Electric brake system for vehicle

Patent metadata

Field	Value
Publication number	US-9108611-B2
Application number	US-201314068491-A
Country	US
Kind code	B2
Filing date	Oct 31, 2013
Priority date	Oct 31, 2012
Publication date	Aug 18, 2015
Grant date	Aug 18, 2015

Abstract

Disclosed herein is an electric brake system for a vehicle including a reservoir, an input rod, and a pedal displacement sensor to sense a displacement of a brake pedal. The electric brake system includes a pressure supply unit connected to the reservoir and a hydraulic channel and to output an electrical signal through the pedal displacement sensor, a hydraulic control unit provided with a first circuit and a second circuit, a shut-off valve to control the hydraulic pressure transferred to a wheel cylinder, a switching valve connected to a channel connecting the pressure supply unit to the hydraulic control unit, a compliance unit installed in a channel connected to the shut-off valve and the switching valve and including a compliance chamber, a piston and an elastic member, a simulator connected to the master cylinder to provide reaction force, and an electronic control unit to control the motor and the valves.

First claim

What is claimed is:

1. An electric brake system for a vehicle, the electric brake system comprising:
a reservoir configured to store oil,
a master cylinder provided with two hydraulic circuits and configured to generate a first hydraulic pressure using the oil stored in the reservoir,
an input rod disposed to contact the master cylinder and configured to move forward according to foot force applied from a driver to a brake pedal,
a pedal displacement sensor configured to sense a displacement of the brake pedal connected to the input rod,
a pressure supply unit connected to the reservoir via a hydraulic channel, and configured to
receive the oil from the reservoir, and
supply a second hydraulic pressure;

a hydraulic control unit comprising:
a first circuit connected to at least one first wheel of the vehicle; and
a second circuit connected to at least one second wheel of the vehicle
wherein the first and second circuits are configured to perform braking of one or more of the first and second wheels with the first and second hydraulic pressures supplied by the master cylinder and the pressure supply unit;

a pressure supply channel connected to the pressure supply unit at one end, and connected to first and second inflow channels at the other end;
the first inflow channel connecting the pressure supply unit to the first circuit via the pressure supply channel;
the second inflow channel connecting the pressure supply unit to the second circuit via the pressure supply channel;
a shut-off valve configured to control the first hydraulic pressure transferred from the master cylinder to a wheel cylinder installed at each wheel;
switching valves connected to the first and second inflow channels and configured to control the second hydraulic pressure;
compliance units installed in the first and second inflow channels and connected to the shut-off valve and the switching valves, each of the compliance units comprising:
a compliance chamber having a predetermined volume varying according to change in pressure, and
a piston and an elastic member arranged in the compliance chamber;

a simulator connected to the master cylinder and configured to provide reaction force according to the foot force applied to the brake pedal; and
an electronic control unit configured to control a motor and the valves based on information about pressure and pedal displacement,
wherein the electronic control unit is configured to operate the motor when the driver operates the brake pedal such that rotational motion of the motor is converted into rectilinear motion,
wherein each of the compliance units further comprises a compliance valve arranged at an inlet of the compliance chamber,
wherein the pressure supply unit comprises:
a pressure chamber connected to the hydraulic channel, and configured to receive oil supplied thereto from the reservoir;
a hydraulic piston arranged in the pressure chamber;
a hydraulic spring arranged in the pressure chamber, and configured to elastically support the hydraulic piston;
the motor configured to generate the rotational motion according to an electrical signal from the pedal displacement sensor; and
a ball-screw member comprising a screw and a nut, and configured to convert the generated rotational motion of the motor into the rectilinear motion,

wherein the hydraulic piston is connected to the screw, and the screw is configured to rectilinearly move such that the oil in the pressure chamber is pressurized by the hydraulic piston, and
wherein the electronic control unit is configured to control the compliance valve of each of the compliance units while oil of the reservoir is suctioned into the pressure chamber, thereby supplying a hydraulic pressure of the compliance units to the wheel cylinder.

2. The electric brake system according to claim 1 , wherein the compliance valve is a Normally Closed solenoid valve that remains closed in a normal state and is opened upon receiving a signal for an opening operation from the electronic control unit.

3. The electric brake system according to claim 1 , further comprising:
a check valve installed in the hydraulic channel, and configured to
prevent backflow of pressure from the pressure chamber, and
allow the oil to be suctioned into and stored in the pressure chamber when the hydraulic piston returns.

4. The electric brake system according to claim 1 ,
wherein the switching valves comprise:
a first switching valve installed in the first inflow channel, and configured to control the second hydraulic pressure in the first inflow channel; and
a second switching valve installed in the second inflow channel, and configured to control the second hydraulic pressure in the second inflow channel.

5. The electric brake system according to claim 4 , further comprising:
check valves installed in parallel with the first and second switching valves.

6. The electric brake system according to claim 4 , wherein the first and second switching valves are Normally Closed solenoid valves that remain closed in a normal state and are opened upon receiving a signal for an opening operation from the electronic control unit.

7. The electric brake system according to claim 1 , wherein the hydraulic control unit further comprises:
a Normally Opened solenoid valve disposed upstream of the wheel cylinder, and configured to control transfer of the first and second hydraulic pressures to the wheel cylinder;
a Normally Closed solenoid valve disposed downstream of the wheel cylinder, and configured to control release of the first and second hydraulic pressures from the wheel cylinder; and
a return channel connecting the Normally Closed solenoid valve to the hydraulic channel.

8. The electric brake system according to claim 1 , further comprising:
first and second backup channels connecting the two hydraulic circuits of the master cylinder to the wheel cylinder for controlling the oil to be supplied to the first and second circuits, when the electric brake system malfunctions,
wherein the shut-off valve comprises:
a first shut-off valve installed in the first backup channel, and configured to control connection between the first backup channel and the master cylinder, and
a second shut-off valve installed in the second backup channel, and configured to control connection between the second backup channel and the master cylinder.

9. The electric brake system according to claim 8 , wherein the first and second shut-off valves are Normally Opened solenoid valves that remain opened in a normal state and are closed upon receiving a signal for a closing operation from the electronic control unit.

10. The electric brake system according to claim 1 , wherein the simulator comprises:
a simulation chamber configured to store the oil discharged from the master cylinder;
a reaction piston arranged in the simulation chamber;
a reaction spring configured to elastically support the reaction piston; and
a simulation valve arranged at an inlet of the simulation chamber.

11. The electric brake system according to claim 10 , wherein the simulation valve is a Normally Closed solenoid valve that remains closed in a normal state and is opened upon receiving a signal for an opening operation from the electronic control unit.

Assignees

• Mando Corp

Inventors

• Yang I Jin
• Choi Seong Ho

Classifications

• B60T13/662

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

• B60T13/686

  in hydraulic systems or parts thereof · CPC title

• B60T7/042

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

• B60T13/745 Primary

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

• B60T8/4081

  Systems with stroke simulating devices for driver input (B60T8/4077 takes precedence) · CPC title