JP4779785B2 - Engine exhaust system temperature control device - Google Patents

Description

  The present invention relates to an exhaust system temperature control device for an engine that increases the temperature of an exhaust system through control of an auxiliary machine.

As an engine exhaust system temperature control device, for example, a device described in Patent Document 1 is known. When there is a request to remove particulate matter (PM) deposited on the filter of a diesel engine equipped with an exhaust emission control device, this temperature control device controls the fuel injection amount by energizing the glow plug. I try to increase the amount. As a result, the exhaust gas temperature is raised, and the removal of PM accumulated on the filter is promoted.
JP 2005-90249 A

  By the way, in the engine equipped with the exhaust system temperature control device of Patent Document 1, the glow plug is always energized when the execution condition of the control for removing PM is satisfied. There is a concern that it may lead to a decrease in the service life. Therefore, proposals for measures that can contribute to the improvement of the lifetime of glow plugs are desired, but so far no proposals have been made to meet such requirements. Note that the exhaust system temperature control device is not limited to an exhaust system temperature control device applied to an engine equipped with an exhaust purification device, and an exhaust system temperature control device that increases the temperature of the exhaust system by using an increase in fuel injection amount accompanying the drive of an auxiliary machine. If so, it can be said that it is desirable to take measures for the life of the auxiliary machine as well.

  The present invention has been made in view of such a situation, and an object of the present invention is to improve the life of an auxiliary machine that is driven based on a request to increase the temperature of an exhaust system. An object of the present invention is to provide an exhaust system temperature control device for an engine.

In the following, means for achieving the above object and its effects are described.
(1) According to the first aspect of the invention, the injection control for correcting the fuel injection amount to the increase side based on the drive of the glow plug is performed, and the temperature of the exhaust system is raised, so that it accumulates in the exhaust purification device. The engine is applied to an engine that is configured on the condition that regeneration control for burning the particulate matter being performed is performed, and the glow plug is driven based on the execution condition of the regeneration control being satisfied. In the exhaust system temperature control device, a temperature at which the exhaust system temperature is expected not to reach a required value even when the glow plug is driven is defined as a boundary temperature, and when the exhaust system temperature is less than the boundary temperature, The gist is to prohibit the driving of the glow plug based on the establishment of the execution condition, and to set the boundary temperature based on an allowable continuous energization time of the glow plug. To have.

In the above invention, when it is estimated that the driving of the glow plug does not contribute to the demand for the temperature of the exhaust system, the driving of the auxiliary machine is inhibited by prohibiting the driving of the auxiliary machine. As a result, the life of the glow plug driven based on the request to increase the temperature of the exhaust system can be improved. On the other hand, in the engine, the period during which the temperature of the exhaust system can be raised by driving the glow plug differs depending on the allowable continuous energization time of the glow plug. Therefore, in order for the glow plug drive to contribute more appropriately to the demand for the temperature of the exhaust system, it is desirable to set the glow plug drive mode in consideration of the continuous energization allowable time. It is done. In the invention described in the above claims, the boundary temperature is set on the basis of the allowable continuous energization time in consideration of the above, so that the glow plug is more suitable for the demand for the temperature of the exhaust system. Will be able to contribute.

(2) The invention according to claim 2 is the engine exhaust system temperature control device according to claim 1, wherein the exhaust purification device includes a catalyst capable of oxidizing the additive. And the regeneration control uses the catalyst temperature as the exhaust system temperature, the catalyst temperature threshold set in advance for classifying the active state of the catalyst as the required value, and the catalyst temperature as The additive is supplied into the exhaust gas in an amount suitable for the active state of the catalyst based on being equal to or higher than the required value, and the boundary temperature is a continuous value of the glow plug in a region below the required value. The gist is that it is set in a direction approaching the required value as the energization allowable time becomes shorter.

In the engine, as the allowable continuous energization time of the glow plug becomes shorter, the period during which the exhaust temperature can be raised by driving the glow plug becomes shorter. Therefore, in order to allow the drive of the glow plug to contribute more favorably to raising the temperature of the catalyst to a temperature higher than the required value, the boundary temperature and the required value are set according to the continuous energization time. It may be desirable to change the relationship. In the invention described in the above claims, in consideration of the above, the boundary temperature is made closer to the required value as the allowable continuous energization time is shortened. Therefore, the temperature of the catalyst is increased to a temperature higher than the required value. On the other hand, the driving of the glow plug can contribute more favorably.

(3) In the invention according to claim 3, the fuel injection amount is corrected to the increase side when the glow plug is driven, and the amount of particulate matter deposited in the exhaust purification device is a predetermined amount. In an engine control apparatus on condition that regeneration control for burning the particulate matter is performed at the above time, and in an exhaust system temperature control apparatus for an engine that drives the glow plug when the regeneration control is performed The glow plug is driven when the temperature of the exhaust system is within a specific range, and the size of the specific range when the continuous energization allowable time of the glow plug is the allowable time A and the continuous energization of the glow plug are allowed. The gist is to make the size of the specific range different from each other when the allowable time B is longer than the allowable time A.

(4) The invention according to claim 4 is the engine exhaust system temperature control device according to claim 3, wherein a catalyst capable of oxidizing the additive is provided in the exhaust purification device, and In the regeneration control, the engine control device further includes a condition that the additive is supplied into the exhaust when the temperature of the catalyst as the temperature of the exhaust system is equal to or higher than a required value, and the specific range , When the temperature of the exhaust system is equal to or higher than the boundary temperature, the glow plug is driven, and the boundary when the allowable continuous energization time of the glow plug is the allowable time A The difference between the temperature and the required value is a temperature difference A, and the difference between the boundary temperature and the required value when the continuous energization allowable time of the glow plug is the allowable time B is the temperature difference B. Temperature difference A is summarized in that to set the boundary temperature to be smaller than the temperature difference B.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the present invention is specifically described as an apparatus for increasing the temperature of an exhaust system based on a request for purifying PM in a diesel engine (engine 1) equipped with an exhaust purification apparatus for purifying particulate matter (PM). It has become.

<Diesel engine structure>
FIG. 1 shows a schematic structure of an engine 1 to which an exhaust system temperature control device of the present invention is applied.
The engine 1 is configured by a combination of a cylinder block 11 and a cylinder head 12. The fuel supply device 5, the exhaust gas recirculation device 6, and the exhaust gas purification device 7 are provided. In addition, an electronic control unit 9 is provided for comprehensively controlling various devices. The exhaust system temperature control device includes the electronic control device 9.

  A plurality of cylinders 13 are provided in the cylinder block 11. Each cylinder 13 is formed with a combustion chamber 14 for burning a mixture of air and fuel. The cylinder head 12 is provided with an injector 51 that directly injects fuel into each combustion chamber 14 and a glow plug 15 that heats the combustion chamber 14 and fuel.

  An intake manifold 21 is connected to the intake port of the cylinder head 12. An intake pipe 22 is connected to the collecting pipe of the intake manifold 21. In the engine 1, an intake passage 23 for circulating external air to each combustion chamber 14 is formed by a passage in the intake pipe 22 and a passage in the intake manifold 21. An exhaust manifold 24 is connected to the exhaust port of the cylinder head 12. An exhaust pipe 25 is connected to the collecting pipe of the exhaust manifold 24. In the engine 1, an exhaust passage 26 for circulating the combustion gas in the combustion chamber 14 to the outside is formed by a passage in the exhaust manifold 24 and a passage in the exhaust pipe 25.

  In the intake passage 23, an air cleaner 31, a compressor wheel 35 of a turbocharger 34, an intercooler 32, and a throttle valve 33 are arranged in order from the upstream side in the air flow direction. In the exhaust passage 26, a sub-injector 71 of the exhaust purification device 7, a turbine wheel 36 of the turbocharger 34, a NOx catalytic converter 72 and a catalyst-carrying filter 73 of the exhaust purification device 7 are arranged in order from the upstream side in the exhaust flow direction. Has been. In the present embodiment, the NOx catalytic converter 72 corresponds to the first purification device. The catalyst-carrying filter 73 corresponds to the second purification device.

  The fuel supply device 5 is configured as a common rail device capable of injecting high-pressure fuel into the combustion chamber 14. Specifically, the injector 51, the fuel tank 52, the fuel pump 53, and the common rail 54 are included. The injector 51 injects fuel directly into the combustion chamber 14. The fuel pump 53 sucks the fuel in the fuel tank 52, pressurizes the fuel to a predetermined pressure, and supplies the fuel to the common rail 54. The common rail 54 maintains the fuel supplied from the fuel pump 53 in a high pressure state. The fuel in the common rail 54 is injected into the corresponding combustion chamber 14 as each injector 51 opens.

  The exhaust gas recirculation device 6 is configured as a device that can reduce the generation amount of nitrogen oxides by performing exhaust gas recirculation (so-called EGR) for supplying a part of the exhaust gas into the intake pipe 22. Specifically, an EGR pipe 61, an EGR cooler 62, and an EGR valve 63 are included. The EGR pipe 61 communicates the exhaust passage 26 upstream of the turbine wheel 36 and the intake passage 23 downstream of the throttle valve 33. The EGR cooler 62 cools the exhaust gas supplied to the intake pipe 22 via the EGR pipe 61. The EGR valve 63 adjusts the flow rate of the exhaust gas supplied to the intake pipe 22 via the EGR pipe 61.

  The exhaust purification device 7 is configured as a device that can purify particulate matter (PM), nitrogen oxides (NOx), hydrocarbons (HC), and carbon monoxide (CO) in the exhaust. Specifically, it includes a sub-injector 71, a NOx catalytic converter 72, and a catalyst-carrying filter 73.

  The sub-injector 71 injects fuel into the exhaust gas in the collecting pipe of the exhaust manifold 24. The sub-injector 71 is supplied with fuel having a lower pressure than the fuel supplied to the common rail 54 through the fuel pump 53. The fuel injected through the sub-injector 71 is supplied to the NOx catalytic converter 72 and the catalyst-carrying filter 73 together with the exhaust gas.

  The NOx catalytic converter 72 includes a catalyst carrier on which an NOx storage reduction catalyst is supported. NOx in the exhaust is stored in the NOx catalyst when the exhaust is in an oxidizing atmosphere (lean). On the other hand, NOx occluded in the NOx catalyst is released as nitrogen monoxide (NO) and reduced by HC or CO when the exhaust is in a reducing atmosphere (stoichiometric or rich). “Stoichi” is the state where the air-fuel ratio of the exhaust corresponds to the stoichiometric air-fuel ratio, “Lean” is the state where the air-fuel ratio of the exhaust is larger than the stoichiometric air-fuel ratio, “Rich” is the state where the air-fuel ratio of the exhaust is the stoichiometric air-fuel ratio Each smaller state is shown.

  The catalyst-carrying filter 73 includes a porous ceramic structure (PM filter) that can capture PM in the exhaust gas. The PM filter carries a NOx storage reduction catalyst. The PM in the exhaust is trapped by the wall of the structure as the exhaust passes through the porous ceramic structure. On the other hand, PM trapped in the ceramic structure is oxidized by oxygen in the exhaust when the exhaust is hot. It is also oxidized by active oxygen generated during NOx storage and release. The catalyst-carrying filter 73 also purifies NOx in the same manner as the NOx catalytic converter 72.

  In addition to the above devices, the engine 1 is provided with an alternator 16 that generates power through the torque of the crankshaft. The electric power generated by the alternator 16 is supplied to the vehicle battery 17. Auxiliaries such as the injector 51, the glow plug 15, the sub-injector 71, and the throttle valve 33 are driven by the power of the battery 17.

  The electronic control unit 9 temporarily stores a central processing unit that executes arithmetic processing related to engine control, a read-only memory in which programs and maps necessary for engine control are stored in advance, calculation results of the central processing unit, etc. A random access memory, an input port for inputting an external signal, an output port for outputting a signal to an external device, and the like. A crank position sensor 91, a throttle position sensor 92, an inlet exhaust temperature sensor 93, an outlet exhaust temperature sensor 94, and the like for detecting the operating state of the engine 1 are connected to the input port. An injector 51, a glow plug 15, a sub-injector 71, a throttle valve 33, and the like are connected to the output port.

  The crank position sensor 91 is provided in the vicinity of the crankshaft of the engine 1 and outputs a power signal corresponding to the rotation angle of the crankshaft (crank rotation angle CA). The output signal of the crank position sensor 91 is input to the electronic control unit 9 and then used for various controls as a crank rotation angle measurement value CAM. The electronic control unit 9 calculates the rotation speed of the crankshaft (engine rotation speed NE) based on the crank rotation angle measurement value CAM.

  The throttle position sensor 92 is provided in the vicinity of the throttle valve 33 and outputs an electrical signal corresponding to the opening of the throttle valve 33 (throttle opening TA). The output signal of the throttle position sensor 92 is input to the electronic control unit 9, and then used as a throttle opening measurement value TAM for various controls.

  The inlet exhaust temperature sensor 93 is provided in the exhaust passage 26 downstream of the NOx catalytic converter 72 and upstream of the catalyst-carrying filter 73, and has an exhaust gas temperature (inlet exhaust gas temperature TGI) immediately before flowing into the catalyst-carrying filter 73. A corresponding electrical signal is output. The output signal of the inlet exhaust temperature sensor 93 is input to the electronic control unit 9 and is then used for various controls as the inlet exhaust temperature measured value TGIM.

  The outlet exhaust temperature sensor 94 is provided in the exhaust passage 26 downstream of the catalyst-carrying filter 73 and in the vicinity of the catalyst-carrying filter 73, and the exhaust gas temperature immediately after passing through the catalyst-carrying filter 73 (exit exhaust gas temperature TGO). ) Is output. The output signal of the outlet exhaust temperature sensor 94 is input to the electronic control unit 9 and is then used for various controls as the outlet exhaust temperature measured value TGOM.

  The electronic control unit 9 is a throttle control that adjusts the opening degree of the throttle valve 33 based on the engine operating state that is grasped through the output signals of the respective sensors, a fuel injection control that adjusts the fuel injection amount by the injector 51, Various controls such as auxiliary fuel injection control for adjusting the fuel injection amount by the sub-injector 71 and charging control for adjusting the power generation amount of the alternator 16 are performed.

  In the fuel injection control, basically, a basic value (basic injection amount Fbse) of the fuel injection amount is set based on the engine speed NE and the throttle opening degree TA. Further, when the load on the engine 1 increases due to the driving of the auxiliary machine, the correction amount (corrected injection amount Fadd) of the fuel injection amount is set according to the magnitude of the load. When the corrected injection amount Fadd is set, the injection amount obtained by adding the basic injection amount Fbse and the corrected injection amount Fadd is set as the final fuel injection amount of the injector 51 (final injection amount Ffin). On the other hand, when the correction injection amount Fadd is not set, the basic injection amount Fbse is set as the final fuel injection amount of the injector 51 (final injection amount Ffin).

  In the charge control, the power generation amount of the alternator 16 is set based on the power consumption of the battery 17 by driving the electric auxiliary machine (glow plug 15 or the like). Specifically, the power generation amount of the alternator 16 is set to increase as the power consumption of the battery 17 increases. Therefore, since the load applied from the alternator 16 to the engine 1 increases as the power consumption of the battery 17 increases, the correction injection amount Fadd is set to increase accordingly. The electric auxiliary machine is an auxiliary machine that is driven by being supplied with electric power from the battery 17.

  As described above, in the engine 1, the correction injection amount Fadd corresponding to the magnitude of the load applied to the engine 1 by the alternator 16 when the electric auxiliary machine is driven is added to the basic injection amount Fbse. The final injection amount Ffin of the injector 51 is set to a larger value than when the machine is not driven. For example, when energization of the glow plug 15 is being performed, the final injection amount Ffin of the injector 51 corresponds to at least the amount of power consumed by the glow plug 15 compared to when the energization of the glow plug 15 is not being performed. It is set to a larger value.

<Outline of playback control>
In the engine 1, since the pressure loss increases as the amount of PM trapped in the catalyst-carrying filter 73 increases, the PM accumulated on the filter 73 is removed before the operating state deteriorates. Is required. Therefore, when it is estimated that the amount of PM deposited on the catalyst-carrying filter 73 exceeds the allowable amount, the electronic control unit 9 burns and removes the PM to remove the PM of the catalyst-carrying filter 73. The reproduction control for reproducing the capture capability is executed. Hereinafter, the operation of regenerating the PM trapping ability of the catalyst-carrying filter 73 is appropriately indicated as “filter regeneration”.

  In regeneration control, the temperature of the catalyst-carrying filter 73 (downstream catalyst bed temperature TR) is required for filter regeneration by supplying fuel (additive) into the exhaust gas in a state where the NOx catalyst is sufficiently active. The temperature is raised to a temperature equal to or higher than the temperature (regenerated catalyst bed temperature TRfin (for example, 600 ° C.)). When the fuel supplied into the exhaust is oxidized by the NOx catalytic converter 72, the temperature of the exhaust supplied to the catalyst-carrying filter 73 is raised, so that the downstream catalyst bed temperature TR can be increased. Further, when the fuel supplied into the exhaust gas is oxidized by the catalyst-carrying filter 73, the downstream catalyst bed temperature TR is increased through the heat generated by the oxidation reaction. Further, when the fuel supplied into the exhaust is oxidized in the exhaust upstream of the catalyst-carrying filter 73, the temperature of the exhaust supplied to the catalyst-carrying filter 73 is raised, so the downstream catalyst bed temperature TR Will rise. Hereinafter, the operation of supplying the fuel into the exhaust will be referred to as “fuel addition” as appropriate. As the fuel addition method, mainly (a) a method of executing fuel injection through the sub-injector 71, (b) a method of executing post injection (details will be described later) through the injector 51, and a method of these (a) ( The method of performing in combination with the method of b) is mentioned.

  In a state where the NOx catalyst is sufficiently active, the downstream catalyst bed temperature TR is basically raised to a temperature equal to or higher than the regenerated catalyst bed temperature TRfin by fuel addition regardless of the fuel injection amount in the main injection of the injector 51. It becomes possible to make it. On the other hand, in a state where the NOx catalyst is not sufficiently activated, even if an amount of fuel necessary for raising the downstream catalyst bed temperature TR to the regeneration catalyst bed temperature TRfin or higher is supplied into the exhaust gas, this fuel Is not oxidized on the NOx catalyst, basically the filter regeneration cannot be completed. For this reason, when the amount of PM deposited on the catalyst-carrying filter 73 exceeds the allowable amount, it is required to activate the NOx catalyst sufficiently earlier.

  Therefore, in the regeneration control, when the NOx catalyst is not sufficiently activated in a state where the execution condition is satisfied, after-injection of the injector 51 (details are described) as a process for shifting the NOx catalyst to a sufficiently activated state. The energization of the glow plug 15 is executed in accordance with the addition of a small amount of fuel by the sub-injector 71 (described later). Incidentally, when the glow plug 15 is energized, the fuel injection amount of the injector 51 is increased according to the power generation amount of the alternator 16, thereby increasing the temperature of the exhaust gas sent from the combustion chamber 14 to the exhaust passage 26. Therefore, the downstream catalyst bed temperature TR can be increased. Hereinafter, the operation of energizing the glow plug 15 will be appropriately referred to as “glow energization”.

The type of fuel injection form of the injector 51 will be described.
“Main injection”: The main injection indicates a fuel injection mode of the injector 51 that mainly injects fuel in the compression stroke. That is, the aim is to obtain the expansion force for burning the injected fuel in the combustion chamber 14 to push down the piston.

  “After injection”: After injection indicates a fuel injection mode of the injector 51 that injects fuel during the expansion stroke after the main injection is performed. That is, it is performed with the aim of raising the temperature of the exhaust gas by burning most of the injected fuel in the combustion chamber 14. A part of the fuel injected through the after injection is sent to the exhaust passage 26 together with the exhaust.

  “Post injection”: Post injection indicates a fuel injection mode of the injector 51 that injects fuel during the expansion-exhaust stroke after the after injection. That is, the aim is to send most of the injected fuel to the exhaust passage 26 together with the exhaust gas without burning it in the combustion chamber 14.

The type of fuel addition mode of the sub-injector 71 will be described.
“Basic fuel addition”: The basic fuel addition is a fuel addition mode of the sub-injector 71 that injects an amount of fuel suitable for a state in which the NOx catalyst is in an active state but its activity level is not sufficient (a weakly active state of the NOx catalyst). Indicates. That is, a fuel addition mode in which a small amount of fuel that can be sufficiently oxidized on the NOx catalyst in a weak active state is injected is shown.

  “Regeneration fuel addition”: Regeneration fuel addition indicates a fuel addition mode of the sub-injector 71 that is performed with the aim of raising the downstream catalyst bed temperature TR to a temperature equal to or higher than the regeneration catalyst bed temperature TRfin. That is, a fuel addition mode in which a large amount of fuel that can be sufficiently oxidized on the NOx catalyst in a sufficiently active state is injected is shown. The regenerated catalyst bed temperature TRfin is set as the downstream catalyst bed temperature TR that can sufficiently burn the PM deposited on the catalyst-carrying filter 73.

<About the overview of playback control processing>
With reference to FIGS. 2 and 3, an outline of the “reproduction control process (FIGS. 4 to 6)” will be described.
As shown in FIG. 2, in the “regeneration control process”, the temperature of the NOx catalytic converter 72 (upstream catalyst bed temperature TF) is set to the following (a) to (d), and the exhaust temperature immediately before flowing into the NOx catalytic converter 72 (Reference exhaust gas temperature TG) is divided into the following regions (e) to (h), and after injection and fuel addition are performed based on the temperature region to which the upstream catalyst bed temperature TF and the reference exhaust gas temperature TG belong. A mode is set.
(A) Catalyst bed temperature region FA: less than the first catalyst bed temperature TF1.
(B) Catalyst bed temperature region FB: not less than the first catalyst bed temperature TF1 and less than the second catalyst bed temperature TF2.
(C) Catalyst bed temperature region FC: not less than the second catalyst bed temperature TF2 and less than the third catalyst bed temperature TF3.
(D) Catalyst bed temperature region FD: Third catalyst bed temperature TF3 or higher.
(E) Exhaust temperature region GA: less than the first exhaust temperature TG1.
(F) Exhaust temperature region GB: not less than the first exhaust temperature TG1 and less than the second exhaust temperature TG2.
(G) Exhaust temperature region GC: not less than the second exhaust temperature TG2 and less than the third exhaust temperature TG3.
(H) Exhaust temperature region GD: not less than the third exhaust temperature TG3.

  Specifically, based on the fact that the upstream catalyst bed temperature TF belongs to the catalyst bed temperature region FB and the reference exhaust gas temperature TG belongs to the exhaust gas temperature region GB as the first temperature rise condition, this condition is satisfied. To perform after-injection. Further, based on the fact that this condition is established based on the fact that the upstream catalyst bed temperature TF belongs to the catalyst bed temperature region FC and the reference exhaust gas temperature TG belongs to the exhaust gas temperature region GC, this condition is satisfied. Perform the addition. Further, based on the fact that the upstream catalyst bed temperature TF belongs to the catalyst bed temperature region FD and the reference exhaust gas temperature TG belongs to the exhaust gas temperature region GD as a third temperature rise condition, this condition is satisfied. Perform the addition. The above threshold values for the upstream catalyst bed temperature TF correspond to catalyst temperatures that are set in advance to classify the active state of the catalyst.

Each upstream catalyst bed temperature TF and each reference exhaust gas temperature TG indicating the boundary of each temperature region can be set as follows, for example. In the “regeneration control process” of the present embodiment, the following temperature setting is adopted.
First catalyst bed temperature TF1: 150 ° C
Second catalyst bed temperature TF2: 200 ° C
Third catalyst bed temperature TF3: 260 ° C
・ First exhaust temperature TG1: 150 ° C
Second exhaust temperature TG2: 200 ° C
-Third exhaust temperature TG3: 260 ° C
In the following (A) to (F), each upstream catalyst bed temperature TF and each reference exhaust gas temperature TG indicating the boundary of each temperature region will be described. In the following description, the NOx catalytic converter 72 is targeted, but the same description can be applied to the catalyst-carrying filter 73.

  (A) When the upstream catalyst bed temperature TF is lower than the first catalyst bed temperature TF1, the NOx catalyst is inactive (inactive state of the NOx catalyst), so that the amount of fuel contained in the exhaust gas is very small. However, this fuel is not oxidized on the NOx catalyst. That is, the first catalyst bed temperature TF1 corresponds to a threshold value of the upstream catalyst bed temperature TF for grasping a state in which a small amount of fuel can be oxidized on the NOx catalyst. For this reason, in the state where the upstream catalyst bed temperature TF belongs to the catalyst bed temperature region FA, the execution of after-injection in which the amount of fuel supplied into the exhaust gas is extremely small cannot be permitted. Therefore, in the present embodiment, the first catalyst bed temperature TF1 is stored in advance in the electronic control unit 9 as a value for determining whether or not at least the execution of after-injection is permitted. Yes.

  (B) When the upstream catalyst bed temperature TF is equal to or higher than the first catalyst bed temperature TF1 and lower than the second catalyst bed temperature TF2, the NOx catalyst is in an active state but its activity level is very weak (the NOx catalyst is in a very weak active state) ), When the amount of fuel contained in the exhaust gas is very small, this fuel is sufficiently oxidized on the NOx catalyst, but a larger amount of fuel (small amount of fuel) is contained in the exhaust gas. This fuel is not fully oxidized on the NOx catalyst. That is, the second catalyst bed temperature TF2 corresponds to a threshold value of the upstream catalyst bed temperature TF for grasping a state in which a small amount of fuel can be oxidized on the NOx catalyst. Therefore, in a state where the upstream catalyst bed temperature TF belongs to the catalyst bed temperature region FB, basic fuel addition for supplying a small amount of fuel into the exhaust (and post injection for supplying a small amount of fuel (basic post injection)) is performed. Execution is not allowed. Accordingly, in the present embodiment, the second catalyst bed temperature TF2 is preliminarily set as an electronic control device as a value for determining whether or not at least the execution of the basic fuel addition (and the basic post-injection) can be permitted. 9 is memorized.

  (C) When the upstream catalyst bed temperature TF is equal to or higher than the second catalyst bed temperature TF2 and lower than the third catalyst bed temperature TF3, the NOx catalyst is in an active state but its activity level is weak (a weak active state of the NOx catalyst). Therefore, when a small amount of fuel is contained in the exhaust gas, this fuel is sufficiently oxidized on the NOx catalyst, but a larger amount of fuel (a large amount of fuel) is contained in the exhaust gas. This fuel is not fully oxidized on the NOx catalyst. That is, the third catalyst bed temperature TF3 corresponds to a threshold value of the upstream catalyst bed temperature TF for grasping a state in which a large amount of fuel can be oxidized on the NOx catalyst. Therefore, when the upstream catalyst bed temperature TF belongs to the catalyst bed temperature region FC, regeneration fuel addition for supplying a large amount of fuel into the exhaust (and post injection for supplying a large amount of fuel (regeneration post injection)) Execution is not allowed. Therefore, in the present embodiment, the third catalyst bed temperature TF3 is preliminarily set to the electronic control device 9 as a value for determining whether or not the execution of the regeneration fuel addition (and regeneration post-injection) can be permitted. To remember.

  (D) When the reference exhaust gas temperature TG is lower than the first exhaust gas temperature TG1 and the upstream catalyst bed temperature TF is equal to or higher than the first catalyst bed temperature TF1, the upstream catalyst bed temperature TF is changed by the heat exchange between the exhaust gas and the catalyst-carrying filter 73. There is a possibility that it falls below 1 catalyst bed temperature TF1. Therefore, in a state where the reference exhaust temperature TG belongs to the exhaust temperature region GA, it is not desirable to allow the execution of after-injection in which the amount of fuel supplied into the exhaust gas is very small. Therefore, in the present embodiment, the first exhaust temperature TG1 is stored in advance in the electronic control unit 9 as a value for determining whether or not the execution of the after injection can be permitted.

  (E) When the reference exhaust gas temperature TG is lower than the second exhaust gas temperature TG2 and the upstream catalyst bed temperature TF is equal to or higher than the second catalyst bed temperature TF2, the upstream catalyst bed temperature TF is changed by heat exchange between the exhaust gas and the catalyst-carrying filter 73. There is a possibility that it falls below the catalyst bed temperature TF2. Therefore, in a state where the reference exhaust gas temperature TG belongs to the exhaust gas temperature range GB, the execution of basic fuel addition for supplying a small amount of fuel into the exhaust gas (and post injection for supplying a small amount of fuel (basic post injection)) is permitted. It is not desirable. Therefore, in the present embodiment, the second exhaust temperature TG2 is preliminarily stored in the electronic control unit 9 as a value for determining whether or not the execution of basic fuel addition (and basic post-injection) is allowed. I try to remember it.

  (F) When the reference exhaust gas temperature TG is lower than the third exhaust gas temperature TG3 and the upstream catalyst bed temperature TF is equal to or higher than the third catalyst bed temperature TF3, the upstream catalyst bed temperature TF is changed by heat exchange between the exhaust gas and the catalyst-carrying filter 73. There is a risk that the catalyst bed temperature TF3 will be below. Therefore, in a state where the reference exhaust gas temperature TG belongs to the exhaust gas temperature range GC, execution of regeneration fuel addition for supplying a large amount of fuel into the exhaust (and post injection for supplying a large amount of fuel (regeneration post injection)) is permitted. It is not desirable. Therefore, in the present embodiment, the third exhaust temperature TG3 is preliminarily stored in the electronic control unit 9 as a value for determining whether or not it is desirable to allow execution of regeneration fuel addition (and regeneration post-injection). I try to remember it. If the upstream catalyst bed temperature TF is equal to or higher than the third catalyst bed temperature TF3, it is basically possible to supply a large amount of fuel into the exhaust gas to increase the catalyst temperature. Can be allowed to perform the regeneration fuel addition (and regeneration post-injection) when the temperature is equal to or higher than the second exhaust temperature TG2. That is, on the condition that the upstream catalyst bed temperature TF belongs to the catalyst bed temperature region FD and the reference exhaust gas temperature TG belongs to the exhaust gas temperature region GC, the regeneration fuel addition is executed based on the fact that this condition is satisfied. You can also

As shown in FIG. 3, in the “regeneration control process”, the region of the upstream catalyst bed temperature TF is the following regions (a) to (c), and the region of the reference exhaust gas temperature TG is the following (d) to (f). The execution mode of glow energization is set based on the temperature region to which the upstream catalyst bed temperature TF and the reference exhaust gas temperature TG belong.
(A) Catalyst bed temperature region FE: 1st catalyst bed temperature TF1 or more and less than 4th catalyst bed temperature TF4.
(B) Catalyst bed temperature region FF: Fifth catalyst bed temperature TF5 or higher.
(C) Catalyst bed temperature region FG: 4th catalyst bed temperature TF4 or more and less than 5th catalyst bed temperature TF5.
(D) Exhaust temperature region GE: not lower than the first exhaust temperature TG1 and lower than the fourth exhaust temperature TG4.
(E) Exhaust temperature region GF: Fifth exhaust temperature TG5 or higher.
(F) Exhaust temperature region GG: not lower than the fourth exhaust temperature TG4 and lower than the fifth exhaust temperature TG5.

  Specifically, this condition is satisfied by setting the upstream catalyst bed temperature TF as belonging to the catalyst bed temperature region FG and the reference exhaust gas temperature TG as belonging to the exhaust gas temperature region GG as the fourth temperature rise condition. Glow energization is performed based on this. On the other hand, when the fourth temperature rise condition is not satisfied, glow energization based on the condition that the regeneration control execution condition is satisfied is prohibited. The catalyst bed temperature region FG corresponds to a specific range set in advance with respect to the temperature of the catalyst. The fourth catalyst bed temperature TF4 and the fifth catalyst bed temperature TF5 correspond to boundary temperatures set in advance as threshold values for the catalyst temperature. Further, the exhaust gas temperature region GG corresponds to a specific range set in advance with respect to the exhaust gas temperature. The fourth exhaust temperature TG4 and the fifth exhaust temperature TG5 correspond to boundary temperatures set in advance as threshold values for the exhaust temperature.

Each upstream catalyst bed temperature TF and each reference exhaust gas temperature TG indicating the boundary of each temperature region can be set as follows, for example. In the “regeneration control process” of the present embodiment, the following temperature setting is adopted.
-Fourth catalyst bed temperature TF4: 240 ° C
-Fifth catalyst bed temperature TF5: 310 ° C
-4th exhaust temperature TG4: 180 degreeC
-Fifth exhaust temperature TG5: 310 ° C
In the following (A) to (D), each upstream catalyst bed temperature TF and each reference exhaust gas temperature TG indicating the boundary of each temperature region will be described. In the following description, the NOx catalytic converter 72 is targeted, but the same description can be applied to the catalyst-carrying filter 73.

  (A) When the upstream catalyst bed temperature TF is lower than the fourth catalyst bed temperature TF4, the upstream catalyst bed temperature TF rises to a temperature equal to or higher than the third catalyst bed temperature TF3 even if glow energization is performed in accordance with the basic fuel addition. I can't expect to do it. Therefore, in the state where the upstream catalyst bed temperature TF belongs to the catalyst bed temperature region FE, the increase in the exhaust temperature obtained by execution of glow energization does not contribute to starting or continuing the regeneration fuel addition or regeneration post injection. Even if glow energization is performed, it can be considered that it is wasted. Therefore, in the present embodiment, the fourth catalyst bed temperature TF4 is stored in advance in the electronic control unit 9 as a value for determining whether or not the execution of glow energization is useless. Incidentally, since there is an upper limit for the rise in the exhaust temperature obtained by executing glow energization, the temperature of the exhaust obtained through the main injection is excessively low, that is, the fuel injection amount of the main injection (final injection amount Ffin) is small. In the operation state (mainly in the idle operation state), the upstream catalyst bed temperature TF cannot be raised to a temperature equal to or higher than the third catalyst bed temperature TF3 even if glow energization is executed in accordance with the addition of the basic fuel.

  The fourth catalyst bed temperature TF4 can be set as a value belonging to the range of the second catalyst bed temperature TF2 or higher and lower than the third catalyst bed temperature TF3. Further, it can be set as a threshold value of the upstream catalyst bed temperature TF that can be expected to increase the upstream catalyst bed temperature TF to a temperature equal to or higher than the third catalyst bed temperature TF3 by execution of glow energization. Since the exhaust gas temperature actually changes according to the engine operating state, even when glow energization is performed based on the fact that the upstream catalyst bed temperature TF is equal to or higher than the fourth catalyst bed temperature TF4, the upstream catalyst The bed temperature TF does not necessarily rise to a temperature equal to or higher than the third catalyst bed temperature TF3. In other words, the fourth catalyst bed temperature TF4 does not guarantee that the upstream catalyst bed temperature TF reliably rises to a temperature equal to or higher than the third catalyst bed temperature TF3 by performing glow energization.

  (B) When the upstream catalyst bed temperature TF is equal to or higher than the fifth catalyst bed temperature TF5, the upstream catalyst bed temperature TF is maintained at a temperature equal to or higher than the third catalyst bed temperature TF3 without executing glow energization in accordance with the regeneration fuel addition. I can expect that. Moreover, it can be expected that the downstream catalyst bed temperature TR rises to a temperature equal to or higher than the regeneration catalyst bed temperature TRfin due to the addition of the regenerated fuel. Therefore, in a state where the upstream catalyst bed temperature TF belongs to the catalyst bed temperature region FF, the increase in the exhaust temperature obtained by execution of glow energization does not contribute to continuing regeneration fuel addition or regeneration post-injection. It can be considered that even if it is executed, it will be wasted. Further, the increase in the exhaust temperature obtained by executing the glow energization does not contribute to raising the downstream catalyst bed temperature TR to a temperature equal to or higher than the regeneration catalyst bed temperature TRfin. It can be considered useless. Therefore, in the present embodiment, the fifth catalyst bed temperature TF5 is stored in advance in the electronic control unit 9 as a value for determining whether or not the execution of glow energization is useless.

  The fifth catalyst bed temperature TF5 can be set as a value belonging to the range of the third catalyst bed temperature TF3 or higher and lower than the regenerated catalyst bed temperature TRfin. Further, it can be set as a threshold value of the upstream catalyst bed temperature TF that can be expected to maintain the upstream catalyst bed temperature TF at a temperature equal to or higher than the third catalyst bed temperature TF3 without performing glow energization. In practice, since the temperature of the exhaust gas changes according to the engine operating state, even when glow energization is stopped based on the fact that the upstream catalyst bed temperature TF is equal to or higher than the fifth catalyst bed temperature TF5, thereafter In addition, the upstream catalyst bed temperature TF is not always maintained at a temperature equal to or higher than the third catalyst bed temperature TF3. That is, the fifth catalyst bed temperature TF5 does not guarantee that the upstream catalyst bed temperature TF is reliably maintained at a temperature equal to or higher than the third catalyst bed temperature TF3 without performing glow energization.

  (C) When the reference exhaust gas temperature TG is lower than the fourth exhaust gas temperature TG4, the reference exhaust gas temperature TG is expected to rise to a temperature equal to or higher than the second exhaust gas temperature TG2 even if glow energization is executed in accordance with the after injection. I can't. Therefore, in a state where the reference exhaust gas temperature TG belongs to the exhaust gas temperature region GE, the increase in the exhaust gas temperature obtained by execution of glow energization does not contribute to starting or continuing basic fuel addition or basic post injection. It can be considered that even if it is executed, it will be wasted. Therefore, in the present embodiment, the fourth exhaust temperature TG4 is stored in advance in the electronic control unit 9 as a value for determining whether or not execution of glow energization is in a useless state. Incidentally, since there is an upper limit for the rise in the exhaust temperature obtained by executing glow energization, the temperature of the exhaust obtained through the main injection is excessively low, that is, the fuel injection amount of the main injection (final injection amount Ffin) is small. In the operation state (mainly in the idle operation state), the reference exhaust gas temperature TG cannot be increased to a temperature equal to or higher than the second exhaust gas temperature TG2 even if glow energization is executed in accordance with the after injection.

  The fourth exhaust temperature TG4 can be set as a value belonging to a range not lower than the first exhaust temperature TG1 and lower than the second exhaust temperature TG2. Further, it can be set as a threshold value of the reference exhaust gas temperature TG that can be expected to increase the reference exhaust gas temperature TG to a temperature equal to or higher than the second exhaust gas temperature TG2 by executing glow energization. It should be noted that since the exhaust gas temperature actually changes in accordance with the engine operating state, the reference exhaust gas temperature TG is used even when glow energization is performed based on the reference exhaust gas temperature TG being equal to or higher than the fourth exhaust gas temperature TG4. Does not necessarily rise to a temperature equal to or higher than the second exhaust temperature TG2. That is, the fourth exhaust temperature TG4 does not guarantee that the reference exhaust temperature TG reliably rises to a temperature equal to or higher than the second exhaust temperature TG2 by performing glow energization.

  (D) When the reference exhaust gas temperature TG is equal to or higher than the fifth exhaust gas temperature TG5, the reference exhaust gas temperature TG is expected to be maintained at a temperature equal to or higher than the third exhaust gas temperature TG3 without executing glow energization in accordance with the addition of the regenerated fuel. be able to. Moreover, it can be expected that the downstream catalyst bed temperature TR rises to a temperature equal to or higher than the regeneration catalyst bed temperature TRfin due to the addition of the regenerated fuel. Accordingly, in a state where the reference exhaust temperature TG belongs to the exhaust temperature region GF, the increase in the exhaust temperature obtained by executing the glow energization does not contribute to continuing the regeneration fuel addition or the regeneration post injection, so the glow energization is performed. Even so, it can be considered useless. Further, the increase in the exhaust temperature obtained by executing the glow energization does not contribute to raising the downstream catalyst bed temperature TR to a temperature equal to or higher than the regeneration catalyst bed temperature TRfin. It can be considered useless. Therefore, in the present embodiment, the fifth exhaust temperature TG5 is stored in advance in the electronic control unit 9 as a value for determining whether or not execution of glow energization is in a useless state.

  The fifth exhaust temperature TG5 can be set as a value belonging to a range that is equal to or higher than the third exhaust temperature TG3 and lower than the regenerated catalyst bed temperature TRfin. Further, it can be set as a threshold value of the reference exhaust temperature TG that can be expected to maintain the reference exhaust temperature TG at a temperature equal to or higher than the third exhaust temperature TG3 without executing glow energization. It should be noted that since the exhaust gas temperature actually changes according to the engine operating state, even when glow energization is stopped based on the fact that the reference exhaust gas temperature TG is equal to or higher than the fifth exhaust gas temperature TG5, the reference gas is subsequently The exhaust temperature TG is not necessarily maintained at a temperature equal to or higher than the third exhaust temperature TG3. That is, the fifth exhaust temperature TG5 does not guarantee that the reference exhaust temperature TG is reliably maintained at a temperature equal to or higher than the third exhaust temperature TG3 without performing glow energization.

<Details of playback control processing>
The electronic control unit 9 executes “regeneration control processing (FIGS. 4 to 6)” for performing regeneration control during operation of the engine 1. Further, an “exhaust temperature estimation process” for estimating the reference exhaust temperature TG, a “first catalyst bed temperature estimation process” for estimating the upstream catalyst bed temperature TF, and a “first catalyst bed temperature estimation process” for estimating the downstream catalyst bed temperature TR. The “second catalyst bed temperature estimation process” is executed in parallel with the “regeneration control process”.

  In the “exhaust temperature estimation process”, an estimated value (estimated reference exhaust temperature TGV) of the reference exhaust temperature TG is calculated based on parameters affecting the exhaust temperature (mainly the engine speed NE and the fuel injection amount of the injector 51). To do.

  In the “first catalyst bed temperature estimation process”, the inlet exhaust temperature measured value TGIM of the inlet exhaust temperature sensor 93 is set as the estimated value of the upstream catalyst bed temperature TF (estimated upstream catalyst bed temperature TFV). The estimated upstream catalyst bed temperature TFV can also be calculated by taking into account a response delay until the temperature of the exhaust gas that has passed through the inlet exhaust temperature sensor 93 is reflected in the upstream catalyst bed temperature TF. That is, a value obtained by correcting the measured inlet exhaust temperature value TGIM based on the exhaust flow rate can be calculated as the estimated upstream catalyst bed temperature TFV.

  In the “second catalyst bed temperature estimation process”, the outlet exhaust temperature measurement value TGOM of the outlet exhaust temperature sensor 94 is set as the estimated value of the downstream catalyst bed temperature TR (estimated downstream catalyst bed temperature TRV). The estimated downstream catalyst bed temperature TRV can also be calculated by taking into account the response delay until the downstream catalyst bed temperature TR is reflected in the outlet exhaust temperature sensor 94. That is, a value obtained by correcting the outlet exhaust temperature measured value TGOM based on the exhaust flow rate can be calculated as the estimated downstream catalyst bed temperature TRV.

[1] "Reproduction control processing"
A detailed processing procedure of the “reproduction control process” will be described with reference to FIG. Note that this process includes a “first temperature rise process (FIG. 5)” that sets the execution mode of after-injection and fuel addition, and a “second temperature rise process (FIG. 6)” that sets the execution mode of glow energization. It is comprised including. Further, it is repeatedly executed every predetermined control cycle (for example, 65 msec) during operation of the engine 1.

  [Step S110] It is determined whether regeneration control is being executed. When the reproduction control is stopped, the process proceeds to step S120. When the reproduction control is being executed, the process proceeds to step S130.

  [Step S120] It is determined whether or not an execution condition for regeneration control is satisfied. When the reproduction control execution condition is satisfied, the process proceeds to step S122. When the execution condition for the regeneration control is not satisfied, the “reproduction control process” is temporarily ended.

In the process of step S120, based on the fact that the following [execution condition A] and [execution condition B] are met, it is determined that the regeneration control execution condition is met.
[Execution Condition A]: The estimated value (estimated deposition amount) of the PM deposited on the catalyst-carrying filter 73 exceeds the deposition amount upper limit value. The estimated accumulation amount can be calculated based on parameters (mainly the intake air amount and the final injection amount Ffin) indicating the history of the operating state of the engine 1. The upper limit value of the accumulation amount is a value for determining that PM is accumulated to such an extent that the engine operating state is deteriorated due to clogging of the catalyst-carrying filter 73 or an increase in back pressure. Can be set in advance. In place of [Execution Condition A], the execution condition is that the difference between the pressure upstream of the catalyst-carrying filter 73 and the downstream pressure (pressure difference between filters) exceeds the pressure difference upper limit value. You can also.
[Execution Condition B]: The upstream catalyst bed temperature TF is equal to or higher than the first catalyst bed temperature TF1, and the reference exhaust gas temperature TG is equal to or higher than the first exhaust gas temperature TG1. That is, the first temperature raising condition that is the execution condition of the after injection is satisfied.

  [Step S122] Regeneration control is started based on the fact that the execution condition is satisfied. That is, the “first temperature raising process (FIG. 5)” and the “second temperature raising process (FIG. 6)” are started. After completion of these processes, the “reproduction control process” is temporarily ended. Details of each process will be described later.

  [Step S130] It is determined whether or not a condition for terminating regeneration control is satisfied. That is, it is determined whether or not PM deposited on the catalyst-carrying filter 73 has been sufficiently removed. When the reproduction control end condition is not satisfied, the process proceeds to step S132. When the reproduction control end condition is satisfied, the process proceeds to step S134.

  In the process of step S130, when the estimated value (estimated accumulation amount) of the PM accumulated on the catalyst-carrying filter 73 is less than the lower limit accumulation amount, the regeneration control end condition is satisfied. I try to judge. The lower limit deposition amount can be set in advance through a test or the like as a value for determining a state in which PM is not substantially deposited on the catalyst-carrying filter 73. Instead of the termination condition, it is also possible to adopt that the difference between the pressure upstream of the catalyst-carrying filter 73 and the pressure downstream (pressure difference between filters) is less than the lower limit pressure difference.

[Step S132] The “first temperature rise process (FIG. 5)” and the “second temperature rise process (FIG. 6)” are continuously executed. After completion of these processes, the “reproduction control process” is temporarily ended.
[Step S134] The reproduction control is terminated. That is, the process (basically, regeneration fuel addition) that is executed based on the condition that the regeneration control execution condition is satisfied is terminated. After executing the process of step S134, the “reproduction control process” is temporarily ended.

[2] "First temperature rise process"
With reference to FIG. 5, a detailed processing procedure of the “first temperature raising process” will be described. In this process, through each determination process, it is determined to which temperature region (see FIG. 2) the upstream catalyst bed temperature TF and the reference exhaust temperature TG belong. Then, any one of regeneration fuel addition, basic fuel addition, and after injection is executed according to the determination result.

  [Step S210] It is determined whether the estimated upstream catalyst bed temperature TFV is equal to or higher than the second catalyst bed temperature TF2 (eg, 200 ° C.) and the estimated reference exhaust temperature TGV is equal to or higher than the second exhaust temperature TG2 (eg, 200 ° C.). That is, it is determined whether or not a second temperature raising condition, which is an execution condition for basic fuel addition, is satisfied. When the relationship of “TFV ≧ TF2” and the relationship of “TGV ≧ TG2” are established, the process proceeds to step S220. When at least one of the relationship of “TFV ≧ TF2” and the relationship of “TGV ≧ TG2” is not established, the process proceeds to step S226.

  [Step S220] It is determined whether the estimated upstream catalyst bed temperature TFV is equal to or higher than the third catalyst bed temperature TF3 (eg, 260 ° C.) and the estimated reference exhaust temperature TGV is equal to or higher than the third exhaust temperature TG3 (eg, 260 ° C.). That is, it is determined whether or not a third temperature raising condition, which is an execution condition for adding the regenerated fuel, is satisfied. When the relationship of “TFV ≧ TF3” and the relationship of “TGV ≧ TG3” are established, the process proceeds to step S222. When at least one of the relationship of “TFV ≧ TF3” and the relationship of “TGV ≧ TG3” is not established, the process proceeds to step S224.

  [Step S222] The regeneration fuel addition to the sub-injector 71 is started on the basis that the third temperature raising condition is satisfied. When regeneration fuel addition has already begun, it continues. When after-injection or basic fuel addition is being executed, the process being executed is terminated and regeneration fuel addition is started. After performing the process of step S222, the “first temperature raising process” is temporarily ended.

  The regeneration fuel addition is basically performed based on the temperature of the catalyst-carrying filter 73 (estimated downstream catalyst bed temperature TRV). That is, the fuel injection amount of the sub-injector 71 is set so that the estimated downstream catalyst bed temperature TRV finally rises to a temperature equal to or higher than the regenerated catalyst bed temperature TRfin.

  [Step S224] Basic fuel addition to the sub-injector 71 is started based on the fact that the second temperature raising condition is satisfied. If basic fuel addition has already begun, continue. When after-injection or regenerated fuel addition is being executed, the process being executed is terminated and basic fuel addition is started. After executing the process of step S224, the “first temperature raising process” is temporarily ended.

  [Step S226] After injection of the injector 51 is started based on the fact that the first temperature raising condition is satisfied. When after-injection has already started, it continues. When the basic fuel addition or the regeneration fuel addition is being executed, the process being executed is terminated and the after injection is started. After performing the process of step S226, the “first temperature raising process” is temporarily ended.

[3] “Second heating process”
With reference to FIG. 6, a detailed processing procedure of the “second temperature raising process” will be described. In this process, through each determination process, it is determined to which temperature range (see FIG. 3) the upstream catalyst bed temperature TF and the reference exhaust gas temperature TG belong. Then, glow energization is executed or stopped according to the determination result.

  [Step S310] It is determined whether the estimated upstream catalyst bed temperature TFV is lower than the fifth catalyst bed temperature TF5 (eg, 310 ° C.). When the relationship of “TFV <TF5” is established, the process proceeds to step S320. When the relationship of “TFV <TF5” is not established, the process proceeds to step S344.

  [Step S320] It is determined whether the estimated upstream catalyst bed temperature TFV is equal to or higher than the fourth catalyst bed temperature TF4 (eg, 240 ° C.). When the relationship “TFV ≧ TF4” is established, the process proceeds to step S330. When the relationship of “TFV ≧ TF4” is not established, the process proceeds to step S344.

  [Step S330] It is determined whether the estimated reference exhaust temperature TGV is lower than a fifth exhaust temperature TG5 (eg, 310 ° C.). When the relationship of “TGV <TG5” is established, the process proceeds to step S340. When the relationship of “TGV <TG5” is not established, the process proceeds to step S344.

  [Step S340] It is determined whether or not the estimated reference exhaust temperature TGV is equal to or higher than a fourth exhaust temperature TG4 (example: 180 ° C.). When the relationship of “TGV ≧ TG4” is established, the process proceeds to step S342. When the relationship of “TGV ≧ TG4” is not established, the process proceeds to step S344.

  [Step S342] Glow energization is started based on the fact that the fourth temperature raising condition is satisfied. When glow energization has already started, it continues to run. After performing the process of step S342, the “second temperature raising process” is temporarily ended.

[Step S344] Glow energization is prohibited based on the fact that the fourth temperature raising condition is not satisfied. After performing the process of step S344, the “second temperature raising process” is temporarily ended.
The execution and stop of glow energization in step S342 and step S344 are performed based on the following conditions (A) to (C). Hereinafter, the continuous energization time of the glow plug 15 is referred to as a continuous energization time HG.

  (A) After the energization of glow is started, the glow energization is terminated when the continuous energization time HG reaches the allowable energization time HX. That is, even when glow energization is performed based on the establishment of the fourth temperature rise condition, when the continuous energization time HG reaches the allowable energization time HX, the glow energization ends regardless of the establishment of the fourth temperature rise condition. To do. Then, after the glow energization is completed based on the continuous energization time HG, the glow energization is started again when the fourth temperature raising condition is satisfied when a later-described minimum non-energization time HB elapses. The allowable energization time HX is set in advance as a value that can suppress a decrease in the life of the glow plug 15 due to overheating or the like.

  (B) After the start of glow energization, the end of glow energization is prohibited until the continuous energization time HG reaches the minimum energization time HA. That is, even when it is determined that the fourth temperature raising condition is not satisfied during glow energization, the end of glow energization is prohibited when the continuous energization time HG is less than the minimum energization time HA. When the continuous energization time HG reaches the minimum energization time HA, the end of glow energization is permitted. The minimum energization time HA is set in advance as a value that can suppress a decrease in the life of the relay circuit due to switching between execution and stop of energization.

(C) After the glow energization is finished, execution of glow energization is prohibited until the continuous non-energization time reaches the minimum non-energization time HB. That is, even when it is determined that the fourth temperature raising condition is satisfied while the glow energization is stopped, execution of the glow energization is prohibited when the continuous non-energization time is less than the minimum non-energization time HB. When the continuous non-energization time reaches the minimum non-energization time HB, execution of glow energization is permitted. The minimum non-energization time HB is set in advance as a value that can suppress a reduction in the life of the relay circuit due to switching between execution and stop of energization.

<Example of playback control>
With reference to FIG. 7, an example of an execution mode of the reproduction control will be described.
[Time t71]: Assume that the execution condition of the regeneration control is determined at this time. At this time, after injection is started based on the fact that the first temperature raising condition is satisfied. On the other hand, execution of glow energization is prohibited based on the fact that the fourth temperature rise condition is not satisfied.

  [Time t72]: Assume that it is determined that the second temperature increase condition is satisfied at this time due to the increase in the upstream catalyst bed temperature TF and the reference exhaust gas temperature TG accompanying the after injection. At this time, the basic fuel addition is started based on the fact that the second temperature raising condition is satisfied. On the other hand, execution of glow energization is prohibited based on the fact that the fourth temperature rise condition is not satisfied.

  [Time t73]: Assume that the establishment of the fourth temperature rise condition is determined at this time due to the rise in the upstream catalyst bed temperature TF accompanying the addition of the basic fuel. At this time, execution of glow energization is started based on the fact that the fourth temperature raising condition is satisfied. Further, the execution of the basic fuel addition is continued based on the fact that the second temperature raising condition is satisfied.

  [Time t74]: Assume that it is determined at this time that the third temperature rise condition is satisfied, due to the increase in the upstream catalyst bed temperature TF and the reference exhaust gas temperature TG accompanying the addition of basic fuel and glow energization. At this time, the execution of regeneration fuel addition is started based on the fact that the third temperature raising condition is satisfied. Further, the execution of glow energization is continued based on the fact that the fourth temperature raising condition is satisfied.

  [Time t75]: Assume that it is determined that the fourth temperature rise condition is not satisfied at this time due to an increase in the upstream catalyst bed temperature TF and the reference exhaust gas temperature TG due to the addition of regenerated fuel and glow energization. At this time, execution of glow energization is prohibited based on the fact that the fourth temperature rise condition is not satisfied. On the other hand, the execution of the regeneration fuel addition is continued based on the fact that the third temperature raising condition is satisfied.

  [Time t76] It is assumed that the completion condition of the regeneration control is determined at this time because the upstream catalyst bed temperature TF is maintained at a temperature equal to or higher than the regeneration upstream catalyst bed temperature TFfin for a certain period. At this time, regeneration control (regeneration fuel addition) is terminated based on the fact that the termination condition is satisfied.

<Effect of embodiment>
As described above in detail, according to the engine exhaust system temperature control apparatus of this embodiment, the following effects can be obtained.

  (1) In the exhaust system temperature control device of the present embodiment, when the regeneration control execution condition is satisfied, it is obtained when the upstream catalyst bed temperature TF is lower than the fourth catalyst bed temperature TF4, that is, by performing glow energization. Glow energization is prohibited when the increase in exhaust gas temperature that is generated does not contribute to starting or continuing the addition of the regenerated fuel. In this way, unnecessary glow energization is performed by prohibiting glow energization when it is estimated that the upstream catalyst bed temperature TF does not reach the required value (third catalyst bed temperature TF3) even if glow energization is performed. Is to be suppressed. As a result, the life of the glow plug 15 and the fuel consumption rate can be improved.

  (2) In the exhaust system temperature control apparatus according to the present embodiment, when the upstream catalyst bed temperature TF is equal to or higher than the fifth catalyst bed temperature TF5 in a state where the regeneration control execution condition is satisfied, that is, obtained by executing glow energization. Glow energization is prohibited when the increase in the exhaust gas temperature does not contribute to continuing the addition of the regenerated fuel, and consequently increasing the downstream catalyst bed temperature TR to a temperature equal to or higher than the regenerated catalyst bed temperature TRfin. As described above, by prohibiting glow energization when it is estimated that the upstream catalyst bed temperature TF is maintained at a temperature equal to or higher than the required value (third catalyst temperature TF3) without executing glow energization, a wasteful glow is prevented. The execution of energization is suppressed. As a result, the life of the glow plug 15 and the fuel consumption rate can be improved.

  (3) In the exhaust system temperature control device according to the present embodiment, the control of the execution mode of glow energization based on the upstream catalyst bed temperature TF is continued from when the execution condition for regeneration control is satisfied until the end condition is satisfied. To do. As a result, when it is estimated that unnecessary glow energization is performed due to a change in the engine operating state or the like, the execution of glow energization is accurately prohibited, so that the life of the glow plug 15 and the fuel consumption rate are improved more appropriately. Will be able to.

  (4) In the exhaust system temperature control apparatus according to the present embodiment, when the reference exhaust temperature TG is lower than the fourth exhaust temperature TG4 in a state where the regeneration control execution condition is satisfied, that is, exhaust obtained by execution of glow energization. When the increase in temperature does not contribute to starting or continuing the basic fuel addition, glow energization is prohibited. As described above, the execution of useless glow energization is suppressed by prohibiting glow energization when it is estimated that the reference exhaust gas temperature TG does not reach the required value (second exhaust gas temperature TG2) even if glow energization is performed. To be. As a result, the life of the glow plug 15 and the fuel consumption rate can be improved.

  (5) In the exhaust system temperature control apparatus according to the present embodiment, when the reference exhaust temperature TG is equal to or higher than the fifth exhaust temperature TG5 in a state where the regeneration control execution condition is satisfied, that is, exhaust obtained by executing glow energization. Glow energization is prohibited when the increase in temperature does not contribute to continuing the addition of the regenerated fuel, and consequently increasing the downstream catalyst bed temperature TR to a temperature equal to or higher than the regeneration catalyst bed temperature TRfin. As described above, when it is estimated that the reference exhaust gas temperature TG is maintained at a temperature equal to or higher than the required value (third exhaust gas temperature TG3) without executing glow energization, the glow energization is prohibited, thereby preventing unnecessary glow energization. Execution is suppressed. As a result, the life of the glow plug 15 and the fuel consumption rate can be improved.

  (6) In the exhaust system temperature control device of the present embodiment, the control of the execution mode of glow energization based on the reference exhaust gas temperature TG is continued from the time when the regeneration control execution condition is satisfied until the end condition is satisfied. Like to do. As a result, when it is estimated that unnecessary glow energization is performed due to a change in the engine operating state or the like, the execution of glow energization is accurately prohibited, so that the life of the glow plug 15 and the fuel consumption rate are improved more appropriately. Will be able to.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIG.
The exhaust system temperature control apparatus of the present embodiment applies the following changes to the setting aspect of the first embodiment with respect to the setting aspect of the execution range of glow energization based on the upstream catalyst bed temperature TF and the reference exhaust gas temperature TG. It is configured as a control device. Except for the changes described below, the same configuration as that of the first embodiment is employed.

<Main changes in playback control processing>
As shown in FIG. 8, in the “regeneration control process” of the present embodiment, the upstream catalyst bed temperature TF region is set to the following regions (a) to (c), and the reference exhaust gas temperature TG region is set to the following (d). To (f), and the execution mode of glow energization is set based on the temperature region to which the upstream catalyst bed temperature TF and the reference exhaust gas temperature TG belong.
(A) Catalyst bed temperature region FH: The first catalyst bed temperature TF1 or more and less than the sixth catalyst bed temperature TF6.
(B) Catalyst bed temperature region FF: Fifth catalyst bed temperature TF5 or higher.
(C) Catalyst bed temperature region FI: 6th catalyst bed temperature TF6 or more and less than 5th catalyst bed temperature TF5.
(D) Exhaust temperature region GH: not less than the first exhaust temperature TF1 and less than the sixth exhaust temperature TG6.
(E) Exhaust temperature region GF: Fifth exhaust temperature TG5 or higher.
(F) Exhaust temperature region GI: 6th exhaust temperature TG6 or more and less than 5th exhaust temperature TG5.

  Specifically, this condition is established with the fifth temperature rise condition that the upstream catalyst bed temperature TF belongs to the catalyst bed temperature region FI and the reference exhaust gas temperature TG belongs to the exhaust temperature region GI. Glow energization is performed based on this. On the other hand, when the fifth temperature increase condition is not satisfied, glow energization based on the condition that the regeneration control execution condition is satisfied is prohibited. The catalyst bed temperature region FI corresponds to a specific range set in advance with respect to the temperature of the catalyst. The sixth catalyst bed temperature TF6 corresponds to a boundary temperature set in advance as a threshold value for the temperature of the catalyst. Further, the exhaust gas temperature region GI corresponds to a specific range set in advance with respect to the exhaust gas temperature. The sixth exhaust temperature TG6 corresponds to a boundary temperature set in advance as a threshold for the exhaust temperature.

Each upstream catalyst bed temperature TF and each reference exhaust gas temperature TG indicating the boundary of each temperature region can be set as follows, for example. In the “regeneration control process” of the present embodiment, the following temperature setting is adopted.
-Sixth catalyst bed temperature TF6: 180 ° C
-Fifth catalyst bed temperature TF5: 310 ° C
-6th exhaust temperature TG6: 240 degreeC
-Fifth exhaust temperature TG5: 310 ° C
In the following (A) and (B), the sixth catalyst bed temperature TF6 and the sixth exhaust temperature TG6 indicating the boundaries of the respective temperature regions will be described. In the following description, the NOx catalytic converter 72 is targeted, but the same description can be applied to the catalyst-carrying filter 73.

  (A) When the upstream catalyst bed temperature TF is lower than the sixth catalyst bed temperature TF6, the upstream catalyst bed temperature TF rises to a temperature equal to or higher than the second catalyst bed temperature TF2 even if glow energization is performed in accordance with after injection. I can't expect that. Therefore, in the state where the upstream catalyst bed temperature TF belongs to the catalyst bed temperature region FH, the increase in the exhaust temperature obtained by execution of glow energization does not contribute to starting or continuing basic fuel addition or basic post injection. Even if glow energization is performed, it can be considered that it is wasted. Therefore, in the present embodiment, the sixth catalyst bed temperature TF6 is stored in advance in the electronic control unit 9 as a value for determining whether or not the execution of glow energization is useless.

  The sixth catalyst bed temperature TF6 can be set as a value belonging to a range that is equal to or higher than the first catalyst bed temperature TF1 and lower than the second catalyst bed temperature TF2. Further, it can be set as a threshold value of the upstream catalyst bed temperature TF that can be expected to increase the upstream catalyst bed temperature TF to a temperature equal to or higher than the second catalyst bed temperature TF2 by execution of glow energization. Since the exhaust gas temperature actually changes depending on the engine operating state, even when glow energization is performed based on the fact that the upstream catalyst bed temperature TF is equal to or higher than the sixth catalyst bed temperature TF6, the upstream catalyst The bed temperature TF does not always rise to a temperature equal to or higher than the second catalyst bed temperature TF2. That is, the sixth catalyst bed temperature TF6 does not guarantee that the upstream catalyst bed temperature TF reliably rises to a temperature equal to or higher than the second catalyst bed temperature TF2 by execution of glow energization.

  (B) When the reference exhaust temperature TG is lower than the sixth exhaust temperature TG6, the reference exhaust temperature TG is expected to rise to a temperature equal to or higher than the third exhaust temperature TG3 even if glow energization is executed in accordance with the addition of the basic fuel. I can't. Therefore, in a state where the reference exhaust temperature TG belongs to the exhaust temperature region GH, the increase in the exhaust temperature obtained by executing the glow energization does not contribute to starting or continuing the regeneration fuel addition or regeneration post injection, so the glow energization It can be considered that even if it is executed, it will be wasted. Therefore, in the present embodiment, the sixth exhaust temperature TG6 is stored in advance in the electronic control unit 9 as a value for determining whether or not the execution of glow energization is useless.

  The sixth exhaust temperature TG6 can be set as a value belonging to a range not lower than the second exhaust temperature TG2 and lower than the third exhaust temperature TG3. Further, it can be set as a threshold value of the reference exhaust gas temperature TG that can be expected to increase the reference exhaust gas temperature TG to a temperature equal to or higher than the third exhaust gas temperature TG3 due to execution of glow energization. It should be noted that since the exhaust gas temperature actually changes according to the engine operating state, even when glow energization is executed based on the reference exhaust gas temperature TG being equal to or higher than the sixth exhaust gas temperature TG6, the reference exhaust gas temperature TG. Does not necessarily rise to a temperature equal to or higher than the third exhaust temperature TG3. That is, the sixth exhaust temperature TG6 does not guarantee that the reference exhaust temperature TG reliably rises to a temperature equal to or higher than the third exhaust temperature TG3 by performing glow energization.

In the “regeneration control process” of the present embodiment, a part of the “second temperature raising process (FIG. 6)” is changed and executed as shown in the following [A] to [C].
[A]: In the process of step S320, it is determined whether or not the estimated upstream catalyst bed temperature TFV is equal to or higher than the sixth catalyst bed temperature TF6 (example: 180 ° C.). When the relationship of “TFV ≧ TF6” is established, the process proceeds to step S330. When the relationship of “TFV ≧ TF6” is not established, the process proceeds to step S344.

  [B]: In the process of step S340, it is determined whether or not the estimated reference exhaust temperature TGV is equal to or higher than a sixth exhaust temperature TG6 (eg, 240 ° C.). When the relationship of “TGV ≧ TG6” is established, the process proceeds to step S342. When the relationship of “TGV ≧ TG6” is not established, the process proceeds to step S344.

  [C]: In the process of step S342, glow energization is executed based on the fact that the fifth temperature rise condition is satisfied. In the process of step S344, glow energization is prohibited based on the fact that the fifth temperature raising condition is not satisfied.

<Effect of embodiment>
As described above in detail, according to the exhaust system temperature control device for an engine according to the second embodiment, the operational effects of (2), (3), (5) and (6) according to the first embodiment. In addition, the following effects can be obtained.

  (7) In the exhaust system temperature control apparatus according to the present embodiment, when the regeneration control execution condition is satisfied, it is obtained when the upstream catalyst bed temperature TF is lower than the sixth catalyst bed temperature TF6, that is, by performing glow energization. Glow energization is prohibited when the increase in exhaust gas temperature that does not contribute to starting or continuing to add basic fuel. In this way, unnecessary glow energization is performed by prohibiting glow energization when it is estimated that the upstream catalyst bed temperature TF does not reach the required value (second catalyst bed temperature TF2) even if glow energization is performed. Is to be suppressed. As a result, the life of the glow plug 15 and the fuel consumption rate can be improved.

  (8) In the exhaust system temperature control apparatus of the present embodiment, when the reference exhaust temperature TG is lower than the sixth exhaust temperature TG6 in a state where the regeneration control execution condition is satisfied, that is, exhaust obtained by executing glow energization. When the increase in temperature does not contribute to starting or continuing the addition of the regenerated fuel, glow energization is prohibited. As described above, the execution of useless glow energization is suppressed by prohibiting glow energization when it is estimated that the reference exhaust gas temperature TG does not reach the required value (third exhaust gas temperature TG3) even if glow energization is performed. To be. As a result, the life of the glow plug 15 and the fuel consumption rate can be improved.

(Third embodiment)
A third embodiment of the present invention will be described with reference to FIG.
The exhaust system temperature control device of the present embodiment is configured to set the execution mode of glow energization based on the upstream catalyst bed temperature TF and the reference exhaust gas temperature TG, and the setting mode of the first embodiment and the setting mode of the second embodiment. Is configured as a control device that sets the same execution range. Except for the changes described below, the same configuration as that of the first embodiment is employed.

<Main changes in playback control processing>
As shown in FIG. 9, in the “regeneration control process” of the present embodiment, the region of the upstream catalyst bed temperature TF is the following regions (a) to (c), and the region of the reference exhaust gas temperature TG is the following (d). To (f), and the execution mode of glow energization is set based on the temperature region to which the upstream catalyst bed temperature TF and the reference exhaust gas temperature TG belong.
(A) Catalyst bed temperature region FH: The first catalyst bed temperature TF1 or more and less than the sixth catalyst bed temperature TF6.
(B) Catalyst bed temperature region FF: Fifth catalyst bed temperature TF5 or higher.
(C) Catalyst bed temperature region FI: 6th catalyst bed temperature TF6 or more and less than 5th catalyst bed temperature TF5.
(D) Exhaust temperature region GE: not lower than the first exhaust temperature TG1 and lower than the fourth exhaust temperature TG4.
(E) Exhaust temperature region GF: Fifth exhaust temperature TG5 or higher.
(F) Exhaust temperature region GG: not lower than the fourth exhaust temperature TG4 and lower than the fifth exhaust temperature TG5.

  Specifically, this condition is established with the sixth temperature rise condition that the upstream catalyst bed temperature TF belongs to the catalyst bed temperature region FI and the reference exhaust gas temperature TG belongs to the exhaust gas temperature region GG. Glow energization is performed based on this. On the other hand, when the sixth temperature rise condition is not satisfied, glow energization based on the condition that the regeneration control execution condition is satisfied is prohibited.

  In the “regeneration control process” of the present embodiment, a part of the “second temperature raising process (FIG. 6)” is changed as follows. That is, in the process of step S320, it is determined whether or not the estimated upstream catalyst bed temperature TFV is equal to or higher than the sixth catalyst bed temperature TF6 (example: 180 ° C.). When the relationship of “TFV ≧ TF6” is established, the process proceeds to step S342. When the relationship of “TFV ≧ TF6” is not established, the process proceeds to step S344. In the process of step S342, glow energization is executed based on the fact that the sixth temperature raising condition is satisfied. In the process of step S344, glow energization is prohibited based on the fact that the sixth temperature rise condition is not satisfied.

<Effect of embodiment>
As described above in detail, according to the exhaust system temperature control apparatus for an engine according to the third embodiment, the effects (2) to (6) of the first embodiment and the second embodiment described above. The effect (7) according to the form can be obtained.

(Fourth embodiment)
A fourth embodiment of the present invention will be described with reference to FIGS.
The exhaust system temperature control device of the present embodiment applies the following changes to the setting mode of the third embodiment with respect to the setting mode of the glow energization execution range based on the upstream catalyst bed temperature TF and the reference exhaust gas temperature TG. It is configured as a control device. Except for the changes described below, the same configuration as that of the first embodiment is employed.

<Main changes in playback control processing>
As shown in FIG. 10, in the “regeneration control process” of the present embodiment, the upstream catalyst bed temperature TF region is set to the following regions (a) to (c), and the reference exhaust gas temperature TG region is set to the following (d). To (f), and the execution mode of glow energization is set based on the temperature region to which the upstream catalyst bed temperature TF and the reference exhaust gas temperature TG belong.
(A) Catalyst bed temperature region FH: The first catalyst bed temperature TF1 or more and less than the sixth catalyst bed temperature TF6.
(B) Catalyst bed temperature region FJ: 7th catalyst bed temperature TF7 or higher.
(C) Catalyst bed temperature region FK: 6th catalyst bed temperature TF6 or more and less than 7th catalyst bed temperature TF7.
(D) Exhaust temperature region GE: not lower than the first catalyst bed temperature TF1 and lower than the fourth exhaust temperature TG4.
(E) Exhaust temperature region GF: Fifth exhaust temperature TG5 or higher.
(F) Exhaust temperature region GG: not lower than the fourth exhaust temperature TG4 and lower than the fifth exhaust temperature TG5.

  Specifically, the seventh catalyst temperature condition is satisfied when the upstream catalyst bed temperature TF belongs to the catalyst bed temperature region FK and the reference exhaust gas temperature TG belongs to the exhaust gas temperature region GG. Glow energization is performed based on this. On the other hand, when the seventh temperature rise condition is not satisfied, glow energization based on the condition that the regeneration control execution condition is satisfied is prohibited. The catalyst bed temperature region FK corresponds to a specific range set in advance with respect to the temperature of the catalyst. The seventh catalyst bed temperature TF7 corresponds to a boundary temperature set in advance as a threshold value for the temperature of the catalyst. In the “regeneration control process” of the present embodiment, the seventh catalyst bed temperature TF7 is set to 250 ° C.

  When the upstream catalyst bed temperature TF is equal to or higher than the seventh catalyst bed temperature TF7, the upstream catalyst bed temperature TF is maintained at a temperature equal to or higher than the second catalyst bed temperature TF2 without executing glow energization in accordance with the addition of the basic fuel. I can expect. Therefore, in the state where the upstream catalyst bed temperature TF belongs to the catalyst bed temperature region FK, the increase in the exhaust temperature obtained by executing the glow energization does not contribute to the continuation of the basic fuel addition and the basic post injection. It can be considered that even if it is executed, it will be wasted. Therefore, in the present embodiment, the seventh catalyst bed temperature TF7 is stored in advance in the electronic control unit 9 as a value for determining whether or not the execution of glow energization is useless.

  The seventh catalyst bed temperature TF7 can be set as a value belonging to the range of the second catalyst bed temperature TF2 or more and less than the regenerated catalyst bed temperature TRfin (or the third catalyst bed temperature TF3). Further, it can be set as a threshold value of the upstream catalyst bed temperature TF that can be expected to maintain the upstream catalyst bed temperature TF at a temperature equal to or higher than the second catalyst bed temperature TF2 without performing glow energization. In practice, since the temperature of the exhaust gas changes according to the engine operating state, even when glow energization is stopped based on the fact that the upstream catalyst bed temperature TF is equal to or higher than the seventh catalyst bed temperature TF7, thereafter In addition, the upstream catalyst bed temperature TF is not necessarily maintained at a temperature equal to or higher than the second catalyst bed temperature TF2. That is, the seventh catalyst bed temperature TF7 does not guarantee that the upstream catalyst bed temperature TF is reliably maintained at a temperature equal to or higher than the second catalyst bed temperature TF2.

<Processing procedure of third temperature raising process>
In the “regeneration control process” of the present embodiment, a “third temperature rise process (FIG. 11)” is executed instead of the “second temperature rise process (FIG. 6)”. In this process, through each determination process, it is determined to which temperature range (see FIG. 10) the upstream catalyst bed temperature TF and the reference exhaust gas temperature TG belong. Then, glow energization is executed or stopped according to the determination result.

  [Step S410] It is determined whether or not the estimated upstream catalyst bed temperature TFV is lower than the seventh catalyst bed temperature TF7 (example: 250 ° C.). When the relationship of “TFV <TF7” is established, the process proceeds to step S420. When the relationship of “TFV <TF7” is not established, the process proceeds to step S444.

  [Step S420] It is determined whether the estimated upstream catalyst bed temperature TFV is equal to or higher than the sixth catalyst bed temperature TF6 (eg, 180 ° C.). When the relationship of “TFV ≧ TF6” is established, the process proceeds to step S430. When the relationship of “TFV ≧ TF6” is not established, the process proceeds to step S444.

  [Step S430] It is determined whether the estimated reference exhaust temperature TGV is lower than a fifth exhaust temperature TG5 (eg, 310 ° C.). When the relationship of “TGV <TG5” is established, the process proceeds to step S440. When the relationship of “TGV <TG5” is not established, the process proceeds to step S444.

  [Step S440] It is determined whether the estimated reference exhaust temperature TGV is equal to or higher than a fourth exhaust temperature TG4 (eg, 180 ° C.). When the relationship of “TGV ≧ TG4” is established, the process proceeds to step S442. When the relationship of “TGV ≧ TG4” is not established, the process proceeds to step S444.

  [Step S442] Glow energization is started based on the fact that the seventh temperature raising condition is satisfied. When glow energization has already started, it continues to run. After executing the process of step S442, the “third temperature raising process” is temporarily ended.

  [Step S444] Glow energization is prohibited based on the fact that the seventh temperature raising condition is not satisfied. After executing the process of step S444, the “third temperature raising process” is temporarily ended. Note that execution and stop of glow energization in steps S442 and S444 are performed in the same manner as in steps S342 and S344 of the “second temperature raising process”.

<Effect of embodiment>
As described above in detail, according to the exhaust system temperature control apparatus for an engine according to the fourth embodiment, the effects (3) to (6) according to the first embodiment, and the second embodiment described above. In addition to the function and effect of (7) above, the following function and effect can be obtained.

  (9) In the exhaust system temperature control apparatus of the present embodiment, when the estimated upstream catalyst bed temperature TFV is equal to or higher than the seventh catalyst bed temperature TF7 in a state where the regeneration control execution condition is satisfied, that is, by execution of glow energization. When the obtained increase in exhaust temperature does not contribute to continuing the basic fuel addition, glow energization is prohibited. In this way, by prohibiting glow energization when it is estimated that the upstream catalyst bed temperature TF is maintained at a temperature equal to or higher than the required value (second catalyst bed temperature TF2) without performing glow energization, it is unnecessary. The execution of glow energization is suppressed. As a result, the life of the glow plug 15 and the fuel consumption rate can be improved.

(Fifth embodiment)
A fifth embodiment of the present invention will be described with reference to FIG.
The exhaust system temperature control device of the present embodiment applies the following changes to the setting mode of the third embodiment with respect to the setting mode of the glow energization execution range based on the upstream catalyst bed temperature TF and the reference exhaust gas temperature TG. It is configured as a control device. Except for the changes described below, the same configuration as that of the third embodiment is employed.

<Main changes in playback control processing>
As shown in FIG. 12, in the “regeneration control process” of the present embodiment, the region of the upstream catalyst bed temperature TF is the following regions (a) to (c), and the region of the reference exhaust gas temperature TG is the following (d). To (f), and the execution mode of glow energization is set based on the temperature region to which the upstream catalyst bed temperature TF and the reference exhaust gas temperature TG belong.
(A) Catalyst bed temperature region FH: The first catalyst bed temperature TF1 or more and less than the sixth catalyst bed temperature TF6.
(B) Catalyst bed temperature region FF: Fifth catalyst bed temperature TF5 or higher.
(C) Catalyst bed temperature region FI: 6th catalyst bed temperature TF6 or more and less than 5th catalyst bed temperature TF5.
(D) Exhaust temperature region GE: not lower than the first exhaust temperature TG1 and lower than the fourth exhaust temperature TG4.
(E) Exhaust temperature region GJ: 7th exhaust temperature TG7 or more.
(F) Exhaust temperature region GK: 4th exhaust temperature TG4 or more and less than 7th exhaust temperature TG7.

  Specifically, this condition is established, assuming that the upstream catalyst bed temperature TF belongs to the catalyst bed temperature region FI and that the reference exhaust gas temperature TG belongs to the exhaust temperature region GK as the eighth temperature rise condition. Glow energization is performed based on this. On the other hand, when the eighth temperature rise condition is not satisfied, glow energization based on the condition that the regeneration control execution condition is satisfied is prohibited. The exhaust gas temperature region GK corresponds to a specific range set in advance with respect to the exhaust gas temperature. The seventh exhaust temperature TG7 corresponds to a boundary temperature set in advance as a threshold for the exhaust temperature. In the “regeneration control process” of the present embodiment, the seventh exhaust temperature TG7 is set to 250 ° C.

  When the reference exhaust temperature TG is equal to or higher than the seventh exhaust temperature TG7, it can be expected that the reference exhaust temperature TG is maintained at a temperature equal to or higher than the second exhaust temperature TG2 without performing glow energization in accordance with the addition of the regenerated fuel. . Therefore, in a state where the reference exhaust temperature TG belongs to the exhaust temperature region GK, glow energization is executed because the increase in exhaust temperature obtained by execution of glow energization does not contribute to continuing basic fuel addition or basic post injection. Even so, it can be considered useless. Therefore, in the present embodiment, the seventh exhaust temperature TG7 is stored in advance in the electronic control unit 9 as a value for determining whether or not the execution of glow energization is in vain.

  The seventh exhaust temperature TG7 can be set as a value belonging to a range that is equal to or higher than the second exhaust temperature TG2 and lower than the regenerated catalyst bed temperature TRfin (or the third exhaust temperature TG3). Further, it can be set as a threshold value of the reference exhaust gas temperature TG that can be expected to maintain the reference exhaust gas temperature TG at a temperature equal to or higher than the second exhaust gas temperature TG2 without executing glow energization. It should be noted that since the exhaust gas temperature actually changes in accordance with the engine operating state, even when the glow energization is stopped based on the reference exhaust gas temperature TG being equal to or higher than the seventh exhaust gas temperature TG7, the reference is thereafter The exhaust temperature TG is not necessarily maintained at a temperature equal to or higher than the second exhaust temperature TG2. That is, the seventh exhaust temperature TG7 does not guarantee that the reference exhaust temperature TG is reliably maintained at a temperature equal to or higher than the second exhaust temperature TG2.

  In the “regeneration control process” of the present embodiment, a part of the “third temperature increase process (FIG. 11)” of the fourth embodiment is changed as follows. That is, in the process of step S430, it is determined whether or not the estimated reference exhaust temperature TGV is lower than the seventh exhaust temperature TG7 (example: 250 ° C.). When the relationship of “TGV <TG7” is established, the process proceeds to step S440. When the relationship of “TGV <TG7” is not established, the process proceeds to step S444. In the process of step S442, glow energization is executed based on the fact that the eighth temperature raising condition is satisfied. In the process of step S444, glow energization is prohibited based on the fact that the eighth temperature raising condition is not satisfied.

<Effect of embodiment>
As described above in detail, according to the exhaust system temperature control device for an engine according to the fifth embodiment, the operations (2), (3), (4) and (6) according to the first embodiment described above. In addition to the effect and the effect (7) of the second embodiment, the following effect can be obtained.

  (10) In the exhaust system temperature control device according to the present embodiment, when the reference exhaust temperature TG is equal to or higher than the seventh exhaust temperature TG7 in a state where the regeneration control execution condition is satisfied, that is, exhaust obtained by executing glow energization. When the increase in temperature does not contribute to continuing the basic fuel addition, glow energization is prohibited. In this way, unnecessary glow energization is performed by prohibiting glow energization when it is estimated that the reference exhaust temperature TG is maintained at a temperature equal to or higher than the required value (second exhaust temperature TG2) without executing glow energization. Execution is suppressed. As a result, the life of the glow plug 15 and the fuel consumption rate can be improved.

(Other embodiments)
In addition, each said embodiment can also be changed and implemented as shown below, for example.
In each of the above embodiments, the configuration in which the execution mode of glow energization is set based on the temperature region to which the upstream catalyst bed temperature TF and the reference exhaust temperature TG belong is employed. However, for example, the following changes may be made. That is, it is possible to change to a configuration in which the execution mode of glow energization is set based only on the upstream catalyst bed temperature TF. Moreover, it can also change to the structure which sets the execution aspect of glow electricity supply based only on the reference | standard exhaust temperature TG.

  The execution region of glow energization based on the upstream catalyst bed temperature TF and the reference exhaust gas temperature TG is not limited to the region exemplified in the above embodiments. For example, other execution regions different from the execution regions of the above embodiments can be set by appropriately combining the threshold values of the upstream catalyst bed temperature TF and the reference exhaust gas temperature TG of the above embodiments.

  In the engine 1, the period during which the temperature of the exhaust gas can be raised by execution of glow energization varies depending on the allowable energization time HX of the glow plug 15. That is, as the allowable energization time HX becomes shorter, the period during which the exhaust temperature can be raised by execution of glow energization becomes shorter. Therefore, in order to allow glow energization to contribute more appropriately to the requirements for the upstream catalyst bed temperature TF and the reference exhaust gas temperature TG, the following [Configuration 1] to [Configuration 4] are applied to each of the above embodiments. It can also be applied. Each of the following configurations can be applied to an embodiment including a corresponding threshold value.

  [Configuration 1]: The fourth catalyst bed temperature TF4 is changed to approach the third catalyst bed temperature TF3 as the allowable energization time HX becomes shorter. Specifically, the relationship between the allowable energization time HX and the fourth catalyst bed temperature TF4 is defined before the determination process based on the fourth catalyst bed temperature TF4 and the estimated upstream catalyst bed temperature TFV in the “regeneration control process”. Through the map (see FIG. 13A), the fourth catalyst bed temperature TF4 adapted to the allowable energization time HX at that time is calculated. According to this configuration, glow energization is started in a state where the upstream catalyst bed temperature TF is closer to the third catalyst bed temperature TF3 as the allowable energization time HX becomes shorter. In addition, the frequency at which the upstream catalyst bed temperature TF rises to a temperature equal to or higher than the third catalyst bed temperature TF3 is increased by executing the glow energization.

  [Configuration 2]: The sixth catalyst bed temperature TF6 is changed to approach the second catalyst bed temperature TF2 as the allowable energization time HX becomes shorter. Specifically, the relationship between the allowable energization time HX and the sixth catalyst bed temperature TF6 is defined before the determination process based on the sixth catalyst bed temperature TF6 and the estimated upstream catalyst bed temperature TFV in the “regeneration control process”. Through the map (see FIG. 13B), the sixth catalyst bed temperature TF6 suitable for the allowable energization time HX at that time is calculated. According to this configuration, glow energization is started in a state where the upstream catalyst bed temperature TF is closer to the second catalyst bed temperature TF2 as the allowable energization time HX becomes shorter. However, the frequency at which the upstream catalyst bed temperature TF rises to a temperature equal to or higher than the second catalyst bed temperature TF2 is increased by executing the glow energization.

  [Configuration 3]: The sixth exhaust temperature TG6 is changed to approach the third exhaust temperature TG3 as the allowable energization time HX becomes shorter. Specifically, before performing the determination process based on the sixth exhaust temperature TG6 and the estimated reference exhaust temperature TGV in the “regeneration control process”, a map that defines the relationship between the allowable energization time HX and the sixth exhaust temperature TG6 ( Through FIG. 13 (C), a sixth exhaust temperature TG6 suitable for the allowable energization time HX at that time is calculated. According to this configuration, glow energization is started in a state where the reference exhaust temperature TG is closer to the third exhaust temperature TG3 as the allowable energization time HX becomes shorter. The frequency at which the reference exhaust temperature TG rises to a temperature equal to or higher than the third exhaust temperature TG3 by energization is increased.

  [Configuration 4]: As the allowable energization time HX becomes shorter, the fourth exhaust temperature TG4 is changed to approach the second exhaust temperature TG2. Specifically, before performing the determination process based on the fourth exhaust temperature TG4 and the estimated reference exhaust temperature TGV in the “regeneration control process”, a map in which the relationship between the allowable energization time HX and the fourth exhaust temperature TG4 is defined ( The fourth exhaust gas temperature TG4 suitable for the allowable energization time HX is calculated through (see FIG. 13D). According to this configuration, glow energization is started in a state where the reference exhaust gas temperature TG is closer to the second exhaust gas temperature TG2 as the allowable energization time HX becomes shorter. Therefore, even when the allowable energization time HX is short, The frequency at which the reference exhaust temperature TG rises to a temperature equal to or higher than the second exhaust temperature TG2 by energization is increased.

  In each of the above embodiments, an exhaust system temperature control device that increases the exhaust temperature by executing glow energization is assumed, but an exhaust system temperature control device that increases the exhaust temperature by energizing other electric auxiliary machines is used. The present invention can also be applied to this. Further, the present invention can be similarly applied to an exhaust system temperature control device that increases the exhaust temperature through driving of an auxiliary device that applies a load other than an electrical load to the engine 1. As such an auxiliary machine, for example, an exhaust throttle valve that is provided in the exhaust passage and adjusts the flow rate of exhaust gas can be cited. Incidentally, in an engine equipped with an exhaust throttle valve, the fuel injection amount is increased by increasing the back pressure accompanying the change in the opening degree of the exhaust throttle valve. Therefore, the exhaust temperature can be increased by controlling the exhaust throttle valve. It becomes possible.

  In each of the above embodiments, an exhaust system temperature control device that increases the temperature of the exhaust system in a diesel engine is assumed. However, the control device to which the present invention is applied is limited to the control device exemplified in each embodiment. It is not a thing. In short, in an engine in which the fuel injection amount is corrected to the increase side based on the driving of the auxiliary machine, any control can be used as long as it is an exhaust system temperature control device that increases the temperature of the exhaust system by driving the auxiliary machine. The present invention can also be applied to an apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing a schematic structure of a diesel engine equipped with a control device according to a first embodiment that embodies an exhaust system temperature control device for an engine of the present invention. The graph which shows the correspondence of catalyst bed temperature and exhaust temperature, and the content of regeneration control regarding the "regeneration control process" performed through the exhaust system temperature control apparatus of the embodiment. The graph which shows the correspondence of a catalyst temperature and exhaust temperature, and the content of regeneration control regarding the "regeneration control process" performed through the exhaust system temperature control apparatus of the embodiment. The flowchart which shows the process sequence of the "regeneration | regeneration control process" performed through the exhaust system temperature control apparatus of the embodiment. The flowchart which shows the process sequence of the "1st temperature rising process" performed through the exhaust system temperature control apparatus of the embodiment. The flowchart which shows the process sequence of the "2nd temperature rising process" performed through the exhaust system temperature control apparatus of the embodiment. The timing chart which shows an example of the execution aspect about "regeneration | regeneration control processing" performed through the exhaust system temperature control apparatus of the embodiment. The graph which shows the correspondence of catalyst bed temperature and exhaust temperature, and the content of regeneration control about 2nd Embodiment which actualized the exhaust system temperature control apparatus of the engine of this invention. The graph which shows the correspondence of catalyst bed temperature and exhaust temperature, and the content of regeneration control about 3rd Embodiment which actualized the exhaust system temperature control apparatus of the engine of this invention. The graph which shows the correspondence of catalyst bed temperature and exhaust temperature, and the content of regeneration control about 4th Embodiment which actualized the exhaust system temperature control apparatus of the engine of this invention. The flowchart which shows the process sequence of the "3rd temperature rising process" performed through the exhaust system temperature control apparatus of the embodiment. The graph which shows the correspondence of catalyst bed temperature and exhaust temperature, and the content of regeneration control about 5th Embodiment which actualized the exhaust system temperature control apparatus of the engine of this invention. The graph which shows the correspondence of the allowable energization time of a glow plug, the catalyst bed temperature, and the threshold value of exhaust temperature about other embodiment which actualized the exhaust system temperature control apparatus of the engine of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine, 11 ... Cylinder block, 12 ... Cylinder head, 13 ... Cylinder, 14 ... Combustion chamber, 15 ... Glow plug, 16 ... Alternator, 17 ... Battery, 21 ... Intake manifold, 22 ... Intake pipe, 23 ... Intake passage 24 ... Exhaust manifold, 25 ... Exhaust pipe, 26 ... Exhaust passage, 31 ... Air cleaner, 32 ... Intercooler, 33 ... Throttle valve, 34 ... Turbocharger, 35 ... Compressor wheel, 36 ... Turbine wheel, 5 ... Fuel supply device , 51 ... Injector, 52 ... Fuel tank, 53 ... Fuel pump, 54 ... Common rail, 6 ... Exhaust gas recirculation device, 61 ... EGR pipe, 62 ... EGR cooler, 63 ... EGR valve, 7 ... Exhaust gas purification device, 71 ... Sub Injector, 72 NOx catalytic converter, 73 ... catalyst loaded filter, 9 ... electronic control unit, 91 ... crank position sensor, 92 ... throttle position sensor, 93 ... inlet exhaust temperature sensor, 94 ... outlet exhaust gas temperature sensor.

Claims (4)

The injection control for correcting the fuel injection amount to the increase side based on the drive of the glow plug is performed, and the regeneration control for burning the particulate matter accumulated in the exhaust purification device by raising the temperature of the exhaust system. In an exhaust system temperature control device for an engine that is applied to an engine that is configured to be performed and drives the glow plug based on the execution condition of the regeneration control being satisfied,
A temperature at which the exhaust system temperature is expected not to reach a required value even when the glow plug is driven is defined as a boundary temperature, and when the exhaust system temperature is lower than the boundary temperature, the execution condition is satisfied based on the establishment of the execution condition. An exhaust system temperature control apparatus for an engine, characterized by prohibiting driving of the glow plug and setting the boundary temperature based on a continuous energization allowable time of the glow plug. The exhaust system temperature control device for an engine according to claim 1,
The exhaust purification device is configured to include a catalyst capable of oxidizing an additive, and the regeneration control classifies the active state of the catalyst by setting the temperature of the catalyst as the temperature of the exhaust system. Therefore, a predetermined threshold temperature of the catalyst is set as the required value, and an amount of the additive suitable for the active state of the catalyst is discharged into the exhaust gas based on the catalyst temperature being equal to or higher than the required value. The boundary temperature is set so as to approach the required value as the continuous energization time of the glow plug becomes shorter in a region below the required value. Exhaust system temperature control device. When the glow plug is driven, the fuel injection amount is corrected to the increase side, and the regeneration is performed so that the particulate matter is burned when the amount of the particulate matter accumulated in the exhaust purification device is greater than or equal to a predetermined amount. An engine control apparatus on condition that control is performed, and an exhaust system temperature control apparatus for an engine that drives the glow plug when the regeneration control is performed,
The glow plug is driven when the temperature of the exhaust system is within a specific range, and the size of the specific range and the continuous energization allowable time of the glow plug when the allowable continuous energization time of the glow plug is the allowable time A. The exhaust system temperature control device for an engine is characterized in that the specified range is different from each other when the allowable time B is longer than the allowable time A. The engine exhaust system temperature control device according to claim 3,
A catalyst capable of oxidizing the additive is provided in the exhaust purification device, and the additive is exhausted when a temperature of the catalyst as a temperature of the exhaust system in the regeneration control is equal to or higher than a required value. A control device for the engine, which is further conditional on being supplied
Driving the glow plug when the temperature of the exhaust system is equal to or higher than the boundary temperature, where the temperature defining the specific range is a boundary temperature;
The difference between the boundary temperature and the required value when the continuous energization allowable time of the glow plug is the allowable time A is defined as a temperature difference A, and the continuous energization allowable time of the glow plug is the allowable time B. An exhaust system temperature control apparatus for an engine, wherein the difference between the boundary temperature and the required value is defined as a temperature difference B, and the boundary temperature is set such that the temperature difference A is smaller than the temperature difference B.

Images