An air compressor of weight-reduction type is disclosed, wherein the bearing and the main housing thereof are formed integrally, so that when the piston body conducts reciprocating motion within the cylinder at high frequencies, the bearing is firmly fixed on the main housing without nonfunctioning or falling off. Furthermore, the main housing and the cylinder thereof are made of plastic and formed integrally. The main housing is formed with a wind collecting hood to facilitate the air flow being introduced through the main housing for rapidly dissipating the heat generated by the bearing and the heat generated from the reciprocating motion of the piston body. Accordingly, the manufacturing cost of the air compressor can be reduced to achieve an economical design, and the weight of the air compressor can be reduced to facilitate the compressor being carried onto a vehicle.

An air compressor includes an air storage unit defining a first chamber and a cylinder containing a piston body. The top wall of the cylinder is formed with a tubular projection defining a bore to serve as a second pressure chamber. When the piston head of the piston body is almost in contact with the top wall of the cylinder, part of the compressed air can enter the second pressure chamber, so that the piston body can conduct reciprocation motion more smoothly. Furthermore, the cylinder has an open bottom that is divided into two halves according to a central vertical line of the cylinder, wherein one half of the open bottom is horizontal while the other half of the open bottom is slanted. When the piston body is at BDC, the piston head will be entirely within the cylinder and thus keep gas-tight with the cylinder.

An air compressor includes an air storage unit defining a first chamber and a cylinder containing a piston body. The top wall of the cylinder is formed with a tubular projection defining a bore to serve as a second pressure chamber. When the piston head of the piston body is almost in contact with the top wall of the cylinder, part of the compressed air can enter the second pressure chamber, so that the piston body can conduct reciprocation motion more smoothly. Furthermore, the cylinder has an open bottom that is divided into two halves according to a central vertical line of the cylinder, wherein one half of the open bottom is horizontal while the other half of the open bottom is slanted. When the piston body is at BDC, the piston head will be entirely within the cylinder and thus keep gas-tight with the cylinder.

An actuated rotary valves for reciprocating compressors used in oil and gas industry, the valve including a stator with a stator opening, a rotor with a rotor opening, and an actuation mechanism. The actuation mechanism is configured to receive a rotation motion and to actuate the rotor to perform first an axial translation moving away from the stator and then a rotation. The actuation mechanism includes an outer shaft configured to receive the rotation motion, and an inner shaft inside the outer shaft and configured to rotate the rotor. The outer shaft is configured to rotate a predetermined angular displacement while pushing the rotor away from the stator before engaging the inner shaft to rotate together with the rotor.

An actuated rotary valves for reciprocating compressors used in oil and gas industry, the valve including a stator with a stator opening, a rotor with a rotor opening, and an actuation mechanism. The actuation mechanism is configured to receive a rotation motion and to actuate the rotor to perform first an axial translation moving away from the stator and then a rotation. The actuation mechanism includes an outer shaft configured to receive the rotation motion, and an inner shaft inside the outer shaft and configured to rotate the rotor. The outer shaft is configured to rotate a predetermined angular displacement while pushing the rotor away from the stator before engaging the inner shaft to rotate together with the rotor.

A pumping assembly keeps a pneumatic tire from becoming underinflated. The pumping assembly includes an even number of pumps attached to the tire rim, a gravity mass for producing a pumping action, a cam fixed to the gravity mass for maintaining the cam in a fixed position relative to the gravity mass, and rollers for engaging the cam and producing the pumping action as the tire rim rotates and the gravity mass retards rotation of the cam as the tire rim rotates.

A pumping assembly keeps a pneumatic tire from becoming underinflated. The pumping assembly includes an even number of pumps attached to the tire rim, a gravity mass for producing a pumping action, a cam fixed to the gravity mass for maintaining the cam in a fixed position relative to the gravity mass, and rollers for engaging the cam and producing the pumping action as the tire rim rotates and the gravity mass retards rotation of the cam as the tire rim rotates.

A lubricating oil supply apparatus may include a rotational portion that rotates together with a rotational shaft and a fixed portion that maintains a fixed location thereof and supplies oil through a space that circles with respect to a rotational center of the rotational portion, thereby supplying oil regardless of a rotational direction of the rotational shaft.

A lubricating oil supply apparatus may include a rotational portion that rotates together with a rotational shaft and a fixed portion that maintains a fixed location thereof and supplies oil through a space that circles with respect to a rotational center of the rotational portion, thereby supplying oil regardless of a rotational direction of the rotational shaft.

A method and apparatus for gas compression and expansion that simultaneously serves as storage tank for the compressed gas, and heat exchanger for heat transfer to the environment to maintain near-isothermal conditions.