JPS60243357A - Engine exhaust recirculation amount control device - Google Patents

Abstract

PURPOSE:To keep the rate of exhaust-gas recirculation always at a proper value, by preventing excessive recirculation of exhaust gas by detecting the degree of clogging in the exhaust system of an engine by the intake pressure, and correcting a control value for the opening of an EGR (exhaust-gas recirculation) valve according to the detected intake pressure. CONSTITUTION:In a control apparatus, in which work chambers of a differential- pressure type actuator for controlling an EGR valve disposed in an EGR passage are communicated respectively with a negative-pressure source and the atmospheric pressure via two solenoid valves having solenoids 11a, 12a, a section 27 for effecting clogging correction is provided in an ECU14 which controls the solenoids 11a, 12a. The section 27 is so designed to produce an aimed value L'o obtained by correcting (at 20) a base aimed value Lo of the lift of the EGR valve determined by a setter 19 on the basis of the engine speed Ne and the accelerator opening theta according to the temperature Tn of cooling water as an aimed value L''o that is subjected to correction for clogging on the data Ne, theta and the supercharging pressure detected by a supercharging-pressure sensor 26. The solenoids 11a, 12a are controlled on the basis of the above aimed value L''o.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a device for recirculating exhaust gas from an internal combustion engine to an intake passage through an exhaust gas recirculation passage, and in particular, to a device for controlling the amount of exhaust gas recirculation. Regarding the device.

[Conventional technology]

As a conventional engine exhaust recirculation amount control device, there is one as shown in Fig. 7.
The air passage 2 is provided with a filter 4 such as a catalytic converter or a diesel particulate filter on the downstream side of the turbine 3a of the turbocharger 3, and this filter 4 collects diesel particulates discharged from the diesel engine 1. Collect curates (see Figure 3)
.

Overpressurized intake air is supplied from the fuel tank 31 of the turbocharger 3 through the intake passage 5 to the combustion chamber 1a of the diesel engine 1, and the turbine 3
An exhaust gas recirculation passage 6 is provided which communicates the exhaust passage 2 on the second side of the compressor 3b with the intake passage 5 on the downstream side of the compressor 3b.

This exhaust gas recirculation passage 6 is provided with an exhaust gas adjustment valve 7, and this exhaust gas adjustment valve 7 is controlled by its lift amount ( (opening degree) is controlled.

That is, the exhaust gas regulating valve 7 is retracted and controlled by the rod 8C connected to the diaphragm 8a of the differential pressure responsive actuator 8.

The working chamber 81) of the differential pressure responsive actuator 8 includes a vacuum pump 9, an air filter 10, and a solenoid valve 11. ．． The diaphragm 8a is connected to the diaphragm 8a through a passage 12, and is configured to receive a reduced and regulated control pressure through a passage 13, thereby tensioning the diaphragm 8a.

Furthermore, each solenoid 11a, 12 of the solenoid valve 11.12
Electronic control unit (ECU) 1.4 that supplies control signals to a
The ECU 4 includes an engine rotation speed sensor 15° for detecting the rotation speed Ne of the diesel engine 1 and an accelerator opening sensor 1 for detecting the accelerator opening θ.
6° EG composed of a cooling water temperature sensor 17 that detects the cooling water temperature TI+ of the diesel engine 1, a position sensor that detects the position (lift amount) La of the EGR valve 7, etc.
Each detection signal from the R valve position sensor 18 is received.

Then, the basic target value setter 15 of the EC 1114 sets the basic target value of the lift amount of the EGR valve 7 according to the engine speed Ne and the accelerator opening degree θ. Output.

Next, the water temperature correction calculator 20 of the ECU 14 outputs a target value of the lift amount of the EGR valve 14 corrected by the cooling water temperature according to the basic target value and the cooling water temperature TI+.

Then, in the adder/subtractor 21, this target value, ,' and E
By adding the offset value Loff from the R valve off-cent value setter 22, the target value Li of the EGR valve 14 amount converted to the position detected by the EGR valve position sensor 18 is output. .

Then, in the adder/subtractor 23, since the target value of the amount of
The measured value La detected by the EaR valve position sensor 18 is subtracted, the difference Le(-1-i-La) is output, and the signal of this difference)-e is sent through the sole fluid drive circuit 24. Tension/id 11a, 1.2 of each solenoid valve 11.12
The reference numeral 25 in FIG. 7 indicates a battery because the amount of fuel supplied to the EGR valve 7 is controlled.

[Problem that the invention seeks to solve]

However, in such a conventional engine exhaust recirculation amount control device, the target value Li of the EGR valve is determined by the following formula, so if a blockage occurs in the exhaust system, the exhaust pressure will decrease. There is a problem in that the amount of EGR increases and the amount of EGR becomes excessive.

EGR target value Li - basic target value.

x Water temperature correction coefficient Th' + Offset value Loff In other words, the EGR amount is determined by the pressure difference between the pressure in the exhaust passage 2 and the pressure in the intake passage 5 and the EGR valve position.
When the pressure in the exhaust passage 2 increases, the pressure difference increases and the EGR amount increases.

As described above, when the amount of EGR becomes excessive, a decrease in output and a deterioration in fuel efficiency occur, and this effect is particularly large in diesel engines.

Also, in order to solve the above-mentioned problem, it may be possible to correct the EGR amount by sensing the exhaust pressure, but if the EGR amount is directly corrected using the exhaust pressure, this correction of the EGR amount will cause the exhaust pressure to be corrected. The pressure will rise, and the EGR amount will be further corrected.

Furthermore, when the EGR amount is corrected using exhaust pressure detection, there is a problem that the EGR control amount becomes a positive feedback and becomes unstable.

Furthermore, there is a problem that the sensor for detecting the exhaust pressure deteriorates in function due to corrosive gas and becomes clogged with soot, which is difficult in practical use.

The present invention aims to solve these problems and provides an engine that detects the clogging state of the exhaust system using intake pressure and corrects the opening control amount of the EGR valve according to this pressure. The purpose of the present invention is to provide an exhaust gas recirculation amount control device.

[Means for solving problems]

Therefore, the exhaust gas recirculation amount control device for an engine according to the present invention is installed in the exhaust gas recirculation passage that communicates the exhaust passage and the intake passage of the engine, and in the exhaust gas recirculation passage to adjust the amount of exhaust gas recirculation. Equipped with an exhaust gas adjustment valve and an exhaust gas adjustment valve control mechanism that controls the opening degree of the exhaust gas adjustment valve,
The intake passage is provided with a pressure sensor that detects a clogging state of the exhaust passage or the intake passage, and the exhaust gas adjustment valve control mechanism receives a pressure signal from the pressure sensor to control the exhaust gas adjustment valve. The present invention is characterized by being provided with a clogging correction calculation section for correcting the opening degree control amount.

[Effect]

With the above configuration, the clogging correction calculating section of the exhaust gas adjustment valve control mechanism receives the boost pressure signal from the boost pressure sensor, calculates the clogging correction coefficient corresponding to the clogging state, and uses this clogging correction coefficient to adjust the exhaust gas. Correct the opening control amount of the regulating valve.

〔Example〕

Hereinafter, embodiments of the present invention will be explained with reference to the drawings.
1 to 6 show a diesel engine equipped with an engine exhaust recirculation amount control device as an embodiment of the present invention, and FIGS. 1 and 2 are block diagrams of this device, and
The figure shows the overall configuration, and FIGS. 4, 5 (,) to (e), and 6 (a) to (e) are graphs for explaining the operation.

As shown in FIGS. 1 to 3, in this embodiment as well, a filter 4 such as a catalytic converter or a diesel particulate filter is provided in the exhaust passage 2 of the diesel engine 1 on the downstream side of the turbine 3a of the turbocharger 3. This filter 4 collects diesel particulates discharged from the diesel engine 1.

Overpressurized intake air is supplied from the hump sensor 3b of the turbocharger 3 to the combustion chamber 1a of the diesel engine 1 through the intake passage 5, and the turbine 3a
An exhaust gas recirculation passage 6 is provided that communicates the exhaust passage 2 on the more upstream side with the intake passage 5 on the downstream side of the fan plater 31).

This exhaust gas recirculation passage 6 is provided with a bleed force adjustment valve 7, and this exhaust gas adjustment valve 7 is operated by a differential pressure responsive actuator 8 that constitutes an exhaust gas adjustment valve control mechanism GO.
The lift amount (opening degree) is controlled by.

That is, the exhaust gas regulating valve 7 is retracted and controlled by a rod 8c connected to a diaphragm 8a of a differential pressure responsive actuator 8.

The working chamber 8b of the differential pressure responsive actuator 8 is connected to a vacuum pump 9 and an air filter 10, which constitute the exhaust gas regulating valve control mechanism GC, via electromagnetic valves 11 and 12, and the pressure is regulated through a passage 13. The diaphragm 8a is configured to receive a controlled pressure, thereby tensioning the diaphragm 8a.

Furthermore, each strain/id lla, 12 of the solenoid valve 11.12
An electronic control device that supplies control signals to a? 1i (EC1J)
The EcU 14 includes an engine rotation speed sensor 15° for detecting the rotation speed Ne of the diesel engine 1, an accelerator opening sensor 16° for detecting the accelerator opening θ, and a cooling water temperature TI+ of the diesel engine 1. Cooling water temperature sensor 1'? + E GR valve 7 position (
EGR valve position sensor 18, which is composed of a position sensor etc. that detects the lift amount) La, and the pressure P of the intake passage 5
Each detection signal from a supercharging pressure sensor 26 that detects a is received.

Then, the basic target value setter 19 of the ECU 14 outputs the basic target value of the lift amount of the EGR valve 7 according to the engine speed Ne and the accelerator opening θ.

Next, the water temperature correction calculator 20 of the ECU 4 calculates the basic target value. The target value of the lift amount of the EGR valve 14 is corrected by the cooling water temperature according to the cooling water temperature Th. ′ is output.

In the clogging correction calculation section 27, this target value is calculated. ', the engine speed Ne from the engine speed sensor 15, the accelerator opening θ from the accelerator opening sensor 16, and the boost pressure 26 from the boost pressure sensor 26. , ” is output.

That is, in the clogging correction calculating section 27, the standard supercharging pressure setting device 28 determines the standard supercharging pressure P when the exhaust system is not clogged, based on the engine rotation speed Ne and the accelerator opening degree θ. Output.

Then, the adder/subtractor 29 calculates the standard boost pressure P. and the supercharging pressure Pa from the supercharging pressure sensor 26 ε (=P, -Pa)
I put it on.

Further, a correction slope setting device 30 is provided, and a deviation ε- at each operating point determined by the engine speed Ne and the accelerator opening θ is calculated from the engine speed Ne and the accelerator opening θ.
The slope a of the correction coefficient KIT characteristic is output.

This gradient α is determined in advance by experiment.

Then, the correction coefficient calculator 31 outputs +] (=1-ε·α) as a clogging correction coefficient from the deviation (differential pressure) ε and the gradient a (see FIG. 4).

The clogging correction calculator 32 uses this clogging correction coefficient Kp and the target value from the water temperature correction calculator 20. ′ and the target value corrected for clogging. ” is output.

Then, the adder/subtractor 21 calculates the target value. ” and EGR
Offset value Loff from valve offset value setter 22
By adding the above, a target value Li of the EGR valve 14 7F amount converted to the position detected by the EGR valve position sensor 18 is output.

Then, the adder/subtractor 23 subtracts the target value Li of the lift amount detected by the EGR valve position sensor 18 and the measured value 1-a of the amount of 7 points, and outputs the difference Le (=Li-La). The signal of this difference Le is supplied to the valve/id 11, 12a of each electromagnetic valve 11, 12 through the solenoid drive circuit 24, and the lift amount of the EGR valve 7 is controlled.

In addition, the code|symbol 8d in a figure shows a return spring, 11b and 12b are valve bodies, and 25 is a pantry, respectively.

Since the exhaust gas recirculation amount control device for an engine as an embodiment of the present invention is configured as described above, when a blockage occurs in the exhaust system, the EGR amount is adjusted to the desired control amount.
Control is performed in the direction of closing the EGR valve 7.

In the diesel engine 1 with the turbocharger 3, if the exhaust passage 2 becomes clogged, the turbine efficiency decreases.
This has a causal relationship in that the supercharging pressure in the intake passage 5 decreases, and in this embodiment, this fact is mainly utilized to perform correction control for <EGR amount based on the supercharging pressure.

That is, the clogging correction calculation unit 27 compares the reference supercharging pressure Po when no clogging occurs and the measured actual supercharging pressure Pa, and calculates the differential pressure ε (=F'6-Pa) and the engine speed Ne.
- Determine the clogging correction coefficient (1-ε・α) from the correction gradient α determined according to the accelerator opening degree θ, and calculate the EGR valve 7 based on the following formula.
A target value Li is determined.

EGR target value Li - basic target value ■ - 6 × water temperature correction coefficient Th'X clogging correction coefficient (1 - ε・α) +
Offset value Loff In this way, as can be seen from the characteristics of the present embodiment shown by solid lines and white circles in FIG. 5(,) to (e), and the characteristics of the conventional example shown by broken lines and black circles, the NOx in the exhaust gas remains almost constant in response to fluctuations in the downstream exhaust pressure, so even if the exhaust system is clogged, fuel efficiency will not deteriorate.

The loading amount of particulates and the amount of CO and HC also do not fluctuate more than in the conventional case, as shown in FIGS. 5(b), (d), and (e), respectively.

Furthermore, as can be seen from the characteristics of this embodiment shown by broken lines and black circles in FIG. 6(,) to (e), and the characteristics of the conventional example shown by solid lines and white circles, it is possible to reduce the influence of variations in the amount of EGR. I can do it.

According to the engine exhaust gas recirculation amount control device as an embodiment of the present invention, the correction ability for making the EGR amount constant is exhibited even with respect to the response delay of the turbocharger 3.

Furthermore, similar effects can be obtained against clogging of the air conditioner element or the like disposed on the upstream side of the intake passage 5.

〔Effect of the invention〕

As described in detail above, according to the Ennon exhaust gas recirculation amount control device of the present invention, there is an exhaust gas recirculation passage that communicates the exhaust passage and the intake passage of the engine, and an air-loss gas An exhaust gas regulating valve that can adjust the recirculation amount;
The exhaust gas regulating valve control mechanism is provided to control the opening degree of the exhaust gas regulating valve, and the intake passage is provided with a pressure sensor for detecting a clogging state of the exhaust passage or the intake passage. A simple configuration in which the regulating valve control mechanism is provided with a clogging correction calculating section for correcting the opening control amount of the exhaust gas regulating valve in response to the pressure signal from the pressure sensor has the following effects and advantages. can be obtained.

(1) By detecting the supercharging pressure and performing control based on this, the lift control amount of the EGR valve is controlled by negative feedback feedback, so that stable control can be performed.

(2) Even if the exhaust system becomes clogged, an excessive amount of EGR is prevented and the amount of EGR is maintained at an appropriate amount.

(3) Item 2 above prevents a decrease in output and deterioration of fuel efficiency.

[Brief explanation of the drawing]

1 to 6 show a diesel engine equipped with an engine exhaust recirculation amount control device as an embodiment of the present invention, and FIGS. 1 and 2 are block diagrams of this device, and
The figure is a diagram of its overall configuration, Figures 4, 5 (a) to (e), and 6 (a) to (e) are graphs for explaining its effects, and Figure 7 is a graph for explaining its operation. FIG. 2 is a block diagram of a conventional engine exhaust gas recirculation amount control device. 1...Diesel engine, 1a...Combustion chamber, 2...Exhaust passage, 3...Turbocharger, 3a...Turbine,
31]...Compressor, 4...Filter, 5...Intake passage, 6...Exhaust gas recirculation passage, 7...Exhaust gas regulation valve (EGR valve), 8...Configuring exhaust gas regulation valve control mechanism Differential pressure responsive actuator, 8a...Guia 7ram,
8b... Working chamber, 8c... Rod, 8d... Return spring,
9...Vacuum pump, 10...Air filter, 11
．． 12...Solenoid valve, 14a, 12a...Solenoid, l
lb, 121)... Valve body, 13... Passage, 14... Electronic control unit (ECU), 15... Engine speed sensor,
16...Accelerator opening sensor, 17...Cooling water temperature sensor, 18...EGR valve position sensor, 19...Basic target value setter, 20...Water temperature correction calculator, 21...Adder/subtractor, 2
2. EGR valve offset value setter, 23. Adder/subtractor, 24. Solenoid drive circuit, 25. Battery, 2
6... Boost pressure sensor (pressure sensor), 27... Clogging correction calculation section, 28... Reference boost pressure setting device, 29... Addition/subtraction device, 30... Correction gradient setting device, 31... Correction coefficient calculation vessel,
32...Clogging correction calculator, GC...Exhaust gas adjustment valve control mechanism. Figure 3 Figure 4 Deviation ε

Claims (1)

[Claims] An exhaust gas recirculation passage that communicates the exhaust passage and intake passage of the engine, an exhaust gas regulation valve that is installed in the exhaust gas recirculation passage and can adjust the amount of exhaust gas recirculation, and an exhaust gas regulation valve that can adjust the opening degree of the exhaust gas regulation valve. Equipped with an exhaust gas adjustment valve control mechanism to control
The intake passage is provided with a pressure sensor that detects a clogging state of the exhaust passage or the intake passage, and the exhaust gas regulation valve control mechanism receives a pressure signal from the pressure sensor to open the exhaust gas regulation valve. characterized by being provided with a clogging correction calculation unit for correcting the degree control amount;
Engine exhaust recirculation flow control device.