Electric brake system

An electric brake system comprising:

• a reservoir configured to store oil;
• a master cylinder having first and second hydraulic ports, connected to the reservoir to receive oil from the reservoir;
• a simulation device connected not only to a pedal displacement sensor sensing a displacement of a brake pedal, but also to the master cylinder, configured to provide reaction force in response to foot force applied to the brake pedal;
• a hydraulic-pressure supply device configured to convert rotational force of a motor into rectilinear motion upon receiving an electric signal from the pedal displacement sensor according to operation of the brake pedal, and move a double-acting piston designed to perform reciprocating motion within a hydraulic cylinder, wherein the double-acting piston moves in one direction to generate hydraulic pressure by pressing a first hydraulic chamber provided in one end thereof, and moves in another direction to generate hydraulic pressure by pressing a second hydraulic chamber provided in the other end thereof;
• a hydraulic-pressure control unit including a first hydraulic circuit connected to the first hydraulic chamber via a first hydraulic passage, and a second hydraulic circuit connected to the second hydraulic chamber via a second hydraulic passage, configured to control flow of hydraulic pressure applied to a caliper brake installed in one or more wheels via a plurality of valves disposed in the first and second hydraulic circuits;
• an electronic control unit (ECU) configured to control the motor and one or more valves on the basis of hydraulic pressure information and pedal displacement information;
• a first dump valve arranged in a flow passage, which is branched from downstream of a first switching valve of the first hydraulic passage and connects the first hydraulic passage to a reservoir, so as to control flow of oil;
• a second dump valve arranged in a flow passage, which is branched from downstream of a second switching valve of the second hydraulic passage and connects the second hydraulic passage to a reservoir, so as to control flow of oil;
• and
• a balance valve disposed in a flow passage interconnecting the first hydraulic circuit and the second hydraulic circuit, configured to interconnect or sever the two hydraulic circuits,
• wherein one end of the flow passage in which the balance valve is installed is branched from a section interposed between the first switching valve and the first dump valve, and the other end thereof is branched from a section interposed between the second switching valve and the second dump valve,
• wherein the hydraulic-pressure control unit includes:
• the first switching valve disposed in the first hydraulic passage communicating with the first hydraulic chamber, configured to control hydraulic pressure applied to the caliper brake;
• and
• the second switching valve disposed in the second hydraulic passage communicating with the second hydraulic chamber, configured to control hydraulic pressure applied to the caliper brake.