Turbine housing in turbocharger

Abstract

The present invention relates to a turbine housing (100) for use in a turbocharger, comprising a wheel housing space (120), an inlet (130), at least one volute (140), and a tongue (150) protruding from a separation wall (160). The tongue (150) is configured to guide an exhaust gas flow to an area (121) of the wheel housing space (120) in which an induction area of ​​a turbine wheel housed by the turbine housing (100) is located. At least one of the tongue (150) and the separation wall (160) is configured to allow a portion of the exhaust gas flow to pass as a leakage flow from an upstream side of at least one of the tongue (150) and the separation wall (160) to a downstream side of at least one of the tongue (150) and the separation wall (160).

Description

[Technical field]

[0001] The present invention relates to a turbine housing for use in a turbocharger and configured to house a turbine wheel, the turbine housing comprising an inlet configured to introduce an exhaust gas flow of an engine into the turbine housing, at least one volute defining a flow path of the exhaust gas flow through the turbine housing from the inlet towards a wheel housing space in the turbine housing in which a turbine wheel housed by the turbine housing is located, and a tongue protruding from a separation wall defining a portion of the at least one volute and configured to guide the exhaust gas flow into an area of ​​the wheel housing space in which an induction area of ​​the turbine wheel housed by the turbine housing is located.

[0002] Furthermore, the present invention relates to a turbocharger comprising a turbine housing as previously described herein and a turbine wheel housed by the turbine housing, the turbine wheel being positioned in a wheel housing space of the turbine housing.

[0003] Still further, the present invention relates to a method of directing engine exhaust gas flow through a turbine section of a turbocharger having a turbine housing and a turbine wheel housed by the turbine housing. [Background technology]

[0004] A turbocharger is a well-known device for supplying air at a pressure above atmospheric (supercharging pressure) to the intake of an internal combustion engine. In general, a turbocharger comprises a turbine wheel arranged and configured to be driven by the engine's exhaust gas flow. The turbine wheel is mounted on a rotatable shaft and housed in a turbine housing. A compressor wheel is mounted on the other end of the shaft and housed in the compressor housing. The compressor wheel is thus arranged to rotate with the turbine wheel. The compressor wheel provides compressed air to be delivered to the engine intake manifold. Conventionally, the shaft of a turbocharger is supported by journal and thrust bearings, including appropriate lubrication systems, located in a central bearing housing located between the turbine and compressor housings.

[0005] During operation of the turbocharger, the engine exhaust gas flow is introduced into the turbine housing through an inlet therein and flows through at least one volute-shaped volute towards the turbine wheel, which is configured to rotate under the influence of the exhaust gas flow, thereby also causing the shaft and the compressor wheel to rotate. In this way, the compressor wheel is enabled to achieve the envisaged functionality of the turbocharger, i.e. the functionality of compressing the air to be supplied to the engine.

[0006] At least one volute of the turbine housing is defined by a separation wall disposed inside the turbine housing. A tongue is disposed to protrude from the separation wall and configured to guide the exhaust gas flow to a guidance area of ​​the turbine wheel. It is practical if the tongue and the separation wall are provided as a whole. The tongue may have a generally tapered shape toward a tip thereof.

[0007] In a turbine housing of double volute design, the clearance between the tongue and the turbine wheel has a large effect on the turbine performance. This is caused by leakage at the clearance between the infeed volute, i.e. the volute into which the exhaust gas flow is introduced, and the non-infeed volute. With that in mind, it is desirable to have a small clearance. However, a drawback of a small clearance is an increase in the sound pressure level of the blade passing noise, i.e. the sound pressure level of the noise resulting from the turbine wheel blades passing through the tongue. In this regard, it is believed that part of the blade passing noise is caused by the passage of the turbine wheel blades through the separated wake region downstream of the tongue. A small gap between the tip of the tongue and the tip of each turbine wheel blade increases the blade passing noise, since a smaller gap involves a longer path of the turbine wheel blade through the separated wake region.

[0008] Given the fact that the number of turbine wheel blades is usually high, the critical turbocharger speed is relatively low, in the range of 60,000 to 110,000 rpm. The relatively low turbocharger speeds often occur at low engine load conditions, where engine noise is low enough that turbocharger noise is often not masked.

[0009] Typical examples of vehicle operations involving low engine load conditions include: - Car parking, - Driving at the parking gate (window open for ticket), - Departure / arrival in a car while people are watching, - Driving in traffic jams, - Driving indoors and / or through tunnels There is.

[0010] In "normal" vehicles, the cab is isolated from the noise and wing passing noise is not (yet) significant. However, wing passing noise is indicated as a significant design criterion for convertible cars (for both open and closed roof conditions, since the convertible roof provides poorer noise insulation). Wing passing noise is also indicated as a significant design criterion when considering the option of having one or more windows open. Summary of the Invention [Problem to be solved by the invention]

[0011] It is an object of the present invention to provide a turbine housing that is designed to reduce the level of blade passing noise without the need to apply expensive measures and without (significantly) affecting the turbine performance. [Means for solving the problem]

[0012] Aspects of the invention are set out in the accompanying independent and dependent claims. Features from the dependent claims may be combined with features from the respective independent claims as appropriate, as well as explicitly set out in the claims and as explained below in the description.

[0013] In view of the foregoing, the present invention provides a turbine housing configured for use in a turbocharger and for housing a turbine wheel, the turbine housing comprising: an inlet configured to introduce an exhaust gas flow into the turbine housing; at least one volute defining a flow path of the exhaust gas flow through the turbine housing from the inlet towards a wheel housing space in the turbine housing in which a turbine wheel housed by the turbine housing is located; and a tongue protruding from a separation wall defining a portion of the at least one volute and configured to guide the exhaust gas flow to an area of ​​the wheel housing space in which an induction area of ​​the turbine wheel housed by the turbine housing is located, the tongue and at least one of the separation wall being configured to allow a portion of the exhaust gas flow to pass as a leakage flow from an upstream side of at least one of the tongue and the separation wall to a downstream side of at least one of the tongue and the separation wall.

[0014] From the above broad definition of the turbine housing according to the invention, it follows that the invention functions at a location where the exhaust gas flow passes from the upstream side of the tongue and the separation wall to the downstream side of the tongue and the separation wall. According to the invention, at least one of the tongue and the separation wall is configured in such a way that a part of the exhaust gas flow can pass as a leakage flow from the upstream side of the tongue and the separation wall to the downstream side of the tongue and the separation wall. Thus, when the invention is put into practice, a part of the exhaust gas flow is passed between the tongue and the turbine wheel, as is usually the case, while another part of the exhaust gas flow, which is preferably a much smaller part, is passed as a leakage flow through at least one of the tongue and the separation wall, so that the performance of the turbocharger is reduced only to a minimal extent, or indeed not at all. The invention relates to a way in which at least one of the tongue and the separation wall is configured to define the leakage flow as mentioned. For the sake of clarity, it is noted that the terms "downstream" and "upstream" as used in this document are related to the direction of the exhaust gas flow.

[0015] With reference to the above description of the background of the invention, it is noted that allowing leakage flow through the tongue and / or the separating wall results in a reduction in the strength / occurrence of the separated wake region downstream of the tongue. In view of that, the present invention may be advantageous in that it may reduce the level of blade passing noise, but also in that it may reduce the level of material stress at the tip of each turbine wheel blade, so that the durability of the turbine wheel blade may be improved.

[0016] It is practical if at least one of the tongue and the separation wall comprises at least one open flow passage extending between an upstream side of at least one of the tongue and the separation wall and a downstream side of at least one of the tongue and the separation wall. During the manufacturing process of the turbine housing, such an open flow passage can be partially or integrally created in a conventional step of the manufacturing process, such as a casting step, or can be partially or integrally created in an additional step, such as a machining step.

[0017] In an embodiment of the turbine housing, the at least one open flow passage comprises a slit located in the tip portion of the tongue and opening into an area of ​​the wheel housing space in which the induction area of ​​the turbine wheel accommodated by the turbine housing is located. It is noted that in order to avoid as much as possible disturbances of the exhaust gas flow, it is advantageous if the bottom surface of the slit in the tip portion of the tongue extends generally in the direction of the exhaust gas flow defined by the at least one volute. In this respect, there are at least two options: - it may be practical if the bottom of the slit is concentric with the wheel housing space and the radius of the bottom of the slit to an axis centered in the wheel housing space is between the radius of the wheel housing space and 130% of the radius of the wheel housing space, or the base of the slit generally extends according to a tangent extending in a direction between 80° and 100° to the radius of the base of the slit as measured in the range from 60° upstream of the tip of the tongue to 20° downstream of the tip of the tongue.

[0018] In another embodiment of the turbine housing, the at least one open flow passage comprises a passage extending through one of the tongue and the separating wall. Such a passage may be provided, for example, as a hole in one of the tongue and the separating wall. The passage may be referred to as a through hole. Generally, as mentioned, the passage may be made to extend through one of the tongue and the separating wall, the passage only being accessible from the outside at its two opposite open ends and being surrounded by the material of one of the tongue and the separating wall. It may be advantageous if the passage is located in a region extending along 90° upstream of the tip of the tongue. For the sake of completeness, it is noted that the indication of the value of the angle upstream or downstream of the tip of the tongue is understood to be related to the generally circular contour of the wheel housing space.

[0019] The at least one open flow passage, whether with a slit or with a passage, may be such that the tongue of the turbine housing includes at least two open flow passages extending between the upstream side of the tongue and the downstream side of the tongue. If so desired, any suitable combination of the above mentioned options relating to the slits and passages may be applied.

[0020] The present invention encompasses a variety of turbine housing designs, including single swirl chamber designs and multiple swirl chamber designs.

[0021] Regarding the option of a turbine housing having a multiple volute design, an embodiment of the turbine housing is feasible in which the turbine housing has a double volute design and comprises a separation wall and two sets of tongues protruding from the separation wall, and at least one of the tongues and the separation wall is configured to allow a portion of the exhaust gas flow to pass as a leakage flow from the upstream side of at least one of the tongues and the separation wall to the downstream side of at least one of the tongues and the separation wall in each of the separation wall and the two sets of tongues protruding from the separation wall.

[0022] The invention further relates to a turbocharger comprising a turbine wheel and a turbine housing as described hereinbefore, the turbine wheel being located in a wheel housing space of the turbine housing. With reference to the above description of the background of the invention, it is noted that during operation of the turbocharger, the turbine wheel is driven by the exhaust gas flow of the engine, such that it is realized that the rotation of the compressor wheel, which is housed in the compressor housing, is directly related to the rotation of the turbine wheel.

[0023] Regarding the method, the present invention relates to a method of directing engine exhaust gas flow through a turbine section of a turbocharger having a turbine housing and a turbine wheel housed by the turbine housing.

[0024] The method is: - allowing the exhaust gas flow to travel through the turbine housing from an inlet of the turbine housing towards a turbine wheel; - allowing a greater portion of the exhaust gas flow to proceed along a separation wall in the turbine housing and a tongue protruding from the separation wall and to be guided by the tongue towards a guidance area of ​​the turbine wheel, while allowing a smaller portion of the exhaust gas flow to pass through at least one of the tongue and the separation wall as a leakage flow from an upstream side of at least one of the tongue and the separation wall to a downstream side of at least one of the tongue and the separation wall under the effect of a pressure difference across at least one of the tongue and the separation wall. This is accompanied by:

[0025] In practical cases, in which the tongue and / or the separating wall comprise at least one open flow passage extending between an upstream side of the tongue and / or the separating wall and a downstream side of the tongue and / or the separating wall, the method further comprises: - allowing a smaller portion of the exhaust gas flow to proceed through the at least one open flow passage.

[0026] This implies that, if at least one open flow passage comprises the aforementioned slit, the method includes a step of allowing a smaller portion of the exhaust gas flow to proceed through the slit, and, if at least one open flow passage comprises the aforementioned passage, the method includes a step of allowing a smaller portion of the exhaust gas flow to proceed through the passage.

[0027] It can be understood that various options relating to the method according to the invention may be relevant to the above-mentioned options relating to the turbine housing according to the invention and to the turbocharger according to the invention and may involve the same features or combinations of features. Thus, aspects of the above discussion and description are also applicable when the invention is described with respect to the method.

[0028] Further features and advantages of the invention become apparent from the description thereof using an exemplary, non-limiting embodiment of a turbine housing of a turbocharger.

[0029] Those skilled in the art will understand that the described embodiments of the turbine housing according to the invention are merely exemplary in nature and are not to be construed as limiting in any way the scope of protection defined in the claims. Those skilled in the art will be aware that alternative and equivalent embodiments of the turbine housing can be conceived and reduced to practice without departing from the scope of protection of the invention.

[0030] Reference is made to the figures in the accompanying drawings, which are schematic in nature and not necessarily drawn to scale, and in which identical reference numerals indicate identical or similar parts. [Brief description of the drawings]

[0031] [Figure 1] FIG. 2 is a cross-sectional view of a turbine housing of a single volute design according to an embodiment of the present invention, the turbine housing being intended to be applied in a turbocharger. [Diagram 2] FIG. 2 is a side view of a turbine wheel housed by a turbine housing. [Diagram 3] 1 illustrates a portion of an embodiment of a turbine housing including a slit positioned on a tongue of the turbine housing. [Figure 4] FIG. 11 is a diagram of a first possible design of the bottom surface of the slit. [Diagram 5] FIG. 11 shows a second possible design of the bottom surface of the slit. [Figure 6] 1 is a view of a portion of an embodiment of a turbine housing including two passages positioned on a tongue of the turbine housing. [Figure 7] FIG. 2 is a cross-sectional view of a turbine housing of a double volute design according to an embodiment of the present invention, the turbine housing being intended to be applied in a turbocharger. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Figure 1 shows a cross-sectional view of a turbine housing 100 of single volute design according to an embodiment of the invention, the turbine housing 100 being intended to be applied in a turbocharger. Figure 2 shows a side view of a turbine wheel 110 housed by the turbine housing 100. The general design of the turbine housing 100 is comparable to the general designs of commonly known turbine housings for use in turbochargers, and therefore will only be briefly described here.

[0033] The turbine housing 100 comprises a wheel housing space 120 in which a turbine wheel 110 housed by the turbine housing 100 is positioned, and further comprises an inlet 130 and a volute 140. The inlet 130 serves to introduce engine exhaust gas flow into the turbine housing 100. The volute 140 defines a flow path for the exhaust gas flow through the turbine housing 100 from the inlet 130 towards the wheel housing space 120. In FIG. 1, the direction of exhaust gas flow defined by the volute 140 is indicated by arrow F.

[0034] The turbine housing 100 also includes a tongue 150 protruding from a separation wall 160 that defines a portion of the volute 140, the tongue 150 being configured to guide the exhaust gas flow into a section 121 of the wheel housing space 120 in which the induction region 111 of the turbine wheel 110 is positioned.

[0035] In the illustrated embodiment, the tongue 150 is provided with a slit 171 that constitutes an open flow passage extending between the upstream side H of the tongue 150 and the downstream side L of the tongue 150. A portion of the turbine housing 100 including the slit 171 is shown in more detail in FIG. 3. The slit 171 is located in the tip portion 151 of the tongue 150 and opens into the area 121 of the wheel housing space 120 in which the induction area 111 of the turbine wheel 110 is located. A bottom surface 172 of the slit 171 in the tip portion 151 generally extends in the direction F of the exhaust gas flow. Due to the presence of the slit 171 in the tongue 150, the tongue 150 is configured to allow a portion of the exhaust gas flow to pass as a leakage flow from the upstream side H to the downstream side L. An advantage of implementing such leakage flow during operation of a turbocharger in which the turbine housing 100 may be included is that a reduction in the level of blade passing noise generated as the turbine wheel 110 rotates can be obtained, while the leakage flow can be small enough to avoid a significant reduction in turbocharger performance. Specifically, various relevant dimensions can be selected in the design of the turbine housing 100 such that a greater portion of the exhaust gas flow is guided by the tongue 150 to the induction region 111 of the turbine wheel 110, while a lesser portion of the exhaust gas flow passes through the slits 171 in the tongue 150 as leakage flow from the upstream side H of the tongue 150 to the downstream side L of the tongue 150 under the influence of a pressure difference across the tongue 150.

[0036] 4 shows a first possible design of the bottom surface 172 of the slit 171. In this design, the bottom surface 172 is concentric with the wheel housing space 120. The bottom surface 172 has a radius r to an axis C that is centered in the wheel housing space 120. According to practical options, the radius r as mentioned can be defined between the radius R of the wheel housing space 120 and 130% of the radius R of the wheel housing space 120.

[0037] 5 shows a second possible design of the bottom surface 172 of the slit 171. In this design, the bottom surface 172 of the slit 171 generally follows a tangent line T that extends in a direction between 80° and 100° to the radius r of the bottom surface 172, as measured in the range from 60° upstream of the tip 152 of the tongue 150 to 20° downstream of the tip 152.

[0038] FIG. 6 shows aspects of an alternative embodiment of the turbine housing 100, specifically the fact that it is possible to have an open flow path extending through the tongue 150, which is realized by means of passages 173 instead of slits 171. In the embodiment shown, the tongue 150 is provided with two passages 173 extending through the tongue 150 between the upstream side H and the downstream side L. It is practical if the passages 173 are located in a region extending along 90° upstream of the tip 152 of the tongue 150, as is the case in the example shown. Roughly speaking, the at least one passage 173 is configured to have the same function as the at least one slit 171, i.e. to allow a portion of the exhaust gas flow to pass through at least one of the tongue 150 and the separating wall 160 as a leakage flow.

[0039] In the embodiment of the turbine housing 100 shown in Figure 6, the tongue 150 comprises two open flow passages extending between the upstream side H of the tongue 150 and the downstream side L of the tongue 150. It will be clear to a person skilled in the art that in a configuration of the present invention the number of open flow passages through the tongue 150 and / or the separating wall 160 can be freely selected and that when the number is selected to be at least two, it is possible to have only slits 171, only passages 173 or a suitable combination of at least one slit 171 and at least one passage 173.

[0040] 7 shows a cross-sectional view of a turbine housing 200 in a double swirl design according to an embodiment of the present invention, where the turbine housing 200 is intended to be applied in a turbocharger. In the double swirl design, the turbine housing 200 comprises two swirl chambers 140 separated by a partition wall 141, which serve to direct the exhaust gas flow to a respective section 121 of the wheel housing space 120 in which the induction area 111 of the turbine wheel 110 is located. In this configuration, the turbine housing 200 comprises two sets of separation walls 160 and tongues 150. According to the present invention, at least one of the tongues 150 and the separation walls 160, either in one set or both sets, preferably in both sets, may be provided with at least one open flow passage extending therethrough. It will be understood that all of the features or combinations of features relating to the functionality of enabling leakage flow of exhaust gas flow as discussed above in connection with the single volute design turbine housing 100 and as shown in Figures 1 and 3-6 are equally applicable to at least one set of dual volute design turbine housings 200 in which this functionality is realized.

[0041] It will be apparent to those skilled in the art that the scope of the present invention is not limited to the examples discussed above, and that several modifications and variations thereof are possible without departing from the scope of the present invention as defined by the appended claims. In particular, combinations of specific features of the various aspects of the present invention may be made. Aspects of the present invention may be further advantageously enhanced by adding features described in connection with other aspects of the present invention. While the present invention has been illustrated and described in detail in the drawings and specification, such illustration and description are to be considered merely as illustrative or exemplary, and not as limiting.

[0042] The present invention is not limited to the disclosed embodiments. Variations to the disclosed embodiments can be understood and effected by those skilled in the art when practicing the claimed invention, from a study of the drawings, the specification, and the appended claims. In the claims, the word "comprises" does not exclude other steps or elements. The mere fact that certain measures are proposed in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Reference signs in the claims should not be interpreted as limiting the scope of the invention.

[0043] The notable aspects of the invention are summarized as follows: The invention relates to a turbine housing 100, 200 for use in a turbocharger, comprising a wheel housing space 120, an inlet 130, at least one volute 140, and a tongue 150 protruding from a separation wall 160. The tongue 150 is configured to guide the exhaust gas flow to an area 121 of the wheel housing space 120 in which a guidance area 111 of a turbine wheel 110 housed by the turbine housing 100, 200 is located. At least one of the tongue 150 and the separation wall 160 is configured to allow a portion of the exhaust gas flow to pass as a leakage flow from an upstream side H of at least one of the tongue 150 and the separation wall 160 to a downstream side L of at least one of the tongue 150 and the separation wall 160. [Explanation of symbols]

[0044] 100 Turbine housing with single volute design 200 Turbine housing with double volute design 110 Turbine Wheel 111 Turbine wheel induction area 120 Wheel housing space 121 Wheel housing space area 130 Turbine housing inlet 140 Spiral Room 141 Bulkhead 150 Tongue 151 Tip of tongue 152 Tongue tip 160 Separation Wall 171 Slit 172 Bottom of the slit 173 Passage F Exhaust gas flow direction r Radius of the bottom of the slit R Radius of wheel housing space T tangent C Axis at the center of the wheel housing space H Upstream side of tongue and separation wall L Downstream of tongue and separation wall

Claims

1. A turbine housing (100, 200) for use in a turbocharger and configured to house a turbine wheel (110), comprising: an inlet (130) configured to introduce an engine exhaust gas flow into the turbine housing (100, 200); at least one volute (140) defining a flow path for the exhaust gas flow through the turbine housing (100, 200) from the inlet (130) toward a wheel housing space (120) in the turbine housing (100, 200) in which the turbine wheel (110) housed by the turbine housing (100, 200) is positioned; a tongue (150) protruding from a separation wall (160) defining a portion of the at least one volute (140) and configured to guide the exhaust gas flow to an area (121) of the wheel housing space (120) in which an induction area (111) of the turbine wheel (110) housed by the turbine housing (100, 200) is located, wherein at least one of the tongue (150) and the separation wall (160) is configured to allow a portion of the exhaust gas flow to pass as a leakage flow from an upstream side (H) of the at least one of the tongue (150) and the separation wall (160) to a downstream side (L) of the at least one of the tongue (150) and the separation wall (160); Equipped with the at least one of the tongue (150) and the separation wall (160) comprises at least one open flow passage (171, 173) extending between the upstream side (H) of the at least one of the tongue (150) and the separation wall (160) and the downstream side (L) of the at least one of the tongue (150) and the separation wall (160); The open flow path has an upstream inlet and a downstream outlet. Turbine housing (100, 200).

2. 2. The turbine housing (100, 200) of claim 1, wherein the at least one open flow passage (171, 173) is positioned in a tip portion (151) of the tongue (150) and comprises a slit (171) opening into the area (121) of the wheel housing space (120) in which the induction area (111) of the turbine wheel (110) housed by the turbine housing (100, 200) is positioned.

3. 3. The turbine housing (100, 200) of claim 2, wherein a bottom surface (172) of the slit (171) at the tip portion (151) of the tongue (150) generally extends in the direction (F) of the exhaust gas flow defined by the at least one volute (140).

4. The turbine housing (100, 200) of claim 3, wherein the bottom surface (172) of the slit (171) is concentric with the wheel housing space (120).

5. 5. The turbine housing (100, 200) of claim 4, wherein a radius (r) of the bottom surface (172) of the slit (171) to an axis (C) centered in the wheel housing space (120) is between a radius (R) of the wheel housing space (120) and 130% of the radius (R) of the wheel housing space (120).

6. 4. The turbine housing (100, 200) of claim 3, wherein the bottom surface (172) of the slit (171) generally extends according to a tangent (T) extending in a direction between 80° and 100° to a radius (r) of the bottom surface (172) of the slit (171) as measured in a range from 60° upstream of the tip (152) of the tongue (150) to 20° downstream of the tip (152) of the tongue (150).

7. The turbine housing (100, 200) of claim 1, wherein the at least one open flow passage (171, 173) comprises a passage (173) extending through one of the tongue (150) and the separating wall (160).

8. 8. The turbine housing (100, 200) according to claim 1, wherein the tongue (150) comprises at least two open flow passages (171, 173) extending between the upstream side (H) of the tongue (150) and the downstream side (L) of the tongue (150).

9. The turbine housing (100, 200) according to any one of the preceding claims, being of single or multiple swirl design.

10. 9. The turbine housing (200) according to any one of claims 1 to 8, being of a double volute design and comprising a separation wall (160) and two sets of tongues (150) protruding from the separation wall (160), at least one of the tongues (150) and the separation wall (160) being configured to allow a portion of the exhaust gas flow to pass as a leakage flow from an upstream side (H) of the at least one of the tongues (150) and the separation wall (160) to a downstream side (L) of the at least one of the tongues (150) and the separation wall (160) in each of the separation wall (160) and the two sets of tongues (150) protruding from the separation wall (160).

11. 11. A turbocharger comprising: a turbine housing (100, 200) according to any one of claims 1 to 10; and a turbine wheel (110) accommodated by the turbine housing (100, 200), the turbine wheel (110) being positioned in the wheel housing space (120) of the turbine housing (100, 200).

12. 1. A method of directing an engine exhaust gas flow through a turbine section of a turbocharger having a turbine housing (100, 200) and a turbine wheel (110) housed by said turbine housing (100, 200), comprising: allowing the exhaust gas flow to travel through the turbine housing (100, 200) from an inlet (130) of the turbine housing (100, 200) towards the turbine wheel (110); allowing a greater portion of the exhaust gas flow to travel along a separation wall (160) in the turbine housing (100, 200) and a tongue (150) protruding from the separation wall (160) and to be guided by the tongue (150) to a guidance area (111) of the turbine wheel (110), while allowing a smaller portion of the exhaust gas flow to pass through at least one of the tongue (150) and the separation wall (160) as a leakage flow from an upstream side (H) of the at least one of the tongue (150) and the separation wall (160) to a downstream side (L) of the at least one of the tongue (150) and the separation wall (160) under the effect of a pressure difference across the at least one of the tongue (150) and the separation wall (160); Including, the at least one of the tongue (150) and the separation wall (160) comprises at least one open flow passage (171, 173) extending between the upstream side (H) of the at least one of the tongue (150) and the separation wall (160) and the downstream side (L) of the at least one of the tongue (150) and the separation wall (160), the method including the step of allowing the smaller portion of the exhaust gas flow to travel through the at least one open flow passage (171, 173); The open flow paths (171, 173) have an upstream inlet and a downstream outlet. method.

13. 13. The method of claim 12, wherein the at least one open flow passage (171, 173) comprises a slit (171) positioned at a tip portion (151) of the tongue (150) and opening into the induction area (111) of the turbine wheel (110), the method including the step of allowing the smaller portion of the exhaust gas flow to proceed through the slit (171).

14. 13. The method of claim 12, wherein the at least one open flow path (171, 173) comprises a passage (173) extending through one of the tongue (150) and the separation wall (160), the method including the step of allowing the smaller portion of the exhaust gas flow to travel through the passage (173).

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