GB1561338A

GB1561338A - Spiral casing for fluid flow machines

Info

Publication number: GB1561338A
Application number: GB3670476A
Authority: GB
Original assignee: MAN Maschinenfabrik Augsburg Nuernberg AG
Current assignee: MAN AG
Priority date: 1975-09-06
Filing date: 1976-09-03
Publication date: 1980-02-20
Also published as: FR2323014B1; DE2539711A1; JPS5234116A; DE2539711B2; JPS5947130B2; FR2323014A1; DE2539711C3; CH609127A5

Abstract

In a spiral housing for turbo-engines at least one tongue (7, 8) is guided, sliding on the radially inner wall of the sprial housing, by virtue of the displacement of which tongue in the circumferential direction the inflow and outflow cross-section can be adjusted in that the tongue (7, 8) has end areas running radially inwards. The tongue (7, 8) is at the same time fixed on a pivotably mounted tongue insert, which is formed by a tubular connection piece lying opposite the spiral housing in the flow path. An exhaust turbocharger with such a spiral housing can be adjusted very precisely to the characteristic of an internal combustion engine. <IMAGE>

Description

(54) SPIRAL CASING FOR FLUID FLOW MACHINES (71) We, MASCHINENFABRIK AUGS suRG-NüRNsERG AKTIENGESELLSCHAFT, a German company, of Stadtbachstrasse 1, Augsburg 8900, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a spiral casing for a fluid flow machine particularly, although not exclusively, an exhaust-gas driven supercharger for an internal combustion engine.

In order to achieve satisfactory efficiency, the turbines and blowers used in exhaustgas driven superchargers must be adapted very precisely to the by-pass ratios and boost pressure requirements of the internal combustion engine.

According to the present invention there is provided a spiral casing for a fluid flow machine, in which there is provided at least one baffle plate adapted to slide over a, or a respective, radially inner wall or radially inner wall surface of the casing, which wall or wall surface has a spiral contour, the or each baffle plate being fixed on a baffle plate insert which is formed by a tubular pipe connection, part of which bounds the spiral flow path in the spiral casing, and which is mounted on the casing for rotation coaxially with the machine rotor, so that by rotation of the insert the or each baffle plate is displaceable in a circumferential direction as an extension of the said wall or wall surface to vary the cross-sectional flow area and the direction of flow of the fluid flow passage, the or each baffle plate being shaped and arranged so as to follow closely the spiral contour of the, or the respective, wall or wall surface, or an extension of that contour, in all circumferential positions of the baffle plate.

The desired flow conditions are thus achievable by varying the baffle plate position by rotating the insert, to vary the cross-sectional flow area of the spiral casing passage, for example the inlet passage to the rotor. There are no problems of sealing the baffle plate or plates relative to the casing. Moreover, the arrangement is not susceptible to fouling.

In order to obtain a close disposition of the or each baffle plate and the adjacent part of the casing wall or wall surface, the latter and the baffle plate guided thereon have curved cooperating surfaces which are relatively simple to manufacture; these curved surfaces enable the baffle plate or plates to be fixed rigidly to the insert and in all positions the baffle plates lie closely adjacent the casing wall.

With the aid of an appropriate drive of the baffle plate insert the flow cross-sectional area particularly required in the baffle plate area, and thereby the desired flow behaviour of the spiral casing, may be adjusted continually by simple displacement of the baffle plate or plates. This is particularly advantageous for supercharged internal combustion engines which require a favourable torque behaviour. With this the high air-charge pressure required by the engine under partial load is successfully realised.

A further important advantage of the invention is that for different rotor wheel contours, which demand different crosssections in the baffle plate region, the same spiral casings may be used by using appropriately shaped baffle plates. The advantages according to the invention have a positive effect both in application of the invention on a turbine influx casing of a radial or axial flow turbine and also on a discharge flow casing of a blower.

The or each baffle plate is advantageously releasably connected to the baffle plate insert. The space between the end of the baffle plate and, for instance, the rotor entry and also the influx angle, say, to the turbine blading, which is of great importance for the turbine efficiency, may here be varied in a very simple manner by using different baffle plate shapes. This is also important for the avoidance of vibrations.

Stock keeping for providing for machines capable of operating over a wide range is thus restricted merely to a stock of the relatively small and inexpensive baffle plates of different shapes and sizes.

The invention may be carried into practice in a number of ways but certain specific embodiments will now be described, by way of -example only, with reference to the accompanying drawing, in which: Figure 1 is a section through an intake spiral casing, -constructed according to the invention, of a radial-to-axial flow turbine with two inlet flow passages, in simplified representation, Figure 2 is a section taken along the line II-II in Figure 1, and Figure 3 is a section-through a further embodiment showing an intake spiral casing of an axial flow turbine, in a representation corresponding to that of Figure 2.

The inlet spiral casing represented in Figure 1 for a radial-to-axial flow turbine has two inlet flow passages 1 and 2 which communicate with two respective admission zones 3 and 4 which are mutually circumferentially staggered by approximately 1800, each admission zone extending around the rotor over an angle of approximately 100 . The inflow passage I extends spirally around the admission zone 4 of the inflow passage 2 and is separated from it by its radially inner wall 5. The admission zone 3 extends from adjacent the waIl 5 approximately as far as a radially inner wall 6 of the inflow passage 2, at which the coordinated admission zone 4 begins.

There are provided as an extension of the radially inner wall 5 and also of the radially inner wall 6 baffle plates 7 and 8, coordinated respectively, which are displaceable in the circumferential direction by adjustment means which, for the sake of simplicity, -is not represented here. The baffle plates 7 and 8 have expediently curved guide surfaces 9 which are adapted to slide on coordinated radially inner guide surfaces 10 of -the associated radially inner casing wall 5 and of the inside of the outer wall of the casing where it connects with the passage wall 6. To avoid flow losses in the region of overlap of the baffle plates 7 and 8 and the respective inner and outer casing walls the surfaces of the baffle plates and of the adjacent walls merge smoothly into one another.The radially inner wall 5 is tapered in the peripheral direction for this purpose in the region of overlap with the baffle plate 7.

The adjustable baffle plates 7 and 8 allow the upstream limiting edges of the admission zones 3 and 4 to be shifted forwards and backwards relative to the direction of fluid flow in an advantageous manner md thereby the torque imparted to the inflow ing fluid to be varied. Furthermore, the admission zone cross-sectional flow area may be varied by this adjustment of the baffle plate positions. In the position of the baffle plates 7 and 8 represented in Figure 1 by continuous lines, the admission zone crosssectional flow areas have their maximum dimension. The position for the minimum entrance cross-sectional flow areas is indicated by broken lines. Adjustment to virtually every value in between these maximum and minimum dimensions is possible.

The baffle plates may either be fixed in a particular adjusted position or be subjected to continual positional adjustment which can be an advantage with lorry internal combustion engines, for instance, which demand a favourable torsional behaviour.

Owing to the arrangement of the baffle plates in accordance with the invention which are displaceable in the circumferential direction, it is possible for the flow behaviour of each influx spiral to be adapted to the given conditions. As will be appreciated from Figure 1, the baffle plates 7 and 8 follow closely the spiral contours of the casing walls 5 and 6, or extensions of these contours, in all circumferential positions of the baffle plates so that in all adjusted positions the flow behaviour of the casing is favourable. Since the baffle plates 7 and 8 are located inside the spiral casing, problems of sealing relative to the exterior of the casing do not arise.

The -baffle plates 7 and 8 are fixed on a baffle plate insert mounted coaxially with the rotor axis in the machine body. As can be seen from Figure 2, -a tubular outlet pipe connection 11, in the case of a radial to axial flow turbine is employed for this purpose. The outlet pipe connection 11 is rotatably adjustably mounted on the spiral casing; it has a flange 12 fixed to it by screws, and in the present example the flange 12 is pressed firmly on to the casing by a clamping ring 13. An arrangement such as this is advantageous when merely a single adjustment of the baffle plate position is needed. It would be entirely conceivable, however, to mount the outlet pipe connection 11, with the baffle plates 7 and 8, so as to be readily rotatable and to adjust it continually during the operation of the machine by an automatic regulating device, for example with the aid of gearing or a push rod. The continual adjustment may for example be in depend ence upon an operating variable of an internal combustion engine with which the machine is associated. In the example represented the baffle plates 7 and 8 are formed integrally with the outlet pipe connection 11 as a unitary cast part. To simplify stock keeping it can be an advantage, however, to join the baffle plates releasably to the rotatable baffle plate insert. In this case, only baffle plates of different size and different curvature need be kept in stock and only particular ones are used where necessary.The possible variations offered by such a stock of baffle plates thus cover an extremely wide range of machine operating requirements.

The basic structure of the construction shown in Figure 3 corresponds generally to the embodiment described above with reference to Figures 1 and 2, and the same reference numerals are therefore used for the same parts.

In the case of an axial flow turbine, the fluid introduced into the influx spiral is directed axially of the rotor. To limit the admission zones the baffle plates therefore have end zones directed radially inwards.

In Figure 3 a boundary wall of this type of the admission zone 4 ending at the baffle plate 7 is indicated by reference numeral 14. The baffle plates together with a radial boundary wall may, in this embodiment also, be combined with the outlet pipe connection 11 which is rotatably mounted on the casing.

WHAT WE CLAIM IS: - 1. A spiral casing for a fluid flow machine, in which there is provided at least one baffle plate adapted to slide over a, or a respective, radially inner wall or radially inner wall surface of the casing, which wall or wall surface has a spiral contour, the or each baffle plate being fixed on a baffle plate insert which is formed by a tubular pipe connection, part of which bounds the spiral flow path in the spiral casing, and which is mounted on the casing for rotation coaxially with the machine rotor, so that by rotation of the insert the or each baffle plate is displaceable in a circumferential direction as an extension of the said wall or wall surface to vary the cross-sectional flow area and the direction of flow of the fluid flow passage, the or each baffle plate being shaped and arranged so as to follow closely the spiral contour of the, or the respective, wall or wall surface, or an extension of that contour, in all circumferential positions of the baffle plate.

2. A spiral casing as claimed in claim 1, in which the or each baffle plate is releasably connected to the baffle plate insert.

3. A spiral casing as claimed in claim 1 or claim 2, having more than one fluid inflow or outflow passage, and in which a respective baffle plate is provided for each such passage.

4. A spiral casing as claimed in claim 3, in which the baffle plates are provided on a common baffle plate insert.

5. A spiral casing as claimed in any one of the preceding claims, in which the or each baffle plate is provided with an end region extending radially inwards whereby the casing is adapted for a machine in which the fluid flows axially through the rotor.

6. A fluid flow machine having a spiral casing as claimed in any one of the pre

Claims

ceding claims.

7. A fluid flow machine as claimed in claim 6, in which the spiral casing defines the fluid inflow passage.

8. A fluid flow machine as claimed in claim 7, comprising the turbine of an exhaust-gas driven supercharger for an internal combustion engine.

9. A fluid flow machine as claimed in claim 6, in which the spiral casing defines the fluid outflow passage.

10. A fluid flow machine as claimed in claim 9, comprising the blower of an exhaust-gas driven supercharger for an internal combustion engine.

11. A fluid flow machine as claimed in any one of claims 6 to 10, in which the baffle plate or plates are continually adjustable in position.

12. A fluid flow machine as claimed in claim 11, in which the or each baffle plate is adjustable automatically by a regulating device, for example in dependence upon an operating variable of an internal combustion engine associated with the machine.

13. A spiral casing, or a fluid flow machine incorporating a spiral casing, substantially as specifically, described herein with reference to Figures 1 and 2 or to Figure 3 of the accompanying drawing.