DE102008007027A1 - Turbocharger with a compressor, which has two air channels, for controlling a bleed air and for blowing off a bleed air - Google Patents

Abstract

The invention relates to a turbocharger with a compressor, wherein the compressor has a compressor housing in which a compressor wheel is arranged, wherein in the compressor housing, a first and a second air passage are provided, via the first air duct air for displacement of the surge line of the compressor can be fed and wherein via the second air channel (22) air is blown off.

Description

The The invention relates to a turbocharger with a compressor, which has two air channels for controlling a bleed air and for blowing off a diverting air. The bleed air is used in particular for Creating a pre-whirl before the compressor of the turbocharger to to reduce occurrence of pumping of the compressor or in To prevent it from happening. By means of the bleed air here is the Pumping limit shifted towards smaller mass flows.

Of the Compressor of an exhaust gas turbocharger is characterized by a map, in which at certain turbocharger speeds and mass flows create a unique assigned pressure. This Map is at large mass flows through the limited so-called Stopfgrenze. At low mass flows is the map is limited by the surge line. This so-called surge limit Occurs due to a stall at the compressor wheel inlet or at the compressor wheel outlet or both.

In the DE 10 2007 051 844 It is described how by means of the bleed air, the surge limit can be further shifted towards smaller air mass flows. For this purpose, air is branched off after the compressor and blown at a suitable angle in such a way before the compressor in the intake that a Vordrall the air is formed. It is expected that, for example, up to about 40% of the intake air will be recycled. In order to be able to generate the pre-swirl in the intake air, the outflow opening of the bleed air must be as small as possible, so that the air reaches the speed of sound in maximum return at the outlet nozzle. However, if now the normal operation of a diverter valve occurs, that is, the engine quickly closes at high speed and Aufla training, the throttle, so this entire amount of air u. U. not be discharged via this one channel, which is designed for the above-described application of the surge limit shift.

Therefore It is the object of the present invention to provide an improved Turbocharger, in which both a surge line of a Compressor suitable can be moved and further the Return air can be sufficiently blown off the compressor.

These Task is achieved by a turbocharger with the features of the claim 1 solved.

• – wobei in dem Verdichtergehäuse ein erster und ein zweiter Luftkanal vorgesehen ist,
• – wobei über den erste Luftkanal Luft zur Verschiebung der Pumpgrenze des Verdichters zuführbar ist und
• – wobei über den zweiten Luftkanal Luft abblasbar ist.

Accordingly, according to the invention a turbocharger is provided with a compressor, the compressor having a compressor housing in which a compressor wheel is arranged,

• Wherein a first and a second air duct are provided in the compressor housing,
• - In which air can be supplied to shift the pumping limit of the compressor via the first air duct and
• - Whose air is blown over the second air duct.

This Turbocharger has the advantage that by providing a second air duct can be blown off a suitable amount of air, if For example, an operating case occurs in which the engine the throttle closes at high speed and charge. In this case, the amount of air, for example, in addition are discharged to the first air passage via the second air channel or also exclusively via the second air duct, depending on how the two air channels are opened become.

advantageous Refinements and developments of the invention will become apparent the dependent claims and the description with reference on the drawings.

In an embodiment of the invention the first air duct conducts a sufficient air mass flow the intake passage in front of the compressor to produce a pre-whirl, which shifts the surge line towards smaller mass flows. This has the advantage that by preventing the pump a Damage to the turbocharger can be prevented.

In a further embodiment of the invention can, for example, via the first and second air duct Air are blown off, for example, a fast closing a throttle valve. In this case, for example, a common Valve means are provided which opens the first air duct first and then the second. The valve device can be actuated via an actuator. On this way, both a surge line can be moved and the Other a boost pressure suitable blown off. Furthermore you can By using only one actuator costs can be saved.

According to one another embodiment may for the first and second air duct also provided in each case a separate valve device be used to open and close the first and second Air duct. The respective valve device is over here actuates an associated actuator. Thereby can For example, the two air channels independently open and closed, depending on the desired Function or purpose.

In a further inventive Aus Guide shape, the valve device has a variable cross-section, for example, to adjust the air mass flow through the first and / or second air duct. Due to the variable cross section, in this case, in particular, the air mass flow through the first air duct for shifting the pumping limit can be set very precisely, depending on the desired air mass flow to be introduced into the compressor housing.

In An embodiment of the invention comprises the valve device an actuating device, for example a stamp which is provided at its end with a conical valve seat. about the slope of the conical valve seat and the feed can be the Air mass flow through the first air duct very easy and accurate be set.

In a further embodiment of the invention is the respective actuator, for example via a stepper motor or a plunger operated. In this way, the Actuator adjusted relatively accurately become.

According to one another embodiment of the invention the cross section of the first air channel is chosen so that an incoming air the highest possible speed achieved, for example, essentially speed of sound. In this way, the intake air as strong as possible Swirl be imprinted. The bigger the Twist is, the better can be a departure of the air flow, for example be prevented at the front edge of the compressor blade and the farther the surge line can go towards smaller mass flows to be postponed.

In a further embodiment of the invention is the second air duct formed larger than the first air duct. This has the advantage that over the second air duct flow larger amounts of air can or a larger air outlet is given for blowing off a boost pressure when, for example, the Throttle is closed quickly.

The Invention will be described below with reference to the schematic figures the drawings specified embodiments closer explained. Show it:

1 a partial sectional view of a compressor housing of a turbocharger according to the invention;

2 a schematic sectional view BB of the compressor housing, wherein the compressor housing is provided with a groove for generating a Vordralls according to an embodiment of the invention; and

3 a schematic sectional view of a compressor housing, according to a second embodiment of the invention.

In all figures are the same or functionally identical elements and devices - if nothing else is indicated - with the same reference numerals been provided.

In 1 is a side sectional view of a compressor 10 a turbocharger shown. The compressor 10 here has a compressor housing 12 with a compressor spiral 15 on. In the case 12 is a compressor wheel 14 with compressor blades 13 rotatably mounted on a shaft.

The compressor housing 12 has a first air channel according to a first embodiment of the invention 18 or a feeder on. About the first air channel 18 This air or bleed air is in the compressor 10 directed to move a surge line, for example, towards smaller mass flows.

The bleed air can in this case, for example, via a sampling point 20 for air in the spiral 15 of the compressor housing 12 taken and / or also at the height of the diffuser and / or behind the wheel outlet or at any other point in the turbocharger housing, which is adapted to take air. About the first air channel 18 the bleed air is the compressor 10 supplied before the Verdichterradeintritt to shift the surge limit and thereby to produce before the Radeintritt a Vordrall, which is suitable that so-called. "Pumping" of the compressor 10 to prevent or at least reduce.

It is in the field of compressor feed in one embodiment of the invention, as in 1 is shown, for example, a groove 16 provided via which the bleed air via the first air duct 18 in the compressor housing 12 is initiated. The groove 16 is in this case, for example, substantially circumferential or at least partially circumferential on the inside of the compressor housing 12 educated. The groove can 16 For example, be formed so that they are tapered towards its end or alternatively have the same diameter throughout. The groove 16 can be produced here by means of milling, for example.

Furthermore, the turbocharger according to the invention has a second air duct 22 on. This second air duct 22 is used to reduce excess boost pressure by blowing off (propulsion air). This happens, for example, when a rapid closing of the throttle valve in the thrust by the continuing compressor wheel 14 in the pressure system in front of the throttle, the boost pressure increases. To reduce the boost pressure is the second air duct 22 open.

The first and second air channels 18 . 22 can each be actuated via its own actuator (not shown). In a preferred embodiment, as in 1 shown, the two air channels 18 . 22 but also together via just one actuator 24 be operated.

The invention provides in this case that the actuator 24 , which controls the bleed air to the pump limit shift or the associated first air duct 18 also opens the second air channel 22 or Schubumluftkanals done.

This can be done by a valve device 26 , For example, a discharge valve, is provided, which via the actuator 24 is pressed. This discharge valve 26 or be ne actuating device 28 is arranged so that it can be moved between a position in which both air channels 18 . 22 are closed and positions in which the first air duct 18 is opened and positions in which next to the first air duct 18 also the second air duct 22 is opened until the end of both air channels 18 . 22 are fully open. The second air channel 22 In this case, for example, has a larger diameter than the first air duct 18 , since relatively large mass flows are required to be blown off, for example, when the throttle is quickly closed. At the first air duct 18 On the other hand, relatively small mass flows are supplied to the compressor for shifting the surge line, to low amounts of air.

As shown in 1 can the discharge valve 26 or its actuator 28 , Here, for example, a stamp, as far as in the direction of arrow A are moved to the left, until it is at the end of his path to the opening to the very large, second air duct 22 releases. Basically, the discharge valve 26 and its actuator 28 be formed and positioned as desired, provided that so the first and second air duct 18 . 22 open and close. It is conceivable here that the discharge valve 26 to completely blow off the propulsion air opens in a different direction than in 1 is shown.

In this way, an actuator can be saved, so that one for the two outflow channels 18 . 22 no two actuators needed. This can reduce manufacturing and assembly costs and further reduce system complexity.

According to the invention, two separate air ducts are provided for the fulfillment of the two requirements, ie the shifting of the surge limit in the range of low mass flows and high pressure, and for example the complete blowing off of the boost pressure in the case of a rapid closing of the throttle valve, ie the first and second air duct 18 . 22 , These who in a preferred embodiment, as described above, only by a common actuator 24 served.

The actuator 24 as he is in 1 may be, for example, a stepper motor with a threaded spindle or a plunger coil or a solenoid. This actuator 24 is with a control unit 25 connected. This can either be a separate control unit for the turbocharger, which is then connected to the engine control or coupled, or else the engine control itself. The actuator 24 operates the actuator 28 or the punch of the discharge valve 26 or another suitable device, which on the one hand the first air duct 18 to shift the surge line and on the other hand, the second air duct 22 can open and close to blow off air. It is desirable that the degree of opening, in particular of the first air channel 18 as very finely controlled, so that, for example, always just as much air through the first air duct 18 flows as required, for example, to prevent the pumping. For this purpose, the discharge valve 26 or its actuator 28 for example, a variable cross section, for example in the form of a conical valve seat 30 , wherein on the slope of the conical seat and the feed of the cross section of the valve 26 can be suitably adjusted to allow a predetermined air mass flow ṁ flow. However, this is just one example of an embodiment of the discharge valve 26 , The invention is not limited to this embodiment.

When designing the size of the first air duct 18 For pump limit shift, it is advantageous to choose this so that the incoming air reaches a high speed as possible, preferably substantially sound velocity, in order to impress the intake air as strong a twist as possible. The greater this swirl, the better can be a tearing off of the air flow at the front edge of the compressor blade 13 the compressor wheel 14 prevented and the further the pumping limit is shifted towards lower mass flows.

For everyday operation of a turbocharger compressor 10 However, it is also, as previously described, that it provides high boost pressure at high engine speeds, for example when driving on the highway at high speed or when overtaking. If the driver now fast off the gas, for example, because the overtaking process is complete, so must at ei In an Otto engine, the throttle valve must be closed so that less air is sucked into the cylinders because the combustion should always take place with the correct ratio of fuel and air volume. The rotor of the turbocharger, so the unit of turbine wheel, shaft and compressor 10 has in this case, however, a high speed and first further promotes fresh air in the intake of the engine - against the closed throttle. So now no pumps on the compressor 10 occurs this large air mass flow must be blown off the pressure side. In this case, the other second air duct 22 needed. The second air channel 22 is preferably made larger in diameter than the first air duct 18 and thus can also dissipate a correspondingly large or larger amount of air.

The actuator 24 is preferably arranged as described above, that this the second air duct 22 can also open, for example by further displacement of the actuator 28 or the punch to the rear or in the direction of arrow A. In principle, the movement can also be done in the other direction. By this arrangement, an actuator 24 take over both tasks.

In 2 is greatly simplified a sectional view of the compressor housing 12 according to 1 in the area of the first air duct 18 and the groove 16 shown. The groove 16 is indicated by a dashed line, with the groove 16 for example tapered to its end. The discharge valve is not shown for reasons of clarity.

The introduction of a predetermined air mass flow ṁ in the groove 16 or in the compressor housing 12 takes place via the first air duct 18 and requires control of the opening of the valve device 26 or here the discharge valve. In this way, the introduced air mass flow ṁ can be controlled to produce a Vordrall depending on the required air mass flow for the engine ṁ and pressure ratio. In this case, the discharge valve 26 be actuated or controlled so that it has a predetermined air mass flow ṁ in the groove 16 initiates.

The discharge valve 26 Here, as described above, has a variable cross-section. About the air mass flow ṁ from the discharge valve 26 the groove 16 is fed, in particular near the wall, a large pre-whirl can be generated, where as the first release phenomena can occur. In this case, a uniform pre-whirl is preferably generated over the entire circumference.

The cross section of the groove 16 is chosen, for example, so that the air mass flow ṁ preferably in a circle, ie preferably over the entire circumference is promoted or at least over part of the circumference. For example, a minimum cross-section can be chosen so that the mass flow at idle and the mass flow through the valve device 26 is provided right of the surge line is. However, the invention is not limited to this definition of a minimum cross section.

In 3 is now a schematic front view of a compressor 10 and its compressor housing 12 shown according to another embodiment of the invention. The compressor housing 12 differs from the compressor housing 12 according to 1 and 2 essentially in that instead of the groove 16 the first air channel 18 is arranged such that the air mass flow ṁ of the discharge valve 26 essentially tangential or nearly tangential into the compressor housing 12 or the compressor feed is introduced. The compressor housing 12 also shows how the embodiment in 1 and 2 , a second air duct 22 on and one discharge valve 26 and an actuator 24 for actuating the discharge valve 26 , Therefore, the apply to the 1 and 2 also made according to the execution, as in 3 is shown and will therefore not be repeated.

In principle, however, it is also conceivable to combine the designs with each other by optionally in 3 in addition a groove 16 according to the embodiment in the 1 and 2 is provided, which via the first air duct 18 the air mass flow ṁ is supplied in a substantially tangential or almost tangential direction. In the 1 and 2 can in this case according to the first air duct 18 be provided so that the air mass flow ṁ in a substantially tangential direction or almost tangential direction into the groove 16 or the compressor housing 12 is initiated.

Even though the present invention described above with reference to the preferred embodiments it is not limited to that, but to manifold ones Modifiable manner. The embodiments described above are combined with each other, in particular individual features from that.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102007051844 [0003]

Claims (15)

Turbocharger with a compressor ( 10 ), the compressor ( 10 ) a compressor housing ( 12 ), in which a compressor wheel ( 14 ), wherein - in the compressor housing ( 12 ) a first and a second air duct ( 18 . 22 ) are provided, - wherein via the first air duct ( 18 ) Air for shifting the surge limit of the compressor ( 10 ), and - whereby via the second air channel ( 22 ) Air is blown off. Turbocharger according to claim 1, characterized in that the first air duct ( 18 ) a sufficient air mass flow into the compressor ( 10 ) in order to shift the surge limit towards smaller mass flows, and preferably to produce a pre-whirl suitable for pumping the compressor ( 10 ) to prevent. Turbocharger according to at least one of claims 1 or 2, characterized in that via the first and second air duct ( 18 . 22 ) Air is blown, for example, in a rapid closing of a throttle valve connected to the turbocharger engine. Turbocharger according to at least one of claims 1 or 3, characterized in that for the first and second air duct ( 18 . 22 ) a valve device ( 26 ) is provided for opening and closing the first and second air channel ( 18 . 22 ), wherein the valve device ( 26 ) via an actuator ( 24 ) is operable. Turbocharger according to at least one of claims 1 or 3, characterized in that for the first and second air duct ( 18 . 22 ) each have their own valve device ( 26 ) is provided for opening and closing the first and second air channel ( 18 . 22 ), wherein the respective valve device ( 26 ) via an associated actuator ( 24 ) is operable. Turbocharger according to at least one of claims 4 or 5, characterized in that the valve device ( 26 ) at least in the region of the opening of the first air channel ( 18 ) has a variable cross-section to set a suitable air mass flow. Turbocharger according to at least one of claims 4 to 6, characterized in that the valve device ( 26 ) an actuating device ( 28 ), which, for example, with a conical valve seat ( 30 ) is provided, wherein on the slope of the conical valve seat, the cross section of the valve device ( 26 ) is suitably adjustable. Turbocharger according to at least one of claims 4 to 7, characterized in that the actuator ( 24 ) is actuated, for example via a stepper motor or a plunger coil or a solenoid. Turbocharger according to at least one of claims 4 or 8, characterized in that the actuator ( 24 ) via a control device ( 25 ) is controllable, wherein the control device is for example a part of the engine control or is connected as a separate part with this. Turbocharger according to at least one of claims 1 to 9, characterized in that the cross section of the first air channel ( 18 ) is chosen so that an incoming air reaches the highest possible speed, for example substantially sound velocity. Turbocharger according to at least one of claims 1 to 10, characterized in that the cross section of the second air channel ( 22 ) is greater than the cross section of the first air channel ( 18 ), wherein the cross section of the second air channel ( 22 ) is selected, for example, so that an excess charge pressure by opening the second air channel ( 22 ) and optionally the first air channel ( 18 ) can be dismantled suitably. Turbocharger according to at least one of claims 1 to 11, characterized in that the first air duct ( 18 ) is designed so that an air mass flow almost tangentially or substantially tangentially into the compressor housing ( 12 ) can be introduced. Turbocharger according to at least one of claims 1 to 12, characterized in that the compressor housing ( 12 ) a groove ( 16 ), which is connected to the first air channel ( 18 ), wherein the groove ( 16 ) is arranged for example in an area in front of the compressor impeller inlet or in the region of the compressor feed. Turbocharger according to claim 13, characterized in that the groove ( 16 ) is arranged at a predetermined distance in front of the Verdichterradeintritt, wherein the distance of the groove ( 16 ) from the compressor wheel ( 14 ) is selected for example so that the distance of the groove ( 16 ) is at least 1/4 of the diameter at the compressor inlet and at most five times the diameter at the compressor impeller inlet. Turbocharger according to at least one of claims 13 or 14, characterized in that the groove ( 16 ) at least partially or completely circulating in the compressor housing ( 12 ) is formed, wherein the groove ( 16 ) optionally to its end rejuvenated.