Brake control system for a motor vehicle

• US 20060049687A1
• Filed: 09/06/2005
• Published: 03/09/2006
• Est. Priority Date: 09/06/2004
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Higuma, Motohiro, Iizuka, Isamu
• Granted Patent: US 7,527,339 B2
• Time in Patent Office: Days
• US Class Current: 303/11
• CPC Class Codes: B60T 2201/12 Pre-actuation of braking systems without significant braking effect; Optimizing brake performance by reduction of play between brake pads and brake disc
• CPC Class Codes: B60T 7/12 for automatic initiation; for initiation not subject to will of driver or passenger limiting speed of vehicles other than rail vehicles B60K31/00
• CPC Class Codes: B60T 8/4872 pump-back systems

Abstract

A brake control system for a motor vehicle comprising a brake control unit which controls increasing and decreasing of a brake pressure of a wheel cylinder from a pressure source by driving plural solenoid valves without a brake operation by a driver. The system comprises a flow back control unit which controls the brake pressure of a wheel cylinder to drive the plural solenoid valves before control by the brake control unit and returns the brake fluid to the pressure source from the wheel cylinder.

Claims

1. A brake control system for a motor vehicle comprising:

a brake control unit which controls increasing and decreasing of a brake pressure of a wheel cylinder from a pressure source by driving plural solenoid valves without a brake operation by a driver, and

a flow back control unit which controls the brake pressure of the wheel cylinder to drive the plural solenoid valves before control by the brake control unit, and returns the brake fluid to the pressure source from the wheel cylinder.

2. A brake control system for a motor vehicle comprising:

a wheel cylinder which is provided in a wheel,

a brake pressure source which generates a brake pressure,

a brake pressure circuit which connects the brake pressure source and the wheel cylinder,

plural solenoid valves which are provided to the brake pressure circuit,

a brake control unit which adjusts increasing and decreasing of a brake pressure of a wheel cylinder from the brake pressure source by driving plural solenoid valves without a brake operation by a driver;

wherein the brake control unit controls the plural solenoid valves to open and control a flow of a brake fluid from the brake pressure source to the wheel cylinder substantially at the beginning of a control by the brake control unit.

3. A brake control system as claimed in claim 2,

further comprising a wheel pressure detector which detects a brake pressure in the wheel cylinder,

wherein the brake control unit provides a pressurization management to control plural solenoid valves to open and control flow of a brake fluid from the brake pressure source to the wheel cylinder substantially at the beginning a control by the brake control unit, based on the wheel pressure detected by the wheel pressure detector.

4. A brake control system as claimed in claim 3,

wherein the brake control unit is operative to cancel the pressurization management when a detected brake pressure by the wheel pressure detector is higher than a predetermined value.

5. A brake control system as claimed in claim 4,

wherein the wheel cylinder has a brake pad which engages a brake rotor on the wheel based on the application of wheel cylinder pressure, and

wherein the predetermined value is a wheel cylinder pressure that is identified when there is substantially no clearance between the brake pad and the brake rotor.

6. A brake control system as claimed in claim 5,

further comprising a vehicle stability detector which detects a stability of the vehicle,

wherein an actuation time of the pressurization management is established based on the stability of the vehicle detected by the vehicle stability detector.

7. A brake control system as claimed in claim 6,

wherein the vehicle stability detector detects at least lateral-G, and

wherein the actuation time of the pressurization that is established based on an amount of the lateral-G becomes longer as the amount of the lateral-G becomes higher.

8. A brake control system as claimed in claim 6,

wherein the vehicle stability detector detects at least cornering rate of the vehicle, and

wherein the actuation time of the pressurization that is established based on a rate of the cornering becomes longer as rate of the cornering becomes high.

9. A brake control system as claimed in claim 3,

a first wheel cylinder and a second wheel cylinder are connected via a brake pressure circuit system comprising the brake pressure source,

further comprising an outflow calculation unit that estimates or detects outflow from the second wheel cylinder a predetermined time before stating a decreasing control of the first wheel cylinder controlled currently, and

wherein the brake control unit interrupts the pressurization management when the amount of the brake fluid detected by the outflow calculation unit is higher than a predetermined value.

10. A brake control system as claimed in claim 9,

wherein each wheel cylinder is provided with a brake pad which engages a rotor provided to a corresponding wheel, and

wherein the predetermined value is established based upon a pressure of the wheel cylinder when there is substantially no clearance between the brake pad and rotor and when a flow of the brake fluid from the second wheel cylinder influences the first wheel cylinder.

11. A brake control system for a motor vehicle comprising:

a wheel cylinder which is provided to a wheel,

a master cylinder,

a first fluid circuit which connects the master cylinder and the wheel cylinder,

a first solenoid valve which is provided in the first fluid circuit and controls the opening and closing of the first fluid circuit between the master cylinder and the wheel cylinder,

a pressure control valve which is provided in the first fluid circuit downstream of the first solenoid valve and controls an increase and decrease of the brake pressure into the wheel cylinder,

a pump which has a discharge portion connecting to the first fluid circuit and can provide brake fluid to the wheel cylinder,

a second fluid circuit which connects a suction portion of the pump upstream of the first solenoid valve of the first pressure circuit,

a second solenoid valve which is provided in the second fluid circuit and can control supply of fluid to the suction portion of the pump,

a brake control unit which controls increasing and decreasing of a brake pressure of the wheel cylinder to drive the first solenoid valve, the second solenoid valve and the pressure control valve without a braking operation by a driver,

wherein the brake control unit controls the first and the second solenoid valves to open and controls a flow of brake fluid from the brake pressure source to the wheel cylinder before controlling increase and decrease of the brake pressure.

12. A brake control system for a motor vehicle as claimed in claim 11,

further comprising a wheel pressure detector which detects a brake pressure in the wheel cylinder,

wherein the brake control unit provides a pressurization management which actuates to control plural solenoid valves to open and control flow of a brake fluid from the brake pressure source to the wheel cylinder when beginning a control by the brake control unit, based on the wheel pressure detected by the wheel pressure detector.

13. A brake control system for a motor vehicle as claimed in claim 11,

wherein the brake control unit is operative to cancel the pressurization management when a detected brake pressure by the wheel pressure detector is higher than a predetermined value.

14. A brake control system for a motor vehicle as claimed in claim 13,

wherein the wheel cylinder has a brake pad which engages a brake rotor on the wheel based on the application of wheel cylinder pressure, and

wherein the predetermined value defines a wheel cylinder pressure that is identified when there is substantially no between the brake pad and the brake rotor.

15. A brake control system as claimed in claim 14,

further comprising a vehicle stability detector which detects a stability of the vehicle,

wherein an actuation time of the pressurization management is established based on the stability of the vehicle detected by the vehicle stability detector.

16. A brake control system for a motor vehicle as claimed in claim 15,

wherein the vehicle stability detector detects at least lateral-G, and

wherein the actuation time of the pressurization management that is established based on an amount of the lateral-G becomes longer as the amount the lateral-G becomes higher.

17. A brake control system for a motor vehicle as claimed in claim 15,

wherein the vehicle stability detector detects at least cornering rate of the vehicle, and

wherein the actuation time of the pressurization management that is established based on a rate of the cornering becomes longer as rate of cornering becomes longer.

18. A brake control system for a motor vehicle as claimed in claim 12,

wherein a first wheel cylinder and a second wheel cylinder are provided to the brake pressure circuit system comprising the brake pressure source,

wherein an outflow calculation unit that estimates or detects outflow from the second wheel cylinder a predetermined time before stating a decreasing control of the first wheel cylinder controlled currently, and

wherein the brake control unit interrupts the pressurization management when an amount of the brake fluid detected by the outflow calculation unit is higher than a predetermined value.

19. A brake control system for a motor vehicle as claimed in claim 18,

wherein each wheel cylinder is provided with a brake pad which engages a rotor is provided to a corresponding wheel, and

wherein the predetermined value is established based upon a pressure of the wheel cylinder when there is substantially zero clearance between the brake pad and rotor when a flow of the brake fluid from the second wheel cylinder influences the first wheel cylinder.

20. A brake control system for a motor vehicle comprising:

a pressure generation means for generating a pressure,

a brake control means for increasing and decreasing a brake pressure in a wheel cylinder from the pressure generation means to drive plural solenoid valves,

a flow back control means for controlling a brake fluid in the wheel cylinder to drive the plural solenoid valves before starting operation of the brake control means and return the brake pressure to the pressure generation means from the wheel cylinder of the brake pressure in the wheel cylinder.

21. A method of brake control for a motor vehicle based on an increase and a decrease of brake pressure in a wheel cylinder using plural solenoid valves without brake operation by driver comprising:

pumping a brake fluid to a wheel cylinder,

controlling a flow back such that the brake fluid flows back from wheel cylinder to the pump by driving plural solenoid valves; and

controlling increasing and decreasing of the brake pressure in the wheel cylinder after the flow back.