JP7690928B2 - Control device for internal combustion engine - Google Patents

Description

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

Internal combustion engines equipped with turbochargers are known (for example, Patent Document 1).

International Publication No. 2013/080600

The turbocharger compressor deteriorates over time. Deterioration means that deposits build up on the turbocharger compressor, causing the compressor's efficiency to decrease due to the deposits. Therefore, the objective of this invention is to provide an internal combustion engine control device that can determine compressor deterioration.

The above object can be achieved by a control device for an internal combustion engine equipped with a turbocharger, the turbocharger having a compressor, the control device including: a decrease amount acquisition unit that acquires an amount of decrease in efficiency of the compressor based on a temperature of the compressor and a concentration of insoluble components in oil; and a determination unit that determines whether the turbocharger has deteriorated based on the amount of decrease, wherein, when the temperature is a first temperature and the concentration of insoluble components is a first concentration, the decrease amount acquisition unit acquires a rate of decrease in efficiency based on the first temperature and the first concentration, the decrease amount acquisition unit acquires the amount of decrease by multiplying the rate of decrease at the first temperature and the first concentration by a time during which the temperature is the first temperature and the concentration of insoluble components is the first concentration, the decrease amount acquisition unit adds up the amounts of decrease corresponding to the temperature and the concentration of insoluble components, and the determination unit determines that the turbocharger has deteriorated when the added amount of decrease is equal to or greater than a threshold value .

It is possible to provide a control device for an internal combustion engine that can determine compressor deterioration.

FIG. 1 is a schematic diagram illustrating an engine system. FIG. 2 is a diagram illustrating the rate of efficiency decrease. FIG. 3 is a flowchart illustrating a process executed by the ECU.

Figure 1 is a schematic diagram illustrating an engine system 100. The engine system 100 includes an internal combustion engine 10, a turbocharger 18, and an ECU (Electronic Control Unit) 50.

The internal combustion engine 10 is, for example, a gasoline engine or a diesel engine, and includes a piston 17, an intake valve 30, an exhaust valve 32, and a fuel injector 34. A combustion chamber 27 is formed in the bore of the internal combustion engine 10. The fuel injector 34 is provided in the intake passage 12, but may also be provided in the combustion chamber 27. The piston 17 is disposed inside the combustion chamber 27 and is connected to a crankshaft 19.

An intake passage 12 and an exhaust passage 14 are connected to the internal combustion engine 10. In the intake passage 12, an air cleaner 20, an air flow meter 22, an intercooler 25, a throttle valve 26, and a fuel injection valve 34 are provided in this order from the upstream side. A catalyst 28 is provided in the exhaust passage 14.

The turbocharger 18 includes a turbine 18a and a compressor 18b. The turbine 18a and the compressor 18b are connected to each other. The turbine 18a is located in the exhaust passage 14 upstream of the catalyst 28. The compressor 18b is located in the intake passage 12 downstream of the air flow meter 22 and upstream of the intercooler 25. The turbine 18a and the compressor 18b are housed inside a housing (not shown).

A bypass passage 13 that bypasses the compressor 18b is connected to the intake passage 12, and a valve 11 is provided in the bypass passage 13. When the accelerator is OFF, air is bypassed from downstream to upstream of the compressor 18b through the bypass passage 13. A bypass passage 15 that bypasses the turbine 18a is connected to the exhaust passage 14, and a valve 16 is provided in the bypass passage 15.

A PCV (Positive Crankcase Ventilation) passage 23 is connected to the internal combustion engine 10 and to a position in the intake passage 12 upstream of the compressor 18b of the turbocharger 18. The blow-by gas is returned to the intake passage 12 through the PCV passage 23 and flows through the intake passage 12 together with air. Oil is mixed into the blow-by gas. Deposits are generated from the insoluble matter contained in the oil and adhere to the compressor 18b. The adhesion of deposits reduces the efficiency of the turbocharger 18.

The intake air passes through the intake passage 12, is purified by the air cleaner 20, and is cooled by the intercooler 25. When the intake valve 30 opens, the intake air is introduced into the combustion chamber 27 of the internal combustion engine 10. The fuel injection valve 34 injects fuel into the combustion chamber 27. When an ignition plug (not shown) ignites, the mixture of intake air and fuel is burned in the combustion chamber 27. The piston 17 reciprocates up and down in the combustion chamber 27, and the driving force is transmitted to the crankshaft 19, causing the vehicle to move.

When the exhaust valve 32 opens, the exhaust gas generated by the combustion is discharged into the exhaust passage 14. The exhaust gas is purified by the catalyst 28 in the exhaust passage 14 and then discharged. The catalyst 28 is, for example, a three-way catalyst, and purifies carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and other substances contained in the exhaust gas.

When the exhaust gas is introduced into the turbine 18a of the turbocharger 18, the turbine 18a rotates, and the compressor 18b connected to the turbine 18a also rotates. The rotation of the compressor 18b supercharges the intake air, and the intake air is sent into the combustion chamber 27 of the internal combustion engine 10 at a higher pressure than the intake air upstream of the compressor 18b.

The engine system 100 has an air flow meter 22, a vehicle speed sensor 40, pressure sensors 42 and 43, temperature sensors 44 and 46, and a water temperature sensor 47. The air flow meter 22 detects the flow rate of intake air. The vehicle speed sensor 40 detects the speed of the vehicle (vehicle speed) on which the engine system 100 is mounted. The pressure sensor 42 detects atmospheric pressure. The pressure sensor 43 detects the pressure (supercharging pressure) of the air supercharged by the supercharger 18. The temperature sensor 44 detects the temperature of the outside air. The temperature sensor 46 detects the temperature inside the intake passage 12. The water temperature sensor 47 detects the temperature of the cooling water for the internal combustion engine 10.

The ECU 50 is a control device for the internal combustion engine 10. The ECU 50 includes an arithmetic unit such as a CPU (Central Processing Unit) and storage devices such as a RAM (Random Access Memory) and a ROM (Read Only Memory). The ECU 50 performs various controls by executing programs stored in the ROM and the storage devices.

The ECU 50 controls the opening of the throttle valve 26 and the opening of valves 11 and 16. Valve 11 is an air bypass valve (ABV) that opens when the accelerator is off to allow supercharged air to escape. The ECU 50 switches fuel injection from the fuel injection valve 34 on and off to control the amount of fuel injected.

The ECU 50 obtains the intake air flow rate from the air flow meter 22, the vehicle speed from the vehicle speed sensor 40, and the fuel injection amount. The ECU 50 obtains the atmospheric pressure from the pressure sensor 42, and obtains the pressure of the air introduced into the compressor 18b based on the atmospheric pressure. The ECU 50 obtains the boost pressure from the pressure sensor 43. The ECU 50 obtains the outside air temperature from the temperature sensor 44, the air temperature in the intake passage 12 from the temperature sensor 46, and the water temperature from the water temperature sensor 47. From this information, the ECU 50 calculates the component temperature (housing temperature) of the compressor 18b and the insoluble matter concentration of the oil.

The ECU 50 functions as a decrease amount acquisition unit that acquires the amount of decrease in efficiency of the compressor 18b, and as a determination unit that determines whether the turbocharger 18 has deteriorated based on the amount of decrease.

The adhesion of deposits to the compressor 18b reduces efficiency. The decrease in efficiency is sometimes described as deterioration of the turbocharger 18. The amount of deposits produced depends on the temperature of the compressor 18b and the concentration of insoluble matter contained in the oil. The oil is mixed into the blow-by gas. The blow-by gas is introduced into the compressor 18b of the turbocharger 18 together with the intake air. When the temperature of the compressor 18b rises, the oil becomes more likely to evaporate. When the oil evaporates, the insoluble matter contained in the oil condenses and hardens, and adheres to the compressor 18b as deposits. The efficiency of the compressor 18b decreases when deposits adhere to the compressor 18b. The higher the temperature of the housing and the higher the concentration of insoluble matter, the more likely it is that deposits will occur and the easier it is for efficiency to decrease.

Figure 2 is a diagram illustrating the rate of efficiency decline. The horizontal axis represents the temperature of the housing of compressor 18b. The vertical axis represents the rate of efficiency decline of compressor 18b. The dashed line represents an example where the insoluble matter concentration is 0.3 wt%. The dotted line represents an example where the insoluble matter concentration is 0.5 wt%. The solid line represents an example where the insoluble matter concentration is 1 wt%.

As shown in Figure 2, when the housing temperature is below T0, the rate of efficiency decline is zero. This is because deposits are unlikely to occur when the temperature is below T0. When the temperature is above T0, deposits are formed and the rate of efficiency decline increases above zero. Compared to the 0.3 wt% example shown by the dashed line, the rate of efficiency decline is greater in the 0.5 wt% example shown by the dotted line. Compared to the dashed and dotted line examples, the rate of efficiency decline is greater in the 1 wt% example shown by the solid line. The higher the concentration of insoluble matter, the greater the amount of deposits generated and the greater the decline in efficiency.

Figure 3 is a flow chart illustrating the process executed by the ECU 50. The ECU 50 estimates the housing temperature T (step S10). The ECU 50 calculates the air temperature at the outlet of the compressor 18b from, for example, the pressure at the inlet of the compressor 18b, the boost pressure, the intake air temperature, the intake air flow rate, and the vehicle speed. The ECU 50 calculates the housing temperature T based on the air temperature at the outlet.

The ECU 50 estimates the concentration of insoluble matter in the oil (step S12). For example, the amount of sludge precursors is estimated based on the fuel injection amount and water temperature, and the concentration of insoluble matter is estimated from the amount of precursors.

The ECU 50 estimates the amount of decrease in efficiency Δη of the compressor 18b based on the temperature T of the housing and the concentration of insoluble matter (step S14). For example, the ECU 50 obtains the rate of decrease in efficiency as shown in FIG. 2 from the temperature T and the concentration of insoluble matter. The amount of decrease in efficiency is obtained by multiplying the time during which the temperature T and the concentration of insoluble matter were at a specific value by the rate of decrease in efficiency corresponding to the temperature and the concentration of insoluble matter. The ECU 50 calculates the amount of decrease Δη by adding up the amount of decrease in efficiency from the start of operation of the internal combustion engine 10 to the present time, for example. The ECU 50 determines whether the amount of decrease Δη is equal to or greater than the threshold value Δηth (step S16). If the determination is negative (No), the process ends. If the determination is positive (Yes), the ECU 50 determines that the compressor 18b is deteriorated (step S18). After step S18, the process ends.

According to this embodiment, the ECU 50 obtains the amount of decrease Δη in the efficiency of the compressor 18b based on the temperature T of the housing of the compressor 18b and the concentration of insoluble matter in the oil. If the amount of decrease Δη is equal to or greater than the threshold value Δηth, the ECU 50 determines that the compressor 18b has deteriorated. The deterioration of the compressor 18b can be accurately determined.

The higher the temperature of the housing of the compressor 18b, the easier it is for the oil to evaporate. The insoluble parts of the oil adhere to the housing as deposits. In other words, the higher the temperature of the housing and the higher the concentration of insoluble parts, the easier it is for deposits to occur. The amount of efficiency loss due to deposits also increases. According to this embodiment, the ECU 50 obtains the rate of efficiency loss based on the temperature of the housing and the concentration of insoluble parts. The ECU 50 obtains the amount of efficiency loss by multiplying the rate of efficiency loss by time. The amount of efficiency loss can be obtained in real time according to changes in temperature and the concentration of insoluble parts. The ECU 50 can grasp the amount of efficiency loss since the start of operation by accumulating the amount of efficiency loss in, for example, an on-board storage device. The ECU 50 may transmit the amount of efficiency loss to an external server, etc.

The ECU 50 estimates the air temperature at the outlet of the compressor 18b from the inlet pressure of the compressor 18b, the boost pressure, the intake air temperature, the intake air flow rate, and the vehicle speed. The ECU 50 estimates the housing temperature based on the outlet air temperature. The ECU 50 estimates the concentration of insoluble matter from the fuel injection amount and the water temperature. That is, the ECU 50 obtains the housing temperature and the concentration of insoluble matter based on information obtained from the vehicle, and obtains the amount of efficiency reduction based on the housing temperature and the concentration of insoluble matter. The amount of efficiency reduction according to the vehicle condition is obtained. The accuracy of deterioration determination is improved. Since there is no need to add a sensor to measure the housing temperature and a sensor to measure the concentration of insoluble matter, an increase in costs is suppressed.

If the efficiency decrease amount Δη is equal to or greater than the threshold value Δηth, the ECU 50 may notify the user of the vehicle. The notification may be, for example, a voice message or a screen display. The notification may include information about maintenance such as part replacement and oil change.

The threshold value Δηth may be, for example, 3 points, 5 points, 10 points, 15 points, etc. Five points means that the efficiency of compressor 18b has changed from 75% to 70%.

In order to improve the performance of the internal combustion engine 10, it is important to increase the boost pressure provided by the turbocharger 18. By increasing the boost pressure, the air temperature increases, and the housing temperature T also increases. Blow-by gas is recirculated to the intake air. Deposits are formed when the oil in the blow-by gas is exposed to high temperatures. As described above, the ECU 50 obtains the amount of decrease in efficiency of the compressor 18b. It is possible to improve the performance of the internal combustion engine 10 while predicting the decrease in efficiency.

For example, the amount of efficiency decrease may be collected from multiple vehicles. A threshold value Δηth may be determined for each vehicle type and region based on the degree of deterioration according to the vehicle type, region, etc.

Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims.

REFERENCE SIGNS LIST 10 internal combustion engine 11, 16 valve 12 intake passage 13, 15 bypass passage 14 exhaust passage 17 piston 18 turbocharger 18a turbine 18b compressor 19 crankshaft 20 air cleaner 22 air flow meter 23 PCV passage 25 intercooler 26 throttle valve 27 combustion chamber 28 catalyst 30 intake valve 32 exhaust valve 34 fuel injector 40 vehicle speed sensor 42, 43 pressure sensor 44, 46 temperature sensor 47 water temperature sensor 50 ECU
100 Engine System

Claims (1)

A control device for an internal combustion engine equipped with a turbocharger,
The turbocharger has a compressor,
a reduction amount acquisition unit that acquires a reduction amount of efficiency of the compressor based on a temperature of the compressor and a concentration of insoluble matter in the oil;
A determination unit that determines whether the turbocharger is deteriorated based on the amount of decrease ,
the decrease amount acquisition unit, when the temperature is a first temperature and the insoluble matter concentration is a first concentration, acquires a decrease rate of the efficiency based on the first temperature and the first concentration;
the decrease amount acquisition unit acquires the decrease amount by multiplying the decrease rate at the first temperature and the first concentration by a time during which the temperature is the first temperature and the insoluble concentration is the first concentration;
the decrease amount acquisition unit sums up the decrease amounts corresponding to the temperature and the insoluble matter concentration,
The control device for an internal combustion engine , wherein the determination unit determines that the supercharger has deteriorated when the added-up amount of decrease is equal to or greater than a threshold value .

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