Braking force distribution control apparatus and method

• US 20050182550A1
• Filed: 02/10/2005
• Published: 08/18/2005
• Est. Priority Date: 02/12/2004
• Status: Active Grant

• Current Assignee: Advics Company Limited (Aisin Corp.)
• Original Assignee: Advics Company Limited (Aisin Corp.)
• Inventors: Matsuura, Masahiro
• Granted Patent: US 7,185,957 B2
• Time in Patent Office: Days
• US Class Current: 701/78
• CPC Class Codes: B60T 2240/03 Tire sensors
• CPC Class Codes: B60T 8/1725 Using tyre sensors, e.g. Sidewall Torsion sensors [SWT] for tyre pressure and temperature detection B60C23/00
• CPC Class Codes: B60T 8/1766 Proportioning of brake forces according to vehicle axle loads, e.g. front to rear of vehicle

Abstract

A braking force distribution apparatus for a vehicle includes pressure sensors for detecting the internal pressures of the tires, and wheel speed sensors for detecting the angular speeds of the wheels. The apparatus obtains a dynamic load radius change rate of each tire which corresponds to the deviation of the internal pressure of the tire from a reference pressure, obtains a wheel speed for calculation of a slip value on the basis of the angular speed of the tire and the change rate, and obtains a slip value on the basis of the obtained wheel speed. As a result, EBD control is started at proper timing in accordance with the slip value.

Claims

1. A braking force distribution apparatus for a vehicle, comprising:

front-wheel braking force application means for applying to a front wheel of the vehicle a braking force corresponding to a braking operation;

rear-wheel braking force application means for applying to a rear wheel of the vehicle a braking force corresponding to the braking operation and a control signal;

front-wheel wheel speed obtaining means for obtaining peripheral speed of a tire of the front wheel as front-wheel wheel speed;

rear-wheel wheel speed obtaining means for obtaining peripheral speed of a tire of the rear wheel as rear-wheel wheel speed;

slip value calculation means, operable when the braking operation is performed, for calculating a slip value on the basis of the obtained front-wheel wheel speed and rear-wheel wheel speed, the slip value corresponding to the degree of slippage of the rear wheel with respect to the front wheel; and

control signal generation means for generating the control signal in such a manner that the ratio of the braking force applied to the rear wheel to the braking force applied to the front wheel decreases in accordance with the calculated slip value, wherein,

the front-wheel wheel speed obtaining means includes;

front-wheel angular speed detection means for detecting angular speed of the front wheel;

front-wheel tire pressure detection means for detecting internal pressure of the tire of the front wheel; and

front-wheel wheel speed calculation means for calculating the wheel speed of the front wheel on the basis of the detected angular speed of the front wheel and the detected internal pressure of the tire of the front wheel, and

the rear-wheel wheel speed obtaining means includes;

rear-wheel angular speed detection means for detecting angular speed of the rear wheel;

rear-wheel tire pressure detection means for detecting internal pressure of the tire of the rear wheel; and

rear-wheel wheel speed calculation means for calculating the wheel speed of the rear wheel on the basis of the detected angular speed of the rear wheel and the detected internal pressure of the tire of the rear wheel.

2. A braking force distribution apparatus according to claim 1, further comprising:

reference pressure setting means for setting, in response to an external operation signal, values corresponding to the tire internal pressure of the front wheel and the tire internal pressure of the rear wheel, respectively, as a reference tire pressure of the front wheel and a reference tire pressure of the rear wheel, wherein

the front-wheel wheel speed calculation means calculates a value indicative of a change in dynamic load radius of the tire of the front wheel on the basis of a deviation of the detected tire internal pressure of the front wheel from the reference tire pressure of the front wheel, and calculates the wheel speed of the front wheel on the basis of the detected angular speed of the front wheel and the calculated value indicative of the change in dynamic load radius of the tire of the front wheel;

the rear-wheel wheel speed calculation means calculates a value indicative of a change in dynamic load radius of the tire of the rear wheel on the basis of a deviation of the detected tire internal pressure of the rear wheel from the reference tire pressure of the rear wheel, and calculates the wheel speed of the rear wheel on the basis of the detected angular speed of the rear wheel and the calculated value indicative of the change in dynamic load radius of the tire of the rear wheel; and

the slip value calculation means calculates the slip value on the basis of the calculated wheel speed of the front wheel and the calculated wheel speed of the rear wheel.

3. A braking force distribution apparatus according to claim 1, wherein

the front-wheel wheel speed calculation means includes front-wheel tire pressure condition determination means for determining whether the detected tire internal pressure of the front wheel satisfies a prescribed pressure condition for the front wheel, calculates the wheel speed of the front wheel on the basis of the detected angular speed of the front wheel and the detected tire internal pressure of the front wheel when the detected tire internal pressure of the front wheel does not satisfy the pressure condition for the front wheel, and calculates the wheel speed of the front wheel on the basis of the detected angular speed of the front wheel without consideration of the detected tire internal pressure of the front wheel when the detected tire internal pressure of the front wheel satisfies the pressure condition for the front wheel;

and

the rear-wheel wheel speed calculation means includes rear-wheel tire pressure condition determination means for determining whether the detected tire internal pressure of the rear wheel satisfies a prescribed pressure condition for the rear wheel, calculates the wheel speed of the rear wheel on the basis of the detected angular speed of the rear wheel and the detected tire internal pressure of the rear wheel when the detected tire internal pressure of the rear wheel does not satisfy the pressure condition for the rear wheel, and calculates the wheel speed of the rear wheel on the basis of the detected angular speed of the rear wheel without consideration of the detected tire internal pressure of the rear wheel when the detected tire internal pressure of the rear wheel satisfies the pressure condition for the rear wheel.

4. A braking force distribution apparatus for a four-wheeled vehicle, comprising:

front-wheel braking force application means for applying to left and right front wheels of the vehicle a braking force corresponding to a braking operation;

rear-wheel braking force application means for applying to left and right rear wheels of the vehicle a braking force corresponding to the braking operation and a control signal;

front-wheel wheel speed obtaining means for obtaining a front-wheel wheel speed substantially representing the wheel speed of the front wheels;

rear-wheel wheel speed obtaining means for obtaining a rear-wheel wheel speed substantially representing the wheel speed of the rear wheels;

slip value calculation means, operable when the braking operation is performed, for calculating a slip value on the basis of the obtained front-wheel wheel speed and rear-wheel wheel speed, the slip value corresponding to the degree of slippage of the rear wheels with respect to the front wheels; and

control signal generation means for generating the control signal in such a manner that the ratio of the braking force applied to the rear wheels to the braking force applied to the front wheels decreases in accordance with the calculated slip value,

wherein the front-wheel wheel speed obtaining means includes;

front-wheel angular speed detection means for detecting angular speed of the left front wheel and angular speed of the right front wheel;

front-wheel tire pressure detection means for detecting internal pressure of the tire of the left front wheel and internal pressure of the tire of the right front wheel;

front-wheel tire pressure condition determination means for determining whether each of the detected internal pressure of the tire of the left front wheel and the detected internal pressure of the tire of the right front wheel satisfies a predetermined pressure condition for the front wheels; and

front-wheel wheel speed calculation means for calculating the wheel speed of the front wheels on the basis of the angular speeds of the left and right front wheels when both the detected internal pressures of the tires of the left and right front wheels satisfy the pressure condition for the front wheels, and for calculating the wheel speed of the front wheels on the basis of the angular speed of one wheel which satisfies the pressure condition for the front wheels without consideration of the angular speed of the other wheel which fails to satisfy the pressure condition for the front wheels when only one of the detected internal pressures of the tires of the left and right front wheels satisfies the pressure condition for the front wheels, and

the rear-wheel wheel speed obtaining means includes;

rear-wheel angular speed detection means for detecting angular speed of the left rear wheel and angular speed of the right rear wheel;

rear-wheel tire pressure detection means for detecting internal pressure of the tire of the left rear wheel and internal pressure of the tire of the right rear wheel;

rear-wheel tire pressure condition determination means for determining whether each of the detected internal pressure of the tire of the left rear wheel and the detected internal pressure of the tire of the right rear wheel satisfies a predetermined pressure condition for the rear wheels; and

rear-wheel wheel speed calculation means for calculating the wheel speed of the rear wheels on the basis of the angular speeds of the left and right rear wheels when both the detected internal pressures of the tires of the left and right rear wheels satisfy the pressure condition for the rear wheels, and for calculating the wheel speed of the rear wheels on the basis of the angular speed of one wheel which satisfies the pressure condition for the rear wheels without consideration of the angular speed of the other wheel which fails to satisfy the pressure condition for the rear wheels when only one of the detected internal pressures of the tires of the left and right rear wheels satisfies the pressure condition for the rear wheels.

5. A braking force distribution apparatus for a four-wheeled vehicle, comprising:

front-wheel braking force application means for applying to left and right front wheels of the vehicle a braking force corresponding to a braking operation;

rear-wheel braking force application means for applying to left and right rear wheels of the vehicle a braking force corresponding to the braking operation and a control signal;

front-wheel wheel speed obtaining means for obtaining a front-wheel wheel speed substantially representing the wheel speed of the front wheels;

rear-wheel wheel speed obtaining means for obtaining a rear-wheel wheel speed substantially representing the wheel speed of the rear wheels;

slip value calculation means, operable when the braking operation is performed, for calculating a slip value on the basis of the obtained front-wheel wheel speed and rear-wheel wheel speed, the slip value corresponding to the degree of slippage of the rear wheels with respect to the front wheels; and

control signal generation means for generating the control signal in such a manner that the ratio of the braking force applied to the rear wheels to the braking force applied to the front wheels decreases in accordance with the calculated slip value, wherein,

the front-wheel wheel speed obtaining means includes;

front-wheel angular speed detection means for detecting angular speed of the left front wheel and angular speed of the right front wheel;

front-wheel tire temperature detection means for detecting internal temperature of the tire of the left front wheel and internal temperature of the tire of the right front wheel;

front-wheel tire temperature condition determination means for determining whether each of the detected internal temperature of the tire of the left front wheel and the detected internal temperature of the tire of the right front wheel satisfies a predetermined temperature condition for the front wheels; and

front-wheel wheel speed calculation means for calculating the wheel speed of the front wheels on the basis of the angular speeds of the left and right front wheels when both the detected internal temperatures of the tires of the left and right front wheels satisfy the temperature condition for the front wheels, and for calculating the wheel speed of the front wheels on the basis of the angular speed of one wheel which satisfies the temperature condition for the front wheels without consideration of the angular speed of the other wheel which fails to satisfy the temperature condition for the front wheels when only one of the detected internal temperatures of the tires of the left and right front wheels satisfies the temperature condition for the front wheels, and

the rear-wheel wheel speed obtaining means includes;

rear-wheel angular speed detection means for detecting angular speed of the left rear wheel and angular speed of the right rear wheel;

rear-wheel tire temperature detection means for detecting internal temperature of the tire of the left rear wheel and internal temperature of the tire of the right rear wheel;

rear-wheel tire temperature condition determination means for determining whether each of the detected internal temperature of the tire of the left rear wheel and the detected internal temperature of the tire of the right rear wheel satisfies a predetermined temperature condition for the rear wheels; and

rear-wheel wheel speed calculation means for calculating the wheel speed of the rear wheels on the basis of the angular speeds of the left and right rear wheels when both the detected internal temperatures of the tires of the left and right rear wheels satisfy the temperature condition for the rear wheels, and for calculating the wheel speed of the rear wheels on the basis of the angular speed of one wheel which satisfies the temperature condition for the rear wheels without consideration of the angular speed of the other wheel which fails to satisfy the temperature condition for the rear wheels when only one of the detected internal temperatures of the tires of the left and right rear wheels satisfies the temperature condition for the rear wheels.

6. A braking force distribution method for a vehicle, comprising:

detecting angular speed of a front wheel of the vehicle;

detecting internal pressure of the tire of the front wheel;

calculating, as front-wheel wheel speed, peripheral speed of the tire of the front wheel on the basis of the detected angular speed of the front wheel and the detected internal pressure of the tire of the front wheel;

detecting angular speed of a rear wheel of the vehicle;

detecting internal pressure of the tire of the rear wheel;

calculating, as rear-wheel wheel speed, the peripheral speed of the tire of the rear wheel on the basis of the detected angular speed of the rear wheel and the detected internal pressure of the tire of the rear wheel;

calculating, when a braking operation is performed, a slip value on the basis of the calculated front-wheel wheel speed and rear-wheel wheel speed, the slip value corresponding to the degree of slippage of the rear wheel with respect to the front wheel;

generating a control signal in such a manner that the ratio of the braking force applied to the rear wheel to the braking force applied to the front wheel decreases in accordance with the calculated slip value; and

applying to the front wheel of the vehicle a braking force corresponding to the braking operation, and applying to the rear wheel of the vehicle a braking force corresponding to the braking operation and the generated control signal.

7. A braking force distribution method according to claim 6, further comprising:

setting, in response to an external operation signal, values corresponding to the tire internal pressure of the front wheel and the tire internal pressure of the rear wheel, respectively, as a reference tire pressure of the front wheel and a reference tire pressure of the rear wheel;

calculating a value indicative of a change in dynamic load radius of the tire of the front wheel on the basis of a deviation of the detected tire internal pressure of the front wheel from the reference tire pressure of the front wheel, and calculating the wheel speed of the front wheel on the basis of the detected angular speed of the front wheel and the calculated value indicative of the change in dynamic load radius of the tire of the front wheel;

calculating a value indicative of a change in dynamic load radius of the tire of the rear wheel on the basis of a deviation of the detected tire internal pressure of the rear wheel from the reference tire pressure of the rear wheel, and calculating the wheel speed of the rear wheel on the basis of the detected angular speed of the rear wheel and the calculated value indicative of the change in dynamic load radius of the tire of the rear wheel; and

calculating the slip value on the basis of the calculated wheel speed of the front wheel and the calculated wheel speed of the rear wheel.