Brake booster and method for operating a brake booster

Patent metadata

Field	Value
Publication number	US-9868428-B2
Application number	US-201113880816-A
Country	US
Kind code	B2
Filing date	Sep 5, 2011
Priority date	Nov 2, 2010
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

Abstract

A brake booster includes an input element actuatable by a driver, an actuator for generating a support force, an output element that receives at least one of an input or support force and that applies an actuating force to a piston of a brake master cylinder, a force transmission unit having elastic properties and transmitting the input and/or support forces to the output element, and a preload unit acting on the force transmission unit to apply a force couple to the force transmission unit when the brake booster is in idle mode. A method for operating the brake booster includes generating a support force prior to a braking intent to be anticipated or immediately after detection of a braking intent, in a time span before or immediately after detection of an actuation of the input element.

First claim

What is claimed is:

1. A brake booster, comprising:
an input element which is actuatable by a driver,
an actuator for generating a support force,
an output element, to which an input force or the support force may be applied by the input element and/or the actuator and through which an actuating force may be applied to a piston of a brake master cylinder,
a force transmission unit having elastic properties, which is situated between the input element and the actuator on one end and the output element on an other end and which transmits the input force and/or the support force to the output element, and
a preload unit, which acts upon the force transmission unit such that a first part of a force couple is applied to a first side of the force transmission unit and a second part of the force couple is applied to a second side of the force transmission unit when the brake booster is in idle mode,
wherein between the input element and the force transmission unit or between a first and a second subcomponent of the input element an air gap is provided, wherein the air gap must be overridden before the input element applies the input force to the force transmission unit,
wherein at least one of: (i) the preload unit applies the first part of the force couple directly onto the first side of the force transmission unit, and (ii) the preload unit applies the second part of the force couple directly onto the second side of the force transmission unit.

2. The brake booster as recited in claim 1 , wherein the actuator is configured as a pneumatic, a hydraulic, an electrohydraulic, an electromechanical or an electrothermal actuator.

3. The brake booster as recited in claim 1 , wherein the force transmission unit is configured such that a deviation of a ratio of the support force to the input force from a predefined ratio causes a deflection of the force transmission unit.

4. The brake booster as recited in claim 3 , wherein the force transmission unit is configured as an elastically deformable reaction disk or an elastic spring construction.

5. The brake booster as recited in claim 1 , wherein the preload unit has a force generation unit, which applies the first part of the force couple to the force transmission unit in the idle mode.

6. The brake booster as recited in claim 5 , wherein the force generation unit is configured as a spring element which is preloaded when the brake booster is in the idle mode and which rests on the first side on the force transmission unit.

7. The brake booster as recited in claim 6 , wherein a return spring of the brake booster acts as the spring element.

8. The brake booster as recited in claim 6 , wherein a spring of the brake master cylinder acts as the spring element.

9. The brake booster as recited in claim 5 , wherein the preload unit includes a reaction unit which generates the second part of the force couple as a reaction force to the first part of the force couple.

10. The brake booster as recited in claim 9 , wherein the reaction unit includes a stop, on which the second side of the force transmission unit at least one of directly or indirectly rests.

11. The brake booster as recited in claim 10 , wherein the first subcomponent is actuatable by the driver, for generating the input force and the second subcomponent is configured for transmitting the input force to the force transmission unit and the stop is situated such that in the idle mode of the brake booster a side of the second subcomponent of the input element which faces away from the force transmission unit rests on the stop.

12. The brake booster as recited in claim 10 , wherein the input element is situated movably in a tube while the brake booster is in idle mode, and wherein the brake booster is in contact with the force transmission unit and rests with a side of the brake booster facing away from the force transmission unit on the stop.

13. The brake booster as recited in claim 1 , wherein the air gap in the idle mode is smaller or larger than a desired air gap at a beginning of a braking operation.

14. The brake booster as recited in claim 1 , wherein the stop is situated in an area between the force transmission unit and the input element.

15. The brake booster as recited in claim 1 , wherein the air gap is adjustable so that a size of the air gap represents a force at which the brake booster transfers from a non-muscular energy mode to an energy-assisted mode.

16. A method for operating a brake booster, the method comprising:
selectively activating, at an end of a first side of a force transmission unit having elastic properties, a support force generated by an actuator;
receiving, at an other end of the first side of the force transmission unit, an input force from an input element actuated by a driver;
applying to an output element, by a second side that is opposite to the first side of the force transmission unit, an actuating force that further is applied via the output element to a piston of a brake master cylinder;
when the brake booster is in an idle mode, engaging the force transmission unit, by a preload unit, with a force couple having a first part of the force couple engaging the first side of the force transmission unit and a second part of the force couple engaging the second side of the force transmission unit; and
when a braking intent is at least one of:
(i) anticipated, activating the support force immediately after anticipation of the braking intent, in a time span before detection of an actuation of the input element, and
(ii) detected, activating the support force immediately after detection of the braking intent, in a time span immediately after detection of the actuation of the input element,

wherein between the input element and the force transmission unit or between a first and a second subcomponent of the input element an air gap is provided, wherein the air gap must be overridden before the input element applies the input force to the force transmission unit,
wherein at least one of: (i) the preload unit engages the first part of the force couple directly with the first side of the force transmission unit, and (ii) the preload unit engages the second part of the force couple directly with the second side of the force transmission unit.

17. The method as recited in claim 16 , further comprising:
calculating a ratio of the support force to the input force by:
measuring a first distance between a point of contact of the output element on the force transmission unit to a point of contact of the support force on the force transmission unit,
measuring a second distance between a point of contact of the output element on the force transmission unit to a point of contact of the input element on the force transmission unit, and
dividing the measured first distance by the measured second distance; determining a deviation between the calculated ratio and a predefined ratio; and determining, based on the deviation, the deflection of the force transmission unit.

18. The method as recited in claim 16 , wherein the first part of the force couple is actively applied by the preload unit.

19. The method as recited in claim 17 , wherein the preload unit shifts based on the determined deflection.

Assignees

• Mahnkopf Dirk
• Bosch Gmbh Robert

Inventors

• Mahnkopf Dirk

Classifications

• B60T7/042 Primary

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

• B60T2201/12

  Pre-actuation of braking systems without significant braking effect; Optimizing brake performance by reduction of play between brake pads and brake disc · CPC title

• B60T17/22

  Devices for monitoring or checking brake systems; Signal devices · CPC title

• B60T13/52 Primary

  indirect, i.e. vacuum booster units · CPC title

• B60T13/662

  characterised by specified functions of the control system components · CPC title