JPH0587218U - Vehicle exhaust purification device - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the NOx purification efficiency of the catalyst of the vehicle exhaust purification system. An exhaust emission control device for a vehicle having a NOx purification catalyst device (30) in an exhaust passage (20), wherein a light oil supply device (40) is provided in the exhaust passage (20) upstream of the catalyst device (30).
The gasification and mixing promoting means 10 is provided between the catalyst 40 and the catalyst device 30. The internal combustion engine 60 also includes a rotation sensor 62 and a load sensor 64.
On the other hand, a catalyst temperature sensor 35 is arranged near the catalyst device 30. Then, the control unit 50 controls the light oil supply device 40 based on the detection values of the catalyst temperature sensor 35, the rotation sensor 62, and the load sensor 64 to supply an appropriate amount of light oil into the exhaust passage 20. The light oil supplied into the exhaust passage 20 is sprayed on the gasification and mixing promotion means 10 to promote the gasification and mixing with the exhaust gas, so that the NOx purification capacity of the catalyst device 30 is sufficiently drawn out.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a catalyst device for purifying nitrogen oxides of exhaust gas from an internal combustion engine.

[0002]

[Prior Art]

 In recent years, regulations on exhaust gas from vehicles have become stricter from the viewpoint of environmental problems. The harmful components contained in the exhaust gas of vehicles equipped with an internal combustion engine are mainly nitrogen oxides (NOx), hydrocarbons (HC), and carbon monoxide (CO). A method of purifying using a catalyst has been widely used. In addition, various measures have been taken to improve the efficiency of catalyst purification.

Since the efficiency of action of the catalyst greatly changes with temperature, strict temperature control is required. Japanese Utility Model Application No. 3-19047 proposes a device that includes a heat storage body and that keeps the temperature of the exhaust gas within the activation temperature range of the catalyst by heat exchange between the heat storage body and the exhaust gas. In a diesel engine in which the exhaust gas contains a small amount of HC and a large amount of O ₂ exists in the exhaust gas, it is necessary to add HC as a reducing agent to the exhaust gas in order to efficiently remove NOx by a catalyst. Light oil is mainly used as the HC source.

FIG. 5 is an explanatory view showing the configuration of a conventional NOx purification catalyst device. A catalyst device 30 is provided in the exhaust passage 20 of the internal combustion engine 60. A light oil jet 41 is provided in the exhaust passage 20 on the upstream side of the catalyst device 30, and the light oil supply device 40 jets light oil into the exhaust passage 20 in a mist state via the light oil jet 41. A catalyst temperature sensor 35 is arranged near the upstream of the catalyst device 30, and a rotation sensor 62 for detecting the engine rotation speed and a load sensor 64 for detecting the engine load are arranged in the internal combustion engine 60. The catalyst temperature sensor 35, the rotation sensor 62, the load sensor 64, and the light oil supply device 40 are connected to the control unit 50 by wiring. Here, the catalyst device 30 is, for example, a monolithic catalytic converter, in which a carrier 31 carries a NOx purification catalyst.

The control unit 50 determines whether or not the catalyst is at the activation temperature based on the detection value of the catalyst temperature sensor 35. When the catalyst is at the activation temperature, the control unit 50 sends a command to the light oil supply device 40 based on the detection values of the rotation sensor 62 and the load sensor 64 to supply an appropriate amount of light oil into the exhaust passage 20. To purify NOx with a catalyst.

[0006]

[Problems to be solved by the device]

 In the conventional NOx purification catalyst device described above, when light oil is supplied into the exhaust passage, light oil is merely atomized and ejected from the light oil ejection port, so gasification of light oil is insufficient. In some cases, the mixture of exhaust gas and light oil gas was insufficient. Liquid gas oil is less reactive than gasified gas oil, so if the gasification of gas oil is insufficient, the supplied gas oil cannot be used effectively. Further, if the exhaust gas and the light oil gas are not sufficiently mixed, the light oil gas (HC) passing through the catalyst is unevenly distributed, and the catalyst is partially deficient in HC, and the NOx purification capacity is deteriorated.

The present invention has been made in view of the above, and provides a NOx purification catalyst device that promotes gasification of light oil and mixing of exhaust gas with light oil gas to effectively utilize the NOx purification capacity of the catalyst. To do.

[0008]

[Means for Solving the Problems]

 For this reason, the present invention includes a catalyst for purifying nitrogen oxides in an exhaust passage of an internal combustion engine, an engine speed detecting means, an engine load detecting means, a catalyst temperature detecting means, and detecting means for detecting these. In a vehicle exhaust gas purification device equipped with a light oil supply control unit that supplies the amount of light oil according to the engine speed and the engine load to the catalyst upstream side exhaust passage when the catalyst temperature is above the activation temperature based on the value, A gasification and mixing promotion unit that promotes gasification of light oil and mixing with exhaust gas is provided in the exhaust passage between the unit and the catalyst, and the supplied light oil is sprayed toward the gasification and mixing promotion unit.

[0009]

In this configuration, the light oil supply control means determines whether the catalyst is at the activation temperature based on the detection value of the catalyst temperature detection means, and if it is at the activation temperature, the engine rotation speed detection means and the engine load are detected. An optimum amount of light oil is supplied from the light oil ejection port into the exhaust passage according to the detection value of the detection means. The light oil is sprayed in a mist form from the light oil jet toward the gasification and mixing promotion means, and the non-gasified light oil is captured by the gasification and mixing promotion means and gasified by the heat from the exhaust. Further, when passing through the gasification and mixing promoting means, the mixing of the exhaust gas and the light oil gas is also promoted.

[0010]

【Example】

 FIG. 1 is an explanatory view showing a NOx purification catalyst device according to a first embodiment of the present invention. A catalyst device 30 is interposed in the exhaust passage 20 of the internal combustion engine 60, and a catalyst temperature sensor 35 as a catalyst temperature detecting means is arranged near the upstream of the catalyst device 30. A gasification and mixing promotion means 10 is provided upstream of the catalyst temperature sensor 35, and a light oil jet port 41 is provided upstream of the gasification and mixing promotion means 10. The light oil supply device 40 supplies the light oil to the light oil jet 41. The internal combustion engine 60 is provided with a rotation sensor 62 as an engine rotation speed detection means and a load sensor 64 as engine load detection means.The rotation sensor 62, the load sensor 64, and the light oil supply device 40 are connected to the control unit 50 by wiring. Connected with.

The control unit 50 controls the light oil supply device 40 to supply the light oil into the exhaust passage 20 when the detected value obtained from the catalyst temperature sensor 35 is the activation temperature of the catalyst. The control unit 50 optimally adjusts the amount of light oil supplied based on the detection values of the rotation sensor 62 and the load sensor 64. Therefore, the light oil supply control means is composed of the control unit 50 and the light oil supply device 40.

The details of the gasification and mixing promoting means 10 are shown in FIG. A bead holding net 14 made of stainless steel, for example, is provided at the most upstream part and the most downstream part of the housing 12 interposed in the exhaust passage 20, and the space between the bead holding nets 14 is, for example, ceramic beads. 16 filled. Of the atomized light oil supplied from the light oil jet port 41, particles of light gas oil that have not been gasified adhere to the ceramic beads 16 and are gasified by the heat of exhaust gas. Further, the exhaust gas flowing between the beads 16 promotes the mixing of the exhaust gas and the light oil gas. It should be noted that it is conceivable to use a stainless steel chip or the like instead of the ceramic beads 16.

In such a configuration, when the catalyst temperature reaches the activation temperature, the light oil corresponding to the engine operating state at that time is supplied into the exhaust passage 20 through the light oil jet port 41. At this time, since the light oil jet port 41 is a sprayer, the light oil is atomized and sprayed to the downstream gasification and mixing promotion means 10. Most of the atomized gas oil is gasified before reaching the gasification and mixing promotion means 10, but the gas oil particles that have reached the gasification and mixing promotion means 10 without being gasified are captured by the gasification and mixing promotion means 10. And is gasified by the heat from the exhaust. Further, when the exhaust gas passes through the gasification mixing promoting means 10, the flow is disturbed, so that the mixing of the light oil gas and the exhaust gas is promoted. Therefore, the gas mixture of the exhaust gas and the light oil that has passed through the gasification and mixing promoting means 10 is sufficiently gasified and mixed with the light oil. it can.

3 and 4 show another embodiment of the gasification mixing promoting means. In this embodiment, a plurality of nets 18 made of, for example, stainless steel are connected in a housing 12 provided in an exhaust passage 20. As shown in FIG. 4, the mesh 18 made of stainless steel has a very fine lattice, and out of the atomized gas oil supplied from the gas oil jet 41, particles of gasified gas oil are trapped in the mesh 18. It is gasified by the heat of exhaust gas. By connecting a plurality of nets 18 to each other, it is possible to almost completely capture ungasified gas oil particles and gasify them. Further, exhaust gas and gas oil gas are sufficiently mixed.

[0015]

[Effect of the device]

 As described above, according to the present invention, the gasification and mixing promoting means is interposed between the gas oil jet in the exhaust passage and the catalyst to capture and gasify ungasified gas oil particles, and to further exhaust gas and gas oil gas. By promoting the mixing, the NOx purification capacity of the catalyst can be effectively used and the NOx purification efficiency can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a NOx purification catalyst device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing the details of a gasification mixing promoting means of the above embodiment.

FIG. 3 is a configuration diagram showing another embodiment of a gasification mixing promoting means.

FIG. 4 is a front view of the mesh of the gasification mixing promoting means of FIG.

FIG. 5 is an explanatory view showing a conventional NOx purification catalyst device.

[Explanation of symbols]

 10 Gasification and mixing promoting means 20 Exhaust passage 30 Catalyst device 35 Catalyst temperature sensor 40 Light oil supply device 50 Control unit 60 Internal combustion engine 62 Rotation sensor 64 Load sensor

Claims (1)

[Scope of utility model registration request] 1. A nitrogen oxide purifying catalyst is provided in an exhaust passage of an internal combustion engine, and an engine speed detecting means, an engine load detecting means, a catalyst temperature detecting means, and detection values of these detecting means are used. In a vehicle exhaust gas purification device equipped with a light oil supply control means for supplying a light oil amount corresponding to the engine speed and the engine load to the catalyst upstream side exhaust passage when the catalyst temperature is equal to or higher than the activation temperature, In the exhaust passage between
An exhaust emission control device for a vehicle, comprising: a gasification mixing promoting means for promoting gasification of light oil and mixing with exhaust gas, and spraying the supplied light oil toward a gasification mixing promoting section.