Control device for an internal combustion engine

Abstract

Provided is a control device for an internal combustion engine provided with a turbocharger, wherein the turbocharger includes a compressor, and the control device includes a first acquisition unit configured to acquire a temperature of a casing of the compressor, and a determination unit configured to determine whether deposits have been generated in the compressor based on the temperature.

Description

Technical Field

[0001] This disclosure relates to a control device for an internal combustion engine. Background Technology

[0002] For example, International Publication No. 2013 / 080600 (Patent Document 1) discloses an internal combustion engine equipped with a turbocharger. Summary of the Invention

[0003] When deposits form in the compressor of a turbocharger, the efficiency of the turbocharger decreases. Therefore, one object of the present invention is to provide a control device for an internal combustion engine capable of determining the formation of deposits.

[0004] In one aspect of this disclosure, a control device for an internal combustion engine equipped with a turbocharger is provided, wherein the turbocharger includes a compressor, and wherein the control device includes: a first acquisition unit configured to acquire the temperature of the housing of the compressor; and a determination unit configured to determine, based on the temperature, whether deposits have been generated in the compressor.

[0005] When the temperature is equal to or higher than a predetermined temperature, the determination unit can determine that sediment has been generated.

[0006] The control device may further include: a second obtaining unit configured to obtain the concentration of oil insoluble matter; and a third obtaining unit configured to obtain the amount of efficiency reduction of the compressor based on the temperature and the concentration of insoluble matter.

[0007] The third obtaining unit can obtain a first decreasing rate and a second decreasing rate, wherein the first decreasing rate is the rate of decrease in compressor efficiency caused by the temperature, and the second decreasing rate is the rate of decrease in compressor efficiency caused by the concentration of insoluble matter, and the third obtaining unit can obtain the amount of decrease in compressor efficiency based on the first decreasing rate and the second decreasing rate.

[0008] The control device may further include: a fourth acquisition unit configured to acquire the temperature of the air inside the compressor; and an estimation unit configured to estimate the attachment site of the deposit based on the temperature of the air, wherein the third acquisition unit acquires the amount of efficiency reduction of the compressor based on the attachment site of the deposit. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of an engine system according to the first embodiment;

[0010] Figure 2 This illustrates the relationship between temperature and the rate of efficiency decline;

[0011] Figure 3 The process performed by the ECU is shown;

[0012] Figure 4 The relationship between insoluble concentration and the rate of efficiency decline is shown;

[0013] Figure 5 The process performed by the ECU is shown;

[0014] Figure 6A It shows a cross-sectional view of the compressor. Figure 6B This is a schematic diagram showing the rate of efficiency decline;

[0015] Figure 7 The process performed by the ECU is shown. Detailed Implementation

[0016] First Embodiment

[0017] Figure 1 This is a schematic diagram of an engine system 100 according to a first embodiment. The engine system 100 includes an internal combustion engine 10, a turbocharger 18, and an electronic control unit (ECU) 50.

[0018] 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 cylinder bore of the internal combustion engine 10. Although the fuel injection valve 34 is located in the intake passage 12, it can also be located in the combustion chamber 27. The piston 17 is located inside the combustion chamber 27 and is connected to the crankshaft 19.

[0019] The intake passage 12 and the exhaust passage 14 are connected to the internal combustion engine 10. The intake passage 12 is provided with an air filter 20, an air flow meter 22, an intercooler 25, a throttle valve 26, and a fuel injection valve 34 in sequence from the upstream side. The exhaust passage 14 is provided with a catalyst 28.

[0020] The turbocharger 18 includes a turbine 18a and a compressor 18b. The turbine 18a and 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 compressor 18b are housed within a housing (not shown).

[0021] The intake passage 12 is connected to a bypass passage 13 that bypasses the compressor 18b, and a valve 11 is installed in the bypass passage 13. When the accelerator is closed, air flows from downstream to upstream through the bypass passage 13, bypassing the compressor 18b. The exhaust passage 14 is connected to a bypass passage 15 that bypasses the turbine 18a, and a valve 16 is installed in the bypass passage 15.

[0022] A crankcase ventilation (PCV) passage 23 is connected to the internal combustion engine 10 and to the intake passage 12 upstream of the compressor 18b of the turbocharger 18. Blow-by gas returns to the intake passage 12 via the PCV passage 23 and flows through the intake passage 12 with air. Oil mixes with the blow-by gas. Insoluble substances contained in the oil produce deposits that adhere to the compressor 18b. When these deposits adhere to the turbocharger 18, the efficiency of the turbocharger 18 decreases.

[0023] Intake air passes through intake passage 12, is purified by air filter 20, and cooled by intercooler 25. When intake valve 30 is open, intake air is introduced into combustion chamber 27 of internal combustion engine 10. Fuel injection valve 34 injects fuel into combustion chamber 27. When spark plug (not shown) ignites, the mixture of intake air and fuel burns in combustion chamber 27. Piston 17 reciprocates up and down in combustion chamber 27, and driving force is transmitted to crankshaft 19 to drive the vehicle.

[0024] When the exhaust valve 32 is opened, the exhaust gas produced 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, and purifies the exhaust gas of carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), etc.

[0025] When 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 intake air is pressurized by the rotation of the compressor 18b, and the intake air with a pressure higher than the intake air pressure upstream of the compressor 18b is supplied to the combustion chamber 27 of the internal combustion engine 10.

[0026] 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. Air flow meter 22 detects the intake air flow. Vehicle speed sensor 40 detects the speed of the vehicle equipped with engine system 100. Pressure sensor 42 detects atmospheric pressure. Pressure sensor 43 detects the pressure of the air pressurized by turbocharger 18 (boost pressure). Temperature sensor 44 detects the temperature of the outside air. Temperature sensor 46 detects the temperature in the intake passage 12. Coolant temperature sensor 47 detects the temperature of the coolant in internal combustion engine 10.

[0027] ECU 50 is a control device for internal combustion engine 10. ECU 50 includes a computing unit such as a central processing unit (CPU) and storage devices such as random access memory (RAM) and read-only memory (ROM). ECU 50 performs various types of control by executing programs stored in storage devices such as ROM.

[0028] ECU 50 controls the opening of throttle valve 26 and the opening of valves 11 and 16. Valve 11 is an air bypass valve (ABV) that releases boosted air when the accelerator is off. ECU 50 toggles the on / off state of fuel injection from fuel injection valve 34 to control the amount of fuel injected.

[0029] ECU 50 obtains intake airflow from airflow meter 22, vehicle speed from vehicle speed sensor 40, and fuel injection quantity. ECU 50 obtains atmospheric pressure from pressure sensor 42 and, based on atmospheric pressure, obtains the pressure of the air introduced into compressor 18b. ECU 50 obtains boost pressure from pressure sensor 43. ECU 50 obtains the outside air temperature from temperature sensor 44, the air temperature in intake passage 12 from temperature sensor 46, and the water temperature from water temperature sensor 47. Based on this information, ECU 50 calculates the component temperature (casing temperature) of compressor 18b and the concentration of insoluble substances in the oil. ECU 50 serves as the first unit for obtaining the temperature of the compressor 18b casing and as a unit for determining whether deposits have been formed.

[0030] When deposits adhere to compressor 18b, efficiency decreases. This decrease in efficiency can be termed the degradation of turbocharger 18. The amount of deposits produced depends on the temperature of compressor 18b and the concentration of insolubles in the oil. Oil mixes with blow-by gas. Blow-by gas is introduced into compressor 18b of turbocharger 18 along with the intake air. Oil adheres to the casing of compressor 18b. As the temperature of compressor 18b increases, the oil is likely to evaporate. When the oil evaporates, the insolubles in the oil solidify and harden, adhering to compressor 18b as deposits. When deposits adhere to compressor 18b, the efficiency of compressor 18b decreases.

[0031] Figure 2 The relationship between temperature and the rate of efficiency decline is shown. The horizontal axis represents the component temperature (casing temperature) of compressor 18b. The vertical axis represents the rate of efficiency decline of compressor 18b. Figure 2As shown, when the temperature is below T0, the rate of efficiency decrease is zero. At temperature T0, no deposits are formed, therefore no efficiency reduction occurs due to deposits. On the other hand, when the temperature is equal to or above T0, the rate of efficiency decrease increases to above zero. When the temperature is equal to or above T0, deposits are formed, and the efficiency of compressor 18b also decreases due to deposits. As the temperature increases, the amount of deposits produced increases. Therefore, the rate of efficiency decrease also increases.

[0032] Figure 3 The process performed by ECU 50 is shown. ECU 50 estimates the temperature T of the housing (step S10). For example, ECU 50 estimates the air temperature at the outlet of compressor 18b based on the pressure at the inlet of compressor 18b, the boost pressure, the intake air temperature, the intake air flow rate, and the vehicle speed. ECU 50 estimates the temperature T of the housing based on the air temperature at the outlet.

[0033] ECU 50 determines whether the housing temperature T is equal to or greater than a predetermined temperature T0 (step S12). When the determination in step S12 is negative (N), ECU 50 terminates. Figure 3 The processing. On the other hand, when the determination in step S12 is affirmative (Y), ECU50 determines that deposits have been generated (step S14). After step S14, Figure 3 The processing is now complete.

[0034] In the first embodiment, the ECU 50 determines whether deposits have formed in the compressor 18b based on the temperature T of the compressor 18b housing. By predicting the formation of deposits, it can also predict the decrease in the efficiency of the compressor 18b due to the adhesion of deposits.

[0035] When the casing temperature T is equal to or higher than T0, ECU 50 determines that deposits have been generated. Figure 2 Step S14 in the process. Figure 2 As shown, when the temperature T is below T0, no deposits are expected to form and efficiency will not decrease. When the temperature T is equal to or higher than T0, insoluble substances in the oil concentrate and deposits form. That is, the temperature at which insoluble substances in the oil undergo a chemical change and become deposits is T0. By comparing the temperature T obtained by the ECU 50 with T0, deposit formation can be accurately predicted. The threshold T0 can be determined based on factors such as vehicle model, housing size, and material.

[0036] To improve the performance of the internal combustion engine 10, it is important to increase the boost pressure of the turbocharger 18. By increasing the boost pressure, the air temperature rises, and the casing temperature T also increases. Blow-by gas is recirculated into the intake air. When the oil in the blow-by gas is exposed to high temperatures, deposits are formed. As described above, based on the casing temperature T and a threshold T0, the ECU 50 predicts the formation of deposits. Thus, the improvement in the performance of the internal combustion engine 10 and the prediction of deposit formation can be achieved simultaneously.

[0037] Second Embodiment

[0038] In the second embodiment, the efficiency reduction of compressor 18b is obtained. Figure 1 The engine system 100 shown is also shared with the second embodiment. Descriptions of configurations identical to those in the first embodiment will be omitted.

[0039] Figure 4 The relationship between insoluble matter concentration and the rate of efficiency decline is shown. The horizontal axis represents the concentration of insoluble matter in the oil. The vertical axis represents the rate of efficiency decline of compressor 18b. Figure 4 As shown, the rate of efficiency decreases more rapidly with increasing insoluble concentration. This is because as the insoluble matter hardens, deposits are formed and adhere to the compressor 18b.

[0040] like Figure 2 As shown, the rate of efficiency decreases as the component temperature of compressor 18b increases. Figure 4 As shown, the rate of efficiency decrease increases with increasing concentration of insoluble matter in the oil. ECU 50 serves as a second unit for obtaining the insoluble matter concentration. Furthermore, ECU 50 serves as a third unit for obtaining the amount of efficiency decrease in compressor 18b based on component temperature and insoluble matter concentration.

[0041] Figure 5 The process performed by ECU 50 is shown. ECU 50 estimates the temperature T of the compressor 18b housing (step S20). For example, step S20 is related to... Figure 3 The same as step S10. ECU 50 obtains the efficiency decrease rate corresponding to temperature T (step S22).

[0042] The ECU 50 estimates the concentration of insoluble matter in the oil (step S24). For example, the ECU 50 obtains the insoluble matter concentration based on the fuel injection quantity and the temperature of the cooling water. The ECU 50 obtains the rate of efficiency decrease corresponding to the insoluble matter concentration (step S26).

[0043] The ECU 50 obtains the efficiency decline rate of the compressor 18b based on the efficiency decline rate corresponding to temperature and the efficiency decline rate corresponding to the concentration of insoluble matter. The ECU 50 multiplies the efficiency decline rate by the operating time of the internal combustion engine 10 and integrates / accumulates the efficiency decline (step S27). The ECU 50 calculates the efficiency decline amount through integration (step S28). Then, Figure 5 The processing is now complete.

[0044] In the second embodiment, the ECU 50 obtains the housing temperature of the compressor 18b and the concentration of insoluble substances in the oil. Based on the housing temperature and insoluble substance concentration of the compressor 18b, the ECU 50 obtains the amount of efficiency reduction of the compressor 18b. For example, when the efficiency reduction reaches a predetermined amount, the efficiency reduction can be suppressed by replacing components of the compressor 18b.

[0045] like Figure 2 As shown, the efficiency decrease rate (first decrease rate) is determined based on the casing temperature of compressor 18b. For example, when the temperature is Ta, the decrease rate is Va. Figure 4 As shown, the efficiency decrease rate (second decrease rate) is determined based on the insoluble matter concentration. For example, when the insoluble matter concentration is Xu, the decrease rate is Vb. When the temperature is Ta and the insoluble matter concentration is Xb, ECU 50 multiplies the decrease rate Va by the decrease rate Vb to calculate the efficiency decrease rate (Va·Vb) under that condition. The efficiency decrease is obtained by multiplying the decrease rate (Va·Vb) by the duration of the condition. As in the example above, the efficiency decrease is obtained by multiplying the decrease rate based on the condition (casing temperature and insoluble matter concentration) by the duration of maintaining that condition. ECU 50 can obtain the efficiency decrease of compressor 18b by integrating the efficiency decrease for each condition. Figure 5 Step S28 in the process.

[0046] ECU 50 estimates the air temperature at the outlet of compressor 18b based on the pressure at the compressor inlet, boost pressure, intake air temperature, intake air flow rate, and vehicle speed. ECU 50 estimates the housing temperature based on the outlet air temperature. ECU 50 estimates the insoluble concentration based on the fuel injection quantity and coolant temperature. In other words, ECU 50 obtains the housing temperature and insoluble concentration based on information obtained from the vehicle, and calculates the efficiency reduction based on these parameters. Because estimations are performed based on real-time vehicle information, the accuracy of the efficiency reduction estimation is improved.

[0047] Alternatively, sensors for detecting the housing temperature of compressor 18b and for detecting the concentration of insoluble matter can be installed in the vehicle. Based on the housing temperature and insoluble matter concentration detected by the sensors, ECU 50 can estimate the amount of efficiency reduction. Furthermore, as described above, ECU 50 can calculate the outlet temperature of compressor 18b based on boost pressure, etc., and calculate the housing temperature based on that outlet temperature. ECU 50 can calculate the insoluble matter concentration based on fuel injection quantity and coolant temperature. Since no sensors are installed, cost increases can be suppressed.

[0048] Third Embodiment

[0049] In the third embodiment, the attachment site of the deposit in the compressor 18b is predicted. Figure 1 The engine system 100 shown is also shared with the third embodiment. Descriptions of configurations identical to those in the first embodiment will be omitted.

[0050] Figure 6A Figure 6 shows a cross-sectional view of compressor 18b. Compressor 18b has an impeller 51 and a housing 52. The impeller 51 is housed within the housing 52. The impeller 51 is connected to a turbine (not shown) via a shaft 54. Air flows through compressor 18b as indicated by the arrows in Figure 6. The introduced air is pressurized by the rotation of the impeller 51 and sent to the internal combustion engine 10. In the housing 52, the portion located upstream in the airflow direction is called the shroud 52a, while the portion located downstream is called the diffuser 52b.

[0051] The deposits adhering to the casing 52 reduce the efficiency of the compressor 18b. The amount of efficiency reduction varies depending on the location of the deposits. The efficiency reduction caused by deposits adhering to the shroud 52a is greater than the efficiency reduction caused by deposits adhering to the diffuser 52b.

[0052] Figure 6B This is a schematic diagram illustrating the decrease in efficiency. Figure 6B In the example, assume the efficiency decrease is D1 (%). In D1, the contribution of deposits attached to the shroud 52a is D2 (%). In D1, the contribution of deposits attached to the diffuser 52b is D3 (%). D2 is greater than D3, for example, approximately twice D3. The deposits on the shroud 52a contribute more to the efficiency decrease than the deposits on the diffuser 52b.

[0053] ECU 50 is used as a fourth acquisition unit to obtain the air temperature (outlet temperature) at the outlet of compressor 18b and an estimation unit to estimate the deposit attachment site based on the outlet temperature.

[0054] Figure 7The process performed by ECU 50 is shown. ECU 50 estimates the air temperature T3 at the outlet of compressor 18b (step S30). ECU 50 estimates the temperature T of the compressor housing 18b (step S32). Based on the outlet temperature T3 and the housing temperature T, ECU 50 estimates the location of deposit adhesion (step S34). ECU 50 obtains the efficiency decline rate based on the location of deposit adhesion and the housing temperature T (step S36). The efficiency decline amount (e.g., ...) is obtained from the efficiency decline rate. Figure 5 ).Then, Figure 7 The processing is now complete.

[0055] In the third embodiment, the ECU 50 obtains the outlet temperature and uses this temperature to estimate the location of deposit adhesion. For example... Figure 6B As shown, the deposits on the shield 52a contribute more to the efficiency decrease than the deposits on the diffuser 52b. The ECU 50 obtains both the rate and amount of efficiency decrease based on the location of the deposit adhesion. By taking the location of the deposit adhesion into account, the accuracy of the estimated amount of efficiency decrease is improved.

[0056] While some embodiments of the invention have been described in detail, the invention is not limited to these specific embodiments, but various changes or modifications can be made within the scope of the claimed invention.

Claims

1. A control device for an internal combustion engine, said internal combustion engine being equipped with a turbocharger, in, The turbocharger includes a compressor, and The control device includes: A first acquisition unit configured to acquire the temperature of the compressor housing; A second obtaining unit configured to obtain the concentration of insoluble matter in the oil of the compressor; A third obtaining unit is configured to obtain the amount of efficiency reduction of the compressor based on the temperature and the concentration of insoluble matter; A fourth acquisition unit configured to acquire the temperature of the air in the compressor, and A determination unit configured to determine whether deposits have been generated in the compressor based on the temperature. The determination unit determines that the deposit has been generated when the temperature is equal to or higher than a predetermined temperature. The third obtaining unit obtains a first decreasing rate and a second decreasing rate. The first decreasing rate is the rate of decrease in compressor efficiency caused by the temperature, and the second decreasing rate is the rate of decrease in compressor efficiency caused by the concentration of insoluble matter. The third obtaining unit multiplies the product of the first descent rate and the second descent rate by the duration of the temperature corresponding to the first descent rate and the insoluble matter concentration corresponding to the second descent rate to obtain the efficiency reduction of the compressor. An estimation unit configured to estimate the attachment site of the deposit based on the temperature of the air. The third obtaining unit obtains the amount of efficiency reduction of the compressor based on the attachment location of the deposit.

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