JPH05918U - Exhaust gas purification device - Google Patents

Abstract

(57) [Summary] [Purpose] It is possible to shorten the reaction start time of the catalyst. [Structure] An electric heater 15 is provided in the exhaust gas passage 12 on the upstream side of the catalyst 13 to heat a part of the exhaust gas to raise its temperature when the exhaust gas temperature is low.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an exhaust gas purifying device, and more particularly to an exhaust gas purifying device for accelerating the reaction start time of a catalyst.

[0002]

[Prior Art]

 The methanol engine is provided with the exhaust gas purification device shown in FIG. 7. As shown in the figure, an oxidation catalyst 3 is provided midway in the exhaust gas passage 2 of the methanol engine 1, and a silencer 4 is provided downstream thereof. This purifying device makes it possible to reburn the unburned fuel that cannot be completely burned in the engine combustion chamber by the oxidation catalyst 3 in the middle of the exhaust gas passage 2 to reduce HC and CO.

[0003]

[Problems to be solved by the device]

 By the way, since the oxidation catalyst 3 is heated to a predetermined temperature or higher by the heat of the exhaust gas and reacts, the catalyst temperature is low for a while after the engine 1 is started, and the exhaust gas temperature is also high. Since it is low, the oxidation catalyst 3 does not react. Therefore, there is a problem that a large amount of unburned HC and CO are discharged and a strong odor is generated.

Therefore, in order to raise the temperature of the exhaust gas, as shown in FIG. 8, an electric heater 5 is provided in the exhaust gas passage 2 upstream of the oxidation catalyst 3. Since the electric heater 5 is wound around the outer periphery of the exhaust gas passage 2 and the amount of exhaust gas is large, a large amount of heating is required to shorten the reaction start time of the catalyst 3, which is not practical. There was a chipping problem.

In this type of purifying device, Japanese Patent Laid-Open No. 62-58007 proposes an “exhaust gas purifying device for a diesel engine” that heats a heater by narrowing the amount of exhaust gas. If the amount is reduced, the engine performance such as fuel consumption and exhaust gas (NOX) will be deteriorated and durability will be affected. Further, Japanese Patent Application Laid-Open No. 52-70224 proposes "catalytic purifying muffler for internal combustion engine". In this proposal, the catalyst is directly heated. There is a problem in that the temperature rises too much, which leads to a decrease in durability, and the structure becomes complicated and costly, making it impractical. Furthermore, although the ceramics are heated, it takes time to start the reaction, and it is difficult to shorten the catalyst reaction start time because the entire exhaust gas is heated.

The present invention was devised to effectively solve the above problems.

An object of the present invention is to provide an exhaust gas purifying apparatus that can raise the temperature of exhaust gas to a temperature higher than the catalytic reaction temperature in a short time and shorten the time when the reaction of the catalyst starts. ..

[0008]

[Means for Solving the Problems]

 An electric heater is provided in the exhaust gas passage on the upstream side of the catalyst to heat and raise a part of the exhaust gas when the temperature of the exhaust gas is low.

[0009]

[Action]

 In this way, since a part of the exhaust gas is heated and heated, the heating amount can be reduced and the heating time can be shortened. Further, a part of the exhaust gas heated and heated by the electric heater starts the reaction of the catalyst, and thereafter, the catalyst is activated by the heat of the reaction, so that the catalyst reaction start time can be shortened and the heating heat amount can be reduced.

[0010]

【Example】

 Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, an exhaust gas passage 12 for transferring exhaust gas emitted from the methanol engine 11 is connected to the methanol engine 11. The exhaust gas passage 12 is provided with an oxidation catalyst 13 and downstream thereof. A silencer 14 is provided on the side.

In particular, in the exhaust gas passage 12 on the upstream side of the oxidation catalyst 13, an electric heater 15 is provided for heating and heating a part of the exhaust gas passing through the exhaust gas passage 12. In the illustrated example, an electric heater 15 is inserted in the center of the exhaust gas passage 12 along the axial direction. A power source 16 is connected to the electric heater 15 and the electric heater 15 is energized. A controller 17 that turns off is connected. A sensor 18 that detects the temperature of the oxidation catalyst 13 is connected to the controller 17. That is, the controller 17 is preliminarily input with the reaction temperature of the oxidation catalyst 13, and energizes the electric heater 15 when the actual temperature obtained from the sensor 18 is lower than the catalyst reaction temperature, and energizes when the reaction temperature exceeds the reaction temperature. It is configured to stop.

FIG. 2 is a flow chart showing heating control by the electric heater 15.

That is, the exhaust gas discharged from the engine 11 when it is started passes through the oxidation catalyst 13 provided in the exhaust gas passage 12 and is discharged. When the exhaust gas passes through, the temperature of the oxidation catalyst 13 is detected by the sensor 18. The temperature detected by the sensor 18 is input to the controller 17, and the controller 17 compares and examines the catalyst reaction temperature input in advance and the actual temperature obtained from the sensor 18.

In particular, since the exhaust gas is exhausted at a relatively low temperature immediately after the engine is started, the electric heater 15 is energized when it is detected that the actual temperature obtained from the sensor 18 is lower than the catalyst reaction temperature. It Since the electric heater 15 is provided at the central portion of the cross section of the exhaust gas passage 12, only the exhaust gas passing through the central portion of the cross section is heated and heated. The exhaust gas heated and heated flows down and is introduced into the central portion of the oxidation catalyst 13 to heat the central portion of the oxidation catalyst 13. Therefore, the oxidation catalyst 13 starts the reaction from the central portion thereof, the reaction spreads over the entire catalyst, and all unburned gas in the exhaust gas starts to burn.

When the sensor detects that the temperature of the exhaust gas has exceeded the catalyst reaction temperature, the controller 17 stops energizing the electric heater 15.

As described above, in the present invention, since a small amount of exhaust gas is heated and heated, the temperature rise of the exhaust gas can be accelerated and the catalyst reaction temperature can be reached in a short time, and the heating heat amount is small. Complete. Therefore, the amount of unburned HC and CO emitted can be reduced, and the generation of odor can also be reduced.

3 to 6 show another embodiment of the present invention, each showing an electric heater 15 for heating a part of the exhaust gas.

In FIG. 3, a cylindrical partition member 19 is provided in the exhaust gas passage 12 so as to be located upstream of the oxidation catalyst 13 and divide the exhaust gas passage 12 into a central portion side and an outer peripheral portion side. The electric heater 15 is wound around the outer periphery of the partition member 19. Therefore, the exhaust gas passing through the inside of the partition member 19 is heated and heated. A material having high thermal conductivity such as copper is selected for the partition member 19.

4 to 6 show an electric heater 15 provided so as to traverse the inside of the partition member 19, one electric heater 15 is provided in FIG. 4, and FIG. 5 is substantially Y-shaped. An electric heater 15 is provided, and in FIG. 6, the electric heater 15 is provided in the shape of a cross.

[0021]

[Effect of the device]

 In summary, according to the present invention, since a small amount of exhaust gas is heated and heated, the temperature rise of the exhaust gas can be accelerated and the catalyst reaction temperature can be reached in a short time. It is possible to reduce emissions of HC and CO and generation of odor.

[Brief description of drawings]

FIG. 1 is a view showing a purifying device of the present invention.

FIG. 2 is a diagram showing a flow of heating temperature raising control.

FIG. 3 is a diagram showing another embodiment.

FIG. 4 is a diagram showing another embodiment.

FIG. 5 is a diagram showing another embodiment.

FIG. 6 is a diagram showing another embodiment.

FIG. 7 is a diagram showing a conventional purification device.

FIG. 8 is a diagram showing a conventional purification device.

[Explanation of symbols]

 12 exhaust gas passage 13 catalyst 15 electric heater

Claims (1)

[Claims for utility model registration] Claim 1. An exhaust gas purification device characterized in that an electric heater is provided in the exhaust gas passage upstream of the catalyst for heating a portion of the exhaust gas to raise its temperature when the exhaust gas temperature is low. apparatus.