JP4307855B2 - Exhaust purification equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust emission control device.
[0002]
[Prior art]
Conventionally, exhaust purification has been performed with an exhaust purification catalyst installed in the middle of an exhaust pipe. As this type of exhaust purification catalyst, when the exhaust air-fuel ratio is lean, NOx in the exhaust gas is oxidized and temporarily stored in the form of nitrate, and when the oxygen concentration in the exhaust gas decreases, unburned HC or There is known an NOx occlusion reduction catalyst having the property of decomposing and releasing NOx through CO or the like for reduction and purification.
[0003]
In this NOx occlusion reduction catalyst, when the occlusion amount of NOx increases and reaches the saturation amount, no more NOx can be occluded. Therefore, the oxygen concentration of the exhaust gas that periodically flows into the NOx occlusion reduction catalyst is reduced. It is necessary to reduce and release NOx by decomposition. For example, when used in a gasoline engine, the operating air-fuel ratio of the engine is reduced (the engine is operated at a rich air-fuel ratio), thereby reducing the oxygen concentration in the exhaust gas and unburned HC in the exhaust gas. Reduction components such as CO can be increased to promote decomposition and release of NOx.
[0004]
However, when the NOx storage reduction catalyst is used as an exhaust gas purification device for a diesel engine, it is difficult to operate the engine at a rich air-fuel ratio. For this reason, by adding fuel to the exhaust gas upstream of the NOx storage reduction catalyst, the added fuel is thermally decomposed in high-temperature exhaust gas to produce a large amount of hydrocarbon, and this hydrocarbon is reduced. It is necessary to reduce the oxygen concentration in the exhaust gas by reacting with oxygen on the NOx storage reduction catalyst as an agent.
[0005]
On the other hand, as a measure to reduce particulate matter (particulate matter) discharged from diesel engines, an exhaust purification catalyst such as an oxidation catalyst supported on a particulate filter or a flow-through oxidation catalyst is placed in the middle of the exhaust pipe. Has already been equipped. By using such an oxidation catalyst, it is possible to promote the oxidation reaction of the particulates collected in the particulate filter and the particulates in the exhaust gas, and to reduce the particulates by combustion removal.
[0006]
However, such an oxidation catalyst has an active temperature region, and if the operation state continues at an exhaust temperature that falls below the lower limit temperature of activation, the oxidation catalyst will not be activated and the particulates will not be burned and removed well. The malfunction that can happen. Therefore, if necessary, fuel is added to the upstream exhaust gas, and the added fuel is pyrolyzed in high-temperature exhaust gas to produce a large amount of hydrocarbons. It has been proposed that the catalyst bed temperature be positively increased by the reaction heat in the reaction.
[0007]
As described above with some examples, the fuel is added to the upstream side of the exhaust purification catalyst (NOx storage reduction catalyst, oxidation catalyst, or particulate filter carrying these) installed in the middle of the exhaust pipe. The idea itself has been proposed in the past.
[0008]
For example, a fuel addition injector is installed in an exhaust port of a cylinder head, fuel is added to exhaust gas by exhaust port injection by the injector, and the added fuel is stirred by a turbine and supplied to an exhaust purification catalyst. A means for adding fuel to exhaust gas by such exhaust port injection has already been developed for practical use in some passenger cars and the like (for example, Patent Document 1). reference).
[0009]
However, in large vehicles equipped with diesel engines, it is possible to add fuel by installing an injector on the inlet side of the exhaust purification catalyst in the middle of the exhaust pipe from the viewpoint of ensuring the reliability of the EGR device and turbocharger. A means for adding fuel with an injector in the middle of an exhaust pipe has been proposed (see, for example, Patent Document 2).
[0010]
[Patent Document 1]
JP 2001-280125 A [Patent Document 2]
Japanese Patent Laid-Open No. 2000-240429
[Problems to be solved by the invention]
However, when the injector is provided in the middle of the exhaust pipe as described above, there is a possibility that a portion exposed to the outside of the exhaust pipe of the injector may be damaged by flying stones that jump from the road surface during traveling.
[0012]
The present invention has been made in view of the above circumstances, and an object thereof is to reliably protect an injector provided in the middle of an exhaust pipe from a stepping stone from a road surface.
[0013]
[Means for Solving the Problems]
The present invention is equipped with an exhaust purification catalyst in the middle of an exhaust pipe, and the front end portion is directed downwardly on the outside in the bending direction of the bent portion that is bent upstream of the exhaust purification catalyst in the exhaust pipe toward the rear of the vehicle. In addition, a fuel addition injector is disposed in a posture in which the base end portion is inclined outward in the vehicle width direction, and the injector is concealed between the bent portion and a peripheral structure located in front of the vehicle, and the periphery of the injector Further, the present invention relates to an exhaust emission control device characterized in that a water jacket is formed in the water jacket and an outer side in the vehicle width direction of the injector is protected by a water pipe for supplying and discharging cooling water to and from the water jacket .
[0014]
In this way, the flying stone that jumps up from the road surface during traveling is blocked by the bent portion of the exhaust pipe , the surrounding structure, and the water pipe , so that it does not hit the injector, and damage by the flying stone of the injector is avoided in advance. Will be.
[0017]
Also, since Lee Njekuta is located the leading edge in a posture and a proximal end inclined outward in the vehicle width direction downward, during maintenance such as replacement of the injector, to desorb the injector from the outside in the vehicle width direction As a result, the assembly workability and maintainability are greatly improved.
[0018]
Furthermore, in the present invention, it is preferable to protect the outer side in the vehicle width direction of the base end portion of the injector with a fuel pipe that guides fuel to the base end portion of the injector.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
1 to 4 show an example of an embodiment for carrying out the present invention. Reference numeral 1 in FIG. 1 denotes a diesel engine equipped with a turbocharger 2, and an intake pipe led from an air cleaner 3 is connected to an intake pipe. 5 is introduced to the compressor 2a of the turbocharger 2 and pressurized, and the pressurized intake air 4 is distributed and introduced to each cylinder of the diesel engine 1 via the intercooler 6.
[0020]
Further, exhaust gas 8 discharged from each cylinder of the diesel engine 1 through the exhaust manifold 7 is sent to the turbine 2b of the turbocharger 2 through the exhaust pipe 9, and the exhaust gas 8 driving the turbine 2b is of a catalyst regeneration type. Particulates are collected through the particulate filter 10 (exhaust gas purification catalyst) and then discharged outside the vehicle.
[0021]
Further, on the exhaust pipe 9 upstream of the bent portion 9a, on the outer side in the bending direction of the bent portion 9a bent in a substantially L shape toward the rear of the vehicle (right side in FIG. 1) upstream of the particulate filter 10 in the exhaust pipe 9. A fuel addition injector 11 is attached along an inclined state with the tip portion directed downward. In addition, the injector 11 is hidden between the bent portion 9a and the oil filter 12 positioned in front of the vehicle and is protected from stepping stones from the road surface.
[0022]
Further, as shown in a schematic cross-sectional view in FIG. 2, an injection space 13 is formed in a direction along the exhaust pipe downstream of the bent portion from the tip portion of the injector 11, and the bent portion 9 a is formed through the injection space 13. Fuel is injected into the flow path in the downstream exhaust pipe 9.
[0023]
In addition, a water jacket 15 having a cylindrical shape substantially concentric with the injector 11 is bored inside the boss portion 14 that holds the injector 11, and the front end side of the injector 11 in the water jacket 15 ( A water supply port 16 is provided on the lower end side and away from the exhaust pipe 9, and a drain port 17 is provided on the water jacket 15 on the base end side (upper end side) of the injector 11 and on the side close to the exhaust pipe 9. Is provided.
[0024]
As shown in FIGS. 3 and 4, a water pipe 18 that guides a part of the cooling water of the diesel engine 1 is connected to the water supply port 16, and is extracted from the water jacket 15 to the drain port 17. A water pipe 19 for returning cooling water to a thermostat (temperature controller) (not shown) is connected. The water pipes 18 and 19 also protect the outside of the injector 11 in the vehicle width direction.
[0025]
That is, the vehicle width direction outer side portion of the base end portion exposed upward from the boss portion 14 of the injector 11 is hidden by the shadows of the water pipes 18 and 19 with respect to the stepping stones bounced up by the front wheels and coming from the front side of the vehicle. It is.
[0026]
Further, in this embodiment, as clearly shown in FIG. 4, the injector 11 not only inclines the base end portion toward the front of the vehicle but also the base end on the outer side in the vehicle width direction (the right side in FIG. 4). It is arranged with the posture which inclined the part.
[0027]
In the figure, reference numeral 20 denotes a fuel pipe for guiding a part of the fuel guided from a combustion tank (not shown) or the like to the base end portion of the injector 11.
[0028]
Thus, if the exhaust gas purification device is configured in this way, the flying stones that jump from the road surface during travel are blocked by the bent portion 9a of the exhaust pipe 9, the oil filter 12, and the water pipes 18, 19 and do not hit the injector 11. Damage to the injector 11 due to flying stones is avoided in advance.
[0029]
Also, since Lee Njekuta 11 is disposed in a posture tilted and the base end portion toward the tip down to the outside in the vehicle width direction, during maintenance such as replacement of the injector 11, the vehicle width direction outside the injector 11 Therefore, the assembly workability and maintainability are greatly improved.
[0030]
The exhaust purification apparatus of the present invention is not limited to the above-described embodiment. For exhaust purification catalysts that require the addition of hydrocarbons, in addition to catalyst regeneration type particulate filters, NOx reduction catalysts (selection) Reduction type catalyst), NOx occlusion reduction catalyst, particulate filter combined with NOx occlusion reduction catalyst, oxidation catalyst etc. may be adopted, and the fuel added by injector is a general diesel engine In addition to using diesel oil as a fuel for fuel, different types of fuel such as kerosene may be used, and the peripheral structure is not limited to an oil filter, and various other modifications may be made without departing from the scope of the present invention. Of course, it can be added.
[0031]
【The invention's effect】
According to the exhaust emission control device of the present invention described above, various excellent effects as described below can be obtained.
[0032]
Since hurting the stepping stones which jumps from the road surface during (I) run line by the exhaust pipe and the peripheral structure can be prevented hit the injector, it can be avoided in advance damage stepping stones of the injector.
[0033]
Since by utilizing the water pipe for supplying and discharging the cooling water (II) c O over data jacket may protect the vehicle width direction outer side of the injector, it is possible to more reliably protect the injectors.
[0034]
During maintenance such as replacement of (III) b Njekuta, since the injector is easily desorbed from the outside in the vehicle width direction, it is possible to greatly improve the assembling workability and maintainability.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of an embodiment for carrying out the present invention.
FIG. 2 is a cross-sectional view schematically showing a structure of an installation location of the injector of FIG.
FIG. 3 is an external view showing an enlarged detail of an installation location of the injector of FIG. 1;
4 is a view taken in the direction of arrows IV-IV in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Diesel engine 9 Exhaust pipe 9a Bending part 10 Catalyst regeneration type particulate filter (exhaust purification catalyst)
11 Injector 12 Oil filter (peripheral structure)
15 Water jacket 18 Water pipe 19 Water pipe

Claims (2)

Equipped with an exhaust purification catalyst in the middle of the exhaust pipe, with the distal end facing downward and the base end on the outer side in the bending direction of the bent portion of the exhaust pipe bent upstream of the exhaust purification catalyst The fuel addition injector is disposed in a posture inclined to the outside in the vehicle width direction, the injector is concealed between the bent portion and a peripheral structure positioned in front of the vehicle, and a water jacket is provided around the injector. An exhaust emission control device characterized in that an outer side in the vehicle width direction of the injector is protected by a water pipe that is formed and for supplying and discharging cooling water to and from the water jacket . 2. The exhaust emission control device according to claim 1, wherein an outer side in a vehicle width direction of the base end portion of the injector is protected by a fuel pipe that guides fuel to the base end portion of the injector .

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