JPH0988567A - Exhaust gas purification device - Google Patents

Abstract

(57) Abstract: The present invention relates to an exhaust gas purifying apparatus, and promotes purification of exhaust gas from a combustion furnace such as an engine, a boiler, or a blast furnace. SOLUTION: The heating catalyst parts 20a, 20b of an electric heating catalyst, which is provided on the upstream side of a main catalyst H arranged in an exhaust system and is divided into a plurality of parts, are configured to be able to selectively raise the temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for purifying exhaust gas by combustion from a combustion furnace such as an engine, a boiler or a blast furnace.

[0002]

2. Description of the Related Art As is well known, in order to purify exhaust gas from the above-mentioned engine, combustion furnace, etc., various catalytic converters are used as one method. For example, in order to reduce harmful substances emitted immediately after the start of the conventional engine, catalyst heating by various electric heating catalyst devices that rapidly heat the catalyst immediately after the start or introduction of secondary air into the exhaust port. There are proposals of various exhaust gas purifying devices, such as one that accelerates the reaction by using the reaction heat and accelerates the temperature rise of the catalyst by this reaction heat.

As a conventional example when the above exhaust gas purifying apparatus is applied to an automobile, for example, there is Japanese Utility Model Laid-Open No. 5-919. As shown in FIG. 26, the technique described in the publication discloses that an exhaust gas purifying device 05 sandwiched between two oxygen concentration sensors 01a and 01b is provided with a heater 06, and the heater 06 is controlled by the two oxygen concentration sensors 01a and 01b. The exhaust gas purifying device 05 is configured to generate heat only when the output difference is smaller than a predetermined value. The heater is controlled according to the activity of the exhaust gas purifying device 05, and the catalyst is cooled immediately or by activation. It is intended to purify the exhaust gas at the start of the state.

As another conventional example, Japanese Patent Laid-Open No. 4-6
There is a publication 0109. According to the technique described in the publication, as shown in FIG. 27, a plurality of electrodes are provided on a honeycomb structure and a honeycomb heater is arranged on the downstream side of a main monolith catalyst arranged on the upstream side of an exhaust gas passage, The exhaust gas is heated at a low temperature, and the melter corrosion and catalyst deterioration are suppressed.

A honeycomb heater is constructed by providing a plurality of slits as a resistance adjusting mechanism in a honeycomb structure having a large number of through holes and installing two electrodes on its outer wall.
Then, for example, the main monolith catalyst 015 and the ignition catalyst 01
A honeycomb heater or a heater catalyst 014 is inserted between them and 6. According to this, since the honeycomb heater is installed on the downstream side of the main monolith catalyst 015, it is possible to heat the exhaust gas at a low temperature such as when the engine is started, and the upstream side of the exhaust gas even after the exhaust gas becomes high in temperature. Since the main monolith catalyst 015 is disposed in the main heater, the corrosion of the metal of the honeycomb heater and the deterioration of the catalyst carried on the honeycomb heater catalyst 014 can be suppressed.

[0006]

However, any of the techniques described in Japanese Utility Model Laid-Open No. 5-919 and Japanese Patent Application Laid-Open No. 4-60109 described as the above-mentioned conventional example is simply a heater or a heater upstream of the main catalyst. In order to purify the harmful exhaust gas discharged immediately after the start by providing the catalyst, the main catalyst arranged downstream of the heater or the heater catalyst should be promptly activated immediately after the start in order to purify the harmful exhaust gas. It was done.

However, immediately after starting, the exhaust gas has a low temperature and requires a large amount of electric power to warm it to a high temperature. For example, even if the conversion efficiency of electric energy into heat is 100%, the exhaust gas amount and the temperature difference cause several KW. Because a certain amount of power is required,
It is necessary to increase the size of the battery and the capacity of the alternator, which causes a loss such as an increase in cost and an increase in weight.

On the other hand, in order to comply with the above-mentioned strict regulations on exhaust gas in North America, the most harmful gas is generated, especially immediately after the engine is started, so it is necessary to further promote the warm-up of the catalyst. Even if the above heater or heater catalyst or its system is used, it is necessary to reduce the amount of electric power used as much as possible from the viewpoint of energy saving and to efficiently warm up the catalyst.

The present invention was devised in view of the above problems, and it is possible to selectively raise the temperature of a heating catalyst portion of an electric heating catalyst which is provided along an exhaust gas flow and is divided into a plurality of parts. An object is to provide an exhaust gas purification device.

[0010]

Therefore, in the exhaust gas purifying apparatus of the present invention according to claim 1, a main catalyst provided in the exhaust system and an exhaust gas flow which is provided upstream of the main catalyst and flows into the exhaust system. It is characterized in that it is constituted by an electric heating catalyst which can selectively raise the temperature of the heating catalyst portion of the electric heating catalyst which is provided along the above and is divided into a plurality of parts.

In the exhaust gas purifying apparatus according to the present invention as defined in claim 2, in the structure according to claim 1, the divided heating catalyst portions of the electric heating catalyst can be operated by arbitrarily ranking or operating them. It is characterized by being configured so that it can be switched and operated. An exhaust gas purifying apparatus according to a third aspect of the present invention is the exhaust gas purifying apparatus according to the first or second aspect, including a control device that selectively operates a heating catalyst portion divided into a plurality of the electric heating catalysts. It is characterized by that.

According to a fourth aspect of the present invention, there is provided the exhaust gas purifying apparatus according to any one of the first to third aspects, wherein the control device for the electrically heated catalyst is the engine cooling water temperature, accelerator pedal opening. The temperature difference of thermocouples disposed upstream and downstream of the electrocatalyst or the wake thermocouple temperature, and operation signal detecting means such as a timer are used for operation.

According to a fifth aspect of the present invention, in the exhaust gas purifying apparatus of the first aspect, the exhaust gas purifying device according to any one of the first to fourth aspects is provided in the vicinity of the upstream or the downstream of the electric heating catalyst and the exhaust gas flow direction. And a thin catalyst portion formed to be thinner than the main catalyst. An exhaust gas purifying apparatus according to a sixth aspect of the present invention is, in the configuration according to any one of the first to fifth aspects, provided in an exhaust system having at least the main catalyst and having the electrically heated catalyst. A catalyst case connected to an exhaust pipe, and an inlet expansion of the catalyst case formed so that a flow cross-sectional area of the exhaust gas gradually increases from a connection portion of the exhaust pipe of the catalyst case to an inlet of the main body of the catalyst case. And a thin catalyst portion which is arranged in the vicinity of the upstream side of the main catalyst at a distance in the flow direction of the exhaust gas and is formed thinner than the main catalyst in the flow direction. Is characterized by.

According to a seventh aspect of the present invention, there is provided the exhaust gas purifying apparatus according to the sixth aspect, wherein the inlet expansion portion has a length of about 5 to 25 mm in the exhaust gas flow direction. I am trying. An exhaust gas purifying apparatus according to an eighth aspect of the present invention is characterized in that, in the configuration according to the fifth or sixth aspect, the thin catalyst portion is formed to have a thickness of about 5 to 45 mm in an exhaust gas flowing direction. There is.

An exhaust gas purifying apparatus according to a ninth aspect of the present invention has the structure according to any one of the fifth, sixth and eighth aspects.
It is characterized in that the main catalyst and the thin catalyst portion are formed such that the distance in the flow direction is in the range of about 15 mm. An exhaust gas purifying apparatus according to a tenth aspect of the present invention is the exhaust gas purifying apparatus according to any one of the fifth to ninth aspects, wherein the length R from the central axis of the main catalyst in the flow direction to the outer periphery of the main catalyst. And a length r from the center of the axis to the outer periphery of the heated laminar flow of the exhaust gas heated in the thin catalyst section toward the main catalyst, a distance ratio r / R is formed to be about 40 to 60%. It is characterized by being done.

According to the eleventh aspect of the present invention, in the exhaust gas purifying apparatus according to the sixth aspect, the length of the inlet expansion portion of the catalyst case in the exhaust gas flow direction is about 5 to 25 mm. The thickness of the thin catalyst portion in the flow direction is about 5
The main catalyst and the thin catalyst portion are arranged so that the distance between them in the flow direction is about 15 mm, and the distance ratio r / R from the central axis is about 40 to 40 mm.
It is characterized by being formed in 60%.

According to a twelfth aspect of the present invention, in the exhaust gas purifying apparatus of the present invention, in the structure according to any one of the fifth, sixth and eleventh aspects, a catalyst case connected to the exhaust pipe and the catalyst case is housed in the catalyst case. And a thin catalyst portion housed in the catalyst case near the upstream side of the main catalyst. An exhaust gas purifying apparatus according to a thirteenth aspect of the present invention is the exhaust gas purifying apparatus according to any one of the fifth, sixth and eleventh aspects, wherein the exhaust pipe connected to the catalyst case is located in the exhaust pipe near an inlet of the catalyst case. It is characterized in that the thin catalyst portion is provided in.

An exhaust gas purifying apparatus according to a fourteenth aspect of the present invention is the exhaust gas purifying apparatus according to any one of the fifth, sixth, eleventh, twelfth and thirteenth aspects, wherein the electrically heated catalyst and the thin catalyst portion are provided. It is characterized in that the integrally formed electrically heated thin catalyst is arranged in the exhaust pipe near the inlet of the catalyst case. The exhaust gas purifying apparatus of the present invention according to claim 15 provides the exhaust gas purifying apparatus according to claim 5,
In the configuration according to any one of 6, 11, and 12, the electrically heated thin catalyst in which the electrically heated catalyst and the thin catalyst portion are integrally formed is provided in an upstream side of the main catalyst in the catalyst case. It is characterized by being arranged in the vicinity.

An exhaust gas purifying apparatus according to a sixteenth aspect of the present invention is the exhaust gas purifying apparatus according to any one of the fifth to eleventh aspects, wherein the main catalyst is provided in an exhaust system of an engine and an upstream side of the main catalyst. And a thin catalyst portion capable of raising a temperature of a part of exhaust gas flowing into the exhaust system, wherein the central axis of the main catalyst is inclined with respect to the central axis of the thin catalyst portion. It is characterized by being formed.

An exhaust gas purifying apparatus according to a seventeenth aspect of the present invention is the exhaust gas purifying apparatus according to any one of the first to sixth, twelfth, thirteenth and fourteenth aspects, wherein the heating catalyst portion into which the electric heating catalyst is divided is divided. It is characterized in that the electrically heated catalyst is concentrically divided. An exhaust gas purifying apparatus of the present invention according to claim 18 is the exhaust gas purifying device according to any one of claims 1 to 6, 12, 13, and 14, wherein the heating catalyst portion into which the electric heating catalyst is divided is the exhaust system. Is arranged in parallel in the flow direction of the exhaust gas.

An exhaust gas purifying apparatus according to a nineteenth aspect of the present invention is the exhaust gas purifying apparatus according to any one of the first to sixth aspects, wherein the electrically heated catalyst has a center along the central axis of the exhaust gas flow of the main catalyst. A first heating catalyst portion for generating a stratified flow of the heated exhaust gas flowing through a portion, and a stratified flow of heated exhaust gas flowing in the outer peripheral portion of the heated stratified flow in the central portion of the main catalyst. And a second heating catalyst section for generating

According to the twentieth aspect of the present invention, in the exhaust gas purifying apparatus of the present invention, in the configuration of the nineteenth aspect, the first heating catalyst portion is concentrically provided with a space near the outer peripheral portion of the main catalyst. It is characterized in that it is constituted by a second heating catalyst portion for generating a laminar flow of the heated exhaust gas flowing therethrough.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) A first embodiment of the present invention will be described with reference to FIGS. 1 is an explanatory view showing an engine to which an exhaust gas purifying apparatus of the present invention is applied, FIG. 2 is a longitudinal sectional view showing a case where a single catalyst is applied to the first catalyst apparatus of FIG. 1, and FIG. FIG. 4 is a vertical cross-sectional view showing a case where a split catalyst is applied to one catalyst device, FIG. 4 is a vertical cross-sectional view showing a case where an inlet catalyst is applied to the first catalyst device of FIG. 1, and FIG. FIG. 6 is a schematic diagram showing dimensions of each part of the catalyst, FIG. 6 is a performance diagram showing the shape of the inlet expansion portion and flow velocity distribution of FIG. 5, FIG. 7 is a performance chart showing the shape of the inlet expansion portion and pressure loss of FIG. 5, and FIG. 5 is a performance chart showing the thickness and flow velocity distribution of the thin catalyst portion in FIG. 5, FIG. 9 is a performance chart showing the interval between the thin catalyst portion and the main catalyst in FIG. 5, and the catalyst temperature history,
FIGS. 10, 11 and 12 are explanatory views showing the states of the flow and temperature distribution in each of the split catalyst, the inlet catalyst and the single catalyst, and FIG. 13 is the start of the split catalyst of FIG. FIG. 14 is a performance diagram showing the subsequent catalyst temperature history, FIG. 14 is a pressure comparison diagram showing the pressure loss due to the shape of the catalyst case applied to the first catalyst of FIG. 5, and FIG. 15 is the exhaust gas flow rate and flow velocity distribution of FIG. It is a performance diagram.

FIG. 16 is an explanatory view showing the outline of the layout when an electrically heated catalyst is arranged in the exhaust pipe in the vicinity of the upstream side of the small thin catalyst F2 used for the first catalyst of FIG. 1, and FIG.
FIG. 17 is a schematic view showing the electrically heated catalyst of FIG. 16, (A) is a longitudinal sectional view schematically enlarging the electrically heated catalyst of FIG. 16,
17B is a side view schematically showing the arrow Y of FIG. 17A, and FIG. 18 is a laminar flow in which the first heated catalyst portion of the electrically heated catalyst of FIG. FIG. 19 is an explanatory view showing a state in which a laminar flow in which the second heating catalyst portion of the electric heating catalyst in FIG. 17 is heated and is heated is flowing downstream, and FIG. 20 is in FIG. It is explanatory drawing which shows the application example which changed the arrangement | positioning position of the division | segmentation heating catalyst part of an electric heating catalyst, (A) is the longitudinal cross-sectional view which showed typically, (B) is X of FIG. 20 (A). 21 is a side view schematically showing the view,
22 is a graph showing the elapsed time after engine start and the detection threshold of each operation signal, FIG. 22 is an explanatory view showing another application example of the divided heating catalyst portion of the electric heating catalyst of FIG. 17, and FIG. 23 is FIG.
7 is an explanatory view showing another application example of the divided heating catalyst portion of the electric heating catalyst of FIG. 7, and FIG. 24 is a flowchart showing an operation routine of electric heating of FIG.

In the first embodiment, as shown in FIG.
Exhaust gas from the combustion chamber 3 of the engine 1 is connected via an exhaust pipe 5 to a first catalyst 9 arranged near an oil pan 7.
The second catalyst 11 and the like arranged downstream of the first catalyst 9 purify the first catalyst 9, but the present embodiment is a study of the first catalyst 9. The thermocouples N1, N straddling the upstream and downstream sides of the small thin catalyst F2 used for the first catalyst 9 described above.
Two.

Cooling chamber 1 of cylinder block of engine 1
Water temperature sensor CW for detecting the water temperature of a, throttle valve 1b
Axle opening sensor CS that detects the opening of an accelerator petal that is linked to the above, a thermocouple sensor that detects the temperature difference between the thermocouples N1 and N2 provided upstream and downstream of the small thin catalyst F2 or the wake thermocouple temperature. CD, a heating catalyst portion of the electric heating catalyst 20 divided into a plurality of pieces by the operation detection signal means CM such as a timer CT for detecting the passage of time, and in the present embodiment, 20a and 20b divided into two pieces. A control device C for controlling the operation is provided.

Reference numeral 13 is an intake pipe, 15 is a secondary air pump, 1
Reference numeral 7 denotes a supply port connected to the exhaust port 21 from the secondary air pump 15 via the check valve 19. First, the first
In the embodiment, the electric heating catalyst 20 which is an element of the present invention can exert its function and effect even when applied to a conventional single-type catalyst described later, but considering only the supply of heat from the exhaust gas, Disregarding the heat generated by the catalyst and the electrically heated catalyst 20, the main catalyst provided in the exhaust system, the thin catalyst portion arranged in the vicinity of the upstream side of the main catalyst, the catalyst case containing the catalyst, the exhaust gas It was sought to accelerate the temperature rise of the main catalyst and accelerate the reaction of the main catalyst only by the heat energy of the exhaust gas by devising the layout of the tubes, etc. Is intended to promote the rapid activation of the main catalyst by the combination of
First, the layout of the thin catalyst, the main catalyst, the exhaust pipe, the catalyst case and the like will be described, and then the relationship with the electrically heated catalyst 20 will be described.

First, an ordinary honeycomb type catalyst layout will be examined, but it will be explained by comparing three types of a split type catalyst, an inlet type catalyst and a single type catalyst of the present invention described later. As shown in FIG. 2, the single-type catalyst 40 has a rectifying effect so that the total amount of exhaust gas flows into all the honeycomb-type lattices substantially uniformly and heats a large vertical section of the catalyst with respect to the exhaust gas flow direction. Therefore, the temperature rise of the catalyst is slow.

That is, as shown in FIG. 2, the single type catalyst 40 has a length of, for example, about 75 mm which is sufficiently thick in the exhaust gas flow direction and is accommodated in the catalyst case 2 connected to the exhaust system. When the catalyst 4 included is examined, by placing the catalyst 4 (resistor) in the flow of the exhaust gas as shown by the arrow w in FIG. 2, the flow is decelerated in the resistor, and the speed is increased in the upstream side immediately before the resistor. The static pressure of the portion h near the central axis 14 of the catalyst 4 becomes fast.

Since the flow of the exhaust gas is generated according to the pressure gradient, a part of the fluid in the high speed portion h joins the low speed portion s to make the flow rate distribution uniform, that is, the arrow y shown in FIG. As described above, the flow velocity distribution is made substantially uniform. Therefore, in the present embodiment, the thin catalyst portion F is provided in the vicinity of the upstream side of the main catalyst 4, which is the normal single-type catalyst 40, and is formed from the thin catalyst F1 or the small thin catalyst F2. ing.

Further, the above heating catalyst section 20 intensively heats a small flow area of the thin catalyst F1 or the small thin catalyst F2 to rapidly raise the temperature of the heated portion or to the reaction start temperature of the catalyst. It is a technical idea to raise. Based on the above technical concept, as shown in FIG. 3 as a method for collecting exhaust gas locally and accelerating the temperature rise, the split catalyst 50 is a thin catalyst disposed near the upstream side of the main catalyst H. F1 is arranged in the vicinity of the upstream side of the main catalyst H and in the catalyst case 2 in which the main catalyst H is housed.

Further, as shown in FIG. 4, the inlet type catalyst 60
The small thin catalyst F2 is arranged in the exhaust pipe 5 near the inlet 8 connected to the inlet 8 of the catalyst case 2 in which the main catalyst H is stored. That is, in the split catalyst 50, the thin catalyst F1 is made thinner than the main catalyst to eliminate the rectifying effect of the exhaust gas and to leave the flow of the exhaust gas unbalanced.

Further, the small thin catalyst F2 in the inlet type catalyst 60 is intended to forcibly flow the total amount of exhaust gas to the thin catalyst in the flow cross sectional area of the small exhaust pipe 5 in the exhaust pipe 5. Is. Exhaust gas flow and heat transfer for three types of split catalyst 50, inlet catalyst 60, and single catalyst 40 (conventional normally used catalyst shown in FIG. 2) provided in the exhaust system as described below. Was tested.

As an initial condition, the exhaust gas flow is a steady flow of 10 m / s with reference to the engine speed after starting, intake efficiency, and temperature, and the pressure loss is 6000 rpm of engine speed.
m, 100m / s assuming a fully open throttle valve
Is a steady flow of. FIG. 5 schematically shows the split catalyst 50 of the exhaust gas purifying apparatus used in the above test.

In FIG. 5, d is the diameter of the exhaust pipe 5, and D is the diameter of the portion of the catalyst case 2 supporting the catalyst. L is a length from the connecting portion 8 to the inlet 2b of the main body 2a of the catalyst case 2 in the exhaust pipe 5, and is formed so that the flow cross-sectional area of the exhaust gas from the connecting portion 8 to the inlet 2b is gradually increased. It is the length of the inlet expansion portion 12 in the flow direction.

Further, S is the distance between the main catalyst H and the thin catalyst F1 provided close to the upstream side of the main catalyst H housed in the catalyst case 2, and T is the flow direction of the thin catalyst F1. Is the thickness of. Further, R is the length from the central axis 14 in the flow direction of the main catalyst H in the portion supporting the catalyst of the catalyst case 2 to the outer periphery of the main catalyst H, and r is the exhaust gas flow on the inner peripheral wall of the opening of the exhaust pipe 5. From the extension line extending in the direction
The length is up to 4, and r / R represents the distance ratio from the central axis of the both.

Further, the above-mentioned r is a stratified flow 16 of the exhaust gas formed by heating in the thin catalyst portion F (a columnar layer is formed in the exhaust gas flow and flows from upstream to downstream. It is also the length from the central axis 14 to the outer periphery of the laminar flow of a part of the exhaust gas, which is referred to as a laminar flow in the present invention. Selection of catalyst inlet shape In FIG. 5, the test results obtained by setting d = 56 mm, D = 100 mm and L = 5 mm, 10 mm, 20 mm, 25 mm in the above are shown in FIG.
It was found that there was a relationship between the inlet expansion portion 12 and the flow velocity distribution, and as shown in FIG. 7, there was a relationship between the inlet expansion portion shape and the pressure loss corresponding to 6000 rpm (throttle valve fully opened).

The flow velocity distribution of FIG. 6 is the distribution at the inlet of the thin catalyst F1. As shown in FIG. 6, in order to impart a bias to the flow of the exhaust gas, L = 5 mm rather than L = 10 mm,
That is, it is understood that it is better to widen the entrance abruptly. On the other hand, as shown in FIG. 7, when L = 10 mm or less, the pressure loss rapidly increases. Therefore, considering the flow velocity distribution shown in FIG.
Preferably L = about 10 mm is considered suitable.

Relationship between Thickness of Thin Catalyst Section and Flow Rate Distribution The relationship between the thickness T of the thin catalyst F1 and the flow rate distribution at the catalyst inlet is as shown in FIG. The sum of the thickness of the thin catalyst portion F and the thickness of the main catalyst H is 75 in the above three types of catalyst shapes.
mm, and the interval S between both catalysts was fixed at 15 mm.

If the distance S between the thin catalyst F1 and the main catalyst H is extremely shorter than about 15 mm, which is the distance S between the thin catalyst F1 and the main catalyst H as shown in FIG. Since the turbulent flow is less likely to occur in the exhaust gas after passing through the thin catalyst F1 due to the shortening, the temperature distribution is not uniform and the high temperature exhaust gas is not evenly distributed in front of the main catalyst H.
It becomes difficult to sufficiently activate the main catalyst H.

On the contrary, the distance S between the thin catalyst F1 and the main catalyst H
Is extremely longer than about 15 mm as described above, the total amount of exhaust gas flows into all the grids substantially uniformly due to the rectifying effect of the main catalyst H as described above, but due to the long gap S, it goes out of the catalyst case 2. Of the main catalyst H not only slows down the temperature of the main catalyst H by heating the large flow cross-sectional area but also escapes from the exhaust pipe 5 and the catalyst case 2 to the outside. It is not very preferable to make the interval S extremely long, because the preferable temperature distribution will not be obtained due to an increase in the amount of heat.

It is preferable that the maximum value of the interval S is determined in consideration of the heat quantity and the flow velocity distribution, and is set within the range. The maximum value of the interval S can be increased to some extent by providing an additional device in the exhaust pipe 5, the catalyst case 2 or the like to suppress the escape of the heat amount.
Also, since the honeycomb structure used for the catalyst has a strong rectifying effect, the thin catalyst must be made sufficiently thin and the flow velocity distribution should be uneven as shown in the figure.

As can be seen from FIG. 8, the thickness of the thin catalyst F1 should be about 45 mm in order to accelerate the exhaust gas flow rate by about 10% from the average flow rate, and similarly, the thin catalyst F1 should be thin by about 38%. It is understood that the thickness of the shaped catalyst F may be about 5 mm.
As shown in FIG. 7, considering the pressure loss, the thickness T of the thin catalyst F1 is preferably about 10 mm.

Below, a thickness of 5 mm, which is considered to be the upper limit of strength, is selected to examine the effect of raising the temperature. Temperature rising characteristics of catalyst The arrows in FIGS. 10 to 12 represent the exhaust gas flow, and the distribution of the symbols represents the temperature distribution 20 seconds after the engine starts.
In the case of the split type catalyst 50, as shown in FIG.
The flow is concentrated in the central portion of No. 1 and the local portion Ha in the central portion shown in black is heated.

It can be seen that the exhaust gas entering the rear main catalyst H has a uniform flow due to the above rectification effect.
Exhaust gas that is rapidly heated in the local portion Ha of the central portion of the thin catalyst F1 and flows out from the thin catalyst F1 is the thin catalyst F1.
In the gap S between the No. 1 and the main catalyst H, a turbulent flow is generated and the mixture is stirred,
The temperature distribution and the flow velocity distribution are made substantially uniform, and the main catalyst H flows from upstream to downstream.

Further, as explained with reference to FIG. 2 above, the main catalyst H has a high static pressure in the central portion where the speed is still high immediately upstream of the main catalyst H. Therefore, FIG.
As shown in the catalyst 4 corresponding to the main catalyst H shown in (4), since the flow responds to the pressure gradient, a part of the fluid in the high speed portion h joins the low speed portion s and Figure 1 shows how the above-mentioned fluid distribution is made uniform.
It is understood as shown in 0.

Further, in the case of the inlet type catalyst 60, the small thin catalyst F2 has a small flow cross-sectional area of the exhaust pipe 5 as shown in FIG. 11, so that this portion Hb is installed in the exhaust pipe 5 and has a unit area. Since the flow rate per hit is large, the temperature becomes the highest among the above three types, and the small-sized thin catalyst F2 of the inlet catalyst 60
As shown in FIG. 11, a wide cross section corresponding to the flow cross sectional area of the exhaust pipe 5 is heated, and the deviation is smaller than that of the split catalyst 50.

Further, a turbulent flow is formed in the gap S with the main catalyst H flowing out from the small thin catalyst F2, the temperature of the high-temperature exhaust gas is made substantially uniform, and the flow of the main catalyst H is uniform due to the rectifying effect as described above. It becomes the highest temperature among the three types because it is activated and the activation is promoted. Further, in the case of the single type catalyst 40, the flow is made uniform as shown in FIG. 2 by the rectifying effect of the catalyst 4 as shown in FIG. Part of the exhaust gas h flowing toward the slow exhaust gas s at the outer periphery, and the flow velocity distribution is made uniform,
Moreover, the temperature distribution is smaller than the deviation of the temperature distribution, and the temperature rise becomes slow.

FIG. 13 shows the change in the maximum temperature of the main catalyst H for 20 seconds after the start. As shown in FIG. 13, the inlet catalyst 60 has the fastest temperature rising rate, and exhaust gas is exhausted after 20 seconds. The temperature of the split-type catalyst 50 rises faster than that of the single-type catalyst 40, and the time required to reach around 150 ° C. is shortened by about 5 seconds. If a catalyst having a low activation temperature such as a palladium-based catalyst is used, the reaction will occur even at around 150 ° C. Therefore, it is considered that the temperature further rises in these 5 seconds.

Pressure Loss In order to compare the pressure loss of four types (types) by adding a shape with a smoothed inlet shape to the three types of catalyst shapes compared above, test under load conditions equivalent to 6000 rpm (throttle valve fully open) The results obtained are shown in FIG. Since the inlet catalyst 60 is installed in the exhaust pipe, the inflow speed of the exhaust gas is high and the frictional force is large. As a result, the pressure loss increases and the output decreases by about 3%.

The split type catalyst 50 having the same inlet shape
As a result of comparing the inlet-changed single-type catalyst 45 with each other, it was found that the pressure loss was almost the same and there was almost no influence due to division, that is, the presence or absence of the thin catalyst F1. The difference in pressure loss due to the inlet shape increases as the inlet is suddenly widened as discussed in FIG. 7, but the way this test is spread has little effect on the output.

From the above, according to the exhaust gas purifying apparatus of the present invention, the length L of the inlet expansion portion 12 of the catalyst case 2 in the exhaust gas flow direction is about 5 to 25 mm and the thickness of the thin catalyst F1 in the flow direction is. It is arranged such that T is about 5 to 45 mm, and the distance S between the main catalyst H and the thin catalyst F1 in the flow direction is in the range of about 15 mm.
When the above distance ratio r / R is about 60% or less, about 40 to 6
If set to 0%, the average flow rate of the exhaust gas is 10 to 10.
Acceleration of 65% is possible.

Even if the distance ratio r / R is about 40% or less, the same thin catalyst F1 as shown in FIGS.
Is not accelerated with respect to the thickness of the same inlet, and is not accelerated with respect to the length L of the same inlet expansion portion 12 as shown in FIG. If the distance ratio r / R is set according to desired specifications, desired effects can be obtained.

Relationship between Flow Rate and Velocity Distribution FIG. 15 shows the test results when the flow rate of exhaust gas is 25 liters (L) / second (S) and 250 (L / S). It was found that the flow velocity distribution did not change significantly even when the exhaust gas flow rate was changed. This is because the increase in frictional resistance (decrease in flow velocity difference) generated in the catalyst and the increase in kinetic energy due to increase in flow velocity (increase in flow velocity difference) are offset.

As is apparent from the above, as a result of studying the technical constitution based on the technical idea of the present invention that the temperature is raised quickly in a small region, the following has been found. By arranging the thin catalyst F1 before the normal catalyst (main catalyst H), it is possible to locally accelerate the temperature rise while maintaining the same level of pressure loss. By disposing the small thin catalyst F2 in the exhaust pipe 5 connected to the inlet of the catalyst case that houses the main catalyst H, although the pressure loss increases, the temperature rise can be greatly promoted.

Since both of the above have excellent temperature rising properties,
If the required amount of heat is suitable, the thin catalyst F1 or the small thin catalyst F2 and the main catalyst H can be used according to their specifications such as the split catalyst 50, the inlet catalyst 60, the inlet changing single catalyst 45, etc. If necessary, the heater or an electrically heated catalyst 20 described later may be used in the vicinity of the front and rear of the thin catalyst portion F on the upstream side of the main catalyst H when the amount of heat is insufficient. The catalyst used in the main catalyst H and the thin catalyst portion F can obtain a desired amount of heat by using, for example, a palladium-based catalyst that reacts at a low activation temperature near 150 ° C. In this case, the heater and the electrically heated catalyst 20 may have a low capacity, so that not only the cost can be reduced but also a desired rapid temperature rise can be performed.

Next, a case where an electrically heated catalyst is used in the exhaust pipe in the vicinity of the upstream side of the small thin catalyst F2 arranged in the inlet type catalyst 60 as shown in FIG. 16 will be described. The electrically heated catalyst 20 shown in FIG. 16 is arranged upstream of the main catalyst H as shown in FIG. 17 and is concentrically divided into the flow of the exhaust gas flow, or as shown in FIG. And a heating catalyst portion 20a divided into a plurality of electric heating catalyst portions 20 arranged in parallel in the flow direction and divided.
In the case of the present embodiment, the first heating catalyst portion 20a of the electric heating catalyst 20 and the first heating catalyst which are provided only in the central portion of the electric heating catalyst 20 including the central axis 14 are included. The outer periphery of the portion 20a and the first heating catalyst portion 20a
And the first heating catalyst portion 20a so as to be polymerized into a donut shape.
Is divided into two second heating catalyst portions 20b formed concentrically with.

As shown in FIG. 17, the electrode D1 of the first heating catalyst section 20a and the electrode D of the second heating catalyst section 20b described above.
2, D3 are connected to a power source via a control device C operated by the operation signal detecting means CM. Although not shown, the control device C includes a first heating control unit and a second heating catalyst unit 20b that control an operation output signal to the first heating catalyst unit 20a.
A second heating control unit for controlling an operation output signal to the second heating control unit.

Since the first embodiment is configured as described above, after the engine 1 is started, the operation signal detecting means CM has the water temperature sensor CW and the accelerator pedal opening sensor C.
S, the temperature difference between the electrodes N1 and N2 of the thermocouple or the temperature sensor CD of the wake thermocouple temperature, the fact that the threshold value of any one of the timer CT is exceeded is detected and input to the control device C. The above-mentioned electrode D is controlled by the actuated signal which is controlled and output.
1, electric power is supplied from a power source (not shown), and only the limited exhaust gas passing through the first heating catalyst section 20a is intensively heated, so that the temperature can be rapidly raised to a high temperature gas.

The exhaust gas generated at this high temperature is the main catalyst H
A turbulent flow is generated on the inlet side of the exhaust gas, but a part of the flow is downstream in the state of a laminar flow Q1 as shown in FIG. The main catalyst H flows in a laminar flow Q1 from the upstream side to the downstream side in the central portion, and can be effectively heated and activated from the central portion of the main catalyst H.

When the time set according to the specifications has elapsed after the first heating catalyst section 20a was operated, the first heating catalyst section 20a was deactivated by the control device C, and the second heating catalyst section 20b was activated. Then, as shown in FIG. 19, the outer peripheral portion of the thin catalyst F2 flows as a ring-shaped laminar flow Q2 of the exhaust gas in the same manner as the first heating catalyst portion 20a, and the outer periphery of the main catalyst portion 20b. Since the portion flows as a laminar flow Q2 of the exhaust gas whose temperature is raised in a ring shape, the ring-shaped outer peripheral portion of the main catalyst H is heated and activated, and the whole main catalyst H is heated and activated rapidly. It can be hastened.

When the main catalyst H reaches the set temperature set according to the above specifications, the second heating catalyst section 20b causes the controller C to
It is deactivated by the stop output signal that is input to and controlled by
The operation of the exhaust gas purifying device at the time of starting is completed. The sensors CW, CS, C of the operation signal detecting means CM
As shown in FIGS. 21A to 21E, D and CT are RAMs (not shown) of the controller C in which the elapsed time after starting and thresholds are set in advance according to the specifications of various catalyst devices.
It has been entered in.

In the first embodiment, since activation is carried out from the central portions of the thin catalyst F2 and the main catalyst H, heat is less likely to escape to the outside of the catalyst case 2, so that the above temperature rise is effectively achieved. be able to. On the contrary to the above, if the second heating catalyst portion 20b is operated and then the first heating catalyst portion 20a is operated, the second heating catalyst portion 20b is activated first and a part of the heat is generated in the catalyst case 2. Even if it escapes to the outside, the heated second heating catalyst portion 20b serves as a heat insulating layer between the outer peripheral wall of the catalyst case 2 and the first heating catalyst portion 20a to be operated next is sufficiently heated and heated. can do.

Further, as described above, the electrically heated catalyst 20 is arranged concentrically with respect to the flow direction of the exhaust gas, for example, as shown in FIGS.
As shown in FIG. 9, the doughnut-shaped portion is divided into the first heating catalyst portion 20a and the second heating catalyst portion 20b substantially concentrically with respect to the central axis 14 of the exhaust gas flow, but it is not limited to this. For example, as shown in FIG. 20, even if the second heating catalyst portion 20b and the first heating catalyst portion 20a are arranged side by side in series along the central axis in the flow direction of the exhaust gas flow,
The same operation and effect as the embodiment can be obtained.

In this case, the first heating catalyst section 20a is provided on the downstream side.
Since the first heating catalyst section 20a is operated by the output signal of the control device C as described above, the temperature is raised,
Next, the second heating catalyst section 20b is heated in the same manner.
The heated exhaust gas flow in the central portion in the vicinity of the central axis of the heating catalyst portion 20b is blocked by the first heating catalyst portion 20a, so that as shown in FIGS. The laminar flows Q1 and Q2 are generated and reach the main catalyst as described above, and the main catalyst H can be rapidly heated in the same manner as above.

Further, as shown in FIG.
One of the second heating catalyst parts 20a and 20b is formed in a thin ring shape so as to cover the outer peripheral part of the heating catalyst part of the electric heating catalyst 20, and the other is formed in the central part of the central axis part of the electric heating catalyst 20. , The first and second heating catalyst parts 20a,
If 20b is heated at the same time, the heated catalyst portion arranged on the outer peripheral side serves as an adiabatic layer and can prevent the heat radiation to the outside of the catalyst case 2. The heating catalyst section can effectively raise the temperature and be activated.

FIG. 24 is a flowchart of the operation routine of the first and second heating catalyst portions 20a and 20b of the electrically heated catalyst 20. An engine is started by an ignition key (not shown), and a timer CT is set in step 70. In step 72, the operation signal detecting means CM determines, for example, the conditions of 1 to 5, namely, the water temperature sensor CW, the accelerator petal opening sensor CS, the temperature difference between the electrodes N1 and N2 of the thermocouple or the temperature sensor CD of the wake thermocouple temperature, When it is detected that one of the thresholds of the timer CT is exceeded, the first
The heating control unit 20a is turned on to operate the first heating catalyst unit 20a.

In step 76, the count value CNT = 0 is set and the measurement of the elapsed time after the first heating control section is turned on is started, and the process proceeds to step 78, where CNT> 10 cycles (for example, if 1 cycle is 1 second, 10 seconds) has elapsed, and if CNT> 10 cycles, proceed to step 84,
If CNT <10 cycles, the process proceeds to step 80. In step 80, it is determined whether or not any one of the above conditions 1 to 5 in step 72 is satisfied. If not satisfied, the process proceeds to step 82, the count value CNT is incremented, and after one cycle, the step If it is satisfied, the process proceeds to step 84, and the first heating control unit is turned off and the second heating control unit 20b is turned on to operate the first heating catalyst unit 20a. Switch to 20b operation.

At step 86, the temperature T of the electrically heated catalyst 20 is compared with a set value T ₀ set according to the specifications of the catalyst to determine whether T> T ₀ or not, and T> T ₀ must be satisfied. For example, the process returns to the input side of step 86, and if T> T ₀ , proceeds to step 88, that is, waits until T> T ₀ , proceeds to step 88, and turns off the second heating control unit 20b. The operation of the heating catalyst unit 20b is stopped, and the operation routine of the heating catalyst unit is finished.

In this embodiment, as described above, the exhaust gas limited to a small amount passing through the first heating catalyst section 20a of the electric heating catalyst section 20 is heated to locally raise the temperature of the exhaust gas, and this temperature rise The small thin catalyst F2 is intensively heated by the generated exhaust gas, so that the temperature is rapidly raised, and the small thin catalyst F2 is heated.
The laminar flow Q1 having a high temperature in the axial center portion of the small thin catalyst F2 even after flowing out from the turbulent flow is generated at the interval S, but a part of the laminar flow Q1 is not agitated and the main flow is as shown in FIG. The high temperature laminar flow Q1 flows as a laminar flow Q1 from upstream to downstream of the catalyst H.
Becomes a spark and the activation is rapidly started, and as a result, the main catalyst H becomes the laminar flow Q2 of the ring-shaped heated exhaust gas that is heated by the second heating catalyst section 20b of the electric heating catalyst 20 as described above. Since the ring-shaped outer peripheral portion of the main catalyst H is heated, the temperature of the main catalyst H can be rapidly raised due to activation heat generation of the entire main catalyst H.

In this case, since the heat is released from the axial center portion of the main catalyst H, the heat does not escape from the catalyst case 2 to the outside so much that the main catalyst H is effectively and rapidly raised. Can be warmed, for example about 300-400 ° C
Sudden temperature rise easily without consuming large power,
The cost can be low. In the case of FIG. 23, only a small amount of exhaust gas flowing in, for example, the upper half (or the lower half or one of the left and right half) of the flow cross-sectional area of the exhaust pipe 5 upstream of the small thin catalyst F2 is electrically heated. Since the first heating catalyst 20a of the catalyst 20 heats the exhaust gas, the temperature of the exhaust gas rises rapidly and becomes the above-mentioned laminar flow Q3.
Flow into the main catalyst H, the main catalyst H is rapidly activated from the upper half (or the lower half, or either one of the left and right half) of the central axis, and the temperature of the main catalyst H rises rapidly due to the heat generated by the main catalyst H itself. it can.

Next, as in the case of FIGS. 18 and 19, the lower half of the second heating catalyst section 20b operates in the same manner as described above, and the lower half of the main catalyst H is moved by the laminar flow Q4 of the heated exhaust gas. When heated and activated, the main catalyst H as a whole can be rapidly activated. In this case, the heat escapes from the catalyst case 2, but since the small amount of exhaust gas passing through the small thin catalyst F2 can be concentratedly heated, the activation starts from the axial center portion of the main catalyst H, In addition, since the temperature of the main catalyst can be rapidly increased as a whole, the temperature can be rapidly reduced to, for example, about 300 ° C. to 400 ° C. without consuming a large amount of electric power.

As described above, the electrically heated catalyst 20 can be disposed at an appropriate position in the vicinity of the upstream and downstream sides of the small thin catalyst F2 so that a part of the main catalyst H can be activated quickly, so that the main catalyst H can be activated quickly. A large amount of heat can be supplied and the temperature can be raised from the time. Further, even if the electrically heated catalyst 20 is arranged in the same manner as above in the vicinity of the upstream and downstream sides of the small thin catalyst F1 arranged in the catalyst case 2 of the split catalyst 50, the same operational effect is obtained. Can play.

If the electrically heated catalyst and the thin catalyst portion F are integrally formed into an electrically heated thin catalyst, the whole can be made compact. (Second Embodiment) FIG. 25 is a longitudinal sectional view showing a second embodiment, in which the central axis 14b of the main catalyst H is arranged so as to be inclined with respect to the central axis 14a of the small catalyst F2. It was done.

In the second embodiment, the inlet expansion portion 12a is expanded upward by α degrees from the connecting portion 8 of the exhaust pipe as shown in FIG. The laminar flow Q5 can flow more widely in the axial center portion of the main catalyst H. Next, the second heating catalyst section 20b shown in FIG.
If is heated, as in the above case, the ring-shaped laminar flow Q6 can raise the temperature of the entire main catalyst H as a result, and abrupt activation can be achieved.

That is, the main catalyst H provided in the exhaust system of the engine and the small thin catalyst capable of raising the temperature of a part or all of the exhaust gas flowing into the exhaust system in the vicinity of the upstream side of the main catalyst H. Since it has F2, it is possible to obtain substantially the same operational effects as those of the above-described respective embodiments. Also, a small thin catalyst F2
Is considered to be activated from the central portion of the catalyst, but in the state where the peripheral portion is not activated, only the central portion of the main catalyst H is warmed up, and heat is discharged without heating the peripheral portion, which is not desirable.

In order for hot gas to reach the front surface of the main catalyst H,
If the distance between the small-sized thin catalyst F2 and the main catalyst H is increased, the heat radiation during this time increases and the opposite effect occurs. Therefore, it is necessary to keep the distance below a certain value. Further, as shown in FIG. 25, when the central axis of the main catalyst H is arranged so as to be inclined with respect to the central axes of the electric medium heating catalyst 20 and the small thin catalyst F2,
Even if the distance between the small thin catalyst F2 and the main catalyst H is kept at the current level, the high temperature gas can reach a wide surface of the main catalyst in a state where only the central portion of the small thin catalyst F2 is activated. As a result, the main catalyst H can be activated early.

Further, as described above, the first heating catalyst section 20a,
Since the second heating catalyst portion 20b is provided, the flow main catalyst H can be rapidly heated like the laminar flows Q5 and Q6 shown in FIG. Therefore, for example, about 300 ° C to 400 ° C
With the electric heating catalyst of a small capacity, which is less expensive than the conventional electric heating catalyst, it is possible to easily and rapidly raise the temperature without consuming a large amount of electric power.

Further, the above electrically heated catalyst 20 and thin catalyst F
If the 1 or small thin catalyst F2 is integrally formed, the whole can be made compact. In each of the above embodiments, the main catalyst H and the thin catalyst F1 or the small thin catalyst F2 are used.
Since the activating action of the catalyst is not taken into consideration, if the activating action is added, the temperature rise can be further rapidly accelerated from the test result.

In each of the above embodiments, the inlet type catalyst 60 is used.
However, even if the electrically heated catalyst 20 is applied to the split type catalyst 50 or a single type catalyst that has been conventionally used, the same operation and effect as above can be obtained. Further, as is apparent from the above-described embodiment of the present invention, when the present invention rapidly activates the catalyst, first, the shape of the catalyst case 2, the shape of the thin catalyst portion F, and the catalyst case described above are used. 2. Due to the mutual arrangement positions of the thin catalyst part F and the main catalyst H, the exhaust gas flow rate distribution in the thin catalyst part F is biased, and the exhaust gas whose temperature is increased by accelerating the flow speed is mainly used. It is possible to raise the temperature to high and medium temperatures with the catalyst H, and to purify the exhaust gas by using the electrocatalyst having the smallest capacity as described above to achieve the desired activation temperature in the shortest possible time. .

In the embodiment of the invention described above, the case of the engine has been described, but although not shown, the same operation as in the above embodiment can be applied to the case where the invention is applied to purification of exhaust gas by combustion from a combustion furnace such as a boiler or a blast furnace. It is possible to exert an effect. Further, in the present embodiment, the configuration in which the electrically heated catalyst 20 is divided into two has been described, but the present invention is not limited to this configuration at all, and the number and direction in which the electrically heated catalyst 20 is divided according to various conditions. Can be set in any way.

Further, in this embodiment, the electrically heated catalyst 2 is used.
The first heating catalyst 20a and the second heating catalyst 20 of 0 are set to be controlled to be switched between two stages of ON and OFF, respectively, but the heat quantity of one heating catalyst is set to be higher than the heat quantity of the other heating catalyst in advance. The heating catalysts may be operated simultaneously in such a state, and both heating catalysts may be gradually changed continuously or stepwise so that the heat amount of the other heating catalyst increases under certain conditions.

Further, the first heating catalyst and the second heating catalyst may be simultaneously operated in the same heat quantity state so that the heat quantity of one heat catalyst becomes lower than that of the other under certain conditions.

[0084]

As described above in detail, according to the exhaust gas purifying apparatus of the present invention as set forth in claim 1, the main catalyst provided in the exhaust system and the main catalyst provided upstream of the main catalyst and flowing into the exhaust system. Since it is composed of an electric heating catalyst that can selectively raise the temperature of the heating catalyst portion of the electric heating catalyst that is provided along the exhaust gas flow and is divided into a plurality of parts, By dividing the heating of the heating catalyst part into a plurality of stages, activating and activating in the previous stage heating, and by supplying the high temperature gas to the unactivated heating catalyst part in the heating in the next stage, The peripheral portion of the main catalyst can be activated and further accelerated to promote the activation of the entire main catalyst.

That is, since the temperature is raised by the heating catalyst section operated as described above and is biased by the flow velocity distribution of the exhaust gas in the thin catalyst section, a part of the bias flowing in the thin catalyst section is caused. It is possible to heat the exhaust gas provided with the above in a concentrated manner to form a substantially laminar flow state and to flow the inside of the main catalyst from the upstream side to the downstream side. Therefore, as described above, the plurality of laminar flows heated and activated and heated in a plurality of stages by the electrically heated catalyst as described above are gradually supplied to the main catalyst to be gradually activated, which becomes a spark. Since the entire main catalyst is efficiently activated and a rapid temperature rise can be obtained within a short time, it is possible to effectively achieve purification of exhaust gas within tens of seconds immediately after starting. is there.

According to the exhaust gas purifying apparatus of the present invention as set forth in claim 2, in the structure as set forth in claim 1, the divided heating catalyst parts of the electric heating catalyst can be operated by arbitrarily ranking them or operating them. Since it is configured to operate by switching, the laminar flow that has been raised in temperature can be effectively supplied to the main catalyst by applying the order selectively according to the specifications. , It becomes an ignition source, and the whole main catalyst is efficiently activated and a rapid temperature rise can be obtained within a short time. Therefore, it is effective to achieve purification of exhaust gas within several tens of seconds immediately after starting. Is something that can be done.

According to the exhaust gas purifying apparatus of the third aspect of the present invention, in the structure of the first or second aspect, the heating catalyst portion divided into a plurality of the electric heating catalysts is selectively operated. Since the control device is provided, the divided heating catalyst parts are appropriately sequenced or appropriately switched, so that the plurality of laminar flows heated and activated in a plurality of stages by the electric heating catalyst are heated, It is supplied to the main catalyst stepwise and activated step by step, and it becomes a spark and the whole main catalyst is efficiently activated and a rapid temperature rise can be obtained within a short time. Achieving purification of exhaust gas within tens of seconds can be effectively performed.

According to the exhaust gas purifying apparatus of the present invention as set forth in claim 4, in the structure as set forth in any one of claims 1 to 3,
The control device for the electrically heated catalyst is an engine cooling water temperature, an accelerator pedal opening, a temperature difference between thermocouples arranged upstream and downstream of the electrocatalyst or a wake thermocouple temperature, and operation signal detection means such as a timer. It is effective to achieve exhaust gas purification within a few tens of seconds immediately after starting by activating and activating the catalyst intensively at the time when exhaust gas is easily discharged. Is what you can do.

According to the exhaust gas purifying apparatus of the present invention as set forth in claim 5, in the structure as set forth in any one of claims 1 to 4,
Since the thin catalyst portion is disposed upstream or downstream of the electrically heated catalyst and has a thickness in the flow direction of the exhaust gas thinner than the main catalyst, the exhaust gas of the thin catalyst portion Since the deviation is given by the flow velocity distribution, a portion of the exhaust gas flowing in the thin catalyst portion is concentratedly heated to a substantially laminar flow state, and the inside of the main catalyst is changed from upstream to downstream. Can be flushed.

Therefore, it is possible to effectively achieve purification of the exhaust gas within several tens of seconds immediately after the start. According to the exhaust gas purifying apparatus of the present invention as set forth in claim 6,
In the structure according to any one of claims 1 to 5, a catalyst case that stores at least the main catalyst and is connected to an exhaust pipe provided in an exhaust system having the electrically heated catalyst, and the catalyst case. The inlet expansion part of the catalyst case formed so that the flow cross-sectional area of the exhaust gas from the connection part of the exhaust pipe to the inlet of the main body of the catalyst case gradually increases, and the exhaust gas near the upstream side of the main catalyst. Since the thin catalyst portion having a thickness in the flow direction, which is arranged at intervals in the flow direction, is formed to be thinner than the main catalyst,
The inlet of the inlet expansion portion of the catalyst case may be rapidly expanded, the thickness of the thin catalyst portion may be reduced, and the flow velocity distribution of the exhaust gas may be intentionally biased, and the biased exhaust gas flow velocity may be accelerated. it can.

Therefore, the heated laminar flow of the electrically heated catalyst causes the exhaust gas, to which the bias has been imparted in the thin catalyst portion, to be heated in a concentrated manner into a substantially laminar flow state, and to flow into the interval. It is possible to flow from the upstream side to the downstream side in the main catalyst. Therefore, the exhaust gas whose temperature has been raised within the above interval is activated in the main catalyst, which serves as a fire to activate the whole main catalyst, and a rapid temperature rise can be obtained within a short time. It is possible to effectively achieve purification of exhaust gas within a few tens of seconds immediately after starting.

According to the exhaust gas purifying apparatus of the present invention as set forth in claim 7, in the structure as set forth in claim 6, the length of the inlet expansion portion in the exhaust gas flow direction is formed to be about 5 to 25 mm. Therefore, the exhaust gas having the above-mentioned deviation with respect to the average flow velocity of the exhaust gas by the thin catalyst portion is about 10% to 65%.
Since the gas can be accelerated, a portion of the exhaust gas flowing in the thin catalyst portion is concentratedly heated so as to have a substantially laminar flow state as described above and flow out into the interval, Can flow from upstream to downstream in the main catalyst,
It is possible to effectively achieve purification of exhaust gas within tens of seconds immediately after starting.

According to the exhaust gas purifying apparatus of the present invention described in claim 8, in the structure of claim 5 or 6, the thin catalyst portion is formed to have a thickness in the exhaust gas flow direction of about 5 to 45 mm. Therefore, the exhaust gas having the above-mentioned bias given to the average flow velocity of the exhaust gas by the thin catalyst portion is about 10% to 38%.
%, It is possible to accelerate the exhaust gas, which is partly biased in the thin catalyst portion, into a substantially laminar flow state so that the exhaust gas flows into the main catalyst. Can be made to flow from upstream to downstream, and purification of exhaust gas within several tens of seconds immediately after starting can be effectively achieved.

According to the exhaust gas purifying apparatus of the present invention as set forth in claim 9, in the structure as set forth in any one of claims 5, 6 and 8, the interval between the main catalyst and the thin catalyst portion in the distribution direction. Is formed in a range of about 15 mm, so that a portion of the exhaust gas flowing in the thin catalyst portion having the above-mentioned deviation is concentratedly heated and held and supplied to the main catalyst. Can be made to flow in the interval in the substantially laminar flow state, can flow from the upstream in the main catalyst from the downstream, it is effective to achieve purification of the exhaust gas within tens of seconds immediately after the start. Is what you can do.

According to the exhaust gas purifying apparatus of the present invention as set forth in claim 10, in the structure as set forth in any one of claims 5 to 9, from the central axis of the main catalyst in the flow direction to the outer periphery of the main catalyst. A distance ratio r / R between the length R and the length r from the center of the axis to the outer periphery of the laminar flow of the exhaust gas heated in the thin catalyst portion toward the main catalyst is set to about 40 to 60%. Therefore, the exhaust gas which has been biased by the thin catalyst portion with respect to the average flow velocity of the exhaust gas is about 10% to 6%.
Since it can be accelerated by 5%, a portion of the exhaust gas flowing in the thin catalyst portion is concentratedly heated so as to be in the substantially laminar flow state and discharged into the interval. The main catalyst can be made to flow from upstream to downstream, and the exhaust gas can be effectively purified within a few tens of seconds immediately after starting.

According to the exhaust gas purifying apparatus of the present invention described in claim 11, in the structure described in claim 6, the length of the inlet expansion portion of the catalyst case in the exhaust gas flow direction is about 5 to 25.
mm, the thickness of the thin catalyst portion in the flow direction is about 5 to 45 mm, and the distance between the main catalyst and the thin catalyst portion in the flow direction is about 15 mm. And the distance ratio r / R from the central axis
Is formed in about 40 to 60%, the exhaust gas to which the above-mentioned bias is given by the thin catalyst part can be accelerated by about 10% to 65% with respect to the average flow speed of the exhaust gas. Part of the non-uniformity of the exhaust gas flowing in the shaped catalyst section is concentratedly heated to the above-mentioned substantially laminar flow state, and is made to flow into the above interval so that the main catalyst can flow from upstream to downstream. It is possible to effectively achieve purification of exhaust gas within tens of seconds immediately after starting.

According to the exhaust gas purifying apparatus of the present invention as set forth in claim 12, in the structure as set forth in any one of claims 5, 6 and 11, the catalyst case connected to the exhaust pipe and housed in the catalyst case. Since the main catalyst and the thin catalyst portion housed in the catalyst case in the vicinity of the upstream side of the main catalyst are provided, a part of the deviation flowing in the thin catalyst portion is The supplied exhaust gas is heated in a concentrated manner into a substantially laminar flow state so that the exhaust gas can flow out at the intervals and flow from the upstream side to the downstream side in the main catalyst, and the output loss of the engine can be suppressed to reduce the main catalyst. It is possible to accelerate the temperature rise locally.

Therefore, it is possible to effectively achieve purification of the exhaust gas within several tens of seconds immediately after the start. According to the exhaust gas purifying apparatus of the present invention as set forth in claim 13, in the structure according to any one of claims 5, 6 and 11, the inside of the exhaust pipe in the vicinity of the catalyst case inlet of the exhaust pipe connected to the catalyst case Since the thin catalyst portion is provided in the above, the output loss of the engine increases, but the local temperature rise of the main catalyst can be greatly promoted.

According to the exhaust gas purifying apparatus of the present invention as set forth in claim 14, in the constitution as set forth in any one of claims 5, 6, 11, 12 and 13, the electrically heated catalyst and the thin catalyst part are provided. Since the integrally formed electrically heated thin catalyst is disposed in the exhaust pipe near the inlet of the catalyst case, the overall size becomes compact, the flow resistance in the exhaust pipe decreases, the flow velocity of the exhaust gas is accelerated, and the temperature rises. Can be promoted.

According to the exhaust gas purifying apparatus of the present invention as set forth in claim 15, in the structure as set forth in any one of claims 5, 6, 11 and 12, the electric heating catalyst and the thin catalyst portion are integrally formed. Since the formed electrically heated catalyst is arranged in the vicinity of the upstream side of the main catalyst in the catalyst case, the overall size becomes compact and the capacity of the main catalyst in the catalyst case can be increased. The purification capacity can be increased.

According to the exhaust gas purifying apparatus of the present invention as set forth in claim 16, in the structure as set forth in any one of claims 5 to 11, the main catalyst provided in the exhaust system of the engine and the upstream of the main catalyst. And a thin catalyst portion capable of raising a temperature of a part of exhaust gas flowing into the exhaust system, wherein the central axis of the main catalyst is inclined with respect to the central axis of the thin catalyst portion. Therefore, even if the above-mentioned thin catalyst portion and the main catalyst are kept at the present distance, the high temperature gas is spread over the wide surface of the main catalyst in a state where only the central portion of the thin catalyst portion is activated. Can be supplied to promote early activation of the main catalyst.

According to the exhaust gas purifying apparatus of the present invention as set forth in claim 17, in the structure as set forth in any one of claims 1 to 6, 12, 13, and 14, the heating catalyst in which the electric heating catalyst is divided is divided. Since the portion is the electrically heated catalyst that is concentrically divided, if the heating is performed from the axial center portion of the axis line of the exhaust gas flow direction of the electrically heated catalyst, the heat does not escape from the outer peripheral wall of the catalyst case, Achieves purification of exhaust gas within a few tens of seconds immediately after start-up because the activated catalyst is intensively activated from the axial center portion and then the divided heating catalyst portion on the outer periphery of the axial center portion is heated and activated. Is something that can be done effectively.

According to the exhaust gas purifying apparatus of the present invention as set forth in claim 18, in the structure as set forth in any one of claims 1 to 6, 12, 13 and 14, the heating catalyst in which the electric heating catalyst is divided is divided. Since the parts are arranged in parallel in the exhaust gas flow direction in the exhaust system, the divided heating catalyst parts are arranged so as to be upstream and downstream with respect to the exhaust gas flow direction. If the heating catalyst portion is appropriately selectively activated to be activated, the heating catalyst portion of the shaft center portion is heated from the shaft center portion of the axis line in the exhaust gas flow direction of the electric heating catalyst, and is heated from the outer peripheral wall of the catalyst case. The heat does not escape and is intensively activated from the axial center portion, and then the divided heating catalyst portion is heated and activated, so that the exhaust gas can be purified within tens of seconds immediately after the start. Is something that can be done effectively.

According to the exhaust gas purifying apparatus of the present invention as set forth in claim 19, in the structure as set forth in any one of claims 1 to 6, the electrically heated catalyst is arranged on the central axis of the exhaust gas flow of the main catalyst. The first heated catalyst portion for generating a laminar flow of the heated exhaust gas flowing through the central portion along with the exhaust gas flowing in the outer peripheral portion of the heated laminar flow of the central portion of the main catalyst was heated. Since it is composed of the second heating catalyst portion for generating a laminar flow, if the heating is performed from the axial center of the axis line of the electric heating catalyst in the exhaust gas flow direction, the heat escapes from the outer peripheral wall of the catalyst case. Instead, it is intensively activated from the shaft center portion, and then the divided heating catalyst portion on the outer periphery of the shaft center portion is heated and activated, so that the exhaust gas can be purified within several tens of seconds immediately after the start. What you achieve is what you can do effectively.

[0105] According to the exhaust gas purifying apparatus of the present invention as set forth in claim 20, in the structure of claim 19, the first heating catalyst portion is concentrically provided with a space and substantially the outer peripheral portion of the main catalyst. Since it is composed of a second heating catalyst portion for generating a laminar flow of the exhaust gas heated in the vicinity, a laminar flow of the exhaust gas heated in the vicinity of the outer periphery of the main catalyst is generated, An effective temperature rise can be achieved in which the laminar flow serves as a heat insulating wall for the catalyst.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a first embodiment in which an exhaust gas purifying apparatus of the present invention is applied to an engine.

FIG. 2 is a vertical cross-sectional view showing a case where a single type catalyst is applied to the first catalyst of FIG.

3 is a vertical cross-sectional view showing a case where a split catalyst is applied to the first catalyst of FIG.

FIG. 4 is a vertical cross-sectional view showing a case where an inlet catalyst is applied to the first catalyst of FIG.

FIG. 5 is a schematic diagram showing dimensions of each part of the catalyst case and the catalyst of FIG.

FIG. 6 is a performance diagram showing the inlet shape and the flow velocity distribution of FIG.

FIG. 7 is a performance diagram showing the inlet shape and pressure loss of FIG.

8 is a performance diagram showing the thickness and flow velocity distribution of the thin catalyst portion of FIG.

9 is a performance diagram showing a gap between the thin catalyst portion and the main catalyst of FIG. 5 and a catalyst temperature history.

10 is a state diagram showing the flow and temperature distribution in the catalyst of the split catalyst of FIG.

11 is a state diagram showing the flow and temperature distribution in the catalyst of the inlet type catalyst of FIG.

FIG. 12 is a state diagram showing a flow and temperature distribution in the single type catalyst of FIG. 2 in the catalyst.

FIG. 13 is a performance diagram showing a catalyst temperature history after the first catalyst of FIG. 1 is started.

FIG. 14 is a pressure comparison diagram showing pressure loss due to the shape of a catalyst case applied to the first catalyst of FIG.

FIG. 15 is a performance diagram showing the flow rate and flow velocity distribution of the exhaust gas in FIG.

16 is a small thin catalyst 2 used for the first catalyst of FIG.
FIG. 6 is a schematic explanatory view showing a layout when an electrically heated catalyst is arranged in an exhaust pipe on the upstream side of FIG.

FIG. 17 is a schematic diagram showing the electrically heated catalyst of FIG.
17A is a vertical cross-sectional view schematically enlarging the electrically heated catalyst of FIG. 16, and FIG. 17B is a side view schematically showing the Y arrow of FIG. 17A.

18 is an explanatory diagram showing a state in which a laminar flow of which the first heated catalyst portion of the electrically heated catalyst of FIG. 17 is heated and heated is flowing downstream.

FIG. 19 is an explanatory view showing a state in which the second heating catalyst portion of the electrically heated catalyst of FIG. 17 is heated and the laminar flow of which the temperature has been raised flows downstream.

20 is an explanatory view showing an application example in which the disposition position of the divided heating catalyst portion of the electric heating catalyst of FIG. 17 is changed,
20A is a schematic vertical sectional view, and FIG.
It is the side view which showed typically the X arrow view of (A).

FIG. 21 is a graph showing the elapsed time after the engine start of FIG. 1 and the detection threshold value of each operation signal, (A) switching with water temperature, (B) switching with accelerator opening,
(C) shows switching by wake thermocouple temperature, (D) shows switching by thermocouple temperature difference, and (E) shows switching by time.

22 is an explanatory diagram showing another application example of the divided heating catalyst portion of the electrically heated catalyst of FIG.

23 is an explanatory view showing another application example of the divided heating catalyst portion of the electrically heated catalyst of FIG.

24 is a flowchart showing an operation routine of the electrically heated catalyst of FIG.

FIG. 25 is a vertical sectional view showing a second embodiment of the present invention.

FIG. 26 is a functional configuration diagram showing an exhaust gas purification apparatus of a conventional example.

FIG. 27 is a functional configuration diagram showing another conventional exhaust gas purifying apparatus.

[Explanation of symbols]

 1 Engine 1a Cooling Chamber 1b Throttle Valve 2 Catalyst Case 2a Catalyst Body 2b Catalyst Case Body Inlet 3 Combustion Chamber 4 Catalyst 5 Exhaust Pipe 7 Oil Pan 8 Exhaust Pipe Connection 9 1st Catalyst 11 2nd Catalyst 12 Inlet Expansion part 13 Intake pipe 14 Central axis 14a Small thin catalyst central axis 14b Main catalyst central axis 15 Secondary air pump 16 Laminar flow 17 Supply port 19 Check valve 20 Electric heating catalyst 20a-20n Electric heating catalyst heating catalyst Part 21 Exhaust port 40 Single catalyst 45 Inlet change Single catalyst 50 Split catalyst 60 Inlet catalyst CD Thermocouple sensor CM Actuation detection signal means CS Axle position sensor CT timer CW Water temperature sensor D1 Electric heating catalyst electrode D2 Electrode of electrically heated catalyst D3 Electrode of electrically heated catalyst F Thin catalyst part F1 Thin catalyst F2 Small and thin Shaped catalyst H Main catalyst L Inlet extension length N1 Thermocouple N2 Thermocouple S Distance between thin catalyst part and main catalyst T Thickness of thin catalyst part h Fast exhaust gas flow s Slow exhaust gas flow y Exhaust gas flow Uniformized flow velocity distribution w Exhaust gas flow

Claims (20)

[Claims] 1. A main catalyst provided in an exhaust system, and a heating catalyst section of an electric heating catalyst which is provided upstream of the main catalyst and is arranged along an exhaust gas flow flowing in the exhaust system and is divided into a plurality of parts. An exhaust gas purifying device comprising an electrically heated catalyst capable of selectively raising the temperature. 2. The divided heating catalyst portion of the electrically heated catalyst is configured to be operated in an arbitrary order or to be operated by switching in a predetermined order. Exhaust gas purification device. 3. The exhaust gas purifying apparatus according to claim 1 or 2, further comprising a control device for selectively operating a heating catalyst portion of the electrically heated catalyst divided into a plurality of parts. 4. The control device for the electrically heated catalyst, wherein the temperature of the cooling water of the engine, accelerator pedal opening, temperature difference of thermocouples arranged upstream and downstream of the electrocatalyst or wake thermocouple temperature, timer, etc. The exhaust gas purifying apparatus according to any one of claims 1 to 3, wherein the exhaust gas purifying apparatus is configured to be operated by the operation signal detecting means. 5. A thin catalyst portion disposed near the upstream or downstream of the electrically heated catalyst and having a thickness in the exhaust gas flow direction thinner than the main catalyst.
The exhaust gas purifying apparatus according to claim 1. 6. A catalyst case which houses at least the main catalyst and is connected to an exhaust pipe provided in an exhaust system having the electrically heated catalyst, and the catalyst case from the connecting portion of the exhaust pipe of the catalyst case. The inlet expansion portion of the catalyst case formed so that the flow cross-sectional area of the exhaust gas up to the inlet of the main body of the main catalyst and the upstream side of the main catalyst are spaced apart in the flow direction of the exhaust gas. The exhaust gas purifying apparatus according to any one of claims 1 to 5, further comprising: the thin catalyst portion whose thickness in the flow direction is thinner than that of the main catalyst. 7. The exhaust gas purifying apparatus according to claim 6, wherein the length of the inlet expansion portion in the exhaust gas flow direction is about 5 to 25 mm. 8. The exhaust gas purifying apparatus according to claim 5, wherein the thin catalyst portion has a thickness in the exhaust gas flow direction of about 5 to 45 mm. 9. The method according to claim 5, wherein the main catalyst and the thin catalyst portion are formed so that the distance in the flow direction is about 15 mm. The exhaust gas purifying apparatus according to. 10. The length R from the central axis of the main catalyst in the flow direction to the outer periphery of the main catalyst and the temperature of the exhaust gas heated from the center of the axis to the thin catalyst section toward the main catalyst. The distance ratio r / R to the length r to the outer circumference of the laminar flow is about 40 to 60%.
The exhaust gas purification apparatus according to any one of 1 to 9. 11. The length of the inlet expansion portion of the catalyst case in the exhaust gas flow direction is about 5 to 25 mm, and the thickness of the thin catalyst portion in the flow direction is about 5 to 45 mm. The main catalyst and the thin catalyst portion are arranged such that the distance in the flow direction is about 15 mm, and the distance ratio r / R from the central axis is set to about 40 to 60%. The exhaust gas purifying apparatus according to claim 6, characterized in that 12. A catalyst case connected to an exhaust pipe, the main catalyst housed in the catalyst case, and the thin catalyst section housed in the catalyst case near the upstream side of the main catalyst. 5. The method according to claim 5, 6, or 1, further comprising:
The exhaust gas purification apparatus according to any one of 1. 13. The thin catalyst portion is provided in the exhaust pipe near the catalyst case inlet of the exhaust pipe connected to the catalyst case, according to claim 5, 6, or 11. Exhaust gas purification device described. 14. The electric heating thin catalyst in which the electric heating catalyst and the thin catalyst portion are integrally formed is arranged in an exhaust pipe near an inlet of the catalyst case. , 6, 11, 12. 13. The exhaust gas purifying apparatus according to any one of 1. 15. The electrically heated thin catalyst in which the electrically heated catalyst and the thin catalyst portion are integrally formed is disposed in the vicinity of an upstream side of the main catalyst in the catalyst case. The exhaust gas purifying apparatus according to claim 5, 6, 11, or 12. 16. The main catalyst provided in an exhaust system of an engine, and the thin catalyst section provided upstream of the main catalyst and capable of heating a part of exhaust gas flowing into the exhaust system. , Characterized in that the central axis of the main catalyst is formed to be inclined with respect to the central axis of the thin catalyst portion,
The exhaust gas purifying apparatus according to claim 5. 17. The heating catalyst portion of the electrically heated catalyst, which is divided, is the electrically heated catalyst which is concentrically divided, and any one of claims 1 to 6, 12, 13, and 14. The exhaust gas purifying apparatus according to. 18. The divided heating catalyst portion of the electrically heated catalyst is arranged in parallel in the exhaust system in the flow direction of the exhaust gas.
The exhaust gas purification device according to any one of 1. 19. The electrically heated catalyst comprises a first heated catalyst section for generating a laminar flow of the heated exhaust gas flowing through a central portion along a central axis of the exhaust gas flow of the main catalyst, and the main catalyst center. 7. A second heating catalyst unit for generating a heated laminar flow of the exhaust gas flowing through the outer peripheral portion of the heated laminar flow of a portion, any one of claims 1 to 6, characterized in that The exhaust gas purifying apparatus according to claim 2. 20. A second heating catalyst section for generating a laminar flow of the heated exhaust gas, which flows concentrically near the outer periphery of the main catalyst with a space in the first heating catalyst section. The exhaust gas purifying apparatus according to claim 19, wherein the exhaust gas purifying apparatus is provided.