Brake booster and brake system

Patent metadata

Field	Value
Publication number	US-10556576-B2
Application number	US-201615759748-A
Country	US
Kind code	B2
Filing date	Jul 13, 2016
Priority date	Sep 14, 2015
Publication date	Feb 11, 2020
Grant date	Feb 11, 2020

Abstract

A brake booster for a brake master cylinder of a motor vehicle includes a drive motor that is connected/connectable by a gear unit to a pressure piston for the brake master cylinder, the gear unit converting a rotational motion of the drive motor into a translational motion of the pressure piston to actuate the brake master cylinder, and the gear unit including a rotatable spindle nut and a non-rotatable spindle rod having intermeshing trapezoidal threads that have have a flank clearance and a tip clearance that are greater than a bottom clearance.

First claim

What is claimed is:

1. A brake booster for a brake master cylinder of a motor vehicle, the brake booster comprising:
a drive motor; and
a gear unit that is configured to convert a rotational motion of the drive motor into a translational motion of a pressure piston to actuate the brake master cylinder and that includes:
a rotatable spindle nut including a first trapezoidal thread; and
a non-rotatable spindle rod including a second trapezoidal thread that intermesh with the first trapezoidal thread with a flank clearance and a tip clearance that are greater than a bottom clearance between the first and second threads;

wherein the spindle nut includes an external toothing that engages with an internal toothing of a drive ring gear of the gear unit.

2. The brake booster of claim 1 , wherein the flank clearance is 8-12% of a tooth width of the trapezoidal thread.

3. The brake booster of claim 1 , wherein the flank clearance is 10% of a tooth width of the trapezoidal thread.

4. The brake booster of claim 1 , wherein the tip clearance is 8-12% of a tooth width of the trapezoidal thread.

5. The brake booster of claim 1 , wherein the tip clearance is 10% of a tooth width of the trapezoidal thread.

6. The brake booster of claim 1 , wherein the external toothing and the internal toothing are formed for axial displacement of the spindle nut relative to the drive ring gear.

7. The brake booster of claim 1 , wherein the spindle nut includes an axial stop interacting with the drive ring gear.

8. The brake booster of claim 7 , further comprising a spring that presses the spindle nut with the axial stop against the drive ring gear.

9. A motor vehicle brake system comprising:
a brake pedal that is mechanically connected to a pressure piston of a brake master cylinder; and
a brake booster that includes:
a drive motor; and
a gear unit that is configured to convert a rotational motion of the drive motor into a translational motion of the pressure piston to actuate the brake master cylinder and that includes:
a rotatable spindle nut including a first trapezoidal thread; and
a non-rotatable spindle rod including a second trapezoidal thread that intermesh with the first trapezoidal thread with a flank clearance and a tip clearance that are greater than a bottom clearance between the first and second threads;
wherein the spindle nut includes an external toothing that engages with an internal toothing of a drive ring gear of the gear unit.

10. A brake booster for a brake master cylinder of a motor vehicle, the brake booster comprising:
a drive motor; and
a gear unit that:
includes:
a rotatable spindle nut including a first trapezoidal thread; and
a non-rotatable spindle rod including a second trapezoidal thread that intermesh with the first trapezoidal thread with a flank clearance and a tip clearance that are greater than a bottom clearance between the first and second threads; and

is configured to convert a rotational motion of the drive motor into a translational motion of the spindle rod to actuate the brake master cylinder;
wherein the spindle nut includes an external toothing that engages with an internal toothing of a drive ring gear of the gear unit.

Assignees

• Bosch Gmbh Robert

Inventors

• Ohm Andreas
• Deberling Andreas
• Weissinger Daniel
• Nagel Willi

Classifications

• F16H25/2003

  with arrangements for taking up backlash (F16H25/2209 takes precedence) · CPC title

• F16H25/24

  Elements essential to such mechanisms, e.g. screws, nuts (F16H25/22 takes precedence) · CPC title

• B60T13/745 Primary

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

• B60T13/143

  Master cylinder mechanically coupled with booster · CPC title