DE112011104731T5 - Miniature regeneration unit - Google Patents

Abstract

The present invention provides a system for controlling the temperature of an exhaust stream from an engine at a position upstream of an exhaust aftertreatment device, the system having a main exhaust passage adapted to receive the exhaust flow from the engine. One side branch is connected to the main exhaust duct. In the side branch, there is disposed a regeneration unit for burning a fuel and heating the exhaust gas flowing through the main exhaust passage. An ion sensor is operable to output a signal indicative of the presence of fuel combustion. A control part selectively controls the regeneration unit to increase the exhaust gas temperature. The control part is operable to control a fuel supply to the regeneration unit based on the ion sensor signal.

Description

THE iNVENTION field

The present invention relates generally to a system for treating exhaust gases. In particular, a miniature regeneration unit for increasing an exhaust gas temperature is discussed.

background

In an effort to reduce the amount of NO _x and particulate matter emitted into the atmosphere during operation of an internal combustion engine, a plurality of exhaust treatment devices have been developed. A need for exhaust treatment systems arises particularly in connection with diesel combustion processes. Typical diesel engine after-treatment systems may include one or more of a diesel particulate filter (DPF), an SCR (Selective Catalytic Reduction) system, an HO (Hydrocarbon) injector, and a Diesel Oxidation Catalyst (DOC).

During engine operation, the DPF absorbs soot particles emitted by the engine, thus reducing the emission of particulate matter (PM). Over time, the DPF becomes laden and begins to clog. For proper operation, periodic regeneration or oxidation of the soot absorbed in the DPF is required. Regenerating the DPF requires relatively high exhaust gas temperatures in combination with a sufficient amount of oxygen in the exhaust stream to oxidize the soot absorbed in the filter.

The DOC is typically used to generate heat to regenerate the soot-laden DPF. When hydrocarbons (HC) are sprayed over the DOC at a specific light-off temperature or at a higher temperature, the hydrocarbons will oxidize. This reaction is highly exothermic and the exhaust gases are heated during the light-off. The heated exhaust gases are used to regenerate the DPF.

However, under many engine operating conditions, the exhaust gas is not hot enough to maintain a DOC light-off temperature of about 300 ° C. Therefore, DPF regeneration does not passively occur. Additionally, NO _x adsorbers and selective catalytic reduction systems typically require a minimum exhaust gas temperature for proper operation.

A burner may be provided for heating the exhaust stream upstream of the various aftertreatment devices. Known burners have successfully increased the exhaust gas temperature of internal combustion engines for use in motor vehicles. Some OEMs have resisted the use of older burners due to their size and cost. In addition, relatively large diesel engines may be provided in other applications such as diesel locomotives, stationary power plants, ships, and the like. The exhaust mass flow rate from the larger engines may be more than ten times the maximum throughput typically provided to the combustor. While it is possible to increase the size of the combustor to accommodate the increased exhaust mass flow rate, the cost, weight, and location concerns associated with such a solution may be unacceptable. Therefore, there is a need in the art for a miniature regeneration unit to increase the temperature of the exhaust gas emitted from an engine while minimizing the cost, weight, size, and performance of the exhaust system. It may also be desirable to have minimal impact on the pressure drop and / or back pressure associated with the use of a burner.

Brief description of the invention

This section is merely a general brief description of the invention and is not intended to be exhaustive of its full scope or all features.

A system for controlling the temperature of an exhaust gas flow from an engine at a position upstream of an exhaust aftertreatment device has a main exhaust passageway adapted to receive the exhaust gas flow from the engine. One side branch is connected to the main exhaust duct. In the side branch, there is disposed a regeneration unit for burning a fuel and heating the exhaust gas flowing through the main exhaust passage. An ion sensor is operable to output a signal indicating whether a fuel burning process is taking place. A control part selectively controls the regeneration unit to increase the exhaust gas temperature. The control part is operable to control a fuel supply to the regeneration unit based on the ion sensor signal.

Upstream of the exhaust aftertreatment device is provided a system for controlling the temperature of an exhaust stream from a motor. The system has a main exhaust passage suitable for receiving the flow of exhaust gas from the engine. A blind side branch is connected to the main exhaust duct. In the side branch is a regeneration unit for burning Fuel and heating of the main exhaust gas channel flowing through the exhaust gas arranged. The regeneration unit includes a housing disposed within the side branch and spaced from a sidewall of the side branch, a nozzle for injecting the fuel into a chamber defined by the housing, and an igniter for initiating combustion of the fuel in the housing. A control part selectively controls the regeneration unit to increase the exhaust gas temperature.

Further fields of application emerge from the description presented herein. The description and specific examples presented in this brief description are intended for purposes of illustration only and are not intended to limit the scope of the present invention.

drawings

The drawings described herein are merely illustrative of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present invention.

1 FIG. 12 is a schematic diagram showing a system for controlling the temperature of an exhaust gas from an engine; FIG.

2 shows a side cross-sectional view of a part of the in 1 illustrated exhaust aftertreatment system with a miniature regeneration unit;

3 shows a cross-sectional view of another regeneration unit;

4 shows a cross-sectional view of another regeneration unit;

5 shows a cross-sectional view of an engine after-treatment system with a flow deflector;

6 shows a perspective view of the aftertreatment system with the Strömungsumlenkeinrichtung;

7 shows a partial perspective view of part of another regeneration unit;

8th shows a cross-sectional view of another regeneration unit;

9 - 13 show perspective views for illustrating other inlet pipe sections of the regeneration unit; and

14 shows a cross-sectional view for illustrating another exhaust aftertreatment system.

In the several views of the drawings, corresponding parts are designated by like reference numerals.

Detailed description

Hereinafter, exemplary embodiments will be described with reference to the accompanying drawings.

1 shows an exhaust aftertreatment system 10 for treating by an exemplary engine 12 to a main exhaust duct 14 output exhaust gas. An inlet channel 16 is with the engine 12 connected to supply combustion air to the engine. A turbocharger 18 has a driven element (not shown) disposed in an exhaust gas flow. During engine operation, the driven element is caused to rotate by the flow of exhaust gas, which causes the intake passage 16 Compressed air is supplied before these in the engine 12 is initiated.

The exhaust aftertreatment system 10 also has a downstream of the turbocharger 18 and a miniature regeneration unit disposed upstream of a plurality of exhaust aftertreatment devices 26 on. In the in 1 As shown in the exemplary after-treatment system, the aftertreatment devices include a hydrocarbon injector 28 , a diesel oxidation catalyst 30 and a diesel particulate filter 32 on.

The regeneration unit 26 is within a side branch section 34 of the system 10 arranged with the main exhaust duct 14 connected is. The regeneration unit 26 can be used to warm the channel 14 flowing exhaust gas can be used at an elevated temperature, thereby reducing the efficiency of the DOC 30 increased and a regeneration of the DPF 32 is possible.

The regeneration unit 26 can be one or more injectors 36 for injecting a suitable fuel and an oxygenating agent. The fuel may be hydrogen or a hydrocarbon. The injector 36 can be structured as a combined injector that injects both the fuel and the oxygenating agent, as in FIG 1 or may have separate injectors for the fuel and the oxygenating agent ( 11 ). It becomes a control module 38 for monitoring and controlling the flow rates through the injector 36 and the Ignition of fuel by a first ignition device 42 using a suitable processor (s), sensors, flow control valves, electric coils, etc.

The regeneration unit 26 has a housing 50 designed as a multi-part assembly of fabricated metal components. The housing 50 has an inlet tube 52 , a cylindrical body 54 and an outlet pipe 56 on. An inlet head 58 is at the inlet pipe 52 attached. The inlet head 58 is at the side branch section 34 attached and enclosing one of its ends. Within the scope of the present invention, other one-piece or multi-part inlet arrangements are contemplated. A space between an inner surface 64 of the side branch section 34 and an outer surface of the housing 50 forms an annular volume 62 ,

An injector holder 65 is at the inlet pipe 52 and / or at the inlet head 58 attached to a mounting mechanism for the injector 36 provide. A nozzle section 66 the injection device 36 extends into the inlet pipe 52 , allowing atomized fuel into a primary combustion chamber 58 can be injected, at least partially through an inner cylinder surface 70 of the body 54 is defined. The injector 36 has a fuel inlet 72 and an air inlet 74 on. The fuel inlet 72 is with a fuel delivery system 76 connected to a fuel tank 78 , a fuel filter 80 , a fuel pump 82 and a fuel block 84 that passes through a fuel line 86 connected to each other. By the operation of the components of the fuel supply system 76 becomes the injector 36 selectively fed to hydrocarbon.

A secondary air system 90 has a secondary air filter 92 and a MAF sensor 94 on. A compressor 96 receives air, which is the secondary air filter 92 and the MAF sensor 94 flowed through. The compressor 96 may be part of a supercharger or turbocharger or a stand-alone electric compressor. The outlet flow of the compressor 96 gets the air intake 74 fed. When exhaust heating is desired, fuel will be delivered via the fuel inlet 72 injected and the oxygenating agent through the air inlet 74 provided to inject a stream of atomized fuel. The first ignition device 42 is at the side branch section 34 downstream from the inlet head 58 mounted and operable to the by the ignition device 36 provided fuel within the primary combustion chamber 68 to burn.

The side branch section 34 runs at an angle A of substantially 30 Degree with the exhaust duct 14 together. The through the regeneration unit 26 generated flame extends at substantially the same angle in the exhaust passage 14 ,

An elongated opening 110 extends through a main exhaust duct 14 defining pipe 112 , Part of the body 54 and the outlet tube 56 are inside the exhaust duct 14 arranged. From the engine 12 provided exhaust gas strikes the housing 50 and cools it during operation of the regeneration unit 26 from. It also takes off because of the case 50 Only minimal in the channel 14 extends, the exhaust back pressure also only minimal. It should be clear that the side branch section 34 and the injector 36 from the pipe 112 extend radially to the outside. Such an arrangement allows an OEM to more easily house the miniature regeneration unit in the vehicle.

In the present aftertreatment system, the first ignition device 42 also one with the coil 46 connected ion sensor 44 exhibit. The ion sensor 44 can take the form of one inside the combustion chamber 68 arranged electrode. To the ion sensor, a voltage for generating an electric field from the sensor to a mass, such as the housing 50 to be created. When a voltage is applied, an electric field is generated by the sensor to ground. If there are free ions in the field, a small ion current can flow. The size of the ionic current is an indication of the density of the ions. A control module 38 detects and receives signals from the ion sensor 44 to determine the presence or absence of a flame. The ion sensor 44 can also determine if the ignition device 42 is dirty.

Contamination can occur due to buildup of soot, oil or other contaminants. When the ignition device 42 polluted, no suitable combustion can take place. The control module 38 is operable to the fuel inlet 72 Fuel and injector 36 Supply air and interrupt the fuel / air supply, and the control module 38 determined by the ion sensor 44 provided signal, whether the ignition device 42 is dirty. If it is determined that the ignition device is ready, the control module 38 a plurality of engine and vehicle operating parameters, such as engine speed, ambient temperature, vehicle speed, engine coolant temperature, oxygen content, air mass flow rate, pressure differential across the diesel particulate filter 32 and any number of others Consider vehicle parameters. If the control module 38 determines that an increase in the exhaust gas temperature is desired, the injector 36 Fuel and secondary air supplied. The sink 46 leads the ignition device 42 electrical energy to cause combustion within the primary combustion chamber 68 trigger.

The control module 38 may also include a number of other parameters, such as the presence of combustion and the temperature of the exhaust gas within the duct 14 at a location downstream of the regeneration unit to determine when the fuel and air supply to the injector 36 should be terminated. For example, the control module 38 Receive signals from one or more temperature sensors in the regeneration unit 26 , in the side branch section 34 or in the main channel 14 are arranged to operate by the regeneration unit 26 to perform closed-loop control to maintain a desired temperature at a particular location. If combustion unexpectedly goes off, the control module stops 38 the fuel supply. Within the scope of the present invention, other control methods are also contemplated.

3 shows one with the side branch section 34 connected other regeneration unit 26a , The regeneration unit 26a is the regeneration unit 26 substantially similar except that the outlet tube section is of reduced diameter or narrowed mouth of the housing 50 has been removed. Therefore, similar elements are designated by an addition "a". The main body section 54a has a substantially constant diameter at an outlet opening 53a ends.

4 shows a by the reference numeral 26b designated other regeneration unit. The regeneration unit 26b is the regeneration unit 26 is substantially similar except that a length L has been increased to cause a larger portion of the housing 50b inside the exhaust duct 14 is arranged. Similar elements are designated by an addition "b". The position of the ignition device 42b has been changed so that it is farther from one end of the nozzle 66 is removed.

The 5 and 6 show another arrangement with a baffle 140 located upstream of the miniature regeneration unit 26 in the pipe 112 is arranged.

The baffle plate 140 has a D-shaped opening extending therethrough 142 on. The baffle plate 140 is arranged at an angle, as in 5 is shown to pass through the channel 14 forcing flowing exhaust gas to the housing 50 to flow around and around the case. The redirected exhaust gas flow transfers heat from the regeneration unit 26 to through the pipe 112 flowing exhaust gas.

7 shows a part of one by the reference numeral 26c designated other regeneration unit. The regeneration unit 26c is the regeneration unit 26 essentially similar, except that the length of the outlet tube 56c is enlarged and the outlet pipe a plurality of openings extending through the outlet pipe 144 having. The larger outlet tube length and the openings 144 Make sure that the combustion flame during operation of the regeneration unit 26c is maintained properly and remains aligned. If exhaust through the channel 14 flows, a portion of the exhaust gas flows through the openings 144 whereby a mixing effect is produced, which leads to a more favorable temperature distribution, flame stability and flame quality.

8th shows a by the reference numeral 26d designated other regeneration unit. The regeneration unit 26d has the components of the regeneration unit 26 and an additional housing section 145 on top of a secondary combustion chamber 146 Are defined. A second ignition device 148 extends into the secondary combustion chamber 146 , Several openings 149 extend through the second housing 145 to allow exhaust gas into the second combustion chamber 146 can occur. By using the regeneration unit 26d Better exhaust gas heating and mixing can be achieved.

The 9 - 13 show other inlet tube configurations that replace the inlet tube 52 can be used. Each of the modified inlet tubes has a plurality of circumferentially spaced openings 150 on, extending through an end wall 152 extend. The openings 150 allow that to be the channel 14 flowing exhaust gas into the primary combustion chamber 68 can occur. By feeding oxygen into the primary combustion chamber 68 over the openings 150 can the pressure of the injector 36 from the compressor 96 supplied secondary air can be reduced. The cost and size of the compressor 96 can also be reduced.

This in 9 illustrated inlet pipe 52e has several at one end to an end wall 152e attached tabs 156e on. The tabs 156e are designed to swirl the openings 150e to induce gas flow. 10 shows rectangular openings 150f without straps. 11 shows several on a radially inner side of the openings 150g attached tabs 156g , The tabs 156g extend radially outward at an angle to the exhaust stream. 12 shows another inlet tube assembly 52h with several openings 150h and several tabs 156h , The tabs 156h extend radially inward.

13 shows a plurality of circumferentially spaced apart circular openings 150i , The openings are not partially blocked by tabs. Through each of the in the 9 - 13 arrangements shown is a substantially homogeneous flow distribution in the interior of the primary combustion chamber 68 provided.

It is also contemplated that any of the described miniature regeneration unit assemblies having openings 150 an injection device 36j with a differently arranged secondary air inlet 74j for injecting compressed air at a relatively low pressure into an annular volume 62 may have, as in 14 is shown. A fuel inlet 72j is arranged such that atomized fuel into the primary combustion chamber 68j is injected as discussed above. Part of the in the annular volume 62j injected air flows through the openings 150i and the remainder of the secondary air flows along an outer surface of the housing 50j to the miniature regeneration unit 26j to cool.

The foregoing description of the embodiments is for explanation and illustration only. It should not be understood as complete or in a limiting sense. Individual elements or features of a particular embodiment are generally not limited to this particular embodiment but, where possible, interchangeable and usable in a selected embodiment, although not specifically illustrated or described. Within the scope of the present invention, various changes and modifications are possible.

Claims (20)

A system for controlling the temperature of an exhaust stream from an engine at a position upstream of an exhaust aftertreatment device, the system comprising: a main exhaust passage adapted to receive the exhaust gas flow from the engine; a side branch connected to the main exhaust duct; a side-branched regeneration unit for burning a fuel and heating the exhaust gas flowing through the main exhaust passage; an ion sensor operable to output a signal indicative of the presence of fuel combustion; and a control part for selectively controlling the regeneration unit to increase the exhaust gas temperature, the control part being operable to control a fuel supply to the regeneration unit based on the ion sensor signal. The system of claim 1, further comprising supplying secondary oxygen to the regeneration unit. The system of claim 2, wherein the regeneration unit comprises a housing defining a primary combustion chamber, wherein the fuel and the secondary oxygen are directly supplied to the primary combustion chamber. The system of claim 3, wherein the housing has a reduced diameter portion at a free distal end. The system of claim 3, wherein the housing has a first end held by the side branch and a non-retained second end, the first end having a plurality of apertures extending through the first end for receiving a portion of the exhaust gas flow. The system of claim 3, wherein the housing extends at least partially into the main exhaust passage to cool the housing. The system of claim 3, wherein the regeneration unit comprises a housing defining a primary combustion chamber, wherein the fuel is directly supplied to the primary combustion chamber, the secondary oxygen is supplied to an outer surface of the housing, and the housing has openings to allow a portion of the secondary oxygen to flow into the primary combustion chamber enters. The system of claim 1, further comprising a baffle disposed in the main exhaust passage upstream of the regeneration unit, the baffle having an opening shaped and arranged to direct the flow of exhaust gas toward the regeneration unit. The system of claim 8, wherein the opening is formed substantially D-shaped. The system of claim 1, wherein the controller terminates the supply of fuel when the ion sensor signal indicates an unexpected extinguishment of the combustion. The system of claim 1, wherein the side branch converges to the main exhaust passage at an angle of substantially thirty degrees. The system of claim 1, wherein the side branch has a distal end that faces away from the main exhaust passage and at which no exhaust gas is received. A system for controlling the temperature of an exhaust stream from an engine at a position upstream of an exhaust aftertreatment device, the system comprising: a main exhaust passage adapted to receive the exhaust gas flow from the engine; a blind side branch connected to the main exhaust duct; a side-branched regeneration unit for combusting a fuel and heating the exhaust gas flowing through the main exhaust passage, the regeneration unit comprising a housing disposed within the side branch and spaced from a sidewall of the side branch, a nozzle for injecting the fuel into an exhaust gas defined by the housing Chamber and an ignition device for triggering a fuel combustion within the housing; and a control part for selectively controlling the regeneration unit to increase the exhaust gas temperature. The system of claim 13, further comprising supplying secondary air to the regeneration unit. The system of claim 14, wherein the housing has a reduced diameter portion at a free distal end. The system of claim 15, wherein the housing has a first end held by the side branch and a non-retained second end, the first end having a plurality of openings extending through the first end for receiving a portion of the exhaust gas flow. The system of claim 13, wherein the housing extends at least partially into the main exhaust passage to cool the housing. The system of claim 13, further comprising supplying secondary air to an area between the housing and the sidewall. The system of claim 13, further comprising a baffle disposed in the main exhaust passage upstream of the regeneration unit, the baffle having an opening shaped and arranged to direct the flow of exhaust gas toward the regeneration unit. The system of claim 19, wherein the opening is formed substantially D-shaped.

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