EP2446125B1 - Injection system for injecting fluid into an exhaust system - Google Patents

Description

State of the art

The invention relates to an injection system for injecting fluid into an exhaust tract.

It is known to install a particulate filter in an exhaust system of an internal combustion engine of a vehicle. If the internal combustion engine is, for example, a diesel engine, the particulate filter, for example, acts as a soot filter and, due to its filtering effect, reduces particulate matter pollution. In order to prevent the filter from becoming clogged after a certain period of use, it is necessary to regenerate the filter from time to time. The regeneration is carried out by increasing the temperature, for example, to about 600 degrees Celsius, whereby the particles, especially soot particles, burn. Since this is not possible in all operating states by means of engine measures, the temperature increase is achieved by means of fuel, for example diesel, which is injected into the exhaust tract via an injection valve. The injected fuel reaches an oxidation catalyst, which is arranged in front of the particle filter. The reaching into the oxidation catalyst fuel is oxidized or burned and leads to an exhaust gas temperature increase, so that correspondingly hot exhaust gases reach the downstream particle filter and cause the regeneration there.

Methods and devices for the regeneration of a particulate filter are described, for example in DE 10 2005 034 704 A1 . DE 10 2006 062 491 A1 and DE 10 2006 057 425 A1 described. From the DE 100 59 427 is known to divert fuel from a common rail system for the exhaust aftertreatment.

The previously known systems for injecting fluid into an exhaust tract can only be used for a single exhaust tract and do not permit any increase in the amount of fluid injected.

Disclosure of the invention

It is an object of the invention to provide an improved system for injecting a fluid into an exhaust tract that is easily adaptable to exhaust systems having multiple exhaust trains and allows for the injection of arbitrarily large quantities of fluid.

The object is achieved by an injection system according to the independent patent claims. The dependent claims describe advantageous embodiments of the injection system according to the invention according to the independent claim. 1

An injection system according to the invention has at least two modules and at least one pressure compensation volume. The pressure compensation volume is designed to supply fluid to at least one of the modules and connects at least two of the modules hydraulically with each other. Each of the modules has an inlet for receiving fluid and at least one injection unit configured to inject fluid into the exhaust tract.

Due to the modular structure, the injection system according to the invention is easily adaptable to multi-flow exhaust systems and different quantity requirements of the fluid to be injected. In particular, by adding additional modules arbitrarily large amounts of fluid can be injected.

The pressure equalization volume provided according to the invention dampens the transmission of pressure oscillations between the individual modules. This ensures that essentially constant pressure conditions are present on each module. This allows a precise injection of a given amount of fluid.

In this case, at least one metering unit is provided for metering the fluid. By such a metering unit, the desired injection quantity can be set exactly.

In this case, the metering unit may have a shut-off valve for switching off the fluid supply and a metering valve for metering the fluid. In this case, an output of the shut-off valve is hydraulically connected to an input of the metering valve. Such a construction of a metering unit with a shut-off valve and a metering valve, which are arranged in series one behind the other, enables on the one hand a reliable shutdown of the fluid supply and on the other hand a precise metering of the desired injection quantity. Because the fluid supply through the shut-off valve can be switched off independently of the metering valve, uncontrolled leakage of fluid can be reliably prevented even in the event of a malfunction of the metering valve. The safety of the injection system is increased.

In an arrangement which is not part of the invention, the inlets of the modules are hydraulically connected to a common fluid supply. The common fluid supply is at least partially designed as a pressure equalization volume. An at least partially designed as a pressure compensation volume fluid supply provides the necessary pressure decoupling between the modules. A correspondingly large volume can be designed, for example, like a rail used in common-rail technology, so that it is possible to fall back on the experience known from common-rail technology.

In one embodiment, the inlet of the second module via the pressure equalization volume is hydraulically connected to the output of the shut-off valve of the first module. In this embodiment, the fluid supply of the entire injection system can be switched off by the shut-off valve of the first module. This eliminates the need for a shut-off valve in the additional modules to reduce the cost of these modules.

In a variant of this embodiment, the inlet of a third module is hydraulically connected to the pressure equalization volume, so that the pressure equalization volume is used in common for the second, third and possibly further modules and regardless of the number of modules used only a single pressure compensation volume is provided. By using only a single pressure compensation volume, the cost of the injection system can be kept low.

In an alternative embodiment, the inlet of the third module via a second pressure equalization volume is hydraulically connected to the output of the shut-off valve of the second module. Because in this embodiment each module is coupled in each case via its own pressure compensation volume with a preceding module, the individual pressure compensation volume can be smaller than a common pressure compensation volume. By using several small pressure compensation volumes, the injection system can be flexibly adapted to the available space and the installation of the injection system is simplified.

In one embodiment, at least one metering device is provided for metering the fluid. In this case, the pressure compensation volume can be filled by the metering device with fluid. In an injection system in which the common pressure compensation volume can be filled with fluid by a metering device, only a single metering device is required. As a result, the cost of the injection system can be further reduced.

In one embodiment, a valve, in particular a check valve, is arranged between the pressure compensation volume and each module. By means of such a valve, the individual modules are hydraulically decoupled from each other. If the modules are hydraulically decoupled from one another, the pressure compensation volume can be made smaller and the reliability of the injection system is improved, since harmful interactions between the individual modules are reliably prevented.

In a further embodiment, a second metering device, which supplies a second pressure compensation volume with fluid, is hydraulically connected to the first metering device via a third pressure compensation volume. An injection system with such a structure can be expanded as desired, in particular, the injection system can be constructed so that even large amounts of fluid can be injected into multiple exhaust tracts.

In one embodiment, the injection units for injecting fluid are formed upstream of a catalyst disposed in the exhaust tract. This will cause catalytic combustion of the injected fluid and thus achieves a particularly effective regeneration of the filter arranged in the exhaust tract.

The invention will be explained in more detail below with reference to the systems shown in the accompanying figures for injecting fluid fuel into an exhaust gas tract. However, the invention is also applicable to systems for injecting other fluids, e.g. Urea, applicable.

FIG. 1 shows a first embodiment of an injection system according to the invention with three dosing units connected in series.

FIG. 2 shows a second embodiment of an injection system according to the invention, in which the metering units are connected to each other via a common pressure equalization volume.

FIG. 3 shows a variant of the second embodiment with two simplified metering units.

FIG. 4 an arrangement in which all three dosing units are supplied with fluid via a common pressure compensation volume.

FIG. 5 schematically shows an internal combustion engine with an exhaust system and a fourth embodiment of an injection system according to the invention, in which a common pressure equalization volume is fed by a single metering unit.

FIG. 6 shows a combination of the in the FIGS. 1 and 5 shown embodiments.

FIG. 1 shows a first embodiment of an injection system according to the invention with a first module having a first metering unit 10 and a first injection unit 40. The first dosing unit 10 has a shut-off valve 12, by which a fuel flow supplied by a fuel supply 8 can be switched on and off. At the output, ie in the flow direction behind the shut-off valve 12, a first pressure sensor 16 is arranged on a fuel line 19 in the first dosing unit 10 to the pressure of the incoming fuel to eat. In the flow direction behind the first pressure sensor 16, a metering valve 14 is arranged, which is designed to meter the desired injection quantity. At the outlet of the metering valve 14, a second pressure sensor 18 is provided to measure the fuel pressure at the outlet of the metering valve 14. An output of the first metering unit 10 is hydraulically connected to an input of the first injection unit 40. The injection unit 40 has, in addition to an injection valve 42, a cooling adapter and a metal gasket, which in the schematic representation of FIG. 1 not shown.

The injection valve 42 is arranged at an exhaust tract, also not shown, upstream of a catalytic converter, to inject fuel into the exhaust gas tract. The injected fuel is catalytically burned in the catalyst. This raises the temperature around the exhaust tract so that deposits deposited in a particulate filter located downstream of the catalyst are burned and the filter is regenerated.

To the fuel line 19 is hydraulically connected between the output of the shut-off valve 12 and the first pressure sensor 16 of the first metering unit 10, a first pressure compensation volume 44, which is filled with open shut-off valve 12 with fuel from the fuel supply line 8. An output of the first pressure compensation volume 44 is connected to the input of a dosing unit 20 of a second module, which has the second dosing unit 20 and a second injection unit 50. Thus, when the shut-off valve 12 of the first metering unit 10 is open, the metering unit 20 of the second module is supplied with fuel from the fuel supply 8 via the first pressure compensation volume 44.

The second metering unit 20 supplies the associated second injection unit 50 with a metered quantity of fuel. The second module with the second metering unit 20 and the second injection unit 50 is identical in construction to the first module with the first metering unit 10 and the first injection unit 40. Therefore, a detailed description of the structure will be omitted.

Between the shut-off valve 22 and the first pressure sensor 26 of the dosing unit 20 of the second module, a second pressure compensation volume 54 is connected to a fuel line 29 which supplies a dosing unit 30 of a third module with fuel when the shut-off valve 22 is open. The third module has a third injection unit 60, which is supplied by the metering unit 30 of the third module with fuel.

By connecting further, in the FIG. 1 Not shown metering units, each with a further injection unit to the fuel line 39 in the third metering unit 30 via additional, in the FIG. 1 Not shown, pressure compensation volume is that in the FIG. 1 shown injection system arbitrarily expandable.

By virtue of the fact that identical modules, which comprise the metering units 10, 20, 30 and the injection units 40, 50, 60, and pressure compensation volumes 44, 54 are used, an injection system according to the invention is particularly simple, flexible and inexpensive to produce. There are only three different components must be made from which arbitrarily large injection systems are composable. Characterized in that for the connection of each dosing unit 10, 20, 30 each have a separate pressure compensation volume 44, 54 is used, the individual pressure compensation volume 44, 54 have a small size and are easy and flexible to install.

FIG. 2 shows an alternative embodiment of an injection system according to the invention.

The metering units 10, 20, 30 and injection units 40, 50, 60 used in this embodiment are identical in construction to the units used in the first embodiment and will therefore not be described again.

That in the FIG. 2 embodiment shown differs from that in the FIG. 1 shown embodiment in that at the pressure compensation volume 46, which is connected downstream of the shut-off valve 12 to the fuel line 19 of the first metering unit 10, both the second metering unit 20 and the third metering unit 30 and possibly further, in the FIG. 2 not shown dosing units are connected. As in the in the FIG. 2 shown embodiment, only a single pressure compensation volume 46 is used, can be dispensed with the production and installation of multiple pressure compensation volume. The injection system is therefore simple and inexpensive to produce and assemble

FIG. 3 shows a variant of in the FIG. 2 shown embodiment, wherein the metering units 21, 31 connected to the pressure compensation volume 48 have no shut-off valve and only one pressure sensor 28, 38 which is arranged behind the respective metering valve 22, 34.

Dosing units 21, 31, which have no shut-off valve, are referred to as "SLAVE" dosing units 21, 31 and are less expensive to produce than a so-called "MASTER" dosing unit 10, which additionally has a shut-off valve 12 and a first pressure sensor 16 between the shut-off valve 12 and the metering valve 14. The fuel supply in this embodiment can be switched off for the entire injection system by closing the shut-off valve 12 in the first, "MASTER" -dosing unit 10.

FIG. 4 shows an arrangement with three "MASTER" -Dosiereinheiten 10, 20, 30, which are identical in construction to the metering units of the first embodiment and connected to a common fuel supply 54. The common fuel supply 54 ("common rail") is at least partially designed as a pressure equalization volume. Here, components and experiences from common-rail technology are used.

In an alternative arrangement, not shown, the metering units are designed as "SLAVE" metering units without shut-off valve, and a central shut-off valve is formed in the supply line (not shown) for common fuel supply 54.

FIG. 5 shows an alternative embodiment of an injection system according to the invention, in which the individual modules each comprise an injection unit 40, 50, 60, 70 and are supplied via a common pressure equalization volume 58 from a common metering unit 10 with fuel.

In the FIG. 5 schematically an internal combustion engine 72 with six cylinders and two exhaust gas lines 82, 84 is shown. In each of the exhaust lines 82, 84, a particulate filter 76 is arranged in each case, which is designed to filter particles from the exhaust gas stream. In each of the exhaust lines 82, 84 is between the Combustion engine 72 and the respective particulate filter 76 each an oxidation catalyst 74 is arranged.

A total of four injection units 40, 50, 60, 70 are arranged on the exhaust gas lines 82, 84 in order to inject the metered by the metering unit 10 fuel upstream of the oxidation catalysts 74 in the respective exhaust gas tract 82, 84. The injected fuel is catalytically combusted in the oxidation catalysts 74. By the combustion, the temperature in the exhaust lines 82, 84 is increased so much that soot deposited in the particulate filters 76 burns and the particulate filters 76 are regenerated.

That in the FIG. 5 shown embodiment of an injection system according to the invention has a known from the first embodiment of dosing unit 10, which is supplied via a fuel supply 8 with fuel. The metering unit 10 feeds a quantity of fuel dosed by the metering unit 14 into a common pressure compensation volume 58, which is hydraulically connected to four injection units 40, 50, 60, 70. The four injection units 40, 50, 60, 70 can be supplied with fuel from the pressure compensation volume 58. The injection units 40, 50, 60, 70 are identical in construction to the injection units 40, 50, 60 described in connection with the previous embodiments and will therefore not be described again.

Each of the four injection units 40, 50, 60, 70 is connected to the pressure compensation volume 58 via its own fuel line 49, 59, 69, 79. In each of the fuel lines 49, 59, 69, 79, a check valve 64, 65, 66, 67 is provided in each case between the pressure compensation volume 58 and the respective injection unit 40, 50, 60, 70. The check valve 64, 65, 66, 67 prevents backflow of fuel from the injection units 40, 50, 60, 70 into the pressure compensating volume 58. The injection units 40, 50, 60, 70 are thus hydraulically decoupled from each other.

This in FIG. 5 shown embodiment of an injection system has only a single metering unit 10 and a single pressure compensation volume 58. It is therefore particularly inexpensive to produce and has only a small footprint.

FIG. 6 shows a further embodiment of an injection system according to the invention, in which the first embodiment is combined with the fourth embodiment.

This in FIG. 6 embodiment shown has three metering units 10, 20, 30, for filling each of the respective metering unit 10, 20, 30 associated pressure compensation volume 56, 57, 58 with a metered amount of fuel. To each of the pressure compensation volumes 56, 57, 58 are respectively three injection units 40, 50, 60, 41, 51, 61, 43, 53, 63 connected, which are identical to the injection units 40, 50, 60 described in connection with the previously described embodiments are and in particular each have an injector, not shown in the figure 7 for injecting the metered by the metering units 10, 20, 30 fuel into a not shown exhaust tract.

The first metering unit 10 is supplied with fuel by a fuel inlet 8.

Analogously to the first exemplary embodiment, the second dosing unit 20 is connected to the first dosing unit 10 via a pressure compensation volume 44 which is connected behind the shut-off valve 12 to the fuel line 19 of the first dosing unit 10 and is supplied with fuel via this pressure compensation volume 44.

The second dosing unit 30 is connected to the first dosing unit 20 via a second pressure compensation volume 54 which is connected behind the shut-off valve 12 to the fuel line 12 of the second dosing unit 20 and is supplied with fuel via the second pressure compensation volume 54.

That in the FIG. 6 embodiment shown combines the advantages of the first embodiment ( FIG. 1 ) with the advantages of the fourth embodiment ( FIG. 5 ). In particular, the two-stage modular design of this embodiment makes it possible to adapt the injection system particularly flexibly to any exhaust system and, in particular, to inject large quantities of fuel into particularly large exhaust systems with a plurality of exhaust gas lines.

The Indian FIG. 6 shown construction with three metering units 10, 20, 30, each of which three fuel injection units 40, 50, 60, 41, 51, 61, 43, 53, 63 fueled, is only an example. Each of the metering units 10, 20, 30 may fuel any larger or smaller number of injection units 40, 50, 60, 41, 51, 61, 43, 53, 63. Likewise, any number of metering units 10, 20, 30 may be combined to provide an injection system of the desired size.

In alternative exemplary embodiments, which are not shown in the figures, the additional metering units 20, 30 are connected to the first metering unit 10 via a common pressure compensation volume according to the second exemplary embodiment. Also, the additional metering units 20, 30 may be configured as "SLAVE" metering units 21, 31 without their own shut-off valve 22, 32 in order to keep the costs for the injection system low.

Claims (10)

1. An injection system for injecting a fluid into an exhaust tract, having at least two modules and at least one pressure compensation volume (44, 46, 48, 54, 56, 57, 58), wherein each module comprises at least one injection unit (40, 50, 60), which is designed to inject the fluid into the exhaust tract and wherein the pressure compensation volume (44, 46, 48, 54, 56, 58) is designed to feed the fluid to at least one of the modules and connects at least two of the modules hydraulically to one another,
   characterized in that at least the first module comprises a metering unit (10, 20, 30; 21, 31) for metering the fluid, wherein the metering unit (10, 20, 30) comprises a cutoff valve (12, 22, 32) for cutting off the fluid feed and a metering valve (14, 24, 34) for metering the fluid, and wherein an outlet of the cutoff valve (12, 22, 32) is hydraulically connected to an inlet of the metering valve (14, 24, 34), wherein the inlet of the second module is hydraulically connected via the pressure compensation volume (44, 46) to the outlet of the cutoff valve (12) of the first module.
2. Injection system for injecting a fluid into an exhaust tract, which comprises at least two modules and at least one pressure compensation volume (58); wherein each module comprises at least one injection unit (40, 50, 60, 70), which is designed to inject the fluid into the exhaust tract and wherein the pressure compensation volume (58) is designed to feed the fluid to at least one of the modules and connects at least two of the modules hydraulically to one another,
   characterized in that at least a first metering unit (10) for metering the fluid, is provided,
   wherein the pressure compensation volume (58) can be filled with fluid by the first metering unit (10), wherein a valve (64, 65, 66, 67, 68), in particular a non-return valve, is arranged between the pressure compensation volume (58) and each injection unit (40, 50, 60, 70).
3. Injection system according to Claim 2, wherein the metering unit (10) comprises a cutoff valve (12) for cutting off the fluid feed and a metering valve (14) for metering the fluid.
4. Injection system according to Claim 1, having a third module, wherein the inlet of the third module is hydraulically connected to the pressure compensation volume (46).
5. Injection system according to Claim 1, having a third module and a second pressure compensation volume (54), wherein the inlet of the third module is hydraulically connected via the second pressure compensation volume (54) to the outlet of the cutoff valve (22) of the second module.
6. Injection system according to Claims 1, 4 or 5, wherein only the first module comprises a cutoff valve (12).
7. Injection system according to one of Claims 2 and 3, having at least one pressure compensation volume (56), which can be filled with fluid by the metering unit (10).
8. Injection system according to Claim 7, wherein a valve, in particular a non-return valve, is arranged between the additional pressure compensation volume (56) and each injection unit (40, 50, 60) connected to the additional pressure compensation volume (56).
9. Injection system according to one of the preceding claims, having a second metering unit (20), wherein the second metering unit (20) is hydraulically connected to the first metering unit (10) via the or an additional pressure compensation volume (44).
10. Injection system according to one of the preceding claims, wherein at least one injection unit is designed so that the fluid can be injected into the exhaust tract upstream of a catalytic converter arranged in the exhaust tract.

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