FR2527702A1 - Compressor with rotary blades - has plastics lobes moulded on to rotor shafts equal in number to blades - Google Patents

Abstract

The compressor has a body with an inner cylindrical chamber having inlet and outlet holes and in this run two combined rotors. These have radial lobes driven by two gears on their shafts. Each rotor (5,6) is of plastics and moulded on a metal shaft (7,8). Blades (42) are welded on the shafts, and have holes (41). These are plastics filled during rotor moulding. The ends of each blade are bent over at their corners. The number of blades equals that of the lobes (normally three).

Description

 The invention relates to a rotary lobe fluid compressor, comprising a body which internally provides a cylindrical chamber of appropriate section, provided with fluid inlet and outlet ports, in which rotate two rotors conjugated with radial lobes placed in rotation by means of two gears mounted on the respective shafts of the rotors.

 According to the invention, such a compressor is characterized in that each of the rotors is made of plastic material overmolded on a respective metal shaft, on the latter being welded radial fins which are embedded in the lobes and ensure the joining of the rotor with its shaft both in rotation and in axial direction.

 The description which follows. with reference to the accompanying drawings by way of nonlimiting example, will make it possible to understand clearly how the present invention can be put into practice.

 Figure 1 shows in longitudinal section a compressor according to the invention.

 FIG. 2 represents a section along line II-II of the object of FIG. 1.

 FIG. 1 shows a compressor intended to supply a pressurized fluid such as air. The body of the compressor is constituted by a cylindrical casing 1 closed by two bottoms 2,3 so as to delimit an interior chamber 4, the section of which comprises two arcs of intersecting circles and in which two rotors 5.6 conjugated rotate. Each of these rotors comprises a shaft 7,8 of which are integral three radial lobes 9,10 hollowed longitudinally. The two shafts 7,8 extend in parallel and are coupled in rotation by a pair of pinions 11,12.

The casing 1 comprises an inlet orifice and a discharge orifice for the fluid to be compressed (which have not been shown).

 Each bottom 2,3 is a hollow casing offering an internal cavity 13,14. The forA2 is formed of an outer sheet 2a, stamped in hollow, and of a flat inner sheet 2b. Ball bearings 15,16 carrying the corresponding ends of the shafts 7,8 of the rotors 5,6 are embedded in the sheet 2b and protrude into housings hollowed out coaxially in the ends of the rotors 5,6.

The bottom 3 likewise comprises an outer sheet 3a, stamped in the shape of a bell, and an inner sheet b similar to the sheet 2b. Ball bearings 17,18 carrying the opposite ends S of the shafts 7,8 are held by a common part 36, made of a sheet metal strip conformed substantially in the shape of the figure eight and covered with a flange 37 also in jail. The pinions 11,12 are housed in the cavity 14 of the bottom 3. The shaft 8 emerges from the sheet metal 3a of the latter by a threaded part 8a for driving in rotation.

 The cavities 13, 14 communicate with each other by a channel 23 drilled coaxially in the shaft 7 of the rotor 5. Furthermore, the bottom 2 is provided with an orifice 30 drilled in the sheet 2a and opening into the internal cavity 13; similarly, the bottom 3 is provided with an orifice 29 pierced in the sheet metal 3a and opening into the internal cavity 14. The orifice 29 is a throttled inlet orifice and the orifice 30 an outlet of larger section , allowing a current of lubricating oil to circulate without pressure, thanks to an external pumping device, in the cavities 13,14 and the channel 23 by bathing the ball bearings 15,16,17,18 and the pinions 11 , 12.The cylindrical casing 1 comprises rectilinear cooling fins extending along generatrices of the casing, which makes it possible to produce the latter by spinning and cutting.

 The rotors 5 and 6 are made of plastic overmolded on the shafts 7 and 8 of metal. A perfect connection is ensured by the presence of a sleeve 38 welded to each shaft and comprising three radial fins 40 oriented like the lobes of the corresponding rotor (FIG. 2), which link each rotor to its shaft in rotation. To immobilize it in a certain way with respect to a displacement on its shaft in axial translation, it is advisable that said fins 40 are pierced with holes 41 which are filled with plastic during overmolding of the rotor.

In addition, provision may be made to fold the ends of each fin into a corner, as indicated at 42 in FIG. 1.

Claims (5)

 1. Fluid compressor with rotary lobes, comprising a body which internally offers a cylindrical chamber of appropriate section, provided with fluid inlet and outlet ports, in which rotate two rotors conjugated with radial lobes rotated by the intermediate of two gears mounted on the respective shafts of the rotors, characterized in that each of the rotors (5,6) is made of plastic material overmolded on a respective metal shaft (7,8), on the latter being welded radial fins (40) which are embedded in the lobes (9,10) and ensure the attachment of the rotor with its shaft both in rotation and in the axial direction.  2. Compressor according to claim 1, characterized in that the fins (40) are pierced with holes (41) which fill with plastic material during the molding of each rotor (5,6).  3. Compressor according to claim 1 or 2, characterized in that the ends (42) of each fin (40) are folded in a corner.  4. Compressor according to any one of claims 1 to 3, characterized in that the fins (40) are in number equal to that of the lobes (9,10).  5. Compressor according to claim 4, characterized in that each rotor (5,6) has three lobes (9,10) and three fins (40).