JPH0713451B2 - Filter recycling processor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a filter regeneration processing apparatus which is provided in an exhaust system of a diesel engine and collects particulates.

[Conventional technology]

In order to secure the exhaust performance and the particulate trapping performance, this type of filter is sometimes burned with the particulates for regeneration processing. Conventionally, this regeneration time is determined by using this back pressure because the amount of particulate accumulation on the filter and the back pressure on the upstream side of the filter are approximately proportional. The back pressure corresponding to the amount is stored as a two-dimensional map of the engine speed and the accelerator opening, and the regeneration timing is determined according to the operating state at that time.

However, this operating state is premised on a steady state, and if the regeneration time is judged in the transient state, there is a possibility that an error may occur in the judgment. If the regeneration time is too early, even if the particulates ignite, they may be digested in the middle, and if this continues, the amount of particulates in the latter half of the filter will increase and the temperature of the filter will increase during subsequent regeneration. There is a possibility that the filter may melt due to excessive rise. For the purpose of preventing such an erroneous determination of the regeneration timing, Japanese Patent Laid-Open No. 61-1816 proposes a configuration in which the regeneration timing is not determined when the accelerator opening or the like is unstable.

[Problems to be solved by the invention]

When the engine changes from the high load operation state to, for example, the idle operation state, the exhaust system is heated by the high load operation, but in the idle operation, the engine speed is low and the exhaust system is difficult to cool. The back pressure is high due to the high temperature of the gas. Therefore, it is judged that the regeneration time has come even though the filter regeneration time has not been reached, which results in a problem that the regeneration time is too early to sufficiently regenerate the filter as described above.

An object of the present invention is to prevent the regeneration of the filter from being incompletely determined by mistakenly determining the regeneration timing of the filter when the engine changes from the high load operating state to the light load operating state.

[Means for solving problems]

The filter regeneration processing apparatus according to the present invention is configured to incinerate particulates on the filter 15, a pressure sensor 22 provided upstream of the filter 15, and a pressure value detected by the pressure sensor 22. Means A for determining the regeneration time of the filter 15 and the incineration means at the regeneration time.
A filter regenerating unit B for operating 21 is provided, an exhaust sensor 23 provided in the exhaust system, and a temperature change detecting unit C for detecting a temporal change in the exhaust temperature detected by the exhaust temperature sensor 23. The regeneration timing determining means A does not determine the regeneration timing when the temporal change rate of the exhaust temperature has a substantially negative value.

〔Example〕

 The present invention will be described below with reference to illustrated embodiments.

FIG. 2 shows an exhaust system of a diesel engine to which an embodiment of the present invention is applied. In this figure, an intake manifold 12 and an exhaust manifold 13 are attached to an engine body 11, and an exhaust pipe 14 is provided at a downstream side base of the exhaust manifold 13. The filter 15 is arranged in the middle of the exhaust pipe 14, and the upstream side and the downstream side of the filter 15 are connected by a bypass pipe 16. A bypass valve 17 for opening and closing the bypass pipe 16 is provided, and the bypass valve 17 is driven to open and close by an actuator 18. The electric heater 21 is provided in the vicinity of the upstream side portion of the filter 15 and generates heat during regeneration of the filter 15 to burn the particulates accumulated in the filter.
The pressure sensor 22 is provided on the upstream side of the filter 15 of the exhaust pipe 14 and on the downstream side of the branched portion of the bypass pipe 16,
The back pressure on the upstream side of the filter 15 is detected. Exhaust temperature sensor 23
Is the downstream side of the filter 15 of the exhaust pipe 14 and the bypass pipe.
The temperature of the exhaust gas passing through the filter 15 is detected on the upstream side of the collection portion of 16.

Normally, the bypass valve 17 is closed and the electric heater 21 is not energized. In this state, the filter 15 collects particulates in the exhaust gas. When the amount of collected particulates reaches a predetermined amount, the bypass valve 17 is opened to reduce the amount of exhaust gas flowing into the filter 15, and the electric heater 21 is energized. As a result, the particulates are heated and ignited. After this ignition, the power supply to the heater 21 is cut off. Particulate burning filter
It propagates to the rear end of 15, whereby the particulates on the filter 15 are burned and removed, and the regeneration is completed. Then, the bypass valve 17 is closed, and the collection of particulates is restarted.

By the way, the judgment of the regeneration time of the filter 15 is usually made by the filter 15
This is done by measuring the back pressure of. That is, there is a correlation between the amount of particulates accumulated on the filter 15 and the back pressure, and when the back pressure reaches a predetermined value, the filter 15 is regenerated. More specifically, the back pressure value corresponding to the regeneration time is stored in the memory of the microcomputer as a two-dimensional map of the accelerator opening and the engine speed, and the back pressure value is changed according to the engine condition at that time. It is arranged to judge whether or not the value of the reproduction time has been reached. In the present embodiment, the exhaust gas temperature is measured, and as will be described later in detail, when the influence of preheating of the exhaust system on the back pressure is large, that is, the temporal change rate of the exhaust gas temperature has a practically negative value. It is configured not to judge the reproduction time.

The exhaust temperature sensor 23 is provided on the downstream side of the filter 15 in order to measure the preheating state of the filter 15 as easily as possible. In the present embodiment, a thermistor is used as the exhaust temperature sensor 23. The thermistor has a measurement accuracy of about ± 30 ° C, which is not suitable for accurate temperature measurement, but as shown in Fig. 3, its resistance value decreases monotonically with increasing exhaust gas temperature. It is suitable for determining whether the exhaust system is cooled or heated.

As shown in FIG. 2, the determination of the regeneration time of the filter 15 and the regeneration process are performed by a control circuit composed of a microcomputer.
Performed by 31. The control circuit 31 includes a micro processing unit (MPU) 32, a memory 33, and an input port 3
4 and an output port 35, which are interconnected by a bus 36. In addition to the pressure sensor 22 and the exhaust temperature sensor 23, the accelerator sensor 24 and the rotation speed sensor 25 are connected to the input port 34. The accelerator sensor 24 detects the opening degree of an accelerator lever provided in a fuel injection pump (not shown), and the rotation speed sensor 25 detects the engine rotation speed. On the other hand, the actuator 18 and the electric heater 21 are connected to the output port 35 via the drive circuit 26. Then control circuit
31 Based on the input signals from the respective sensors 22, 23, 24, 25, the regeneration timing of the filter 15 is determined.When it is determined that the regeneration timing is reached, the actuator 18 is driven to open the bypass valve 17 and The heater 21 is energized to regenerate the filter 15.

FIG. 4 shows the main routine of the filter regeneration processing executed by the control circuit 31. In step 101, it is determined whether it is time to regenerate the filter 15 at present, and as will be described later, if it is time to regenerate, the flag f is set to 1. In step 102, if the flag f is 1, the actuator 17 and the heater 21 are operated to perform the regeneration process of the filter 15, and conversely, if the flag f is not 1, nothing is done. In step 103, if the flag f is 1,
When the bypass valve 17 is closed, the back pressure is detected by the pressure sensor 22, the quality of the reproduction result is judged, and the flag f is cleared to 0. On the contrary, if the flag f is not 1, nothing is done. In the regeneration good / bad determination, if the back pressure is lower than a predetermined value, it is determined that the regeneration is performed favorably, and if the back pressure is high, it is determined that the regeneration is not conducted favorably, and a warning lamp (not shown) is turned on.

FIG. 5 shows a reproduction timing determination routine executed in step 101 of the main routine.

In steps 201 to 209, the state of fluctuation of the accelerator opening ACCP and the engine speed NE is checked every 10 msec. First, in step 201, it is determined whether 10 msec has elapsed after entering this step, and if 10 msec has not elapsed, this step
Return to before 201, but if 10 msec has passed, step 202 ~
Run 208. That is, when the current accelerator opening ACCP is larger than the maximum value AMAX so far in step 202, the routine proceeds to step 203, where the accelerator opening ACCP is replaced with a new maximum value AMAX, and in contrast, the current accelerator opening ACCP is set. Is less than or equal to the maximum value so far, step 20
Go to 4. At step 204, the current accelerator opening ACCP
Is smaller than the minimum value AMIN so far, step 205
Then, the accelerator opening ACCP is replaced with a new minimum value AMIN. On the other hand, when the current accelerator opening ACCP is equal to or greater than the previous minimum value AMIN, the current accelerator opening ACCP is changed to the maximum value AMAX. And the minimum value AMIN, and then steps 206 to 209 are executed. If the current engine speed NE is larger than the maximum value NMAX so far in step 206, the maximum value NMAX is replaced in step 207, and if the current engine speed NE is smaller than the minimum value NMIN so far in step 208, step Minimum value N at 209
Replace MIN. Then, the maximum value AMAX or the minimum value AMIN of the accelerator opening is updated, and the maximum value NMAX or the minimum value NMIN of the engine speed is updated.

In steps 211 to 215, it is determined whether the engine is in a steady state. In step 211, it is determined whether or not 1 sec has elapsed after entering this step. If 1 sec has not elapsed, the process returns to the step before step 201, but if 1 sec has elapsed, the process proceeds to step 212. In step 212, it is judged whether or not the difference between the maximum value AMAX and the minimum value AMIN of the accelerator opening is larger than 1 °, and if it is larger, it is judged that the engine is not in a steady state, and in step 213, the accelerator opening and the engine are opened. Each maximum value AMAX, NMAX of rotation speed and each minimum value AMIN,
Clear NMIN to 0 to end the routine. On the other hand, in step 212, the maximum accelerator opening AMAX and the minimum accelerator opening AMI
When the difference between N is 1 ° or less, the routine proceeds to step 214, where it is judged whether the difference between the maximum value NMAX and the minimum value NMIN of the engine speed is larger than 20 rpm. If this difference is greater than 20 rpm, it is determined that the engine is not in a steady state, and similarly to the case of the accelerator opening described above, step 213 is executed, but if this difference is 20 rpm or less, the engine is in a steady state. Is determined and the maximum values AMAX, NMAX and minimum values AMIN, NMIN of the accelerator opening and engine speed are cleared to 0 in step 215, and then step 221 for checking the temporal change rate of the exhaust temperature is performed. Continue to the following.

In steps 221 to 229, the resistance value P (t) of the exhaust temperature sensor 23 is detected 5 times every 100 msec to obtain the average value R (1), and about 2 seconds after that, the resistance value P (t) is similarly set. ) Average value R (2). In step 221, it is determined whether 100 msec has elapsed since entering this step, and 100 msec
If not, go back to step 221
When msec has elapsed, the parameter t is incremented by 1 in step 222, and then the current resistance value P is replaced with P (t) in step 223. The parameter t is initially defined to be 0 and therefore step 222
In step 223, the resistance value P
(1) is determined. In step 224, the parameter t
Is 5 or more, and if less than 5, step
Return to before 221, but when it is 5 or more, that is, the resistance value P
When (1) to P (5) are defined, the parameter t is cleared to 0 in step 225 and the process proceeds to step 227. In step 227, the parameter t'is incremented by 1. Then, in step 228, the resistance value P
The average value R (t ') of (1) to P (5) is calculated. The parameter t'is initially set to 0, set to 1 in step 227, and the average value R (1) is obtained in step 228. Next, at step 229, it is judged if the parameter t'is 2 or more, and if not 2 or more, the routine proceeds to step 230. In step 230, it is determined whether or not 2 seconds have passed since this step was entered, and if 2 seconds have not elapsed, the process returns to the step before this step 230, and if 2 seconds have elapsed, step 2
Return to before 21. On the other hand, when it is 2 or more in step 229, 0 is set to the parameter t ′ in step 231. Then, in step 230, the average resistance value R
The measurement timings of (1) and R (2) are separated from each other by 2 seconds or more.

In step 232, the average resistance value R (2) is equal to the average value R (2).
(1) It is determined whether or not it is greater than. When the average value R (2) is larger than the average value R (1), the resistance value of the thermistor of the exhaust temperature sensor 23 increases with time, that is, the exhaust temperature is decreasing. Therefore, the exhaust temperature is still high, and the back pressure is detected to be high, so that the regeneration timing of the filter should not be judged and this routine is ended. On the other hand, if the average value R (2) is not larger than the average value R (1) in step 232, it can be said that the exhaust gas temperature is not lowered and is substantially stable, and then the process proceeds to step 241.

In steps 241 and 242, the magnitude of the back pressure on the upstream side of the filter is detected to determine whether or not it is time to regenerate the filter. That is, at step 241, it is determined whether or not the back pressure P detected by the pressure sensor 22 is equal to or greater than a predetermined value P ₀ determined by the accelerator opening and the engine speed, and the predetermined value P ₀ is determined.
If the above is the case, the flag f for performing the filter regeneration process is set to 1 in step 242, and this routine is ended. On the other hand, when the back pressure P is smaller than the predetermined value P ₀ , it is not necessary to regenerate the filter, and step 24 is performed.
Skip 2 and end this routine. As described in the description of FIG. 4, when the flag f is 1, the filter regeneration processing and the regeneration pass / fail judgment are performed.

In the above embodiment, the judgment of the filter regeneration time was made by the back pressure on the upstream side of the filter.
Alternatively, the differential pressure before and after the filter may be used.

〔The invention's effect〕

As described above, according to the present invention, it is possible to improve the reliability of the filter regeneration processing device without the risk of misjudging the regeneration time of the filter due to the influence of the heat of the exhaust system of the engine.

[Brief description of drawings]

FIG. 1 is a block diagram of the invention, FIG. 2 is a diagram showing an engine to which an embodiment of the present invention is applied, FIG. 3 is a graph showing the relationship between exhaust gas temperature and thermistor resistance value, and FIG. 4 is filter regeneration. FIG. 5 is a flowchart of the reproduction timing determination routine, and FIG. 5 is a flowchart of the main routine of the processing. 15 …… Filter, 16 …… Bypass pipe (bypass passage),
17 …… Bypass valve, 21 …… Heater, 22 …… Pressure sensor,
23 ... Exhaust temperature sensor.

Claims (1)

[Claims] 1. A filter regeneration treatment device provided in an exhaust system of a diesel engine, comprising means for incinerating particulates on the filter, a pressure sensor provided upstream of the filter, and the pressure sensor. Means for judging the regeneration timing of the filter in accordance with the pressure value detected by, the regeneration means of the filter for operating the incineration means at the regeneration timing, the exhaust temperature sensor provided in the exhaust system, and the exhaust temperature And a temperature change detecting means for detecting a temporal change of the exhaust gas temperature detected by the sensor, wherein the regeneration timing determining means determines the regeneration timing when the temporal variation rate of the exhaust gas temperature has a substantially negative value. A filter regeneration processing device characterized by not judging.