JP6027376B2 - Fuel addition structure - Google Patents

Description

  The present invention relates to a fuel addition structure in which fuel is added to exhaust gas flowing in an exhaust system passage by a fuel addition valve.

  Particulate matter (particulate matter) discharged from a diesel engine is mainly composed of a soot fraction composed of carbon and a SOF fraction (Soluble Organic Fraction) composed of a high-boiling hydrocarbon component. Furthermore, it has a composition containing a small amount of sulfate (mist-like sulfuric acid component). As a measure to reduce this type of particulates, a particulate filter can be installed in the middle of the exhaust pipe through which exhaust gas flows. Has been done.

  The particulate filter has a porous honeycomb structure made of a ceramic such as cordierite, and the inlets of the respective channels partitioned in a lattice shape are alternately sealed, and the channels are not sealed. The outlet is sealed, and only the exhaust gas that has permeated through the porous thin wall defining each flow path is discharged to the downstream side.

  Then, the particulates in the exhaust gas are collected and deposited on the inner surface of the porous thin wall, so that the particulates are appropriately burned and removed before the exhaust resistance increases due to clogging. It is necessary to regenerate, but in normal diesel engine operating conditions, there are few opportunities to obtain exhaust temperatures that are high enough for particulates to self-combust. A type of particulate filter is used.

  By adopting such a catalyst regeneration type particulate filter, the oxidation reaction of the collected particulates is promoted, the ignition temperature is lowered, and it is possible to burn and remove the particulates even at an exhaust temperature lower than before. However, even when such a catalyst regeneration type particulate filter is adopted, the trapped amount exceeds the particulate processing amount in the operation region where the exhaust temperature is low, so such a low value. If the operation state at the exhaust gas temperature continues, there is a possibility that the particulate filter will fall into an over trapped state without the particulate filter regenerating well.

  Therefore, an oxidation catalyst for regeneration is separately arranged in the front stage of the particulate filter, and when the accumulated amount of particulates has increased, fuel is added to the exhaust gas upstream of the oxidation catalyst to actively use the particulate filter. Forced regeneration is performed.

  In other words, the fuel added on the upstream side of the particulate filter undergoes an oxidation reaction while passing through the preceding oxidation catalyst, and the catalyst bed temperature of the particulate filter immediately after that rises due to the inflow of exhaust gas heated by the reaction heat. As a result, the particulates are burned out, and the particulate filter is regenerated.

  As a specific means for executing this kind of fuel addition, post-injection is added at the timing of non-ignition later than the compression top dead center following the main injection of fuel performed near the compression top dead center. It is common to add fuel to the gas.

  However, when fuel is added by post injection in this way, fuel, engine oil, apportionment, and HC gas are mixed in a high temperature and high pressure environment, so that HC polymerization is likely to occur and abruptly occurs at the outlet of the EGR cooler. A tar-like high-viscosity polymer is generated at a location with a decrease in temperature, and this polymer may have an adverse effect on the intake system and valve system, so the middle of the exhaust system downstream of the turbocharger turbine. It has also been proposed to add a fuel addition valve by directly injecting fuel into the exhaust system by using the fuel addition valve.

  In addition, as the prior art document information related to the fuel addition structure in which fuel is added to the exhaust gas flowing in the exhaust system passage by the fuel addition valve in the same manner as the present invention, for example, the following Patent Document 1 has already been disclosed. Existing.

JP 2011-252438 A

  However, when the direct injection method using the fuel addition valve as described above is employed, if the injection port is directed to the upstream side of the flow of the exhaust gas, the exhaust gas including apportioning is vigorously moved from the front with respect to the injection port. The injection port is likely to be blocked by apportioning, so that it is usual to inject the fuel obliquely downstream with respect to the flow direction of the exhaust gas. When the fuel is injected obliquely downstream with respect to the direction, the fuel is injected in the same direction as the flow of the exhaust gas, and the fuel smoothly rides on the flow of the exhaust gas and is not refined or diffused. There has been a problem that the evaporation and dispersion of the fuel added from the fuel addition valve does not proceed well.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel addition structure that can accelerate evaporation and dispersion of added fuel from a fuel addition valve.

  According to the present invention, a fuel addition valve is provided in an exhaust brake housing that opens and closes an exhaust system passage by a butterfly type valve body so that fuel can be injected toward the valve body, and the fuel is in a tilted position when the valve body is fully opened. The present invention relates to a fuel addition structure characterized in that a reflection portion is provided so that the fuel injected from the addition valve can collide and bounce back to the upstream side.

The present invention provides a fuel addition structure in which a fuel addition valve is attached in the middle of an exhaust system path, and fuel is added to the exhaust gas flowing through the exhaust system path from the fuel addition valve. A spray pocket recessed from the inside to the outside of the exhaust system passage is formed at the valve mounting position, and the nozzle portion of the fuel addition valve is disposed through the spray pocket so as to be obliquely downstream with respect to the exhaust gas flow direction. And a vortex flow that deflects the flow of exhaust gas to the spray pocket side at a position facing the spray pocket in the exhaust system path and returns to the upstream side in the spray pocket. A slope portion is provided which is formed and collides with the injected fuel from the nozzle portion of the fuel addition valve and rebounds upstream .

  When the evaporation and dispersion of the fuel is promoted, the fuel reaches the oxidation catalyst in a well dispersed state as HC gas. The oxidation catalyst effectively causes an oxidation reaction to efficiently exhaust the exhaust gas. Since the temperature can be raised, the forced regeneration of the particulate filter can be completed in as little time as possible.

Furthermore, in the present invention, since the fuel addition valve is provided in the exhaust brake housing, even if a deposit is formed around the injection port of the fuel addition valve and grows to the exhaust brake operating range, the exhaust brake operates. Each time the valve is tilted, it interferes with the deposit, which breaks the deposit and prevents further growth.

  According to the fuel addition structure of the present invention described above, various excellent effects as described below can be obtained.

  (I) According to the invention described in claim 1 of the present invention, the fuel from the fuel addition valve collides with the reflecting part of the valve body of the exhaust brake and bounces back to the upstream side to counteract the flow of the exhaust gas. The fuel can evaporate and disperse significantly by striking the exhaust gas flow from the front.

According to the invention described in claim 1, (II) the present invention, it is possible to inhibit the growth extends to the operating range of the deposit of the exhaust brake in the injection port around the fuel addition valve, mounting portion of the fuel addition valve The frequency of troublesome cleaning work such as disassembling and cleaning can be greatly reduced, and the labor and time required for the cleaning work can be reduced, and the work burden can be greatly reduced.

It is sectional drawing which shows an example of the form which implements this invention. It is a sectional view for explaining about the shape forming deposit.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows an example of an embodiment of the present invention. In the figure, 1 is an exhaust system path, 2 is an exhaust brake interposed in the exhaust system path 1, and the exhaust brake 2 is tilted. The exhaust system path 1 is opened and closed by a butterfly-type valve body 4 tilting about the shaft 3.

  Further, the housing 5 of the exhaust brake 2 is provided with a fuel addition valve 6 so that the fuel F can be injected toward the valve body 4, and the valve body 4 is tilted at a fully opened position (FIG. 1). The reflecting portion 8 is provided so that the injected fuel F from the fuel addition valve 6 can collide and rebound to the upstream side at a tilting position along the flow of the exhaust gas 7 shown in FIG.

  That is, the reflecting portion 8 is provided with an inclined surface 8a that gradually approaches the fuel addition valve 6 side at an inclination angle θ with respect to the flow direction of the exhaust gas 7, and the fuel addition valve is provided on the inclined surface 8a. The injected fuel F from 6 collides and is bounced back to the upstream side.

FIG. 2 illustrates the deposit 10 formed around the injection port of the fuel addition valve 6. The deposit 10 can be used for a short time such as a delivery vehicle for delivering goods to a courier or a convenience store. In the case of a vehicle having an operation mode in which the vehicle is repeatedly stopped, the operating state in which the temperature of the exhaust gas 7 is low and the flow is slow is intermittently continuous. Therefore, the fuel F around the injection port of the fuel addition valve 6 A cylindrical deposit 10 is formed by accumulating and accumulating grains and soot, and the deposit 10 grows within the operating range of the exhaust brake 2 shown as the tilting locus 9 of the valve body 4 in FIG. In this case, the valve body 4 tilts and interferes with the deposit 10 every time the exhaust brake 2 is operated.

  Thus, if the fuel addition structure is configured as described above, the injected fuel F from the fuel addition valve 6 can be used when the exhaust brake 2 is inactive and the valve body 4 is in the fully tilted position. By colliding with the reflecting portion 8 of the valve body 4 and bounced upstream, it mixes as a counter flow with the flow of the exhaust gas 7, and by striking the flow of the exhaust gas 7 from the front, evaporation and dispersion are significantly promoted. become.

  When the evaporation and dispersion of the fuel F are promoted, the fuel F becomes an HC gas and reaches the oxidation catalyst in a well dispersed state. The oxidation catalyst effectively causes an oxidation reaction to efficiently exhaust the fuel F. Since the temperature of the gas 7 can be raised, the forced regeneration of the particulate filter can be completed in as little time as possible.

Further , since the fuel addition valve 6 is provided in the housing 5 of the exhaust brake 2, even if a deposit 10 is formed around the injection port of the fuel addition valve 6 and grows within the operating range of the exhaust brake 2 , the exhaust brake 2 The valve body 4 tilts and interferes with the deposit 10 each time the valve is actuated, whereby the deposit 10 is broken and further growth is prevented.

Therefore, according to the above-described embodiment, the fuel F from the fuel addition valve 6 collides with the reflecting portion 8 of the valve body 4 of the exhaust brake 2 and bounces back to the upstream side, thereby mixing as a counter flow with the flow of the exhaust gas 7. It is possible to significantly accelerate the evaporation and dispersion of the fuel F by hitting the flow of the exhaust gas 7 from the front, and the operating range of the exhaust brake 2 of the deposit 10 around the injection port of the fuel addition valve 6. Since it can be prevented from growing to the inside, the frequency of troublesome cleaning work such as disassembling and cleaning the mounting portion of the fuel addition valve 6 can be greatly reduced, and labor and time required for the cleaning work can be reduced. Thus, the work load can be greatly reduced.

  The fuel addition structure of the present invention is not limited to the above-described embodiments, and various changes can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Exhaust system path 2 Exhaust brake 4 Valve body 5 Housing 6 Fuel addition valve 7 Exhaust gas 8 Reflecting part 9 Tilt locus 10 Deposit F Fuel

Claims (1)

A fuel addition valve is provided in an exhaust brake housing that opens and closes an exhaust system path by a butterfly-type valve body so that fuel can be injected toward the valve body, and the valve body from the fuel addition valve is tilted when fully opened. A fuel addition structure characterized in that a reflecting portion is provided so that the injected fuel can collide and bounce back to the upstream side.

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