Booster, resistance force applying apparatus, and stroke simulator

Patent metadata

Field	Value
Publication number	US-2016016569-A1
Application number	US-201514797657-A
Country	US
Kind code	A1
Filing date	Jul 13, 2015
Priority date	Jul 16, 2014
Publication date	Jan 21, 2016
Grant date	—

Abstract

The present invention controls an electric motor according to a stroke that an input rod performs in response to an operation performed on a brake pedal, and thrusts a primary piston, thereby generating a brake hydraulic pressure in a master cylinder. The brake hydraulic pressure is fed back to the input rod via an input piston and an input plunger. The present invention applies a sliding resistance against the stroke of the input rod by pressing a frictional member of a resistance force applying mechanism against a tapering sliding portion of the input rod with the aid of a spring force of a spring member. A taper angle of the sliding portion allows the sliding resistance to change at a varying ratio according to a position of the input rod, which can lead to stable application of a desired sliding resistance.

First claim

What is claimed is:

1 . A booster comprising:
a housing; an input, member disposed movably in a housing, and coupled to a brake pedal; an electric motor configured to be actuated in response to an operation performed on the brake pedal; an assist mechanism configured to thrust a piston in a master cylinder by the actuation of the electric motor; and a resistance force applying mechanism, configured to apply a resistance force against a displacement of the input member relative to the housing, wherein the resistance force applying mechanism includes a sliding portion having an inclination formed at the input member, and a sliding member configured to apply a sliding resistance against the displacement of the input member by slidably contacting the sliding portion, the resistance force applying mechanism being configured in such a manner that the sliding resistance changes at a varying ratio according to a position of the input member relative to the housing.

2 . The booster according to claim 1 , wherein the resistance force applying mechanism is configured in such a manner that the sliding resistance increases until the input member reaches a predetermined position, and increases at a higher ratio after the input member reaches the predetermined position, as the input member is displaced in response to pressing of the brake pedal.

3 . The booster according to claim 1 , wherein the resistance force applying mechanism is configured in such a manner that the sliding resistance increases until the input member reaches a predetermined position, and increases at a lower ratio after the input member reaches the predetermined position, as the input member is displaced in response to pressing of the brake pedal.

4 . The booster according to claim 1 , wherein the resistance force applying mechanism is configured in such a manner that the sliding resistance is maintained constant until the input member reaches a predetermined position, and increases after the input member reaches the predetermined position, as the input member is displaced in response to pressing of the brake pedal.

5 . The booster according to claim 1 , wherein the resistance force applying mechanism, includes a spring member configured to urge the sliding member toward the sliding portion of the input member, the spring member having a spring coefficient varying according to a position of the sliding member being displaced forward and rearward relative to the sliding portion along the inclination.

6 . A stroke simulator configured to apply a reaction force against a displacement of an input member coupled to a brake pedal, the stroke simulator comprising:
a sliding member configured to apply a sliding resistance against the displacement of the input member; and a sliding portion provided at a member in which the input member is inserted, and configured to slidably contact the sliding member, wherein at least one of the input member and the sliding portion is provided with an inclination extending along a direction in which the input member is displaced, thereby causing the sliding resistance to change at a varying ratio according to a position of the input member.

7 . The stroke simulator according to claim 6 , wherein the inclination is shaped in such a manner that the sliding resistance increases until the input member reaches a predetermined position, and increases at a higher ratio after the input member reaches the predetermined position, as the input member is displaced in response to pressing of the brake pedal.

8 . The stroke simulator according to claim 6 , further comprising a spring member configured to apply a spring force against the displacement of the input member, the spring member having a spring constant varying according to a position of the sliding member.

9 . A resistance force applying apparatus configured to apply a resistance force against a stroke of a rotatably supported brake pedal, the resistance force applying apparatus comprising:
a rotational member coupled to a rotational shaft of the brake pedal; and a sliding member configured to apply a sliding resistance against a rotation of the rotational member by slidably contacting the rotational member, wherein at least one of the sliding member, and a sliding portion of the rotational member, which the sliding member slidably contacts, has an inclination to cause the sliding resistance to change at a varying ratio according to a rotational position of the rotational member.

10 . The resistance force applying apparatus according to claim 9 , wherein the inclination is formed in such a manner that the sliding resistance increases until the rotational member reaches a predetermined rotational position, and increases at a higher ratio after the rotational member reaches the predetermined rotational position, as the rotational member rotates in response to pressing of the brake pedal.

11 . The resistance force applying apparatus according to claim 9 , wherein the inclination causes the sliding member to be axially displaced as the rotational member rotates, and
wherein a spring member is provided, the spring member being configured to press the sliding member against the sliding portion of the rotational member, the spring member having a spring constant varying according to a position of the sliding member.

Assignees

• Hitachi Automotive Systems Ltd

Inventors

• Odaira Atsushi
• Usui Takuya

Classifications

• B60T8/4086

  the stroke simulating device being connected to, or integrated in the driver input device · CPC title

• B60T7/042

  by electrical means, e.g. using travel or force sensors · CPC title

• B60T8/4077 Primary

  Systems in which the booster is used as an auxiliary pressure source · CPC title

• B60T13/745 Primary

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

• B60T7/04

  foot actuated · CPC title