Brake booster for a motor vehicle

Patent metadata

Field	Value
Publication number	US-10391995-B2
Application number	US-201615758779-A
Country	US
Kind code	B2
Filing date	Jul 13, 2016
Priority date	Sep 14, 2015
Publication date	Aug 27, 2019
Grant date	Aug 27, 2019

Abstract

A brake booster for a brake master cylinder including a drive motor connected via a linkage to a pressure piston for the brake master cylinder, the linkage having a rotatable spindle nut having an internal thread and a nonrotatable, axially displaceable spindle rod having an external thread, the threads interengaging to convert a rotational motion of the drive motor into a translational motion of the spindle rod in order to displace the pressure piston. The spindle nut has an external tooth set that is in engagement with an internal tooth set of a annular drive gear of the linkage. The spindle nut is axially displaceable with respect to the annular drive gear. Except for a first tooth flank of a tooth, which extends in a first axial portion in its longitudinal extent toward an oppositely located tooth flank, tooth flanks of the internal and external tooth sets extend axially.

First claim

What is claimed is:

1. A brake booster for a brake master cylinder of a motor vehicle, comprising:
a drive motor; and
a linkage, the drive motor connected via the linkage to a pressure piston for the brake master cylinder, the linkage including a rotatable spindle nut having an internal thread, and a nonrotatable, axially displaceable spindle rod having an external thread, the internal thread and the external thread interengaging to convert a rotational motion of the drive motor into a translational motion of the spindle rod to displace the pressure piston;
wherein the spindle nut has an external tooth set in engagement with an internal tooth set of an annular drive gear, disposed coaxially with the spindle nut, of the linkage, the spindle nut is axially displaceable with respect to the annular drive gear, and except for at least one first tooth flank of at least one tooth, which extends in a first axial portion in its longitudinal extent in a direction toward an oppositely located tooth flank, tooth flanks of teeth of the internal tooth set and of the external tooth set extend axially.

2. The brake booster as recited in claim 1 , wherein in the first axial portion the first tooth flank diverges from the axial extent at an angle.

3. The brake booster as recited in claim 1 , wherein a second tooth flank of the at least one tooth extends continuously axially.

4. The brake booster as recited in claim 1 , wherein a first tooth flank of one of all teeth of the internal thread or the external thread diverges, in the first axial portion, from the axial extent at the angle.

5. The brake booster as recited in claim 1 , wherein respectively mutually oppositely located tooth flanks of the interengaging teeth of the external tooth set and internal tooth set are embodied at least substantially in complementary fashion to one another.

6. The brake booster as recited in claim 1 , wherein the external tooth set and the internal tooth set exhibit, between mutually oppositely located tooth flanks, a minimum clearance that enables a rotation of the spindle nut with respect to the annular drive gear.

7. The brake booster as recited in claim 1 , wherein the first axial portion is a terminal portion of one of the external tooth set or of the internal tooth set.

8. The brake booster as recited in claim 1 , wherein the linkage has associated with it at least one spring element that axially forces an axial stop of the spindle nut against the annular drive gear.

9. A braking device for a vehicle, comprising:
a brake pedal mechanically connected to a pressure piston of a brake master cylinder; and
a brake booster, including a drive motor, and a linkage, the drive motor connected via the linkage to the pressure piston for the brake master cylinder, the linkage including a rotatable spindle nut having an internal thread, and a nonrotatable, axially displaceable spindle rod having an external thread, the internal thread and the external thread interengaging to convert a rotational motion of the drive motor into a translational motion of the spindle rod to displace the pressure piston, wherein the spindle nut has an external tooth set in engagement with an internal tooth set of an annular drive gear, disposed coaxially with the spindle nut, of the linkage, the spindle nut is axially displaceable with respect to the annular drive gear, and except for at least one first tooth flank of at least one tooth, which extends in a first axial portion in its longitudinal extent in a direction toward an oppositely located tooth flank, tooth flanks of teeth of the internal tooth set and of the external tooth set extend axially;
wherein the spindle rod of the brake booster is one of operatively connected to, or constitutes, the pressure piston.

10. The brake booster as recited in claim 9 , wherein the spindle nut has associated with it at least one travel sensor that monitors the axial displacement of the spindle nut.

Assignees

• Bosch Gmbh Robert

Inventors

• Ohm Andreas
• Deberling Andreas

Classifications

• F16H25/20

  Screw mechanisms (with automatic reversal F16H25/12) · CPC title

• F16H2025/2081

  Parallel arrangement of drive motor to screw axis · CPC title

• B60T13/745 Primary

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

• B60T13/746

  and mechanical transmission of the braking action · CPC title

• B60T8/4077

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