DE10312212B4 - Reducing agent infeed - Google Patents

Abstract

Cover (30) attachable to a reducing agent injection nozzle (16), wherein
the cover (30) has a nozzle receiving portion (31) which is open at one axial end and closed at the other axial end, and wherein
in the nozzle receiving portion (31), in an area closer to the closed axial end than the open axial end, there is provided an opening (33) through which a reducing agent can be injected.

Description

The present invention relates to a reductant feed having an injector for supplying reductant to a catalyst for removing nitrogen oxide (NO _x ).

A number of technologies for reducing NO _x in the exhaust gas of an internal combustion engine have been proposed.

A Technology is disclosed in Japanese Patent Laid-Open JP 02-223624 A discloses.

Further, Japanese Laid-Open Patent Publication JP 2001-65333A discloses an exhaust gas purifying apparatus having a NO _x eliminating catalyst, which is located in an exhaust system and reduces NO _x in the exhaust gas for purifying the exhaust gas. The apparatus supplies reductant, such as fuel, to the catalyst. Exhaust gas from lean combustion of gasoline engines and diesel engines contains a relatively small amount of hydrocarbon (HC) and carbon monoxide (CO). Since the device according to the publication supplies reducing agent to the catalyst, the apparatus enables the catalyst of such engines to satisfactorily reduce _NOx from the exhaust gas.

at the device of publication There is a reductant injector in the exhaust system. The injection injects reducing agents, e.g. Fuel, in the exhaust system one. The injector injects reductant from its outlet, using the reducing agent atomized. The amount of supplied Reducing agent is easily adjusted. The reduction performance on the catalyst is thus improved.

The injection is in an exhaust system, such as e.g. an exhaust port, arranged so that the nozzle outlet exposed to the system. The injection outlet is therefore always exposed to the exhaust while the engine is running.

When the outlet of the injection nozzle is exposed to the exhaust gas, soot accumulates in the exhaust gas around the outlet. Exhaust heat changes the nature of the collected soot and solidifies the soot. The hardened soot, or soot deposit, accumulates around the outlet and reduces the opening area of the nozzle outlet. The reduced opening area of the outlet prevents a sufficient amount of reducing agent from being supplied to the catalyst. This lowers the NO _x removal performance of the catalyst.

Accordingly, it is an object of the present invention to provide a reductant feed having an injector for supplying reductant to a catalyst for removing NO _x while preventing soot deposits from accumulating around the outlet of the nozzle.

According to the invention this Task with an attachable to a reducing agent injector Cover according to claim 1 and a reducing agent feed according to claim 6. Further embodiments of the invention are in the dependent claims explained.

Further Aspects and advantages of the invention will become apparent from the following Description in conjunction with the accompanying drawings, which illustrate by way of example the basis of the invention, can be seen.

The Invention, together with its objects and advantages, is best with reference to the description below of the presently preferred embodiments together with the accompanying drawings, in which:

1 Fig. 12 is a diagrammatic view showing an exhaust system and the surroundings of an engine;

2 Fig. 12 is a perspective view illustrating an injector cover according to an embodiment of the present invention;

3 is a sectional view showing the mounting structure of in 2 shown nozzle shows;

4 (a) a side view is the in 2 illustrated cover illustrated;

4 (b) a front view is the in 2 illustrated cover illustrated;

4 (c) a subview is that the in 2 illustrated cover illustrated;

5 FIG. 4 is a sectional view illustrating a reductant feed according to another embodiment; FIG. and

6 a sectional view illustrating a reducing agent feed according to another embodiment.

Now, with respect to 1 to 4 (c) a reductant feed according to a Embodiment of the present invention described. The reductant feed is in a four cylinder common rail diesel engine 1 used.

As in 1 shown has the engine 1 a cylinder head 2 , in which four cylinders # 1- # 4 are formed. The cylinder head 2 is each with one of the cylinders # 1- # 4 corresponding fuel injectors 3a to 3d Mistake. Intake ports and intake valves (none are shown) are in the cylinder head 2 according to each cylinder # 1- # 4 provided. When a respective intake valve is open, the corresponding intake port communicates with the corresponding cylinder of the # 1- # 4 cylinders. An intake manifold 5 is connected to the inlet openings. The intake manifold 5 is with a loader 9 with an inlet tube 7 connected. An intercooler 10 is in the inlet tube 7 provided to lower the temperature of the intake air.

The fuel injectors 3a to 3d are with a common rail 14 connected. The common rail 14 collects high pressure fuel. The common rail 14 is with a feed pump 15 connected. The feed pump 15 pressurizes and supplies fuel from a fuel tank (not shown) to the common rail 14 to. If one of the fuel injectors 3a to 3d is open, the pressurized fuel in the common rail 14 from the outlet of the fuel injector 3a to 3d injected into the corresponding cylinder of cylinders # 1- # 4.

The cylinder head 2 is provided with exhaust valves (not shown) and exhaust passages. In this embodiment, the exhaust passages are exhaust ports 8th , 3 shows a part of one of the outlet openings 8th and an injection nozzle 16 , which will be discussed below. When one of the exhaust valves is open, the corresponding exhaust port is 8th with the corresponding cylinder of cylinders # 1 to # 4 in conjunction. Each pair of exhaust valves (not shown) and exhaust ports 8th corresponds to one of the cylinders # 1- # 4. The outlet openings 8th are over an exhaust manifold 20 with the loader 9 connected.

In the exhaust system is a catalyst 13 for removing NO _x downstream of the compressor 9 , The catalyst 13 is a reduction absorption type NO _x catalyst. That is, the catalyst 13 absorbs NO _x in the exhaust gas when the air-fuel ratio of the exhaust gas is lean. When the air-fuel ratio of the exhaust gas is rich or when reducing agent is supplied, the catalyst is reduced and decomposed 13 the absorbed NO _x .

Since the combustion is performed in a diesel engine with an oxygen-rich air-fuel mixture, the exhaust gas contains a relatively small amount of HC and CO. Therefore, the air-fuel ratio rarely gets rich. Thus, a NO _x absorption-reduction catalyst, when mounted on a diesel engine, can not obtain a sufficient amount of reductant to reduce NO _x from the exhaust gas. In this embodiment, besides the injectors 3a to 3d the injector 16 for supplying reducing agent to the catalyst. The injector 16 is with the feed pump 15 and is powered by a built-in electromagnetic solenoid (not shown).

As in 3 is shown at the distal end of the injection nozzle 16 an outlet 17 educated. The injector 16 is in the cylinder head 2 provided so that the distal end and attached to the distal end cover 30 in the fourth cylinder # 4 associated exhaust port 8th protrudes. The cover 30 acts as a deflector. The at the distal end of the injector 16 attached cover 30 Prevents soot in the environment of the outlet 17 collects and prevents the temperature in the environment of the outlet 17 increases.

To prevent excessive temperature rise due to the exhaust heat, the projecting amount of the cover 30 in the exhaust port 8th preferably equal to or less than 20 mm, and more preferably equal to or less than 5 mm. In order to prevent the collected soot from changing its texture and hardening, the position of the injection nozzle is 16 preferably chosen so that the highest temperature of the outlet 17 is equal to or less than 250 ° C. More preferably, the position of the injector is 16 so chosen that the highest temperature of the outlet 17 is equal to or less than 120 ° C. The optimal projection amount of the cover 30 and the optimal position of the injector 16 were confirmed by experiments by the inventors.

2 is a perspective view showing the cover 30 shows. 4 (a) to 4 (c) are a side view, a front view and a bottom view. As in 2 and 4 (a) to 4 (c) is shown is the cover 30 essentially cylindrical and has a closed end. The cover 30 has a nozzle receiving portion 31 and a flange 32 , The distal end of the injector 16 is in the nozzle receiving portion 31 introduced. The flange 32 extends from the upper end of the nozzle receiving portion 31 abroad. The cover 30 is made of a heat-resistant metal such as stainless steel.

A right-angled opening 33 is at the un the lower part of the nozzle receiving portion 31 educated. The one through to the opening 33 plane containing vertical direction and the flow direction of the exhaust gas defined angle is preferably between 0 ° and 90 °. Even more preferably, the defined angle is between 0 ° and 30 °.

As in 2 to 4 (c) is shown extending three baffles from the sides or the bottom of the opening 33 abroad. In this embodiment, the baffles are baffles 41 . 42 . 43 , The baffles 41 . 42 . 43 change the flow direction of the exhaust gas. As in 4 (b) are shown are the lower ends of the side baffles 41 . 42 with the sides of the lower baffles 43 connected. The baffles 41 to 43 form a U-shaped cross-section around the sides and bottom of the opening 33 around.

As in 3 . 4 (a) and 4 (c) Shown are the baffles 41 to 43 relative to the flow direction of the exhaust gas inclined by predetermined angle. In particular, the baffles 41 to 43 curved in such a way that sections located further downstream of the flow direction have larger angles of inclination. In order to suppress the increase in the exhaust gas resistance, the length La (see 4 (a) ) of the lower baffle 43 preferably equal to or less than 5 mm. More preferably, the length La is equal to or less than five times the length B of the opening 33 ,

To prevent exhaust gas in the cover 30 enters, the area of the opening becomes 33 preferably minimized. However, if the opening area is too small, can from the outlet 17 the injector 16 injected fuel with the edges of the opening 33 or the baffles 41 to 43 get in touch.

In this embodiment, the opening area is minimized while preventing injected fuel from the edges of the opening 33 comes into contact. In particular, the area of the opening 33 about 20% larger than the cross-sectional area of the injected fuel at a plane perpendicular to the injection direction at the opening.

As in 3 is shown is a retaining element 18 at the distal end of the injector 16 screwed. The flange 32 is between the injector 16 and the retaining element 18 held. Thus, the cover 30 at the injection nozzle 16 secured. A return 4 is formed in the cylinder head. The injector 16 is in the recess from the distal end 4 introduced. The injector 16 is with a clamp (not shown) on the cylinder head 2 attached. A conical exhaust gasket spring 19 is located between the bottom of the return 4 and the retaining element 18 ,

The outlet 17 the injector 16 is located in a downstream region of the exhaust port 8th , Therefore, fuel, which acts as a reducing agent, from the outlet 17 the injector 16 in the downstream direction of the exhaust port 8th injected. The injected fuel flows with exhaust gas from the fourth cylinder # 4 downstream and becomes the catalyst 13 supplied as a reducing agent. The reducing agent is supplied at a predetermined timing, so that the catalyst 13 maintains its NO _x removal function for a longer period of time.

The cover 30 Prevents exhaust gas from entering the exhaust port 8th projecting portion of the injection nozzle 16 directly hits. The upstream section of the cover 30 acts as a shield and deflects the flow direction of the exhaust gas (see arrow A from 3 ).

Extending from edges of the cover 30 extending baffles 41 to 43 are inclined at predetermined angles relative to the flow direction of the exhaust gas. The baffles 41 to 43 change the flow direction from the distal end of the injector 16 , or the outlet 17 the injector 16 path. For example, the under baffle changes 43 the exhaust gas flow direction from the outlet 17 away, as indicated by arrow B 3 is shown. The side baffles 41 and 42 change the exhaust gas flow direction from the outlet 17 away, as indicated by arrow C. 4 (c) is shown. To prevent the exhaust from the outlet 17 meets, while the increase of the exhaust resistance is suppressed, is due to the direction along which the lower baffle plate 43 extends and through the injection direction (see 3 ) defined angle, preferably between 0 ° and 90 ° and more preferably between 0 ° and 60 °.

The exhaust gas flow in the exhaust port 8th flows along the inclined relative to the exhaust gas flow direction baffles 41 to 43 and is from the outlet 17 the injector 16 distracted. The exhaust gas thus hits the outlet 17 Not.

The baffles 41 to 43 are curved so that the angle of inclination in the exhaust port 8th are larger in more downstream areas. Therefore, the resistance of the exhaust gas that would be increased by forcibly changing the flow direction is minimized.

Because the baffles 41 to 43 are curved, the exhaust gas flow direction is prevented from suddenly changing. This prevents that the exhaust gas flow along the baffles 41 to 43 swirls, which prevents turbulence from entering. Accordingly, the exhaust gas flow does not flow to the outlet due to any turbulence generated by swirling the exhaust gas flow 17 the injector 16 ,

The cover 30 essentially covers the entire section of the exhaust opening 8th projecting distal end of the injector 16 from. The cover 30 thus shields the injector 16 Effective against heat and prevents the temperature of the distal end of the injector 16 is heated excessively.

The outlet 17 the injector 16 is located at the downstream portion of the exhaust port 8th and injects reducing agent downstream. Therefore, downstream exhaust gas hits the outlet 17 not directly. This prevents soot from accumulating and deposits from accumulating.

This embodiment offers the following advantages.

The reductant feed has the cover 30 that the exhaust gas flow in the exhaust port 8th to the distal end of the injector 16 So distracts away from the distal end of the nozzle. Therefore, the flow of exhaust gas is prevented from the distal end of the injector 16 , in particular the outlet 17 , meets. Accordingly, it prevents deposits around the outlet 17 the injector 16 pile around.

That in the exhaust port 8th protruding distal end of the injector 16 is through the cover 30 covered. The cover 30 shields the distal end from exhaust flows to the distal end and shields the distal end from heat. As a result, the projecting portion does not collect soot and the temperature is not excessively increased. This effectively prevents deposits from accumulating.

The cover 30 is with the baffles 41 to 43 provided that the exhaust gas flow from the outlet 17 the injector 16 distract away. Thus, exhaust gas is prevented from leaving the outlet 17 which prevents soot from accumulating and accumulating debris.

The baffles 41 to 43 are curved so that the angle of inclination in further downstream of the exhaust port 8th lying areas are larger. This prevents the flow along the baffles 41 to 43 swirls and suppresses eddies generated by these turbulences. As a result, exhaust gas is prevented due to an increase in exhaust resistance and turbulence in the cover 30 arrives.

The outlet 17 the injector 16 is located at the downstream portion of the outlet opening 8th and injects reducing agent downstream. Therefore, exhaust gas that hits in the exhaust port meets 8th downstream flows the outlet 17 not directly. This prevents soot from accumulating and suppresses accumulation of deposits.

It should for It will be apparent to those skilled in the art that the present invention can be done in many other specific educations without doing so to deviate from the scope of the invention. In particular, should be understood will be that the invention be carried out in the following ways can.

The distal end of the injector 16 does not have to be in the exhaust port 8th protrude. As in 5 is shown, the nozzle outlet 17 inside the cylinder head 2 are located.

As in 6 shown, the lower baffle 43 through an element (baffle plate 47 ), which is integral with the cylinder head 2 is formed and an equivalent function as the baffle 43 Has.

Because the baffle 47 with the cylinder head 2 in which the injector 16 is provided, is integrally formed, escapes the heat of the baffle 47 to the other section of the cylinder. Thus it prevents the temperature of the plate 47 increases excessively and also the heat shielding performance of the plate 47 improved.

To prevent excessive exhaust gas resistance while preventing exhaust gas from leaving the exhaust 17 achieved and to maintain the Wärmeabschirmleitung is the length of the baffle 47 preferably equal to or less than 5 mm and is between one tenth of the length Lc of an opening 2a and one half of the length Lc.

The number of baffles is not limited to three. As long as one or more baffles are provided, only the lower baffle can 43 be provided.

The injector 16 can in the exhaust manifold 20 be provided.

The reducing agent does not need to power the engine 1 be used fuel. Any material with reduction effect can be used. Examples are urea, ammonium components, cyanic acid, dimethyl ether and methyl ether.

The present invention can be applied to one in other types of engines, such as. a lean burn engine, used reductant feed be applied.

Therefore For example, the present examples and embodiments are illustrative and not as limiting and the invention is not limited to those specified herein Details limited, but may be within the scope and equivalence of the attached claims be modified.

A reducing agent feed has an injector disposed in an exhaust system of an internal combustion engine provided with a catalyst for NO _x . The injector has an outlet at the distal end. The injector injects reducing agent through the outlet into a passage of the exhaust system, thereby supplying reducing agent to the catalyst. A baffle deflects the exhaust flow to the distal end of the injector in the exhaust passage from the distal end.

Claims (6)

Cover ( 30 ) connected to a reducing agent injection nozzle ( 16 ) is attachable, wherein the cover ( 30 ) a nozzle receiving portion ( 31 ), which is open at one axial end and closed at the other axial end, and wherein in the nozzle receiving portion ( 31 ) in an area closer to the closed axial end than the open axial end, an opening ( 33 ) is provided, through which a reducing agent can be injected. Cover ( 30 ) according to claim 1, wherein at the open axial end of the nozzle receiving portion (FIG. 31 ) a radially outwardly extending flange ( 32 ) for attachment to the reducing agent injection nozzle ( 16 ) is trained. Cover ( 30 ) according to claim 1 or 2, wherein the opening ( 33 ) to the closed axial end of the nozzle receiving portion (FIG. 31 ). Cover ( 30 ) according to one of claims 1 to 3, wherein at the lateral edges and at the close axial end of the closed edge of the opening ( 33 ) outwardly inclined baffles ( 41 . 42 . 43 ) are provided. Cover ( 30 ) according to claim 4, wherein the baffles ( 41 . 42 . 43 ) are curved concave from outside the cover. Reducing agent feed with a reducing agent injection nozzle ( 16 ) and a cover ( 30 ) according to one of the preceding claims, wherein one with an outlet ( 17 ) provided tip of the reducing agent injection nozzle ( 16 ) in the nozzle receiving portion ( 31 ) of the cover ( 30 ), and the outlet ( 17 ) is arranged so that the tip of the reducing agent injection nozzle ( 16 ) so into the nozzle receiving section ( 31 ) of the cover ( 30 ) can be used, that from the outlet ( 17 ) Reducing agent through the opening ( 33 ) of the cover ( 30 ) can be injected.