JPH0713453B2 - Exhaust gas filter regenerator for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas filter regenerator for an internal combustion engine, and more particularly to a short time without burning the filter while accurately correcting the combustion temperature of the filter based on the set temperature. The invention relates to an exhaust gas filter regenerating device for an internal combustion engine, which can regenerate the filter efficiently.

2. Description of the Related Art At present, DPF (Deisel Particulate Filter) regeneration burners are used for particulates (Particulat) contained in the exhaust gas of internal combustion engines.
It is used as an exhaust emission control system for an internal combustion engine that collects e) with a filter called a trap and enables repeated use of this filter by the fuel injected from the burner.
In this type of exhaust emission control device, for example, Japanese Patent Application Laid-Open No. 56-11580
As shown in the publication, traps provided in the exhaust passage collect fine particles containing carbon as a main component contained in the exhaust gas. After using for a certain period of time, the pressure difference between the inlet pressure and the outlet pressure of the trap is detected to determine the trapped particle state in the trap.When the pressure difference reaches a predetermined level, the burner is activated to The fine particles inside are incinerated to regenerate the filter.

Problems to be Solved by the Invention When the burner temperature is increased during filter regeneration,
When a certain temperature is reached, the particles adhering to the filter explosively start combustion, which causes a radical combustion phenomenon in which the temperature inside the filter rapidly rises. For example, as shown in FIG. 7, when fuel is supplied to the burner at the supply amount A, the extreme combustion phenomenon C is that the filter temperature B is about T = 60.
It occurs at 0 ℃. When the extreme combustion phenomenon occurs, the temperature inside the filter becomes extremely high locally, which causes a large temperature difference locally, which may cause the filter to crack or burn. In order to avoid such a situation, conventionally, regeneration is performed at a time when the amount of carbon trapped is small, or a certain amount of fuel is not supplied to the burner all at once when the burner is ignited, but shown in FIG. As described above, the fuel supply amount is gradually increased, and the fuel supply is performed so as to reach the constant supply amount after a fixed time.

In the above-mentioned conventional method, if the regeneration is performed at a time when the amount of collected carbon is small, the regeneration cycle is shortened, so that the number of times of regeneration is increased, the life of the filter is shortened, and the amount of regeneration fuel is increased. If the fuel is supplied so that the temperature rise of the burner is slow, it takes a long time for regeneration. Since the internal combustion engine cannot be stopped when the filter is regenerated, if the regeneration time is long, the operating time of the internal combustion engine must be extended.

An object of the present invention is to provide an exhaust gas filter regenerating apparatus for an internal combustion engine, which can efficiently regenerate a filter in a short time without burning the filter while continuously correcting the combustion temperature of the filter based on a set temperature. To do.

Means for Solving the Problems An exhaust gas filter regenerating apparatus for an internal combustion engine according to the present invention includes a filter for filtering fine particles contained in exhaust gas discharged through an exhaust pipe of an internal combustion engine, and a filter for collecting the particles. A burner that burns the particulates, an injector that controls the amount of fuel supplied to the burner, a temperature sensor that is disposed adjacent to the filter and that detects the combustion temperature of the filter, and a temperature sensor from the temperature sensor. A control circuit for receiving an electric signal is provided, and the control circuit includes a temperature detection circuit connected to the temperature sensor, a starter circuit provided with a pressure sensor for measuring exhaust gas pressure upstream of the filter, and the starter circuit. And a drive circuit for operating the injector with the output of. This internal combustion engine exhaust gas filter regenerating apparatus stores a clock circuit that generates a time signal by the output of the starting circuit, a preset temperature of the filter corresponding to the elapse of the regenerating time, and the time signal of the clock circuit to store the set temperature of the filter. The control circuit is provided with a temperature correction circuit having a memory circuit that outputs a set temperature signal of the filter and a comparator that compares the output signal of the memory circuit with the output signal of the temperature sensor.

Action The temperature sensor detects the actual combustion temperature of the filter by adjusting the reference to the output signal of the memory circuit that changes according to the elapse of the filter regeneration time, and the output signal of the memory circuit and the output signal of the temperature sensor are detected. Comparison is made by a comparator, and the fuel supply amount to the burner is controlled through an injector by the output difference. As a result, it is possible to efficiently regenerate the filter in a short time without burning the filter while continuously correcting the combustion temperature of the filter that changes over time based on the set temperature.

Embodiment An embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 1, an exhaust gas filter regenerating apparatus 10 for an internal combustion engine according to the present invention includes fine particles contained in exhaust gas exhausted through an exhaust pipe 12 of an internal combustion engine 11 to which a rotation sensor 17 is attached. Filter 13 and the filter
The burner 14 burns the fine particles collected in 13. The burner 14 has an ignition glow plug 18 and an injector 19 for controlling the amount of fuel supplied to the burner 14, and these glow plug 18 and injector 19 are attached to the upstream side of the filter 13. The injector 19 is connected to the fuel tank through a pump or a fuel filter (neither is shown). A temperature sensor 15 and a pressure sensor 16 are provided adjacent to the filter 13, the temperature sensor 15 detects the temperature of the filter 13, and the pressure sensor 16 detects the clogging state of the filter 13, so that Detects exhaust gas pressure on the upstream side. Temperature sensor 15, pressure sensor 16, rotation sensor 1
7, the glow plug 18 and the injector 19, the control circuit 20
Connected to.

As shown in detail in FIG. 2, the control circuit 20 includes a starting circuit provided with a temperature detection circuit 21 connected to a temperature sensor 15 and the pressure sensor 16 for detecting the exhaust gas pressure upstream of the filter 13. 22 and the output of the starting circuit 22
When the output of the drive circuit 23 that operates the temperature detection circuit 21 is generated, the fuel control circuit 24 that reduces the output to be supplied to the injector 19, and the fuel control circuit 24 is operated after the fuel control circuit 24 operates for a certain period of time. Control stop circuit 25 to prevent operation
And a regeneration stop circuit that stops the operation of the injector 19 when the filter 13 reaches the maximum combustion temperature and a predetermined time elapses.
With 26 and. Further, the control circuit 20 detects the combustion temperature of the filter 13 with respect to the passage of the regeneration time, and when the combustion temperature is higher than the set temperature, the fuel increase amount to the burner 14, that is, the fuel amount to be increased per unit time. The temperature correction circuit 27 controls the injector 19 so as to decrease the supply amount and increase the fuel supply amount to the burner 14 when the temperature is lower than the set temperature.

The starting circuit 22 includes an amplifier 30 connected to the pressure sensor 16,
A comparator 32 that compares the output of the amplifier 30 with the output of the reference voltage power supply 31, an AND gate 34 that receives the output of the rotation sensor 17 and the output of the comparator 32 via the amplifier 33, and an AND gate
A one-shot multivibrator 35 that produces a pulse at the output of 34. The output of the multivibrator 35 is RS
It is connected to the set terminal of the flip-flop 36 and the clock circuit 37 of the temperature correction circuit 27. Q of flip-flop 36
The output terminal is connected to the base of the transistor 40 of the drive circuit 23.

The drive circuit 23 includes the transistor 40 and the transistor 40.
Glow plug 18 connected between the collector and the power supply
A transistor 41 having an emitter connected to the collector of the transistor 40, a transistor 42 having a base connected to the collector of the transistor 14, and one end of the transistor 42 connected to the crector and the other end of which is grounded. Coil 45 of injector 19 and transistor 42
Having an emitter connected to the emitter of
44, a resistor 43 connected in parallel to the collector-emitter of the transistor 44, and a resistor 46 connected between the base of the transistor 41 and the power supply. The emitter of transistor 40 is grounded and the base of transistor 41 is resistor 49
It is also connected to the collector of the transistor 53 via.

The temperature detection circuit 21 has a comparator 51 connected to the temperature sensor 15 via an amplifier 50, and a constant voltage power supply 52 that applies a constant voltage to the comparator 51. The output of the comparator 51 is the fuel control circuit.
Base of transistor 53 that constitutes 24 and control stop circuit
It is connected to the collectors of the timer 54 and the transistor 55 which constitute 25. The emitter of the transistor 55 is grounded,
The base is connected to the Q output terminal of the RS flip-flop 56. The set terminal of the flip-flop 56 receives the output of the timer 54.

The output of the amplifier 50 is the comparator 60 that constitutes the regeneration stop circuit 26.
Also, the comparator 60 compares the output of the amplifier 50 with the output of the constant voltage power supply 61. The output of the comparator 60 is the timer 62
Through the reset terminals of the flip-flops 36 and 56.

The temperature correction circuit 27 supplies the time signal generated by the clock circuit 37 to the storage circuit 38 as an address signal, and the storage circuit 38
Generate output to. In the memory circuit 38, the set temperature of the filter 13 over time is stored as digital information. The output of the memory circuit 38 is applied to the comparator 48 through the D / A converter 39. The comparator 48 compares the output of the D / A converter 39 with the output of the temperature sensor 15 supplied via the amplifier 50, and when the temperature of the filter 13 is higher than the set temperature, outputs the low level of the transistor 44. When the temperature of the filter 13 is lower than the set temperature, a high level output is applied to the base of the transistor 44.

In the above-mentioned configuration, the filter 13 is attached due to a large amount of adhered fine particles.
When clogging occurs, the output of the pressure sensor 16 given to the comparator 32 via the amplifier 30 becomes higher than the output of the reference voltage power supply 31, and the comparator 32 sends the output to the AND gate 34. When the internal combustion engine 11 is rotating at a predetermined rotation speed, the output of the rotation sensor 17 is given to the AND gate 34 through the amplifier 33, so that the AND gate 34 generates an output and causes the multivibrator 35 to generate a pulse. Therefore, the flip-flop 36 is set and the base input of the transistor 40 is given from the Q output terminal. Therefore, the transistor 40 is turned on, the glow plug 18 is ignited,
Further, since the emitter current of the transistor 41 flows, the transistor 42 is turned on, and the coil 45 of the injector 19 is energized from the power source through the resistor 43 and the transistor 44.

Clock circuit 37 by the pulse of multivibrator 35
Starts operating, the time information is input from the clock circuit 37 to the memory circuit 38, and the comparator 48 passes through the D / A converter 39.
A set temperature signal is given to. Further, the comparator 48 receives the temperature signal of the temperature sensor 15 through the amplifier 50, and therefore compares it with the set temperature signal. When the temperature signal from the temperature sensor 15 is higher than the above set temperature signal, the comparator 48
Gives a low level current to the base of the transistor 44, so the emitter current of the transistor 44 is small,
The current in the coil 45 is low and the injector 19 supplies a reduced amount of fuel to the burner 14. Conversely, when the temperature signal from the temperature sensor 15 is below the set temperature signal, the comparator 48 provides a high level of current to the base of the transistor 44 so that the injector 19 supplies an increased amount of fuel to the burner 14. . When the temperature signal from the temperature sensor 15 and the set temperature signal are equal, the comparator 48 produces a constant level output. As described above, the temperature correction circuit 27 corrects the temperature of the filter 13. When the comparator 48 produces a constant level of output, the injector 19 burns fuel at maximum flow.
And the filter 13 is heated to a high temperature in a short time.

When the filter 13 is heated to a temperature at which the particles in the filter 13 rapidly start burning, that is, a temperature immediately before the temperature of about 600 ° C., about 500 ° C., the comparator 51 produces an output at the temperature just before this and turns on the transistor 53. To Therefore, the base current of transistor 41 is reduced and the emitter current of transistor 41 is limited, thus reducing the base current of transistor 42 and the current to coil 45 and reducing the fuel gain to burner 14. When a predetermined time elapses in this state, the timer 54 generates an output and the flip-flop 56 is set, so that the transistor 55 is turned on and the transistor 53 is turned off. Therefore, the base of transistor 42 is supplied with a high level of current so that burner 14 rapidly heats filter 13. When the burner 14 reaches the maximum combustion temperature, the comparator 60 produces an output and the timer 62 is activated. Timer 62
Outputs after a certain period of time, and flip-flop 36
And 56 are reset to complete the regeneration of filter 13. The temperature correction circuit 27 performs temperature correction until the maximum combustion temperature is reached and regeneration is completed.

In the exhaust gas filter regenerating device for an internal combustion engine of the present invention,
In order to avoid the rapid combustion temperature of the particles, the fuel passing through the injector 19 can be controlled by various control methods.
For example, as shown in the flowchart of FIG. 3, when clogging is detected in step 70, the glow plug 18 is energized for 60 to 70 seconds and fuel supply is started (step 7
1, 72). In this stage, the fuel supply amount at the time of ignition is small, while detecting the filter temperature, the fuel supply amount is increased, and in the above 60 to 70 seconds, the filter temperature is the rapid combustion temperature of fine particles 500 to 700 ° C, preferably Fuel is supplied so that it reaches just before about 550 to 600 ° C (step 73). At the stage of reaching the rapid combustion temperature (step 74), feedback control from the internal temperature of the filter 13 is performed for about 3 to 4 minutes, and the fuel amount is controlled so that the burner temperature is maintained at about 550 to 600 ° C (step 75). After the lapse of 3 to 4 minutes, the fuel supply amount is increased again and heating is performed by the burner 14 until the maximum combustion temperature reaches about 750 ° C (step 76). When the maximum combustion temperature (regeneration temperature) is reached (step 77), feedback control is performed (step 78) in the same manner as above for about 10 minutes, and the regeneration process is terminated (step 79).

In the method shown in FIG. 3, the filter temperature characteristic and the fuel supply characteristic shown in FIG. 4 are obtained, and in step 75, the fuel is hardly increased and the temperature inside the filter is also sharply increased.

FIG. 5 shows another control method. in this way,
In steps 72 and 73, as in the case of FIG. 3, the fuel supply amount at the time of ignition is reduced, and the fuel supply amount is increased while controlling the fuel supply amount (duty ratio) per unit time and the burner temperature. Further, in step 75, the fuel increase amount is reduced, and in step 76, the fuel supply control is performed so that the burner temperature rise is further slowed down. That is, steps 75 and 76
Then, temperature control is performed so as to reach 750 ° C in 3 to 4 minutes. In the method shown in FIG. 5, the filter temperature characteristic and the fuel supply characteristic shown in FIG. 6 are obtained, and as in the case of FIG. 4, a sharp increase in the temperature inside the filter is slight. The maximum fuel temperature (regeneration temperature) is 750 ° C. At this temperature, the incineration rate of fine particles is about 50-60%, while the temperature of the burner 14 is finally raised to 750-850 ° C. Then, the incineration rate of fine particles can be improved to about 70 to 80% or more.

Modifications are possible in the above-described embodiments of the invention. For example, the control circuit 20 may be configured by a microcomputer and the fuel supply amount may be controlled by a program. In addition, the temperature at which the particulates start to burn rapidly in the filter is usually 600
However, the temperature immediately before the rapid combustion that limits the fuel supply amount is in the range of 500 to 700 ° C, because it varies depending on various factors such as the compositional components of fine particles, the shape of the filter, and the passing state of exhaust gas. Must be set.

EFFECTS OF THE INVENTION In the gas filter regenerating apparatus for an internal combustion engine of the present invention, the reference is adjusted to the output signal of the memory circuit which changes according to the passage of the regenerating time, and the actual combustion temperature of the filter is detected by the temperature sensor and stored. Since the output signal of the circuit and the output signal of the temperature sensor are compared by the comparator, and the fuel supply amount to the burner is controlled through the injector by the output difference,
The combustion temperature of the filter, which changes over time, can be continuously corrected based on the set temperature signal of the storage circuit. Therefore, it is possible to efficiently regenerate the filter in a short time without burning the filter while continuously correcting the combustion temperature of the filter based on the set temperature.

[Brief description of drawings]

FIG. 1 is a schematic view of an exhaust gas filter regenerator for an internal combustion engine according to the present invention, FIG. 2 is an electric circuit diagram showing details of a control circuit used in the regenerator of FIG. 1, and FIG. A flow chart showing an example of a fuel control method in the regenerator of the present invention, FIG. 4 is a graph showing filter temperature characteristics and fuel supply characteristics when the method of FIG. 3 is performed, and FIG.
A flow chart showing another example of the fuel control method in the regenerator of the present invention, FIG. 6 is a graph showing the filter temperature characteristic and the fuel supply characteristic when the method of FIG. 5 is performed, and FIG. FIG. 8 is a graph showing a filter temperature characteristic and a fuel supply characteristic in the conventional exhaust gas filter regenerating device for an internal combustion engine. 10 …… Exhaust gas filter regenerator for internal combustion engine, 11 …… Internal combustion engine, 12 …… Exhaust pipe, 13 …… Filter, 14 …… Burner, 15 …… Temperature sensor, 16 …… Pressure sensor, 17 …… Rotation Sensor, 18 …… glow plug for ignition, 19 …… injector, 20 …… control circuit,

Claims (1)

[Claims] 1. A filter for filtering fine particles contained in exhaust gas discharged through an exhaust pipe of an internal combustion engine, a burner for burning fine particles collected by the filter, and a fuel for supplying to the burner. An injector that controls the supply amount,
A temperature sensor that is disposed adjacent to the filter and that detects a combustion temperature of the filter, and a control circuit that receives an electric signal from the temperature sensor are provided, and the control circuit is a temperature detection device that is connected to the temperature sensor. In an exhaust gas filter regenerator for an internal combustion engine, comprising a circuit, a starter circuit provided with a pressure sensor for measuring exhaust gas pressure upstream of the filter, and a drive circuit for operating the injector with the output of the starter circuit, A clock circuit that generates a time signal by the output of the starting circuit; a storage circuit that stores the set temperature of the filter corresponding to the passage of the reproduction time and that outputs the set temperature signal of the filter by the time signal of the clock circuit; A temperature correction circuit having a comparator for comparing an output signal of the memory circuit and an output signal of the temperature sensor is provided in the control circuit. Providing a reference to the output signal of the storage circuit that changes according to the passage of the regeneration time, the actual combustion temperature of the filter is detected by the temperature sensor, and the output signal of the storage circuit and the temperature sensor. The exhaust gas filter regenerator for an internal combustion engine according to claim 1, wherein the output signal of the burner is compared by the comparator, and the fuel supply amount to the burner is controlled through the injector based on the output difference.