Electric motor-driven booster

Patent metadata

Field	Value
Publication number	US-9568026-B2
Application number	US-201113825910-A
Country	US
Kind code	B2
Filing date	Oct 24, 2011
Priority date	Nov 1, 2010
Publication date	Feb 14, 2017
Grant date	Feb 14, 2017

Abstract

In an electric motor-driven booster, a sharp change of reaction force to an operation of a brake pedal is reduced to improve the brake pedal operation feeling. Operation of the brake pedal causes an input rod ( 34 ) and an input piston ( 32 ) to advance, and an electric motor ( 40 ) is driven according to the movement of the input piston to propel a primary piston ( 10 ) through a ball-screw mechanism, thereby generating a desired brake hydraulic pressure in a master cylinder. At this time, the input piston receives the hydraulic pressure in the master cylinder to feed back a part of reaction force during braking to the brake pedal. When the brake pedal is further depressed after the output of the electric motor has reached a maximum output and the primary piston 10 has stopped, a lock nut abuts against a movable spring retainer and compresses a reaction force spring.

First claim

The invention claimed is:

1. An electric motor-driven booster comprising
an input member movable to advance and retract in response to an operation of a brake pedal;
a boosting member provided to be movable relative to the input member, the input member being abuttable against the boosting member when the input member advances;
an electric motor-driven actuator adapted to drive the boosting member, an operation of the electric motor-driven actuator being controlled based on movement of the input member so as to adjust relative positions of the input member and the boosting member to generate a brake hydraulic pressure in a master cylinder with a desired boost ratio;
a spring device disposed between the boosting member and the input member and configured to bias the input member against the booster relatively in a rearward direction;
a movable spring retainer that is disposed closer to the brake pedal than the spring device and is configured to abut against the input member when the input member advances to near where an output of the electric motor-driven actuator reaches a predetermined maximum output; and
a reaction force spring configured to bias the input member through the movable spring retainer toward the brake pedal with the input member and the movable spring retainer contacting each other.

2. The electric motor-driven booster of claim 1 , wherein, when the input member advances to near where an output of the electric motor-driven actuator reaches a predetermined maximum output as a result of advancement of the input member, the reaction force spring applies, to the advancement of the input member, a reaction force only sufficient to compensate for a reduction in a rate of increase in reaction force to the input member due to a fact that the electric motor-driven actuator has reached the maximum output and is unable to further increase the output.

3. The electric motor-driven booster of claim 2 , further comprising:
a fixed spring retainer secured to a housing which accommodates the input member, the boosting member and the electric motor-driven actuator, the reaction force spring being interposed between the fixed spring retainer and the movable spring retainer; and
a cover member secured to the housing to cover the reaction force spring and configured to guide the movable spring retainer along a direction of movement of the input member.

4. The electric motor-driven booster of claim 3 , wherein the cover member supports the movable spring retainer in a direction perpendicular to the direction of movement of the input member.

5. The electric motor-driven booster of claim 3 , wherein the input member has a clevis for connecting the input member to the brake pedal, the clevis being attached to the input member by using a lock nut, so that the input member abuts against the movable spring retainer through the lock nut.

6. The electric motor-driven booster of claim 2 , further comprising:
a fixed spring retainer secured to a housing which accommodates the input member, the boosting member and the electric motor-driven actuator,
wherein the reaction force spring is interposed between the fixed spring retainer and the movable spring retainer; and
a guide member secured to the housing and extended in a direction of movement of the input member to secure the fixed spring retainer to the housing and configured to guide the movable spring retainer along the direction of movement of the input member.

7. The electric motor-driven booster of claim 1 , further comprising a fixed spring retainer secured to a housing which accommodates the input member, the boosting member and the electric motor-driven actuator,
the reaction force spring being interposed between the fixed spring retainer and the movable spring retainer; and
a cover member secured to the housing to cover the reaction force spring and configured to guide the movable spring retainer along a direction of movement of the input member.

8. The electric motor-driven booster of claim 7 , wherein the cover member supports the movable spring retainer in a direction perpendicular to the direction of movement of the input member.

9. The electric motor-driven booster of claim 7 , wherein the input member has a clevis for connecting the input member to the brake pedal, the clevis being attached to the input member by using a lock nut, so that the input member abuts against the movable spring retainer through the lock nut.

10. The electric motor-driven booster of claim 1 , further comprising:
a fixed spring retainer secured to a housing which accommodates the input member, the boosting member and the electric motor-driven actuator,
the reaction force spring being interposed between the fixed spring retainer and the movable spring retainer; and
a guide member secured to the housing and extended in a direction of movement of the input member to secure the fixed spring retainer to the housing and configured to guide the movable spring retainer along the direction of movement of the input member.

11. The electric motor-driven booster of claim 1 , wherein the input member has a clevis for connecting the input member to the brake pedal, the clevis being attached to the input member by using a lock nut, so that the input member abuts against the movable spring retainer through the lock nut.

Assignees

• Yoshimoto Masayuki
• Ikeuchi Ryozo
• Sekiya Ryo
• Ishii Hideaki
• Sano Kazumoto
• Shigeta Hiroshi
• Shirakawa Naoki
• Yagi Ryoichi
• Abe Masami
• Nissan Motor
• Hitachi Automotive Systems Ltd

Inventors

• Yoshimoto Masayuki
• Ikeuchi Ryozo
• Sekiya Ryo
• Ishii Hideaki
• Sano Kazumoto
• Shigeta Hiroshi
• Shirakawa Naoki
• Yagi Ryoichi
• Abe Masami

Classifications

• B60T13/745 Primary

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

• F15B15/08 Primary

  Characterised by the construction of the motor unit · CPC title