Electric parking brake device

Patent metadata

Field	Value
Publication number	US-12286089-B2
Application number	US-202017910635-A
Country	US
Kind code	B2
Filing date	Dec 18, 2020
Priority date	Mar 12, 2020
Publication date	Apr 29, 2025
Grant date	Apr 29, 2025

Abstract

Provided is an electric parking brake device in which a drum brake includes braking gap automatic adjustment means and a parking brake lever, and the operation of an electric actuator that drives the parking brake lever is controlled by a control unit. When an application operation time of the electric actuator ( 38 ) by the time when a parking brake state is obtained has exceeded a predetermined application operation end determination time (T 2 ), the control unit (C) determines that the braking gap automatic adjustment means ( 18 ) is abnormal. With this configuration, at the time of obtaining the parking brake state, the presence or absence of abnormality in the braking gap automatic adjustment means can be determined.

First claim

The invention claimed is:

1. An electric parking brake device, comprising:
a drum brake including:
braking gap automatic adjuster for automatically adjusting a gap between a pair of brake shoes and a brake drum; and
a parking brake lever configured to operate between an operation position for obtaining a parking brake state by bringing the pair of brake shoes into slide contact with the brake drum and a non-operation position for releasing the parking brake state;

an electric actuator configured to exert power for driving the parking brake lever; and
a control unit configured to control the operation of the electric actuator,
wherein, when an application operation time of the electric actuator by a time when the parking brake state is obtained has exceeded a predetermined application operation end determination time, the control unit determines that the braking gap automatic adjuster is abnormal.

2. The electric parking brake device according to claim 1 , further comprising current detector for detecting an energization current to the electric actuator,
wherein, when a detection value by the current detector of an inrush current generated in response to the start of the operation of the electric actuator has exceeded a predetermined current threshold, the control unit performs abnormality determination of the braking gap automatic adjuster.

3. The electric parking brake device according to claim 2 , wherein, when the detection value by the current detector of the inrush current is equal to or less than the current threshold, and the control unit determines that the application operation time from a start of an application operation of the electric actuator has exceeded a predetermined inrush current abnormality determination time, the control unit initializes the abnormality determination of the braking gap automatic adjuster.

Assignees

• Hitachi Astemo Ltd
• Hitachi Astemo Ueda Ltd

Inventors

• PURANE Sandip
• Yamamoto Yasuhiro
• Takahashi Mari

Classifications

• F16D2121/24

  using motors · CPC title

• F16D2066/003

  Position, angle or speed · CPC title

• F16D66/00

  Arrangements for monitoring working conditions, e.g. wear, temperature · CPC title

• F16D65/52

  self-acting in one direction for adjusting excessive play · CPC title

• F16D65/22

  adapted for pressing members apart {, e.g. for drum brakes} · CPC title