Patent ID: 7748963

Claim:
A linear compressor comprising: a cylinder; a piston linearly reciprocally disposed in the cylinder to compress a fluid; a motor configured to operate the piston; an oil suction channel configured to allow oil to be introduced into a space between the cylinder and the piston; an oil discharge channel configured to allow the oil between the cylinder and the piston to be discharged to the outside of the cylinder; and a pumping device formed at the cylinder and the piston, the pumping device producing a low pressure between the cylinder and the piston when the piston moves in a first direction so as to allow the oil to be suctioned into the space between the cylinder and the piston via the oil suction channel, and producing a high pressure between the cylinder and the piston when the piston moves in a second direction so as to allow the oil between the cylinder and the piston to be discharged via the oil discharge channel, wherein the pumping device includes: a stepped cylinder portion formed at an inner peripheral surface of the cylinder such that a portion of the cylinder in front of the stepped cylinder portion has an inner diameter smaller than the inner diameter of a portion of the cylinder in rear of the stepped cylinder portion; and a stepped piston portion formed at an outer peripheral surface of the piston, the stepped piston portion being formed by a section of the piston having an increased wall thickness.