JPS6338538B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention corrects the output of a displacement detection means for detecting displacement of a control member in an engine control device, particularly an exhaust recirculation control device, an idle control device, etc. The present invention relates to a device designed to achieve accurate control.

(Prior art) An engine exhaust recirculation control device or idle control device detects the displacement (opening degree) of a control member such as an exhaust recirculation valve or a throttle valve, and determines the displacement to a preset value depending on the operating state. In this control, it is important to accurately detect the displacement of the control member in order to perform accurate control. However, the zero reference position of the sensor that detects the displacement of the control member may change due to installation errors, wear, thermal expansion, etc., and the output characteristics themselves with respect to the detected values also vary. Therefore, the output of the sensor does not accurately indicate the actual displacement of the control member, which causes a decrease in control accuracy.

For such problems, for example, Japanese Patent Application Laid-Open No. 1987-
Publication No. 188753 proposes "automatic correcting device for fully closed reference position of exhaust recirculation valve of exhaust recirculation control device". This device automatically corrects the fully closed reference position of the exhaust gas recirculation valve to achieve accurate exhaust gas recirculation control. However, since this device only corrects the fully closed reference position, that is, the zero point, it can deal with sensor installation errors and wear, but it does not prevent errors in the characteristics of the sensor, that is, the slope of the output value with respect to the detected value. In some cases, this cannot be addressed.

(Objective of the present invention) The present invention detects the displacement of a control member such as an exhaust recirculation valve in an exhaust gas recirculation control device or a throttle valve in an idle control device and performs feedback control of the displacement. The purpose of the present invention is to automatically correct the output characteristics including both the zero point and slope of a sensor that detects the exhaust gas recirculation amount or the idle rotation speed, etc., so that the control of the exhaust gas recirculation amount or the idle rotation speed can always be performed with high precision.

(Configuration of the Invention) An engine control device according to the present invention is configured as follows to achieve the above object.

First, as shown in FIG. 1, the control device of the present invention basically consists of a control member A that controls the operating state of the engine, such as an exhaust recirculation valve or a throttle valve, and a main displacement device that detects the displacement of the control member A. A detection means B, an operation state detection means C that detects engine operating states such as rotational speed and intake negative pressure, and a main storage device D that stores in advance the required displacement of the control member A according to each operating state. and a displacement difference calculating means E for calculating the difference between the required displacement read from the main storage device D and the detected displacement output from the main displacement detecting means B, and a displacement control means F that controls the control member A so as to make the difference zero. As a result, the displacement of the control member A, for example, the opening degree of the exhaust gas recirculation valve or the throttle valve, is feedback-controlled so that it becomes a preset opening degree depending on the operating state.

In the present invention, in addition to the above configuration,
Furthermore, two specific displacements of the control member A, namely the first,
From the first and second setting displacement detection means G and H that detect the second setting displacement, respectively, and the main displacement detection means B when these detection means G and H detect the first and second setting displacement, respectively. First and second storage means I and J that respectively store the output detected displacements, and the main displacement detection means B based on the stored values of both storage devices I and J.
A correction means K is provided for correcting the detected displacement output from. This correction means K calculates the output characteristic of the main displacement detection means B from the detected displacement (output value) of the main displacement detection means B when the displacement of the control member A is at the first and second set displacements, and calculates the output characteristic of the main displacement detection means B. If there is an error with respect to a predetermined reference characteristic, it is corrected to match the reference characteristic. As a result, when the detected displacement outputted from the main displacement detection means B is controlled to be equal to the required displacement read from the main storage device D, the displacement of the control member A is equal to the required displacement instructed by the main storage device D. will match.
It is preferable to use switches as the first and second set displacement detection means G and H in order to accurately detect the first and second set displacements of the control member A.
Further, in order to improve accuracy, it is desirable to select zero displacement (fully closed state) and maximum displacement (fully open state) of the control member A as the first and second set displacements.

(Example) The present invention will be described below based on an example regarding an exhaust gas recirculation control device.

As shown in FIG. 2, the exhaust gas recirculation control device includes an exhaust gas recirculation passage 3 that communicates the downstream position of the throttle valve 2 in the intake pipe 1 with an exhaust pipe (not shown), and a negative pressure installed on the passage 3. A diaphragm type exhaust recirculation valve 4, an electromagnetic control valve 5 that controls the opening degree of the valve 4 by controlling the control negative pressure supplied to the negative pressure chamber 4a of the valve 4, and a duty control of the control valve 5. It has a control circuit 6. This control circuit 6 receives a signal a from an engine rotation sensor 7 that detects the engine rotation speed, and an intake negative pressure sensor 8 that detects the intake negative pressure downstream of the throttle valve in the intake pipe 1.
and a signal c from a position sensor 9 that detects the displacement of the diaphragm 4b in the exhaust gas recirculation valve 4, that is, the opening degree of the valve 4,
The operating state is determined based on the signals a and b, and the required opening of the exhaust recirculation valve 4 corresponding to the operating state stored in advance is compared with the opening of the valve 4 indicated by the signal c. , and outputs first and second control signals d and e corresponding to the difference to the first and second solenoids 5a and 5b of the electromagnetic control valve 5, respectively. The first solenoid 5a closes the valve body 5c in response to the first control signal d, thereby controlling the intake negative pressure introduction path 10 led from the downstream side of the throttle valve of the intake pipe 1 and the exhaust gas recirculation valve 4. The second solenoid 5
b receives the second control signal e and opens and closes the valve body 5d to open and close the atmospheric pressure introduction path 12 led from the air cleaner (not shown) and the negative pressure supply path 1.
1 and is controlled to cut off communication. As a result, the control negative pressure supplied to the negative pressure chamber 4a of the exhaust recirculation valve 4 is controlled, and the diaphragm 4b moves against the spring 4c according to the magnitude of the control negative pressure, so that the diaphragm 4b moves integrally with the diaphragm 4b. The opening degree of the moving valve body 4d is controlled so as to match the above-mentioned required opening degree.

However, in this embodiment, the exhaust gas recirculation valve 4 is provided with a fully closed switch 13 for detecting the fully closed state of the valve 4 and a fully open switch 14 for detecting the fully open state of the valve 4, and the output from these switches 13 and 14 is A fully closed signal f and a fully open signal g are input to the control circuit 6.

Next, the configuration of the control circuit 6 will be explained.

As shown in FIG.
The output signal a is converted into a digital value by the rotational speed measuring counter 15 and then inputted to the operating state detection circuit 17 via the engine rotational speed register 16. In addition, the output signal b of the intake negative pressure sensor 8
The value is also converted into a digital value by the first A/D converter 18 and then input to the operating state detection circuit 17 via the intake negative pressure register 19. A data memory 20 that stores the required displacement (opening degree) of the exhaust gas recirculation valve 4 according to the operating state as a map is connected to the output side of the operating state detection circuit 17. Required displacement of exhaust recirculation valve 4 corresponding to rotation speed and intake negative pressure
Lmap is output.

On the other hand, the output signal c of the position sensor 9 provided in the exhaust gas recirculation valve 4 is transmitted to the second A/D converter 21,
The signals are input to the third A/D converter 22 and the fourth A/D converter 23, respectively. The second A/D converter 21 constantly outputs the detected displacement (opening degree) L of the exhaust gas recirculation valve 4, which is obtained by converting the signal c into a digital value. On the other hand, the third A/D converter 22 operates only when the fully closed signal f is input from the fully closed switch 13, that is, only when the exhaust recirculation valve 4 is fully closed. The displacement L ₁ detected by the position sensor 9 when the position sensor 9 is fully closed is outputted and input into the first register 24 . Similarly, the
The 4A/D converter 23 operates only when the full open signal g from the full open switch 14 is input, and the position sensor 9 operates when the exhaust recirculation valve 4 is fully open.
outputs the detected displacement L ₂ and stores it in the second register 2.
Enter 5. The fully closed detection displacement L ₁ stored in the first register 24 and the detection displacement L output from the second A/D converter 21 are input to the first correction circuit 26 and detected by the circuit 26. The displacement L is corrected to the first corrected displacement L'=L- _L1 .
Additionally, the fully closed detection displacement L ₁ stored in the first register 24 , the fully open detection displacement L ₂ stored in the second register 25 , and the fully closed exhaust gas recirculation valve 4 stored in the data memory 27 . The total displacement L ₀ from the state to the fully open state is input to the calculation circuit 28,
The arithmetic circuit calculates a correction coefficient k=(L ₂ -L ₁ )/L ₀ indicating the slope of the output characteristic of the position sensor 9. This correction coefficient k is input to the second correction circuit 29 together with the first correction displacement L', and the first correction displacement L' is corrected to the second correction displacement L''=L'/k.

Then, this second correction displacement L'' and the required displacement Lmap output from the data memory 20 are transmitted to the comparator circuit 3 via D/A converters 30 and 31, respectively.
2 is input. This comparison circuit 32
The first one that operates when Lmap is larger than the correction displacement L″
It consists of a comparator 33 and a second comparator 34 that operates when the corrected displacement L'' is larger than the required displacement Lmap,
When the first comparator 33 is activated, the first control signal d is outputted to the first solenoid 5a of the electromagnetic control valve 5 via the first drive circuit 35, and when the second comparator 34 is activated, the second drive circuit 36 is outputted. A second control signal e is output to the second solenoid 5b via the second solenoid 5b.

Next, the operation of the above embodiment will be explained with reference to the flowchart of FIG. 4 and the characteristic diagram of FIG. 5.

The control circuit 6 detects the operating state based on signals a and b input from the engine speed sensor 7 and the intake negative pressure sensor 8, and also detects the required displacement (opening degree) of the exhaust recirculation valve 4 corresponding to the operating state. )Lmap
is read from the data memory 20, and the displacement L of the exhaust gas recirculation valve 4 is detected based on the signal c from the position sensor 9 (steps S 1 _{and 1} in FIG. 4).
_S2 , _S3 ).

In this case, when the characteristic of the detected displacement (output value) L with respect to the actual displacement Lact of the position sensor 9 matches the reference characteristic shown by the solid line in FIG. 5, that is, when L=Lact always, , the detected displacement L is not corrected by the first and second correction circuits 26 and 29 (L=L′=L″), and the above-mentioned required displacement Lmap
It is also input to the comparator circuit 32. and,
When Lmap>L, the first control signal d is output from the control circuit 6 to the first solenoid 5a of the electromagnetic control valve 5, thereby increasing the control negative pressure supplied to the negative pressure chamber 4a of the exhaust recirculation valve 4. The opening degree of the valve 4 is increased until the detected displacement L becomes equal to the required displacement Lmap, and if Lmap<L, the second control signal e is output to the second solenoid 5b and the control negative is increased. As the pressure is lowered, the opening degree of the exhaust gas recirculation valve 4 is reduced until the detected displacement L becomes equal to the required displacement Lmap (steps _S10 to _S13 ). In this case, since the detected displacement L and the actual displacement Lact match, the above control causes the actual displacement Lact to match the required displacement Lmap.

However, if the characteristics of the position sensor 9 have an error with respect to the reference characteristics as shown by the dotted line in FIG. 5, the detected displacement L output from the sensor 9 does not correctly indicate the actual displacement Lact. Even if the detected displacement L is made to match the required displacement Lmap by the above-described control, the actual displacement Lact has a value different from the required displacement Lmap. In this case, the control circuit 6 operates as follows in order to match the characteristics of the position sensor 9 with the reference characteristics.

First, when the exhaust recirculation valve 4 becomes fully closed during operation, the third A/D converter 22 is activated by the signal f from the fully closed switch 13, and the displacement L detected by the position sensor 9 at that time is It is stored in the first register 24 as the fully closed detection displacement L ₁ (steps S ₄ and S ₅ ). Furthermore, when the exhaust gas recirculation valve 4 is fully open, the fourth A/D converter is activated by the signal g from the fully open switch 14, so that the displacement L detected by the position sensor 9 at that time is changed to the fully open detected displacement. It is stored in the second register 25 as _L2 (steps _S6 , _S7 ). Then, the first correction circuit 26 corrects the detected displacement L to the first correction displacement L′=L−L ₁ using the fully closed detection displacement L ₁ , and the correction coefficient k calculated by the calculation circuit 28
=(L ₂ −L ₁ )/L ₀ In the second correction circuit 29, the first correction displacement L′ is converted to the second correction displacement L″=
Correct to L'/k (steps S ₈ and S ₉ ). These corrections are made using the position sensor 9 shown in dotted lines in FIG.
This is to match the characteristic with an error with the reference characteristic shown by the solid line. In other words, L″=(L−L ₁ )L ₀ /
(L ₂ - L ₁ ), so for example, when L = L ₁ (fully closed), L'' = 0, and when L = L ₂ (fully opened),
L″=L ₀ , and the second correction displacement L″ is the actual displacement Lact
will match.

The displacement L'' corrected in this way is compared with the required displacement Lmap in the same way as in the above case, and is controlled so that L''=Lmap according to the above steps _S10 to _S13 . Since the displacement L'' correctly indicates the actual displacement Lact, when L''=Lmap, the opening degree of the exhaust gas recirculation valve 4 is set to the opening degree required according to the operating state.

In this embodiment, the correction is made based on the detected displacements L ₁ and L ₂ when the exhaust recirculation valve 4 is fully closed and fully open, but it is not limited to when the exhaust recirculation valve 4 is fully closed and when it is fully open, but it is also corrected based on two specific actual displacements. are detected as the first and second set displacements, and the displacement detected by the position sensor 9 at this time is
It may be corrected as L ₁ and L ₂ . However, in order to improve accuracy, it is desirable that the first and second set displacements be as far apart as possible.

In addition, in this embodiment, the valve body 4d of the exhaust recirculation valve 4
The fact that the displacement of This may be done indirectly by detecting when each displacement is output.

Further, the control circuit 6 shown in FIG. 3 may be constituted by a microcomputer that performs the operations shown in the flowchart of FIG. 4.

(Effects of the Invention) As described above, according to the present invention, in the engine exhaust recirculation control device or idle control device,
Even if the displacement detection means that detects and feeds back the displacement of the exhaust recirculation valve or throttle valve has an error from the predetermined standard characteristics due to installation error, wear, thermal expansion, or variations, the output characteristics of the detection means will be automatically corrected at both the zero point and the slope. As a result, exhaust gas recirculation control or idle control is always performed with high precision.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of the present invention.
2 to 5 show embodiments of the present invention.
3 is a block diagram showing the configuration of the control circuit, FIG. 4 is a flowchart showing the operation of the control circuit, and FIG. 5 is a graph for explaining the operation. A...Control member (4...Exhaust recirculation valve), B...Displacement detection means (9...Position sensor), C...Operating state detection means (7...Engine speed sensor, 8...Intake negative pressure sensor, 17...Operating state D... Main storage means (20... Data memory), E... Displacement difference calculation means (32... Comparison circuit), F... Displacement control means (5... Solenoid control valve), G... First setting displacement detection means (13... Fully closed switch), H... Second setting displacement detection means (14... Fully open switch), I... First storage means (24... First register), J... Second storage means (25
...second register), K...correction means (26...first correction circuit, 29...second correction circuit).

Claims (1)

[Claims] 1 A control member that controls the operating state of the engine,
main displacement detection means for detecting displacement of the control member;
operating state detection means for detecting the operating state of the engine; main memory means for storing in advance a required displacement of the control member according to the operating state; and the required displacement read from the main storage means and the main displacement. An engine comprising a displacement difference calculation means for calculating a difference between the detected displacement output from the detection means and a displacement control means for controlling the control member so as to reduce the displacement difference to zero in response to the output of the calculation means. The control device includes a first setting displacement detecting means and a second setting displacement detecting means for respectively detecting that the displacement of the control member becomes a first setting displacement and a second setting displacement.
a set displacement detecting means, and a first means for storing detected displacements outputted from the main displacement detecting means when these detecting means respectively detect the first and second set displacements;
It is characterized by comprising a storage means, a second storage means, and a correction means for correcting the detected displacement outputted from the main displacement detection means based on the stored values of the first and second storage means. Engine control device.