The disclosure relates to compressors for heat exchange systems, heat exchange systems having such compressors, and methods for controlling operation of compressors. The compressor includes a drive device for driving the compressor and having at least a first and second working conditions. An output power of the drive device under the second working condition is greater than an output power under the first working condition. The compressor has at least one upload/download flow path configured to be opened before the drive device is switched from the first working condition to the second working condition to reduce a suction flow of the compressor until current operating parameters of the compressor reach preset values, after which the switching is performed, and to increase the suction flow until the compressor is in a required working state, after the switching is completed.

A positive displacement device includes a first cylinder, a second cylinder disposed within the first cylinder, and a third cylinder disposed around the first cylinder. An interior surface of the first cylinder and an exterior surface of the second cylinder define an inner cavity. An exterior surface of the first cylinder and an interior surface of the third cylinder define an outer cavity. A partition between the interior surface of the first cylinder and the exterior surface of the second cylinder divides the inner cavity into inner regions, and another partition between the exterior surface of the first cylinder and the interior surface of the third cylinder divides the outer cavity into outer regions. The second cylinder and the third cylinder orbit with respect to the first cylinder to create alternating regions of high pressure and low pressure in the inner regions and the outer regions.

A compressor may include non-orbiting and orbiting scrolls, a hub plate, and primary and secondary discharge valve assemblies. The non-orbiting scroll includes a first end plate having primary and secondary discharge passages. The hub plate may be mounted to the non-orbiting scroll and may include a main body and a central hub extending axially from the main body. The central hub may include a recess and a hub aperture. The primary discharge valve assembly may include a retainer and a primary valve member. In a closed position, the primary valve member may restrict fluid flow between the discharge chamber and the primary discharge passage. The secondary discharge valve assembly may include a secondary valve member that selectively allows and restricts fluid communication between the secondary discharge passage and the hub aperture of the central hub.

A vacuum pump for pumping a gas includes a pump housing which defines a pump cavity, a shiftable vane, a pump rotor body, a separate axial rotor retaining arrangement, and a radial friction bearing. The pump housing includes a closed housing wall. The pump rotor body includes a vane slit which supports the shiftable vane to define rotating pumping chambers, an axial low-pressure end which is axially supported by the closed housing wall so that a gas pressure inside the pumping chambers is present at the low-pressure end, and an axial high-pressure end. The pump housing is fluidically open at the axial high-pressure end so that atmospheric pressure is present. The axial rotor retaining arrangement includes a retaining sheet body arranged in a transversal plane which axially in part blocks the axial high-pressure end. The radial friction bearing is arranged axially between the vane slit and the axial high-pressure end.

The present disclosure provides a compressor including a rounded portion surrounding a discharge port, including a cylinder without an oil-blocking structure for ease of shaping the rounded portion, and including a valve-recess cover coupled to the cylinder. At least one valve-recess is defined in an outer face portion of the cylinder. A discharge valve assembly is fixedly received in the valve-recess, wherein the discharge valve assembly is configured for opening and closing the discharge port. The valve-recess is defined between the outer face, primary and secondary side blocks. The rounded portion surrounds the discharge port, to reduce a contact area between the discharge port and the valve assembly.

A compressor system includes: a compressor having a suction side and a discharge side, wherein the compressor is operative to compress a gas using oil, wherein the suction side operates at a suction pressure and is operative to receive a the gas and the oil into the compressor; and wherein the discharge side is operative to discharge the compressed gas and the oil; a gas/oil separator tank operative to store oil separated from the compressed gas for subsequent use by the compressor; a supplemental oil reservoir in fluid communication with the suction side; and a valve operative to, when opened, expose the supplemental oil reservoir to the suction pressure of the suction side of the compressor, and draw oil from the supplemental oil reservoir by suction into the suction side of the compressor.

A compressor includes a compression mechanism that compresses low-pressure refrigerant in a compression chamber into high-pressure refrigerant, and an injection pipe arranged to supply intermediate-pressure refrigerant to the compression chamber. A valve assembly is disposable between the compression chamber and the injection pipe. The valve assembly includes an opening forming member that forms an opening, a valve body and a spring member. The valve body moves in accordance with differences between pressure of the refrigerant supplied from the injection pipe and pressure of the refrigerant in the middle of compression in the compression chamber. The valve body blocks the opening when the valve body has moved from a compression chamber side to an injection pipe side. The spring member is disposed on the injection pipe side of the opening. The spring member applies force in a direction of the injection pipe to the valve body.

An object is to optimize a back pressure pressing an orbiting scroll against a fixed scroll in a scroll compressor to which an injection cycle is applied. A back pressure control valve (400) adjusting back pressure (Pm) in a back pressure chamber (H4), adjusts the opening degree of a first valve body (424) increasing and decreasing the flow rate of lubricant which has been separated from gaseous refrigerant compressed in a compression chamber and is supplied to the back pressure chamber (H4), in accordance with suction pressure (Ps) in a suction chamber (H1), discharge pressure (Pd) in a discharge chamber (H2), and injection pressure (Pinj). Then, the back pressure control valve (400) increases and decreases the lubricant flow rate in accordance with injection pressure (Pinj) as well as suction pressure (Ps) and discharge pressure (Pd), to adjust back pressure to target back pressure varying in accordance with injection pressure (Pinj).

A multi-stage compressor includes a compression module configured to compress a refrigerant therein through reciprocation of a plurality of pistons provided in a front housing, a rear housing coupled to the front housing to define an internal space between the front housing and the rear housing; a separation plate located between the front housing and the rear housing to separate the internal space between the front housing and the rear housing into a front space and a rear space; and a partition wall coupled to the rear housing to partition the rear space into an injection space before a refrigerant injected thereinto is primarily compressed, a primary discharge space from which the refrigerant is discharged in a primary compressed state by some of the pistons, and a secondary discharge space from which the primary compressed refrigerant is discharged.

Systems and methods are used to control operation of a rotary compressor of a refrigeration system to improve efficiency by varying the volume ratio and the speed of the compressor in response to current operating and load conditions. The volume of the axial and/or radial discharge ports of the compressor can be varied to provide a volume ratio corresponding to operating conditions. In addition, permanent magnet motors and/or control of rotor tip speed can be employed for further efficiency gains.