Rotary expansible chamber devices – Specific material
Patent
1992-06-01
1994-07-26
Bertsch, Richard A.
Rotary expansible chamber devices
Specific material
4182011, 403334, F01C 2100
Patent
active
053323769
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a screw compressor, especially for use as a super-charger for an internal combustion engine.
Such a screw compressor comprises a housing, having a barrel section and two end sections, enclosing a working space provided with inlet and outlet ports and formed by two intersecting bores, and a pair of intermeshing rotors mounted in the housing, each rotor being provided with helical lands and intervening grooves.
A screw compressor according to the invention is an improvement to earlier used super-chargers, e.g. turbo chargers which give a poor efficiency especially at low speed of the engine. A compressor according to the invention may suitably be driven by the crank shaft of the engine through a belt drive, which means that independent of the number of revolutions, the compressor can always deliver a volume of air enough to fill the engine and having a pressure higher than atmospheric pressure. Such feeding of pressurized air to the engine results in a higher power delivered.
In a screw compressor it is essential that the barrel section and the end sections of the housing in mounted position has acceptable rigidity for the intermeshing rotors to act properly. Earlier known compressor housings have been produced from east iron, which results in a rather heavy compressor partly due to the high density of iron, and partly due to relatively thick walls. Such housing further requires a considerable mount of work to cut the housing to exact dimensions (measure deviation 0.03 to 0.05 mm). Screw compressor housings have also been east from aluminium. In order to obtain the necessary stability the barrel section and one end section are cast as one unit. This means complicated bottom hole manufacture and thick walls. All those compressors are thus relatively heavy and bulky and are thus unsuitable for mounting on the side of the engine.
The aim of the present invention is to avoid the disadvantages mentioned above and to obtain a number of advantages in comparison with the earlier known screw rotor super-chargers.
SUMMARY OF THE INVENTION
A screw compressor according to the invention comprises barrel section of a housing which is produced by extrusion from a suitable material, preferably light metal, especially aluminium, and where the end sections each are provided with a projection shaped correspondingly to the transverse section of the working space and inserted into the barrel section by forced fit. Such an extruded housing needs considerably less and simpler adjustment. On the whole the extruded casing results in lower production cost. Furthermore an extruded barrel section can be cut into different lengths in order to achieve different swept volumes when using the same end sections. However, such an extruded barrel section is comparatively weak and needs strengthenings to obtain the necessary rigidity. This rigidity is obtained by the interconnection under pressure between the barrel section and the end section projections.
The highest rigidity is obtained if the interconnected surfaces are cylindrical but it is also possible according to the invention that at least one of the interconnected surfaces is tapered.
In a preferred embodiment of a compressor according to the invention, the outlet port means is provided in a portion of the barrel section having a flat surface. This flat surface can be produced by the extrusion which means a minimum of adjustment. The outlet ports can be cut out to a shape and size adapted to the desired internal compression ratio of the compressor.
A preferred embodiment of the invention will now be described in connection with the drawings where:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a perspective view of a compressor housing, with a barrel section and end sections which are separated from each other,
FIG. 2 shows a perspective view of a combined compressor and
FIG. 3 shows a central longitudinal section through the compressor, and
FIG. 4 shows an enlarged detail of a modification of FIG. 3.
DETAILED DESCR
REFERENCES:
patent: 1567073 (1925-12-01), Mocigemba
patent: 3057543 (1962-10-01), Marsden
patent: 4648817 (1987-03-01), Mariani
patent: 4711006 (1987-12-01), Baldenko et al.
patent: 4846642 (1989-07-01), Nuber et al.
Bertsch Richard A.
Freay Charles G.
Opcon Autorotor AB
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