Oil dilution elimination device

Abstract

To provide an oil dilution solving apparatus capable of quickly solving oil dilution caused by mixture of fuel into engine oil.SOLUTION: An ECU 80 estimates friction of an engine 20, on the basis of an amount of intake air requied for keeping an idling speed at a predetermined rotation rate, and determines that oil dilution is occurring when the amount of intake air requied for keeping the idling speed at the predetermined rotation rate decreases to a level lower than or equal to a predetermined threshold. In order to operate the engine 20 at a higher speed, the ECU 80 requests a TCU 50 to perform shift control of an automatic transmission 30 so that the engine 20 is operated at a higher speed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0004] , , , , , , , , , , ,

[0005]

[0001] The present invention relates to an oil dilution elimination device that eliminates oil dilution caused by fuel mixing into engine oil.

Background Art

[0002] In an engine, so-called oil dilution (oil thinning), in which engine oil is diluted, may occur when fuel mixes with the engine oil. In particular, in an in-cylinder injection engine in which fuel is directly injected into the cylinder, for example, fuel adheres to the inner peripheral surface of the cylinder, and the fuel mixes with the engine oil, making it easier for the engine oil to be diluted by the fuel (oil dilution).

[0003] When oil dilution occurs, for example, the fuel mixed in the engine oil volatilizes, and a large amount of blow-by gas containing fuel is introduced (inhaled) into the intake system, which may cause a disturbance (e.g., richening) in the air-fuel ratio.

[0004] Here, Patent Document 1 discloses a technique for more quickly suppressing the disturbance of the air-fuel ratio due to the volatilization of fuel in engine oil. More specifically, in this technique, a reflection rate REF is set as a value proportional to the amount of blow-by gas released into the intake air, and the fuel injection amount is corrected with the product obtained by multiplying the reflection rate REF by a dilution learning value LDIL as a correction value. The value of the dilution learning value LDIL is updated so that the value of the air-fuel ratio F / B correction value FAF approaches 0 on the condition that the fuel dilution amount of the engine oil is equal to or greater than a preset value.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] As described above, the technology described in Patent Document 1 can more quickly suppress disturbances in the air-fuel ratio caused by the vaporization of fuel in the engine oil. However, the technology described in Patent Document 1 does not take into consideration the rapid resolution of oil dilution, which is the cause of disturbances in the air-fuel ratio. Therefore, it was not possible to prevent the deterioration of engine oil performance (deterioration of function) due to oil dilution.

[0007] The present invention was made to solve the above-mentioned problems, and aims to provide an oil dilution elimination device that can quickly eliminate oil dilution caused by fuel mixing with engine oil. [Means for solving the problem]

[0008] The oil dilution elimination device according to the present invention is an oil dilution elimination device that eliminates oil dilution caused by the mixing of fuel with engine oil, and is characterized by comprising a control unit that estimates the friction of the engine, determines that oil dilution is occurring when the friction of the engine falls below a predetermined threshold, and controls the engine to operate at a higher rotational speed. [Effects of the Invention]

[0009] According to the present invention, it is possible to quickly resolve oil dilution caused by fuel mixing with engine oil. [Brief explanation of the drawing]

[0010] [Figure 1] This is a block diagram showing an oil dilution elimination device according to an embodiment, and the configuration of an engine and automatic transmission to which the oil dilution elimination device is applied. [Figure 2]This flowchart shows the processing procedure for oil dilution elimination control by the oil dilution elimination device according to the embodiment. [Figure 3] This figure shows an example of a gear shift diagram for an automatic transmission (step AT) used in oil dilution elimination control. [Modes for carrying out the invention]

[0011] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts will be denoted by the same reference numerals. In addition, in each drawing, the same elements will be denoted by the same reference numerals, and redundant explanations will be omitted.

[0012] First, the configuration of the oil dilution elimination device 1 according to this embodiment will be explained using Figure 1. Figure 1 is a block diagram showing the configuration of the oil dilution elimination device 1, and the engine 20 and automatic transmission 30 to which the oil dilution elimination device 1 is applied.

[0013] The engine 20 can be of any type, but for example, it is a horizontally opposed, direct-injection, four-cylinder gasoline engine. In the engine 20, air drawn in from an air cleaner (not shown) is restricted by an electronically controlled throttle valve (hereinafter also simply called "throttle valve") 87 located in the intake manifold, passes through the intake manifold, and is drawn into each cylinder formed in the engine 20. Here, the amount of air drawn in from the air cleaner is detected by an airflow meter 81. Furthermore, the throttle valve 87 is equipped with a throttle opening sensor 82 that detects the opening degree of the throttle valve 87. Each cylinder is fitted with an injector that injects fuel. Each cylinder is also fitted with a spark plug that ignites the air-fuel mixture, and an igniter-integrated coil that applies a high voltage to the spark plug. In each cylinder of the engine 20, the air-fuel mixture is ignited by the spark plug and combusted. The exhaust gas after combustion is discharged through the exhaust pipe.

[0014] In addition to the airflow meter 81 and throttle position sensor 82 mentioned above, a cam angle sensor 86 for cylinder identification of the engine 20 is mounted near the camshaft of the engine 20. A crank angle sensor 85 for detecting the position of the crankshaft is mounted near the crankshaft of the engine 20. These sensors are connected to the engine control unit (hereinafter referred to as "ECU") 80, which will be described later. The ECU 80 is also connected to various other sensors, such as an accelerator pedal position sensor 83 for detecting the amount the accelerator pedal is pressed, i.e., the opening angle of the accelerator pedal, and a water temperature sensor 84 for detecting the temperature of the coolant in the engine 20.

[0015] A stepped automatic transmission (step AT) 30 (corresponding to the automatic transmission described in the claims, hereinafter also simply referred to as "automatic transmission") is connected to the output shaft (crankshaft) 21 of the engine 20 via a torque converter 22 having a clutch function and a torque amplification function, which converts and outputs the driving force (torque) from the engine 20.

[0016] The torque converter 22 mainly consists of a pump impeller 23, a turbine runner 24, and a stator 25. The pump impeller 23, connected to the output shaft 21, generates an oil flow, and the turbine runner 24, positioned opposite the pump impeller 23, receives power from the engine 20 via the oil and drives the output shaft 27. The stator 25, located between the two, rectifies the discharge flow (return) from the turbine runner 24 and returns it to the pump impeller 23, thereby generating a torque amplification effect. The torque converter 22 also has a lock-up clutch 26 that directly connects the input and output. When not in the lock-up state, the torque converter 22 amplifies the driving force of the engine 20 and transmits it to the automatic transmission 30, and when locked up, it directly transmits the driving force of the engine 20 to the automatic transmission 30.

[0017] The automatic transmission 30 is configured to have a transmission mechanism 31 including a transmission gear train. More specifically, the transmission mechanism 31 is configured to have a plurality of planetary gear sets 32, each having a plurality of planetary gears composed of, for example, sun gears, ring gears, pinion gears, etc., and friction engagement elements 33 such as clutches and brakes for switching (i.e., changing gears) the power transmission paths of the plurality of planetary gear sets 32. Therefore, the transmission of the automatic transmission 30 is performed by engaging or disengaging the friction engagement elements such as clutches (hereinafter simply referred to as "clutches, etc." or "clutch") 33. Note that known mechanisms can be used as the hardware of the transmission mechanism 31.

[0018] Furthermore, instead of a planetary gear type automatic transmission, a parallel twin-shaft stepped automatic transmission may be used as the automatic transmission 30, for example, which selectively switches between combinations of gear trains provided on each of a pair of parallel shafts by engaging and disengaging multiple wet clutches to obtain a finite number of gear stages. Alternatively, instead of a stepped automatic transmission (step AT), a continuously variable transmission (CVT) such as a chain type or belt type, or a DCT (Dual Clutch Transmission) which has independent clutches for the odd-numbered and even-numbered gear sets and switches between them sequentially to perform gear changes, may be used.

[0019] The driving force (torque) input from the engine 20 is converted by the automatic transmission 30 and then transmitted from the output shaft 35 of the automatic transmission 30 to the drive wheels of the vehicle via, for example, a propeller shaft, differential gear, drive shaft, etc. (not shown).

[0020] The engine 20 is controlled by the ECU 80. The ECU 80 includes a microprocessor that performs calculations, an EEPROM that stores programs for causing the microprocessor to execute each process, a RAM that stores various data such as calculation results, a backup RAM whose stored content is retained by a battery, and an input / output I / F and the like. As described above, various sensors such as an air flow meter 81, a throttle opening sensor 82, an accelerator pedal opening sensor 83, a water temperature sensor 84, a crank angle sensor 85, and a cam angle sensor 86 are connected to the ECU 80.

[0021] In the ECU 80, the cylinder is discriminated from the output of the cam angle sensor 86, and the engine speed is obtained from the change in the rotational position of the crankshaft detected by the output of the crank angle sensor 85. Also, in the ECU 80, various information such as the intake air amount, the accelerator pedal opening, the air-fuel ratio of the air-fuel mixture, and the water temperature is acquired based on the detection signals input from the various sensors described above. Then, the ECU 80 comprehensively controls the engine 20 by controlling various devices such as the fuel injection amount, the ignition timing, and the throttle valve 87 based on the acquired various information.

[0022] Here, the ECU 80 is communicably connected to a transmission control unit (hereinafter referred to as "TCU") 50 that controls the automatic transmission 30 and the like via a CAN (Controller Area Network) 100.

[0023] The ECU 80 transmits information such as the engine speed, the accelerator pedal opening, the engine torque, and the engine water temperature (cooling water temperature) to the TCU 50 and the like via the CAN 100.

[0024] The hydraulic pressure required to shift the automatic transmission 30, that is, the engagement and disengagement of the clutch etc. 33 described above, is controlled by the valve body (control valve) 60. The valve body 60 adjusts the hydraulic pressure discharged from the oil pump by opening and closing an oil passage formed within the valve body 60 using a spool valve and a solenoid valve (electromagnetic valve) that moves the spool valve, thereby supplying hydraulic pressure to the clutch etc. 33 for engaging and disengaging the clutch etc. 33.

[0025] The shift control of the automatic transmission 30 is performed by the TCU 50. Specifically, the TCU 50 changes the gear of the automatic transmission 30 by adjusting the hydraulic pressure supplied to the clutch etc. 33 by controlling the drive of the solenoid valves that constitute the valve body 60 described above.

[0026] The TCU50 is connected to an output shaft rotation sensor 53, which is mounted near the output shaft 35 of the automatic transmission 30 and detects the rotational speed of the output shaft 35. The TCU50 is also connected to a range switch 54, which detects the selected position of the shift lever. Furthermore, the TCU50 receives information such as wheel speed (vehicle speed), engine speed, accelerator pedal opening, and engine torque via the CAN100.

[0027] The TCU50 consists of a microprocessor that performs calculations, an EEPROM that stores programs and shift maps for the microprocessor to execute various processes, a RAM that stores various data such as calculation results, a backup RAM whose contents are maintained by a battery, and input / output interfaces.

[0028] The TCU 50 controls the shifting of the automatic transmission 30 based on various information acquired, such as the output shaft rotation speed (vehicle speed), accelerator pedal opening, and shift position of the shift lever (state of the range switch 54). In doing so, the TCU 50 automatically changes the gear according to the vehicle's driving conditions (e.g., accelerator pedal opening and vehicle speed) according to the gear shift diagram (gear shift map). The gear shift diagram (gear shift map) is stored in the EEPROM of the TCU 50. In addition, the TCU 50 controls the gear ratio (gear shift) of the automatic transmission 30 to operate the engine 20 at a higher rotation speed in response to a request from the ECU 80 (details will be described later).

[0029] In particular, the ECU80 and TCU50 work together to quickly resolve oil dilution caused by the mixing of fuel (gasoline) with engine oil. This function is realized in the ECU80 and TCU50 by the execution of a program stored in an EEPROM or the like by a microprocessor. The ECU80 and TCU50 function as the control units described in the claims.

[0030] The ECU 80 estimates the friction of the engine 20. When the friction of the engine 20 falls below a predetermined threshold, the ECU 80 determines that oil dilution is occurring and controls the engine 20 to operate at a higher rotational speed compared to when oil dilution is not occurring.

[0031] Incidentally, when oil dilution occurs, the kinematic viscosity of the engine oil decreases, reducing engine friction and decreasing the amount of intake air required to maintain the idling speed at a predetermined speed (amount of intake air required to maintain idling speed). In other words, the amount of intake air required to maintain the idling speed at a predetermined speed is an index value that correlates with the friction of the engine 20 (and consequently, the presence or absence of oil dilution). More specifically, the ECU 80 learns the deviation (deviation) from a reference value of the amount of intake air required to maintain the idling speed at a predetermined speed (amount of intake air at idle). For example, the ECU 80 learns (the deviation from the reference value) using a feedback value (a feedback value that corrects the throttle valve 87 to open) to correct the deviation from the reference value (target opening) of the amount of intake air at idle (throttle valve opening).

[0032] Then, when the amount of intake air required to maintain the idling speed at a predetermined speed falls below a predetermined threshold, the ECU 80 determines that the friction of the engine 20 has decreased, that is, that oil dilution is occurring, and controls the engine 20 to operate at a higher speed.

[0033] Furthermore, the ECU80 determines that the greater the decrease in the amount of intake air required to maintain the idling speed at a predetermined speed, the greater the decrease in friction of the engine 20 and the greater the degree of oil dilution (the greater the amount of fuel mixed in the engine oil). On the other hand, the ECU80 determines that if the amount of intake air required to maintain the idling speed at a predetermined speed does not decrease below a predetermined threshold, then oil dilution has not occurred or has been resolved.

[0034] When the ECU 80 determines that oil dilution is occurring, and controls the engine 20 to operate at a higher rotational speed, it requests the TCU 50 to control the gear ratio (gear stage) of the automatic transmission 30 so that the engine 20 operates at a higher rotational speed (by lowering the gear ratio in the gear diagram) (by sending the request information via CAN 100).

[0035] On the other hand, when the TCU50 receives the above request from the ECU80 via the CAN100, it adjusts the gear ratio of the automatic transmission 30 used for gear shift control to a lower gear in response to the request from the ECU80, so that the engine 20 is operated at a higher rotational speed.

[0036] Here, Figure 3 shows an example of a gear shift diagram for an automatic transmission (step AT) 30 used in oil dilution elimination control. In Figure 3, the horizontal axis is vehicle speed (km / h) and the vertical axis is accelerator opening (%). In Figure 3, the gear shift diagram used during normal gear shift control is shown as a solid line, and the gear shift diagram used during oil dilution elimination control is shown as a dotted line. As shown in Figure 3, during oil dilution elimination control, a gear shift (upshift) is performed at any gear when the vehicle speed becomes higher than during normal control (higher vehicle speed for the upshift point). In other words, a gear shift (upshift) is not performed until the vehicle speed becomes higher than during normal control (lower gearing). As a result, the operating range of the engine 20 shifts to or expands to a higher rotational speed than during normal control, and the engine oil temperature rises.

[0037] Furthermore, it is preferable that the ECU80 and TCU50 control the gear ratio (gear stage) of the automatic transmission 30 (making the gear diagram lower) so that the engine 20 is operated at a higher rotational speed as the decrease (amount of decrease) of the intake air volume required to maintain the idling speed at a predetermined rotational speed increases.

[0038] Furthermore, it is preferable that the ECU80 and TCU50 take the engine oil temperature (oil temperature) into consideration and execute the control (process) to resolve the oil dilution described above after the engine 20 has finished warming up (i.e., after the kinematic viscosity of the engine oil has decreased and stabilized). The ECU80 can determine whether or not the engine has finished warming up based on the coolant temperature and oil temperature of the engine 20.

[0039] Next, the operation of the oil dilution elimination device 1 will be explained with reference to Figure 2. Figure 2 is a flowchart showing the processing procedure for oil dilution elimination control by the oil dilution elimination device 1. This process is mainly performed repeatedly at predetermined timings in the ECU 80 and TCU 50.

[0040] After the engine 20 has warmed up, in step S100, the amount of intake air required to maintain the idling speed at a predetermined speed is acquired (learned). The method for acquiring (learning) the amount of intake air required to maintain the idling speed at a predetermined speed is as described above, so a detailed explanation is omitted here.

[0041] Next, in step S102, a determination is made as to whether the amount of intake air required to maintain the idling speed at a predetermined rotational speed has decreased to below a predetermined threshold. If the amount of intake air required to maintain the idling speed at a predetermined rotational speed has decreased to below a predetermined threshold (i.e., it is determined that oil dilution has occurred), the process proceeds to step 104. On the other hand, if the amount of intake air required to maintain the idling speed at a predetermined rotational speed has not decreased to below a predetermined threshold (i.e., it is determined that oil dilution has not occurred, or that oil dilution has been resolved), the process is temporarily exited. Then, normal gear shift control is performed using the gear shift diagram used during normal control.

[0042] In step S104, the gear ratio (gear stage) of the automatic transmission 30 is controlled so that the engine 20 is operated at a higher rotational speed (the gear ratio is lowered). The details of this control are as described above, so a detailed explanation is omitted here. As a result, the engine oil is heated, the fuel (gasoline) mixed in the engine oil evaporates, and oil dilution is eliminated. After that, the process is exited.

[0043] As described in detail above, according to this embodiment, when the amount of intake air required to maintain the idling speed at a predetermined rotational speed falls below a predetermined threshold, it is determined that the friction of the engine 20 has decreased, that is, that oil dilution has occurred, and the engine 20 is controlled to operate at a higher rotational speed. Therefore, when oil dilution occurs, the operating range of the engine 20 is increased to a higher rotational speed, and the temperature of the engine oil is promoted. Consequently, the evaporation of fuel (gasoline) mixed in the engine oil is promoted, and the oil dilution is quickly resolved. As a result, it is possible to quickly resolve oil dilution caused by the mixing of fuel (gasoline) with the engine oil.

[0044] Furthermore, according to this embodiment, when the engine 20 is controlled to operate at a higher rotational speed, the gear ratio (gear stage) of the automatic transmission 30 is controlled to allow the engine 20 to operate at a higher rotational speed (the gear ratio is lowered). As a result, the operating range of the engine 20 is increased, which promotes the temperature rise of the engine oil. Consequently, the vaporization of fuel mixed in the engine oil can be promoted.

[0045] Furthermore, according to this embodiment, the greater the decrease (amount of decrease) in the amount of intake air required to maintain the idling speed at a predetermined rotational speed, the greater the decrease in the gear ratio (gear stage) of the automatic transmission 30, so that the engine 20 is operated at a higher rotational speed (the gear ratio becomes lower). Therefore, depending on the degree of oil dilution, the gear ratio (gear stage) of the automatic transmission 30 can be made lower (the vehicle speed at which the shift-up point occurs can be increased). Thus, the worse the degree of oil dilution (the greater the amount of fuel mixed in the engine oil), the higher the operating range of the engine 20 can be moved to or expanded, thereby further promoting the rise in engine oil temperature (i.e., further promoting the vaporization of the mixed fuel).

[0046] According to this embodiment, after the engine 20 has finished warming up, control (processing) is performed to eliminate the oil dilution described above. Therefore, after the kinematic viscosity of the engine oil has decreased and stabilized, it is possible to determine whether or not oil dilution has occurred, and thus the presence or absence of oil dilution can be determined more accurately.

[0047] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be modified in various ways. For example, in the above embodiments, the present invention was described using the case where it is applied to a planetary gear type stepped automatic transmission (step AT) 30 as an example, but instead of the planetary gear type stepped automatic transmission 30, it may be applied to, for example, a parallel twin-shaft type stepped automatic transmission. Also, instead of the stepped automatic transmission (step AT) 30, it may be applied to, for example, a chain type or belt type continuously variable transmission (CVT) or a DCT. When applied to a continuously variable transmission (CVT), for example, it is preferable to shift the gear ratio to the low side so that the rotational speed of the engine 20 increases at the same vehicle speed.

[0048] Furthermore, although the above embodiment described the present invention as being applied to a gasoline engine vehicle using a gasoline engine 20 as a driving force source, the present invention is also applicable to HEVs (hybrid electric vehicles) and PHEVs (plug-in hybrid electric vehicles) that use an electric motor or the like in addition to a gasoline engine 20 as a driving force source.

[0049] Furthermore, the system configuration is not limited to the configuration of the above embodiment. For example, in the above embodiment, the ECU 80 that controls the engine 20 and the TCU 50 that controls the automatic transmission 30 are configured as separate hardware, but they may be configured as a single piece of hardware. [Explanation of Symbols]

[0050] 1. Oil Dilution Elimination Device 20 Engine 22 Torque Converter 30 Automatic transmission 31. Transmission 32 Planetary Gear Set 33 Clutch 35 Output shaft 50 TCU 53 Output shaft rotation sensor 54 Range switch 60 Valve Body 80 ECU 81 Airflow Meter 82 Throttle position sensor 83. Accelerator pedal position sensor 84 Water temperature sensor 85 Crank angle sensor 86 Cam angle sensor 87 Electronic throttle valve 100 CAN

Claims

1. An oil dilution elimination device that eliminates oil dilution caused by fuel mixing with engine oil, The system includes a control unit that estimates engine friction, determines that oil dilution is occurring when the engine friction falls below a predetermined threshold, and controls the engine to operate at a higher rotational speed compared to when oil dilution is not occurring. The oil dilution elimination device is characterized in that the control unit performs control to eliminate the oil dilution after the engine has finished warming up.

2. The aforementioned control unit is Based on the amount of intake air required to maintain the idling speed at a predetermined rotational speed, the friction of the engine is estimated. If the amount of intake air required to maintain the idling speed at a predetermined rotational speed falls below a predetermined threshold, it is determined that oil dilution is occurring, and the system is controlled to operate the engine at a higher rotational speed compared to when oil dilution is not occurring. The oil dilution elimination device according to feature 1.

3. The oil dilution elimination device according to claim 2, characterized in that when the control unit controls the engine to operate at a higher rotational speed compared to when oil dilution does not occur, it controls the gear ratio of the automatic transmission that converts and outputs the torque generated by the engine to operate at a higher rotational speed compared to when oil dilution does not occur.

4. The oil dilution elimination device according to claim 3, characterized in that the control unit controls the gear ratio of the automatic transmission so that the engine is operated at a higher rotational speed compared to when oil dilution does not occur, as the decrease in the amount of intake air required to maintain the idling speed at a predetermined rotational speed increases.

5. The oil dilution elimination device according to claim 3, characterized in that when the control unit controls the engine to operate at a higher rotational speed compared to when oil dilution does not occur, it uses a gear shift diagram in which the shift-up vehicle speed for each gear at the same accelerator opening is set higher than the gear shift diagram used when oil dilution does not occur.

Images