WO2008125554A1

WO2008125554A1 - Turbocharger and method for controlling the pressure of the turbocharger

Info

Publication number: WO2008125554A1
Application number: PCT/EP2008/054240
Authority: WO
Inventors: Frank Atzler; Schahier El-Garrahi; Roy Haworth; Francis Heyes; Achim Koch
Original assignee: Napier Turbochargers Limited; Continental Automotive Gmbh
Priority date: 2007-04-16
Filing date: 2008-04-08
Publication date: 2008-10-23
Also published as: DE102007017844A1; DE102007017844B4

Abstract

The invention relates to a turbocharger comprising a turbine that is arranged in a turbine housing. Said turbocharger comprises stationary guide blades that are disposed about the periphery of the turbine wheel of the turbine. Said turbocharger also comprises a device for distributing a pressurised gaseous medium, the pressure of said gaseous medium being varied by means of at least one pressure control device. Said turbocharger further comprises supply lines that are arranged in the turbine housing and/or the guide blades such that the gaseous medium can guided at a predetermined pressure through the supply lines in the respective intermediate chambers between the guide blades, in order to control the charge pressure.

Description

description

Turbocharger and method for controlling turbocharger boost pressure

The invention relates to a turbocharger or turbocharger, wherein the turbocharger can be used for example in passenger car engines or truck engines, and a method for controlling the boost pressure of the turbocharger.

In conventional turbochargers, the boost pressure is, if necessary, limited by having your blow-off valve, i. A bypass or a waste gate partially bypasses the hot exhaust gas at the turbine and thus reduces the power of the turbine. For this, the turbine is designed small, so that it works well well below the rated operating point of the engine. At the nominal operating point, opening the blow-off valve directly results in turbine power loss and eventually pressure drop. Therefore, for example, a pressure cell is provided, which is acted upon directly by the boost pressure and is adjusted by an intermediate control valve (timing valve) of an electronic control unit. This allows the boost pressure to be regulated to a specified setpoint.

An energetically more favorable control allows the so-called variable turbine geometry (VTG), with which the Aufstauverhalten the turbine continuously changes and thus each of the entire exhaust gas energy can be used. With the variable turbine geometry, the effective flow area of the turbine is varied so that the optimum inflow can be achieved for each operating point. In this case, movable guide vanes are used, which are arranged between the turbine wheel and the volute, more precisely around the turbine wheel.

During vehicle acceleration from low engine speeds, the vanes are moved to provide the necessary to gain energy from the exhaust gas. In this case, the cross section of the exhaust gas flow from the turbine wheel is changed by the guide vanes and, depending on the system, also the inflow angle. As a result, the exhaust gas energy in the turbine wheel is better utilized and generated in the episode on the compressor side, a higher boost pressure.

With increasing engine speed, the position of the vanes is adapted to the respective operating point. In this case, the flow cross-section and / or the inlet angle of the turbine is changed in order to control the energy supplied to the turbine and the required boost pressure. The desired boost pressure is achieved with a more favorable turbine pressure ratio, the consumption of the engine may be reduced. In a fully open position of the vanes, the maximum throughput of the turbine is revealed at high centripetal fraction of the velocity vector of the flow.

For controlling the guide vanes, levers are used, for example, which are actuated via an adjusting ring housed in the turbine housing. This in turn can be driven by various pneumatic or electric actuators, for example by means of vacuum boxes and timing valves.

The advantage of the variable turbine geometry over the turbocharger with bypass is that the turbine efficiency is improved over a wide flow range, as always the full exhaust stream can be routed through the turbine and used for power conversion. In this case, the turbine cross section can be varied by the movable guide vanes, according to a predetermined operating point.

However, the control of the boost pressure by means of the movable guide vanes in the variable turbine geometry has the disadvantage that it is very complicated and expensive to manufacture. The technical complexity and the associated NEN very high additional costs result in the fact that use of such turbochargers, for example, for most cars with gasoline engines is not yet economical.

Accordingly, it is the object of the present invention to provide an exhaust gas turbocharger, with a simplified structure for controlling the boost pressure. Another object of the invention is to provide an efficient method of controlling boost pressure.

This object is achieved by a turbocharger having the features of patent claim 1 and a method according to claim 15.

Accordingly, a turbocharger is provided with a turbine disposed in a turbine housing, comprising:

Fixed vanes disposed about the circumference of the turbine wheel of the turbine; a device for providing a pressurized gaseous medium, wherein the pressure of the gaseous medium is variable via at least one pressure regulating device,

Supply lines which are arranged in the turbine housing and / or the guide vanes, that the gaseous medium can be introduced at a predetermined pressure via the supply lines into respective spaces between the guide vanes, to regulate a boost pressure.

In addition, a method is provided for controlling the boost pressure of a turbocharger, comprising the steps of:

Arranging fixed vanes (20) within a turbine housing (17) around the circumference of the turbine wheel of a turbine (14),

Introduction of a pressurized gaseous medium into the intermediate spaces (23) of the guide vanes (20) via feed lines in the turbine housing and / or the guide vanes (20), wherein the pressure of the gaseous medium is adjusted in dependence on a desired boost pressure.

By introducing or injecting a gaseous medium into the intermediate spaces between the guide vanes, the effective flow cross section of the turbine can be increased or decreased, thereby controlling the boost pressure, wherein the guide vanes can be designed to be stationary. This has the advantage that it can be dispensed with movable Leitschau- fine, as used in the known from the prior art variable turbine housings VTG, and thereby very significant cost can be saved, so that use of the turbocharger according to the invention now in particular from an economic point of view is suitable for cars with gasoline engine.

According to an advantageous embodiment, the supply lines are at least preferably arranged substantially over the entire circumference of the turbine housing or at least in a portion thereof. This has the advantage that the pressurized gaseous medium can be introduced into the interstices over a large area and thereby the effective flow cross section of the turbine can be easily varied.

In a further advantageous embodiment, the supply lines are preferably arranged substantially perpendicular to the flow direction of the exhaust gas and / or at another suitable angle in order to introduce the gaseous medium into the intermediate space between the guide vanes. The angle of attack of the supply lines is chosen so that the boost pressure can be controlled properly. The supply lines need not all be aligned in the same direction, but may also have different orientations and positions, provided that the effective flow cross-section of the turbine can be suitably varied and the boost pressure can be adapted to a predetermined operating point. In another advantageous embodiment, the supply lines are designed in the form of tubes, in order thereby to introduce, for example, the gaseous medium in a particularly targeted manner into the intermediate spaces of the guide vanes. The diameter of the tubes is adapted for example so that all have the same flow over the diameter and the length. In principle, however, it is conceivable that the tubes may also have a different flow, depending on the function and intended use of the tubes in the control of the boost pressure or depending on, for example, their position and angle of attack. In this case, for example, two or more groups of tubes can be formed. In principle, the tubes need not have the same length and the same diameter, but may have different dimensions, depending on the function and intended use.

The tubes can be arranged in a wall of the turbine housing and / or the guide vanes. The tubes may be formed as separate parts, which are inserted into corresponding openings of the turbine housing or the guide vanes. Optionally, the tubes may also be molded to the turbine housing or vanes.

In a further advantageous embodiment, instead of the tubes openings or channels are provided as supply lines, for example, by holes in the turbine housing and / or the guide vanes are mounted. This has the advantage that such holes are easy to produce.

In another advantageous embodiment, the supply lines are connected via at least one supply line to the device for providing the gaseous medium. This supply line can be attached as a separate line, for example, to the turbine housing or the turbine housing can be formed with such a feed line. The same applies to the supply lines in the guide vanes. As a result, the plurality of supply lines can be supplied very easily with the required gaseous medium become. In principle, however, more than one supply line can also be provided, depending on where, for example, the individual supply lines are arranged.

In a further preferred embodiment, the device for providing the gaseous medium is at least one pressure vessel and / or a pressure pump. Alternatively, the gaseous medium, for example compressed air, can also be provided via the compressor. Both alternatives provide a simple way to provide the gaseous medium.

In another preferred embodiment, the pressure of the gaseous medium is adjusted, for example via a pressure control valve. This has the advantage that the pressure can be very easily and inexpensively regulated for the supply lines.

In a further preferred embodiment, the guide vanes are preferably arranged around the turbine wheel in such a way that the guide vanes each form a gap which is suitable for high throughputs. This has the advantage that, for example, at correspondingly high rotational speeds, the stationary guide vanes form an optimum flow cross-section of the turbine, so that no or substantially no gaseous medium has to be supplied in order to regulate the effective flow cross-section.

The invention will be explained in more detail with reference to the exemplary embodiments shown in the schematic figures of the drawings. Show it:

1 shows a schematic view of a first embodiment of the exhaust gas turbocharger according to the invention;

2 shows a detail of the exhaust gas turbocharger according to the second embodiment of the invention; Fig. 3 shows a detail of an exhaust gas turbocharger according to a third embodiment of the invention.

In all figures, identical or functionally identical elements and devices have been provided with the same reference numerals, unless stated otherwise.

In Fig. 1, a first embodiment of an exhaust gas turbocharger according to the invention is shown. The illustration in Fig. 1 serves to explain the principle of the invention and is greatly simplified and not to scale.

The exhaust gas turbocharger according to the invention has, for example, a radial turbine 10 and a compressor (not shown). In the compressor, a compressor wheel is rotatably mounted and connected to a turbo shaft 12. The turbo shaft 12 is also rotatably disposed and connected at its other end to a turbine wheel 14. Hot exhaust gas 18 is thereby introduced from an internal combustion engine (not shown) via a turbine inlet 16 on the turbine housing or volute 17 into the turbine 10, wherein the turbine wheel 14 is rotated. The exhaust stream 18 exits the turbine 10 through a turbine outlet. Via the turbo shaft 12, the turbine wheel 14 is connected to the compressor wheel and thus drives the compressor. In the compressor, air is sucked in through an air inlet and compressed and fed through the air outlet of the internal combustion engine.

In contrast to the described with reference to the prior art variable turbine geometry VTG, in which the guide vanes are designed to be movable, are according to the invention around the turbine wheel 14 fixed or rigid

Guide vanes 20 arranged. The guide vanes 20 can be arranged in such a way that a flow cross-section is respectively formed between the guide vanes 20, which is preferably suitable for high engine speeds. Particularly preferably, the guide vanes 20 can be arranged such that a maximum flow cross-section is achieved between the guide vanes 20, which is tuned to the exhaust gas stream 18. However, the present invention is not limited to this arrangement of the guide vanes 20, but the arrangement can be varied as desired, depending on the function and purpose, the vanes 20 can also form in areas around the turbine wheel 114 spaces 23 with different lent flow cross sections, depending on the function and purpose.

In order to change the Aufstauverhalten the turbine 10 and the effective flow cross-section of the turbine 10 and thereby to use substantially all of the exhaust gas energy, according to the first embodiment of the invention, a fluid contraction or constriction is generated by a gaseous medium 24, such as compressed air , In each case in the intermediate space 23 and flow cross section between the guide vanes 20 is introduced or injected.

The turbocharger according to the invention with radial turbine 10 has for this purpose at least at least a portion of its circumference leads 26 in the form of tube 28, via which the compressed air between the guide vanes 20 is introduced or flowed. The tubes 28 are preferably arranged on the circumference such that at least one tube 28 is assigned to a gap 23 of two guide vanes 20 in order to introduce the compressed air into this intermediate space 23, as shown in FIG. 1. In principle, however, it is also conceivable to assign more than one tube 28 to a gap 23. Thus, for example, two tubes 28 could also be assigned to a gap 23, which introduces compressed air into the intermediate space 23 from the same or a different angle and / or position in order in this way to vary the effective flow cross section. In a preferred embodiment, the tubes 28 are arranged substantially completely circumferentially on the turbine housing 17 or a side wall. The compressed air is preferably introduced perpendicular to the flow direction of the exhaust gas 18.

As shown in FIG. 1, in the first embodiment according to the invention, the tubes 28 can be arranged in this case, for example in the radial direction to the turbine wheel 14, in order to introduce the compressed air into the intermediate spaces 23 of the guide vanes 20. The tubes 28 are preferably comparable to a heat-resistant material, for example, the turbine wheel 14, the guide vanes 20 or the turbine housing 17. The tubes 28 may also be formed on the turbine housing 17 or each form a separate part.

In principle, however, the tubes 28 can also be arranged at any other angle to the flow direction of the exhaust gas 18, as shown by the dashed tube 28 in FIG. 1. The tubes 28 are preferably arranged so that the compressed air can be suitably introduced into the interspaces 23 of the guide vanes 20 in order to vary the effective flow cross-section.

As further shown in FIG. 1, the tubes 28 are connected, for example, to a compressed air supply line 30. The compressed air supply line 30 can be supplied with compressed air, for example, via a compressed air tank and / or fed with air from the compressor side or via another suitable source. The aforementioned sources for providing compressed air are merely exemplary and their list is not exhaustive.

The effective flow area between the vanes 20 may be varied as follows, ie, increased or decreased. This is done on the one hand by the regulation of the pressure with which the compressed air in the respective space 23 of the guide vanes 20 is introduced and on the other hand, depending on the position of the tube 28 and the angle (with respect to the flow direction of the exhaust gas 18) under which the compressed air into the interstices 23 is initiated. As a result, the inflow velocity and the inflow angle at the turbine wheel inlet can be changed accordingly or the effective flow cross section can be varied in order to be adapted to a desired operating point.

For example, at least one compressed air valve (not shown) can be used to regulate the pressure of the compressed air.

During vehicle acceleration from low rotational speeds, compressed air can be introduced via the tubes 28 into the intermediate spaces 23 of the guide vanes 20, for example, under a corresponding pressure in order to increase the boost pressure and to adapt it to a desired operating point. The pressure of the compressed air is chosen such that a sufficient narrowing of the effective flow cross section of the intermediate space 23 or a contraction of the exhaust gas 18 is achieved in order to be adapted to the respective desired operating point.

With increasing speed, the pressure of the compressed air can be reduced accordingly. In this case, for example, little or substantially no compressed air can be introduced into the intermediate spaces 23 of the guide vanes 20 when a correspondingly high engine speed is reached and the charge pressure should not rise any further. In this case, the desired charge pressure is ensured by means of the respective flow cross-section, which is formed by the correspondingly arranged rigid guide vanes 20.

As a result, the boost pressure can be easily varied, similar to the movable vanes of the variable turbine Housing VTG according to the prior art. The great advantage of the invention, however, is that it can dispense with the very complicated and expensive mechanism for moving the vanes.

In the section in Fig. 2, a second embodiment of the invention of the turbocharger is shown. The second embodiment differs from the first embodiment essentially in that no tubes 28 are used in the second embodiment, but the compressed air simply via correspondingly arranged holes 32, the openings or channels 22 in the side wall of the radial turbine 14th form, is introduced into the spaces 23 of the vanes 20. Otherwise, the embodiments of the first embodiment are to be applied according to the second embodiment.

In Fig. 2, the incoming exhaust gas 18 is shown schematically with arrows and correspondingly the compressed air, which is introduced via the bores 32 into the intermediate spaces 23 of the guide vanes 20. The illustration in FIG. 2 is also greatly simplified and not to scale. Thus, the bores 32 may also be disposed at another suitable location in a side wall of the turbine housing 17, provided that the flow area of the respective gap 23 may be suitably varied to adjust a boost pressure to a desired operating point.

As shown in FIG. 1, the supply line 30 for supplying the compressed air can be fastened to the turbine housing 17 as a separate supply line 30 and compressed air can be introduced via the tubes 28 in the wall of the turbine housing 17. According to the representation in FIG. 2, however, it is also conceivable that the supply line 30 is formed on the turbine housing 17.

In Fig. 3, a third embodiment of the turbocharger according to the invention is shown. The third embodiment differs from the first and second embodiment essentially in that the supply lines 26 through which the compressed air is introduced into the respective intermediate spaces 23 of the guide vanes 20, are arranged in the guide vanes 20 itself. Otherwise, the comments on the first and second embodiments apply mutatis mutandis to the third embodiment.

The representation, in particular of the guide vanes 20 and the openings 22 are also greatly simplified in Fig. 3 and not shown to scale. The illustration serves merely to explain the principle according to the invention. The guide vanes 20 are hollow-drilled or each have at least one opening or channel 22 and are supplied with compressed air via a compressed air source (not shown), the compressed air being controlled by at least one pressure regulating valve (not shown). As in the first and second embodiments, the compressed air can be obtained via a pressure vessel, a pressure pump and / or via the compressor side or via another suitable compressed air source. The hollow-bored guide vanes 20 are connected to the compressed air source via at least one compressed air supply line (not shown).

The exit of the openings 22 for the compressed air in the vanes 20 is selected so that the compressed air can be suitably introduced into the space 23 between the ladder blades 20 to vary the effective flow area of the turbine 10 to achieve a predetermined boost pressure. In principle, more than one opening 22 can also be arranged in the conductor blade 20, wherein the openings 22 can be arranged on one side, as shown in FIG. 3, or on both sides of the conductor blade 20 (not illustrated).

The invention, as described by way of example with reference to the previously described embodiments, has the advantage that essentially the entire exhaust gas stream 18 can be used. Furthermore, the introduction of a pressurized gaseous medium, such as compressed air, whose pressure can be varied, allows the effective flow area between the vanes 20 to be varied very easily, with the vanes 20 being rigid and not variable Turbine housing VTG according to the prior art on a complicated, expensive and expensive mechanism must be designed to be movable.

Due to the significantly lower production costs of the turbocharger according to the invention, it is particularly suitable for passenger cars in economic terms. At the same time, the turbocharger according to the invention achieves the same advantages as the previous turbocharger with variable turbine housing VTG, since the entire exhaust gas flow can be used and a suitable boost pressure can be provided over a large rotational speed range.

In principle, a combination of the first, second and / or third embodiment of the invention is conceivable in which as openings 26 both openings or channels 22 or tubes 28 in the periphery or the side wall of the turbine housing 17 can be provided, or openings or Channels 22 or tubes 28 in the vanes 20.

For engines with catalysts, the amount of gaseous medium, i. the compressed air, in addition to tune so that the catalyst is not affected by the resulting air / exhaust gas mixture and at the same time a suitable boost pressure can be set.

Although the present invention has been described above with reference to the preferred embodiments, it is not limited thereto, but modified in many ways.

Claims

claims

A turbocharger having a turbine (10) disposed in a turbine housing (17), comprising: a) fixed vanes (20) disposed about the circumference of the turbine wheel (14) of the turbine; b) a device for providing a pressurized gaseous medium, wherein the pressure of the gaseous medium can be varied via at least one pressure regulating device, c) supply lines (26, 22, 28, 32) which in the turbine housing (17) and / or or the guide vanes (20) are arranged so that the gaseous medium can be introduced at a predetermined pressure via the supply lines into respective intermediate spaces (23) between the guide vanes (20) in order to regulate a boost pressure.

2. A turbocharger according to claim 1, characterized in that the supply lines (26) are arranged at least in a portion of the circumference of the turbine housing (17), preferably substantially over the entire circumference of the turbine housing (17).

3. turbocharger according to claim 1 or 2, characterized in that the supply lines (26) are preferably arranged substantially perpendicular to the flow direction of the exhaust gas (18) and / or at another suitable angle to the gaseous medium in the intermediate space ( 23) between the guide vanes (20) to control the boost pressure, wherein the leads (26) may each have the same orientation and / or a different orientation.

4. turbocharger according to at least one of claims 1 to 3, characterized in that the supply lines (26) in the form of tubes (28) are formed in a wall of the turbine housing (17) and / or the guide vanes (20) are arranged and with the turbine housing (17) and the guide vanes (20) are formed integrally or as separate parts.

5. Turbocharger according to at least one of claims 1 to 4, d a d u c h e c e n e c e s in that the supply lines (26) in the form of openings or channels (22) in a wall of the turbine housing (17) are arranged.

6. turbocharger according to at least one of claims 1 to 5, d a d e r c h e c e n e c e in that the supply lines (26) in the form of at least one opening or channel (22) in the respective guide vane (20) are formed.

7. Turbocharger according to at least one of claims 1 to 6, d a d e r c h e c e n e c e in that the supply lines (26) via at least one feed line (30) are connected to the means for providing the gaseous medium.

8. The turbocharger according to claim 1, wherein the device for providing the gaseous medium is at least one pressure vessel and / or one pressure pump.

9. Turbocharger according to at least one of claims 1 to 8, d a d e r c h e c e n e c e s in that, for example compressed air is used as the gaseous medium.

10. Turbocharger according to at least one of claims 1 to 9, d a d u r c h e c e n e c e s in that there is used as the gaseous medium compressed air of the compressor.

11. Turbocharger according to at least one of claims 1 to 10, characterized in that the pressure regulating device is a pressure regulating valve.

12. The turbocharger according to claim 1, wherein the guide vanes are preferably arranged around the turbine wheel in such a way that the guide vanes each form a gap, which is suitable for high rotational speeds.

13. The turbocharger according to claim 1, wherein the turbine is a radial turbine or an axial turbine.

14. Internal combustion engine with a turbocharger according to one of claims 1 to 13.

A method of controlling turbocharger boost pressure comprising the steps of: a) placing fixed vanes (20) within a turbine housing (17) around the circumference of the turbine wheel of a turbine (14), b) introducing a pressurized gaseous Me - Dium via supply lines (26) in the turbine housing (17) and / or the guide vanes (20) in the intermediate spaces (23) of the guide vanes (20), c) wherein the pressure of the gaseous medium is set in dependence on a desired boost pressure.

16. The method of claim 15, wherein a pressure of the gaseous medium decreases with increasing engine speed.

17. The method according to claim 15, characterized that as a gaseous medium compressed air in the intermediate spaces (23) between the guide vanes (20) is introduced.