Vehicle brake system and method of operating

Patent metadata

Field	Value
Publication number	US-10189456-B2
Application number	US-201615391403-A
Country	US
Kind code	B2
Filing date	Dec 27, 2016
Priority date	Dec 27, 2016
Publication date	Jan 29, 2019
Grant date	Jan 29, 2019

Abstract

A brake system comprises a master cylinder, a first brake cylinder, a second brake cylinder, an electronically-controlled pressure generating unit distinct from the master cylinder, a first hydraulic circuit in selective fluid communication with the master cylinder and the first brake cylinder, a second hydraulic circuit in selective fluid communication with the master cylinder and the second brake cylinder, and a controller. In a first mode, the controller is operable to actuate the electronically-controlled pressure generating unit to deliver hydraulic fluid pressure to the first brake cylinder and the second brake cylinder proportional to an input. In a second mode, the controller is operable to actuate the electronically-controlled pressure generating unit to deliver hydraulic fluid pressure to the first hydraulic circuit and the first brake cylinder and the master cylinder is in communication with the second hydraulic circuit to deliver hydraulic fluid pressure to the second brake cylinder.

First claim

What is claimed is:

1. A vehicle brake system comprising:
a master cylinder;
a first plurality of brake cylinders provided at a first vehicle axle;
a second plurality of brake cylinders provided at a second vehicle axle;
an electronically-controlled pressure generating unit distinct from the master cylinder;
a first hydraulic circuit in selective fluid communication with the master cylinder and the first plurality of brake cylinders;
a second hydraulic circuit in selective fluid communication with the master cylinder and the second plurality of brake cylinders;
a first isolation valve in the first hydraulic circuit;
a second isolation valve in the second hydraulic circuit; and
a controller operable to receive an input;
wherein, in a first mode, the controller is operable to actuate the electronically-controlled pressure generating unit to deliver hydraulic fluid pressure to the first hydraulic circuit and separately to the second hydraulic circuit proportional to the input,
wherein, in a second mode, the controller is operable to actuate the electronically-controlled pressure generating unit to deliver hydraulic fluid pressure to the first hydraulic circuit and the first plurality of brake cylinders and the master cylinder is in communication with the second hydraulic circuit to deliver hydraulic fluid pressure to the second plurality of brake cylinders,
wherein, in the second mode, the second isolation valve is open to provide a fluid path between the master cylinder and the second plurality of brake cylinders and the first isolation valve is closed to block a fluid path between the master cylinder and the first plurality of brake cylinders.

2. The vehicle brake system of claim 1 , wherein, in the second mode, the master cylinder and the electronically-controlled pressure generating unit are operable to deliver hydraulic fluid pressure to the second plurality of brake cylinders proportional to the input.

3. The vehicle brake system of claim 1 , wherein the electronically-controlled pressure generating unit is a motor-driven piston.

4. The vehicle brake system of claim 1 , wherein the input is a signal indicative of a user input force provided to the master cylinder via a brake pedal.

5. The vehicle brake system of claim 1 , further comprising a sensor operable to provide the input to the controller, wherein the sensor is one of a pressure sensor, a pedal travel sensor, or a pedal force sensor.

6. The vehicle brake system of claim 1 , further comprising a pedal feel simulator, wherein the master cylinder is in communication with the pedal feel simulator in the first mode.

7. The vehicle brake system of claim 1 , further comprising:
a first control valve in the first hydraulic circuit; and
a second control valve in the second hydraulic circuit,
wherein, in the first mode, the first and second control valves open to provide a fluid path between the electronically-controlled pressure generating unit and the respective first and second brake circuits, and
wherein, in the second mode, the first control valve opens to provide a fluid path between the electronically-controlled pressure generating unit and the first brake circuit and the second control valve is closed to block a fluid path between the electronically-controlled pressure generating unit and the second plurality of brake cylinders.

8. A method of operating a vehicle brake system, the vehicle including a first plurality of brake cylinders provided at a first vehicle axle and a second plurality of brake cylinders provided at a second vehicle axle, the method comprising:
operating the vehicle brake system in a primary brake-by-wire mode in which a hydraulic pressure is applied to a first hydraulic circuit and the first plurality of brake cylinders and separately to a second hydraulic circuit and the second plurality of brake cylinders via an electronically-controlled pressure generating unit in response to depression of a brake pedal;
identifying via a controller that the vehicle brake system is inoperable in the primary brake-by-wire mode; and
subsequent to identifying that the vehicle brake system is inoperable in the primary brake-by-wire mode, operating the vehicle brake system as follows when the brake pedal is depressed:
actuating the electronically-controlled pressure generating unit via the controller to provide a first hydraulic pressure to the first plurality of brake cylinders while a fluid path between the electronically-controlled pressure generating unit and the second plurality of brake cylinders is closed; and
opening a fluid path between a master cylinder and the second plurality of brake cylinders, thereby providing a second hydraulic pressure to the second plurality of brake cylinders.

9. The method of claim 8 , wherein the first hydraulic pressure is adjustable relative to the second hydraulic pressure.

10. The method of claim 8 , wherein the first hydraulic pressure and the second hydraulic pressure are applied concurrently.

11. The method of claim 8 , wherein the first and second hydraulic pressures are dependent upon a user input force to the brake pedal, and wherein the hydraulic pressure applied to the first plurality of brake cylinders and second plurality of brake cylinders in the primary brake-by-wire mode is a third hydraulic pressure, and wherein the third hydraulic pressure is dependent upon the user input force.

12. The method of claim 8 , wherein the electronically-controlled pressure generating unit is a piston, and wherein actuating the electronically-controlled pressure generating unit further comprises actuating a motor to drive the piston to produce the first hydraulic pressure.

13. A vehicle brake system comprising:
a first plurality of brake cylinders provided at a first vehicle axle;
a second plurality of brake cylinders provided at a second vehicle axle;
an electronically-controlled pressure generating unit operable to selectively provide pressurized fluid to the first plurality of brake cylinders and the second plurality of brake cylinders;
a master cylinder operable to pressurize fluid in response to an input force;
a pedal feel simulator operable to provide a reaction force in response to the input force;
a first valve connecting the electronically-controlled pressure generating unit to the first plurality of brake cylinders;
a second valve connecting the electronically-controlled pressure generating unit to the second plurality of brake cylinders; and
a controller operable to identify an input and transition the vehicle brake system from a brake-by-wire configuration to a back-up configuration in response to the input,
wherein, in the brake-by-wire configuration, the electronically-controlled pressure generating unit provides pressurized fluid to the first plurality of brake cylinders and separately to the second plurality of brake cylinders, and the master cylinder provides pressurized fluid to the pedal feel simulator, and
wherein, in the back-up configuration, the electronically-controlled pressure generating unit provides pressurized fluid to the first plurality of brake cylinders, and the master cylinder provides pressurized fluid to the second plurality of brake cylinders
wherein, in the brake-by-wire configuration, the electronically-controlled pressure generating unit provides pressurized fluid through the first valve to the first plurality of brake cylinders and through the second valve to the second plurality of brake cylinders, and
wherein in the back-up configuration the electronically-controlled pressure generating unit provides pressurized fluid through the first valve to the first plurality of brake cylinders

Assignees

• Bosch Gmbh Robert

Inventors

• Foitzik Bertram
• Wu Hsien-Cheng
• Zhou Wenguang

Classifications

• B60T2270/82

  Brake-by-Wire, EHB · CPC title

• B60T8/4081

  Systems with stroke simulating devices for driver input (B60T8/4077 takes precedence) · CPC title

• B60T13/745 Primary

  acting on a hydraulic system, e.g. a master cylinder · CPC title

• B60T8/00

  Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force (by changing number of effective brake cylinders in power brake systems B60T17/10) · CPC title

• B60T2270/404

  Brake-by-wire or X-by-wire failsafe · CPC title