EP2166204A1 - Flame glow plug - Google Patents

Abstract

The flame glow plug (10) has a combustion chamber (16), which has an outlet opening (20) for the flame, particularly a blockable fuel supply for preparing a fuel stream to the combustion chamber. An ignition device (32), particularly an electrically operated heating element is provided, which is arranged in the combustion chamber for igniting the air or fuel mixture formed from the prepared fuel stream and the prepared air stream. The air supply is formed in a controllable quantity. Independent claims are included for the following: (1) a regeneration device for a particulate filter of an exhaust system of an internal combustion engine, particularly a diesel engine; and (2) a method for operating a regeneration device of a particulate filter of an exhaust system of an internal combustion engine, particularly a diesel engine.

Description

The present invention relates to a flame glow plug having a combustion chamber having an outlet opening for the flame, a particular lockable fuel supply for providing a fuel flow to the combustion chamber, an air supply for providing an air flow to the combustion chamber and an ignition device, in particular an electrically operated heating element is disposed in the combustion chamber or extends into the combustion chamber and which is adapted to ignite the resulting from the provided fuel flow and the air flow provided air / fuel mixture.

The invention further relates to a regeneration device for a particulate filter of an exhaust system, an exhaust system for an internal combustion engine and a method for operating a regeneration device.

Known flame glow plugs are used as a cold start aid for diesel engines, wherein the air is heated in the intake of the engine by the exiting flame.

It is an object of the invention to develop an additional field of use for flame glow plugs.

This object is achieved by a flame glow plug with the features of claim 1.

According to the invention, the air supply of the flame glow plug is controllable in quantity. In particular, the air supply in the amount can be formed reducible and / or lockable. If the air supply is sufficiently reduced to prevent the formation of an ignitable by the igniter air / fuel mixture, the escape of a flame is omitted from the combustion chamber. Instead, a meterable fuel flow exits the combustion chamber, which can be used for appropriate purposes. However, if the air supply is released sufficiently that an ignitable air / fuel mixture is produced in the combustion chamber, this can be ignited by the ignition device. The corresponding flame exits the outlet and can be used in the usual way. A flame glow plug according to the invention can thus be operated either as a fuel injection device or as a burner.

Such a flame glow plug can be used in particular for the efficient regeneration of a particulate filter in an exhaust system of an internal combustion engine.

Combustion engines emit an exhaust gas stream into the atmosphere containing various types of pollutants. To reduce pollutant emissions various devices have been developed for exhaust aftertreatment. For example, catalysts are used for converting harmful gaseous substances into harmless components and particulate filters for collecting unwanted solid particles. For example, the exhaust line of a diesel engine may be provided with a diesel oxidation catalyst and a particulate filter disposed downstream thereof. Soot particles that are in the exhaust gas flow are collected by the particle filter and stored in this. From a certain amount of accumulated soot from the Particle filters are removed so that the exhaust emissions are not unduly hindered. This process is called regeneration. A common method for the regeneration of a particulate filter is to heat the particulate filter to a certain temperature, so as to burn the soot stored. This can be done in principle by any heating device. However, such a heater must have a relatively high power to heat the particulate filter to the ignition temperature of the soot, which has an increased demand for energy and installation space.

Therefore, other methods based on the principle of secondary fuel injection (HC-dosing) have been developed. In doing so, one makes use of the knowledge that fuel, in particular in the form of unburned hydrocarbons, can bring about a reaction in the catalyst and thereby heat it. From a certain temperature, which is generally referred to as the light-off temperature, there is an exothermic reaction of the fuel, that is, the reaction proceeds independently after ignition with continued heat release. Due to the exothermic reaction, the catalyst may heat sufficiently to heat the downstream particulate filter to the necessary temperature to burn off the stored soot. In this case, no separate heater is required. The injection of fuel into the exhaust stream is usually carried out with an injection device which is arranged in the immediate vicinity of the catalyst. Alternatively, the injection of the fuel into the exhaust gas flow can also take place inside the engine, for example by a post-injection of fuel into the combustion chamber.

However, at catalyst temperatures below the light-off temperature, no exothermic reaction occurs, which is why particulate filter regeneration occurs By fuel injection only in certain operating conditions of the engine is possible. Moreover, there is the problem of increased fuel consumption.

With the aid of a burner operated flame glow plug, which is located in the vicinity of the catalyst, the catalyst can be heated at any time to the light-off temperature. When the temperature of the catalyst is above the light-off temperature, the flame glow plug can be used as a secondary fuel injection device. In this way, with a flame glow plug according to the invention, a regeneration of a particulate filter can be carried out independently of the catalyst temperature, that is to say independently of the operating state of the internal combustion engine.

The means for shutting off the air supply can be provided on the flame glow plug itself or on a component upstream of the flame glow plug. In particular, a controllable solenoid valve may be arranged on an air supply line or on an air source remote from the flame glow plug.

Preferably, to provide the air flow, a connection piece is provided, to which an air line, which is in particular connected with a compressed air source, can be connected. The spigot can be designed in a similar manner as provided in conventional flame glow plugs fuel supply. The flame glow plug can be used in this way in different environments using various types of compressed air tanks, compressors or the like, with only an air line must be provided with a free end matching the connection piece. The air line can be connected to the connecting piece clamped, screwed or otherwise attached to him.

According to a preferred embodiment of the invention, the combustion chamber has an airtight circumferential portion, a single end-side inlet opening and a single outlet opening opposite to the inlet opening. The combustion chamber thus defines an air termination region, wherein access of ambient air into the combustion chamber is prevented when the air supply is shut off. Only after an exit from the combustion chamber, the fuel flow can mix with air. However, since outside the combustion chamber, the igniter is not effective, there is no fire in this case.

Preferably, the combustion chamber is at least partially formed by a cylindrical sleeve member having an air-impermeable lateral surface. Easy-to-manufacture sleeve elements are also used in conventional flame glow plugs as Brennkammerumfassung. However, holes are provided in the circumferential surface of the cylindrical sleeve members in known flame glow plugs to allow air to enter the combustion chamber. By omitting the holes in the sleeve member can thus be provided without additional measures of the desired air termination space, which allows continued operation of the flame glow plug as Eindüsungsvorrichtung.

The flame glow plug is suitably adapted for mounting in an exhaust duct of an internal combustion engine, in particular a diesel engine, in order to be used in the desired manner for regenerating a particulate filter in the exhaust duct.

Another object of the invention is to make the regeneration of particulate filters in exhaust systems more efficient.

This object is achieved by a regeneration device for a particulate filter of an exhaust system comprising an exhaust passage for discharging a hot exhaust gas flow from an internal combustion engine, in particular a diesel engine, and a catalyst, in particular an oxidation catalyst, which is integrated into the exhaust passage upstream of the particulate filter the regeneration device comprises a burner which is able to heat the catalyst to a reaction temperature at which an exothermic reaction of the fuel takes place, wherein a flame glow plug according to the invention is provided as the burner and the regeneration device comprises at least one control device which is designed to to control the air supply of the flame glow plug in dependence on an operating state of the exhaust system and / or the internal combustion engine. The control device can thus ensure that the flame glow plug is operated either as a burner or as an injection device when the particulate filter regeneration is to be carried out as required.

Preferably, the control means is adapted to release the air supply when the temperature of the catalyst is below the reaction temperature and regeneration of the particulate filter is to be performed. For example, if the loading of the particulate filter with soot particles stored has reached a level requiring regeneration but, on the other hand, the temperature of the catalyst is too low for an exothermic reaction since, for example, the engine has just been started, the controller may release the flame glow plug operate the air supply as a burner and thus for efficient and rapid heating of the catalyst to the temperature necessary for secondary fuel injection.

The control device is preferably designed to reduce or shut off the air supply when the temperature of the catalyst is above the reaction temperature and regeneration of the particulate filter is to be performed. The flame glow plug is thus operated in this case as an injection device for providing a secondary fuel flow. In this way, superfluous burning operation is avoided and the regeneration of the particulate filter can be done effectively via the secondary fuel injection whenever possible.

When the temperature of the catalyst has risen above the reaction temperature, the controller may reduce or shut off the air supply again. It is thus switched directly to the more efficient heating principle, as soon as the catalyst has reached the required temperature.

The object directed to an efficient regeneration of particulate filters in exhaust systems is further solved by an exhaust system for an internal combustion engine comprising a regeneration device according to the invention.

Furthermore, this object is achieved by a method for operating a regeneration device according to the invention. The method comprises the steps of determining an operating state of the exhaust system and / or of the internal combustion engine and providing an ignitable air / fuel mixture or providing an ignitable air / fuel mixture as a function of the determined operating state in the event of regeneration of the particulate filter is prevented.

Depending on the current engine operating point, the most effective regeneration principle can thus be selected.

Preferably, a provision of an ignitable air / fuel mixture is prevented by the air supply of the flame glow plug is reduced or shut off. If the air supply is throttled so far that can form no ignitable mixture in the combustion chamber, instead of a flame, a metered fuel flow exits from the outlet opening of the combustion chamber. The ignition device of the flame glow plug can then continue to operate with reduced or shut-off air supply, for example, to bring about or promote evaporation of the fuel flow in the combustion chamber, whereby the effectiveness of the secondary injection is increased. Similarly, a small amount of air supply, which is insufficient to form an ignitable by the igniter air / fuel mixture may be provided to selectively influence the properties of the exiting from the combustion chamber fuel flow, in particular oxygen for the subsequent combustion of To provide soot in the particulate filter.

To determine the operating state of the exhaust system, in particular a temperature of the catalyst can be determined. Alternatively, an operating parameter of the internal combustion engine could also be determined, for example the coolant temperature, the rotational speed or the operating time.

Preferably, an ignitable air / fuel mixture is provided when the temperature of the catalyst is below the reaction temperature and regeneration of the particulate filter is to be performed.

The flame glow plug is then operated as a burner and ensures direct heating of the catalyst.

On the other hand, providing a flammable air / fuel mixture is preferably prevented when the temperature of the catalyst is above the reaction temperature and a reaction is to be carried out. The flame glow plug is thus used as a device for fuel secondary injection and unnecessary, energy-intensive combustion operation is avoided.

Fig. 1

zeigt eine schematische Darstellung einer erfindungsgemäßen Flammglühkerze.

Fig. 2

zeigt schematisch einen Teil eines Abgassystems, das einen Partikelfilter und einen Oxidationskatalysator sowie eine erfindungsgemäße Flammglühkerze umfasst.

The invention will now be described by way of example with reference to the drawings.

Fig. 1

shows a schematic representation of a flame glow plug according to the invention.

Fig. 2

schematically shows a part of an exhaust system comprising a particulate filter and an oxidation catalyst and a flame glow plug according to the invention.

In the Fig. 1 Flammglühkerze 10 shown comprises a substantially cylindrical base body 12, on one end face of a cylindrical sleeve member 14 is arranged made of heat-resistant material. The sleeve element 14 defines a combustion chamber 16, which has an inlet opening 18 facing the main body 12, an outlet opening 20 facing away from the base body 12, and a lateral surface 22.

An attachment flange 24, shown only schematically, is provided on the main body 12, which serves for the flame glow plug 10 in such a way at an exhaust passage 26 (FIG. Fig. 2 ) of an internal combustion engine (not shown), that the sleeve member 14 projects into the exhaust passage 26. A first connecting piece 28 for providing a fuel flow and a second connecting piece 30 for providing an air flow are respectively attached to the main body 12 or formed on this. They each open into a treatment chamber (not shown) in the base body 12, which serves to generate an ignitable air / fuel mixture from the provided fuel flow and the air flow provided. If necessary, additional metering devices for metering the fuel flow and the air flow in the connecting piece 28, 30 or may be provided in the processing chamber. The exact design of the air / fuel treatment chamber and the metering devices is not important. All that is essential is that an ignitable air / fuel mixture is delivered to the combustion chamber 16 when a fuel supply to the first connecting piece 28 and an air supply to the second connecting piece 30. Two heating elements 32 arranged in parallel are arranged in the main body 12 and each have a glow tip (not shown) extending into the combustion chamber 16 and a connecting section 36 arranged opposite to it and led out from the main body 12. By means of the connecting portions 36, the heating elements 32 can be connected to a controllable electrical energy source. The number and the efficiency of the heating rods 32 are designed such that when they are activated, the air / fuel mixture entering the combustion chamber 16 is ignited and accordingly a flame emerges from the outlet opening 20 of the combustion chamber 16.

As in Fig. 1 can be seen, no holes or bushings are provided in the lateral surface 22 of the sleeve member 14, as is the case with conventional flame glow plugs. Moreover, the air supply 30 formed in the amount controllable, that is, it can be throttled or down regulated so far that the formation of an ignitable air / fuel mixture is prevented. With the air supply 30 shut off and the fuel supply 28 provided, a fuel flow enters the combustion chamber 16, the axially flowing fuel on the one hand and the air-impermeable outer surface 22 of the sleeve member 14 on the other hand preventing any air from entering the combustion chamber 16 from the outside. Thus, when the air supply 30 is shut off, no flame but a metered fuel flow emerges from the outlet opening 20 of the combustion chamber 16.

By the in Fig. 1 shown flame glow plug 10 can be realized in an advantageous manner, a regeneration device for an exhaust passage 26, as described below with reference to Fig. 2 is explained in more detail.

The in Fig. 2 shown exhaust passage 26 receives at an upstream end 27, the hot exhaust gas flow from an internal combustion engine and passes it on to a tailpipe (not shown), through which the exhaust gases are discharged into the atmosphere. Before it escapes into the atmosphere, the exhaust gas flow, represented by an arrow, passes through a catalytic converter 38 and a particle filter 40 for limiting emissions. The catalyst 38 may be a conventional oxidation catalyst, such as a diesel oxidation catalyst. The particulate filter 40 is a soot particulate filter which filters out soot particles contained in the exhaust gas stream from the exhaust gas stream and stores it in its interior. Upstream of the catalyst 38, a regeneration device for the particulate filter 40 in the form of a flame glow plug 10 is arranged.

The flame glow plug 10 is connected via its first connecting piece 28 to a fuel line 44 and via its second connecting piece 30 to an air line 46. The heating rods 32 of the flame glow plug 10 are connected to an electrical energy source 48, for example a battery. The fuel line 44 communicates with a fuel source 50 shown only schematically and the air line 46 communicates with a compressed air source 52 also shown only schematically. In the fuel line 44, a first solenoid valve 54 is arranged and in the air line 46, a second solenoid valve 56 is arranged. In the connecting line between the electric power source 48 and the flame glow plug 10, a controllable electrical switch 51 is arranged.

The flame glow plug 10 can assume three different operating states. According to a first operating state, both the fuel supply and the air supply are shut off and the heating rods 32 are not operated. The flame glow plug 10 is thus out of service altogether. According to a second operating state, the fuel supply is released, the air supply is shut off and the heating rods 32 are operated. The flame glow plug 10 is thus operated as a secondary injection device. According to a third operating state, both the air supply and the fuel supply are released and the heating rods 32 are operated. The flame glow plug 10 is operated in this case as a burner.

The control of the individual operating states of the flame glow plug 10 by means of a control device 60 which is connected via electrical control lines to the first solenoid valve 54, the second solenoid valve 56 and the electrical switch 51. In the illustrated embodiment, the controller 60 is a stand-alone controller formed, which is remote from the flame glow plug 10 and is connected via electrical lines to the respective components. Alternatively, the control device 60 may also be integrated into a control unit of the internal combustion engine.

The controller 60 receives various input signals and controls the operation of the flame glow plug 10 based thereon. Specifically, the controller 60 receives a catalyst temperature signal 62 and a particulate filter loading signal 64. However, various other input signals are conceivable that can be used to determine whether regeneration of the particulate filter 40 is being performed should and whether the temperature of the catalyst 38 is above the light-off temperature.

When the particulate filter loading signal 64 indicates that regeneration of the particulate filter 40 is to be performed, the controller 60 checks, based on the catalyst temperature signal 62, if the temperature of the catalyst 38 is below the reaction temperature at which an exothermic reaction of the injected fuel occurs. If this is the case, the flame glow plug 10 is operated as a burner to heat the exhaust passage 26 and the catalyst 38. The controller 60 then continuously checks the catalyst temperature based on the catalyst temperature signal 62. Once the catalyst temperature has risen above the reaction temperature, the controller 60 shuts off the air supply to the flame glow plug 10 to thereby operate the flame glow plug 10 as an injector and thus unburned liquid hydrocarbons into the exhaust stream enter. These react exothermically in the catalyst 38, releasing heat and increasing the catalyst temperature. Due to the exothermic reaction of the injected fuel, the catalyst 38 and the particulate filter 40 arranged in the immediate vicinity are heated to a temperature which is sufficient is to achieve combustion of the soot particles in the particulate filter 40 and thus regeneration of the particulate filter 40.

The means for shutting off the air supply are in the illustrated embodiment, therefore, on the one hand in the sleeve member 14 with luftundurchlässiger lateral surface 22 and on the other hand in the second solenoid valve 56. However, shut-off valves of different types and at different locations can be used. For example, the solenoid valve 56 may be located directly on the flame glow plug 10 or on the compressed air source 52. It is only important that the air supply of the flame glow plug can be controlled interrupted or reduced sufficiently to allow the output of a fuel flow without flame formation in desired time intervals.

By the regeneration method described above, it is possible to perform a regeneration of the particulate filter 40 at arbitrary times and during any operating conditions of the exhaust system or the internal combustion engine, that is, for example, immediately after the start of the internal combustion engine. Conveniently, this is only a single, compact and easy to manufacture component, namely a Flammglühkerze 10 of the invention required. A costly and space consuming heater for directly heating the particulate filter 40 to the Rußabbrandtemperatur is not necessary. The regeneration concept according to the invention is applicable to many different types of internal combustion engines in the industrial plant and motor vehicle sector.

LIST OF REFERENCE NUMBERS

10

flame glow plug

12

body

14

sleeve member

16

combustion chamber

18

inlet opening

20

outlet opening

22

lateral surface

24

mounting flange

26

exhaust duct

28

first connection piece

30

second connection piece

32

heater

36

connecting portion

38

catalyst

40

particulate Filter

44

Fuel line

46

air line

48

electrical energy source

50

Fuel source

51

switch

52

Compressed air source

54

first solenoid valve

56

second solenoid valve

60

control device

62

Catalyst temperature signal

64

Particle filter charge signal

Claims (15)

Flame glow plug (10) with
a combustion chamber (16) having a discharge opening (20) for the flame,
a particular lockable fuel supply for providing a fuel flow to the combustion chamber (16),
an air supply to provide an air flow to the combustion chamber (16), and
an ignition device (32), in particular an electrically operated heating element, which is arranged in the combustion chamber (16) or extends into the combustion chamber (16) and which is designed to control the air / fuel flow resulting from the supplied fuel flow and the air flow provided. Ignite mixture,
characterized in that
the air supply in the amount is controllable. Flame glow plug (10) according to claim 1,
characterized in that
the air supply in the amount is formed reducible and / or lockable. Flame glow plug (10) according to claim 1 or 2,
characterized in that
the means for controlling the air supply to the flame glow plug (10) or on a flame glow plug (10) upstream component are provided. Flame glow plug (10) according to one of the preceding claims,
characterized in that
in order to provide the air flow, a connecting piece (30) is provided, to which an air line (46) which is in particular connected to a compressed air source (52) can be connected. Flame glow plug (10) according to one of the preceding claims,
characterized in that
the combustion chamber (16) has a hermetically sealed peripheral portion (22), an end-side inlet opening (18) and an outlet opening (20) opposite to the inlet opening (18). Flame glow plug (10) according to one of the preceding claims,
characterized in that
the combustion chamber (16) is at least partially formed by a cylindrical sleeve element (14) with an air-impermeable lateral surface (22). Flame glow plug (10) according to one of the preceding claims,
characterized in that
it is designed for mounting in an exhaust duct (26) of an internal combustion engine, in particular a diesel engine. Regeneration device for a particulate filter (40) of an exhaust system, which has an exhaust gas channel (26) for discharging a hot exhaust gas stream from an internal combustion engine, in particular a diesel engine, and a catalyst (38), in particular an oxidation catalyst, integrated into the exhaust passage (26) upstream of the particulate filter (40), the regeneration device comprising a burner capable of bringing the catalyst (38) to a reaction temperature in which an exothermic reaction of the fuel takes place, to heat up,
characterized in that
as burner a flame glow plug (10) according to one of claims 1 to 7 is provided and that
the regeneration device comprises at least one control device (60) which is designed to control the air supply of the flame glow plug (10) as a function of an operating state of the exhaust system and / or of the internal combustion engine. Regeneration device according to claim 8,
characterized in that
the control means (60) is adapted to release the air supply when the temperature of the catalyst (38) is below the reaction temperature and regeneration of the particulate filter (40) is to be performed. Regeneration device according to claim 8 or 9,
characterized in that
the control device (60) is designed to reduce or shut off the air supply when the temperature of the catalyst (38) is above the reaction temperature and regeneration of the particulate filter (40) is to be carried out, and / or
the control device (60) is designed to reduce or shut off the air supply once the temperature of the catalyst (38) has risen above the reaction temperature. Exhaust system for an internal combustion engine, in particular a diesel engine, comprising: an exhaust passage (26) for discharging a hot exhaust gas flow from the internal combustion engine, a particulate filter (40), and a catalyst (38), in particular an oxidation catalyst, integrated into the exhaust passage (26) upstream of the particulate filter (40); characterized in that
the exhaust system comprises a regeneration device according to any one of claims 8 to 10. Method for operating a regeneration device according to one of claims 8 to 10,
characterized in that
an operating state of the exhaust system and / or the internal combustion engine is determined and
in the case of a regeneration of the particulate filter (40), an ignitable air / fuel mixture is provided as a function of the determined operating state, or a provision of an ignitable air / fuel mixture is prevented. Method according to claim 12,
characterized in that
a provision of an ignitable air / fuel mixture is prevented by the air supply of the flame glow plug (10) is reduced or shut off, in particular
the ignition device (32) of the flame glow plug (10) is operated with reduced or blocked air supply. Method according to one of claims 12 to 13,
characterized in that
for determining the operating state of the exhaust system, a temperature of the catalyst (38) is determined. Method according to one of claims 12 to 14,
characterized in that
an ignitable air / fuel mixture is provided when the temperature of the catalyst (38) is below the reaction temperature and regeneration of the particulate filter (40) is to be performed, and / or
providing an ignitable air / fuel mixture is inhibited when the temperature of the catalyst (38) is above the reaction temperature and regeneration of the particulate filter (40) is to be performed.

Images