Electro-hydraulic braking system

• US 20060186729A1
• Filed: 02/23/2005
• Published: 08/24/2006
• Est. Priority Date: 02/23/2005
• Status: Active Grant

• Current Assignee: Continental Automotive Systems, Inc. (Continental AG)
• Original Assignee: Continental Teves Incorporated (Continental AG)
• Inventors: Beaver, Robert Charles, Agnew, David Leslie, Young, Kent Randolph, Lehmann, Kurt Stouffer
• Granted Patent: US 7,686,404 B2
• Time in Patent Office: Days
• US Class Current: 303/11
• CPC Class Codes: B60T 8/3275 Systems with a braking assistant function, i.e. automatic full braking initiation in dependence of brake pedal velocity
• CPC Class Codes: B60T 8/4086 the stroke simulating device being connected to, or integrated in the driver input device
• CPC Class Codes: B60T 8/442 the booster being a fluid return pump, e.g. in combination with a brake pedal force booster
• CPC Class Codes: B60T 8/444 using vacuum B60T8/445, B60T8/446, B60T8/448 take precedence
• CPC Class Codes: B60T 8/447 Reducing the boost of the power-assist booster means to reduce brake pressure

Abstract

A hydraulic brake system for a motor vehicle supplies pressurized brake fluid to a wheel brake in response to a demand signal. The brake system includes a master cylinder in fluid communication with the wheel brake to control the actuation thereof. Furthermore, actuation of the master cylinder is controlled and/or amplified by first and second pressure-amplifying mechanisms, which are electrically controlled by an electrical control unit.

Claims

1. A hydraulic brake system for a motor vehicle providing pressurized brake fluid to a wheel brake in response to a demand signal, the brake system comprising:

a master cylinder in working communication with the wheel brake such as to control a pressure of the pressurized brake fluid;

a first pressure-amplifying mechanism in working communication with and configured to control the master cylinder in response to a first electrical output signal that is based on the demand signal;

a second pressure-amplifying mechanism in working communication with the wheel brake to control the pressure of the pressurized brake fluid in response to a second electrical output signal; and

an electronic control unit in electrical communication with the first and the second pressure-amplifying mechanisms to provide the first electrical output signal to the first pressure-amplifying mechanism and to provide the second electrical output signal to the second pressure-amplifying mechanism.

2. A hydraulic brake system as in claim 1, wherein the electronic control unit receives an electrical signal proportional to the demand signal and a first input signal such that the first and second electrical output signals are based on the demand signal and the first input signal, wherein the demand signal corresponds to a muscle force exerted on a brake pedal by a system user, and wherein the first input signal corresponds to a first pressure of the pressurized brake fluid exiting the master cylinder.

3. A hydraulic brake system as in claim 2, wherein the electronic control unit receives a second input signal such that the first and second electrical output signals are based on the demand signal, the first input signal, and the second input signal, wherein the second input signal corresponds to a second pressure of the pressurized brake fluid exiting the second pressure-amplifying mechanism.

4. A hydraulic brake system as in claim 3, further comprising:

a first pressure sensor configured to measure the first pressure and to provide the electrical control unit with the first input signal; and

a second pressure sensor configured to measure the second pressure and to provide the electrical control unit with the second input signal.

5. A hydraulic brake system as in claim 4, further comprising:

a road wheel selectively engaged by the wheel brake; and

a rotational wheel speed sensor measuring a rotational wheel speed of the road wheel and providing a third input signal corresponding to the rotational wheel speed to the electronic control unit, such that the first and second electrical output signals are based on the demand signal, the first input signal, the second input signal, and the third input signal.

6. A hydraulic brake system as in claim 1, further comprising:

a brake pedal configured to be depressed by a muscle force; and

a mechanical control unit connected to the brake pedal, the mechanical control unit configured to provide a mechanical signal proportional to the demand signal to the first pressure-amplifying mechanism to control the pressure of the pressurized brake fluid if at least one of the first and second pressure-amplifying mechanisms fails to increase the pressure of the pressurized brake fluid in correlation with the first electrical output signal.

7. A hydraulic brake system as in claim 6, wherein the mechanical control unit includes a push rod configured to engage a secondary activation means in the first pressure-amplifying mechanism to control the pressure of the pressurized brake fluid if at least one of the first and second pressure-amplifying mechanisms fails to increase the pressure of the pressurized brake fluid in correlation with the first electrical output signal.

8. A hydraulic brake system as in claim 1, further comprising:

a brake pedal configured to be depressed by a muscle force to generate the demand signal; and

a pedal feel simulator mechanically connected to the brake pedal, wherein the pedal feel simulator is configured to generate an electrical signal proportional to the demand signal based on the muscle force and to apply onto the brake pedal a reactionary force.

9. A hydraulic brake system as in claim 1, wherein the first pressure-amplifying mechanism includes a vacuum chamber and a valve, wherein the valve is configured to control a fluid connection between the vacuum chamber and ambient air based on the first electrical output signal.

10. A hydraulic brake system as in claim 9, wherein the second pressure-amplifying mechanism includes a hydraulic pump configured to urge the pressurized brake fluid towards the wheel brake.

11. A hydraulic brake system for a motor vehicle providing pressurized brake fluid to a wheel brake in response to a demand signal, the brake system comprising:

a master cylinder in working communication with the wheel brake such as to be configured to control a pressure of the pressurized brake fluid;

a vacuum booster in working communication with and configured to control the master cylinder in response to a first electrical output signal, the vacuum booster including a vacuum chamber and a valve vacuum chamber and a valve, wherein the valve is configured to control a fluid connection between the vacuum chamber and ambient air based on the first electrical output signal;

a hydraulic pump in working communication with the wheel brake and configured to urge the pressurized brake fluid towards the wheel brake to control the pressure of the pressurized brake fluid in response to a second output signal;

a first pressure sensor fluidly connected to the master cylinder such as to provide a first input signal corresponding to a first pressure of the pressurized brake fluid exiting the master cylinder;

a second pressure sensor fluidly connected to the hydraulic pump such as to provide a second input signal corresponding to a second pressure of the pressurized brake fluid exiting the hydraulic pump; and

a control unit in working communication with the first and second pressure sensors to receive the first and second input signals therefrom, such that the first and second output signals are based on the demand signal, the first input signal, and the second input signal, wherein the control unit is in working communication with the vacuum booster and the hydraulic pump to provide the first output signal to the vacuum booster and to provide the second output signal to the hydraulic pump.

12. A hydraulic brake system as in claim 11, further comprising:

a road wheel selectively engaged by the wheel brake to retard rotation of the road wheel; and

a rotational wheel speed sensor measuring a rotational wheel speed of the road wheel and providing a third input signal to the control unit, such that the first and second signals are based on the demand signal, the first input signal, the second input signal, and the third input signal.

13. A hydraulic brake system as in claim 11, further comprising:

a brake pedal configured to be depressed by a muscle force, wherein the demand signal corresponds to the muscle force; and

a pedal feel simulator mechanically connected to the brake pedal, the pedal feel simulator configured to generate an electrical signal based on the demand signal, and the pedal feel simulator configured to apply onto the brake pedal a reactionary force.

14. A hydraulic brake system as in claim 11, further comprising:

a brake pedal configured to be depressed by a muscle force; and

a mechanical control unit connected to the brake pedal and configured to provide a mechanical signal to the vacuum booster to increase the pressure of the pressurized brake fluid if at least one of the vacuum booster and the hydraulic pump fails to increase the pressure of the pressurized brake fluid in correlation with the first output signal.

15. A hydraulic brake system as in claim 14, further comprising a push rod connected to the brake pedal that selectively abuts an activation means of the vacuum booster to increase the pressure of the pressurized brake fluid when the at least one of the vacuum booster and the hydraulic pump fails to increase the pressure of the pressurized brake fluid in correlation with the first output signal.

16. A hydraulic brake system as in claim 15, wherein the first control signal causes the activation means to move in unison with the push rod such that the activation means and the push rod are prevented from abutting each other while the vacuum booster is increasing the pressure of the pressurized brake fluid in correlation with the first control signal.

17. A hydraulic brake system for a motor vehicle providing pressurized brake fluid to a wheel brake in response to a demand signal from a brake pedal, the brake system comprising:

a master cylinder in working communication with the wheel brake such as to control a pressure of the pressurized brake fluid in response to the demand signal;

a pressure-amplifying mechanism in working communication with and configured to control the master cylinder in response to an electrical signal based on the demand signal or a mechanical signal based on the demand signal;

a primary control unit in electrical communication with the pressure-amplifying mechanism such as to provide the electrical signal to the pressure-amplifying mechanism; and

a secondary control unit connected to the brake pedal and configured to provide the mechanical signal to the pressure-amplifying mechanism to increase the pressure of the pressurized brake fluid if the pressure-amplifying mechanism fails to increase the pressure of the pressurized brake fluid in correlation with the electrical signal.

18. A hydraulic brake system as in claim 17, further comprising:

a brake pedal configured to be depressed by a muscle force, wherein the demand signal is related to the muscle force; and

a push rod connected to the brake pedal that selectively abuts an activation means of the pressure-amplifying mechanism to create the mechanical signal and to increase the pressure of the pressurized brake fluid.

19. A hydraulic brake system as in claim 18, wherein the electrical signal causes the activation means to move in unison with the push rod such that the activation means and the push rod are prevented from abutting each other while the pressure-amplifying mechanism is increasing the pressure of the pressurized brake fluid in correlation with the electrical signal.