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Title:
A BRAKING CONTROL SYSTEM
Document Type and Number:
WIPO Patent Application WO/2018/029472
Kind Code:
A1
Abstract:
The present invention relates to a braking control system for a vehicle. The vehicle comprises a brake pedal that is pivotable to adjust the braking of said vehicle. The braking control system comprises an actuator configured to couple to said brake pedal such that the actuator is operable to exert a force on said brake pedal to adjust the braking of said vehicle.

Inventors:
IRINICS, Aleks (Unit 2, Banbury CrossSoutham Road,Banbury, Oxfordshire OX15 2SN, OX15 2SN, GB)
Application Number:
GB2017/052350
Publication Date:
February 15, 2018
Filing Date:
August 09, 2017
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
ARRIVAL LIMITED (Unit 2, Banbury CrossSoutham Road,Banbury, Oxfordshire OX16 2SN, OX16 2SN, GB)
International Classes:
B60T7/10; B60T11/18; B60T13/74
Foreign References:
FR3029478A12016-06-10
DE2459187A11976-06-16
DE10113346A12002-09-26
JP2011219064A2011-11-04
DE2640768A11978-03-16
DE102004011622A12005-03-31
GB2011563A1979-07-11
DE102013019843A12015-05-28
CN204641422U2015-09-16
JP2011225012A2011-11-10
DE102010040854A12012-03-22
Attorney, Agent or Firm:
HUDSON, George et al. (Venner Shipley LLP, 200 Aldersgate, London EC1A 4HD, EC1A 4HD, GB)
Download PDF:
Claims:
Claims

1. A braking control system for a vehicle, said vehicle comprising a brake pedal that is pivotable about a rotational axis to adjust the braking of said vehicle, wherein the braking control system comprises an actuator configured to couple to said brake pedal such that the actuator is operable to exert a force on said brake pedal to adjust the braking of said vehicle, wherein the actuator comprises an electric motor and a gear assembly configured to couple the electric motor to said brake pedal, wherein the gear assembly comprises first and second gears, wherein the first gear is fixed relative to said brake pedal and is pivotable about said rotational axis and wherein the electric motor is configured to drive the second gear to exert a force on the first gear.

2. A braking control system according to claim 1, wherein said brake pedal comprises a lever and a foot portion at one end of said lever, wherein the actuator is configured to couple to said lever.

3. A braking control system according to claim 2, wherein the actuator is configured to act on said lever to exert said force on the brake pedal.

4. A braking control system according to claim 3, wherein the first gear is fixed to said lever.

5. A braking control system according to claim 2, wherein said lever is connected to a shaft such that the brake pedal is pivotable about the rotational axis of the shaft to adjust the braking of said vehicle, wherein the actuator is configured to act on said shaft to exert said force on the brake pedal.

6. A braking control system according claim 5, wherein the first gear is fixed to said shaft of the brake pedal. 7. A braking control system according to any of claims 1 to 6, wherein the first gear is arcuate.

8. A braking control system according to any of claims 1 to 7, wherein the electric motor comprises a servo motor.

9. A braking control system according to any preceding claim, wherein the actuator is electrically controllable.

10. A braking control system according to any preceding claim, comprising a controller configured to control operation of the actuator.

11. A braking control system according to claim 10, wherein the controller is configured to adjust the force exerted on the brake pedal by the actuator in accordance with information indicative of an operating condition of the vehicle.

12. A braking control system according to claim 11, wherein said information indicative of an operating condition of the vehicle comprises information indicative of an operating condition of the brake pedal.

13. A braking control system according to claim 12, comprising a pedal sensor that is connected to the controller and is configured to detect said information indicative of an operating condition of the brake pedal.

14. A braking control system according to claim 13, wherein the pedal sensor is configured to detect information indicative of the position of the brake pedal.

15. A braking control system according to claim 13 or claim 14, wherein the pedal sensor is configured to detect information indicative of the velocity and/ or acceleration of the brake pedal.

16. A braking control system according to any of claims 13 to 15, wherein the pedal sensor is configured to detect information indicative of the force applied to the brake pedal by the driver.

17. A braking control system according to any of claims 11 to 16, wherein said vehicle is powered by an electric motor, and wherein said information indicative of an operating condition of the vehicle comprises information indicative of the level of regenerative braking available from said electric motor.

18. A braking control system according to any of claims 11 to 17, wherein said information indicative of an operating condition of the vehicle comprises information indicative of the location of said vehicle. 19. A braking control system according to any of claims 11 to 18, wherein the braking control system comprises an obstacle detection system, and wherein said information indicative of an operating condition of the vehicle comprises information indicative of a collision with an obstacle detected by the obstacle detection system. 20. A braking control system according to any preceding claim, wherein said vehicle is powered by an electric motor.

21. A braking control system according to any preceding claim, wherein the braking control system is configured for autonomous vehicle operation.

22. A braking control system for a vehicle, said vehicle comprising a brake pedal that is pivotable about a rotational axis to adjust the braking of said vehicle, wherein the braking control system comprises an actuator configured to couple to said brake pedal such that the actuator is operable to exert a force on said brake pedal to adjust the braking of said vehicle.

23. A braking control system according to claim 22, wherein the actuator comprises a hydraulic actuator. 24. A braking control system according to claim 23, wherein the hydraulic actuator comprises a piston coupled to the brake pedal, a cylinder to receive the piston, and a fluid pressure source fluidly connected to the cylinder and operable to control a fluid pressure in the cylinder to move the piston to exert a force on said brake lever. 25. A braking control system according to claim 24, wherein the fluid pressure source comprises a pump.

26. A braking control system according to claim 25, wherein the fluid pressure source further comprises a reservoir fluidly connected to the pump.

27. A braking control system according to claim 26, comprising a fluid return path that selectively fluidly communicates the cylinder with the reservoir.

28. A braking control system according to claim 27, comprising a pressure relief valve configured to move from a closed state to an open state when the pressure of hydraulic fluid in the cylinder exceeds a predetermined level to allow hydraulic fluid to flow through the fluid return path from the cylinder to the reservoir.

29. A braking control system according to any of claims 25 to 28, further comprising a valve that permits the flow of fluid from the pump to the cylinder and restricts the flow of fluid from the cylinder to the pump.

30. A braking control system according to claim 22, wherein the actuator comprises a pneumatic actuator.

31. A braking control system according to claim 30, wherein the pneumatic actuator comprises a piston coupled to the brake pedal, a cylinder to receive the piston, a fluid pressure source, and a control valve that is operable to fluidly connect the fluid pressure source to the cylinder to move the piston to exert a force on said brake lever.

32. A braking control system according to claim 31, wherein the compressed air source comprises a compressor.

33. A braking control system according to claim 32, wherein the compressed air source further comprises a tank, wherein the compressor is configured to fill the tank with compressed air.

34. A braking control system according to any of claims 31 to 33, wherein the pneumatic actuator comprises a pressure relief valve connected between the cylinder and the fluid pressure source.

35. A braking control system according to any of claims 22 to 34, wherein the braking control system has one or more of the features of claims 9 to 21.

36. A braking system for a vehicle comprising a brake pedal that is pivotable to adjust the braking of said vehicle and a braking control system having an actuator coupled to the brake pedal such that the actuator is operable to exert a force on the brake pedal to adjust the braking of said vehicle.

37. A braking system according to claim 36, wherein the braking control system comprises the features of any of claims 1 to 35.

38. A vehicle comprising the braking system of claim 36 or claim 37.

39. A vehicle according to claim 38, wherein the vehicle is powered by an electric motor.

Description:
A Braking Control System

Technical Field

The present invention relates to a braking control system and to a vehicle comprising the same.

Background

Vehicle braking systems generally include a master cylinder with a piston to control the pressure of hydraulic fluid contained in the master cylinder. The master cylinder is fluidly connected to a plurality of brake callipers each having a brake pad that is actuated according to the pressure of the hydraulic fluid in the master cylinder. The vehicle braking system further includes a brake pedal which may be actuated by the driver to exert a force on the piston to increase the pressure of the hydraulic fluid, thereby applying the brakes.

It is desirable to reduce the stopping distance of the vehicle in order to prevent collisions or at least reduce the impact speed in the event that a collision is

unavoidable. When the vehicle is powered by an internal combustion engine, the stopping distance of the vehicle can be reduced by utilising a vacuum assist system that increases the braking power of the vehicle. The vacuum assist system is fluidly connected to the vacuum manifold of the internal combustion engine. Thus, when the internal combustion engine is running a vacuum is applied to a diaphragm of the vacuum assist system. The diaphragm is coupled to the piston of the master cylinder such that said vacuum generated by the internal combustion engine results in an assisting force being exerted on the piston to increase the braking power.

One disadvantage associated with such vacuum assist systems is that an internal combustion engine is required in order to generate the vacuum which assists in braking the vehicle. This makes the vacuum assist system unsuitable for use with vehicles that are powered by alternative means, for example, an electric motor. In addition, even if the vehicle does comprise an internal combustion engine, the vacuum assist system only assists in braking the vehicle when the internal combustion engine is running. Moreover, vacuum assist systems are difficult to retrofit to existing vehicles. Summary

According to the present invention, there is provided a braking control system for a vehicle, said vehicle comprising a brake pedal that is pivotable to adjust the braking of said vehicle, wherein the braking control system comprises an actuator configured to couple to said brake pedal such that the actuator is operable to exert a force on said brake pedal to adjust the braking of said vehicle, wherein the actuator comprises an electric motor and a gear assembly configured to couple the electric motor to said brake pedal, wherein the gear assembly comprises first and second gears, wherein the first gear is fixed relative to said brake pedal and is pivotable about said rotational axis and wherein the electric motor is configured to drive the second gear to exert a force on the first gear.

The brake pedal may comprise a lever and a foot portion at one end of said lever, wherein the actuator is configured to couple to said lever. In one embodiment, the actuator is configured to act on said lever to exert said force on the brake pedal. The first gear may be fixed to said lever. In another embodiment, said lever is connected to a shaft such that the brake pedal is pivotable about the rotational axis of the shaft to adjust the braking of said vehicle, wherein the actuator is configured to act on said shaft to exert said force on the brake pedal. The first gear may be fixed to said shaft of the brake pedal.

The electric motor may be operable to rotate the first gear about said rotational axis to exert a force on said brake pedal to adjust the braking of said vehicle. The electric motor may comprise a servo motor. The actuator may be electrically controllable.

In one embodiment, the first gear is arcuate.

The braking control system may comprise a controller configured to control operation of the actuator. In one embodiment, the controller is configured to adjust the force exerted on the brake pedal by the actuator in accordance with information indicative of an operating condition of the vehicle. In one embodiment, said information indicative of an operating condition of the vehicle comprises information indicative of an operating condition of the brake pedal.

The braking control system may further comprise a pedal sensor that is connected to the controller and is configured to detect said information indicative of an operating condition of the brake pedal. The pedal sensor maybe configured to detect information indicative of the position of the brake pedal. The pedal sensor maybe configured to detect information indicative of the velocity and/or acceleration of the brake pedal. The pedal sensor may be configured to detect information indicative of the force applied to the brake pedal by the driver.

In one embodiment, said vehicle is powered by an electric motor, and wherein said information indicative of an operating condition of the vehicle comprises information indicative of the level of regenerative braking available from said electric motor.

In one embodiment, said information indicative of an operating condition of the vehicle comprises information indicative of the location of said vehicle.

In one embodiment, the braking control system comprises an obstacle detection system, and wherein said information indicative of an operating condition of the vehicle comprises information indicative of a collision with an obstacle detected by the obstacle detection system.

In one embodiment, said vehicle is powered by an electric motor. In one embodiment, the braking control system is configured for autonomous vehicle operation.

According to another aspect of the present invention, there is provided a braking control system for a vehicle, said vehicle comprising a brake pedal that is pivotable to adjust the braking of said vehicle, wherein the braking control system comprises an actuator configured to couple to said brake pedal such that the actuator is operable to exert a force on said brake pedal to adjust the braking of said vehicle.

The braking control system may have one or more of the features described above.

The actuator may comprise a hydraulic actuator. In one embodiment, the hydraulic actuator comprises a piston coupled to the brake pedal, a cylinder to receive the piston, and a fluid pressure source fluidly connected to the cylinder and operable to control a fluid pressure in the cylinder to move the piston to exert a force on said brake lever The fluid pressure source may comprise a pump. The fluid pressure source may further comprise a reservoir fluidly connected to the pump. In one embodiment, the braking control system further comprises a fluid return path that selectively fluidly

communicates the cylinder with the reservoir.

In one embodiment, the braking control system further comprises a pressure relief valve configured to move from a closed state to an open state when the pressure of hydraulic fluid in the cylinder exceeds a predetermined level to allow hydraulic fluid to flow through the fluid return path from the cylinder to the reservoir.

In one embodiment, the braking control system further comprises a valve that permits the flow of fluid from the pump to the cylinder and restricts the flow of fluid from the cylinder to the pump. The actuator may comprise a pneumatic actuator. In one embodiment, the pneumatic actuator comprises a piston coupled to the brake pedal, a cylinder to receive the piston, a fluid pressure source, and a control valve that is operable to fluidly connect the fluid pressure source to the cylinder to move the piston to exert a force on said brake lever. The compressed air source may comprise a compressor. In one embodiment, the compressed air source further comprises a tank, wherein the compressor is configured to fill the tank with compressed air.

In one embodiment, the pneumatic actuator comprises a pressure relief valve connected between the cylinder and the fluid pressure source.

In one embodiment, the actuator comprises a fluidly-driven actuator. The fluidly- driven actuator may comprise a hydraulic actuator or a pneumatic actuator. In another embodiment, the actuator comprises an electric motor. The actuator may further comprise a gear assembly configured to couple the electric motor to said brake pedal.

According to another aspect of the present invention, there is provided a braking system for a vehicle comprising a brake pedal that is pivotable to adjust the braking of said vehicle and a braking control system having an actuator coupled to the brake pedal such that the actuator is operable to exert a force on the brake pedal to adjust the braking of said vehicle. According to another aspect of the present invention, there is provided a vehicle comprising the braking system of the present invention. In one embodiment, the vehicle is powered by an electric motor.

Brief Description of the Drawings

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. l is a schematic side view of a braking system according to a first embodiment of the invention;

Fig. 2 is a schematic front view of the braking system of Fig. l;

Fig. 3 is a block diagram representing a controller of the braking system of Fig. l;

Fig. 4 is a schematic side view of a braking system according to a second embodiment of the invention;

Fig. 5 is a schematic front view of the braking system of Fig. 4;

Fig. 6 is a schematic side view of a braking system according to a third embodiment of the invention; and,

Fig. 7 is a schematic side view of a braking system according to a fourth embodiment of the invention.

Detailed Description

Referring to Figs. 1 to 3, a braking system 1 according to a first embodiment of the invention is shown. The braking system 1 comprises a braking mechanism lA for a vehicle (not shown) and a braking control system 10. The braking control system 10 is coupled to the braking mechanism lA.

The braking mechanism lA comprises a brake pedal 2, a pushrod 3 and a master cylinder 4.

The brake pedal 2 comprises a foot portion 5 and a brake lever 6. The foot portion 5 is provided at a first end 6A of the brake lever 6. A second end 6B of the brake lever 6 is pivotally attached to a mount 7 of the vehicle. More specifically, the second end 6B of the brake lever 6 is attached to a shaft 8 which is rotatable within a bearing (not shown) attached to the mount 7. Thus, the foot portion 5 of the brake pedal 2 is moveable about the rotational axis (illustrated by the chain-dashed line A-A in Fig. 2) of the shaft 8 to travel in an arcuate path relative to the mount 7. The mount 7 is fixed relative to the chassis (not shown) of the vehicle.

The master cylinder 4 is of a conventional arrangement that will be apparent to a person skilled in the art, comprising a piston 4A and a barrel 4B that receives the piston 4A. The barrel 4B contains a hydraulic fluid (not shown). The piston 4A is slidable within the barrel 4B to adjust the pressure of the hydraulic fluid. The pressure of the hydraulic fluid controls the position of the vehicle brake pads (not shown) and therefore determines the rate of braking. In one embodiment, the master cylinder 4 is fluidly connected to a plurality of brake callipers (not shown) each having a brake pad that is moved according to the pressure of the hydraulic fluid in the master cylinder 4.1n one embodiment, the master cylinder 4 is fluidly connected to an anti-lock braking system (ABS) that is connected to the plurality of brake callipers. The anti-lock braking system may be configured to modulate the pressure of the hydraulic fluid supplied to the brake callipers.

The push rod 3 comprises a first end 3A that is attached to the brake lever 6 by a pivotal coupling 9 at a location between the first and second ends 6A, 6B of the brake lever 6. A second end 3B of the push rod 3 extends into the barrel 4B of the master cylinder 4 to couple to the piston 4A.

In one embodiment, the pivot coupling 9 comprises a slot pivot (not shown) that pivotally connects the first end 3A of the push rod 3 to the brake lever 6 whilst allowing for said first end 3A to slide relative to the brake lever 6 in the longitudinal direction of the brake lever 6. The slot pivot may comprise a slot in the brake lever 6 that slidably receives a pivotal joint that is connected to the first end 3A of the push rod 3. Therefore, pivotal movement of the brake lever 6 about the rotational axis A-A of the shaft 8 causes the first end 3A of the push rod 3 to pivot relative to the brake lever 6 and also to slide within the slot of the brake lever 6. Thus, the movement of the push rod 3 is generally linear. For example, if the brake pedal 2 is pressed down such that the brake lever 6 is pivoted in a first direction (shown by arrow 'X' in Fig. 1), the first end 3A of the push rod 3 slides towards the second end 6B of the brake lever 6. Conversely, if the brake lever 6 is pivoted in a second direction (shown by arrow Ύ in Fig. 1), opposite to the first direction X, the first end 3A of the push rod 3 slides towards the first end 6A of the brake lever 6. Pivotal movement of the brake lever 6 about the rotational axis A-A of the shaft 8 causes the push rod 3 to move to slide the piston 4A within the barrel 4B of the master cylinder 4 to adjust the pressure of the hydraulic fluid. For example, if the driver of the vehicle presses his or her foot down on the foot portion 5 of the brake pedal 2 then the brake lever 6 pivots in the first direction X about the rotational axis A-A of the shaft 8 against the force of a spring (not shown). This causes the push rod 3 to move further into the barrel 4B of the master cylinder 4 to urge the piston 4A to compress the hydraulic fluid, thereby increasing braking of the vehicle. Conversely, if the driver reduces the force applied to the foot portion 5 then the spring urges the brake lever 6 to pivot in the second direction Y, opposite to the first direction X, such that the foot portion 5 moves upwardly. This causes the push rod 3 to move further out of the barrel 4B to slide the piston 4A such that the pressure of the hydraulic fluid in the barrel 4B is reduced, thereby reducing braking of the vehicle. The braking control system 10 comprises an actuator 11 and a controller 12. The actuator 11 comprises an electric motor 13 and a gear assembly 14.

In the present embodiment, the electric motor 13 is a servo motor 13. However, it should be recognised that the electric motor 13 may comprise a different type of electric motor, for example, any kind or AC motor or DC motor. In one embodiment, the electric motor comprises a brushless DC (BLDC) motor. The electric motor may include an inverter configured to provide an AC power signal. In one embodiment, the electric motor comprises a stepper motor. The gear assembly 14 comprises first and second gears 15, 16. The first gear 15 is connected to the rotor 13A of the electric motor 13 such that the electric motor 13 drives the first gear 15.

In one embodiment, the gear ratio between the first and second gears 15, 16 is 5:1 such that five rotations of the first gear 15 results in one rotation of the second gear 16.

However, it should be recognised that the gear assembly 14 may alternatively have a different gear ratio or may comprise more than two gears.

The second gear 16 is connected to the shaft 8 such that the second gear 16 rotates about the rotational axis A-A of the shaft 8. The brake lever 6 and second gear 16 are both fixed relative to the shaft 8 and therefore rotation of the second gear 16 causes pivotal movement of the brake lever 6 about the rotational axis A-A of the shaft 8.

The first and second gears 15, 16 engage, for example, having teeth that mesh. Thus, when the electric motor 13 is operated to drive the first gear 15 the second gear 16 is also rotated, which results in pivotal movement of the brake lever 6 about the rotational axis A-A of the shaft 8. As discussed above, pivotal movement of the brake lever 6 adjusts the pressure of the hydraulic fluid in the master cylinder 4. Therefore, the electric motor 13 is operable to exert a force on the brake lever 6 to adjust the braking of the vehicle.

The controller 12 comprises a processor 17 and a memory 18. The memory 18 is configured to store instructions which are carried out by the processor 17. The controller 12 is connected to the electric motor 13 to control the actuator 11 such that the braking control system 10 acts as a 'brake assist' system to boost the braking of the vehicle when the driver applies the brakes. In more detail, when the driver presses on the foot portion 5 to pivot the brake lever 6 in the first direction X to apply the brakes, the controller 12 operates the electric motor 13 to exert a force on the first gear 15 to urge the first gear 15 to rotate. This causes the second gear 16, and the brake lever 6 attached thereto, to be urged to rotate in the first direction X. Thus, the electric motor 13 exerts a force on the brake lever 6 to increase the force exerted on the piston 4A of the master cylinder 4 by the push rod 3. The force exerted on the brake lever 6 by the actuator 11 therefore increases the pressure of the hydraulic fluid in the master cylinder 4 to increase the force applied to the vehicle brake pads (not shown), thereby reducing the stopping distance of the vehicle.

The controller 12 is configured to control the force exerted on the brake pedal 2 by the actuator 11 in accordance with information indicative of an operating condition of the vehicle. In the present embodiment, said information indicative of an operating condition of the vehicle comprises information indicative of an operating condition of the brake pedal 2 and, more specifically, information indicative of the position of the brake pedal 2. The braking control system 10 comprises a pedal sensor 19 that is connected to the controller 12. The pedal sensor 19 is configured to detect the positon of the brake pedal 2 and output a pedal position signal to the controller 12 based on the position of the brake pedal 2. More specifically, the pedal sensor 19 is configured to detect the pivotal position of the brake lever 6 to determine the distance that the brake pedal 2 is displaced in the first direction X away from a rest position, which is the position of the brake pedal 2 when the driver's foot is not applied to the brake pedal 2. Thus, the pedal sensor 19 detects the degree to which the brake pedal 2 is pressed down by the driver's foot.

The pedal sensor 19 comprises a proximity sensor 19, for example, a Hall Effect sensor or inductive sensor. The proximity sensor 19 is configured to measure the distance between a part of the brake pedal 2 and a point fixed relative to the vehicle chassis. In the present embodiment, the proximity sensor 19 is fixed relative to the vehicle chassis and is configured to measure the distance to a part of the brake pedal 2. The proximity sensor 19 is arranged such that when the brake pedal 2 is pivoted away from the rest position in the first direction X, the measured distance increases or decreases. Thus, by measuring said distance between the proximity sensor 19 and said part of the brake pedal 2 the rotational position of the brake pedal 2 can be determined. In another embodiment (not shown), the proximity sensor 19 is mounted to the brake pedal 2 and is configured to measure the distance to a point fixed relative to the vehicle chassis.

In an alternative embodiment (not shown), the pedal sensor 19 is mounted to the shaft 8 and is configured to measure the angular position of the shaft 8 to determine the rotational position of the brake pedal 2. For example, the pedal sensor 19 may comprise a rotary potentiometer (not shown) that is coupled to the shaft 8 such that rotation of the shaft 8 varies a pedal position signal output by the rotary potentiometer. The controller 12 is connected to the rotary potentiometer to detect the pedal position signal. In one embodiment (not shown), the pedal sensor 19 comprises a rotary variable differential transformer (RVDT). In yet another embodiment (not shown), the pedal sensor 19 is configured to measure the position of the push rod 3 or the piston 4A of the master cylinder 4 to determine the position of the brake pedal 2. In one embodiment (not shown), the pedal positon sensor 19 comprises an optical sensor.

The controller 12 is configured to control the actuator 11 in accordance with the pedal position signal output from the pedal sensor 19. More specifically, the controller 12 is configured to operate the electric motor 13 to exert a force on the brake lever 6 that is dependent on the pedal position signal. When the driver presses on the foot portion 5 of the brake pedal 2 to apply the brakes, the movement of the brake pedal 2 in the first direction X is detected by the pedal sensor 19 which outputs a pedal position signal accordingly. The controller 12 detects the pedal position signal and operates the electric motor 13. For example, the controller 12 may be connected to a motor controller circuit (now shown) that controls power to the electric motor 13. Therefore, a force is applied to the brake pedal 2 by the electric motor 13 to increase the force exerted on the piston 4A of the master cylinder 4 and thus boost the braking of the vehicle.

If the driver then presses harder on the foot portion 5 of the brake pedal 2 to increase the braking of the vehicle, the brake pedal 2 moves further in the first direction X and this movement is detected by the pedal sensor 19 which outputs a pedal position signal accordingly. The controller 12 operates the electric motor 13 to increase the force exerted on the brake lever 6 by the electric motor 13, thus further increasing the force exerted on the piston 4A of the master cylinder 4 to boost the vehicle braking.

Conversely, if the driver reduces the force applied to the brake pedal 2 by his or her foot in order to reduce braking of the vehicle, the brake pedal 2 moves in the second direction Y under the force of the spring. This movement is detected by the pedal sensor 19, which outputs a pedal position signal accordingly. The controller 12 detects the pedal position signal and controls the electric motor 13 to decrease the force exerted on the brake lever 6 by the electric motor 13 and thus the force exerted on the piston 4A of the master cylinder to boost braking is reduced. For example, when the pedal sensor 19 outputs a pedal position signal indicating that the brake pedal 2 has pivoted in the second direction Y, the controller 12 detects the pedal position signal and operates the electric motor 13 to drive the first gear 15 such that the second gear 16 is rotated in the second direction Y, thus reducing the force exerted on the brake lever 6. When the driver's foot is removed from the brake pedal 2 the spring returns the brake pedal 2 to the rest position. This movement of the brake pedal 2 towards the rest position is detected by the pedal sensor 19, which outputs a pedal position signal accordingly. The controller 12 detects the pedal position signal and operates the electric motor 13 to rotate the first gear 15, and thus the second gear 16 engaged therewith, to a position wherein substantially no force is exerted on the brake pedal 2 by the electric motor 13. The braking control system 10 is therefore able to exert a force on the brake pedal 2 to assist the driver in braking the vehicle. The force exerted on the brake pedal 2 by the actuator 11 is increased when the driver presses on the brake pedal 2 to apply the brakes.

Advantageously, the braking control system 10 reduces the stopping distance of the vehicle. This is because the electric motor 13 can exert a relatively large force on the piston 4A of the master cylinder 4 in comparison to the force generated by the driver's foot. Moreover, the braking control system 10 does not require a vacuum to operate and therefore is suitable for use with vehicles that do not comprise an internal combustion engine, for example, electric vehicles.

Another advantage of the braking control system 10 is that it can be retrofitted to existing vehicles. This is because the actuator 11 couples to the brake pedal 2 and therefore major modification of the braking mechanism lA to allow for coupling to the braking control system 10 is not necessary. For example, the gear assembly 14 can easily be coupled to the brake pedal 2 of a conventional braking mechanism lA such that the second gear 16 is connected to the shaft 8. In comparison, a vacuum assist system would normally require modification of various parts of the braking

mechanism, for example, modification of the push rod of the braking mechanism to accommodate the vacuum assist system.

In addition, the braking control system 10 advantageously mimics the action of the driver's foot. This is because the actuator 11 exerts a force on the brake pedal 2 to pivot the brake lever 6 in the first direction X, which is also how the driver operates the brakes.

In some applications, for example, motor sport applications, regulations dictate that braking assist systems may not be used. Instead, the braking force must be generated entirely by the force of the driver's foot applied to the brake pedal. Advantageously, the braking control system 10 of the present invention can be deactivated to comply with the regulations when the vehicle is used in such applications so that the actuator 11 does not exert any force on the brake pedal 2. The braking control system 10 can then be switched on when used in other applications, for example, regular road use, testing, or autonomous applications, including autonomous motor sport applications. Another advantage of the braking control system 10 is that braking of the vehicle is still possible in the event that the braking control system 10 fails or power is lost to the braking control system 10. This is because in such a scenario the driver is still able to press the brake pedal 2 to manually force the push rod 3 into the barrel 4B of the master cylinder 4 to actuate the piston 4A and apply the brakes.

In the above described embodiment, the electric motor 13 is coupled to the brake lever 6 by the gear assembly 14. However, in an alternative embodiment (not shown), the gear assembly 14 is omitted and instead the rotor 13A of the electric motor 13 is connected directly to the shaft 8.

Referring now to Figs. 4 and 5, a braking system 21 according to a second embodiment of the invention is shown. The braking system 21 is similar to the braking system 1 of the first embodiment of the invention described above in relation to Figs. 1 to 3, with like features retaining the same reference numerals. A difference is that the braking control system 10 of the first embodiment is omitted and is replaced with an alternative braking control system 30.

The braking control system 30 is coupled to a braking mechanism 21A having similar features to the braking mechanism lA described above in relation to Figs. 1 to 3 and therefore, for the sake of brevity, a detailed description of the braking mechanism 21A will not be repeated hereinafter.

The braking mechanism 21A comprises a brake pedal 2, a pushrod 3 and a master cylinder 4. The brake pedal 2 comprises a foot portion 5 and a brake lever 6 that is attached to a mount 7 of the vehicle by a shaft 8. The brake pedal 2 is pivotable relative to the mount 7 to increase the pressure of hydraulic fluid within the master cylinder 4 to apply the brakes of the vehicle. The braking control system 30 comprises an actuator 31 and a controller 32. The actuator 31 comprises an electric motor 33 and a gear assembly 34.

The gear assembly 34 comprises first and second gears 35, 36. The first gear 35 is connected to the rotor 33A of the electric motor 33 such that the electric motor 33 drives the first gear 35. The second gear 36 is arcuate. The second gear 36 is fixed relative to the brake lever 6 such that the centre point of the arcuate second gear 36 is common with the rotational axis A-A of the shaft 8. Thus, the brake lever 6 and second gear 36 both pivot together about the rotational axis A-A of the shaft 8. In one embodiment, the second gear 36 is integrally formed with the brake lever 6. In another embodiment, the second gear 36 is attached to the brake lever 6, or example, being bolted or welded to the brake lever 6.

The first and second gears 35, 36 engage such that when the electric motor 33 is operated to drive the first gear 35, the second gear 36 is pivoted about the rotational axis A-A of the shaft 8, which results in corresponding pivotal movement of the brake lever 6. As discussed above in relation to the first embodiment, pivotal movement of the brake lever 6 adjusts the pressure of the hydraulic fluid in the master cylinder 4.

Therefore, the electric motor 33 is operable to adjust the braking of the vehicle. The controller 32 is configured to control the force exerted on the brake pedal 2 by the actuator 31 in accordance with information indicative of an operating condition of the vehicle. In the present embodiment, said information indicative of an operating condition of the vehicle comprises information indicative of an operating condition of the brake pedal 2 and, more specifically, information indicative of the position of the brake pedal 2.

The controller 32 comprises a processor and a memory (not shown). A pedal sensor 39 is connected to the controller 32. Similarly to the first embodiment, the pedal sensor 39 is configured to output a pedal position signal that is dependent on the angular displacement of the brake pedal 2 away from the rest position.

The controller 32 is configured to control the actuator 31 in accordance with the pedal position signal output from the pedal sensor 39. More specifically, the controller 32 is configured to operate the electric motor 33 to exert a force on the brake lever 6 according to the pedal position signal, thereby adjusting the rate of braking. The braking control system 30 is therefore able to exert a force on the brake pedal 2 to assist the driver in braking the vehicle. The force exerted on the brake pedal 2 by the actuator 31 is increased when the driver presses on the brake pedal 2. In the above described embodiment, the first gear 35 is a rotary gear and the second gear 36 is arcuate. However, it should be recognised that in an alternative embodiment (not shown) the gear assembly 34 instead comprises a rack and pinion. Referring now to Fig. 6, a braking system 41 according to a third embodiment of the invention is shown. The braking system 41 is similar to the braking system 1 of the first embodiment of the invention described above in relation to Figs. 1 to 3, with like features retaining the same reference numerals. A difference is that the braking control system 10 of the first embodiment is omitted and is replaced with an alternative braking control system 50.

The braking control system 50 is coupled to a braking mechanism 41A having similar features to the braking mechanism lA described above in relation to Figs. 1 to 3 and therefore, for the sake of brevity, a detailed description of the braking mechanism 41A will not be repeated hereinafter.

The braking mechanism 41A comprises a brake pedal 2, a pushrod 3 and a master cylinder 4. The brake pedal 2 comprises a foot portion 5 and a brake lever 6 that is attached to a mount 7 of the vehicle by a shaft 8. The brake pedal 2 is pivotable relative to the mount 7 to increase the pressure of hydraulic fluid within the master cylinder 4 to apply the brakes of the vehicle.

The braking control system 50 comprises an actuator 51 and a controller 52. The actuator 51 is a hydraulic actuator 51, comprising a piston 53A, a cylinder 53B for containing a hydraulic fluid, and a rod 54. The piston 53A is slidably received within the cylinder 53B.

A first end of the rod 54 is connected to the piston 53A and a second end of the rod 54 is connected to the brake lever 6 by a pivotal coupling 54A. Thus, movement of the piston 53A within the cylinder 53B of the hydraulic actuator 51 results in the rod 54 moving with respect to the cylinder 53B to exert a force on the brake lever 6 to urge the brake pedal 2 to pivot about the rotational axis A-A of the shaft 8. The hydraulic actuator 51 further comprises a reservoir 55, a pump 56, a pressure relief valve 57, and a control valve 58. The reservoir 55 contains a hydraulic actuation fluid (not shown). The pump 56 is fluidly connected between the reservoir 55 and the cylinder 53B of the hydraulic actuator 51. Thus, the pump 56 can be driven to transfer hydraulic actuation fluid from the reservoir 55 to the cylinder 53B to increase the pressure of the hydraulic actuation fluid in the cylinder 53B, thereby sliding the piston 53A within the cylinder 53B.

When the pump 56 is driven to transfer hydraulic actuation fluid from the reservoir 55 to the cylinder 53B, the fluid pressure in the cylinder 53B is increased. This causes the piston 53A to be slid relative to the cylinder 53B of the hydraulic actuator 51 such that the rod 54 is urged out of the cylinder 53B and thus the brake pedal 2 is moved in the first direction X. As discussed above in relation to the first embodiment, movement of the brake pedal 2 in the first direction X exerts a force on the piston 4A of the master cylinder 4 to increase the braking of the vehicle.

The pressure relief valve 57 is configured to regulate the pressure at the outlet of the pump 56 by controlling the flow of hydraulic actuation fluid through a return path 57A. When the pressure at the outlet of the pump 56 is below a predetermined maximum value, the pressure relief valve 57 fluidly connects the outlet of the pump 56 with the cylinder 53B of the hydraulic actuator 51 and the return path 57A is closed. However, if the pressure at the outlet of the pump 56 exceeds said predetermined maximum value, the pressure relief valve 57 opens the return path 57A such that the outlet of the pump 56 is fluidly connected to the reservoir 55. Thus, when the pressure at the outlet of the pump 56 exceeds said predetermined maximum value the hydraulic actuation fluid flows through the return path 57A and back into the reservoir 55 such that the pressure at the outlet of the pump 56 decreases.

The pressure relief valve 57 therefore prevents the pressure of the hydraulic actuation fluid at the outlet of the pump 56 from exceeding said maximum predetermined value, and thus prevents damage to the hydraulic actuator 51. The control valve 58 is connected between the pressure relief valve 57 and the cylinder 53B. The control valve 58 is also connected to the return path 57A. The control valve 58 is configured to fluidly communicate the pump 56 with the cylinder 53B when the brake pedal 2 is pressed in the first direction X and to block the cylinder 53B and pump 56 from the return path 57A. The control valve 58 is configured to fiuidly communicate the cylinder 53B with the return path 57A when the brake pedal 2 moves in the second direction Y and to block the cylinder 53B and return path 57A from the pump 56. Thus, when the brake pedal 2 is pressed in the first direction X hydraulic fluid flows from the pump 56 to the cylinder 53B to act on the piston 53A such that the rate of braking is increased. When the brake pedal 2 moves in the second direction Y, under the force of the spring, hydraulic fluid flows out of the cylinder 53B and through the return path 57A to flow back into the reservoir 55 and thus the pressure in the cylinder 53B is decreased.

In one embodiment (not shown), the control valve 58 is a three-way valve. The three- way valve may comprise a valve head, for example, a ball or piston, which is moveable between first and second positions. The valve head is biased into the first position by a biasing member. In the first position, the valve head rests against a first seat to block the pump 56 from the cylinder 53B and return path 57A. The cylinder 53B is communicated with the return path 57A when the valve head is in the first position. In the second position, the valve head rests against a second seat to block the return path 57A from the cylinder 53B and pump 56. The cylinder 53B is communicated with the pump 56 when the valve head is in the second position. When the pump 56 is operated, fluid flows from the pump 56 to the cylinder 53B such that the valve head is urged against the force of the biasing member and into the second position and thus the return path 57A is blocked. When the driver reduces the force applied to the brake pedal 2, the pump 56 is switched off by the controller 52. The brake lever 2 is pivoted in the second direction Y by the force of the spring such that the rate of braking is reduced and also the rod 54 moves into cylinder 53B such that the piston 53A is slid to increase the pressure of the hydraulic fluid in said cylinder 53B. This causes the hydraulic fluid to flow from the cylinder 53B towards the pump 56 and thus the biasing member urges the valve head back to the first position, thereby sealing the cylinder 53B from the pump 56. The hydraulic fluid in the cylinder 53B flows through the return path 57A to enter the reservoir 55.

In an alternative embodiment (not shown), the control valve 58 comprises first and second valves. The first valve is a check valve that allows fluid to flow from the pump 56 to the cylinder 53B but prevents fluid from flowing in the reverse direction from the cylinder 53B to the pump 56. The second valve is openable to selectively communicate the cylinder 53B with the return path 57A to allow hydraulic fluid in the cylinder 53B to flow back into to the reservoir 55. In one such embodiment, the second valve is connected to the controller 52, which opens the second valve to connect the cylinder 53B to the return path 57A when the brake pedal 2 moves in the second direction Y. For example, the second valve may comprise a motorised valve or solenoid valve that is connected to the controller 52.

In one embodiment (not shown), the control valve comprises a check valve that allows fluid to flow from the pump 56 to the cylinder 53B but prevents fluid from flowing in the reverse direction from the cylinder 53B to the pump 56. A second pressure relief valve (not shown) is connected between the cylinder 53B and the return path 57A. When the brake pedal 2 is pressed in the first direction X, hydraulic fluid flows from the pump 56 to the cylinder 53B to act on the piston 53A such that the rate of braking is increased. The pressure of the hydraulic fluid in the cylinder 53B is insufficient to open the second pressure relief valve when the brake pedal 2 is pressed in the first direction X. When the brake pedal 2 moves in the second direction Y under the force of the spring, the piston 53A moves within the cylinder 53B to urge hydraulic fluid out of the cylinder 53B. This causes the check valve to close to prevent hydraulic fluid in the cylinder 53B from flowing to the pump 56 and thus the pressure of the hydraulic fluid in the cylinder 53B increases such that the second pressure relief valve opens.

Therefore, the hydraulic fluid in the cylinder 53B flows through the second pressure relief valve and back into the reservoir 55, via the return path 57A, such that the pressure in the cylinder 53B decreases. The controller 52 comprises a processor (not shown) and a memory (not shown). The memory is configured to store instructions which are carried out by the processor. In one embodiment, the pump 56 comprises an electric motor (not shown) and the controller 52 is configured to control the power supplied to the electric motor to control operation of the pump 56.

The controller 52 is configured to control the force exerted on the brake pedal 2 by the actuator 51 in accordance with information indicative of an operating condition of the vehicle. In the present embodiment, said information indicative of an operating condition of the vehicle comprises information indicative of an operating condition of the brake pedal 2 and, more specifically, information indicative of the position of the brake pedal 2. The controller 52 is connected to the pump 56 to control the actuator 51 such that the braking control system 50 acts as a 'brake assist' to boost the braking of the vehicle when the driver applies the brakes. In more detail, when the driver presses on the foot portion 5 to pivot the brake lever 6 in the first direction X to apply the brakes, the controller 52 operates the pump 56 to increase the pressure of the hydraulic actuation fluid in the cylinder 53B of the hydraulic actuator 51. This causes the rod 54 of the hydraulic actuator 51 to exert a force on the brake lever 6. The force exerted on the brake lever 6 by the actuator 51 increases the pressure of the hydraulic fluid in the master cylinder 4 to increase the force applied to the vehicle brake pads (not shown), thereby increasing the braking of the vehicle.

The braking control system 50 further comprises a pedal sensor 59 that is connected to the controller 52. Similarly to the first embodiment, the pedal sensor 59 is configured to output a pedal position signal that is dependent on the angular displacement of the brake pedal 2 away from the rest position.

The controller 52 is configured to control the hydraulic actuator 51 in accordance with the pedal position signal output from the pedal sensor 59. More specifically, the controller 52 is configured to operate the pump 56 to adjust the pressure of the hydraulic actuation fluid in the cylinder 53B according to the pedal position signal, thereby adjusting the rate of braking. The braking control system 50 is therefore able to exert a force on the brake pedal 2 to assist the driver in braking the vehicle. The pressure in the cylinder 53B of the hydraulic actuator 51, and thus the force exerted on the brake pedal 2 by the hydraulic actuator 51, is increased when the driver presses on the brake pedal 2. Similarly, if the driver reduces the force applied to the brake pedal 2 by his or her foot, the force applied to the brake pedal 2 by the hydraulic actuator 51 is also reduced, with hydraulic fluid in the cylinder 53B returning to the reservoir 55 via the return path 57A.

In some embodiments (not shown), the braking control system 50 comprises one or more pressure sensors configured to measure the pressure of the hydraulic fluid. The or each pressure sensor may be connected to the controller 52. In one such embodiment, the braking control system 50 comprises a pressure sensor configured to measure the pressure of the hydraulic fluid in the cylinder 53B. The pump 56 is controlled by the controller 52 to maintain the pressure of the hydraulic fluid in the cylinder 53B within a pressure range. If the measured pressure in the cylinder 53B is below the pressure range, the pump 56 is operated to supply hydraulic fluid from the reservoir 55 to the cylinder 53B to increase the pressure therein. If the pressure in the cylinder 53B exceeds the pressure range, the control valve 58 is operated by the controller 52 to return hydraulic fluid in the cylinder 53B to the reservoir 55. The pressure range may be determined by the controller 52 based on information indicative of an operating condition of the vehicle, for example, the position of the brake pedal 2. The pressure range may also comprise a safe operating pressure range of the hydraulic actuator 51. In one embodiment, the braking control system 50 comprises a pressure sensor configured to measure the pressure of the hydraulic fluid at the outlet of the pump 56. If the measured pressure exceeds a predetermined value, the controller 52 opens the pressure relief valve 57.

Referring now to Fig. 7, a braking system 61 according to a fourth embodiment of the invention is shown. The braking system 61 is similar to the braking system 1 of the first embodiment of the invention described above in relation to Figs. 1 to 3, with like features retaining the same reference numerals. A difference is that the braking control system 10 of the first embodiment is omitted and is replaced with an alternative braking control system 70.

The braking control system 70 is coupled to a braking mechanism 61A having similar features to the braking mechanism lA described above in relation to Figs. 1 to 3 and therefore, for the sake of brevity, a detailed description of the braking mechanism 61A will not be repeated hereinafter.

The braking mechanism 61A comprises a brake pedal 2, a pushrod 3 and a master cylinder 4. The brake pedal 2 comprises a foot portion 5 and a brake lever 6 that is attached to a mount 7 of the vehicle by a shaft 8. The brake pedal 2 is pivotable relative to the mount 7 to increase the pressure of hydraulic fluid within the master cylinder 4 to apply the brakes of the vehicle.

The braking control system 70 comprises an actuator 71 and a controller 72.

The actuator 71 is a pneumatic actuator 71, comprising a piston 73A, a cylinder 73B for containing compressed air, and a rod 74. The piston 73A is slidably received within the cylinder 73B. A first end of the rod 74 is connected to the piston 73A and a second end of the rod 74 is connected to the brake lever 6 by a pivotal coupling 74A. Thus, movement of the piston 73A within the cylinder 73B of the pneumatic actuator 71 results in the rod 74 moving with respect to the cylinder 73B to exert a force on the brake lever 6 to urge the brake pedal 2 to pivot about the rotational axis A-A of the shaft 8.

The pneumatic actuator 71 further comprises an air tank 75, a compressor 76, a pressure relief valve 77 and a control valve 78.

The compressor 76 is fluidly connected to the air tank 75 and is operable to fill the air tank 75 with compressed air (not shown). In one embodiment (not shown), the compressor 76 is configured to maintain the compressed air in the air tank 75 at a predetermined minimum pressure. For instance, the compressor 76 may include a sensor to detect the pressure in the air tank 75. If the sensor detects that the pressure in the air tank 75 drops below said predetermined minimum pressure, the compressor 76 is operated to increase the pressure in the air tank 75.

The control valve 78 is provided between the air tank 75 and the cylinder 73B of the pneumatic actuator 71. The control valve 78 selectively fluidly communicates the air tank 75 with the cylinder 73B to supply the cylinder 73B with compressed air, thereby increasing the air pressure in the cylinder 73B to slide the piston 73A within the cylinder 73B. When the control valve 78 is opened to fluidly connect the air tank 75 with the cylinder 53B, the air pressure in the cylinder 73B is increased. This causes the piston 73A to be slid relative to the cylinder 73B of the pneumatic actuator 71 such that the rod 74 is urged out of the cylinder 73B and thus a force is exerted on the brake lever 6 to move the brake pedal 2 in the first direction X. As discussed above in relation to the first embodiment, movement of the brake pedal 2 in the first direction X exerts a force on the piston 4A of the master cylinder 4 to increase the braking of the vehicle.

The pressure relief valve 77 is openable to allow the cylinder 73B to vent to atmosphere, thereby reducing the air pressure in the cylinder 73B. This reduces the force exerted on the brake lever 6 by the rod 74 such that the rate of braking of the vehicle is reduced. The controller 72 comprises a processor (not shown) and a memory (not shown). The memory is configured to store instructions which are carried out by the processor. In one embodiment, the compressor 76 comprises an electric motor (not shown) and the controller 72 is configured to control the power supplied to the electric motor to control operation of the compressor 76.

The controller 72 is configured to control the force exerted on the brake pedal 2 by the pneumatic actuator 71 in accordance with information indicative of an operating condition of the vehicle. In the present embodiment, said information indicative of an operating condition of the vehicle comprises information indicative of an operating condition of the brake pedal 2 and, more specifically, information indicative of the position of the brake pedal 2.

The controller 72 is connected to the pressure relief valve 77 and control valve 78 to control the pneumatic actuator 71 such that the braking control system 70 acts as a 'brake assist' to boost the braking of the vehicle when the driver applies the brakes. In more detail, when the driver presses on the foot portion 5 to pivot the brake lever 6 in the first direction X to apply the brakes, the controller 72 opens the control valve 78 to supply compressed air from the air tank 75 to the cylinder 73B of the pneumatic actuator 71 to increase the air pressure in the cylinder 73B. This causes the rod 74 of the pneumatic actuator 71 to exert a force on the brake lever 6. The force exerted on the brake lever 6 by the pneumatic actuator 71 increases the pressure of the hydraulic fluid in the master cylinder 4 to increase the force applied to the vehicle brake pads (not shown), thereby reducing the stopping distance of the vehicle. When the driver reduces the force applied to the foot portion 5 to reduce braking such that the brake lever 6 pivots in the second direction Y, the controller 72 closes the control valve 78 and opens the pressure relief valve 77 such that the air pressure in the cylinder 73B is reduced and thus the force exerted on the brake lever 6 by the rod 74 to assist in braking the vehicle is also reduced.

The braking control system 70 comprises a pedal sensor 79 that is connected to the controller 72. Similarly to the first embodiment, the pedal sensor 79 is configured to output a pedal position signal that is dependent on the angular displacement of the brake pedal 2 away from the rest position. The controller 72 is configured to control the pneumatic actuator 71 in accordance with the pedal position signal output from the pedal sensor 79. More specifically, the controller 72 is configured to control the pressure relief valve 77 and control valve 78 to adjust the air pressure in the cylinder 73B according to the pedal position signal, thereby adjusting the rate of braking. The braking control system 70 is therefore able to exert a force on the brake pedal 2 to assist the driver in braking the vehicle. The air pressure in the cylinder 73B, and thus the force exerted on the brake pedal 2 by the pneumatic actuator 71, is increased when the driver presses on the brake pedal 2.

Similarly, if the driver reduces the force applied to the brake pedal 2 by his or her foot, the force applied to the brake pedal 2 by the pneumatic actuator 71 is also reduced.

In the above described embodiment, the pneumatic actuator 71 controls the flow of compressed air to exert a force on the brake pedal 2. However, in other embodiments the pneumatic actuator is instead used with a different gas, for example, carbon dioxide or nitrogen.

In some embodiments (not shown), the braking control system 70 comprises one or more pressure sensors configured to measure the pressure of the air in the pneumatic actuator 71. The or each pressure sensor may be connected to the controller 72. In one such embodiment, the braking control system 70 comprises a pressure sensor configured to measure the pressure of the air in the cylinder 73B. The control valve 78 is controlled by the controller 52 to maintain the pressure of the air in the cylinder 73B within a pressure range. If the measured pressure in the cylinder 73B is below the pressure range, the control valve 78 is opened to supply compressed air from the air tank 75 to the cylinder 73B. If the pressure in the cylinder 73B exceeds the pressure range, the pressure relief valve 77 is operated to allow air in the cylinder 73B to vent to atmosphere. The pressure range may be determined by the controller 72 based on information indicative of an operating condition of the vehicle, for example, the position of the brake pedal 2. The pressure range may also be a safe operating pressure range of the pneumatic actuator 71. In one embodiment, the braking control system 70 comprises a pressure sensor configured to measure the pressure of the air at the outlet of the control valve 78. If the measured pressure exceeds a predetermined value, the controller 72 opens the pressure relief valve 77. In the second, third and fourth embodiments described above in relation to Figs. 4 to 7, the actuator 31, 51, 71 is coupled to the brake lever 6 at a location between the shaft 8 and the pivotal coupling 9 with the push rod 3. Advantageously, this arrangement means that a relatively small movement of the actuator 31, 51, 71 results in a relatively large movement of the push rod 3. Thus, the size of the actuator 31, 51, 71 can be minimised. However, in alternative embodiments (not shown), the actuator 31, 51, 71 is instead coupled to the brake lever 6 at a location on the other side of the pivotal coupling 9 to the shaft 8. Advantageously, this alternative arrangement increases the leverage that the actuator 31, 51, 71 exerts on the brake lever 6 such that a relatively small force exerted on the brake lever 6 by the actuator 31, 51, 71 results in a relatively large force being exerted on the piston 4A of the master cylinder 4 by the pushrod 3.

In the second, third and fourth embodiments described above in relation to Figs. 4 to 7, the shaft 8 is provided at the second end 6B of the brake lever 6. However, in alternative embodiments (not shown), the shaft 8 is provided at a location between the first and second ends 6A, 6B of the brake lever 6. In one such embodiment, the actuator 3i > 5i > 71 is coupled to the second end 6B of the brake lever 6 or to a location between the shaft 8 and the second end 6B of the brake lever 6 and is operable to exert a force on the brake lever 6.

In the above described embodiments, the controller 12, 32, 52, 72 is configured to control the actuator 11, 31, 51, 71 such that the braking control system 10, 30, 50, 70 acts as a 'brake assist' system to boost the braking of the vehicle when the driver applies the brakes. However, the braking control system 10, 30, 50, 70 may also be configured to alternatively, or additionally, control the braking of the vehicle based on a different operating condition of the vehicle. In one embodiment, the braking control system 10, 30, 50, 70 exert a force on the brake pedal 2 that is dependent on the vehicle speed. For example, if the controller determines that the vehicle is travelling quickly then a large force is exerted on the brake lever by the actuator when the driver applies the brakes. Conversely, if the controller determines that the vehicle is travelling slowly then a smaller force is exerted on the brake lever by the actuator when the driver applies the brakes.

In one embodiment (not shown), the brake control system comprises a receiver that allows the brake control system to be controlled remotely. This allows for a user to remotely operate the actuator to exert a force on the brake lever to apply the vehicle brakes. This is particularly advantageous in vehicle testing applications. In one embodiment (now shown), the braking control system comprises an obstacle detection system. The obstacle detection system may detect information indicative of a collision with an obstacle detected by the obstacle detection system. In one

embodiment, the obstacle detection system includes an obstacle sensor for detecting obstacles in the vehicle path. The obstacle sensor is connected to the controller such that the controller can determine whether the vehicle is likely to collide with an obstacle. If the controller determines that a collision is likely, the controller operates the actuator to exert a force on the brake lever to slow the vehicle, thus avoiding the collision or reducing the speed of impact. The obstacle sensor may utilise one or more of radar, ultrasound or infrared to detect obstacles. Alternatively, or additionally, the obstacle sensor may comprise a camera.

In one embodiment, the braking control system 10, 30, 50, 70 is configured to allow the vehicle to operate in an autonomous or 'driverless' mode of operation. In one embodiment, the braking control system includes a location sensor for detecting information indicative of the location of the vehicle. The location sensor may be a GPS device or a device for determining location based on local WiFi connections.

Alternatively, or additionally, the location sensor may be a device for determining location based on a mobile phone network signal. The location sensor is connected to the controller. The controller is configured to operate the actuator to exert a force on the brake lever in accordance with the detected location of the vehicle. In one such embodiment, the controller is also configured to control the vehicle steering and acceleration in accordance with the detected location of the vehicle. In one embodiment, the vehicle is powered by an electric motor and the braking control system 10, 30, 50, 70 exert a forces on the brake pedal 2 that is dependent on information indicative of the amount of regenerative braking available from the electric motor. For example, if a small amount of regenerative braking is available to slow the vehicle then a relatively large force is exerted on the brake pedal 2 by the actuator in order to assist in braking of the vehicle. Conversely, if a relatively large amount of regenerative braking is available then the actuator exerts a relatively small force on the brake pedal 2. Thus, the force with which the vehicle is braked when then driver presses on the brake pedal 2 is largely independent on the amount of regenerative braking available. Advantageously, this makes the braking more predictable for the driver and therefore the vehicle is easier to operate. The information indicative of the amount of regenerative braking available may be determined based on the vehicle speed or the rotational speed of the electric motor that powers vehicle. For example, in some embodiments the amount of regenerative braking available increases when the vehicle speed increases. In one embodiment, the vehicle includes a system which determines a required braking rate and determines the proportion of the required braking rate that is achievable via regenerative braking and the proportion of the required braking rate that is achievable via the pressure of the hydraulic fluid in the master cylinder 4. The required braking rate may be determined, for example, based on the positon of the brake pedal 2, the current speed of the vehicle and/or the rate of braking necessary to avoid a collision. In one embodiment, the braking control system comprises a pressure sensor that measures the pressure of the hydraulic fluid in the master cylinder. The pressure sensor is connected to the system such that the system can determine the braking rate that can be achieved hydraulically based on the pressure of the hydraulic fluid.

If the amount of regenerative braking available is determined to be sufficient to achieve the required braking rate then the system utilises only regenerative braking to brake the vehicle. Alternatively, if the system determines that regenerative braking alone would be insufficient to achieve the required braking rate then the system supplements the regenerative braking with braking using the hydraulic pressure in the master cylinder to achieve the required braking rate. In one embodiment, the controller is configured to operate the actuator to exert a force on the brake pedal to assist in braking of the vehicle in dependence on the difference between the required braking rate and the braking rate available via regenerative braking. For example, if the braking rate available via regenerative braking alone is sufficiently smaller than the required braking rate then the actuator is operated to exert a relatively large force on the brake pedal to assist in braking of the vehicle.

The system therefore only brakes the vehicle using the hydraulic pressure in the master cylinder 4, which is less efficient than braking the vehicle using regenerative braking, when this is necessary to achieve the required braking rate. Thus, the efficiency of the vehicle is improved. In one embodiment, the system that determines the required braking rate comprises the controller 12, 32, 52, 72 and/or the anti-lock braking system.

In the above described embodiments, the pedal sensor 19, 39, 59, 79 is configured to detect the angular displacement of the brake pedal 2 relative to the rest position. However, it should be recognised that in other embodiments (not shown) the pedal sensor may be configured to alternatively, or additionally, determine information indicative of a different operating characteristic of the brake pedal 2. In one such embodiment, the pedal sensor comprises an accelerometer that is configured to measure the acceleration of the brake pedal 2. In another embodiment, the pedal sensor is configured to detect the velocity of the brake pedal 2. In yet another embodiment, the pedal sensor is configured to detect the force applied to the foot portion 5 of the brake pedal 2 by the driver's foot and may comprise, for example, a strain gauge that is mounted to the foot portion 5.

In one embodiment, the braking control system 10, 30, 50, 70 is configured such that the controller 12, 32, 52, 72 operates the actuator 11, 31, 51, 71 to exert a force on the brake lever 6 that is linearly proportional to the angular displacement of the brake pedal 2 away from the rest position. However, in alternative embodiments this relationship between the position of the brake pedal 2 and the force applied to the brake lever 6 by the actuator 11, 31, 51, 71 may be non-linear and, for example, may be a curved relationship. In one such embodiment, the controller 12, 32, 52, 72 is configured to store a number of different relationship curves between the position of the brake pedal 2 and the resultant force applied to the brake lever 6 by the actuator 11, 31, 51, 71, wherein each relationship curve represents a different vehicle driving mode, for example, 'sport mode', 'standard mode', 'wet conditions mode' or 'winter conditions mode'. The vehicle driving mode may be selected automatically according to detected driving conditions or may be manually selected by the driver. In one embodiment (not shown), the braking system comprises a pedal box. The pedal box comprises a housing, braking mechanism and braking control system. The braking mechanism is located in the housing and comprises a brake pedal, push rod, and master cylinder. The brake lever of the brake pedal is pivotally mounted within the housing and the foot portion protrudes out of the housing for access by the driver. The braking control system is similar to those described above, comprising an actuator for exerting a force on the brake lever. The pedal box can be mounted in a vehicle and the master cylinder fluidly connected to the slave cylinders of the vehicle. Thus, the pedal box can easily be retrofitted to existing vehicles. In one embodiment, the vehicle comprises an electronic control unit (not shown) that controls one or more electronic systems of the vehicle. In one such embodiment, the electronic control unit comprises the controller 12, 32, 52, 72. Alternatively, the controller 12, 32, 52, 72 may be separate to the electronic control unit of the vehicle.

In the above described embodiments, the braking control system 10, 30, 50, 70 is coupled to the braking mechanism lA, 21A, 41A, 61A of an electric vehicle. However, it should be recognised that the braking control system 10, 30, 50, 70 is also suitable for use with the braking mechanism of a vehicle that is powered by different means. For example, the braking control system 10, 30, 50, 70 may instead be coupled to the braking mechanism of a vehicle powered by an internal combustion engine or a hybrid vehicle that has both an electric motor and an internal combustion engine. The internal combustion engine may be configured to act as a range-extender that recharges a battery connected to the electric motor.

In one embodiment, the braking control system 10, 30, 50, 70 comprises an anti-lock braking system.

Embodiments of the present invention may be implemented in software, hardware, application logic or a combination of software, hardware, and application logic. The software, application logic and/or hardware may reside on memory, or any computer media. In an example embodiment, the application software or an instruction set is maintained on any one of various conventional computer-readable media. In the context of this document, a "memory" or "computer-readable medium" may be any media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer.

In order to address various issues and advance the art, the entirety of this disclosure shows by way of illustration various embodiments in which the claimed invention(s) may be practiced and provide for a superior electro-hydraulic power steering system. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and/or exclusive. They are presented only to assist in understanding and teach the claimed features. It is to be understood that advantages, embodiments, examples, functions, features, structures, and/or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope and/ or spirit of the disclosure. Various embodiments may suitably comprise, consist of, or consist essentially of, various combinations of the disclosed elements, components, features, parts, steps, means, etc. In addition, the disclosure includes other inventions not presently claimed, but which may be claimed in future.