DE4038918A1 - Mixer for gaseous media at different pressures - is controlled electronically by transducer which causes mixing member to rotate for direct mixt. of two flows - Google Patents

Abstract

The mixing member (21) is rotatable about its axis (R) between two positions (S1, S2), connecting the air intake (15) permanently via a central duct (22) to the manifold (18). Its outer surface (23) occupies a cross-section (24) between the inlet (15) and a surrounding outer sleeve (17). Another air stream (N), at lower pressure, flows from the sleeve through mixing ducts (25, 26) into a variable Venturi duct (33). At equal pressures, the mixing member is rotated to the second position (S2) so that the two streams (N, L) are mixed directly. USE/ADVANTAGE - For turbocharged i.c. engines, without loss of pressure during mixing.

Description

The invention relates to a mixing device for gaseous media according to the Preamble of claim 1.

DE 25 21 747 describes a device for an internal combustion engine disclosed, by means of a mixing device designed as a jet pump a low pressure exhaust gas flow into one of a turbocharger compressor feeds promoted charge air flow of higher pressure. The charge air flow is thereby by a flap at its downstream end Cross section changeable air intake into the jet pump. This End is surrounded coaxially spaced by a jacket tube through which the exhaust gas stream is fed. The jacket tube is adjacent to the end conical in cross-section, so that an annular, nozzle-like Passage cross section formed between the casing tube and the flaps is. The ratio of the exhaust gas flow fed in to the charge air flow becomes by the position of the size of the passage cross-section Flaps set.

From DE 34 20 015 an internal combustion engine is known, the two Turbocharger-containing supercharger system as a supercharger is switched. In a first speed range of the internal combustion engine a turbine cut-off valve shuts off the second turbocharger, so that the entire exhaust gas flow drives the compressor of the first turbocharger, the compressed air is supplied to all cylinders.

When a certain speed is reached, the turbine cut-in valve opens the second turbocharger starts up, the compressed air of which is first through Check valve blocked and by an upstream arranged Ventilation valve is supplied to the air filter of the internal combustion engine. If the pressure upstream of the check valve reaches a certain value, opens this and the internal combustion engine are operated in double-charger mode. The The two charge air flows are mixed in a T-shaped pipe section, which leads into a common manifold.

The invention has for its object a mixing device for gaseous media of different pressure in an internal combustion engine create, the mixing is as lossless as possible.

This object is achieved with the features of claim 1. One arranged in the passage cross section, at least in two Positions rotatable mixing body, connects in both positions by means of a central flow channel, the air inlet line with the Manifold. The second gas stream is mixed in via the outgoing outer mixing surface of the mixing body, depending on Position of the mixing head an almost unhindered, low-loss access allow the gas flow into the manifold or the gas flow to a Lead inflow point, which is narrowed like a nozzle and in the charge air flow lies.

At different pressures in the jacket pipe and the air inlet pipe the mixing takes place in the inflow point, due to its nozzle-like Narrowing accelerates part of the charge air flow and high pressure thus lowering its pressure to such an extent that the gas flow is of low pressure can be added.

Advantageous embodiments of the invention are in the subclaims named. At the same or almost the same pressure of the charge air flow and further The gas flow is mixed via mixing channels, the Outlet cross sections are at least the same size as theirs Inlet cross sections, d. H. the pressure of the gas flow is in the Mixing channels not affected.

With different pressure between charge air flow and the further gas flow is the mixing through admixture channels opening in the inflow point enables whose outlet cross-sections are significantly smaller than theirs Inlet cross-sections. The geometric interpretation of the narrowing in the The inflow point and the inlet and outlet cross sections are such that for a certain pressure ratio between charge air flow and gas flow Pressure in the narrowest cross section of the inflow point is lower than that of the Gas flow; this is an inflow of this flow into the charge air flow possible.  

The inflow point has a lying in the direction of the charge air flow Venturi Canal, which the part of the Charge air flow initially accelerated and thereby lowering its pressure, then picks up the further gas flow and then via one Diffuser section of the Venturi channel delays the flow, so that Mixture of partial charge air flow and gas flow and the rest of the charge air flow can be supplied.

In a further advantageous embodiment, the Venturi channel is made up of two opposing molded body formed, the distance by the Moving a molded body is changeable. The speed and Pressure drop along the Venturi canal is therefore variable and can different pressure ratios between charge air flow and gas flow be adjusted.

An electronic control unit, which parameters of the internal combustion engine processed, receives the from in the charge air line or the jacket pipe Arranged pressure transducer emitted signals and controls two Actuators, one of which is on the displaceable molded body attacks and the other by means of a pivotable lever in a backdrop of the mixing body engages. Depending on the pressure transducers emitted signals that pivots an actuator at a particular Pressure ratio the mixing body in the position in which the gas flow over the Venturi channel is mixed while the other actuator in this Position attacks on a molded body and the cross section of the Venturi channel controls. In a simplified embodiment, the two actuators as Pressure sockets trained and directly via pipelines with the charge air flow or Gas flow pressure must be applied.

In all versions, the gas flow mixed with the charge air flow can be used Exhaust gas flow of the internal combustion engine for exhaust gas recirculation or one of a second exhaust gas turbocharger arranged parallel to the first second charge air flow. This mixing device can thus advantageously be used in register charging of an internal combustion engine can be used. The at usual register charging after switching on the second turbocharger First of all, the charge air flow that is blown off to reduce efficiency is low Pressure can be immediately with the help of the inflow point of the internal combustion engine  are fed. If the second charge air pressure reaches the value of the first the mixing head is turned to the second position, in which both Charge air flows can mix immediately.

The invention is explained below by way of example with reference to figures.

Show it:

Fig. 1 shows schematically a first embodiment of the invention in section;

Fig. 2 shows schematically a section along the line II-II of FIG. 1 of a second embodiment and

Fig. 3 shows schematically a mixing device according to the invention on an internal combustion engine with supercharging.

An internal combustion engine 1 (not shown ) with two rows of cylinders 2 , 3 has a first and a second exhaust gas turbocharger 4 and 5 , each with a compressor 6 and 7 and a turbine 8 and 9 . Both cylinder banks 2 , 3 are connected to the turbines 8 , 9 via exhaust manifolds 10 . The turbines 8 , 9 each have an exhaust pipe 11 , 12 leading to a catalytic converter (not shown), the exhaust pipe 12 of the second exhaust gas turbocharger 5 being able to be shut off by means of a cut-in valve 13 . The exhaust manifolds 10 are interconnected with a cross tube 14 . The compressor 6 driven by the turbine 8 is connected with an air inlet line 15 to a mixing device 16 , while the compressor 7 is connected there by means of a casing tube 17 arranged coaxially to the line 15 . Between the mixing device 16 and the internal combustion engine 1 , a manifold 18 is arranged, which opens into an I-shaped intake manifold 19 .

The mixing device 16 has a mixing body 21 which can be rotated about an axis R in two positions S 1 , S 2 and which constantly connects the air inlet line 15 to the collecting pipe 18 by means of a central flow channel 22 . With its outer lateral surface 23 , the mixing device 16 is inserted into a passage cross section 24 formed between the air inlet line 15 and the tubular casing 17 . Starting from the lateral surface 23 , first and second admixing channels 25 and 26 are formed in the mixing body 21 , the inlet cross sections 27 and 28 of which lie in the average cross section 24 . Outlet cross sections 29 assigned to the second admixing ducts 26 lie in an opening 30 connecting the throughflow duct 22 to the manifold 18 . The first admixing channels 25 have outlet cross sections 31 at the end, which open into a nozzle-like constricted inflow point 32 located in the flow channel 22 and which are significantly smaller than the inlet cross sections 27 . This inflow point 32 has a Venturi channel 33 , in the narrowest cross-section 34 of which the first admixing channels 25 open.

In a radially extending, starting from the outer surface 23 in the direction of the throughflow 22 backdrop 35 engages pivotally supported on a plate connected to the casing tube 17 bearing block 36 a lever 37 which is pivotally connected to a first actuator 38th In a second embodiment according to FIG. 2, the venturi channel 33 is formed by two opposing shaped bodies 39 , 40 , the spacing of which from one another can be changed by displacing the one shaped body 40 . This is provided with a tubular extension 41 and slidably inserted in a receptacle 42 formed in the mixing body 21 . The extension 41 has radially extending channels 43 which connect the inlet cross section 27 to the outlet cross section 31 and thus form part of the first admixing channel 25 . A second actuator 44 acts on the extension 41 by means of a push rod 45 against a tension spring 46 arranged between the receptacle 42 and the molded body 40 . The jacket tube 17 is reduced in the region of the mixing body 21 in cross-section so that the passage cross-section 24 is formed by two opposite partial cross sections 47th

An electrical control unit 50 takes various parameters of the internal combustion engine 1 , such as. B. speed n, load L etc. on. Furthermore, signals, which are designed as pressure sensors 51 and 52 and are arranged on the air inlet line 15 and the jacket tube 17, are received and processed via connecting lines 53 . The control unit 50 controls the actuators 38 and 44 and the connecting valve 13 via further lines 54 .

In operation of the internal combustion engine 1 in a first speed range up to approximately 4000 rpm. closes the connection valve 13 the exhaust pipe 12 so that the entire exhaust gas flow of the internal combustion engine reaches the turbine 8 of the first exhaust gas turbocharger 4 via the cross pipe 14 and the exhaust pipe 11 . The compressor 6 , driven by its turbine 8 , conveys a first charge air flow L, hereinafter referred to as the main flow, through the air inlet line 15 into the mixing device 16 , the mixing body 21 of which is in the first position S 1 . The positions S 1 and S 2 are shown in FIGS. 1 and 2 on the right and left of the freehand line, respectively. The charge air flow L passes through the flow channel 22 into the collecting pipe 18 and from there via the intake manifold 19 to the cylinder rows 2 , 3 .

When a certain pressure PL in the charge air flow L is reached, the pressure sensor 51 sends a corresponding signal to the control unit 50 via the connecting line 53 , which then partially opens the connecting valve 13 . As a result, part of the exhaust gas flow reaches the catalytic converter via the exhaust pipe 12 , whereby the compressor 7 starts up and conveys a second charge air flow N, which is hereinafter referred to as a secondary flow, and is supplied to the mixing device 16 with a pressure PN via the casing pipe 17 becomes.

The bypass flows through the inlet cross sections 27 into the first admixing channels 25 and arrives at the outlet cross section 31 located in the Venturi channel 33 . A partial flow of the main flow flows through the Venturi channel 33 and is accelerated in the first, nozzle-like narrowed part of this channel 33 , as a result of which the pressure PL drops to a value below the pressure PN in the outlet cross section 31 . This means that the secondary flow can flow into the main flow. In the diffuser-like part of the venturi channel 33 located downstream of the outlet cross sections 31 , the flow is delayed and mixed into the part of the main flow which is directed past the inflow point 32 .

If the speed of the internal combustion engine 1 is increased beyond the value of 4000 rpm, the pressure PN of the secondary flow continues to increase until there is only a slight pressure drop in the venturi channel 33 . If the pressure PN reaches a value stored in the control unit 50 , the connecting valve 13 is fully opened and a signal is transmitted via the line 54 connected to the first actuator 38 , which causes the lever 37 to pivot and thus the mixing body 21 into the second position S 2 twisted.

The secondary flow supplied by the second exhaust gas turbocharger 5 now has the same pressure PN as the main flow of the first exhaust gas turbocharger 4 . The entire secondary stream is now fed into the main stream via the second admixing channels 26 . The inlet cross sections 28 connect the casing tube 17 directly to the outlet cross sections 29 located in the opening 30 .

In the second embodiment according to FIG. 2, the secondary flow in the area of the mixing body 21 is supplied to the inlet cross sections 25 and 26 via the partial cross sections 47 . Furthermore, the distance between the molded bodies 39 , 40 forming the venturi channel 33 can be changed by means of the second actuator 44 . In the first position 51 , the secondary flow is supplied via the channels 43 of the attachment 41 to the outlet cross sections 31 of the admixing channels 25 . In this operating state of the internal combustion engine 1, the pressure sensor 51 detects a low pressure PN, whereupon the control unit 50 controls the actuator 44 in such a way that the narrowest cross section 34 is small. The approach 41 is moved against the force of the tension spring 46 in the receptacle 42 . The small cross-section 34 causes a high flow velocity in the venturi channel 33 , which causes the pressure PL to drop below the value of the pressure PN.

With increasing speed of the internal combustion engine 2 and thus increasing pressure PN, the actuator 44 is controlled such that the tension spring 46 increases the distance between the shaped bodies 39 , 40 . A geometrical adaptation to a multiplicity of pressure ratios PL to PN is thus possible, the pressure PL always being kept below the pressure PN and by increasing the cross section 34 the increasingly increasing secondary mass flow can be absorbed.

As in the first embodiment of the invention, the mixing body 21 is rotated into the second position S 2 from a certain pressure ratio. At this point, the shaped bodies 39 , 40 have reached their maximum distance and the push rod 45 is no longer in contact with the attachment 41 .

The functioning of the mixing device 16 is independent of the position of the inflow point 32 in the throughflow channel 22 , ie it can also be arranged offset to the axis R.

Instead of the supply of an air stream from a second exhaust gas turbocharger described above, an exhaust gas stream of the internal combustion engine 1 for exhaust gas recirculation, for. B. in the starting phase of the internal combustion engine 1 in the mixing device 16 .

In an internal combustion engine with more than two exhaust gas turbochargers, for. B. at four turbochargers according to a mixing device 16 to merge the charge air currents of two exhaust gas turbochargers and, if necessary, a third mixer 16 combine these two streams.

With three exhaust gas turbochargers, the third charge air flow z. B. can be supplied via a further jacket tube, a corresponding number of admixture channels being formed in the mixing body 21 . For a three-stage register charging, this can be rotated into three positions by means of the actuator 38 .

The position of the mixing device 16 between the compressor 6 and the intake manifold 19 is arbitrary, and one or two charge air coolers can also be arranged in front of or behind the mixing device 16 .

In a simplified embodiment, the actuators 38 and 44 can be designed as pressure sockets which are directly pressurized with the pressures PN and PL via pipelines.

Claims (8)

1.Mixing device for gaseous media of different pressures, preferably for a first charge air flow conveyed by a compressor of an exhaust gas turbocharger in an internal combustion engine and at least one further gas flow, the charge air flow being conveyed through an air inlet line into the mixing device and the gas flow being supplied by means of a jacket pipe spaced coaxially therewith and both streams are discharged in a common manifold, and with a changeable passage cross section, formed between the air inlet line and the jacket tube, leading into the manifold, characterized by
a mixing body ( 21 ) which can be rotated at least in two positions (S 1 , S 2 ) and is arranged in the passage cross section ( 24 ) and which connects the air inlet line ( 15 ) to the collecting pipe ( 18 ) with a central flow channel ( 22 ) and
has the admixing channels ( 25 , 26 ) starting from its outer lateral surface ( 23 ), assigned to the positions (S 1 , S 2 ) and receiving the gas flow (second charge air flow N), at least one of which is narrowed in a nozzle-like manner in the first charge air flow (L) lying inflow point ( 32 ) opens. 2. Device according to claim 1, characterized in that in a first position (S 1 ) of the mixing body ( 21 ) the supply of the entire second charge air flow (N) via first admixing channels ( 25 ), the outlet cross section ( 31 ) of which is significantly smaller than their entrance cross-section ( 27 ). 3. Apparatus according to claim 1, characterized in that in a second position (S 2 ) of the mixing body ( 21 ) the supply of the entire second charge air flow (N) via second admixture channels ( 26 ), the outlet cross section ( 29 ) of which is at least the same size has as their inlet cross-section ( 28 ). 4. Device according to one or more of the preceding claims, characterized in that the inflow point ( 32 ) has a venturi channel ( 33 ) extending in the direction of the first charge air flow (L), in its narrowest cross section ( 34 ) the outlet cross sections ( 31 ) the first admixing channels ( 25 ) open. 5. The device according to one or more of the preceding claims, characterized in that the venturi channel ( 33 ) consists of two opposing shaped bodies ( 39 , 40 ), the distance between which can be changed by moving at least one shaped body ( 40 ). 6. The device according to claim 5, characterized in that the displacement of the shaped body ( 40 ) and the rotation of the mixing body ( 21 ) via an actuator ( 38 , 44 ). 7. The device according to claim 6, characterized in that the actuator ( 38 ) engages by means of a pivotable lever ( 37 ) in a link ( 35 ) of the mixing body ( 21 ). 8. The device according to one or more of the preceding claims, characterized in that the actuators ( 38 , 44 ) are controlled by an electronic control unit ( 50 ) which processes signals from sensors (pressure transducers 51 and 52 ), respectively, on the air inlet line ( 15 ) or the casing tube ( 17 ) are arranged.