Patent Grant
10473115
The present disclosure relates to a diffuser for a radial compressor. In the following text, the term “radial compressor” also covers what are known as mixed-flow compressors having axial flow into and radial flow out of the compressor impeller. The field of application of the present disclosure also extends to compressors with purely radial or diagonal flow into or out of the compressor impeller. Furthermore, the present disclosure relates to a diffuser for a radial compressor usable in a turbocharger, wherein the turbocharger can have an axial turbine, a radial turbine, or a mixed-flow turbine.
In a radial compressor, a fluid (e.g. air) is first of all drawn in axially via a compressor wheel connected upstream of a diffuser and is accelerated and pre-compressed in the compressor wheel. In this process, energy in the form of pressure, temperature, and kinetic energy is supplied to the fluid. At the outlet of the compressor wheel, high flow rates prevail. The accelerated, pre-compressed air leaves the compressor wheel tangentially in the direction of the diffuser. In the diffuser, the kinetic energy of the accelerated air is converted into pressure. This takes place by deceleration of the flow in the diffuser. Through radial expansion, the flow cross-section of the diffuser is enlarged. The fluid is thus decelerated and pressure is built up. In order to achieve pressure ratios that are as high as possible in a turbocharger with a radial compressor, the diffusers that are used therein can be provided with a blading. An example of a bladed diffuser is shown by German Patent Application Publication No. 102008044505 A1 (the entire disclosure of which is incorporated by reference herein). The diffusers with blading that are known from the prior art are generally configured as radial parallel-walled diffusers with blading, as shown for example in U.S. Pat. No. 4,131,389 (the entire disclosure of which is incorporated by reference herein). In order to achieve a greater compressor efficiency at a given overall pressure ratio, the flow in the diffuser can be decelerated more greatly. The flow rates in the spiral are reduced as a result, with the result that the wall friction losses decrease and the efficiency of the compressor stage is improved. The use of diffusers with radial side-wall divergence allows greater deceleration with the same overall length compared with parallel-walled diffusers.
However, the deceleration or pressure increase that is achievable in the diffuser by geometric variation for a given operating point is limited, since flow instabilities arise in the diffuser on account of boundary layer separation in the event of excessive deceleration. The limits of the stable operating range of the diffuser thus determine the position of the surge line of the compressor in the compressor characteristic map. If, instead of a parallel-walled diffuser, a diffuser with side-wall divergence is used—such a diffuser is described for example in PCT International Publication No. WO 2012/116880 A1 (the entire disclosure of which is incorporated by reference herein)—although the efficiency increases with identical compressor pressure ratios, at the same time the surge line moves toward greater mass flows at a given compressor pressure ratio compared with the compressor with a parallel-walled diffuser. This effect is not desired. The width of the compressor characteristic map is thereby reduced, and the usability of the compressor stage for applications in a turbocharger is thereby limited. One solution is to fluidically connect a diffuser duct portion of a bladed diffuser to an annular duct via pressure equalizing openings in order to allow pressure equalization between individual diffuser passages of the diffuser which are formed by adjacent diffuser blades. However, in this solution using pressure equalizing openings, the problem of the annular duct and/or the individual pressure equalizing openings becoming clogged can arise (e.g. on account of residues and deposits from compressor cleaning or by particles which are found in oil-containing intake air). This has a negative effect on the surge line of the compressor and, in extreme cases, can result in an engine connected to the diffuser no longer being able to be operated.
One object of the present disclosure is developing a bladed diffuser having radial side-wall divergence for a radial compressor where the efficiency compared with parallel-walled diffusers is improved and, at the same time, the flow in the diffuser is stabilized, in order to improve the pumping behavior of the compressor. A further object of the present disclosure is to avoid or reduce premature boundary layer separation at the diffuser blades and at the side walls of the diffuser in individual diffuser passages as a result of excessive deceleration. Furthermore, another object of the present disclosure is to ensure that the operation of the diffuser is not impaired even in the case of possible contamination on account of deposits and residues from oil-containing intake air from the compressor. These and other objects may be achieved by the features of the diffusers described and claimed in the present disclosure.
In particular, the foregoing objects (among others) may be achieved by a diffuser for a radial compressor, wherein the diffuser comprises a diffuser duct portion which is formed by a first side wall and a second side wall, wherein the first side wall and the second side wall are arranged so as to diverge at least partially from one another in a direction of flow. Furthermore, the diffuser may comprise a blade ring having a number of blades, wherein the blades are arranged at least partially in the diffuser duct portion, wherein each of the blades has a pressure side and a suction side, and wherein the pressure side and the suction side of each blade are delimited by a blade leading edge and by a blade trailing edge of the respective blade. Furthermore, the diffuser may comprise a number of pressure equalizing openings which are incorporated into at least one of the first and second side walls of the diffuser duct portion in a region where the first and second side walls diverge from one another, wherein each of the pressure equalizing openings is arranged between the pressure side of one blade and the suction side of an adjacent blade of the blade ring. Furthermore, the diffuser may comprise a first annular duct, which is arranged behind the pressure equalizing openings, wherein the first annular duct is fluidically connected to the diffuser duct portion via at least two of the pressure equalizing openings, such that a number of diffuser passages of the diffuser are fluidically connectable together, each diffuser passage being a region between two adjacent blades of the blade ring in the diffuser duct portion.
One basic concept underlying the present disclosure is that, in a diffuser having side-wall divergence, the bladed diffuser duct portion of the diffuser may have pressure equalizing openings which are incorporated into at least one of the two side walls of the diffuser duct portion, wherein the diffuser duct portion of the diffuser is fluidically connected to a first annular duct and wherein the first annular duct is connectable to a pressure plenum via a connecting duct, such that a fluid can flow from the pressure plenum into the first annular duct in order that the first annular duct is flushed with the fluid.
This entails the advantage that, via the fluid in the form of a flushing medium which flows from the pressure plenum into the first annular duct in order to flush the annular duct with fluid, possible deposits and residues from coking by oil-containing intake air, which could clog the annular duct and the pressure equalizing openings, are flushed from the annular duct and thus also from the pressure equalizing openings. In this way, it is possible to prevent the pressure equalizing openings from being closed by deposits and the volume of the annular duct being greatly reduced.
A further advantage of the present disclosure is that pressure equalization can take place in the annular duct, thus counteracting flow separation at the diffuser blades in the bladed diffuser duct portion on account of excessive flow deceleration and thus neutralizing flow separation.
A further advantage of the present disclosure is that, as a result of the pressure equalization which takes place in the annular duct, pressure equalization also takes place at the same time between the individual passages of the diffuser in the diffuser duct portion, this in turn resulting in a reduction in the irregular loading of individual diffuser passages in the diffuser duct portion. A “diffuser passage” is defined here as being a space or a portion between two adjacent diffuser blades. Irregular loading of individual diffuser passages in the diffuser duct portion arises, by way of example, on account of asymmetries of the compressor housing and air intake port of the compressor, and the non-rotationally symmetrical pressure field brought about thereby, in the outflow region of the diffuser, on account of manufacturing and installation tolerances, and on account of transient flow effects. Pressure equalization makes it possible to neutralize incipient instabilities in individual diffuser passages, in that the stability reserves of other diffuser passages that are still running in a stable manner are used. As a result, the stable working range of the diffuser, and of the compressor, is expanded overall until all of the diffuser passages pass into the region of unstable flow. One consequence of this is that the surge line of the compressor is displaced toward smaller volume flows and enlarges the usable region of the compressor characteristic map.
In one embodiment according to the present disclosure, the pressure plenum is connected to a fluid source, wherein the fluid source is configured to provide fluid for the pressure plenum.
In one embodiment according to the present disclosure, the fluid source is configured as a charge air cooler, wherein the charge air cooler is configured to provide fluid, and wherein the fluid is introducible into the pressure plenum from the charge air cooler. Here, it should be noted that the fluid from the charge air cooler, which is in the form, for example, of flushing medium, is also or additionally usable for cooling a compressor wheel of the radial compressor.
In one embodiment according to the present disclosure, a filter system for cleaning the fluid is installed between the pressure plenum and the fluid source.
In one embodiment according to the present disclosure, a turbocharger arrangement is provided, which comprises a diffuser.
In one embodiment according to the present disclosure, the first annular duct is incorporated in one of the two side walls of the diffuser duct portion.
In one embodiment according to the present disclosure, the number of pressure equalizing openings which are incorporated into at least one of the two side walls of the diffuser duct portion are arranged in a region of the respective side wall in which the first side wall and second side wall are arranged so as to diverge at least partially from one another in the direction of flow.
In one embodiment according to the present disclosure, the pressure equalizing openings are each configured as one of a bore and a slot. Alternatively, a pressure equalizing opening could also be formed from several individual bores or slots.
In one embodiment according to the present disclosure, the orientation of each of the pressure equalizing openings in the respective side wall of the diffuser duct portion is determined by a setting angle, which is defined as the setting angle of the respective pressure equalizing opening to that face of the respective side wall that faces the diffuser duct portion.
In one embodiment according to the present disclosure, the first annular duct is subdivided by separating means into a number of individual, mutually separate duct sub-regions of the first annular duct. In this way, pressure equalization between diffuser passages within a duct sub-region can be locally limited.
In one embodiment according to the present disclosure, each duct sub-region of the first annular duct comprises at least two pressure equalizing openings. Here, it should generally be noted, however, that the pressure equalizing openings do not have to be an integral constituent of the annular duct.
In one embodiment according to the present disclosure, at least one second annular duct is incorporated in one of the side walls with pressure equalizing openings of the diffuser duct portion, such that the diffuser passages of two nonadjacent blades of the blade ring are fluidically connectable together.
In one embodiment according to the present disclosure, the first or second side wall of the diffuser duct portion is configured as a diffuser plate, wherein the number of pressure equalizing openings and at least one annular duct are incorporated in the diffuser plate.
One embodiment of the present disclosure comprises a radial compressor having a diffuser.
A diffuser according to the present disclosure is described in the following text by way of exemplary embodiments which are explained in more detail by way of drawings, in which:
In the following description, identical reference signs are used for similar and/or similarly acting parts:
While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the concepts of the present disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives consistent with the present disclosure and appended claims.
In the following description, numerous specific details, such as types and interrelationships of system components, are set forth in order to provide a more thorough understanding of the present disclosure. It will be appreciated, however, by one skilled in the art that embodiments of the disclosure may be practiced without such specific details. Those of ordinary skill in the art, with the included descriptions, will be able to implement appropriate functionality without undue experimentation.
References in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etcetera, indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
The first annular duct 10 can be integrated directly, as a constituent of the side wall 3, 4, into one or both of the side walls 3, 4, so long as the annular duct 10 is installed behind the pressure equalizing openings 7, 7′. However, embodiments in which a respective annular duct is installed in each of the side walls 3, 4 would also be possible, said annular duct being fluidically connected (not illustrated) to the diffuser duct portion 2 via pressure equalizing openings 7, 7′.
In the embodiment in
However, the annular duct 10 (and thus also the pressure equalizing openings 7, 7′) could also be a constituent of the second side wall 4 or of the first side wall 3 of the diffuser duct portion 2 (this not being illustrated), and so the third side wall 15 could be dispensed with. The pressure equalizing openings 7, 7′ and the first annular duct 10 would then be incorporated in a component manufactured in one piece, wherein one face of this component would form the first side wall 3 or the second side wall 4. In this embodiment, too, the annular duct 10 would be arranged behind the pressure equalizing openings 7, 7′, however, so that the annular duct 10 is fluidically connected to the diffuser duct portion 2 via the pressure equalizing openings 7, 7′ and with the result that, at the same time, the number of flow cross sections of the diffuser 1 are fluidically connected together. In the embodiment in
Each of the pressure equalizing openings 7, 7′ which are incorporated into at least one of the two side walls 3, 4 of the diffuser duct portion 2 are arranged, in the embodiment shown in
In this case, the pressure equalizing openings 7, 7′ can each be configured as a bore and/or as a slot. Alternatively, however, a pressure equalizing opening could also be made up of a plurality of openings, i.e. for example of a plurality of individual bores or slots or a combination of both shapes. However, some other form of the pressure equalizing opening in the diffuser 1 could also be realizable. In
The second side wall 4 of the diffuser 1 is a constituent of a diffuser plate 12 in the embodiment of the diffuser 1 that is illustrated in
The individual pressure equalizing openings 7, 7′ are configured as slots in
In the embodiment of the diffuser 1 illustrated in
In the embodiment in
The pressure in the first annular duct 10 should be minimally higher in terms of value than a pressure which is formed in the diffuser duct portion 2, in order that intended pressure equalization in the first annular duct 10 is not impaired. Furthermore, a situation should be avoided in which a large amount of air is blown out of the first annular duct 10 into the diffuser duct portion 2. As a result of the geometric design of the connecting duct 30, the pressure at which the flushing agent is transported in the connecting duct 30 to the first annular duct 10 can be set. As a result of the flushing agent conveyed into the first annular duct 10 at a determined, set pressure, the first annular duct 10 is flushed with flushing agent. Flushing prevents soiling of the first annular duct 10 and clogging of the pressure equalizing openings 7, 7′, 7″, 7′″ by deposits of oil-containing particles, as can be contained in the air from the diffuser duct portion 2. In order that the flushing medium can be introduced into the first annular duct 10 at a defined pressure, a defined pressure should already be formed in the fluid source 35 and in the pressure plenum 31, said defined pressure being greater in terms of value than a pressure in the first annular duct 10 and a pressure in the diffuser 2. The pressure in the fluid source 35 should in this case be greater in terms of value than a pressure in the pressure plenum 31 and a pressure in the annular duct 10 and a pressure in the diffuser duct portion 2. The fluid source 35 can in this case also be configured as a compressed air network. The fluid source 35 can in this case also comprise a plurality of fluid sources which provide fluid for the pressure plenum 31. In addition, in the embodiment in
While certain illustrative embodiments have been described in detail in the drawings and the foregoing description, such an illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only illustrative embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected. There are a plurality of advantages of the present disclosure arising from the various features of the systems, apparatus, and methods described herein. It will be noted that alternative embodiments of the systems, apparatus, and methods of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of systems, apparatus, and methods that incorporate one or more of the features of the present disclosure and fall within the spirit and scope of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2014 119 558 | Dec 2014 | DE | national |
| 10 2014 119 562 | Dec 2014 | DE | national |
This application is a continuation of PCT International Patent Application No. PCT/EP2015/081037, filed on Dec. 22, 2015, which claims the benefit of German Patent Application No. 102014119558.2, filed on Dec. 23, 2014, and of German Patent Application No. 102014119562.0, filed on Dec. 23, 2014. The entire disclosures of the foregoing applications are expressly incorporated herein by reference.
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| Number | Date | Country | |
|---|---|---|---|
| 20170284401 A1 | Oct 2017 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2015/081037 | Dec 2015 | US |
| Child | 15630938 | US |
