DE102012022647A1 - Exhaust gas turbocharger for lifting cylinder internal combustion engine of motor vehicle, has portion limited by spine in axial direction, where spine comprises blade elements partially arranged in portion for compressing blade - Google Patents

Abstract

The turbocharger (10) has a shaft (20) rotatably connected to a compressor wheel (22). A rotor (18) comprises housing elements (14, 16), and is rotatably mounted and linked to the housing elements about a rotational axis (24). The compressor wheel is partially accommodated in one of housing elements in radial direction. A portion (36) is limited by a wheel spine (34) of the compressor in axial direction. The wheel spine comprises blade elements partially arranged in the portion for compressing an air exhibiting blade.

Description

The invention relates to an exhaust gas turbocharger for an internal combustion engine according to the preamble of patent claim 1.

Such exhaust gas turbochargers for internal combustion engines are the DE 10 2007 027 869 B4 , of the DE 10 2008 049 250 A1 , of the DE 33 13 484 A1 as well as the DE 10 2006 029 542 A1 to be known as known. The respective exhaust-gas turbocharger has a rotor, which comprises a shaft and a compressor wheel connected in a rotationally fixed manner to the shaft. Furthermore, the exhaust gas turbocharger has a bearing housing element as the first housing element. On the bearing housing element, the rotor is rotatably mounted about an axis of rotation relative to the bearing housing element. In addition, the exhaust gas turbocharger on a compressor housing element as a second housing element, which is connected to the bearing housing element. The compressor wheel is at least partially received in the compressor housing element.

Furthermore, the exhaust gas turbocharger has a region which is delimited at least in regions by at least one of the housing elements in the radial direction and by a wheel back of the compressor wheel in the axial direction. In this area, the shaft opens into the compressor housing element.

In order to lubricate and / or cool the bearing of the rotor on the bearing housing element, a lubricant is used, for example in the form of lubricating oil. In order to prevent lubricant from entering the compressor housing element from the bearing housing element between the shaft and the bearing housing element, at least one sealing element, for example a shaft seal, is used to seal the shaft against at least one of the housing elements.

Nevertheless, it has been found that at certain operating points of the internal combustion engine, in particular at idle, in which the exhaust gas turbocharger or its rotor has low speeds and thus little pressure buildup takes place in the compressor, come to a transfer of lubricant in the compressor housing element, since in these small Speeds the sealing concept between the shaft and the at least one corresponding housing element does not work or only insufficient.

As a result, there is a so-called compressor oils, in which lubricant passes in by means of the compressor to be compressed and the internal combustion engine to be supplied air. Due to unfavorable pressure conditions between the area behind the compressor wheel and the bearing housing element of this compressor oils can be further enhanced.

The compressed air promotes the lubricant in combustion chambers of the internal combustion engine, where it is burned with air and fuel. However, the increased by the compressor oils proportion of lubricant in the combustion chambers causes compared to operating points in which it does not come to compressor oils, other raw emissions of the internal combustion engine and deposits on components such as valve seats or injectors. The components can then be affected or even damaged as a result of these deposits in their respective function.

In order to compensate for the increased raw emissions, a correspondingly increased performance of exhaust aftertreatment devices is required, which in turn results in an increased consumption of fuel and / or reducing agent for de-stemming exhaust gas of the internal combustion engine.

The deposits due to the compressor oil can also have a negative effect on the life of the internal combustion engine with the exhaust gas turbocharger and the exhaust aftertreatment device. As a result of the lubricant entry into the compressor housing element and the efficiency of the exhaust gas turbocharger is affected, which may lead to a drop in boost pressure. This is particularly critical in so-called highly supercharged internal combustion engines. Here, the lubricant clogged by high charge air temperature in the compressor coil / compressor housing of the turbocharger and its diffuser, whereby the flow resistance increases and as a result, the boost pressure and the pressure build-up are reduced.

In order to avoid the compressor oils, ie the passage of lubricant from the bearing housing element in the said area or at least to keep low, attempts are made to take known from the cited prior art countermeasures. In the DE 33 13 484 A1 a vent of the bearing housing element is provided in the vicinity of the compressor wheel. In the DE 10 2006 029 542 A1 the design of the compressor oils should be counteracted by arranging a mounting surface and a gap surface in one plane. In the DE 10 2008 049 250 A1 is proposed a complex Ölabweisblech. Also the DE 10 2007 027 869 B4 proposes a correspondingly expensive sealing system.

The known countermeasures for avoiding the compressor oils are very expensive and lead to a high complexity as well optionally to a high number of parts of the exhaust gas turbocharger.

It is therefore an object of the present invention to develop such an exhaust gas turbocharger for an internal combustion engine of the type mentioned that the described compressor oils can be kept at least low in a particularly simple manner.

This object is achieved by 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.

In order to provide an exhaust gas turbocharger for an internal combustion engine specified in the preamble of claim 1 species, in which the described compressor oils can be kept at least low in a particularly simple manner, it is inventively provided that the Radrücken with an at least partially arranged in the area blade elements for Compressing air having blade device is provided. In other words, the Radrücken the compressor wheel, at least in a partial area on a blade device with blade elements. By means of the blade elements, air is to be compressed in the region, so that a negative pressure favoring the compressor oils in the region mentioned can be avoided or at least kept very small with respect to the bearing housing element.

Due to the targeted shaping in the form of the blade means of Radrückens behind the compressor wheel, d. H. in the region bounded in the axial direction at least partially by the wheel back pressure, so that during operation of the exhaust gas turbocharger pressure in the region, d. H. the pressure between the Radrücken and the bearing housing member increases. A differential pressure between the Radrücken and the bearing housing element can thus be selectively avoided. Furthermore, it is possible during the operation of the exhaust gas turbocharger by means of the blade device to generate a pressure in the region which is greater than a pressure prevailing in the bearing housing element. As a result, flow of lubricant, in particular lubricating oil, from the bearing housing element in the regions and thus into the compressor housing element can be avoided in a particularly simple manner.

The pressure ratios between the area and the bearing housing element which can be effected by the blade device benefit the function of a sealing device which comprises at least one sealing element for sealing the shaft against at least one of the housing elements. Furthermore, the pressure ratios which can be effected can even counteract a flow of lubricant from the bearing housing element into the compressor housing element, since the high pressure in the region prevents such an overflow.

Due to the pressure increase in the range that can be effected, for example, a sealing concept of shaft sealing rings can also act at low rotational speeds of the exhaust gas turbocharger or its rotor, so that no lubricant can flow via the shaft sealing rings in the direction of the compressor housing.

As a result of the prevention of compressor oils and oil deposits on components such as the compressor, the compressor housing element, the bearing housing element, tubular elements for guiding by means of the compressor to be compressed and the internal combustion engine to be supplied air, deposits on a charge air cooler, on a suction pipe, on sensors, valves and be avoided at injectors, etc. In addition, deterioration of the efficiency of the compressor due to oil deposits can be avoided, so that there is no loss of boost pressure. Furthermore, an entry of the lubricant from the bearing housing element into combustion chambers of the internal combustion engine and concomitant changes in raw emissions can be avoided. This is also a low fuel consumption and a low consumption of reducing agent for Entsticken exhaust gas of the internal combustion engine to good.

Furthermore, maintenance work on the internal combustion engine and exhaust aftertreatment devices can be kept low. The prevention of the compressor oil also has a positive effect on the life of the internal combustion engine, the exhaust aftertreatment devices and the exhaust gas turbocharger. The exhaust gas turbocharger is used in any type of internal combustion engine, in particular reciprocating internal combustion engine and thus in particular in diesel engines, gasoline engines and Diesottmotorenen.

Advantageously, the blade device is formed integrally with the Radrücken. This leads to a particularly low number of parts of the exhaust gas turbocharger.

The blade device can be formed, for example, by machining, in particular by mechanical processing, of the wheel back at this. Moreover, it is possible to form the blade means together with the Radrücken in a casting process for producing the compressor wheel with.

In a particularly advantageous embodiment of the invention is a ratio of an outer diameter of the blade device to an outer diameter of the compressor wheel, in particular the Radrücken d / D, in a range of from 0.01 to 1. inclusive, particularly advantageous pressures can be realized in the said range even at low rotational speeds of the rotor and in a particularly wide operating range of the internal combustion engine for preventing the compressor oil.

As further particularly advantageous for the prevention of the compressor oil, it has been found that a ratio of an inner diameter of the blade device to an outer diameter of the blade device ds / d is within a range of 0.01 to 1 inclusive.

In a further embodiment of the invention, it is provided that the blade elements have a respective wrapping angle, which lies in a range of ε including 0.5 ° to 120 ° inclusive. The respective wrap angle indicates the angular range over which the respective blade elements extend in the circumferential direction of the compressor wheel. By means of this corresponding embodiment of the blade elements, advantageous pressures in the area can be generated even at low rotational speeds of the rotor, thereby assisting, for example, a sealing device for sealing the shaft against at least one of the housing elements and thus avoiding a transfer of lubricant into the compressor housing element.

In a further embodiment of the invention, a respective inlet angle, under which the air flows in the said region during operation of the exhaust gas turbocharger, the respective blade elements of the blade means β, in a range of 0.5 ° to 88 ° inclusive including. As a result, the air in the area can be compacted particularly effectively and efficiently by means of the blade device.

A particularly effective mode of operation of the blade device can be realized if a respective outlet angle at which the air flows out of the respective blade elements of the blade device during operation of the exhaust gas turbocharger lies in a range of from 0.5 ° to 90 ° inclusive. The respective entry angle and exit angle can be determined by appropriate geometric design, d. H. Shaping the blade elements are set, as is also provided in conventional impeller blades for compressing the internal combustion engine to be supplied air.

If the blade elements each have a pitch angle α at least in a partial area which lies in a range of 0 ° to 45 ° inclusive, a particularly advantageous geometry of the blade elements can be realized thereby providing advantageous pressures in particular at particularly low rotational speeds of the rotor can be adjusted to the specified range. In this case, the pitch angle relates, for example, to a pitch of a respective outer contour of the blade elements relative to a plane running perpendicular to the axis of rotation of the compressor wheel.

In a further advantageous embodiment of the invention, a ratio of a respective thickness of the blade elements to the outer diameter of the blade device is in a range t / d from 10 ^-4 to 1 inclusive. In this way, a particularly advantageous compression of the air in the area can be realized by means of the blade device. On the other hand, the cost of materials for producing the blade device and thus the weight of the compressor wheel can thus be kept low.

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 combinations of features mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively indicated combination but also in other combinations or alone, without the frame to leave the invention.

The drawing shows in:

1 a schematic longitudinal sectional view of an exhaust gas turbocharger for an internal combustion engine, with a compressor wheel, which has a Radrücken, wherein 1 to explain the background of the invention;

2 a schematic rear view of an embodiment of the compressor wheel, the Radrücken is provided with blade elements for compressing air comprising blade device;

3 a schematic view of an in 2 X1 designated area of the compressor wheel;

4 Sectionally a schematic sectional view of the compressor according to 2 along an in 2 shown section line A1-A1;

5 a schematic rear view of another embodiment of the compressor wheel;

6 a schematic rear view of another embodiment of the compressor wheel;

7 a schematic rear view of another embodiment of the compressor wheel; and

8th a schematic and perspective rear view of another embodiment of the compressor wheel.

1 shows in a fragmentary longitudinal sectional view of a whole 10 designated exhaust gas turbocharger for a designed as a reciprocating internal combustion engine internal combustion engine of a motor vehicle. The turbocharger 10 includes a compressor 12 to which a compressor housing element 14 the exhaust gas turbocharger 10 assigned. The turbocharger 10 further comprises a bearing housing element 16 , which with the compressor housing element 14 connected is.

In addition, the exhaust gas turbocharger points 10 a rotor 18 with a wave 20 and a compressor wheel 22 on. The rotor 18 also includes a in 1 unrecognizable with the wave 20 rotatably connected turbine wheel of a 1 unrecognizable turbine of the exhaust gas turbocharger 10 , The turbine wheel is in one with the bearing housing element 16 associated turbine housing element of the turbine. The turbine is arranged in an exhaust tract of the internal combustion engine, wherein the turbine wheel of the exhaust gas can be flowed against and thereby driven.

The rotor 18 is on the bearing housing element 16 around a rotation axis 24 relative to the bearing housing element 16 rotatably mounted. The rotatably with the shaft 20 connected compressor wheel 22 can be driven via the shaft and the turbine wheel and thereby compress the air supplied to the internal combustion engine.

In the present case, the compressor is a centrifugal compressor, wherein the compressor wheel 22 during operation of the exhaust gas turbocharger 10 via a Verdichterradseintrittsbereich 26 at least substantially flowed in the radial direction of the air to be compressed and via a Verdichterradaustrittsbereich 28 is at least substantially radiated in the radial direction of the compressed air. The flow of air is in 1 by directional arrows 32 illustrated. For compressing the air, the compressor wheel comprises 22 while a plurality of impeller blades 30 ,

How out 1 can be seen, is through the bearing housing element 16 in the radial direction to the outside and by a Radrücken 34 the compressor wheel 22 in the axial direction in each case at least partially an area 36 limited. The bearing housing element 16 includes a plurality of inserts 25 , In addition, with the wave 20 an element 27 rotatably connected.

To the storage of the rotor 18 on the bearing housing element 16 To cool and / or lubricate the storage is supplied with a lubricant in the form of lubricating oil. To prevent lubricating oil from bearing housing element 16 between this and the wave 20 through into the area 36 and further into the compressor housing element 14 passes, is the bearing housing element 16 about his bets 25 and the element 27 against the wave 20 through shaft seals 29 sealed.

If no appropriate countermeasures are taken, however, it may, in spite of this seal, become one of directional arrows 41 illustrated flows of lubricant from the bearing housing element 16 in the area 36 come, whereby the compressed air is supplied with the lubricating oil. This flow can unfavorably be promoted by a so-called Radüberstand B and in particular at low speeds of the rotor 18 occur. Here it may be in the range 36 opposite the bearing housing element 16 come to a negative pressure, by means of which the lubricating oil from the bearing housing element 16 in the area 36 can be sucked.

Based on 2 to 4 is now an embodiment of the compressor wheel 22 illustrates, by means of which this overflow of lubricating oil from the bearing housing element 16 in the compressor housing element 14 , which is commonly referred to as compressor oils, can be kept at least low.

How out 1 relating to 2 to 4 is recognizable, is the Radrücken 34 the compressor wheel 22 in a subarea 38 with a blade device 40 provided with a plurality of blade elements 42 includes. The scoop elements 42 are based on the bearing housing element 16 stored state of the compressor wheel 22 at least partially in the said area 36 arranged and serve, during operation of the exhaust gas turbocharger 10 ie while the rotor is moving 18 turns, air in the area 36 to condense.

This can cause the formation of a negative pressure in the area 36 opposite the bearing housing element 16 be avoided. By means of the blade device 40 it is also possible in the field 36 opposite the bearing housing element 16 one To generate overpressure. Due to this pressure generation at Radrücken 34 in the area 36 acts the sealing concept of the shaft seals 40 even at low speeds of the rotor 18 , so do not lubricate the oil seals 40 in the compressor housing element 14 can flow. How out 2 can be seen, the blade elements extend 42 starting from a receiving opening 44 in the radial direction outwards and are configured at least substantially arcuate. In the receiving opening 44 , Which in the present case as a passage opening of the compressor wheel 22 is formed, is the wave 20 added.

The blade device 40 has an outer diameter d, which is on respective, in the radial direction outermost edges of respective outer contours 46 the blade elements 42 refers. The blade device 40 also has an inner diameter ds, which corresponds to the inner diameter of the at least substantially circular receiving opening 44 equivalent. In 2 is also an outer diameter D of the Radrücken 34 and in the present case the compressor wheel 22 shown in total.

3 shows further geometric parameters using the example of one of the blade elements 42 , In 3 an entrance angle β is shown below that in the area 36 by means of the blade device 40 to be compressed air during operation of the exhaust gas turbocharger 10 the respective blade elements 42 flows against. The entrance angle β is enclosed by an in 3 chord line P illustrated with a dashed line of the respective blade element 42 and a tangent T to the radially outer edge. In 3 is also an exit angle γ recognizable under the in the area 36 from the blade device 40 air to be compressed from the respective blade element 42 flows. The angle γ is thereby included by the chord P and a tangent F to a respective blade root on the inner diameter ds. Furthermore, in 3 a radius R of the chord P recognizable. In addition is 3 a respective wrap angle ε of the respective blade element 42 recognizable. The wrap angle ε refers to an angular range over which the respective blade element 42 based on the outer diameter d, ie on the outer diameter d, in the circumferential direction of the compressor wheel 22 extends.

In 4 are other parameters of the vane elements 42 recognizable. In 4 is a respective pitch angle of the respective blade elements 42 denoted by α. In addition, the respective blade elements have 42 a thickness t.

The by means of the blade device 40 in the area 36 To be compressed air in the present case serves to avoid compressor oils. In other words, the blade device serves 40 exclusively to counteract the compressor oils, that is, the bearing housing element 16 To seal and not for compression of the internal combustion engine to be supplied air For the realization of a particularly effective and efficient compression of the air in the area 36 the mentioned geometric parameters are present in the following proportions:
0.01 ≥ d / D ≤ 1
0.01 ≤ ds / d ≤ 1
0.5 ° ≤ ε ≤ 120 °
0.5 ° ≤ β ≤ 88 °
0.5 ° ≤ γ ≤ 90 °
0 ° ≤ α ≤ 45 °
1 ≤ t / d ≤ 0.0001

5 to 7 illustrate further embodiments of the compressor wheel 22 , which can be realized by variation of said geometric parameters. In the embodiment of the compressor wheel 22 according to 5 extend the blade elements 42 starting from the inner diameter ds in one direction substantially more outward than according to 2 to 4 , The outer diameter d is according to 5 thus much larger than according to 2 ,

In the embodiment of the compressor wheel 22 according to 6 falls the inner diameter ds of the blade device 40 not with the inner diameter of the receiving opening 44 together. The scoop elements 42 are according to 6 in an at least substantially annular area 48 arranged, which extends in the circumferential direction of the compressor wheel 22 completely circumferential over the Radrücken 34 extends. Also based on 7 is a possible embodiment of the blade device 40 illustrated.

8th shows in a schematic perspective view of another embodiment of the compressor wheel 22 , which can be represented by appropriate adjustment of the geometric parameters.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007027869 B4 [0002, 0010]
• DE 102008049250 A1 [0002, 0010]
• DE 3313484 A1 [0002, 0010]
• DE 102006029542 A1 [0002, 0010]

Claims (8)

Exhaust gas turbocharger ( 10 ) for an internal combustion engine, with a shaft ( 20 ) and one with the shaft ( 20 ) rotatably connected compressor wheel ( 22 ) comprehensive rotor ( 18 ), with a bearing housing element ( 16 ) as the first housing element, on which the rotor ( 18 ) about a rotation axis ( 24 ) is rotatably mounted, and with one with the bearing housing element ( 16 ) associated compressor housing element ( 14 ) as a second housing element, in which the compressor wheel ( 22 ) is at least partially received, wherein by at least one of the housing elements ( 14 . 16 ) in the radial direction and by a Radrücken ( 34 ) of the compressor wheel ( 22 ) in the axial direction in each case at least partially an area ( 36 ) is limited, characterized in that the Radrücken ( 34 ) with one at least partially in the area ( 36 ) arranged blade elements ( 42 ) for compressing air-bearing blade device ( 40 ) is provided. Exhaust gas turbocharger ( 10 ) according to claim 1, characterized in that a ratio of an outer diameter (d) of the blade device ( 40 ) to an outer diameter (D) of the compressor wheel ( 22 ), in particular the Radrücken ( 34 ) is within a range of 0.01 to 1 inclusive. Exhaust gas turbocharger ( 10 ) according to one of claims 1 or 2, characterized in that a ratio of an inner diameter (ds) of the blade device ( 40 ) to an outer diameter (d) of the blade device ( 40 ) is within a range of 0.01 to 1 inclusive. Exhaust gas turbocharger ( 10 ) according to one of the preceding claims, characterized in that the blade elements ( 42 ) have a respective wrap angle (ε) which is in a range of from 0.5 degrees to 120 degrees inclusive. Exhaust gas turbocharger ( 10 ) according to any one of the preceding claims, characterized in that a respective inlet angle (β), below which the air during operation of the exhaust gas turbocharger ( 10 ) the respective blade elements ( 42 ) of the blade device ( 40 ), ranging from 0.5 degrees to 88 degrees inclusive. Exhaust gas turbocharger ( 10 ) according to one of the preceding claims, characterized in that a respective outlet angle (γ), below which the air during operation of the exhaust gas turbocharger ( 10 ) the respective blade elements ( 42 ) of the blade device ( 40 ), ranging from 0.5 degrees to 90 degrees inclusive. Exhaust gas turbocharger ( 10 ) according to one of the preceding claims, characterized in that the blade elements ( 42 ) in each case at least in a partial region have a pitch angle (α), which is in a range of from 0 degrees to 45 degrees inclusive. Exhaust gas turbocharger ( 10 ) according to one of the preceding claims, characterized in that a ratio of a respective thickness (t) of the blade elements ( 42 ) to an outer diameter (d) of the blade device ( 40 ) ranges from 0.0001 to 1 inclusive.

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