JPH04308309A - Particulate filter regenerative device of diesel engine - Google Patents

Abstract

PURPOSE:To provide an exhaust heat recovery type regenerative device which is in a simple steel structure and where filter regeneration can be realized efficiently therein, and so damage of the filter can be sustained through stable combustion. CONSTITUTION:A judgement (S5) of the filter regeneration timing is made by the integrated operating time of a diesel engine, and in the regeneration process a compound control (S8-S12) of the feed-forward control and the feedback control is realized where the target regeneration temperature D0 is calculated based on the operating conditions, an error DELTAD between the target regeneration temperature and the detected temperature (D) of the exhaust gas is calculated, and at the same time, the injection timing is delayed by throttling the intake air in response to the error DELTAD. Then, the exhaust gas temperature is raised and particulates built up on the filter are ignited and combusted by heat of the exhaust gas to regenerate the filter.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a diesel particulate trapper that collects particulates (fine particles such as carbon) contained in the exhaust gas of a diesel engine using a filter having a honeycomb structure made of a heat-resistant material such as ceramic. (hereinafter abbreviated as DPT) relates to a regeneration device that regenerates a filter by burning particulates deposited on the filter.

0002

[Prior Art] In the DPT which is the subject of the present invention, particulates such as carbon particles in the exhaust gas are collected by a filter, so the concentration of particulates in the exhaust gas discharged to the rear of the filter is reduced. , the collected particulates are deposited on the wall of the filter. Therefore,
As the collection time progresses, the filter becomes clogged, which increases the back pressure in the engine's exhaust system. If the back pressure exceeds the limit, the engine will obviously not be able to operate normally. For this reason, when the particulates accumulated on the filter exceed a certain amount, a process called regeneration is required to ignite and burn the particulates to eliminate them and reduce pressure loss.

Conventionally, as a filter regeneration device in such a case, for example, the one described in Japanese Patent Publication No. 60-42331 is known. This conventional device is of the so-called burner type, and is equipped with a particulate regeneration burner, an attached fuel supply device, a burner ignition heater, a combustion air supply system, etc. near the filter, and during regeneration, A configuration was adopted in which combustible particulates (particulates) such as carbon particles attached to the filter were incinerated by burning the burner.

0004

However, this conventional regenerator requires a particulate combustion burner and its auxiliary equipment, and has a complicated structure. Another problem was that it was difficult to stabilize the fuel in the burner. In addition, there was also the problem that energy loss occurred due to the combustion in the burner.

The present invention was completed with the aim of providing a regenerator that can efficiently regenerate a filter with a simple configuration and that does not cause damage to the filter due to stable combustion.

[0006]

[Means and operations for solving the problems] In order to achieve the above object, the present invention collects particulates in the exhaust gas of a diesel engine with a filter, and collects particulates with the filter at a predetermined time. In a particulate filter regeneration device for a diesel engine that regenerates a filter by burning particulates, a regeneration timing instructing means directly or indirectly detects the state of collection of particulates in the filter and instructs the timing of regeneration processing. and exhaust temperature detection means for detecting exhaust temperature near the filter;
When the regeneration timing is instructed by the regeneration timing instruction means, based on the exhaust temperature detected by the exhaust temperature detection means and the target regeneration temperature necessary for combustion of the particulates,
The present invention is characterized in that it includes exhaust temperature feedback control means for feedback controlling the combustion conditions of the diesel engine so as to maintain the exhaust gas temperature near the filter within the range of the target regeneration temperature.

According to the particulate filter regeneration device for a diesel engine of the present invention, when a predetermined regeneration time is instructed by the regeneration time instruction means, the exhaust temperature feedback control means refers to the detection result of the exhaust temperature detection means. At the same time, the combustion conditions of the diesel engine are feedback-controlled to maintain the exhaust temperature near the filter within the target regeneration temperature range necessary for particulate combustion. Then, the particulates adhering to the filter are ignited by the exhaust temperature and burned. As a result, the filter is regenerated.

As described above, the diesel engine particulate filter regeneration device of the present invention incinerates and regenerates combustible deposits on the filter using the exhaust thermal energy of the diesel engine itself that should collect particulates. This is a completely new device that can be called an exhaust heat type regenerator.

[0009] Although the present invention has already been completed with the structure set forth in claim 1, in actually applying it,
Furthermore, it is recommended to take into account the following general points and systemize them. In diesel engines, exhaust temperature generally depends on the load (injection amount)
, changes depending on rotation speed, intake air volume, injection timing, etc. Of these, the load and rotation speed are variables that are arbitrarily set according to the operating conditions desired by the driver.

In general, even if the load and rotation speed are arbitrarily set, under normal conditions without filter regeneration, the throttle valve is kept at an opening that does not cause the effect of throttling the intake air in order to reduce intake air loss as much as possible. . Similarly, under normal conditions, an appropriate standard value for the injection timing is set in consideration of the engine efficiency, the concentration of nitrogen oxides contained in the exhaust gas, and the like.

On the other hand, in a diesel engine, even if the load and rotation speed are constant, if the throttle valve is throttled within a certain range to reduce the intake air or retard the injection timing, the exhaust temperature will decrease. It has the property of rising.

[0012] Therefore, in adjusting the exhaust temperature in a specific system of the present invention, as an example, it is possible to cite a configuration in which the throttle amount of an intake throttle valve disposed in the intake system of a diesel engine is electrically adjusted. can. That is, the exhaust temperature can be adjusted by adjusting the intake air amount among the combustion conditions of the diesel engine. Note that the intake throttle valve used for adjusting the exhaust gas temperature may be the throttle valve itself linked to the accelerator, or another dedicated sub-throttle valve may be provided.

Furthermore, the exhaust temperature can be adjusted by electrically adjusting the injection timing of the injection pump that injects fuel into the diesel engine, and both the intake throttle valve and the fuel injection timing can be adjusted. It's okay.

In other words, when the time has come for the filter to be regenerated, by tightening the throttle valve or retarding the injection timing from the standard value, or by using both in combination, the temperature of the exhaust gas is raised and the deposits on the filter are reduced. Particulates can be ignited and burned. Note that the same effect can be achieved by adjusting combustion conditions other than these, as long as they are effective in increasing the exhaust gas temperature and are suitable for feedback control.

If the exhaust heat type regeneration according to the present invention is performed as described above, there is no need to prepare a special energy source, and stable regeneration can be achieved by applying thermal energy evenly to the filter with a simple configuration.

By the way, the temperature at the time of filter regeneration, that is, the regeneration temperature, is determined only by the exhaust heat energy of the engine before the particulates are ignited, but once the particulates are ignited, the combustion energy is added. Therefore,
The exhaust gas temperature on the outlet side of the filter increases accordingly. However,
Attempting to determine this amount of increase by calculation or other means is troublesome and it is not possible to estimate a value with high accuracy.

Furthermore, if the degree of intake air throttling or the amount of retardation of the injection timing is not appropriate during regeneration, the exhaust gas temperature will be inappropriate and particulates may not be ignited and burned sufficiently, resulting in poor regeneration. In addition, the temperature rise or temperature rise rate of the filter may become excessive, and the filter may be damaged. To prevent these, it is necessary to carefully control the temperature during regeneration.

The particulate filter regeneration device according to claim 1 is configured to detect the exhaust gas temperature near the filter and perform feedback control, so that the temperature rise during regeneration after ignition can be controlled without the need for such troublesome calculations. It is possible to perform fine-grained control while keeping this in mind.

By the way, if, for example, the accelerator pedal is depressed while such fine-grained regeneration processing is being performed, the combustion conditions may be changed so much that feedback control may not be able to keep up.

[0020] In general, in a diesel engine, for example, when the driver changes the amount of operation of the accelerator pedal, a new operating condition is set, but along with this, the fuel supply to the diesel engine changes. The injection amount changes, and the thermal energy contained in the exhaust gas also changes. Therefore, if the accelerator is operated while the regeneration process is being performed to maintain the exhaust gas temperature within the range of the target regeneration temperature, the thermal energy will change rapidly and feedback control will not be able to catch up.

Therefore, the particulate filter regeneration device for a diesel engine according to claim 1 further includes an operating condition detecting means for detecting the operating condition of the diesel engine, and an operating condition detected by the operating condition detecting means. 2. The exhaust temperature feedforward control means for performing feedforward control that adjusts the feedback control conditions or the control amount of the combustion conditions of the diesel engine based on the estimated exhaust heat. He also invented a particulate filter regeneration device for diesel engines as described in .

Specifically, if the accelerator is suddenly depressed while the regeneration process is being performed, the exhaust temperature will rise rapidly due to the increase in the amount of fuel injected, so the regeneration process will be delayed accordingly. It is necessary to take measures such as rapidly restoring the intake throttle amount or rapidly returning the injection timing to its normal state. Therefore, the exhaust temperature feedforward control means calculates combustion conditions such as intake throttling amount and fuel injection timing according to the exhaust heat estimated from the operating conditions and performs feedforward control, which solves the problem of responsiveness of feedback control. I will solve it. That is, when the estimated exhaust heat is large, the exhaust gas temperature feedforward control means performs feedforward control so as not to eliminate the intake throttle amount or retard the injection timing. Therefore, if the accelerator is depressed during regeneration processing, this feedforward control immediately returns the intake throttle and injection timing to normal operating conditions, making it possible to promptly prevent the exhaust temperature from rising too much. can.

[0023] The exhaust temperature feedforward control means also controls the target regeneration temperature, which is a feedback control condition, in accordance with the operating conditions, such as virtually lowering the target regeneration temperature when the operating condition is such that the exhaust gas temperature increases. The same objective can be achieved by making adjustments to the feedback condition of doing something. That is, if the accelerator is depressed during regeneration processing, the target regeneration temperature, which is the feedback condition, is virtually lowered to increase the difference between the detected value by the exhaust temperature detection means and the target value, thereby increasing the feedback control. This increases the speed and eliminates the response delay that occurs when only feedback control is used.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained in detail with reference to embodiments shown in the drawings. As shown in FIG. 1, the diesel engine 1 of the embodiment detects operating conditions such as engine speed and accelerator operation amount, calculates various control amounts in an arithmetic processing unit (ECU) 3, and distributes them to the intake system 5. The servo motor 9 of the installed throttle valve 7 is electrically driven and controlled to adjust the intake air amount, and the injection adjustment means 13 of the injection pump 11 is electrically driven and controlled to control the fuel injection amount and injection timing. This is a so-called electronically controlled type. Moreover, the diesel engine 1 is
The exhaust system 15 is of a type having a DPT equipped with a filter 17 for collecting particulates in the exhaust gas. The filter 17 has a honeycomb-shaped exhaust passage made of a ceramic material, and its wall surface has a large number of pores for collecting particulates in the exhaust while allowing gas components of the exhaust to pass through.

Operating conditions such as engine speed are determined by an electrode pickup type rotation sensor 19 that detects the rotation of a pulser engaged with the crankshaft of the diesel engine 1, and a potentiometer type rotation sensor 19 that detects the amount of operation of the accelerator pedal by the driver. It is detected by an operating condition detecting means constituted by an accelerator sensor 21, a thermistor type water temperature sensor 23 for detecting the cooling water temperature, etc., and is inputted to the ECU 3.

The injection pump 11 is based on a distribution type injection pump, as shown in FIG. The injection pump 11 can control the injection amount by causing the electromagnetic spill valve 25 to spill (overflow) the fuel in the high pressure chamber of the injection pump 11 to the low pressure side except for the required injection amount. Further, the injection timing can be controlled by controlling the hydraulic pressure in the timer chamber of the hydraulic timer and the drive duty ratio of the timer control valve (TCV) 27. These electromagnetic spill valve 25 and TCV 27 correspond to the above-mentioned injection adjustment means 13.

The ECU 3 uses the engine operating parameters detected by the rotation sensor 19 and the like as input signals to calculate the normal state calculation values of the fuel injection amount and injection timing, that is, the normal target injection amount and the normal target injection timing. . Then, using this calculated value as a target value, these electromagnetic spill valves 25 and TC
By electrically driving V27, the injection pump 11 is caused to perform fuel injection. Note that such arithmetic control is well known in electronically controlled injection pumps, and further detailed explanation will be omitted.

Further, near the outlet of the filter 17, which is one of the hardware features of this embodiment, there is an exhaust temperature sensor consisting of a heat-sensitive element, such as a thermocouple, that generates a constant electromotive force depending on the temperature. 29 is arranged to detect the temperature of the exhaust gas that has passed through the filter 17. In addition,
The exhaust temperature can also be detected by a configuration that detects the temperature inside the main body of the filter 17 or a configuration that detects the temperature on the inlet side of the filter 17, and these hardware configurations may be used.

As shown in FIG. 3, the ECU 3 includes, in addition to a central information processing unit (CPU), a read-only memory (ROM), a write-only memory (RAM), a counter for pulse counting, and a timer for time setting. A so-called microcomputer (MPU) 31 with a built-in microcomputer (MPU) 31, an analog-to-digital converter (ADC) 32 for converting an analog signal into a digital signal and inputting it to the MPU 31, and a pulse waveform shaping circuit that shapes the waveform signal into a pulse waveform. (IB) 33, and output buffers (OB1, OB2, OB3) 35, 36, and 37 for outputting control signals to the servo motor 9, electromagnetic spill valve 25, and TCV 27.

An example of the MPU 31 is a one-chip microcomputer "6801 model" manufactured by Motorola, USA.
is available. The input end of the waveform shaping circuit 33 is connected to the rotation sensor 19, and a rotation pulse signal proportional to the engine rotation speed is obtained. This rotation pulse signal is
1 input capture port, and the period of the rotation pulse is measured based on this input. This measurement result is temporarily stored in the built-in RAM. Furthermore, analog signals detected by the accelerator sensor 21, water temperature sensor 23, and exhaust temperature sensor 29 are converted into digital signals via the ADC 32, input to the MPU 31, and stored in the RAM as operating condition data.

Next, the operation of the ECU 3 including the MPU 31 will be explained with reference to the flowchart shown in FIG. Calculation starts with "Start (S1)". Specifically, MPU3
1 starts arithmetic processing according to a program stored in the built-in ROM, and initializes the built-in RAM, timer, counter, etc.

Next, the process advances to "operating condition signal input, operating time integration (S2)", where signals from various sensors 19, 21, 23, etc. are received, operating conditions are input, and data is stored in the built-in RAM.

Specifically, the period of rotation pulses generated by the rotation sensor 19 is counted by the clock signal of the MPU 31, and period data inversely proportional to the rotation speed is detected as the rotation speed of the diesel engine 1. Further, the amount of accelerator operation by the driver is detected by an accelerator sensor 21 that generates an analog voltage signal according to the amount of operation of the accelerator pedal. Furthermore, the cooling water temperature of the diesel engine 1 is detected by the water temperature sensor 2.
3, it is detected as an analog voltage signal. These analog signals are converted into digital signals by the ADC 32 and stored in the RAM as accelerator data and water temperature data. In this way, the operating condition signal is input. Furthermore, signals are also input from various correction sensors, switches, etc. for correcting these detected operating conditions, but the details are omitted as they are off topic.

On the other hand, the operation time is started to be integrated by the counter function of the MPU 31. Next, the process proceeds to "injection amount and injection timing calculation (S3)". In this step, MPU3
1 uses the operating condition data input to the RAM as a variable, and calculates command values for the injection amount and injection timing during normal operation of the diesel engine 1 according to the control algorithm defined in the program, and performs "injection amount control (S4)". Proceed to.

[0035] In step S4, the MPU 31
Generates an electrical drive output to drive the electromagnetic spill valve 25 of the injection pump 11 based on the injection amount command value calculated in
Controls the injection amount according to the command value.

Next, proceed to "Reproduction time determination (S5)",
The MPU 31 determines whether the DPT filter 17 has reached the regeneration time. As this determination condition, for example, a determination method may be adopted in which the engine operating time is accumulated and the regeneration time is reached when the accumulated value reaches a certain limit. In this embodiment, the regeneration timing is determined based on the engine operating time accumulated in the process of S2. However, in this case, it goes without saying that countermeasures such as power supply backup are required because the data on the cumulative operating time does not disappear in the built-in RAM even when the key switch is turned off. Note that this can be handled using known techniques, so a detailed explanation will not be provided.

If it is determined in step S5 that the regeneration timing has not yet been reached, "injection timing control (S6
)”. In this "injection timing control (S6)",
The MPU 31 generates an injection timing adjustment drive output to drive the TCV 27 of the injection pump 11 in accordance with the normal injection timing command value T, controls the injection timing, and again performs the "operating condition signal input, operating time integration" in S2. Return to step.

On the other hand, as a result of the regeneration time determination in step S5, if it is determined that the regeneration time has been reached, the filter 17
The process moves to "exhaust temperature signal input (S7)" for regeneration. In "exhaust temperature signal input (S7)", the MPU 31 inputs exhaust temperature data from the exhaust temperature sensor 29. Through this step S7, the regeneration temperature D is detected during the execution of the regeneration process.

Next, the process proceeds to "target regeneration temperature calculation (S8)". In this step, the MPU 31 calculates a target value Do of regeneration temperature suitable for regenerating the filter 17 according to the operating conditions. For example, the target regeneration temperature Do can be calculated by searching a two-dimensional map of the engine speed N and the accelerator operation amount α, and performing a correction calculation. Such two-dimensional maps are stored in advance in the ROM. Note that the target regeneration temperature Do here is not the ignition temperature or combustion temperature for actually igniting and burning particulates in the filter 17, but is used for adjusting the feedback conditions in the exhaust temperature feedforward control means of the present invention. is the hypothetical target regeneration temperature. In the two-dimensional map referred to in this process, if the exhaust heat becomes large based on the operating conditions, the target regeneration temperature Do is set to a low value,
In the opposite case, a correction calculation can be performed to set the value to a high value, for example, in accordance with the amount of change in the accelerator opening degree or the number of rotations per unit time.

Next, the process proceeds to "regeneration temperature error calculation (S9)", and the target regeneration temperature Do of the detected actual regeneration temperature D is calculated.
Calculate the error ΔD=D−Do. Next, the process proceeds to "throttle valve opening calculation control (S10)", and the MPU 31 controls the opening of the throttle valve 7 according to the regeneration temperature error ΔD with respect to the operating conditions. As an example of this calculation, the drive pulse duty of the linear solenoid, which is the drive actuator of the throttle valve 7, is calculated by interpolating a two-dimensional map using the engine speed N as the operating condition and the regeneration temperature error ΔD as two arguments. Here are some methods to control the calculation. Note that a two-dimensional map for calculation processing in this step is also stored in advance in the ROM.

Next, the process proceeds to "injection timing retard calculation (S11)". In this step, the operating conditions and regeneration temperature error ΔD
Accordingly, a retard amount TR for retarding the injection timing from the normal injection timing T is calculated. Specifically, for example, R
TR by referring to a two-dimensional map using the rotation speed N and reproduction temperature error ΔD stored in advance in the OM as arguments.
is calculated.

In the subsequent step of "injection timing retard control (S12)", the injection timing command value T'=T-TR, which is retarded by the retard amount TR with respect to the normal injection timing T, is used as the injection timing command value to control the injection pump 11. The TCV 27 is driven. As a result, the injection timing is retarded and the exhaust temperature is increased.
Particulates adhering to the filter 17 are ignited and burned, and filter regeneration processing is started.

This filter regeneration process is then continued until the MPU 31 determines that the regeneration has ended (Y) in the step ``Regeneration End Determination (S13)''. This reproduction end determination is performed by determining whether the execution time t of the reproduction process has continued for a certain period of time to (Y) or not (N).

If t<to, the determination is "N" and the process moves to step S2, where the processing from step S2 onwards is executed again. When t≧to, it is determined that the regeneration process has ended, and the “Y” loop is followed to clear the “operating time clear (S)”.
14)”. In this step S14, the MPU
31, after clearing the counter for accumulating the driving time, the process moves to step S2.

The above processing operations can be summarized as follows. When the operating time of the diesel engine 1 is short and the time to regenerate the filter 17 has not yet been reached, the ECU
Since the regeneration timing determination in step 3 is determined to have not been achieved, the process branches to the N side, fuel injection is controlled with the normal injection amount and injection timing, the throttle valve 7 is not throttled, and no regeneration processing is performed (S
5→S6).

On the other hand, when the diesel engine 1 is operated for a certain length of time and the time when the filter 17 should be regenerated is reached, the regeneration time is determined to have been reached and the process branches to the Y side.
Reproduction processing is performed (S5→S7).

That is, the ECU 3 calculates the regeneration temperature error ΔD from the regeneration temperature D detected by the exhaust temperature sensor 29 and the target regeneration temperature Do calculated from the operating conditions, and also adjusts the throttle valve according to the regeneration error temperature ΔD. 7 drive servo motor 9 generates a drive output to throttle the intake air, TCV27
This generates a drive output to retard the injection timing, thereby raising the exhaust temperature, and igniting and burning particulates adhering to the filter 17 with the exhaust heat (S7 to S
12). This regeneration process continues for a certain period of time to, which is sufficient to regenerate the filter 17 (S13→S2), and the regeneration temperature D during this period is controlled to the target regeneration temperature Do, so that the filter 17 accurately completes regeneration. be able to.

Thereafter, the injection amount and injection timing are controlled normally until the filter 17 reaches the next regeneration time. That is, until the next regeneration time, control is not performed to throttle the intake air or retard the injection timing in order to raise the exhaust gas temperature to the target regeneration temperature (S2 to S5→S6→S2).

As explained above, according to this embodiment, the filter is regenerated by adjusting the exhaust gas temperature of the diesel engine 1, so there is no need for any new addition of hardware, which is economical and efficient. Regeneration processing can be realized.

Furthermore, since the exhaust gas temperature in the vicinity of the filter 17 is detected and feedback control is performed, the exhaust gas temperature during the regeneration process does not rise too much and damage the filter 17 etc. due to heat.

Furthermore, the combustion conditions can be controlled by feedback control taking into account the stability of ignition and the rise in exhaust gas temperature near the filter 17 during the combustion period, and the adjustment of the combustion conditions can be kept to the necessary minimum. be able to.

By the way, when the driver changes the amount of operation of the accelerator pedal, a new operating condition is set, the amount of fuel injected into the diesel engine 1 changes, and the thermal energy contained in the exhaust gas also changes. Therefore, the exhaust gas temperature that acts on the filter during regeneration also changes.

[0053] In the embodiment, feedforward control is also performed to change the target regeneration temperature Do, so changes in operating conditions during the regeneration process can be quickly responded to, and response delays that would otherwise occur when only feedback control is used are eliminated. be able to.

Although one embodiment of the present invention has been described above, the present invention is not limited thereto, and various embodiments can be adopted without departing from the gist thereof. For example, when adjusting the exhaust temperature, the order in which the intake throttling amount and injection timing retardation amount are adjusted is such that if the regeneration temperature has not reached the target value even after the intake throttling amount reaches a certain limit, the intake air When you throttle down, black smoke in the exhaust increases rapidly. Therefore, in such a case,
It is appropriate to keep the intake throttle amount within a certain limit and shift to retard control of the injection timing.

Even so, if the amount of retardation of the injection timing exceeds a certain limit, combustion in the engine will still deteriorate. In such a case, the amount of retardation should be kept within a certain limit even if the exhaust gas temperature has not reached the target value.

[0056] Under operating conditions where the retardation amount is kept within a certain limit as described above, it may become impossible to raise the exhaust gas temperature to the temperature required for regeneration processing. Therefore, under such conditions, if the playback end determination is made in the same manner as in the above embodiment, it will be determined that the playback has ended because the certain period of time to has elapsed, even though the playback process has not actually been completed. Put it away.

[0057] Therefore, when determining the end of playback, the fixed time t
It is preferable to use a modified example in which o is not simply a time, but is set as a condition related to the time during which the exhaust gas temperature exceeds the temperature required for the regeneration process.

Furthermore, in the embodiment, an example is shown in which the cumulative operating time is used as a method for determining the filter regeneration time, but in addition to this, any parameter related to the amount of particulates deposited on the filter may be used. is possible. For example, it is possible to determine that the regeneration time has come when the cumulative engine speed reaches a certain value.

Furthermore, in determining the regeneration timing, the detection result of the water temperature sensor 23 may also be added, and the regeneration process may be started after the warm-up of the diesel engine 1 is detected. In addition, as mentioned in the prior art section, the need for filter regeneration is due to an increase in back pressure due to filter clogging, so this back pressure is measured, and if the back pressure exceeds a predetermined value, regeneration is performed. A direct determination method for determining the timing may be used.

On the other hand, in this embodiment, reliable and stable regeneration can be achieved by using both feedforward control that calculates the target regeneration temperature from the operating conditions and feedback control that detects the regeneration temperature using the exhaust temperature sensor 29. However, feedback control alone is sufficient to achieve the object of the present invention.

[0061] Furthermore, for feedback of the regeneration temperature, the exhaust temperature sensor 29 may be disposed inside the filter 17 to detect the regeneration temperature from the filter internal temperature.

In addition, in feedforward, instead of calculating the target regeneration temperature Do, if the accelerator is depressed during execution of regeneration processing, the exhaust temperature will rise due to an increase in the fuel injection amount. Therefore, a structure may be adopted in which the control amount is directly adjusted, such as by restoring the intake throttle amount for regeneration processing or returning the injection timing to a normal state.

Furthermore, during regeneration, if the thermal energy contained in the exhaust gas of the diesel engine 1 is excessive and there is a risk that the filter 17 may burn out or other problems, the diesel engine 1
A bypass valve may be provided so that part or all of the exhaust gas does not flow into the filter 17, and this bypass valve may be driven by a separate actuator in the ECU 3.

In addition, when regenerating at idling speed, an idle-up function is added to increase the idling speed to increase exhaust energy, and once the regeneration process begins, the key switch is turned off and operation is stopped. The ECU 3 may be configured to have an automatic regeneration operation function that continues idling operation for a certain period of time until regeneration is completed even if the engine is stopped.

[0065] In addition, during regeneration during idling, during the initial fixed period t1, the engine is operated at an idle speed N1 for ignition, which is higher than the normal idle speed N0, in order to improve the ignitability of the filter volume. In addition to raising the exhaust temperature, after ignition, the idle speed for regeneration is lowered to N2 (N0<N2<N1) to save fuel amount due to idling operation, and to supply oxygen for filter regeneration. It is also possible to employ special rotation control for filter regeneration, which restores the normal idle rotation speed N0 after the regeneration is completed. This special rotation control for filter regeneration makes it possible to achieve reliable ignition even during idling operation, and to enable energy-saving regeneration after ignition.

[0066]

[Effects of the Invention] As described above, according to the present invention, when regenerating the filter of the DPT system, the thermal energy of the exhaust gas is used and feedback control of the exhaust temperature is performed, so that the system does not become complicated. Moreover, damage to the filter due to overheating can be prevented, and efficient filter regeneration processing can be performed through stable ignition combustion.

Furthermore, the particulate filter regeneration device for a diesel engine according to claim 2 also performs feedforward control depending on operating conditions, so the responsiveness to changes in operating conditions is improved compared to a case where only feedback control is used. Good.

As described above, according to the present invention, there is no need to provide a special configuration as a heat source for regeneration processing, and a regeneration device that is simple in configuration, matches energy saving, and is highly stable can be realized. Its practical effectiveness is extremely high.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a system of an embodiment.

FIG. 2 is a sectional view showing the configuration of an electronically controlled injection pump.

FIG. 3 is a block diagram showing the configuration of arithmetic processing means of the embodiment.

FIG. 4 is a flowchart of a combustion control processing routine including filter regeneration processing in the embodiment.

[Explanation of symbols]

1... Diesel engine, 3... Arithmetic processing means (EC
U), 7... Throttle valve, 9... Servo motor,
11... Injection pump, 17... Filter, 19...
・Rotation sensor, 21... Accelerator sensor, 23...
Water temperature sensor, 25... Electromagnetic spill valve, 27... Timer control valve (TCV), 29... Exhaust temperature sensor.

Claims (4)

[Claims] 1. A particulate filter for a diesel engine that collects particulates in the exhaust gas of a diesel engine with a filter and regenerates the filter by burning the particulates collected in the filter at a predetermined time. In the regeneration device, a regeneration time instructing means for directly or indirectly detecting the particulate collection state of the filter and instructing the timing of regeneration processing, an exhaust temperature detecting means for detecting an exhaust temperature near the filter; When the regeneration timing is instructed by the regeneration timing instructing means, the exhaust gas temperature near the filter is determined from the exhaust temperature detected by the exhaust temperature detection means and the target regeneration temperature necessary for combustion of the particulates. 1. A particulate filter regeneration device for a diesel engine, comprising exhaust temperature feedback control means for feedback controlling combustion conditions of the diesel engine so as to maintain the regeneration temperature within a range of regeneration temperature. 2. The particulate filter regeneration device for a diesel engine according to claim 1, further comprising an operating condition detecting means for detecting an operating condition of the diesel engine, and an operating condition estimated from the operating condition detected by the operating condition detecting means. and exhaust temperature feedforward control means for performing feedforward control that adjusts the feedback control conditions or the control amount of the combustion conditions of the diesel engine based on the exhaust heat generated. Curate filter regeneration device. 3. The exhaust temperature adjusting means performs the feedback control by electrically adjusting the throttle amount of an intake throttle valve disposed in the intake system of the diesel engine. The particulate filter regeneration device for a diesel engine according to any one of Item 2. 4. The exhaust temperature adjusting means performs the feedback control by adjusting the injection timing of an injection pump that injects fuel into the diesel engine to an electrical output. A particulate filter regeneration device for a diesel engine according to any one of the above.