JPS63120811A - Filter regenerating device - Google Patents

Abstract

PURPOSE:To instantaneously determine a regeneration timing of a filter and thereby efficiently carry out regeneration, by operating an ignition mechanism for burning a particulate deposited on the filter according to a result of detection of an engine operating condition. CONSTITUTION:A particulate collector 20 includes a filter 23 in a main passage 22, and also includes an electric heater 24 at an inlet of the filter 23. The electric heater 24 is controlled by an ECU 40 to burn a particulate deposited on the filter 23 by heat generation. The ECU 40 inputs signals from various sensors for detecting an engine operating condition, e.g., a vehicle speed signal from a vehicle speed sensor 51. When a vehicle speed is greater than a predetermined value, the ECU 40 instantaneously determines that a regenerable timing of the filter 23 has reached, and immediately start regeneration, thus efficiently carrying out the regeneration of the filter 23.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a filter regeneration processing device that incinerates particulates deposited on a filter provided in an exhaust system of a diesel engine to regenerate the filter.

[Conventional technology]

Exhaust gas from a diesel engine contains particulates whose main component is carbon, and a filter is provided in the exhaust system to collect these particulates. As the amount of particulates accumulated on the filter increases, the filter becomes clogged, which increases ventilation resistance and reduces engine performance, and the particulate collection performance of the filter itself decreases, worsening exhaust gas emissions. I will let you do it. Particulates self-ignite when the exhaust temperature is high, and the filter self-regenerates, but when the exhaust temperature is low, it does not self-ignite, so the particulates are forcibly ignited according to the amount of particulates accumulated, and the filter is regenerated. Need to play. Japanese Patent Publication No. 60-111013
The publication describes a configuration in which a burner is provided opposite the filter, and it is determined whether or not the filter is performing natural regeneration based on the output signal of an exhaust temperature sensor, and if it is determined that the filter is undergoing natural regeneration, the operation of the burner is delayed. is disclosed.

[Problem that the invention seeks to solve]

If natural regeneration is determined based on the output signal of the exhaust gas temperature sensor as in the above configuration, the following problem occurs. In other words, the responsiveness of the exhaust temperature sensor is low, so short-term changes in the exhaust temperature are not detected sufficiently, and as a result, the burner operation is delayed and the filter is not regenerated sufficiently, or conversely, the burner may operate unnecessarily. This may cause the filter to overheat and burn out.

[Means for solving problems]

In order to solve the above-mentioned problems, the filter regeneration processing device according to the present invention is characterized in that the filter ignition mechanism is configured to operate according to the operating state of the engine.

〔Example〕

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

FIG. 1 shows a schematic configuration of a diesel engine equipped with a filter regeneration processing device according to an embodiment of the present invention. The engine body 10 is provided with a fuel injection pump, and this fuel injection pump supplies high-pressure fuel to a fuel injection valve (not shown) by rotating an accelerator lever 13 that is linked to an accelerator pedal 12. is injected into the combustion chamber of each cylinder. The exhaust gas is sent to the particulate collector 20 through an exhaust manifold (not shown), and is discharged into the atmosphere through an exhaust pipe (not shown). The collector 20 has a bypass passage 21 and a main passage 22 that bulges out laterally from the bypass passage 21. A filter 23 is disposed inside the main passage 22, and an inlet of the filter 23 is disposed inside the main passage 22. An electric heater 24 is provided in the section. The electric heater 24 is energized under the control of an electronic control unit (ECU) 40 (described later), generates heat, and ignites and burns the particulates deposited on the filter 23. The control valve 25 provided in the bypass passage 21 normally closes as shown by the solid line to guide the exhaust gas to the main passage 22, and opens as shown by the broken line to bypass most of the exhaust gas while the filter is being regenerated. The inside of the passage 21 is made to flow. The actuator 26 that controls opening and closing of the control valve 25 has a diaphragm 28 inside the shell 27.
A variable pressure chamber 29 is formed, a spring 30 is accommodated in the variable pressure chamber 29, and the variable pressure chamber 29 is connected to a negative pressure source 32 via an on-off valve 31, and the diaphragm 28 is controlled via a link 33. The valve 25 is connected to the valve 25 . Open/close valve 31
is switched under the control of the ECU 40. When negative pressure is introduced into the pressure transformation chamber 29, the actuator 26 opens the control valve 25, and when atmospheric pressure is introduced into the pressure transformation chamber 29, the actuator 26 causes the spring 30 to open the control valve 25. occlusion.

In order to control the electric heater 24 and the control valve 25, the EC
Various signals are input to U40. That is, the vehicle speed sensor 51 sends a signal according to the vehicle speed, the rotation speed sensor 52 sends a signal according to the engine rotation speed, the water temperature sensor 53 sends a signal according to the cooling water temperature, and the exhaust pressure sensor 54 sends a signal according to the exhaust pressure, and the accelerator opening. The degree sensor 55 outputs a signal corresponding to the accelerator opening degree.

As shown in FIG. 2, the ECU 40 includes a one-chip microprocessor 41, a digital buffer 42, and an AD converter 43.
and an output buffer 44.

The one-chip microprocessor 41 includes a central processing unit (CPU) 45, a read-on memory (ROM) 46, a random access memory (RAM) 47, and a timer 48.
and an interface 49, which are interconnected by a bus 50. The output signals of the vehicle speed sensor 51 and the rotation speed sensor 52 are input to the microprocessor 41 via the digital buffer 42, and the output signals of the water temperature sensor 53, exhaust pressure sensor 54, and accelerator opening sensor 55 are converted into digital signals by the AD converter 43. and is input to the microphone o processor 41. The ECU 40 controls the electric heater 24 according to the programs shown in FIGS.
The control valve 25 is opened and closed via the on-off valve 31.

The routines shown in FIGS. 3 and 4 are interrupted at regular intervals. In other words, the timer 48 clocks CP at a constant cycle.
An interrupt request is generated to U45, and CPU 45 executes these routines in response to the interrupt request.

FIG. 3 shows the operating state detection routine. Step 101
Then, the accelerator opening, exhaust pressure, water temperature, engine speed, and vehicle speed at that time are read, and in step 102, the integrated value of the engine speed is determined, and this routine ends.

FIG. 4 shows a filter regeneration control routine.

In step 111, flags f, , f, are set based on the map shown in FIG. FIG. 6 shows whether the vehicle speed and the accelerator opening are such that the heater 24 is energized. That is, when the vehicle speed is less than a predetermined value A, the heater 24 is energized, and the flag f is set.

is set to 1, and if the vehicle speed is higher than a predetermined value A, natural regeneration is possible and the heater 24 is not energized, but if the accelerator opening is larger than a predetermined value B, the heater 24 is in a state of high-speed, high-load operation. As a result, there is a lack of oxygen in the exhaust system, making it difficult for particulates to burn, and flag f2 is set to 1.
Set to .

In step 112, the integrated value of the engine speed is set to the target value N.
It is determined whether or not the water temperature is equal to or higher than the target value No. If the water temperature is equal to or higher than the target value No, it is determined in step 113 whether the water temperature is equal to or higher than a predetermined value To. Even if the integrated value of the engine rotational speed has not reached the target value No, if the exhaust pressure is equal to or higher than the predetermined value Po in step 117, the water temperature is determined in step 113. If the water temperature is lower than the predetermined value To in step 113 and if the exhaust pressure is lower than the predetermined value Po in step 117, the process proceeds to step 118, but if the water temperature is equal to or higher than the predetermined value To in step 113, the process proceeds to step 114.

In step 114, it is determined whether or not the flag fI is set to 1. If the flag f is set to 1, the filter 23 is regenerated in step 115.
116 is executed. In step 115, the current supply time to the heater 24 is 1. Set. This energization time t2 is a predetermined basic energization time t.

It is obtained by adding the additional energization times t and l to the above, but the additional energization time 1. is cleared to O,
Therefore, normally, the energization time t is the basic energization time t.

is set as is. In step 116, the electric heater control routine shown in FIG.
4 is energized.

If the flag f is not set to 1 in step 114, the process proceeds to step 118, where it is determined whether the flag f2 is set to 1.

When the flag f2 is set, the counter C is incremented by 1 in step 119, and then, in step 120, the value of the counter C is converted into additional energization times t and l by multiplying by a coefficient, for example. However, in the case of high-speed, high-load operation, that is, in the area shown in Figure 4,
Additional energizing time 1 corresponding to the time in this state
M is determined.

On the other hand, if the flag f2 is not set in step 118, steps 119 and 120 are skipped and the process proceeds to step 121. In step 121, power supply to the heater 24 is stopped, and in step 122, the control valve 25 is closed.

FIG. 5 shows the electric heater control routine. Step 13
1, the time t is counted up. The time t is cleared to O when the engine is started or at step 138, which will be described later, and is counted up each time step 131 is executed, that is, it indicates the time during which the heater 24 is energized. Next, in step 132, the control valve 25 is opened,
In step 133, the heater 24 is energized. Step 1
At step 34, it is determined whether or not the time t has reached the energization time t. If the time t has not reached the energization time t, the routine is ended as is, but if the time has been reached, the steps from step 135 onwards are executed. That is, when the energization time exceeds 1, the energization of the heater 24 is stopped in step 135, the control valve 25 is closed in step 136, and the regeneration process of the filter 23 is ended. Then, in step 137, the integrated value of the engine rotation speed is cleared to O, and in step 138, the time t is cleared to O, and in step 139, the additional time t and the counter C are each cleared to O,
Exit this routine.

For example, if the integrated rotational speed value is greater than or equal to the target value No, the water temperature is greater than or equal to the predetermined value To, and the vehicle speed is lower than the predetermined value A, the routine in FIG.
．． The routine of FIG. 5 is executed in the order of 131.132.133.134, and the heater 24 is energized. Such processing is repeated for a predetermined energization time t1, and when the energization time 1K has elapsed, steps 135 to 139 are executed, the energization of the heater 24 is stopped, and the filter regeneration processing is completed. When the engine enters the high-speed, high-load operating state shown in the area shown in FIG. 6, the flag f2 is set to 1, so step 1
14, go to step 118, and step 119.12
The process is executed in the order of 0.121° and 122°, and an additional energization time tH corresponding to the time in this operating state is determined.

That is, in this operating state, it is difficult for the filter 23 to naturally regenerate due to the lack of oxygen in the exhaust system, so the energization time 1E of the heater 24 in the subsequent regeneration process is extended by the time that this operating state continues.

As described above, this embodiment is configured to determine the regeneration timing of the filter 23 based on the vehicle speed and energize the electric heater 24, and the responsiveness of the vehicle speed sensor 51 is much better than that of the exhaust temperature sensor. Therefore, the filter 23 can be efficiently regenerated, and there is no fear that the filter 23 will be burnt out due to, for example, heating time of the heater 24 being too long. Further, by extending the energization time of the heater 24 according to the time that the high-speed, high-load state continues, the filter 23 is regenerated more efficiently.

In the above embodiment, the regeneration timing of the filter 23 is determined based on the vehicle speed and the maximum opening degree, but it may also be determined based on the vehicle speed and the fuel injection amount. In this case, the map corresponding to FIG. 6 becomes the one shown in FIG. 7, in which the heater 24 is energized when the vehicle speed is less than a predetermined value A, and the flag f,
is set, and if the vehicle speed is greater than a predetermined value A, and the fuel injection amount is greater than a predetermined value B, a flag f2 is set. Note that the fuel injection amount is determined from the accelerator opening degree and the engine rotational speed with reference to a map (not shown). Other configurations and operations are similar to those of the above embodiment.

FIG. 8 shows yet another example of a map of filter regeneration timing, in which the filter 23 changes depending on engine speed and accelerator opening.
This determines the regeneration period.

When the engine speed is below a predetermined value A, the heater 24 is energized and a flag f is set, and when the engine speed is greater than a predetermined value A and the accelerator opening is larger than a predetermined value B, a flag f2 is set. Other configurations and operations are similar to those of the above embodiment.

Note that the mechanism for igniting particulates on the filter 23 is not limited to the electric heater 24, and may be a burner, for example.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to instantly determine that it is time for the filter to be regenerated and to immediately start the regeneration process, thereby making it possible to efficiently regenerate the filter.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a diesel engine having a filter regeneration processing device according to an embodiment of the present invention, FIG. 2 is a block diagram showing the electronic control unit, FIG. 3 is a flowchart of the operating state B detection routine, and FIG. Figure 5 is a flowchart of the regeneration processing routine, Figure 5 is a flowchart of the electric heater control routine, Figure 6 is a map showing the relationship between engine operating conditions and filter regeneration timing, and Figure 7 is a map of the relationship between engine operating conditions and filter regeneration timing. FIG. 8 is a diagram showing still another example of a map of the relationship between engine operating conditions and filter regeneration timing. 22... Main passage, 23... Filter, 24... Electric heater (ignition mechanism), 40... Electronic control unit, 51... Vehicle speed sensor, 52... Rotation speed sensor, 53. ...Water temperature sensor, 54...Exhaust pressure sensor, 55...Accelerator opening sensor.

Claims (1)

[Claims] 1. Filter regeneration in which an ignition mechanism is provided in close proximity to a filter disposed in an exhaust passage, and when the ignition mechanism operates, particulates accumulated on the filter are ignited and burned. A filter regeneration processing device, characterized in that the processing device is provided with means for detecting the operating state of the engine, and is configured to operate the ignition mechanism according to the operating state of the engine. 2. The filter regeneration processing device according to claim 1, wherein the driving state detection means detects a vehicle speed, and the electric heater is not energized when the vehicle speed is equal to or higher than a predetermined value. 3. The operating state detection means detects the engine rotation speed,
2. The filter regeneration processing device according to claim 1, wherein the electric heater is not energized when the engine speed is above a predetermined value.