JPH0236785B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is provided with a valve opening indicating means for outputting an instruction signal of the required valve opening of the exhaust recirculation valve according to the operating state of the engine, and the exhaust recirculation valve opening instruction from the indicating means is provided. The present invention relates to an exhaust gas recirculation control device for an internal combustion engine that corrects the deviation between a valve opening value and an actual valve opening degree using feedback control to achieve quick and accurate exhaust gas recirculation control.

The valve opening time of the fuel injection device of an internal combustion engine, especially a gasoline engine, is set to a standard value depending on the engine speed and the absolute pressure inside the intake pipe, and the specifications representing the operating state of the engine, such as the engine speed and the inside of the intake pipe. Constants and/or coefficients are added by electronic means depending on the absolute pressure of the engine, engine water temperature, throttle valve opening, exhaust concentration (oxygen concentration), etc.
The present applicant has proposed a fuel supply device that determines the amount of fuel by multiplying the amount of fuel and controls the fuel injection amount, thereby controlling the air-fuel ratio of the air-fuel mixture supplied to the engine.

According to this fuel supply control device, the reference value for the valve opening time of the fuel injection device is determined by two different maps depending on whether the exhaust recirculation valve is in operation or inactive. On the other hand, the amount of exhaust recirculation of the exhaust gas recirculation valve is controlled by determining the valve lift amount according to the engine rotational speed, the absolute pressure in the intake pipe, and the like. In this way, the amount of exhaust gas recirculation and the amount of fuel supplied are controlled according to the engine operating state, thereby optimizing the exhaust gas characteristics and operating performance of the engine.

Conventionally, in order to accurately control the exhaust recirculation amount, the actual opening value is detected against the opening indication value of the exhaust recirculation valve, and if there is a deviation between the indication value and the actual opening value, the valve is moved closer to the indication value. A device has been proposed that performs feedback control to control the valve opening to a target value. If the control method in such a control device is inappropriate, the valve opening degree will not converge to the target value, resulting in overshoot, hunting, or slow response speed, making it impossible to accurately control the amount of exhaust gas recirculation.

The present invention makes it possible to change the lift amount of the exhaust recirculation valve by using the negative pressure of the intake pipe and atmospheric pressure when the actual opening degree of the exhaust recirculation valve has a deviation from the indicated value, and also to change the lift amount of the exhaust recirculation valve according to the amount of deviation. An object of the present invention is to provide an exhaust gas recirculation control device for an internal combustion engine that achieves quick and accurate exhaust gas recirculation control by performing feedback control having a plurality of correction speeds.

Embodiments of the present invention will be described below with reference to the drawings.

First, FIG. 1 is a block diagram showing the entire fuel supply control device for an internal combustion engine to which the device of the present invention is applied. Reference numeral 1 indicates, for example, a four-cylinder internal combustion engine, and the engine 1 has four main combustion engines. This type consists of a combustion chamber and an auxiliary combustion chamber (both not shown) communicating with the combustion chamber. An intake pipe 2 is connected to the engine 1,
This intake pipe 2 includes a main intake pipe that communicates with each main combustion chamber and a sub-intake pipe that communicates with each sub-combustion chamber (both not shown).
Consists of. A throttle body 3 is provided in the middle of the intake pipe 2, and a main throttle valve and a sub-throttle valve (both not shown) disposed inside the main intake pipe and a sub-intake pipe, respectively, are provided in conjunction with each other. A throttle valve opening sensor 4 is connected to the main throttle valve and converts the valve opening of the main throttle valve into an electrical signal, which is then sent to an electronic control unit (hereinafter referred to as "ECU").
5).

A fuel injection device 6 is provided in the intake pipe 2 between the engine 1 and the throttle body 3. This fuel injection device 6 consists of a main injector and a sub-injector (both not shown).The main injector is located in the main intake pipe slightly upstream of the intake valve (not shown) for each cylinder, and the sub-injector is located in the sub-intake pipe. These throttle valves are common to each cylinder and are provided slightly downstream of the sub-throttle valve. The fuel injection device 6 is connected to a fuel pump (not shown). Main injector and sub injector are ECU5
The fuel injection valve opening time is controlled by a signal from the ECU 5.

On the other hand, an absolute pressure sensor 8 is provided immediately downstream of the main throttle valve of the throttle body 3 via a pipe 7, and an absolute pressure signal converted into an electrical signal by the absolute pressure sensor 8 is sent to the ECU 5.
sent to. Further, an intake air temperature sensor 9 is installed downstream thereof, and this air intake air temperature sensor 9 also converts the intake air temperature into an electrical signal and sends it to the ECU 5.

The main body of the engine 1 is provided with an engine water temperature sensor 10, which is made of a thermistor or the like, and is inserted into the engine cylinder wall filled with cooling water, and supplies a detected water temperature signal to the ECU 5.

Engine rotation speed sensor (hereinafter referred to as "Ne sensor")
) 11 and cylinder discrimination sensor 12 are installed around the camshaft or crankshaft (not shown) of the engine, and the former 11 receives a TDC signal, that is, at a predetermined crank angle position every 180° rotation of the engine crankshaft. The latter 12 outputs one pulse each at a predetermined crank angle position of a specific cylinder, and these pulses are sent to the ECU 5.

A three-way catalyst 14 is arranged in the exhaust pipe 13 of the engine 1, and performs a purifying action on HC, CO, and NOx components in the exhaust gas. On the upstream side of this three-way catalyst 14,
An O ₂ sensor 15 is inserted into the exhaust pipe 13 , and this sensor 15 detects the oxygen concentration in the exhaust gas and supplies the detected value signal to the ECU 5 .

Further, a sensor 16 for detecting atmospheric pressure and an engine starter switch 17 are connected to the ECU 5, and the ECU 5 is supplied with a detected value signal from the sensor 16 and a starter switch ON/OFF state signal.

An exhaust gas recirculation passage 18 is provided by connecting the exhaust pipe 13 to the intake pipe 2, and an exhaust gas recirculation valve 19 is provided in the middle of this passage 18. This exhaust recirculation valve 19
is a negative pressure responsive valve, and mainly includes a valve body 19a arranged to be able to open and close the passage 18, and atmospheric pressure or negative pressure connected to the valve body and selected and introduced by electromagnetic control valves 21 and 22, which will be described later. The diaphragm 19b is actuated by the diaphragm 19b, and the spring 19c biases the diaphragm 19b in the valve closing direction. A communication passage 20 is connected to the negative pressure chamber 19d defined by the diaphragm, and the absolute pressure in the intake pipe 2 is introduced through a normally closed electromagnetic control valve 22 provided in the middle of the communication passage 20. It is designed to be Further, an atmospheric communication passage 23 is connected to the communication passage 20 on the downstream side of the electromagnetic control valve 22, and atmospheric pressure is supplied to the communication passage 20 via a normally open electromagnetic control valve 21 provided in the middle of the communication passage 23. Then, it is introduced into the negative pressure chamber. The electromagnetic control valves 21 and 22 are both
It is connected to the ECU 5 and operates together or only one of them depending on the signal from the ECU 5 to control the lift operation and speed of the valve body of the exhaust recirculation valve 19.

The exhaust gas recirculation valve 19 is provided with a lift sensor 24 that detects the operating position of the valve body of the valve 19 and sends a detected value signal to the ECU 5.

Next, details of the fuel amount control operation of the fuel supply control device of the present invention having the above-described structure will be explained with reference to FIG. 1 and FIGS. 2 to 9 described above.

First, FIG. 2 shows the air-fuel ratio control of the present invention, that is,
This is a block diagram showing the overall program configuration of the control contents of the main and sub-injector valve opening times T _OUTM and T _OUTS in the ECU 5. It consists of a main program 1 and a sub-program 2, and the main program 1 is based on the engine speed Ne.
The subprogram 2 performs control in synchronization with the TDC signal and consists of a starting control subroutine 3 and a basic control program 4. On the other hand, the subprogram 2 consists of an asynchronous control subroutine 5 when not synchronized with the TDC signal.

The basic calculation formula in the start control subroutine 3 is expressed as T _OUTM = Ti _CRM ×K _Ne + ( _TV + ΔT _V ) (1) T _OUTS = Ti _CRS × K _Ne + T _V (2). Here, Ti _CRM and Ti _CRS are reference values for the valve opening times of the main and sub-injectors, respectively, and are determined by Ti _CRM and Ti _CRS tables 6 and 7, respectively. This is a correction coefficient at startup defined by K _Ne and is determined by K _Ne table 8.
T _V is a constant for correcting the increase or decrease of the valve opening time according to changes in battery voltage, and is obtained from _TV table 9. _TV is for the sub-injector, while the injector for the main injector is different due to the difference in structure. The amount of ΔT _V is increased according to the operating characteristics of.

In addition, the basic calculation formula in basic control program 4 is T _OUTM = (Ti _M − T _DEC ) × (K _TA・K _TW・K _AFC・K _PA・K _AST
・K _WOT・K _O2・K _LS ) +T _ACC × (K _TA・K _TWT・K _AFC・K _PA・K _AST )+(T _V +Δ
T _V )……(3) T _OUTS = (Ti _S − T _DEC ) × (K _TA・K _TW・K _AST・K _P
A ) + T _V ………(4) Here, Ti _M and Ti _S are reference values for the valve opening times of the main and sub-injectors, respectively, and are calculated from the basic Ti map 10, respectively. T _DEC and T _ACC are constants during deceleration and acceleration, respectively, and are determined by the acceleration and deceleration subroutine 11. Various coefficients such as K _TA , K _TW . . . are calculated by respective tables and subroutines 12. K _TA is calculated from the table based on the intake air temperature, K _TW is the fuel increase coefficient obtained from the table based on the actual engine water temperature T _W , K _AFC is the fuel increase coefficient after fuel cut determined by the subroutine, K _PA is an atmospheric pressure correction coefficient determined from a table based on the actual atmospheric pressure, K _AST is a post-start fuel increase coefficient determined by a subroutine, and K _WOT is a constant that enriches the mixture when the throttle valve is fully opened. The coefficient K _O2 is an O ₂ feedback correction coefficient determined by a subroutine according to the actual oxygen concentration in exhaust gas, and K _LS is a constant that is a lean coefficient of the air-fuel mixture during lean/stoichiometric operation. Stoichiometric is an abbreviation for Stoichiometric, which indicates stoichiometric amount, that is, the theoretical air-fuel ratio. Further, T _ACC is a fuel increase constant during acceleration determined by the subroutine, and is determined from a predetermined table.

On the other hand, the formula for calculating the asynchronous control subroutine 5 for the valve opening time T _MA of the main injector, which is not synchronized with the TDC signal, is T _MA = Ti _A ×K _TWT × K _AST + (T _V + ΔT _V ) ………(5 ). Here, Ti _A is a fuel increase reference value during acceleration control that is asynchronous during acceleration, that is, not synchronized with the TDC signal, and is determined from the Ti _A table 13. K _TWT is the water temperature increase coefficient K _TW shown in Table 1.
Synchronous acceleration obtained from 4 and calculated based on it,
This is the fuel increase coefficient after acceleration and during non-uniform acceleration.

Figure 3 shows the cylinder discrimination signal and TDC signal input to the ECU 5, and the main signal and TDC signal output from the ECU 5.
This is a timing chart showing the relationship between the sub-injector drive signal and the pulse of the cylinder discrimination signal _S1 .
S ₁ a is inputted once every 720° of the engine crank angle, and in parallel, pulses S _{2 a} - S _{2 e of the TDC signal S 2} are inputted once every 180° of the engine crank angle.
Each cylinder's main injector drive signal S ₃ − is inputted pulse by pulse, and the relationship between these two signals is
The output timing of _S6 is set. That is, the first TDC signal pulse S ₂ a outputs the main injector drive signal S ₃ for the first cylinder, and the second TDC
The main injector drive signal S ₄ for the third cylinder is output at the signal pulse S ₂ b, the drive signal S 3 for the fourth cylinder is output at the third pulse S ₂ c, and the drive signal S ₃ for the fourth cylinder is output at the fourth pulse S ₂ d. 2 cylinder drive signal S ₆
are output sequentially. Further, the sub-injector drive signal _S7 is generated one pulse each time each TDC signal pulse is input, that is, every 180 degrees of crank angle.
The TDC signal pulses S ₂ a, S ₂ b... are set to occur 60 degrees earlier than the top dead center of the piston in the cylinder. The time lag between when the air-fuel mixture is generated by opening the valve and operating the injector until the air-fuel mixture is sucked into the cylinder is absorbed in advance.

FIG. 4 shows a flowchart of the main program 1 when the valve opening time is controlled in synchronization with the TDC signal in the ECU 5, and the program as a whole consists of an input signal processing block, a basic control block, and a starting control block. First, in the input signal processing block, when the engine ignition switch is turned on, the CPU in the ECU 5 is initialized (step 1), and when the engine is started, a TDC signal is input (step 2). Then all the basic analog values are atmospheric pressure P _A , absolute pressure P _B , from each sensor.
Engine water temperature T _W , atmospheric pressure T _A , lift amount L of the valve body of the exhaust recirculation valve 19 , battery voltage V, throttle valve opening θth, output voltage value V of the O ₂ sensor, and on/off state of the starter switch 17 ECU etc.
5 and store the necessary values (step 3). Next, the elapsed time from the first TDC signal to the next TDC signal is counted, and based on that value, the engine rotation speed Ne is calculated and stored in the ECU 5 (step 4). Next, in the basic control block, it is determined whether or not the calculated value of Ne indicates that the engine speed is less than or equal to the cranking speed (starting speed) (step 5). If the answer is affirmative (Yes), it is sent to the startup control subroutine of the startup control block, and the engine cooling water temperature is determined by the Ti _CRM table and Ti _CRS table.
Determine Ti _CRM and Ti _CRS based on T _W (Step 6),
Further, the correction coefficient for Ne is determined using the K _Ne table (step 7). Then, determine the battery voltage correction constant _TV using the _TV table (step 8).
Insert each numerical value into the above equations (1) and (2) to calculate T _OUTM and T _OUTS (step 9).

When performing the above-mentioned startup subroutine, the lift instruction value L _MAP of the lift instruction value map for setting the lift amount of the valve body of the recirculation control valve is set to zero (step 10). Fig. 5 shows a map of the lift instruction value L _MAP , and the absolute pressure P _B is set in 10 stages as P _B6 P _B15 in the range of 204 to 780 mmHg, and the rotation speed
For example, Ne is provided in 10 stages as N ₁ to N ₁₀ in the range of 0 to 4000 rpm, and the indicated value corresponds to the engine rotation speed Ne and absolute pressure P _B other than the map grid points.
L _MAP is obtained by interpolation calculation. If the answer is No in step 5, it is determined whether the engine is in fuel cut mode (step 11), and if the answer is yes, the above
While setting the L _MAP value to zero (step 12),
Set the values of T _OUTM and T _OUTS to zero (step 13).

On the other hand, if the answer is determined to be No in step 11, each correction coefficient K _TA , K _TW , K _AFC ,
Calculate K _PA , K _AST , K _WOT , K _O2 , K _LS , K _{TWT , etc.} and correction constants T _DEC , T _ACC , TV , ΔT _V using their respective subroutines or tables (step
14).

Next, it is determined whether the actual engine cooling water temperature T _W is higher than the predetermined value T _WE at which exhaust gas recirculation should be performed (step 15). If the answer is yes, the actual engine cooling water temperature T W is determined from the lift instruction value map. Lift instruction value according to engine speed Ne and intake pipe absolute pressure P _B
Take out the L _MAP (step 16). Next, it is determined whether the exhaust gas recirculation valve 19 is operating or not operating (hereinafter referred to as "EGR operating" or "non-EGR operating") (step 17), and if the answer is affirmative (Yes),
A reference value Ti _M is selected according to the actual engine speed Ne and absolute pressure P _B from the Ti _M map during EGR operation.
(Step 18). If the answer in step 17 is No, a reference value Ti _M corresponding to the actual engine speed Ne and absolute pressure P _B is selected from the Ti _M map during non-EGR operation (step 20).

On the other hand, if the answer in step 15 is negative (No), the lift instruction value L _MAP is set to zero (step 15).
19), and a reference value Ti _M corresponding to the actual engine speed Ne and absolute pressure P _B is selected from the Ti _M map during non-EGR operation (step 20).

After selecting the reference value Ti _M as described above, a reference value Ti _S corresponding to the actual engine speed Ne and absolute pressure P _B is selected from the Ti _S map (step 21).

T _OUTM ,
Calculate T _OUTS (Step 22). Then, the main and sub-injectors are operated, respectively, based on the T _OUTM and T _OUTS values obtained in steps 9, 13, and 22 described above (step 23).

As mentioned above, in addition to controlling the valve opening times of the main and sub-injectors in synchronization with the TDC signal, the main injector is controlled in synchronization with a pulse train that is not synchronized with the TDC signal but has a fixed time interval. Asynchronous control is performed, but detailed explanation will be omitted.

Next, a method of controlling the exhaust gas recirculation valve will be explained with reference to FIGS. 6 to 8. As described above, in step 16 of FIG. 4, the command value L _MAP of the lift amount L of the exhaust gas recirculation valve shown in FIG. 5 is determined in accordance with the engine speed Ne and the intake pipe absolute pressure P _B. On the other hand, the first
Lift sensor 2 installed in the exhaust gas recirculation valve 19 shown in the figure
4, the actual opening L _ACT of the exhaust recirculation valve is input to the ECU 55, and the deviation l between the actual opening L _ACT and the indicated value L _MAP is calculated.
(=L _ACT −L _MAP ) is calculated. Depending on the absolute value and sign (i.e., plus or minus) of the deviation l, the pressure in the negative pressure chamber 19d provided in the exhaust gas recirculation valve 19 is controlled by the electromagnetic control valve 21 (which communicates with the atmosphere; hereinafter referred to as " _SOL.A "). ) and the electromagnetic control valve 22 (intake pipe 2
is connected to. (hereinafter _referred to as "S _OL . controlled. FIG. 6 illustrates changes in the operation of the exhaust gas recirculation valve depending on the absolute value and sign of the deviation l. When the absolute value of the deviation l is large, the lift correction operation of the exhaust recirculation valve is carried out rapidly, and when the absolute value of the deviation l is smaller than the predetermined value l ₁ , the lift correction operation is performed slowly, and furthermore, when the absolute value of the deviation l is smaller than the predetermined value l ₀ . If it becomes smaller, it is assumed that the target value has been reached, and the lift correction operation is stopped to maintain the current state. Now, if the indicated value is L _MAP > 0 _and the sign of the deviation is negative and the lift amount is too small (l<-l ₁ B), S _OL .
A and _SOL . B is energized and the negative pressure chamber 19 is
The passage 20 that communicates with the intake pipe 2 is opened, and the passage 23 that communicates with the atmosphere is closed to create a negative pressure chamber 19d.
By making the pressure negative, the exhaust recirculation valve is lifted up in rapid mode. When the exhaust recirculation valve opening increases and the deviation l approaches the target value -l ₁ B<l<-l ₀ , the lift-up operation of the exhaust recirculation valve is slowed down so that the actual valve opening does not overshoot the target value. _SOL for fast mode. Turn on valve B intermittently.
Perform duty control to turn off. in this way,
_SOL in rapid mode. In the slow mode, _SOL . By repeating the opening and closing of valve B, the lift-up speed of the exhaust gas recirculation valve can be controlled to a desired slow speed. When the lift further increases and the actual valve opening approaches the target value and the deviation l enters the allowable range of minute amount ±l ₀ , that is, when -l ₀ ≦ l ≦ + l ₀ , lift correction is performed. stop. Changes in deviation l and _SOL over time as explained above. A and _SOL . The relationship between B and changes in energization operation is shown in FIG. 7a.

Next, if the indicated value L _MAP is L _MAP > 0, the sign of the deviation is positive, and the lift amount is excessive (l > + l ₁ A),
_SOL ． A and _SOL . B is shut off and deenergized to create negative pressure chamber 1.
9d is communicated with the atmosphere, and the exhaust recirculation valve is lifted down in rapid mode. When the deviation l approaches the target value and becomes +l ₀ <l < +l ₁ A, S _OL . A
Performs duty control that turns the valves on and off intermittently. In this way, when the duty control is performed in the same way as in the case where the lift amount is too small, the lift down speed of the exhaust gas recirculation valve can be controlled to an arbitrarily slow speed. When the lift further decreases and the actual valve opening approaches the target value and the deviation l enters the allowable range of minute amount ±l ₀ , that is, -l ₀ ≦l ≦ +l ₀
When it reaches , the lift correction operation is stopped. The change in deviation l with respect to the time course explained above, and the change _{in SOL} .
The relationship between the changes in the energization operations of A and _SOL B is shown in FIG. 7b.

There is an instruction to set the lift amount L of the exhaust recirculation valve to 0.
When output from ECU5 (indication value L _MAP = 0),
The valve body 19a of the exhaust recirculation valve 19 is pressed against the valve seat (not shown in FIG. 1) by the spring 19c to close the passage, so in this case, the exhaust gas is kept until the actual valve opening reaches 0. Even if the lift-down operation of the recirculation valve is performed in the rapid mode, there is no fear that the valve body 19a will overshoot or hunt. Figure 8 shows the indicated value L _MAP
Change in deviation l when =0 is output and S _OL . A and _SOL . The relationship between B and the energization operation is shown. _SOL ． A and _SOL . Both B are cut off and deenergized, and the lift-down operation is performed in rapid mode.

FIG. 9 shows an embodiment of a valve opening degree control circuit provided in the ECU 5 for carrying out the above-described method of controlling the exhaust gas recirculation valve. The engine speed sensor 11 in FIG.
The output terminal is connected to the N _E value register 29, and the second output terminal is connected to the Ne measurement counter 28 and the address register 30, respectively. A first reference clock generation circuit 27 is connected to the input side of the sequence clock generation circuit 26 and to the Ne measurement counter 28.
It is connected to the. Ne measurement counter 28, N _E
The value register 29 and the address register 30 are connected in this order, and the output side of the address register 30 is further connected to the input side of the valve opening instruction memory 31. Intake pipe absolute pressure in Figure 1
The P _B sensor 8 is connected to the P _B sensor 8 via the first A/D converter 32.
It is connected to the input side of the value register 30, and P _B
The output side of the value register 33 is connected to the input side of the address register 30. The output side of the valve opening instruction value memory 31 is connected to the input terminal 3 of the comparator circuit 34.
4a and an input terminal 35a of the subtraction circuit 35. The EGR lift sensor 24 shown in FIG. 1 is connected to the input side of a valve opening value register 37 via a second A/D converter 36.
The output side of the valve opening value register 37 is connected to the input terminal 35b of the subtraction circuit 35. No.
2A/D converter 36 and valve opening value register 3
Two reference clock generation circuits 38 are connected to 7, and a start command signal and a data set signal are respectively supplied from the reference clock generation circuits 38. The output terminal 35c of the subtraction circuit 35 is connected to one input terminal of each of AND circuits 39 to 42 and one input terminal of each of AND circuits 44 to 47 via an inverter 43. The other output terminal 35d of the subtraction circuit 35 is connected to the AND circuits 39 and 4.
It is connected to the other input terminal of 4. The output side of the AND circuit 44 is the input terminal 48b of the comparison circuit 48.
and connected to the input terminal 49b of the comparison circuit 49,
The output side of the AND circuit 39 is connected to an input terminal 50b of a comparison circuit 50 and an input terminal 51b of a comparison circuit 51. The input terminals 48a to 51a of the comparison circuits 48 to 51 are provided with an l ₁ A value memory 52, an l ₀ value memory 53, an l ₀ value memory 54, and an l ₁ B value memory 55.
are connected to each other. The AND circuit 45
The output terminal 4 of the comparison circuit 48 is connected to the other input terminal of the comparator circuit 48.
8c, the output terminal 48d of the comparison circuit 48 and the output terminal 49c of the comparison circuit 49 are respectively connected to the second and third input terminals of the AND circuit 46, and the output terminal of the comparison circuit 49 is connected to the other input terminal of the AND circuit 47. Terminals 49d are connected to each other. Also, the above
The comparison circuit 5 is connected to the other input terminal of the AND circuit 40.
The output terminal 50c of the comparison circuit 50 and the output terminal 51c of the comparison circuit 51 are respectively connected to the second and third input terminals of the AND circuit 41.
However, the output terminal 51d of the comparison circuit 51 is connected to the other input terminal of the AND circuit 42, respectively. The output side of the AND circuit 45 is connected to one input terminal of an OR circuit 56, and the output side of the OR circuit 56 is connected via an inverter 57 to one input terminal of the AND circuit 58 and directly to the input side of the OR circuit 64. There is. The output side of the AND circuit 46 is connected to the input terminal of each one of the OR circuit 64 and the AND circuit 59,
The output side of the AND circuit 47 is connected to each input side of the OR circuit 63 and the OR circuit 64. The third reference clock generation circuit 61 is connected to the input side of the OR circuit 63 via the AND circuit 59. AND
The output side of the circuit 40 is an OR circuit 63 and an OR circuit 6.
The output side of the AND circuit 41 is connected to the input sides of the OR circuit 63 and the AND circuit 60, and the output side of the AND circuit 42 is connected to the input sides of the OR circuit 63 and the AND circuit 42, respectively.
and each input side of the OR circuit 65.
The fourth reference clock generating circuit 62 is connected to the input side of the OR circuit 65 via the AND circuit 60. The output side of the OR circuit 63 is connected to the other input terminal of the AND circuit 58, the output side of the OR circuit 64 is connected to one input terminal of the AND circuit 67 via the inverter 66, and the output side of the OR circuit 65 is connected to the other input terminal of the AND circuit 67. are respectively connected to the other input terminal. AND
The output side of the circuit 58 is connected to the solenoid of the electromagnetic control valve ( _SOL.A ) 21 shown in FIG.
The output side of each is connected to the solenoid of the electromagnetic control valve ( _SOL.B ) 22. The output terminal 34c of the comparison circuit 34 is connected to the input side of the OR circuit 56.

The functions and effects of the exhaust recirculation valve control circuit configured as described above will be described in detail below.

The TDC signal from the engine speed sensor 11 is
The signal is supplied to a one-shot circuit 25 that constitutes a waveform shaping circuit together with a sequence clock generation circuit 26 at the next stage, and the one-shot circuit 25 generates an output signal _S0 for each TDC signal, and the signal _S0 is used for sequence clock generation. The sequence clock generation circuit 26 generates predetermined sequence clock signals _CP0 and _CP1 using the reference clock signal supplied from the first reference clock generation circuit 27, _S0.
Each time a signal is input, they are generated sequentially, and the CP ₀ signal is supplied to the _NE value register 29, and the CP ₁ signal is supplied to the Ne measurement counter 28 and address register 30, respectively. The Ne measurement counter 28 starts counting the number of clock pulses of the first reference clock generation circuit 27 when the CP ₁ signal is input, counts and stores the number of pulses until the next CP ₁ signal is input, At the timing of the CP ₀ signal applied to the _NE value register 29, a value corresponding to the number of pulses stored by the Ne measurement counter 28 is inputted to the _{NE value register 29 as the NE value} . Therefore, the higher the engine speed, the shorter the interval between the occurrences of the _CP1 signal, so the N _E value register 29 stores a value proportional to the reciprocal of the engine speed Ne. P _B value register 3
3, the intake pipe absolute pressure signal measured by the P _B sensor 8 is converted into a digital quantity by the first A/D converter 32 and stored. address register 30
When sequence clock signal CP ₁ is applied to N _E
The value corresponding to the engine speed Ne stored in the value register 29 and the intake pipe absolute pressure value stored in the P _B value register 30 are input to the address register 30 and correspond to the engine speed Ne and the absolute pressure P _B. The address value _LMAP stored in the valve opening instruction value memory 31 is selected according to the address value.
The address value and L _MAP value corresponding to the engine speed Ne and absolute pressure P _B are stored in the address register 30 and the valve opening instruction value memory, respectively, so as to correspond to the map of the lift instruction value L _MAP shown in Fig. 5. L _MAP is calculated by cage interpolation calculation. The instruction value L _MAP thus obtained is input to the input terminal 34a of the comparator circuit 34 as a signal _A4 , and to the input terminal 65a of the subtraction circuit 35 as a signal Y.

The other input terminal 34b of the comparison circuit 34 is grounded, which means that the input signal B ₄ =0.
When the indicated value L _MAP > 0, A ₄ = B ₄ does not hold, so in this case, the output = 0 is output from the output terminal 34c, and the output = 1 inverted by the inverters 57 and 66 is output from the respective AND circuits 58 and 66. 67 input terminals. At this time, if input = 1 is input to the other input terminal of the AND circuits 58 and 67, _SOL . A and _SOL . Both solenoids of B are energized and the valves are opened. indicated value
When L _MAP = 0, A ₄ = B ₄ is established in the comparison circuit 34, and the output = 1 is output from the output terminal 64c.Therefore, the output = 0 inverted by the inverters 57 and 66 is output from the AND circuits 58 and 67, respectively. Supplied to one input terminal. Therefore, at this time, regardless of the on-off signal input to the other input terminal of the AND circuits 58 and 67, _SOL . A and _SOL . Both solenoids at B are deenergized and the valves are closed, lowering the lift and closing the exhaust recirculation valve in the rapid down mode illustrated in FIG.

The actual valve opening signal from the lift sensor 24 attached to the exhaust recirculation valve is input to the second A/D converter 36, and the second reference clock generating circuit 38 is input to the second A/D converter 36.
A new actual valve opening signal is A/D converted for each start command signal supplied from the valve opening value register 37.
supplied to The valve opening value register 37 replaces the stored value with a new value for each data set signal supplied from the second reference clock generation circuit 38, and supplies the new value to the input terminal 35b of the subtraction circuit 35 as a signal X.

The subtraction circuit 35 outputs the actual valve opening signal X and the indicated value.
Subtraction (X-Y) of the signal Y of L _MAP is performed to obtain the deviation l (=X-Y). When X-Y<0, output from the output terminal 35c of the subtraction circuit 35 = 1
However, when X-Y≧0, output=0 is output. On the other hand, from the other output terminal 35d,
The value of (=l) is output.

Now, the case where the actual lift amount is too small as shown in FIG. 6 will be explained as an example. First, when the instruction value L _MAP has just been output and the deviation l<-l ₁ B, the subtraction circuit 35 has X-Y<-l ₁ B, so the output = 1 from the output terminal 35c is the AND circuit 39 42. Also, the output = 0 inverted by the inverter 43 is
The signal is supplied to AND circuits 44 to 47, and the AND circuits 44 to 47 are closed. AND circuit 3
Output=1 is input to one input terminal of the subtractor circuit 35 and is in an open state, and the output terminal 35d of the subtraction circuit 35
The XY value from is supplied via the AND circuit 39 to the input terminals 50b of comparators 50 and 51 as a signal B ₂ and to 51b as a signal B ₃ . still,
If X-Y<0, the two's complement of the absolute value |X-Y| is respectively supplied to the comparison circuit. l ₀ value memory 5
4 stores the two's complement of the _l0 value mentioned above, and the stored value is input to the input terminal 50a of the comparator circuit 50.
is input as signal _A2 . l ₁ B value memory 5
5 stores the two's complement of the l ₁ B value described above, and the stored value is input to the input terminal 51 of the comparator circuit 51.
A is input as signal _A3 . Now X-Y<
-l ₁ B, so A ₂ > B ₂ is established in the comparator circuit 50, and output from the output terminal 50d to the AND circuit 41 =
1 is supplied, A ₃ > B ₃ is established in the comparison circuit 51, and output = 1 from the output terminal 51d to the AND circuit 42.
supply. Since output=0 is output from the other output terminals 50c and 51c of the comparison circuits 50 and 51, the AND circuits 40 and 41 are in a closed state,
Since only the AND circuit 42 has an output of 1 input to each of its input terminals, the output of 1 is supplied from the AND circuit 42 to the AND circuits 58 and 67 via the OR circuits 63 and 65. Therefore, the output = 0 is input to any input terminal of the OR circuit 64, and the output = 1 is inverted by the inverter 66.
It is supplied to the other input terminal of the AND circuit 67, and since A ₄ =B ₄ (L _MAP =0) does not hold in the comparator circuit 34, an output = 0 is output from the output terminal 34c and inverted by the inverter 57. Output = 1 is AND
Since it is supplied to the other input terminal of the circuit 58, S _OL .
A and _SOL . 6 and 7 when both B are energized and energized.
As shown in the figure, the exhaust recirculation valve is lifted up in rapid mode.

Next, the exhaust recirculation valve lift increases and the deviation becomes −l ₁ B<
When l<-l ₀ , the subtraction circuit 35 calculates that X-Y<
Since -l ₀ , the output=1 is supplied to the AND circuits 39 to 42 as described above. Comparison circuit 5
0 input signal is A ₂ = −l ₀ (two's complement l ₀ of l ₀ ), B ₂ =
Since X-Y=l, A ₂ >B ₂ holds true, and output=0 is supplied from the output terminal 50c to the AND circuit 40, and output=1 is supplied from the output terminal 50d to the AND circuit 41. The input signal of the comparator circuit 51 is A ₃ =-
l ₁ B (two's complement of l _{1 B} ), B ₃ = X-Y = l, so A ₃ ≦ B ₃ holds true, and AND
Output = 1 to the circuit 41, but output from the output terminal 51d
Output=0 is supplied to the AND circuit 42. AND circuits 40 and 42 are in a closed state because output = 0 is input to one of their input terminals, and AND circuit 41 is in a closed state because output = 1 is input to both input terminals. through the OR circuit 63
Output=1 is supplied to the AND circuit 58 and the AND circuit 60. The other input terminal of the AND circuit 60 is supplied with an on-off signal having a predetermined pulse width at a predetermined minute time interval generated by a fourth reference clock generation circuit 62. When the signal generated in is an ON signal, that is, output = 1, an output = 1 is supplied from the AND circuit 60 to the AND circuit 67 via the OR circuit 65. Therefore, the output = 0 is input to either input terminal of the OR circuit 64, and the output = 1 inverted by the inverter 66 is supplied to the other input terminal of the AND circuit 67, and the comparison circuit 34 outputs A ₄ =B ₄ (L _MAP =
Since _SOL . A is energized and S _OL . B is a fourth reference clock generating circuit 62, which performs duty control such that it is energized every time an on signal is transmitted. At this time, the exhaust gas recirculation valve is lifted up in the slow mode shown in FIGS. 6 and 7.

Furthermore, the exhaust recirculation valve lift increases and the deviation becomes -l ₀
When <l<0, the subtraction circuit 35 calculates -l ₀ <X
Since −Y<0, the AND circuit 39
Output=1 is supplied to 42 through 42. In the comparison circuit 50, A ₂ ≦B ₂ holds true, and the output terminal 50c outputs 1 to the AND circuit 40, and the output terminal 50c outputs 1 to the AND circuit 40.
Output=0 is supplied from d to the AND circuit 41.
In the comparator circuit 51, A ₃ ≦B ₃ holds true, and the output terminal 5
An output of 1 is supplied from the output terminal 1c to the AND circuit 41, and an output of 0 is supplied to the AND circuit 42 from the output terminal 51d. AND circuits 41 and 42 are input terminals 1
Since the output = 0 is input to the AND circuit 40, it is in a closed state, and since the output = 1 is input to both of the input terminals of the AND circuit 40, the AND circuit 40
Output = 1 via OR circuit 63 is AND circuit 58
The output = 0, which is inverted by the inverter 66, is supplied to the AND circuit 67 via the OR circuit 64 and the inverter 66. In the comparison circuit 34
Since A ₄ =B ₄ (L _MAP =0) does not hold, output = 0 is output from the output terminal 34c and the inverter 5
The output = 1 inverted at SOL.7 is supplied to the other input terminal of the AND circuit 58, and _SOL . A is energized,
Since output = 0 is input to one of the input terminals of the AND circuit 67, S _OL . B is cut off and deenergized. At this time, the lift amount of the exhaust recirculation valve is the indicated value which is the target value.
The control is completed when the L _MAP tolerance range ±l ₀ is reached, and the lift operation is stopped and maintained.

The case where the actual lift amount is too small has been explained above, but in the case where the actual lift amount is too large, that is, X-Y>l ₁ A
At this time, output = 0 is output from the output terminal 35c of the subtraction circuit 35, so the AND circuits 44 to 47 are opened, the AND circuits 39 to 42 are closed, and the comparison circuits 48 and 49 calculate the deviation l(=X-Y )but
It is compared with the aforementioned predetermined values L ₁ A and l ₀ stored in the l ₁ A value memory 52 and l ₀ value memory 53, respectively, and S _OL . A and _SOL . B is controlled. The control method can be explained in the same way as the case where the actual lift amount is too small, so the explanation will be omitted below.

In addition, the control of the exhaust recirculation valve lift operation is performed each time the TDC signal from the Ne sensor 11 is input, and the valve opening instruction value L _MAP corresponding to the engine speed Ne and absolute pressure P _B is determined by the comparison circuit as described above. 34 and a subtraction circuit 35, and is executed by a second reference clock generation circuit 38 which is not synchronized with the TDC signal. The output signal actual valve opening _LACT from 24 is supplied to the subtraction circuit 35, and control of the lift operation is also executed for each input.

As detailed above, according to the present invention, when the actual opening degree of the exhaust recirculation valve has a deviation from the indicated value, the lift amount of the exhaust recirculation valve can be changed using the negative pressure of the intake pipe and atmospheric pressure. Since it is decided to perform feedback control having a plurality of correction speeds depending on the amount of deviation, it is possible to control the exhaust gas recirculation valve quickly and accurately.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of a fuel supply control device to which the exhaust gas recirculation device of the present invention can be applied, and FIG.
Figure 3 is a block diagram of the overall program configuration of the control contents of the main and sub-injector valve opening times T _OUTM and T _OUTS in the ECU shown in the figure.
A timing chart showing the relationship between the cylinder discrimination signal and TDC signal input to the ECU and the main and sub-injector drive signals output from the ECU. Figure 4 is a flowchart of the main program with exhaust recirculation control. Figure 5 is a map of the lift command value L _MAP of the exhaust recirculation valve, and Fig. 6 shows the S _OL according to the deviation between the actual valve opening and the command value. A and _SOL . B's on
Figure 7 shows the lift operation of the exhaust recirculation valve due to off control. Figure 7 shows the speed change of the lift operation when the opening degree of the exhaust recirculation valve is set to the target value. FIG. 8 is a diagram showing the lift-down operation when the instruction value L _MAP =0, and FIG. 9 is a circuit diagram of an embodiment of the exhaust gas recirculation control device of the present invention. 1... Internal combustion engine, 2... Intake pipe, 8... Absolute pressure sensor, 11... Engine rotation speed sensor, 1
9... Exhaust recirculation valve, 21, 22... Solenoid control valve,
24... Lift sensor, 31... Valve opening instruction value memory, 34, 48, 49, 50, 51... Comparison circuit, 35... Subtraction circuit.

Claims (1)

[Scope of Claims] 1. In an exhaust recirculation control device including an exhaust recirculation passage connecting an exhaust pipe of an internal combustion engine to an intake pipe and an exhaust recirculation valve provided in the middle of the exhaust recirculation passage, valve opening indicating means for outputting an instruction signal for a requested opening of the exhaust recirculation valve in response to the request;
an actual valve opening detection means for detecting the actual opening of the exhaust recirculation valve and outputting an actual opening signal; and a valve opening changing means connected to the exhaust recirculation valve so as to change the opening of the exhaust recirculation valve. Depending on the instruction signal and the actual opening signal,
valve opening degree control means for supplying a control signal to the valve opening degree changing means so that the actual opening signal approaches the instruction signal; Depending on the deviation from the actual opening signal, if the deviation is outside a predetermined minute range and the absolute value of the deviation is large, a control signal is output that rapidly changes the valve opening, and the deviation is within the specified range. The exhaust gas recirculation valve is configured to output a control signal for changing the valve opening degree to a slow speed when the absolute value of the deviation is outside a predetermined minute amount section and the absolute value of the deviation is small, and the exhaust recirculation valve is a valve that opens and closes the exhaust gas recirculation path a negative pressure responsive member connected to the valve body and increasing the valve opening as negative pressure increases; and a negative pressure chamber having one wall formed of the negative pressure responsive member, the valve opening changing means a negative pressure passage that communicates the engine intake pipe with the negative pressure chamber; an atmospheric passage that communicates the atmosphere with the negative pressure chamber; a first solenoid valve provided in the middle of the negative pressure passage; and a first solenoid valve provided in the middle of the atmospheric passage. a second solenoid valve provided, the valve opening control means includes a deviation detection means for detecting the absolute value and sign of the deviation calculated by subtracting the instruction signal value from the actual opening signal value; a deviation determining means for determining the range of the absolute value of the deviation by comparing the absolute value of the deviation with a predetermined value, and a range of the absolute value of the deviation determined by the deviation determining means and a sign detected by the deviation detecting means. and a solenoid driving means for driving one or both of the first and second solenoid valves, and the solenoid driving means controls the deviation when the sign of the deviation is positive and the deviation changes from positive to zero. The first solenoid valve is always held in a fully closed position according to the absolute value of , and the second solenoid valve is continuously operated in a fully open position, duty energized
The control is performed in the order of continuous operation of the fully closed position, and the sign of the deviation is negative, and from the negative of the deviation to 0.
, the first solenoid valve is controlled in the order of continuous operation to the fully open position, duty energized, and continuous operation to the fully closed position according to the absolute value of the deviation, and the second solenoid valve is always controlled to the fully closed position. An exhaust recirculation control device for an internal combustion engine, which is configured to maintain the 2. The first solenoid valve is a normally closed on/off valve that closes a negative pressure passage when deenergized, and the second solenoid valve is a normally open on/off valve that opens an atmospheric passage when deenergized. When the sign of the deviation is positive and the deviation changes from positive to 0, the solenoid driving means always deenergizes the first solenoid valve according to the absolute value of the deviation, and deenergizes the second solenoid valve. The valve is controlled in the order of deenergization, duty energization, and continuous energization, and when the sign of the deviation is negative and the deviation changes from negative to 0, the valve is controlled in the order of deenergization, duty energization, and continuous energization. Exhaust recirculation control for an internal combustion engine according to claim 1, wherein the first solenoid valve is controlled in the order of continuous energization, duty energization, and deenergization, and the second solenoid valve is always energized. Device. 3. Claims in which the solenoid driving means is configured to maintain the first and second solenoid valves in the fully closed and fully open states, respectively, when the instruction signal output from the valve opening degree indicating means instructs the solenoid valves to be fully closed. 2. The exhaust recirculation control device for an internal combustion engine according to claim 1.