JP2012002163A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine capable of accurately protecting its exhaust system by estimating the catalyst temperature accurately.SOLUTION: A controlling means (31) includes a catalyst temperature estimating means (31A) to estimate the catalyst temperature on the basis of the engine speed sensed by an engine speed sensing means (32) and the engine load sensed by an engine load sensing means (35), and a throttle opening controlling means (31B) to control the throttle opening of a throttle valve (13), wherein the throttle opening controlling means (31B) makes open-close control of the throttle valve (13) so that the internal combustion engine (1) is put into an idling state when the catalyst temperature estimated by the catalyst temperature estimating means (31A) has exceeded the set value set previously.

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for an internal combustion engine that estimates a catalyst temperature based on an engine speed and an engine load.

In an internal combustion engine of a vehicle, harmful substances (CO, HC, NOx) are contained in exhaust gas, and a catalyst is provided in an exhaust system so that the harmful substances are not discharged into the atmosphere.
In the electronic control device, the internal combustion engine is controlled based on the engine speed detected by the engine speed detecting means and the engine load detected by the load detecting means, thereby preventing the exhaust system from overheating.

Japanese Patent Laid-Open No. 10-184396

  The engine idling control device according to Patent Document 1 avoids engine idling when the accelerator pedal is depressed while the vehicle is stopped, and prevents abnormal overheating of the exhaust system.

By the way, conventionally, in the control according to the above-mentioned Patent Document 1, it is assumed that the vehicle is stopped and that the internal combustion engine and the drive wheels are in an unlinked state. When the accelerator pedal is depressed for a predetermined time, the throttle valve for controlling the output of the internal combustion engine is operated to be closed by electronic control, thereby bringing the operation state of the internal combustion engine into an idling state, It prevents damage and deterioration due to abnormal overheating of the exhaust system.
However, since only the depression time of the accelerator pedal is controlled as a determination factor, it cannot be accurately determined whether the exhaust system is actually overheated abnormally.
Also, when the throttle valve is opened / closed by depressing the accelerator pedal intermittently, the preset set time does not elapse, so the control does not function, and the exhaust system is damaged or deteriorated due to abnormal overheating. There was an inconvenience.

  Accordingly, an object of the present invention is to provide a control device for an internal combustion engine that can accurately estimate a catalyst temperature and accurately protect an exhaust system.

  The present invention is provided with a throttle valve disposed in an intake passage of an internal combustion engine, provided with a catalyst disposed in an exhaust passage of the internal combustion engine, and provided with an engine speed detection means for detecting the engine speed of the internal combustion engine, Engine load detecting means for detecting the engine load of the internal combustion engine is provided, and the internal combustion engine is controlled based on the engine speed detected by the engine speed detecting means and the engine load detected by the engine load detecting means. In the control device for an internal combustion engine provided with the control means, the control means estimates the catalyst temperature based on the engine speed detected by the engine speed detection means and the engine load detected by the engine load detection means. A catalyst temperature estimating means; and a throttle opening control means for controlling the throttle opening of the throttle valve. When the catalyst temperature exceeds a predetermined set value, the internal combustion engine by the throttle opening control means and wherein the opening and closing controls the throttle valve so that the idling state.

  The control apparatus for an internal combustion engine according to the present invention can accurately estimate the catalyst temperature, and when the estimated catalyst temperature exceeds a set value, the internal combustion engine can be set in an idling state to accurately protect the exhaust system.

FIG. 1 is a flowchart for estimating the catalyst temperature. (Example) FIG. 2 is a system configuration diagram of the control device for the internal combustion engine. (Example)

  The present invention achieves the purpose of accurately protecting the exhaust system by accurately estimating the catalyst temperature and, when the estimated catalyst temperature exceeds a set value, putting the internal combustion engine in an idling state.

1 and 2 show an embodiment of the present invention.
In FIG. 2, 1 is a dual-type internal combustion engine as an internal combustion engine mounted on a vehicle, and 2 is a cylinder block. A crankshaft 3 and a pair of one-side cylinder head 4A and the other-side cylinder head 4B are attached to the cylinder block 2.
An intake manifold 5 is attached to the one side cylinder head 4A and the other side cylinder head 4B in the intake system. The intake manifold 5 includes a one-side intake manifold pipe 6A and another-side intake manifold pipe 6B connected to the one-side cylinder head 4A and the other-side cylinder head 4B, and the one-side intake manifold pipe 6A and the other-side intake manifold pipe 6B. Are provided on the upstream side, and a surge tank 8 on the upstream side of the intake manifold 7 is provided.
An intake pipe 10 that forms an intake passage 9 together with the intake manifold 5 is connected to the surge tank 8. An air cleaner 11 is attached to the upstream end of the intake pipe 10.
Inside the intake pipe 10 on the surge tank 8 side, a throttle valve 13 that is electronically controlled and is operated by a throttle valve actuator 12 is disposed.

An exhaust manifold 14 is attached to the one-side cylinder head 4A and the other-side cylinder head 4B in the exhaust system. The intake manifold 14 includes a one-side exhaust manifold pipe 15A and another-side exhaust manifold pipe 15B connected to the one-side cylinder head 4A and the other-side cylinder head 4B, and the one-side exhaust manifold pipe 15A and the other-side exhaust manifold pipe 15B. Is provided with an exhaust collecting pipe 16 that collects on the downstream side.
An upstream catalytic converter 18 including an upstream catalyst 17 is provided at the downstream end of the exhaust collecting pipe 16. An exhaust pipe 20 that forms an exhaust passage 19 together with the intake manifold 14 is connected to the upstream catalytic converter 18. The exhaust pipe 20 is provided with a downstream catalytic converter 22 having a downstream catalyst 21 and a muffler 23 sequentially.

One side fuel injection valve 24A and the other side fuel injection valve 24B are attached to the one side intake manifold pipe 6A and the other side intake manifold pipe 6B. A fuel supply pipe 26 opened in the fuel tank 25 is connected to the one side fuel injection valve 24A and the other side fuel injection valve 24B. A fuel pump 27 is provided in the middle of the fuel supply pipe 26.
The one side exhaust manifold pipe 15 </ b> A and the intake side collecting pipe 7 are connected by an exhaust gas recirculation pipe 28. In the middle of the exhaust gas recirculation pipe 28, an EGR valve 29 is provided.
The one side spark plug 30A and the other side spark plug 30B are attached to the one side cylinder head 4A and the other side cylinder head 4B.

The throttle valve actuator 12, the one-side fuel injection valve 24 </ b> A / the other-side fuel injection valve 24 </ b> B, the fuel pump 27, and the EGR valve 29 communicate with a control means (ECU) 31 that constitutes a control device in the internal combustion engine 1. ing.
The control means 31 includes a crank angle sensor 32 that is attached to the cylinder block 2 and functions as a rotation speed detection means that can detect the crank angle of the crankshaft 3 as the engine rotation speed, a one-side spark plug 30A, and the like. An ignition regulator 34 connected to the ignition coil 33 to which the side spark plug 30B is connected, and an engine load detection that is attached to the intake pipe 10 so as to detect the intake air amount and detects the intake air amount as an engine load (rate) An air flow meter 35 that functions as a means, a throttle opening sensor 36 that detects the throttle opening of the throttle valve 13, and an upstream catalytic converter 18 that is attached to the upstream catalytic converter 18 so as to detect the temperature of the upstream catalyst 17 as a catalyst. There is communication with a catalyst temperature sensor 37 which is used during the adaptation of the conditions.
Further, the control means 31 is in communication with an accelerator opening sensor 39 for detecting the depression state of the accelerator pedal 38 and a vehicle speed detecting means 40 for detecting the vehicle speed.
Furthermore, the control means 31 includes a map M for calculating the catalyst temperature increase (gradient) from the engine speed and the engine load (rate). Since this map M has a catalyst temperature increase (gradient) that differs depending on the internal combustion engine 1 and the vehicle specifications (displacement, shape of the internal combustion engine 1, nature of the catalyst 7, etc.), the catalyst temperature is determined after investigation. The increase (gradient) can be changed, and is set so that the catalyst temperature increase (gradient) decreases as the engine speed and engine load (rate) decrease.

The control means 31 estimates the catalyst temperature based on the engine load detected from the engine speed detected by the crank angle sensor 32 serving as the rotational speed detection means and the intake air amount detected by the air flow meter 35 serving as the load detection means. A catalyst temperature estimation means 31A and a throttle opening degree control means 31B for controlling the throttle opening degree of the throttle valve 13 are provided, and a catalyst temperature (estimated catalyst temperature) estimated by the catalyst temperature estimation means 31A is set in advance. When the (catalyst allowable temperature) is exceeded, the throttle valve control means 31B controls the opening and closing of the throttle valve 13 so that the internal combustion engine 1 is in an idling operation state. In this case, the intake air amount detected by the air flow meter 35 is used by the control means 31 to calculate the engine load (rate) applied to the internal combustion engine 1. Further, the control means 31 always measures the engine speed and the engine load (rate), and calculates the estimated catalyst temperature using an estimation formula for the catalyst temperature rise (gradient).
Further, the control means 31 estimates the travel air volume from the vehicle speed detected by the vehicle speed detection means 40 by the catalyst temperature estimation means 31A, and subtracts the catalyst temperature drop (gradient) due to the estimated travel air volume. Thus, in order to predict the temperature displacement of the exhaust system, it is possible to further improve the accuracy of the temperature displacement of the exhaust system by considering the cooling state by the traveling wind and the like.
Further, the control means 31 includes a fuel cut (F / C) means 31C for stopping the fuel supply to the internal combustion engine 1 when a predetermined condition is satisfied during deceleration, and a timer 31D for measuring time. Then, the time during which the fuel supply is stopped by the fuel cutting means 31C is measured, and the catalyst temperature increase (gradient) calculated from the measured time is added. Thus, in order to predict the temperature displacement of the exhaust system, it is possible to further increase the accuracy of the temperature displacement of the exhaust system by calculating the temperature rise during the fuel cut (F / C) during deceleration. It becomes.

Next, the control according to this embodiment will be described based on the flowchart of FIG. 1 executed in a catalyst temperature reduction routine including a catalyst temperature estimation routine. This catalyst temperature reduction routine estimates an increase in the catalyst temperature based on the operating state parameter of the internal combustion engine 1 that causes overheating of the exhaust system, and lowers the catalyst temperature when the catalyst temperature exceeds a set value. It is.
As shown in FIG. 1, when the program of the control means 31 is started (step A01), first, the catalyst temperature estimation routine is started, and the estimated catalyst temperature (n)
Estimated catalyst temperature (n) = estimated catalyst temperature (n−1) + catalyst temperature rise (gradient)
(Step A02).
The catalyst temperature increase (gradient) is obtained from a map M in the control means 31 shown in FIG.
Then, it is determined whether or not the vehicle speed (Vs) is zero (0) (step A03).
If this step A03 is NO, the estimated catalyst temperature is
Estimated catalyst temperature = estimated catalyst temperature (n) −traveling wind temperature drop (gradient)
(Step A04). That is, in this step A04, when estimating the catalyst temperature, the temperature drop due to the travel air volume is subtracted.
Here, the running wind temperature drop (gradient) is
Traveling air temperature drop (gradient) = Traveling air volume (converted into vehicle speed) x Cooling temperature (gradient)
Is required.
If YES in step A03, or after the processing in step A04, it is determined whether or not a fuel cut (F / C) is in progress (step A05).
If this step A05 is YES, the estimated catalyst temperature is
Estimated catalyst temperature = estimated catalyst temperature (n) + fuel cut (F / C) temperature rise (gradient)
(Step A06). That is, in this step A06, the temperature increase due to the fuel cut is added.
Here, the fuel cut (F / C) temperature rise (gradient) is
Fuel cut (F / C) temperature rise (gradient) = Fuel cut (F / C) start-up time x Upper temperature rise (gradient)
Is required.
When Step A05 is NO or after the processing of Step A06, the catalyst temperature estimation routine is terminated.
Then, it is determined whether or not the estimated catalyst temperature <the set value (catalyst allowable temperature) (step A07). That is, in step A07, it is determined whether or not the estimated catalyst temperature is equal to or lower than a set value (catalyst allowable temperature).
If this step A07 is NO and the estimated catalyst temperature exceeds the set value (catalyst allowable temperature), it is determined whether or not throttle opening> air amount required opening (step A08).
When this step A08 is YES, the throttle valve 13 is closed so that the throttle opening becomes the required air amount opening (throttle opening that becomes the idling air amount) (throttle opening = air amount required opening). (Step A09). Thereby, the internal combustion engine 1 is controlled to an idling state, and the temperature of the exhaust system is lowered.
On the other hand, if step A07 is YES and the estimated catalyst temperature is equal to or lower than the set value (catalyst allowable temperature), the throttle opening is not controlled and the program is returned (step A10).
If step A08 is NO or after the process of step A09, the program is returned (step A10).

As a result, in this embodiment, when the catalyst temperature estimated by the catalyst temperature estimating means 31A of the control means 31 exceeds a preset set value, the throttle opening control means 31B causes the internal combustion engine 1 to perform idling operation. Since the throttle valve is controlled to open and close so that the engine is in a state, the engine rotation of the internal combustion engine 1 is compared to the conventional case where the depression of the accelerator pedal is detected to prevent the exhaust system from exceeding the allowable temperature. Since the catalyst temperature is estimated from the number and the engine load, the catalyst temperature can be estimated accurately, and the exhaust system can be protected accurately.
Further, the catalyst temperature estimating means 31A of the control means 31 estimates the traveling air volume from the vehicle speed detected by the vehicle speed detecting means 40, and subtracts the catalyst temperature drop due to the estimated traveling air volume, so that the catalyst temperature is accurately determined. Can be estimated well.
Further, the catalyst temperature estimation means 31A of the control means 31 measures the time during which the fuel supply is stopped by the fuel cut means 31C, and adds the amount of increase in the catalyst temperature calculated from the measured time, thereby adding the catalyst. The temperature can be accurately estimated.

  In the examples, the catalyst temperature is taken as an example. However, by examining in advance the temperature rise gradient and the limit value of a portion where there is a risk of thermal degradation or damage due to heat generation of the internal combustion engine, It is possible to deal with other parts.

  The control apparatus for an internal combustion engine according to the present invention can be applied to various vehicles.

1 Internal combustion engine 3 Crankshaft 9 Intake passage 13 Throttle valve 17 Upstream catalyst (catalyst)
19 exhaust passage 31 control means 31A catalyst temperature estimation means 31B throttle opening control means 31C fuel cut (F / C) means 31D timer 32 crank angle sensor (engine speed detection means)
35 Air flow meter (engine load detection means)
40 Vehicle speed detection means

Claims (3)

  A throttle valve disposed in the intake passage of the internal combustion engine, a catalyst disposed in the exhaust passage of the internal combustion engine, an engine speed detecting means for detecting the engine speed of the internal combustion engine, and Engine load detecting means for detecting engine load is provided, and control means for controlling the internal combustion engine based on the engine speed detected by the engine speed detecting means and the engine load detected by the engine load detecting means is provided. In the control apparatus for an internal combustion engine, the control means is a catalyst temperature estimating means for estimating a catalyst temperature based on the engine speed detected by the engine speed detecting means and the engine load detected by the engine load detecting means. And throttle opening control means for controlling the throttle opening of the throttle valve, and the catalyst estimated by the catalyst temperature estimation means If the degree exceeds a predetermined set value, the control apparatus for an internal combustion engine wherein the internal combustion engine by the throttle opening control means and wherein the opening and closing controls the throttle valve so that the idling state.   The control means communicates with a vehicle speed detecting means for detecting a vehicle speed, and the catalyst temperature estimating means estimates the traveling air volume from the vehicle speed detected by the vehicle speed detecting means, and the catalyst temperature drop due to the estimated traveling air volume. 2. The control device for an internal combustion engine according to claim 1, wherein the minute is subtracted.   The control means includes fuel cut means for stopping fuel supply to the internal combustion engine, and the catalyst temperature estimation means measures the time during which fuel supply is stopped by the fuel cut means, and this measurement is performed. 2. The control apparatus for an internal combustion engine according to claim 1, wherein a catalyst temperature increase calculated from the time is added.

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