JPH0680812U - Engine exhaust purification device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an exhaust emission control device for an engine, which activates the catalyst at the time of cold start of the engine and suppresses excessive temperature rise of the catalyst after warming up. [Structure] An engine exhaust gas purification device is provided for an engine body 1
The inner pipe 4 which is connected to the exhaust pipe 2 and which contains the catalyst 3
A double pipe 6 composed of an outer pipe 5 surrounding the inner pipe 4, a branch pipe 10 connecting the outer pipe 5 and an exhaust pipe 7 downstream of the inner pipe via a check valve 9, and an inner pipe 4 and a switching valve 8 that connects the exhaust pipe 7 downstream of the inner pipe. By switching the switching valve 8, the exhaust gas that has passed through the inner pipe 4 either flows into the outer pipe 5 or is exhausted as it is. It is configured so that it can be selected whether to go to the tube 7.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an engine exhaust gas purification device.

[0002]

[Prior art]

 Conventionally, various technologies have been developed for exhaust emission control devices in engine exhaust systems. FIG. 3 is a configuration diagram showing an exhaust pipe device in a cylinder number control engine disclosed in JP-A-58-59308. Generally, in a cylinder number control engine, harmful components such as HC are contained in the low temperature fresh air discharged from the cylinders that are idle when the engine is lightly loaded. The components may be released into the atmosphere without being purified.

The above invention has been made to avoid this, and as shown in FIG. 3, the exhaust passage is deactivated corresponding to the deactivated side cylinders # 1 to # 3 and the activated side cylinders # 4 to # 6. The exhaust side exhaust passage 21 and the working side exhaust passage 22 are divided, and an exhaust purification catalyst 23 is arranged corresponding to both the exhaust passages, and the catalyst 23 and the catalyst inflow portion 25 of the exhaust passages 21 and 22 are arranged. An enclosing confluent passage 24 is formed to guide the exhaust gas after passing through the catalyst to the confluent passage 24 to heat the fresh air from the # 1 to # 3 cylinders and the catalyst 23 to enhance the activity of the catalyst 23. is there.

FIG. 4 is a configuration diagram of an exhaust gas purification device for an internal combustion engine disclosed in Japanese Patent Laid-Open No. 2-291414. In this exhaust gas purification device, in a V-type internal combustion engine, a catalytic converter 35 is provided downstream of a confluence portion between the first exhaust pipe 33 of the rear engine 31 and the second exhaust pipe 34 of the front engine 32. The upstream side is formed into a double tubular shape and the downstream side is joined to the merging portion, and a merging pipe 36 is provided in the merging portion. It is made up of.

As a result, the exhaust gas of the rear engine 31 is heated by the reaction heat when passing through the start cat 38 in the confluence pipe 36 and its temperature rises. Therefore, the catalyst 35 is heated to promote its activation. At the same time, the exhaust of the front engine 32 heats the start cat 38 from the outside in the confluence pipe 36 to promote its activation. That is, in the present invention, the heat retained by the engine exhaust is effectively utilized for activating the catalyst 35 or the start cat 38.

[0006]

[Problems to be solved by the device]

 By the way, in the above-mentioned conventional exhaust emission control device, in the former structure, when all the cylinders # 1 to # 6 are operating, the catalyst heats up excessively, so that the catalyst is destroyed due to melting damage or the like. There is a risk of promoting heat deterioration of the catalyst. Also in the latter case, after warming up, the start cat may cause destruction due to melting loss or the like due to excessive temperature rise, or may accelerate thermal deterioration of the catalyst.

The present invention has been made in order to solve the above-mentioned drawbacks of the conventional device, and aims to activate the catalyst for purifying exhaust gas and prevent an excessive temperature rise of the catalyst after engine warm-up. It is intended to provide an exhaust emission control device that prevents the destruction of the catalyst due to melting damage and the like.

[0008]

[Means for Solving the Problems]

 To achieve the above object, the present invention connects an engine exhaust gas purification device to an engine exhaust pipe and passes an internal passage containing a catalyst, an external passage surrounding the internal passage, and a catalyst in the internal passage. A branching means provided with a switching means for switching the outflow of exhaust gas to the exhaust pipe downstream of the catalyst and to the above-mentioned external passage, the external passage and the exhaust pipe downstream of the catalyst, and a check valve. It is configured with a tube and.

[0009]

[Action]

 When the engine is in a cold state, the switching means is switched so that the exhaust gas passing through the catalyst in the internal passage passes through the external passage and goes to the exhaust pipe downstream of the catalyst via the branch pipe. As a result, when the exhaust gas passes through the external passage, the heat of the exhaust gas heats the catalyst, so that the catalyst is activated, and the exhaust gas is purified even in the cold state immediately after the engine is started.

After the engine warms up and the catalyst is sufficiently activated, the switching means is switched to connect the internal passage to the exhaust pipe downstream of the catalyst, and the exhaust gas passing through the catalyst is directly supplied to the exhaust pipe downstream of the catalyst. Drain. As a result, the heating of the catalyst by the exhaust gas is stopped, the catalyst is not overheated, and troubles such as catalyst melting loss do not occur. It should be noted that the check valve prevents the influence of pulsating exhaust gas that has flowed out to the exhaust pipe downstream of the catalyst on the external passage due to the resistance of the muffler.

[0011]

【Example】

 FIG. 1 is a block diagram of an exhaust gas purification apparatus which is an embodiment of the present invention. As shown in the figure, the exhaust gas purification device is connected to an exhaust pipe 2 connected to the engine body 1, and has a double pipe 6 composed of an inner pipe 4 containing a catalyst 3 and an outer pipe 5 surrounding the inner pipe 4, A branch pipe 10 that connects the outer pipe 5 and the exhaust pipe 7 downstream of the inner pipe via a check valve 9 and a switching valve 8 that connects the inner pipe 4 and the exhaust pipe 7 downstream of the inner pipe are provided. By switching the switching valve 8, it is possible to select whether the exhaust gas after passing through the inner pipe 4 flows out into the outer pipe 5 or goes directly to the exhaust pipe 7. The switching valve 8 must be made of a material having heat resistance. The exhaust emission control device according to the present invention is constructed in this way.

Next, the operation will be described. Generally, when the engine is in a cold state at the time of starting, the temperature of the catalyst 3 is low and the exhaust gas purification capability is low. At this time, when the switching valve 8 is switched so that the exhaust gas after passing through the inner pipe 4 is directed to the outer pipe 5, the exhaust gas of the engine 1 flows from the exhaust pipe 2 to the outer pipe 5 via the inner pipe 4 in the direction of arrow A. After that, it is discharged to the atmosphere from the exhaust pipe 7 downstream of the inner pipe 4 via the branch pipe 10. During this time, the exhaust gas is cleaned of harmful components by the catalyst in the inner pipe 4, the temperature of the exhaust gas is raised by the reaction heat, and the heat retained when passing through the outer pipe 5 heats the catalyst 3. As a result, the catalyst 3 is activated even in the cold state immediately after the engine is started, and the exhaust gas is purified.

Next, after the engine is started and after the time has elapsed and the engine has been warmed up, the catalyst 3 is sufficiently activated, so the switching valve 8 is switched to direct the exhaust from the inner pipe 4 in the direction of arrow B, It is directly discharged to the exhaust pipe 7 downstream of the inner pipe. For this reason, the catalyst 3 is not heated by exhaust gas, and as a result, troubles such as excessive heating of the catalyst 3 and melting damage are eliminated. It should be noted that the check valve 9 suppresses the adverse effect of the pulsating exhaust gas flowing into the exhaust pipe 7 on the outer pipe due to the resistance of the muffler or the like.

FIG. 2 is a block diagram of an exhaust gas purification apparatus showing another embodiment of the present invention, in which two cut valves 11 and 12 are provided at the outlet of the inner pipe 4 instead of the switching valve 8. . When the engine is in a cold state immediately after starting, the cut valve 11 is opened and the cut valve 12 is closed, and exhaust gas is guided from the inner pipe 4 to the outer pipe 5 to heat the catalyst 3. After the engine is warmed up, the cut valve 11 is closed and the cut valve 12 is opened, so that the exhaust gas is directly discharged from the inner pipe 4 to the exhaust pipe 7.

[0015]

[Effect of device]

 According to the present invention, an exhaust gas purifying apparatus for an engine is connected to an exhaust pipe of the engine, an internal passage for containing a catalyst, an external passage surrounding the internal passage, and a catalyst for exhaust gas passing through the catalyst in the internal passage are provided. A switching pipe for switching between the outflow to the exhaust pipe downstream and the outflow to the external passage; and a branch pipe connecting the external passage and the exhaust pipe downstream of the catalyst and having a check valve. Since it was configured as described above, it was possible to obtain the following excellent effects.

(1) Since the catalyst is heated by the exhaust gas and activated when the engine is started, the exhaust gas is purified even when the engine is in a cold state, and the emission amount of harmful components is reduced. (2) In addition, after a certain time has passed since the engine was started and the catalyst has been sufficiently activated, heating of the catalyst by exhaust gas is stopped, so the catalyst does not rise excessively and the catalyst melts accordingly. There is no risk of destruction due to loss or the like, or promotion of thermal deterioration of the catalyst. (3) The equipment is lightweight and the equipment cost is low.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an engine exhaust gas purification apparatus showing an embodiment of the present invention.

FIG. 2 is a schematic diagram of an engine exhaust gas purification apparatus showing another embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional exhaust emission control device.

FIG. 4 is a configuration diagram of a conventional exhaust emission control device.

[Explanation of symbols]

 1 engine body 2 exhaust pipe 3 catalyst 4 inner pipe 5 outer pipe 6 double pipe 7 exhaust pipe 8 switching valve 9 check valve 10 branch pipe 11 cut valve 12 cut valve

Claims (3)

[Scope of utility model registration request] 1. An internal passage that is connected to an exhaust pipe of an engine and contains a catalyst, an external passage that surrounds the internal passage, and an exhaust gas that passes through the catalyst in the internal passage and flows into an exhaust pipe downstream of the catalyst. An engine characterized by comprising switching means for switching between outflow to the external passage and a branch pipe connecting the external passage and an exhaust pipe downstream of the catalyst and having a check valve. Exhaust purification device. 2. The exhaust gas purifying apparatus for an engine according to claim 1, wherein the switching means is a two-way switching valve. 3. The engine according to claim 1, wherein the switching means is a cut valve that connects the internal passage and an exhaust pipe downstream of the internal passage, and a cut valve that connects the internal passage and the external passage. Exhaust purification device.