Patent Application
20070140846
An exhaust gas turbine having a cleaning device is disclosed as it relates to exhaust gas turbines for internal combustion engines.
Exhaust gas turbines, in particular in exhaust gas turbochargers, are used in conjunction with an internal combustion engine. The exhaust gas from the internal combustion engine is utilized as a driving medium for driving the turbine wheel. The turbine wheel is connected by means of a shaft to the compressor wheel which compresses the intake air which is supplied to the internal combustion engine. The exhaust gas guided to the guide blades of the exhaust gas turbine contains impurities resulting from incomplete combustion and impurities in the fuel. The quantity of impurities which the internal combustion engine discharges with the exhaust gas is highly dependent on the fuel which is used. If a dirty fuel is used, for example heavy diesel oil, then considerable quantities of impurities can be discharged with the exhaust gas.
The impurities in the exhaust gas lead to depositions on the turbine rotor blades and in particular on the guide elements (guide blades) of the guide device (nozzle ring) which are arranged in the flow duct upstream of the turbine blades.
In order to be able to ensure permanently failure-free operation with full performance, the contaminated parts, that is to say that turbine blades and in particular the guide elements of the guide device, must be freed from depositions at regular intervals by means of a cleaning liquid injected into the exhaust gas flow in the flow duct.
An axial turbine having a device for introducing a cleaning medium into the blade duct is known from CH 335 901. Said document discloses a nozzle carrier which guides the cleaning medium, is provided with outlet points, forms a ring, and is arranged radially outside the inflow duct at the inlet into the blade duct of the turbine and at a distance from the guide blade carrier. The distance to the guide blade carrier and the radially external arrangement of the nozzle carrier ensure that no thermal stresses are generated between the nozzle carrier and the guide blade carrier. The nozzle carrier and the nozzles which introduce the cleaning medium into the flow duct are additionally arranged at a distance from the guide blades in order to ensure that the cleaning medium can be distributed in the flow before it impinges on the guide blades. Said spacing from the guide blades can however have the result that the cleaning medium is dissolved in the flow to too great a degree, and it is therefore not possible to provide a cleaning action which even comes close to that of a focused jet. Targeted cleaning of the guide elements therefore cannot be provided.
A similar device is known from DE 2 008 503. A cleaning liquid is again injected into the flow at a great distance and radially from the outside of the flow duct.
A device for cleaning the turbine blades of an exhaust gas turbocharger is known from DE 35 15 825, in which device water is injected into the exhaust gas flow upstream of the guide elements by means of water injection nozzles. The water is conducted from a high pressure water supply via a water line to the individual water injectors which then deliver the suitable flow of droplets for cleaning. The water line, water injectors and injection nozzles are arranged outside the housing parts which form the flow duct, and are provided as separate components.
An axial turbine with a simplified cleaning device provides a uniform distribution of water over the guide device of the exhaust gas turbine.
An exhaust gas turbine is disclosed. Openings for injecting a cleaning liquid are arranged, in the region of the flow duct, in the flow direction directly upstream of the guide elements of the guide device, with the openings being arranged in the radially inner side of the annular flow duct.
As a result of the injection taking place from the radially inner side, the cleaning liquid is better distributed over the radial height of the guide elements. The flow, which is sucked in by the fast-rotating turbine blades arranged further downstream and has a radially outwardly directed component already in the region upstream of the guide device, guides the cleaning liquid injected radially from the inside to the guide elements.
In addition, if injection takes place from the radially inner side, the cleaning liquid can be supplied centrally in the region of extension of the turbine shaft. The injection from the radially inner side can be advantageously used in new-generation exhaust gas supply housings without a spherical cap. In housings of said type, the flow duct merges from a circular cross section of the exhaust gas supply tube directly into an annular flow duct without a concentric, spherical-cap-shaped inner wall. The region in the extension of the turbine axis is easily accessible.
In addition, if the injection takes place from the radially inner side, it is generally the case that no tubes which are complex to relocate are required in the radially outer region of the turbine housing, which could otherwise lead to insulation losses in terms of the insulation of the housing. Each element in the region of the insulation can, as a heat bridge, conduct undesired heat from the inner region of the turbine to the outside.
In order to distribute the cleaning liquid from the central supply along the periphery of the flow duct ring, the openings are connected to an encircling cavity for the cleaning liquid.
The cavity which is arranged so as to be rotationally symmetrical about the rotational axis of the exhaust gas turbine serves to uniformly distribute the cleaning liquid over the entire guide device. The openings for injecting the cleaning liquid arranged upstream from or at the same level as the guide device serve to direct the cleaning liquid directly at those guide elements which are contaminated to the greatest degree, making more effective cleaning possible. In addition, the surrounding turbine housing, which delimits the flow duct, is loaded to a lesser degree if the relatively cold cleaning liquid does not come into contact with the hot housing walls or comes into contact with the housing walls to only a small extent.
The injection advantageously takes place in the axial direction and/or in the direction of rotation in the region of the stagnation line, as close as possible to the stagnation point itself. The injection pressure can therefore be reduced, since the cleaning liquid is injected into the stagnated flow against a relatively low flow resistance.
In the following, different embodiments of the cleaning device according to the invention are explained in more detail on the basis of figures, in which:
FIGS. 5 to 7 are detailed illustrations of a second variant of the fourth exemplary embodiment according to
An exemplary cleaning device comprises a cavity which is arranged cylindrically or annularly around the central axis of the exhaust gas turbine, and openings which are connected to said cavity directly or via feed lines and open out into the flow duct. The cavity is connected via a feed line to a pump. The latter pumps the cleaning liquid (water, if required provided with an additive for improving the cleaning action) at high pressure (up to 40 bar) into the cavity and through the openings into the flow duct. The pressure distribution in the cavity and the distribution of the openings along the periphery of the flow duct ensure a uniform distribution of the cleaning liquid and therefore uniform cleaning of the guide device.
The cavity can be integrally formed in a housing part which delimits the flow duct or can be formed so as to be thermally decoupled in an additional separate component, a hollow ring, which likewise at least partially delimits the flow duct. If the cavity is arranged in one of the housing parts present in conventional exhaust gas turbines, this has the advantage that it is not necessary for an additional component to be provided for cleaning. On the other hand, a separate component can be easily retrofitted in an existing exhaust gas turbine or can be easily replaced if excessively worn or in the event of a fault.
Since the cleaning liquid is injected into the flow duct in the flow direction of the exhaust gas flow directly upstream or at the level of the guide device (nozzle ring), it is possible to prevent too much of the relatively cold cleaning liquid from coming into contact with the hot turbine housing parts which for the most part delimit the flow duct. It is therefore possible to prevent cold shock, which adversely affects the service life of the housing parts, as the guide device is cleaned. In return, it can occur that the cleaning liquid is not uniformly distributed in the flow before it reaches those surfaces of the guide elements (guide blades) of the guide device which are exposed to the flow. It is therefore advantageous if at least one opening, through which the cleaning liquid is sprayed onto the respective guide element, is provided for each of the guide elements.
The openings, cavity and if appropriate the feed lines from the cavity to the openings can also be formed by two-part or multi-part components. It is possible, for example, for a flat disk-shaped element to be connected to a T-shaped disk element having a tubular feed line in the centre in such a way that a central cavity between the element and the T-shaped disk and an encircling gap which leads radially outward are formed, or that, with corresponding surface profiling either of the flat element or of the T-shaped disk, duct-shaped feed lines to the radially outer edge are formed. The cleaning liquid is again sprayed into the flow duct through the encircling gap or the openings at the end of the supply ducts.
FIGS. 1 to 7 schematically show a section, running along the rotational axis (dash-dotted line) of the turbine wheel 3, through an exhaust gas turbine with a different embodiment of the cleaning device according to the invention in each case. The figures show that region of the flow duct 2 in which the exhaust gas is guided in the direction of the arrow via the guide device (nozzle ring) 4 to the rotor blades 31 of the turbine wheel. Radially outer parts 11 and radially inner parts 12 of the turbine housing are illustrated in outline.
The first exemplary embodiment of the cleaning device as exemplified in
When the guide device is cleaned, the cleaning liquid is pumped at high pressure via the feed lines 54 into the cavity 52. The cleaning medium is distributed in the cavity, fills the latter and then enters the flow duct 2 via the openings 51. The manner in which the cleaning liquid is to be injected into the flow duct can be set by means of the shape, the size and the alignment of the openings. As already mentioned, as a result of the arrangement according to the invention of the openings directly upstream of the guide device, the cleaning liquid impinges primarily on the guide device and does not come into contact with the housing parts which delimit the flow duct further upstream.
In the second exemplary embodiment of the cleaning device as exemplified in
Said second exemplary embodiment of the cleaning device is characterized by a very simple and compact design, and permits an absolutely uniform distribution of water in a very simple manner. Said third embodiment is additionally very particularly suitable for being retrofitted to existing exhaust gas turbines. The previous guide device is simply substituted with a guide device according to the invention which, in addition, has a cavity with openings toward the flow duct. Depending on requirements and on the supply possibilities for the cleaning liquid, the cavity can be integrated here into the radially inner housing part or in the radially outer housing part of the guide device, or even in both.
In the third exemplary embodiment of the cleaning device as exemplified in
In the fourth exemplary embodiment of the cleaning device as exemplified in FIGS. 4 to 7, the cavity 52 for receiving the cleaning liquid is again arranged centrally and at a certain radial distance from the flow duct. The cavity 52 and the duct-like feed lines 53 to the openings 51 are formed between two elements 56 and 57 which are held together by fastening means or in some other way.
In the first variant as exemplified in
In the second variant, the feed line ducts 53 from the cavity 52 to the openings 51 are formed by a plate 59 which is arranged between the two elements 56 and 57 and are provided with grooves. In the variant illustrated in
In order to utilize this effect of the stagnation region, the openings 51 are advantageously to be arranged in each case directly upstream of the stagnation point, at most half of a guide blade length upstream of the stagnation point of the guide element. It can be assumed that there is a reduced flow speed in this region, so that the pressure of the injection can be reduced as mentioned.
The openings 51 are advantageously situated in the peripheral direction on the respective stagnation line 22, that is to say that streamline which leads directly into the stagnation point. This ensures that the liquid is conveyed by the flow to both sides of the stagnation point and therefore to both sides of the flow profile of the guide elements.
It will be appreciated by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted. The scope of the invention is indicated by the appended claims rather than the foregoing description and all changes that come within the meaning and range and equivalence thereof are intended to be embraced therein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 04405513.5 | Aug 2004 | EP | regional |
This application claims priority under 35 U.S.C. §119 to EP Application 04405513.5 filed in European Patent Office on 16 Aug. 2004, and as a continuation application under 35 U.S.C. §120 to PCT/CH2005/000465 filed as an International Application on 10 Aug. 2005 designating the U.S., the entire contents of which are hereby incorporated by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CH05/00465 | Aug 2005 | US |
| Child | 11703741 | Feb 2007 | US |
