A rotary compressor includes a cylindrical housing, a cylindrical roller accommodated in the housing, a motor shaft leading through the roller having a cam for rolling the roller along a side wall of the housing, and a discharge port leading through a bottom cover, wherein a height-to-radius ratio of the roller is between 6 and 1.2, a radius of the motor shaft is 8.0 mm or less, a cam height of 14 mm or less, an area of the discharge port of 17 mm.sup.2 or more, and a thickness of the discharge port of 2.5 mm or less. For operation of the compressor, a top cover may be put onto the top open side of the housing. The top cover may have a bushing for the shaft. A heat pump includes the compressor. A household appliance, in particular laundry care apparatus, includes the heat pump.

A compressor may include a non-orbiting scroll, an orbiting scroll, a driveshaft and an Oldham coupling. The orbiting scroll meshingly engages the non-orbiting scroll. The driveshaft includes a crankpin engaging the orbiting scroll and driving the orbiting scroll in an orbital path relative to the non-orbiting scroll. The Oldham coupling may include an annular body and a plurality of first keys extending from the annular body and slidably received in slots formed in the orbiting scroll. Each of the first keys may include a first post and a first cap covering at least a portion of the first post. The first posts may be integrally formed with the annular body from a first material. The first caps may be attached to the first posts and formed from a second material.

A gear pump includes a housing, at least one gear set and a plurality of end plates. The gear set may be positioned between the end plates so that side surfaces of the gears face corresponding side surfaces of the end plates. The side surfaces of the end plates may have a plurality of spiral grooves positioned directly adjacent the side surface of the gears. The plurality of spiral grooves may have a logarithmic shape. Thus arranged, when the gears rotate, fluid in the pump is forced along the lengths of the spiral grooves, creating a local high pressure region that forces fluid between the side surfaces of the gears and the end plates, minimizing or eliminating contact therebetween. In some embodiments the plurality of spiral grooves may be positioned on bearing surfaces of the pump instead of end plates.

The present disclosure relates to a field of scroll compressors, and more particularly to a muffler device and a compressor with the muffler device. In one embodiment, a muffler device includes a sound hood inside which an expanding cavity is defined, and a microporous plate which is disposed inside the expanding cavity and divides the expanding cavity into a first cavity body and a second cavity body, and a plurality of through holes are provided in the microporous plate such that the air flow entering the expanding cavity exits the expanding cavity after passing through the plurality of through holes of the microporous plate. The muffler device and the compressor with the muffler device provided herein may effectively reduce the noise of the scroll compressor, especially pneumatic noise.

A compressor includes an actuator, a compression mechanism, a drive shaft, a support, a casing, and a welding pin. The drive shaft transmits a driving force of the actuator to the compression mechanism. The support supports a bearing that rotatably supports the drive shaft. The support has at least one hole formed in an outer surface. The casing has a cylindrical shape and accommodates the drive shaft and the support. The welding pin is press-fitted into the hole of the support and is welded and fixed to the casing. A low rigidity region is provided at at least a part of a periphery of an adjacent portion adjacent to the hole of the support. The low rigidity region has lower rigidity than the adjacent portion. The low rigidity region includes a thin portion having a smaller thickness in a radial direction of the casing than the adjacent portion.

A liquid ring screw pump includes a housing with a suction inlet section and a pressure outlet section. Within the housing an Archimedes screw rotor is driven by a motor via a shaft. The inlet section and outlet section are each provided with connecting structure for suction and pressure piping respectively. The displacement CD of the screw rotor in relation to the center axis of the housing is determined by an equation based on the screw rotor radius, a minimum screw rotor core radius, and a variable k that is between 0.14 and 0.29.

A shaft (1) is shown comprising a shaft section (2) having an axis (3), a tooth geometry (4) at least at one end of said shaft section, said tooth geometry (4) having a first end (5) opposite said shaft section (2) and a second end (6) adjacent said shaft section (2), a number of teeth (7) distributed in circumferential direction around said axis (3), a bottom curve (9) between adjacent teeth (7), and an outer tooth curve (12), said bottom curve (9) having a positive slope from said first end (5) towards said shaft section (2) and a negative slope (14) at said second end (6). In such a shaft wear should be made as small as possible. To this end said bottom curve (9) comprises a section having a concave bottom curvature (15) between said positive slope and said negative slope.

The present invention provides a rotary engine including a housing having therein N rob accommodating portions (N is a natural number equal to or greater than 3), and combustion chambers communicating with the rob accommodating portions, respectively, a rotor having N1 robs eccentrically rotating centering on a center of the rob accommodating portions, and consecutively accommodated in the respective rob accommodating portions during the eccentric rotation, and combustion controllers provided at both sides of each combustion chamber, and configured to limit a combustion range of mixed gas, whereby an excessive emission of unburned gas caused in an existing rotary engine can be overcome, efficiency of the engine can be improved, and a rotary engine with an optimized design condition can be provided.

A gear pump includes a housing, at least one gear set and a plurality of end plates. The gear set may be positioned between the end plates so that side surfaces of the gears face corresponding side surfaces of the end plates. The side surfaces of the end plates may have a plurality of spiral grooves positioned directly adjacent the side surface of the gears. The plurality of spiral grooves may have a logarithmic shape. Thus arranged, when the gears rotate, fluid in the pump is forced along the lengths of the spiral grooves, creating a local high pressure region that forces fluid between the side surfaces of the gears and the end plates, minimizing or eliminating contact therebetween. In some embodiments the plurality of spiral grooves may be positioned on bearing surfaces of the pump instead of end plates.

A scroll type positive displacement assembly includes a first scroll and a second scroll, where the second scroll is configured to orbit with respect to a center of the first scroll without rotating with respect to the first scroll. Together, the first scroll and the second scroll define a compression chamber between two seal points where the first scroll and the second scroll contact one another as the second scroll orbits with respect to the first scroll during a compression cycle, and the two seal points come together proximate to a discharge port between the first scroll and the second scroll such that there is at least substantially no dead space between the first scroll and the second scroll at an end of the compression cycle. For example, the two seal points remain in sealing contact during at least one hundred and eighty (180) degrees of the compression cycle.