

As the lift angle 14 increases, more and more intervention in the form of increased applied braking force is provided by the system 10, to ensure that the rider does not lose control over the motorcycle 12 causing same to tip over. In some cases of operation, the system 10 merely seeks to facilitate an equilibrium between torque provided by the engine and torque provided by the rear brakes.

When a critical angle is reached (associated with the fourth range of angles 52), the brakes are fully engaged, and the kill switch is used to kill the motor to cause the motorcycle rapidly to articulate forwards and onto the front wheel 18.

It will be appreciated that the above description only provides example embodiments of the invention and that there may be many variations without departing from the spirit and/or the scope of the invention. It is easily understood from the present application that the particular features of the present invention, as generally described and illustrated in the figures, can be arranged, and designed according to a wide variety of different configurations. In this way, the description of the present invention and the related figures are not provided to limit the scope of the invention but simply represent selected embodiments. The skilled person will understand that the technical characteristics of a given embodiment can in fact be combined with characteristics of another embodiment, unless otherwise expressed or it is evident that these characteristics are incompatible. Also, the technical characteristics described in a given embodiment can be isolated from the other characteristics of this embodiment unless otherwise expressed.