JPH0110421Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an engine control device.

[Prior art]

Generally, automobile engines contain
Various control devices are provided for the purpose of reducing NOx components, improving fuel efficiency, etc. One example is an exhaust gas recirculation (EGR) system, which redirects some of the exhaust gases back into the engine's intake system.
Lowers the combustion temperature of the engine and reduces the
This aims to reduce NOx components. By the way, in this EGR device, if unburned components or dust in the exhaust gas adheres to the EGR valve, the EGR
The valve may remain open (opening abnormality), and in such a case, there is a problem that the combustion temperature drops too much, resulting in a decrease in engine output and a misfire.

From the perspective of solving the above-mentioned problems, the applicant has already developed a device that detects abnormal opening of the EGR valve (Japanese Patent Application Laid-Open No. 1983-1999).
(See Publication No. 212358). However, failures in the EGR system include not only the EGR valve opening abnormality mentioned above.
The EGR passage is clogged, and the above equipment will cause problems.
Detection of clogging in the EGR passage cannot be addressed.

In addition, as other engine control devices, the above-mentioned
Some systems include an EGR device and a speed density type fuel supply device that performs feedback control of the amount of fuel supplied based on the output of an air-fuel ratio sensor. In the fuel supply system in this case, the basic control value of the fuel supply amount during EGR gas recirculation and non-recirculation is mapped according to the engine operating state, and one side of the map is mapped according to the EGR gas recirculation state. is selected, the basic control value in the map is corrected using the air-fuel ratio sensor output to obtain an actual control value, and the fuel supply amount is controlled accordingly.

The inventor of the present invention has considered in detail the control operation of the fuel supply device in the event of an EGR system failure in an engine control device equipped with the above-mentioned EGR device and fuel supply device, and has found that the control operation can be effectively controlled. It has been found that by using this method, it is possible to detect not only abnormal opening of the EGR valve but also clogging of the EGR passage. That is, when the EGR device operates,
The fuel supply system selects the map during EGR gas recirculation and adjusts the fuel amount corresponding to the basic control value in the map.
The actual fuel supply amount is feedback-controlled based on F ₀ (see section A in Figure 1). If the EGR passage becomes clogged in this state, EGR gas will not be recirculated to the engine intake system.Using the map for EGR gas recirculation above would normally result in a constant feedback control amount. Since a limit is set, the air-fuel ratio of the air-fuel mixture becomes over-lean (see section B in FIG. 1). Therefore, if we switch the basic control value map to the one when EGR gas is not recirculating when such a situation occurs, the engine intake system will have a
Since the EGR gas is not being recirculated due to clogging of the EGR passage, the fuel supply system will feedback control the fuel supply amount based on the fuel amount F1 corresponding to the basic control value in the map switched above. (See section C in Figure 1).

In other words, when the air-fuel ratio of the mixture becomes over-lean while the EGR device is operating, if the basic control value map is switched and feedback control is performed normally in that state, clogging will occur in the EGR passage. It can be detected that there is a Further, abnormality in the opening of the EGR valve, etc. can be detected in the same manner as described above.

[Purpose of invention]

In view of these points, this invention aims to provide an engine control device that can optimally control the amount of fuel supplied and can detect not only abnormal opening of the EGR valve but also clogging of the EGR passage.

[Structure of the idea]

Therefore, in this invention, as shown in the functional block diagram of FIG.
The basic control value of the fuel supply amount during EGR gas recirculation and non-recirculation is stored in 0, the operating state of the EGR device 18 is detected by the operating state detecting means 21, and the selecting means 22 is set according to the detected output. First,
One of the second storage means 19 and 20 is selected, and the fuel supply control means 23 selects the second storage means 19 and 20.
Alternatively, the basic control value corresponding to the output of the operating state sensor 24 in the fuel supply unit 20 is corrected with the output of the air-fuel ratio sensor 25 to obtain an actual control value, and the supply amount of the fuel supply means 26 is adjusted according to the actual control value. At this time, the failure detection means 27 receives the basic control value output and the actual control value output from the fuel supply control means 23, and when the magnitude of the difference between the two control value outputs is greater than or equal to the set value, the above selection is made. The means 22 selects the other storage means 20 or 19, and when the difference between the two control value outputs becomes less than a set value, it is determined that the EGR device 18 is malfunctioning. be.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 3 shows an engine control device according to an embodiment of the present invention. In the figure, 1 is an engine, 2 is an intake passage, and 3 is an exhaust passage.
A fuel injection valve 4 is installed near the engine 1, and on the upstream side of the intake passage 2 there is a throttle valve 5, and a negative pressure sensor 6 which is a speed density type air flow sensor that detects negative pressure downstream of the throttle. is installed. Further, an O ₂ sensor 7, which is an air-fuel ratio sensor, is attached to the exhaust passage 3 to detect whether the oxygen concentration in the exhaust gas is higher than a set value.

Then, a part of the exhaust gas is sent to engine 1.
Returns to the engine intake system as EGR valve gas
An EGR device 8 is provided. This EGR device 8
, one end of the EGR passage 9 is connected to the exhaust passage 3,
The other ends are respectively connected to the downstream side of the negative pressure sensor 6 of the intake passage 2, and an EGR valve 10 for opening and closing the EGR passage 9 is interposed in the middle of the EGR passage 9. This EGR
The valve 10 is composed of a valve body 10a and a diaphragm device 10b, and the diaphragm device 10b is provided with a three-way solenoid 11. When the three-way solenoid 11 receives an EGR close signal, it closes the negative pressure chamber of the diaphragm device 10b. By introducing atmospheric pressure to
When the EGR valve 10 is closed and an open signal is received, negative pressure downstream of the throttle is introduced into the negative pressure chamber.
The EGR valve 10 is opened.

Further, in the figure, 12 is a water temperature sensor that detects the temperature of engine cooling water, 13 is a rotation speed sensor that detects the engine rotation speed from the rotation angle of the distributor, and 14 is a controller consisting of an interface 15, a CPU 16, and a memory 17. In the memory 17, the basic fuel injection pulse, which is the basic control value of the fuel supply amount when EGR gas is recirculated and when it is not recirculated, is mapped using the engine rotation speed and negative pressure as parameters, and the fourth, Programs for arithmetic processing of the CPU 16, etc., shown in a flowchart in FIG. 5, are stored.

Furthermore, the CPU 16 generates a close signal when the engine 11 cooling water temperature is below the set temperature T.
The EGR valve 10 is closed, and when the temperature reaches the set temperature T or higher, an open signal is generated and the EGR valve 1 is closed.
EGR control is performed by opening 0. Further, the CPU 16 selects one of the basic fuel injection pulse maps in the memory 17 according to the opening/closing control state of the EGR valve 10, and reads out the basic fuel injection pulse according to the engine speed and negative pressure from the selected map. , corrects the pulse using the output of the air-fuel ratio sensor 7 to obtain an actual fuel injection pulse, which is then applied to the fuel injection valve 4 for fuel injection control. Furthermore, when the difference between the basic fuel injection pulse and the actual fuel injection pulse is greater than or equal to the set value, the CPU 16 selects the map of the other basic fuel injection pulse, and in that state, the difference between the two pulses becomes less than or equal to the set value. When it gets hot, it is determined that the EGR device 8 is malfunctioning.
Control is performed to turn on the EGR failure lamp 18.

In the above configuration, the negative pressure sensor 6 and the rotational speed sensor 13 serve as the operating state sensor 24 in FIG. 2, and the memory 17 serves as the first and second memory elements 19 in FIG. , 20, and the CPU 16 is connected to the EGR device 1 in Fig. 2.
EGR control means in 8, operating state detection means 21,
The functions of the selection means 22, the fuel supply control means 23, and the failure detection means 27 are realized.

Next, the operation will be explained using FIGS. 4 and 5.

When the engine starts, the CPU 16 executes the main routine shown in _FIG . Read each output of sensor 13 (step 3)
1) Determine whether or not the engine cooling water temperature is below the set value T (step 32). If the water temperature is above the set value T, it is determined NO in the above step 32 and the process proceeds to step 33, where the EGR flag is set to "1". ”, and on the other hand, if the water temperature is below the set value T, proceed to step 32 above.
If the result is YES, the process proceeds to step 34, where the EGR flag is set to "0". Next, the CPU 16 determines whether the register fail is “1” (step 3).
5) If no failure has occurred in the EGR system, the memory content of the register fail is "0", so the determination in step 35 is NO and the process proceeds to step 36.
Therefore, it is determined whether the O ₂ sensor output has reversed.

And if the _O2 sensor output is not inverted,
The CPU 16 determines NO in step 36 and proceeds through steps 37 and 38, where the timer value since the previous _O2 sensor output was reversed is the second set value.
K2 or higher, that is, whether or not the O ₂ sensor output is stuck, and whether it is the first set value K1.
Since the timer value does not exceed the first set value K1 during normal operation, it is determined NO in the above step 37, YES in the above step 38, and the process proceeds to step 39, where the register is set.
After storing the O ₂ sensor output in the CFB, it is determined whether the EGR flag is "1" (step 40),
If the EGR flag is “1”, proceed to step 4 above.
If the EGR flag is 0, it is determined as YES and the process proceeds to step 41, where the EGR open signal is output.On the other hand, when the EGR flag is ``0'', the process makes a NO judgment in step 40 and proceeds to step 42, where the EGR close signal is output. Then, the process returns to step 31 and repeats the process described above. On the other hand, if the O ₂ sensor output fluctuates for some reason, the CPU 16
makes a YES determination in step 37 and proceeds to step 50, where 1.0 is stored in register CFB to stop feedback control, and then steps 40, 41 or 40, 42 are followed.

Also, if the O ₂ sensor output is reversed, CPU1
Step 6 determines YES in step 36, proceeds through steps 43 and 44, determines whether the timer value is greater than or equal to the first set value K1 _and less than or equal to the second set value _K2 , and resets the timer. After that, the process proceeds to step 37 and the same processing as above is performed.

Furthermore, when an interrupt signal such as an ignition signal IC is input to the CPU 16 while executing the main routine processing as described above, the CPU 1
Step 6 moves from the main routine processing to the interrupt routine processing shown in FIG. 5. First, it is determined whether the EGR flag is "1" or not (step 51), and if the EGR flag is "1", the answer is YES in step 51. The process proceeds to step 52 and the EGR is stored in the memory 17 as the basic fuel injection pulse map TPMAP.
Select the map TPON during gas reflux, and if the EGR flag is "0", proceed to step 51.
If the answer is NO, proceed to step 53 and map
The map TPOFF at the time of EGR gas non-recirculation is selected as TPMAP, and then the basic fuel injection pulse TP is read from the map TPMAP according to the engine speed and negative pressure (step 54). ₂ sensor output to find the actual fuel injection pulse Ti (Step 5)
5) This actual fuel injection pulse Ti is applied to the fuel injection valve 4.
In addition, the process returns to the main routine (step 56).

And while performing the above process,
If a failure occurs in the EGR system, for example if the EGR passage 9 is clogged, the air-fuel ratio of the mixture will become over-lean; on the other hand, if the EGR valve device 10 is left open, the air-fuel ratio of the mixture will become over-lean. Therefore, the O ₂ sensor output is not inverted and the timer value is greater than or equal to the first set value K1, so the CPU 16
It is determined NO in step 38 of the main routine and proceeds to step 45, where it is determined whether the O ₂ sensor output is lean, that is, whether the EGR passage 8 is clogged or the EGR valve 10 is open abnormally, and the EGR
If passage 8 is clogged, proceed to step 45 above.
Determine YES and proceed to step 46, where
The EGR flag is set to "0", and if the EGR valve 10 is open abnormally, it is determined NO in step 45 and the process proceeds to step 47, where the EGR flag is set to "1", and then steps 40 and 4 described above are performed.
1, 40, and 42 to perform EGR control, and as a result, in the interrupt routine processing, the other map TPOFF or TPON is selected as the basic fuel injection pulse map TPMAP, and fuel injection is performed using this map TPMAP. Control will be carried out.

In this way, EGR control and fuel injection control are performed in response to a failure in the EGR system, and when the O ₂ sensor output is reversed, the CPU 16
If it is determined as YES, the process proceeds to step 43, where it is determined whether the timer value is greater than or equal to the first set value K1 and less than or equal to the second set value K2.
If the value is below the second set value K2, it is determined that there is a failure in the EGR system, and YES is determined in step 43, and the process proceeds to step 48. There, after storing "1" in the register fail, the failure detection lamp 18 is turned on. At the same time as lighting (step 49), register CFB
1.0 is stored in the register (step 50), and the path of steps 40, 41 or 40, 42 is followed to return to step 31, and the above processing is performed. This time, since the register fail is "1", A YES determination is made in step 35, and the process directly proceeds to step 49.

In the device of this embodiment as described above, the basic fuel injection pulse map is switched in the event of a failure in the EGR system, so the fuel injection amount can always be optimally controlled, and the air-fuel ratio can be greatly shifted toward the rich or lean side. Since the feedback control of the fuel injection amount is stopped when there is a deviation, that is, when the O ₂ sensor output fluctuates, it is possible to reduce the deviation in the air-fuel ratio and improve combustibility.

In addition, with this device, when normal feedbug control is performed with the map switched,
Since the EGR system is determined to be a failure, the EGR
It can detect a wide range of EGR system failures, not just valve opening abnormalities.

In the above embodiment, an O ₂ sensor that detects whether the O ₂ concentration in the exhaust gas is above or below a set value was used as _the O ₂ sensor.
It may also be something that detects a concentration value.

In addition, in the above embodiment, when the O ₂ sensor output continues to be in a lean or rich state for a period longer than the first set time K1, the map is switched to detect a failure in the EGR system. The map may be switched when the magnitude of the difference between the value (basic fuel injection pulse) and the actual control value (actual fuel injection pulse) is greater than or equal to the set value.

[Effect of idea]

As described above, according to the present invention, in the fuel supply system for an engine equipped with an EGR device and a speedy fuel supply system, the difference between the basic control value and the actual control value of the fuel supply amount is When the value exceeds the set value, the basic control value map is switched,
As a result, a failure of the EGR system is determined when the difference between the control values mentioned above becomes less than the set value, so the amount of fuel supplied can be well controlled.
This is effective in detecting EGR system failures over a wide range.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the present invention, FIG. 2 is a functional block diagram showing the configuration of the present invention, FIG. 3 is a schematic configuration diagram of an engine control device according to an embodiment of the present invention, and FIG. 4 and FIG. 5 are flowcharts showing the processing of the main routine and interrupt routine of the CPU 16 in the above-mentioned apparatus, respectively. 18... Exhaust gas recirculation device, 19, 20... First and second storage means, 21... Operating state detection means,
22... Selection means, 23... Fuel supply control means,
24... Operating state sensor, 25... Air-fuel ratio sensor, 26... Fuel supply means, 27... Failure detection means, 1... Engine, 4... Fuel injection valve, 6...
Negative pressure sensor, 7... _O2 sensor, 10...EGR valve,
13...Rotation speed sensor, 16...CPU, 17...
…memory.

Claims (1)

[Scope of utility model registration request] An exhaust gas recirculation device that recirculates a portion of exhaust gas to the engine intake system, a fuel supply means that supplies fuel to the engine, an operating state sensor that detects the operating state of the engine, and an air-fuel ratio of the air-fuel mixture. an air-fuel ratio sensor; an operating state detection means for detecting the operating state of the exhaust gas recirculation device; 1. a second storage means, a selection means for receiving the output of the operating state detection means and selecting one of the first and second storage means, and a selection means for receiving the output of both the operating state sensor and the air-fuel ratio sensor; A basic control value corresponding to the operating state sensor output in the selected storage means is corrected using the air-fuel ratio sensor output to obtain an actual control value, and the fuel supply amount of the fuel supply means is controlled using the actual control value. a control means, which receives a basic control value output and an actual control value output from the control means, causes the selection means to select the other storage means when the magnitude of the difference between the two control value outputs is greater than or equal to a set value; An engine control device characterized by comprising failure detection means for determining that the exhaust gas recirculation device is abnormal when the magnitude of the difference between the two control value outputs becomes equal to or less than a predetermined value.