Power assist device and brake system

Patent metadata

Field	Value
Publication number	US-9701296-B2
Application number	US-201314442214-A
Country	US
Kind code	B2
Filing date	Nov 11, 2013
Priority date	Nov 12, 2012
Publication date	Jul 11, 2017
Grant date	Jul 11, 2017

Abstract

A booster includes a valve body and a boosting assembly with a ball screw. The ball screw includes a screw rod, a nut, and a plurality of balls cooperating with and between the screw rod and the nut. The nut is linked with the valve body and moves along a straight line on its cooperated screw rod so as to drive the valve body to move along a straight line. A brake system includes the booster and a hydraulic system that includes a braking main cylinder with a piston. The valve body is connected to the piston. The booster is configured to provide high transmission efficiency.

First claim

The invention claimed is:

1. A booster, comprising:
a valve body; and
a boosting assembly comprising a nut and at least two ball screws, each of the at least two ball screws including a respective screw rod and a plurality of balls cooperating with and between the respective screw rod and the nut, wherein
the nut is linked with the valve body and moves along a straight line on the respective screw rods so as to drive the valve body to move along a straight line,
the boosting assembly further comprises a transmission device, and
the transmission device comprises an input rotating shaft that is linked with the respective screw rods and transmits a rotational power of the input rotating shaft to each respective screw rod.

2. The booster according to claim 1 , wherein the boosting assembly further comprises a boosting plate to which the nut is installed in a non-rotatable manner relative thereto, and wherein the boosting assembly drives the valve body through the boosting plate.

3. The booster according to claim 2 , wherein the boosting plate defines a central hole through which the valve body passes, wherein the valve body has a boosting boss, and wherein the nut abuts against the boosting boss via the boosting plate and then drives the valve body.

4. The booster according to claim 1 , further comprising a housing, wherein:
the valve body is configured to move along a longitudinal straight line between a first position and a second position relative to the housing,
when the input rotating shaft rotates in a forward direction, the nut moves along a straight line on the respective screw rods in a forward stroke so that the boosting assembly drives the valve body to move along a straight line towards the first position, and
when input rotating shaft rotates in a reverse direction, the nut moves along a straight line on the respective screw rods in a backward stroke so that the boosting assembly drives the valve body to move along a straight line towards the second position.

5. The booster according to claim 4 , further comprising a first resilient component, wherein:
when the valve body moves towards the first position, the first resilient component is elastically deformed so as to store a potential energy; and
when the first resilient component releases the potential energy, the first resilient component drives the valve body to move towards the second position.

6. The booster according to claim 1 , further comprising a housing, an input component, an actuator, an electronic control unit, and a stroke sensor, wherein:
the valve body is configured to move along a longitudinal straight line between a first position and a second position relative to the housing,
the input component is configured to drive the valve body to move along a straight line towards the first position without the boost from the boosting assembly,
the actuator is configured to output a rotational power to the input rotating shaft,
the stroke sensor detects a displacement of the input component, and
the electronic control unit controls the operation of the actuator according to the displacement of the input component detected by the stroke sensor.

7. The booster according to claim 6 , wherein:
the input component is configured to reciprocate between a rest position and a drive position relative to the valve body;
a second resilient component is disposed between the input component and the valve body;
the input component is held at the rest position by the resilient force of the second resilient component without an external force being applied;
when an external force drives the input component to move towards the drive position, the second resilient component is elastically deformed so as to store a potential energy;
when the input component arrives at the drive position, the input component, under a further action of the external force, drives the valve body to move; and
when the second resilient component releases the potential energy, the second resilient component drives the input component to move towards the rest position.

8. The booster according to claim 6 , wherein the stroke sensor is a magnetic medium sensor.

9. The booster according to claim 1 , further comprising an actuator connected to the input rotating shaft, wherein the actuator is a motor that is configured output a rotational power in a forward direction and in a reverse direction, and wherein the respective screw rods of the at least two ball screws are disposed in an axial symmetrical manner relative to the valve body.

10. The booster according to claim 1 , wherein the transmission device is a gear transmission device that has a plastic gear mounted to a steel shaft.

11. The booster according to claim 1 , wherein a connection structure is disposed between the valve body and the nut, and wherein a part of the connection structure is fixed to the nut and another part of the connection structure is connected to the valve body.

12. A brake system, comprising:
a hydraulic system including a main braking cylinder having a piston; and
a booster including:
a valve body; and
a boosting assembly comprising a nut and at least two ball screws, each of the at least two ball screws including a respective screw rod and a plurality of balls cooperating with and between the screw rod and the nut, wherein
the nut is linked with the valve body and moves along a straight line on the respective screw rods so as to drive the valve body to move along a straight line,
the valve body is connected to the piston,
the boosting assembly further comprises a transmission device, and
the transmission device comprises an input rotating shaft that is linked with the respective screw rods and transmits a rotational power of the input rotating shaft to each respective screw rod.

13. The brake system according to claim 12 , wherein a reacting plate including a resilient material is arranged between the valve body and the piston.

Assignees

• Bosch Gmbh Robert

Inventors

• Zhang Qiusheng

Classifications

• F16H25/2204

  with balls · CPC title

• B60T13/745 Primary

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

• B60T13/02

  with mechanical assistance or drive {(combined with fluid pressure B60T13/588)} · CPC title