JP2000145432A - Exhaust gas purifier for diesel engines - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas purifier for diesel engines that improves regeneration efficiency and shortens regeneration time. SOLUTION: The regeneration period is divided into three time periods for the purpose of control: an ignition time T1 up until close to the particulate ignition time; a combustion propagation time T2 for spreading ignited particulates, and the cooling time T3 during which the filter is cooled after combustion propagation time T2. So that the air intake volume has a negative correlation with the residual quantity of particulates, at least during the latter half of the combustion propagation time T2, an air intake volume Qv is made to change steplessly or in multiple steps (3 or more steps). This makes it possible to improve the regeneration efficiency and shorten the regeneration time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for collecting and regenerating particulate components (particulates) contained in exhaust gas of a diesel engine.

[0002]

2. Description of the Related Art In an exhaust gas purifying apparatus for a diesel engine described in, for example, Japanese Patent Application Laid-Open No. 9-88549, a supply air flow value to be introduced into a filter is determined in accordance with an estimated amount of particulate collected by the filter. The particulates in the filter are burned at the constant supply air flow value.

[0003] In another prior art, a particulate
Ignition period until the igniter, then the particulates
The combustion propagation period, the cooling period for cooling the filter is provided, and the optimal supply air flow value is determined for each period,
The supply air flow control is performed sequentially according to the change pattern of the supply air flow value. The main purpose of such constant air supply flow rate control is that when the ceramics (for example, cordierite or silicon carbide) constituting the filter exceeds a predetermined maximum allowable temperature, burning such as cracks occurs and the filter temperature decreases. This is to prevent a misfire or an extremely low rate of fire spread.

More specifically, by such a conventional constant air supply flow rate control, the flow rate and temperature of the heated air flowing from the heater into the filter can be made constant to fix the amount of heat applied to the filter from the outside. Furthermore,
The change in the amount of combustion heat generated in the filter due to the change in the supply air flow rate can be reduced, and the filter temperature can be maintained within an expected suitable range.

[0005]

However, according to the above-described conventional supply air flow control technique for performing constant supply air flow value control during combustion propagation, particularly during the latter half of the period, combustion propagation proceeds through the filter during combustion. In spite of the fact that combustion can still be sufficiently promoted within the allowable temperature range of the filter, the combustion speed is slow due to the small constant supply flow rate value, and as a result, the required regeneration time and the power required for regeneration are reduced. There is a problem that the amount increases, and there is a problem that combustion is not sufficiently performed at an end portion of the filter far from the heater, so that unburned residue easily occurs.

Of course, it is also possible to enhance the combustion during the combustion propagation, particularly during the latter half of the period by increasing the constant supply flow rate value set during the combustion propagation, particularly during the latter half of the period. In the initial period and the first half of the period, the supply air flow rate becomes large, causing a problem that the degree of progress of the combustion progress of each part of the filter becomes large. More specifically, particulate combustion starts from the end face of the filter on the heater side. Strictly speaking, first, ignition occurs in a part of this end face,
The flame spreads as the combustion propagation surface advances radially and axially from the ignition region. Therefore, if the air supply flow rate is too large in the period immediately after ignition or in the first half of the combustion propagation period, the flow of supply air and heat in the axial direction of the filter will increase rapidly, and the combustion propagation surface will become the end face of the filter. The combustion proceeds in the axial direction from the ignition region before spreading over the entirety, whereby the degree of axial combustion greatly varies in each radial portion of the filter, and finally the regeneration efficiency of the filter (the reciprocal of the residual ratio of particulates) ) Is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an exhaust gas purifying apparatus for a diesel engine capable of improving the regeneration efficiency and shortening the regeneration time.

[0008]

According to the exhaust gas purifying apparatus for a diesel engine according to the present invention, the regeneration period is as follows.
An ignition period up to near the point at which the particulate is ignited, a combustion propagation period during which the ignited particulate is spread, and
After the combustion propagation period, control is performed by dividing into a cooling period in which the filter is cooled.

In this configuration, in particular, at least in the second half of the combustion propagation period, the supply flow rate is stepless or multi-step (three or more steps) so that the supply flow rate has a negative correlation with the remaining amount of particulates. , The reproduction efficiency can be improved and the reproduction time can be shortened. Hereinafter, this will be described in more detail. According to this configuration, at least at the beginning of the latter half of the combustion propagation period, a relatively small supply flow rate is supplied to the filter. As a result, the combustion propagation surface still remaining at the front or center portion of the filter does not rapidly advance in the axial direction due to the generated heat propagation delay, and the degree of axial combustion progress of each radial portion of the filter greatly varies. Can be suppressed.

[0010] At least in the latter half of the combustion propagation period, the supply air flow supplied to the filter is increased. As a result, at least in the latter half of the combustion propagation period, in which the combustion propagation surface has advanced considerably in the axial direction and it is no longer necessary to consider the above-mentioned variation, a sufficient air supply flow rate is supplied to the filter and combustion is performed. The propagation period can be shortened. In addition, the combustion condition in this period, which is far from the filter end surface on the heater side, is difficult to be heated, is less likely to burn, and tends to reduce the spread of fire, is improved, and the remaining combustion in the last period of the combustion propagation period is reduced. Can be.

Second, in the present configuration, the increase of the supply air flow in at least the latter half of the combustion propagation period is carried out steplessly or in multiple stages so as to have a negative correlation with the remaining amount of particulates. . That is, the air supply flow rate is controlled in accordance with the actual remaining amount of particulates. Accordingly, when the original amount of particulates is small and the remaining amount of particulates decreases early, the air supply flow rate is increased early to enhance the combustion, and the combustion is maintained at the rear end side of the filter. , Preventing its transition to the disappearing state. Conversely, the original amount of particulates is large,
If the amount of heat generated by the heat combustion is large from the early stage of the combustion propagation period, it is possible to delay the increase in the supply air flow rate and prevent the filter temperature from rising excessively.

According to a second aspect of the present invention, in the exhaust gas purifying apparatus for a diesel engine according to the first aspect, the air supply means has a characteristic that the air supply flow rate changes with a negative correlation with the remaining amount. . Then, the electric parameter for controlling the rotation speed of the air supply means is fixed in at least a part of at least the latter half of the combustion propagation period. With this configuration, the supply air flow control according to the first aspect can be realized without employing a complicated feedback control system using a sensor.

The details will be described below. For example, in the air supply means having the above characteristics such as a centrifugal blower, the air supply flow rate is linked with the negative value of the absolute value of the residual amount of particulates. Therefore, regardless of the initial amount of particulates, the supply air flow is determined according to the absolute value of the remaining amount of particulates, and the supply air flow is increased as the amount of remaining particulates decreases, thereby shortening the regeneration period. In addition, the air supply flow rate control according to claim 1 for improving the regeneration efficiency can be realized with an extremely simple device configuration in which the rotation speed of the drive motor of the air supply means is fixed.

According to a third aspect of the present invention, in the exhaust gas purifying apparatus for a diesel engine according to the first aspect, a physical quantity related to the remaining amount of the particulates is further detected, and the supply is positively performed based on the physical quantity. Claim 1
Control by the method described. In this way, the supply flow rate is increased at the rate most suitable for the change in the residual particulate amount, without being limited to the characteristic indicating the relationship between the fluid load resistance of the supply means and the supply flow rate. Can be done.

According to a fourth aspect of the present invention, in the exhaust gas purifying apparatus for a diesel engine according to any one of the first to third aspects, a physical quantity related to a supply air flow is further detected, and the air supply is performed based on the physical quantity. When it is determined that the flow rate has reached the predetermined value, the combustion propagation period ends. In this way, it is possible to easily determine the point in time when it is determined that the supply air flow rate has increased and the residual amount of particulates has substantially reached 0, and to immediately proceed to the cooling period at this point in time. With a simple configuration, the reproduction time can be reduced.

As a means for detecting a physical quantity related to the supply flow rate, in the case of employing an intake means in which the supply flow rate increases due to a decrease in the residual amount of particulates, for example, a supply flow rate sensor may be employed. it can. Also, in many types of air supply means, if the residual amount of particulates is reduced and the load resistance of the air supply means is reduced, the power consumption or load current is reduced, the rotation speed is increased, or the air supply flow rate is increased. These increase the amount of particulates,
The remaining amount of the data can be estimated.

Further, the pressure loss of the filter can be detected by a pressure sensor and the residual amount of the particulate can be estimated from the detected value. According to a fifth aspect of the present invention, in the exhaust gas purifying apparatus for a diesel engine according to any one of the first to fourth aspects, a constant supply flow rate value control is further performed during an initial period of a combustion propagation period. Note that this constant supply air flow value is set smaller than the supply air flow in the latter half of the combustion propagation period.

In this manner, the combustion immediately after ignition can be made to be at a constant level that is slower than the latter half without fluctuating due to the residual amount of particulates. The combustion propagation surface is relatively hotter than the inside of the filter before the combustion propagation surface largely advances in the axial direction, so that the combustion propagation surface can proceed at a remarkably high speed in the radial direction of the filter, which facilitates combustion propagation. Thus, it is possible to suppress the variation in the axial direction of the combustion propagation surface in the above, and reduce the unburned residue at the rear end of the filter due to the variation.

According to a sixth aspect of the present invention, in the exhaust gas purifying apparatus for a diesel engine according to any one of the first to fifth aspects, a constant supply flow rate value control is further performed during an ignition period. In this way, the variation in the time from the start of regeneration to the start of ignition (the length of the ignition period), which strongly depends on the variation in the supply flow rate during this ignition period, can be reduced. Deviation of the starting point from the actual ignition point can be suppressed well.

In addition, since the air supply during this period preheats the respective parts of the filter, the fluctuation of the supply air flow during the ignition period can also reduce the fluctuation of the temperature of the respective parts at the start of the combustion propagation period. In addition,
The air supply flow rate and air supply temperature during this ignition period can be controlled in accordance with the outside air temperature, but this control is completely different from the control according to claim 1, and is performed in the initial stage of the combustion propagation period based on the outside air temperature. In order to reduce the variation in the temperature of each part of the filter.

At the end of the ignition period, that is, at the start of the combustion propagation period, the constant supply air flow value control of the supply air flow during the above ignition period or the constant supply air flow value control canceling the influence of the outside air temperature, By controlling the temperature change to be constant, the control can be performed after a fixed time from the start of the ignition period, and the temperature of the end face of the filter facing the heater can be monitored.

According to a seventh aspect of the present invention, in the exhaust gas purifying apparatus for a diesel engine according to any one of the first to sixth aspects, the supply air flow rate is further controlled during the cooling period. By doing so, the filter temperature can be decreased as quickly as possible within a range where the temperature decrease rate of the filter is not too high during the cooling period, and the cooling period can be shortened.

According to an eighth aspect of the present invention, in the exhaust gas purifying apparatus for a diesel engine according to any one of the fifth to seventh aspects, further, the generation of the heating means during the operation of increasing the supply flow rate of the supply means during the combustion propagation period. Reduce the amount of heat generated. In this way, the temperature of the air supplied to the filter can be decreased stepwise or continuously in accordance with the increase in the combustion heat due to the increase in the supply air flow rate in the latter half of the combustion propagation period. Deter, and
Heater power consumption can be saved.

According to the ninth aspect of the present invention, a physical quantity related to the temperature of the filter is detected, and based on the physical quantity, the supply air flow rate is set within a range in which the temperature does not deviate from a predetermined allowable range at least in the second half of the combustion propagation period. Since the control for increasing the pressure is performed, the combustion can be maintained by making the filter temperature closer to the filter permissible temperature than the control according to the first aspect, and the effect according to the first aspect can be further enhanced.

According to the tenth aspect, the tenth aspect is provided.
In the exhaust gas purifying apparatus for a diesel engine described above, the amount of heat generated by the heating means during the operation of increasing the supply flow rate of the supply means after ignition is reduced within a range in which the internal temperature does not deviate from a predetermined allowable range based on the physical quantity. Therefore, the same effect as the eighth aspect can be obtained.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to examples.

[0027]

Embodiment 1 An embodiment of an exhaust gas purifying apparatus according to the present invention will be described with reference to a block diagram shown in FIG. This exhaust gas purifying apparatus has a metal filter housing case 1 and a ceramic honeycomb filter 2 in the filter housing case 1.
Is housed. A heater 3 is disposed facing the upstream end face of the filter 2 at a small interval, and a temperature sensor 4 is disposed between the filter 2 and the heater 3. The temperature sensor 4 may be in close contact with the upstream end face of the filter 2 or the downstream end face of the heater 3.

The heater 3 is provided with a bare nichrome wire,
The filter 2 is stretched in a direction perpendicular to the axial direction of the filter 2 while being supported by an electrically insulating ceramic member (insulating support) fixed to the filter 2. The heater 3 is supplied with electric power from a commercial 200 V AC power supply through a controller 9 described below. An exhaust main pipe 101 and an air supply branch pipe 102 of the diesel engine 100 are connected to an upstream end wall of the filter housing case 1. The end of the air supply branch pipe 102 is connected to the exhaust main pipe 10.
1 may be connected. Reference numeral 5 denotes an electromagnetic valve, 6 denotes an air flow meter, and 7 denotes a blower. When the motor M of the blower 7 is driven, outside air is supplied to the filter 2 through the air supply branch pipe 102.

A pressure hose 103 extends from the air supply branch pipe 102, and a pressure sensor 8 is provided at an end of the pressure hose 103. 104 is a filter and 10
Reference numeral 5 denotes a tail pipe that discharges exhaust gas from the downstream end wall of the filter housing case 1 to the outside. As the blower 7, one having a type in which the flow rate has a negative correlation with the load fluid resistance is employed. As this type, for example, a centrifugal blade type is suitable. This type of blower has a flow rate characteristic in which the flow rate is substantially inversely proportional to the load fluid resistance when the rotation speed is constant.

As the motor M, either an AC motor or a DC motor can be employed. In the former case, the rotation frequency can be usually fixed by fixing the applied frequency except for the induction motor, and in the latter case, the rotation speed can usually be fixed by fixing the applied voltage. The signals from the temperature sensor 4, the air flow meter 6, and the pressure sensor 8 are input to the controller 9, and the controller 9 outputs the motor M of the heater 3, the solenoid valve 5, and the blower 7 based on the calculation result.
Drive control.

The controller 9 is a control device having a microcomputer (not shown) built therein. The microcomputer 9 converts various kinds of input data into digital data, performs arithmetic processing on the converted data, and performs processing on the heater 3, the solenoid valve 5, and the blower 7 The reproduction is executed by controlling the drive of the motor M for driving. Reference numeral 12 denotes an alarm buzzer that issues an alarm when an abnormality occurs. Reference numeral 13 denotes a lamp that notifies the arrival of the regeneration time. Reference numeral 14 denotes a manual switch that instructs the controller 9 to perform a filter regeneration operation. Reference numeral 15 denotes an on-vehicle battery.

The filter 2 is a honeycomb ceramic filter and is fired in a cylindrical shape using cordierite or silicon carbide as a raw material. The filter 2 has a number of vents penetrating both end faces, one of the adjacent vents is plugged at the upstream end and the other is plugged at the downstream end.
Exhaust gas passes through the porous partition between adjacent vents, and only particulates are trapped in the downstream end plug vent and porous partition.

The controller 9 performs feedback control of the current supplied to the heater 3 so that the temperature detected by the temperature sensor 4 is maintained within a predetermined range during the combustion propagation period. This type of binary on / off feedback control is well known, and a detailed description thereof will be omitted. The controller 9 supplies power to the motor M including an AC motor through an inverter circuit capable of changing the voltage applied to the motor M of the blower 7 in a stepless manner. Since the inverter circuit for controlling the output frequency by intermittently controlling the built-in power switching element by the input PWM control voltage has a well-known configuration, detailed description thereof will be omitted. When a DC motor is used as the motor M, the average output DC voltage can be controlled by a PWM control type converter to control the number of revolutions. The flow rate of the blower 7 is controlled by controlling the rotation speed.
Since this type of motor control circuit is well known, a detailed description is omitted.

The operation of the exhaust gas purifying apparatus for a diesel engine will be described below. (Particle collection operation) Diesel engine 10
The exhaust gas discharged from the exhaust pipe 0 is introduced into the filter housing case 1 through the exhaust pipe 101, particulates in the exhaust gas are collected by the filter 2, and the purified exhaust gas is discharged from the tail pipe 105 to the outside. You. During this particulate collection operation, the solenoid valve 5 is shut off and the heater 3
The power supply to the motor M of the blower 7 is also cut off.

In this embodiment, a blower having a flow characteristic having a negative correlation with the load fluid resistance is used as the blower 7. As this type of blower, for example, a blower having a centrifugal air blowing shape is preferable. (Filter regeneration timing determination operation) Next, the regeneration timing determination operation of the filter 2 executed by the controller 9 will be described.

When an ignition switch (not shown) is turned on, a power supply voltage is supplied from the battery 15 to the controller 9, and these are reset initially to start operation. At the same time, a starter (not shown) starts the engine.
Next, the pressure P is read from the pressure sensor 8 and the temperature T is read from the temperature sensor 4. Next, if the engine is operating, it is determined whether or not the pressure P exceeds a predetermined threshold pressure, and if so, the lamp 13 is turned on to request the filter to be regenerated.

(Filter regeneration operation) The operator observes the emission of the lamp 13 and confirms that filter regeneration is necessary.
Switch 1 for filter regeneration during engine shutdown
When 4 is turned on, the filter regeneration routine is executed to regenerate the filter 2. This filter regeneration routine will be described below with reference to the flowchart shown in FIG. 2 and the timing chart shown in FIG. In addition, filter regeneration
The ignition period, the combustion propagation period, and the cooling period are performed in this order.

During the ignition period, the controller 9 first opens the solenoid valve 5, supplies power to the heater 3 and the motor M, supplies heated air to the filter 2, and raises the temperature (S10). The blower driving motor M controls the number of revolutions of the motor M so that the detected supply air flow value output from the air flow meter 6 is maintained at the ignition period target supply air flow value Q1. For this rotation speed control, the output frequency of the inverter circuit may be controlled, but if the motor M is a DC motor, the magnitude of the DC voltage output to the motor M may be controlled.

Next, when the count time T of the timer counting from the start of regeneration reaches a predetermined ignition period T1 (S12), the next combustion propagation period starts, and the number of revolutions of the motor M is reduced. The supply air flow Q is reduced to Q2 smaller than the supply air flow Q1 during the ignition period (S14).
In this embodiment, the length of the ignition period T is controlled by timer control.
However, if the temperature sensor 4 is installed close to or in contact with the front end face of the filter 2,
Since the temperature detected by the temperature sensor 4 is almost similar to the temperature of the front end face of the filter, the ignition period can be ended when the detected temperature exceeds the particulate ignition temperature.

In this embodiment, the reason for reducing the supply air flow Q1 to Q2 after the end of the ignition period is that the spread of fire from the ignition region is prevented from proceeding in the axial direction due to the large supply air flow, and the front end face of the filter is evenly distributed. It is to ignite. It is conceivable to set the supply flow rate during the ignition period to Q2 from the beginning, but if the supply flow rate during the ignition period is small, it is difficult to raise the temperature of the entire filter, and only the front end face of the filter is heated. Nevertheless, the temperature rise at the rear end of the filter is small, and the subsequent axial combustion propagation is adversely affected.

Next, it is checked whether or not T2 time has elapsed after the timer reaches the combustion propagation period (S16). When the timer reaches the combustion propagation period, the combustion propagation surface is formed on the entire front end surface of the filter by suppressing the supply air flow after the ignition. When it is determined that this has occurred, the drive frequency of the motor M is set to a predetermined value, and the rotation speed of the blower 7 is fixed to a predetermined value (S18). This predetermined value is preferably a value close to the supply air flow rate Q2 in a normal particulate amount. Steps S14 and S16 can be omitted. In this embodiment, t2 is set to start at least in the first half of the combustion propagation period.

In this way, when the amount of particulates remaining in the filter is large and the combustion propagation surface is still in front of the relatively high temperature filter, the amount of combustion heat is suppressed by suppressing the supply flow rate. In addition, the axial flame spread speed is prevented from varying at each radial portion of the filter (particularly between a relatively high temperature radial center portion and a relatively low temperature outer peripheral portion).

When the residual amount of particulates in the filter decreases and the combustion propagation surface shifts to the rear of the filter, the supply flow rate is increased due to the decrease in the load fluid resistance of the blower 7, and the combustion heat quantity is increased. Is increased to increase the combustion speed, and assist the combustion at the rear part of the filter where the temperature is lower than at the front end of the filter and the combustion rate tends to decrease.
As the axial spreading speed at the rear of the filter is increased, the remaining axial spreading distance is shortened. Therefore, the radial portions of the filter (particularly, between the relatively high-temperature radial center portion and the relatively low-temperature outer peripheral portion). However, there is no problem even if the axial spread speed in (2) varies somewhat.

Thus, the unburned portion at the rear of the filter can be reduced and the regeneration efficiency can be improved. next,
When a predetermined time Tv, which has been determined in advance from time t2, has elapsed (S20), the heater 3 is turned off and the supply air flow Q is set to a large predetermined value Q3 (S22). As a result, the filter 2 is cooled by the cold air supply and cooled.

Next, when the time from t3 reaches a predetermined cooling period T3 (S24), the solenoid valve 5 is turned off, the blower 7 is turned off, and the regeneration operation ends.

[0046]

Embodiment 2 Another embodiment will be described below. In this embodiment, as shown in FIG. 4, at step S20 in FIG. 2, the residual amount of particulates is checked, and when it is determined that the residual amount is 0, the combustion propagation period ends, and the process proceeds to the cooling period. It is like that.

In this embodiment, whether or not the residual amount of particulates is 0 is determined by whether or not the supply flow rate detected by the air flow meter has reached a predetermined value. By doing so, the length of the combustion propagation period can be minimized, so that the regeneration time can be shortened. (Modification) In addition, the combustion propagation period may be ended when the rate of increase of the supply air flow is saturated or a predetermined time after that.

Alternatively, the end of the combustion propagation period may be determined when the pressure detected by the pressure sensor 8 drops to a predetermined threshold value. The period may end.

[0049]

Embodiment 3 Another embodiment will be described below. In this embodiment, instead of steps S18 and S20 in FIG. 2, as shown in FIG. 5, the pressure Pini (or supply air flow rate Q) detected by the pressure sensor 8 when the blower 7 is driven at the start of the regeneration, as shown in FIG. Tv of the combustion propagation period from the map based on
The change pattern of the supply air flow rate Q during the period is determined.

That is, the blower 7 at the start of reproduction
At the time when a constant supply air flow rate is supplied, the pressure Pini detected by the pressure sensor 8 is accurately determined by the filter 2.
Of the fluid resistance. Since the fluid resistance of the filter 2 changes in accordance with the amount of particulates, the initial amount of particulates can be satisfactorily and accurately estimated from a map based on the pressure Pini.

The initial particulate amount, the change pattern of the supply air flow rate Q during the Tv period of the combustion propagation period, and the filter maximum temperature have a fixed relationship. Therefore, the maximum supply flow rate that can be obtained in the latter half of the combustion propagation period can be determined by substituting the initial particulate amount into a map stored in advance through experiments in a range where the maximum filter temperature does not exceed the allowable temperature. As a result, the reproduction time can be reduced and the reproduction efficiency can be maximized.

(Modification) Instead of the pressure Pini detected by the pressure sensor 8 immediately after the regeneration, always during the combustion propagation period,
The pressure is detected by the pressure sensor 8 and the residual amount of the particulate can be determined based on the detected pressure. However, in this case, it is necessary to detect the flow rate by the flow rate sensor and to detect the fluid resistance of the filter, that is, the remaining amount of particulates, from the flow rate and the pressure. Then, the amount of burned particulates is obtained by subtracting the remaining amount of particulates detected at the present time from the above-mentioned initial amount of particulates, the amount of burned particulates is obtained, the total amount of combustion heat is obtained, and the time from the start of combustion is obtained. Can be estimated.
By supplying the air supply flow rate selected according to the filter temperature, the air supply flow rate can be increased without reaching the filter maximum allowable temperature.

[0053]

Embodiment 4 Another embodiment will be described below. In this embodiment, instead of steps S18 and S20 in FIG. 2, the supply air flow rate is gradually increased based on the temperature detected by the temperature sensor 4 during the Tv period of the combustion propagation period as shown in FIG. It is preferable that the temperature sensor 4 be as close as possible to the filter 2.

In this manner, when the detected temperature is higher than the reference temperature at that time, the rate of increase of the supply air flow is suppressed to prevent the filter temperature from rising excessively, and the detected temperature is lower than the reference temperature at that time. In this case, the rate of increase of the supply air flow rate is increased to enhance combustion, thereby improving regeneration efficiency and shortening regeneration time.

[0055]

Embodiment 5 Next, another embodiment will be described. In this embodiment, the power supply to the heater 3 is controlled so that the detected supply air flow rate Q has a negative correlation between steps S18 and S20 in FIG. Increasing the supply air flow rate Q is effective in reducing combustion residue at the rear of the filter by increasing combustion, but the amount of combustion heat is increased, so that the filter temperature may increase too much.

In this embodiment, although the supply air flow rate is increased in the latter half of the combustion propagation period to increase the burning rate of particulates, the amount of heat applied to the filter from the heater through the air is reduced, so that the filter temperature is prevented from rising excessively. In addition, it is possible to achieve an excellent effect that the reproduction time can be reduced and the reproduction efficiency can be improved. (Modification) In this embodiment, the heater power is changed according to the supply air flow rate Q. However, the heater power is not linked with the supply air flow rate, but is automatically set in the latter half of the combustion propagation period in which the supply air flow rate gradually increases. Alternatively, the heater temperature may be gradually reduced.

(Modification) In this embodiment, the heater power is changed according to the supply air flow rate Q. However, other detected quantities related to the amount of heat generated by combustion, such as pressure, the supply air flow rate and the pressure, The heater power may be controlled according to both.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of an exhaust gas purifying apparatus for a diesel engine of the present invention.

FIG. 2 is a flowchart illustrating a reproduction control operation according to the first embodiment.

FIG. 3 is a timing chart showing changes in temperature and supply air flow during regeneration control in the first embodiment.

FIG. 4 is a flowchart showing reproduction control in another embodiment.

FIG. 5 is a flowchart showing reproduction control in another embodiment.

FIG. 6 is a flowchart showing reproduction control in another embodiment.

FIG. 7 is a flowchart showing reproduction control in another embodiment.

[Explanation of symbols]

2 is a filter, 3 is a heater (heating means), 6 is an air flow meter (physical quantity detection means relating to air supply flow), 7 is a blower (air supply means), 9 is a controller (heating control means, air supply control means)

Claims (10)

[Claims] 1. A filter provided in an exhaust path of a diesel engine for collecting particulates, heating means for heating the particulates deposited on the filter, and a filter for burning the particulates An air supply means for supplying air to the filter, an ignition period up to near the point at which the particulate is ignited, a combustion propagation period for spreading the ignited particulate, and a cooling period for cooling the filter after the combustion propagation period. A heating control unit that controls the amount of heat generated by the heating unit during a regeneration period; and an air supply control unit that controls an air supply flow rate of the air supply unit during the regeneration period. The air supply control means determines that the air supply flow rate of the air supply means is at least the remaining amount of the particulates during at least the latter half of the combustion propagation period. An exhaust gas purification system for a diesel engine, wherein the air supply flow rate changing steplessly or multistage so as to have a negative correlation. 2. The exhaust gas purifying apparatus for a diesel engine according to claim 1, wherein the air supply means has a characteristic that the air supply flow rate changes with a negative correlation with the remaining amount. An exhaust gas purifying apparatus for a diesel engine, wherein the control means performs control for fixing an electric parameter for controlling a rotation speed of the air supply means in at least a part of at least a latter half of the combustion propagation period. 3. The exhaust gas purifying apparatus for a diesel engine according to claim 1, further comprising: a remaining quantity-related physical quantity detecting means for detecting a physical quantity related to the remaining quantity of the particulates; Exhaust gas for a diesel engine, wherein control is performed to drive the air supply means during the combustion propagation period so that the air supply flow rate has a negative correlation with the remaining amount of the particulates based on the physical quantity. Purification device. 4. The exhaust gas purifying apparatus for a diesel engine according to claim 1, further comprising a supply flow rate related quantity detecting means for detecting a physical quantity related to the supply flow rate, wherein the charge control is performed. The exhaust gas purifying apparatus for a diesel engine, wherein the means terminates the combustion propagation period when it is determined that the supply flow rate has reached a predetermined value based on a physical quantity related to the supply flow rate. 5. The exhaust gas purifying apparatus for a diesel engine according to claim 1, wherein said air supply control means controls said air supply at a predetermined air supply flow rate during said initial period of said combustion propagation period. An exhaust gas purifying apparatus for a diesel engine, characterized by driving a gas means. 6. An exhaust gas purifying apparatus for a diesel engine according to claim 1, wherein said air supply control means sets said air supply flow rate to a predetermined value during said ignition period. Engine exhaust gas purification device. 7. The exhaust gas purifying apparatus for a diesel engine according to claim 1, wherein said air supply control means sets said air supply flow rate to a predetermined value during said cooling period. Exhaust gas purification equipment for diesel engines. 8. The exhaust gas purifying apparatus for a diesel engine according to claim 1, wherein said heating control means controls said heating means during an operation of increasing a supply flow rate of said supply means during said combustion propagation period. An exhaust gas purifying apparatus for a diesel engine, wherein the amount of generated heat is reduced. 9. A filter interposed in an exhaust path of a diesel engine for collecting particulates, heating means for heating the particulates deposited on the filter, and a filter for burning the particulates. An air supply means for supplying air to the filter, an ignition period up to near the point at which the particulate is ignited, a combustion propagation period for spreading the ignited particulate, and a cooling period for cooling the filter after the combustion propagation period. A heating control unit that drives and controls the amount of heat generated by the heating unit during a regeneration period; and an air supply control unit that drives and controls an air supply flow rate of the air supply unit during the regeneration period. And a temperature-related physical quantity detecting means for detecting a physical quantity related to the temperature of the filter. An exhaust gas purifying apparatus for a diesel engine, wherein control is performed to increase the supply air flow rate within a range in which the temperature does not deviate from a predetermined allowable range based on the physical quantity during at least a latter half of a seeding period. 10. The exhaust gas purifying apparatus for a diesel engine according to claim 9, wherein the heating control means calculates the heat quantity generated by the heating means during the operation of increasing the air supply flow rate of the air supply means after the ignition. An exhaust gas purifying apparatus for a diesel engine, wherein the internal temperature is reduced within a range that does not deviate from a predetermined allowable range based on the following.