Disclosed is a vane pump comprising a cam ring accommodated in a pump housing, a rotor accommodated rotatably with respect to a rotational shaft in the cam ring, and a plurality of vanes coupled to the rotor to discharge fluid, wherein the cam ring has a ring shaped inner profile varied between a maximum radius (Rmax) and a minimum radius (Rmin) in a circumferential direction with respect to the rotational shaft, and the ring shaped inner profile comprises: a cycloid curve passing through a maximum radius point; a circular arc passing through a minimum radius point; and a tangent line connecting the cycloid curve to the circular arc with a tangential curvature.

A rotary compressor is provided that may include a casing, a cylinder, a main bearing, a sub bearing, a rotational shaft, a roller, and at least one vane. The cylinder may include at least one elastic deformation unit to absorb impact with the at least one vane. With this structure, a collision force caused due to chattering of the at least one vane may be absorbed to suppress or prevent friction loss and/or wear between the cylinder and the vane, thereby enhancing compressor efficiency, reducing vibration noise, and enabling fast initial actuation.

A pump having at least two fluid drivers and a method of delivering fluid from an inlet of the pump to an outlet of the pump using the at least two fluid drivers. Each of the fluid drives includes a prime mover and a fluid displacement member. The prime mover drives the fluid displacement member to transfer fluid. The fluid drivers are independently operated. However, the fluid drivers are operated such that contact between the fluid drivers is synchronized. That is, operation of the fluid drivers is synchronized such that the fluid displacement member in each fluid driver makes contact with another fluid displacement member. The contact can include at least one contact point, contact line, or contact area.

A rotary internal combustion engine with a rotor body made at least in major part of a first material, with at least the contact surface of the rotor lands including a second material having a greater wear resistance than that of the first material with respect to frictional engagement with the portion of the inner surface of the internal cavity contacting the at least one land. For at least one of the end faces, the land(s) include(s) the first material and the contact surface is defined by a surface layer of the second material on the first material. A method of axially positioning a rotor of a rotary engine within an internal cavity of an outer body of the engine are also discussed.

A compressor system includes a compressor including a bearing supporting a rotating shaft; a sensor configured to measure an index value correlated with a movement of the rotating shaft being made while the compressor is in operation; and a wear-detecting unit configured to detect a degree of wear of the bearing based on a measured value obtained by the sensor. The bearing is a plain bearing, and has a plurality of air gaps arranged at intervals in a circumferential direction such that wear of the bearing changes a positional relationship between an inner circumferential surface of the bearing and the plurality of air gaps and eventually changes a shape of the inner circumferential surface thereof. The wear-detecting unit detects the degree of wear of the bearing based on a change in the measured value caused by a change in the shape of the inner circumferential surface of the bearing.

A pump having at least two fluid drivers and a method of delivering fluid from an inlet of the pump to an outlet of the pump using the at least two fluid drivers. Each of the fluid drives includes a prime mover and a fluid displacement member. The prime mover drives the fluid displacement member to transfer fluid. The fluid drivers are independently operated. However, the fluid drivers are operated such that contact between the fluid drivers is synchronized. That is, operation of the fluid drivers is synchronized such that the fluid displacement member in each fluid driver makes contact with another fluid displacement member. The contact can include at least one contact point, contact line, or contact area.

A rotary internal combustion engine with a rotor body made at least in major part of a first material, including at least one land protruding axially from each of its end faces and defining a contact surface extending at a fixed position with respect to the end faces. The contact surface frictionally engages a portion of the inner surface of the internal cavity of the engine, and at least the outer surface of the land includes a second material. The second material has a greater wear resistance than that of the first material with respect to frictional engagement with the portion of the inner surface of the internal cavity contacting the land. A method of axially positioning a rotor of a rotary engine within an internal cavity of an outer body of the engine are also discussed.

A fuel pump includes: an outer gear; an inner gear that is meshed with the outer gear and includes a receiving hole; a rotatable shaft; a contact portion that is formed to be contactable with the receiving hole; and a pump housing that rotatably receives the outer gear and the inner gear and includes a first housing component and a second housing component, between which the inner gear is held in the axial direction. At least one of the receiving hole and the contact portion includes a tilt surface, which is tilted relative to the axis direction. When the rotatable shaft is rotated to a drive rotation side, the receiving hole contacts the contact portion through the tilt surface, so that the receiving hole is urged in a circumferential direction and is also urged toward the first housing component in the axial direction.

A scroll compressor comprising a fixed scroll (15); an orbiting scroll (16) supported in a manner allowing for orbiting motion; a discharge port through which a fluid compressed by the two scrolls (15, 16) is discharged; an end plate step portion (16E) provided on an end plate of the orbiting scroll (16) formed so that a height of the end plate is higher on a center portion side in the direction of a spiral wrap and lower on an outer end side; and a wrap step portion (15E) provided on a wall portion of the fixed scroll (15) that corresponds to the end plate step portion (16E) so that a height of the wall portion is lower on the center portion side of the spiral and higher on the outer end side; wherein the orbiting scroll (16) is treated for surface hardening and the fixed scroll (15) is not treated for surface hardening.

Carbon dioxide compressors having one or more coatings with wear surfaces having electroless surface coatings are provided. Alternatively, propane compressors are contemplated having wear surface coatings. The coating is electrolessly applied and may comprise nickel and wear resistant particles, such as boron nitride. The electroless surface coatings for use with compressor machines improve corrosion and wear resistance, as well as anti-friction properties for compressors processing CO.sub.2 or C.sub.3H.sub.8 containing refrigerants. In certain aspects, a scroll machine has an Oldham coupling and/or lower bearing comprising aluminum and has an electroless surface coating comprising nickel boron nitride particles disposed on one or more wear surfaces. In other aspects, a reciprocating compressor has a wear surface, such as on a connecting rod and/or piston coated with an electrolessly applied nickel and boron nitride particle layer. Methods for making the electroless surface coatings are also provided.