JP2003106137A - Exhaust emission control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust emission control device of an internal combustion engine which can favorably maintain purification efficiency of exhaust gas. SOLUTION: In this exhaust emission control device 2, by appropriately controlling an emission throttle amount with an emission throttle valve 62 and a high-temperature exhaust return amount with a first EGR valve 631A using an emission temperature controller 70, the emission temperature is maintained at a predetermined temperature. By this, when an emission post- treatment device 61 is DPF, combustion of PM such as scavenged soot or the like can be promoted, and when the emission post-treatment device 61 has a catalyst, the catalyst can be activated or substances adhering to the catalyst can be burned or removed to recover poisoning state of the catalyst, which can maintain exhaust gas purification effect favorably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for an internal combustion engine, and more particularly to an exhaust gas purifying apparatus for an internal combustion engine that purifies exhaust gas discharged from the internal combustion engine.

[0002]

BACKGROUND ART It has been conventionally known to provide an exhaust aftertreatment device in the middle of an exhaust passage in order to purify exhaust gas discharged from an internal combustion engine. As such an exhaust aftertreatment device, for example, an exhaust aftertreatment having a carrier carrying a NOx reduction catalyst (DeNOx catalyst) or a NOx storage reduction catalyst in order to reduce nitrogen oxides, so-called NOx, contained in the exhaust gas. Processors have been developed.

In an exhaust aftertreatment device having a NOx reduction catalyst and a NOx occlusion reduction catalyst, the NO of the catalyst in an oxidizing atmosphere is used.
Since the exhaust gas is purified by utilizing the x reduction action, it is necessary to add a sufficient amount of hydrocarbon to the exhaust gas flowing into the carrier. Here, as the hydrocarbon, light oil, which is a fuel, is usually used as it is, or a light oil obtained by fractionating and reforming light oil is used.

In such an exhaust aftertreatment device, when the fuel is added to the exhaust gas, the fuel is vaporized due to the exhaust temperature, and when the exhaust gas containing the vaporized fuel reaches the exhaust aftertreatment device, the hydrocarbon of the fuel is discharged. The components act to reduce NOx. However, since the fuel partially contains a hydrocarbon component with a high boiling point, the hydrocarbon component with a high boiling point adheres to the catalyst without causing any reaction without vaporizing in the exhaust gas, There is a case where the exhaust gas purifying ability of is reduced, that is, the catalyst is poisoned.

In order to recover such a poisoning state of the catalyst, it is possible to raise the exhaust temperature for a certain period of time and allow the high-temperature exhaust gas to flow into the exhaust post-treatment device to burn the hydrocarbon components adhering to the catalyst. Are known. As a method of raising the exhaust gas temperature, an exhaust gas recirculation device for extracting a part of exhaust gas and recirculating it to the intake side is used to increase the exhaust gas temperature, which is installed in the intake passage of the internal combustion engine. A method has been proposed (see Japanese Patent Laid-Open No. 2000-18024). In this method, the exhaust temperature is raised by adjusting the opening of the intake throttle valve to increase the amount of intake air or by increasing the amount of exhaust gas recirculation by the exhaust gas recirculation device, and the opening of the intake throttle valve is adjusted. The exhaust gas temperature is reduced by reducing the intake air amount and the exhaust gas recirculation amount by the exhaust gas recirculation device, thereby controlling the exhaust gas temperature.

[0006]

However, in the above method for raising the exhaust gas temperature, the intake air amount is appropriately adjusted by adjusting the opening degree of the intake throttle valve, thereby raising or lowering the exhaust gas temperature. . For this reason, for example, when using an internal combustion engine in the cold season or in cold regions,
In the case of an internal combustion engine equipped with a cooling means such as an intercooler for cooling the intake air, cold intake air is supplied to the combustion chamber, which makes it difficult for the combustion chamber to cool and the exhaust gas temperature to rise.
There is a problem that the exhaust temperature cannot be controlled reliably. If the exhaust gas temperature cannot be controlled reliably, the exhaust aftertreatment device cannot be reliably recovered from the poisoned state, and the NOx purification efficiency in the exhaust aftertreatment device decreases. .

Further, in an internal combustion engine equipped with a supercharger that obtains a driving force for a compressor from an exhaust turbine arranged in the middle of an exhaust passage, when the intake throttle valve is throttled, the work on the compressor side decreases and the exhaust turbine The rotation speed is increasing. In other words, on the intake side, the supercharging pressure by the compressor shifts to a high state. For this reason, even if the intake amount is throttled by the intake throttle valve, the supercharging pressure by the compressor is high, so that there is a problem that the intake amount cannot be adjusted reliably and the exhaust gas temperature cannot be controlled reliably.

An object of the present invention is to provide an exhaust gas purifying apparatus for an internal combustion engine, which can maintain good exhaust gas purifying efficiency.

[0009]

In order to achieve the above-mentioned object, an exhaust gas purifying apparatus for an internal combustion engine according to the present invention includes an exhaust gas recirculation path connecting an intake path and an exhaust path of the internal combustion engine, Exhaust gas recirculation amount adjusting means, which is arranged in the middle of the exhaust gas recirculation passage and is capable of adjusting the amount of exhaust gas flowing in the exhaust gas recirculation passage by changing the opening degree, and arranged in the middle of the exhaust gas passage of the internal combustion engine and opened. The exhaust gas flow rate adjusting means capable of adjusting the amount of exhaust gas flowing in the exhaust passage by changing the degree, an exhaust aftertreatment device disposed in the middle of the exhaust passage of the internal combustion engine to purify the inflowing exhaust gas, A temperature detection means for detecting at least one of the temperature of the exhaust aftertreatment device and the exhaust temperature; and a control means for controlling the operations of the exhaust flow rate adjusting means and the exhaust gas recirculation amount adjusting means, wherein the control means is The internal combustion engine The opening degree of the exhaust flow rate adjusting means and the exhaust gas recirculation amount adjustment so that the temperature detected by the temperature detecting means becomes a predetermined temperature when the load is low or one of the medium and low loads. It is characterized in that the opening of the means is controlled.

On the other hand, in order to achieve the above object, the exhaust gas purifying apparatus for an internal combustion engine according to the present invention comprises:
A supercharger having a compressor arranged in the middle of the intake passage and an exhaust turbine arranged in the middle of the exhaust passage is provided, and the exhaust gas purification device is provided with the intake passage and the exhaust passage of the internal combustion engine. An exhaust gas recirculation path connecting the exhaust gas recirculation path and an exhaust gas recirculation amount adjusting means arranged in the middle of the exhaust gas recirculation path and capable of adjusting the amount of exhaust gas flowing in the exhaust gas recirculation path by means of an opening degree; And a turbine bypass connecting the downstream side, a bypass exhaust amount adjusting means that is arranged in the middle of the turbine bypass and that can adjust the exhaust amount that flows through the turbine bypass by changing the opening, and the turbine bypass. Is also disposed in the exhaust passage on the downstream side and detects at least one of the temperature of the exhaust aftertreatment device for purifying the inflowing exhaust gas and the temperature of the exhaust aftertreatment device. Temperature detecting means and control means for controlling the operations of the bypass exhaust gas amount adjusting means and the exhaust gas recirculation amount adjusting means, wherein the control means is one of low load and medium / low load of the internal combustion engine. At this time, the opening degree of the bypass exhaust gas amount adjusting means and the opening degree of the exhaust gas recirculation amount adjusting means are controlled so that the temperature detected by the temperature detecting means becomes a preset predetermined temperature. It is characterized by that.

Here, as an exhaust aftertreatment device, a diesel particulate filter (hereinafter, DPF (Diesel) is used.
Exhaust aftertreatment device with Particulate Filter)), N
Any of an exhaust aftertreatment device having an Ox reduction catalyst, an exhaust aftertreatment device having a NOx occlusion reduction catalyst, an exhaust aftertreatment device having an oxidation catalyst, and an exhaust aftertreatment device having a three-way catalyst can be adopted. When the exhaust aftertreatment device has a DPF, PM (Particulate Ma
tter) can be used at a temperature higher than the temperature at which it can burn.
When the exhaust aftertreatment device has a catalyst (DP having a catalyst
F also included), the temperature range in which the catalyst has the activation,
Of the substances that adhere to the catalyst and make it poisonous, at least a part of the substances can be burned or desorbed.

In the exhaust gas purifying apparatus for an internal combustion engine, which includes the exhaust flow rate adjusting means and the exhaust gas recirculation amount adjusting means, the exhaust gas throttle amount by the exhaust flow rate adjusting means and the exhaust gas recirculation amount by the exhaust gas recirculating amount adjusting means are controlled means. The exhaust temperature and / or the temperature of the exhaust post-treatment device can be maintained at a predetermined temperature by performing appropriate control according to. Accordingly, when the exhaust aftertreatment device has the DPF, combustion of the collected soot is promoted, and when the exhaust aftertreatment device has the catalyst (including the DPF having the catalyst), the catalyst is activated. Alternatively, the substance adhering to the catalyst is burned to recover the poisoning state of the catalyst, so that the purification efficiency of the exhaust gas in the exhaust gas purification device can be favorably maintained. Further, in the present invention, since the exhaust flow rate adjusting means is used,
By adjusting the opening degree of the exhaust flow rate adjusting means, the exhaust pressure on the upstream side of the exhaust flow rate adjusting means can be increased, and hot exhaust gas is likely to remain in the combustion chamber. Then, since the combustion chamber is warmed by the exhaust gas, the exhaust gas temperature quickly rises. Therefore, the exhaust temperature can be quickly raised to the predetermined temperature in either one of the low load and the medium / low load of the internal combustion engine whose exhaust temperature is low.

On the other hand, in the exhaust gas purifying apparatus for an internal combustion engine which includes the bypass exhaust gas amount adjusting means and the exhaust gas recirculating amount adjusting means, the exhaust gas amount bypassing the exhaust turbine, that is, the work amount of the exhaust turbine and the exhaust gas recirculation amount. By appropriately controlling the exhaust gas recirculation amount by the adjusting means by the control means, the exhaust temperature and / or the temperature of the exhaust post-treatment device is maintained at a predetermined temperature. As a result, like the exhaust gas purifying apparatus for an internal combustion engine that includes the above-described exhaust flow rate adjusting means and exhaust gas recirculation amount adjusting means, the exhaust gas purifying efficiency in the exhaust gas purifying apparatus can be favorably maintained. . Further, in the present invention, since the turbine bypass and the bypass exhaust amount adjusting means are used, the exhaust amount flowing through the exhaust turbine of the supercharger can be adjusted by adjusting the opening degree of the bypass exhaust amount adjusting means. It is possible to adjust the work of the turbine, that is, the degree of boost pressure by the compressor. By adjusting the supercharging pressure of the compressor in this way, the amount of intake air supplied into the combustion chamber can be reliably controlled, so that the exhaust temperature can be reliably controlled. Further, by bypassing the turbine, the pressure difference between the turbine and the compressor can be increased, and the exhaust gas recirculation amount can also be increased, so that the exhaust temperature can be raised more quickly.

In the exhaust gas purifying apparatus for an internal combustion engine according to both of the present invention described above, when the internal combustion engine is at a low load or at a medium or low load, that is, when the operating state of the internal combustion engine has a margin. In addition, since the exhaust temperature is controlled by controlling the exhaust throttle amount or turbine bypass exhaust amount and the exhaust gas recirculation amount, the performance and durability of the internal combustion engine can be maintained.

In the exhaust gas purifying apparatus for an internal combustion engine of the present invention, when the internal combustion engine is provided with an intake cooling means arranged in the middle of the intake passage to cool the intake air, the exhaust gas purifying apparatus is equipped with the intake cooling system. A cooler bypass connecting the upstream side and the downstream side of the means, and a bypass intake air amount adjusting means arranged in the middle of the cooler bypass and capable of adjusting the intake air amount flowing through the cooler bypass by changing the opening degree. The control means controls the bypass intake air amount so that the temperature detected by the temperature detection means becomes a predetermined temperature when the internal combustion engine is at a low load or a medium or low load. It is desirable to control the opening degree of the adjusting means. By bypassing the intake air cooling means and avoiding the cooling of the intake air by the intake air cooling means, the intake air flow rate can be reduced and the exhaust gas temperature can be increased. Therefore, the temperature of the exhaust aftertreatment device and / or the exhaust gas aftertreatment device can be increased. The temperature can be raised quickly.

In the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, the control means is configured so that the internal combustion engine has a low load and a medium load.
It is desirable that the temperature detected by the temperature detecting means is set to the predetermined temperature for a predetermined time when either one of the low loads is applied. Here, the predetermined time may be a time counted and divided by a time measuring means such as a timer, or by using a predetermined low load operation continuously performed for a predetermined time during the operation of the internal combustion engine. The time may be the time during which the internal combustion engine is performing the predetermined low load operation. With this configuration, when the internal combustion engine is at a low load or at a medium or low load, the exhaust temperature is raised to the predetermined temperature only for the preset predetermined time. The burden can be reduced, and the performance and durability of the internal combustion engine can be maintained.

In the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, when the internal combustion engine has a predetermined low load operating state in which the internal combustion engine is operated at a certain frequency and at a low load and at a substantially constant engine rotation speed for a predetermined time. It is preferable that the control means sets the temperature detected by the temperature detection means to the predetermined temperature when the internal combustion engine is in a predetermined low load operation state. In this way, the predetermined low load operation of the internal combustion engine is an operation that is performed with a certain frequency and during a predetermined time during the operation of the internal combustion engine, so that soot combustion is performed with a certain frequency and for a predetermined time. It can promote the recovery of the poisoning state of the catalyst. As a result, it is possible to avoid a reduction in the purification capacity of the exhaust aftertreatment device, so that it is possible to maintain good purification efficiency of the exhaust gas. Further, in the present invention, it is determined whether or not the exhaust gas temperature is maintained at the predetermined temperature based on the determination as to whether or not the internal combustion engine is in the predetermined low load operation state, so that the purification capacity of the catalyst is reduced. The exhaust gas purifying apparatus according to the present invention can be simplified in configuration without separately providing a detecting unit for detecting the.

In the exhaust gas purifying apparatus for an internal combustion engine of the present invention, if a predetermined low load operation state of the internal combustion engine near a high idle with a high engine rotation speed is adopted, for example, a construction machine (such as a hydraulic excavator or a bulldozer) can be used. In internal combustion engines used for construction machinery and generators, when working (load is applied) at a high engine speed, it is usually in a high idle state before the load is applied and after the load is removed. Therefore, the exhaust gas temperature can be reliably maintained at a predetermined temperature with a certain frequency, and the exhaust gas purification efficiency can be favorably maintained.

In the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, the internal combustion engine has a high speed low idle and a low speed low idle with different engine speeds as low idle and low engine speed. After starting the operation of low idle, when a predetermined time has passed,
When the operation of the high speed low idle is ended and the operation of the low speed low idle is started, the high speed low idle state can be adopted as the predetermined low load operation state.

As described above, in an internal combustion engine having two types of low idles, that is, high speed low idle and low speed low idle, when the load is removed and the work is removed, the engine speed is increased to high speed low idle. The engine speed is reduced to a low speed low idle after a predetermined time has elapsed. As a result, even if a load is applied again immediately after the load on the internal combustion engine is removed, the internal combustion engine waits in a high-speed low idle state where the engine rotation speed is high to some extent, so the torque is immediately applied. It can be increased and the response to the load can be made quick. In such an internal combustion engine, the high-speed low idle operation is performed for a predetermined time each time the load is removed, so if the high-speed low idle state is adopted as the predetermined low-load operation state, it will be ensured at a certain frequency. The exhaust temperature can be maintained at a predetermined temperature, and the exhaust gas purification efficiency can be favorably maintained.

In the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, the control means controls the internal combustion engine to have a low load and a medium load.
When either one of the low loads, the air-fuel ratio of the internal combustion engine is close to the stoichiometric air-fuel ratio, the opening degree of the exhaust flow rate adjusting means and the opening degree of the exhaust gas recirculation amount adjusting means, or,
It is desirable to control the opening degree of the bypass exhaust gas amount adjusting means and the opening degree of the exhaust gas recirculation amount adjusting means. As described above, when the air-fuel ratio of the internal combustion engine is close to the stoichiometric air-fuel ratio, when the catalyst is poisoned by the sulfur component, it is possible to effectively release the sulfur component from the catalyst.

In the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, the predetermined temperature is preferably 600 ° C. or higher. As described above, when the air-fuel ratio of the internal combustion engine is set close to the stoichiometric air-fuel ratio and the temperature of the exhaust aftertreatment device or the exhaust temperature is set to a temperature of 600 ° C. or higher, the sulfur component adhering to the catalyst is released more effectively. As a result, the catalyst can be greatly recovered from the poisoned state, and the exhaust gas purification efficiency can be further improved.

In the exhaust gas purifying apparatus for an internal combustion engine of the present invention, it is desirable that the exhaust gas purifying apparatus be provided with a heat insulating material that covers at least a part of the exhaust passage. In this way, since the temperature of the exhaust gas can be kept warm, the temperature of the exhaust post-treatment device or the exhaust temperature can be raised quickly.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. [First Embodiment] FIG. 1 shows a system according to a first embodiment of the present invention. This system includes a diesel engine 1 as an internal combustion engine and exhaust gas provided in the diesel engine 1. The purification device 2 is provided. First, the outline of the system will be described. The diesel engine 1 is an internal combustion engine that generates a driving force by injecting fuel into compressed high-temperature air to self-ignite, and has a plurality of cylinders (not shown) each having a combustion chamber formed therein. An engine body 10, an intake passage 20 for performing intake air to each cylinder, an exhaust passage 30 for exhausting each cylinder, and a supercharger for compressing intake air for supercharging the diesel engine 1. 41, a cooling mechanism 42 for cooling the diesel engine 1, and an engine controller 50 for controlling the operation of the diesel engine 1. The exhaust gas purification device 2 includes an exhaust aftertreatment device 61 installed in the exhaust passage 30 of the diesel engine 1, an exhaust throttle valve 62 as an exhaust flow control valve, and a part of the exhaust gas to be extracted to the intake side. An exhaust gas recirculation unit 63 for recirculating and an exhaust gas temperature controller 70 as a control unit for controlling the exhaust gas temperature are provided.

Next, details of the system will be described.
In the diesel engine 1, although not shown, a cylinder head forming a top wall of a combustion chamber in the cylinder is provided above the cylinder of the engine body 10, and the intake passage 20 and the exhaust gas are exhausted through the cylinder head. The passage 30 is connected to the combustion chamber. Although not shown in the figure, an intake valve that can open and close the combustion chamber and the intake passage 20 to open and close the cylinder head, and an open and close that can open and close the combustion chamber and the exhaust passage 30 to open and close the combustion chamber An exhaust valve and a fuel injection nozzle for injecting and supplying fuel into the combustion chamber are mounted. The fuel supply amount and fuel supply timing from the fuel injection nozzle to the combustion chamber are determined by the operation of the fuel injection pump with a governor that supplies the pressurized fuel to the fuel injection nozzle. The operation of this fuel injection pump is
It is controlled by the engine controller 50 via the governor.

The intake passage 20 includes an intake port formed in the cylinder head, and an intake manifold 21 connected to each cylinder via the intake port. A compressor 41A of the supercharger 41 and an intercooler 43 are provided in the middle of the intake passage 20. The exhaust passage 30 includes an exhaust port formed in the cylinder head and an exhaust manifold 31 connected to each cylinder via the exhaust port. The exhaust turbine 4 of the supercharger 41 is provided in the middle of the exhaust passage 30.
1B, an exhaust aftertreatment device 61 of the exhaust gas purification device 2 and an exhaust throttle valve 62 are provided. Also, the exhaust path 3
In No. 0, the space between the exhaust turbine 41B of the supercharger 41 and the exhaust aftertreatment device 61 is covered with the heat insulating material 65, whereby the exhaust gas in the exhaust passage 30 is kept warm.

As described above, the supercharger 41 has the intake passage 2
Compressor 41A arranged at 0 and exhaust passage 30
Has an exhaust turbine 41B disposed at In the supercharger 41, the exhaust turbine 41B is rotated by utilizing the exhaust gas, whereby the compressor 41A is rotationally driven to compress the intake air, whereby the diesel engine 1 is supercharged.

The cooling mechanism 42 includes a circulation circuit 421 that circulates the refrigerant in the cooling required portion of the diesel engine 1, and a pump 4 that is provided in the circulation circuit 421 to pump the refrigerant.
22 and a radiator 423 provided in the circulation circuit 421 for air cooling the refrigerant. In the cooling mechanism 42 having such a configuration, the pump 422 is provided by a crankshaft (not shown) housed in the engine body 10.
When the engine is driven, the refrigerant is pressure-fed, and the refrigerant cools the engine main body 10 of the diesel engine 1, the supercharger 41, an oil cooler (not shown), and the like, and then the radiator provided in the cooling mechanism 42. It is air-cooled at 423. The radiator 423 and the intercooler 43 described above are designed to be cooled by a fan 11 provided in the engine body 10 and driven to rotate by a crankshaft or the like.

Exhaust gas aftertreatment device 61 of the exhaust gas purification device 2
As shown in FIG. 2, the carrier includes a substantially columnar carrier 61A, and the carrier 61A has a large number of small holes 611 in a honeycomb shape.
It has a structure with. The small hole 611 communicates from the inflow side end surface 612 toward the outflow side end surface 613 side, that is, along the axial direction of the carrier 61A, and its cross section is formed in a polygonal shape (hexagonal shape in this embodiment). There is. The carrier 61A is made of cordierite, ceramics such as silicon carbide, or metal such as stainless steel or aluminum, and the material thereof is appropriately determined according to the use of the carrier 61A.

When the exhaust after-treatment device 61 is a DPF, the numerous small holes 611 of the carrier 61A are provided on the outflow side end face 61.
It is divided into a small hole 611 that functions as an inflow side flow path by plugging the 3 side and a small hole 611 that functions as an outflow side flow path by plugging the inflow side end face 612 side. These flow paths are arranged in a staggered pattern. Then, the boundary wall portion of each flow path (small hole 611) is formed into a random porous shape, and particulates (for example, soot, mist of unburned fuel or lubricating oil) in the exhaust gas flowing from the flow path on the inflow side are formed. Sulfate (composite composed of sulfuric acid mist, etc.) is collected at the boundary wall and accumulated in the inflow side flow path, and clean exhaust gas with particulates removed is collected in the outflow side flow path. Is discharged through.

On the other hand, when a catalyst is used in the exhaust post-treatment device 61, the catalyst is carried on the carrier 61A by a known method such as impregnation by immersion, wash coating, ion exchange or the like. Then, while the exhaust gas passes through the small holes 611, the exhaust gas is purified by the action of the catalyst and becomes clean. The catalyst carried on the carrier 61A is
NOx storage reduction catalyst for removing NOx (nitrogen oxide), NOx storage catalyst, oxidation catalyst for oxidizing and removing HC and CO (carbon monoxide), hydrocarbons, carbon monoxide, and nitrogen oxides. A three-way catalyst or the like can be used.

Returning to FIG. 1, the exhaust throttle valve 62 is provided in the exhaust passage 3 downstream of the installation position of the exhaust turbine 41B of the supercharger 41 and upstream of the installation position of the exhaust aftertreatment device 61.
It is installed at 0. Although not shown, the exhaust throttle valve 62 is provided with an actuator (an actuator such as a motor or a cylinder) that opens and closes the exhaust throttle valve 62. The exhaust flow rate adjusting means is not limited to a throttle valve (throttle valve), but various valves such as a butterfly valve and a gate valve can be adopted, and any valve capable of adjusting the flow rate of exhaust gas flowing through the exhaust passage 30 can be used. The valve of may be adopted. In such a configuration, by appropriately controlling the operation of the actuator, the opening degree of the exhaust throttle valve 62 is adjusted and the flow rate of exhaust gas passing through the exhaust passage 30 per unit time is adjusted.

The exhaust gas recirculation means 63 are respectively provided in the intake passage 20.
The first exhaust gas recirculation passage 631 and the second exhaust gas recirculation passage 632 are connected to the exhaust gas recirculation passage 30. Specifically, these first and second exhaust gas recirculation paths 6
One end of 31, 632 is connected to the intake passage 20 upstream of the branch point of the intake manifold 21, and the other end of the exhaust passage 30 downstream of the merge point of the exhaust manifold 31.
It is connected to the.

A first EGR valve 631A as an exhaust gas recirculation amount adjusting means is provided in the middle of the first exhaust gas recirculation passage 631. Although not shown, the first EGR valve 631A is provided with an actuator that opens and closes the first EGR valve 631A, like the exhaust throttle valve 62. In such a configuration, by appropriately controlling the operation of the actuator, the opening degree of the first EGR valve 631A is adjusted, and the high temperature of the high temperature gas recirculated from the exhaust passage 30 to the intake passage 20 via the first exhaust gas recirculation passage 631 is adjusted. The amount of exhaust is adjusted.

A second EGR valve 632A serving as an exhaust gas recirculation amount adjusting means is provided in the middle of the second exhaust gas recirculation passage 632, like the first exhaust gas recirculation passage 631.
The valve 632A is provided with an actuator that opens and closes the valve 632A. A cooler 632B that cools the exhaust gas flowing through the second exhaust gas recirculation path 632 is provided in the middle of the second exhaust gas recirculation path 632. This cooler 632B is connected in the middle of the circulation circuit 421 of the cooling mechanism 42 of the diesel engine 1, and the refrigerant passing through the inside of the cooler 632B is the second exhaust gas recirculation passage 63.
It is possible to cool the exhaust gas flowing back to the intake passage 20 by removing the heat of the exhaust gas flowing through the inside of the exhaust passage 2. In such a configuration, by appropriately controlling the operation of the actuator, the opening degree of the second EGR valve 632A is adjusted,
The amount of low-temperature exhaust gas that is recirculated from the exhaust passage 30 to the intake passage 20 via the second exhaust gas recirculation passage 632 is adjusted.

The first and second EGR valves 631
A and 632A include a throttle valve (throttle valve),
Various valves such as butterfly valves and gate valves can be adopted,
Any valve can be adopted as long as it can adjust the flow rate of the exhaust gas flowing through the first and second exhaust gas recirculation paths 631 and 632.

The exhaust gas temperature controller 70 is provided to maintain the exhaust gas temperature at a predetermined temperature set in advance when the diesel engine 1 is operating in a predetermined low load operation state. Depending on,
Exhaust throttle valve 62 actuator, first EGR valve 6
31A actuator and second EGR valve 63
Each operation of the 2A actuator is controlled. The exhaust temperature controller 70 is electrically connected to the engine controller 50 that controls the governor of the fuel injection pump and the like in order to detect the operating condition of the diesel engine 1. As a result, the exhaust temperature controller 70
An engine rotation speed signal output from the engine controller 50, which indicates the rotation speed of the diesel engine 1, and
A fuel supply amount signal indicating the fuel supply amount to the diesel engine 1 and an air-fuel ratio signal indicating the air-fuel ratio of the exhaust gas of the diesel engine 1 are input.

Although not shown, the diesel engine 1 has a rotation speed sensor as a rotation speed detecting means for detecting its rotation speed and a load detecting means for detecting a fuel supply amount to the diesel engine 1. A rack sensor and an air-fuel ratio sensor as an air-fuel ratio detecting means for detecting the air-fuel ratio of the diesel engine are provided, and each sensor is electrically connected to the engine controller 50.
Among them, the rack sensor detects the position of a rack slidably provided with respect to the plunger in order to adjust the amount of fuel injected from the fuel injection pump.

Further, the exhaust gas purifying apparatus 2 has a temperature sensor 64 for detecting the exhaust temperature at the inlet side of the exhaust post-treatment device 61.
have. The temperature sensor 64 is electrically connected to the exhaust temperature controller 70, whereby an exhaust temperature signal indicating the exhaust temperature of the diesel engine 1 is input to the exhaust temperature controller 70.
The temperature sensor 64 is the carrier 6 of the exhaust aftertreatment device 61.
It may be directly attached to 1A to detect the temperature of the carrier 61A itself.

The exhaust temperature controller 70 as described above is
As shown in FIG. 3, based on the storage unit 71 that stores three types of maps, and the various maps stored in the storage unit 71, the exhaust throttle valve 62, the first EGR valve 631A, and the second EGR valve 632A are stored. And an arithmetic processing unit 72 for determining the opening degree. Although not shown, the exhaust temperature controller 70 includes an input unit to which an output signal from the engine controller 50 and an output signal from the temperature sensor 64 are input, in addition to the storage unit 71 and the arithmetic processing unit 72. Exhaust throttle valve 62, first EGR valve 63
1A, and an output unit for outputting an operation signal to each actuator of the second EGR valve 632A.

The storage unit 71 is provided with the second E that can obtain the optimum exhaust gas recirculation amount with respect to the engine rotation speed and the fuel supply amount.
A first map showing the opening degree of the GR valve 632A, a second map showing the opening degree of the exhaust throttle valve 62 that provides the optimum exhaust temperature with respect to the engine rotation speed and the fuel supply amount, and the engine rotation speed and Three types of maps are stored: a third map showing the opening degree of the first EGR valve 631A with which the optimum exhaust temperature is obtained for the fuel supply amount.

In the first map, the optimum exhaust gas recirculation amount means that the NOx reduction rate is high and PM (Part
Exhaust gas recirculation amount that reduces the occurrence rate of iculate matter. In the second map and the third map, the optimum exhaust gas temperature is a temperature equal to or higher than the temperature at which PM such as collected soot is combustible when the exhaust aftertreatment device 61 is a DPF. When the post-treatment device 61 has a catalyst, it is in a temperature range in which the catalyst is activated or at a temperature at which at least a part of the substance attached to the catalyst is combustible or desorbable. In addition, these 1st-3rd maps are obtained by experiment, calculation, etc.

The arithmetic processing unit 72 is used for the diesel engine 1
Operation state determination unit 721 that determines whether or not the operation is in a predetermined low load operation state set in advance, and exhaust gas that determines whether the input exhaust temperature signal is at a preset predetermined temperature. A temperature determination unit 722, an air-fuel ratio determination unit 723 that determines whether the input air-fuel ratio signal is near the stoichiometric air-fuel ratio, and an exhaust temperature control unit 72 that controls the exhaust temperature.
4 and a second determining the opening degree of the second EGR valve 632A.
An exhaust gas recirculation amount control unit 725 is provided.

In the operating condition judging section 721, based on the input engine rotation speed signal and fuel supply amount signal,
After determining whether or not the operation of the diesel engine 1 is in a predetermined low load state (predetermined low load operating state), the determination result is output to the exhaust temperature control unit 724. Here, as the predetermined low load operation state, for example, as shown in FIG. 4, high idle in which the diesel engine 1 is operated at a low load and at a substantially constant engine rotation speed N _H can be applied. Also, diesel engine 1
Is a low idle with a low load and a low engine speed, which includes a low speed low idle operated at a substantially constant engine speed N _L1 and a high speed low idle operated at a substantially constant engine speed N _L2. As the predetermined low load operation state, high speed low idle can be adopted.

When the load is released from the state in which the diesel engine 1 is loaded and is working as a prime mover, the engine speed is reduced to some extent, and a predetermined low load such as high idle or high speed low idle is applied. After a certain period of time, the engine speed is further reduced, and in the case of high idle, the engine idle speed is in the middle idle (the engine speed approximately midway between the high idle engine speed and the low idle engine speed). Idle operated at a speed), and in the case of high speed low idle, it moves to low speed low idle. That is, in the diesel engine 1, each time the load is removed, the high idle operation or the high speed low idle operation is performed for a predetermined time. As a result, even if the load is applied again immediately after the load on the diesel engine 1 is removed, the diesel engine 1 is waiting in the high idle or high speed low idle state in which the engine speed is high. The torque can be increased immediately and the response to the load can be made quick.

In the exhaust gas temperature determination section 722, when the exhaust gas post-treatment device 61 has a DPF, the predetermined temperature is
A temperature higher than the temperature at which PM such as collected soot can be combusted can be adopted, and when the exhaust aftertreatment device 61 has a catalyst, among substances that adhere to the catalyst and cause poisoning,
A temperature equal to or higher than the temperature at which at least a part of the substances can be burned or released can be used. Here, when the purpose of raising the exhaust gas temperature to a predetermined temperature is to recover the poisoning state of the catalyst, a temperature of 600 ° C. or higher at which the sulfur component adhering to the catalyst can be released is adopted as the predetermined temperature. Is desirable. In such a case, as the predetermined temperature, only the above-mentioned lower limit temperature may be set, and further, the upper limit temperature may be set. As the upper limit temperature, a temperature corresponding to an allowable temperature in consideration of durability of the diesel engine 1 can be adopted.

If the exhaust aftertreatment device 61 has a catalyst, the temperature range in which the catalyst is activated may be adopted as the predetermined temperature. When the upper limit temperature of the temperature range in which the catalyst is activated is higher than the allowable temperature considering the durability of the diesel engine 1, the upper limit temperature of the predetermined temperature is set to the allowable temperature of the diesel engine 1.
The exhaust temperature determination unit 722 configured as described above outputs the determination result to the exhaust temperature control unit 724 after determining whether the exhaust temperature of the diesel engine 1 is the predetermined temperature as described above. ing.

The air-fuel ratio determination section 723 determines whether or not the input air-fuel ratio signal is in the vicinity of the theoretical air-fuel ratio, and then outputs the determination result to the exhaust temperature control section 724. Here, the vicinity of the stoichiometric air-fuel ratio specifically refers to an air-fuel ratio of 0.85 or more and 1.00 or less.

The exhaust temperature control unit 724 determines the opening degree of the first EGR valve 631A.
A and an exhaust flow rate controller 724B that determines the opening of the exhaust throttle valve 62. First exhaust gas recirculation amount control unit 72
4A is a second map stored in the storage unit 71,
This is a part that outputs an operation signal to the actuator of the first EGR valve 631A based on the input engine rotation speed signal and the fuel supply amount signal, thereby appropriately adjusting the opening degree of the first EGR valve 631A. The exhaust flow rate control unit 724B outputs an operation signal to the actuator of the exhaust throttle valve 62 based on the third map stored in the storage unit 71 and the input engine rotation speed signal and fuel supply amount signal. Therefore, the exhaust throttle valve 62
This is a part for appropriately adjusting the opening degree of. It should be noted that the first exhaust gas recirculation amount control unit 724A and the exhaust gas flow rate control unit 724B use the second map and the third map based on the outputs from the operating state determination unit 721, the exhaust temperature determination unit 722, and the air-fuel ratio determination unit 723. EGR valve 631A based on the map of
Also, it is determined whether or not to control the opening degree of the exhaust throttle valve 62.

The second exhaust gas recirculation amount control unit 725 includes a storage unit 7
An operation signal is output to the actuator of the second EGR valve 632A based on the first map stored in No. 1 and the input engine rotation speed signal and fuel supply amount signal, whereby the second EGR valve 632A operates. This is a part for appropriately adjusting the opening degree.

Next, the operation of this embodiment will be described. First, when a starting switch (not shown) of the diesel engine 1 is turned on, the crankshaft starts to be rotated by a drive source such as a starting device, the diesel engine 1 is started, and an output signal from the starting switch is output to the engine controller. 50 and the exhaust temperature controller 70, and each controller 50, 70 is activated.

In FIG. 5, in step S11, the engine speed signal and the fuel supply amount signal from the engine controller 50 are input to the exhaust temperature controller 70, and the process proceeds to step S12. Here, in the second exhaust gas recirculation amount control unit 725 of the exhaust temperature controller 70, when the engine rotation speed signal and the fuel supply amount signal from the engine controller 50 start to be input, based on the first map of the storage unit 71, The opening degree control of the second EGR valve 632A is started until the operation of the diesel engine 1 is stopped. As a result, the diesel engine 1 can obtain an optimal exhaust gas recirculation amount according to its operating condition,
The NOx reduction efficiency is improved due to the decrease in the maximum combustion temperature.

At step S12, the exhaust temperature controller is controlled.
Engine input by the operating state determination unit 721 of the LA 70
Based on the rotation speed signal and the fuel supply amount signal,
Whether or not the Zel engine 1 is in a predetermined low load operation state
To confirm. Specifically, the predetermined low load operating state is high.
When idling, the engine speed is low and the engine speed is almost constant.
Speed N_HCheck whether the vehicle is driven in
When the loading operation is high speed low idle, the load is low and
Nearly constant engine speed N _L2Whether it is driven in
Check if And the diesel engine 1
When not in the low load operation state, the process proceeds to step S13,
When the diesel engine 1 is in a predetermined low load operation state
If so, the process proceeds to step S14.

In step S13, since the diesel engine 1 is not in the predetermined low load operation state, the first EGR valve 631A is substantially fully closed, the exhaust throttle valve 62 is substantially fully opened, and the diesel engine 1 is operated by the exhaust temperature controller. The normal operation without the exhaust gas temperature control by 70 is performed, and the process returns to step S11. When the operating state determination unit 721 of the exhaust temperature controller 70 determines that the diesel engine 1 is not in the predetermined low load operating state, the first exhaust gas recirculation amount control unit 724A and the exhaust flow rate control unit 724B are stored in the storage unit. The opening degrees of the first EGR valve 631A and the exhaust throttle valve 62 are not controlled according to the second and third maps of the first EGR valve 6 of FIG.
An operation signal for substantially closing the valve 631A is output to the actuator of 31A, and an operation signal for opening the valve 62 to the actuator of the exhaust throttle valve 62 is output.

In step S14, since the diesel engine 1 is in the predetermined low load operation state, the exhaust temperature controller 70 determines the first EGR valve 631A and the exhaust throttle valve based on the second and third maps of the storage unit 71. The opening degree of 62 is set, and the process proceeds to step S15.

In step S15, the air-fuel ratio determination unit 723 of the exhaust temperature controller 70 confirms whether the air-fuel ratio of the exhaust gas of the diesel engine 1 is near the stoichiometric air-fuel ratio, and the air-fuel ratio is not near the stoichiometric air-fuel ratio. If so, the process proceeds to step S16. If the air-fuel ratio is near the stoichiometric air-fuel ratio, the process proceeds to step S17.

In step S16, if the air-fuel ratio of the exhaust gas of the diesel engine 1 has not reached near the stoichiometric air-fuel ratio, the exhaust temperature controller 70 causes the first EGR valve 6
The openings of 31A and the exhaust throttle valve 62 are corrected, and the process returns to step S15 to check again whether the air-fuel ratio of the exhaust gas of the diesel engine 1 is near the stoichiometric air-fuel ratio.

In step S17, the exhaust temperature of the diesel engine 1 is input, and the process proceeds to step S18. In step S18, the input exhaust temperature T is determined by the exhaust temperature determination unit 722 of the exhaust temperature controller 70 to be the upper limit temperature of the predetermined temperature. It is confirmed whether or not T1 is reached, and when it is reached, the process proceeds to step S19, and when it is not reached, the process proceeds to step S20.

In step S19, when the exhaust gas temperature T reaches the upper limit temperature T1 of the predetermined temperature, the exhaust gas temperature T is too high and exceeds the upper limit temperature of the temperature range in which the catalyst of the exhaust aftertreatment device 61 is activated. Since the allowable temperature in consideration of the durability of the diesel engine 1 is exceeded, the exhaust temperature controller 70 uses the first EGR valve 631A in order to make the exhaust temperature T lower than the upper limit temperature T1 of the predetermined temperature.
And the opening degree of the exhaust throttle valve 62 is corrected. In particular,
The exhaust temperature is lowered by decreasing the opening of the first EGR valve 631A to reduce the amount of high temperature exhaust gas recirculation and increasing the opening of the exhaust throttle valve 62 to reduce the amount of exhaust remaining in the combustion chamber. As a result, the temperature of the exhaust post-treatment device 61 also decreases, and the exhaust temperature T (temperature of the exhaust post-treatment device 61)
Becomes lower than the upper limit temperature T1 of the predetermined temperature, so that the purification efficiency of the exhaust gas is favorably maintained and the exhaust temperature is prevented from rising excessively. After that, the process returns to step S17, and it is confirmed whether or not the input exhaust temperature T has reached the upper limit temperature T1 of the predetermined temperature.

In step S20, the exhaust temperature determination unit 722 of the exhaust temperature controller 70 confirms whether or not the exhaust temperature T has reached the lower limit temperature T2 of the predetermined temperature. If not, the process proceeds to step S21 and reaches it. If so, the process returns to step S11.

In step S21, if the exhaust gas temperature T does not reach the lower limit temperature T2 of the predetermined temperature, the exhaust gas temperature T is too low and falls below the lower limit temperature of the temperature range in which the catalyst of the exhaust aftertreatment device 61 is activated. Since the PM collected by the exhaust aftertreatment device 61 is below the combustible temperature, and the substance adhering to the catalyst of the exhaust aftertreatment device is below the combustible or desorbable temperature, the exhaust temperature In order to make T higher than the lower limit temperature T2 of the predetermined temperature, the exhaust temperature controller 70 corrects the opening degrees of the first EGR valve 631A and the exhaust throttle valve 62. Specifically, the first EG
The exhaust temperature is raised by increasing the opening degree of the R valve 631A to increase the high temperature exhaust gas recirculation amount and decreasing the opening degree of the exhaust throttle valve 62 to increase the exhaust gas amount remaining in the combustion chamber. As a result, the temperature of the exhaust after-treatment device 61 also rises, the exhaust temperature T (the temperature of the exhaust after-treatment device 61) becomes higher than the lower limit temperature T2 of the predetermined temperature, and the purification efficiency of the exhaust gas is maintained well. . After this, return to step S17,
It is confirmed whether or not the input exhaust gas temperature T reaches the lower limit temperature T2 of the predetermined temperature.

From each step, step S11
Returning to, a series of steps starting from step S11 is repeated until the diesel engine 1 stops. As a result, when the diesel engine 1 is in a predetermined low load operation state, the exhaust temperature rises to a predetermined temperature,
When the exhaust aftertreatment device 61 has a DPF, combustion of PM such as collected soot is promoted, and when the exhaust aftertreatment device 61 has a catalyst (including a DPF having a catalyst), the catalyst has The poisoned state of the catalyst is restored by activating or burning or detaching the substance attached to the catalyst.

Here, as the predetermined low load operation state of the diesel engine 1, as described above, the high idle or the high speed low idle is adopted, and the predetermined low load operation is applied to the diesel engine 1. Load is removed, that is, with a certain frequency,
It is continuously performed for a predetermined time. Therefore, in this embodiment,
Since the exhaust gas temperature controller 70 controls the exhaust gas temperature when the diesel engine 1 is in a predetermined low load operation state, the exhaust gas temperature controller 70 continuously exhausts the exhaust gas with a certain frequency for a predetermined time when the diesel engine 1 has a low load. The temperature can be set to a predetermined temperature, and the exhaust gas purification efficiency in the exhaust aftertreatment device 61 can be favorably maintained.

According to this embodiment as described above, the following effects can be obtained. In the present embodiment, the exhaust gas purification device 2
Since the exhaust temperature controller 70 appropriately controls the exhaust throttle amount by the exhaust throttle valve 62 and the high temperature exhaust gas recirculation amount by the first EGR valve 631A, the exhaust temperature is maintained at a predetermined temperature. 6
When 1 is a DPF, combustion of PM such as collected soot can be promoted, and when the exhaust aftertreatment device 61 has a catalyst, the catalyst can be activated, or substances adhering to the catalyst are burned or released. By doing so, the poisoning state of the catalyst can be recovered, and the purification efficiency of exhaust gas can be favorably maintained.

Since the exhaust gas purifying apparatus 2 uses the exhaust throttle valve 62, the exhaust pressure on the upstream side of the exhaust throttle valve 62 can be increased by adjusting the opening degree of the exhaust throttle valve 62, and the high temperature inside the combustion chamber can be obtained. The exhaust of the can be easily left. And because the combustion chamber is warmed by this high-temperature exhaust,
The exhaust temperature can be raised quickly, and the combustion of PM, the activation of the catalyst, the recovery from the poisoned state of the catalyst, etc. can be performed quickly.

The exhaust gas temperature controller 70 controls the exhaust gas throttle amount and the high temperature exhaust gas recirculation amount to control the exhaust gas temperature when the diesel engine 1 has a low load, that is, when the operating condition of the diesel engine 1 has a margin. Therefore, it is possible to avoid deterioration of the performance and durability of the diesel engine 1 due to the exhaust temperature control.

Further, the exhaust temperature controller 70 controls the exhaust temperature by controlling the exhaust throttle amount and the high temperature exhaust gas recirculation amount only when the diesel engine has a low load and for a predetermined time. Engine 1
The diesel engine 1
It is possible to surely avoid deterioration of performance and durability.

The exhaust temperature controller 70 burns PM during a predetermined low load operation state such as a high idle operation or a high speed low idle operation which is performed with a certain frequency during operation of the diesel engine 1 and is performed for a predetermined time. Is promoted, the catalyst is activated, and the poisoning state of the catalyst is recovered, it is possible to surely avoid a decrease in the purification capacity of the exhaust aftertreatment device 61, and the exhaust gas purification efficiency is good. Can be maintained at

Further, the exhaust temperature controller 70 determines whether or not to maintain the exhaust temperature at the predetermined temperature based on the determination as to whether or not the diesel engine 1 is in the predetermined low load operation state. As a result, it is not necessary to separately provide a detection unit that detects a decrease in the purification ability of the catalyst, and the configuration of the exhaust gas purification device 2 can be simplified.

Since the exhaust temperature controller 70 sets the air-fuel ratio of the diesel engine 1 to near the stoichiometric air-fuel ratio when raising the exhaust temperature, it is possible to remove the poisoning of the sulfur compound in the exhaust aftertreatment device 61.

In this embodiment, the predetermined temperature in the exhaust temperature control of the exhaust temperature controller 70 is 600
If the temperature is set to ℃ or higher, not only the hydrocarbon component attached to the catalyst of the exhaust aftertreatment device 61 but also the sulfur component can be released, and the catalyst can be greatly recovered from the poisoned state, The gas purification efficiency can be further improved.

Since the exhaust passage 30 between the exhaust turbine 41B of the supercharger 41 and the exhaust aftertreatment device 61 is covered with the heat insulating material 65, the exhaust gas in the exhaust passage 30 can be kept warm and the exhaust temperature can be kept high. It can be raised quickly.

[Second Embodiment] FIG. 7 shows a second embodiment of the present invention.
A system according to an embodiment is shown. In the second embodiment, the exhaust temperature is controlled by the exhaust throttle valve 62 and the exhaust gas recirculation means 63 in the first embodiment, but the exhaust turbine bypass means for bypassing the exhaust turbine 41B of the supercharger 41 is used. The exhaust temperature is controlled by 66 and the exhaust gas recirculation means 63.

That is, in FIG. 7, the diesel engine 1 differs from the first embodiment described above in that instead of the exhaust throttle valve 62, a turbine bypass 66A connecting the upstream side and the downstream side of the exhaust turbine 41B, An exhaust turbine bypass means arranged in the middle of the turbine bypass 66A and including a bypass valve 66B as a bypass exhaust gas amount adjusting means capable of adjusting the exhaust gas amount flowing in the bypass 66A by changing the opening degree. 66 is provided.

Although not shown, the bypass valve 66B is provided with an actuator (actuator such as a motor or a cylinder) for opening and closing the valve 66B, and the operation of this actuator is controlled by the exhaust temperature controller 70. There is. As the bypass valve 66B, various valves such as a throttle valve, a butterfly valve, and a gate valve can be adopted, and any valve can be adopted as long as the flow rate of exhaust gas flowing through the turbine bypass 66A can be adjusted. it can.

In the exhaust turbine bypass means 66 having such a configuration, the opening degree of the bypass valve 66B is adjusted by appropriately controlling the operation of the actuator, and the flow rate of exhaust gas passing through the turbine bypass 66A per unit time. Is adjusted. That is, the amount of exhaust gas that passes through the exhaust turbine 41B of the supercharger 41 can be adjusted, so that the work amount of the compressor 41A driven by the rotational driving of the exhaust turbine 41B, that is, the degree of supercharging pressure can be adjusted. .

Therefore, when raising the exhaust gas temperature of the diesel engine 1, it is sufficient to reduce the supercharging pressure to reduce the intake air amount. Therefore, the exhaust gas temperature controller 70 tells the actuator of the bypass valve 66B to the valve 66B.
An operation signal for increasing the opening degree of is output. On the other hand, when lowering the exhaust gas temperature of the diesel engine 1, it is sufficient to increase the supercharging pressure and increase the intake air amount. Therefore, the exhaust gas temperature controller 70 uses the bypass valve 6
An operation signal for reducing the opening degree of the valve 66B is output to the 6B actuator.

In the exhaust temperature controller 70 of the second embodiment, in the exhaust temperature controller 70 of the first embodiment described above, the second map stored in the storage unit 71 indicates the opening degree of the exhaust throttle valve 62. In addition, the exhaust flow rate control unit 724B controls the exhaust throttle valve 6 based on the second map.
Instead of using the second map, the storage unit 71 outputs the operation signal to the second actuator instead of the opening degree of the bypass valve 66B that provides the optimum exhaust temperature with respect to the engine speed and the fuel supply amount. Is stored, and the bypass valve 66 is based on the fourth map, although not shown in the figure, instead of the exhaust flow rate control unit 724B.
A bypass exhaust amount control unit for outputting an operation signal is provided to the B actuator, and the other configurations are the same as those of the exhaust temperature controller 70 of the first embodiment, and therefore description thereof will be omitted.

According to the second embodiment as described above, the exhaust temperature controller 70 appropriately adjusts the opening degree of the bypass valve 66B, so that the exhaust turbine 4 of the supercharger 41 can be controlled.
Displacement that bypasses 1B, that is, compressor 41
Since the supercharging pressure by A is controlled and the exhaust temperature is maintained at a predetermined temperature, the combustion promotion of PM, the activation of the catalyst, the recovery from the poisoning state of the catalyst, etc. are performed as in the first embodiment. Therefore, the purification efficiency of the exhaust gas in the exhaust aftertreatment device 61 can be favorably maintained.

[Third Embodiment] FIG. 8 shows a third embodiment of the present invention.
A system according to an embodiment is shown. In the third embodiment, the cooler bypass means 67 for bypassing the intercooler 43 as the intake air cooling means is provided in the first embodiment, and the intake air amount bypassing the intercooler 43 is exhausted by the cooler bypass means 67. It is controlled by the temperature controller 70.

That is, in FIG. 8, unlike the first embodiment described above, the diesel engine 1 includes a cooler bypass 67A connecting the upstream side and the downstream side of the intercooler 43, and a cooler bypass 67A in the middle of the cooler bypass 67A. A cooler bypass unit 67 is provided which is arranged and includes a bypass valve 67B as a bypass intake amount adjusting unit that can adjust the intake amount flowing in the bypass 67A by changing the opening degree.

Although not shown, the bypass valve 67B is provided with an actuator (actuator such as a motor or a cylinder) for opening and closing the valve 67B, and the operation of this actuator is controlled by the exhaust temperature controller 70. There is. As the bypass valve 67B, various valves such as a throttle valve, a butterfly valve, and a gate valve can be adopted, and any valve can be adopted as long as the flow rate of the intake air flowing through the cooler bypass 67A can be adjusted. it can.

In the cooler bypass means 67 having such a structure, the opening degree of the bypass valve 67B is adjusted by appropriately controlling the operation of the actuator, and the flow rate of the intake air passing through the cooler bypass 67A per unit time is adjusted. Adjusted. That is, the amount of intake air that passes through the intercooler 43 can be adjusted, and thus the amount of intake air supplied to the cylinder of the diesel engine 1 can be adjusted.

Therefore, when raising the exhaust temperature of the diesel engine 1, it is sufficient to reduce the amount of intake air passing through the intercooler 43 to reduce the amount of intake air supplied to the cylinder. Therefore, the exhaust temperature controller 70 operates the bypass valve 67B. An operation signal for increasing the opening of the valve 67B is output to the actuator. On the other hand, when lowering the exhaust temperature of the diesel engine 1, it is sufficient to increase the amount of intake air that passes through the intercooler 43 and increase the amount of intake air that is supplied into the cylinder. Therefore, the exhaust temperature controller 70 operates as an actuator for the bypass valve 67B. On the other hand, an operation signal for reducing the opening degree of the valve 67B is output.

The exhaust temperature controller 70 of the third embodiment is similar to the exhaust temperature controller 70 of the first embodiment described above, but the optimum exhaust temperature for the engine speed and the fuel supply amount is stored in the storage unit 71. A fifth map indicating the opening degree of the obtained bypass valve 67B is further stored, and the exhaust air temperature control unit 724 outputs the operation signal to the actuator of the bypass valve 67B based on the fifth map. Since the control unit is further provided and the other structure is the same as that of the exhaust temperature controller 70 of the first embodiment, the description thereof will be omitted.

According to the third embodiment as described above, the same operation and effect as those of the above-described first embodiment can be obtained, and further, the opening degree of the bypass valve 67B is appropriately adjusted by the exhaust temperature controller 70. The exhaust temperature can be lowered or raised by increasing or decreasing the amount of intake air supplied to the cylinder, so the exhaust temperature and / or the temperature of the exhaust aftertreatment device can be controlled more reliably and quickly. You will be able to.

The present invention is not limited to the above-described embodiment, and modifications and improvements within a range where the object of the present invention can be achieved are included in the present invention. For example,
The temperature detecting means is not limited to the temperature detecting means for detecting the exhaust temperature near the inlet of the exhaust aftertreatment device, but may be the temperature detecting means for detecting the exhaust temperature on the upstream side of the exhaust passage. However, in such a case, if the exhaust path between the installation position of the temperature detection means and the installation position of the exhaust aftertreatment device is long, there will be a difference between the exhaust temperature detected by the temperature detection means and the temperature of the exhaust aftertreatment device. Therefore, it is preferable to dispose the temperature detecting means as close to the exhaust aftertreatment device as possible.

The exhaust gas recirculation means may be an exhaust gas recirculation means having one exhaust gas recirculation path, for example, an exhaust gas recirculation means 631 having a first exhaust gas recirculation path 631 for recirculating high temperature exhaust gas to the intake side. Alternatively, it may be an exhaust gas recirculation unit having a second exhaust gas recirculation passage 632 for recirculating low-temperature exhaust gas to the intake side.

The heat insulating material is not limited to the heat insulating material that covers the exhaust passage between the exhaust turbine and the exhaust aftertreatment device, but may be the heat insulating material that covers the exhaust passage between the exhaust manifold and the exhaust aftertreatment device. Good.

The internal combustion engine is not limited to the spontaneous ignition type diesel engine, but may be a spark ignition type gasoline engine, and in the first embodiment, it may be a non-supercharged engine. .

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a diesel engine and an exhaust gas purification device according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing an exhaust aftertreatment device in the first embodiment.

FIG. 3 is a block diagram showing an exhaust temperature controller in the first embodiment.

FIG. 4 is a graph showing an operating state of the diesel engine in the first embodiment.

FIG. 5 is a flowchart showing an operation in the first embodiment.

FIG. 6 is a flowchart showing an operation in the first embodiment.

FIG. 7 is a schematic configuration diagram showing a diesel engine and an exhaust gas purification device according to a second embodiment of the present invention.

FIG. 8 is a schematic configuration diagram showing a diesel engine and an exhaust gas purification device according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Diesel engine which is an internal combustion engine, 2 ... Exhaust gas purification device, 20 ... Intake passage, 30 ... Exhaust passage, 41 ... Supercharger, 41A ... Compressor, 41B ... Exhaust turbine, 6
DESCRIPTION OF SYMBOLS 1 ... Exhaust aftertreatment device, 62 ... Exhaust throttle valve as exhaust flow rate adjusting means, 64 ... Temperature sensor as temperature detecting means, 6
5 ... Insulating material, 66A ... Turbine bypass, 66B ... Bypass valve which is a bypass exhaust amount adjusting means, 67A ... Cooler bypass, 67B ... Bypass valve which is bypass intake air amount adjusting means, 70 ... Exhaust temperature controller as a control means, 631A ... First exhaust gas recirculation amount adjusting means
EGR valve, 632A ... Second EGR valve which is exhaust gas recirculation amount adjusting means

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F01N 3/02 F01N 3/02 321H 3G092 3/08 3/08 A 3/24 3/24 B EN 3 / 28 301 3/28 301A 301C F02B 37/00 302 F02B 37/00 302D 302Z 37/12 302 37/12 302D 37/18 F02D 21/08 301H F02D 21/08 301 311B 311 23/00 J 23/00 N 43/00 301N 43/00 301 301R 301T 301Z F02M 25/07 570G F02M 25/07 570 570J 570P F02B 37/12 301A (72) Inventor Nobuhiko Emori 400 Yokokura Nitta, Tochigi Prefecture AIP Co., Ltd. F term in A (reference) 3G005 DA02 EA16 FA35 GB18 GB28 GD13 HA12 HA13 HA18 JA02 JA16 JA24 JA39 JA45 3G062 AA01 AA05 BA04 BA06 CA07 ED08 ED11 GA01 GA05 GA06 GA09 3G084 AA01 BA08 BA19 BA20 BA24 BA26 CA03 DA10 FA13 FA27 FA29 FA33 3G090 AA03 BA01 CB23 DA12 DA18 DB02 AB18 AB06 AB14 AB04 AB02 AB04 AB02 AB02 AB04 AB02 EA01 EA08 EA17 EA34 FA08 FA13 FB02 GA06 GB10X GB17X HA14 HB05 HB06 3G092 AA02 AA17 AA18 AB03 BA04 BB01 DB03 DC09 DC12 DC15 DE15S DF02 DF06 DG07 FA17 FA18 GA05 GA17 HA15X HB01Z HD02XHD05Z HE02

Claims (10)

[Claims] 1. An exhaust gas purification device (2) for an internal combustion engine (1), comprising an intake passage (20) and an exhaust passage (30) of the internal combustion engine (1).
An exhaust gas recirculation path (631, 632) that connects with the exhaust gas recirculation path (631, 632), and
By changing the opening, the exhaust gas recirculation path (631, 63
2) Exhaust gas recirculation amount adjusting means (631A, 632A) capable of adjusting the amount of exhaust gas flowing through the inside of the internal combustion engine (1) and disposed in the middle of the exhaust path (30) of the internal combustion engine (1) by changing the opening degree. An exhaust gas flow rate adjusting means (62) capable of adjusting the amount of exhaust gas flowing in the passage (30), and an exhaust post-treatment which is arranged in the middle of the exhaust passage (30) of the internal combustion engine (1) and purifies inflowing exhaust gas. Device (6
1) and temperature detection means (64) for detecting at least one of the temperature of the exhaust after-treatment device (61) and the exhaust temperature.
And a control means (70) for controlling the operations of the exhaust flow rate adjusting means (62) and the exhaust gas recirculation amount adjusting means (631A, 632A), the control means (70) including the internal combustion engine (1). Of the exhaust flow rate adjusting means (62) so that the temperature detected by the temperature detecting means (64) becomes a predetermined temperature when the load is low load or medium or low load. And the exhaust gas recirculation amount adjusting means (631A, 632)
An exhaust gas purifying device (2) for an internal combustion engine (1), characterized in that the opening degree of A) is controlled. 2. An exhaust gas purifying apparatus (2) for an internal combustion engine (1), wherein the internal combustion engine (1) includes a compressor (41A) disposed midway in an intake passage (20), and the exhaust passage (20). 30)
A supercharger (41) having an exhaust turbine (41B) disposed in the middle of the exhaust gas is provided, and the exhaust gas purification device (2) is provided with an intake passage (20) and an exhaust passage of the internal combustion engine (1). An exhaust gas recirculation path (631, 632) connecting with (30), and arranged in the middle of the exhaust gas recirculation path (631, 632),
By changing the opening, the exhaust gas recirculation path (631, 63
2) Exhaust gas recirculation amount adjusting means (631A, 632A) capable of adjusting the amount of exhaust gas flowing through the inside, a turbine bypass (66A) connecting the upstream side and the downstream side of the exhaust turbine (41B), and the turbine bypass ( 66A), which is disposed in the middle, and is capable of adjusting the amount of exhaust flowing through the turbine bypass (66A) by changing the opening degree.
6B), an exhaust aftertreatment device (61) disposed in the exhaust passage (30) on the downstream side of the turbine bypass (66A) to purify inflowing exhaust gas, and a temperature of the exhaust aftertreatment device (61). And a temperature detecting means (64) for detecting at least one of exhaust temperature.
And a control unit (70) for controlling the operations of the bypass exhaust gas amount adjusting unit (66B) and the exhaust gas recirculation amount adjusting unit (631A, 632A), the control unit (70) including the internal combustion engine (1). ) Is one of low load and medium / low load, the bypass exhaust gas amount adjusting means (66) is set so that the temperature detected by the temperature detecting means (64) becomes a preset predetermined temperature.
B) opening degree and the exhaust gas recirculation amount adjusting means (631A,
An exhaust gas purifying device (2) for an internal combustion engine (1), characterized in that it controls an opening degree of 632A). 3. The exhaust gas purifying apparatus (2) for an internal combustion engine (1) according to claim 1 or 2, wherein the internal combustion engine (1) is arranged in the middle of an intake passage (20). An intake air cooling means (43) for cooling the intake air is provided, and the exhaust gas purification device (2) is provided with the intake air cooling means (4).
3) A cooler bypass (67A) that connects the upstream side and the downstream side, and is arranged in the middle of the cooler bypass (67A), and the amount of intake air flowing through the cooler bypass (67A) is adjusted by changing the opening degree. Possible bypass intake amount adjusting means (6
7B), the control means (70) preliminarily sets the temperature detected by the temperature detection means (64) in advance when the internal combustion engine (1) has either a low load or a medium or low load. The bypass intake air amount adjusting means (67
An exhaust gas purification device (2) for an internal combustion engine (1), characterized in that the opening degree of B) is controlled. 4. The exhaust gas purification device (2) for an internal combustion engine (1) according to any one of claims 1 to 3, wherein the control means (70) is configured so that the internal combustion engine (1) has a low load. The internal temperature of the internal combustion engine (1) is characterized in that the temperature detected by the temperature detecting means (64) is set to the predetermined temperature for a predetermined time when either one of the medium and low loads. Exhaust gas purification device (2). 5. The exhaust gas purification apparatus (2) for an internal combustion engine (1) according to claim 4, wherein the internal combustion engine (1) is operated at a certain frequency, has a low load, and has a substantially constant engine rotation speed. The control means (70) has a predetermined low load operating state that is performed at a speed for a predetermined time, and the control means (70) is detected by the temperature detecting means (64) when the internal combustion engine (1) is in the predetermined low load operating state. An exhaust gas purification device (2) for an internal combustion engine (1), characterized in that the temperature is set to the predetermined temperature. 6. The exhaust gas purifying apparatus (2) for an internal combustion engine (1) according to claim 5, wherein the predetermined low load operating state is a state near high idle where the engine speed is high. An exhaust gas purifying device (2) for an internal combustion engine (1). 7. The exhaust gas purification apparatus (2) for an internal combustion engine (1) according to claim 5, wherein the internal combustion engine (1) is a low idle engine with a low engine speed and a low engine speed. The internal combustion engine (1) has different high-speed low idles and different low-speed idles, and the internal combustion engine (1) terminates the operation of the high-speed low idles when a predetermined time elapses after starting the operation of the high-speed low idles. An exhaust gas purifying apparatus (2) for an internal combustion engine (1), wherein low idle operation is started and the predetermined low load operating state is the high speed low idle state. 8. The exhaust gas purifying apparatus (2) for an internal combustion engine (1) according to any one of claims 1 to 7, wherein the control means (70) controls the internal combustion engine (1) to have a low load. The opening degree of the exhaust flow rate adjusting means (62) and the exhaust gas recirculation amount adjusting means so that the air-fuel ratio of the internal combustion engine (1) becomes close to the stoichiometric air-fuel ratio when either one of the medium and low loads is applied. (631A, 632A), or the opening degree of the bypass exhaust gas amount adjusting means (66B) and the exhaust gas recirculation amount adjusting means (631A, 632A) are controlled. Exhaust gas purification device (2) of the engine (1). 9. The exhaust gas purification apparatus (2) for an internal combustion engine (1) according to claim 8, wherein the predetermined temperature is a temperature of 600 ° C. or higher. Exhaust gas purification device (2). 10. The exhaust gas purifying device (2) for an internal combustion engine (1) according to any one of claims 1 to 9, wherein a heat insulating material (6) covering at least a part of the exhaust passage (30).
An exhaust gas purifying device (2) for an internal combustion engine (1), comprising: