JP4561879B2 - Exhaust sensor regeneration device and intake / exhaust control system using the same - Google Patents

Description

  The present invention relates to an exhaust sensor regeneration device that regenerates an exhaust sensor by removing particulates attached to the exhaust sensor, and an intake / exhaust control system using the exhaust sensor regeneration device.

  Conventionally, it is known that particulates discharged from an internal combustion engine to an exhaust passage are collected by a particulate removal device such as DPF (Diesel Particulate Filter) to prevent discharge of harmful components into the atmosphere (for example, (See Patent Document 1). In Patent Document 1, a regeneration process is performed in which fuel is added to exhaust gas to increase the exhaust gas temperature, and particulates collected by the DPF are burned to regenerate the DPF.

  In recent years, exhaust emission regulations have become stricter, and techniques for reducing harmful components discharged from the internal combustion engine to the exhaust passage as much as possible are being studied. Therefore, it is required that exhaust components in the exhaust passage be detected by exhaust sensors such as an A / F sensor, oxygen sensor, NOx sensor, etc., and intake / exhaust control be performed with high accuracy based on the output signals of these exhaust sensors. Yes. The intake / exhaust control is to control at least one of intake air to the internal combustion engine and exhaust gas from the internal combustion engine, and includes intake air amount control, EGR (Exhaust Gas Recirculation) control, turbo boost pressure control, and the like.

  In general, the exhaust sensor has a structure in which the sensor element is covered with a cover in order to prevent the sensor element from being exposed to water, and the exhaust flows around the sensor element through a vent hole provided in the cover.

  However, since the exhaust sensor installed in the exhaust passage is exposed to exhaust gas, particulates in the exhaust gas may adhere to the exhaust sensor. When the particulates adhere to the exhaust sensor and block the vent hole, the exhaust flow around the sensor element is hindered, and therefore the response time of the output signal of the exhaust sensor is delayed with respect to the state of the exhaust component in the vicinity of the exhaust sensor. As a result, the exhaust component in the exhaust passage cannot be detected with high accuracy by the exhaust sensor. Then, the exhaust component in the exhaust passage is detected based on the output signal of the exhaust sensor, and intake / exhaust control cannot be performed with high accuracy based on the exhaust component.

Therefore, using a regeneration process that regenerates the DPF by burning the particulates collected by the DPF, the particulates adhering to the exhaust sensor are combusted, and the response time of the exhaust sensor is returned to the state before adhering the particulates, It is conceivable to regenerate the exhaust sensor.
JP-T-2006-505748

However, it is difficult to return the exhaust sensor to the original response time by sufficiently burning the particulate adhering to the exhaust sensor only by raising the exhaust temperature.
It is conceivable to add fuel into the exhaust to shorten the interval at which the exhaust temperature rises, and to increase the regeneration frequency of the exhaust sensor to burn the particulates. However, the exhaust temperature rises in the parts installed in the exhaust passage. There is a problem that the load due to the fuel is frequently applied and the fuel consumption deteriorates.

  The present invention has been made to solve the above-described problem, and an exhaust sensor regeneration device that regenerates an exhaust sensor by sufficiently burning particulates adhering to the exhaust sensor without increasing the regeneration processing frequency for the exhaust sensor. It is another object of the present invention to provide an intake / exhaust control system using the same.

  According to the first to eighth aspects of the present invention, when the response time determining means determines that the response time of the exhaust sensor for detecting the exhaust component in the exhaust passage of the internal combustion engine is delayed by a predetermined time or more, the exhaust temperature increasing means The exhaust temperature control means controls the rise in the exhaust temperature in the exhaust passage, and the exhaust flow speed control means controls the increase in the exhaust flow speed in the exhaust passage by the exhaust flow speed increasing means.

  Since not only the rise in the exhaust temperature but also the increase in the exhaust flow velocity is controlled, the particulates adhering to the exhaust sensor are sufficiently combusted, and the exhaust flows around the sensor element of the exhaust sensor. Thereby, the response delay of the exhaust sensor is eliminated, and the exhaust component in the exhaust passage can be detected with high accuracy based on the output signal of the exhaust sensor.

  Furthermore, by controlling both the exhaust gas temperature and the exhaust gas flow rate, the particulate adhering to the exhaust sensor can be efficiently burned by one regeneration process for the exhaust sensor, so that the exhaust gas can be exhausted without increasing the frequency of the regeneration process for the exhaust sensor. The sensor can be regenerated. As a result, it is possible to reduce as much as possible that a load due to a rise in exhaust temperature is applied to the components installed in the exhaust passage, and it is possible to reduce consumption of resources, for example, fuel and electric power required for regeneration of the exhaust sensor.

  According to the second aspect of the present invention, the exhaust flow rate control means instructs the exhaust flow rate increasing means to increase the exhaust flow rate when the response time of the exhaust sensor is delayed for a predetermined time or more and the exhaust flow rate is equal to or lower than the predetermined speed. If the exhaust flow rate is faster than the predetermined speed even if the response time is delayed for a predetermined time or more, the exhaust flow rate increasing means is not instructed to increase the exhaust flow rate.

  Even if the response time of the exhaust sensor is delayed for a predetermined time or more, if the exhaust flow velocity is faster than the predetermined speed, the exhaust flow velocity necessary to sufficiently burn the particulate adhering to the exhaust sensor is secured. There is no need to further increase the current exhaust flow rate. Thereby, unnecessary increase control of the exhaust flow rate can be reduced.

  According to the third aspect of the present invention, the exhaust temperature control means instructs the exhaust temperature raising means to increase the exhaust temperature when the response time of the exhaust sensor is delayed for a predetermined time or more and the exhaust temperature is lower than the predetermined temperature. If the exhaust temperature is higher than the predetermined temperature even if the response time is delayed by a predetermined time or more, the exhaust temperature increasing means is not commanded to increase the exhaust temperature.

  Even if the response time of the exhaust sensor is delayed for a predetermined time or more, if the exhaust temperature is higher than the predetermined temperature, the exhaust temperature necessary to sufficiently burn the particulate adhering to the exhaust sensor is secured. There is no need to further increase the current exhaust temperature. As a result, unnecessary increase control of the exhaust temperature can be reduced.

  According to the fourth aspect of the present invention, the regeneration period estimating means estimates the regeneration period until the regeneration of the particulate filter that collects the particulates in the exhaust gas starts, and the response time of the exhaust sensor is delayed by a predetermined time or more. If the regeneration period estimated by the regeneration period estimation means is less than or equal to a predetermined time, the exhaust flow rate control means does not perform exhaust flow rate increase control on the exhaust flow rate increase means even if the response time determination means determines that The exhaust temperature control means does not perform exhaust temperature increase control on the exhaust temperature increase means.

  That is, even if the response time of the exhaust sensor is delayed by a predetermined time or more, if the regeneration period until the start of regeneration of the particulate filter is less than the predetermined time, the exhaust flow rate increasing means is used only to regenerate the exhaust sensor. The exhaust gas flow rate is not increased and the exhaust gas temperature is not increased by the exhaust gas temperature raising means, and the process waits until the particulate filter is regenerated. This makes it possible to regenerate the exhaust sensor by simultaneously burning the particulate adhering to the exhaust sensor during the regeneration process of the particulate filter that burns the particulate collected by the particulate filter by raising the exhaust temperature. There is. If the exhaust sensor can be regenerated by the regeneration process of the particulate filter, the frequency of the exhaust flow rate increase control and the exhaust temperature increase control performed to regenerate the exhaust sensor can be reduced as much as possible. As a result, resource consumption required to regenerate the exhaust sensor can be reduced as much as possible.

  By the way, when the response time of the exhaust sensor is delayed by a predetermined time or more, it is difficult to perform intake / exhaust control with high accuracy based on the output signal of the exhaust sensor. Therefore, it is desirable to stop the intake / exhaust control based on the output signal of the exhaust sensor until the exhaust sensor is regenerated.

  Therefore, according to the fifth aspect of the present invention, even if the response time determining means determines that the response time of the exhaust sensor is delayed by a predetermined time or more, the regeneration period of the particulate filter estimated by the regeneration period estimating means is predetermined. If the time is less than the time, if the exhaust flow rate control means does not perform the flow rate increase control and the exhaust temperature control means does not perform the temperature rise control, the intake / exhaust control stop means cancels the intake / exhaust control based on the exhaust sensor. Command to control means.

Thereby, it is possible to prevent the intake / exhaust control means from performing the intake / exhaust control based on the output signal of the exhaust sensor whose response time is delayed by a predetermined time or more.
According to the sixth aspect of the present invention, when the intake / exhaust control means is instructed to stop the intake / exhaust control based on the output signal of the exhaust sensor, the intake / exhaust control means performs the intake / exhaust control based on the output signal of the intake air amount sensor.

  Thus, even when the response time of the exhaust sensor is delayed for a predetermined time or more, the intake / exhaust control means stops the intake / exhaust control based on the output signal of the exhaust sensor and performs the intake / exhaust control based on the output signal of the intake sensor. Can be implemented.

According to the seventh aspect of the invention, the intake / exhaust control means performs EGR control as intake / exhaust control.
Therefore, by appropriately regenerating the exhaust sensor, the intake / exhaust control means can accurately calculate the EGR amount to be recirculated to the intake side of the internal combustion engine based on the output signal of the exhaust sensor that detects the exhaust component in the exhaust passage. Can be controlled. Thereby, harmful components discharged from the internal combustion engine to the exhaust passage can be reduced as much as possible.

  The functions of the plurality of means provided in the present invention are realized by hardware resources whose functions are specified by the configuration itself, hardware resources whose functions are specified by a program, or a combination thereof. The functions of the plurality of means are not limited to those realized by hardware resources that are physically independent of each other.

Embodiments of the present invention will be described below with reference to the drawings.
[First Embodiment]
An intake / exhaust control system according to a first embodiment of the present invention is shown in FIG.

(Intake and exhaust control system 10)
The intake / exhaust control system 10 includes an intake air flow sensor (AFM) 12, an EGR valve 20, a DOC (Diesel Oxidation Catalyst) 30, a DPF 40, an electric fan 50, an exhaust temperature sensor 60, an A / F sensor 70, and electronic control. An apparatus (ECU: Electronic Control Unit) 90 is configured. The intake / exhaust control system 10 is a system that controls intake and exhaust of a diesel engine (hereinafter also simply referred to as “engine”) 2. Fuel accumulated in a common rail (not shown) is injected into the engine 2 from the fuel injection valve 4. The fuel injection valve 4 functions as exhaust temperature increasing means by performing at least post injection among after-injection and post-injection described later.

  The AFM 12 detects the amount of intake air that flows into the engine 2. The EGR valve 20 is installed in the EGR passage 110 that connects the intake side and the exhaust side of the engine 2 and controls the amount of EGR that is circulated from the exhaust side to the intake side.

  The DOC 30 is a structure in which an oxidation catalyst such as platinum is supported on a honeycomb structure, and causes the fuel added to the exhaust passage 100 to undergo an oxidation reaction by post injection from the fuel injection valve 4. Due to this reaction heat, the exhaust temperature of the exhaust passage 100 rises.

  The DPF 40, which is a particulate filter, is formed of a honeycomb structure formed of porous ceramic. The inlet side and the outlet side of the exhaust passage formed in the exhaust flow direction of the honeycomb structure of the DPF 40 are alternately sealed. Particulates in the exhaust gas flow into the exhaust passage where the inlet side is not sealed and the outlet side is sealed, and are collected in the pores of the partition walls when passing through the partition walls of the honeycomb structure forming the exhaust passage. Is done. Exhaust gas flows out from an exhaust passage that is sealed on the inlet side and not sealed on the outlet side.

  The electric fan 50 as the exhaust flow velocity increasing means is installed in the exhaust passage 100 downstream of the DOC 30 and upstream of the DPF 40. When the electric fan 50 operates, the exhaust flow velocity of the exhaust passage 100 increases.

The exhaust temperature sensor 60 is installed on the downstream side of the electric fan 50 and on the upstream side of the A / F sensor 70, and detects the exhaust temperature in the vicinity of the A / F sensor 70.
The A / F sensor 70 as an exhaust sensor is a sensor that detects an air-fuel ratio by a limit current depending on, for example, an oxygen concentration in exhaust gas. As the exhaust temperature sensor, an O ₂ sensor that generates an electromotive force based on the oxygen concentration in the exhaust gas may be used.

  The A / F sensor 70 is installed on the downstream side of the exhaust temperature sensor 60 and the upstream side of the DPF 40, and detects the air-fuel ratio in the exhaust passage 100. As shown in FIG. 1B, the A / F sensor 70 covers the periphery of the sensor element 72 with a cylindrical outer cover 74 and an inner cover 80. The sensor element 72 is, for example, a sensor element in which a solid electrolyte body is formed into a low-cylindrical cup shape, or a stacked sensor element in which flat plate-shaped solid electrolyte bodies are stacked.

  A plurality of vent holes 76 are formed in the peripheral wall of the outer cover 74 so as to penetrate the peripheral wall, and a vent hole 78 is formed at the tip. A plurality of louver vent holes 82 are formed in the peripheral wall of the inner cover 80, and a vent hole 84 is formed at the tip. Since the vent hole 82 of the louver on the peripheral wall of the inner cover 80 is formed at a position shifted from the vent hole 76 on the peripheral wall of the outer cover 74, a sensor is provided for condensed water or condensed water generated in the exhaust passage 100. The element 72 has a structure that is difficult to get wet.

  The ECU 90 serving as an exhaust sensor regeneration device includes a CPU, a RAM, a ROM, a rewritable storage device such as a flash memory, an input / output interface, etc. (not shown). The ECU 90 acquires the engine operating state from output signals of various sensors such as the AFM 12, the exhaust temperature sensor 60, the A / F sensor 70, an engine speed sensor (not shown), and an accelerator opening sensor. The ECU 90 controls the injection timing and the injection amount of the fuel injection valve 4 based on the acquired engine operating state. The ECU 90 includes main injection that generates the main torque of the engine based on the engine operating state, and includes pre-injection before main injection, after-injection after main injection, pilot injection before pre-injection, after- Multi-stage injection such as post injection after injection is performed.

  The pilot injection is performed so that air and a small amount of fuel are mixed in advance before ignition by the main injection. The pre-injection suppresses rapid combustion in the main injection by injecting a small amount of fuel before the main injection and burning the fuel in the combustion chamber before the main injection. Thereby, combustion noise and vibration are reduced.

  After-injection purifies exhaust gas by injecting a minute amount of fuel after main injection and burning particulates, which are unburned components generated in the combustion chamber by main injection. By performing after-injection from the fuel injection valve 4, the temperature of the exhaust gas discharged from the engine 2 rises. The post-injection is performed in order to burn particulates collected by the DPF 40 by injecting a small amount of fuel.

The ECU 90 functions as the following means by a control program stored in a storage device such as a ROM or a flash memory of the ECU 90.
(Intake and exhaust control means)
The ECU 90 calculates a target intake air amount from a map or the like based on the engine speed and the engine load. Since the intake air amount changes according to the EGR amount, the ECU 90 controls the target intake air amount by adjusting the EGR amount by controlling the opening of the EGR valve 20 in order to obtain the target intake air amount. In this case, the ECU 90 detects the actual intake air amount (actual intake air amount) based on the output signal of the A / F sensor 70, and performs intake / exhaust control for controlling the EGR amount so that the actual intake air amount becomes the target intake air amount. carry out. For example, when the actual intake air amount detected based on the output signal of the A / F sensor 70 is larger than the target intake air amount, the ECU 90 increases the EGR amount and decreases the actual intake air amount. On the other hand, when the actual intake air amount detected based on the output signal of the A / F sensor 70 is smaller than the target intake air amount, the ECU 90 decreases the EGR amount and increases the actual intake air amount. Thus, ECU90 implements EGR control as intake / exhaust control based on the output signal of A / F sensor 70 as an exhaust sensor. As the intake / exhaust control based on the output signal of the exhaust sensor, the ECU 90 performs an intake air amount control by adjusting the opening degree of the intake valve, a turbo boost pressure control, etc. in addition to the EGR control by adjusting the opening degree of the EGR valve 20. Also good.

(Response time detection means)
In the deceleration operation when the accelerator is off, the ECU 90 cuts off the fuel injection from the fuel injection valve 4, so the exhaust passage 100 has an atmosphere equivalent to the atmosphere. At this time, the ECU 90 determines the time until the output signal of the A / F sensor 70 becomes a value corresponding to the atmosphere after the ECU 90 cuts off the fuel injection from the fuel injection valve 4. Detect as.

  In addition to the fuel cut operation, if the air-fuel ratio in the exhaust passage 100 can be estimated based on the engine operation state, the ECU 90 outputs the output signal of the A / F sensor 70 after shifting to a predetermined engine operation state. The time until the estimated air-fuel ratio value may be detected as the response time of the A / F sensor 70.

(Response time determination means)
As described above, in the A / F sensor 70, the vent hole 82 of the peripheral wall of the inner cover 80 is displaced from the vent hole 76 of the peripheral wall of the outer cover 74 so that the sensor element 72 is not easily wetted. Formed in position. In other words, this configuration is a configuration in which the exhaust gas hardly flows around the sensor element 72 of the A / F sensor 70. As described above, even if the positions of the vent holes 76 and the vent holes 82 formed in the peripheral walls are shifted, if the exhaust gas can pass through the vent holes 76 and 82, the exhaust gas flows around the sensor element 72, and the A / F The sensor 70 can detect the air-fuel ratio of the exhaust passage 100 with high accuracy.

  However, since the A / F sensor 70 is exposed to the exhaust, particulates in the exhaust adhere to the outer cover 74 and the inner cover 80, and the vent holes 76 and 78 of the outer cover 74 or the vent holes of the inner cover 80. Particulates 82 and 84 may be blocked. Then, it becomes difficult for exhaust to pass through the vent holes 76, 78, 82, 84, and the exhaust flow around the sensor element 72 is hindered. As a result, the response time of the A / F sensor 70 that detects the air-fuel ratio in the exhaust passage 100 becomes longer.

  Therefore, the ECU 90 shifts to a predetermined engine operating state in which the air-fuel ratio can be estimated based on the engine operating state, such as a fuel cut operation, and then the output signal of the A / F sensor 70 becomes the estimated air-fuel ratio value. It is determined whether the response time until is delayed by a predetermined time or more. When the response time of the A / F sensor 70 is delayed by a predetermined time or more, the ECU 90 responds because the particulates adhere to the A / F sensor 70 and block the vent holes 76 and 78 or the vent holes 82 and 84. Judge that time is late.

(Exhaust flow rate control means)
When the response time of the A / F sensor 70 is delayed by a predetermined time or more, the ECU 90 burns the particulate adhering to the A / F sensor 70 and removes the particulate adhering to the A / F sensor 70. Judge that it is necessary. For this purpose, it is necessary that the exhaust gas flow rate is faster than a predetermined speed in addition to increasing the exhaust temperature of the exhaust passage 100 by performing after injection or post injection. When the exhaust gas flow rate becomes higher than a predetermined speed, the particulates adhering to the A / F sensor 70 are likely to drop off from the A / F sensor 70, and exhaust gas whose temperature has risen from the vent hole of the outer cover 74 to the inner cover. It is considered that the particulates that reach 80 and adhere to the inner cover 80 are likely to burn. Therefore, when the exhaust gas flow rate is equal to or lower than the predetermined speed, the ECU 90 energizes and operates the electric fan 50 as the exhaust gas flow rate increasing means to increase the exhaust gas flow rate in the exhaust passage 100 from the predetermined speed.

When the exhaust flow velocity is already higher than the predetermined speed, it is not necessary to perform flow velocity increase control for operating the electric fan 50.
(Exhaust temperature control means)
When the response time of the A / F sensor 70 is delayed by a predetermined time or more, the ECU 90 burns the particulate adhering to the A / F sensor 70 and removes the particulate adhering to the A / F sensor 70. Therefore, it is necessary to raise the exhaust temperature of the exhaust passage 100. Therefore, when the exhaust gas temperature is equal to or lower than the predetermined temperature, the ECU 90 commands the fuel injection valve 4 as the exhaust gas temperature raising means to perform at least post injection among after injection and post injection, and sets the exhaust temperature of the exhaust passage 100 to be higher than the predetermined temperature. Raise.

When the exhaust temperature is already higher than the predetermined temperature, it is not necessary to perform after injection or post injection from the fuel injection valve 4.
(Regeneration processing of A / F sensor 70)
Next, regeneration processing of the A / F sensor 70 that is an exhaust sensor will be described based on the regeneration routine of FIG. The reproduction routine of FIG. 2 is always executed. In FIG. 2, “S” represents a step. The ECU 90 executes a routine shown in FIG. 2 by a control program stored in a storage device such as a ROM or a flash memory of the ECU 90.

  In the regeneration routine of FIG. 2, the ECU 90 first detects the air-fuel ratio in S300 based on the output signal of the A / F sensor 70 that is an exhaust sensor. Then, a delay in response time of the A / F sensor 70 for detecting the air-fuel ratio is detected from the value of the air-fuel ratio detected from the A / F sensor 70 and the value of the air-fuel ratio estimated from a predetermined engine operating state.

  The ECU 90 determines whether the response time of the A / F sensor 70 is delayed by a predetermined time (R1) or more (S302), and if the response time delay is shorter than the predetermined time (R1) (S302: No), this routine is executed. finish.

  When the delay of the response time of the A / F sensor 70 is equal to or longer than the predetermined time (R1) (S302: Yes), in S304, the ECU 90 determines whether the exhaust flow velocity in the exhaust passage 100 is equal to or lower than the predetermined speed (V1). Since the exhaust flow rate increases as the engine speed increases, the ECU 90 detects the exhaust flow rate based on the engine speed.

  When the exhaust gas flow velocity is equal to or lower than the predetermined velocity (V1) (S304: Yes), in S306, the ECU 90 energizes the electric fan 50 to forcibly increase the exhaust gas flow velocity, and the process proceeds to S308.

  When the exhaust flow velocity is faster than the predetermined speed (V1) (S304: No), in S308, the ECU 90 determines whether the exhaust temperature in the exhaust passage 100 is equal to or lower than the predetermined temperature (K1). The ECU 90 detects the exhaust temperature based on the output signal of the exhaust temperature sensor 60. If the exhaust gas temperature is higher than the predetermined temperature (K1) (S308: No), the ECU 90 ends this routine.

  When the exhaust temperature is equal to or lower than the predetermined temperature (K1) (S308: Yes), in S310, the ECU 90 determines whether the exhaust temperature in the exhaust passage 100 is equal to or lower than the predetermined temperature (K2). However, K1> K2. When the exhaust temperature is higher than the predetermined temperature (K2) (S310: No), in S312, the ECU 90 instructs the fuel injection valve 4 to perform post injection, and raises the exhaust temperature of the exhaust passage 100 by post injection, and this routine is executed. finish.

  When the exhaust gas temperature is equal to or lower than the predetermined temperature (K2) (S310: Yes), the ECU 90 commands the fuel injection valve 4 to perform after injection in S314 and also commands post injection in S312. The ECU 90 raises the exhaust temperature of the exhaust passage 100 both in the after injection and the post injection, and ends this routine.

  In the first embodiment, when the response time of the A / F sensor 70 is delayed by a predetermined time (R1) or more, in addition to increasing the exhaust temperature by performing at least post injection among after injection and post injection, The fan 50 is driven to increase the exhaust flow velocity. As a result, even if the particulate adhering to the A / F sensor 70 cannot be burned and removed only by increasing the exhaust temperature, the particulate adhering to the A / F sensor 70 can be burned and removed by increasing the exhaust flow velocity. . As a result, since the response time of the A / F sensor 70 is shortened, intake / exhaust control can be performed with high accuracy based on the output signal of the A / F sensor 70.

  Furthermore, by performing both exhaust temperature rise control and flow rate increase control, particulates adhering to the A / F sensor 70 can be efficiently burned and removed by one regeneration process for the A / F sensor 70. The A / F sensor 70 can be reproduced without increasing the frequency of the reproduction process for the A / F sensor 70. As a result, it is possible to reduce as much as possible that a load due to a rise in exhaust temperature is applied to the components installed in the exhaust passage 100, and it is possible to reduce consumption of resources such as fuel and electric power required for regeneration of the A / F sensor 70.

[Second Embodiment]
The configuration of the intake / exhaust control system in the second embodiment of the present invention is substantially the same as that of the first embodiment. In the second embodiment, the ECU 90 functions as a means described below in addition to the means described in the first embodiment by a control program stored in a storage device such as a ROM or a flash memory of the ECU 90.

(Reproduction period estimation means)
Since the DPF 40 collects the particulates in the exhaust passage 100, the particulates accumulate on the DPF 40. When a predetermined amount or more of particulates accumulates, the particulate collection efficiency of the DPF 40 decreases, so it is necessary to regenerate the DPF 40 by burning the particulates accumulated in the DPF 40. The ECU 90 estimates the accumulated amount of particulates accumulated in the DPF 40 based on the operating state history of the engine 2. Then, the ECU 90 estimates the regeneration period until the accumulation amount of the particulates accumulated in the DPF 40 reaches a predetermined amount, and the regeneration process of the DPF 40 for burning the accumulated particulates and removing them from the DPF 40 is started. .

  Then, by adding functions to the ECU 90 as the regeneration period estimating means, the following functions are added to the exhaust flow rate control means and the exhaust temperature control means described in the first embodiment.

(Exhaust flow rate control means)
When post-injection is performed to burn the particulates accumulated in the DPF 40, the exhaust temperature of the exhaust passage 100 rises, so that the particles attached to the A / F sensor 70 during the regeneration process of the DPF 40 are increased. Curate may burn. Therefore, even if the response time of the A / F sensor 70 is delayed by a predetermined time or more, the ECU 90 is relatively quickly because the regeneration period until the regeneration process of the DPF 40 estimated by the regeneration period estimation means is started is less than the predetermined time. If the regeneration process of the DPF 40 is started, the exhaust flow rate increase control for increasing the exhaust flow rate by driving the electric fan 50 is not performed.

(Exhaust temperature control means)
As described above, the particulate adhering to the A / F sensor 70 may burn during the regeneration process of the DPF 40. Therefore, even if the response time of the A / F sensor 70 is delayed by a predetermined time or more, the ECU 90 has a regeneration period that is less than the predetermined time until the regeneration of the DPF 40 estimated by the regeneration period estimation means is started, and is relatively soon. If the regeneration process is started, before the regeneration timing of the DPF 40, the exhaust temperature increase control for increasing the exhaust temperature by instructing the fuel injection valve 4 to perform at least post injection of the after injection and the pilot injection is not performed. .

  It should be noted that the predetermined time of the regeneration period of the DPF 40, which is a criterion for determining whether or not to implement exhaust flow velocity increase control and exhaust temperature rise control, is the amount of power and fuel consumed to regenerate the A / F sensor 70, and The A / F sensor 70 is determined based on the degree of deterioration of emission caused by continuing the state in which the response time of the A / F sensor 70 is delayed for a predetermined time or more.

(Intake / exhaust control prohibition means)
When the response time of the A / F sensor 70 is delayed by a predetermined time or more and the regeneration period until the regeneration of the DPF 40 is less than the predetermined time, the ECU 90 performs intake / exhaust control based on the output signal of the A / F sensor 70. The intake / exhaust control is performed to control the EGR amount so that the actual intake air amount becomes the target intake air amount based on the output signal of the AFM 12.

(Regeneration processing of A / F sensor 70)
Next, the reproduction process of the A / F sensor 70 in the second embodiment will be described based on the reproduction routine of FIG. The reproduction routine of FIG. 3 is always executed. In FIG. 3, “S” represents a step. The ECU 90 executes a routine shown in FIG. 3 by a control program stored in a storage device such as a ROM or a flash memory of the ECU 90. 3 are the same as S304 to S314 in FIG. 2 and will not be described.

  In S320 of FIG. 3, the ECU 90 determines whether intake / exhaust control is being performed based on the output signal of the A / F sensor 70, which is an exhaust sensor. When the intake / exhaust control based on the output signal of the A / F sensor 70 is not performed (S320: No), the ECU 90 ends this routine. In this case, the ECU 90 performs intake / exhaust control based on the output signal of the AFM 12.

  When the intake / exhaust control based on the output signal of the A / F sensor 70 is performed (S320: Yes), the ECU 90 detects the air-fuel ratio based on the output signal of the A / F sensor 70 in S322. Then, a delay in response time of the A / F sensor 70 for detecting the air-fuel ratio is detected from the value of the air-fuel ratio detected from the A / F sensor 70 and the value of the air-fuel ratio estimated from a predetermined engine operating state.

  The ECU 90 determines whether the response time of the A / F sensor 70 is delayed by a predetermined time (R1) or more (S324), and if the response time delay is shorter than the predetermined time (R1) (S324: No), this routine is executed. finish.

  If the response time delay of the A / F sensor 70 is equal to or longer than the predetermined time (R1) (S324: Yes), in S326, the ECU 90 determines whether the regeneration period until the next regeneration start of the DPF 40 is equal to or less than the predetermined time (T1). Determine. When the regeneration period until the next regeneration start of the DPF 40 is longer than the predetermined time (T1) (S326: No), the ECU 90 performs substantially the same processing as S304 to S314 shown in FIG. 2 of the first embodiment in S328 to S338. To complete this routine.

  When the regeneration period until the next regeneration start of the DPF 40 is equal to or shorter than the predetermined time (T1) (S326: Yes), the ECU 90 determines that the response time delay of the A / F sensor 70 is equal to or longer than the predetermined time (R1) ( S324: Yes) In S340, the ECU 90 does not perform forced exhaust flow rate increase control and exhaust temperature increase control by the exhaust flow rate control unit and the exhaust temperature control unit. This is because it is determined that the particulate adhering to the A / F sensor 70 is burned in the next regeneration process of the DPF 40 that is started relatively soon.

  However, if the response time delay of the A / F sensor 70 is equal to or longer than the predetermined time (R1), the ECU 90 determines that the intake / exhaust control cannot be performed with high accuracy based on the output signal of the A / F sensor 70, In S340, the intake / exhaust control based on the output signal of the A / F sensor 70 is stopped, and this routine is terminated.

  As described above, in the second embodiment, even when the delay of the response time of the A / F sensor 70 is equal to or longer than the predetermined time (R1), the regeneration period until the regeneration of the DPF 40 is equal to or shorter than the predetermined time (T1). The forced exhaust flow rate increase control and exhaust temperature increase control by the exhaust flow rate control means and the exhaust temperature control means are not performed, and the particulates adhering to the A / D sensor 70 are to be removed by the next regeneration process of the DPF 40.

  Thereby, the frequency which performs after-injection and pilot injection other than the regeneration timing of DPF40 can further be reduced, and reduction in fuel consumption can be prevented. In addition, oil dilution caused by the post-injection fuel adhering to the cylinder wall surface can be reduced. Furthermore, since it is reduced as much as possible that the load by the exhaust temperature rise is added to the components installed in the exhaust passage 100, damage to the components can be reduced.

In addition, since the frequency of exhaust flow rate increase control for increasing the exhaust flow rate by driving the electric fan 50 is reduced, power consumption can be reduced as much as possible.
[Other Embodiments]
In the above embodiment, the A / F sensor 70 and the O ₂ sensor are exemplified as the exhaust sensor. In addition to this, a NOx sensor may be used as an exhaust sensor for detecting an exhaust component in the exhaust passage. The present invention can be applied as a regenerator to any exhaust sensor as long as particulates in the exhaust adhere and the response time is delayed.

  In the above embodiment, the electric fan 50 is used as an exhaust flow rate increasing means for increasing the exhaust flow rate in the exhaust passage 100. In addition to this, an electromagnetic valve for adjusting the passage area of the exhaust passage 100 may be used as the exhaust flow rate increasing means, and the exhaust flow rate in the exhaust passage 100 may be increased by restricting the passage area of the exhaust passage 100 with the electromagnetic valve. .

  In the above embodiment, the exhaust temperature in the exhaust passage 100 is increased by performing at least the post injection among the after injection and the post injection. On the other hand, a fuel addition valve that directly injects fuel into the exhaust passage 100 is installed upstream of the exhaust temperature sensor, and fuel is injected from the fuel addition valve into the exhaust passage 100 and added, thereby exhausting the exhaust passage 100. The temperature may be increased. In this case, the fuel added from the fuel addition valve may be used for regeneration of the DPF 40.

  As described above, the present invention is not limited to the above-described embodiment, and can be applied to various embodiments without departing from the gist thereof.

The block diagram which shows the intake / exhaust control system by 1st Embodiment. The flowchart which shows the reproduction | regeneration routine by 1st Embodiment. The flowchart which shows the reproduction | regeneration routine by 2nd Embodiment.

Explanation of symbols

2: diesel engine (internal combustion engine), 4: fuel injection valve (exhaust temperature raising means), 10: intake / exhaust control system, 12: AFM (intake air amount sensor), 20: EGR valve, 30: DOC, 40: DPF ( (Particulate filter), 50: electric fan (exhaust flow rate increasing means), 70: A / F sensor (intake and exhaust sensor), 90: ECU (exhaust sensor regeneration device, response time detecting means, response time determining means, exhaust flow rate control) Means, exhaust temperature control means, regeneration period estimation means, intake / exhaust control means, intake / exhaust control prohibition means), 100: exhaust passage

Claims (8)

In an exhaust sensor regeneration device for regenerating the exhaust sensor by removing particulates attached to an exhaust sensor for detecting an exhaust component in an exhaust passage of an internal combustion engine,
Response time detecting means for detecting a response time of the exhaust sensor;
Response time determination means for determining whether the response time detected by the response time detection means is delayed by a predetermined time or more;
When the response time determining means determines that the response time is delayed by a predetermined time or more, an exhaust temperature control means for controlling an increase in the exhaust temperature in the exhaust passage by the exhaust temperature increasing means,
When the response time determining means determines that the response time is delayed by a predetermined time or more, an exhaust flow rate control means for controlling an increase in the exhaust flow rate in the exhaust passage by the exhaust flow rate increasing means;
An exhaust sensor regeneration device comprising:   The exhaust flow rate control means instructs the flow rate increase means to increase the exhaust flow rate when the response time is delayed for a predetermined time or more and the exhaust flow rate is less than a predetermined speed, and the response time is delayed for a predetermined time or more. 2. The exhaust sensor regeneration device according to claim 1, wherein if the exhaust flow velocity is higher than a predetermined speed, the flow velocity increasing means is not instructed to increase the exhaust flow velocity.   The exhaust temperature control means instructs the exhaust temperature increasing means to increase the exhaust temperature when the response time is delayed for a predetermined time or more and the exhaust temperature is not more than a predetermined temperature, and the response time is not less than a predetermined time. 3. The exhaust sensor regeneration device according to claim 1, wherein when the exhaust temperature is higher than a predetermined temperature even if it is delayed, the exhaust temperature increase means is not instructed to increase the exhaust temperature. 4. Further comprising a regeneration period estimating means for estimating a regeneration period until regeneration of the particulate filter that collects particulates in the exhaust gas is started,
Even if the response time determining means determines that the response time is delayed by a predetermined time or more, if the regeneration period estimated by the regeneration period estimating means is less than or equal to a predetermined time, the exhaust flow rate control means Exhaust flow rate increase control is not performed on the increase means, and the exhaust temperature control means does not perform exhaust temperature increase control on the exhaust temperature increase means,
The exhaust sensor regeneration device according to any one of claims 1 to 3, wherein   Even if the response time determination means determines that the response time is delayed by a predetermined time or more, if the regeneration period estimated by the regeneration period estimation means is not more than a predetermined time, the exhaust flow rate control means increases the flow rate. If the exhaust temperature control means does not perform the temperature rise control without performing control, the intake / exhaust control stop means for instructing the intake / exhaust control means to stop the intake / exhaust control based on the output signal of the exhaust sensor is further provided. The exhaust sensor regeneration device according to claim 4, comprising: an exhaust sensor regeneration device according to claim 4.   6. The exhaust sensor according to claim 5, wherein the intake / exhaust control means performs intake / exhaust control based on an output signal of an intake air amount sensor when commanded to stop intake / exhaust control based on the exhaust sensor. Playback device.   The exhaust sensor regeneration device according to claim 5 or 6, wherein the intake / exhaust control means performs EGR control as the intake / exhaust control. An exhaust sensor for detecting an exhaust component of an exhaust passage of the internal combustion engine;
Intake / exhaust control means for performing intake / exhaust control based on the output signal of the exhaust sensor;
An exhaust sensor regeneration device according to any one of claims 1 to 7,
An intake / exhaust control system comprising:

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