Vehicle brake control device for an electrically driven vehicle

Patent metadata

Field	Value
Publication number	US-8998352-B2
Application number	US-201113820114-A
Country	US
Kind code	B2
Filing date	Sep 30, 2011
Priority date	Nov 8, 2010
Publication date	Apr 7, 2015
Grant date	Apr 7, 2015

Abstract

A vehicle brake control device includes a master cylinder, a plurality of wheel cylinders, a VDC brake hydraulic pressure unit, a motor controller and an integration controller. When a brake operation is carried out, the integration controller carries out a regenerative brake control which achieves a target deceleration. Additionally, a motor suspension control is carried out which suspends a drive status of the VDC motor when the vehicle velocity is less than a first prescribed value. Furthermore, when the vehicle velocity exceeds a second prescribed value and the brake operation is carried out while the VDC motor is in the suspended status, the value of the target deceleration is set to a lower value than the value of the target deceleration which the driver requests, and a motor reactivation control is carried out which reactivates the VDC motor.

First claim

The invention claimed is:

1. A vehicle brake control device for an electrically driven vehicle, comprising:
a master cylinder that generates a master cylinder pressure in accordance with a braking operation;
a front wheel cylinder disposed at a front wheel to supply a hydraulic pressure braking power to the front wheel;
a rear wheel cylinder disposed at a rear wheel to supply a hydraulic pressure braking power to the rear wheel;
a brake hydraulic pressure actuator interposed between the master cylinder and the front and rear wheel cylinders, and the brake hydraulic pressure actuator including a hydraulic pressure pump driven by a pumping motor and a differential valve for controlling the pressure difference between a wheel cylinder pressure of the front and rear wheel cylinders and the master cylinder pressure during operation of the pumping motor;
a regenerative brake force control unit connected to an electric drive motor that is coupled to a drive wheel that is one of the front and rear wheels, the regenerative brake force control unit controlling a regenerative brake force that is generated by the electric drive motor; and
a regenerative cooperative brake control unit that calculates a target deceleration of a driver's request and outputs a regenerative braking command to the regenerative brake force control unit and a fluid pressure command to a brake control unit of the brake hydraulic pressure actuator to achieve the target deceleration during the braking operation, the regenerative cooperative brake control unit calculating a sum of a base hydraulic deceleration portion derived from of the master cylinder pressure and a deceleration portion derived from the regenerative brake force, and further compensating for a shortage of the regenerative deceleration portion in the sum to achieve the target deceleration by an add-on deceleration portion generated by the brake hydraulic pressure actuator,
the regenerative cooperative brake control unit stopping the pumping motor from operating upon determining the vehicle speed has fallen below a first predetermined vehicle speed value,
the regenerative cooperative brake control unit setting a target deceleration value that is lower than the target deceleration and restarting the pumping motor upon determining the vehicle speed exceeding a second predetermined vehicle speed value and the braking operation is occurring while the pumping motor is in a stopped state as a result of the vehicle speed falling below the first predetermined vehicle speed value.

2. The vehicle brake control device as claimed in claim 1 , wherein
the regenerative cooperative brake control unit sets the target deceleration value by subtracting from the target deceleration at the vehicle speed exceeding the first predetermined vehicle speed value at least a portion corresponding to an overshoot of an actual deceleration caused by an excessive rotation of the pumping motor.

3. The vehicle brake control device as claimed in claim 1 , wherein
the regenerative cooperative brake control unit determines the target deceleration value that is lower than the target deceleration based on a brake pedal operation amount during the braking operation using a first target deceleration calculation map, where the first target deceleration calculation map is defined by the target deceleration value in the first target deceleration calculation map being smaller for values of the brake pedal operation amount that are less than a predetermined value than in a second target deceleration map that is used while the vehicle speed is equal to or greater than the first predetermined vehicle speed.

4. The vehicle brake control device as claimed in claim 2 , wherein
the regenerative cooperative brake control unit determines the target deceleration value that is lower than the target deceleration based on a brake pedal operation amount during the braking operation using a first target deceleration calculation map, where the first target deceleration calculation map is defined by the target deceleration value in the first target deceleration calculation map being smaller for values of the brake pedal operation amount that are less than a predetermined value than in a second target deceleration map that is used while the vehicle speed is equal to or greater than the first predetermined vehicle speed.

Assignees

• Imamura Masayuki
• Nissan Motor

Inventors

• Imamura Masayuki

Classifications

• B60T13/586

  the retarders being of the electric type · CPC title

• B60T8/4872

  pump-back systems · CPC title

• B60T8/4045

  involving ON/OFF switching · CPC title

• B60T8/17 Primary

  Using electrical or electronic regulation means to control braking {(detecting or indicating faulty operation B60T8/885)} · CPC title

• B60W10/08

  including control of electric propulsion units, e.g. motors or generators · CPC title