JPH04311618A - Exhaust purifier of engine - Google Patents

Abstract

PURPOSE:To prevent noxious substances from being emitted from an absorbent in an engine at a high temperature while purifying efficiently the noxious substance in the start of the engine by providing an adsorbing receptacle capable of changing over to an exhaust path behind a catalyzer container for purifying exhaust gas of the engine. CONSTITUTION:Exhaust gas exhausted from a combustion chamber 1 of an engine is introduced through an exhaust valve 3 into a catalyzer container 5 filled with an exhaust purifying catalyzer. While noxious substances in the exhaust gas are here purified, the purification efficiency of the catalyzer is low in the start of the engine at a low temperature, so that HC or the like is absorbed by an adsorbing receptacle 7 provided behind and filled with an adsorbent. When the engine is warmed, an electromagnetic valve 15 is operated to open exhaust change-over valve 8 so that the exhaust flows to an exhaust path 16. Also, by enabling the atmospheric air to flow into the adsorbing receptacle 7 through a check valve 10 for operating a blast pump 11, the noxious substances exhausted by the adsorbent in high temperature are purified through the catalyzer container 5.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine exhaust gas purification system having means for purifying harmful substances in exhaust gas when the engine is cold and the exhaust gas purification rate of the catalyst is low when the engine is started.

0002

2. Description of the Related Art As a conventional engine exhaust purification device, as shown in FIG.
, there is one that is equipped with an adsorption container 7 filled with an adsorbent that adsorbs harmful substances in the exhaust gas in front of a catalyst container 5 that houses an exhaust purification catalyst that purifies the exhaust gas discharged through the exhaust port 4 . A catalyst made of a ceramic or metal carrier coated with a precious metal is fixedly stored in the catalyst container 5, and the temperature of the inflowing exhaust gas is 3.
When the engine is warmed up to 00°C or higher, it exhibits a high exhaust purification rate of over 90%. However, since the purification rate of the catalyst is low when the exhaust gas temperature is low immediately after the engine is started, harmful substances such as hydrocarbons (HC) are adsorbed by the adsorbent in the adsorption container 7 to purify the exhaust gas. In addition, in Figure 6, 2
indicates an intake valve, and 6 indicates a tail pipe.

0003

[Problems to be Solved by the Invention] As shown in FIG. 7, the characteristics of the adsorbent filled in the adsorption container are as follows: As the temperature of the exhaust gas increases, the amount of adsorption increases;
When the temperature reaches 00°C or higher, what has been adsorbed up to that point is released. At this time, if the temperature of the catalyst is high enough, the released harmful substances can be purified, but if the catalyst is not activated, the harmful substances are released into the atmosphere. In a system in which a catalyst is provided behind an adsorbent, it is difficult to raise the temperature of the catalyst, which causes the above-mentioned problems. Adsorbents also tended to deteriorate in performance when exposed to high temperatures. Furthermore, if the adsorption container is installed at a location where the exhaust gas temperature is high, there is also the problem that the amount of adsorption decreases after long distance travel.

0004

[Means for Solving the Problems] The present invention has been made in view of these problems, and includes a catalyst container housing an exhaust purification catalyst for purifying engine exhaust gas, and a catalyst container located behind the catalyst container. The exhaust passage is switchable between an exhaust passage equipped with an adsorption container filled with an adsorbent that adsorbs harmful substances and an exhaust passage without an adsorption container. The present invention relates to an engine exhaust purification device characterized in that it is equipped with means for introducing into the engine intake system or in front of a catalyst container.

When the apparatus of the present invention is used to purify engine exhaust gas, since the gas is at a low temperature when the engine is started, the gas emitted from the catalyst container is passed through an exhaust passage provided with an adsorption container. Then, after the gas temperature has risen, the gas is passed through an exhaust passage without an adsorption vessel. During this time, air is introduced from the front of the adsorption container into the exhaust passage where the passage of exhaust gas is blocked, and air is passed through the adsorption container to release harmful substances from the adsorbent, and then introduced into the engine intake system or in front of the catalyst container to catalyze the Pass it through a container to purify harmful substances. In this way, harmful substances are prevented from being released into the atmosphere from a low temperature state, such as when the engine is started, where the catalyst temperature is low and is not activated, to a high temperature state, and the exhaust gas purification rate can be improved.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described by way of embodiments with reference to the drawings. FIG. 1 shows an apparatus according to a first embodiment of the present invention. In the illustrated device, an intake valve 2 and an exhaust valve 3
A catalyst container 5 is provided in which a fixed catalyst is housed to purify harmful substances in the exhaust gas discharged from the engine combustion chamber 1 and passed through the exhaust port 4, and an adsorbent that adsorbs the harmful substances is provided behind the catalyst container 5. An exhaust passage including an adsorption container 7 filled with the adsorption container and an exhaust passage 16 without an adsorption container are switchably provided. That is, exhaust switching valves 8 are provided at the inlet and outlet of the exhaust passage, and these valves 8 can be opened and closed by a spiral spring 14 and a solenoid valve 15. The illustrated device includes a pipe 12 connecting the rear of the adsorption container 7 and the front of the catalyst container 5,
This pipe is equipped with a solenoid valve 9 and a blower pump 11.

Next, the operation of the illustrated device will be explained. When the engine is in a cold state, the exhaust switching valve 8 is in a position where the exhaust gas is introduced into the adsorption container by the force of the spiral spring 14, and HC and the like are adsorbed by the adsorbent. As the engine gets warmer, the exhaust temperature also rises to 200~
At temperatures near 300°C, HC and the like will be released. This can be detected by measuring the exhaust gas temperature, but it can also be estimated and controlled from the elapsed time after engine startup. When discharge begins, the solenoid valve 15 is activated based on the control signal, and the exhaust switching valve 8 is opened. As a result, the exhaust gas flows into the exhaust passage 16 and does not flow into the adsorption container. The check valve 10 is for allowing atmospheric air to flow into the adsorption container, and by opening the solenoid valve 9 and operating the blower pump 11, the adsorbed HC etc. are introduced to the front of the catalyst. . As a result, the HC is purified by the catalyst which is already active.

FIG. 2 shows a second embodiment of the apparatus. In the device of this example, the adsorption container 7 is integrated with the exhaust passage 16, and the flow of exhaust gas can be switched to the adsorption container or the exhaust passage 16 by the exhaust switching valve 8. The pipe 12 is connected to the intake manifold via a flow rate adjustment valve 13, and the exhaust gas containing a large amount of adsorbed HC is recirculated by the suction negative pressure. Generally, when exhaust gas is recirculated, the engine becomes unstable, but for this purpose, the amount of recirculation is extremely small, so there is no problem.

FIGS. 3 to 5 show apparatuses according to third to fifth embodiments. The illustrated device has an adsorption container 7 located behind the muffler 17.
Equipped with These systems use adsorbents with poor heat resistance, and allow exhaust gas to flow into the adsorption vessel only when the exhaust gas temperature is sufficiently low. In Fig. 3, the exhaust switching valve 8 has a double structure to prevent exhaust from flowing into the adsorption container when the exhaust valve is closed, and to prevent the temperature of the adsorbent from becoming excessive due to the action of cooling fins 18 installed outside the passage. prevent it from rising.

The apparatus shown in FIG. 4 is a system for heating the adsorbent with a heater 19 when the temperature of the adsorbent is too low and it is necessary to promote HC release. The apparatus shown in FIG. 5 uses heat transfer tubes to perform heating for the same purpose, and is to transfer heat from the high temperature section 20 of the exhaust system to the adsorption container (low temperature section 21). To adjust the temperature, turn the contact part 22 on and off.
Do by doing.

[0011]

As explained above, according to the present invention, the configuration is such that an adsorption container is provided behind the catalyst, and when the gas temperature is low, the gas passes through the adsorption container, and as the gas temperature rises, the adsorption container By passing the adsorbed substances through the exhaust passage instead of passing through them, the structure allows the adsorbed substances to be released and introduced into the engine intake system or in front of the catalyst, which improves the heat resistance of the adsorbent and reduces the temperature rise of the catalyst. This has the effect of increasing the exhaust purification rate immediately after the engine starts.

[Brief explanation of the drawing]

FIG. 1 is a layout diagram of an engine exhaust purification device according to a first embodiment of the present invention.

FIG. 2 is a layout diagram of a device according to a second embodiment of the invention.

FIG. 3 is a layout diagram of a device according to a third embodiment of the invention.

FIG. 4 is a layout diagram of a device according to a fourth embodiment of the present invention.

FIG. 5 is a layout diagram of a device according to a fifth embodiment of the present invention.

FIG. 6 is a layout diagram of a conventional engine exhaust purification device.

FIG. 7 is a diagram showing adsorption and release characteristics of harmful components of an adsorbent.

[Explanation of symbols]

1 Engine combustion chamber 2 Intake valve 3 Exhaust valve 4 Exhaust boat 5 Catalyst container 6 Tail pipe 7 Adsorption container 8 Exhaust switching valve 9 Solenoid valve 10 Check valve 11　Blower pump 12 Pipe 13 Flow rate adjustment valve 14 Whirlpool valve 15 Solenoid valve 16 Exhaust passage 17 Muffler 18 Cooling fins 19 Heater 20 Heat exchanger tube/high temperature section 21 Heat exchanger tube/low temperature section 22 Heat exchanger tube/contact part

Claims (1)

[Claims] Claim 1: An exhaust passage comprising a catalyst container containing an exhaust purification catalyst for purifying engine exhaust gas, an adsorption container filled with an adsorbent for adsorbing harmful substances behind the catalyst container, and an adsorption container. 1. An engine characterized in that an exhaust passage is switchable between two exhaust passages, and further includes a means for introducing a gas containing harmful substances into the engine intake system or in front of a catalyst container when releasing harmful substances adsorbed on an adsorbent. Exhaust purification device.