DE102017122525A1 - Shaft for an exhaust gas turbocharger and turbocharger - Google Patents

Abstract

The invention relates to a shaft for an exhaust gas turbocharger and an exhaust gas turbocharger having such a shaft. Said shaft includes a first cylindrical bearing portion, a second cylindrical bearing portion and a cylindrical connecting portion disposed between these two bearing portions. The diameter of the cylindrical connecting portion is smaller than the diameter of the two bearing sections. The transitions to the cylindrical connecting portion are formed flat.

Description

Technical field of the invention

The invention relates to a shaft for an exhaust gas turbocharger and an exhaust gas turbocharger, which is equipped with such a shaft.

State of the art

Exhaust gas turbochargers are used to increase the performance of internal combustion engines. They include an exhaust gas turbine driven by the exhaust gases of the internal combustion engine and a compressor for compressing the fresh air supplied to the internal combustion engine. The turbine wheel and the compressor wheel are usually arranged on a common shaft.

In the lower power range up to a few megawatts, turbochargers with a radially impinged turbine wheel and an inner bearing of the shaft are predominantly used.

The shafts on the market today turbocharger have a comparatively large, in the longitudinal direction of the shaft constant diameter, which differs only slightly from the diameters of the bearings in which the turbocharger shaft is mounted. These bearings are usually radial bearings, which are realized as radial plain bearings. In order to provide the largest possible external surface for damping by the oil, these radial plain bearings must be dimensioned correspondingly large. Furthermore, additional catch mechanisms are often implemented at the gas outlet in the radial direction in order to prevent an axial leakage of the turbocharger shaft in the event of a bursting of the compressor or in the event of disengagement of the compressor wheel. Furthermore, by means of suitable backup bearings, which are located between the bearings on the rotatably mounted shaft which connects the compressor to the turbine wheel, an axial leakage of the shaft in case of bursting of the compressor or in case of release of the compressor wheel can be prevented. Such an arrangement of safety bearings is for example in the DE 102013 114 626 A1 described.

All these additional mechanisms mean that the space required in the bearing housing is comparatively large and that the oil emerging from the plain bearings has an unfavorable outflow behavior. Furthermore, said additional catching mechanism for the turbocharger shaft in the radial direction at the gas outlet due to the necessary complexity of the component at high cost and due to restrictions in the outflowing exhaust gas to the turbine to a deterioration of the turbine efficiency.

In order to increase the smoothness of the turbocharger rotor during operation and thus keep the vibrations of the turbocharger as small as possible, the imbalance of the turbocharger rotor are set to a minimum. This can be done by others in the DE 10 2015 218 428 A1 shown device for adjusting the balance of the rotational arrangement of a turbocharger done. In this device, an annular balance adjusting device is provided in the clamping region of a rotating assembly of the turbocharger. This comprises an annular element with a non-uniform weight distribution. By adjusting the rotational orientation of the annular member relative to the rotational assembly, the imbalance of the rotational assembly can be treated. The annular balance adjustment device can be used to correct the imbalance of the rotation assembly. This reduces the turbocharger's vibrations and increases its durability.

Summary of the invention

The invention relates to a shaft for an exhaust gas turbocharger and an exhaust gas turbocharger, which is equipped with such a shaft.

The invention has for its object to provide a shaft for an exhaust gas turbocharger whose space is reduced in the bearing housing and which is held in the event of bursting of the compressor and in the case of disengagement of the compressor of the shaft of the turbocharger in the turbocharger.

This object is achieved by a shaft having the features specified in claim 1. Advantageous embodiments and further developments of the invention are specified in the dependent claims 2 to 11. The claim 12 has the subject of a turbocharger, which is equipped with a shaft according to one of the preceding claims.

A shaft according to the invention comprises a first cylindrical bearing portion, a second cylindrical bearing portion and a cylindrical connecting portion disposed between the first bearing portion and the second bearing portion, wherein the diameter of the cylindrical connecting portion is smaller than the diameter of the bearing portions. The transitions between the cylindrical connecting portion and the respective bearing portion are each formed flat.

According to one embodiment of the invention, the diameter of the first bearing section is equal to the diameter of the second bearing section.

According to one embodiment of the invention, the diameters of the two bearing sections differ from each other.

According to one embodiment of the invention, the ratio of the diameter of the connecting portion to the largest diameter of the bearing portions is between 0.5 and 0.75.

According to one embodiment of the invention, the transition from the connecting section to the two bearing sections is in each case a bevel.

According to one embodiment of the invention, the slope angle of the slope is less than 45 °.

According to one embodiment of the invention, the transition from the connecting portion to the slope is in each case curved.

According to one embodiment of the invention, the transition from the connecting portion to the slope corresponds to a flat rising curve.

According to one embodiment of the invention, instead of the bevel, a flat rising curve having a radius larger than the diameter of the connecting portion is used.

According to one embodiment of the invention, the cylindrical connecting portion has a crown, i. a bulging deformation.

According to one embodiment of the invention, a turbocharger has a shaft with the features according to the invention.

The achievable by the invention advantages are thus achieved by a targeted taper of the shaft of the turbocharger between the two bearing sections. Preferably, the transition from the taper to the bearing portions of the shaft by means of a flat rising slope or by means of a curve with the largest possible radius.

By the described special design of the shaft, the load on the shaft is positively influenced, so that even occurring during operation major imbalances can be endured without damage. In addition, the shaft due to the described embodiment in a burst case and also in the event of omission of the compressor wheel allows a curvature, due to which the remaining part of the shaft is held with the turbine wheel in the turbocharger. This avoidance of axial leakage also minimizes the risk of high turbine spin-up by the remainder of the exhaust gas. In addition, the shaft in the operation of the turbocharger even at high additional operating imbalances on a smooth-running behavior. Furthermore, the invention also allows a realization of plain bearings with in relation to the bearing portions of the shaft small diameters.

Further advantageous features of the invention will become apparent from the exemplification thereof with reference to the figures.

list of figures

• 1 eine Seitenansicht einer Welle gemäß einem Ausführungsbeispiel für die Erfindung,
• 2 eine perspektivische Darstellung der in der 1 gezeigten Welle und
• 3 eine Skizze eines Turboladers, welcher mit einer Welle mit den erfindungsgemäßen Merkmalen ausgestattet ist.

The invention will be described with reference to an embodiment which is explained in more detail with reference to the drawings. Hereby show:

• 1 a side view of a shaft according to an embodiment of the invention,
• 2 a perspective view of the in the 1 shown wave and
• 3 a sketch of a turbocharger, which is equipped with a shaft with the features of the invention.

In the following description, identical reference numerals are used for the same and like-acting parts.

Detailed description of the drawings

The 1 shows a side view of a shaft according to an embodiment of the invention. This wave 7 is intended for installation in a turbocharger. It has a first cylindrical bearing section 8th , a second cylindrical bearing portion 9 and one between these two bearing sections 8th and 9 provided cylindrical connecting portion 10 on. In the first cylindrical bearing section 8th it is a turbine-side bearing section. In the second cylindrical bearing section 9 it is a compressor side bearing section. Following the turbine-side bearing section 8th the wave 7 is the turbine wheel 4 attached a turbine not shown on the shaft. The turbine wheel 4 can with the wave 7 also monolithic in one piece. Furthermore, on the shaft 7 Compressor side attached to a not signed compressor wheel of a compressor.

During operation of the turbocharger becomes the turbine wheel 4 offset by the exhaust stream of an internal combustion engine in a rotary motion. This is about the wave 7 on the on the wave 7 transferred fixed compressor wheel, so that this is also set in a rotary motion. By means of the compressor wheel supplied fresh air is compressed, which is supplied to the internal combustion engine to increase their performance.

The wave 7 the finished assembled turbocharger is mounted in a bearing housing of a bearing device. For the purpose of this storage usually two radial bearings are used, which are mostly radial plain bearings. One of these radial bearings is located on the turbine side of the shaft 7 and surrounds the first cylindrical bearing portion 8th the wave 7 , The other radial bearing is located on the compressor side of the shaft 7 and surrounds the second cylindrical bearing portion 9 ,

In order to ensure a low-wear operation of the turbocharger, is a high smoothness of the turbocharger rotor, the out of the shaft 7 and the two wheels fixed on it, necessary in the radial bearings mentioned. This requirement is further exacerbated by high rotor imbalances occurring during operation of the turbocharger due to the formation of non-uniform dirt deposits on the compressor wheel and on the turbine wheel as well as due to possible damage to these components by foreign bodies. In addition, in the case of a bursting of the compressor or in the case of its release from the shaft during operation of the turbocharger there is a risk that the shaft with the turbine wheel mounted thereon can not be held in the turbine housing, but exits therefrom in the axial direction and the Turbine housing destroyed.

In order to meet these requirements or to eliminate the above-mentioned problems, turbocharger shafts are used so far, which have a comparatively large, uniform in the axial direction diameter, so that the inner diameter of the radial bearing must be sized accordingly large.

The shaft according to the invention 7 goes another way to meet the above requirements or to eliminate the problems mentioned. At the same time the wave becomes 7 in the area between the two bearing sections 8th and 9 specifically rejuvenated.

The diameter D1 of the connection section 10 between the two bearing sections 8th and 9 is smaller than the diameter D2a of the first cylindrical bearing section 8th and also smaller than the diameter D2b of the second cylindrical bearing portion 9 ,

und $$\text{D1}<\text{D2b}\text{.}$$

The following relationships apply: $$\text{D1}<\text{D2a}$$

and $$\text{D1}<\text{D2b}\text{,}$$

In this case, the diameter of the two bearing sections 8th and 9 be the same, so that the following relationship holds: $$\text{D2a D2b =}\text{,}$$

Alternatively, the diameter of the two bearing sections can 8th and 9 also different from each other. In this case, the following relationship applies:

Investigations have shown that in both the above cases, the ratio D1 of the connection section 10 to the largest of the diameter D2a . D2b the bearing sections 8th and 9 should be between 0.5 and 0.75 in order to best meet the requirements set during operation of the turbocharger.

On the one hand, these requirements include sufficient stability, so that the shaft 7 Even at very high speeds has a high smoothness and stability, and on the other hand, in the case of bursting of the compressor or a detachment of the compressor wheel from the shaft, an axial leakage of the shaft is prevented from the turbine housing. The latter is ensured by the fact that due to the described rejuvenation of the shaft 7 in the connection region at a detachment of the compressor wheel, a curvature of the shaft is made possible, due to which the shaft 7 together with the attached turbine wheel does not exit axially from the turbine housing.

The transitions 11 between the connecting section 10 and the first storage section 8th or the second bearing section 9 are each advantageously designed such that during operation of the turbocharger an occurrence of notch stresses in the shaft is avoided or at least kept low.

In one embodiment, these transitions are 11 each at a slope or a linear transition, the slope angle is less than 45 °. Preferably, the transitions are from the connection section 10 to the slope in each case curved and correspond in particular a flat rising curve.

In another embodiment, the transitions are 11 each around a curved transition, which corresponds to a flat rising curve, which runs at an angle smaller than 45 °.

The connecting section 10 may have a crown, ie a bulging deformation.

The 2 shows a perspective view of the in the 1 shown wave. Also from the 2 it is obvious that the wave 7 a first cylindrical bearing portion 8th , a second cylindrical bearing portion 9 and a cylindrical connecting portion provided between these two bearing portions 10 having. The first cylindrical bearing section 8th is on the wave 7 arranged on the turbine side. Furthermore, the turbine side is on the shaft 7 the turbine wheel 4 intended. Furthermore, goes from the 2 also shows that the diameter of the cylindrical connecting portion 10 the wave 7 smaller than the diameter of each of the two cylindrical bearing portions 8th and 9 the wave. In addition, from the 2 also seen that between the cylindrical connecting portion 10 and the two cylindrical bearing sections 8th and 9 provided transition is formed in the form of a flat slope.

The 3 shows a sketch of a turbocharger, which is equipped with a shaft having the features according to the invention. This turbocharger 1 has a turbine 2 , a storage device 5 and a compressor 14 on. The turbine 2 has a turbine housing 3 in which a turbine wheel 4 which is arranged on the shaft 7 is attached or monolithic integral with the shaft 7 is trained. With the turbine housing 2 is a bearing housing 6 a storage device 5 connected. Inside the bearing housing 6 is the wave 7 in a turbine-side radial bearing 13 and a compressor-side radial bearing 12 stored. The wave 7 has a first cylindrical bearing portion 8th , a cylindrical connecting portion 10 and a second cylindrical bearing portion 9 on. Between the connecting section 10 and the first storage section 8th is a flat transition formed as a slope 11 intended. Between the connecting section 10 and the second storage section 9 is also a flat transition formed as a slope 11 intended. The first storage section 8th is in the turbine-side radial bearing 13 stored, the second bearing section 9 in the compressor-side radial bearing 12 , To the bearing housing 6 is the compressor housing 15 a compressor 14 connected. In the compressor housing 15 is one on the wave 7 fixed compressor wheel 16 intended.

• - eine verbesserte Verträglichkeit der Betriebsunwucht bei Gleitlagerbüchsen mit kleinen Außendurchmessern,
• - einen kleineren Bauraum der Gleitlagersitze im Lagergehäuse,
• - einen verbesserten Ölabfluss zwischen den Gleitlagern,
• - ein verbessertes Beschleunigungsverhalten des Turboladers aufgrund der reduzierten Masse der Turboladerwelle und der klein gehaltenen inneren Lagersitze,
• - eine zusätzliche Sicherheit bei Bersten eines rotierenden Bauteiles aufgrund eines verbesserten Verhaltens gegen ein axiales Austreten der Welle aus dem Turbinengehäuse im Falle eines Ablösens des Verdichterrades von der Welle und
• - eine Verwendbarkeit für beliebige Werkstoffe der Welle.

The invention described above has, inter alia, the following advantages:

• an improved compatibility of the operational imbalance in plain bearing bushes with small outside diameters,
• a smaller space of the plain bearing seats in the bearing housing,
• - an improved oil drain between the plain bearings,
• an improved acceleration behavior of the turbocharger due to the reduced mass of the turbocharger shaft and the small inner bearing seats,
• - An additional security in case of bursting of a rotating component due to an improved behavior against axial leakage of the shaft from the turbine housing in case of detachment of the compressor wheel from the shaft and
• - Usability for any materials of the shaft.

LIST OF REFERENCE NUMBERS

1

turbocharger

2

turbine

3

turbine housing

4

turbine

5

bearing device

6

bearing housing

7

wave

8th

first cylindrical bearing section

9

second cylindrical bearing section

10

connecting portion

11

crossing

12

compressor-side radial bearing

13

turbine-side radial bearing

14

compressor

15

compressor housing

16

compressor

D1

Diameter of the connection section

D2a

Diameter of the first bearing section

D2b

Diameter of the second bearing section

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 102013114626 A1 [0004]
• DE 102015218428 A1 [0006]

Claims (12)

Shaft (7) for an exhaust gas turbocharger, comprising: a first cylindrical bearing section (8), - A second cylindrical bearing portion (9) and a cylindrical connecting portion (10) arranged between the first bearing portion and the second bearing portion, wherein the diameter (D1) of the cylindrical connecting portion is smaller than the diameters (D2a, D2b) of both bearing portions and wherein the transitions (11) between the cylindrical connecting portion (11) 10) and the respective bearing section (8, 9) are each formed flat .. Wave after Claim 1 in which the diameter (D2a) of the first bearing section (8) is equal to the diameter (D2b) of the second bearing section (9). Wave after Claim 1 in which the diameters (D2a, D2b) of the two bearing sections differ from one another. Wave after Claim 2 or 3 in which the ratio of the diameter (D1) of the connecting portion (10) to the largest diameter (D1, D2) of the bearing portions (8, 9) is between 0.5 and 0.75. Shaft according to one of the preceding claims, in which the transition (11) from the connecting section (10) to the two bearing sections (8, 9) is in each case a bevel. Wave after Claim 5 in which the slope angle of the slope is less than 45 °. Wave after Claim 5 or 6 in which the transition from the connecting portion to the slope is curved in each case. Wave after Claim 7 in which the transition from the connecting portion to the slope corresponds to a flat rising curve. Wave after one of the Claims 1 - 4 in which the transition (11) from the connecting portion (10) to the two bearing sections (8, 9) is in each case curved. Wave after Claim 9 in which the transition (11) from the connecting portion (10) to the two bearing portions (8, 9) corresponds to a flat rising curve which extends at an angle smaller than 45 °. A shaft according to any one of the preceding claims, wherein the cylindrical connecting portion (10) has a crown. Turbocharger (1) having a shaft (7) according to one of the preceding claims.

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