Control device for internal combustion engine

Abstract

To provide a control device for an internal combustion engine which can determine degradation of a compressor.SOLUTION: In a control device for an internal combustion engine including a supercharger, the supercharger has a compressor. The control device for the internal combustion engine includes a reduction amount acquisition part which acquires a reduction amount of an efficiency of the compressor on the basis of a temperature of the compressor and an irresolvability concentration of oil, and a determination part which determines whether or not the supercharger is degraded, on the basis of the reduction amount.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a control device for an internal combustion engine.

Background Art

[0002] An internal combustion engine equipped with a supercharger is known (for example, Patent Document 1, etc.).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The compressor of the supercharger deteriorates. Deterioration means that deposits adhere to the compressor of the supercharger, and the efficiency of the compressor decreases due to the deposits. Therefore, an object of the present invention is to provide a control device for an internal combustion engine capable of determining the deterioration of the compressor.

Means for Solving the Problems

[0005] The above object is achieved by a control device for an internal combustion engine equipped with a supercharger, the supercharger having a compressor, the control device comprising: a reduction amount acquisition unit that acquires a reduction amount of the efficiency of the compressor based on the temperature of the compressor and the concentration of insoluble components of the oil; and a determination unit that determines whether the supercharger is deteriorated based on the reduction amount. When the temperature is the first temperature and the insoluble content concentration is the first concentration, the decrease amount acquisition unit acquires the decrease rate of the efficiency based on the first temperature and the first concentration. The decrease amount acquisition unit multiplies the decrease rate at the first temperature and the first concentration by the time when the temperature is the first temperature and the insoluble content concentration is the first concentration to obtain the decrease amount. The decrease amount acquisition unit adds up the decrease amounts corresponding to the temperature and the insoluble content concentration. When the added decrease amount is equal to or greater than a threshold value, the determination unit determines that the supercharger is deteriorated. This can be achieved by a control device for an internal combustion engine.

Effects of the Invention

[0006] It is possible to provide a control device for an internal combustion engine capable of determining the deterioration of the compressor.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0008] Figure 1 is a schematic diagram illustrating an engine system 100. The engine system 100 includes an internal combustion engine 10, a supercharger 18, and an ECU (Electronic Control Unit) 50.

[0009] 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 injection valve 34. A combustion chamber 27 is formed in the bore of the internal combustion engine 10. The fuel injection valve 34 is provided in the intake passage 12, but may be provided in the combustion chamber 27. The piston 17 is disposed inside the combustion chamber 27 and is connected to a crankshaft 19.

[0010] 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 order from the upstream side. A catalyst 28 is provided in the exhaust passage 14.

[0011] The supercharger 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 on the upstream side of the catalyst 28 in the exhaust passage 14. The compressor 18b is located on the downstream side of the air flow meter 22 and on the upstream side of the intercooler 25 in the intake passage 12. The turbine 18a and the compressor 18b are housed inside a housing (not shown).

[0012] 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 the downstream to the 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.

[0013] A PCV (Positive Crankcase Ventilation) passage 23 is connected to the internal combustion engine 10 and a position upstream of the compressor 18b of the supercharger 18 in the intake passage 12. 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 components contained in the oil and adhere to the compressor 18b. The efficiency of the supercharger 18 decreases due to the adhesion of the deposits.

[0014] 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 air-fuel mixture burns 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 travel.

[0015] When the exhaust valve 32 opens, the exhaust gas generated by 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 that purifies carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), etc. in the exhaust gas.

[0016] By introducing the exhaust gas into the turbine 18a of the supercharger 18, the turbine 18a rotates, and the compressor 18b connected to the turbine 18a also rotates. Due to the rotation of the compressor 18b, the intake air is supercharged, and the high-pressure intake air is sent into the combustion chamber 27 of the internal combustion engine 10 compared to the intake air on the upstream side of the compressor 18b.

[0017] The engine system 100 includes an air flow meter 22, a vehicle speed sensor 40, pressure sensors 42 and 43, temperature sensors 44 and 46, and a coolant temperature sensor 47. The air flow meter 22 detects the flow rate of the intake air. The vehicle speed sensor 40 detects the speed (vehicle speed) of the vehicle on which the engine system 100 is mounted. The pressure sensor 42 detects the atmospheric pressure. The pressure sensor 43 detects the pressure of the air supercharged by the supercharger 18 (supercharging pressure). The temperature sensor 44 detects the outside air temperature. The temperature sensor 46 detects the temperature in the intake passage 12. The coolant temperature sensor 47 detects the temperature of the coolant of the internal combustion engine 10.

[0018] The ECU 50 is a control device for the internal combustion engine 10. The ECU 50 includes an arithmetic device such as a CPU (Central Processing Unit), and a storage device 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 device.

[0019] The ECU 50 controls the opening degrees of the throttle valve 26, and the valves 11 and 16. The valve 11 is an air bypass valve (ABV), and by opening the valve when the accelerator is off, the supercharged air can be released. The ECU 50 switches the on / off of the fuel injection from the fuel injection valve 34 and controls the fuel injection amount.

[0020] The ECU 50 acquires the intake air flow rate from the air flow meter 22, acquires the vehicle speed from the vehicle speed sensor 40, and acquires the fuel injection amount. The ECU 50 acquires the atmospheric pressure from the pressure sensor 42, and acquires the pressure of the air introduced into the compressor 18b based on the atmospheric pressure. The ECU 50 acquires the supercharging pressure from the pressure sensor 43. The ECU 50 acquires the outside air temperature from the temperature sensor 44, acquires the temperature of the air in the intake passage 12 from the temperature sensor 46, and acquires the water temperature from the water temperature sensor 47. The ECU 50 calculates the member temperature (housing temperature) of the compressor 18b and the insoluble component concentration of the oil from this information.

[0021] The ECU 50 functions as a reduction amount acquisition unit that acquires the amount of reduction in the efficiency of the compressor 18b, and a determination unit that determines whether or not the supercharger 18 is deteriorated based on the reduction amount.

[0022] When deposits adhere to the compressor 18b, the efficiency decreases. A decrease in efficiency may be described as deterioration of the supercharger 18. The amount of deposit generation depends on the temperature of the compressor 18b and the concentration of insoluble components 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 supercharger 18 together with the intake air. When the temperature of the compressor 18b rises, the oil is likely to evaporate. When the oil evaporates, the insoluble components contained in the oil are concentrated and hardened, and adhere to the compressor 18b as deposits. When deposits adhere to the compressor 18b, the efficiency of the compressor 18b decreases. The higher the housing temperature and the higher the concentration of insoluble components, the more likely deposits are to occur and the more likely the efficiency is to decrease.

[0023] FIG. 2 is a diagram illustrating the reduction rate of efficiency. The horizontal axis represents the housing temperature of the compressor 18b. The vertical axis represents the reduction rate of the efficiency of the compressor 18b. The broken line represents an example where the insoluble component concentration is 0.3 wt%. The dotted line represents an example where the insoluble component concentration is 0.5 wt%. The solid line represents an example where the insoluble component concentration is 1 wt%.

[0024] As shown in Fig. 2, when the temperature of the housing is less than T0, the rate of decrease in efficiency is zero. This is because deposits are less likely to occur when the temperature is less than T0. When the temperature becomes T0 or higher, deposits are generated and the rate of decrease in efficiency also rises above zero. The rate of decrease in efficiency in the example of 0.5 wt% shown by the dotted line is greater than that in the example of 0.3 wt% shown by the dashed line. The rate of decrease in efficiency in the example of 1 wt% shown by the solid line is greater than that in the examples of the dashed line and the dotted line. The higher the concentration of the insoluble component, the greater the amount of deposits generated and the more significantly the efficiency decreases.

[0025] Fig. 3 is a flowchart illustrating the process executed by the ECU 50. The ECU 50 estimates the temperature T of the housing (step S10). The ECU 50 calculates, for example, the temperature of the air at the outlet of the compressor 18b from the pressure at the inlet of the compressor 18b, the supercharging pressure, the temperature of the intake air, the flow rate of the intake air, and the vehicle speed. The ECU 50 calculates the temperature T of the housing based on the temperature of the air at the outlet.

[0026] The ECU 50 estimates the concentration of the insoluble component in the oil (step S12). For example, based on the fuel injection amount and the water temperature, the amount of the precursor of sludge is estimated, and the concentration of the insoluble component is estimated from the amount of the precursor.

[0027] The ECU 50 estimates the amount of decrease Δη in the efficiency of the compressor 18b based on the temperature T of the housing and the concentration of the insoluble component (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 the insoluble component. By multiplying the time when the temperature T and the concentration of the insoluble component are specific values by the corresponding rate of decrease in efficiency, the amount of decrease in efficiency can be obtained. The ECU 50 calculates the amount of decrease Δη, for example, by adding up the amounts of decrease in efficiency from the start of operation of the internal combustion engine 10 to the current time. The ECU 50 determines whether or not the amount of decrease Δη is equal to or greater than the threshold value Δηth (step S16). In the case of a negative determination (No), the process ends. In the case of an affirmative determination (Yes), the ECU 50 determines that the compressor 18b is deteriorated (step S18). After step S18, the process ends.

[0028] According to the present embodiment, the ECU 50 obtains a decrease amount 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 components in the oil. When the decrease amount Δη is equal to or greater than a threshold value Δηth, the ECU 50 determines that the compressor 18b is deteriorated. It is possible to accurately determine the deterioration of the compressor 18b.

[0029] The higher the temperature of the housing of the compressor 18b, the easier it is for the oil to evaporate. The insoluble components of the oil adhere to the housing as deposits. That is, the higher the temperature of the housing and the higher the concentration of insoluble components, the easier it is for deposits to occur. The amount of efficiency reduction due to deposits also increases. According to the present embodiment, the ECU 50 obtains the rate of decrease in efficiency based on the temperature of the housing and the concentration of insoluble components. The ECU 50 obtains the amount of decrease in efficiency by multiplying the rate of decrease in efficiency by time. It is possible to obtain the amount of decrease in efficiency in real time according to changes in temperature and the concentration of insoluble components. The ECU 50 can grasp the amount of efficiency reduction from the start of operation, for example, by accumulating the amount of efficiency reduction in an in-vehicle storage device. The ECU 50 may transmit the amount of efficiency reduction to an external server or the like.

[0030] The ECU 50 estimates the temperature of the air at the outlet of the compressor 18b from the pressure at the inlet of the compressor 18b, the supercharging pressure, the temperature of the intake air, the flow rate of the intake air, and the vehicle speed. The ECU 50 estimates the temperature of the housing based on the temperature of the air at the outlet. The ECU 50 estimates the concentration of insoluble components from the fuel injection amount and the water temperature. That is, the ECU 50 obtains the temperature of the housing and the concentration of insoluble components based on the information obtained from the vehicle, and obtains the amount of decrease in efficiency based on the temperature of the housing and the concentration of insoluble components. The amount of decrease in efficiency according to the situation of the vehicle can be obtained. The accuracy of deterioration determination is improved. Since it is not necessary to add a sensor for measuring the temperature of the housing and a sensor for measuring the concentration of insoluble components, an increase in cost is suppressed.

[0031] When the amount of efficiency decrease Δη is equal to or greater than the threshold value Δηth, the ECU 50 may notify the vehicle user. The notification may be, for example, voice, screen display, etc. The notification may include content related to maintenance such as component replacement and oil change.

[0032] The threshold value Δηth may be, for example, 3 points, 5 points, 10 points, 15 points, etc. 5 points means that the efficiency of the compressor 18b has changed from 75% to 70%.

[0033] To improve the performance of the internal combustion engine 10, it is important to increase the supercharging pressure by the supercharger 18. By increasing the supercharging pressure, the temperature of the air rises, and the temperature T of the housing also rises. Blow-by gas is refluxed to the intake air. Oil in the blow-by gas is exposed to high temperatures, resulting in deposits. As described above, the ECU 50 acquires the amount of efficiency decrease of the compressor 18b. It is possible to achieve both an improvement in the performance of the internal combustion engine 10 and a prediction of efficiency decrease.

[0034] For example, the amount of efficiency decrease may be collected from a plurality of vehicles. The threshold value Δηth may be determined for each vehicle type and region based on the degree of deterioration according to vehicle type and region, etc.

[0035] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

Explanation of Reference Numerals

[0036] 10 Internal combustion engine 11, 16 Valve 12 Intake passage 13, 15 Bypass passage 14 Exhaust passage 17 Piston 18 Supercharger 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 Engine Water Temperature Sensor 50 ECU 100 Engine System

Claims

【Claim 1】 A control device for an internal combustion engine equipped with a supercharger, wherein the supercharger has a compressor, a reduction amount acquisition unit that acquires a reduction amount of the efficiency of the compressor based on the temperature of the compressor and the concentration of insoluble components in the oil, a determination unit that determines whether the supercharger is deteriorated based on the reduction amount, and when the temperature is a first temperature and the insoluble component concentration is a first concentration, the reduction amount acquisition unit acquires a reduction rate of the efficiency based on the first temperature and the first concentration, the reduction amount acquisition unit acquires the reduction amount by multiplying the reduction rate at the first temperature and the first concentration by the time when the temperature is the first temperature and the insoluble component concentration is the first concentration, the reduction amount acquisition unit adds up the reduction amounts corresponding to the temperature and the insoluble component concentration, and when the added reduction amount is equal to or greater than a threshold value, the determination unit determines that the supercharger is deteriorated. A control device for an internal combustion engine.

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