DK146861B - SCOROTOR MACHINE WITH TWO PARALLEL COLLECTIVE SPINDLES - Google Patents

Description

146861 i

The invention relates to a screw rotor machine of the kind specified in the preamble of the claim, in particular for compressing compressed air, which is forced by the rotation of the screws from the inlet opening through the channels formed by the cooperating screw threads with decreasing cross-sectional profile for the outlet opening.

From, for example, the description to Austrian patent no.

261 792, such a twin-rotor machine is known in which the rotors have decreasing diameters and / or decreasing groove depth towards the high-pressure side. In such machines, the barrel diameter is changed continuously over the entire spindle length, also at the inlet and outlet of the medium, i.e., the medium having a certain elasticity also undergoes immediately at the inlet and at the outlet a compression or expansion, which in practice have been shown to induce vibrations due to eddy formation. The vibrations cause a noisy operation and cause a loss of pressure during compression.

The invention has for its object to overcome this disadvantage.

This is achieved according to the invention by a design of the windscreen as indicated in the characterizing part of the claim. By such a constant retention of the channel-forming cross-sectional area of the first and last screws, the inlet and outlet ratios of the medium are stabilized, thereby avoiding vibration, pressure loss and noise, and the axially directed load compressive forces acting on the mechanical parts of the machine are substantially reduced.

The helical rotors of the machine can conveniently be built up by supporting punched sheet metal plates with mutually taped outer threaded grooves.

The invention will be explained in more detail below with reference to the drawing, in which: 1 shows a section through a screw rotor machine according to the invention along the plane through the spindle shafts; and FIG. 2 is a section through the machine of FIG. 1 along line II-II.

5 The screw rotor machine of FIG. 1 can be used as a compressor for compression or as an engine for expansion of a gaseous medium supplied. The machine has two helical twin spindles 1a, 1b and 2a, 2b lying parallel to each other as cam rollers, and 10 each having a bearing pin 3 and a drive shaft 4. The bearing pins 3 and drive shafts 4 rest in ball bearings 5 which is built into two identical, mutually opposed bearing shields 6 in a machine housing 7. The two drive shafts 4 are interconnected over identical gears 8. The twin spindle halves 15a, 1b and 2a, 2b each have a threaded groove 9, the width of which is radial depth decreases in direction from the outer spindle towards the center.

In groove 9, a correspondingly designed threaded tooth 10 engages on the second spindle, so that for each screw operation of the two twin spindle halves 1a, 1b and 2a, 2b, a groove-filled groove volume is closed between the inner sheath of the housing 7 and the cam lu of the opposite spindle at their points of engagement in the plane determined by the spindle axes.

The outer diameter of the twin spindles 1a, 1b and 2a, 2b decreases tapered towards the center of the spindle, while the core diameter increases tapered towards the center. The housing 7 is therefore bifurcated and provided with longitudinal flanges 11.

Rotate the two twin spindles 1a, 1b and 2a, 2b of FIG. 1 30 seen at their upper casing side against each other, the machine acts as a compressor in which the gaseous medium flows through channels 12 of the two bearing shields 6 and is displaced in groove volumes against the twin spindles 1a, 1b and 2a, 2b as the medium flows in in a central groove 13 and flows through a housing groove 14 out of the machine through 5 channels 15. As the cross-section of the thread groove 9 decreases from the ends of the twin spindles towards the center, the individual closed groove volumes of the screw threads also decrease, thereby increasing the pressure and density of the medium.

In order to prevent a relative backflow of the medium in the altered groove cross section, the first threading at the inlet of the medium as well as the last screwing before the outlet of the medium according to the invention are designed with a constant thread groove cross section. The axial forces exerted by the pressure difference between the inlet and outlet of the medium on the spindles are compensated by the twin spindles 1a, 1b and 2a, 2b such that the ball bearings 5 are only radially loaded.

With the same direction of rotation, the machine can also be used as a vacuum pump to produce a negative pressure in the channels 20 12. The diluted medium is then condensed to atmospheric pressure and also leaves the machine through the channels 15.

If the machine is supplied with a gaseous medium with overpressure through the channels 15, the medium can expand in the enclosed groove volume against the channels 12, so that the machine acts as a motor. The twin spindles 1a, 1b and 2a, 2b then rotate away from one another, seen at their upper casing side (Fig. 1).

The width of the threaded groove 9 is defined by flat planes 16 perpendicular to the spindle axis, which appear 30 in succession seen in the helix, and by mutually spaced steps 17. Thus, the groove 9 acts as a series of parallel parallel laterally displaced recesses 14. (Fig. 1). Hereby, the rotors can be built up by stacking punched sheet metal plates with suitably stepped outer surfaces.

As shown in FIG. 2, the machine has a circular cross section 5 and contains holes 23 for material saving and weight reduction. The two bearing shields 6 are secured to the housing 7 by means of stud bolts through bores 24.

The machine may also be provided with twin spindles 1a, 1b and 2a, 2b, the outer diameter of which increases conically against the center and whose core diameter decreases towards the center. Conveniently, the twin spindles can also be designed with a constant outer diameter, whereby the machine housing 7 can be formed in one piece and with cylindrical bores.

The spindles 1a, 1b and 2a, 2b can also be formed as shafts 15 on which inseparable annular discs are arranged close to each other with omega-shaped recesses. These ring washers must be angularly oriented so that their recesses together form the threaded groove 9.

Such slices are shown in FIG. 1 is indicated on the right side of the twin spindles.

The machine according to the invention has a simple structure with fixed and rotating parts with a relatively small diameter, so that very high turnover figures are possible. Thereby, a friction-poor closure is obtained at a small clearance.