JPH01257710A - Exhaust gas purifying device for alcohol fuel engine - Google Patents

Abstract

PURPOSE:To aim at purification of exhaust gas by providing an exhaust gas passage for a low temperature which is branched from the upper stream side of a catalyst device to introduce the exhaust gas to the catalyst device via an adsorption chamber. CONSTITUTION:An adsorption chamber 9 is provided at the outer circumference of a catalyst device 8. An exhaust passage 13 for a low temperature, is provided, which is branched from the upper stream side of the catalyst device 8 to introduce exhaust gas to the catalyst device via an adsorption chamber 9. An exhaust gas passage 6 and the exhaust gas passage 13 for a low temperature are switched over by a change valve 14. Accordingly, aldehyde and uncombusted methanol are removed even during a cold engine state so that the exhaust gas can be purified.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for purifying exhaust gas discharged from an alcohol fuel engine that uses alcohol or alcohol-based fuel.

(Prior art) In recent years, alcohol or alcohol-based alcohols have been used to improve environmental pollution caused by exhaust gas emitted from gasoline engines, to conserve petroleum resources, and to improve ignitability and prevent knocking compared to gasoline engines. Alcohol-fueled engines have been developed that use fuels such as methanol.

Measures are taken to purify the exhaust gas in this type of alcohol fuel engine as well, and generally a catalyst is installed in the middle of the exhaust pipe and the catalyst purifies the exhaust gas discharged from the alcohol fuel engine. However, until the catalyst is warmed by the exhaust gas and reaches a predetermined temperature or higher, the catalyst does not purify the exhaust gas satisfactorily. It has been difficult to effectively purify the exhaust gas discharged during the cold period, that is, until the catalyst is warmed to a predetermined temperature or higher.

For example, Japanese Patent Application Laid-Open No. 61-200315 discloses a preheating device in front of a catalyst held in a catalyst casing or between catalysts divided into front and rear parts in order to purify exhaust gas discharged from an alcohol fuel engine. By providing a preheating device, the catalyst can be preheated before starting the engine, or by heating the catalyst at the same time as the engine is started, the catalyst can be quickly warmed to a predetermined temperature or higher, and the engine can be cooled during the cold period. The engine is also configured to be able to effectively purify the exhaust scum discharged from the engine.

(Problems to be Solved by the Invention) By the way, in the above-mentioned conventional technology, by preheating the catalyst itself using a preheating device until it quickly reaches a predetermined temperature or higher, the exhaust gas is effectively purified by the catalyst. However, when heating the catalyst at the same time as the engine starts, the heating device heats the catalyst until it reaches a predetermined temperature from the time exhaust scum is discharged with the engine starting. There was a time delay during this time, and the exhaust gas emitted during this time could not be reliably purified. Therefore, during the cold period of the engine, it has been difficult to remove certain components that are particularly problematic, such as unburned methanol when aldehyde or methanol contained in the exhaust gas is used as fuel. Furthermore, when preheating the catalyst prior to starting the engine, the preheating device must be operated before starting the engine, which is extremely uneconomical.

Therefore, in an alcohol fuel engine that uses alcohol or alcohol-based fuel, the present invention satisfactorily purifies the exhaust gas emitted especially during the engine cold opening period, and eliminates the problems such as aldehydes contained in the exhaust gas. An object of the present invention is to provide an exhaust gas purification device for an alcohol fuel engine that can reliably remove components.

(Means for Solving the Problems) In order to achieve the above object, the present invention is characterized by the following configuration.

That is, in an exhaust gas purification device for an alcohol fuel engine that uses alcohol or alcohol-based fuel,
A catalyst device is provided in the middle of an exhaust passage connected to the engine body to purify exhaust gas, and an adsorbent is provided around the outside of the catalyst device and is filled with an adsorbent to adsorb and remove predetermined components in the exhaust gas. an adsorption chamber, a low-temperature exhaust passage that branches from the upstream side of the catalyst device in the exhaust passage and introduces exhaust gas into the catalyst device through the adsorption chamber, and a low-temperature exhaust passage downstream of the branched part of the low-temperature exhaust passage. The present invention is characterized in that a switching valve is provided in the exhaust passage on the upstream side of the catalyst device to close the air passage and introduce exhaust scum only into the low-temperature exhaust passage when the exhaust scum is at a low temperature.

(Function) According to the above configuration, when the exhaust gas discharged from the engine is at a low temperature during the cold opening period, such as immediately after the engine starts,
By switching the switching valve, exhaust gas is introduced into the low-temperature exhaust passage that branches from the upstream side of the catalyst device in the exhaust passage and introduces exhaust gas into the catalyst device through an adsorption chamber filled with adsorbent. As a result,
The adsorbent filled in the adsorption chamber reliably adsorbs and removes certain components that are particularly problematic, such as unburned methanol when aldehyde or methanol contained in exhaust gas is used as fuel. Moreover,
The exhaust gas introduced into the adsorption chamber via the low-temperature exhaust passage warms the catalyst device from its surroundings and quickly heats it above a predetermined temperature at which it can satisfactorily exert a purifying effect on the exhaust gas. When the exhaust gas introduced into the catalyst device from the low-temperature exhaust passage via the adsorption chamber reaches a predetermined temperature, the switching valve is switched and the exhaust gas is introduced directly into the catalyst device from the exhaust passage. It will be purified. This makes it possible to reliably purify exhaust gas without causing an increase in exhaust pressure when the engine is under high load or at high speed.

(Example) Embodiments of the present invention will be described below based on the drawings.

As shown in FIG. 1, the engine 1 according to this embodiment is an alcohol fuel engine that uses alcohol or alcohol-based fuel, and is connected to a plurality of exhaust ports (not shown) in the engine 1. Exhaust manifold 2
An exhaust pipe 3 is connected to the engine 1 through the manifold 2 for discharging exhaust gas from the engine 1 to the outside. Further, an exhaust gas purification device 4 for purifying the exhaust gas is provided in the middle of the exhaust pipe 3, and a muffler is also provided on the downstream side of the exhaust gas purification device 4 in the exhaust pipe 3. 5 is connected.

In this embodiment, the exhaust gas purification device 4
is structured as follows.

That is, as shown in FIG. 2.3, the exhaust gas purification device 4 has one end connected to the exhaust pipe 3 to form an exhaust passage 6 that is continuous with the exhaust pipe 3, and also has an exhaust passage 6 in the exhaust passage 6. A catalyst device main body 8 in which a catalyst 7 for purifying introduced exhaust gas is interposed, an adsorption chamber 9 disposed around the outer periphery of the catalyst device main body 8, and a catalyst device main body 8 in the adsorption chamber 9. When a specific component contained in the exhaust gas, such as aldehyde or methanol, is used as a fuel, adsorption is used to adsorb and remove particularly problematic components such as unburned methanol. 10, a partition plate 11 which branches from the upstream side of the catalyst 7 in the exhaust passage 6 and connects to the adsorption chamber 9, a partition plate 11 provided with a plurality of communication holes 11a and 11a, and a partition plate 11 disposed around the outer periphery of the catalyst device main body 8. A low-temperature exhaust passage 13.13 that introduces exhaust gas into the catalyst 7 through a plurality of openings 8a, 8a through the communication chamber 12, and a downstream side of the branch parts 13a, 13a of the low-temperature exhaust passage 13.13. The low-temperature exhaust passage 13 is provided in the exhaust passage 6 on the upstream side of the catalyst 7 and is used when the exhaust gas is at a low temperature.
A switching valve 14 that can be switched to introduce exhaust gas only into the catalyst 13, a temperature sensor 15 that detects the temperature of the exhaust gas passing through the catalyst 7, and an output signal a from the temperature sensor 15 is input, and When it is determined based on the output signal a that the temperature of the exhaust gas passing through the catalyst 7 is equal to or higher than a predetermined temperature, the switching valve 14 is switched by outputting an output signal A. It has a controller 16 for controlling. Therefore,
The exhaust gas guided into the exhaust passage 6 from the exhaust pipe 3 is
After passing through the catalyst 7 and being purified, the exhaust gas is discharged to the outside, and if the temperature of the exhaust gas is below a predetermined temperature, the switching valve 14 is switched based on the output signal outputted from the controller 16. The exhaust gas is arranged to be introduced into the cold exhaust passage 13.13.

In this embodiment, as shown in the figure, the low-temperature exhaust passages 13.13 and the openings 8a, 8a are provided at two locations each, but the number may be increased as necessary. . Further, as the adsorbent 1o filled in the adsorption chamber 9, for example, metal fibers or the like can be considered.

According to the above configuration, when the exhaust gas discharged from the engine 1 is at a low temperature in a cold period such as immediately after engine startup, the switching valve 14 is switched to the state shown by the solid line in FIG. The exhaust gas is introduced only into the low temperature exhaust passage 13.13 which branches from the upstream side of the catalyst 7 and introduces the exhaust gas into the catalyst 7 through the adsorption chamber 9 filled with adsorbent 10 and the communication chamber 12. As a result, the adsorbent 10 filled in the adsorption chamber 9 removes certain components that are particularly problematic, such as unburned methanol when aldehyde or methanol contained in the exhaust gas is used as fuel. It will definitely be removed by adsorption. However, the low temperature exhaust passage 13.13
The catalyst 7 is warmed from its surroundings by the exhaust gas introduced into the adsorption chamber 9 and the communication chamber 12 through the catalyst 7, and is quickly heated to a predetermined temperature or higher at which the exhaust gas purifying effect is effectively exerted. . 7, above -10 = adsorption chamber 9 and communication chamber 1 from low temperature exhaust passage 13.13
When it is detected by the temperature sensor 15 that the temperature of the exhaust gas introduced into the catalyst 7 via the controller 16 has reached a predetermined temperature or higher,
The switch is made in response to the output signal outputted from the converter, and a state not shown by the chain line in FIG. 1. As the temperature of the catalyst 7 increases, the adsorbent 10 degass the aldehyde or unburned methanol supplemented by O, and is reliably purified by the catalyst 7. This makes it possible to reliably purify exhaust gas without causing an increase in exhaust pressure when the engine 1 is under high load or at high speed.

(Effects of the Invention) As described in Part 2 below, according to the exhaust gas purification device for an alcohol-fueled engine according to the present invention, the exhaust gas contained in the exhaust gas emitted during the cold period of the engine such as when starting the engine or during low load is reduced. It is possible to reliably remove specific components that are particularly problematic, such as aldehydes or unburned methanol, and to purify exhaust gas reliably without causing an increase in exhaust pressure even when the engine is under high load. Become.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a schematic side view of an alcohol fuel engine equipped with an exhaust gas purification device according to the embodiment, and FIG. An enlarged vertical cross-sectional view showing the purification device, FIG. 3 is the l in FIG.
It is a sectional view of the main part of the exhaust gas purification device as seen from the -111 cutting line. 1. Alcohol fuel engine, 3. Exhaust pipe, 4.
・・Exhaust gas purification device, 6 exhaust passage, 7 catalyst, 8・・
Catalyst device (catalyst device main body), 9 adsorption chamber, 10 adsorbent,
13 Low temperature exhaust passage, 14 switching valve.

Claims (1)

[Claims] (1) An exhaust gas purification device for an alcohol fuel engine that uses alcohol or alcohol-based fuel,
A catalyst device is provided in the middle of an exhaust passage connected to the engine body to purify exhaust gas, and an adsorbent is provided around the outside of the catalyst device and is filled with an adsorbent to adsorb and remove predetermined components in the exhaust gas. an adsorption chamber, a low-temperature exhaust passage that branches from the upstream side of the catalyst device in the exhaust passage and introduces exhaust gas into the catalyst device through the adsorption chamber, and a low-temperature exhaust passage that is downstream of the branched part of the low-temperature exhaust passage and that An alcohol fuel engine characterized in that the switching valve is provided in the exhaust passage on the upstream side of the catalyst device and closes the exhaust passage when the exhaust gas is at a low temperature and introduces the exhaust gas only into the low-temperature exhaust passage. Exhaust gas purification device.