JPH09177584A - Engine device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of the operational failure of an idle speed controller by performing control so as to increase a passing air flow rate passing through an idle speed control passage more than that during a non-reduction operation state when the reduction operation state of exhaust gas is detected. SOLUTION: In an ECU 17 to which signals are inputted from a water temperature sensor 11, a throttle opening sensor 9, a crank angle sensor 18 and the like, determination is first made as to idling running and if non-idling running is determined, a basic ISC air amount as the passing air flow rate of an ISC passage 13 is decided. Then, the opening/closing of an EGR valve 16 is controlled. If the operation of the EGR valve 16 is determined, an ISC correction amount for increasing the basic ISC air amount is decided based on an engine revolution speed or a throttle opening degree. Then, an ISC air amount is decided by adding the basic ISC air amount and an ISC corrected amount and an ISC valve 14 is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine idle speed control device, and more particularly to an engine idle speed control device having an exhaust gas recirculation means.

[0002]

2. Description of the Related Art Conventionally, an idle speed control (hereinafter referred to as ISC) device for maintaining an idle speed at a predetermined value according to an engine cooling water temperature and an engine load has been used in an intake system of an engine.

In one of the ISC devices, an ISC valve is provided in the middle of an ISC passage provided by bypassing a throttle valve to increase or decrease the flow rate of air passing through the ISC passage to control the idle rotation speed. Some use a method of adjusting and controlling.

For example, there is one in which an actuator such as a rotary solenoid or a stepping motor and an ISC valve connected to the actuator are provided, and the ISC valve is arranged in the middle of the ISC passage. By adjusting and controlling this actuator by the ON / OFF duty ratio, the number of steps, etc., the flow rate of passing air passing through the ISC passage is adjusted to be increased or decreased. The idle rotation speed is increased or decreased by the increase / decrease adjustment of the passing air flow rate.

The control of this ISC device compares a target rotational speed determined by the engine cooling water temperature Tw and the state of the engine load such as the compressor load of the air conditioner with the actual rotational speed Ne of the engine and responds to the difference between them. The control amount is determined by the control so that the target rotation speed is achieved. That is, the ISC device that detects the engine speed Ne and adjusts the flow rate of air passing through the ISC passage based on the detected value is feedback-controlled.

[0006] Generally, the control of the ISC device is
Not done while the driver is operating the accelerator. This is to prevent the intake air amount that changes by operating the throttle valve and the ISC air amount that passes through the ISC passage that changes by the control of the ISC device from interfering with each other. Therefore, in the control of the ISC device, the idle operation state of the engine is detected by the throttle fully closed signal, the vehicle speed signal, etc., and the feedback control is performed only in the idle operation state.

For example, control of an ISC device using a rotary solenoid will be described below. This IS
The control of the C device is controlled by the ON / OFF duty ratio.

FIG. 4 is a graph showing the relationship between the ON / OFF duty ratio (%) and the flow rate Q'of air passing through the ISC passage. The relationship between the two is shown by the solid line on the graph. It is formed in a straight line rising to the right. This indicates that the flow rate of air passing through the ISC passage increases as the ON / OFF duty ratio increases. According to this flow rate characteristic, the basic duty ratio corresponding to the basic air flow rate is determined during the idle operation of the engine.

The engine is idling at a speed at which the output generated by the basic air flow rate contributing to combustion and the load of the engine are balanced. However, during this idle operation, the load of the compressor of the air conditioner, the load of the power steering pump, and the load of the torque converter in the drive (D) range are added, and the engine load may increase. In this case, the balance between the engine rotation speed and the load during idle operation is lost, the engine rotation speed decreases, and the rotation becomes unstable.

Therefore, it is necessary to increase and correct the engine rotation speed in response to the increase in the engine load. Therefore, various correction duty ratios are determined in order to supplement the air flow rate corresponding to this correction amount. Furthermore, PI
A duty change amount during feedback, which is a proportional value and an integral value of control, is also determined.

Further, in recent years, various exhaust gas purifying devices have been provided in engines in order to solve problems such as environmental pollution due to engine exhaust gas. One of the devices is an exhaust gas refueling system that aims to reduce the amount of NOx contained in the exhaust gas by returning a part of the exhaust gas to the intake system to lower the combustion temperature in the combustion chamber to reduce the NOx. There is a circulation (hereinafter referred to as EGR) device. This EGR device is
While the fuel efficiency can be improved by performing the GR, the ignitability of the air-fuel mixture and the engine output are reduced. Therefore, control is performed so that an appropriate amount of EGR is performed by selecting an engine operating region with a large NOx emission amount.

A blow-by gas returning device is one of the other devices. This device discharges the blow-by gas that leaks into the crankcase through the gap between the piston and the cylinder wall of the engine from the crankcase and recirculates it to the intake system to remove harmful unburned HC (which is contained in the blow-by gas). It is a device that has the function of burning hydrocarbons.

However, since the EGR device and the blow-by gas reducing device are provided for the above reason, these EG devices are not provided.
The EGR gas and the blow-by gas flow into the ISC passage provided in the intake system, which is the recirculation destination and the recirculation destination of the R gas and the blow-by gas, due to the blowback due to the intake pulsation generated in the intake system.

Then, the deposits produced by exposure of the carbon contained in the EGR gas recirculated to the intake system and the oil mist contained in the recirculated blow-by gas to the high temperature of the EGR gas are the ISC passages. It adheres to and deposits on the ISC valve provided inside.

Therefore, when deposits adhere to this ISC valve, the area of the opening of the ISC valve becomes narrow,
The passing air flow rate Q'through the ISC passage decreases as shown by the dotted line in FIG. Moreover, if the adhesion further evolves, I
This will interfere with the operation of the SC valve, and in the worst case ISC
It is remembered that the valve sticks.

The decrease in the passing air flow rate due to the deposits adhered to the ISC valve causes a start failure and a decrease in the rotation speed due to the insufficient air flow rate at the time of engine start and idle, and in the worst case, the engine stalls. Reach In addition, since various correction duty ratios also reduce the air flow rate passing through the ISC passage from the time of setting, in this state, a decrease in rotation and engine stall similarly occur due to fluctuations in the load of the air conditioner or the like. Further, since the change in the air amount corresponding to the operation of the actuator due to the change in the duty ratio becomes small, the responsiveness of the feedback control deteriorates, and this also causes a decrease in rotation and engine stall.

In order to solve the above problems, in the conventional embodiment, as shown by the dotted line in FIG.
The EGR gas was kept away from the SC passage so as not to reach the ISC valve.

Further, as another conventional form, Japanese Patent Laid-Open No. 5-1
Japanese Patent Publication No. 95880 discloses a combustion control device in which a return port of EGR gas to the intake system is provided near the intake valve of each cylinder on the downstream side of the ISC valve.

Further, as still another conventional form, Japanese Patent Laid-Open No. Hei 5 (1999) -5200
No. 296095 discloses an engine with a supercharger and an EG.
In the combination of the R devices, a filter for collecting fine particles such as carbon in the exhaust gas is provided to prevent carbon from adhering and depositing on the clearance of the compression portion of the supercharger.

[0020]

According to the above-mentioned conventional form, the positions of the EGR gas recirculation destination and the ISC passage are set as far apart as possible in the collecting portion of the intake system, and
It aims to minimize the effect of gas. However, in the intake system, blowback due to intake pulsation occurs, so even if the two are separated, a great effect could not be expected.

Further, the provision of the EGR pipe for each cylinder according to the above-mentioned Japanese Patent Laid-Open No. 5-195880 causes the structure to become complicated and the cost to rise.

Further, Japanese Patent Laid-Open No. 5-296095 describes a method of removing foreign matters such as carbon by providing a filter in the EGR gas recirculation passage. However, the manufacturing cost also rises. This also causes a burden such as periodical filter replacement.

Therefore, the present invention has been made in view of the above various circumstances, and its purpose is to provide an ISC device and an EG.
In an engine having an R device, without changing the recirculation destination of EGR, I
An object of the present invention is to provide an engine device having a mechanism for preventing malfunction of the SC device and suppressing a change over time in the flow rate characteristic of the ISC device.

[0024]

An engine device according to a first aspect of the present invention has an ISC means and an EGR means, a detection means for detecting a recirculation operation state of EGR gas is provided, and the EGR means performs EGR. In this case, the ISC means controls to increase and correct the flow rate of the air passing through the ISC passage.

Therefore, even if the EGR gas is blown back into the ISC passage due to the intake pulsation, the adherence of deposits such as carbon contained in the EGR gas to the ISC valve due to the increased corrected passing air flow rate. It can be prevented.
That is, it is possible to prevent the malfunction of the ISC valve due to the adhered deposits such as carbon, and to suppress the change over time of the flow rate characteristic of the ISC means.

The engine device according to claim 2 is the ISC
Control is performed to operate the means in correspondence with at least one of the engine speed and the opening of the throttle valve. That is, when the engine speed increases or the throttle valve opening increases, the IS
The flow rate of air passing through the C valve is increased and corrected.

Therefore, when the control of the ISC means is adjusted according to the engine rotation speed, the increase correction amount of the passing air flow rate is adjusted to be small on the low rotation side, so that the operator's operation state and the engine rotation speed are adjusted. That is, it is possible to eliminate the discomfort caused by the difference in the actual traveling speed. Although the increased correction amount increases on the high rotation side, the influence of drivability is small because the intake air amount of the entire engine is large.

Similarly, when the control of the ISC means is adjusted according to the opening of the throttle valve, the increase correction amount of the passing air flow rate is small when the opening is small, so that the throttle operation of the operator is performed. It is possible to eliminate the discomfort caused by the difference between the actual engine output and. On the other hand, when the opening is large, the increase correction amount increases, but since the intake air amount of the entire engine is large, it does not affect the drivability.

Therefore, it is possible to perform the control adapted to the operation feeling of the driver while maintaining the operation of the first aspect.

In the engine device according to claim 3, the IS
The C means corrects the flow rate of the air passing through the ISC passage.
Adjustment is made to correspond to the EGR amount detected by the recirculation operation state detecting means. That is, when the EGR amount increases, the passing air flow rate is increased and corrected, and when the EGR amount decreases, the decrease amount is adjusted to be decreased from the increase correction amount.

Therefore, when the EGR amount increases, the EGR gas concentration on the downstream side of the throttle valve becomes high, and the IS
Although the EGR gas also drifts around the C passage, the flow rate of the passing air passing through the ISC valve is increased accordingly in the present invention, so that the EGR gas is blown back into the ISC passage due to intake pulsation or the like. However, due to the increased flow rate of passing air, it is possible to prevent the deposition of carbon and the like contained in the EGR gas on the ISC valve. And EGR
When the amount is small, the flow rate of passing air is adjusted accordingly.

In the engine device according to the fourth aspect, the control for stopping the EGR or reducing the EGR amount is performed during the idle operation.

Therefore, EG during idle operation
By limiting the operation of R, it is possible to suppress the influence of the increase and decrease of the EGR amount on the control of the ISC means with respect to the ISC means that is performing the engine speed adjustment control during idle operation. That is, the EGR is performed by the EGR means, and the ISC is performed in accordance with the EGR amount.
It is possible to prevent the valve from operating and idling becoming unstable.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments in which the engine device of the present invention is used in a vehicle such as an automobile will be described in detail below.

FIG. 1 is a schematic explanatory view of an engine to which an engine device according to the present invention is applied. As shown,
An intake passage 4 and an exhaust passage 19 communicate with the cylinder head 3 of the engine body 1. An injector 12 is provided on the intake side of the engine body 1 to inject fuel into the cylinder. A throttle valve 8 for controlling the operating state of the engine is provided on the upstream side of the intake passage 4 via the air chamber 5. Further, an ISC passage 13 is provided by bypassing the throttle valve 8, and an ISC valve 14 for adjusting and controlling the passing air flow rate is provided in the ISC passage 13.

Further, there is provided an EGR passage 15 which communicates with the air chamber 5 through the exhaust passage 19 and recirculates a part of the exhaust gas to the intake system.
Is provided with an EGR valve 16 which is a duty control valve for controlling the recirculated EGR amount by a duty ratio.

Further, the cylinder block 2 of the engine body 1 is provided with a water temperature sensor 11 for measuring the engine cooling water temperature Tw. Further, an air cleaner 6 for air purification and an air flow meter 7 for detecting the intake air amount Q are provided upstream of the intake passage 4. Further, the throttle valve 8 is provided with a throttle opening sensor 9 for detecting the opening θ thereof.

An electronic control unit (hereinafter referred to as an ECU) 17 is provided as means for controlling the drive of each member and transmitting / receiving a detection signal from each sensor. In addition, to the ECU 17, detection signals of the engine speed Ne detected by the crank angle sensor 18 and the vehicle speed V detected by the vehicle speed sensor 10 are sent. The ECU 17
Is provided with a ROM storing preset data for controlling the ISC valve 14 and the EGR valve 16 and a RAM storing data received from each sensor.

Next, FIG. 2 is a block diagram showing the configuration of a basic embodiment of the present invention applied to the engine device of FIG. 1, and the portion surrounded by the one-dot chain line is the ECU 17
Is a part composed of.

As shown in the figure, the ECU 17 is provided with an ISC control means 20, an EGR control means 22, and an EGR operating state detection means 24.

The ISC control means 20 has a water temperature Tw detected by each of the water temperature sensor 11, the throttle opening sensor 9, the crank angle sensor 18 and the vehicle speed sensor 10 shown in FIG. The signals of the speed Ne and the vehicle speed V are taken in and I
The ISC air amount which is the flow rate of air passing through the SC passage is determined, and a signal for controlling the ISC is output to the ISC valve 14 in order to achieve this ISC air amount.

Similarly, the EGR control means 22 also takes in the signals measured by the respective sensors, and the EG is controlled by these signals.
EGR, which is the amount of exhaust gas recirculated through the R passage
The EGR valve 1 sends a signal that determines the amount and controls the EGR amount.
6 is output.

The EGR operating state detecting means 24 is
Captures the signals measured by each sensor, and further EGR
An EGR operating state signal of the EGR valve 16 from the control means 22, for example, whether or not the EGR valve is operating, or EG
A signal indicating the amount of R or the like is taken in, and this EGR operation state signal is output to the ISC control means 20 as an ISC correction signal. ISC control means 20 receiving this ISC correction signal
Is a crank angle sensor 18 and a throttle opening sensor 9
The ISC air amount, which is the amount of air passing through the ISC passage, is determined from the detection signal from.

Next, the operation of the engine device configured as shown in FIG. 2 will be described in more detail with reference to the flowchart of FIG.

The flow chart shown in this figure shows a method of adjusting the ISC air amount for preventing deposits from adhering to the ISC valve by the above configuration, and shows the operation of the EGR during the operation of the ISC valve. ing.

First, step (hereinafter referred to as "S")
In 101 and S102, it is determined whether the engine is in idle operation. In S101, it is determined whether the throttle valve 8 (see FIG. 1) is open (θ ≠ 0) or closed (θ = 0). If the throttle valve 8 is open (θ ≠ 0) (No) , It is determined that the engine is in non-idle operation, and the basic ISC is preset in S103 according to the engine operating state during non-idle operation.
A basic ISC air amount, which is a flow rate of air passing through the passage 13, is determined.

Further, in S101, the throttle valve 8
When (see FIG. 1) is closed (θ = 0), (Ye
In s) and S102, it is determined whether the vehicle is running or stopped. Here, when the vehicle speed V detected by the vehicle speed sensor 10 is not 0 (No), that is, when the vehicle is traveling, it is determined that the vehicle is in non-idle operation, and the basic ISC air amount is determined (S103).

Below, ISC during non-idle operation
The control of the flow rate of the passing air passing through the passage 13 will be described.

In S103, the ISC control means 20
The basic ISC air amount is determined according to the engine operating state detected by each sensor shown in FIG. For example, the IS corresponding to the throttle opening θ and the engine speed Ne
The basic ISC air amount is determined by reading the data with a three-dimensional map that defines the C air amount.

Then, in S104, the ISC valve 1
The EGR amount, which is a pre-stage operation for correcting the basic ISC air amount passing through the ISC passage 13 in order to prevent deposits from adhering to No. 4, is determined. Here, the EGR control means 22 determines the EGR amount according to the engine operating state detected by each sensor, and controls the opening / closing of the EGR valve 16 in order to achieve this EGR amount. For example, EGR
The valve 16 is controlled to increase the EGR gas amount in order to reduce the combustion temperature in the combustion chamber and reduce NOx in the engine operating state where the NOx emission amount is large, and to control the engine output and the engine output in the engine operating state where the NOx emission amount is small. The amount of EGR gas is controlled so as to be reduced in order to prevent deterioration of the ignitability of the air-fuel mixture. Further, the amount of EGR gas is set to 0 when the engine is operating without EGR.

Next, in S105, the EGR valve 16
A determination is made as to whether or not is operating. Here, when the EGR operation state detection means 24 determines that the EGR valve 16 is operating (Yes), that is, the EGR gas is being recirculated, the prevention of deposition of deposits on the ISC valve 14 in S106. For this reason, an ISC correction signal for determining an ISC correction amount for increasing the basic ISC air amount passing through the ISC passage 13 is output to the ISC control means 20. Then, the ISC control means 20 which has received this ISC correction signal
Determines the ISC correction amount for correcting the basic ISC air amount based on the engine rotation speed Ne or the throttle opening θ.

Next, in S107, the ISC control means 2
0 determines the ISC air amount which is the flow rate of the air passing through the ISC passage 13 in order to prevent the deposition of deposits on the ISC valve 14. Here, the ISC control means 20 determines the ISC air amount by adding the basic ISC air amount determined in S103 and the ISC correction amount determined in S106. The ISC control means 20 then determines the I
The ISC valve 14 is controlled to achieve the SC air amount.

If the EGR operating state detecting means 24 determines in S105 that the EGR valve 16 is not operating (No), that is, if the EGR gas is not being recirculated, the basic state is determined in S108. I
An ISC correction signal that determines the ISC correction amount to be 0 is output to the ISC control means 20 without performing the increase correction of the SC air amount.
Then, the ISC air amount is determined (S107). Here, a value obtained by adding the ISC correction amount 0 to the basic ISC air amount,
That is, the basic ISC air amount becomes the ISC air amount. Then, the ISC control means 20 controls the ISC valve 14 for achieving the determined ISC air amount.

Next, the control of the flow rate of the passing air passing through the ISC passage 13 during the idle operation will be described below.

First, when the throttle opening θ is 0 in S101 (Yes), that is, when the throttle valve 8 is fully closed, the vehicle speed V of the vehicle is determined in S102. Here, when the vehicle speed V detected by the vehicle speed sensor 10 is 0 (Yes), that is, when the vehicle is in the non-running state, it is determined that the vehicle is idling, and S109
In the same manner as a general engine, the idling engine speed during idling is determined. Here, the setting operation of the ISC air amount for adjusting the idle engine rotation speed, which is the original function of the ISC valve 14, is performed. That is, the ISC control means 20 determines the ISC air amount by rotational speed feedback control that adjusts to an appropriate idle engine rotation speed in response to an increase or decrease in the engine load during idle operation, such as a compressor load of an air conditioner. . Then, the ISC control means 20 uses the ISC valve 1 for achieving the determined ISC air amount.
4 is controlled.

Then, in S110, the ISC air amount for adjusting the idle engine speed is set.
The EGR amount is set in order to prevent the EGR operation that hinders the operation of the SC valve 14. Where E
Since the GR control means 22 does not affect the ISC control means 20 performing the idle engine speed control by the increase or decrease of the EGR amount, the EGR amount is set to 0 during the idle operation.
Alternatively, control is performed to reduce the EGR amount, and the EGR valve 16 is controlled to be fully closed or closed in order to achieve this EGR amount. By this control, the EGR valve 1 is operated during idle operation.
The influence of the operation of 6 on the control of the ISC valve 14 can be suppressed, and the normal idle engine speed adjustment control can be reliably performed.

The above control is performed and this flowchart is ended.

The present invention is not limited to the configuration of the above embodiment, but various modifications can be made within the scope of the gist of the invention. For example, in the above embodiment, the ISC correction amount is determined by the engine speed or the throttle opening, but instead of this, the ISC correction amount is determined according to the fuel injection amount of the engine or the suction pipe negative pressure. Is also possible.

[0059]

As described above, according to the engine device of the present invention, the EGR operating state detecting means is provided, and when the detecting means detects that the EGR operating state is in progress, the ISC control means is provided. Makes a correction to increase the flow rate of the passing air passing through the ISC passage as compared with the case where the EGR is not operating.

As a result, even if the EGR gas may enter the ISC passage due to the intake pulsation, it is possible to prevent deposits from adhering to the ISC valve by the increased flow rate of the passing air. Therefore, it is possible to prevent the change in the amount of air passing through the ISC valve and the occurrence of malfunction due to the adhered deposits, and it is possible to suppress the change over time in the flow rate characteristic of the ISC means, and to control the intake air amount by the ISC valve. Reliability is increased.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory diagram of an engine to which an engine device according to the present invention is applied.

FIG. 2 is a block diagram showing the configuration of a basic embodiment of the present invention applied to the engine device of FIG.

FIG. 3 is a flow chart showing a method for adjusting the ISC air amount by the engine device of the present invention.

FIG. 4 is a diagram showing a relationship between an ON / OFF duty ratio for controlling an ISC valve and a flow rate of air passing through an ISC passage.

[Explanation of symbols]

 1 ... Engine Body 2 ... Cylinder Block 3 ... Cylinder Head 4 ... Intake Passage 5 ... Air Chamber 6 ... Air Cleaner 7 ... Air Flow Meter 8 ... Throttle Valve 10 ... Vehicle Speed Sensor 11 ... Water Temperature Sensor 12 ... Injector 13 ... ISC Passage 14 ... ISC Valve 15 ... EGR passage 16 ... EGR valve (duty control valve) 17 ... Electronic control unit (ECU) 18 ... Crank angle sensor 19 ... Exhaust passage

Claims (4)

[Claims] 1. An idle speed control passage provided by bypassing a throttle valve in an intake system of an engine, idle speed control means for adjusting and controlling a flow rate of air passing through the idle speed control passage, and intake air from an exhaust system. An exhaust gas recirculation operation state is detected in an engine device having a recirculation passage for recirculating a part of exhaust gas in the system and an exhaust gas recirculation control means for adjusting and controlling the recirculation amount of exhaust gas passing through the recirculation passage. Recirculation operation state detection means is provided, and the idle speed control means, when the recirculation operation state detection means detects that the recirculation operation state is in a recirculation operation state, the flow rate of passing air passing through the idle speed control passage An engine device characterized in that it is increased from that during the state. 2. The increase adjustment of the passing air flow rate by the idle speed control means is performed in accordance with at least one of a rotation speed of the engine and an opening degree of a throttle valve as the rotation speed increases or the throttle opening degree increases. The engine device according to claim 1, wherein the engine device is operated so as to increase the flow rate of the passing air. 3. The idle speed control means increases or decreases the passing air flow rate according to the increase or decrease of the recirculation amount of the exhaust gas detected by the recirculation operation state detecting means. Or the engine device according to 2. 4. The exhaust gas recirculation control means controls the exhaust gas recirculation during the idling operation of the engine or controls the amount of recirculation of the exhaust gas to be smaller than during the idling operation. The engine device according to items 1 to 3.