DE4213047A1 - Radial compressor for vehicle exhaust gas turbocharger - uses feed pipe to deliver flow medium to influence conditions in circulation chamber - Google Patents

Abstract

The radial compressor has an arrangement for influencing the main flow where a flow medium connection (70) runs into the circulation chamber (14) via one or more bores (73) in the housing (10). The bore opens into one or more places in the circulation chamber. A flow medium can be introduced through the flow medium connection to give a required condition in the circulation chamber. USE/ADVANTAGE - Allows flows conditions in exhaust gas turbocharger to be varied to increase torque at low engine speeds and to reduce exhaust gas emissions.

Description

The invention relates to a device for influencing the main flow of a radial compressor with a map stabilization, one by one Includes a circulating chamber delimited against the main flow, which extends from the inlet area to the contour wall and that from Inlet area opposite the main flow is partially covered, the Circulation chamber with at least one in front and one behind the impeller arranged entry level and in front of the impeller exit level Connection opening in the contour wall in connection with the main flow stands.

Nowadays, the demands on internal combustion engines are increasing provided, on the one hand increases the output with the same displacement and on the other hand pollutant emissions and consumption are reduced should. For this reason, exhaust gas turbochargers (ATL) are already used, with which increase the power and torque of the internal combustion engine and / or reduce pollutant emissions. This leads to diesel engines in particular to reduce the amount of particles expelled. For both requirements stations, both for increasing torque at low engine speeds as well as to reduce pollutant emissions are higher ed degrade required. Here you can quickly toast with conventional compressors  the stability limit. Compressors are required that work well provide usable maps with a wide range. In addition to the new development from Verdich components, the use of a KSM offers a cost-effective way without the new development of flow parts that can be used with good efficiency clearly widen the map area.

A compressor without a KSM with a drop in the surge limit from π _v 2.5 and a noise region upstream of the surge limit is shown in FIG. 7. The motor full load line shown as an example is partly in the area of the pumping area. The compressor without KSM is therefore not suitable. The map of a compressor is overlaid with KSM. There are no noise areas here, the surge limit is significantly further to the left and the compressor is suitable for this full-load engine line, especially because with KSM the range that can be driven with good efficiency is widened (using the example of the 0.7 efficiency shell).

As is well known, the engine full load line represents the one for a selected (i.e. on the Mo adapted ATL version represents maximum degree of charging. This is not only the compressor of importance, but also the chosen turbine. The change The full load line is possible with a different compressor / turbine combination Lich, an improvement in one area usually a deterioration in another area, d. H. Polls that are an improvement cause air supply to the engine in the lower engine speed range, generally have a reduction in performance at high engine speeds len result.

The DD-PS 54 055 is already known in the area in front of the wheel outlet to attach a nozzle ring in the housing wall and this over a Connect the line with a valve to a compressed air source. Like in shown in the document, a flow arises against the Main flow, which when emerging from the nozzle ring Flow on the compressor blades some of the air in the impeller back to the Inlet flows. As a result, valuable energy is lost. This follows  due to the fact that the additional air supplied is a higher pressure than has the air that is conveyed into the volute casing by the impeller.

It is also known from DE-AS 10 42 828 to stop the flow to prevent the compressor blades at low speed by there the flow channel is narrowed pneumatically by blowing additional air of higher pressure, the blowing direction opposite to Direction of funding takes place. That is, the annular column in the wall of the Flow channel are aligned so that the additional air with the axial Flow direction opposite component is blown. Also this means that valuable energy is lost.

Finally, a measure is known from DE-OS 23 23 857, in which two Radial compressors are connected in series, with compressed air from Output of the second compressor into the one supplied to the first compressor Airflow is recirculated. For the rest, it is proposed that the recirculated Compressed air not in the inlet air flow of the first compressor initiate, but in the screw diffuser chamber behind the rotor, so the air does not expand and again in the impeller of the first compressor must be compressed. These measures also result in a Back flow of air through the impeller, because at constant speed of the Impeller the pressure generated also remains constant and through the Air blowing increases the pressure behind the impeller. You can also use these Measures do not accelerate the compressor wheel to higher speeds will.

In the known measures, the stability of the Compressor in the surge area can be improved by adding air to the Main flow outside the impeller area is blown through Cross-sectional reduction to increase the speed of the flow.

The invention has for its object in a map-stabilized Radial compressors to create measures with which the interaction motor - Exhaust gas turbocharger can be influenced in such a way that on the one hand the engine in the un tere speed range more air mass is available, on the other hand at ho high speeds, in the range of the nominal power, no performance losses in purchase  must be taken. The change from low load and speed to higher load and / or speed should also be favored so that a first the change of state and second the ATL the operating point changes can accomplish faster.

Starting from the device mentioned above for influencing the Main flow in a radial compressor with a map stabilization solved this measure according to the invention in that a Fluid connection through one or more holes in the housing in the Circulation chamber leads, the bore at one or more points in the circulation chamber opens, and that through the fluid connection a flow medium can be supplied or in the circulation chamber predeterminable state can be produced.

In particular, it is by making the connection opening behind the Impeller outlet level possible, a medium of high pressure, d. H. vacuum supplying standing air directly to the motor via the volute casing. Since that pressurized medium is supplied via the circulation chamber, the division of the flow plays a role. This division is through the Ratio of the size of the connection openings in front of and behind the Impeller inlet and before and after the impeller outlet determined. Here is an optimization in which the connection openings fall from case to be adjusted to the desired circumstances.

Another embodiment of the invention also provides that the contour ring load-bearing webs in the circulation space as blade profiles or guide webs Generation of a swirl are designed. These walkways are in the Connection openings to the impeller. It is also in itself known way provided as a further embodiment, the Form connection openings as a nozzle.

To prevent the compressed air from flowing out when the turbine power is still there not sufficient to achieve the power for the operating point driven with additional air apply, the invention provides that in the main flow before Ver dichterrad a flap is arranged. Also one in the line of the flow  built-in flap, is advantageous to the To be able to close the fluid connection when the turbocharger generates enough compressed air due to its speed.

Another measure of the invention also provides that the circulation chamber is divided into two ring spaces via a ring, which is separated by separate Lines are interconnected and connected to the fluid connection. A control flap can be arranged in each of the separate lines. With such a configuration, versatile adjustment options are available optimal coordination of the main and additional flows possible, the response behavior in the lower engine speed range by blowing in additional air in the sense of a steeper increase in torque and on the other hand to improve the emission of pollutants improvement.

As part of this adjustment and control of optimal operating conditions of the Motor is also provided that the separate lines via a three-way Valve on the one hand with the pressurized fluid and others on the one hand with the crankcase ventilation, the air filter or the Exhaust gas recirculation can be connected.

The advantages and features of the invention also result from the following description of exemplary embodiments in connection with the Claims and the drawing. It shows

Fig. 1 shows a section through the compressor part of a turbocharger having an opening into the provided for stabilizing the performance characteristics circulation chamber fluid port;

FIG. 2 shows a section through an embodiment of the invention according to FIG. 1 with an additional connection opening behind the impeller outlet;

Figure 3 shows a further embodiment of the invention, in which in the flow medium connection separate lines lead into the annular spaces of the circulation chamber divided by an annular web;

Figure 4 is a section through an embodiment with two separate annular spaces in the circulation chamber opening out separate lines.

FIG. 5 shows a schematic illustration of the structural integration of the compressor to explain the mode of operation for the embodiment of the invention according to FIG. 1;

Fig. 6 is a schematic representation of the structural integration of the compressor for explaining the operation of the embodiment of Figure 3, with two pipes for the flow-agent connection.

Fig. 7 is a characteristic field for explaining the invention.

In Fig. 1, a radial compressor is shown in section, which consists of a compressor housing 10 with an impeller 80 . The medium to be compressed is moved from left to right in FIG. 1, the main flow from the inlet area 11 , in which a partially conical inlet ring 12 is arranged, enters the impeller 80 and flows from the impeller outlet 82 into the diffuser 83 of the compressor.

A detour line is formed in the housing wall with a circulation chamber 14 , which is connected to the inlet area 11 via an inlet groove 15 , which is also referred to as a connection opening. The circulation chamber 14 opens into the main flow via a further contour groove or connection opening 16 in the region of the impeller contour.

This inlet groove 15 is located with its full opening width in front of the impeller inlet plane 81 .

The circulation chamber is delimited to the main flow by a contour ring 17 , which extends from the inlet groove 15 to the contour groove 16 . The impeller inlet plane 81 is located in a central axial position of the contour ring 17 , the inside diameter of the contour ring corresponding to that of the impeller diameter while maintaining a necessary running gap. The contour ring 17 is held centrally via webs 18 towards the housing, these webs being cast onto the compressor housing or being able to be mounted in the compressor housing with an extension of the inlet ring 12 . As shown in FIG. 2, a further contour groove 19 can be arranged outside the impeller outlet 82 , which represents a direct flow connection between the circulation chamber 13 or 14 and the diffuser area.

A fluid connection 70 is arranged on the compressor housing 10 , from which a line 71 opens into the circulation chamber 14 . A control flap 72 is attached in the line, the purpose of which is explained below.

The embodiment shown in FIG. 2 differs from the embodiment according to FIG. 1 only in the design of the circulation chamber 13 , which extends to the impeller outlet area and opens into the diffuser 83 via a contour groove 19 .

In FIG. 5, the constructive integration of the compressor is shown. The compressor has a further control flap 75 in the inlet area 11 and a three-way valve 76 in the line 71 to a pressure vessel 77 . Via the three-way valve 76 and a further line 74 , the line 71 is connected to the crankcase ventilation in the engine 85 . Although not shown, line 74 may also be connected to the air filter or exhaust gas recirculation. This connection serves to create a buffer volume to increase the volume of the circulation chamber. Instead of the pressure vessel 77 , the pressure side of a second exhaust gas turbocharger or a mechanical charger connected in series can also be connected to the line 71 .

In the lower speed range of the engine, when the compressor cannot yet provide sufficient air mass, additional air is supplied to the compressor from the pressure vessel 77 , which air is introduced into the circulation chamber 14 via the open control flap 72 and one or more openings 73 . The pressure medium 77 provides the required medium with a pressure level that is sufficient to cover the air requirement in the lower speed range of the engine

• 1) to supply the engine with more air mass even when the turbine is running not enough,
• 2) to provide the required air mass on the compressor side.

The additional air can be guided in the compressor so that the turning up of the ATL to higher peripheral speeds.

In this operating state, the control flap 75 is closed, so that the compressed air to be supplied cannot relax over the inlet area. During the acceleration state, the control flap 75 remains closed until the peripheral speed of the compressor is high enough to maintain the required pressure at the impeller outlet. The flap 75 may only be opened when this operating status is reached. Before that, compressed air must be supplied via the con turnut 15 so that no vacuum or vacuum is created in front of the compressor wheel, ie in the inlet area 11 , which could lead to overspeeding and to the rotor's disruption.

As soon as the compressor delivers sufficient compressed air to the engine via the turbine when the control flap 75 is open, the control flap 72 or 76 can be closed, so that only the circulation chamber 14 with the contour grooves is used to stabilize the main flow, ie to stabilize the map .

If a further operational improvement is now to be achieved in the upper speed range of the engine, the three-way valve 76 can be flipped and the control valve 72 can be opened again. In this state, the motor is connected to the circulation chamber, this additional volume being effective as a buffer volume for the circulation chamber. The distribution of the additional medium introduced into the main flow plays a major role in the described mode of action. This division is determined by the ratio of the opening cross sections of the contour grooves to one another, where optimization can be achieved by experiment.

In FIGS. 3 and 4, another embodiment of the invention is shown, in which the circulation chamber by an annular web 30 into two annular chambers 32 and 33 is divided. The line 71 opens into the front annular space 33 , as in the embodiment according to FIGS. 1 and 2. Another line 35 opens into the rear annular space 32 with at least one opening 3 , the line 35 behind in the embodiment according to FIG. 3 the control valve 91 opens into the line 71 and leads to a separate fluid connection 38 in the embodiment according to FIG. 4.

In Fig. 6, a structural integration of the compressor according to the embodiment shown in FIG. 3 is shown. The line 71 provided for the supply of fluid from the pressure vessel 77 leads via the three-way valve 76 and a control flap 90 , which in the line 71 after the three-way valve 76 and before the forking of the line into those divided by an annular web Rin gräum the circulation chamber is arranged. In the extension of the line 71 , which opens into the front annular space 33 , the control valve 91 is attached.

There are essentially three configurations for the mode of operation individual control flaps and accordingly the following operating states:

• 1. The three-way valve 76 and the control flaps 90 and 91 are closed ge. At the same time, the control flap 75 is open. In this operating state, the compressor of the turbocharger behaves like a regular standard compressor with KSM.
• 2. When the control valve 75 is closed and the three-way valve 76 and control valves 90 and 91 are open, the compressor is pressurized with compressed air from the pressure vessel 77 , which via the contour groove or the connection opening 16 and the compressor wheel to the motor 85 and via the Inlet groove or the connection opening 15 flows into the inlet area 11 . An air mass is thus supplied to the engine for combustion directly at low engine speeds, which, with the appropriate fuel supply, brings about a very rapid increase in output. Accordingly, the start-up of the ATL is accelerated. If, on the other hand, a higher proportion of fuel is not supplied under the given conditions, the same conditions result in a better and cleaner combustion.
• 3. On the other hand, if the three-way valve 76 is closed and the control flaps 90 and 91 are open, a map stabilization results, with the motor acting as a buffer volume for the map stabilization. This operating state is set as soon as the compressor maintains the required boost pressure when the engine is running up and can apply it automatically.

The improvements arising from the invention can be seen from the diagrams in the illustration according to FIG. 7. This diagram shows the characteristic field of an ATL with and without KSM. The characteristic curve field shows the surge limit of the ATL without KSM and with KSM and the speed curves n _T1 assigned to these surge limits _{. . . n of} the turbocharger. This characteristic curve field is the so-called engine intake lines K _{1. . . n} superimposed, which essentially reflect the engine speed for a given engine configuration, since the parameter value of the individual engine intake lines depends on the following expression:

In this equation, V _H corresponds to the stroke volume of the engine, n _{M to} the engine speed and µ _{l to} the air expenditure. It can be seen from the printout. that for a given stroke volume V _{H of} the engine and given air consumption µ _l the individual engine intake lines are essentially dependent on the speed.

The driving range of an engine with ATL charging is the entire range below half of the full-load line, the operating point being at a constant engine speed Line up or down depending on the load on the corresponding engine swallow line can move down.

The course of curve 2 from operating point A to operating point B results from the chosen compressor / turbine combination (mass inertia, turbine size, efficiency, etc.). With an ATL matching curve 2, a change in state according to curve 1 can only be achieved with additional measures such as additional air injection. Here, the engine is provided with more air mass at low engine speeds, the full load line in the illustration according to FIG. 7 already being reached at operating point C and even exceeded from operating point C to operating point B on curve 1.

With the measure according to the invention, the engine full load line can also can be improved without performance disadvantages in the nominal power range must be taken.

The invention thus offers the possibility of the main flow in the compressor housing for increasing torque at low engine speeds or for Influencing reduction of pollutant emissions very beneficial. At the same time, the invention offers the possibility of further measures in the upper RPM range by incorporating the main flow of the compressor the crankcase ventilation or the air filter or the exhaust gas recirculation is adapted closer to the conditions of the engine.

Claims (10)

1. Device for influencing the main flow in a radial compressor with a map stabilization (KSM), which comprises a circulation chamber delimited by a contour ring against the main flow, which extends from the inlet area to the contour wall and which is partially covered by the inlet area from the main flow, the Circulation chamber communicates with the main flow at least with a connection opening in the contour wall arranged in front of and behind a plane of the impeller, characterized in that

• - That a fluid connection ( 70 ) through one or more bores ( 73 ) in the housing ( 10 ) in the circulation chamber ( 13 ; 14 ), the bore ( 73 ) opening at one or more points in the circulation chamber ( 13 ; 14 )
• - And that through the fluid connection ( 70 ) a flow medium can be supplied or in the circulation chamber ( 13 ; 14 ) a predeterminable state can be produced.

2. Device according to claim 1, characterized in

• - That a flap ( 75 ) is arranged in the main flow in front of the compressor wheel ( 80 ).

3. Device according to claim 1 or 2, characterized in

• - That the connection opening ( 16 ) is attached just before the impeller outlet plane ( 82 ).

4. Device according to one of claims 1 to 3, characterized in

• - That a further connection opening ( 19 ) is arranged behind the impeller outlet plane ( 82 ).

5. Device according to one or more of claims 1 to 4, characterized in

• - That the webs ( 18 ) supporting the contour ring ( 17 ) in the circulation chamber ( 13 ; 14 ) are designed as blade profiles or guide webs for generating a swirl,
• - And that the guide bars in the connecting openings ( 16 ) to the impeller ( 80 ) are guided.

6. Device according to one of claims 1 to 5, characterized in

• - That behind the impeller inlet ( 81 ) and before the impeller outlet ( 82 ) arranged connection openings ( 16 ) are designed as nozzles.

7. Device according to one of claims 1 to 6, characterized in that

• - That in the line ( 71 ) to the fluid connection, a control valve ( 72 ) is provided.

8. Device according to one or more of claims 1 to t, characterized in

• - That the circulation chamber via a ring ( 30 ) is divided into two annular spaces ( 32 , 33 ) which are connected to one another and to the fluid connection ( 70 ) via separate lines ( 71 , 35 ).

9. Device according to claim 7 and 8, characterized in

• - That in each of the separate lines ( 35 , 71 ) or in the line ( 71 ) both before and after the fork, a flap ( 90 , 91 ) is arranged.

10. Device according to claim 7 and 8, characterized in

• - That the separate lines ( 35 , 71 ) via a three-way valve ( 76 ) on the one hand with the pressurized flow angle and on the other hand with the crankcase ventilation, the air filter or the exhaust gas recirculation can be connected.