Turbine of an exhaust turbocharger

Technical field

The invention relates to the exhaust gas turbine of an associated internal combustion engine with an exhaust gas turbocharger, according to the preamble of claim 1.

State of the art

When operating an exhaust gas turbocharger whose exhaust gas turbine of pages of affiliated engine relatively high temperatures is exposed. Thus arise in the turbine-side components, such as the gas inlet casing, the nozzle ring, the cover ring and the gas outlet casing large thermal stresses. Since each of these components has a different distance from the internal combustion engine and also different materials are used, the component temperatures differ accordingly. This results in different thermal expansions with relative movements between the individual components, which may lead to the bolts breaking, gas leaks and component cracks. Therefore, the design and arrangement makes the separation points of the gas inlet casing, gas outlet casing, nozzle ring and cover ring an essential role for the functioning of an exhaust gas turbocharger.

From DE-A1-4223496 a screw of the nozzle ring to the gas inlet casing is known. For this purpose, the inner ring of the nozzle ring is thickened and is provided with an additional flange, which receives the the connection with the gas inlet casing serving screws.

Due to the unilateral gland may occur in such a solution to irreversible distortions of the nozzle ring. There is also the risk of the formation of a bypass flow at the outer ring of the nozzle ring, whereby the efficiency of the exhaust turbine of the turbocharger and thus is reduced. Because of the large heat generation on the turbine side, the means of attachment of the nozzle ring screws are too tight and can be very difficult dissolved. Thus the force required to replace the nozzle ring assembly time is greatly extended, which is a major disadvantage for the associated with the turbocharger and in performance of this dependent internal combustion engine.

The EP-B1-191380 shows the exhaust gas turbine of an exhaust turbocharger, whose nozzle ring is stuck through the seal against the gas inlet casing. For this purpose, the outer ring of the nozzle ring has an axial projection and the cover ring has a corresponding fixing flange. The latter is connected by a plurality of bolts to the gas inlet casing. In the circumferential direction of the nozzle ring is fixed by means of positive centering pin at the gas inlet casing.

Both solutions have the common disadvantage that the nozzle ring in each case has an additional component for the arrangement or accommodating fastening elements. This makes it complicated to manufacture and therefore relatively expensive. Moreover, both the axial projection of the outer ring and the flange of the inner ring are anriss risk due to the thermal stresses already described above, whereby a reliable fastening of the nozzle ring and thus the functionality of the turbocharger is not guaranteed permanently.

Summary of the Invention

The invention attempts to avoid all these disadvantages. It is based on the object of the exhaust gas turbine of an exhaust turbocharger in such a way that a simple and secure fastening of the nozzle ring is ensured.

According to the invention this is achieved in that in a device according to the preamble of claim 1, the nozzle ring bears with its outer ring on the cover ring and by its inner ring on the gas inlet casing. Between the outer ring and the gas inlet casing is an axial as well as formed between the outer ring and the gas outlet casing, a radial expansion gap.

The advantages of the invention lie in the fact that the nozzle ring is merely braced diagonally between the gas outlet casing and the gas inlet casing. Because of this fastening, the force flow in the nozzle ring is carried out starting from the cover ring on the outer ring, the vanes and the inner ring, to the gas inlet casing. The two expansion gaps, the nozzle ring can freely expand both in radial and in axial direction. This diagonal bracing of the nozzle ring creates the conditions for free thermal expansion between the turbine-side components so that either no thermal stresses occur or can be offset.

Teaser Endangered, the nozzle ring stiffening components are not present. It is therefore relatively soft, ie designed to be elastic and acts to some extent as a membrane between the components surrounding it. Since the nozzle ring has no mounting flanges it is simple and inexpensive to manufacture. Because consequently no screws are required for fixing, labor is saved even when mounting and dismounting. As an additional advantage, the nozzle ring can be mounted now from both sides, ie, both the compressor side and on the part of the internal combustion engine.

It is particularly expedient if a sealing surface is disposed toward the gas inlet housing the gas outlet casing. Radially outside the sealing surface is formed between the Gasaustritt- and the gas inlet casing, a mounting gap. Due to this design, a good seal is achieved between Gaseintritt- and gas outlet casing.

Further, it is advantageous if the gap width of the axial and radial expansion of the gap is greater than / equal formed of the maximum thermal expansion of outer ring and gas inlet casing and of outer ring and gas outlet casing.

In this way it is ensured that the nozzle ring in all operating states of the exhaust turbine retains its elastic form, ie, no stresses occur. In extreme cases, the outer ring can be easily applied in the axial direction at the gas inlet housing and in the radial direction at the gas outlet housing without the resulting pressure leads to a material wear. This has the advantage that gas leaks can be prevented.

Finally, both the outer and also the inner ring each have a significantly smaller material thickness than the covering ring and the gas inlet casing. The resulting minimum wall thickness differences between the vanes of the nozzle ring and its outer or inner ring have only small thermal stresses result.

it when outer and inner ring are made of sheet metal is particularly advantageous. Thus, the nozzle ring can be manufactured very easily and inexpensively.

In a second embodiment of the invention is on a gas inlet casing, both with this and with the gas outlet casing in the axial direction in a form-locking clamping segment and provided with recesses for the connecting elements. Between the gas inlet casing and the clamping segment has at least one radial gap is formed. In contrast to the first embodiment of the thermal expansions of the gas inlet casing can be compensated in this manner. Accordingly, the junction of Gaseintritt- and gas outlet casing is relieved, so that significantly lower operating voltages occur. For this reason, the solution is especially suitable for thermally highly stressed turbochargers.

Brief Description of Drawing

In the drawing two embodiments of the invention are illustrated with reference to the axial turbine of an exhaust turbocharger.

Show it:<dl id="dl0001" compact="compact"><dt>Fig. 1</dt><dd>a partial longitudinal section of the turbocharger in the region of the exhaust turbine;</dd><dt>FIG. 2</dt><dd>an enlarged detail of Figure 1, in the area of ​​the outer ring.</dd><dt>Fig. 3</dt><dd>a representation corresponding to FIG. 1, but in a second embodiment.</dd></dl>

Only the elements essential for understanding the invention are shown. Not shown are, for example, the internal combustion engine and the compressor side of the turbocharger. The flow direction of the working medium is indicated by arrows.

Way of Implementing the Invention

The exhaust gas turbine of a turbocharger includes one of a Gaseintritt- and a gas outlet casing 1, 2 formed turbine housing 3 which is held together by means of bolts designed as connecting elements 4th In the turbine housing 3 could be accepted by a shaft 5 turbine impeller 6 is arranged with blades. 7 The turbine impeller 6 is defined on the outside by a cover ring designed as a diffuser 8, which in turn is fixed by screws 9 on the gas outlet casing second Between the turbine impeller 6 and the turbine housing 3, a flow channel 10 is formed which receives the exhaust gases of an unillustrated diesel engine connected to the turbocharger turbine wheel and directs it to the 6th Of course, other internal combustion engine may be connected to the turbocharger.

Upstream of the turbine impeller 6 a of an outer ring 11, an inner ring 12 and a number of guide vanes 13 formed between existing and formed as a casting nozzle ring 14 is arranged in the flow channel 10th The latter is disposed axially between the covering 8 and the gas inlet casing 1 and braced radially inside the gas outlet housing. 2 For this is the nozzle ring 14 with its outer ring 11 on the cover plate 8 and with its inner ring 12 on the gas inlet casing. 1 Both its outer and the inner ring 11, 12 each have a significantly smaller material thickness than the covering ring 8 and the gas inlet casing 1 (FIG. 1). Of course, the nozzle ring 14 from other materials, such as are produced for example from sheet metal or steel profiles or consist of ceramic.

Between the outer ring 11 and the gas inlet casing 1, an axial expansion gap 15, and between the outer ring 11 and the gas outlet casing 2, a radial expansion gap 16 is formed. The gap width of the expansion gaps 15, 16 is greater than the maximum thermal expansion of outer ring 11 and gas inlet casing 1 and of outer ring 11 and gas outlet casing 2. Here, the ratio of the gap width of the radial expansion gap 16 is at this gap width of the axial expansion gap 15 about 4: 1. This ratio arises from the radial and axial dimensions of the nozzle ring 14. Of course, the gap widths can also correspond to the maximum thermal expansion of the components involved.

In Fig. 2 an enlarged detail of FIG. 1 is shown which illustrates the proportions of the gap widths roughly. At the radially inner area of ​​the gas outlet casing 2 is adapted to the gas inlet casing 1 a sealing surface 17th Radial outside this sealing surface 17 is arranged a mounting gap 18 between the gas outlet casing 2 and the gas inlet casing. 1

The inner ring 12 is supported by several developed as pins Positionierlementen 19 against rotation on the gas inlet casing. 1 For receiving the pins 19 has the inner ring 12 at its upstream side, a corresponding number of thickened portions 20 having first recesses 21, while the gas inlet casing 1 thus has corresponding, second recesses 22nd Each of the thickenings 20 disposed in the first recesses 21, in the region of the pin 19 an additional inner gap 23 (FIG. 1).

During operation of the diesel engine whose exhaust gases pass via the hot gas inlet casing 1 and disposed therein flow passage 10 to the turbine runner 6 of the exhaust gas turbine. In this case, the nozzle ring 14 has the task to direct the exhaust gases optimally at the moving blades 7 of the turbine impeller. 6 The thus driven turbine wheel 6, in turn, provides for driving the connected thereto, not shown compressor. The compressed air in the compressor is used for charging, that is used to increase performance of the Diesel engine.

The arranged directly in the flow channel 10 nozzle ring 14 is exposed in the process the high exhaust temperatures. Because its vanes 13 are relatively thin, and the entire nozzle ring 14. Moreover, a much smaller mass than the gas inlet casing 1, the gas outlet casing 2 and the cover ring 8 has, experienced by the nozzle ring 14 has a significantly larger increase in temperature than the mentioned surrounding components.

The inventive design of the radial and the axial expansion gap 16, 15, the outer ring 11 of the nozzle ring 14 can accordingly extend the concrete operating conditions freely in both the radial and axial directions. In this case the considerably greater radial expansion of the material in the area between the outer ring 11 and the gas outlet casing 2, opposite the possible axial expansion of the outer ring 11 and gas inlet casing 1 by the above-mentioned ratio of the gap widths of about 4: 1 is taken into account. In this way, the forming between the covering ring 8, the gas inlet casing 1, the gas outlet casing 2 and the nozzle ring 14 thermal stresses can be compensated. The nozzle ring 14 is clamped to a diagonal between the covering 8 and the gas inlet casing 1 and acts on the other hand as a membrane between the components surrounding it. By designing the assembly gap 18, the sealing surface 17 is always connected to the gas inlet casing. 1 The sealing surface 17 prevents exhaust gas leakage to the surroundings. When using metal as the material of the nozzle ring 14 whose flexible design is also supported.

Corresponds to the gap width of the axial and the radial expansion gap 15, 16 of the maximum thermal expansion of outer ring 11 and gas inlet casing 1 and of outer ring 11 and gas outlet casing 2, so the outer ring is 11 at full load of the diesel engine axially on the gas inlet casing 1 and radially on the gas outlet casing 2 at , Thereby, the expansion gaps 15, 16 closed during operation of the exhaust gas turbine. Thus, no exhaust gas to penetrate into the space formed between the outer ring 11, the gas outlet casing 2 and the diffuser cavity 8. In this manner, interference of the exhaust gas flow and gap losses are avoided, which has a higher efficiency result.

In a second embodiment is a located both with this and with the gas outlet casing 2 axially positive-locking clamping segment 24 and provided with recesses formed as bores 25 for the screws 4 at the gas-inlet casing. 1 Between the clamping segment 24 and the gas inlet casing 1 radial gaps 26 are formed (Fig. 3). This also the gas inlet casing 1 can expand radially without increasing its operating voltages. The other arrangement and function of the components is analogous to the first embodiment.

LIST OF REFERENCE NUMBERS

<dl id="dl0002" compact="compact"><dt>1</dt><dd>Gas inlet casing</dd><dt>2</dt><dd>Gas outlet casing</dd><dt>3</dt><dd>Turbinenghäuse</dd><dt>4</dt><dd>Connection element, screw</dd><dt>5</dt><dd>wave</dd><dt>6</dt><dd>turbine impeller</dd><dt>7</dt><dd>blade</dd><dt>8th</dt><dd>Cover ring, diffuser</dd><dt>9</dt><dd>screw</dd><dt>10</dt><dd>flow channel</dd><dt>11</dt><dd>outer ring</dd><dt>12</dt><dd>inner ring</dd><dt>13</dt><dd>vane</dd><dt>14</dt><dd>nozzle ring</dd><dt>15</dt><dd>axial expansion gap</dd><dt>16</dt><dd>radial expansion gap</dd><dt>17</dt><dd>sealing surface</dd><dt>18</dt><dd>mounting gap</dd><dt>19</dt><dd>Positionierlement, pin</dd><dt>20</dt><dd>Thickening of 12</dd><dt>21</dt><dd>Recess, first</dd><dt>22</dt><dd>Recess, second</dd><dt>23</dt><dd>Gap, inside</dd><dt>24</dt><dd>terminal segment</dd><dt>25</dt><dd>Recess, bore</dd><dt>26</dt><dd>Gap, radially</dd></dl>