JP2922103B2 - Exhaust gas recirculation control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas recirculation control device using, for example, a stepper motor type EGR valve for recirculating exhaust gas of an internal combustion engine (hereinafter, referred to as EGR). The present invention relates to an exhaust gas recirculation control device that has improved reliability by preventing erroneous control due to changes over time or over time.

[0002]

2. Description of the Related Art Conventionally, in an internal combustion engine control device for an automobile engine or the like, for example, in order to reduce the combustion temperature of the internal combustion engine and suppress NOx components in the exhaust gas, a part of the exhaust gas is returned to the internal combustion engine. EGR control technology for reflux is well known. FIG. 16 is a configuration diagram schematically showing an entire system of a conventional exhaust gas recirculation control device.

In FIG. 1, reference numeral 1 denotes an internal combustion engine, ie, an engine; 2, an air cleaner for purifying intake air to the engine 1; 3, an intake pipe for supplying air through the air cleaner 2 to the engine 1; An intake manifold (hereinafter, referred to as an intake manifold) provided on the downstream side of the pipe 3, that is, on the intake side of the engine 1, 5 is an injector for injecting fuel into an intake manifold 4 of the intake pipe 3, and 7 is an intake pipe 3
, A throttle valve for detecting the opening θ of the throttle valve 7, and 9 a throttle valve for bypassing the upstream side and the downstream side of the throttle valve 7. This is a bypass air flow rate control means for controlling.

Reference numeral 10 denotes an EGR pipe for recirculating exhaust gas of the engine 1 to the intake pipe 3 side, and 11 denotes a stepper motor type EG for controlling a flow rate of the exhaust gas flowing through the EGR pipe 10.
This is an R valve. The EGR valve 11 controls the EGR flow so as to have a flow according to the operating state of the engine 1.
It constitutes a flow control means.

[0005] Reference numeral 12 denotes an air flow sensor for detecting the amount of air Qa taken into the intake pipe 3, which is, for example, of a vane type and measures a volume flow as the detected air amount Qa. Therefore, inside or outside of the airflow sensor 12,
Intake air temperature sensor and atmospheric pressure sensor (neither shown)
Is provided, and the mass air amount actually sucked into the engine 1 is measured.

Reference numeral 13 denotes an ignition coil for generating a high voltage for burning each cylinder of the engine 1;
An igniter 15 for energizing and cutting off the primary current 3 is an exhaust pipe 15 for discharging exhaust gas after combustion in the engine 1,
Reference numeral 6 denotes an exhaust gas purifying catalyst provided downstream of the exhaust pipe 15.

The ignition signal Q from the ignition coil 13 driven by the igniter 14 corresponds to the rotation speed of the engine 1, and also functions as a sensor signal indicating the rotation speed. Reference numeral 17 denotes a water temperature sensor for detecting the temperature T of the cooling water of the engine 1, and constitutes sensor means for providing operating state information of the engine 1 together with the throttle opening sensor 8 and the ignition coil 13. Reference numeral 20 denotes a battery serving as a power supply of the vehicle-mounted device, and 21 denotes a battery which is closed at the time of startup to
An ignition key switch for supplying the electric power to the in-vehicle device.

Reference numeral 22 denotes an electronic control unit composed of a computer system which is started by power supply from the battery 20. Operating state information (ie, throttle opening θ, intake air amount Qa, cooling water temperature T) from various sensor means is provided. , An ignition signal Q, etc.), a combustion injection amount calculating means for calculating a combustion injection amount and an EGR flow rate Qr according to the operating state information, an EGR flow rate calculating means, etc., and a combustion injection control signal J for the injector 5 and an EGR valve. 11 to output an EGR control signal Cr.

FIG. 17 shows the electronic control unit 2 shown in FIG.
2 is a block diagram showing a detailed configuration of FIG. In the figure, 1
00 is a microcomputer, and operating state information Q,
A CPU 200 for calculating a control signal J of the injector 5 and a control signal Cr of the EGR valve 11 according to a predetermined program based on Qa, θ and T, and a free running counter 20 for measuring the rotation cycle of the engine 1
1 and a timer 202 for counting time for various controls
A / which converts an analog input signal into a digital signal
D converter 203 and RA used as work memory
M205 and R in which various operation programs are stored.
An OM 206, an output port 207 for outputting each control signal J and Cr, and each of the elements 201-207
And a common bus 208 coupled to the common bus 200.

Reference numeral 101 denotes a first input interface circuit, which shapes the ignition signal Q on the primary side of the ignition coil 13 into an interrupt signal and inputs it to the microcomputer 100. When this interrupt signal is generated, the CPU 200 in the microcomputer 100
And the rotation cycle of the engine 1 is calculated from the difference between the current read value and the previous read value to calculate R
It is stored in the AM 205.

Reference numeral 102 denotes a second input interface circuit, which comprises a throttle opening sensor 8, an air flow sensor 12
And the respective sensor signals θ, Qa and T from the water temperature sensor 17 and the like, and input them to the A / D converter 203. 1
Reference numeral 04 denotes an output interface circuit, and output port 2
07, the control signals J and Cr are amplified and output to the injector 5 and the EGR valve 11.

FIG. 18 is a side sectional view showing the structure of the EGR valve 11. A unipolar type 30 is mounted on the upper part of the valve body of the EGR valve 11 and can control the EGR valve 11 in 48 steps from fully closed to fully open. Stepper motor, 31
Is a motor shaft rotated and driven by the stepper motor 30,
Reference numeral 32 denotes a feed screw that is driven up and down by rotating in conjunction with the motor shaft 31, reference numeral 33 denotes a valve shaft that is driven vertically by the feed screw 32 to adjust the passage area of the EGR valve 11, and reference numeral 34 denotes a valve shaft 33. A compression coil spring 35 for urging in the upward (opening) direction is provided between the motor shaft 31 of the stepper motor 30 and the valve shaft 32, and is a feed screw for converting the rotational movement of the motor shaft 31 into the vertical movement of the valve shaft 33. 32.

FIG. 19 shows the pressure between the inlet and the outlet of the EGR valve 11 .
FIG. 7 is a characteristic diagram showing a relationship between the flow rate [liter / minute] of the EGR valve 11 and the number of steps of the stepper motor 30 when the force difference ΔP is set to 200 mmHg, in which the horizontal axis represents the number of steps of the stepper motor 30 and the vertical axis represents EGR. Indicates the flow rate. FIG.
In the flow rate characteristics described above, when the number of steps of the stepper motor 30 is “0”, the EGR valve 11 is fully closed, and when the number of steps of the stepper motor 30 is “48”, the EGR valve 11 is fully opened.

[0014]

FIGS. 20 and 21 are flow charts showing the operation of the CPU 200 of the conventional exhaust gas recirculation control device. FIG. 20 shows the processing of the main routine, and FIG.
3 shows a control processing routine. Next, the operation of the conventional exhaust gas recirculation control device shown in FIGS. 16 to 18 will be described with reference to FIGS.

First, in another control processing step S1 in the main routine, processing such as calculation of the engine speed Ne based on the ignition signal Q, reading of a sensor signal from the A / D converter 203, and fuel control are performed. Will be When this control processing step S1 ends, subsequently, an EGR control processing step S2 is performed, and the process returns to step S1. The control of the engine 1 is performed by the control processing steps S1 and S2 described above.

EGR control processing step S2 in FIG.
Is specifically executed as shown in FIG. First, in step S601, another control processing routine S
The engine speed Ne and the intake air amount Qa which have been processed in step 1 are read. Subsequently, in step S602, the read engine speed Ne and intake air amount Q
A predetermined target stepper motor opening (number of steps) is calculated based on a.

Subsequently, in order to carry out a correction based on the engine warm-up state of the engine 1, in step S603, the water temperature T processed in another processing routine S1 is read. Next, in step S604, according to the water temperature T, S6
The target stepper motor opening obtained in 02 is corrected so as to decrease as the water temperature T decreases.

Finally, in step S605, the stepper motor 30 is driven to have the target stepper motor opening calculated and corrected in steps S602 and S604, and the process returns. Processing steps S601 to S601
The control of the EGR flow rate Qr is performed by S605.

Next, a specific operation of the stepper motor 30 will be described with reference to FIGS. FIGS. 22A and 22B are explanatory diagrams showing a relative relationship of each phase of the stepper motor 30 that drives the EGR valve 11 and a connection relationship between the stepper motor 30 and the electronic control unit 22. FIGS. 23A and 23B are explanatory diagrams showing a drive pattern and a rotation direction of the stepper motor 30 by the two-phase excitation method.

As shown in FIG. 22, the windings of the coils A and B are biphasic windings having a positive common of the battery 20. When one of the coils is excited on the same coil, the direction of the other magnetic flux is reversed. It is configured to be.

The stepper motor 30 constructed as described above
Is driven by the two-phase excitation method shown in FIG. 23, at the step position “0”, it is indicated by the number in the circle of FIG. 22 (1).
The (2) -phase stators (hatched portions in FIG. 22A) are excited. Therefore, as shown in FIG.
The magnetic pole (N, S) distribution shown in FIG.
The S pole of the rotor is positioned at a step position “0” corresponding to the center of the N pole synthesized by the (1) and (2) phases.

At the step position "1", the coil A
Are reversed, and the excitation of the phase (1) is released and the phase (3) is excited, so that the S pole of the rotor has the phases (2) and () as indicated by the arrows shown in FIG. 3) Move to the step position "1" corresponding to the center of the N pole synthesized by the phases.

At the step position "2", the coil B
Are reversed, and the excitation of the phase (2) is released and the phase (4) is excited, so that the S pole of the rotor further moves to the step position “2”. Thereafter, the phase is excited while being shifted by two phases, and a similar pattern is applied to generate a rotating magnetic field. The step movement is repeated, and the motor shaft 31 rotates counterclockwise as shown in FIG. FIG.
When the pattern is changed in the direction opposite to 3 (a), the rotation direction of the motor shaft 31 is reversed (clockwise).

Using the above method, a predetermined time interval τ (100 ms, 100 PPS [pulse /
By controlling the respective coils of the stepper motor 30 in seconds), the control of the valve opening degree α (corresponding to the flow rate Qr) of the EGR valve 11 can be performed.

Although the stepper motor type EGR valve 11 is used as an actuator for controlling the EGR amount here, a vacuum motor type EGR valve may be used. In this case, if a position sensor for detecting the EGR valve opening α is further provided, it is possible to control the EGR valve opening α to control the EGR flow rate Qr as described above.

However, since the opening degree α of the EGR valve is controlled, EGR valve 11 is subject to variations due to manufacturing variations and changes over time.
When the GR valve 11 becomes clogged or the like, an error ΔQr occurs in the relationship between the EGR valve opening α and the EGR flow rate Qr as shown in FIG. 24, and the exhaust gas emission amount may increase. In FIG. 24, the solid line is the characteristic of a regular product, the dashed line is the characteristic of a valve clogged product due to aging, and the dashed line is the upper and lower limit characteristics of manufacturing variations.

When a variation ΔQr in the EGR flow characteristic as shown in FIG. 24 occurs, an accurate EG is obtained only with the EGR valve opening α.
The R flow rate Qr cannot be obtained, and in particular, it becomes impossible to cope with the stricter exhaust gas regulation values seen in recent years in California, USA. Similarly, EG also depends on variations in the engine 1 and other parts.
An error occurs in the R flow rate Qr.

Further, in the case of an EGR control device provided with a vaporized gas recovery system (not shown), the vaporized gas recovery system operates independently of the EGR control.
It is possible that the control and the evaporative gas recovery system operate simultaneously. In this case, the intake pipe pressure Pm changes due to the influence of the operation of the vaporized gas recovery system, and it becomes impossible to calculate an accurate EGR flow rate Qr.

[0030]

The conventional exhaust gas recirculation control device is constructed as described above, and controls the EGR flow rate Qr by the EGR valve opening α according to the operating condition. E due to manufacturing variations and aging
When the GR valve is clogged, as shown in FIG.
There is a problem that an error occurs in the relationship between the R valve opening α and the EGR flow rate Qr, and the exhaust gas emission increases.

There is also a problem that the EGR flow rate Qr similarly causes an error due to the variation of the engine 1 and other parts, thereby increasing the amount of exhaust gas emission.

Further, when a vaporized gas recovery system is provided, and the vaporized gas recovery system operates simultaneously with the EGR control, the intake pipe pressure Pm changes due to the influence of the operation of the vaporized gas recovery system, and accurate EGR is performed. The flow rate Qr cannot be calculated, and there is a problem that an error occurs in the EGR flow rate Qr and the exhaust gas emission increases.

The first aspect of the present invention has been made to solve the above-described problems. An exhaust gas recirculation control device capable of accurately controlling the EGR flow rate regardless of the characteristic variation of the EGR valve is provided. The purpose is to gain.

A second object of the present invention is to provide an exhaust gas recirculation control device capable of more accurately controlling the EGR flow rate.

A third object of the present invention is to provide an exhaust gas recirculation control device in which the atmospheric pressure sensor can be omitted.

A fourth object of the present invention is to provide an exhaust gas recirculation control device in which the reliability of EGR flow control is improved without increasing the cost by omitting an intake pipe pressure sensor. I do.

A fifth aspect of the present invention is to correct the intake pipe pressure calculated by the fourth aspect of the present invention and to compensate for errors due to variations in the engine and other parts, thereby further improving the reliability of the EGR flow control. It is an object of the present invention to obtain an exhaust gas recirculation control device with improved characteristics.

Another object of the present invention is to provide an exhaust gas recirculation control device in which the reliability of EGR flow control is improved without increasing the cost by omitting an air flow sensor.

According to a seventh aspect of the present invention, the EGR flow control is further improved by correcting the intake air amount calculated by the sixth aspect and compensating for errors caused by variations in the engine and other parts. It is an object of the present invention to obtain an exhaust gas recirculation control device with improved characteristics.

Another object of the present invention is to provide an exhaust gas recirculation control device in which the atmospheric pressure sensor can be omitted.

Further, according to the ninth and the first aspects of the present invention,
0 is to prevent the change in the intake pipe pressure due to the operation of the vaporized gas recovery system, eliminate the influence of the vaporized gas recovery system, and obtain an exhaust gas recirculation control device with further improved EGR flow rate control. Aim.

[0042]

An exhaust gas recirculation control device according to a first aspect of the present invention controls an EGR pipe for recirculating exhaust gas of an internal combustion engine to an intake pipe, and controls an EGR flow rate of the exhaust gas flowing in the EGR pipe. An EGR valve, a sensor means for detecting an operation state of the internal combustion engine, and an EGR flow control means for controlling the EGR valve in accordance with the operation state information from the sensor means. In the exhaust gas recirculation control device for recirculating to the internal combustion engine, the sensor means includes: an air flow sensor for detecting an amount of intake air to the intake pipe; an intake pipe pressure sensor for detecting a pressure in the intake pipe;
A target EGR rate calculating means for calculating a target EGR rate in accordance with the operating state information, and an intake air amount, an intake pipe pressure, and an EGR pressure sensor for detecting an EGR pressure sensor for detecting a pressure in the EGR pipe.
Actual EGR that calculates the actual EGR rate based on the GR pressure
And an EGR flow rate calculating means including a rate calculating means.
The flow rate control means changes the EGR valve passage area so that the EGR rate matches the target EGR rate.
It controls the flow rate.

The exhaust gas recirculation control device according to a second aspect of the present invention is the exhaust gas recirculation control device according to the first aspect, wherein the orifice is provided in the EGR pipe downstream of the installation position of the EGR pressure sensor.

Further, the exhaust gas recirculation control device according to claim 3 of the present invention is characterized in that, according to claim 1 or 2, the exhaust gas recirculation control device is based on the intake pipe pressure when the internal combustion engine is stopped or the intake pipe is fully opened. Atmospheric pressure detecting means for obtaining atmospheric pressure is provided.

An exhaust gas recirculation control device according to a fourth aspect of the present invention includes an EGR pipe for recirculating exhaust gas of the internal combustion engine to an intake pipe, and an EGR pipe for exhaust gas flowing in the EGR pipe.
An EGR valve for controlling the flow rate, a sensor means for detecting an operation state of the internal combustion engine, and an EGR flow control means for controlling the EGR valve in accordance with the operation state information from the sensor means; In an exhaust gas recirculation control device for recirculating a part of the exhaust gas to the internal combustion engine, the sensor means includes an air flow sensor for detecting the amount of air taken into the intake pipe,
An EGR pressure sensor for detecting a pressure in the GR pipe,
Intake pipe pressure calculating means for calculating the pressure in the intake pipe based on the rotational speed and the intake air amount of the internal combustion engine; target EGR rate calculating means for calculating a target EGR rate in accordance with the operating state information; An actual EGR rate calculating means for calculating an actual EGR rate based on the pipe pressure and the EGR pressure; and an EGR flow rate controlling means,
By changing the passage area of the EGR valve, the EGR flow is controlled so that the EGR rate matches the target EGR rate.

According to a fifth aspect of the present invention, there is provided an exhaust gas recirculation control device according to the fourth aspect, further comprising means for determining a steady operation state of the internal combustion engine, and forcing the EGR flow rate when the steady operation state is determined. EGR control prohibiting means for setting the EGR pressure to zero, an EGR pressure deviation calculating means for calculating a difference between the EGR pressure in the EGR control in the steady operation state and the EGR pressure in the EGR control prohibiting state, and an intake pipe based on the EGR pressure deviation. And an intake pipe pressure correcting means for correcting the pressure.

According to a sixth aspect of the present invention, there is provided an exhaust gas recirculation control device for recirculating exhaust gas of an internal combustion engine to an intake pipe, and for controlling EGR of exhaust gas flowing through the EGR pipe.
An EGR valve for controlling the flow rate, a sensor means for detecting an operation state of the internal combustion engine, and an EGR flow control means for controlling the EGR valve in accordance with the operation state information from the sensor means; In the exhaust gas recirculation control device for recirculating a part of the internal combustion engine, the sensor means includes an intake pipe pressure sensor for detecting a pressure in the intake pipe, and an EGR pressure sensor for detecting a pressure in the EGR pipe. Intake air amount calculation means for calculating the intake air amount to the intake pipe based on the rotational speed and the intake pipe pressure; target EGR rate calculation means for calculating the target EGR rate in accordance with the operating state information; An actual EGR rate calculating means for calculating an actual EGR rate based on the pipe pressure and the EGR pressure; and an EGR flow rate controlling means,
By changing the passage area of the EGR valve, the EGR flow is controlled so that the EGR rate matches the target EGR rate.

According to a seventh aspect of the present invention, in the exhaust gas recirculation control device according to the sixth aspect, a means for determining a steady operation state of the internal combustion engine, and a forced EGR flow rate when the steady operation state is determined. EGR control prohibiting means for setting the EGR pressure to zero, EGR pressure deviation calculating means for calculating a difference between the EGR pressure during the EGR control in the steady operation state and the EGR pressure in the EGR control prohibited state, and intake air based on the EGR pressure deviation. Intake air amount correcting means for correcting the amount.

The exhaust gas recirculation control device according to claim 8 of the present invention is characterized in that, according to claim 6 or claim 7, the exhaust gas recirculation control device is based on the intake pipe pressure when the internal combustion engine is stopped or the intake pipe is fully opened. Atmospheric pressure detecting means for obtaining atmospheric pressure is provided.

According to a ninth aspect of the present invention, there is provided the exhaust gas recirculation control device according to any one of the first to eighth aspects, wherein the vaporized gas is recovered for recovering the vaporized gas from the fuel tank to the internal combustion engine. Means, a vaporized gas introduction amount detecting means for detecting an introduced amount of vaporized gas, and an EGR flow rate correcting means for correcting an EGR flow rate according to the vaporized gas introduction amount.

According to a ninth aspect of the present invention, there is provided the exhaust gas recirculation control device according to any one of the first to eighth aspects, wherein the vaporized gas is recovered for recovering the vaporized gas from the fuel tank to the internal combustion engine. Means and a vaporized gas recovery inhibiting means for inhibiting the operation of the vaporized gas recovery means during execution of the EGR control.

[0052]

According to the first aspect of the present invention, the operating state, the intake air amount, the intake pipe pressure and the EGR pressure are detected, and the target EGR rate and the actual EGR rate are calculated from the operating state, the intake pipe pressure and the EGR pressure according to a predetermined formula. Is estimated and calculated based on the intake air amount, the target EGR rate and the actual EGR rate.
Control the R valve opening. Thereby, the EGR flow rate is accurately controlled to reduce the exhaust gas emission amount.

According to a second aspect of the present invention, the orifice makes the pressure difference between the EGR pressure and the intake pipe pressure remarkable, and detects the operating state, the intake air amount, the intake pipe pressure and the EGR pressure, and performs the operation. The target EGR rate and the actual EGR rate are estimated and calculated from the state, the intake pipe pressure, and the EGR pressure according to a predetermined calculation formula, and the EGR valve opening is controlled based on the intake air amount, the target EGR rate, and the actual EGR rate.
Thereby, the EGR flow rate is accurately controlled to reduce the exhaust gas emission amount.

According to a third aspect of the present invention, the operating state, the intake air amount, the intake pipe pressure and the EGR pressure are detected, and the atmospheric pressure is estimated and detected from the intake pipe pressure in the stop operation state or when the intake pipe is fully opened. At the same time, the target EG is calculated from the operating state, the intake pipe pressure and the EGR pressure according to a predetermined calculation formula.
The R rate and the actual EGR rate are estimated and calculated, and the EGR valve opening is controlled based on the intake air amount, the target EGR rate, and the actual EGR rate. This makes it possible to reduce costs by eliminating the need for an atmospheric pressure sensor, and to control the EGR flow rate accurately to reduce exhaust gas emissions.

According to a fourth aspect of the present invention, the operating state, the intake air amount and the EGR pressure are detected, and the intake pipe pressure, the target EGR rate, the actual EGR rate and the atmospheric pressure are estimated and calculated according to a predetermined calculation formula. The EGR valve opening is controlled based on the intake air amount, the target EGR rate, and the actual EGR rate, and the exhaust gas emission is reduced by accurately controlling the EGR flow rate. Further, cost reduction is realized by eliminating the need for an intake pipe pressure sensor.

According to a fifth aspect of the present invention, the operating state, the intake air amount and the EGR pressure are detected, and the intake pipe pressure, the target EGR rate, the actual EGR rate and the atmospheric pressure are estimated and calculated according to a predetermined calculation formula. The EGR valve opening is controlled based on the intake air amount, the target EGR rate, and the actual EGR rate to accurately control the EGR flow rate. As a result, the exhaust gas emission amount is reduced, and the cost is reduced by eliminating the need for an intake pipe pressure sensor. In addition, EG in a predetermined operation state
The calculated intake air amount is corrected based on the EGR passage pressure deviation with or without R to compensate for variations in components such as the engine and the EGR valve.

According to a sixth aspect of the present invention, the operating state, the intake pipe pressure and the EGR pressure are detected, and the intake air amount, the target EGR rate, the actual EGR rate and the atmospheric pressure are estimated and calculated according to a predetermined formula. The EGR valve opening is controlled based on the intake air amount, the target EGR rate, and the actual EGR rate, and the exhaust gas emission is reduced by accurately controlling the EGR flow rate. Further, cost reduction is realized by eliminating the need for an airflow sensor.

According to a seventh aspect of the present invention, the operating state, the intake pipe pressure and the EGR pressure are detected, and the intake air amount, the target EGR rate, the actual EGR rate and the atmospheric pressure are estimated and calculated according to a predetermined formula. The EGR valve opening is controlled based on the intake air amount, the target EGR rate, and the actual EGR rate to accurately control the EGR flow rate. As a result, the amount of exhaust gas emission is reduced, and the cost is reduced by eliminating the need for an air flow sensor. In addition, EG in a predetermined operation state
The calculated intake air amount is corrected based on the EGR passage pressure deviation with or without R to compensate for variations in components such as the engine and the EGR valve.

Further, in claim 8 of the present invention, the operating state, the intake pipe pressure and the EGR pressure are detected, and the atmospheric pressure is estimated and detected from the stopped operating state or the intake pipe pressure in the fully opened state. The intake air amount, the target EGR rate and the actual EGR rate are estimated and calculated from the intake pipe pressure and the EGR pressure in accordance with a predetermined calculation formula, and the intake air amount and the target EGR are calculated.
The EGR valve opening is controlled based on the rate and the actual EGR rate. As a result, the amount of exhaust gas is reduced by accurately controlling the EGR flow rate, and the cost is reduced by eliminating the need for an air flow sensor and an atmospheric pressure sensor.

In the ninth aspect of the present invention, the vaporized gas introduction amount is calculated and the EGR flow rate is corrected based on the vaporized gas introduction amount to eliminate the influence of the vaporized gas recovery system.

According to a tenth aspect of the present invention,
At the time of EGR control, the influence of the vaporized gas recovery system is eliminated by prohibiting the operation of the vaporized gas recovery system.

[0062]

【Example】

Embodiment 1 FIG. Hereinafter, a first embodiment (corresponding to claims 1 to 3) of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram schematically showing an entire system according to a first embodiment of the present invention, FIG. 2 is a block diagram showing details of an electronic control unit 22 in FIG. 1, and FIG. 3 is a diagram showing an EGR pipe 10 in FIG. It is an expanded sectional view which shows a peripheral part, In each figure, 1-5, 7-17, 20-20
22, 100 to 105 and 200 to 208 are the same as described above. In this case, the function of the EGR flow control means in the electronic control unit 22 is different from that described above. Also, E
The specific structure and driving method of the GR valve 11 are as shown in FIGS. 18, 19, 22 and 23. Reference numeral 6 denotes an intake pipe pressure sensor for detecting an intake pipe pressure Pm of an intake manifold in the intake pipe 3, and reference numeral 18 denotes an EGR pressure Pr in the EGR pipe 10.
, And the intake pipe pressure Pm and the EGR pressure Pr are input to the electronic control unit 22.

Reference numeral 19 denotes an orifice provided in the EGR pipe 10 so that a pressure difference is easily generated between both ends of the EGR pipe 10. The orifice 19 is located downstream of the EGR pressure sensor 18, that is, at a position closer to the intake pipe 3. Is provided. Reference numeral 23 denotes an alarm lamp that is turned on in response to an alarm signal F from the electronic control unit 22.

In FIG. 3, Pa is an atmospheric pressure for calculating an intake air amount Qa as a mass in the intake pipe 3,
Pex is the exhaust pressure in the exhaust pipe 15. In addition, even if the orifice 19 is not provided, the orifice 19 can be omitted because a pressure difference exists in the EGR pipe 10.

The electronic control unit 22 calculates a target EGR flow rate calculating means Qo for calculating a target EGR flow rate Qo according to operating state information from various sensor means including the intake pipe pressure sensor 6, the air flow sensor 12, the EGR pressure sensor 18, and the like. And EGR flow control means for controlling the EGR valve 11 so that the EGR flow rate Qr matches the target EGR flow rate Qo, and when the internal combustion engine is stopped or the intake pipe 3 is fully opened (the throttle valve 7 is fully opened). Atmospheric pressure detecting means for obtaining the atmospheric pressure Pa based on the intake pipe pressure Pm is provided.
In the first embodiment, the target EGR flow rate calculating means is realized as a means for determining the number of steps of the stepping motor.

The EGR in the electronic control unit 22
The flow rate calculating means calculates the target EGR rate β according to the operating state information.
target EGR rate calculating means for calculating the value o, and the intake air amount Q
a actual EGR rate calculating means for calculating an actual EGR rate βr based on the intake pipe pressure Pm and the EGR pressure Pr, and the EGR flow control means changes the passage area of the EGR valve 11 to change the EGR rate. βr is the target EGR rate βo
The control of the EGR flow rate Qr is performed so as to coincide with.

The EGR rate βr is an EGR flow rate Qr with respect to a new intake air amount Qa, and is a value represented by a relational expression (Qr / Qa) described later. The target EGR rate βo is a value that is set in advance according to various operating conditions (operating state information).

Next, the first embodiment of the present invention shown in FIGS. 1 to 3 will be described with reference to the flowcharts of FIGS.
Will be described. When the EGR control process (step S2) is executed by the main routine of FIG. 20, the EGR control process routine of FIG. 4 is executed as follows.

First, in step S131, the engine speed Ne, the intake air amount Qa, the water temperature T, and the like are read based on various sensor input signals.
32, a predetermined target stepper motor opening degree αo and a target EGR rate β are determined based on the read information.
Read out o. These steps S131 and S13
2 corresponds to steps S601 to S604 described above (FIG. 21) except that the target EGR rate βo is read.

Here, if there is no variation in the engine 1 and the EGR valve 11, the target stepper motor opening α
If the EGR valve 11 is opened at o, the target EGR rate βo is obtained. Next, in order to control the EGR rate βr, step S1
At step 33, the intake pipe pressure Pm and the EGR pressure Pr are read, and then at step S134, the following equation (1) (Bernoulli equation) is calculated to obtain the EG.
Calculate the R flow rate Qr.

Qr = Kr · Ar · {2g · (Pr / RTr) · (Pr−Pm)} (1)

In the equation (1), Kr is the flow coefficient of the orifice 19, Ar is the passage area of the orifice 19 or the area of the EGR pipe 10 (when there is no orifice), g
Is the gravitational acceleration, R is the gas constant, Tr is the gas temperature upstream of the orifice 19, Pr is the EGR pressure detected by the EGR pressure sensor 18, Pm is the intake pipe pressure detected by the intake pipe pressure sensor 6, and the flow rate The coefficient Kr, the passage area Ar, the gravitational acceleration g, and the gas constant R are constants.

In the equation (1), (Pr / RT
r) is a value related to the gas density, and is less affected by changes in the gas temperature Tr and the exhaust pressure Pex on the upstream side of the EGR pipe 10 (each about 10 ppm with respect to the change range of the gas temperature Tr and the exhaust pressure Pex). ), It can be regarded as almost a constant. So, in practice,
The expression (1) is modified and simplified as in the following expression (2), and is a calculation target.

Qr {K} (Pr-Pm) (2)

However, in the equation (2), K = Kr · Ar
A coefficient corresponding to {2g · (Pr / RTr)}. As is clear from equation (2), the EGR flow rate Qr is
It is determined from the EGR pressure Pr and the intake pipe pressure Pm.

Next, in step S135, the actual EGR rate βr is calculated. At this time, the EGR rate βr is
EGR flow rate Qr and intake air amount Q equivalent to new intake mass
Using “a”, it can be calculated as follows.

Βr = Qr / Qa

Therefore, by substituting equation (2), EG
The R rate βr is represented by the following equation (3).

Βr = (K / Qa) √ (Pr−Pm) (3)

As described above, steps S131 to S135
Thus, the EGR flow rate Qr can be obtained from the EGR pressure Pr and the intake pipe pressure Pm. Therefore, when the intake pipe pressure sensor 6, the air flow sensor 12, and the EGR pressure sensor 18 are provided, the intake air amount Qa,
Using the EGR pressure Pr and the intake pipe pressure Pm, the EGR pressure
The rate βr can be accurately detected.

As described above, the target EGR rate βo and the actual E
After the GR rate βr is obtained, in step S136, a deviation Δβ between the target EGR rate βo and the actual EGR rate βr is calculated, and it is determined whether or not both coincide with each other based on whether or not the EGR rate deviation Δβ = 0. .

If it is determined that βo = βr (that is, YES), the actual EGR rate βr matches the target EGR rate, so that in step S137, the EGR valve 11
Of the stepper motor is stopped, and the stepper motor opening α
Hold. On the other hand, if it is determined that the actual EGR rate βr does not match the target EGR rate (that is, NO), the process proceeds to step S138, and E calculated in step S136.
The stepper motor opening α of the EGR valve 11 is changed according to the GR ratio deviation Δβ.

From the above processing, the target EGR rate βo and the actual E
Control can be performed so that the GR rate βr matches, and the EGR rate βr can be controlled according to the operating state. Further, the electronic control unit 22 detects the atmospheric pressure Pa using the intake pipe pressure Pm from the intake pipe pressure sensor 6 according to the processing routine of FIG.

First, in step S141, it is determined from the engine rotation information whether the operating state is the engine stall state. If it is determined that the engine is in the engine stall state (ie, YES), the intake pipe pressure Pm at this time is equal to the atmospheric pressure Pa.
Therefore, at step S142, the intake pipe pressure Pm is taken as the atmospheric pressure Pa, and at step S14
Proceed to 3.

On the other hand, the engine is not in the engine stall state (that is, N
If it is determined as O), the process immediately proceeds to step S143,
From the information from the throttle opening sensor 8, it is determined whether or not the throttle opening θ is equal to or greater than a predetermined value indicating full opening.

If the throttle opening .theta. Is equal to or larger than a predetermined value and the throttle valve 7 is fully opened (that is, YE
S) (when the throttle opening θ is equal to or more than a predetermined value as full open), the intake pipe pressure Pm at this time is determined.
Indicates a pressure reduced by the intake system pressure loss γ from the atmospheric pressure Pa, the flow proceeds to step S144, the loss γ is added to the intake pipe pressure Pm, the pressure is taken as the atmospheric pressure Pa, and the process returns.

On the other hand, the throttle opening .theta. Is smaller than the predetermined value, and the throttle valve 7 is not fully opened (that is, N
If it is determined as O), the process skips step S144 and returns.

The above processing (steps S141 to S14)
4), the intake pipe pressure sensor 6 provided in the intake pipe 3
Can be used to detect the atmospheric pressure Pa, so that there is no need for an atmospheric pressure sensor for converting the intake air amount information Qa from the air flow sensor 12 for measuring the volume flow rate into a mass flow rate. Therefore, without increasing costs,
Accurate EGR control can be realized.

In the device of the present invention, the EGR flow rate Q
Although the stepper motor type EGR valve 11 is used as an actuator for controlling r, if a vacuum motor type EGR valve is used and a position sensor for detecting the EGR valve opening α is provided as described above, Similarly to the present invention, the EGR flow rate Qr can be controlled by controlling the EGR valve opening α.

Embodiment 2 FIG. In the first embodiment, two intake pipe pressure sensors 6 and 18 need to be provided to detect the intake pipe pressure Pm and the EGR pressure Pr.
Sufficient cost reduction cannot be realized. Therefore, the intake pipe pressure Pm may be obtained by calculation without using the intake pipe pressure sensor 6.

FIG. 6 is a block diagram showing the entire system of a second embodiment (corresponding to claim 4) of the present invention in which the intake pipe pressure sensor 6 is omitted, and FIG. 7 is a detailed configuration of the electronic control unit 22 in FIG. FIG. 2 is a block diagram showing
5, 7 to 23, 100 to 105 and 200 to 208 are the same as described above. In this case, the electronic control unit 22 includes a calculation unit for calculating the intake pipe pressure Pm.

Next, the operation of the second embodiment of the present invention shown in FIGS. 6 and 7 will be described with reference to the flowchart of FIG. In FIG. 8, S131, S132
And S134 to S138 are the same steps as those described above, and S133a and S133b are steps S1
33. In the main routine of FIG. 20, when the EGR control step S2 is executed, E in FIG.
The execution of the GR control routine is started.

First, in step S131, the engine speed Ne, the intake air amount Qa, and the water temperature T are read, and in step S132, the target stepper motor opening α and the target EGR rate βo are read based on the read information.
In order to control the EGR rate βr, in step S133a, the intake pipe pressure Pm is calculated as follows. That is, the intake pipe pressure Pm is expressed by the following equation (4) from the theoretical equation.

Pm = {(Qa + Qr) 2R · Tm} / (Vc · Ne · ηv) (4)

However, in the equation (4), Tm is the intake pipe 3
, Vc is the cylinder volume of the engine 1, Ne is the engine speed, and ηv is the volume efficiency. Here, if the actual target EGR rate βo corresponding to each operating point is determined according to the operating state, the target EGR rate βo is expressed by the following equation (5) from βr = βo.

Βo = Qr / Qa (5)

By substituting equation (5) into equation (4), the intake pipe pressure Pm is expressed by the following equation (6).

Pm = (Qa / Ne) (1-βo) 2R · Tm / (Vc · ηv) (6)

Here, based on the load (Qa / Ne) and the engine speed Ne, the target EGR rate βo, the intake pipe temperature Tm, and the volumetric efficiency ηv can be set in advance. Qa / Ne) and the function f of the engine speed Ne can be expressed by the following equation (7).

Pm = f ｛(Qa / Ne), Ne｝ · (Qa / Ne) (7)

Next, at step S133b, the EGR
The pressure Pr is read, and the following steps S134 to S134 are performed.
Step S138 is executed. That is, in step S134, the calculation of equation (2) is performed, the EGR flow rate Qr is calculated, in step S135, the calculation of equation (3) is performed, the actual EGR rate βr is calculated, and in step S136, the target EGR rate is calculated. It is determined whether βo and the actual EGR rate βr match, and if they do match, the stepper motor drive is stopped in step S137, and if they do not match, in step S138 the stepper motor is driven according to the EGR rate deviation Δβ. Change the opening degree α.

From the above processing, similarly to the first embodiment, the control is performed so that the target EGR rate βo and the actual EGR rate βr match, and it is possible to control the EGR rate βr according to the operating state. Become. Therefore, accurate EGR control can be realized without increasing the cost.

Embodiment 3 FIG. Conventionally, there is a device that performs fuel injection control using the intake pipe pressure sensor 6, but when the first embodiment of the present invention is applied, it is necessary to add the air flow sensor 12 and the EGR pressure sensor 18. Therefore, the cost is increased. Therefore, the air flow sensor 12 may be omitted, and the intake air amount Qa may be calculated based on the operating state and the intake pipe pressure Pm.

FIG. 9 is a block diagram showing the entire system of the third embodiment (corresponding to claim 6) of the present invention in which the air flow sensor 12 is omitted, and FIG. 10 is an electronic control unit 22 shown in FIG.
FIG. 2 is a block diagram showing a detailed configuration of FIG.
-11, 13-23, 100-105 and 200-2
08 is the same as described above. In this case, the electronic control unit 22 includes a calculation unit for calculating the intake air amount Qa.

Next, the operation of the third embodiment of the present invention will be described with reference to the flowchart of FIG. In FIG. 11, S131 to S138 are the same steps as described above, and S200 is a step for calculating the intake air amount Qa without using the airflow sensor 12. As described above, when the EGR control step S2 is executed in the main routine of FIG. 20, the execution of the EGR control routine of FIG. 11 is started.

First, in step S131, the engine speed Ne, the intake pipe pressure Pm, and the water temperature T are read, and in step S132, the target stepper motor opening α and the target EGR rate βo are read based on the read information. Here, if there is no variation between the engine 1 and the EGR valve 11, the target EGR rate βo can be obtained by opening the EGR valve 11 at the target stepper motor opening αo.

Next, at step S133, E is further added.
After reading the GR pressure Pr and calculating the EGR flow rate Qr from the calculation of the above equation (2) in step S134,
In order to control the EGR rate βr, in step S200, the intake air amount Qa is calculated as follows. First, the total intake air amount Qm in the intake pipe 3 (= Qa + Qr)
Is expressed by the following equation (8) from the theoretical equation.

Qm = {Vc · Ne · ηv / (2R · Tm)} × Pm (8)

In the equation (8), Vc is a cylinder capacity, Ne is an engine speed, ηv is a volume efficiency, R is a gas constant, Tm is an intake pipe temperature, and Pm is an intake pipe pressure. Further, the volume efficiency ηv is calculated by using a function f of the intake pipe pressure Pm, the engine speed Ne, and the target EGR rate βo.
It is expressed by the following equation (9).

Ηv = f (Pm, Ne, βo) (9)

In the equation (9), the actual target EG
When the R rate βo is determined according to the operating state, the volumetric efficiency ηv
Is a function of the intake pipe pressure Pm and the engine speed Ne, and is expressed by the following equation (10).

Ηv = f (Pm, Ne) (10)

From equations (8) and (10), the total intake air amount Qm is expressed by the following equation (11).

Qm = Kp · f (Pm, Ne) · Ne · Pm (11)

However, in equation (11), Kp is a constant and is expressed as follows.

Kp = Vc / (2R · Tm)

Therefore, the intake air amount Qa is expressed by the following equation (12).

Qa = Qm−Qr = Kp · f (Pm, Ne) · Ne · Pm−Qr (12)

Subsequently, in step S135, the actual EGR rate βr is calculated from the above equation (3), and in step S13
In 6, the deviation Δβ between the target EGR rate βo and the actual EGR rate βr obtained in steps S132 and S135 is calculated, and it is determined whether or not the two coincide.

Then, if the target EGR rate βo and the actual EGR
If the rate βr matches, the actual EGR rate βr becomes the target EG
Since the R rate βo, the stepper motor drive is stopped to maintain the stepper motor opening α, and if they do not match, the process proceeds to step S138, and the stepper motor is driven according to the EGR rate deviation Δβ calculated in step S136. Change the motor opening α.

As a result, the target EGR rate βo and the actual EGR
The EGR rate βr can be controlled so as to be equal to the rate βr, and the EGR rate βr can be controlled according to the operating state. With the above configuration and processing, cost increase is suppressed and accurate E
GR control can be performed.

Embodiment 4 FIG. In the third embodiment, since the intake pipe pressure sensor 6 is provided, the intake pipe when the engine 1 is stopped or the intake pipe is fully opened, as in the first embodiment. By estimating and detecting the atmospheric pressure based on the pressure Pm, the atmospheric pressure sensor can be omitted.

Embodiment 5 FIG. In addition, the above-mentioned Examples 2 to 4
Then, in order to reduce the cost by omitting the sensor, the EGR control is performed by calculating the intake pipe pressure Pm and the intake air amount Qa by predetermined arithmetic expressions, that is, expressions (7) and (12), respectively. If there is a variation in parts such as the engine 1 and the EGR valve 11, an error occurs in the intake pipe pressure Pm and the intake air amount Qa obtained from the above arithmetic expression, and eventually an error occurs in the EGR control. .

Therefore, it is desirable to compensate for the above-mentioned EGR control error due to variations in parts such as the engine 1 and the EGR valve 11. FIG. 12 shows a fifth embodiment of the present invention in which a control error due to component variation can be compensated for by offset compensation.
It is a flowchart which shows the compensation processing routine (corresponding to Claim 5 and Claim 7).

In this case, for the electronic control unit 22 of the second embodiment (FIG. 6) and the third embodiment (FIG. 9), a steady operation determining means for determining a steady operation state of the internal combustion engine, EGR control prohibiting means for forcibly reducing the EGR flow rate Qr to 0 when the determination is made, and E calculating a deviation ΔPr between the EGR pressure Pra in the EGR control in the steady operation state and the EGR pressure Prb in the EGR control prohibited state E
GR pressure deviation calculating means is provided.

When the fifth embodiment is applied, the electronic control unit 22 of the second embodiment includes an EGR pressure deviation Δ
An intake pipe pressure correcting means for correcting the intake pipe pressure Pm based on Pr is provided.
Includes the intake air amount Qa based on the EGR pressure deviation ΔPr.
Is provided. Thus, the intake pipe pressure P calculated in step S133a
m and the intake air amount Qa calculated in step S203 are respectively compensated.

First, in step S211 in FIG. 12, it is determined whether or not the engine 1 is in a steady operation state. That is, after confirming that the EGR control is performed and that the engine 1 is in the warm-up state, it is determined whether or not the change amount of the engine speed Ne and the change amount of the throttle opening θ are equal to or less than predetermined values. Determine whether or not.

If the vehicle is not in the steady operation state (ie, N
If it is determined to be O), the process returns as it is, and if it is determined that the vehicle is in the steady operation state (that is, YES), the process proceeds to step S212 to detect the pressure PrA in the EGR passage 10 in the state where the EGR control is performed. .

Subsequently, at step S213, EG
After forcibly terminating the EGR control by the R control prohibiting means, the pressure PrB in the EGR passage 10 in a state without the EGR control is detected in step S214. As well
EGR is forcibly introduced during deceleration (no EGR)
Detects pressures PrA and PrB with and without EGR
can do. Next, the detected EGR pressure PrA
And PrB, an EGR pressure deviation ΔPr is calculated.
If there is no variation in parts such as the engine 1, EG
The R pressure deviation ΔPr becomes a predetermined value.

On the other hand, if there is a variation in the parts, E
Since it appears in the change in GR pressure deviation ΔPr, step S
At 216, a correction coefficient corresponding to the EGR pressure deviation ΔPr is read out by a map calculation or the like. In this manner, a correction coefficient for the component variation is obtained from the EGR pressure deviation ΔPr when the EGR control is switched to the presence or absence during the steady operation.

Hereinafter, the intake pipe pressure Pm (see step S133a in FIG. 8) and the intake air amount Qa (FIG. 1) obtained by the above-described calculation using the variation correction coefficient.
(Step S203 within 0) is multiplied or added so as to cancel out the variation error. Thus, it is possible to compensate for the EGR control error caused by the component variation.

Embodiment 6 FIG. In addition, the above-mentioned Examples 1 to 5
Detects the EGR flow rate Qr and the atmospheric pressure Pa based on each information of the intake air amount Qa, the intake pipe pressure Pm, and the EGR pressure Pr, and accurately controls the EGR flow rate Qr. In the case of the apparatus having the vaporized gas recovery means, since the vaporized gas is introduced into the intake manifold of the intake pipe 3 in addition to the EGR flow rate Qr, the introduction of the vaporized gas may change the intake pipe pressure Pm.

With the change in the intake pipe pressure Pm,
An error occurs in the EGR flow rate Qr, and an error occurs in the EGR control. Therefore, it is desirable to compensate for the EGR control error caused by the operation of the vaporized gas recovery system.

FIG. 13 is a block diagram showing a sixth embodiment (corresponding to claim 9) of the present invention in which a control error in the case of having a vaporized gas recovery system can be compensated. FIG. 14 is an electronic control in FIG. It is a block diagram which shows the detail of the unit 22, In each figure, 1-23, 100-105 and 2
Reference numerals 00 to 208 are the same as those described above.

Reference numerals 24 to 28 denote constituent elements of a vaporized gas recovery system, 24 is a recovery pipe for introducing vaporized gas into the intake pipe 3, and 25 is a valve for opening and closing the recovery pipe 24 under the control of the electronic control unit 22. A purge solenoid 26 for selectively introducing vaporized gas into the intake pipe 3 through a purge solenoid 25.
Is a canister provided on the upstream side of the canister for absorbing vaporized gas, 27 is a check valve provided on the upstream side of the canister 26, 28 is a fuel tank provided on the upstream end of the recovery pipe 24 and filled with fuel. .

The evaporative gas recovery systems 24 to 28 configured as described above operate as follows. First, the fuel in the fuel tank 28 evaporates and becomes vaporized gas. When the pressure of the vaporized gas exceeds a predetermined pressure, the check valve 2
7 is opened, and the vaporized gas is adsorbed on the canister 26.

On the other hand, if predetermined conditions are satisfied after the engine 1 is started, the electronic control unit 22 operates the purge solenoid 25 in accordance with the purge control signal Cp, and removes the vaporized gas adsorbed by the canister 26 into the engine 1. Intake pipe 3
Introduce within. Thereby, the evaporated gas generated from the fuel tank 28 can be collected in the engine 1.

In this case, the vaporized gas recovery means 24 to 24 for recovering the vaporized gas from the fuel tank 28 to the engine 1.
Since the electronic control unit 27 is provided, the electronic control unit 22 estimates and detects the purge gas introduction amount Qp by a map calculation according to the operation state, and a purge control means for generating a purge control signal Cp according to the operation state. A vaporized gas introduction amount detecting means and an EGR flow rate correction means for correcting the EGR flow rate Qr according to the vaporized gas introduction amount Qp are provided.

Next, the compensation operation according to the sixth embodiment of the present invention will be described with reference to the flowchart of FIG. FIG. 15 shows the flow rate of the EGR flow Q
9 is a flowchart illustrating a processing routine for compensating for r.

First, in step S241, the amount Q of vaporized gas introduced into the engine 1 according to the operating state
Calculate p. Next, in step S242, the true EGR is calculated from the vaporized gas introduction amount Qp and the EGR flow rate Qr.
The flow rate Qr 'is obtained by the following equation (13).

Qr '= Qr-Qp (13)

As a result, the EGR flow rate Qr is corrected,
Accurate EGR control becomes possible. Also, when the EGR control and the evaporated gas recovery system are operated independently, it goes without saying that accurate EGR control is possible.

Embodiment 7 FIG. In the sixth embodiment, the true EGR flow rate Qr 'is obtained in step S242.
The true target EGR flow rate Qo 'is obtained to obtain the target EGR flow rate Qo.
Is corrected, a true EGR flow rate Qr 'can be obtained as a result. In addition, the EGR rate βr
Alternatively, even if the target EGR rate βo is corrected, the true E
The same effect can be obtained by obtaining the GR flow rate Qr '.

Embodiment 8 FIG. In the sixth embodiment, the vaporized gas introduction amount detecting means estimates and detects the vaporized gas introduction amount Qp by calculation based on the operating state. However, a flow meter is provided downstream of the purge solenoid 25, and the vaporized gas introduction amount Qp is provided. May be directly detected.

Embodiment 9 FIG. In the sixth embodiment, the EGR flow rate Qr is corrected by calculating the true EGR flow rate Qr ′ by subtracting the vaporized gas introduction quantity Qp.
2 may be provided with a vaporized gas recovery prohibiting means so that the operation of the vaporized gas recovery system is prohibited during the EGR control.

That is, the vaporized gas recovery inhibiting means in the electronic control unit 22 fixes the purge control signal Cp to OFF and sets the vaporized gas introduction amount Qp to 0 when it is determined that the EGR control is being performed. As a result, since the evaporated gas is not recovered, no control error occurs in the EGR flow rate Qr.

[0147]

As described above, according to the first aspect of the present invention, an EGR pipe for recirculating exhaust gas of an internal combustion engine to an intake pipe, an EGR valve for controlling an EGR flow rate of exhaust gas flowing in the EGR pipe, A sensor for detecting an operation state of the internal combustion engine; and an EGR flow control unit for controlling an EGR valve in accordance with the operation state information from the sensor, and a part of the exhaust gas of the internal combustion engine is returned to the internal combustion engine again. In the exhaust gas recirculation control device, the sensor means includes an air flow sensor that detects an amount of air taken into the intake pipe, an intake pipe pressure sensor that detects a pressure in the intake pipe, and an EGR pressure sensor that detects a pressure in the EGR pipe. A target EGR rate calculating means for calculating a target EGR rate according to the operating state information, and calculating an actual EGR rate based on the intake air amount, the intake pipe pressure and the EGR pressure. EGR including the actual EGR rate calculating means
The flow rate calculating means includes a flow rate calculating means, and the EGR flow rate controlling means changes the passage area of the EGR valve so that the EGR rate becomes equal to the target EG.
Since the EGR flow rate is controlled so as to match the R rate, the EGR flow rate is accurately controlled regardless of the variation in the characteristics of the EGR valve.
There is an effect that an exhaust gas recirculation control device that can reduce the amount of exhaust gas emission by controlling the R flow rate can be obtained.

According to a second aspect of the present invention, in the first aspect, an orifice is provided in the EGR pipe downstream of the installation position of the EGR pressure sensor, and E orifice is provided by the orifice.
Since the pressure difference between the GR pressure and the intake pipe pressure is made remarkable, an exhaust gas recirculation control device that can more accurately control the EGR flow rate is obtained.

According to a third aspect of the present invention, in the first or second aspect, the atmospheric pressure is obtained based on the intake pipe pressure when the internal combustion engine is stopped or the intake pipe is fully opened. Since the detection means is provided, there is an effect that an exhaust gas recirculation control device can be obtained in which the cost can be reduced by eliminating the need for an atmospheric pressure sensor and the EGR flow rate can be accurately controlled irrespective of variations in the characteristics of the EGR valve.

According to a fourth aspect of the present invention, an EGR pipe for recirculating exhaust gas of an internal combustion engine to an intake pipe,
EGR for controlling EGR flow rate of exhaust gas flowing in R pipe
A valve, sensor means for detecting the operating state of the internal combustion engine, and EGR flow control means for controlling the EGR valve in accordance with the operating state information from the sensor means. In the exhaust gas recirculation control device, the sensor means includes an air flow sensor for detecting the amount of intake air to the intake pipe and an EGR pressure sensor for detecting the pressure in the EGR pipe. Intake pipe pressure calculating means for calculating the pressure in the intake pipe based on the air amount, target EGR rate calculating means for calculating a target EGR rate in accordance with the operating state information, and based on the intake air quantity, the intake pipe pressure and the EGR pressure And an actual EGR rate calculating means for calculating the actual EGR rate. The EGR flow rate controlling means changes the passage area of the EGR valve by changing the passage area of the EGR valve. Since the EGR flow is controlled so that the EGR rate coincides with the target EGR rate, exhaust gas recirculation control that realizes cost reduction by eliminating the need for an intake pipe pressure sensor and improves the reliability of the EGR flow rate control There is an effect that the device can be obtained.

According to a fifth aspect of the present invention, in the fourth aspect, means for determining a steady operation state of the internal combustion engine, and forcibly setting the EGR flow rate to 0 when the steady operation state is determined. EGR control prohibiting means, EGR pressure deviation calculating means for calculating a difference between the EGR pressure in the EGR control in the steady operation state and the EGR pressure in the EGR control prohibiting state, and intake air for correcting the intake pipe pressure based on the EGR pressure deviation. The provision of the pipe pressure correction means eliminates the need for an intake pipe pressure sensor, thereby realizing cost reduction, compensating for errors due to variations in the engine and other parts, and improving the reliability of EGR flow control. There is an effect that an exhaust gas recirculation control device can be obtained.

According to a sixth aspect of the present invention, an EGR pipe for recirculating exhaust gas of an internal combustion engine to an intake pipe,
EGR for controlling EGR flow rate of exhaust gas flowing in R pipe
A valve, sensor means for detecting the operating state of the internal combustion engine, and EGR flow control means for controlling the EGR valve in accordance with the operating state information from the sensor means. In the exhaust gas recirculation control device for recirculating the exhaust gas, the sensor means includes an intake pipe pressure sensor for detecting the pressure in the intake pipe, and an EG for detecting the pressure in the EGR pipe.
R pressure sensor, an intake air amount calculating means for calculating an intake air amount to the intake pipe based on the rotational speed of the internal combustion engine and the intake pipe pressure, and a target EGR for calculating a target EGR rate according to the operating state information The EGR flow rate calculating means includes an EGR flow rate calculating means for calculating an actual EGR rate based on the intake air amount, the intake pipe pressure, and the EGR pressure. By changing the passage area, the EGR flow rate is controlled so that the EGR rate matches the target EGR rate. This eliminates the need for an air flow sensor, reduces costs, and improves the reliability of EGR flow rate control. There is an effect that the exhaust gas recirculation control device is obtained.

According to a seventh aspect of the present invention, in the sixth aspect, means for determining a steady operation state of the internal combustion engine, and forcibly setting the EGR flow rate to 0 when the steady operation state is determined. EGR control prohibiting means, EGR pressure deviation calculating means for calculating a difference between the EGR pressure in the EGR control in the steady operation state and the EGR pressure in the EGR control prohibiting state, and suction for correcting the intake air amount based on the EGR pressure deviation. The provision of the air amount correction means eliminates the need for an air flow sensor, thereby reducing costs, compensating for errors due to variations in the engine and other components, and further improving the reliability of EGR flow control. There is an effect that a reflux control device can be obtained.

According to an eighth aspect of the present invention, in the sixth or seventh aspect, the atmospheric pressure is obtained based on the intake pipe pressure when the internal combustion engine is stopped or the intake pipe is fully opened. The provision of the detection means eliminates the need for an atmospheric pressure sensor as well as an air flow sensor, thereby realizing a cost reduction and, further, providing an exhaust gas recirculation control device capable of accurately controlling the EGR flow rate irrespective of variations in the characteristics of the EGR valve. Has the effect.

According to a ninth aspect of the present invention, in any one of the first to eighth aspects, the vaporized gas recovery means for recovering the vaporized gas from the fuel tank to the internal combustion engine; A vaporized gas introduction amount detecting means for detecting an introduced amount of EGR gas and an EGR flow rate correcting means for correcting an EGR flow rate in accordance with the vaporized gas introduction amount so as to prevent a change in the intake pipe pressure at the time of operation of the vaporized gas recovery system. The effect of the vaporized gas recovery system is eliminated, and E
There is an effect that an exhaust gas recirculation control device in which the reliability of the GR flow rate control is improved can be obtained.

According to a tenth aspect of the present invention, in any one of the first to eighth aspects, a vaporized gas recovery means for recovering vaporized gas from the fuel tank to the internal combustion engine, and EGR control And the transpiration gas recovery prohibiting means for prohibiting the operation of the transpiration gas recovery means during the execution of
There is an effect that the influence of the evaporated gas recovery system on the EGR control is eliminated, and an exhaust gas recirculation control device in which the reliability of the EGR flow rate control is improved can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing an entire system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a specific configuration of an electronic control unit in FIG.

FIG. 3 is an enlarged sectional view showing a periphery of an EGR pipe in FIG. 1;

FIG. 4 is a diagram illustrating an E according to a main routine according to the first embodiment of the present invention;
It is a flowchart which shows operation | movement of GR control processing.

FIG. 5 is a flowchart illustrating an atmospheric pressure detection process according to the first embodiment of the present invention.

FIG. 6 is a configuration diagram schematically showing an entire system according to a second embodiment of the present invention.

FIG. 7 is a block diagram showing a specific configuration of the electronic control unit in FIG.

FIG. 8 is a flowchart illustrating an operation of an EGR control process according to the second embodiment of the present invention.

FIG. 9 is a configuration diagram schematically showing an entire system according to a third embodiment of the present invention.

FIG. 10 is a block diagram showing a specific configuration of an electronic control unit in FIG. 9;

FIG. 11 is a flowchart showing an EGR processing operation according to Embodiment 3 of the present invention.

FIG. 12 is a flowchart showing a compensation processing operation according to Embodiment 5 of the present invention.

FIG. 13 is a configuration diagram schematically showing an entire system according to a sixth embodiment of the present invention.

FIG. 14 is a block diagram showing a specific configuration of the electronic control unit in FIG.

FIG. 15 is a flowchart showing a compensation processing operation according to a vaporized gas introduction amount according to Embodiment 6 of the present invention.

FIG. 16 is a configuration diagram showing an entire system of a conventional stepper motor type exhaust gas recirculation control device.

FIG. 17 is a block diagram showing a specific configuration of the electronic control unit in FIG.

FIG. 18 is a side sectional view showing a specific configuration of the EGR valve in FIG.

FIG. 19 is a characteristic diagram showing flow characteristics of a general EGR valve.

FIG. 20 is a flowchart showing a main routine of a control processing operation by a general electronic control unit.

FIG. 21 is a flowchart showing a conventional EGR control processing operation.

FIG. 22 is an explanatory diagram showing an operation principle of a general stepper motor together with a basic drive connection diagram.

FIG. 23 is an explanatory diagram showing a drive pattern and a rotation direction of a general stepper motor by a two-phase excitation method.

FIG. 24 is a characteristic diagram for explaining a problem in the conventional EGR control.

[Explanation of symbols]

Reference Signs List 1 engine 3 intake pipe 6 intake pipe pressure sensor 8 throttle opening sensor 10 EGR pipe 11 EGR valve 12 air flow sensor 13 ignition coil 15 exhaust pipe 17 water temperature sensor 18 EGR pressure sensor 19 orifice 22 electronic control unit 24 recovery pipe 25 purge solenoid 26 Canister 27 Check valve 28 Fuel tank Cr EGR control signal Cp Purge control signal Pa Atmospheric pressure Pm Intake pipe pressure Pr EGR pressure PrA EGR pressure during EGR control PrB EGR pressure during EGR control inhibition Qa Intake air amount Qr EGR flow rate T Cooling Water temperature Q Ignition signal βo Target EGR rate βr Actual EGR rate θ Throttle opening S132 Step of calculating target EGR rate S133a Step of calculating intake pipe pressure S134 Step of calculating EGR flow rate S1 35 Step of calculating actual EGR rate S136 Step of comparing target EGR rate and actual EGR rate S138 Step of controlling EGR flow rate according to EGR rate deviation S141 Step of determining stop state of internal combustion engine S142, S144 Estimation and detection step S143 Step of determining the fully open state of the intake pipe S200 Step of calculating the intake air amount S211 Step of determining the steady operation state S212 Step of detecting the EGR pressure during EGR control S213 Forcibly setting the EGR flow rate to 0 Step S214 Step of detecting the EGR pressure when EGR control is prohibited S215 Step of calculating the EGR pressure deviation S216 Step of calculating the correction coefficient based on the EGR pressure deviation S241 Step of calculating and detecting the introduction amount of the vaporized gas S242 Steam Step of correcting the EGR rate according to the gas introduction amount

Claims (10)

(57) [Claims] An EGR pipe configured to recirculate exhaust gas from an internal combustion engine to an intake pipe; an EGR valve configured to control an EGR flow rate of exhaust gas flowing in the EGR pipe; a sensor unit configured to detect an operation state of the internal combustion engine; The EGR according to the operating state information from the sensor means
An exhaust gas recirculation control device for recirculating a part of the exhaust gas of the internal combustion engine to the internal combustion engine, the sensor device comprising: an intake air amount to the intake pipe; A target for calculating a target EGR rate in accordance with the operating state information, including an air flow sensor for detecting a pressure in the intake pipe, an intake pipe pressure sensor for detecting a pressure in the intake pipe, and an EGR pressure sensor for detecting a pressure in the EGR pipe. An EGR rate calculating means for calculating an actual EGR rate based on the intake air amount, the intake pipe pressure and the EGR pressure;
An EGR flow rate calculation means including a GR rate calculation means, wherein the EGR flow rate control means changes the passage area of the EGR valve so that the EGR flow rate matches the target EGR rate. An exhaust gas recirculation control device characterized by performing the following control. 2. The exhaust gas recirculation control device according to claim 1, wherein an orifice is provided in the EGR pipe downstream of an installation position of the EGR pressure sensor. 3. An atmospheric pressure detecting means for obtaining an atmospheric pressure based on the intake pipe pressure when the internal combustion engine is stopped or when the intake pipe is fully opened. 2. Exhaust gas recirculation control device. 4. An EGR pipe for recirculating exhaust gas of the internal combustion engine to an intake pipe, an EGR valve for controlling an EGR flow rate of the exhaust gas flowing in the EGR pipe, a sensor means for detecting an operation state of the internal combustion engine, The EGR according to the operating state information from the sensor means
An exhaust gas recirculation control device for recirculating a part of the exhaust gas of the internal combustion engine to the internal combustion engine, the sensor device comprising: an intake air amount to the intake pipe; An intake air pressure sensor for detecting the pressure in the intake pipe based on a rotational speed of the internal combustion engine and the amount of intake air; ,
Target EGR rate calculating means for calculating a target EGR rate in accordance with the operating state information; and actual EGR for calculating an actual EGR rate based on the intake air amount, the intake pipe pressure and the EGR pressure.
An EGR flow rate calculation means including a GR rate calculation means, wherein the EGR flow rate control means changes the passage area of the EGR valve so that the EGR flow rate matches the target EGR rate. An exhaust gas recirculation control device characterized by performing the following control. 5. A means for determining a steady operation state of the internal combustion engine; an EGR control prohibiting means for forcibly setting the EGR flow rate to 0 when the steady operation state is determined; EGR pressure deviation calculating means for calculating a difference between the EGR pressure during control and the EGR pressure in the EGR control prohibited state; and intake pipe pressure correcting means for correcting the intake pipe pressure based on the EGR pressure deviation. The exhaust gas recirculation control device according to claim 4, characterized in that: 6. An EGR pipe for recirculating exhaust gas of the internal combustion engine to an intake pipe, an EGR valve for controlling an EGR flow rate of the exhaust gas flowing in the EGR pipe, a sensor means for detecting an operation state of the internal combustion engine, The EGR according to the operating state information from the sensor means
An exhaust gas recirculation control device for recirculating a part of the exhaust gas from the internal combustion engine to the internal combustion engine, the sensor device detecting a pressure in the intake pipe. An intake pipe pressure sensor and an EG for detecting the pressure in the EGR pipe
An R pressure sensor; an intake air amount calculating means for calculating an intake air amount to the intake pipe based on a rotation speed of the internal combustion engine and an intake pipe pressure; and a target EGR rate according to the operation state information. A target EGR rate calculating means for calculating an actual EGR rate based on the intake air amount, the intake pipe pressure and the EGR pressure; and an EGR flow rate controlling means. In the exhaust gas recirculation control device, the EGR flow rate is controlled such that the EGR rate matches the target EGR rate by changing a passage area of the EGR valve. 7. A means for determining a steady operation state of the internal combustion engine; an EGR control inhibiting means for forcibly setting the EGR flow rate to 0 when the steady operation state is determined; EGR pressure deviation calculating means for calculating the difference between the EGR pressure during control and the EGR pressure in the EGR control prohibited state; and intake air amount correcting means for correcting the intake air amount based on the EGR pressure deviation. The exhaust gas recirculation control device according to claim 6, characterized in that: 8. An atmospheric pressure detecting means for obtaining an atmospheric pressure based on the intake pipe pressure when the internal combustion engine is stopped or when the intake pipe is fully opened. 7. Exhaust gas recirculation control device. 9. A vaporized gas recovery means for recovering vaporized gas from a fuel tank to the internal combustion engine, a vaporized gas introduction amount detecting means for detecting an introduction amount of the vaporized gas, and according to the vaporized gas introduction amount. The exhaust gas recirculation control device according to any one of claims 1 to 8, further comprising an EGR flow rate correction means for correcting the EGR flow rate. 10. A vaporized gas recovery means for recovering vaporized gas from a fuel tank to the internal combustion engine, and a vaporized gas recovery inhibiting means for inhibiting operation of the vaporized gas recovery means during execution of the EGR control. The exhaust gas recirculation control device according to any one of claims 1 to 8, wherein the exhaust gas recirculation control device is provided.