JP2021188510A - Internal combustion engine control device - Google Patents

Abstract

To provide an internal combustion engine control device capable of accurately calculating a flow rate of blow-by gas.SOLUTION: A control device comprises: an acquisition section acquiring a throttle opening which is an opening of a throttle valve, intake pipe pressure which is pressure in an intake pipe, a deviation value between an actual intake air amount which is a measurement value of an amount of air introduced into the intake pipe and an estimated intake air amount which is an estimated value, and a flow rate of blow-by gas; and a storage section storing each previous values of the throttle opening, the intake pipe pressure, the deviation value and the flow rate of the blow-by gas and latest values thereof. When an absolute value of a difference between the previous throttle opening and the latest throttle valve opening is smaller than a threshold, an absolute value of a difference between the previous intake pipe pressure and the latest intake pipe pressure is larger than a threshold, and an absolute value of a difference between the previous deviation value and the latest deviation value is larger than a threshold, the control device calculates an update value on the basis of the difference between the previous deviation value and the latest deviation value and calculates the latest value of the flow rate of the blow-by gas by adding the update value to the previous flow rate of the blow-by gas.SELECTED DRAWING: Figure 4

Description

The present invention relates to a control device for an internal combustion engine.

There is a technique for estimating the blow-by gas flow rate based on the intake air amount, the throttle valve opening degree, and the intake pipe pressure (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2010-096032

The blow-by gas flow rate with respect to the intake pipe pressure may vary greatly due to variations in the parts constituting the blow-by gas processing device and changes over time. In such a case, it may not be possible to accurately calculate the blow-by gas flow rate.

Therefore, an object of the present invention is to provide a control device for an internal combustion engine capable of accurately calculating a blow-by gas flow rate.

The above object is a control device for an internal combustion engine provided with a blow-by gas processing device, and has a throttle opening which is an opening degree of a throttle valve provided in an intake pipe, an intake pipe pressure which is a pressure in the intake pipe, and the intake air. The acquisition unit that acquires the deviation value between the actual intake air amount, which is the measured value of the intake air amount introduced into the pipe, and the assumed intake air amount, which is the assumed value, and the blow-by gas flow rate, the throttle opening, and the intake pipe pressure. , The previous value which is the value previously acquired for each of the deviation value and the blow-by gas flow rate, and the value acquired this time for the throttle opening, the intake pipe pressure, and the deviation value. The absolute value of the difference between the previous value and the current value of the throttle opening and the storage unit that stores the value is smaller than the predetermined threshold value, and the absolute value of the difference between the previous value and the current value of the intake pipe pressure is the predetermined threshold value. When the absolute value of the difference between the previous value and the current value of the deviation value is larger than a predetermined threshold value, the update amount is calculated based on the difference between the previous value and the current value of the deviation value, and the blow-by This can be achieved by a control device for an internal combustion engine provided with a calculation unit that calculates the current value of the blow-by gas flow rate by adding the update amount to the previous value of the gas flow rate.

According to the present invention, it is possible to provide a control device for an internal combustion engine capable of accurately calculating a blow-by gas flow rate.

FIG. 1 is a schematic configuration diagram of an internal combustion engine. FIG. 2 is a graph showing the characteristics of the throttle opening degree and the intake air amount. FIG. 3 is a graph showing the characteristics of the intake pipe pressure and the blow-by gas flow rate. FIG. 4 is a flowchart showing an example of PCV flow rate calculation control executed by the ECU. FIG. 5 is a map that defines the relationship between the difference between the current value and the previous value of the divergent air amount and the update amount of the PCV flow rate.

FIG. 1 is a schematic configuration diagram of an internal combustion engine 10. As shown in FIG. 1, a throttle mechanism 12 is provided in the intake pipe 11 of the internal combustion engine 10. The throttle mechanism 12 includes a throttle valve 13 and a throttle motor 14. Then, the opening degree of the throttle valve 13 is adjusted through the drive control of the throttle motor 14, whereby the amount of air sucked into the combustion chamber 15 through the intake pipe 11 is adjusted. Further, the intake pipe 11 is provided with a fuel injection valve 16. The fuel injection valve 16 is driven to open the valve through its operation control to inject fuel into the intake port.

In the combustion chamber 15 of the internal combustion engine 10, an air-fuel mixture composed of intake air and injected fuel is ignited and burned. This combustion causes the piston 18 to reciprocate and the crankshaft 19 to rotate. Then, the air-fuel mixture after combustion is sent out from the combustion chamber 15 to the exhaust pipe 20 as exhaust gas.

The internal combustion engine 10 is provided with an oil tank 21 for storing oil, and a pump 22 is provided inside the oil tank 21. Then, by being pumped by the pump 22, the oil in the oil tank 21 is supplied to each operating unit of the internal combustion engine 10. The oil after being lubricated for each moving part runs down the inner wall of the internal combustion engine 10 and is stored in the oil tank 21.

The internal combustion engine 10 is provided with a fuel vapor processing device 30. The fuel steam processing device 30 is provided by a canister 31 that adsorbs fuel steam generated in the fuel tank 23, a vapor passage 32 that communicates the fuel tank 23 and the canister 31, and a throttle valve 13 in the intake pipe 11 of the internal combustion engine 10. It is provided with a portion on the downstream side in the intake flow direction (hereinafter, simply the downstream side) and a purge passage 33 that communicates with the canister 31.

The fuel vapor generated in the fuel tank 23 is sent to the canister 31 through the vapor passage 32. The canister 31 is provided with an adsorbent inside, and the fuel vapor from the fuel tank 23 is condensed into the fuel of the liquid phase and adsorbed by the adsorbent to temporarily store the fuel vapor. The canister 31 has a configuration capable of re-disengaging the fuel adsorbed on the adsorbent in this way.

A purge control valve 34 is provided in the middle of the purge passage 33 that communicates the canister 31 and the intake pipe 11, and an electromagnetic control valve is adopted as the purge control valve 34. Further, the canister 31 is connected to an atmosphere introduction passage 35 for introducing the atmosphere into the canister 31.

The fuel vapor processing device 30 functions as follows. That is, first, the fuel vapor generated in the fuel tank 23 is sent to the canister 31 through the vapor passage 32 and is adsorbed by the adsorbent of the canister 31. Then, when the purge control valve 34 is opened through the operation control (purge control) of the purge control valve 34 based on the operating state of the internal combustion engine 10, the pressure on the downstream side of the throttle valve 13 in the intake pipe 11 (intake pressure " <Atmospheric pressure ") is supplied to the canister 31 via the purge passage 33. On the other hand, atmospheric pressure is introduced into the canister 31 via the atmospheric introduction passage 35. As a result, the fuel adsorbed on the adsorbent of the canister 31 becomes fuel vapor and is released to the intake pipe 11.

The internal combustion engine 10 is provided with a fresh air introduction pipe 41 that communicates a portion of the intake pipe 11 upstream of the throttle valve 13 in the intake flow direction (hereinafter, simply upstream side) with the inside of the crankcase 24. The internal combustion engine 10 is also provided with a gas discharge pipe 42 that communicates a portion of the intake pipe 11 downstream of the throttle valve 13 with the inside of the crankcase 24. Further, the gas discharge pipe 42 is provided with a PCV (Positive Crankcase Verification) valve 43. In the present embodiment, the blow-by gas treatment device 40 for discharging and processing the blow-by gas in the crankcase 24 to the intake pipe 11 is configured by the fresh air introduction pipe 41, the gas discharge pipe 42 and the PCV valve 43. .. Blow-by gas is gas (including fuel) that leaks from the combustion chamber 15 into the crankcase 24 through the gap between the piston ring 25 of the internal combustion engine 10 and the inner wall surface 26 of the cylinder in the compression stroke and expansion stroke of the internal combustion engine 10. That is.

In this blow-by gas processing device 40, basically, by utilizing the difference between the intake pressure and the pressure in the crankcase 24, the blow-by gas in the crankcase 24 is discharged to the intake pipe 11 through the gas discharge pipe 42. .. Further, by utilizing the difference between the pressure in the crank case 24, which decreases with the discharge of gas to the intake pipe 11, and the pressure on the upstream side of the throttle valve 13 in the intake pipe 11, fresh air in the intake pipe 11 is used. Is introduced into the crank case 24 through the fresh air introduction pipe 41. The PCV valve 43 is a one-way valve (check valve) that enables ventilation from the crankcase 24 to the intake pipe 11 in only one direction. When a negative pressure is generated in the intake pipe 11, the PCV valve 43 opens, and blow-by gas is discharged from the inside of the crankcase 24 to the intake pipe 11 through the gas discharge pipe 42.

The ECU (Electronic Control Unit) 27 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory). The ECU 27 performs various calculations based on the detection signals of various sensors by executing a program stored in the RAM or ROM, and based on the calculation results, throttle control, fuel injection control, purge control, etc. are performed. Perform various controls. The ECU 27 is an example of a control device for an internal combustion engine.

Examples of various sensors include a crank sensor for detecting the rotation speed (engine rotation speed) of the crankshaft 19, an accelerator sensor for detecting the amount of depression of the accelerator pedal (not shown), and an opening degree of the throttle valve 13. A throttle sensor for detection is provided. Further, an air flow meter for detecting the amount of intake air, which is the amount of air flowing upstream from the connection portion of the intake pipe 11 with the fresh air introduction pipe 41, and a temperature sensor for detecting the temperature of the engine cooling water. A pressure sensor or the like for detecting the intake pipe pressure, which is the pressure of the portion downstream of the throttle valve 13 in the intake pipe 11, is also provided.

The ECU 27 learns the characteristics of the throttle opening degree and the intake air amount. FIG. 2 is a graph showing the characteristics of the throttle opening degree and the intake air amount. The vertical axis shows the intake air amount [% · rpm], and the horizontal axis shows the throttle opening [°]. Note that [% · rpm] is obtained by multiplying the load factor [%] of the internal combustion engine 10 by the rotation speed [rpm] of the internal combustion engine 10. FIG. 2 shows the central characteristics and the individual characteristics of the vehicle. The median characteristic indicates the median value of the above-mentioned characteristics in various vehicles acquired from experimental results and the like, and is stored in advance in the ROM of the ECU 27 from the beginning. On the other hand, the vehicle individual characteristic is a characteristic obtained by learning the ratio of the actual intake air amount to the intake air amount indicated by the central characteristic. In the example of FIG. 2, the case where the intake air amount is smaller in the vehicle individual characteristic than in the central characteristic is shown. By performing such learning, it is possible to obtain appropriate characteristics in response to the type of vehicle, aging, and the like. Also, the property update in this learning is not done during the trip.

Here, due to changes in environmental conditions and the like, the assumed intake air amount obtained from the individual characteristics of the vehicle and the actual intake air amount, which is the actual intake air amount, may deviate from each other during the trip. Such a case is dealt with by feedback-controlling the divergent air amount, which is the difference between the actual intake air amount and the assumed intake air amount.

FIG. 3 is a graph showing the characteristics of the intake pipe pressure and the blow-by gas flow rate. The blow-by gas flow rate is the flow rate of blow-by gas discharged from the crankcase 24 to the intake pipe 11 through the gas discharge pipe 42. The blow-by gas flow rate with respect to the intake pipe pressure also varies due to variations in the parts constituting the blow-by gas processing apparatus 40, changes over time, and the like. Therefore, the convergence value of the above-mentioned divergent air amount also differs depending on the intake pipe pressure, and the variation becomes large. In this embodiment, the blow-by gas flow rate is calculated accurately by the method described later. In the following, the blow-by gas flow rate will be referred to as a PCV flow rate.

Next, the PCV flow rate calculation control executed by the ECU 27 will be described. FIG. 4 is a flowchart showing an example of PCV flow rate calculation control executed by the ECU 27. This control is repeatedly executed. In the following description, a plurality of values of different types acquired this time are referred to as current values, and a plurality of values of different types acquired last time are referred to as previous values. The different types of current values are values acquired at substantially the same timing, and similarly, a plurality of previous values are also acquired at substantially the same timing. These values are constantly taken into the ECU 27 from various sensors and the like and stored in the RAM of the ECU 27.

First, it is determined whether or not the absolute value of the difference between the current value and the previous value of the throttle opening is smaller than the threshold value A (step S1). Here, the threshold value A is set to a small value such that the previous value and the current value of the throttle opening can be regarded as substantially the same. If No in step S1, this control ends.

In the case of Yes in step S1, it is determined whether or not the absolute value of the difference between the current value and the previous value of the intake pipe pressure is larger than the threshold value B (step S2). Here, the threshold value B is set to a value indicating that the difference between the current value and the previous value of the intake pipe pressure has a large variation in the PCV flow rate. If No in step S2, this control ends.

Here, the case of Yes in step S2 is the case of Yes in both steps S1 and S2. This is a case where the current value and the previous value of the intake pipe pressure are significantly different even though the current value and the previous value of the throttle opening are almost the same. In the case of Yes in step S2, it is determined whether or not the absolute value of the difference between the current value and the previous value is larger than the threshold value C with respect to the divergent air amount divergent between the actual intake air amount and the assumed intake air amount (step). S3). Here, the threshold value C is set to a value indicating that the difference between the current value and the previous value of the divergent air amount is large. If No in step S3, this control ends.

If Yes in step S3, the update amount of the PCV flow rate is calculated (step S4). FIG. 5 is a map defining the relationship between the difference between the current value and the previous value of the above-mentioned divergent air amount and the update amount of the PCV flow rate. The vertical axis shows the update amount of the PCV flow rate, and the horizontal axis shows the value obtained by subtracting the previous value from the current value of the divergent air amount. This map is defined based on the experimental results and the like and is stored in advance in the ROM of the ECU 27. The ECU 27 calculates the update amount with reference to this map. In this map, in the range where the value obtained by subtracting the previous value from the current value of the divergent air amount is larger than 0, the update amount increases as the value obtained by subtracting the previous value from the current value of the divergent air amount increases, and the divergent air amount increases. In the range where the value obtained by subtracting the previous value from the current value of the amount is smaller than 0, the amount of renewal decreases as the value obtained by subtracting the previous value from the current value of the divergent air amount decreases. Further, the renewal amount is substantially directly proportional to, but not limited to, the value obtained by subtracting the previous value from the current value of the divergent air amount. Further, the update amount may be calculated by an arithmetic expression.

Next, the current value of the PCV flow rate is calculated based on the renewal amount calculated in this way, the previous value of the PCV flow rate, and the current value of the intake pipe pressure (step S5). Specifically, the value obtained by adding the update amount to the previous value of the PCV flow rate is calculated as the current value of the PCV flow rate at the current value of the intake pipe pressure. The current value of the PCV flow rate calculated in this way is reflected in the characteristics of the intake pipe pressure and the PCV flow rate as shown in FIG. 3 described above together with the current value of the intake pipe pressure. The previous value of the PCV flow rate is the previous value calculated by the present PCV flow rate calculation control, but is not limited to this, and the characteristics of the PCV flow rate and the intake pipe pressure in various vehicles acquired from the experimental results and the like are not limited to this. It may be the PCV flow rate obtained by the median value.

As described above, the PCV flow rate can be calculated accurately. Thereby, various values can be accurately calculated based on the PCV flow rate, and various control targets can be accurately controlled based on the PCV flow rate.

The order of steps S1 and S2 does not matter.

Although the examples of the present invention have been described in detail above, the present invention is not limited to such specific examples, and various modifications and variations are made within the scope of the gist of the present invention described in the claims. It can be changed.

10 Internal combustion engine 11 Intake pipe 12 Throttle mechanism 13 Throttle valve 14 Throttle motor 15 Combustion chamber 16 Fuel injection valve 18 Piston 19 Crankshaft 20 Exhaust pipe 21 Oil tank 22 Pump 23 Fuel tank 24 Crank case 25 Piston ring 26 Cylinder inner wall surface 27 ECU
30 Fuel steam treatment device 31 Canister 32 Vapor passage 33 Purge passage 34 Purge control valve 35 Air introduction passage 40 Blow-by gas treatment device 41 Fresh air introduction pipe 42 Gas discharge pipe 43 PCV valve

Claims (1)

A control device for an internal combustion engine equipped with a blow-by gas processing device.
Throttle opening, which is the opening of the throttle valve provided in the intake pipe, intake pipe pressure, which is the pressure in the intake pipe, and actual intake air amount and assumed value, which are measured values of the intake air amount introduced into the intake pipe. The acquisition unit that acquires the deviation value of the assumed intake air amount and the blow-by gas flow rate, which are
The throttle opening, the intake pipe pressure, the deviation value, and the previous value which is the previously acquired value of the blow-by gas flow rate, and the throttle opening, the intake pipe pressure, and the deviation value, respectively. The storage unit that stores the current value, which is the value acquired this time,
The absolute value of the difference between the previous value and the current value of the throttle opening is smaller than the predetermined threshold value, and the absolute value of the difference between the previous value and the current value of the intake pipe pressure is larger than the predetermined threshold value. When the absolute value of the difference between the previous value and the current value is larger than a predetermined threshold value, the update amount is calculated based on the difference between the previous value and the current value of the deviation value, and the update is made to the previous value of the blow-by gas flow rate. A control device for an internal combustion engine, comprising a calculation unit that adds an amount to calculate the current value of the blow-by gas flow rate.

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