EP0985092B1 - Exhaust gas recirculation device - Google Patents

Abstract

The invention relates to an exhaust gas recirculation device for recirculating exhaust gases in a gas supply line of an engine, specially a motor vehicle engine, comprising an exhaust gas supply line (5), a fresh gas supply line (2) and an outlet port (4), wherein at least the exhaust gas supply line (5) and the fresh gas supply line (2) are interconnected by means of a control member (69) to measure exhaust gas levels and a pressure plate (44) is arranged on the side of the control member (69) facing the fresh gas supply line. Said pressure plate minimizes the influence of fluctuations in pressure occurring in the exhaust and fresh gas lines and affecting the exhaust gas flow rate.

Description

The invention relates to an exhaust gas recirculation device with pressure compensation, as described in claim 1.

US-A-4 027 638 discloses such a device according to the preamble of claim 1.

Otto and diesel engines, especially those of motor vehicles usually with exhaust gas recirculation devices, in particular exhaust gas recirculation valves (EGR valves). Through them the sucked in Fresh gas partially mixed with exhaust gas to reduce NOx emissions as well to improve fuel consumption and reduce noise.

Such exhaust gas recirculation devices include metering devices or control devices, with which the amount of the recirculated exhaust gas depends on the operating point can be adjusted. Exhaust gas recirculation would be too low Missing effects, too big with petrol engines to malfunctions or one lead to and undesirable increase in HC or even CO emissions Diesel engines lead to an undesirable increase in particle emissions.

Such controls are usually fully closable valves by a vacuum membrane or a servomotor or one against a spring working proportional magnets can be set, which in turn have a Clock valve or a relay can be operated by the engine control unit. The one Information used in the control unit is usually that about load and Engine speed and the amount of air drawn in. To improve the Working will also be the feedback of the opening path via a path measuring system applied.

The exhaust gas recirculation devices are located between the fluctuating pressures in the exhaust system and the fluctuating pressures in the intake system of the Motors, the changes in these pressures on the one hand with the changes of the operating point, on the other hand from intermittent escaping of the exhaust gas and intermittent suction of the fresh gas can be determined.

These pressure fluctuations already represent the metering function of the exhaust gas recirculation device a problem with naturally aspirated engines and are with supercharged ones Motors particularly serious.

JP 06 147 025 (Patent Abstract of Japan) shows an exhaust gas recirculation device such as it is described in the preamble of claim 1. Here, exhaust gas from an internal combustion engine fed to a double valve via two exhaust gas inlets. The Double valve consists of two valve plates rigidly attached to a valve rod, which the exhaust gas feeds each from a common exhaust gas recirculation channel separate, the one valve plate for opening the valve along the exhaust gas flow direction and the other valve plate against the exhaust gas flow direction must be moved.

US-A-4 027 638 discloses an exhaust gas recirculation valve which allows metering of Exhaust gas into the fresh gas stream of an internal combustion engine by means of a Flußregelventilserlaubt. On the fresh gas side of this flow control valve is a Pressure control valve arranged. The pressure control valve is from a Actuating rod closed accordingly if the above the Flow control valve applied gas pressure difference increases. Closing the Pressure control valve leads to such a gas pressure increase between the Flow control valve and the pressure control valve that the pressure difference over the Flow control valve is reduced. This essentially ensures one constant gas pressure difference via the flow control valve.

It is an object of the invention to provide an exhaust gas recirculation device where the throughput or metered amount of exhaust gas is as independent as possible from the above pressure fluctuations acting on the exhaust gas recirculation device is.

The object is achieved by an exhaust gas recirculation device with the in the claim 1 specified features solved.

An exhaust gas recirculation device according to the invention for recycling Exhaust gas in a gas supply of engines, especially automotive engines, includes an exhaust gas supply, a fresh gas supply and one in the Gas supply outlet channel, at least the exhaust gas supply and the fresh gas supply with each other via a metering or control element Connect and on the fresh gas supply side of the Control element a pressure plate is arranged, the influence of on the exhaust gas - and fresh gas side occurring and affecting the exhaust gas flow Pressure fluctuations minimized and preferably eliminated.

The control element is located, in particular through a valve or main valve can be formed in a partially or fully open position, can exhaust gas from the exhaust side of the exhaust gas recirculation device in the direction flow on the fresh gas side. The pressure plate is in the gas or exhaust gas flow arranged in the exhaust gas recirculation device that they have a flow resistance for the exhaust gas flow flowing around or flowing through them and so when flowing through the exhaust gas from the exhaust side towards the fresh gas side for a partial build-up or an increase in the pressure of the exhaust gas flow leads. In this case, therefore, the gas pressure is in a space between the Control unit and the pressure plate larger than in a room on the fresh gas side is arranged by the pressure plate. The difference between these fresh gas and gas pressures acting on the pressure plate on the exhaust side result in a Force that acts on the pressure plate. This force acting on the pressure plate is used according to the invention to influence or control the position or of the free opening cross section of the control member can be used so that for example, the free opening cross section of the control member is reduced if one in the direction of the fresh gas side or in the closing direction of the control member directed force on the pressure plate increases. The pressure plate can thus be designed such that an increase in the pressure differential between exhaust gas and the fresh gas side of the exhaust gas recirculation device to a predetermined Reduction of the free opening cross section of the control gear and one Reduction of this pressure drop to a predetermined increase in the leads free opening cross section of the control member.

In this way, the influence of flue gas and fresh gas side fluctuations or variations of the gas pressure in the exhaust gas recirculation device the throughput or the measurement of the recirculated exhaust gas or on the The proportion of exhaust gas in the gas stream in the outlet channel is minimized and preferably completely be eliminated.

According to a preferred embodiment of the invention, the control member with a mechanical, pneumatic, hydraulic, magnetic or electrical actuator or servomotor connected. Particularly advantageous the use of a magnet or a proportional magnet has proven to be because with such the opening or position of the control member very precisely is set and, above all, it also reacts quickly.

According to a further preferred embodiment, the exhaust gas recirculation device is provided with a compensation device for compensation or to balance forces resulting from a difference between exhaust gas side and fresh gas side gas pressure act on the control element. The Pressure drop in the gas pressure via the control member can be due to this compensation device not lead to a force component that is in the direction of a undesired opening or closing of the control member acts, causing the desired control or regulation of the amount of exhaust gas enforced considerably is improved. A second can in particular be used as the compensation device Valve plates or pistons, membranes and / or bellows are used.

It is advantageous here that the compensation device on one side with the exhaust gas pressure, i.e. the gas pressure prevailing in the exhaust gas supply to act on and on the other hand with the fresh gas side Gas pressure, i.e. that on the fresh gas side of the control member and thus between Main valve and pressure plate prevailing gas pressure. Which resulting pressure difference across the compensation device results in a Force component that opposes the force component to be compensated is the same amount and thus a balance of the two Power components causes.

According to a further preferred embodiment, the compensation device with a kinematic transmission, in particular a lever transmission, provided. This translation translates that from the compensation device generated force component to a size that is used for the compensation of the force to compensate for the control member is suitable. This is particularly so advantageous if the areas or areas effective for the gas pressures differ from compensation device and control body.

According to a further preferred embodiment, the compensation device, the control element and the pressure plate are connected to one another in an effective manner and controllable via the control device. In this way, those of the Compensation device, the pressure plate and generated by the actuator Forces work together on the control body and become suitable add or compensate to the desired net force or force component to exercise on the tax body.

According to a further preferred embodiment, it has proven to be advantageous proved to provide a stationary stowage plate in order to allow direct inflow an exhaust gas stream flowing from the control member towards the pressure plate prevent. The effect of an undesirable back pressure portion on the Pressure plate can be eliminated in this way. The baffle plate is typically used for this arranged such that the exhaust gas stream flowing out of the control member is not flows directly onto the pressure plate, i.e. that there is no undesirable Impulse transfer of the inflowing exhaust gas stream comes to the pressure plate.

According to a further preferred embodiment, the control member by a spring action of a membrane or bellows in the closing direction biased, in particular in addition a spring to support the Preload can be provided to add an additional force component To effect the closing direction of the control member.

The pressure plate can advantageously be arranged and designed in such a way that that the gas or exhaust gas essentially through precisely defined openings in the pressure plate flows and as little gas as possible around its outer circumference can step around, i.e. little gas between the pressure plate and one on it adjacent wall can flow, but instead the gas flow through openings designed for this purpose are guided in the printing plate itself. These openings are in particular according to acoustic, fluidic and mechanical aspects.

Furthermore, an execution of the printing plate is possible, in which this additional equipment is equipped so that with a small gas pressure gradient or small pressure differences between the exhaust side and fresh gas side gas pressures on the pressure plate the exhaust gas around the outer Circumference of the pressure plate can flow around, with growing or larger Differences in pressure, however, released additional gas passage openings through which the gas flow can flow. This will be a additional and advantageous degree of freedom for tuning according to acoustic, fluidic and mechanical aspects created.

An exhaust gas recirculation device is preferred in which a gas pressure in one Internal valve compensation space from the interaction of an internal valve with an opening gap between the piston and a guide sleeve of the Piston is controlled, with the inner valve by the actuator and / or an additional inner valve actuating device is actuated. The vote the diameter of the piston relative to that of the control element, for example of the main valve also affects the tuning of the inner valve to that Opening gap between the piston and the guide sleeve.

Figur 1

eine schematische Querschnittsdarstellung einer erfindungsgemäßen Abgasrückführungseinrichtung mit einer Druckkompensationsleitung;

Figur 1A

eine schematische Querschnittsdarstellung einer weiteren Ausführungsform der Erfindung mit einer abgasführenden Druckkompensationsleitung und einem Doppelventil;

Figur 2

eine schematische Querschnittsdarstellung einer weiteren Ausführungsform der Erfindung mit einer Drosselklappe als Steuerorgan;

Figur 3

eine schematische Querschnittsdarstellung einer weiteren Ausführungsform der Erfindung mit zwei entgegengerichteten Ventilen;

Figur 4

eine schematische Querschnittsdarstellung einer weiteren Ausführungsform der Erfindung mit einem Kugel-, Kegel- oder Zylinderventil;

Figur 5

eine schematische Querschnittsdarstellung einer weiteren Ausführungsform der Erfindung mit einer Membran und einer Hebelübersetzung;

Figur 6

eine schematische Querschnittsdarstellung einer weiteren Ausführungsform der Erfindung mit einer Membran und einer Hebelübersetzung;

Figur 7

eine schematische Querschnittsdarstellung einer weiteren Ausführungsform der Erfindung mit einer Membran und einer Hebelübersetzung;

Figur 8

eine schematische Querschnittsdarstellung einer Ausführungsform einer Druckplatte;

Figur 9

eine schematische Querschnittsdarstellung einer weiteren Ausführungsform einer Druckplatte;

Figur 10

eine schematische Querschnittsdarstellung einer weiteren Ausführungsform der Erfindung mit einem Balg;

Figur 11

eine schematische Querschnittsdarstellung einer weiteren Ausführungsform der Erfindung mit einem zwecks Druckkompensation über einen hohlen Ventilkörper beaufschlagten Kolben;

Figur 12

eine schematische Querschnittsdarstellung einer weiteren Ausführungsform der Erfindung mit einem zusätzlichen inneren Ventil;

Figur 13

eine schematische Querschnittsdarsteliung einer weiteren Ausführungsform der Erfindung mit einem zusätzlichen inneren Ventil;

Figur 14

eine Querschnittsdarstellung einer weiteren Ausführungsform der Erfindung mit einer zusätzlichen ortsfesten Stauplatte; und

Figur 15

eine Querschnittsdarstellung einer weiteren Ausführungsform der Erfindung ähnlich zu Figur 12 mit einem zusätzlichem Topf.

The invention is described in more detail below with reference to preferred embodiments, for example. Show it:

Figure 1

is a schematic cross-sectional view of an exhaust gas recirculation device according to the invention with a pressure compensation line;

Figure 1A

is a schematic cross-sectional view of another embodiment of the invention with an exhaust gas-carrying pressure compensation line and a double valve;

Figure 2

is a schematic cross-sectional view of another embodiment of the invention with a throttle valve as a control member;

Figure 3

is a schematic cross-sectional view of another embodiment of the invention with two opposite valves;

Figure 4

is a schematic cross-sectional view of a further embodiment of the invention with a ball, cone or cylinder valve;

Figure 5

is a schematic cross-sectional view of a further embodiment of the invention with a membrane and a lever transmission;

Figure 6

is a schematic cross-sectional view of a further embodiment of the invention with a membrane and a lever transmission;

Figure 7

is a schematic cross-sectional view of a further embodiment of the invention with a membrane and a lever transmission;

Figure 8

is a schematic cross-sectional view of an embodiment of a pressure plate;

Figure 9

a schematic cross-sectional view of a further embodiment of a printing plate;

Figure 10

is a schematic cross-sectional view of a further embodiment of the invention with a bellows;

Figure 11

is a schematic cross-sectional view of a further embodiment of the invention with a piston acted upon for the purpose of pressure compensation via a hollow valve body;

Figure 12

is a schematic cross-sectional view of a further embodiment of the invention with an additional inner valve;

Figure 13

a schematic cross-sectional representation of a further embodiment of the invention with an additional inner valve;

Figure 14

a cross-sectional view of another embodiment of the invention with an additional stationary storage plate; and

Figure 15

a cross-sectional view of another embodiment of the invention similar to Figure 12 with an additional pot.

In the following, all are the same for the sake of simplicity of illustration or the same features of the different embodiments referred to uniform reference numerals.

Figure 1 shows schematically a cross section of a first embodiment of the Exhaust gas recirculation device according to the invention. The exhaust gas is by means of a Exhaust gas duct or exhaust gas supply 5, one side of which is in the main exhaust gas stream of the engine opens, fed to the exhaust gas recirculation device. The exhaust gas supply 5 is via a valve or main valve 60, which consists of a valve plate 60A and a valve seat or wall 60B, with a chamber 3 connected. On the fresh gas side, the chamber 3 is partially through a pressure plate 40 closed, which represents a flow resistance for gas or exhaust gas.

Gas passage openings (not shown) from the chamber 3 into an opening 1 can between the outer periphery of the pressure plate 40 and a Wall 8 or be formed in the pressure plate 40 itself. The confluence 1 of the recirculated exhaust gas flow is with a fresh gas supply 2 and a Output channel 4, which carries on the fresh gases mixed with the exhaust gas, connected.

In an upper wall 9 of the exhaust gas supply 5 there is a compensation space or Piston chamber 10 for receiving a compensation piston or compensation piston or piston 80 provided. The piston 80 lies against its circumference a wall or side wall 11 and is via a spring or spiral spring 6 connected to an upper part of the wall 11. The piston chamber 10 is over a Line or equalization line 12 connected to the chamber 3 in such a way that can quickly compensate for the gas pressures in the piston chamber 10 and the chamber 3.

Piston 80, valve plate 60A and pressure plate 40 are together in this order connected via a rod 13. On a piston 80 opposite Side of the rod 13 is an actuator in the form of an electrical Magnets or proportional magnets 14 arranged, via which the main valve 60 can be controlled or regulated.

The gas pressure in the mouth 1 of the recirculated exhaust gas flow into the fresh gas is p ₃ under operating conditions, the gas pressure p ₃ ′ prevails in the chamber 3 between the valve plate 60A and the pressure plate 40, and the gas pressure p _{5 is} present in the exhaust gas supply 5. In all operating points of a naturally aspirated engine relevant for exhaust gas recirculation, p ₅ > p ₃ applies. A positive, ie reverse, purge gradient p ₅ <p ₃ may occur when the engine is mechanically or turbocharged.

Due to the flow resistance connected to the pressure plate 40, when the main valve 60 is open there is an increase in the gas pressure p ₃ 'in the chamber 3 compared to the gas pressure p ₃ in the mouth 1. Thus p ₅ > p ₃ '> p ₃ applies.

When the exhaust gas recirculation or main valve 60 is opened, the exhaust gas will therefore generally flow in the desired direction, ie from the exhaust gas supply 5 in the direction of the junction 1. The amount of exhaust gas passed through essentially depends on the opening cross section of the main valve and on the gas pressure drop across the main valve 60, ie on the pressure difference p ₅ -p ₃ '.

The pressure plate 40 serves to minimize the influence of this pressure gradient or this pressure difference p ₅ -p ₃ or p ₅ -p ₃ 'on the amount of exhaust gas that is passed through. By a suitable choice of the shape and diameter of the pressure plate 40 and a design of the gas transfer from the Chamber 3 for the mouth 1 between a chamber wall or wall 8 and the outer circumference of the pressure plate 40 and / or through the pressure plate 40, can be achieved that the free opening cross section of the main valve when increasing or decreasing the pressure gradient p ₅ - p ₃ 60, that is to say the opening cross section between the valve plate 60A and the valve seat 60B, is reduced or increased precisely by such an amount that the recirculated exhaust gas quantity does not change with the above pressure fluctuations or changes in the pressure difference and a determinable or predetermined size has or so that the exhaust gas portion in the outlet channel 4 downstream of the mouth ung 1 remains constant and has a determinable or predetermined size. The throughput of the recirculated exhaust gas quantity is therefore essentially independent of the fluctuations or variations of fresh and exhaust gas pressure (p ₅ and p ₃ ) at the exhaust gas recirculation device, ie essentially independent of changes in the gas pressure difference or the pressure drop p ₅ - p ₃ ,

In order to make the throughput, recirculated exhaust gas quantity largely independent of the pressure drop p ₅ -p ₃ by such a design of the pressure plate 40 and the gas transfer thereon, it is advantageous to make the force contribution of the force acting in the rod 13 due to the pressure drop p ₅ -p ₃ 'to compensate so that this force contribution does not lead to an undesired opening or closing of the main valve 60, which would make the desired control or regulation of the exhaust gas throughput with the pressure plate 40 more difficult.

This force acting in the rod 13 is strongly dependent on the pressure drop p ₅ - p ₃ 'via the main valve 60. When the main valve 60 is closed, the force which results from the pressure drop p ₅ -p ₃ and a cross-sectional area or cross section F _{3 of} the valve plate 60A acts without the piston 80 and without the line 12 in the rod 13. In a first approximation, the force acting in the rod 13 is through when the valve is open (p 5 - p 3 ') x F 3 + (p 3 '- p 3 ) x F 4 + C 6 x p 6 given, F _{4 is} an effective cross-sectional area of the pressure plate 40 and C ₆ denote the spring constant of the spring 6 and S ₆ their deflection from the equilibrium position. Here, the magnet or proportional magnet 14 initially does not exert any force on the rod 13.

A compensation of the force (p 5 - p 3 ') x F 3 takes place by the piston 80, which has the same effective area or contact area F ₃ for the gas pressure as the valve plate 60A. A force of the same amount counteracting the force on the valve disk 60A thus acts on the piston 80.

The actuation of the main valve 60 of the exhaust gas recirculation device is preferred essentially by the electrical proportional magnet 14 over the rod 13 achieved, with the proportional magnet 14, the force only from Coil current and is not dependent on the position of the armature. Such The arrangement has the advantage that it responds quickly and a valve lift or Opening the valve 60 can be adjusted very precisely. But it is also possible other actuations of the main valve 60, such as mechanical, pneumatic, hydraulic and electromotive with the described pressure compensation to combine.

1A shows a further embodiment of the invention, in which a further possibility of compensating for the force acting in the rod 13 (p ₅ -p ₃ ') x F ₃ is a second valve plate 60A', preferably of slightly larger diameter than the valve plate 60A must be provided in order to precisely compress the force acting on the valve plate 60A. This valve plate 60A requires an exhaust gas-carrying, ie sufficiently dimensioned, compensation line 12A into space 3.

Further possibilities of compensating the force acting in the rod 13 (p ₅ - p ₃ ') x F ₃ are to use valves or main valves which operate in the same or almost the same way and simultaneously or almost simultaneously in the direction of the exhaust gas flow and in Open the opposite direction to it.

Another embodiment based on such pressure compensation the invention is shown in FIG. In the simplest way, this can be done as A metering or control member 61 find a throttle valve 61A which is connected to the rod 13 via a lever 15. It is advantageous here that the desired pressure compensation with the simplest mechanical design is possible. The disadvantage, however, is that the 61 A formed with the throttle valve Valve or main valve 61 is not hermetically gas-tight when closed is.

Figure 3 shows a further embodiment of the invention. Here is a Another possibility of pressure compensation used, in which a valve plate 62A of a main valve 62 on an arc in the exhaust gas flow direction and another valve plate 62 linear, but opposite to the exhaust gas flow direction to be led. One of the valve plates 62A is in this case on an L-shaped one Lever 19, which is pivotally connected to the rod 13, fixed the lever 19 in the middle of a fixed wall projection 17 is pivotally mounted. The other valve plate 62A is at the upper end of the Set rod 13. The arrangement of the lever 19 and that for the gas pressure effective areas of the valve plate 62A are selected so that the the rod 13 acting forces due to the pressure differential between the Compensate exhaust gas supply 5 and chamber 3. Instead of circular orbits and one To use linear valve plate filling, there are also two linear valve plate guides or two circular path guides possible.

Figure 4 shows a further embodiment of the invention similar to Figure 2, at which is provided as a main valve, a ball, cone or cylinder valve 63 to to enable the desired pressure compensation.

FIG. 5 shows a further embodiment of the invention, which seeks to overcome the disadvantages of the embodiment with the piston 80 described with reference to FIG. 1. In the embodiment described with reference to FIG. 1, completely mechanically frictionless operation of the piston 80 is not possible and, with the main valve 60 closed, there can still be a connection between the exhaust gas supply 5 and the junction 1, so that exhaust gas can still flow to the intake side of the engine. This can be prevented by replacing the piston 80 with a membrane 81 which has the same or a different effective area or cross-section as the piston 80. If the effective area F ₈₁ of diaphragm 81 is different, for example larger, a translation or reduction must be created between diaphragm 81 and rod 13. In the embodiment of FIG. 5 is a lever transmission with a lever arm 21 which is pivotally mounted on one side on a projection of the wall 8 and which can be brought into engagement with the rod 13 on both sides (alternative A) or on one side (alternative B). The compensation force that arises due to the pressure drop across the diaphragm 81 is transmitted to the rod 13 with a compensation arm, which is connected to the diaphragm 81 on the one hand and pivotably to the lever arm 21 on the other hand, in accordance with the predetermined translation. In the case of one-sided engagement according to alternative B, the lever arm 21 can only take the rod 13 in the opening direction of the main valve 60, ie there is a one-sided decoupling of the diaphragm 81 from the main valve 60. The larger force F ₈₁ xp ₅ is translated down to the old compensation force of the piston F ₈₀ xp ₅ .

A corresponding embodiment with a lever ratio is also in Versions with pistons are recommended if their effective surfaces deviate from those of the main valve. Leverage kinematics is particularly useful for Functional membranes, which can usually only make smaller strokes.

Figures 6 and 7 show further embodiments of the invention. Here, in order to achieve installation space advantages and cost savings or possible ones To eliminate causes of damage, an embodiment proposed that without the line 12 of the embodiment described with reference to FIG. 1 gets along. In place of the wall 60B supporting the valve seat, there is one Membrane 82 is provided which separates the exhaust gas supply 5 from the chamber 3. A valve seat of a valve plate 64A of a main valve 64 is here in the Membrane 82 formed. The exhaust gas to be recycled flows through a hollow one Pressure plate body or around the pressure plate 41 in the direction of the confluence 1.

In the embodiment of Figure 6 is a fulcrum 23 for a lever transmission 24 rigidly connected to the fixed pipelines via a star 25.

In the embodiment shown in Figure 7, the rotatably mounted Lever 27 actuated via rods 28 which, for reasons of gas resistance in the Mouth 1 expediently in the direction of flow from the fresh gas supply 2 to the outlet channel 4 in front of and behind the rod 13. The Lever mechanism 27 is here because of the risk of contamination and corrosion as well as for temperature reasons from the area caused by exhaust gas is rinsed. The translated compensation force is in turn over the bar 13 transferred to the valve plate of the main valve 64 and leads to a Compensation of the force component to be compensated.

FIG. 8 shows an expedient embodiment of the hollow pressure plate or of the pressure body 41, which for those described with reference to Figures 6 and 7 Embodiments are provided. From acoustic, mechanical and fluidic Voting reasons, it can be advantageous that possible little exhaust gas around the outer edge or outer circumference of this pressure body 41 but mainly through the designated flow openings or gas passage openings 29, which can be designed like a nozzle.

Figure 9 shows that the wall 8 'comprising the pressure plate 42 for reasons of coordination can also be shaped differently than purely cylindrical.

Figure 10 shows a further embodiment of the invention. In this case, a bellows 84 is provided in the exhaust gas supply 5, which is attached on one side to a valve plate 65A of a main valve 65 and on its other side opposite in the longitudinal direction on the upper wall 9 of the exhaust gas supply 5. The valve plate 65A has a passage opening 30, which connects the chamber 3 to the interior of the bellows 84 in a gas-permeable manner, as a result of which a pressure equalization can form between the chamber 3 and the interior of the bellows 84. If the pressure drop p ₅ -p ₃ 'increases, the bellows 84 contracts in its longitudinal direction, as a result of which a force is exerted on the valve disk 65A in the opening direction of the main valve 65. The bellows 84 should be designed so that this force takes over the pressure compensation function.

Such an embodiment can be advantageous if membranes with sufficient membrane stroke (bellows) are available. For example, lets this results in low friction and no hysteresis achieve; in addition, the bellows 84 can advantageously also act as a closing spring of the main valve 65 act.

An embodiment based on this is also possible with a piston 85 instead of a bellows, as shown in FIG. A hollow valve body 66A of a main valve 66 connects the chamber 3 in a gas-permeable manner to the compensation chamber 10, which receives the piston 85, whereby the compensation of the force associated with the pressure drop p ₅ -p ₃ 'is possible. However, in this embodiment the piston-specific disadvantages of friction and incomplete tightness occur again.

An embodiment according to FIG. 12 can therefore be advantageous, in which the hermetic seal between the exhaust gas supply 5 and the junction 1 is not produced by a sealing ring 31 on the piston 85 as in FIG. 11, but by an inner valve 32 within the main valve 67 , The inner valve 32 is opened with a forward stroke of the rod 13, which is caused by the actuating device, in particular by an electric magnet or proportional magnet 14. As long as the inner valve 32 is closed, the pressure drop p ₅ -p ₃ keeps the inner valve 32 and thus the main valve 67 closed. If the inner valve 32 is opened by the preliminary stroke, there is a throttling point between the outer circumference of the piston 86 and the wall 11, the cross section of which must be small in comparison with that of the passage opening 30 in the valve body 67A, above the piston 86 in the compensation space 10 the pressure p ₃ ', whereby the pressure equalization is established. The pressure compensation can be influenced by the choice of the diameter ratio of the effective area of the piston 86 to that of the valve disk 67A and by the ratio of the opening cross sections of the throttle point and the inner valve 32.

FIG. 13 shows a further embodiment of the exhaust gas recirculation device Pressure compensation similar to the embodiment shown in FIG. 12, with the difference that here the main valve 68 together with valve plate 68A with an inner valve 32 not exclusively by the spring 6, but is also forcibly taken from the rod 13 in the closing direction.

FIG. 14 shows a particularly preferred embodiment of the exhaust gas recirculation device with pressure compensation with an inner valve 34, the is opened during the forward stroke of the rod 13. The inner valve 34 has here a conical or preferably hemispherical valve disc. On in the upper region of the rod 13 attached pin 35 has the task of a Raise the main valve 69 after the preliminary stroke to open the inner valve 34. Instead of actuating the inner valve in this way via the actuating device 14 can optionally also be provided for the actuation of the inner valve Internal valve actuating device can be provided that operate independently of main valve and inner valve enabled (not shown).

A protective sleeve or sleeve 36 can optionally be provided, which protects the sliding fit of the piston 89 in a guide sleeve 37 against contamination. A cover 38 is designed or provided with a separate filler in order to make a space above the main valve 69, which represents an inner valve compensation space 10 ', as small as possible, so that the desired pressure (p ₅ in the closed and p ₃ ' in open state) is formed as quickly as possible and as little exhaust gas as possible can enter this inner valve compensation space 10 '. The gas pressure in the inner valve compensation space is denoted by p ₁₀ '. If advantageous for coordination and / or against contamination, a sealing ring 50, which partially seals an opening gap between the piston 89 and the guide sleeve 37, can be used. In order to facilitate the threading of the piston 89 into the guide sleeve 37, the latter has been chamfered at its lower end on the inside diameter thereof. A baffle plate 52 is provided in order to eliminate the distorting effect of the dynamic pressure of the gases flowing from the opening cross section of the main valve 69 on a pressure plate 44, ie it is to be prevented that the flowing through the main valve from the exhaust gas supply 5 in the direction of the mouth 1 Exhaust gas stream flows directly onto the pressure plate 44, since this can have an undesired impulse transfer with a falsifying effect on the control properties of the exhaust gas recirculation device. It has proven to be particularly advantageous to pull a collar 53 of the storage plate 52 into the main valve 69 as high as possible. The storage plate 52 can advantageously take over the upper guidance of the rod 13 at the same time. Such upper guidance of the rod 13 is also possible through the pressure plate 44, the pin 35, a membrane or a bellows.

It has proven advantageous to have openings or gas passage openings 29 ' to be formed in the pressure plate 44 as spring-loaded valves. Such Embodiment is shown in Figure 14, in which the gas passage openings 29 'are covered by resilient tongues 55 of different spring stiffness.

The tongues 55 are fixed on one side of the pressure plate 44. A further refinement of the vote is possible through the number of openings 29 'and by the choice of the diameter of the gas passage openings 29 '.

An embodiment is also advantageous in which the gas passage openings 29 'are chosen to be sufficiently large from the outset and are closed with a spring-loaded plate or sealing plate 56 which seals at their edges, as shown in the embodiment shown in FIG. Depending on the pressure difference p ₃ '- p _{3, the} sealing plate 56 opens more or less into a pot 58 surrounding it, whereby it opens up elongated openings or passages 59, the opening characteristics of which are to be determined during the tuning. As long as they remain constant, the shape of such passages can even be used to implement any force-throughput characteristics.

Depending on the coordination of the diameter ratios of the pistons or membranes or bellows 80-89 to the respective main valves 60-69, pressures p ₃ > p ₅ , which can occur, for example, in the event of a positive purge gradient due to a turbocharger or when a motor is mechanically charged the valves 60, 64, 65, 66, 67, 68, 69 open, which would lead to loss of charge air. One way to counteract this is to reverse the polarity of the magnet when using a permanent magnet as an armature or a corresponding measure if an electromotive, pneumatic, hydraulic or mechanical actuation of the inner valves is provided as the actuating device.

Another possibility in the embodiments shown from FIG. 12 is to simply open the inner valve 32 or 34 at such operating points via the magnet or the corresponding actuating device. The pressure p ₃ , which is higher than p _5, would then be present below the main valve 67 to 69 in the chamber 3 and above the piston 86 or 89, so that the main valve 67 to 69 could be closed by a spring, for example. The slight charge air loss via a throttle point between the guide sleeve 11 or 37 and the piston 86 or 89 is manageable.

LIST OF REFERENCE NUMBERS

1.

junction

Second

Fresh gas supply

Third

chamber

4th

output channel

5th

exhaust gas supply

6th

feather

6 '.

feather

8th.

wall

8th'.

wall

9th

wall

10th

compensation chamber

11th

top wall

12th

compensation line

12A.

compensation line

13th

pole

14th

Magnet or proportional magnet

15th

lever

17th

wall lead

19th

lever

21st

lever arm

23rd

pivot point

24th

leverage

25th

star

27th

lever

28th

rods

29th

Gas openings

29 '.

Gas openings

30th

passage opening

31st

sealing ring

32nd

inner valve

33rd

inner valve

34th

inner valve

35th

pen

36th

protective sleeve

37th

guide sleeve

38th

cover

40th

printing plate

41st

pressure vessels

42nd

printing plate

44th

printing plate

50th

sealing ring

52nd

baffle plate

53rd

collar

55th

tongues

56th

sealing

58th

pot

59th

openings

60th

main valve

60A.

valve plate

60A '.

valve plate

60B.

Valve seat or wall

61st

main valve

61A.

throttle

62-69.

main valve

62A-69A.

valve plates

80th

piston

81-82.

membrane

84th

bellows

85th

piston

87-89.

piston

Claims (11)

1. Exhaust gas recirculation device for recirculating exhaust gas into a gas feed to engines, especially motor vehicle engines, having an exhaust gas feed (5), a fresh gas feed (2) and an outlet duct (4) opening into the gas feed, where at least the exhaust gas feed (5) and the fresh gas feed (2) are interconnected via a control means (60-69) having an adjustable free opening cross section for metering exhaust gas, where, on the side of the control means (60-69) facing the fresh gas feed, there is arranged a pressure plate (40-44) which minimizes the influence of pressure fluctuations that occur on the exhaust gas side (p₅) and fresh gas side (p₃, p₃') and have an effect on the exhaust gas throughput characterized in that the pressure plate (40-44) is designed in such a way that the difference between the gas pressures acting on the fresh gas side and exhaust gas side of the pressure plate (40-44) results in a force which acts on the pressure plate and which is used to set the free opening cross section of the control means (60-69) and therefore minimizes the influence of the pressure fluctuations.
2. Exhaust gas recirculation device according to Claim 1, where the control means (60-69) can be actuated by a mechanical, pneumatic, hydraulic, magnetic or electric actuating device (14), especially an electromagnet or proportional magnet (14).
3. Exhaust gas recirculation device according to Claim 1 or 2, where a compensation device (80; 81; 82; 84; 85; 86; 89) is provided, especially in the form of a piston (80; 85; 86; 89), a diaphragm (81) and/or a bellows (84), in order to compensate for forces which act on the control means (60-69) on account of a pressure difference between gas pressures (p₅- p₃, p₅ - p₃') on the exhaust gas side and the fresh gas side.
4. Exhaust gas recirculation device according to Claim 3, where one side of the compensation device (80-89) is loaded by the gas pressure (p₅) on the exhaust gas side, and the other side of the compensation device (80-89) is loaded by the gas pressure (p₃ or p₃') on the fresh gas side.
5. Exhaust gas recirculation device according to Claim 3 or 4, where the compensation device (81; 82) acts on the control means (60; 64) via a kinematic transmission, especially a lever transmission (21; 24), in order to compensate for a difference between areas of the control means (60; 64) which are effective for the gas pressure, on the one hand, and the compensation device (81; 82) on the other hand.
6. Exhaust gas recirculation device according to Claims 3 to 5, where the compensation device (80-82; 84-86; 89), the control means (60-69) and the pressure plate (40; 41; 42; 44) are interconnected in terms of the action of force and are controllable via the actuating device (14).
7. Exhaust gas recirculation device according to one or more of the preceding claims, where a stationary impact-pressure plate (52) is provided in order to prevent an exhaust gas stream flowing out of the control means (60-69) from flowing directly onto the pressure plate (40; 41; 42; 44).
8. Exhaust gas recirculation device according to one or more of the preceding claims, where the control means (60; 64; 65) is prestressed in the closed direction by the spring action of a diaphragm (81; 82) or a bellows (84), it being possible, in particular, for a spring (6; 6') to be provided as well to assist the prestressing.
9. Exhaust gas recirculation device according to one or more of the preceding claims, where the pressure plate (40; 41; 42; 44) is designed and arranged in such a way that the gas essentially flows through exactly defined openings (29; 29') in the pressure plate (40; 41; 42; 44) and as little gas as possible flows around its outer circumference.
10. Exhaust gas recirculation device according to one or more of the preceding claims, where the pressure plate (40; 44) is equipped with additional devices (8'; 55; 56-59) so that, at low exhaust gas throughput rates, the exhaust gas passes only through a narrow gap between the pressure plate (40; 44) and wall (8; 8') but, with increasing pressure differences, additional gas passage openings (8'; 29'; 59) are opened.
11. Exhaust gas recirculation device according to one or more of the preceding claims, where a gas pressure (p₁₀') in an inner valve compensation chamber (10') is controlled by the interaction of an inner valve (34) with an opening gap between the piston (89) and a guide sleeve (37) of the piston (89), the inner valve (34) being actuated by the actuating device (14) and/or an inner-valve actuating device.

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