JP6807567B1 - Regeneration system and regeneration method of diesel particulate filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously use DPF by oxidizing and removing PM (particulate matter) collected by DPF (diesel particulate filter) installed in a diesel engine of an automobile or the like by the action of a catalyst. Provide a system and method to do so. SOLUTION: A pipe (3) connecting a PM reduction device (1) and an engine (2) and a PM reduction device (1) have a heat insulating structure, and a means (4) for heating exhaust gas flowing into the PM reduction device (1). ), The exhaust gas dispersion plate (5), the temperature sensor (6), and the pressure sensor (7) are provided in the PM reduction device (1), and the operation of the heating means can be controlled by the signal from the pressure sensor. A regeneration system for a diesel particulate filter, which comprises a control device (8). [Selection diagram] Fig. 1

Description

In the present invention, PM (particulate matter) collected by a DPF (diesel particulate filter) installed in a diesel engine of an automobile or the like is oxidized and removed by the action of a catalyst, thereby continuously using the DPF. Regarding the system and method to enable it.

In order to enable continuous use by oxidizing and removing PM collected in the DPF installed in a diesel engine of an automobile or the like by the action of a catalyst, (1) First, DOC (diesel oxidation catalyst) ), The PM component SOF (soluble organic component) contained in the exhaust gas is oxidized and removed in the temperature range of 250 to 450 ° C., and the NO (nitric oxide) generated in the combustion chamber of the engine is oxidized. , NO ₂ (nitric oxide) needs to be changed. Next, in the DPF, the collected PM component C (carbon, soot) is used as a catalyst such as Pt (platinum) and CeO ₂ (cerium oxide) supported on the DPF, and O ₂ (oxygen) in the exhaust gas. It is necessary to remove this by oxidizing it at a temperature of 400 ° C. or lower (changing it to CO and CO ₂ which are carbon compounds) by the action of NO ₂ (hereinafter, this is referred to as DPF regeneration). (2) In a PM reduction device composed of a DOC and a DPF, in order to realize this effect, a temperature of about 250 ° C. or higher is required for the DOC and about 350 ° C. or higher for the DPF. This temperature can be achieved only by the exhaust gas of the engine because the temperature of the exhaust gas is high during steady operation (normal driving), but since the exhaust gas temperature is low during low load operation including immediately after the engine is started. It is difficult to achieve the temperature required for DPF regeneration. (3) For this reason, a method of injecting fuel from a fuel injection device installed in the exhaust system and oxidizing this fuel in the DOC to raise the temperature of the exhaust gas and obtain the target temperature, from the engine to the DOC. The temperature of the exhaust gas is raised by installing an electric heater in the middle of the exhaust pipe to reach the exhaust pipe to raise the temperature of the exhaust gas to obtain the desired temperature, or by narrowing the intake air and circulating the exhaust gas to the intake side. The method of obtaining the target temperature is used.

Among these methods, for example, in Patent Document 1, fuel injection is performed in the exhaust stroke in addition to the injection in the latter stage of the normal compression stroke, and the exhaust temperature is raised by burning this fuel with an oxidation catalyst. Further, by energizing the electric heater installed in the oxidation catalyst as needed, the exhaust gas of, for example, about 400 ° C. to 500 ° C. flows into the DPF, so that NO _{2 in} the exhaust can easily be mixed with the soot deposited on the DPF. It reacts and the soot is removed. Further, in Patent Document 2, the amount of soot accumulated on the DPF during deceleration of the vehicle or idling in the stopped state is calculated using the temperature and pressure of the exhaust gas, and this amount exceeds the set value (for example, 10 g). In this case, the intake throttle valve is closed wide and the exhaust recirculation control valve is wide open to raise the temperature of the exhaust gas passing through the catalyst.

In these documents, the criteria for controlling the timing and amount of fuel injection, whether or not the electric heater is energized, and controlling the flow rate of intake and exhaust are mainly the temperature of the exhaust gas flowing into the DOC and DPF. .. The lower the activation temperature of the catalyst supported on the DOC or DPF, the more stable the performance can be exhibited under various usage conditions (operating conditions). However, the catalyst supported on the DOC or DPF due to technological improvement of the catalyst or the like. The temperature required for activation of the swelling may decrease in the future. For example, Patent Document 3 describes that the composition of silver-stabilized ceria and cobalt-stabilized ceria oxidizes soot at 250 to 300 ° C. in the presence of NO ₂ and O ₂ . Further, Patent Document 4 describes a method for improving the efficiency of fuel for an internal combustion engine by adding cerium oxide to fuel in fuel refining, fuel storage, and refueling facilities.

Japanese Unexamined Patent Publication No. 9-137716 Japanese Unexamined Patent Publication No. 10-68315 Japanese Unexamined Patent Publication No. 2004-42021 Special Table 2006-516996

In order to effectively oxidatively remove PM collected in the DPF installed in a diesel engine of an automobile or the like by the action of a catalyst, it is necessary to raise the exhaust temperature to a temperature higher than the temperature at which the catalyst is activated. In automobiles, etc., this temperature does not reach when idling or when the load is low, so a method of injecting fuel by installing a fuel injection device in the exhaust system and an electric heater installed in the middle of the exhaust pipe to heat the exhaust gas. Although methods are used, from the viewpoint of preventing global warming and saving energy, fuel consumption and electricity consumption are reduced as much as possible, and PM collected in the DPF is effectively used while maintaining engine performance. Needs to be removed. In addition, it is necessary to develop a DPF that supports a catalyst that activates in a lower temperature range than before, and to support technologies that can activate even in a low temperature range by adding this catalyst to fuel. It is necessary to continue to develop DPF regeneration systems and regeneration methods that respond to technological innovation.

Therefore, the present invention provides a DPF regeneration system and a regeneration method having the following elements, which are easy to handle, have high reliability, and have a structure and a function such that the input energy for operating the DPF is as small as possible. The purpose is.
(1) Used in many general devices such as PM reduction devices, engines, exhaust pipes, means for heating exhaust gas , or heating devices such as electric heaters , exhaust gas dispersion plates, temperature sensors , pressure sensors, and control devices. By using a proven device, it will have a structure and functions with versatility, reliability and durability.
(2) By making the PM reduction device and the exhaust pipe a heat insulating structure, it has a function of preventing the temperature of the exhaust gas from dropping.
(3) Ceria or the like is added to the fuel injected from the fuel injection device installed at any one of the engine, exhaust pipe, and PM reduction device as a means for heating the exhaust gas or as a heating device such as an electric heater . It has a function to add a catalyst.
(4) A distributed plate with a plurality of holes is installed in the PM reduction device to make the temperature distribution in the DOC and DPF uniform, and to have a function of effectively oxidizing and removing oxidation.
(5) A function for detecting the accumulation state of soot in the device by a signal emitted from a temperature and pressure sensor installed in the PM reduction device and operating a means for heating the exhaust gas or a heating device such as an electric heater. By incorporating a control device having the DPF, the regeneration of the DPF is effectively carried out.

PM in the exhaust gas is collected while passing through the DPF and is deposited in the DPF. If this is left unattended, the flow path of the exhaust gas will be narrowed, the exhaust pressure will rise and the engine performance will deteriorate, so it is necessary to remove it on a regular basis. When the PM collected in the DPF is removed by combustion, a temperature of about 600 ° C. or higher and oxygen are required, but it is difficult to always achieve this temperature in a diesel engine. Therefore, until around 2000, a method of burning and removing it by using an electric heater or a burner, or a method of backwashing by using the pressure of air was studied. According to subsequent research, a DOC was installed in front of the DPF and O ₂ in the catalyst and air was used to (1) HC consisting of unburned fuel and lubricating oil components contained in the exhaust gas, and when the fuel was incompletely burned. Oxidize the generated CO to produce H ₂ O and CO ₂ , (2) Oxidize NO in the combustion gas to produce NO ₂ , and ((3) Exhaust gas due to the heat generated by the oxidation reaction at this time. It has become possible to simultaneously cause the phenomenon of raising the temperature of the fuel. In addition, by supporting a catalyst such as Pt on the surface of the DPF installed after that, NO ₂ generated by DOC and exhaust gas By utilizing the phenomenon that the remaining O ₂ reacts with the soot (C) collected in the DPF to generate CO ₂ , the combustion and removal of the soot, which previously required a temperature of about 600 ° C. or higher, can be achieved. Oxidation and removal of soot by the catalyst and O ₂ and NO ₂ became possible at a temperature of 400 ° C. or lower .

According to previous studies, these oxidation reactions in the DOC require a temperature of about 250 ° C. or higher, and the oxidation removal of soot by the DPF requires a temperature of about 350 ° C. Since these temperatures can be achieved during normal operation of the diesel engine, the soot collected in the DPF is oxidized in real time with the PM reduction device consisting of DOC and DPF attached during normal operation. Since it can be removed, it can be said that the title of the present invention, "DPF regeneration system and regeneration method," is completed only by the DOC and DPF described in claim 1 in the present invention. During low load operation including startup, the exhaust gas temperature is low, so that the catalyst on the DOC and DPF does not function, and the PM discharged from the engine is deposited on the DPF. However, when the exhaust gas temperature rises to the temperature at which the catalyst on the DOC and the DPF is activated in the subsequent normal operation, the PM accumulated during the low load operation is sequentially oxidized and removed, and the DPF is regenerated.

However, in a route bus or a car traveling only in an urban area, if low load operation continues, the exhaust gas temperature does not reach the temperature at which the DOC and DPF are activated, and the PM collected in the DPF repeatedly accumulates. Since the surface of the catalyst carried on the DPF is completely covered, NO ₂ oxidized in the DOC and O _{2 in} the exhaust gas reach the surface of the soot (C), but cannot come into contact with the catalyst. , It becomes impossible to remove oxidation by catalyst. Such removing soot deposited on the DPF became state is the use of method of combustion removal by O ₂ under the temperature of about 600 ° C. or more as described above. However, when a phenomenon called "combustion" occurs in which the soot (C) deposited on the DPF reacts with O ₂ at a high temperature, the ambient temperature reaches a high temperature of 1000 ° C. or higher, which may burn the DPF itself. .. Also, when using the method of burning off, it takes extra energy to the high temperature of at least about 600 ° C. The exhaust gas temperature, global warming, is not preferable from the viewpoint of energy saving.

In order to prevent this, as described in most of the patent documents so far, (1) measures during normal operation when the exhaust gas temperature is high (the temperature conditions required for catalyst activation are reached) And (2) instead of setting the condition of dealing with low load operation when the exhaust gas temperature is low (the temperature condition required for catalyst activation has not been reached), from the beginning, "exhaust gas in most operating conditions" It is necessary to develop a PM reduction device by setting the condition that "the temperature has not reached the temperature at which the catalyst carried on the DOC and DPF is activated".

To that end, leading to (exhaust gas temperature is significantly reduced by the work by expansion) so, PM reduction apparatus from an engine and place a phenomenon that the combustion, the combustion temperature has reached more than 1000 ° C. in (1) Engine The structure shall be such that this temperature can be maintained as much as possible in the path (exhaust pipe). (2) The structure of the PM reduction device shall be such that the inside of the device is not cooled as much as possible by the outside air. (3) In the DOC and DPF, the outer circumference is easily cooled by the outside air, so the temperature tends to decrease. Therefore, even if the exhaust gas temperature reaches the activation temperature of the catalyst, if the outer circumference is lower than that, the soot cannot be oxidized and removed, and soot is likely to be deposited. When soot accumulates, the flow path narrows and the flow becomes worse, resulting in a vicious cycle of lowering the temperature. To prevent this, DOC and are within the PM reduction apparatus consists DOC and DPF, or prior to the DPF, by installing a distribution plate spaced plurality of holes around the flow of the exhaust gas DOC and or by dispersing until an outer peripheral portion of the DPF, DOC and, or it is necessary to equalize the temperature of the entire DPF. At the same time, in order to raise the temperature of the exhaust gas flowing into the PM reduction device to a temperature higher than the temperature at which the catalyst can be activated, a means for heating the exhaust gas flowing into the PM reduction device or a heating device such as an electric heater is installed. Then, by operating this as necessary, it is necessary to perform oxidative removal before PM becomes a state in which oxidative removal cannot be performed by covering the catalyst carried on the DPF.

The feature of the present invention is to develop a PM reduction device from the beginning by setting the condition that "in most operating conditions, the exhaust gas temperature does not reach the temperature at which the catalyst supported on the DOC and DPF is activated". There is. A system in which such a minimum condition is set is a general-purpose system that operates well under all conditions.
"In order to raise the temperature of the exhaust gas flowing into the PM reduction device to a temperature higher than the temperature at which the catalyst can be activated, a means for heating the exhaust gas flowing into the PM reduction device or a heating device such as an electric heater is installed. In order to "operate this as needed", it is important under what circumstances the heating device such as an electric heater is operated. When a heating device such as an electric heater is always operated, the exhaust gas temperature is always higher than the temperature at which the catalyst carried on the DOC and DPF is activated, so that the soot can be continuously oxidized and removed. Since it consumes energy, it is not preferable from the viewpoints of global warming prevention, energy saving, and economic efficiency.

As described above, normally, during low load operation including startup, the catalyst on the DOC and DPF does not function due to the low exhaust gas temperature, and the PM discharged from the engine is deposited on the DPF. become. However, when the exhaust gas temperature rises to the temperature at which the catalyst on the DOC and the DPF is activated in the subsequent normal operation, the PM accumulated during the low load operation is sequentially oxidized and removed, and the DPF is regenerated.
From this, the accumulation of soot on the DPF is allowed to some extent, but if the soot covers the surface of the catalyst, NO ₂ and O ₂ react with the catalyst to oxidize and remove the soot even if the temperature conditions are met. Therefore, it can be said that soot must be removed by oxidative removal before the reaction occurs. In addition, if the oxidation removal reaction does not occur even if the exhaust gas temperature is raised, soot deposition accelerates, causing deterioration of engine performance and burning and removing soot by raising the exhaust temperature to about 600 ° C or higher. Since a method with a risk of damage to the DPF will be used, it is necessary to sequentially oxidize and remove the soot accumulated on the DPF.

When soot on the DPF is deposited narrowing the flow path of the exhaust gas, the pressure within the exhaust system is increased. From this, it is possible to know the accumulation state of soot in the DPF by detecting the pressure in the exhaust pipe.
On the other hand, even if the exhaust gas temperature is raised to 350 ° C. or higher, which is said to activate the catalyst, the oxidation removal reaction does not occur if the catalyst is covered with soot. Therefore, in order to remove the soot, the exhaust gas temperature is adjusted. It is necessary to raise the temperature to about 600 ° C. or higher. In addition, since the activation temperature of the catalyst may decrease due to technological innovation, a means for heating the exhaust gas flowing into the PM reduction device based on the temperature , or a device for controlling the heating device such as an electric heater. Even if it is incorporated, there is a possibility that it will become obsolete in the future, and even at present, there is almost no data showing at what temperature the catalyst is activated in the actual machine, and the value is based on other conditions (for example, of the catalyst). It is greatly affected by the state of support, the state of soot adhesion, the concentration of NO ₂ as ambient conditions, etc.).

In the present invention, attention is paid to "exhaust system pressure" as an index capable of absolutely evaluating the soot adhesion state, and a temperature sensor and a pressure sensor are installed in the PM reduction device. When soot is deposited on the DPF, the flow path of the exhaust gas is narrowed, and when the amount of exhaust gas is constant, the pressure of the exhaust system rises. Immediately after starting the engine (idling operation) or during low-load operation where the exhaust gas temperature does not reach the catalyst activation temperature, the amount of exhaust gas can be considered to be almost constant (within the range of pressure fluctuation error in the exhaust system). Therefore, the temperature and pressure in the PM reduction device are detected, and the pressure is set when the temperature is below the temperature at which the catalyst carried on the DOC or DPF installed in the PM reduction device is activated (for example, 350 ° C. or less). When the temperature rises above the value, efficient control becomes possible by operating a means for heating the exhaust gas flowing into the PM reduction device or a heating device such as an electric heater . Even if the amount of soot accumulated on the DPF is constant, the amount of exhaust gas increases in proportion to the engine speed and the intake pressure, and the pressure of the exhaust system also increases accordingly. Therefore, the cylinder volume of the engine is adjusted in advance. type, leave calculated quantity of exhaust gas from a signal of the rotational speed and intake pressure of the engine, the measured pressure, the differential pressure between the pressure in the exhaust system for the calculated amount of exhaust gas is a certain value (e.g., 3 kPa) or higher In such a case, more accurate control becomes possible by providing a means for heating the exhaust gas flowing into the PM reduction device or a system for operating a heating device such as an electric heater .

The invention according to claim 1 is a material (cylindrical or tubular) having a circular cross-sectional shape and a length around a pipe connecting an engine and a PM reduction device composed of a DOC and a DPF , or around the PM reduction device. By winding a wire (such as a wire) in a spiral shape and making the outer circumference corrugated with some protrusions, the material stored in the container and the fluid flowing in the pipe change in temperature, resulting in thermal heat. Cover with a flat plate having a structure that can respond to various changes (expansion / contraction of containers and pipes), close both ends of the flat plate, and connect the PM reduction device (1) and the PM reduction device to the engine, and both ends. By making the closed space formed between the closed flat plate and the closed flat plate into a vacuum structure , it is possible to prevent the temperature of the exhaust gas flowing through the PM reduction device and the exhaust pipe connecting the PM reduction device and the engine from dropping. It is characterized by having.

It is well known that the heat insulating effect is significantly improved by forming a container or a pipe into a double structure and evacuating the inside thereof. However, when the inside of the container is evacuated, the internal pressure becomes almost zero, so that the outer portion having the double structure is deformed by the external pressure. In order to prevent this, measures are taken to prevent deformation by providing protrusions (including spiral installation of flat plates) on the inner container having a double structure. However, when this method is used, the structure becomes complicated and the heat of the inner container is transmitted to the outer container through the protrusions, so that the outer container also needs to be kept warm.

The amount of heat transfer between two substances is proportional to the contact area (heat transfer area), contact time and thermal conductivity. By creating a vacuum inside the double tube, there is almost no air, which is a substance that conducts heat, so the thermal conductivity becomes almost zero, and an outstanding heat retention effect can be obtained.
The feature of the present invention is that when the inside is evacuated as a double pipe, a circular substance is spirally wound to prevent the outer container from being deformed, so that a reinforcing effect at regular intervals can be obtained. it is that the contact between the inner material and the outer material of the double tube is "surface (there are heat transfer area)" from "line (almost no heat transfer area)." As a result, the same effect as that of a container having a double-tube structure with a vacuum inside can be obtained.
Further, the effect can be further enhanced by making the circular substance wound in a spiral shape hollow (the thermal conductivity of air is smaller than the thermal conductivity of solid) and further evacuating the inside thereof.

The invention according to claim 2 is a material (cylindrical or tubular) having a circular cross-sectional shape and a length around a pipe connecting an engine and a PM reduction device composed of a DOC and a DPF , or around the PM reduction device. By winding a wire (such as a wire) in a spiral shape and making the outer circumference corrugated with some protrusions, the material stored in the container and the fluid flowing in the pipe change in temperature, resulting in thermal heat. Cover with a flat plate that has a structure that can respond to various changes (expansion and contraction of containers and pipes), close both ends of the flat plate, and connect the PM reduction device (1) and the piping and both ends that connect the PM reduction device to the engine. By creating a vacuum structure in the closed space formed between the closed flat plate, the PM reduction device and the function that can prevent the temperature of the exhaust gas flowing through the exhaust pipe connecting the PM reduction device and the engine from dropping can be prevented. It is characterized by being prepared.

By forming the PM reduction device and the exhaust pipe into a double pipe structure in which the inside is evacuated, it is possible to minimize the release of heat to the outside air. This is an excellent method in terms of prevention of global warming, energy saving, and economy because the amount of heat supplied to the means for heating the exhaust gas can be reduced.

According to the third aspect of the present invention, at least one selected from an engine, a PM reduction device, and a pipe connecting the engine and the PM reduction device is a means for heating the exhaust gas flowing into the PM reduction device , or an electric heater. A catalyst such as ceria (cerium oxide, CeO ₂ ) is added to the fuel injected as a heat source for heating the exhaust gas flowing into the PM reduction device from the fuel injection device installed as one of the heating devices. The present invention is characterized by comprising an apparatus having a function of promoting the oxidative removal of soot by reacting this catalyst with the soot (C) contained in PM in the DPF.

By mixing additives such as cerium and iron in the fuel, the effect of reducing PM generated when the fuel burns, the effect of removing the oxidation of PM in the exhaust stroke and exhaust pipe after combustion, and the effect of removing PM from PM in DPF . Oxidation removal effect may be obtained. However, when added to the fuel before it is supplied to the engine, it welds to many sliding parts and welds to the fuel injection pump, fuel injection valve, cylinder liner and piston (piston ring), exhaust valve, and turbocharger turbine part. You will pass through the possible parts. When the additive enters the sliding surface, it may act as an abrasive, and when it is welded to the member, it may cause various harmful effects. Although the risk is reduced by making the additive into fine particles, the possibility remains.

The present invention has shown a method of adding effectively, efficiently and economically while minimizing the risk.
When an additive is added to the fuel tank, the additive is always consumed as the fuel is consumed, so it is necessary to record the maintenance cost, but the PM reduction device can effectively remove PM (exhaust temperature is 350). It is not necessary to do this under normal operating conditions above ° C. However, when the catalyst is below the activation temperature in the PM reduction device, this method (reducing PM in advance) is effective.
In the present invention, the catalyst that is effective in removing the oxidation of PM is consumed only when the catalyst is below the activation temperature in the PM reduction device, so that the ability is effectively and efficiently exhibited. It becomes possible to make it.
In addition, catalysts such as ceria (cerium oxide, CeO ₂ ) that have been mixed in the exhaust gas together with the heating fuel and reached the DPF are collected in the DPF together with the PM and act as an oxidation removal catalyst for the PM on the DPF. Become.

The invention according to claim 4 is a means for heating the exhaust gas flowing into the PM reduction device , or an electric heater, in at least one selected from the engine, the PM reduction device, and the piping connecting the engine and the PM reduction device. A catalyst such as ceria (cerium oxide, CeO ₂ ) is contained in the fuel injected as a heat source for heating the exhaust gas flowing into the PM reduction device (1) from the fuel injection device installed as one of the heating devices. Is characterized by reacting this catalyst with the soot (C) contained in PM in the DPF to promote the oxidative removal of soot.

By using the method described in the present invention, it becomes possible to add a catalyst such as ceria (cerium oxide, CeO ₂ ) effectively, efficiently and economically.

The invention described in claim 5, DOC and are within the PM reduction apparatus consists DOC and DPF, or prior to the DPF, by installing a distribution plate spaced plurality of holes around the flow of the exhaust gas Is characterized in that the temperature of the DOC and the DPF as a whole is made uniform and the function as a heat storage material is provided by dispersing the DOC and the DPF to the outer peripheral portion.

As described above, the amount of heat transfer between two substances is proportional to the contact area (heat transfer area), contact time and thermal conductivity. In the PM reduction device, when the exhaust gas temperature is equal to or lower than the activation temperature of the catalyst, the temperature of the exhaust gas by heating the exhaust gas by means for heating the exhaust gas flowing into the PM reduction device or by a heating device such as an electric heater. For example, the temperature is raised to 350 ° C. or higher. Since most of the outside air temperature at this time is less than 40 ° C., the temperature difference is about 300 ° C. Therefore, a large amount of heat is released from the outer circumference of the PM reduction device composed of the DOC and the DPF (cooled by the outside air). On the other hand, the temperature near the center of the PM reduction device is the highest because the DOC or DPF itself made of a material such as ceramic acts as a heat insulating material. From these facts, the temperature distribution in the cross section of the DOC or DPF is in a state where the temperature gradually decreases from the center toward the periphery. Further, since the DOC and the DPF are installed in series and parallel, once such a temperature distribution occurs in the DOC, it may be amplified in the DPF.
Even if the temperature of the exhaust gas is raised in such a temperature distribution, the greatest benefit is in the vicinity of the central part, and in the outer peripheral part, the temperature at which the catalyst is activated is not reached and PM is not oxidized and removed. Will remain deposited in the flow path, increasing the flow resistance and making it difficult for high-temperature exhaust gas to pass through (the temperature will also decrease as the flow velocity decreases), and PM accumulation will proceed.

In the present invention, by installing an exhaust gas dispersion plate having a plurality of holes around it in front of the DOC and / or DPF , turbulence is generated in the exhaust gas and the temperature distribution of the exhaust gas in the PM reduction device is made uniform. It has a structure that allows it to be used. As a result, the exhaust gas having a high temperature also flows in the outer peripheral portion, so that it is possible to effectively remove the oxidation of PM.
In addition, by using a substance with a large heat capacity for this dispersion plate or by increasing the volume of the dispersion plate to have a structure with a large heat capacity, a heat storage (heat retention) function is provided and the exhaust gas temperature drops. When passing through the high-temperature dispersion plate, the temperature is restored, and it is possible to have a function of maintaining the activation temperature of the catalyst.

Further, by incorporating an electric heater as a means for heating the exhaust gas flowing into the PM reduction device into the dispersion plate, effective and efficient heating of the exhaust gas becomes possible.

According to the invention of claim 6 , a dispersion plate having a plurality of holes is installed in front of the DOC and / or the DPF in the PM reduction device composed of the DOC and the DPF to prevent the flow of exhaust gas. By dispersing the DOC and / or DPF to the outer peripheral portion, the temperature of the entire DOC and / or DPF is made uniform and the function as a heat storage material is provided.

By using the method described in the present invention, the temperature distribution of the exhaust gas in the PM reduction device can be made uniform, and by giving the distributed plate a role of heat storage (heat retention), even if the temperature of the exhaust gas changes. , The PM reduction device can maintain the activation temperature of the catalyst.

In the invention according to claim 7 , a temperature sensor and a pressure sensor are installed in front of the DPF in the PM reduction device composed of the DOC and the DPF , and the signal is transmitted to the control device to set the temperature before the DPF. When the pressure exceeds the set value (for example, 3 kPa or more) in the state of the value (for example, 350 ° C.) or less, it is installed in at least one selected from the engine, the PM reduction device, and the pipe connecting the engine and the PM reduction device. , The exhaust gas is heated by a means for heating the exhaust gas flowing into the PM reduction device (1) , or by a heating device such as an electric heater, and when the pressure becomes less than the set value (for example, 2 kPa or less), the PM reduction device ( It is characterized by including a means for heating the exhaust gas flowing into 1) and a control device having a function of ending the heating of the exhaust gas by a heating device such as an electric heater .

Since the exhaust temperature of a diesel engine is proportional to its load factor, in general, in the normal load and high load range, the temperature becomes higher than the activation temperature of the catalyst supported on the DOC and DPF in the PM reduction device, and the PM continues. Effectively oxidatively removed. However, when the engine is stopped for a long time , the temperatures of the engine , piping, and PM reduction device become substantially equal to the outside air temperature, so that the exhaust temperature remains low for several minutes after the engine is started. Further, since the exhaust temperature does not rise to the active temperature of the catalyst even during low load operation, the PM discharged from the engine is accumulated in the DPF.
On the other hand, research on catalysts that activate at low temperatures is underway, and Document 3 describes the possibility of catalysts that activate at 300 ° C. or lower. Further, by using the system and method according to claims 1 to 8, it is possible to reduce the temperature drop of the exhaust gas discharged from the engine.
Based on such a situation, in the present invention, the DPF is effectively used at the time of start-up or low-load operation, where it is currently difficult to oxidize and remove PM (system and method using activation of catalyst). The purpose is to provide a system and method that can reproduce the. By using this system, effective DPF regeneration is possible in all operating areas.

In the invention according to claim 8 , a temperature sensor and a pressure sensor are installed in front of the DPF in the PM reduction device composed of the DOC and the DPF , and the signal is transmitted to the control device to set the temperature before the DPF. at a value (e.g., 350 ° C.) the following conditions, when equal to or greater than the pressure setpoint (e.g. 3kPa or more) engine, PM reduction apparatus is installed in at least one selected from the piping connecting the engine and the PM reduction apparatus Further, the exhaust gas is heated by a means for heating the exhaust gas flowing into the PM reduction device or by a heating device such as an electric heater, and when the pressure becomes less than the set value (for example, 2 kPa or less), the exhaust gas flows into the PM reduction device. It is characterized by terminating the heating of the exhaust gas by means for heating the exhaust gas or by a heating device such as an electric heater .

By using this method, effective DPF regeneration is possible in all operating regions.

The invention according to claim 9 has a pipe connecting a PM reduction device composed of a DOC and a DPF and an engine, and a pipe connecting the engine, a PM reduction device, and an engine and a PM reduction device with the PM reduction device having a heat insulating structure. At least one selected from the above is equipped with a means for heating the exhaust gas flowing into the PM reduction device and a heating device such as an electric heater , and the exhaust gas dispersion plate, the temperature sensor, and the pressure sensor are built in the PM reduction device. It is characterized by comprising means for heating the exhaust gas flowing into the PM reduction device by signals from the temperature sensor and the pressure sensor , or a control device capable of operating a heating device such as an electric heater .

The invention according to claim 10 has a pipe connecting a PM reduction device composed of a DOC and a DPF and an engine, and a pipe connecting the engine, a PM reduction device, and an engine and a PM reduction device with the PM reduction device having a heat insulating structure. At least one selected from the above is provided with a means for heating the exhaust gas flowing into the PM reduction device and a heating device such as an electric heater, and the PM reduction device is provided with an exhaust gas dispersion plate, a temperature sensor, and a pressure sensor. By controlling the means for heating the exhaust gas flowing into the PM reduction device by the signals from the temperature sensor and the pressure sensor and the operation of the heating device such as an electric heater , the PM collected in the DPF can be effectively collected. It is characterized by being able to remove oxidation.
By using this invention, the DPF can be continuously and efficiently regenerated even in automobiles such as fixed-route buses and garbage trucks, which are often operated with a low load in urban areas.

By using the present invention, PM (particulate matter) collected by a DPF (diesel particulate filter) installed in a diesel engine of an automobile or the like is oxidized and removed by the action of a catalyst in all operating regions. , DPF can be used continuously.

It shows the basic configuration of this system which concerns on embodiment of this invention. It is a flowchart which showed an example of the process at the time of effectively and efficiently oxidizing and removing PM collected in the DPF installed in the diesel engine which concerns on embodiment of this invention. It is a figure which showed the outline of the vacuum insulation apparatus which concerns on embodiment of this invention.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.
FIG. 1 shows the basic configuration of the present system according to the embodiment of the present invention. In this figure, when fuel burns in an engine, a high temperature of 1500 ° C. or higher is generated in the combustion chamber and PM is generated.
The exhaust gas containing PM flows into the PM reduction device through the exhaust pipe, and the exhaust gas diffuser plate installed inside makes the temperature uniform by creating a turbulent flow state. In the DOC installed in the PM reduction device, SOF, which is a component of PM, is oxidized and removed (to become CO ₂ ), and NO in the exhaust gas is oxidized to become NO ₂ . The temperature of the exhaust gas emitted from the DOC is made uniform by being in a turbulent state by the exhaust gas dispersion plate installed between the DOC and the DPF. Further, this exhaust gas dispersion plate is heated in a state where the exhaust gas temperature is high (stores heat), and when the exhaust gas temperature is low, it also performs a heat storage action of giving heat to the exhaust gas.

Soot ( C ) among the PM components contained in the exhaust gas is collected (collected) in the DPF. Since the DPF carries an oxidation catalyst such as Pt (platinum), the collected soot reacts with the oxidation catalyst and O ₂ and NO ₂ in the exhaust gas under certain temperature conditions (for example, 350 ° C. or higher). By doing so, it becomes CO ₂ (oxidation is removed).
However, when the engine is started or when the load is low, the temperature of the exhaust gas does not reach the activation temperature of the catalyst, so soot in the PM is deposited on the DPF, and if this is left unattended, the surface of the catalyst carried on the DPF Even if the temperature conditions are met, the exhaust gas and the catalyst cannot come into contact with each other.

Under such a situation (soot is deposited on the DPF), the flow path of the exhaust gas is narrowed, so that the pressure of the exhaust system rises. When this increase value exceeds a certain value (for example, 3 kPa), the signal of the pressure sensor is transmitted to the control device to activate a means for heating the exhaust gas flowing into the PM reduction device or a heating device such as an electric heater . As a result, the exhaust gas temperature rises to the activation temperature of the catalyst, and the soot accumulated on the DPF is oxidized and removed.
Here, since the exhaust gas pressure in the exhaust system has a characteristic that it increases as the load factor increases, a means for heating the exhaust gas flowing into the PM reduction device using only the signal of the pressure sensor , or an electric heater or the like. When the heating device is operated, the load factor rises and the exhaust gas temperature is high (it is not necessary to operate the means for heating the exhaust gas flowing into the PM reduction device or the heating device such as an electric heater ). Since heating is continued, it is not preferable in terms of both energy saving and economy. Therefore, the temperature of the exhaust gas is detected by the temperature sensor, and if this temperature is equal to or higher than a certain value (the temperature at which the catalyst is activated ), a means for heating the exhaust gas flowing into the PM reduction device (1), or electricity. It also has a system that stops the operation of heating devices such as heaters .
As described above, by using this system, the DPF can be effectively, efficiently and economically regenerated in all operating conditions including the start-up time and the low load time.

FIG. 2 is a flowchart showing an example of a process for effectively and efficiently oxidizing and removing PM collected in the DPF installed in the diesel engine according to the embodiment of the present invention.
In S1, when soot is deposited on the DPF, the flow path of the exhaust gas is narrowed, and when the amount of exhaust gas is constant, the pressure in the exhaust system rises and the pressure in the PM reduction device also rises.
In S2, the temperature sensor and the pressure sensor installed in the PM reduction device detect the temperature and pressure in the PM reduction device and transmit the temperature and pressure to the control device.
In S3, when the temperature in the PM reduction device is equal to or lower than the temperature at which the catalyst in the device is activated (for example, 350 ° C. or lower) and the pressure rises above the set value, the control device provides means for heating the exhaust gas. , Or activate a heating device such as an electric heater .
In S4, the exhaust gas flowing into the PM reduction device (1) is heated by means for heating the exhaust gas or a heating device such as an electric heater .
In S5, the catalyst supported on the DPF is activated by heating the exhaust gas to oxidize and remove soot, so that the exhaust gas flowing into the PM reduction device when the pressure in the PM reduction device becomes equal to or less than a set value (for example, 2 kPa or less). The heating of the exhaust gas by the means for heating the exhaust gas and the heating device such as an electric heater is completed.

FIG. 3 is a diagram showing an outline of the vacuum insulation device according to the embodiment of the present invention.
In this figure, a substance having a circular cross-sectional shape and a length (cylindrical shape, wire shape, etc.) is spirally wound around the exhaust pipe and the PM reduction device, and the outer circumference thereof is partially provided with protrusions. By covering with a corrugated flat plate, closing both ends of the flat plate, and creating a vacuum structure in the sealed space formed between the exhaust pipe and PM reduction device and the flat plate with both ends closed, the exhaust pipe and PM reduction It is possible to prevent the temperature of the exhaust gas flowing through the device from dropping.

The present invention is applicable when the diesel particulate filter is effectively, efficiently and economically regenerated.

1. 1. PM reduction device 2. Engine 3. Exhaust pipe 4. 4. Means for heating the exhaust gas and heating devices such as electric heaters . Exhaust gas dispersion plate 6. Temperature sensor 7. Pressure sensor 8. Control device

Claims (8)

By oxidizing and removing PM (particulate matter) collected by the diesel particulate filter installed in a diesel engine of an automobile or the like by the action of a catalyst, the diesel particulate filter can be used continuously. As part of the system, the outside air from around the PM reduction device (1) and the engine (2), which are composed of a diesel oxidation catalyst and a diesel particulate filter, and the piping (3), or the PM reduction device (1). In order to prevent heat dissipation to the diesel engine, the PM reduction device (1) and the engine (2) are connected to a substance filled with air, which has a tubular cross-sectional shape and has a better thermal conductivity characteristic than a solid engine. It is built into the PM reduction device (1) by spirally winding it around the piping (3) and / or the PM reduction device (1) to form a waveform, and making the outer circumference a waveform with a protrusion. Cover with a flat plate having a structure that can respond to thermal changes (expansion / contraction of containers and pipes) due to changes in the temperature of the fluid flowing in the diesel engine and piping (3), and close both ends of the flat plate. By creating a vacuum in the sealed space formed between the PM reduction device (1), the pipe (3) connecting the PM reduction device (1) and the engine (2), and the flat plate with both ends closed. , A diesel particulate filter characterized by having a function capable of preventing a temperature drop of the exhaust gas flowing through the PM reduction device (1) and the pipe (3) connecting the PM reduction device (1) and the engine (2). Collection filter regeneration system. By oxidizing and removing PM (particulate matter) collected by the diesel particulate filter installed in a diesel engine of an automobile or the like by the action of a catalyst, the diesel particulate filter can be used continuously. As part of the method, the outside air from the pipe (3) connecting the PM reduction device (1) and the engine (2) composed of the diesel oxidation catalyst and the diesel particulate filter, or the PM reduction device (1). In order to prevent heat dissipation to the diesel engine, the PM reduction device (1) and the engine (2) are connected to a substance filled with air, which has a tubular cross-sectional shape and has a better thermal conductivity characteristic than a solid engine. It is built into the PM reduction device (1) by spirally winding it around the piping (3) and / or the PM reduction device (1) to form a waveform, and making the outer circumference a waveform with a protrusion. Cover with a flat plate having a structure that can respond to thermal changes (expansion / contraction of containers and pipes) due to changes in the temperature of the fluid flowing in the diesel engine and piping (3), and close both ends of the flat plate. By creating a vacuum in the sealed space formed between the PM reduction device (1) and the piping (3) connecting the PM reduction device (1) and the engine (2) and the flat plate with both ends closed, the air is created. Diesel particulate filter characterized by having a function capable of preventing a temperature drop of the exhaust gas flowing through the PM reduction device (1) and the pipe (3) connecting the PM reduction device (1) and the engine (2). How to play the filter. By oxidizing and removing PM (particulate matter) collected by the diesel particulate filter installed in the diesel engine of automobiles by the action of a catalyst, the diesel particulate filter can be used continuously. As part of the system, the exhaust gas discharged from the engine and having a temperature ( for example, 350 ° C.) higher than the temperature at which the catalyst carried on the diesel particulate filter is activated is cooled by the outside air (for example, 40 ° C.) . Even if the exhaust gas temperature reaches the activation temperature of the catalyst, if the outer periphery of the diesel particulate filter is lower than that temperature, soot cannot be oxidized and removed, soot accumulates, and when soot accumulates, the flow path narrows. In order to prevent repeating a vicious cycle in which the temperature of the outer peripheral portion further decreases as a result of poor flow, the PM reduction device (1) and the piping (3) connecting the PM reduction device (1) and the engine (2). In addition to having a function that can prevent the temperature of the exhaust gas flowing in the air from dropping, a dispersion plate with multiple holes is installed directly upstream of the diesel particulate filter to collect the exhaust gas flow. The regeneration system for the diesel particulate filter according to claim 1, further comprising a function of equalizing the temperature of the entire diesel particulate filter by dispersing it up to the outer peripheral portion of the filter. By oxidizing and removing PM (particulate matter) collected by the diesel particulate filter installed in the diesel engine of automobiles by the action of a catalyst, the diesel particulate filter can be used continuously. As part of the method, the exhaust gas discharged from the engine and having a temperature ( for example, 350 ° C.) higher than the temperature at which the catalyst carried on the diesel particulate filter is activated is cooled by the outside air (for example, 40 ° C.) . Even if the exhaust gas temperature reaches the activation temperature of the catalyst, if the outer periphery of the diesel particulate filter is lower than that, the soot cannot be oxidized and removed, soot accumulates, and when soot accumulates, the flow path narrows. In order to prevent repeating a vicious cycle in which the temperature of the outer peripheral portion further decreases as a result of deterioration, the PM reduction device (1) and the piping (3) connecting the PM reduction device (1) and the engine (2) are installed. In addition to providing a method that can prevent the temperature of the flowing exhaust gas from dropping, a dispersion plate with multiple holes is installed immediately upstream of the diesel particulate filter in the PM reduction device (1). The diesel particulate filter according to claim 2, wherein the temperature of the entire diesel particulate filter is made uniform by using a method of dispersing the exhaust gas flow to the outer peripheral portion of the diesel particulate filter. How to play the particulate filter. A substance having a large heat capacity is used as the dispersion plate (6) having a plurality of holes around it, which is installed directly upstream of the diesel particulate filter in the PM reduction device (1), or the dispersion plate. By making the structure with a large heat capacity by increasing the volume etc., it has a heat storage (heat retention) function, and even when the exhaust gas temperature drops, the temperature recovers when passing through the high temperature dispersion plate, and the catalyst The regeneration system for a diesel particulate filter according to claim 1 or 3, further comprising a function of being able to have a function of holding an activation temperature. A substance having a large heat capacity is used as the dispersion plate (6) having a plurality of holes around it, which is installed directly upstream of the diesel particulate filter in the PM reduction device (1), or the dispersion plate. By using a method of increasing the heat capacity by increasing the volume, the heat storage (heat retention) function is provided, and even when the exhaust gas temperature drops, the temperature recovers when passing through the high-temperature dispersion plate. The method for regenerating a diesel particulate filter according to claim 2 or 4, wherein the activation temperature of the catalyst can be maintained. Electricity as a means of heating the exhaust gas flowing into the PM reduction device on the dispersion plate (6) with a plurality of holes around it, which is installed directly upstream of the diesel particulate filter in the PM reduction device (1). The diesel particulate filter according to claim 1, claim 3 or claim 5, characterized in that it has a function of enabling effective and efficient heating of exhaust gas by incorporating a heater. Playback system. Electricity as a means of heating the exhaust gas flowing into the PM reduction device on the dispersion plate (6) with a plurality of holes around it, which is installed directly upstream of the diesel particulate filter in the PM reduction device (1). The diesel particulate filter according to claim 2, claim 4 or claim 6, characterized in that effective and efficient heating of exhaust gas is possible by using the method of incorporating a heater. Playback method.

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