Electronic brake system

An electronic brake system comprising:

• a hydraulic pressure supply apparatus including a motor operated by an electrical signal outputted corresponding to a displacement of a brake pedal, a power converting unit for converting a rotational force of the motor into a linear movement, a cylinder block, a hydraulic piston connected to the power converting unit and movably accommodated in the cylinder block, a first pressure chamber provided at one side of the hydraulic piston and connected to one or more wheel cylinders, and a second pressure chamber provided at the other side of the hydraulic piston and connected to one or more wheel cylinders;
• a first dump passage communicating directly with the first pressure chamber and connected directly to a reservoir in which oil stored;
• a second dump passage communicating directly with the second pressure chamber and connected directly to the reservoir;
• a first dump valve provided on the first dump passage to control the flow of oil and provided as a check valve for blocking the flow of oil in the opposite direction while allowing the flow of oil in the direction to the first pressure chamber from the reservoir;
• a second dump valve provided on the second dump passage to control the flow of oil and provided as a check valve for blocking the flow of oil in the opposite direction while allowing the flow of oil in the direction to the second pressure chamber from the reservoir;
• a third dump valve provided on a bypass passage connecting an upstream side and a downstream side of the second dump valve on the second dump passage to control the flow of oil and provided as a solenoid valve for controlling the flow of oil in both directions between the reservoir and the second pressure chamber;
• and
• a fourth dump valve provided on a bypass passage connecting an upstream side and a downstream side of the first dump valve on the first dump passage to control the flow of oil and provided as a solenoid valve for controlling the flow of oil in both directions between the reservoir and the first pressure chamber.