JP2004257323A - Exhaust system control system of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique in which regeneration treatment of an exhaust emission control means can be efficiently performed at low fuel consumption by a simple constitution, temperatures of the emission control means and a heat recovery apparatus can be accurately controlled, a best emission control characteristic is provided, and optimum recycle of exhaust gas heat is possible. <P>SOLUTION: An exhaust temperature sensor 9 is arranged between the emission control means 8 and 16 and a heat recovery apparatus 25. In response to the output signal, a spraying burner 14 that is disposed on the upstream side of these and has an air assist fuel supply device 14a and an air pump 14b is combusted to increase the exhaust temperature. The exhaust temperature is decreased by supplying only air to the exhaust gas by the air pump 14b, and a reducing agent is supplied to the exhaust gas by combusting the burner at a rich air-fuel ratio or supplying only fuel to the exhaust gas. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an exhaust system control system for an internal combustion engine that controls the exhaust of the internal combustion engine and exhaust system components.
[0002]
[Prior art]
In recent years, internal combustion engines mounted on automobiles have been required to reduce harmful gas components in exhaust gas for reasons such as environmental protection. In response to such demands, an exhaust system of an internal combustion engine is provided with a NOx catalyst for reducing and purifying NOx in exhaust gas discharged from the engine under predetermined conditions, and a particulate matter such as soot contained in the exhaust gas (Particulate). (Matter) An exhaust gas purification device such as a particulate filter for removing PM is provided.
[0003]
The NOx catalyst stores NOx in the exhaust gas when the air-fuel ratio of the exhaust gas flowing into the catalyst is lean, releases the stored NOx when the oxygen concentration in the exhaust gas decreases, and releases the released NOx. NOx catalyst which reacts with a reducing agent such as HC or carbon monoxide (CO) to reduce and purify it to N2 or the like, or the state of exhaust gas flowing into the catalyst is an oxygen excess state and a state where HC exists. A selective reduction type NOx catalyst or the like which sometimes reduces NOx to nitrogen (N2), water (H2O), carbon dioxide (CO2) or the like using hydrocarbon (HC) as a reducing agent is known.
[0004]
On the other hand, the particulate filter is formed of a porous ceramic or the like, captures PM in the exhaust gas when the exhaust gas passes through the holes, makes the inflow exhaust gas lean, and has a high exhaust gas temperature (for example, 600 ° C. or more). ), A catalyst that burns the trapped PM or a catalyst is carried on the surface of the exhaust flow path in the particulate filter, and a reducing agent such as HC reacts with oxygen on the catalyst, and the reaction that occurs at that time What burns captured PM by heat is known.
[0005]
Some exhaust systems of internal combustion engines include a heat recovery device in an exhaust passage that recovers heat of high-temperature exhaust gas discharged from the internal combustion engine and sends the recovered heat to a vehicle interior heater.
[0006]
The heat recovery unit and the vehicle interior heater use a part of the cooling water circuit of the internal combustion engine as a common component, and the heat of exhaust gas discharged from the internal combustion engine is recovered by circulating cooling water and Carried. Therefore, the exhaust heat of the internal combustion engine can be used as a heating heat source.
[0007]
However, if the heat for heating the passenger compartment is to be obtained only by the heat of the exhaust gas from the internal combustion engine, the amount of heat recovered by the heat recovery unit is reduced because the exhaust gas temperature is low when the internal combustion engine is operating under low or medium load. As a result, in some cases, rapid heating by the cabin heater cannot be obtained.
[0008]
Therefore, in order to solve the above-mentioned problem, there is an engine equipped with a spray combustor for supplying a reducing agent to exhaust gas or heating exhaust gas, separately from an internal combustion engine as a power source.
[0009]
For example, a spray combustor is provided on the exhaust passage upstream side of the exhaust purification device, and when the spray combustor is in an operating state, the gas combusted by the spray combustor is introduced as an additive into the exhaust system upstream of the exhaust purification device. If the spray combustor is in a non-operating state, the fuel is supplied to the spray combustor to vaporize the fuel, and the vaporized fuel is introduced as a reducing agent into an exhaust system upstream of the exhaust gas purifying means, and NOx or PM Conventional techniques for reducing / treating have been proposed. (For example, refer to Patent Document 1).
[0010]
In addition, using the heat of the combustion gas from the spray combustor, the PM captured by the particulate filter is burned to make it a harmless component, and furthermore, technology for preventing clogging of the particulate filter and the heat of the combustion gas from the spray combustor are used. There is disclosed a technique in which the amount of heat recovered by a heat recovery unit is increased, and air for heating the vehicle interior heated by the heat is blown into the vehicle interior through an air conditioner to be used for heating the vehicle interior. (For example, see Patent Documents 2 and 3.)
[0011]
However, in the above-described prior art spray combustor, when heating the exhaust gas, since the spray combustor is controlled by detecting the indoor temperature of the vehicle, the actual temperature of the exhaust purification device or the heat exchanger is controlled. Was not appropriate in some cases.
[0012]
[Patent Document 1]
JP 2000-186545 A
[Patent Document 2]
JP-A-59-29718
[Patent Document 3]
JP-A-11-70813
[Patent Document 4]
JP 2000-186538 A
[Patent Document 5]
JP 2000-186541 A
[0013]
[Problems to be solved by the invention]
The present invention has been made in view of the above prior art, and has as its object to provide a technology capable of accurately controlling the temperature of exhaust purification means and heat recovery means in an exhaust system of an internal combustion engine. It is to be.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an exhaust system for an internal combustion engine, wherein an exhaust temperature acquisition unit is disposed between the exhaust purification unit and the heat exchange unit, and the exhaust temperature acquisition unit is configured to operate according to the exhaust temperature acquired by the exhaust temperature acquisition unit. A spray combustor arranged upstream of the exhaust purification means and the heat recovery means, which has an air-assisted fuel supply device and an air pump, for example, by raising the exhaust gas temperature by burning, Controls such as lowering the exhaust temperature by supplying only air to the exhaust by an air pump, or supplying a reducing agent to the exhaust by burning at a rich air-fuel ratio or supplying only fuel to the exhaust. is there.
[0015]
According to the present invention, there is provided an exhaust purification device disposed in an exhaust passage of the internal combustion engine for purifying exhaust gas of the internal combustion engine, and an exhaust gas disposed in series with the exhaust purification device in the exhaust passage. Heat recovery means for recovering heat, exhaust temperature adjustment means for adjusting the temperature of the exhaust gas flowing into the exhaust gas purification means and the heat recovery means, and temperature of the exhaust gas between the exhaust gas purification means and the heat recovery means And an exhaust temperature acquiring means for acquiring the exhaust gas temperature.
[0016]
That is, by arranging the exhaust gas temperature acquisition means between the exhaust gas purification means arranged in the exhaust system of the internal combustion engine and the heat recovery means arranged in series with the exhaust gas purification means, one exhaust gas temperature acquisition means Since the temperatures of both the exhaust gas discharged from the exhaust gas purifying means and the exhaust gas flowing into the heat recovery means can be obtained, the temperature of the exhaust gas purifying means and the heat recovery means can be accurately obtained from the obtained signal. it can.
[0017]
Further, the apparatus further includes a temperature control unit that controls the exhaust gas temperature adjustment unit based on the temperature of the exhaust gas acquired by the exhaust gas temperature acquisition unit.
[0018]
That is, since the exhaust gas temperature adjusting device is controlled based on the temperature of the exhaust gas corresponding to the accurate temperatures of the exhaust gas purifying device and the heat recovery device, the temperatures of the exhaust gas purification device and the heat recovery device can be accurately controlled.
[0019]
Therefore, it is possible to accurately control the temperatures of the exhaust gas purifying means and the heat recovery means in the exhaust system of the internal combustion engine with a low-cost and simple configuration, so that the temperatures of the heat recovery means and the exhaust gas purifying means do not become appropriate. As a result, the best emission characteristics and the optimal reuse of exhaust heat can be realized.
[0020]
Further, the exhaust gas temperature adjusting means includes an air introduction passage for introducing air into the exhaust passage, an air pump for sending air in the air introduction passage to the exhaust passage side, and a fuel supply to the sent air. And a spray combustor disposed upstream of the exhaust purification means in the exhaust passage.
[0021]
That is, in the reduction treatment of the exhaust gas purifying means, the fuel can be atomized by colliding and mixing the air and the fuel delivered by the air pump by the air-assisted fuel supply device, so that the fuel can be atomized. When the fuel as the reducing agent is supplied, the fuel does not adhere to the wall of the exhaust passage, and the reduction process can be performed without deteriorating the fuel efficiency. Also, when burning at a rich air-fuel ratio, since the fuel is atomized, non-uniformity of the air-fuel ratio is less likely to occur, soot is less generated, and CO and H2 having strong reducing power can be efficiently removed at any timing. Because it can be produced well, fuel efficiency does not deteriorate. Further, as a result, the capacity of the catalyst can be reduced, and the amount of noble metal in the catalyst can be reduced, which leads to cost reduction.
[0022]
Further, when the exhaust gas temperature obtained by the exhaust gas temperature obtaining device is higher than a predetermined temperature, the temperature control unit sets the fuel supply amount by the air assist fuel supply device to zero, and the air introduction by the air pump. The exhaust gas temperature control means is controlled to supply air in a road to exhaust gas of the internal combustion engine.
[0023]
That is, when the exhaust gas temperature obtained by the exhaust gas temperature obtaining means is higher than the predetermined temperature, the temperature of the exhaust gas purifying means or the heat recovery means may be excessively high. The fuel supply amount by the air-assisted fuel supply device of the spray combustor is set to zero, and the low-temperature air introduced from outside the exhaust passage is directly supplied to the exhaust by the air pump of the spray combustor, and the exhaust purification means or the heat recovery means Is to lower the temperature.
[0024]
As a result, it is possible to control the exhaust purification means or the heat recovery means so as not to be excessively hot regardless of the exhaust gas temperature discharged from the internal combustion engine with a low cost and a simple configuration without adding a new device or the like. It becomes possible to do.
[0025]
Further, the exhaust gas purifying means has an exhaust gas purifying catalyst whose purification performance is restored by the reduction processing, and when executing the reduction processing, the temperature control means controls the combustion of the spray combustor to a rich air-fuel ratio. It is characterized by doing.
[0026]
That is, when it becomes necessary to reduce the exhaust purification catalyst, the spray combustor is burned at a rich air-fuel ratio to control the amount of combustion, thereby raising the exhaust gas temperature and simultaneously increasing the unburned fuel as a reducing agent. Can be supplied to the exhaust purification catalyst.
[0027]
Therefore, the reduction process for the exhaust gas purifying means can be performed at an arbitrary timing without affecting the operation state of the internal combustion engine. Also, by burning at a rich air-fuel ratio instead of simply supplying fuel as a reducing agent, the unburned fuel is exposed to high-temperature combustion heat in the spray combustor, and is converted into a relatively small molecular size. It is decomposed and contains HC with a high NOx purification rate. This makes it possible to more efficiently perform the reduction process of the exhaust gas purification unit.
[0028]
In addition, since the above-described spray combustor has the air assist fuel supply device, in particular, it is difficult for the air-fuel ratio to be uneven, the generation of soot can be suppressed, and the reducing components such as HC and CO are efficiently generated. be able to.
[0029]
Further, the air conditioner further includes a bypass unit that causes the exhaust gas of the internal combustion engine to bypass the heat recovery unit.
[0030]
That is, for example, when the temperature of the heat recovery unit becomes excessively high due to the high-temperature exhaust gas, the heat recovery unit is detoured to the high-temperature exhaust gas by operating the bypass unit.
[0031]
Thus, it is possible to control the temperature of the heat recovery means regardless of the temperature of the exhaust gas depending on the operation state of the internal combustion engine. Further, for example, when the exhaust gas purifying means includes a particulate filter and the regeneration control is performed, the temperature of the exhaust gas purifying means is increased by increasing the temperature of the exhaust gas. By operating the bypass means, the temperatures of the exhaust purification means and the heat recovery means can be controlled independently.
[0032]
Further, the apparatus further comprises bypass control means for controlling the operation of the bypass means, wherein the bypass control means is configured such that the temperature of the exhaust gas acquired by the exhaust gas temperature acquisition means is equal to or higher than a predetermined temperature, and the flow rate of the exhaust gas of the internal combustion engine is Operating the bypass means when is equal to or higher than a predetermined flow rate.
[0033]
That is, not only the temperature of the exhaust gas but also the flow rate of the exhaust gas is obtained, and as a result, the bypass unit is operated when the amount of heat of the exhaust gas recovered by the heat recovery unit is equal to or more than a predetermined value. It is possible to more accurately cope with an increase in the temperature of the means and an increase in the temperature of the engine cooling water. Then, excessive heat recovery can be prevented, the load on the radiator can be reduced, and the occurrence of heat damage to the cooling system can be prevented.
[0034]
Further, the exhaust gas purification means has an exhaust gas purification catalyst and a particulate filter whose purification performance is restored by a reduction process, and the exhaust gas passage is provided in the exhaust gas passage from an upstream side of the exhaust gas passage. -The filter and the heat recovery means are arranged in this order.
[0035]
In other words, when arranged in the above order from the upstream side of the exhaust passage, by supplying the reducing agent from the spray combustor, the reducing agent can be burned by the exhaust purification catalyst upstream of the particulate filter. Therefore, high-temperature exhaust gas containing no combustibles and having a uniform and stable temperature can be supplied to the particulate filter and the heat recovery means.
[0036]
As a result, the temperature of the particulate filter can be increased uniformly, and it is possible to prevent the fuel and PM from burning excessively due to burning of the particulate filter. At the same time, stable heat recovery can be performed.
[0037]
In addition, the temperature of the exhaust gas can be increased by the combustion of the fuel in the exhaust purification catalyst without supplying the fuel as a reducing agent from the fuel supply means of the spray combustor, and without burning the spray combustor. The frequency of combustion in the combustor can be reduced, and reliability and overall fuel efficiency can be improved.
[0038]
Note that the means for solving the above-described problems can be implemented in combination as much as possible.
[0039]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto unless otherwise specified. Absent.
[0040]
(First Embodiment)
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which the present invention is applied. In FIG. 1, an internal combustion engine 1 is a four-cylinder water-cooled diesel engine. An intake branch pipe 2 is connected to the internal combustion engine 1, and each branch pipe of the intake branch pipe 2 communicates with a combustion chamber of each cylinder via an intake port (not shown).
[0041]
The intake branch pipe 2 is connected to an intake pipe 3, and the intake pipe 3 is connected to an air cleaner box 4 containing an air filter. In the intake system configured as described above, fresh air flowing into the air cleaner box 4 is removed by an air filter to remove dust and dirt, and then guided to the intake branch pipe 2 through the intake pipe 3. The fuel is distributed to the combustion chamber of each cylinder through each branch pipe.
[0042]
The internal combustion engine 1 is provided with one fuel injection valve 10 for each cylinder. Each fuel injection valve 10 is mounted so that its injection hole faces the combustion chamber of each cylinder, so that fuel can be directly injected into the combustion chamber. The fuel injection valve 10 communicates with a common rail 12 via a fuel distribution pipe 11, and the common rail 12 communicates with a fuel pump (not shown) via a fuel passage 13. In the fuel injection system configured as described above, the fuel discharged from the fuel pump is accumulated at a predetermined pressure by the common rail 12, and the accumulated fuel is applied to the fuel injection valve 10 through the fuel distribution pipe 11. Then, fuel is injected from the fuel injection valve 10 into the combustion chamber.
[0043]
On the other hand, an exhaust branch pipe 6 is connected to the internal combustion engine 1, and each branch pipe of the exhaust branch pipe 6 communicates with a combustion chamber of each cylinder via an exhaust port (not shown).
[0044]
The exhaust branch pipe 6 is connected to an exhaust passage 7, and the exhaust passage 7 is provided with a spray combustor 14, which is an exhaust gas temperature adjusting means in the present embodiment.
[0045]
FIG. 2 is a diagram showing a schematic configuration of the spray combustor 14 in the present embodiment.
[0046]
2, the spray combustor 14 in the present embodiment includes an air-assisted fuel supply device 14a, an air pump 14b, and an ignition device 35. The air-assisted fuel supply device 14a is a fuel supply device that has an air introduction hole at a tip end to collide and mix fuel and air to atomize the fuel.
[0047]
A fuel introduction passage 20 is connected to the air assist fuel supply device 14a, and the fuel introduction passage 20 supplies the fuel sent by the fuel pump to the air assist fuel supply device. This fuel introduction passage 20 is connected to a fuel passage 13 that transports fuel to the common rail 12 as shown in FIG. This makes it possible to supply a part of the fuel flowing through the fuel passage 13 to the spray combustor 14.
[0048]
Further, the air pump 14b guides the air purified by the air filter of the air cleaner 4 from the intake pipe 3 into the intake passage 15 as an air introduction passage, and further through the air assist fuel supply device 14a. This is for sending to the side.
[0049]
The ignition device 35 ignites the fuel supplied from the air assist fuel supply device 14a and causes combustion by a reaction between the fuel and air sent from the air pump 14b.
[0050]
FIG. 3 is a detailed sectional view of the air-assisted fuel supply device 14 a provided in the spray combustor 14. As shown in the figure, an adapter 50 is attached to the distal end. The adapter 50 has two fuel passages 50a and 50b extending from the two nozzles of the air-assisted fuel supply device 14a to the front end face of the adapter in the fuel injection direction, and the fuel injection of the fuel passages 50a and 50b from the side of the adapter. At least two communication passages 50c and 50d communicating with the vicinity of the valve nozzle are formed.
[0051]
An air assist chamber 51 is provided around the side of the adapter at the mounting portion of the fuel injection valve 52, and the assist air provided therein is supplied to each of the fuel passages 50a and 50b through the communication passages 50c and 50d. By colliding and mixing with the fuel injected by the injection valve 52, the fuel is finely atomized and released from the front end face of the adapter.
[0052]
Next, returning to FIG. 1, an occlusion reduction type NOx catalyst 8 and a particulate filter 16 as exhaust gas purifying means are provided in the exhaust passage 7 downstream of the spray combustor 14.
[0053]
In the present embodiment, the exhaust purification means of the type in which the NOx storage reduction catalyst 8 and the particulate filter 16 are housed in the same case is used. Needless to say, the filter may be arranged on the filter 7 or a particulate filter or the like carrying an oxidation catalyst may be used.
[0054]
When the air-fuel ratio of the exhaust gas flowing into the NOx storage reduction catalyst 8 is in a lean atmosphere, the NOx storage reduction catalyst 8 absorbs NOx in the exhaust gas, and the air-fuel ratio of the inflowing exhaust gas is a rich atmosphere. In addition, when a reducing agent is present, the catalyst is a catalyst that reduces the absorbed NOx to nitrogen while releasing it.
[0055]
The storage reduction type NOx catalyst 8 uses alumina as a carrier, and on the carrier, selects from alkaline earth metals such as potassium (K) and sodium (Na) and rare earths such as lanthanum (La) or yttrium (Y). And a noble metal such as platinum (Pt).
[0056]
Further, a heat recovery unit 25 as a heat recovery unit is disposed downstream of the NOx storage reduction catalyst 8 as the exhaust gas purification unit and the particulate filter 16. The heat recovery unit 25 includes a cooling water introduction passage 18 that guides the cooling water of the internal combustion engine 1 to the heat recovery unit 25, and a cooling water that guides the cooling water heated by the heat recovered in the heat recovery unit 25 to the internal combustion engine 1. The discharge passage 19 is connected.
[0057]
The heat of the exhaust gas is recovered by the heat recovery device 25, and the heated cooling water passes through the cooling water discharge passage 19 and returns to the internal combustion engine 1, and passes through the refrigerant heater 27.
[0058]
A heater 29 is connected to the refrigerant heater 27 via a refrigerant passage 28. The coolant is heated by the heat recovery unit 25 to exchange heat with the refrigerant heater 27 to heat the refrigerant, and the heater 29 heats the vehicle interior.
[0059]
An exhaust gas temperature sensor 9 as an exhaust gas temperature acquiring device is provided between the heat exchanger 25 and the storage reduction type NOx catalyst 8 and the particulate filter 16 as exhaust gas purifying devices. Further, a muffler 26 is arranged downstream of the heat exchanger 25.
[0060]
In the exhaust system configured as described above, the exhaust gas composed of the air-fuel mixture burned in the combustion chamber of each cylinder is guided to the exhaust passage 7 through each branch pipe of the exhaust branch pipe 6, and first, the spray combustor 14 pass.
[0061]
The spray combustor 14 is supplied with air introduced by the air pump 14b through the fuel introduction passage 20 when the regeneration control of the particulate filter is performed or when the amount of heat recovered in the heat recovery unit 25 is insufficient. In addition to burning the supplied fuel to raise the temperature of the exhaust gas, as described later, the fuel is introduced by the air pump 14b to supply fuel as a reducing agent into the exhaust gas or to lower the temperature of the exhaust gas. An operation such as supplying only the exhausted air to the exhaust is performed.
[0062]
Next, the exhaust gas flows into the NOx storage reduction catalyst 8. At this time, if the air-fuel ratio of the exhaust gas flowing into the NOx storage reduction catalyst 8 is in a lean atmosphere, nitrogen oxides (NOx) in the exhaust gas of the NOx storage reduction catalyst 8 are converted into nitrate ions (NOx). ^3- ) Is absorbed in the form. Further, when passing through the subsequent particulate filter 16, particulate matter PM such as soot contained in the exhaust gas is removed.
[0063]
Then, when the exhaust gas passes through the heat recovery unit 25, heat in the exhaust gas is recovered and used as a heat amount for heating the interior of the vehicle. Thereafter, the exhaust gas passes through the muffler 26 and is discharged outside the vehicle.
[0064]
Further, the internal combustion engine 1 is provided with an electronic control unit (ECU: Electronic Control Unit) 21 for engine control. The ECU 21 includes a CPU, a ROM, a RAM, an input interface circuit, an output interface circuit, and the like, which are mutually connected by a bidirectional bus. Various sensors are connected to the input interface circuit via electric wiring. I have.
[0065]
The various sensors described above include an air flow meter 5 attached to the intake pipe 3 and an exhaust gas attached to the exhaust passage 7 between the storage reduction NOx catalyst 8 and the particulate filter 16 and the heat exchanger 25 described above. Examples include a temperature sensor 9, a crank position sensor 22 and a water temperature sensor 23 attached to the internal combustion engine 1, an accelerator position sensor 24 attached to an accelerator pedal (not shown) or an accelerator lever that operates in conjunction with the accelerator pedal, and the like. it can.
[0066]
The air flow meter 5 is a sensor that outputs an electric signal corresponding to the mass of intake air flowing through the intake pipe 3. The exhaust gas temperature sensor 9 is a sensor that outputs an electric signal corresponding to the temperature of exhaust gas discharged from the storage reduction type NOx catalyst 8 and the particulate filter 16 and flowing into the heat recovery unit 25. The crank position sensor 22 is a sensor that outputs a pulse signal each time a crankshaft (not shown) of the internal combustion engine 1 rotates by a predetermined angle. The water temperature sensor 23 is a sensor that outputs an electric signal corresponding to the temperature of the cooling water flowing through the water jacket of the internal combustion engine 1. The accelerator position sensor 24 is a sensor that outputs an electric signal corresponding to the operation amount of the accelerator pedal.
[0067]
The ECU 21 determines the operating state of the internal combustion engine 1 based on the output signal values of the various sensors as described above, and based on the determination result, the control signal value for the fuel injection valve 10, the spray combustor 14, or the air pump 14b. Is calculated. The various control signal values thus calculated are output from the output interface circuit to the fuel injection valve 10, the spray combustor 14, or the air pump 14b via an electric line.
[0068]
Among the above, the most significant features of the present embodiment are that the exhaust gas temperature sensor 9 as the exhaust gas temperature acquisition means, the NOx storage reduction catalyst 8 and the particulate filter 16 as the exhaust gas purification means, and the heat recovery means as the heat recovery means That the spray combustor 14 as an exhaust gas temperature control means is provided with an air-assisted fuel supply device 14a, and that the NOx storage-reduction type is provided in the exhaust passage 7 from the upstream side. The catalyst 8, the particulate filter 16, and the heat recovery unit 25 are arranged in this order.
[0069]
Next, control of the spray combustor 14, the storage reduction type NOx catalyst 8, the particulate filter 16, and the heat exchanger 25, which are components of the exhaust system of the internal combustion engine in the case of the above configuration, particularly, An example of control for increasing the temperature of these components and the exhaust gas will be briefly described.
[0070]
Here, a case where the temperature of the particulate filter 16 is increased will be described. The control for increasing the temperature of the particulate filter 16 is performed, for example, in the following case.
[0071]
As described above, the particulate filter 16 captures PM such as soot in the exhaust gas. However, the filter may be clogged by the captured PM as it is. The filter is regenerated by raising the temperature of the filter 16 and burning the PM captured by the filter.
[0072]
At this time, if the temperature of the particulate filter 16 is too low, PM cannot be sufficiently burned and removed. Conversely, if the temperature is too high, the temperature of the filter itself becomes excessively high. Therefore, accurate temperature control is required.
[0073]
In the exhaust system control system according to the present embodiment, as a method of increasing the temperature of exhaust gas for the purpose of regenerating the particulate filter 16, only the air assist fuel supply device 14a and the air pump 14b are operated to store fuel. A method of increasing the temperature of exhaust gas flowing into the particulate filter 16 by burning with the reduced NOx catalyst 8 is adopted. At this time, the supply amount of fuel is determined based on the exhaust gas temperature signal from the exhaust gas temperature sensor 9.
[0074]
In the present embodiment, the temperature control means includes the ECU 21 that generates a control signal for the air-assisted fuel supply device 14a when a signal from the exhaust gas temperature sensor 9 is input.
[0075]
As described above, the exhaust system control system for the internal combustion engine according to the present embodiment includes the spray combustor 14 having the air-assisted fuel supply device 14a as the exhaust gas temperature control means. When only the fuel is supplied to the exhaust gas, the fuel is atomized and hardly adheres to the wall surface of the exhaust passage 7, so that the fuel efficiency can be improved when the fuel is supplied to increase the exhaust gas temperature.
[0076]
Note that the spray combustor 14 as the exhaust temperature adjusting means in the present embodiment is provided with an internal combustion engine that controls the exhaust temperature adjusting means based on other than the temperature of the exhaust gas acquired by the exhaust temperature sensor 9 as the exhaust temperature acquiring means. The present invention is also applicable to an exhaust system control system.
[0077]
Further, when the above-described method for increasing the temperature of exhaust gas is used in the configuration of the exhaust system according to the present embodiment, almost no fuel reaches downstream of the NOx storage reduction catalyst 8, so that uniform and high-temperature exhaust gas containing no combustibles is used. Can be supplied to the particulate filter 16, and the temperature of the particulate filter 16 can be increased uniformly. Further, it is possible to prevent the fuel and the deposit from burning in the particulate filter 16 and prevent the particulate filter 16 itself from becoming excessively hot.
[0078]
Further, in this method, the temperature of the exhaust gas flowing into the particulate filter 16 can be increased by burning the fuel in the NOx storage reduction catalyst 8 without igniting the spray combustor 14, so that the operation frequency of the ignition device is increased. , The life of parts and the reliability are improved, and the fuel economy can be improved.
[0079]
In addition, in the present embodiment, since the exhaust gas temperature sensor 9 is disposed between the storage reduction NOx catalyst 8 and the particulate filter 16 which are exhaust gas purifying means, and the heat exchanger 25, one exhaust gas temperature sensor 9 is provided. By obtaining the temperature of the exhaust gas discharged from the storage reduction type NOx catalyst 8 and the particulate filter 16 and flowing into the heat recovery unit 25 by the exhaust gas temperature sensor, the storage reduction type NOx catalyst 8 and the particulate The temperatures of both the curated filter 16 and the heat exchanger 25 can be obtained at once.
[0080]
Therefore, the temperature of the NOx storage reduction catalyst 8, the particulate filter 16, and the temperature of the heat exchanger 25 can be accurately controlled with a simple configuration at low cost.
[0081]
When the temperatures of the storage reduction type NOx catalyst 8 and the particulate filter 16 are increased by the above method, the temperature of the heat recovery unit 25 is also increased. The temperature of both the filter 16 and the heat exchanger 25 is acquired, and when either temperature becomes excessively high, a plurality of exhaust system components such as stopping the operation of the air assist fuel supply device 14a are removed. It is possible to perform optimal control.
[0082]
The temperature of the exhaust gas detected by the exhaust gas temperature sensor 9 and the temperature of the inside of the particulate filter 8 depend on the configuration and shape of the NOx storage reduction catalyst 8, the particulate filter 16, the heat recovery unit 25, and the exhaust passage 7. Alternatively, it is conceivable that there is a difference between the temperature of the heat recovery unit 25 and in this case, a conversion map of the temperature data is stored in the ROM of the ECU 21 and the temperature data detected by the exhaust gas temperature sensor 9 is stored. By correcting, the temperature of the particulate filter 8 or the temperature of the heat recovery unit 25 may be used.
[0083]
Also in this case, according to the present embodiment, since the exhaust gas temperature sensor 9 is arranged near both the storage reduction NOx catalyst 8 and the particulate filter 16 and the heat recovery unit 25, both exhaust temperature sensors 9 are used. Temperature data having a high correlation with the temperature can be obtained, and the temperature control can be accurately performed.
[0084]
The above-described method of increasing the temperature of the exhaust gas may be used other than during the regeneration control of the particulate filter 16. For example, the present invention can be applied to a case where the heat recovery amount in the heat recovery device 25 is insufficient to maintain the vehicle interior temperature by the heater 29. Even in that case, the same effects as those described above can be obtained.
[0085]
In the exhaust system control system for an internal combustion engine in the present embodiment, the exhaust system components are arranged from the upstream side of the exhaust passage 7 in the storage reduction type NOx catalyst 8, the particulate filter 16, the heat recovery unit 25, and the like. In this order, the temperature control of the NOx storage reduction catalyst 8, the particulate filter 16, and the heat recovery unit 25 can be performed only by supplying the fuel from the air assist fuel supply device 14a provided upstream thereof. Further, since the particulate filter 16 is disposed upstream of the heat recovery unit 25, soot in the exhaust reaches the heat recovery unit 25, and is cooled and accumulated by the cooling water of the internal combustion engine 1. Also, there is no problem such as clogging of the exhaust passage.
[0086]
In the present embodiment, the exhaust system components are arranged in the order of the storage reduction type NOx catalyst 8, the particulate filter 16, and the heat recovery unit 25 from the upstream side of the exhaust passage 7. This arrangement may be applied to an exhaust system control system for an internal combustion engine provided with an exhaust temperature adjusting means other than the spray combustor shown in the present embodiment, or an exhaust temperature sensor which is an exhaust temperature acquiring means. Alternatively, the present invention may be applied to an exhaust system control system for an internal combustion engine that controls an exhaust gas temperature adjusting means based on a temperature other than the exhaust gas temperature obtained by the control unit 9.
[0087]
(Second embodiment)
A second embodiment of the present invention will be described with reference to FIG. Here, a configuration different from the above-described first embodiment will be described, and a description of the same configuration will be omitted.
[0088]
Also in this embodiment, since the configuration of the exhaust system of the internal combustion engine 1 is the same as that of the first embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted.
[0089]
In the present embodiment, an operation in the case where control is performed to lower the exhaust gas temperature by the same exhaust system configuration as in the first embodiment will be described.
[0090]
The case where it is necessary to control to lower the exhaust gas temperature means that when the temperature of the NOx storage reduction catalyst 8 and the particulate filter 16 as the exhaust gas purifying means becomes higher than a predetermined temperature, the high temperature deterioration of the catalyst is accelerated. Or the performance of the particulate filter 16 may be degraded.
[0091]
In the present embodiment, when it is necessary to lower the temperature of the exhaust gas as described above, only the air pump 14b of the spray combustor 14 is operated, and the low-temperature air introduced from the intake introduction passage 15 is exhausted. To lower the temperature of the exhaust.
[0092]
FIG. 4 shows an exhaust cooling routine according to the present embodiment.
[0093]
This routine is a routine stored in the ROM of the ECU 21 and is executed every time the crank position sensor 22 outputs a signal corresponding to a predetermined angle.
[0094]
When performing this routine, first, in S301, the ECU 21 acquires an output signal of the exhaust temperature sensor 9. Then, in S302, if the exhaust gas temperature acquired by the exhaust gas temperature sensor 9 is lower than the predetermined temperature, it is not necessary to lower the temperature of the exhaust gas. Here, the predetermined temperature may be set to 800 ° C. at which high-temperature deterioration of the NOx storage reduction catalyst 8 may be rapidly promoted.
[0095]
In S306, it is determined whether or not the air pump 14b is turned on. If the air pump 14b is turned on, the air pump 14b is turned off. If the air pump 14b is turned off, the present routine is terminated. If it is determined in S302 that the temperature of the exhaust gas is equal to or higher than the predetermined temperature, the process proceeds to S303. In S302, the time after the previous switching from the determination that the temperature is lower than the predetermined temperature to the determination that the temperature is equal to or higher than the predetermined temperature is performed. It is determined whether or not a predetermined time has elapsed. That is, it is determined whether the high temperature state of the exhaust gas has continued for a predetermined time or more.
[0096]
Here, the predetermined time may be set to one minute at which high-temperature deterioration of the NOx storage reduction catalyst 8 accelerates at a high temperature of, for example, 800 ° C. or higher. If it is determined that the predetermined time has elapsed, the process proceeds to S304, and it is determined whether the air pump 14b is already ON. Here, if the air pump 14b is in the OFF state, the process proceeds to S305, where only the air pump 14b of the spray combustor 14 is turned on, and this routine ends. If it is determined in S303 that the predetermined time has not elapsed, or if it is determined in S304 that the air pump has already been turned on, this routine is terminated as it is.
[0097]
In the present embodiment, by providing the exhaust gas cooling routine as described above, only the air pump 14b of the spray combustor 14 is operated when the exhaust gas temperature is equal to or higher than a predetermined temperature. The temperature of the exhaust gas can be lowered at an arbitrary timing without performing complicated control with a low cost and a simple configuration without performing.
[0098]
Then, by lowering the temperature of the exhaust gas, it is possible to promote the high-temperature deterioration of the NOx storage reduction catalyst 8 and prevent the performance deterioration of the particulate filter 16 due to overheating.
[0099]
(Third embodiment)
A third embodiment of the present invention will be described with reference to FIG. Here, a configuration different from the above-described first embodiment will be described, and a description of the same configuration will be omitted.
[0100]
Also in this embodiment, since the configuration of the exhaust system of the internal combustion engine 1 is the same as that of the first embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted.
[0101]
In the present embodiment, when performing the reduction treatment of the NOx storage reduction catalyst 8 with the same exhaust system configuration as in the first embodiment, the spray combustor 14 as the exhaust gas temperature adjusting means is burned at a rich air-fuel ratio. The control in the case where the control is performed will be described.
[0102]
FIG. 5 is a reduction processing routine for the storage reduction type NOx catalyst 8 according to the present embodiment. This routine is executed every time the crank position sensor 22 outputs a signal corresponding to a predetermined angle.
[0103]
In this routine, the determination as to whether or not the NOx absorption capacity of the storage reduction type NOx catalyst 8 is saturated is performed by estimating the integrated value of the NOx emission amount in the exhaust gas discharged from the engine, and calculating the integrated value of the exhausted NOx. From this, the amount of NOx stored in the NOx storage reduction catalyst 8 is estimated.
[0104]
That is, as the engine speed Ne increases, the amount of exhaust gas discharged from the engine per unit time increases, so the NOx amount discharged from the internal combustion engine increases as the engine speed Ne increases. Further, since the combustion temperature increases as the engine load L increases, it is based on the principle that as the engine load increases, the amount of NOx emitted from the engine per unit time increases.
[0105]
In this routine, the engine speed Ne, the accelerator opening α and the NOx amount are determined based on the relationship between the NOx amount discharged from the engine per unit time, the engine load L, and the engine speed Ne obtained by an experiment. Is mapped as a NOx emission map and stored in the ROM of the ECU 21 in advance. By reading this data, it is possible to estimate the NOx emission amount during each operation.
[0106]
When the processing of this routine is started, first, in S401, the aforementioned NOx is determined based on the engine rotation speed N obtained based on the output signal of the crank position sensor 22 and the accelerator opening α detected by the accelerator position sensor 24. The engine emission NOx amount Nm per unit time is read from the emission amount map.
[0107]
In S402, the amount of NOx absorbed by the NOx storage reduction catalyst 8 is integrated based on the engine exhaust NOx amount Nm read in S401.
[0108]
In S403, it is determined whether or not the integrated value S of the NOx amount has exceeded the saturation determination value S0. The saturation determination value S0 is the amount of NOx that can be absorbed before the NOx absorption capacity of the NOx storage reduction catalyst 8 is saturated, and the value determined in advance by experiment is stored in the ROM of the ECU 21.
[0109]
When it is determined in S403 that the integrated value S of the NOx amount has exceeded the saturation determination value S0, the process proceeds to S404, and it is determined whether or not the operation region is in a reduction processing-possible state. Here, the operation range in which the reduction process is possible is defined as a condition in which the temperature of the exhaust gas discharged from the exhaust gas purification means is equal to or higher than a predetermined temperature (for example, 250 ° C. or higher) and the engine speed Ne is equal to or lower than a predetermined speed (for example, 3000 rpm). The following conditions must be satisfied. The temperature of the exhaust gas discharged from the exhaust gas purifying means is obtained by the exhaust gas temperature sensor 9.
[0110]
If it is determined in S404 that the operating range is such that the reduction process can be performed, the ECU 21 operates the spray combustor 14. In this case, the amount of fuel supplied by the air-assisted fuel supply device 14a in the spray combustor 14 and the amount of air to be supplied by the air pump 14b are determined by the amount of HC and CO required for performing the reduction process of the NOx storage reduction catalyst 8. It is determined from the amounts of the components, mapped in advance, and stored in the ROM in the ECU 21.
[0111]
In the present embodiment, the air-assisted fuel supply device 14a supplies a fuel amount obtained by adding the fuel supplied to the storage reduction type NOx catalyst 8 as a reducing agent to the fuel amount burned in the spray combustor 14, and the result is as follows. As a result, combustion is performed at a rich air-fuel ratio.
[0112]
In S406 to S408, the timer is started, and Δt1 is added to the timer value T after the time Δt1 has elapsed, and it is determined whether or not the added timer value (T + Δt1) exceeds a predetermined determination value T0. If it is determined in S408 that the timer value has not exceeded T0, the process returns to S407 and repeats until it is determined in S408 that the timer value has exceeded T0.
[0113]
The determination value T0 is a time required to release and reduce all the NOx absorbed by the NOx storage reduction catalyst 8, and a value obtained by an experiment in advance is stored in the ROM of the ECU 21.
[0114]
If it is determined in S408 that the timer value has exceeded T0, the operation of the spray combustor 14 is terminated in S409, and the routine ends.
[0115]
As described above, in this routine, a part of the fuel is supplied to the exhaust without being burned in order to burn the spray combustor 14 at the rich air-fuel ratio. This unburned fuel contains HC that has been pyrolyzed to a relatively small molecular size when exposed to high temperature combustion heat in the spray combustor 14. As a result, exhaust containing HC having a small molecular size and a high NOx purification rate flows into the NOx storage reduction catalyst 8, and the reduction process can be performed efficiently.
[0116]
In particular, in the present embodiment, the spray combustor 14 includes the above-described air-assisted fuel supply device 14a, and the fuel supplied as the reducing agent is atomized by colliding with and mixing with the assist air. Therefore, reducing components such as HC and CO can be generated more efficiently, and the reduction treatment of the NOx storage reduction catalyst 8 can be performed with low fuel consumption.
[0117]
In addition, since the capacity of the NOx storage reduction catalyst 8 of the vehicle can be reduced, the amount of noble metal used can be reduced, and the cost can be reduced as a whole.
[0118]
FIG. 5 illustrates an example in which the spray combustor 14 having the air-assisted fuel supply device 14a is partially burned at a rich air-fuel ratio. Only the air pump 14b and the air assist fuel supply device 14a may be operated without burning the vessel 14.
[0119]
Even in this case, the fuel is atomized by the air-assisted fuel supply device 14a when the fuel collides with and mixes with the air. The fuel is not attached to the wall of the passage 7 and the catalyst can be efficiently reduced.
[0120]
The reduction processing routine described in the present embodiment may be applied to an exhaust system control system for an internal combustion engine in which the exhaust cooling routine described in the second embodiment is performed.
[0121]
(Fourth embodiment)
The fourth embodiment of the present invention will be described with reference to FIG. Here, a configuration different from the above-described first embodiment will be described, and a description of the same configuration will be omitted.
[0122]
Other configurations and operations are the same as those of the first embodiment, and therefore, the same components will be denoted by the same reference characters and description thereof will be omitted.
[0123]
In the present embodiment, an embodiment will be described in which the exhaust gas of the internal combustion engine 1 is provided with bypass means for bypassing the heat recovery unit 25.
[0124]
FIG. 6 is a diagram showing a schematic configuration of an internal combustion engine to which the present invention is applied. The difference from the exhaust system in the first embodiment is that a bypass passage 30 that connects the exhaust passages 7 before and after the heat recovery unit 25 in parallel with the heat exchanger 25 and an upstream side of the heat recovery unit 25 are provided. The point is that bypass means including an exhaust passage switching valve 31 for switching an exhaust passage between the exhaust passage 7 on the recovery unit 25 side and the bypass passage 30 is provided.
[0125]
This bypass means prevents the heat recovery unit 25 from excessively rising even when the exhaust gas temperature of the internal combustion engine 1 becomes high.
[0126]
FIG. 7 shows an exhaust passage switching routine according to the present embodiment. This routine is executed every time the crank position sensor 22 outputs a signal corresponding to a predetermined angle.
[0127]
When the execution of this routine is started, first, in S601, an exhaust gas temperature signal is obtained from the exhaust gas temperature sensor 9. In S602, the intake air amount from the air flow meter 5 of the internal combustion engine and the fuel injection amount of the engine from the RAM inside the ECU 21 are obtained, and the exhaust gas flow rate at this time is calculated from these values.
[0128]
Next, in S603, it is determined whether or not the exhaust gas temperature is equal to or higher than a predetermined temperature based on the value acquired in S601. In S604, it is determined whether the flow rate of the exhaust gas obtained in S602 is equal to or more than a predetermined flow rate.
[0129]
Here, in the steps S603 and S604, when it is determined that the temperature of the exhaust gas and the flow rate of the exhaust gas are respectively equal to or more than the predetermined values, it is preferable that the heat quantity of the exhaust gas is high and the passage through the heat recovery unit 25 is continued. Since there is not, the process proceeds to S605.
[0130]
In S605, it is determined whether or not the bypass passage 30 is open. If it is determined that the bypass passage 30 has already been opened, the routine exits from this routine. In this case, the control for cooling the temperature of the exhaust gas may be dealt with separately as described in the second embodiment of the present invention.
[0131]
When the bypass passage 30 is closed in S605, the process proceeds to S606, the exhaust passage switching valve 31 is operated, the bypass passage 30 is opened, and the exhaust passage 7 on the heat recovery unit 25 side is closed. Accordingly, when the heat amount of the exhaust gas is equal to or more than the predetermined value, the exhaust gas does not pass through the heat recovery device 25, so that the heat amount of the exhaust gas recovered by the heat recovery device 25 is reduced, and the heat recovery device 25 is prevented from being overheated. be able to.
[0132]
If it is determined in step S603 or S604 that either the temperature of the exhaust gas or the flow rate of the exhaust gas is equal to or less than the predetermined value, it is not necessary to make the exhaust gas bypass the heat recovery unit 25, and the process proceeds to S607. .
[0133]
In S607, it is determined whether or not the bypass passage 30 is open. If the bypass passage 30 is already closed, the routine ends. If the bypass passage 30 is open, the process proceeds to step S608 to operate the exhaust passage switching valve 31, close the bypass passage 30, open the exhaust passage 7 on the heat recovery unit 25 side, and execute this routine. finish.
[0134]
In the present embodiment, the bypass control means is configured to include the ECU 21 having a ROM storing the exhaust passage switching routine.
[0135]
According to the present embodiment, the amount of heat recovery in the heat recovery device 25 is controlled separately from the temperature of the exhaust gas by bypassing the heat recovery device 25 under predetermined conditions for the exhaust gas passing through the exhaust passage 7. Can be. Therefore, the temperature of the NOx storage reduction catalyst 8 and the particulate filter 16 as the exhaust gas purifying means and the temperature of the heat recovery unit 25 can be controlled independently.
[0136]
As a result, excessive heat recovery is prevented even under high load operation, during the reduction process of the NOx storage reduction catalyst 8, during the regeneration process of the particulate filter 16, and the like, in the operating condition where the temperature of the exhaust gas becomes high. However, the load on a radiator (not shown) can be reduced, and heat damage to the cooling system can be prevented.
[0137]
In the present embodiment, the routine for operating the bypass unit when the temperature of the exhaust gas of the internal combustion engine is equal to or higher than the predetermined temperature and the flow rate of the exhaust gas is equal to or higher than the predetermined flow rate has been described. In this case, the conditions for operating the bypass unit may be other than those described in the present embodiment, such as a routine for operating the bypass unit.
[0138]
Further, the bypass unit in the present embodiment is applied to an exhaust system control system of an internal combustion engine in which an exhaust cooling routine or a reduction processing routine as described in the second or third embodiment is executed. Alternatively, the present invention may be applied to an exhaust system control system for an internal combustion engine provided with an exhaust temperature adjusting means other than the spray combustor described with reference to FIGS. The present invention may be applied to an exhaust system control system for an internal combustion engine that controls an exhaust gas temperature adjusting unit based on a temperature other than the temperature of exhaust gas from the temperature sensor 9.
[0139]
【The invention's effect】
As described above, according to the present invention, the exhaust gas purifying means disposed in the exhaust passage of the internal combustion engine to purify the exhaust gas of the internal combustion engine, and the internal combustion engine disposed in series with the exhaust gas purifying means in the exhaust passage. Heat recovery means for recovering exhaust heat of the exhaust gas of the engine, exhaust temperature adjustment means for adjusting the temperature of the exhaust gas flowing into the exhaust purification means and the heat recovery means, and the exhaust purification means and the heat recovery means. Exhaust temperature acquisition means for acquiring the temperature of the exhaust gas during the period, so that one exhaust temperature acquisition means acquires both the temperature of the exhaust gas discharged from the exhaust gas purification means and the temperature of the exhaust gas flowing into the heat recovery means. The temperature of the exhaust gas purifying means and the heat recovery means can be accurately obtained from the obtained signal, and the temperatures of the exhaust gas purifying means and the heat recovery means can be accurately controlled.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a schematic configuration of a spray combustor according to the first embodiment of the present invention.
FIG. 3 is a sectional view of an air-assisted fuel supply device provided in the spray combustor according to the first embodiment of the present invention.
FIG. 4 is a flowchart illustrating an exhaust cooling routine according to a second embodiment of the present invention.
FIG. 5 is a flowchart illustrating a reduction processing routine of an occlusion reduction type NOx catalyst according to a third embodiment of the present invention.
FIG. 6 is a diagram illustrating a schematic configuration of an internal combustion engine according to a fourth embodiment of the present invention.
FIG. 7 is a flowchart illustrating an exhaust passage switching routine according to a fourth embodiment of the present invention.
[Explanation of symbols]
1. Internal combustion engine
2. Intake branch pipe
3. Intake pipe
6. Exhaust branch pipe
7. Exhaust passage
8. Oxidation reduction type NOx catalyst
9 ... Exhaust gas temperature sensor
14. Spray combustor
14a: Air assist fuel supply device
14b… Air pump
16 ... Particulate filter
21 ... ECU
25 ... Heat recovery unit
26 ... Muffler
30 ... Bypass passage
31 ... Exhaust passage switching valve

Claims (9)

Exhaust purification means disposed in an exhaust passage of the internal combustion engine to purify exhaust gas of the internal combustion engine;
A heat recovery unit disposed in series with the exhaust gas purification unit in the exhaust passage to recover exhaust heat of exhaust gas of the internal combustion engine;
Exhaust temperature adjusting means for adjusting the temperature of the exhaust gas of the internal combustion engine flowing into the exhaust gas purifying means and the heat recovery means;
Exhaust temperature obtaining means for obtaining the temperature of the exhaust gas of the internal combustion engine between the exhaust purification means and the heat recovery means,
An exhaust system control system for an internal combustion engine, comprising: 2. The exhaust system control of an internal combustion engine according to claim 1, further comprising a temperature control unit that controls the exhaust gas temperature adjustment unit based on the exhaust gas temperature of the internal combustion engine acquired by the exhaust gas temperature acquisition unit. system. The exhaust temperature control means includes an air introduction passage for introducing air into the exhaust passage, an air pump for sending air in the air introduction passage to the exhaust passage side, and an air for supplying fuel to the sent air. The exhaust system control system for an internal combustion engine according to claim 1, further comprising: a spray combustor having an assist fuel supply device and disposed upstream of the exhaust gas purifying means in the exhaust passage. The exhaust temperature control means includes an air introduction passage for introducing air into the exhaust passage, an air pump for sending air in the air introduction passage to the exhaust passage side, and an air for supplying fuel to the sent air. 3. An exhaust system control system for an internal combustion engine according to claim 2, further comprising: a spray combustor having an assist fuel supply device and disposed upstream of said exhaust gas purifying means in said exhaust passage. When the exhaust gas temperature obtained by the exhaust gas temperature obtaining device is higher than a predetermined temperature, the temperature control unit sets the fuel supply amount by the air-assisted fuel supply device to zero, and the air pump supplies the fuel in the air introduction passage. The exhaust system control system for an internal combustion engine according to claim 4, wherein the exhaust temperature control means is controlled so as to supply the air to the exhaust gas of the internal combustion engine. The exhaust gas purifying means has an exhaust gas purifying catalyst whose purification performance is restored by the reduction processing, and when performing the reduction processing, the temperature control means controls the spray combustor to burn at a rich air-fuel ratio. The exhaust system control system for an internal combustion engine according to claim 4 or 5, wherein: The exhaust system control system for an internal combustion engine according to any one of claims 1 to 6, further comprising a bypass unit that causes the exhaust gas of the internal combustion engine to bypass the heat recovery unit. A bypass control unit that controls an operation of the bypass unit, wherein the bypass control unit determines that the temperature of the exhaust gas acquired by the exhaust gas temperature acquisition unit is equal to or higher than a predetermined temperature, and that the flow rate of the exhaust gas of the internal combustion engine is equal to or less than a predetermined value. The exhaust system control system for an internal combustion engine according to claim 7, wherein the bypass unit is operated when the flow rate is equal to or more than the flow rate. The exhaust gas purification means has an exhaust gas purification catalyst and a particulate filter whose purification performance is restored by a reduction process,
9. The exhaust passage according to claim 1, wherein the exhaust gas purification catalyst, the particulate filter, and the heat recovery unit are arranged in this order from an upstream side of the exhaust passage. An exhaust system control system for an internal combustion engine as described in the above.

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