JP2000204931A - Exhaust emission control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent melting down due to considerable increase of a catalyst temperature and prevent deterioration due to sintering when exhaust emission control is carried out at starting of engine. SOLUTION: In this exhaust emission control device for internal combustion engine in which a catalyst for controlling exhaust emission is disposed to an exhaust pipe 31 of engine (internal combustion engine), a main catalyst 50 is arranged in a midway of the exhaust pipe 31, and a subsidiary catalyst 51 whose light on temperature is lower than that of the main catalyst 50 is arranged at an upstream side of the main catalyst 50. The subsidiary catalyst 51 is formed with a through hole 51a into which exhaust emission flows, an adjusting valve 55 opening or closing an exhaust emission inflow opening 51b is provided at the exhaust emission inflow opening 51b which is in an upstream side of the through hole 51a, and open/close control means for opening or closing the adjusting valve 55 in response to an operating condition of the internal combustion engine is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to an exhaust gas purifying apparatus for an internal combustion engine in which a catalyst for purifying exhaust gas is disposed in an exhaust passage.

[0002]

2. Description of the Related Art Generally, in an internal combustion engine (hereinafter, referred to as an engine) using gasoline, light oil, or gas as a fuel, a catalyst is disposed in an exhaust passage to purify exhaust gas. Since this catalyst exhibits a purification function when it rises to the activation start temperature due to the exhaust gas temperature, it is general to set the activation start temperature of the catalyst in accordance with the temperature of the exhaust gas discharged during traveling. .

However, in the case of a conventional general catalyst, since the activation start temperature is high, and especially when the engine is started (cold start), the temperature of the catalyst carrier does not immediately rise to the activation temperature, so that the exhaust gas is almost completely purified. May not be. For this reason, in an engine that emits a large amount of HC, for example, the amount of noble metal constituting the catalyst is increased to set the activation start temperature low, or the catalyst is arranged near the engine having a high exhaust gas temperature to start the engine. Sometimes, exhaust gas purification is performed.

[0004]

However, when the catalyst is arranged near the engine as described above, after the catalyst is activated, the reaction heat of the catalyst is added to the exhaust gas temperature, so that the catalyst temperature rises significantly. In some cases, there is a concern that the catalyst may be melted.

[0005] Further, in the conventional method of increasing the amount of noble metal of the catalyst to lower the activation start temperature, there is a concern that sintering (bonding of metals due to thermal strain) is likely to occur at a high temperature, and the deterioration of the catalyst is accelerated. is there.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances, and it is possible to reliably purify exhaust gas at the time of starting an engine. An object of the present invention is to provide an exhaust gas purifying apparatus for an internal combustion engine that can avoid the problem of catalyst deterioration due to a ring.

[0007]

According to a first aspect of the present invention, there is provided an exhaust gas purifying apparatus for an internal combustion engine in which a catalyst for purifying exhaust gas is disposed in an exhaust passage. Gas flow adjusting means for disposing a sub-catalyst whose activation start temperature is lower than that of the catalyst, and for adjusting the flow rate of exhaust gas passing through the sub-catalyst so that the flow rate is higher when the temperature of the sub-catalyst is lower than when it is higher It is characterized by having provided.

According to a second aspect of the present invention, in the first aspect, the sub-catalyst is disposed on the upstream side and the main catalyst is disposed on the downstream side, and the gas flow rate adjusting means includes a through-hole through which exhaust gas passes through the sub-catalyst. Forming an adjustment valve for adjusting the exhaust gas flow area of the through hole, and opening and closing the adjustment valve so as to reduce the exhaust gas flow area when the temperature of the sub-catalyst is lower than when it is high. It is characterized by being constituted so that.

According to a third aspect of the present invention, in the second aspect, the gas flow rate adjusting means includes a shut-off valve that opens and closes between a closed position covering the upstream end face of the sub-catalyst and an open position exposing the same. The shut-off valve is driven to open and close so as to be at an open position when the regulating valve closes the through-hole and at a closed position when opening the through-hole.

According to a fourth aspect of the present invention, in the first aspect, the main catalyst and the sub-catalyst each have a shape that closes a part of an exhaust passage and are arranged in series along an exhaust gas flow direction. The gas flow rate adjusting means is constituted by an exhaust flow switching valve for the main catalyst and an exhaust flow switching valve for the sub-catalyst.

According to a fifth aspect of the present invention, in the first aspect, the main catalyst and the sub-catalyst have a shape in which the exhaust passage is closed by the two catalysts, and are arranged in parallel. It is characterized by comprising a switching valve for switching to the catalyst side or the auxiliary catalyst side.

The invention of claim 4 includes both cases where the sub-catalyst is disposed upstream or downstream of the main catalyst.

[0013]

According to the exhaust gas purifying apparatus of the present invention, a sub-catalyst having an activation start temperature lower than that of the main catalyst is provided, and a gas flow rate for adjusting the flow rate of exhaust gas passing through the sub-catalyst is provided. An adjusting means is provided, and the gas flow rate adjusting means increases the amount of exhaust gas passing when the temperature of the sub-catalyst is low than when the temperature of the sub-catalyst is high. The flow rate of exhaust gas passing through the sub-catalyst is increased by gas flow rate adjusting means,
As a result, the sub-catalyst is immediately activated, and the exhaust gas is purified. When the temperature of the sub-catalyst rises, the flow rate of the exhaust gas passing through the sub-catalyst is reduced by the gas flow rate adjusting means, so that the temperature rise of the sub-catalyst is suppressed and the melting of the sub-catalyst is prevented.

According to the second aspect of the present invention, the sub-catalyst is disposed upstream of the main catalyst in the exhaust passage, that is, near the exhaust port of the engine, and therefore at a portion where the exhaust gas temperature is high, and A regulating valve for adjusting the exhaust gas flow area of the through-hole formed in the sub-catalyst is provided, and the control valve is arranged such that the exhaust gas flow area becomes narrower when the temperature of the sub-catalyst is lower than when it is high. For example, when the engine is started, the regulating valve closes the through hole, and a large amount of exhaust gas passes through the sub-catalyst, whereby the sub-catalyst is immediately activated and purifies the exhaust gas. When the temperature of the sub-catalyst rises, the regulating valve opens a through-hole, most of the exhaust gas passes through the through-hole, and the temperature rise of the sub-catalyst is suppressed, so that the melting of the sub-catalyst is prevented.

According to the third aspect of the present invention, a shut-off valve is disposed on the upstream end face of the sub-catalyst, and when the regulating valve closes the through hole, the shut-off valve is opened to expose the end face of the sub-catalyst, When the through-hole is opened, the end face is covered with the shielding valve, so that the exhaust gas can surely flow through the sub-catalyst at a low temperature, and can reliably prevent the exhaust gas from flowing through the sub-catalyst at a high temperature. In addition, it is possible to reliably prevent the exhaust gas purification at a low temperature and the melting and deterioration of the sub-catalyst at a high temperature. As a result, the activation start temperature of the sub-catalyst can be set further lower, and the exhaust gas can be more reliably purified when the engine is started.

According to the fourth aspect of the present invention, the main and sub-catalysts are arranged in series and the main and sub-catalyst exhaust flow switching valves are provided.
Exhaust gas can be reliably purified, and the catalyst can be prevented from being melted.

According to the fifth aspect of the present invention, since the main and sub-catalysts are arranged in parallel and the exhaust flow switching valve is provided, the exhaust gas can be reliably purified and the catalyst can be prevented from being melted. .

[0018]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 to FIG.
FIG. 1 is a diagram for explaining an exhaust gas purifying apparatus for a GHP engine according to the first embodiment of the inventions of FIGS. 1 to 3; FIG. 1 is a configuration diagram of an engine-driven air conditioner equipped with the exhaust gas purifying apparatus; FIG. 4 is a sectional plan view, a plan view, and a sectional front view of the exhaust gas purifying apparatus, and FIGS. 5 and 6 are sectional plan views of the exhaust gas purifying apparatus.

In FIG. 1, reference numeral 1 denotes an engine-driven air conditioner, which comprises an indoor air conditioning unit 2 and an outdoor air conditioning unit 3. The indoor air conditioning unit 2
Is mainly provided with a refrigerant indoor heat exchanger 4 and an expansion valve 5 for reducing pressure. The outdoor air conditioning unit 3 mainly includes an engine 6, a compressor 7, an accumulator 8, a refrigerant outdoor heat exchanger 9, and a four-way valve 10.

The engine 6 is a four-stroke water-cooled gas-fueled engine. A starting motor 12 is connected to a crankshaft 6a of the engine 6 via a starting clutch 11, and the engine 6 is connected to an output shaft 6b. Is connected to the compressor 7 via an output clutch 13.

The outlet 7a of the compressor 7 is connected to a refrigerant pipe 14
a, which is connected to the refrigerant outdoor heat exchanger 9 via the four-way valve 10 and the refrigerant pipe 14b switched to the cooling operation position, and from the outdoor heat exchanger 9 via the refrigerant pipe 14c and the expansion valve 5, It is connected to the indoor heat exchanger 4. The indoor heat exchanger 4 includes a refrigerant pipe 14d, a four-way valve 10, a refrigerant pipe 14d.
e, connected to the suction port 7b of the compressor 7 via the heat exchange section 8a of the accumulator 8 and the refrigerant pipe 14f.

An intake pipe 16 is connected to an intake port 15 of the engine 6, and the throttle valve 1 is connected to the intake pipe 16.
An air cleaner 18 is provided on the upstream side of the intake pipe 7, and an upstream end opening 16a of the intake pipe 16 is open to the outside. The throttle valve 17 is driven to open and close by a governor device 20 using the power of the crankshaft 6a so that the throttle valve opening becomes the set engine speed. The engine speed is increased as the heat load of the heat pump increases. Set high to increase volume.

A venturi section 21 is provided between the throttle valve 17 and the air cleaner 18 of the intake pipe 16, and a fuel supply pipe 23 connected to a fuel gas source 22 is connected to the venturi section 21. ing. The fuel supply pipe 23 has two opening / closing valves 24 and 25, a zero governor (decompressor) 26, and an odorant removing device 2 for removing an odorant contained in the fuel gas in order from the upstream side.
7, and a flow control valve 28 are interposed.

An exhaust pipe 31 is connected to the exhaust port 30 of the engine 6, and an exhaust gas heat exchanger 32 is provided in the exhaust pipe 31 and a muffler 33 is provided downstream of the exhaust heat exchanger 32. The downstream end opening 31a of the exhaust pipe 31 is open to the outside.

The engine 6 is provided with a cooling water circulation circuit 35. The cooling water circulation circuit 35 includes a first circulation path for circulating the cooling water jacket 36, the thermostat 37, and the first cooling water pump 38 of the engine 6 during a warm-up operation in which the temperature of the cooling water is equal to or lower than a predetermined value. Also the second
A second circulation path circulating from the cooling water pump 42, the exhaust gas heat exchanger 32, the linear three-way valve 40 via the radiator 41 or via the heat exchange part 8 b in the accumulator 8 is provided.

When the cooling water temperature exceeds the predetermined value, a part of the cooling water from the second cooling water pump 42 is supplied to the first cooling water pump 38, the cooling water jacket 36 of the engine 6, and the thermostat 37. As described above, the cooling water passes through the exhaust gas heat exchanger 32, merges with the cooling water, passes through the radiator 41 from the three-way valve 40, or the heat exchange unit 8 in the accumulator 8.
A third circulation path circulating through b is formed.

In the air conditioner 1, the four-way valve 10 is switched to the outdoor heat exchanger 9 during the cooling operation.
The high-temperature, high-pressure refrigerant gas compressed by the compressor 7 is supplied to the outdoor heat exchanger 9 via the four-way valve 10, where it is cooled by outside air and liquefied. The liquefied high-pressure refrigerant liquid is decompressed by the expansion valve 5. The decompressed low-pressure refrigerant liquid evaporates by removing heat from the indoor air in the indoor heat exchanger 4, and the evaporated heat causes a cooling effect to cool the room. The evaporated refrigerant gas is supplied to the four-way valve 10.
And returns to the compressor 7 via the accumulator 8, and the same cycle is repeated.

During the heating operation, the four-way valve 10 is switched to the indoor heat exchanger 4 side, and the high-temperature, high-pressure refrigerant gas from the compressor 7 is supplied to the indoor heat exchanger 4, where it is cooled by the indoor air. It liquefies, and the indoor air is warmed by the condensation heat in this case, and a heating effect is obtained. The liquefied refrigerant liquid is decompressed by the expansion valve 5. The decompressed low-pressure refrigerant liquid evaporates by removing the heat of the outside air in the outdoor heat exchanger 9, returns to the compressor 7 via the accumulator 8, and the same cycle is repeated.

The engine 6 is provided with an exhaust gas purifying device which is a feature of the present embodiment. This exhaust gas purifying device mainly includes a main catalyst 50 disposed upstream of a muffler 33 of an exhaust pipe 31 and an exhaust gas heat exchanger 32.
Catalyst 5 disposed near the exhaust port 30 on the upstream side of the
And 1. When the exhaust gas heat exchanger 32 is configured not to allow water to flow during warm-up of the engine, the auxiliary catalyst 51 is disposed downstream of the exhaust gas heat exchanger 32. You may.

The main catalyst 50 has a cylindrical casing 52.
And is accommodated and arranged in an accommodating portion 31 a formed in a cylindrical shape with a larger diameter than the exhaust pipe 31. The sub-catalyst 51 is loaded in a rectangular cylindrical casing 53, and is accommodated in an accommodating portion 31b having a larger diameter than the exhauster 31 and formed in a rectangular cylindrical shape. The housing 31b may be directly connected to the exhaust port of the engine 6.

The main and sub-catalysts 50 and 51 are oxidation catalysts, and the oxidation catalyst is composed of γ-Al ₂ O ₃ containing at least one of Pt, Rh and Pd noble metals. The precious metal content of the sub-catalyst 51 is larger than the precious metal content of the main catalyst 50, whereby the sub-catalyst 5
The activation start temperature of No. 1 is set lower than that of the main catalyst 50. Specifically, the activation start temperature of the sub-catalyst 51 is 180 ° C.
Hereinafter, preferably set to 120 ~ 150 ℃,
The activation start temperature of the main catalyst 50 is set to 200 ° C. or higher, preferably 250 to 300 ° C. The main and sub-catalysts 50 and 51 are not limited to oxidation catalysts, but may be constituted by redox catalysts obtained by adding CeO ₂ to Pt, Rh, Pd / γ-Al ₂ O ₃ .

A rectangular through hole 51a through which exhaust gas flows is formed in the axis of the sub-catalyst 51. A rectangular plate-shaped adjusting valve 55 is provided at the exhaust gas inlet 51b on the upstream side of the through hole 51a. The adjusting valve 55 covers the exhaust gas inlet 51a when viewed in the gas flow direction. It is rotatable between a closed position and a fully open position exposing the inflow port 51b. Both ends of the valve shaft 55a fixed to the adjustment valve 55 penetrate the large-diameter portion 31b and protrude outward, and are air-tightly supported by the large-diameter portion 31b.

On both sides of the regulating valve 55, shut-off valves 56, 56 are provided, respectively. Each of the shut-off valves 56
Is a fully open position that exposes the upstream end face 51c of the sub-catalyst 51 when viewed from the front in the gas flow direction;
1c, and is rotatable between a fully closed position and an inclined position to guide the exhaust gas a to the through hole 51a. Both ends of the valve shaft 56a fixed to each of the shut-off valves 56 penetrate the large portion 31b and protrude outward, and are air-tightly supported by the large diameter portion 31b.

The adjusting valve 55 and each of the shut-off valves 56 are opened and closed by a driving mechanism. The drive mechanism has a drive pulley 57 and a fan-shaped drive gear 58 fixed to one end of a valve shaft 55a of the adjustment valve 55, and a drive motor 59 fixed to the other end.
Connect. Further, a driven pulley 61 is fixedly connected to a valve shaft 56a of the one shielding valve 56 and connected to the driving pulley 57 by a belt 60, and the valve shaft 56 of the other shielding valve 56 is fixed.
a, a fan-shaped driven gear 62 is fixed to the drive gear 5.
8 is of a structure that is meshed. When the drive motor 59 rotates the adjusting valve 55 to the fully closed position, each shielding valve 56 is integrally rotated to the fully open position, and when the adjusting valve 55 is rotated to the fully open position, each shielding valve 56 is fully closed. Pivots into position.

Exhaust gas temperature sensors 63a, 63b, and 63c are disposed near the upstream side and downstream side of the sub-catalyst 51 of the exhaust pipe 31 and near the upstream side of the main catalyst 50, respectively. the vicinity of the upstream side of 50 oxygen sensor 64 and the NO _X sensor 65 is arranged.

The regulating valve 55 is controlled by an ECU (not shown) as an open / close control means. This ECU outputs a close signal to the drive motor 59 when the temperature near the upstream side of the sub-catalyst 51 is equal to or lower than a predetermined value, such as during a cold start of the engine 6. Then, the adjustment valve 55 is rotated to the fully closed position to close the through hole 51a, and the respective shielding valves 56 are opened to expose the upstream end surface 51c of the sub-catalyst 51 into the exhaust passage. As a result, the exhaust gas discharged from the engine 6 is introduced into the auxiliary catalyst 51.

In this case, since the auxiliary catalyst 51 is located near the exhaust port of the engine, the temperature of the exhaust gas flowing in is relatively high, and the activation start temperature of the auxiliary catalyst 51 is set low, The sub-catalyst 51 is immediately activated to purify the exhaust gas. Further, the temperature of the exhaust gas passing through the sub-catalyst 51 increases due to the purifying action of the exhaust gas, and the temperature of the exhaust gas flowing into the main catalyst 50 increases.

When the temperature of the exhaust gas flowing into the sub-catalyst 51 exceeds a predetermined value, the ECU outputs an open signal to the drive motor 59. Then, the adjustment valve 55 is rotated to the fully open position to open the through hole 51 a, and each shielding valve 56 is closed to close the upstream end surface 51 c of the sub-catalyst 51. As a result, the exhaust gas passes through the through-hole 51a without passing through the sub-catalyst 51, and is introduced into the main catalyst 50, where the main catalyst 50 purifies the exhaust gas.

Here, each shielding plate 56 has a through hole 51a.
The exhaust gas smoothly through the through-hole 5
1a. The control of the adjustment valve 55 is not limited to the exhaust gas temperature. For example, the adjustment valve 55 may be closed for a predetermined time after the engine is started, and the adjustment valve 55 may be opened after a predetermined time has elapsed. good. The may be the amount of oxygen in the exhaust gas, or based on the amount of NO _X opens the on-off valve.

As described above, according to the present embodiment, the exhaust pipe 3
A sub-catalyst 51 having an activation start temperature lower than that of the main catalyst 50 is disposed upstream of the main catalyst 50, a through-hole 51a is formed in the axis of the sub-catalyst 51, and an exhaust gas flow through the through-hole 51a is formed. Since the inlet 51b is provided with the regulating valve 55 for opening and closing the inflow port 51b, when the engine is started, by closing the regulating valve 55, the through hole 51a is closed, so that the entire amount of the exhaust gas a passes through the sub-catalyst 51. From the secondary catalyst 51
The exhaust gas can be purified immediately at
Emission of C amount can be reduced.

When the temperature of the sub-catalyst 51 reaches a predetermined value or more, the regulating valve 55 is fully opened and the through-hole 51a
The exhaust gas a passes through the through-hole 51a and is introduced into the main catalyst 50 without passing through the sub-catalyst, so that the sub-catalyst 51 does not abnormally rise in temperature, and
1 can be prevented from being melted down or shortened in life. At this time, the main catalyst 50 is sufficiently activated, and the main catalyst 50 purifies the exhaust gas. In this way, the exhaust gas can be reliably purified over the entire range of the normal operation from the start of the engine.

In this embodiment, a shielding valve 56 for opening and closing the upstream end face 51c of the sub-catalyst 51 is provided on both sides of the regulating valve 55. When the regulating valve 55 opens the through hole 51a, the sub-catalyst is opened. Since the block 51 is closed, high-temperature exhaust gas can be reliably prevented from flowing in the sub-catalyst 51, and the sub-catalyst 51 can be reliably prevented from being overheated and melted or deteriorated by sintering. As a result, the life of the sub-catalyst 51 can be improved.

FIG. 7 is a characteristic diagram showing the results of an experiment performed to confirm the effect of the present embodiment. In the figure, curve A,
B shows the relationship between the HC purification rate of the exhaust gas on the main catalyst outlet side and the elapsed time from the start of the engine when the auxiliary catalyst is not provided and when the auxiliary catalyst is provided. As is clear from the figure, when the auxiliary catalyst is provided (see the curve B), the exhaust gas temperature after the start of the engine becomes the activation start temperature (T ₁ ) of the auxiliary catalyst.
Since the time (t ₁ ) hardly takes time until the temperature rises, the sub-catalyst is immediately activated, and the catalytic action of the sub-catalyst purifies HC components in the exhaust gas in a short time. Further, the temperature of the exhaust gas flowing into the main catalyst rises due to the oxidation reaction, and as a result, a shorter time (t ₂ -t
_{In 1} ), the main catalyst activation temperature rises. This increases the overall purification rate in a short time. On the other hand, when the secondary catalyst is not provided (see curve A), it takes a considerable time (t ₂ ) for the temperature of the exhaust gas flowing into the main catalyst to reach the main catalyst activation start temperature (T ₂ ). The time that the purification rate remains low is prolonged. When the sub-catalyst 51 is arranged as shown in FIG. 2, the shielding valve 56 is opened and closed until a time (t _b ) slightly elapses from _a time (t _a ) at which the HC purification rate becomes almost 100% after the engine is started. The regulating valve 55 is closed, and thereafter, the shielding valve 56 is closed and the regulating valve 55 is opened.

In the above embodiment, the shut-off valve 5 for opening and closing the upstream end 51c of the sub-catalyst 51 is provided on both sides of the regulating valve 55.
Although the case where 6 is provided has been described, in the present invention, the shut-off valve is not necessarily provided, and the flow of exhaust gas may be controlled by the adjusting valve alone. When the control valve is used alone, the activation start temperature of the sub-catalyst is raised slightly to 150 ° C.
It is desirable to set to about 200 ° C. Thereby, even when a part of the exhaust gas is at a high temperature, even if there is a temperature rise due to the flow in the sub-catalyst, the sub-catalyst can be prevented from being melted, and a necessary life can be secured.

In the above embodiment, a gas fuel engine has been described as an example. However, the present invention is not limited to this. The present invention can be applied to a gasoline engine or a diesel engine. it can.

FIG. 8 shows an exhaust gas purifying apparatus for a gasoline engine for an automobile or a motorcycle.
Is a fuel injection type four-cycle four-cylinder engine. An exhaust passage of the engine 80 has a structure in which a branch pipe 81a of an exhaust manifold 81 is connected to an exhaust port of each cylinder, and the branch pipe 81a is joined to one exhaust pipe 82. belongs to. A muffler 83 is provided downstream of the exhaust pipe 82.
A main catalyst 50 is disposed on the upstream side of the muffler 83 of the exhaust pipe 82, and a sub-catalyst 51 is disposed on the merging portion on the upstream side of the main catalyst 50. The same effects as those of the above embodiment can be obtained in the engine 80.

FIG. 9A shows an exhaust gas purifying apparatus according to a second embodiment of the present invention. In the second embodiment, the main catalyst 50 and the sub-catalyst 51 are respectively arranged in series so as to close a part of the exhaust passage, and the direction of the exhaust flow a is set forward of the main catalyst 50 on the upstream side. Exhaust flow switching valve 100 for the main catalyst that switches to the main catalyst 50 side or the side path 50a side
And a sub-catalyst exhaust flow switching valve 20 for switching the direction of the exhaust flow forward of the sub-catalyst 51 to the side of the sub-catalyst 51 or the side path 51a.
This is an example in which 0 is arranged.

In the second embodiment, the exhaust gas temperature sensor 1
When 10a is at a low temperature, the main catalyst exhaust flow switching valve 100
00b position, the sub-catalyst exhaust flow switching valve 200 is at the 200b position, and the exhaust gas temperature sensor 110a is at or above the first predetermined value, or the sub-catalyst downstream exhaust gas temperature sensor 110b is at or above the second predetermined temperature. When the temperature is equal to or higher than the predetermined temperature, the main catalyst exhaust flow switching valve 100 is set to the position 100c, and the auxiliary catalyst exhaust flow switching valve 200 is set to the position 200c. With the above configuration, the same operation and effect as those of the first embodiment shown in FIGS.
Has an effect.

Further, when the temperature of the main catalyst downstream exhaust gas temperature sensor 110c becomes equal to or higher than the third predetermined temperature higher than the second predetermined temperature, the throttle valve is throttled to limit the engine output. Fifty protections are provided.

FIG. 9B is a diagram showing a third embodiment of the present invention. In the third embodiment, the main medium 50 and the sub-catalyst 51 are arranged in parallel such that both of them block the exhaust passage. At the upstream end of the boundary between the two catalysts 50 and 51, an exhaust flow switching valve 30 for switching the direction of the exhaust flow a to either the main catalyst 50 side or the auxiliary catalyst 51 side.
0 is arranged.

In this embodiment, the exhaust gas temperature sensor 110a
When the temperature is low, the switching valve 300 is set to the 300b position, and when the exhaust gas temperature sensor 110a becomes equal to or higher than the first predetermined value or the auxiliary catalyst downstream exhaust gas temperature sensor 110b becomes equal to or higher than the second predetermined temperature, the switching valve 300 is turned on. The position is 300c.
In this case, similarly, the above configuration has the same operation and effect as the first embodiment shown in FIGS.

Further, an exhaust gas temperature sensor 1 downstream of the main catalyst
When 10c becomes equal to or higher than the third predetermined temperature higher than the second predetermined temperature, the throttle valve is throttled to limit the engine output, thereby protecting the main catalyst 50.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an engine-driven air conditioner provided with an exhaust gas purifying device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional plan view of the exhaust gas purification device.

FIG. 3 is a plan view showing a drive mechanism of a sub-catalyst of the exhaust gas purifying device.

FIG. 4 is a cross-sectional front view showing a driving mechanism of the auxiliary catalyst (FIG. 3)
FIG. 4 is a sectional view taken along line IV-IV of FIG.

FIG. 5 is a cross-sectional plan view showing a closed state of the on-off valve of the auxiliary catalyst.

FIG. 6 is a cross-sectional plan view showing an open state of the on-off valve of the auxiliary catalyst.

FIG. 7 is a characteristic diagram showing an effect of the exhaust gas purification device.

FIG. 8 is a schematic view of an engine for an automobile and a motorcycle using the exhaust gas purifying apparatus.

FIG. 9 is a view showing an exhaust gas purifying apparatus according to second and third embodiments according to the fourth and fifth aspects of the present invention.

[Explanation of symbols]

 Reference Signs List 6 engine (internal combustion engine) 31 exhaust pipe 50 main catalyst 51 sub-catalyst 51a through hole 51b exhaust gas inlet 51c upstream end face 55 regulating valve 56 shielding valve 100, 200 exhaust flow switching valve for auxiliary and main catalyst 300 switching valve

 ────────────────────────────────────────────────── ─── Continued on the front page F-term (reference)

Claims (5)

[Claims] In an exhaust gas purifying apparatus for an internal combustion engine, wherein a catalyst for purifying exhaust gas is disposed in an exhaust passage, a main catalyst and a sub-catalyst whose activation start temperature is lower than that of the main catalyst are provided in the exhaust passage. A gas flow rate adjusting means for adjusting the flow rate of the exhaust gas passing through the sub-catalyst when the temperature of the sub-catalyst is lower than when the temperature of the sub-catalyst is higher. Exhaust gas purification device. 2. The method according to claim 1, wherein the sub-catalyst is disposed upstream and the main catalyst is disposed downstream, and the gas flow rate adjusting means forms a through hole through which exhaust gas passes through the sub-catalyst. An adjustment valve for adjusting the exhaust gas flow area of the through hole is provided, and the control valve is configured to open and close so that the exhaust gas flow area becomes narrower when the temperature of the auxiliary catalyst is lower than when the temperature is high. An exhaust gas purifying device for an internal combustion engine, comprising: 3. The gas flow adjusting device according to claim 2, wherein the gas flow rate adjusting means includes a shut-off valve that opens and closes between a closed position that covers an upstream end surface of the sub-catalyst and an open position that exposes the auxiliary catalyst. An exhaust gas purifying device for an internal combustion engine, wherein the valve is driven to open and close so as to be at an open position when the valve closes the through hole and at a closed position when the valve opens the through hole. 4. The gas flow control device according to claim 1, wherein the main catalyst and the sub-catalyst each have a shape that closes a part of an exhaust passage, and are arranged in series along an exhaust gas flow direction. An exhaust gas purifying apparatus for an internal combustion engine, comprising an exhaust flow switching valve for a main catalyst and an exhaust flow switching valve for a sub-catalyst. 5. The method according to claim 1, wherein the main catalyst and the sub-catalyst have a shape in which an exhaust passage is closed by both catalysts.
An exhaust gas purifying apparatus for an internal combustion engine, wherein the exhaust gas purifying device is arranged in parallel, and the gas flow rate adjusting means is constituted by a switching valve for switching an exhaust flow to a main catalyst side or a sub-catalyst side.