JPS63189679A - Displacement type machine for compressible medium - Google Patents

Abstract

In a displacement machine for compressible media, having at least one conveying chamber which is arranged in a fixed housing and is designed in the manner of a spirally running slot, displacement bodies are assigned to the conveying chamber, engaging therein. The said displacement bodies, in the form of spirally designed strips (3', 3''), are held on a disc-shaped rotor which can be driven eccentrically with respect to the housing. The displacement body (3', 3'') is reinforced on the inlet-side end in an angle region between 0 DEG and preferably 90 DEG in its radial extent. <IMAGE>

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The invention relates to a positive displacement machine for compressible media, comprising at least one slit arranged in a stationary casing and formed in the form of a spirally extending slit. It is equipped with one pressure-feeding chamber and a displacement member attached to the pressure-feeding chamber and inserted into the pressure-feeding chamber, and the displacement member is eccentrically driven relative to the casing as a spiral strip. It concerns a type that is held approximately vertically on a possible disc-shaped rotor.

Prior Art This type of positive displacement machine is known, for example, from West German Patent No. 2603462.
Known by No. This known machine is characterized by an almost pulsation-free pumping of a gaseous working medium, for example consisting of air or an air-fuel mixture.
Therefore, it can also be used advantageously for supercharging purposes in internal combustion engines. During the operation of such a positive displacement machine working as a compressor, as a result of the difference in the curvature of the spiral along the pumping chamber between the spirally configured displacement member and both peripheral walls of the pumping chamber. A number of approximately crescent-shaped working chambers are formed. These working chambers move from the working medium inlet into the pumping chamber towards the working medium outlet, the volume of the working chamber being gradually reduced and the pressure of the working medium being correspondingly increased.

The displacement member is composed of a plurality of spiral strips held with edges approximately perpendicular to the disc-shaped rotor surface, and these strips have a large axial length relative to their thickness. have. The same thing applies to the stationary casing side, where the chamber walls consisting of spiral strips between the pumping chambers have a large length in the axial and circumferential directions compared to the wall thickness. . In this case, the vertical edges of the strips, at least in the upper end region furthest away from the rotor disc or the housing chamber, are relatively unstable and come into contact with adjacent structural parts during operation.

Furthermore, significant stresses occur in the base area of the strip edge, possibly leading to breakage.

OBJECTS OF THE INVENTION It is an object of the invention to provide a positive displacement machine of the type mentioned at the outset, such that the inlet edge of the displacement member is not susceptible to damage in the area of its transition to the rotor disk. .

Solution to the Problems The present invention has solved these problems as follows. That is, the displacement member is increased in width in the radial direction at the inlet end over an angular range between Oo and a maximum of 120°. An angular range of 900 is advantageous.

It is particularly advantageous if the wall thickness of the displacement element increases continuously in the inlet region up to the maximum thickness at the actual inlet edge. It is advantageous if this continuous increase is produced by spirally widening the outer contour of the displacement element relative to the inner contour. Not only does this measure reduce the tendency to vibrate during operation, but the stable inlet section is also suitable for mechanical post-processing, for example with a milling tool. Better surface quality is obtained as a result of the elimination of vibrations during processing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will now be explained according to the embodiments shown in the drawings: The drawings show a rotor of a positive displacement machine according to the invention in an end view. In the figures, parts that are not essential for understanding the essence of the invention, such as the stationary housing of the rotor, drive parts, bearing and guide parts, inflow and outflow of the working medium, etc., have been omitted.

The operating mode of the compressor, which is outside the scope of the present invention, is the one described in German Patent No. 2,603,462, which is exemplified as a prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The general reference numeral 1 designates the rotor of a positive displacement machine, which is used in particular for supercharging internal combustion engines. The rotor disk 2 has at least one end face, and particularly advantageously both end faces, of a displacement element in the form of a spirally extending strip 3', 3''; In the illustrated embodiment, two are shown that fit together.As can be seen from the illustration, the rotor 1 can have a whole system of many volutes in the same plane, how many volutes each It can be pumped from a unique inlet to a common outlet.

The displacement members are located in displacement chambers (not shown) in a stationary casing, each chamber being formed in the casing in the form of a spiral slit. Each of these displacement chambers leads from an inlet chamber provided on the outer periphery of the casing to an outlet chamber provided on the inner periphery of the casing. These displacement chambers have spiral, substantially parallel chamber walls arranged at regular mutual spacing. These chamber walls are formed, for example, by a number of circular arcs connected to one another. Between the chamber walls, displacement elements consisting of strips 3', 3'' enter the pumping chamber. For example, they are set to almost touch each other at two locations.

The rotor 1 is driven and guided by two mutually spaced eccentrics 5.

The eccentrics 4, 5 may be eccentric plates or eccentric cranks, with the central eccentric generally driving and the outer eccentric 5 guiding. In order to achieve unambiguous guidance of the rotor 1 in the dead center position, the two eccentrics 5 are precisely synchronized via a timing belt drive 6 shown in dotted lines. Due to this double eccentric drive, all points of the rotor disc 2 and thus all points of both strips 3', 3'' produce a circular displacement movement.

As a result of the strips 3', 3'' approaching the inner chamber wall as well as the outer chamber wall of the associated pumping chamber alternately, a crescent-shaped working chamber is formed, which encloses the working medium on both sides of the strip. During the rotation of the rotor disk 2, these working chambers move within the pumping chamber towards the outlet chamber, and with this movement the volume of the working chambers is reduced and the pressure of the working medium is correspondingly increased. .

In order to increase the stability, according to the invention the strips 3', 3"
The end on the inlet side is reinforced by an increased wall thickness. This reinforcement takes place over an angular range of 00 to 120°, in the case of the illustrated example an angular range of 00 to 900°. In this case, the wall thickness increases continuously up to the inlet edge. A continuous increase is produced in the simplest case by a spiral widening of the outer contour 3a of the strip relative to the inner contour 3b. That is, the original arc for a constant wall thickness is maintained and its center is moved by a dimension a. This results in a smooth transition at position A of the outer contour.

It is clear that in the angular range in which the displacement elements are reinforced, the walls of the pumping chamber do not run parallel. In accordance with the spirally widening of the outer contour of the strip, the shape of the directly opposite pumping chamber must also be adapted.

Of course, reinforcement of the pumping chamber may also be provided at the outlet end, ie at the inner volute in the embodiments described above.

When reinforcing the outlet end, the inner contour I! The thickness can be continuously increased by shifting the material inward in a spiral manner.

BRIEF DESCRIPTION OF THE DRAWINGS The drawing is an end view of the rotor of a positive displacement machine. 1... Rotor, 2... Rotor disk 'i 3's
3'...Strip, Raw, 5...Eccentric mechanism, 6...Timing belt transmission mechanism 3.3'...Pushing member

Claims (3)

[Claims] 1. A positive displacement machine for compressible media, comprising at least one pumping chamber arranged in an immovable casing and formed in the form of a spirally extending slit, and a pumping chamber attached to the pumping chamber and extending into the pumping chamber. The device is equipped with a displacing member with a spiral shape, and the displacing member has a spiral strip (3
The displacement member (3', 3'') is held substantially perpendicularly on a disc-shaped rotor that can be driven eccentrically relative to the casing.
Volumetric equipment, characterized in that the width is increased in the radial direction over an angular range between 0° and a maximum of 120° at the end on the inlet side. 2. 2. Positive displacement machine according to claim 1, wherein the wall thickness of the displacement member (3', 3'') increases continuously in the inlet region up to a maximum thickness at the actual inlet edge. 3. 3. Positive displacement machine according to claim 2, wherein the continuous increase in wall thickness is caused by a spiral widening of the outer contour (3a) relative to the inner contour (3b).