Brake apparatus for vehicle

1. A brake apparatus for a vehicle, comprising:

a screw bar connected to a driving motor and configured to rotate based on a rotary power from the driving motor;

a nut unit configured to move toward a pad member in response to a rotation of the screw bar, the nut unit including:

a nut surrounding the screw bar; and

a nut holder threaded to the screw bar and configured to move toward the pad member by the rotation of the screw bar; and

a piston unit having an inner surface surrounding the nut unit and configured to press the pad member when pushed by the nut unit toward the pad member,

wherein the nut holder is spaced apart from the inner surface of the piston when the screw bar is not rotated, and

wherein the nut is configured, when the nut holder moves toward the pad member by the rotation of the screw bar, to push the nut holder toward the inner surface of the piston unit such that the nut holder contacts the inner surface of the piston.

2. A brake apparatus for a vehicle, comprising:

a screw bar positioned inside a caliper body, and rotated by receiving power of a driving motor;

a nut unit including a nut which surrounds the screw bar, and a nut holder which is threaded to the screw bar, is movable on the nut and is moved toward a pad member by rotation of the screw bar; and

a piston unit surrounding the nut unit, and pressing the pad member,

wherein the nut holder is brought into contact with the piston unit while being moved toward the pad member, and moves the nut such that the nut pushes the piston unit, and

wherein the nut holder comprises:

a moving block threaded to the screw bar, and moved on the nut; and

a contact module section rotatably coupled to the moving block, moved together with the moving block, and brought into contact with the piston unit while being moved toward the pad member.

3. The brake apparatus according to claim 2 , wherein the nut comprises a nut body including a nut body section which is formed with a movement guide portion for guiding movement of the moving block.

4. The brake apparatus according to claim 3 , wherein the nut further comprises a nut head which is connected with the nut body, has a size larger than that of the nut body and comes into contact with the contact module section.

5. The brake apparatus according to claim 4 , wherein the nut body further includes a contact guide section which guides the contact module section to be brought into contact with the piston unit.

6. The brake apparatus according to claim 5 , wherein the contact guide section connects the nut body section and the nut head, and a width of the contact guide section increases from the nut body section toward the nut head.

7. The brake apparatus according to claim 6 , wherein

a plurality of movement guide portions are formed in the nut body section along a circumference, and

a plurality of contact module sections are disposed in the movement guide portions, respectively, and an interval between the contact module sections is expanded upon contact with the contact guide section such that the contact module sections are brought into contact with the piston unit.

8. The brake apparatus according to claim 7 , wherein the contact module section comprises:

a rotation bar rotatably installed on the moving block, and moved together with the moving block; and

a contact block coupled to the rotation bar, and brought into contact with the contact guide section.