Brake control device

Patent metadata

Field	Value
Publication number	US-9278676-B2
Application number	US-201013148952-A
Country	US
Kind code	B2
Filing date	Feb 25, 2010
Priority date	Mar 31, 2009
Publication date	Mar 8, 2016
Grant date	Mar 8, 2016

Abstract

According to the present invention, limited electric power is consumed so as to achieve long-lasting use of electric power during brake control with the use of an auxiliary power supply source when there is a malfunction of a vehicle power supply source. In addition, a brake control device for ensuring responsiveness at the beginning of braking or when emergency braking is necessary is provided. The brake control device of the present invention is a brake control device for detecting electric signals generated depending on the degree of brake-pedal operation and calculating the driver's demanded braking force based on the electric signals so as to generate the demanded braking force, which comprises an auxiliary power supply source for supplying electric power to the brake control device when there is a malfunction of a vehicle power supply source and controls braking depending on the charged capacity of the auxiliary power supply source.

First claim

The invention claimed is:

1. A brake control device comprising:
a master cylinder configured to generate hydraulic pressure, the hydraulic pressure generating a braking force;
an electric motor configured to control the hydraulic pressure in the master cylinder;
a control circuit configured to generate a current that drives the electric motor with electric power supplied from a main power supply source; and
an auxiliary power supply source, wherein
the control circuit is configured to calculate a demanded braking force corresponding to an operation amount of a brake pedal,
the current that drives the electric motor is generated on the basis of the calculated demanded braking force,
the electric motor is configured to convert the hydraulic pressure generated in the master cylinder into the demanded braking force,
when there is an abnormality in the main power supply source, the control circuit carries out braking control with electric power supplied from the auxiliary power supply source in the following manner:
the control circuit determines whether or not the brake pedal operation corresponds to emergency braking, and
if the control circuit determines that the brake pedal operation does not correspond to the emergency braking, the current that drives the electric motor is reduced in response to the brake pedal operation carried out under conditions equivalent to the conditions for carrying out braking control with electric power supplied from the main power supply source, and
if the control circuit determines that the brake pedal operation corresponds to the emergency braking, the current that drives the electric motor is substantially maintained at a same level in response to the brake pedal operation carried out under conditions equivalent to the conditions for carrying out braking control with electric power supplied from the main power supply source.

2. A brake control device comprising:
a master cylinder configured to transmit hydraulic pressure, the hydraulic pressure generating a braking force;
an input piston configured to control the hydraulic pressure in the master cylinder through movement by a distance that corresponds to an operation amount of a brake pedal;
an assisting piston configured to control the hydraulic pressure in the master cylinder together with the input piston;
an electric motor configured to move the assisting piston; and
a control circuit configured to control the electric motor based on the operation amount of the brake pedal, the control circuit having electric power terminals to receive electric power from a main power supply source and an auxiliary power supply source, respectively, wherein
the control circuit is configured to control the electric motor based on the operation amount of the brake pedal when the control circuit is operated with electric power from the main power source, provided that a limit is imposed on a current that drives the electric motor when the control circuit is operated with the electric power from the auxiliary power source, and
the control circuit is configured to perform braking control based on the operation amount of the brake pedal in the following manner:
a rate of decline in the current that drives the electric motor, when the operation amount of the brake pedal is low, is made larger than a rate of decline in the current that drives the electric motor when the operation amount of the brake pedal is high, such rate of decline being obtained by comparing the current that drives the electric motor that is operated with the electric power supplied from the auxiliary power supply source with the current that drives the electric motor that is operated with the electric power supplied from the main power supply source.

3. A brake control device comprising:
a master cylinder configured to generate a hydraulic pressure, the hydraulic pressure generating a braking force;
an electric motor configured to control the hydraulic pressure in the master cylinder;
a control circuit configured to generate a current that drives the electric motor with electric power supplied from a main power supply source; and
an auxiliary power supply source, wherein
the control circuit is configured to calculate a demanded braking force corresponding to an operation amount of a brake pedal,
the current that drives the electric motor is generated on the basis of the calculated demanded braking force,
the electric motor is configured to convert the hydraulic pressure generated in the master cylinder into the demanded braking force,
the control circuit generates the current for driving the electric motor on the basis of the demanded braking force calculated based on an operation amount of the brake pedal, and
when there is an abnormality in the main power supply source, if the maximum operation amount of the brake pedal is maintained at a substantially constant level during plural consecutive operations of the brake pedal,
the control circuit generates a current that drives the electric motor with substantially a same current during a first phase corresponding to at least two brake pedal operations of the plural consecutive operations.

4. The brake control device according to claim 3 , wherein the control circuit subsequently reduces the current that drives the electric motor to a lower level than a level of the current for braking control with electric power supplied from the main power supply source during a second phase that begins after the first phase.

Assignees

• Nishino Kimio
• Innami Toshiyuki
• Matsuzaki Norikazu
• Kikawa Masayuki
• Miyajima Ayumu
• Ajima Toshiyuki
• Hitachi Automotive Systems Ltd

Inventors

• Nishino Kimio
• Innami Toshiyuki
• Matsuzaki Norikazu
• Kikawa Masayuki
• Miyajima Ayumu
• Ajima Toshiyuki

Classifications

• B60T8/321

  deceleration (B60T8/34, B60T8/52, B60T8/54, B60T8/56, B60T8/58, B60T8/72, B60T8/86, B60T8/88 take precedence) · CPC title

• B60T8/885

  using electrical circuitry · CPC title

• B60T8/442 Primary

  the booster being a fluid return pump, e.g. in combination with a brake pedal force booster · CPC title

• B60T13/745

  acting on a hydraulic system, e.g. a master cylinder · CPC title

• B60T8/4872

  pump-back systems · CPC title