JP4163453B2 - Injection pipe assembly structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an assembly structure of an injection pipe.
[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) emitted 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. If necessary, fuel is added to the exhaust gas on the upstream side, and the added fuel is pyrolyzed in high-temperature exhaust gas to produce a large amount of hydrocarbons, which are then oxidized on the oxidation catalyst. It has been proposed that the catalyst bed temperature be positively increased by the heat of reaction.
[0007]
As described above with some examples, 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. For example, in Japanese Patent Laid-Open No. 2001-280125, 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. Means for supplying exhaust purification catalyst have been proposed above, and 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. Has been made.
[0008]
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. Japanese Patent Laid-Open No. 2000-240429 has already proposed means for adding fuel with an injector in the middle of an exhaust pipe.
[0009]
[Problems to be solved by the invention]
However, in order to extract a part of the fuel from the fuel supply system arranged on the intake side of the engine and lead it to the exhaust side of the engine in consideration of safety, the rear of the engine with relatively little interference is routed. It is preferable to arrange an injection pipe, and the length of the injection pipe is unavoidable. However, when the injection pipe is a long integrally formed product, it causes a problem that it becomes difficult to handle when carrying it in and out as a part. Further, when the injection pipe is divided into a plurality of parts, there is a concern that fuel may leak to the engine exhaust side having a high temperature due to the formation of a plurality of connecting portions in the injection pipe.
[0010]
The present invention has been made in view of the above-mentioned circumstances, and the injection pipe has a divided structure that is easy to handle as a component, and leaks toward the engine exhaust side where the temperature is high even in the event of a fuel leak from the connecting portion. It is an object of the present invention to reliably prevent fuel scattering.
[0011]
[Means for Solving the Problems]
In the present invention, a part of the fuel extracted from the fuel supply system arranged on the intake side of the engine is routed behind the engine with respect to the fuel addition injector provided on the inlet side of the exhaust purification catalyst in the middle of the exhaust pipe. In the assembly structure of the injection pipe that is guided, the injection pipe is divided into a pair of pipe pieces with the location located on the intake side behind the engine as the connection part, and the joint end of the pipe piece on the exhaust side is the engine And a shielding surface is formed on the bracket so as to prevent scattering of leaked fuel from the connecting portion toward the exhaust side of the engine.
[0012]
Thus, in this way, since the injection pipe is divided into a pair of pipe pieces, both pipe pieces are formed as relatively short parts, and both pipe pieces are carried as parts. Easy handling when unloading.
[0013]
In addition, since the connection part of both pipe pieces is located on the intake side behind the engine, and a shielding surface is formed on the bracket that supports the joint end of the pipe piece on the exhaust side, both pipes should be Even if the fuel leaks from the connecting portion of the pieces, the leakage of the leaked fuel toward the exhaust side of the engine is reliably prevented.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0015]
1 to 3 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. The intake air 4 guided from the air cleaner 3 is sent to the compressor 2a of the turbocharger 2 through the intake pipe 5, and the intake air 4 pressurized by the compressor 2a is sent to the intercooler 6 to be cooled, The intake air 4 is further guided from the cooler 6 to the intake manifold 7 and is distributed to each cylinder 8 of the diesel engine 1 (the case of in-line 6 cylinders is illustrated in FIG. 1).
[0016]
Further, the exhaust gas 9 discharged from each cylinder 8 of the diesel engine 1 is sent to the turbine 2b of the turbocharger 2 through the exhaust manifold 10, and the exhaust gas 9 that has driven the turbine 2b passes through the exhaust pipe 11. It is designed to be discharged outside the vehicle.
[0017]
An exhaust purification catalyst 12 such as a NOx storage reduction catalyst or an oxidation catalyst is provided in the middle of the exhaust pipe 11, and a fuel addition injector 13 is provided on the inlet side of the exhaust purification catalyst 12. Has been. A part of the fuel extracted from the fuel supply pump 14 (fuel supply system) disposed on the intake side of the diesel engine 1 is guided to the fuel addition injector 13 by the injection pipe 15.
[0018]
Here, the injection pipe 15 is arranged so as to be routed from the fuel supply pump 14 to the fuel addition injector 13 around the rear (the right side in FIG. 1) of the diesel engine 1 with relatively little interference. A portion located on the intake side (the lower side in FIG. 1) behind the diesel engine 1 is divided into a pair of pipe pieces 15a and 15b with a connection portion. Note that “Fr” in FIG. 1 indicates the vehicle front direction.
[0019]
Further, the joint end of the pipe piece 15 a on the exhaust side of the pair of pipe pieces 15 a, 15 b is supported by a bracket 16 attached to the back surface of the diesel engine 1. As shown in enlarged views in FIGS. 2 and 3, the bracket 16 has leaked fuel from the connecting portion of both pipe pieces 15 a and 15 b toward the exhaust side of the diesel engine 1 (the right side in FIGS. 2 and 3). A shielding surface 17 that extends over a wide range is formed around the penetrating portion of the pipe piece 15a so as to prevent scattering.
[0020]
Here, the structure of the connecting portion of both pipe pieces 15a and 15b will be described in detail. A male connector 20 comprising a tubular male screw portion 19 having a nut-shaped flange portion 18 on the proximal end side is attached to the joint end portion of the pipe piece 15a on the exhaust side. The male screw part 19 of the male connector 20 is passed through the hole of the bracket 16 from the exhaust side, and tightened with the nut 21 from the intake side (left side in FIGS. 2 and 3), whereby the pipe piece 15a on the exhaust side is connected. The joint end is fixed to the bracket 16.
[0021]
Then, the joint end of the intake-side pipe piece 15b is put on the tip of the male screw portion 19 of the male connector 20, and is tightened by a female connector 22 formed as a socket-type female screw. In addition, pressure is maintained between the tapered peripheral surface inside the female connector 22 and the tip of the male screw portion 19 of the male connector 20. In this way, the pipe connectors 15a and 15b are connected to each other by screwing the female connector 22 into the male screw portion 19 of the male connector 20 and tightening it. Note that reference numeral 23 in FIG. 3 denotes a detent of the flange portion 18 attached to the side surface of the bracket 16 on the exhaust side.
[0022]
Thus, if the assembly structure of the injection pipe 15 is configured in this way, since the injection pipe 15 is divided into a pair of pipe pieces 15a and 15b, each of the pipe pieces 15a and 15b is relatively short. It will be formed as a part, and handling in the case of carrying in and carrying out both pipe pieces 15a and 15b as a part becomes easy.
[0023]
Further, the connecting portion of both pipe pieces 15a, 15b is located on the intake side behind the diesel engine 1, and a shielding surface 17 is formed on the bracket 16 that supports the joint end portion of the pipe piece 15a on the exhaust side. Therefore, even if a situation occurs in which fuel leaks from the connecting portion of both pipe pieces 15a and 15b, the leakage of the leaked fuel toward the exhaust side of the diesel engine 1 is reliably prevented. become.
[0024]
Therefore, according to the said form example, the handling at the time of carrying in / out as components can be made easy by dividing | segmenting the injection pipe 15 into a pair of pipe piece 15a, 15b. In addition, even in the unlikely event of a fuel leak from the connection portion of the pair of pipe pieces 15a, 15b that is divided, fuel scattering toward the exhaust side can be reliably prevented and high safety can be ensured.
[0025]
In addition, the assembly structure of the injection pipe of the present invention is not limited to the above-described embodiment, and can be applied to engines other than diesel engines, and the extraction of fuel into the fuel addition injector Of course, it may be performed from a fuel supply system other than the fuel supply pump, and other various modifications may be made without departing from the scope of the present invention.
[0026]
【The invention's effect】
According to the assembly structure of the injection pipe of the present invention described above, by dividing the injection pipe into a pair of pipe pieces, handling when carrying in and out as parts can be facilitated. Moreover, even in the unlikely event of a fuel leak from the connection part of the paired pipe pieces, it is possible to reliably prevent fuel scattering toward the exhaust side and to ensure high safety. obtain.
[Brief description of the drawings]
FIG. 1 is a plan view schematically showing an example of an embodiment for carrying out the present invention.
2 is a perspective view showing details of a connecting portion of both pipe pieces of FIG. 1; FIG.
FIG. 3 is a front view of FIG. 2;
[Explanation of symbols]
1 Diesel engine (engine)
9 exhaust gas 11 exhaust pipe 12 exhaust purification catalyst 13 fuel addition injector 14 fuel supply pump (fuel supply system)
15 Injection pipe 15a Exhaust side pipe piece 15b Intake side pipe piece 16 Bracket 17 Shielding surface

Claims (1)

A part of the fuel extracted from the fuel supply system arranged on the intake side of the engine is guided around the rear of the engine to the fuel addition injector provided on the inlet side of the exhaust purification catalyst in the middle of the exhaust pipe. In the assembly structure of the injection pipe,
The injection pipe is divided into a pair of pipe pieces with the location located on the intake side behind the engine as a connecting portion, and the joint end of the exhaust pipe piece is supported by a bracket attached to the back of the engine. An assembly structure of an injection pipe, wherein a shielding surface is formed on the bracket to prevent leakage of leaked fuel from the connecting portion toward the exhaust side of the engine.

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