Vehicle dynamics control system

• US 6,003,959 A
• Filed: 12/08/1997
• Issued: 12/21/1999
• Est. Priority Date: 12/10/1996
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Unisia Jecs Corporation (Hitachi, Ltd.)
• Inventors: Imamura, Masamichi, Katayose, Shinji
• Primary Examiner(s): Butler, Douglas C.
• Application Number:
  US08/986,931
• Time in Patent Office: 743 Days
• Field of Search: 303/146, 303/147, 303/148, 303/139, 303/140, 701/72, 318/587, 318/586
• US Class Current: 303/146
• CPC Class Codes: B60T 2270/306 hydraulic system components
• CPC Class Codes: B60T 8/1755 Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve road vehicle drive control systems for control of driving stability otherwise than by controlling a particular sub-unit B60W30/02
• CPC Class Codes: B60T 8/246 Change of direction
• CPC Class Codes: B60T 8/4872 pump-back systems

Abstract

A vehicle dynamics control system for an automotive vehicle with a parallel split layout of brake circuits comprises a tandem master cylinder, a hydraulic pump fluidly disposed in one brake circuit, a selector valve for selecting a brake-fluid pressure to be fed to a first brake line from between the fluid pressure generated from the pump and the master-cylinder pressure, a plurality of pressure control valves for regulating a fluid pressure in each individual wheel-brake cylinder, vehicle sensors for detecting a vehicle'"'"'s cornering behavior, and a control unit being responsive to the sensor'"'"'s input information for controlling the respective control valves associated with the front wheel-brake cylinders. The control unit operates to supply the fluid pressure generated from the pump to an inner front wheel-brake cylinder in the vehicle understeer on turns. The control unit also operates to supply the fluid pressure generated from the pump to an outer front wheel-brake cylinder in the vehicle oversteer on turns.

Claims

1. A vehicle dynamics control system for an automotive vehicle with a parallel split layout of brake circuits, said system comprising:

a first brake line connected to a pair of front-left and front-right wheel-brake cylinders;

a second brake line connected to a pair of rear-left and rear-right wheel-brake cylinders;

a first brake-fluid pressure generator for generating a first brake-fluid pressure which is variable depending on a magnitude of brake-pedal depression;

a second brake-fluid pressure generator for generating a second brake-fluid pressure, independently of said first brake-fluid pressure based on the magnitude of brake-pedal depression;

a brake-fluid pressure selector valve means for selecting a brake-fluid pressure to be fed to said first brake line from between said first and second brake-fluid pressures;

a first pressure control valve means fluidly disposed in a first brake circuit including said first brake line for regulating a fluid pressure in said front-left wheel-brake cylinder;

a second pressure control valve means fluidly disposed in said first brake circuit including said first brake line for regulating a fluid pressure in said front-right wheel-brake cylinder;

a vehicle-behavior detector for detecting a vehicle'"'"'s cornering behavior; and

a brake-fluid pressure control means being responsive to input information from said vehicle-behavior detector for controlling said brake-fluid pressure selector valve means and said first and second pressure control valve means;

wherein said brake-fluid pressure control means operates to supply said second brake-fluid pressure to an inner front wheel-brake cylinder of said front-left and front-right wheel-brake cylinders for increasing a fluid pressure in the inner front wheel-brake cylinder and operates to reduce a fluid pressure in an outer front wheel-brake cylinder of said front-left and front-right wheel-brake cylinders to a predetermined minimum brake-fluid pressure level when said input information from said vehicle-behavior detector indicates a vehicle understeer during a turn, and said brake-fluid pressure control means operates to supply said second brake-fluid pressure to an outer front wheel-brake cylinder of said front-left and front-right wheel-brake cylinders for increasing a fluid pressure in the outer front wheel-brake cylinder and operates to reduce a fluid pressure in an inner front wheel-brake cylinder of said front-left and front-right wheel-brake cylinders to a predetermined minimum brake-fluid pressure level when said input information from said vehicle-behavior detector indicates a vehicle oversteer during a turn.

2. The vehicle dynamics control system as claimed in claim 1, wherein said first brake-fluid pressure generator comprises a dual-brake system master cylinder with two pistons set in tandem.

3. The vehicle dynamics control system as claimed in claim 1, wherein said second brake-fluid pressure generator comprises a single-directional type electric-motor driven hydraulic pump being disposed in said first brake circuit.

4. The vehicle dynamics control system as claimed in claim 1, wherein said vehicle-behavior detector comprises at least wheel speed sensors for monitoring front-left, front-right, rear-left and rear-right wheel speeds, a yaw-velocity sensor for monitoring a yaw velocity about a z-axis of the vehicle, a lateral acceleration sensor for monitoring a lateral acceleration exerted on the vehicle, and a steering angle sensor for monitoring a steer angle.

5. A vehicle dynamics control system for an automotive vehicle with a parallel split layout of brake circuits, said system comprising:

a first brake line connected to a pair of front-left and front-right wheel-brake cylinders;

a second brake line connected to a pair of rear-left and rear-right wheel-brake cylinders;

a first brake-fluid pressure generator for generating a first brake-fluid pressure which is variable depending on a magnitude of brake-pedal depression;

a second brake-fluid pressure generator for generating a second brake-fluid pressure, independently of said first brake-fluid pressure based on the magnitude of brake-pedal depression;

a brake-fluid pressure selector valve for selecting a brake-fluid pressure to be fed to said first brake line from between said first and second brake-fluid pressures;

a first group of pressure control valves fluidly disposed in a first brake circuit including said first brake line for regulating a fluid pressure in said front-left wheel-brake cylinder;

a second group of pressure control valves fluidly disposed in said first brake circuit including said first brake line for regulating a fluid pressure in said front-right wheel-brake cylinder;

a vehicle-behavior detector for detecting a vehicle'"'"'s cornering behavior; and

a control unit being configured to be connected to said vehicle-behavior detector for controlling said brake-fluid pressure selector valve and said first and second groups of pressure control valves in response to input information from said vehicle-behavior detector;

wherein said control unit operates to supply said second brake-fluid pressure to an inner front wheel-brake cylinder of said front-left and front-right wheel-brake cylinders for increasing a fluid pressure in the inner front wheel-brake cylinder and operates to reduce a fluid pressure in an outer front wheel-brake cylinder of said front-left and front-right wheel-brake cylinders to a predetermined minimum brake-fluid pressure level when said input information from said vehicle-behavior detector indicates a vehicle understeer during a turn, and said control unit operates to supply said second brake-fluid pressure to an outer front wheel-brake cylinder of said front-left and front-right wheel-brake cylinders for increasing a fluid pressure in the outer front wheel-brake cylinder and operates to reduce a fluid pressure in an inner front wheel-brake cylinder of said front-left and front-right wheel-brake cylinders to a predetermined minimum brake-fluid pressure level when said input information from said vehicle-behavior detector indicates a vehicle oversteer during a turn.

6. The vehicle dynamics control system as claimed in claim 5, wherein said first brake-fluid pressure generator comprises a dual-brake system master cylinder with two pistons set in tandem.

7. The chicle dynamics control system as claimed in claim 5, wherein said second brake-fluid pressure generator comprises a single-directional type electric-motor driven hydraulic pump being disposed in said first brake circuit.

8. The vehicle dynamics control system as claimed in claim 5, wherein said vehicle-behavior detector comprises at least wheel speed sensors for monitoring front-left, front-right, rear-left and rear-right wheel speeds, a yaw-velocity sensor for monitoring a yaw velocity about a z-axis of the vehicle, a lateral acceleration sensor for monitoring a lateral acceleration exerted on the vehicle, and a steering angle sensor for monitoring a steer angle.