Brake apparatus for vehicle

• US 6,533,370 B2
• Filed: 10/24/2001
• Issued: 03/18/2003
• Est. Priority Date: 10/25/2000
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Yamaguchi, Masanobu, Takeshita, Takayuki, Imoto, Yuzo, Yokoyama, Takahisa
• Primary Examiner(s): Graham, Matthew C.
• Application Number:
  US09/983,440
• Publication Number:
  US 20020047305A1
• Time in Patent Office: 510 Days
• Field of Search: 303/163, 303/156, 303/157, 303/158, 303/168
• US Class Current: 303/163
• CPC Class Codes: B60T 8/17616 Microprocessor-based systems

Abstract

In a vehicle brake apparatus for executing ABS control to prevent a wheel from locking in such a manner that braking force is controlled so as to keep a slip ratio of a wheel at a target slip ratio so that an excessive drop of a wheel speed from a vehicle body speed is adjusted, an output current for driving a braking actuator is set to a current on which oscillating waves are superimposed during ABS control so that the wheel speed changes to show oscillating waves. Even if the wheel speed once drops to an extent that the slip ratio exceeds the target slip ratio, further decrease of the wheel speed is restricted and the wheel speed turns to an increase soon and this cycle is repeated. Accordingly, there occurs no excessive drop of the wheel speed due to the response delay so that sufficient braking force is generated.

Claims

1. A vehicle brake apparatus having slip ratio calculation means for calculating a slip ratio based on vehicle body speed and wheel speed in which ABS control is executed to prevent a wheel from locking in such a manner that braking force is controlled so as to keep the slip ratio at a target slip ratio so that an excessive drop of the wheel speed from the vehicle body speed is adjusted, comprising:

a braking actuator for adjusting braking force applied to a wheel;

a drive circuit for generating an output current by which the braking actuator is driven,

wherein the output current during ABS control is a current on which oscillating waves are superimposed so that the wheel speed changes to show oscillating waves; and

wheel speed phase delay calculation means for calculating a phase delay of the oscillating waves of the wheel speed from those of the output current and detecting whether the wheel speed drops to an extent that the slip ratio exceeds the target slip ratio in use of the calculated phase delay.

2. A vehicle brake apparatus in which ABS control is executed to prevent a wheel from locking in such a manner that braking force is controlled so as to keep a slip ratio of a wheel at a target slip ratio so that an excessive drop of wheel speed from vehicle body speed is adjusted, comprising:

a braking actuator for adjusting braking force applied to a wheel;

a drive circuit for generating an output current by which the braking actuator is driven;

slip ratio calculation means for calculating the slip ratio based on the vehicle body speed and the wheel speed;

first instruction current calculation means for calculating first instruction current corresponding to a depression state of a brake pedal;

second instruction current calculation means for calculating second instruction current necessary for controlling braking force so as to keep the slip ratio at a vicinity of the target slip ratio once the slip ratio exceeds the target slip ratio during ABS control;

comparison means for comparing the first instruction current with the second instruction current and generating third instruction current, the third instruction current being the first instruction current when the second instruction current is larger than the first instruction current and the second instruction current when the second instruction current is smaller than the first instruction current;

oscillating wave calculation means for generating fourth instruction current formed by superimposing oscillating waves on the third instruction current,

wherein the fourth instruction current during ABS control corresponds to the output current by which the braking actuator is driven so that the wheel speed changes to show oscillating waves.

3. A vehicle brake apparatus according to claim 2, wherein the slip ratio calculation means further detects whether or not the wheel speed drops to an extent that the slip ratio exceeds the target slip ratio in use of an integration value of the slip ratio after starting ABS control.

4. A vehicle brake apparatus according to claim 2, wherein the slip ratio calculation means further detects whether or not the wheel speed drops to an extent that the slip ratio exceeds the target slip ratio in use of an integration value of differences between the wheel speed and the vehicle body speed after starting ABS control.

5. A vehicle brake apparatus according to claim 2, further comprising:

wheel speed variation calculation means for calculating a variation range of the wheel speed and detects whether or not the wheel speed drops to an extent that the slip ratio exceeds the target slip ratio in use of the calculated variation range.

6. A vehicle brake apparatus according to claim 2, further comprising:

wheel speed phase delay calculation means for calculating a phase delay of the oscillating waves of the wheel speed from those of the output current and detects whether or not the wheel speed drops to an extent that the slip ratio exceeds the target slip ratio in use of the calculated phase delay.

7. A vehicle brake apparatus according to claim 2, wherein the oscillation waves of the wheel speed oscillates to keep the slip ratio at a vicinity of the target slip ratio so that an increase of braking force is restricted.

8. A vehicle brake apparatus according to claim 2, wherein the oscillating waves of the output current are formed in sin waves.

9. A vehicle brake apparatus having slip ratio calculation means for calculating a slip ratio based on vehicle body speed and wheel speed in which ABS control is executed to prevent a wheel from locking in such a manner that braking force is controlled so as to keep the slip ratio at a target slip ratio so that an excessive drop of the wheel speed from the vehicle body, speed is adjusted, comprising:

a braking actuator for adjusting braking force applied to a wheel; and

a drive circuit for generating an output current by which the braking actuator is driven,

wherein the output current during ABS control is a current on which oscillating waves are superimposed so that the wheel speed changes to show oscillating waves and

wherein the slip ratio calculation means further detects whether or not the wheel speed drops to an extent that the slip ratio exceeds the target slip ratio in use of an integration value of the slip ratio after starting ABS control.

10. A vehicle brake apparatus having slip ratio calculation means for calculating a slip ratio based on vehicle body speed and wheel speed in which ABS control is executed to prevent a wheel from locking in such a manner that braking force is controlled so as to keep the slip ratio at a target slip ratio so that an excessive drop of the wheel speed from the vehicle body speed is adjusted, comprising:

a braking actuator for adjusting braking force applied to a wheel; and

a drive circuit for generating an output current by which the braking actuator is driven,

wherein the output current during ABS control is a current on which oscillating waves are superimposed so that the wheel speed changes to show oscillating waves, and

wherein the slip ratio calculation means further detects whether or not the wheel speed drops to an extent that the slip ratio exceeds the target slip ratio in use of an integration value of differences between the wheel speed and the vehicle body speed after starting ABS control.

11. A vehicle brake apparatus having slip ratio calculation means for calculating a slip ratio based on vehicle body speed and wheel speed in which ABS control is executed to prevent a wheel from locking in such a manner that braking force is controlled so as to keep the slip ratio at a target slip ratio so that an excessive drop of the wheel speed from the vehicle body speed is adjusted, comprising:

a braking actuator for adjusting braking force applied to a wheel;

a drive circuit for generating an output current by which the braking actuator is driven,

wherein the output current during ABS control is a current on which oscillating waves are superimposed so that the wheel speed changes to show oscillating waves, and

wheel speed variation calculation means for calculating a variation range of the wheel speed and detecting whether the wheel speed drops to an extent that the slip ratio exceeds the target slip ratio in use of the calculated variation range.