A gear wheel (10) for a hydraulic apparatus is rotatable about an axis of rotation (H-H) and comprises a plurality of teeth (11) having a sectional profile (P) and being adapted to mesh with respective teeth of another gear wheel during a rotational motion about the axis of rotation (H-H), wherein at least one tooth (11) is shaped so as to have at least one cutting edge (12) configured to remove material, in particular chips, from a body which is contacted by said cutting edge during the rotation of the gear wheel (10). Suitably, the cutting edge (12) is defined by at least one groove (14) which is lowered by amount from 0.2% to 5% of the height (H′) of the tooth (11), said groove (14) decreasing away from the cutting edge (12) along the profile (P).

A positive displacement device that converts energy, namely positive displacement compressors that rotate in a single rotational direction to displace working fluid contained in operating chambers. The device described herein is particularity advantageous for the ability to achieve high compression ratios in combination with high discharge pressure and high volumetric throughput in a single stage.

A rotary piston engine comprises a housing (10), which forms an interior space (11), and at least two rotary pistons (20, 30), which are arranged in the interior space (11). Formed on the interior space (11) are an inlet opening (13) and an outlet opening (15) to guide a fluid through the interior space (11). The rotary pistons (20, 30) are thereby driven by fluid flowing through. Each rotary piston (20, 30) has on its outer circumference at least two sealing strips (21, 31). According to the invention each rotary piston (20, 30) comprises at least two cavities (27, 37), in each of which a tube (38B) or an elastic solid rod is arranged. The sealing strips (21, 31) project into the cavities and against the tube (38B) received therein or the elastic solid rod. Through the tube (38B) or the rod, the sealing strips (21, 31) are pushed radially outwards.

A pump particularly for pumping a liquid such as ink, paint, glue or the like, includes at least one rotating pumping member having a respective shaft. The at least one rotating pumping member being at least partially housed inside a pump body, the shaft being rotatably supported by at least one support associated with the pump body.

The shaft has on its external cylindrical surface in contact with the liquid one, or more recesses, or the at least one support includes on its internal cylindrical surface in contact with the liquid, one or more recesses.

An internal combustion engine includes one or more pairs of non-meshing, externally timed rotors disposed within a housing in an expander module and a compressor module. Each rotor includes a cylindrical, center main body including a first end, a second end opposite the first end, an elongate portion extending between the ends and a first peripheral surface portion and a second peripheral surface portion and a bore extending through a center of the main body from the first end to the to second end. The rotors each have a groove extending along outer peripheral edge portions of the rotor. A pair of tip seals is disposed in the grooves. A pair of apex seals is disposed on the first peripheral surface portion and the second peripheral surface portion and an axially floating end plate is disposed at an end of the housing.

A pressure reducer for a rotary internal combustion engine comprises a housing (1) accommodating a first shaft (6) and a second shaft (8) running parallel to each other through the housing (1), and a first rotor (7) on the first shaft (6) and a second rotor (9) on the second shaft (8). The first rotor (7) and the second rotor (9) are configured in a meshing arrangement, when the first shaft (6) and the second shaft (8) rotate in counter direction to each other. The first rotor (6) comprises several radial extensions (10) having convex shaped outer flanks (11), and the second rotor (9) comprises several radial wings (13) defining indentations (14) between two wings (13) having a concave shaped surface (15). A pressure expansion chamber (17) is defined by a volume between a convex shaped flank (11a) of an extension (10a) of the first rotor (7) and a concave shaped surface (15a) of an indentation (14a) of the second rotor (9), such that an outer tip (12a) of the radial extension (10a) abuts on the concave shaped surface (15a) of the indentation (14a) and an outer edge (16a) of the indentation (14a) abuts on the convex shaped flank (11a) of the extension (10a). In rotation the tip (12a) slides over the concave surface (15a) of the indentation (14a) and the edge (16a) of the indentation (14a) slides along the convex flank (11a), thereby expanding the volume of the pressure expansion chamber (17).

A positive displacement device that converts energy, namely positive displacement compressors that rotate in a single rotational direction to displace working fluid contained in operating chambers. The device described herein is particularity advantageous for the ability to achieve high compression ratios in combination with high discharge pressure and high volumetric throughput in a single stage.

The invention reduces a pressure or thermal effect while reducing the mass of a screw rotor. There is provided a screw rotor having a helical tooth on an outer periphery, the helical tooth extending by a predetermined length in an axial direction, in which a radial cross section of the screw rotor includes a lobe portion having a predetermined thickness in a direction toward an axis and forming the helical tooth, and a hollow portion extending from an axial side inner surface of the lobe portion toward an axial side, and the predetermined thickness of the lobe portion differs between a high load side on the outer periphery of the screw rotor and a low load side on the outer periphery.

A rotary piston engine comprises a housing (10), which forms an interior space (11), and at least two rotary pistons (20, 30), which are arranged in the interior space (11). Formed on the interior space (11) are an inlet opening (13) and an outlet opening (15) to guide a fluid through the interior space (11). The rotary pistons (20, 30) are thereby driven by fluid flowing through. Each rotary piston (20, 30) has on its outer circumference at least two sealing strips (21, 31). According to the invention each rotary piston (20, 30) comprises at least two cavities (27, 37), in each of which a tube (38B) or an elastic solid rod is arranged. The sealing strips (21, 31) project into the cavities and against the tube (38B) received therein or the elastic solid rod. Through the tube (38B) or the rod, the sealing strips (21, 31) are pushed radially outwards.

A toothing for a gerotor pump comprises a plurality of outer teeth (10) at a gerotor inner element (1) and a plurality of inner teeth (20) greater by one at a gerotor outer element (2), wherein a centre (M1) of the gerotor inner element (1) is offset from a centre (M2) of the gerotor outer element (2) by an eccentricity (e), the outer teeth (10) thereby meshing with the inner teeth (20). A contour of the outer teeth (10) at the gerotor inner element (1) is essentially defined by a curve of a single ellipse from a tooth tip (11) continuously via tooth flanks (13) to a transition radius (14) towards a tooth space or a tooth root (12); wherein the principal axis of the ellipse is arranged radially to the gerotor inner element (1) and the centre of the ellipse determines a radius (R.sub.min) at the gerotor inner element (1) which corresponds to the maximum meshing depth of the gerotor outer element (2) between the outer teeth (10) at the meshing.