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Title:
CENTRIFUGAL COMPRESSOR IMPELLER FOR A CHARGING DEVICE OF AN INTERNAL COMBUSTION ENGINE
Document Type and Number:
WIPO Patent Application WO/2020/251448
Kind Code:
A1
Abstract:
A centrifugal compressor impeller (1) is disclosed for a charging device (30) of an internal combustion engine (50). The impeller (1) comprises a hub (3), a number of full blades (5, 5', 5'') arranged on the hub (3) and being spaced in a circumferential direction (cd) of the impeller (1), and one splitter blade (7) arranged between a pressure side (8) of a first full blade (5') and a suction side (9) of a second full blade (5'') of the number of full blades (5, 5', 5''). A leading edge (11) of the splitter blade (7) is arranged closer to the pressure side (8) of the first full blade (5') than the suction side (9) of the second full blade (5''). The present disclosure further relates to a charging device (30), an internal combustion engine (50), and a vehicle (60).

Inventors:
THIYAGARAJAN JANAKIRAMAN (SE)
FREDRIKSSON CARL (SE)
PER-INGE LARSSON (SE)
Application Number:
PCT/SE2020/050558
Publication Date:
December 17, 2020
Filing Date:
June 03, 2020
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
SCANIA CV AB (SE)
International Classes:
F04D29/30; F02B37/00
Foreign References:
JPS5644495B21981-10-20
US20100254816A12010-10-07
KR20110057737A2011-06-01
GB2337795A1999-12-01
US20130195667A12013-08-01
EP2392830A12011-12-07
EP3369938A12018-09-05
Attorney, Agent or Firm:
STOLT FALLDAHL, Caroline (SE)
Download PDF:
Claims:
CLAIMS

1. A centrifugal compressor impeller (1 ) for a charging device (30) of an internal

combustion engine (50), wherein the impeller (1 ) comprises:

- a hub (3),

a number of full blades (5, 5’, 5”) arranged on the hub (3) and being spaced in a circumferential direction (cd) of the impeller (1 ), and

one splitter blade (7) arranged between a pressure side (8) of a first full blade (5’) and a suction side (9) of a second full blade (5”) of the number of full blades (5, 5’,

5”),

wherein a leading edge (1 1 ) of the splitter blade (7) is arranged closer to the pressure side (8) of the first full blade (5’) than the suction side (9) of the second full blade (5”).

2. The impeller (1 ) according to claim 1 , wherein the leading edge (1 1 ) of the splitter blade (7) is arranged at least 0.5 %, or at least 5 %, closer to the pressure side (8) of the first full blade (5’) than the suction side (9) of the second full blade (5”).

3. The impeller (1 ) according to claim 1 or 2, wherein a tip angle (ta) of the leading edge (1 1 ) of the splitter blade (7) is larger than blade angles (ba1 ) of the first and second full blades (5’, 5”) measured at meridional projections (mp1) of the leading edge (11) on the first and second full blades (5’, 5”).

4. The impeller (1 ) according to claim 3, wherein the tip angle (ta) of the leading edge (1 1 ) of the splitter blade (7) is at least 0.5 degrees, or at least 5 degrees, larger than blade angles (ba1) of the first and second full blades (5’, 5”) measured at the meridional projections (mp1) of the leading edge (11) on the first and second full blades (5’, 5”).

5. The impeller (1 ) according to any one of the preceding claims, wherein the splitter blade (7) comprises a leading section (13) comprising 30 % of the length of the splitter blade (7) measured from the leading edge (1 1 ) in an intended flow direction along the splitter blade (7), and wherein each portion of the leading section (13) is arranged closer to the pressure side (8) of the first full blade (5’) than the suction side (9) of the second full blade (5”).

6. The impeller (1 ) according to claim 5, wherein the blade angles (ba2) along the leading section (13) are larger than the blade angles (ba3) of the first and second full blades (5’, 5”) measured at meridional projections (mp) of the leading section (13) on the first and second full blades (5’, 5”).

7. The impeller (1 ) according to any one of the preceding claims, wherein the meridional projections (mp1 ) of the leading edge (1 1 ) on the first and second full blades (5’, 5”) are downstream of leading edges (15) of the first and second full blades (5’, 5”) at a position within the range of 20 % - 40 %, or within the range of 25 % - 35 %, of the length of the first and second full blades (5’, 5”) measured from the leading edges (15) in an intended flow direction along the first and second full blades (5’, 5”).

8. The impeller (1 ) according to any one of the preceding claims, wherein a shroud side (27) of the splitter blade (7) is clocked towards a shroud side (25’) of the first full blade (5’) in relation to a centre line (cl) extending between shroud sides (25’, 25”) of the first and second full blades (5’, 5”).

9. The impeller (1 ) according to claim 8, wherein the full extent of the shroud side (27) of the splitter blade (7) is clocked towards the shroud side (25’) of the first full blade (5’) in relation to the centre line (cl).

10. The impeller (1 ) according to claim 8 or 9, wherein a first distance (d1 ) between the

centre line (cl) and a shroud side (27’) of the leading edge (11) of the splitter blade (7) is greater than a second distance (d2) between the centre line (cl) and a shroud side (33) of a portion (13’) of the splitter blade (7) located downstream of the leading edge (11) at 30 % of the length of the splitter blade (7) measured from the leading edge (1 1 ) in an intended flow direction along the splitter blade (7).

1 1 . The impeller (1 ) according to claim 10, wherein the first distance (d1 ) is at least 1%, or at least 5%, greater than the second distance (d2).

12. The impeller (1 ) according to any one of the preceding claims, wherein an exit blade angle (ea1 ) of an outlet edge portion (21 ) of the splitter blade (7) is different from exit blade angles (ea2) of outlet edge portions (23) of the first and second full blades (5’, 5”).

13. The impeller (1 ) according to any one of the preceding claims, wherein an exit blade angle (ea1 ) of an outlet edge portion (21 ) of the splitter blade (7) is 0.5 - 15 degrees smaller, or 1 - 12 degrees smaller, than exit blade angles (ea2) of outlet edge portions (23) of the first and second full blades (5’, 5”).

14. The impeller (1 ) according to any one of the preceding claims, wherein the radius (r1 ) of an outlet edge portion (21 ) of the splitter blade (7) is 0.5 - 10 % greater, or 3 - 7 % greater, than the radii (r2) of outlet edge portions (23) of the first and second full blades (5’, 5”).

15. The impeller (1 ) according to any one of the preceding claims, wherein the impeller (1 ) comprises the same number of splitter blades (7) as the number of full blades (5, 5’, 5”), and wherein each splitter blade (7) of the number of splitter blades (7) is arranged between two full blades (5, 5’, 5”) of the number of full blades (5, 5’, 5”).

16. A charging device (30) for an internal combustion engine (50), wherein the charging device (30) comprises an impeller (1 ) according to any one of the preceding claims. 17. The charging device (30) according to claim 16, wherein the charging device (30) is a turbocharger.

18. An internal combustion engine (50) comprising a charging device (30) according to claim 16 or 17.

19. A vehicle (60) comprising an internal combustion engine (50) according to claim 18.

Description:
CENTRIFUGAL COMPRESSOR IMPELLER FOR A CHARGING DEVICE

OF AN INTERNAL COMBUSTION ENGINE

TECHNICAL FIELD

The present disclosure relates to a centrifugal compressor impeller for a charging device of an internal combustion engine. The present disclosure further relates to a charging device for an internal combustion engine, wherein the charging device comprises a centrifugal compressor impeller. Moreover, the present disclosure relates to an internal combustion engine comprising a charging device, as well as a vehicle comprising an internal combustion engine.

BACKGROUND

Charging devices, such as turbochargers, are used to compress air to an inlet of a combustion engine. A charging device can increase the performance and fuel efficiency of a combustion engine. With increasing demands on combustion engines, higher pressure turbochargers are being designed and manufactured. Compressor impeller noise is an unavoidable by-product of high pressure turbochargers used in modern engines.

Moreover, performance targets on combustion engines have led to the development of compressor impellers comprising splitter blades between the full blades of the compressor impeller. These types of compressor impellers can increase the operational range and overall efficiency of a charging device. However, a drawback with compressor impellers comprising splitter blades is that they generate more noise than purely full bladed impellers, and in particular regarding the exducer induced blade passing frequency (BPF) noise contribution. Moreover, the exducer induced blade passing frequency noise is not only higher but also in a frequency that is audible to the human ear (2kHz-8kHz).

Previously, the problem of noise generated by compressor impellers has been handled by providing the charging device with noise deflectors and/or damping systems surrounding the charging device. Such noise deflectors and/or damping systems can attenuate the noise generated to some extent. However, such solutions add costs, weight, and complexity to the charging device. Moreover, charging devices, such as turbochargers, generate a lot of heat during operation and must, in many cases, be cooled by air surrounding to the charging device, which puts limitations on using damping systems surrounding the charging device, and the like.

SUMMARY It is an object of the present invention to overcome, or at least alleviate, at least some of the above-mentioned problems and drawbacks.

According to a first aspect of the invention, the object is achieved by a centrifugal compressor impeller for a charging device of an internal combustion engine. The impeller comprises a hub, a number of full blades arranged on the hub and being spaced in a circumferential direction of the impeller, and one splitter blade arranged between a pressure side of a first full blade and a suction side of a second full blade of the number of full blades. A leading edge of the splitter blade is arranged closer to the pressure side of the first full blade than the suction side of the second full blade.

Since the leading edge of the splitter blade is arranged closer to the pressure side of the first full blade than the suction side of the second full blade, a compressor impeller is provided generating less noise, and in particular regarding the exducer induced blade passing frequency noise contribution. This because a more uniform pressure distribution is provided from a splitter pressure side passage and a splitter suction side passage, which in turn eliminates the half frequency harmonics that otherwise would be present downstream the compressor impeller and generate lower half-tone blade passing frequency noise.

Accordingly, due to these features, a compressor impeller is provided having a splitter blade, which provides conditions for increased operational range and overall efficiency of a charging device, while the compressor impeller generates less noise during operation.

Moreover, since the compressor impeller generates less noise during operation, the need for noise deflectors and/or damping systems surrounding the charging device is reduced, which provides conditions for a less costly, a lighter, and less complex charging device.

Accordingly, a centrifugal compressor impeller is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above- mentioned object is achieved.

Optionally, the leading edge of the splitter blade is arranged at least 0.5 %, or at least 5 %, closer to the pressure side of the first full blade than the suction side of the second full blade. Thereby, it is ensured that a compressor impeller is provided generating less noise, in particular regarding the exducer induced blade passing frequency noise contribution. Optionally, a tip angle of the leading edge of the splitter blade is larger than blade angles of the first and second full blades measured at meridional projections of the leading edge on the first and second full blades. Thereby, an even more uniform pressure distribution is provided from the splitter pressure side passage and the splitter suction side passage. As a result thereof, a compressor impeller is provided generating even less noise during operation.

Optionally, the tip angle of the leading edge of the splitter blade is at least 0.5 degrees, or at least 5 degrees, larger than blade angles of the first and second full blades measured at the meridional projections of the leading edge on the first and second full blades. Thereby, it is ensured that an even more uniform pressure distribution is provided from the splitter pressure side passage and the splitter suction side passage. As a result thereof, a compressor impeller is provided generating even less noise during operation.

Optionally, the splitter blade comprises a leading section comprising 30 % of the length of the splitter blade measured from the leading edge in an intended flow direction along the splitter blade, and wherein each portion of the leading section is arranged closer to the pressure side of the first full blade than the suction side of the second full blade. Thereby, an even more uniform pressure distribution is provided from the splitter pressure side passage and the splitter suction side passage. As a result thereof, a compressor impeller is provided generating even less noise during operation.

Optionally, the blade angles along the leading section are larger than the blade angles of the first and second full blades measured at meridional projections of the leading section on the first and second full blades. Thereby, an even more uniform pressure distribution is provided from the splitter pressure side passage and the splitter suction side passage. As a result thereof, a compressor impeller is provided generating even less noise during operation.

Optionally, the meridional projections of the leading edge on the first and second full blades are downstream of leading edges of the first and second full blades at a position within the range of 20 % - 40 %, or within the range of 25 % - 35 %, of the length of the first and second full blades measured from the leading edges in an intended flow direction along the first and second full blades. Thereby, a compressor impeller is provided where the leading edge of the splitter blade is closer to the leading edges of the first and second full blades than what is commonly used on compressor impellers comprising splitter blades. As a result, a more uniform pressure distribution is provided from the suction side and pressure side of the splitter blade passages. Optionally, a shroud side of the splitter blade is clocked towards a shroud side of the first full blade in relation to a centre line extending between shroud sides of the first and second full blades. Thereby, an even more advantageous pressure distribution is provided regarding noise generation on either side of the splitter blade. As a result thereof, a compressor impeller is provided generating even less noise during operation.

Optionally, the full extent of the shroud side of the splitter blade is clocked towards the shroud side of the first full blade in relation to the centre line. Thereby, an even more uniform pressure distribution is provided from the splitter pressure side passage and the splitter suction side passage. As a result thereof, a compressor impeller is provided generating even less noise during operation.

Optionally, a first distance between the centre line and a shroud side of the leading edge of the splitter blade is greater than a second distance between the centre line and a shroud side of a portion of the splitter blade located downstream of the leading edge at 30 % of the length of the splitter blade measured from the leading edge in an intended flow direction along the splitter blade. Thereby, an even more uniform pressure distribution is provided from the splitter pressure side passage and the splitter suction side passage. As a result thereof, a compressor impeller is provided generating even less noise during operation.

Optionally, the first distance is at least 1%, or at least 5%, greater than the second distance. Thereby, it is ensured that an even more uniform pressure distribution is provided from the splitter pressure side passage and the splitter suction side passage. As a result thereof, a compressor impeller is provided generating even less noise during operation.

Optionally, an exit blade angle of an outlet edge portion of the splitter blade is different from exit blade angles of outlet edge portions of the first and second full blades. Thereby, an even more uniform pressure distribution is provided from the splitter pressure side passage and the splitter suction side passage. This because a more uniform pressure distribution is provided especially at the outlet of the compressor impeller which reduces the exducer induced blade passing frequency (BPF) noise contribution that propagates from the compressor impeller. As a result thereof, a compressor impeller is provided generating even less noise during operation.

Optionally, an exit blade angle of an outlet edge portion of the splitter blade is 0.5 - 15 degrees smaller, or 1 - 12 degrees smaller, than exit blade angles of outlet edge portions of the first and second full blades. Thereby, it is ensured that an even more advantageous pressure distribution is provided regarding noise generation. As a result thereof, a

compressor impeller is provided generating even less noise during operation.

Optionally, the radius of an outlet edge portion of the splitter blade is 0.5 - 10 % greater, or 3 - 7 % greater, than the radii of outlet edge portions of the first and second full blades.

Thereby, an even more advantageous pressure distribution is provided regarding noise generation. This because a more uniform pressure distribution is provided especially at the outlet of the compressor impeller which reduces the exducer induced blade passing frequency (BPF) noise contribution that propagates from the compressor impeller. As a result thereof, a compressor impeller is provided generating even less noise during operation.

Optionally, the impeller comprises the same number of splitter blades as the number of full blades, and wherein each splitter blade of the number of splitter blades is arranged between two full blades of the number of full blades. Thereby, an impeller is provided having conditions for increased operational range and overall efficiency of a charging device, while the compressor impeller generates less noise during operation.

According to a second aspect of the invention, the object is achieved by a charging device for an internal combustion engine, wherein the charging device comprises an impeller according to some embodiments of the present disclosure.

Since the charging device comprises an impeller according to some embodiments, a charging device is provided having conditions for increased operational range and overall efficiency while the charging device generates less noise during operation. Moreover, the need for noise deflectors and/or damping systems surrounding the charging device is reduced, which provides conditions for a less costly, a lighter, and less complex charging device.

Accordingly, a charging device is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Optionally, the charging device is a turbocharger. Thereby, a turbocharger is provided having conditions for increased operational range and overall efficiency while the turbocharger generates less noise during operation. Moreover, the need for noise deflectors and/or damping systems surrounding the turbocharger is reduced, which provides conditions for a less costly, a lighter, and less complex turbocharger. According to a third aspect of the invention, the object is achieved by an internal combustion engine comprising a charging device according to some embodiments of the present disclosure.

Since the internal combustion engine comprises a charging device according to some embodiments, an internal combustion engine is provided having conditions for increased operational range and overall efficiency while the internal combustion engine generates less noise during operation. Moreover, the need for noise deflectors and/or damping systems surrounding the charging device is reduced, which provides conditions for a less costly, a lighter, and less complex internal combustion engine.

Accordingly, an internal combustion engine is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above- mentioned object is achieved.

According to a fourth aspect of the invention, the object is achieved by a vehicle comprising an internal combustion engine according to some embodiments of the present disclosure.

Since the vehicle comprises an internal combustion engine according to some embodiments, a vehicle is provided having conditions for increased operational range and overall efficiency while the internal combustion engine of the vehicle generates less noise during operation.

Accordingly, a vehicle is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of the invention, including its particular features and advantages, will be readily understood from the example embodiments discussed in the following detailed description and the accompanying drawings, in which:

Fig. 1 illustrates a perspective view of a centrifugal compressor impeller, according to some embodiments, Fig. 2 illustrates an explanatory diagram illustrating the positional relationship between full blades and splitter blades on a shroud side in a circumferential direction of the impeller, according to some embodiments,

Fig. 3 illustrates an explanatory diagram illustrating the positional relationship between full blades and splitter blades on a shroud side in a circumferential direction of the impeller, according to some embodiments,

Fig. 4 illustrates a front view of the centrifugal compressor impeller, according to the embodiments illustrated in Fig. 1 ,

Fig. 5 illustrates an enlarged view of a portion of the compressor impeller illustrated in Fig. 4, Fig. 6 schematically illustrates an internal combustion engine, according to some

embodiments, and

Fig. 7 illustrates a vehicle, according to some embodiments.

DETAILED DESCRIPTION

Aspects of the present invention will now be described more fully. Like numbers refer to like elements throughout. Well-known functions or constructions will not necessarily be described in detail for brevity and/or clarity.

Fig. 1 illustrates a perspective view of a centrifugal compressor impeller 1 , according to some embodiments. The centrifugal compressor impeller 1 is configured to be arranged in a charging device of an internal combustion engine and is configured to compress air to an inlet of the combustion engine by rotating in a rotational direction rd around a rotation axis ax, as is further explained herein. For the reason of brevity and clarity, the centrifugal compressor impeller 1 is in some places herein referred to as the compressor impeller 1 , or simply the impeller 1.

The impeller 1 comprises a hub 3 and a number of full blades 5, 5’, 5” arranged on the hub 3. The full blades 5, 5’, 5” of the number of full blades 5, 5’, 5” are spaced in a

circumferential direction cd of the impeller 1. Moreover, the impeller 1 comprises a number of splitter blades 7, wherein each splitter blade 7 of the number of splitter blades 7 is arranged between two full blades 5, 5’, 5” of the number of full blades 5, 5’, 5”. The splitter blades 7 are also spaced in the circumferential direction cd of the impeller 1 . Accordingly, the impeller 1 comprises the same number of splitter blades 7 as the number of full blades 5, 5’, 5”. According to the illustrated embodiments, the impeller 1 comprises seven full blades 5, 5’, 5” and seven splitter blades 7. According to further embodiments, the impeller 1 may comprise another number of full blades 5, 5’, 5” and splitter blades 7, such as three, four, five, six, eight, nine, or the like. For the reason of brevity and clarity, one splitter blade 7 of the number of splitter blades 7 is referred to in some places herein. However, all other splitter blades 7 of the number of splitter blades 7 may comprise the same shape, layout, features, functions, and advantages as the splitter blade 7 referred to. Likewise, even though one of the full blades 5, 5’, 5” may be referred to in the following, the other full blades 5, 5’, 5” may comprise the same shape, layout, features, and functions as the full blade 5, 5’, 5” referred to. The splitter blade 7 is arranged between a pressure side 8 of a first full blade 5’ and a suction side 9 of a second full blade 5” of the number of full blades 5, 5’, 5”. The first and second full blades 5’, 5” are adjacent blades 5’, 5” in the sense that no other full blade 5 or blades 5 is/are arranged between the first and second full blades 5’, 5”. However, as understood from the above described, according to the embodiments described herein, one splitter blade 7 arranged between each pair of adjacent full blades 5, 5’, 5”.

As commonly known in the technical field, splitter blades 7 are blades arranged between full blades with their upstream sides simply cut off such that their leading edges are arranged downstream of leading edges of the full blades. Common splitter blades have the same shape as the full blades with the exception that their upstream sides are cut off.

Fig. 2 illustrates an explanatory diagram illustrating the positional relationship between full blades 5’, 5” and splitter blades 7 on a shroud side in a circumferential direction cd of the impeller, according to some embodiments.

As best seen in Fig. 2, a leading edge 1 1 of the splitter blade 7 is arranged downstream of leading edges 15 of the first and second full blades 5’, 5”. Furthermore, as best seen in Fig. 2, the leading edge 1 1 of the splitter blade 7 is arranged closer to the pressure side 8 of the first full blade 5’ than the suction side 9 of the second full blade 5”, in the circumferential direction cd of the impeller. As a result, the impeller will generate less noise, in particular regarding the exducer induced blade passing frequency noise contribution.

According to the illustrated embodiments, the leading edge 1 1 of the splitter blade 7 is arranged approximately 21 % closer to the pressure side 8 of the first full blade 5’ than the suction side 9 of the second full blade 5”, in the circumferential direction cd of the impeller. According to further embodiments, the leading edge 1 1 of the splitter blade 7 may be arranged at least 0.5 %, or at least 5 %, closer to the pressure side 8 of the first full blade 5’ than the suction side 9 of the second full blade 5”, in the circumferential direction cd of the impeller. Moreover, according to the illustrated embodiments, a tip angle ta of the leading edge 1 1 of the splitter blade 7 is larger than blade angles ba1 of the first and second full blades 5’, 5” measured at meridional projections mp1 of the leading edge 1 1 on the first and second full blades 5’, 5”. The tip angle ta of the leading edge 1 1 of the splitter blade 7 may be at least 0.5 degrees, or at least 5 degrees, larger than blade angles ba1 of the first and second full blades 5’, 5” measured at the meridional projections mp1 of the leading edge 1 1 on the first and second full blades 5’, 5”. The wording“tip angle” as used herein may encompass an average blade angle of an inlet portion of the splitter blade 7, wherein the inlet portion of the splitter blade 7 may comprise a certain proportion of the splitter blade 7 at the inlet thereof, such as for example 3% of the length of the splitter blade 7 measured from the leading edge 1 1 along an intended flow direction along the splitter blade 7.

The splitter blade 7 comprises a leading section 13 comprising 30 % of the length of the splitter blade 7 measured from the leading edge 1 1 in an intended flow direction along the splitter blade 7. According to the illustrated embodiments, each portion of the leading suction section 13 is arranged closer to the pressure side 8 of the first full blade 5’ than the suction side 9 of the second full blade 5”, in the circumferential direction cd of the impeller.

Moreover, according to the illustrated embodiments, the blade angles ba2 along the leading section 13 are larger than the blade angles ba3 of the first and second full blades 5’, 5” measured at meridional projections mp of the leading section 13 on the first and second full blades 5’, 5”.

According to the illustrated embodiments, the meridional projections mp1 of the leading edge 11 on the first and second full blades 5’, 5” are located downstream of leading edges 15 of the first and second full blades 5’, 5” at a position located at 32 % of the length of the first and second full blades 5’, 5” measured from the leading edges 15 of the first and second full blades 5’, 5” in an intended flow direction along the first and second full blades 5’, 5”.

According to further embodiments, the meridional projections mp1 of the leading edge 1 1 on the first and second full blades 5’, 5” may be downstream of leading edges 15 of the first and second full blades 5’, 5” at a position within the range of 20 % - 40 %, or within the range of 25 % - 35 %, of the length of the first and second full blades 5’, 5”, measured from the leading edges 15 in the intended flow direction along the first and second full blades 5’, 5”.

Fig. 3 illustrates an explanatory diagram illustrating the positional relationship between full blades 5’, 5” and splitter blades 7 on a shroud side 25’, 25”, 27 in a circumferential direction cd of the impeller, according to some embodiments. As indicated in Fig. 3, a shroud side 27 of the splitter blade 7 is clocked, i.e. moved in the circumferential direction cd of the impeller, towards a shroud side 25’ of the first full blade 5’ in relation to a centre line cl extending between shroud sides 25’, 25” of the first and second full blades 5’, 5”. Since the shroud side 27 of the splitter blade 7 is clocked towards the shroud side 25’ of the first full blade 5’, the shroud side 27 of the splitter blade 7 is also clocked towards the pressure side 8 of the first full blade 5’ in relation to the centre line cl extending between shroud sides 25’, 25” of the first and second full blades 5’, 5”.

The centre line cl, as referred to herein, is a centre line cl extending between shroud sides 25’, 25” of the first and second full blades 5’, 5” with an equal distance to shroud sides 25’, 25” of the first and second full blades 5’, 5” along the extension of the centre line cl.

Accordingly, the shape and curvature of the centre line cl is the same as the shape and curvature of the shroud sides 25’, 25” of the first and second full blades 5’, 5”. Moreover, the centre line cl extends along a centre plane cp, which centre plane cp extends between extension planes ep1 , ep2 of the first and second full blades 5’, 5” with an equal distance to the extension planes ep1 , ep2 of the first and second full blades 5’, 5” along the extension of the centre plane cp. As understood from the above, the shape and curvature of the centre plane cp is the same as the shape and curvature of the extension planes ep1 , ep2 of the first and second full blades 5’, 5”. The shroud side of a common splitter blade would extend along the centre line cl indicated in Fig. 3. Moreover, as understood from the above, a common splitter blade would be arranged such that the extension plane thereof would extend along the centre plane cp referred to herein.

According to the illustrated embodiments, upstream portions of the shroud side 27 of the splitter blade 7 is clocked to a greater extent towards the shroud side 25’ of the first full blade 5’ than downstream portions of the shroud side 27 of the splitter blade 7. As a result thereof, a first distance d1 between the centre line cl and a shroud side 27’ of the leading edge 11 of the splitter blade 7 is greater than a second distance d2 between the centre line cl and a shroud side 33 of a portion 13’ of the splitter blade 7 located downstream of the leading edge 1 1 at 30 % of the length of the splitter blade 7 measured from the leading edge 1 1 in an intended flow direction along the splitter blade 7. According to the illustrated embodiments, the first distance d1 is approximately 45% greater than the second distance d2. According to further embodiments, the first distance d1 may be at least 1%, or at least 5%, greater than the second distance d2. Moreover, as understood from the above, due to these features, the angle distribution along the splitter blade is changed relative to a common splitter blade which would extend along the centre plane cp indicated in Fig. 3. Thereby, an even more advantageous pressure distribution is provided regarding noise generation. This is because of a more uniform pressure distribution from the splitter pressure side passage and the splitter suction side passage, which in turn eliminates the half frequency harmonics that otherwise would be present downstream the compressor impeller 1 and generate lower half-tone blade passing frequency noise. According to the illustrated embodiments, the full extent of the shroud side 27 of the splitter blade 7 is clocked towards the shroud side 25’ of the first full blade 5’ in relation to the centre line cl. According to further embodiments, only an upstream portion of the shroud side 27 of the splitter blade 7 may be clocked towards the shroud side 25’ of the first full blade 5’ in relation to the centre line cl.

Moreover, according to some embodiments of the present disclosure, a hub side of the splitter blade 7 may be clocked towards a hub side of the first full blade 5’ in relation to the centre plane cp. According to such embodiments, upstream portions of the hub side of the splitter blade 7 may be clocked to a greater extent towards the hub side of the first full blade 5’ than downstream portions of the hub side of the splitter blade 7.

Fig. 4 illustrates a front view of the centrifugal compressor impeller 1 , according to the embodiments illustrated in Fig. 1. As indicated in Fig. 4, according to the illustrated embodiments, an exit blade angle ea1 of an outlet edge portion 21 of the splitter blade 7 is different from exit blade angles ea2 of outlet edge portions 23 of the first and second full blades 5’, 5”. The exit blade angle ea1 of an outlet edge portion 21 of the splitter blade 7 may be 0.5 - 15 degrees smaller, or 1 - 12 degrees smaller, than exit blade angles ea2 of outlet edge portions 23 of the first and second full blades 5’, 5”. Thereby, an even more advantageous pressure distribution is provided regarding noise generation. This is because of a more uniform pressure distribution from the splitter pressure side passage and the splitter suction side passage, which in turn eliminates the half frequency harmonics that otherwise would be present downstream the compressor impeller 1 and generate lower half tone blade passing frequency noise. The wording“exit blade angle” as used herein may encompass an average blade angle of an outlet edge portion 21 , 23, wherein the outlet edge portion 21 , 23 may comprise a certain proportion of the blade 5’, 5”, 7 at the outlet thereof, such as for example 3% of the length of the blade 5’, 5”, 7 measured along an intended flow direction along the blade 5’, 5”, 7. The exit blade angles as defined herein may be measured relative a radial direction r of the compressor impeller 1 . Fig. 5 illustrates an enlarged view of a portion of the compressor impeller 1 illustrated in Fig. 4. According to these embodiments, the radius r1 of an outlet edge portion 21 of the splitter blade 7 indicated in Fig. 5, may be 0.5 - 10 % greater, or 3 - 7 % greater, than the radii r2 of outlet edge portions 23 of the first and second full blades 5’, 5”. Thereby, an even more advantageous pressure distribution is provided regarding noise generation. This is because of a more uniform pressure distribution from the splitter pressure side passage and the splitter suction side passage, which in turn eliminates the half frequency harmonics that otherwise would be present downstream the compressor impeller 1 and generate lower half tone blade passing frequency noise.

Fig. 6 schematically illustrates an internal combustion engine 50, according to some embodiments. The internal combustion engine 50 comprises a charging device 30. The charging device 30 comprises an impeller 1 according to the embodiments illustrated in Fig.

1 , Fig. 4, and Fig. 5. The impeller 1 is configured to compress air to an air inlet 52 of the internal combustion engine 50. According to the illustrated embodiments, the charging device 30 is a turbocharger. Thus, according to the illustrated embodiments, the impeller 1 is arranged on a shaft together with a turbine, wherein the turbine is configured to be powered by an exhaust flow of the internal combustion engine 50 so as to power the compressor impeller 1 .

According to further embodiments, the impeller 1 , as referred to herein, may be comprised in another type of charging device for an internal combustion engine 50, such as a

mechanically and/or electrically driven charging device.

The internal combustion engine 50, as referred to herein, may for example be a compression ignition engine, such as a diesel engine, or an Otto engine with a spark-ignition device, wherein the Otto engine may be configured to run on gas, petrol, alcohol, similar volatile fuels, or combinations thereof.

Fig. 7 illustrates a vehicle 60, according to some embodiments. The vehicle 60 comprises an internal combustion engine 50 according to the embodiments illustrated in Fig. 6. The internal combustion engine 50 is configured to provide motive power to the vehicle 60 via wheels 54 of the vehicle 60.

According to the illustrated embodiments, the vehicle 60 is a truck. Flowever, according to further embodiments, the vehicle 60, as referred to herein, may be another type of manned or unmanned vehicle for land or water based propulsion such as a lorry, a bus, a

construction vehicle, a tractor, a car, a ship, a boat, or the like.

It is to be understood that the foregoing is illustrative of various example embodiments and that the invention is defined only by the appended claims. A person skilled in the art will realize that the example embodiments may be modified, and that different features of the example embodiments may be combined to create embodiments other than those described herein, without departing from the scope of the present invention, as defined by the appended claims.

The compressor impeller 1 referred to herein may also be referred to as a compressor wheel 1. Therefore, throughout this disclosure, the wording“wheel” may replace the wording “impeller”. The blade angles and tip angles as defined herein may be measured relative a plane extending along the rotation axis ax of the compressor impeller 1.

As used herein, the term "comprising" or "comprises" is open-ended, and includes one or more stated features, elements, steps, components, or functions but does not preclude the presence or addition of one or more other features, elements, steps, components, functions, or groups thereof.