Control device for internal combustion engine

Abstract

To provide a control device for an internal combustion engine which can determine generation of deposits.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 first acquisition part which acquires a temperature of a housing of the compressor, and a determination part which determines whether or not a deposit is generated in the compressor, on the basis of the temperature.SELECTED DRAWING: Figure 3

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] When deposits are generated on the compressor of the supercharger, the efficiency of the supercharger decreases. Therefore, an object of the present invention is to provide a control device for an internal combustion engine that can determine the generation of deposits.

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, a first acquisition unit that acquires the temperature of the housing of the compressor, a second acquisition unit that acquires an insoluble component concentration of the oil; and a third acquisition unit that acquires a decrease amount of the efficiency of the compressor based on the temperature and the insoluble component concentration and a determination unit that determines whether deposits are generated on the compressor based on the temperature. and the determination unit determines that the deposit is generated by concentration of the insoluble component of the oil that has entered the compressor when the temperature is equal to or higher than a predetermined temperature, and determines that the deposit is not generated when the temperature is lower than the predetermined temperature. The third acquisition unit acquires a first decrease rate that is a decrease rate of the efficiency of the compressor due to the temperature, and a second decrease rate that is a decrease rate of the efficiency of the compressor due to the insoluble component concentration. The third acquisition unit acquires the decrease amount of the efficiency of the compressor based on the first decrease rate and the second decrease rate It can be achieved by a control device for an internal combustion engine.

[0006] the third acquisition unit calculates the decrease rate of the efficiency by multiplying the first decrease rate and the second decrease rate, and the third acquisition unit acquires the decrease amount of the efficiency by multiplying the decrease rate obtained by the multiplication and the time during which the temperature corresponding to the first decrease rate and the insoluble component concentration corresponding to the second decrease rate continue It may be.

Effects of the Invention

[0010] It is possible to provide a control device for an internal combustion engine that can determine the generation of deposits.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

MODE FOR CARRYING OUT THE INVENTION

[0012] (First Embodiment) FIG. 1 is a schematic diagram illustrating an engine system 100 according to the first embodiment. The engine system 100 includes an internal combustion engine 10, a supercharger 18, and an ECU (Electronic Control Unit) 50.

[0013] 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.

[0014] 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.

[0015] 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 upstream of the catalyst 28 in the exhaust passage 14. The compressor 18b is located downstream of the air flow meter 22 and upstream of the intercooler 25 in the intake passage 12. The turbine 18a and the compressor 18b are housed inside a housing (not shown).

[0016] 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.

[0017] 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 insoluble components contained in the oil and adhere to the compressor 18b. The efficiency of the supercharger 18 decreases due to the adhesion of deposits.

[0018] 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 air-fuel mixture burns in the combustion chamber 27. The piston 17 reciprocates up and down in the combustion chamber 27, the driving force is transmitted to the crankshaft 19, and the vehicle runs.

[0019] 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, which purifies carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), etc. in the exhaust gas.

[0020] When the exhaust gas is introduced into the turbine 18a of the supercharger 18, the turbine 18a rotates, and the compressor 18b connected to the turbine 18a also rotates. By 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 with the intake air on the upstream side of the compressor 18b.

[0021] 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 water 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 water temperature sensor 47 detects the temperature of the cooling water of the internal combustion engine 10.

[0022] 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 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 device.

[0023] The ECU 50 controls the opening degrees of the throttle valve 26, the valves 11 and 16. The valve 11 is an air bypass valve (ABV), and by opening 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.

[0024] 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 concentration of insoluble components in the oil from this information. The ECU 50 functions as a first acquisition unit that acquires the temperature of the housing of the compressor 18b, and a determination unit that determines whether or not deposits are generated.

[0025] 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 mixes into the blow-by gas. The blow-by gas is introduced into the compressor 18b of the supercharger 18 together with the intake air. Oil adheres to the housing of the compressor 18b. 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.

[0026] FIG. 2 is a diagram illustrating the relationship between temperature and the rate of efficiency decrease. The horizontal axis represents the member temperature (housing temperature) of the compressor 18b. The vertical axis represents the rate of decrease in the efficiency of the compressor 18b. As shown in FIG. 2, when the temperature is less than T0, the rate of decrease in efficiency is 0. Since no deposit is generated when the temperature is T0, no decrease in efficiency due to deposits occurs either. On the other hand, when the temperature becomes T0 or higher, the rate of decrease in efficiency rises above 0. Since deposits are generated when the temperature becomes T0 or higher, the efficiency of the compressor 18b also decreases due to the deposits. As the temperature increases, the amount of deposit generation increases. For this reason, the rate of decrease in efficiency also increases.

[0027] FIG. 3 is a diagram illustrating the processing executed by the ECU 50. The ECU 50 estimates the temperature T of the housing (step S10). Specifically, the ECU 50 estimates the temperature of the air at the outlet of the compressor 18b from, for example, 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 T of the housing based on the temperature of the air at the outlet.

[0028] The ECU 50 determines whether or not the temperature T of the housing is equal to or higher than a predetermined temperature T0 (step S12). If a negative determination (No) is made in step S12, the ECU 50 ends the processing of FIG. 3. On the other hand, if an affirmative determination (Yes) is made in step S12, the ECU 50 determines that deposits are generated (step S14). After step S14, the processing of FIG. 3 ends.

[0029] According to the first embodiment, the ECU 50 determines whether or not deposits are generated in the compressor 18b based on the temperature T of the housing of the compressor 18b. By predicting the generation of deposits, it is also possible to predict a decrease in the efficiency of the compressor 18b due to the adhesion of deposits.

[0030] When the temperature T of the housing is equal to or higher than T0, the ECU 50 determines that deposits are generated (step S14 in FIG. 2). As shown in FIG. 2, if the temperature T is less than T0, it is predicted that no deposits will be generated and the efficiency will not decrease. If the temperature T is equal to or higher than T0, the insoluble components in the oil are concentrated and deposits are generated. That is, the temperature at which the insoluble components in the oil chemically change to become deposits is T0. By comparing the temperature T acquired by the ECU 50 with T0, the generation of deposits can be accurately predicted. The threshold value T0 may be determined according to, for example, the vehicle type, the size and material of the housing, etc.

[0031] 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 into the intake air. The oil in the blow-by gas is exposed to high temperatures, resulting in the generation of deposits. As described above, based on the temperature T of the housing and the threshold value T0, the ECU 50 predicts the generation of deposits. It is possible to achieve both an improvement in the performance of the internal combustion engine 10 and the prediction of deposit generation.

[0032] (Second Embodiment) In the second embodiment, the amount of decrease in the efficiency of the compressor 18b is obtained. The engine system 100 shown in FIG. 1 is also common to the second embodiment. The description of the same configuration as in the first embodiment will be omitted.

[0033] FIG. 4 is a diagram illustrating the relationship between the insoluble component concentration and the efficiency decrease rate. The horizontal axis represents the concentration of insoluble components in the oil. The vertical axis represents the efficiency decrease rate of the compressor 18b. As shown in FIG. 4, the higher the insoluble component concentration, the greater the efficiency decrease rate. This is because deposits are generated due to the hardening of the insoluble component concentration and adhere to the compressor 18b.

[0034] As shown in FIG. 2, when the member temperature of the compressor 18b increases, the rate of decrease in efficiency also increases. As shown in FIG. 4, when the concentration of insoluble components in the oil increases, the rate of decrease in efficiency also increases. The ECU 50 functions as a second acquisition unit that acquires the concentration of insoluble components. Further, the ECU 50 functions as a third acquisition unit that acquires the amount of decrease in the efficiency of the compressor 18b based on the member temperature and the concentration of insoluble components.

[0035] FIG. 5 is a diagram illustrating the process executed by the ECU 50. The ECU 50 estimates the temperature T of the housing of the compressor 18b (step S20). Step S20 is the same process as step S10 in FIG. 3, for example. The ECU 50 acquires the rate of decrease in efficiency corresponding to the temperature T (step S22).

[0036] The ECU 50 estimates the concentration of insoluble components in the oil (step S24). For example, based on the fuel injection amount and the temperature of the cooling water, the ECU 50 acquires the concentration of insoluble components. The ECU 50 acquires the rate of decrease in efficiency corresponding to the concentration of insoluble components (step S26).

[0037] The ECU 50 acquires the rate of decrease in the efficiency of the compressor 18b from the rate of decrease in efficiency corresponding to the temperature and the rate of decrease in efficiency corresponding to the concentration of insoluble components. The ECU 50 multiplies the rate of decrease in efficiency by the operation time of the internal combustion engine 10 to integrate the amount of decrease in efficiency (step S27). The ECU 50 calculates the amount of decrease in efficiency by integration calculation (step S28). The process of FIG. 5 ends here.

[0038] According to the second embodiment, the ECU 50 acquires the temperature of the housing of the compressor 18b and the concentration of insoluble components in the oil. The ECU 50 acquires the amount of decrease in the efficiency of the compressor 18b based on the temperature of the housing of the compressor 18b and the concentration of insoluble components. For example, when the amount of decrease in efficiency reaches a predetermined magnitude, it is possible to suppress the decrease in efficiency by performing component replacement of the compressor 18b or the like.

[0039] As shown in FIG. 2, the rate of decrease in efficiency (the first rate of decrease) is determined according to the temperature of the housing of the compressor 18b. For example, when the temperature is Ta, the rate of decrease is Va. As shown in FIG. 4, the rate of decrease in efficiency (the second rate of decrease) is determined according to the insoluble matter concentration. For example, when the insoluble matter concentration is Xb, the rate of decrease is Vb. When the temperature is Ta and the insoluble matter concentration is Xb, the ECU 50 calculates the rate of decrease in efficiency (Va·Vb) under the condition by multiplying the rate of decrease Va and the rate of decrease Vb. By multiplying the rate of decrease (Va·Vb) by the duration for which the condition persists, the amount of decrease in efficiency can be obtained. Similar to the above example, by multiplying the rate of decrease according to the condition (the temperature of the housing and the insoluble matter concentration) by the duration of the condition, the amount of decrease in efficiency can be obtained. The ECU 50 can obtain the amount of decrease in the efficiency of the compressor 18b by integrating the amount of decrease in efficiency for each condition (step S28 in FIG. 5).

[0040] 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 the insoluble matter from the fuel injection amount and the water temperature. That is, the ECU 50 obtains the temperature of the housing and the concentration of the insoluble matter 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 the insoluble matter. Since the estimation is performed based on the real-time information of the vehicle, the accuracy of the estimation of the amount of decrease in efficiency is improved.

[0041] Sensors for detecting the temperature of the housing of the compressor 18b and sensors for detecting the insoluble matter concentration may be provided in the vehicle. Based on the temperature of the housing and the insoluble matter detected by the sensors, the ECU 50 can estimate the amount of decrease in efficiency. Also, as described above, the ECU 50 may calculate the outlet temperature of the compressor 18b from the supercharging pressure or the like, and calculate the temperature of the housing based on the outlet temperature. The ECU 50 may calculate the insoluble matter concentration based on the fuel injection amount and the water temperature. By not providing the sensors, an increase in cost can be suppressed.

[0042] (Third Embodiment) In the third embodiment, the deposition adhesion site in the compressor 18b is predicted. The engine system 100 shown in FIG. 1 is also common to the third embodiment. Description of the same configuration as that of the first embodiment is omitted.

[0043] FIG. 6(a) is a cross-sectional view illustrating the compressor 18b. The compressor 18b has a wheel 51 and a housing 52. The wheel 51 is housed in the housing 52. The wheel 51 is connected to a turbine (not shown) by a shaft 54. Air flows through the compressor 18b as indicated by the arrow in FIG. 6. The introduced air is supercharged by the rotation of the wheel 51 and sent into the internal combustion engine 10. Of the housing 52, the upstream portion in the air flow direction is defined as a shroud portion 52a, and the downstream portion is defined as a diffuser portion 52b.

[0044] When deposits adhere to the housing 52, the efficiency of the compressor 18b decreases. The amount of efficiency decrease varies depending on the deposition adhesion site. The amount of efficiency decrease due to deposits adhering to the shroud portion 52a is greater than the amount of efficiency decrease due to deposits adhering to the diffuser portion 52b.

[0045] FIG. 6(b) is a schematic diagram illustrating the amount of efficiency decrease. In the example of FIG. 6(b), the amount of efficiency decrease is D1 (%). Among D1, the contribution by deposits adhering to the shroud portion 52a is D2 (%). Among D1, the contribution by deposits adhering to the diffuser portion 52b is D3 (%). D2 is greater than D3, for example, about twice D3. The deposits on the shroud portion 52a contribute more to the efficiency decrease than the deposits on the diffuser portion 52b.

[0046] The ECU 50 functions as a fourth acquisition unit that acquires the temperature of the air (outlet temperature) at the outlet of the compressor 18b, and an estimation unit that estimates the deposition adhesion site based on the outlet temperature.

[0047] FIG. 7 is a diagram illustrating the process executed by the ECU 50. The ECU 50 estimates the temperature T3 of the air at the outlet of the compressor 18b (step S30). The ECU 50 estimates the temperature T of the housing of the compressor 18b (step S32). The ECU 50 estimates the deposit adhesion site based on the outlet temperature T3 and the housing temperature T (step S34). The ECU 50 obtains the efficiency degradation rate based on the deposit adhesion site and the housing temperature T (step S36). The amount of efficiency degradation can be obtained from the efficiency degradation rate (for example, FIG. 5). Thus, the process of FIG. 7 ends.

[0048] According to the third embodiment, the ECU 50 obtains the outlet temperature and estimates the deposit adhesion site based on the outlet temperature. As shown in FIG. 6(b), the deposit on the shroud portion 52a contributes more to the efficiency degradation than the deposit on the diffuser portion 52b. The ECU 50 obtains the efficiency degradation rate based on the deposit adhesion site and also obtains the amount of efficiency degradation. By also considering the deposit adhesion site, the prediction accuracy of the amount of efficiency degradation is improved.

[0049] 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.

Description of Reference Numerals

[0050] 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 Airflow meter 23 PCV passage 25 Intercooler 26 Throttle valve 27 Combustion chamber 28 Catalyst 30 Intake valve 32 Exhaust valve 34 Fuel injection valve 40 Vehicle speed sensor 42, 43 Pressure sensor 44, 46 Temperature sensor 47 Water temperature sensor 50 ECU 51 Wheel 52 Housing 52a Shroud part 52b Diffuser part 54 Shaft 100 Engine system

Claims

1. A control device for an internal combustion engine equipped with a supercharger, wherein the supercharger has a compressor, a first acquisition unit that acquires the temperature of the housing of the compressor, a second acquisition unit that acquires the concentration of insoluble components of oil, a third acquisition unit that acquires the amount of decrease in the efficiency of the compressor based on the temperature and the concentration of insoluble components, and a determination unit that determines whether or not a deposit is generated on the compressor based on the temperature, wherein the determination unit determines that the deposit is generated by concentration of insoluble components of the oil that has entered the compressor when the temperature is equal to or higher than a predetermined temperature, and determines that no deposit is generated when the temperature is lower than the predetermined temperature, the third acquisition unit acquires a first decrease rate, which is the rate of decrease in the efficiency of the compressor due to the temperature, and a second decrease rate, which is the rate of decrease in the efficiency of the compressor due to the concentration of insoluble components, and the third acquisition unit acquires the amount of decrease in the efficiency of the compressor based on the first decrease rate and the second decrease rate. A control device for an internal combustion engine.

2. The third acquisition unit calculates the rate of decrease in efficiency by multiplying the first decrease rate and the second decrease rate, and the third acquisition unit acquires the amount of decrease in efficiency by multiplying the decrease rate obtained by the multiplication by the time during which the temperature corresponding to the first decrease rate and the concentration of insoluble components corresponding to the second decrease rate continue. The control device for an internal combustion engine according to Claim 1.

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