DE102012102186A1 - Turbine for an exhaust gas turbocharger - Google Patents

Abstract

The invention relates to a turbine for an exhaust gas turbocharger, comprising a turbine housing (12) having a receiving space (12) for a turbine wheel (16) of the turbine (10) which can rotate about an axis of rotation (18) and which has at least one feed channel (20) through which exhaust gas can flow. by means of which the exhaust gas is at least partially obliquely fed to the turbine wheel (16) to the axial direction and obliquely to the radial direction, at least one between at least two positions in the axial direction relative to the turbine housing (12) displaceable adjusting element (24) is provided which is arranged at least in some of the positions at least partially in the feed channel (20) and by means of which a through-flow of the exhaust gas flow cross section (b3) of the feed channel (20) is adjustable. According to the invention, the turbine housing (12) has at least one wall (22) delimiting the supply channel (20) at least partially and inclined obliquely to the axial direction and obliquely to the radial direction for supplying the exhaust gas obliquely to the axial direction and obliquely to the radial direction to the turbine wheel ( 16), wherein the adjusting element (24) facing one of the wall (22) and at least partially obliquely to the axial direction and obliquely to the radial direction extending end face (26), and wherein the adjustable flow cross-section (b3) in at least one of the positions at least partially limited on the one hand by the wall (22) and on the other hand by the end face (26).

Description

The invention relates to a turbine for an exhaust gas turbocharger specified in the preamble of claim 1. Art.

The DE 43 30 487 C1 discloses a turbine for an exhaust gas turbocharger, with a turbine housing. The turbine housing has a receiving space and at least one feed channel through which exhaust gas can flow. In the receiving space, a turbine wheel of the turbine is rotatably received about an axis of rotation relative to the turbine housing. By means of the feed channel, the exhaust gas is supplied to the turbine wheel. In this case, the exhaust gas is supplied by means of the feed channel at least partially obliquely to the axial direction and obliquely to the radial direction. In other words, the flow direction of the exhaust gas through the supply passage in the direction of the turbine wheel has both a component in the radial direction and a component in the axial direction.

It is an object of the present invention to further develop a turbine of the type mentioned in such a way that the turbine can be operated even more efficiently.

This object is achieved by a turbine for an exhaust gas turbocharger having the features of patent claim 1. Advantageous embodiments with expedient and non-trivial developments of the invention are specified in the remaining claims.

The turbine according to the invention comprises an adjusting element which is displaceable in the axial direction between at least two positions relative to the turbine housing and which is arranged in at least one of the positions in the feed channel and by means of which a flow cross section of the feed channel through which the exhaust gas can flow is adjustable. By means of the axially displaceable and arranged in the feed adjusting element can be adjusted variably and as needed due to the adjustment of the flow cross-section of the mass flow through the feed channel and thus of the exhaust gas flowing through the turbine and the exhaust gas back pressure. The exhaust gas is, for example, the exhaust gas of an internal combustion engine of a motor vehicle, in particular a passenger car.

Adjustable relative to the turbine housing and arranged in the feed guide vanes are not provided for adjusting the mass flow and the exhaust back pressure. Relative to the turbine housing movable, in particular rotatable about an axis of rotation vanes, inherently require a respective functional gap to avoid jamming and / or other malfunctions and to ensure their functionality. From the function columns so-called secondary flow losses result, which affect the efficiency and thus the efficient operation of the turbine.

In the turbine according to the invention, such secondary flow losses can now be avoided or at least kept very low, resulting in a particularly efficient and efficient operation of the turbine.

Also fixed relative to the turbine housing fixed or immovable and arranged in the feed guide vanes for diverting or redirecting the exhaust gas are not required in the turbine according to the invention and not provided. The diverting or discharging of the exhaust gas, so that the exhaust gas flows into the turbine wheel in a streamlined and therefore efficient manner, takes place in particular by means of the feed channel and the adjusting element, so that the exhaust gas flows against the turbine wheel obliquely to the axial direction and obliquely to the radial direction, in other words in each case having a component in the radial direction and in the axial direction.

With successive closing or reducing the flow cross section by means of the adjusting element, the exhaust gas is more and more derived or deflected in the axial direction. Conversely, with successive enlargement of the flow cross-section, the exhaust gas is deflected less strongly in the axial direction and has a more pronounced, radial component with respect to its flow direction than with a reduced flow cross-section. In other words, the flow direction with the aid of the adjusting element in its axial direction is variable. At the same time, the radial component also changes in each adjusting position of the adjusting element.

In addition, the axially displaceable adjusting element has a low complexity, which leads to a high functional performance safety even with a long service life with high exhaust gas temperatures. Furthermore, the axially displaceable adjusting element can be produced in a timely and cost-effective manner and can be displaced in the axial direction with little effort.

As a result of the adjustability of the flow cross-section, the turbine according to the invention can also be adapted efficiently to different mass flows of the exhaust gas. Thus, the turbine according to the invention is efficiently operable both at high exhaust gas mass flows and at the same time lower exhaust gas mass flows and has a high throughput parameter or a very high throughput spread and a very wide expansion ratio range.

The turbine housing has at least one at least partially the supply channel limiting and at least partially obliquely to the axial direction and oblique to the radial direction extending wall for supplying the exhaust gas obliquely to the axial direction and obliquely to the radial direction to the turbine wheel. Furthermore, the adjusting element has an end face which faces the wall and at least partially obliquely to the axial direction and obliquely to the radial direction, which preferably corresponds at least substantially with respect to its outer contour to the outer contour of the wall or is complementary. In this case, the adjustable flow cross-section is limited in at least one of the positions at least partially on the one hand by the wall and on the other hand by the end face. As a result, a particularly streamlined supply of the exhaust gas to the turbine wheel is realized in a simple, cost-effective manner, without kinematics or mechanisms, which would require function gaps, being provided and required relative to the turbine housing. This is accompanied by low costs and a particularly efficient operation of the turbine according to the invention.

In a further embodiment of the invention, by means of the displacement of the adjusting element in the axial direction, at least one bypass channel of the turbine is fluidically releasable and can be fluidly blocked. About the bypass channel, the turbine wheel of at least a portion of the exhaust gas to bypass. In other words, when the bypass passage is fluidly released by means of the adjusting element, the exhaust gas can flow through the bypass passage and thereby bypass the turbine wheel without driving the turbine wheel. For this purpose, for example, the exhaust gas is at least partially branched off from upstream of the turbine wheel, in particular from the feed channel and introduced downstream of the turbine wheel in a turbine outlet.

The adjusting element thus provides, in addition to the adjustability of the flow cross-section, a bypass functionality, a so-called blow-by functionality, by means of which the turbine and thus an exhaust gas turbocharger comprising the turbine can be operated particularly efficiently while avoiding overloading. This means that by means of the adjustment element, the derivative or deflection of the exhaust gas adjustable, the blow-by functionality available and the mass flow of the exhaust gas through the turbine is adjustable. The adjusting element thus has a very high functional integration, which keeps the number of parts, the weight and the cost of the turbine according to the invention low. The said numerous functions can be realized by means of only one actuator, by means of which the adjusting element in the axial direction is adjustable relative to the turbine housing. Respective, separate actuators for the realization of said functionalities are not provided and not required.

Due to the realization of the blow-by functionality, the turbine can be optimized in particular in terms of their operation in relatively low speed and / or load ranges of the internal combustion engine and thus at relatively low mass flows of the exhaust gas while simultaneously protected against overload in operation while high mass flows, since, in particular at very high mass flows of the exhaust gas, at least part of the exhaust gas can be conducted past the turbine wheel via the fluidically enabled bypass duct.

To realize a particularly efficient operation of the turbine is provided in a further embodiment that the turbine wheel has at least one leading edge, via which the turbine wheel of the flow cross-section flowing through the exhaust gas can be flowed. In this case, the leading edge has at least one length region which has a first angle which is different from 0 degrees in a plane which is formed extending between the axial direction and the circumferential direction and with respect to the axial direction. With the help of the leading edge formed in this embodiment, the axial flow can be absorbed, so that a low-loss total flow of the turbine wheel can be realized. In cooperation with the adjustment, it is now possible to make the axial component of the flow variable such that over the entire operating range of the exhaust gas turbocharger an optimized, that is respect. Of the prior art increased turbine efficiency can be achieved.

Preferably, the first angle is in a range of -45 degrees to +45 degrees inclusive. As a result, the turbine wheel is flowed particularly streamlined over the leading edge of the obliquely to the radial direction and obliquely to the axial direction of the turbine exhaust gas supplied, which is the efficient operation of the turbine to good.

In a further embodiment of the invention, the length range with the axis of rotation of the turbine wheel includes a second angle different from 0 degrees. The second angle may refer to an imaginary plane to which the second angle is projected. In other words, the length range, starting from a Radrücken the turbine wheel in the axial direction to the turbine outlet from radially inward to radially outward or from radially outward to radially inward.

The adjustment of the first angle and the second angle by the corresponding design of the length range represent respective degrees of freedom in order to adapt the turbine wheel and thus the turbine to different flow conditions as needed.

The length range of the leading edge may be at least partially arcuate or straight, whereby flow conditions for the exhaust gas can be adjusted.

In a further advantageous embodiment, at least one further length region of the leading edge, which extends at least substantially parallel to the axis of rotation, adjoins the length region of the leading edge. Over the further length range, the turbine wheel can in particular be flowed particularly streamlined by the exhaust gas, at least substantially in the radial direction, which is conducive to the particularly efficient operation of the turbine.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing. The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or in the figures alone can be used not only in the respectively indicated combination but also in other combinations or in isolation, without the scope of To leave invention.

The drawing shows in:

1 a schematic longitudinal sectional view of a turbine of an exhaust gas turbocharger for an internal combustion engine, with a displaceable adjusting element, which is set in a first position;

2 in sections, a further schematic longitudinal sectional view of the turbine according to 1 wherein the adjusting element is set in a second position;

3 a fragmentary schematic longitudinal sectional view of the turbine according to the 1 and 2 wherein the adjusting element is set in a third position;

4 a fragmentary schematic longitudinal sectional view of the turbine according to the 1 to 3 wherein the adjusting element is set in a fourth position;

5a C in each case a schematic side view of respective embodiments of the adjustment according to the 1 to 4 ;

6a and b in each case a detail of a schematic side view of embodiments of the adjustment according to the 1 to 5c ; and

7 a schematic side view of an embodiment of a turbine wheel of the turbine according to the 1 to 4 ,

The 1 shows a turbine 10 an exhaust gas turbocharger for an example designed as a reciprocating internal combustion engine internal combustion engine, in particular a motor vehicle. The turbine 10 includes a turbine housing 12 which is a recording room 14 includes. In the recording room 14 is a turbine wheel 16 the turbine 10 at least partially included. The turbine wheel 16 is about a rotation axis 18 relative to the turbine housing 12 rotatable.

The turbine housing 12 also has a feed channel 20 on which of the exhaust gas of the internal combustion engine can be flowed through. The feed channel 20 extends in the circumferential direction of the turbine wheel 16 over its circumference and, for example, at least substantially helically formed. The feed channel 20 is also called a volute. For a better understanding, assume a virtual plane which is perpendicular to the axis of rotation 18 of the turbine wheel 16 is trained.

Again 1 it can be seen, the turbine housing 12 one the feed channel 20 at least partially delimiting, inclined to the virtual plane wall 22 on. By means of the wall 22 this will be the feed channel 20 discharged exhaust gas or deflected the turbine wheel 16 fed. In other words, the exhaust gas flows the turbine wheel 16 at, at a certain angle, an angle α formed between the virtual plane and the flow. That the turbine wheel 16 Incoming exhaust gas has an axial component in addition to the usual radial component and peripheral component with respect to its flow direction. The larger the angle α, the greater the proportion of the axial component in the flow direction of the exhaust gas to the turbine wheel 16 ,

The turbine 10 also includes an axial direction of the turbine 10 , ie at least substantially parallel to the axis of rotation 18 movable adjusting element 24 , which is at least substantially annular. The adjusting element 24 is between one in the 1 shown first End position and one in the 4 shown, second end position relative to the turbine housing in the axial direction translationally displaceable. The end positions limit an adjustment of the adjustment 24 , wherein the end positions belong to the adjustment range. The adjusting element 24 is in the adjustment gradually or at least substantially continuously adjustable. Present in the 2 and 3 two more positions of the adjustment 24 shown which lie in the adjustment between the first end position and the second end position.

In the in the 1 shown, the first end position is the adjustment 24 partially in the feed channel 20 arranged. The adjusting element 24 has one of the wall 22 facing end face 26 on, which in terms of their outer contour at least substantially complementary to the outer contour of the wall 22 is formed and thus also runs obliquely to the axial direction and obliquely to the radial direction.

In the first end position is one of the feed channel 20 flowing through exhaust gas flow section b3 on the one hand from the wall 22 and on the other hand from the front 26 limited. As in synopsis of 1 to 4 can be seen, the flow cross section b3 by moving the adjustment 24 be set variably. In the first end position according to 1 the flow cross-section b3 is maximally narrowed or adjusted to its smallest possible value, for which reason the first end position is also in the closed position or as the 0% position of the adjusting element 24 referred to as.

By moving the adjusting element 24 can the mass flow of the exhaust gas through the turbine 10 and thus the exhaust gas back pressure can be variably adjusted. Furthermore, it is possible by means of displacement of the adjusting element 24 Also, the derivative or the deflection of the exhaust gas and thus the axial component of its flow direction, ie the angle α to set. In the closed position, the angle α has its maximum possible value.

Will the adjusting element 24 from the closed position in the direction of its second end position and thus successively from the feed channel 20 shifted, so the deflection of the exhaust gas in the axial direction and thus the axial component of the flow direction of the exhaust gas, ie, the angle α, and the flow cross-section b3 is increased. The radial component at the flow direction of the exhaust gas increases.

In the in the feed channel 20 at least partially arranged positions of the adjustment 24 form or limit the wall 22 the front side 26 a circumference circumferential and at least substantially annular nozzle 28 over which the exhaust gas is the turbine wheel 16 flows and which has the flow cross section b3.

In the closed position, the flow cross section b3 is greater than 0. This means that the nozzle 28 is not completely closed even in the closed position and also in the closed position of the adjustment 24 Exhaust the turbine wheel 16 can flow to.

To avoid unwanted leaks is a sealing element 30 , For example, an O-ring, provided on the one hand in a groove 32 the turbine 10 is received and on the other hand on the adjustment 24 is applied. This is the adjustment 24 against the turbine housing 12 sealed.

At the turbine 10 the setting of the axial flow direction, that is, the axial component used in the flow direction of the exhaust gas to avoid losses, especially in low speed and / or load ranges of the internal combustion engine, or at least to keep low. Moving the adjusting element 24 in the feed channel 20 not only reduces the flow area b3, but also changes a ratio A / r, where A is a circumferential flow area of the feed channel 20 in the circumferential direction and r the distance of the centroid of the circumferential flow cross-section A from the axis of rotation 18 designated. A change in the ratio A / r and thus of the flow cross section b3 ensures a change in the flow direction both in the radial direction and in the circumferential direction.

Again 1 can also be seen, the impeller blade of the turbine wheel 16 a leading edge 34 on, over which the turbine wheel 16 from the feed channel 20 flowing through the exhaust gas can be flowed. Relative to the axial direction, the leading edge 34 a first length range 36 and a second longitudinal region adjoining it in the axial direction 38 on, which are formed inclined to each other. The first length range 36 runs obliquely to the axial direction and obliquely to the radial direction. In the present case, the first length range runs 36 starting from a Radrücken 40 of the turbine wheel 16 in the axial direction to a turbine outlet 42 out radially outward. The adjoining, second length range 38 runs at least substantially parallel to the axial direction.

In the closed position is the second length range 38 completely from the adjustment 24 covered during the first length range 36 only partially in the radial direction of the adjusting element 24 is covered to the outside.

Preferably, the first length region closes 36 having a plane formed extending between the axial direction and the circumferential direction, a first angle which is in a range of -45 ° inclusive to + 45 ° inclusive. The first angle is especially in the 7 recognizable and _denoted by β _{φ_ax} . The axial flow _{component of} the exhaust gas and the angle β _{φ_ax} have a positive effect on the flow of the turbine wheel 16 Off and flow losses are kept very low. Preferably, the angle β _{φ_ax is different} from 0 °. As a result of the course of the first length range 36 the axial component of the flow direction of the exhaust gas can be used particularly efficiently, so that the turbine wheel 16 can be efficiently driven by the exhaust gas.

The 2 shows the adjusting element 24 in a first position, in which the entire leading edge 34 ie both the first length range 36 as well as the second length range 38 , from which exhaust gas can be flowed. As the leading edge 34 completely by means of the adjusting element 24 is released, the first position is also referred to as 100% position. Compared to the first end position (closed position) according to 1 is the adjusting element 24 from the feed channel 20 moved out, which is associated with the increase of the flow cross section b3 and the reduction of the angle α.

Like that 1 to 4 can be seen, the turbine points 10 also a bypass channel 44 on, which means of the turbine housing 12 is limited and via which the exhaust gas at least partially the turbine wheel 16 handle and thus can not drive. In the first end position (closed position), in the first position and possibly in other positions of the adjustment 24 is the bypass channel 44 fluidly obstructed, so that the bypass channel 44 can not be traversed by exhaust gas and thus the turbine wheel 16 can not be bypassed by exhaust.

The 3 shows the adjusting element 24 in a second position, in which the bypass channel 44 partially released. Thus, exhaust gas from upstream of the turbine wheel 16 in the bypass channel 44 flow in, the turbine wheel 16 deal and thereby do not drive. The bypass channel 44 directs the exhaust gas downstream of the turbine wheel 16 in the turbine exit 42 , The second position is called the 105% position of the adjustment 24 designated.

The 4 shows the adjusting element 24 in its second end position, which is also referred to as open position and 110% position. Based on 3 and 4 it is apparent that by means of the adjusting element 24 not only the flow cross section b3 and, consequently, the angle α, but also the bypass channel 44 can be adjusted with respect to its bypass flow cross section Au. As a result, a so-called blow-by functionality is provided, so that the turbine 10 optimized for operation in relatively low speed and / or load ranges of the internal combustion engine and by releasing the bypass channel 44 can be protected against overload operation. The turbine 10 thus has a very high throughput parameter or a very high throughput spread and a very wide expansion ratio range. Due to the adjustability of the bypass flow section Au of the bypass passage 44 can also be the mass flow of the bypass channel 44 flowing exhaust gas can be adjusted variably and as needed.

The 5a -C show the adjusting element 24 with different, extending in the radial direction wall thicknesses. By adjusting the wall thickness, the ratio A / r can be influenced and adjusted as needed.

The 6a shows the adjusting element 24 whose front side 26 at least essentially straight. As shown by a solid and a dashed line, the front side 26 with respect to their inclination, that is varied with respect to their course obliquely to the radial direction and obliquely to the axial direction.

The 6b shows a further embodiment of the adjusting element 24 , where the front side 26 at least partially arc-shaped and, for example, has a radius R. Due to the appropriate design of the front page 26 can the flow of the turbine wheel 16 adjusted and adapted to different flow conditions.

The 7 shows that the leading edge 34 especially in their first length range 36 relative to the at least substantially perpendicular to the axis of rotation 18 extending plane may be straight or at least substantially arcuate. Furthermore, it is possible, the leading edge 34 in a further plane having a second angle different from 0 degrees, the angle β _{r_ax is inclined} with respect to the axial direction, this further plane being designed to extend between the axial direction and the radial direction.

This creates another, optional degree of freedom. The leading edge 34 can in particular in at least one of the length ranges 36 . 38 relative to the at least substantially parallel to the axis of rotation 18 extending plane straight or at least substantially arcuate and optionally be divided into areas with radial or mixed, ie both radial and axial components. A first region B1 refers to the radial component, while a second region B2 refers to the mixed, ie radial and axial components.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 4330487 C1 [0002]

Claims (7)

Turbine for an exhaust gas turbocharger, having a receiving space ( 12 ) for one about a rotation axis ( 18 ) rotatable turbine wheel ( 16 ) of the turbine ( 10 ) turbine housing ( 12 ), which at least one exhaust gas flow-through feed channel ( 20 ), by means of which of the exhaust gas the turbine wheel ( 16 ) is at least partially obliquely fed to the axial direction and obliquely to the radial direction, wherein at least one between at least two positions in the axial direction relative to the turbine housing ( 12 ) displaceable adjusting element ( 24 ) is provided, which at least in one of the positions at least partially in the feed channel ( 20 ) is arranged and by means of which a through-flow of the exhaust gas flow cross-section (b3) of the feed channel ( 20 ), characterized in that the turbine housing ( 12 ) at least one the feed channel ( 20 ) at least partially limiting and at least partially obliquely to the axial direction and obliquely to the radial direction extending wall ( 22 ) for supplying the exhaust gas obliquely to the axial direction and obliquely to the radial direction to the turbine wheel ( 16 ), wherein the adjusting element ( 24 ) one of the walls ( 22 ) facing and at least partially obliquely to the axial direction and obliquely to the radial direction extending end face ( 26 ), and wherein the adjustable flow cross-section (b3) in at least one of the positions at least partially on the one hand by the wall ( 22 ) and on the other hand from the front side ( 26 ) is limited. Turbine according to claim 1, characterized in that by means of the displacement of the adjusting element ( 24 ) at least one bypass channel ( 44 ) of the turbine ( 10 ) over which the turbine wheel ( 16 ) is to bypass at least a portion of the exhaust gas, fluidly releasable and fluidic lockable. Turbine according to claim 1 or 2, characterized in that the turbine wheel ( 16 ) at least one leading edge ( 34 ), over which the turbine wheel ( 16 ) of which the flow cross-section (b3) flowing through the exhaust gas can be flown, wherein the leading edge ( 34 ) at least one length range ( 36 ) formed with a plane which is formed extending between the axial direction and the circumferential direction, and with respect to the axial direction of the turbine wheel ( 16 ) _{includes a} first angle (β _{φ_ax} ) different from 0 degrees. A turbine according to claim 3, characterized in that the first angle (β _{φ_ax} ) is in a range of -45 degrees inclusive to +45 degrees inclusive. Turbine according to one of claims 3 or 4, characterized in that the length range ( 36 ) with the axis of rotation ( 18 ) includes a second angle (β _{r - max} ) different from 0 degrees. Turbine according to one of claims 3 to 5, characterized in that the length range ( 36 ) of the leading edge ( 34 ) at least partially arcuate or straight. Turbine according to claim 5 or according to claim 6 in the back reference to claim 5, characterized in that the length range ( 36 ) of the leading edge ( 34 ) at least one further length range ( 38 ) of the leading edge ( 34 ), which is at least substantially parallel to the axis of rotation ( 18 ).

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