EP3682116A1

EP3682116A1 - Radial compressor comprising an iris diaphragm mechanism for a charging device of an internal combustion engine, charging device, and lamella for the iris diaphragm mechanism

Info

Publication number: EP3682116A1
Application number: EP18746166.0A
Authority: EP
Inventors: Mathias BOGNER; Christoph Schäfer; Sasa SLAVIC
Original assignee: Vitesco Technologies GmbH
Current assignee: Vitesco Technologies GmbH
Priority date: 2017-09-14
Filing date: 2018-07-25
Publication date: 2020-07-22
Also published as: DE102017216329A1; CN111148901B; US20200208652A1; CN111148901A; WO2019052729A1

Abstract

The invention relates to a radial compressor (30) comprising an iris diaphragm mechanism (50) for a charging device (1) of an internal combustion engine. The invention additionally relates to a charging device (1) comprising a radial compressor (30) and a lamella (52) for the iris diaphragm mechanism (50). The radial compressor (30) has a compressor wheel (13) which is rotationally fixed to a rotatably mounted rotor shaft (14); and a fresh air supply channel (36) for conducting a fresh air mass flow rate (FM) to the compressor wheel (13). An iris diaphragm mechanism (50) is arranged upstream of the compressor wheel (13) such that a flow cross-section for the fresh air mass flow rate (FM) flowing against the compressor wheel (13) can be variably adjusted at least over a sub-region.

Description

Radial compressor with an iris diaphragm mechanism for a charging device of an internal combustion engine, charging device and blade for the iris diaphragm mechanism

The invention relates to a radial compressor (30) with an iris diaphragm mechanism for a charging device of an internal combustion engine. The invention further relates to a supercharger with a radial compressor and a blade for the iris diaphragm mechanism of the centrifugal compressor.

Charging devices are increasingly being used to increase the performance of internal combustion engines, in particular in motor vehicle internal combustion engines. This happens more and more often with the aim of reducing the internal combustion engine with the same or even increased performance in size and weight and at the same time the consumption and thus the CC ^ -Estoß, im

In view of ever stricter legal requirements in this regard. The operating principle is to increase the pressure in the intake tract of the internal combustion engine and thus to effect a better filling of a combustion chamber of the internal combustion engine with air-oxygen. Thus, more fuel, such as gasoline or diesel, per combustion process can be implemented, so the performance of the engine can be increased.

A particular example of such a supercharger is an exhaust gas turbocharger that uses the energy contained in the exhaust stream to create the pressure in the intake tract. For this purpose, the exhaust gas turbocharger to an ordered at ^¬ in the exhaust gas tract of the internal combustion engine exhaust gas turbine, a radial compressor disposed in the intake tract and an interposed rotor bearing. The exhaust gas turbine has a turbine housing and a turbine runner arranged therein, driven by the exhaust gas mass flow. The centrifugal compressor has a compressor housing and a compressor impeller arranged therein, which builds up a boost pressure. The turbine runner and the Verdich ^¬ terlaufrad are on the opposite ends of a common shaft, the so-called rotor shaft, rotatably disposed and thus form the so-called turbocharger rotor. The rotor shaft extends axially between the turbine runner and the compressor runner through the rotor bearing arranged between the exhaust gas turbine and the radial compressor and is in this, with respect to the rotor shaft axis, radially and axially rotatably mounted. According to this structure, driven by the exhaust gas mass flow turbine impeller drives the compressor impeller via the rotor shaft, whereby the pressure in the intake of the engine, based on the air mass flow behind the centrifugal compressor, increased and thereby better filling of the combustion chamber with

Air-oxygen is effected.

Alternatively, in such a charging device for driving the centrifugal compressor instead of an exhaust gas turbine, for example, an electric motor drive unit can be used. Such a charging device is also referred to as a so-called e-booster or e-charger. The radial compressor is characterized in its operating behavior by a so-called compressor map, which describes the pressure build-up on the mass flow rate for different compressor speeds or peripheral speeds. A stable and usable map of the centrifugal compressor is limited by the so-called surge limit to low

Throughputs, through the so-called Stopfgrenze towards higher throughputs, and structurally through the maximum speed limit. When customizing an exhaust gas turbocharger to an internal combustion engine is a centrifugal compressor with a favorable for the engine as possible compressor map is ^¬ selected. The following conditions should be fulfilled:

- A motor full load line should be completely within the

usable compressor map lie;

- Minimum distances to the map limits required by the vehicle manufacturer should be maintained; - maximum compressor efficiency should be present at rated load and in a region of a bottom of the Eckdrehmomentes Ver ^¬ brennungsmotors; and

- The compressor impeller should have a minimum moment of inertia.

The simultaneous fulfillment of all mentioned conditions would be possible with a conventional radial compressor without additional measures only limited. For example, the following trade-offs would result from opposing trends:

- Reduction of the moment of inertia of the centrifugal compressor and

Maximizing the map width and the peak efficiency,

- reduction of flushing in the area of the lower corner torque and maximization of the specific rated power,

- Improvement of the response and increase of the specific rated power of the internal combustion engine.

The trade-offs above could be solved by a compressor design, which has a wide map with minimal Träg ^¬ moment of inertia and maximum efficiency at the full load curve of the engine.

In addition to the above-mentioned stationary requirements, a stable operating behavior of the compressor must be ensured even in transient operating conditions, for example in the case of rapid load shedding of the internal combustion engine. This means that even with a sudden decrease in the delivered compressor mass flow, the harmful so-called compressor pumping must be avoided in a centrifugal compressor. With limitation to the compressor inlet of an Radialver ^¬ dichters the above solution has so far by additional measures, such as an adjustable blade Vorleitapparat, measures for reducing an inlet cross section of the Radi ^¬ alverdichters or solid recirculation, also known respectively as ported shroud. Kennstidstabilisierende measure, has been achieved. In the variable solutions, the broadening of the usable working range of the centrifugal compressor achieved by actively shifting the map. Thus, during engine operation at low speeds and throughputs, the compressor map is shifted "to the left" toward low mass flows, while in engine operation at high speeds and throughputs the compressor map is not shifted or "to the right" toward higher mass flows.

The bucket Vorleitapparat moves by the adjustment of blade angles and induction of a Vordralls in or against the Verdichterlaufraddrehrichtung the entire compressor map to smaller or larger

Throughputs. However, the required adjustment mechanism and the Vorleitapparat itself represent a filigree, compli ^¬ edent and expensive solution.

The cross-sectional reduction of compressor inlet displacement moves the compressor map to smaller flow rates by reducing the inlet area by closing the structure immediately prior to the compressor. In the open state, the measures release as much as possible the entire inlet cross-section and thus do not influence or displace the map in any way or only marginally. Possible, such solutions are described in ^¬ example in US 2016/265424 AI or DE 10 2011 121 996 AI.

To avoid the compressor pumping in a fast load shedding usually a so-called diverter valve is used, which opens in case of sudden decrease of the charge air mass flow through the engine bypass from the compressor outlet to the compressor inlet and so keeps the radial compressor in the stable map area right of the surge line. A combination of active measures, such as the variable Vorleitapparat and the diverter valve is conceivable, but unusual.

An object of the invention is to provide a concept for a radial compressor for a supercharger indicate an internal combustion engine, which contributes to a ver ^¬ venial operation of the supercharger with simultaneously expanded map range. Furthermore, a blade for an iris diaphragm mechanism of the centrifugal compressor is to be made available, which allows the aforementioned concept for the centrifugal compressor. Another object is to provide a charging device for an internal combustion engine, with which the advantages of the inventive radial compressor can be realized during operation of the internal combustion engine.

A radial compressor for a supercharger of an internal combustion engine is disclosed. The radial compressor has a compressor impeller arranged in a compressor housing, which is arranged rotationally fixed on a rotatably mounted rotor shaft. The centrifugal compressor continues to have one

Air supply duct, which is designed for conducting an air mass flow to the compressor impeller. Upstream of the compressor impeller, an iris diaphragm mechanism is arranged, which is designed to at least partially close or open a diaphragm opening, so that a flow cross-section for the air mass flow, such as a cross section of the air supply duct, for flow of the compressor impeller is variably adjustable over at least a ^¬ part. The iris diaphragm mechanism has a plurality of lamellae, each lamella having a lamellar main body which has an inner edge section for delimiting the diaphragm opening. The inner edge portion of each blade has on an opposite side of the compressor impeller on an inner edge, which is not sharp-edged.

In one embodiment of the centrifugal compressor, a variable iris diaphragm mechanism is provided, which is typically located in the air supply duct directly in front of the compressor inlet

Map shift is arranged. The iris diaphragm mechanism can also be referred to as iris diaphragm or iris throttle and has the task of adjusting the inlet mass flow of the radial compressor at least over a partial region. The Iris choke acts as a kind of masking of an outer area of the compressor inlet. With increasing throttling, that is to say cross-sectional constriction, the iris throttle assumes the function of a diverting-air valve, since it can prevent a compressor pumping of the radial compressor. This makes it possible to actively influence the operating range of the centrifugal compressor and also to keep the centrifugal compressor at a stable load point of the engine in a stable operating point.

The air supply duct is formed on the radial compressor. For example, the air supply duct is at least partially formed by the compressor housing, the iris mechanism, an on ^¬ suction port and / or other components of the centrifugal compressor.

In one exemplary embodiment, the iris diaphragm mechanism has a plurality of lamellae which can be displaced by rotation relative to one another and which are arranged partially overlapping one another over the circumference of the air supply channel, concentric with the central axis of the air supply channel or the compressor inlet. Each blade is disposed about a respective, preferably in an edge region of the lamella, stored fulcrum rotatably on a stationary bearing portion and is engaged with an actuating element which is preferably arranged in a side opposite to the fulcrum edge ^¬ area of the lamella, with a movably mounted adjustment ring operatively connected ,

The bearing part is, for example in the area of the air intake guide duct fixed bearing ring, a separate housing of the iris mechanism, part of the compressor housing of the door ^¬ boladers or multi-part design, such as a portion of the compressor housing and a separate additional housing part. The bearing part is annular or has an annular portion. The support member may also be a festste ^¬ Hendes housing element. The adjusting ring is arranged in this embodiment concentric with the bearing part and about the common central axis, which simultaneously forms the central axis of the air supply duct or the compressor inlet, rotatable. The slats are synchronized via the adjusting ring and moved together. By rotation of the adjusting ring about its central axis, the rotation of the lamellae about their respective pivot point is triggered by means of the actuating element. Upon rotation of the slats parallel to the axis of rotation of the compressor wheel, the slats pivot radially inward and thus lead to a desired narrowing of the flow cross-section directly in front of the compaction ^¬ terlaufrad. The adjusting ring itself is driven and moved, for example via an actuator. The actuator may be an electrically or pneumatically operated actuator.

Each lamella has a substantially plate-shaped, flat lamella base body, which serves for the shielding of the air mass flow and thus the adjustment of the aperture. The lamellar base body extends, for example, in a main extension plane in the manner of a circular ring segment over a part of a circular arc, at about the circular arc

constant or changing ring width and wall thickness. Furthermore, each lamella or each Lamel ^¬ lengrundkörper on an inner edge portion which limits the aperture opening of the iris during operation.

The iris mechanism has to have a sufficient Fes ^¬ ACTION and robustness in order to substantially resist in a normal operation of the turbocharger of the incoming air, which is sucked by the compressor without inherent deformation. The lamellae are designed for this purpose so thick, so designed with such a large wall thickness that they can not bend during operation of the turbocharger and thus have sufficient rigidity. With a view to loading Sonders streamlined design is advantageous pre ^¬ see that the slats on their upstream side, ie on the side facing away from the compressor impeller and the compressor inlet side of their respective inner edge portion, an Have inner edge, which is not sharp-edged. As a result, a flow-favorable flow around the inner ^¬ edge portion of the fins and thus a low-loss on-flow of the compressor impeller is effected. So it improves the flow through the iris diaphragm. In addition, such a design of the inner edge has a favorable effect on a possible noise in the flow around the inner edge portion of the respective blade. A non-sharp-edged embodiment is to be understood as meaning that a respective transition between the boundary surfaces delimiting the inner edge section of a respective lamella and forming the respective inner edge, in each case at an angle greater than 90 ° (measured on the inner side of the lamella).

To achieve this, the relevant, inner edge a rounding, in particular a radius; a chamfer; a Fa ^¬ senabfolge, ie a sequence of several chamfers in direct sequence or the like.

Compared to fins with sharp edges on the side facing the flow of the inner edge portion there are no or only small flow separation and associated flow turbulence at this point, ie directly at the diaphragm entrance, which would be associated with losses and thereby losses in terms of performance of the system. This reduces or prevents the same time the so ^¬-called "vena contracta" effect. This indicates that reduced by the flow separation, such as sharp edges, the effective flow cross-section of an orifice with respect to the constructive aperture cross-sectional This would be the actual mass flow. By iris under otherwise identical conditions less than a theoretical, based on the geometric area of the aperture opening calculated mass flow. Basically, the map shift by means of the iris diaphragm mechanism based on a throttling of the compressor. Consequently, the map shift increases with a smaller aperture. The farther the aperture is closed, the farther the map can be shifted. Due to the lower effective flow cross-section, the map ^¬ displacement is amplified by the vena contracta effect. According ^¬ would be expected due to an obvious guess is that the elimination of this effect would adversely lead due to the described embodiment the inside edge next to the desired reduction in power losses also reduce the map shift.

However, it was recognized that in addition to the advantageous reduction in losses no or little effect on the map ^¬ shift could be detected, despite a no longer or almost no longer exists vena contracta effect. Thus, the performance of the system increases due to the un ^¬ terdrückten flow separation, without having to accept losses in terms of the desired displacement of the compressor map. As a result, overall the compressor efficiency is increased in the map range obtained by the map shift. In addition, an improvement in the acoustic behavior of the system, for example in terms of audible and / or noticeable vibrations in motor vehicles (short NVH, English: noise, vibration, harshness) is also achieved with advantage, since turbulence and recirculation areas, which are typically caused by the Flow separations develop, induce pressure fluctuations and thus represent a sound source. By means of the ^¬ be written not sharp-edged design of the inner edge of the lamella facing strömungszu- such vortices, turbulences and recirculations are suppressed, so that consequently also eliminates a source of noise and the acoustic behavior of the system is improved. In summary, the described concept contributes to increased efficiency of the centrifugal compressor. It also helps to solve the above-mentioned conflicting goals. According to one embodiment, the inner edge arranged on the side of the lamella facing away from the compressor impeller has a rounding or is formed by a rounding. In other words, a continuous transition is provided. By training as rounding the advantages and functions mentioned above are made possible. In particular, the

Rounding be formed by a radius. In particular, a particularly positive effect could be achieved from a radius size of 0.5 mm. It has furthermore proven to be advantageous if the wall thickness of the lamella or the lamellar base body is at least as great as the selected radius of the rounding. Furthermore, radius sizes and corresponding minimum wall thicknesses of the slats of 0.75 mm, 1.0 mm, 1.25 mm, 1.5 mm, 2, 0 mm or even larger are suitable. Optionally, two or more different radii along the edge course can be provided. Alternatively or additionally, the radius can not be formed constant, for example, have a change in curvature.

According to one embodiment, the side facing away from the compressor impeller of the inner edge has a chamfer or is formed by a chamfer. A chamfer is a beveled surface on the edge, which is the transition between two

Main boundary surfaces of the corresponding body forms. By means of the chamfer, therefore, a sharp inner edge of the La ^¬ mellengrundkörpers is "broken." For example, it is a 45 ° bevel, wherein the angle is indicated by the chamfer surface over the course of the respective

Main boundary surface is inclined. So stand the two main boundary surfaces perpendicular to each other, so include an angle of 90 °, so the chamfer surface of a 45 ° bevel is inclined in each case by 45 ° to each adjacent main boundary surface. Alternatively, the side facing away from the compressor impeller of the inner edge of the fin main body may also be formed by a phase sequence. By this is meant a plurality of mutually angularly arranged chamfering a polygon or a Anei ^¬ nanderreihung.

The training as a chamfer or Fasenabfolge allows to We ^¬ sentlichen same benefits and features as mentioned above. In these embodiments, too, the above thickness specification applies to the lamella or the lamellar base body. In addition, such a chamfer or a chamfer sequence is easy to produce.

In one embodiment, a thickness of the sheet main body, that the wall thickness is greater than a mechanical structure necessary for the operation of the turbocharger wall ^¬ strength. In other words, the fins are made thicker than necessary for the operation of the turbocharger. As mentioned above, the lamellae must have sufficient rigidity and thus thickness or wall thickness so as not to fail during operation of the turbocharger. For example, the wall thickness of the lamella can be selected as a function of a desired radius of a rounding of the inner edge, which is greater than a structural ^¬ mechanically necessary wall thickness. Due to the fact that the wall thickness of the slats is chosen to be greater than a required wall thickness, the rounding, chamfer or chamfer sequence on the inner edge can also be made larger. In other words, a larger radius or over a larger area extending chamfer relative to the axial direction of the radial ^¬ compressor, given by the axis of rotation of the compressor ^¬ impeller, are provided. As a result, a further improvement of the flow guidance is achieved.

According to one embodiment, each lamella is made by punching, nibbling, forging, embossing or a casting process. Such methods are particularly advantageous manufacturing ^¬ method for the slats. In such methods, the streamlined shape of the upstream side of the La without second machining cut and is thus particularly cost-effective. There are also other different herstel ^¬ development technologies, in which the slats can be made in one processing step with no subsequent second step.

In this connection, therefore, a manufacturing method of a blade for an iris diaphragm mechanism is also disclosed. The method is characterized by the fact that the lamellar base body including the flattening like a radius of a

Slat semi-finished in a machining process step, such as the aforementioned punching, is made.

Furthermore, a lamella for an iris diaphragm mechanism of a radial compressor, as described above, of ^¬ fenbart. The sipe has a sipe main body having an inner edge portion for limiting an aperture of the iris diaphragm mechanism. The inner edge portion has - in an operationally mounted state - on a side facing away from the compressor impeller of the centrifugal compressor side an inner edge, which is not sharp-edged.

The lamella can advantageously be used in a radial compressor as described above and essentially allows the aforementioned advantages and functions.

The charging device for an internal combustion engine according to the invention comprises a radial compressor, as previously described. In this case, the charging device may be formed either as an exhaust gas turbocharger in which the compressor impeller of the centrifugal compressor is driven by means disposed in the exhaust stream of Ver ^¬ combustion engine exhaust gas turbine, or designed as an electric motor-driven supercharger, in which the compressor impeller of the centrifugal compressor by means of an electromechanical drive, in particular an electric motor, is driven. Furthermore, the charging ^¬ device may alternatively as to the previously mentioned embodiments as a via a mechanical coupling with the internal combustion engine operated loader be formed. Such a coupling between the internal combustion engine and the centrifugal compressor can take place, for example, by means of an intermediate gear which is in operative connection on the one hand with a rotating shaft of the internal combustion engine and on the other hand with the rotor shaft of the centrifugal compressor.

Further advantages and functions are disclosed in the following detailed description of exemplary embodiments.

The embodiments are described below with the aid of the attached ^¬ appended figures. Similar or equivalent elements are denoted across the figures with the same reference numerals.

In the figures show:

1 shows a schematic sectional view of a charging ^device with a radial compressor according to the invention, FIG.

Figures 2A to 2C schematically simplified representations of a

Embodiment of an iris diaphragm mechanism in plan view from the axial direction in three different operating states,

FIG. 3 shows a perspective view of an embodiment of a blade according to the invention of the iris diaphragm ^mechanism ,

Figure 4 is a schematically simplified sectional view of a

Execution of a centrifugal compressor with an iris ^¬ dazzle mechanism

5 shows a schematic detail view of the inner edge section of a lamella of the iris diaphragm mechanism of the radial compressor according to FIG. 4, according to the prior art Figure 6 is a more detailed schematic view of the inner edge portion of a blade of the Irisblendenme ^¬ mechanism of the centrifugal compressor according to an off ^¬ exemplary implementation of the invention,

Figure 7 is a more detailed schematic view of the inner edge portion of a blade of the Irisblendenmecha ^¬ mechanism of the centrifugal compressor according to a further embodiment of the invention, and

Figure 8 is a schematic partial sectional view of an inventions ^{¬ to the} invention lamella of the iris diaphragm mechanism according to Figure 6 with punching tool in a manufacturing step in the manufacture of the lamella.

FIG. 1 shows an embodiment of a charging device 1 according to the invention. The charging device 1 has an embodiment of a radial compressor 30 according to the invention, a rotor bearing 40 and a drive unit 20. The radial ^¬ compressor 30 has a in a compressor housing 31 is ^¬ disposed compressor impeller 13 having an impeller blading 131, which is arranged rotationally fixed on a rotatably mounted in a bearing housing 41 of the rotor bearing 40 the rotor shaft 14 and thus forms the so-called loader rotor 10th The loader rotor 10 rotates in operation about a rotor axis of rotation 15 of the rotor shaft 14. The rotor axis 15 simultaneously forms the loader axis 2 and the compressor axis (which together can also be referred to simply as the longitudinal axis of the charging device) is represented by the drawn center line and indicates the axial Alignment of the charging device 1. The charger rotor 10 is mounted with its rotor shaft 14 by means of two radial bearings 42 and a thrust washer 43 in a bearing housing 41, which together form an embodiment of the rotor bearing 40 stored. Both the radial bearing 42 and the thrust washer 43 are supplied here via oil supply channels 44 of an oil port 45 with lubricant. , _n

15

According to the embodiment shown, a charging ^¬ device 1, as shown in Figure 1, a multi-part structure. Here, a housing of the drive unit 20 a which can be arranged in the intake tract of the engine compressor casing 31 and a valve provided between the housing of the drive unit 20 and compressor housing 31 rotor bearing 401 be ^¬ züglich the common charger axis 2 arranged side by side and assembly connected to one another. In this case, alternative arrangements and configurations of drive unit 20 and bearing arrangement 40 are also possible. A further assembly of the charging device 1 illustrates the loader rotor 10, which has at least the rotor shaft 14 and disposed in the Ver ^¬ compressor housing 31 compressor wheel. 13

Furthermore, the centrifugal compressor 30 has an adjoining the compressor housing 31, the compressor inlet 36a forming air supply duct 36 for conducting an air mass flow LM on the compressor impeller 13, the suction ^¬ pipe connection piece 37 for connection to the air suction system (not shown) of the internal combustion engine has and in the direction of the loader axis 2 to the axial end of the Verdich ^¬ terlaufrades 13 to. About this air supply duct 36, the air mass flow LM from the compressor impeller 13 from the

Air intake system sucked and directed to the compressor impeller 13. The air supply duct 36 may also be part of an intake manifold and thus not part of the compressor housing 31 but, for example, connects to the compressor inlet 36a formed on the compressor housing 31. The iris diaphragm mechanism 50 is fixed in the air supply duct 36 and / or forms a partial region of the air supply duct 36 immediately before the compressor inlet 36a of the compressor housing 31.

Furthermore, the compressor housing 31 usually has a, annularly arranged around the loader axis 2 and the compressor impeller 13, helically extending away from the compressor impeller 13 spiral channel 32, a so-called compressor flood on. This spiral channel 32 has at least one part the inner circumference extending gap opening with a defined gap width, the so-called diffuser 35, which in the radial direction from the outer periphery of the compressor impeller 13 directed ge ^¬ directed into the spiral channel 32 and through the air mass flow LM from the compressor impeller 13 away under increased pressure in the spiral channel 32 flows. The spiral channel 32 thus serves to receive and discharge the effluent from the compressor impeller 13 and exiting through the diffuser 35 compressed air mass flow LM. The spiral channel 32 further includes a tangentially outwardly directed Luftabführkanal 33 with a manifold connecting piece 34 for connection to a

Air manifold (not shown) of an internal combustion engine on. Through the Luftabführkanal 33, the air mass flow LM is passed under increased pressure in the air manifold of the internal combustion engine.

The drive unit 20 is not detailed in Figure 1 and can be used both as an exhaust gas turbine and as an electric motor drive unit or as a mechanical coupling with the internal combustion engine, for. Example, as an intermediate gear, which is in operative connection with a rotating shaft of the internal combustion engine, what the charging device 1 in a case to an exhaust gas turbocharger and in the other case to an electric motor-operated charger also called e-booster or e-compressor or to a mechanical loader, power. In the case of an exhaust gas turbocharger, a turbine impeller would be opposite the compaction ^¬ terlaufrades 13 provided, for example, which would also arranged rotatably on the rotor shaft 14 and would be driven by an exhaust gas mass flow.

In the air mass flow LM upstream of the compressor impeller 13, the iris diaphragm mechanism 50 is arranged additionally or alternatively to a diverter valve in the air supply duct 36 immediately before a compressor inlet 36a (also compressor inlet) and / or forms at least a portion of the air supply duct 36 immediately before the compressor inlet 36a of the compressor housing 31 and thus in the immediate vicinity of the leading edges 132 of the impeller blading 131st The iris diaphragm mechanism 50 is designed to at least partially close or open an aperture 55, so that a flow cross-section for the air mass flow LM for flowing the compressor impeller 13 is variably adjustable over at least a portion of the flow cross section. The iris diaphragm mechanism 50 thus enables a characteristic ^¬ field shift for the centrifugal compressor 30 in which this acts as a variable intake throttle for the compressor wheel 13. The iris diaphragm mechanism 50 has, for example, a bearing ring 51 which is concentric with the compressor inlet 36a in the air supply duct 36, an adjusting ring 53 arranged concentrically therewith about a common center with an adjusting lever 53a and several louvres 52 rotatably mounted about a respective pivot point in the bearing ring 51. The fins 52 as shown, for example, in an embodiment in Figure 3 comprise, each base body a plate-shaped slat 56 and a pin- or peg-shaped Actuate the ^¬ restriction member 57 (not visible), which is designed for actuation of the respective slat 52, and a For example, also pin-shaped or journal-shaped bearing member 57 a, for pivotally mounting the respective blade 52 on said bearing ring 51 as constituents of the respective blade 52. Figures 2a to 2c show schematically an embodiment of an iris mechanism 50 for an inventive Radi ^¬ alverdichter 30 in three different operating states. The iris mechanism 50 comprises a stationary, festste ^¬ Henden (stationary) bearing ring 51 (here not shown for the visualization of the fins). The bearing ring 51 can, as shown in Figure 1, are represented by a separate component which is fixed in the surrounding housing, for example, the Luftzu ^¬ guide channel 36. Alternatively, the bearing ring 51 may also be formed directly in the surrounding housing and integrally therewith. Thus, the bearing ring 51 also directly on

Compressor inlet 36a of the compressor housing 31 may be formed. Alternatively, a separate housing for the iris diaphragm mechanism 50 may be provided, so that the Iris diaphragm mechanism 50 can be mounted as a separate, preassembled radio ^¬ tion unit on the compressor housing 31 or in the air supply duct 36. On the bearing ring 51, in this example, three fins 52 are rotatably mounted about a respective bearing element 57a (designated only in FIG. 2A). For this purpose, the bearing ring 51 for each slat 52 has an associated pivot bearing point on which the respective slat 52 is rotatably mounted with its bearing element 57a.

Each lamina 52 has an actuating element 57 (only recognizable in FIGS. 2a, 2b and 3c and designated only in FIG. 2C) for actuation by an adjusting ring 53, the bearing element 57a being in an end region of the respective lamella opposite the actuating element 57 52 is arranged.

As a bearing element 57a, for example, a pin-shaped or peg-shaped element may be provided on the respective lamella 52, with which the respective lamella 52 in one in the bearing ring

51 provided, the bearing point forming hole or recess is mounted.

The iris diaphragm mechanism 50 furthermore has an adjusting ring 53, which is arranged concentrically with respect to the bearing ring 51 and is rotatably mounted about the common center, and which in FIG. 2A is provided by the lamellae

52 is hidden and recognizable only on its lever 53a. In the example of Figures 2A to 2C, the adjusting ring 53 has three grooves 54 (only indicated by dashed lines in Figures 2A to 2C, as largely covered by the slats) for the guided operation of the slats 52. In this case, depending on an inclined with respect to the radial direction of the adjusting ring 53 groove 54 for each blade 52 is provided, in which the actuating element 57 of each slat is engaged ^¬ weiligen 52 and guided therein. Thus, by rotation of the adjusting ring 53, the slats 52 are moved synchronized. The adjusting ring 53 is, for example, at its Au ^¬ ßenumfang on or in the housing of the iris diaphragm mechanism 50 and stored in a housing part formed in the compressor housing 31 or the air supply channel 36.

By actuation of the adjusting ring 53, that is by rotation about the common with the bearing ring 51 center, the Actuate the ^¬ supply elements 57 of the slats are guided 52 by the inclined grooves 54 radially inwardly and so the fins 52 around the respective bearing inside also radially 2A shows the aperture 55 with a maximum opening width, FIG. 2B shows the aperture 55 with a reduced opening width and FIG. 2C shows the aperture 55 with a minimum opening width. These representations thus show the partial region of the flow cross-section which can be variably adjusted by partially closing or opening the iris diaphragm mechanism 50 for this exemplary embodiment. The iris diaphragm mechanism 50 thus acts as a variable intake throttle and thus allows, as mentioned above, an advantageous map shift for the centrifugal compressor 30.

FIG. 3 shows a perspective view of an embodiment of a lamella 52 according to the invention, which is installed, for example, in the iris diaphragm mechanism 50 described with reference to FIGS. 2A to 2C. The lamella 52 is essentially a flat, plate-shaped element. The lamella 52 thus has a plate-shaped lamella base body 56, which is arcuate in accordance with FIG. The lamella main body 56 essentially represents the element which is responsible for the throttling of the compressor impeller 12. In their mutually opposite end regions counter has the lamella 52 a respective actuator 57, and a bearing member 57a, which are formed on opposite sides of the lamella 52 lying ^¬ for cooperation with the adjusting ring 53 and the bearing ring 51st The lamella 52 has an inner edge portion 58, which in an intended mounted state of the blade 52 in the

Iris diaphragm mechanism of the centrifugal compressor the aperture

55 limited (see Figures 2B and 2C). The slat main body

56 has a wall thickness 59 (also thickness) formed in such a way ₂

or is dimensioned that sufficient rigidity for use in the iris diaphragm mechanism 50 of the centrifugal compressor 30 is given and prevents bending under normal operating conditions. Visible is also formed on the inner edge portion 58 inner edge 60, which is not sharp-edged and in this example has a chamfer 63 for flow guidance.

Figure 4 shows in a simplified schematic partial ^¬ sectional view of the centrifugal compressor 30 in the region of the dense Ver ^¬ inlet 36a. In a meridional section, the outer contour of the compressor impeller 13 with its wheel hub 13a and the impeller blading 131 is shown. In this case, a leading edge 132 of the impeller blades can be seen, which are ^¬ arranged in close proximity to the compressor inlet 36a. Schematically simplified is also the iris diaphragm mechanism 50, here reduced to the lamellar arrangement, shown in section. The iris diaphragm mechanism 50 is here in the air supply duct 36 immediately before, that is arranged upstream of the compressor inlet 36a. The lamellae 52 delimit the aperture 55 with their inner edge portion 58 to a flow cross section SQ. The inner edge 60 of the fins is here, on the side facing away from the compressor impeller 13, ie on the upstream side in the air mass flow, with a rounding 62, in particular a radius.

FIG. 5 shows an enlarged detailed view Z of the inner edge 60 of a lamella 52 largely according to FIG. 4, but contrary to the subject invention, with a sharp-edged design of the inner edge 60. Each lamella 52 has an inner edge section 58 which has an inner edge 60 which corresponds to the compressor impeller 13 turned away. In the embodiment according to FIG. 5, the inner edge 60 has a sharp-edged design, which results in disruptive flow separations, recirculation and turbulence formations 61 (indicated by the exemplary flow arrows of the air mass flow LM). Such Strö ^¬ mung commutations, recirculation and turbulence 61 cause losses and adversely affect the performance of the system. In addition, SQ, at a given aperture 55, the design flow cross section is reduced to an effective flow cross-section Strö ^¬ SQeff the diaphragm which phenomenon as mentioned above is known as vena contracta effect.

FIG. 6 shows an enlarged detail view Z of the inner edge 60 of a lamella 52 as in FIG. 4, according to an exemplary embodiment of the invention. In contrast to the previously described embodiment according to FIG. 5, the inner edges 60 of the lamellae 52 situated on a side of the lamella 52 facing away from the compressor impeller are not sharp-edged and have a rounding 62 in the form of a radius. Such a radius on the inner edge of the lamella has, for example, a size in the region of the wall thickness 59 of the lamella 52 or smaller than the wall thickness. In various examples, the wall thickness 59 of the fin 52 is in a range of 0.5 mm to 2 mm. Is the radius of the fillet 62 is equal to or smaller than the respective wall thickness 59 of the slat 52, so a deflection of the air stream LM in parallel to the loader axis 2 in the direction at the Ver ^¬ dense impeller 13 facing inner edge of the blade 52 from ^¬ closed and no further constriction of the flow cross section SQ occurs downstream of the aperture 55, so that the effective flow cross section SQeff corresponds to the flow cross section SQ given by the aperture 55. In this way, the advantages and functions mentioned above are achieved in a particularly effective manner.

Since it has on the other hand proved to be more advantageous for the fillet, in particular a radius as large as possible to be ^¬ measure to avoid premature tearing off of the air flow, it may be, the wall thickness 59 of the slat 52 is greater advantageous to select as this would be structurally necessary for the required stability.

FIG. 7 shows a further enlarged detail view Z of the inner edge 60 of a lamella 52, largely as in FIG. 4, according to a further exemplary embodiment of the invention. In modification 6, the inner edges 60 of the lamellae 52 lying on the side of the lamella 52 facing away from the compressor impeller 13 are designed in the form of a chamfer 63 with a chamfer angle FW. Here, the chamfer angle FW refers to the deviation of the chamfer from the main extension plane of the slat 52 or the slat main body 56 which is perpendicular to the loader axis 2. The attachment of a chamfer 63 results in two surface transitions forming one respective chamfer edge 63a. In order to avoid flow separations, these edge edges 63a should each specify the most gentle change of direction of the air mass flow. If the transition angle of a chamfer edge 63a is reduced, this simultaneously increases the transition angle of the respective other chamfer edge 63a and thereby the tendency for flow separation at this point. This makes it advantageous to select the chamfer angle FW in a range of 45 °, since this achieves a common minimum of the transition angles of the chamfer edges 63a. In this case, the bevel 63 should be dimensioned so that it does not extend over the entire wall thickness 59 of the lamella so that at the inner edge portion 58 of the lamella 52 still remains in the direction of the supercharger axis 2 so the main flow direction of the air mass flow LM extending edge at which the air mass flow LM can invest.

On the other hand, it has proved to be on the other hand also here, the chamfer 63 as large as possible to calm the flow of air and thus premature tearing the

To avoid air flow, it may be advantageous here to choose the wall thickness 59 of the slat 52 larger than would be necessary for the structural stability required for the required stability.

Thus, by arranging a chamfer, the advantages and functions mentioned above are achieved.

In further, not shown embodiments, a chamfer sequence is formed instead of a single chamfer, that is, a polygon. So there are several bevel sections with different different chamfer angles FW lined up. As a result, the transition angle of the individual edge edges can be chosen smaller. What allows a softer change of direction of the air mass flow and so beneficial to avoid premature stalling contributes.

FIG. 8 shows a schematic partial ^sectional view of a blade 52 according to the invention of the iris diaphragm mechanism 50 according to FIG. 6 with punching tool 64 in a production step during the production of the blade. In order to produce a corresponding inner edge 60, which is not sharp-edged, in ^¬ example, as here in the form of a radius 62, is a

Punching tool 64 used with appropriate negative mold for molding. The sheet main body of the blade 52 can thus with the streamlined not be sharp edges formed in ^¬ nenkante 60 particularly cost-effective in a working step without need for further processing step Herge ^¬ represents. For this purpose, the lamella 52 by means of the punching tool ^¬ 64 in a single step from a flat

Sheet metal semi-finished punched and the corresponding inner edge simultaneously reshaped so that the relevant inner edge 60 is not sharp-edged. This is a particularly cost effective way of making the erfindungsge ^¬ MAESSEN slats.

As an alternative, however, other production methods are conceivable which can produce the final shape of the lamella main body 56 in one processing step.

Claims

A radial compressor (30) for a supercharger of an internal combustion engine, comprising

- is arranged (in a compressor casing 31 arranged Ver ^¬ up terrad (13) which is rotationally fixed on a rotatably ge ^¬ superimposed rotor shaft (14); and

- A Frischluftzuführkanal (36) for directing a fresh air mass flow (FM) on the compressor wheel (13), wherein

- upstream of the compressor wheel (13) is arranged an iris ^{mechanism at} (50), which is designed to close an aperture (55) at least partially or to open, so that a flow cross section for the fresh air mass flow (FM) to the flow onto the compressor wheel (13 ) is variably adjustable at least over a partial area;

the iris diaphragm mechanism (50) has a plurality of lamellae (52), each lamina (52) having a lamella main body (56) which has an inner edge section (58) for delimiting the diaphragm opening (55), wherein the inner edge section (58) of each lamella (56) 52) on an opposite side of the compressor (13) has an inner edge (60) which is not sharp-edged.

A radial compressor (30) according to claim 1,

wherein the compressor wheel (13) facing away from the inner edge has a rounding (62).

A radial compressor (30) according to claim 2,

wherein the rounding is formed by a radius (62) greater than or equal to 0.5 mm.

A radial compressor (301) according to claim 1,

wherein the compressor wheel (13) facing away from the

Inner edge has a chamfer (63).

5. turbocharger (1) according to claim 1,

wherein the side facing away from the compressor wheel (13) of the inner edge is formed by a phase sequence.

6. Radial compressor (30) according to one of the preceding claims,

wherein a wall thickness (59) of the lamella main body (56) is greater than a wall thickness which is structurally necessary for the operation of the radial compressor (30).

7. Radial compressor (30) according to one of the preceding claims,

each blade (52) being made by stamping, nibbling, forging, stamping or a casting process.

A blade (52) for an iris diaphragm mechanism (50) of a radial compressor (30) according to any one of claims 1 to 7, wherein the blade (52) comprises a blade body (56) having an inner edge portion (58) for defining an aperture (55 ) of the iris diaphragm mechanism (50); and

- The inner edge portion (58) - in an operationally mounted state - on a compressor wheel (13) of the turbocharger (1) facing away from an inner edge (60), which is not sharp-edged.

9. charging device (1) for an internal combustion engine, wherein the charging device (1) comprises a radial compressor (30) according to one of claims 1 to 7 and wherein the on ^¬ charging device (1) as an exhaust gas turbocharger or as an electromotive-powered supercharger or as an over a mechanical coupling is formed with the internal combustion engine operated supercharger.