Coordinated brake control system

• US 7,136,737 B2
• Filed: 12/11/2003
• Issued: 11/14/2006
• Est. Priority Date: 12/17/2002
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Nakamura, Hideo, Ashizawa, Hiroyuki, Tazoe, Kazuhiko
• Primary Examiner(s): Jeanglaude, Gertrude A.
• Application Number:
  US10/732,310
• Publication Number:
  US 20040122579A1
• Time in Patent Office: 1,069 Days
• Field of Search: 701/1, 701/22, 701 70- 71, 701 78- 79, 701/81, 701/83, 303 2- 3, 303/13, 303 15- 16, 303/20, 303151-152, 303154-155, 303/114.1, 303/115.2, 903/947, 903/920, 903/922
• US Class Current: 701/70
• CPC Class Codes: B60K 6/44 Series-parallel type
• CPC Class Codes: B60L 2210/20 AC to AC converters
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 7/22 Dynamic electric resistor braking, combined with dynamic electric regenerative braking
• CPC Class Codes: B60L 7/26 Controlling the braking effect
• CPC Class Codes: B60T 8/4081 Systems with stroke simulating devices for driver input B60T8/4077 takes precedence
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/18 including control of braking systems
• CPC Class Codes: B60W 10/184 with wheel brakes
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/13 in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 2710/18 Braking system
• CPC Class Codes: G07C 5/08 Registering or indicating performance data other than driving, working, idle, or waiting time, with or without registering driving, working, idle or waiting time
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility
• CPC Class Codes: Y10S 903/947 Characterized by control of braking, e.g. blending of regeneration, friction braking

Abstract

A coordinated brake control system is for a hybrid brake system including a regenerative brake unit and a friction brake unit for a vehicle and is arranged to generate a total braking torque which is a combination of a regenerative braking torque generated by the regenerative brake unit and a friction braking torque generated by the friction brake unit, so as to bring the total braking-torque closer to a target braking torque, and to limit a rate of change of the regenerative braking torque according to a response delay of the friction braking torque when a first distribution ratio of the generative braking torque relative to the total braking torque is decreased and when a second distribution ratio of the friction braking torque relative to the total braking torque is increased.

Claims

1. A coordinated brake control system for a hybrid brake system including a regenerative brake unit and a friction brake unit for a vehicle, the coordinated braking control system comprising:

a controller arranged,

to generate a total braking torque which is a combination of a regenerative braking torque generated by the regenerative brake unit and a friction braking torque generated by the friction brake unit, so as to bring the total braking-torque closer to a target braking torque,and

to limit a rate of change of the regenerative braking torque according to a response delay of the friction braking torque when a first distribution ratio of the generative braking torque relative to the total braking torque is decreased and when a second distribution ratio of the friction braking torque relative to the total braking torque is increased.

2. The coordinated brake control system as claimed in claim 1, wherein the controller is further arranged to obtain the regenerative braking torque by multiplying an allowable maximum regenerative braking-torque and a regenerative braking torque limit coefficient (Kv) which monotonically decreases from 1 to 0 as a vehicle speed is decreased from a limit start speed to a limit finish speed lower than the limit start speed, when the rate of change of the regenerative braking torque is limited.

3. The coordinated brake control system as claimed in claim 2, wherein the regenerative braking-torque limit coefficient Kv is defined according to vehicle speed VSP relative to a limit start speed Vlmth and a limit finish speed Vlmtl as follows.

When VSP≧

Vlmth, Kv=1.

When Vlmtl≦

VSP<

Vlmth,

Kv={VSP/(Vlmth−

Vlmtl)}−

{Vlmtl/(Vlmth−

Vlmtl)}.

When VSP≦

Vlmtl, Kv=0.

4. The coordinated brake control system as claimed in claim 1, wherein the controller is further arranged to obtain the regenerative braking torque by multiplying an allowable maximum regenerative braking-torque and a regenerative braking-torque limit coefficient which monotonically decreases from 1 to 0 as a vehicle speed is decreased from a limit start speed to a limit finish speed lower than the limit start speed, when the vehicle speed is within a range from the limit start speed to a limit middle speed between the limit start speed and the limit finish speed, and to obtain the regenerative braking torque by multiplying the allowable maximum regenerative braking-torque taken at the limit middle speed and the regenerative braking torque limit coefficient, when the vehicle speed is within a range from the limit middle speed to the limit finish speed.

5. The coordinated brake control system as claimed in claim 1, wherein the regenerative braking torque varies to form a quadric curve from an allowable maximum regenerative braking-toque taken at a limit start speed toward zero, when the rate of change of the first regenerative braking torque is limited.

6. The coordinated brake control system as claimed in claim 1, wherein the controller is further arranged to calculate the target braking torque based on a braking intent.

7. A coordinated brake control system for a vehicle comprising:

a vehicle braking detector detecting a braking intent of a driver;

a regenerative brake unit that generates a regenerative braking torque;

a friction braking unit that generates a friction braking torque; and

a controller connected to the vehicle braking detector, the regenerative braking unit and the friction brake unit, the controller being arranged,

to determine a target braking torque according to the braking intent,

to calculate first and second distribution ratios which represents distribution ratios of the total braking torque to the regenerative brake unit and the friction brake unit, respectively,

to generate a total braking torque by dividedly producing the regenerative braking torque and the friction braking torque generated by the friction brake unit on the basis of the first and second distribution ratios, so as to bring the total braking torque closer to the target braking torque, and

to limit a rate of change of the regenerative braking torque according to a generation delay characteristic of the friction braking torque during a period when the first distribution ratio is decreased and the second distribution ratio is increased.

8. A method of controlling a hybrid brake system including a regenerative brake unit and a friction brake unit for a vehicle, the method comprising:

generating a total braking torque which is a combination of a regenerative braking torque generated by the regenerative brake unit and a friction braking torque generated by the friction brake unit, so as to bring the total braking-torque closer to a target braking torque; and

limiting a rate of change of the regenerative braking torque according to a response delay of the friction braking torque when a first distribution ratio of the generative braking torque relative to the total braking torque is decreased and when a second distribution ratio of the friction braking torque relative to the total braking torque is increased.