JP2006266220A - Rising temperature controller of aftertreatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the excessive rise of the temperature of a catalyst at the beginning of a catalyst temperature rising by the supply of HC to the exhaust emission control catalyst of an aftertreatment device. <P>SOLUTION: The target HC supply amount set part 102 of the ECU 10 of a rising temperature controller sets a target HC supply amount at the beginning of temperature rising based on an output from an upstream side temperature sensor 61 in the catalyst indicating the temperature of the upstream side end part of the catalyst 42. A light oil adding injector 50 supplies a light oil HC in the exhaust gases on the upstream side of the catalyst based on the target HC supply amount. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a temperature increase control device for an aftertreatment device having a diesel particulate filter and an exhaust purification catalyst, and more particularly, a temperature increase control that suppresses excessive temperature increase of the catalyst at the initial stage of catalyst temperature increase due to HC supply. Relates to the device.

  If particulates (hereinafter referred to as PM) contained in the exhaust of a diesel engine are released into the atmosphere, air pollution will be caused. Therefore, a diesel particulate filter (hereinafter referred to as DPF) is provided in the engine exhaust system to provide PM. Although the trapping is performed, the engine performance may be reduced due to an increase in exhaust pressure accompanying the increase in the trapped PM. Therefore, PM is burned and removed to regenerate the DPF. Further, since the exhaust temperature is low when the engine is under a low load, unburned charge such as HC is supplied into the exhaust upstream of the DPF during DPF regeneration, and the unburned charge is oxidized by the oxidation catalyst carried on the DPF. There is a case where PM is burned by using the generated oxidation heat. However, the fuel supply amount suitable for DPF regeneration also changes depending on the intake air amount and the exhaust flow rate. For this reason, if the engine speed decreases during DPF regeneration, the fuel concentration in the exhaust gas becomes excessive and the DPF temperature becomes excessive. There is a possibility of an increase, and when the exhaust gas flow rate increases, the fuel concentration in the exhaust gas becomes too low, the DPF temperature does not rise sufficiently, and PM may not burn.

Therefore, the exhaust treatment device described in Patent Document 1 is provided with temperature sensors on the upstream side and downstream side of the DPF, and reduces the amount of fuel supplied to the DPF as the exhaust temperature detected by the upstream temperature sensor increases. The amount of intake air detected by the intake air amount detecting means is calculated to increase, and the fuel supply amount calculated in this way is corrected according to the DPF temperature detected by the downstream temperature sensor. The fuel supply suitable for the engine operating state during the regeneration of the DPF is performed.
JP-A-5-44434

  As described above, the exhaust gas purification device described in Patent Document 1 has a downstream temperature sensor that detects the amount of fuel supplied to the DPF calculated based on the exhaust gas temperature upstream of the DPF detected by the upstream temperature sensor. Although it is corrected according to the DPF temperature (actually, the exhaust temperature downstream of the DPF), the exhaust temperature upstream or downstream of the DPF does not necessarily reflect the DPF temperature during the DPF regeneration, and the fuel during the DPF regeneration. It is actually difficult to control the supply amount well.

  Further, the exhaust purification device (post-treatment device) has various configurations. In the case of an after-treatment device having a DPF and an exhaust purification catalyst, unburnt fuel such as HC is supplied to the exhaust purification catalyst to raise the temperature of the catalyst. Sometimes. If such HC supply control is performed based on the exhaust temperature on the upstream side or downstream side of the catalyst, the exhaust temperature on the upstream side and downstream side of the catalyst both represent the catalyst temperature well. Not particularly, especially during temperature rise transients where the temperature of each part of the catalyst does not become uniform (temperature rise transient state), the difference between the exhaust temperature and the catalyst temperature is large, so the catalyst temperature is well controlled It is difficult to do (see FIG. 3).

  In particular, since the temperature of the catalyst starts to rise from its upstream end at the early stage of temperature rise, the catalyst temperature distribution is high at the upstream end of the catalyst and low at the downstream end. For this reason, the temperature at the upstream end of the catalyst is considerably higher than the exhaust temperature at the upstream or downstream side of the catalyst, and the HC supply is performed so that the target HC supply amount set based on such exhaust temperature is reached. If it does, it will become easy to overheat a catalyst especially the upstream edge part (refer FIG. 3), and the malfunction that a catalyst deteriorates that much arises.

  An object of the present invention is to provide a temperature increase control device for an aftertreatment device that suppresses excessive temperature rise of the catalyst at the initial stage of catalyst temperature rise due to HC supply to the exhaust purification catalyst of the aftertreatment device.

  In order to achieve the above object, an invention according to claim 1 is directed to a temperature increase control device for an aftertreatment device that is disposed in an exhaust pipe of an engine and includes a diesel particulate filter (DPF) and an exhaust purification catalyst. Based on the temperature of the upstream end portion of the exhaust purification catalyst detected by the HC, the HC supply amount setting means sets the target HC supply amount at the initial stage of temperature rise, and the HC supply means sets the target HC supply amount based on the target HC supply amount. It is characterized in that HC is supplied into the exhaust gas on the upstream side.

  According to a second aspect of the present invention, in the first aspect, the HC supply amount setting means has a target HC supply amount at the time of maintaining the temperature rise based on the temperature of the central portion of the exhaust purification catalyst detected by the central temperature sensor in the catalyst. Is set.

In the first aspect of the invention, since the target HC supply amount at the initial stage of temperature rise is set based on the upstream temperature in the catalyst, the HC supply amount into the exhaust gas on the upstream side of the exhaust purification catalyst of the aftertreatment device is set to It can be precisely controlled according to the actual catalyst temperature at the side end, and it is possible to reliably prevent the excessive temperature rise at the upstream end of the catalyst that is likely to occur at the beginning of the temperature rise.
That is, when the temperature rises due to the supply of HC, the temperature of the exhaust purification catalyst rises from its upstream end, and then the temperature of the center or downstream end of the catalyst rises. ), The temperature rise at the upstream end of the catalyst is remarkable, and if the HC supply amount is excessive, the temperature at the upstream end of the catalyst is easily overheated. In this respect, the upstream temperature sensor in the catalyst is provided at the upstream end of the catalyst inside the catalyst, and the output of the sensor reflects the temperature at the upstream end of the catalyst satisfactorily. By setting the target HC supply amount based on this sensor output (intra-catalyst upstream temperature), it is possible to prevent excessive temperature rise at the upstream end of the catalyst at the initial stage of temperature rise (see FIG. 2).

According to the second aspect of the present invention, the target HC supply amount at the time of maintaining the temperature rise is set based on the center temperature in the catalyst according to the first aspect, so that the catalyst temperature at the time of maintaining the temperature rise is well maintained at the target temperature. be able to.
That is, after the temperature rise of the catalyst is performed without overheating the upstream end of the catalyst by the initial temperature rise control according to the invention of claim 1, the control at the time of maintaining the temperature rise according to the invention of claim 2 is performed. Be started. Even when this temperature rise is maintained (middle to late period of temperature rise transient), the exhaust temperature on the upstream side or downstream side of the catalyst does not necessarily represent the catalyst temperature well, and the exhaust temperature and the catalyst temperature are large. Due to the difference, the control responsiveness when HC supply control (catalyst temperature control) is performed based on the exhaust temperature is not good, and it is difficult to stably maintain the catalyst temperature at the target temperature (catalyst downstream). FIG. 3 shows that the catalyst temperature (in-catalyst center temperature) fluctuates greatly in the case of temperature increase control based on the exhaust temperature on the exhaust side. In this respect, the center temperature sensor in the catalyst is provided in the center of the catalyst inside the catalyst, and the output of the sensor reflects the temperature in the center of the catalyst, that is, the catalyst temperature, and therefore the target HC supply amount when maintaining the temperature rise. Is set on the basis of the sensor output (center temperature in the catalyst), the control responsiveness when maintaining the temperature rise can be improved and the catalyst temperature can be stably maintained at the target temperature (see FIG. 2).

  When the temperature rise is maintained, the upstream end of the catalyst is cooled by the inflow of exhaust gas, so the temperature detected by the upstream temperature sensor in the catalyst is lower than the actual catalyst temperature (center temperature in the catalyst). The catalyst center temperature sensor output reflects the actual catalyst temperature better than the catalyst upstream temperature sensor output. Therefore, the target HC supply amount for maintaining the temperature rise should be set based on the catalyst center temperature sensor output. Therefore, better catalyst temperature control can be performed.

Hereinafter, with reference to the drawings, a temperature increase control device for a post-processing apparatus according to an embodiment of the present invention will be described.
In FIG. 1, reference numeral 1 indicates an engine, for example, a common rail type diesel engine, and reference numeral 10 indicates an electronic control unit (hereinafter referred to as an ECU) that forms a main part of the engine control device and the temperature raising control device.

  Although not shown in detail, the common rail diesel engine 1 is provided with a fuel injector having a needle valve and a fuel chamber and a control chamber provided on the distal end side and the proximal end side of the needle valve for each cylinder. The control chamber is connected to the pressure accumulation chamber via a fuel passage, and the control chamber is connected to the fuel tank via a fuel return passage. Under the control of the ECU 10, when the solenoid valve provided in the fuel injector is opened, the high-pressure fuel supplied from the pressure accumulating chamber is injected into the combustion chamber of the engine 1 through the fuel injector, and when the solenoid valve is closed, the fuel injection is finished. Thus, the fuel injection start / end timing (fuel injection amount) is adjusted by controlling the opening / closing timing of the solenoid valve.

  The engine 1 has an intake pipe 12 connected to an intake manifold 11 and an exhaust pipe 14 connected to an exhaust manifold 13. In the middle of the intake pipe 12, a compressor 21, an intercooler 31, and an intake throttle valve 32 of the supercharger 20 are arranged. The opening degree of the intake throttle valve 32 is variably adjusted by the ECU 10 via the intake throttle valve drive unit 33. The exhaust temperature can be raised by reducing the opening of the intake throttle valve 32. On the other hand, a turbine 22 of the supercharger 20, an exhaust brake 15, a light oil addition injector 50, an aftertreatment device 40 and a muffler (not shown) are provided in the middle of the exhaust pipe 14.

  The compressor 21 and the turbine 22 of the supercharger 20 are connected so as to be able to rotate synchronously, and the compressor 21 is rotated by the rotational force of the turbine 22 generated by the flow of exhaust gas discharged from the engine 1 and is pressurized by the compressor 21. Intake air is supplied to the engine 1. At this time, the pressurized and heated air is cooled by the intercooler 31, thereby increasing the density of the intake air and improving the charging efficiency to increase the engine output.

  The supercharger 20 is provided with an exhaust bypass passage (not shown) for bypassing the turbine 22, and the waste gate 23 of the supercharger 20 provided in the middle of the bypass passage is connected by the ECU 10 via the waste gate drive unit 24. By controlling the opening and closing, the pressure of the intake air supplied to the intake pipe 12 is increased or decreased by increasing or decreasing the turbine rotation (compressor rotation). The exhaust gas temperature can be raised by opening the supercharger wastegate 23. Similarly, the exhaust brake 15 can be opened and closed by the ECU 10 via the exhaust brake drive unit 16, and the exhaust gas temperature can be raised by closing the exhaust brake 15.

  In FIG. 1, reference numeral 36 indicates an EGR passage extending from the exhaust manifold 13 to the intake pipe 12, and a part of the exhaust gas is supplied to the engine 1 as a recirculation gas via the EGR passage 36. In the middle of the EGR passage 36, an EGR cooler 37 that cools the recirculation gas to increase the gas filling density of the engine 1 and an EGR valve 38 for supplying and shutting off the recirculation gas to the engine 1 are provided. ing. The EGR valve 38 is controlled to be opened or closed or adjusted by the ECU 10 via the EGR valve drive unit 39.

  The aftertreatment device 40 reduces NOx and PM contained in the exhaust gas flowing into the aftertreatment device 40. The post-processing device 40 of the present embodiment is a diesel particulate filter (DPF) 41 that collects PM and burns and removes it, and light oil (HC) that is disposed in front of the DPF 41 and supplied from the light oil addition injector 50 as a reducing agent. And a NOx storage catalyst (exhaust gas purification catalyst) 42 for purifying NOx in the exhaust gas, and a post-stage catalyst 43 that is disposed downstream of the DPF 41 and oxidizes excess HC, for example.

The light oil addition injector 50 injects light oil (HC) to the NOx storage catalyst 42 and is controlled to be opened and closed by the ECU 10 via the light oil addition injector drive unit 51. At this time, the light oil addition injector 50 is controlled. Is determined based on, for example, the engine speed, the fuel injection amount, and the deviation between the target catalyst temperature and the actual catalyst temperature.
In FIG. 1, reference numeral 61 denotes an in-catalyst upstream exhaust temperature sensor (intra-catalyst upstream temperature sensor) provided at the upstream end (front) of the catalyst 42 in the exhaust gas flow direction inside the NOx storage catalyst 42. There is a temperature detection end that passes through a hole (not shown) formed in the upstream end portion of the NOx storage catalyst 42 and detects the exhaust temperature (catalyst temperature) at the upstream end portion of the NOx storage catalyst 42. ing. Reference numeral 62 is an in-catalyst center exhaust temperature sensor (in-catalyst center temperature sensor) provided at the center of the catalyst 42 inside the NOx storage catalyst 42, and is formed at the center of the NOx storage catalyst 42. It has a temperature detection end through which a hole (not shown) is inserted, and detects the exhaust temperature (catalyst temperature) at the center of the NOx storage catalyst 42. The catalyst temperature data (actual catalyst temperature) detected by the temperature sensors 61 and 62 is used for catalyst temperature control.

Further, various sensors such as a load sensor 71 and a crank angle sensor 72 are connected to the ECU 10. The load sensor 71 detects the amount of depression of an accelerator pedal (not shown), that is, the accelerator opening as an engine load, and the crank angle sensor 72 detects the rotation of the crankshaft (not shown) of the engine 1 as the engine speed. .
The ECU 10 determines the operating region of the engine 1 based on the engine load detected by the load sensor 71 and the engine speed detected by the crank angle sensor 72, and each injector (illustrated) of the engine 1 according to the engine operating region. The fuel injection timing and the fuel injection amount are controlled by turning on and off the abbreviated solenoid valve.

  The diesel engine 1 configured as described above is operated at a lean air-fuel ratio as is well known, and during this lean air-fuel ratio operation, NOx (nitrogen oxide) contained in the exhaust gas discharged from the engine 1 is stored in the NOx storage catalyst 42. Is done. When the NOx occlusion amount increases to a certain level or more, the rich spike operation of the engine 1 is performed, and the NOx occluded in the NOx occlusion catalyst 42 is released and reduced and removed. Further, if the NOx storage catalyst 42 is poisoned by sulfur due to sulfur contained in the fuel, the exhaust gas purification action of the NOx storage catalyst 42 is reduced, so the S purge that reduces and removes the S component adsorbed on the NOx storage catalyst 42. The exhaust temperature (catalyst temperature) such as retarding the fuel injection timing or injecting additional fuel in the latter half of the expansion stroke and further turning on the intake / exhaust actuators such as the exhaust brake 15 and the turbocharger wastegate 23 ) To increase the temperature).

In addition, in order to reduce the amount of PM contained in the exhaust gas into the atmosphere, PM is collected by the DPF 41. When the amount of PM collected increases to a certain level or more, the engine increases due to the exhaust pressure increase due to clogging of the DPF 41. Since there is a possibility that the operation performance is lowered, the temperature rise control is performed in order to regenerate the DPF 41 by burning and removing the collected PM.
In the present embodiment, when controlling the temperature rise during the S purge of the NOx storage catalyst 42 or during the regeneration of the DPF 41, the diesel fuel addition injector 50 is periodically opened, for example, at a predetermined duty ratio under the control of the ECU 10 to enter the exhaust gas. Light oil (HC) is injected, whereby HC is supplied to increase the exhaust gas temperature (catalyst temperature). In order to further accelerate the exhaust gas temperature rise, intake and exhaust actuators such as the exhaust brake 15, the waste gate 23, the intake throttle valve 32, the EGR valve 38, etc. are closed, for example, by closing the exhaust brake 15 and opening the supercharger waste gate 23. The exhaust gas flow rate may be controlled to decrease.

  Although the above temperature rise control itself is basically the same as conventional temperature rise control, the present invention sets the target HC supply amount in the initial stage of temperature rise by HC supply (initial stage of temperature rise transient state) in the catalyst. It is set based on the output of the upstream temperature sensor 61 (upstream temperature in the catalyst), and the target HC supply amount at the time of maintaining the temperature rise (middle or final temperature rise state) is output from the center temperature sensor 62 in the catalyst (center in the catalyst). It is characterized in that it is set based on (temperature).

  In relation to the above temperature increase control, as shown in FIG. 1, the ECU 10 includes a temperature sensor selection unit 101 connected to the in-catalyst upstream temperature sensor 61 and the in-catalyst center temperature sensor 62. As illustrated in FIG. 2, the temperature sensor selection unit 101 increases the temperature until the upstream temperature in the catalyst detected by the temperature sensor 61 becomes a predetermined temperature lower than the central temperature in the catalyst detected by the temperature sensor 62. Is connected to the target HC supply amount setting unit 102, or the catalyst upstream temperature data from the temperature sensor 61 is supplied to the setting unit 102, while the temperature sensor 61 When the in-catalyst upstream temperature detected by the above becomes a predetermined temperature lower than the in-catalyst center temperature detected by the temperature sensor 62, it is determined that the initial temperature rise has ended, and the in-catalyst center temperature sensor 62 is supplied to the target HC. The center temperature data in the catalyst from the temperature sensor 62 is connected to the amount setting unit 102 or supplied to the setting unit 102.

  In FIG. 2, a broken line and a solid line indicate the upstream temperature in the catalyst and the central temperature in the catalyst detected by the upstream exhaust temperature sensor 61 in the catalyst and the central exhaust temperature sensor 62 in the catalyst (here, the upstream of the catalyst in the NOx storage catalyst 42). The exhaust gas temperature at the side end and the center), and the alternate long and short dashed lines indicate the catalyst outlet gas temperature and the catalyst inlet gas temperature. In FIG. 2, a part of the broken line indicating the upstream temperature in the catalyst is thickened to indicate that the temperature increase control in the initial temperature increase is performed based on the upstream temperature in the catalyst, and the center temperature in the catalyst is indicated. The thickening of a part of the solid line indicates that the temperature rise control during the temperature rise maintenance is performed based on the center temperature in the catalyst.

  The HC supply amount setting unit 102 of the present embodiment, for example, based on the engine speed, the fuel injection amount, and the deviation between the target catalyst temperature and the actual catalyst temperature detected by the temperature sensor 61 or 62, The amount (here, the target injection amount of light oil from the light oil addition injector 50) is set. For example, the basic HC supply amount set according to the engine speed and the fuel injection amount is corrected with a correction amount set according to the deviation between the target catalyst temperature and the actual catalyst temperature to obtain the target HC supply amount. ing. Then, the light oil addition injector driving unit 51 operates in accordance with the target light oil injection amount (target HC supply amount), whereby a target amount of light oil (HC) is injected from the light oil addition injector 50 (HC supply means). .

When the temperature rises due to the supply of HC, the temperature of the NOx storage catalyst 42 rises from its upstream end, and then the temperature of the center or downstream end of the catalyst 42 rises. The temperature rise at the upstream end of the catalyst 42 becomes significant. Accordingly, in general, the amount of HC supplied becomes excessive, and the temperature at the upstream end of the catalyst tends to be excessively high.
For example, as shown in FIG. 3, when HC supply control is performed based on the catalyst outlet gas temperature, the initial HC supply amount of the temperature increase due to HC supply becomes excessive, and the upstream end of the catalyst is excessively heated. End up.

  In FIG. 3, the one-dot chain line and the two-dot chain line indicate the catalyst outlet gas temperature and the catalyst inlet gas temperature detected by the temperature sensors (both not shown) of the catalyst, respectively, and the solid line and the broken line indicate the catalyst. The inner center temperature and the catalyst upstream temperature (for example, the exhaust gas temperature at the center and upstream end of the catalyst inside the catalyst) are shown. In FIG. 3, the temperature increase control is performed based on the catalyst outlet gas temperature by thickening the one-dot chain line indicating the catalyst outlet gas temperature.

  In the initial stage of the temperature rise due to the supply of HC, the NOx storage catalyst 42 rises in temperature from its upstream end, and then the temperature at the center or downstream end of the catalyst 42 rises. The catalyst temperature, particularly the temperature at the upstream end of the catalyst (upstream temperature in the catalyst) increases with a considerable delay, and therefore the catalyst outlet temperature does not represent the actual catalyst temperature. Nevertheless, if HC supply control is performed based on the catalyst outlet gas temperature as in FIG. 3, the amount of HC supplied to the catalyst becomes excessive, and the upstream temperature in the catalyst increases as shown in FIG. That is, the temperature at the upstream end of the catalyst is overheated and the catalyst is deteriorated. In particular, in the case of a NOx storage catalyst, if even a part of the catalyst is deteriorated due to excessive temperature rise, a reduction in the NOx purification performance of the catalyst becomes a problem.

  In this respect, the temperature increase control device of the present invention sets the target HC supply amount at the initial temperature increase based on the output of the in-catalyst upstream temperature sensor 61 (intra-catalyst upstream temperature), and the upstream end of the NOx storage catalyst 42. This prevents overheating of the part. The temperature sensor 61 is provided at the upstream end of the catalyst inside the NOx storage catalyst 42, and the sensor output reflects the actual temperature at the upstream end of the catalyst satisfactorily. Therefore, according to the HC supply control based on the output of the temperature sensor 61, the amount of HC supplied into the exhaust gas on the upstream side of the NOx storage catalyst 42 can be precisely controlled, and the upstream end portion of the catalyst 42 can be controlled. It is possible to reliably prevent overheating.

In the present invention, the control at the time of maintaining the temperature rise is started after the initial stage of the temperature rise of the catalyst is completed. As described above, the control at the time of maintaining the temperature rise is based on the output of the center temperature sensor 62 in the catalyst. The target HC supply amount at the time of maintaining the temperature is set so that the catalyst temperature at the time of maintaining the temperature rise is well maintained at the target temperature.
Conventionally, as shown in FIG. 3, temperature increase control based on the exhaust temperature on the downstream side of the catalyst is sometimes performed, but in this case, it is difficult to stably maintain the catalyst temperature at the target temperature. That is, not only in the early stage of temperature rise, but also in the temperature rise maintenance (middle to late stage of temperature rise transient), the exhaust temperatures on the upstream side and downstream side of the catalyst are not necessarily representative of the catalyst temperature. Because the exhaust temperature and the catalyst temperature are significantly different from each other, the control responsiveness when HC supply control (catalyst temperature control) is performed based on the exhaust temperature is not good, and the catalyst temperature is stably maintained at the target temperature. Because it becomes difficult to do.

  In this regard, in the present invention, the in-catalyst center temperature sensor 62 is provided in the center of the catalyst 42 inside the NOx storage catalyst 42, and the output of the sensor 62 favorably reflects the temperature in the center of the catalyst, that is, the catalyst temperature. Therefore, by setting the target HC supply amount when maintaining the temperature rise based on this sensor output, as shown in FIG. 2, the control responsiveness when maintaining the temperature rise is improved and the catalyst temperature is stabilized at the target temperature. Can be maintained.

  When the temperature rise is maintained, the upstream end of the NOx storage catalyst 42 is cooled by the inflow of exhaust gas, so that the temperature detected by the catalyst upstream temperature sensor 61 is lower than the actual catalyst temperature (catalyst center temperature). Therefore, the output of the in-catalyst center temperature sensor 62 better reflects the actual catalyst temperature than the output of the in-catalyst upstream temperature sensor 61. Therefore, the target HC supply amount at the time of maintaining the temperature rise is determined as the in-catalyst center temperature. By setting based on the sensor output, better catalyst temperature control can be performed.

  As described above, in the temperature increase control by HC supply according to the present invention, the HC supply amount is finely controlled, and the total HC supply amount required for temperature increase can be suppressed, so that the fuel consumption is improved. . Further, since the catalyst temperature is finely controlled, the catalyst temperature can be stably maintained at the target temperature. Therefore, the present invention is particularly suitable for performing the S purge of the NOx storage catalyst 42 having strict catalyst temperature requirements. .

Although the description of the temperature increase control device according to the preferred embodiment of the present invention is finished as above, the present invention is not limited to the above embodiment and can be variously modified.
For example, in the above embodiment, the light oil addition injector is used as the HC supply means. However, the present invention is not limited to this. For example, the post-injection in which the additional fuel is injected in the expansion stroke following the main injection is performed in the exhaust pipe. You may make it supply HC. In the above embodiment, the NOx occlusion catalyst is used as the exhaust purification catalyst disposed upstream of the DPF. However, other catalysts such as an oxidation catalyst may be used as the upstream catalyst. Further, it is not essential to provide a post-stage catalyst. In the above embodiment, the end of the initial temperature rise is determined when the upstream temperature in the catalyst becomes a predetermined temperature lower than the central temperature in the catalyst. However, the present invention is not limited to this. For example, the upstream temperature in the catalyst is It may be determined that the initial temperature increase has ended when the temperature becomes equal to the center temperature in the catalyst, or the end of the initial temperature increase may be determined when a predetermined time has elapsed from the start of the temperature increase. good. In addition, the present invention can be variously modified within the scope of the invention.

It is the schematic which shows the temperature rising control apparatus of the post-processing apparatus by one Embodiment of this invention. FIG. 2 is a diagram showing temporal changes in the upstream temperature and the central temperature in the catalyst, which are the basis of the temperature increase control by the temperature increase control device shown in FIG. 1, together with the time changes in the catalyst inlet gas temperature and the catalyst outlet gas temperature. . It is a figure which shows the time change of the catalyst exit gas temperature used as the foundation of the conventional temperature rising control with the time change of a catalyst inlet gas temperature, the upstream temperature in a catalyst, and the center temperature in a catalyst.

Explanation of symbols

1 engine 10 ECU
40 Post-processing equipment 41 DPF
42 NOx storage catalyst 50 Light oil addition injector (HC supply means)
61 In-catalyst upstream temperature sensor 62 In-catalyst center temperature sensor 101 Temperature sensor selection unit 102 Target HC supply amount setting unit (HC supply amount setting means)

Claims (2)

In a temperature increase control device for an aftertreatment device that is disposed in an exhaust pipe of an engine and has a diesel particulate filter and an exhaust purification catalyst,
An in-catalyst upstream temperature sensor that detects the temperature of the upstream end of the exhaust purification catalyst, and an HC supply amount setting that sets a target HC supply amount at the initial stage of temperature rise based on the temperature detected by the in-catalyst upstream temperature sensor And a HC supply means for supplying HC into the exhaust gas on the upstream side of the exhaust purification catalyst based on the target HC supply amount.   A catalyst center temperature sensor for detecting the temperature of the center of the exhaust purification catalyst; and the HC supply amount setting means is configured to detect a target HC at the time of maintaining the temperature rise based on the temperature detected by the catalyst center temperature sensor. The temperature increase control device for a post-processing device according to claim 1, wherein a supply amount is set.

Images