Control device

Abstract

To perform warm-up operation in a hybrid vehicle provided with an engine and a motor as power sources, while reflecting the condition of fuel dilution.SOLUTION: A first coefficient related to the cooling water temperature at the time of start-up and a second coefficient related to the soak time before start-up are calculated. The slope of engine oil pressure rise at start-up is corrected using the first and second coefficients. Whether fuel dilution has occurred in the engine is determined by checking if the corrected result is below a specified threshold, and when fuel dilution is determined to have occurred, warm-up priority control is carried out to accelerate warming of the engine.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a control device mounted on a hybrid vehicle that has an engine and a motor as power sources. [Background technology]

[0002] The technology described in Patent Document 1 below is known regarding a control device mounted on a hybrid vehicle equipped with an engine and a motor as power sources. In Patent Document 1 below, when the engine oil temperature is below a predetermined temperature while the engine is running, the engine speed is kept below a certain level to prioritize warm-up operation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-146539 Summary of the Invention [Problem to be solved by the invention]

[0004] In hybrid vehicles equipped with an engine and a motor as power sources, the engine may be operated in a cold or warm-up state, which may cause engine oil to be diluted by unburned fuel or generated moisture, which is known as fuel dilution, and this may continue. To address this situation, it is necessary to perform warm-up priority operation in accordance with the fuel dilution state, rather than just performing warm-up priority operation when the engine oil temperature is below a predetermined temperature, as in Patent Document 1.

[0005] The present disclosure has an object to perform warm-up operation in a hybrid vehicle equipped with an engine and a motor as power sources, while reflecting the fuel dilution state. [Means for solving the problem]

[0006] The present disclosure relates to a control device mounted on a hybrid vehicle having an engine and a motor as power sources, which calculates a first coefficient relating to the coolant temperature at startup and a second coefficient relating to the soak time before startup, corrects the slope of the engine oil pressure increase at startup using the first coefficient and the second coefficient, determines whether fuel dilution has occurred in the engine oil in the engine based on whether the corrected result is below a predetermined threshold, and if it determines that fuel dilution has occurred, performs warm-up priority control to promote engine warm-up. [Effects of the Invention]

[0007] According to the present disclosure, in a hybrid vehicle equipped with an engine and a motor as power sources, it is possible to perform warm-up operation while reflecting the fuel dilution state. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a control device mounted on a hybrid vehicle. [Figure 2] FIG. 2 is a schematic diagram showing the schematic configuration of an engine mounted on the hybrid vehicle shown in FIG. [Figure 3] FIG. 3 is a flowchart showing the execution procedure of the operation control process. [Figure 4] FIG. 4 is a graph of engine oil pressure used in the explanation of FIG. [Figure 5] FIG. 5 is a graph for explaining the first coefficient Kw related to the coolant temperature at startup. [Figure 6] FIG. 6 is a graph for explaining the second coefficient Kt relating to the soak time before starting. [Figure 7] FIG. 7 is a graph for explaining the relationship between engine oil pressure and estimated fuel dilution value. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions will be omitted.

[0010] 1, a hybrid vehicle 10 is provided with an engine 11 and two motors as its power sources. In the following, the motor that is primarily used for generating electricity will be referred to as a generator 12, and the motor that is primarily used for generating power will be referred to as a motor 13.

[0011] The engine 11, generator 12, and motor 13 are connected to a power split mechanism 14 formed by a planetary gear mechanism. The power split mechanism 14 is also connected to drive wheels 16 via a speed reduction mechanism 15. The power split mechanism 14 splits the power of the engine 11 into power that drives the generator 12 and power that drives the drive wheels 16.

[0012] Hybrid vehicle 10 is further provided with a power control unit 17 having a boost converter and an inverter. The boost converter boosts the voltage of hybrid battery 18 to a voltage required to drive generator 12 and motor 13. The inverter converts the high-voltage DC current boosted by the boost converter into AC current to be supplied to generator 12 and motor 13, and also converts the AC current generated by generator 12 and motor 13 into DC current when generator 12 and motor 13 function as generators.

[0013] As shown in Figure 2, a piston 21 is housed in a cylinder of the engine 11 so that it can reciprocate. A crankshaft 22 is connected to the piston 21 via a connecting rod 23. A combustion chamber 24 is defined inside the engine 11 by the top surface of the piston 21 and the inner circumferential surface of the cylinder. An intake passage 26 is connected to the combustion chamber 24 via an intake valve 25, and an exhaust passage 28 is connected to the combustion chamber 24 via an exhaust valve 27. A fuel injection valve 29 is attached to the intake passage 26 to inject fuel into the intake passage 26. A spark plug 30 is also provided in the combustion chamber 24 to ignite the mixture of intake air and fuel.

[0014] When the engine 11 is operating, air is drawn into the combustion chamber 24 through the intake passage 26 and fuel is supplied through a fuel injection valve 29. When a mixture of the intake air and injected fuel in the combustion chamber 24 is ignited through a spark discharge from a spark plug 30, the mixture burns and the piston 21 moves back and forth, thereby rotating the crankshaft 22. The combusted mixture is sent out as exhaust gas from the combustion chamber 24 of the engine 11 to an exhaust passage 28.

[0015] An intake camshaft 31 for opening and closing the intake valve 25 and an exhaust camshaft 32 for opening and closing the exhaust valve 27 are provided inside the engine 11. Lash adjusters 33 for automatically adjusting valve clearance are provided between the intake camshaft 31 and the intake valve 25, and between the exhaust camshaft 32 and the exhaust valve 27.

[0016] The engine 11 is also equipped with an oil pan 34 that stores engine oil and an oil pump 35 that pumps the engine oil. When the oil pump 35 is operated, the engine oil in the oil pan 34 is supplied to the crankshaft 22, the bearings of the camshafts 31 and 32, the lash adjusters 33, and the like.

[0017] 1, hybrid vehicle 10 is provided with various sensors for determining its operating state. Examples of such sensors include a crank sensor 41 for detecting the rotation speed of crankshaft 22 (see FIG. 2) and a temperature sensor 42 for detecting the temperature of engine oil. Other sensors provided include a pressure sensor 43 for detecting the pressure of engine oil pumped by oil pump 35 (see FIG. 2), a vehicle speed sensor 44 for detecting the traveling speed of hybrid vehicle 10, and a water temperature sensor 45 for detecting the temperature of engine water.

[0018] The hybrid vehicle 10 is also provided with a control device 40 that includes a microcomputer. The control device 40 receives output signals from various sensors and determines the operating state of the hybrid vehicle 10 based on these output signals. Then, depending on the determined operating state, the control device 40 controls the operation of the engine 11, such as controlling the operation of the fuel injection valve 29 (see FIG. 2) and the spark plug 30, and controls the operation of the generator 12 and the motor 13.

[0019] Next, the control executed by the control device 40 will be described with reference to Fig. 3. In step S01, the control device 40 determines whether the engine 11 is being started for the first time. If the engine 11 is being started for the first time (step S01: YES), the process proceeds to steps S02 and S03. If the engine 11 is not being started for the first time (step S01: NO), the process ends.

[0020] In step S02, the control device 40 calculates a first coefficient Kw for the start-up water temperature sensitivity. The first coefficient Kw is set as a factor that affects the start-up water temperature, which will be described later, the hydraulic pressure gradient ΔP of the engine oil. As shown in FIG. 5, the first coefficient Kw increases as the start-up water temperature increases, and decreases as the start-up water temperature decreases. The control device 40 determines the first coefficient Kw for the start-up water temperature sensitivity based on the water temperature data detected by the water temperature sensor 45, using a map such as that shown in FIG. 5.

[0021] In step S03, the control device 40 calculates a second coefficient Kt for the soak time sensitivity. The second coefficient Kt is set as a factor that determines how the soak time affects the engine oil pressure gradient ΔP, which will be described later. As shown in FIG. 6, the second coefficient Kt decreases as the soak time increases and the time the engine 11 is stopped increases, and increases as the soak time decreases and the time the engine 11 is stopped decreases. The control device 40 calculates the soak time based on the start signal and stop signal of the engine 11 and determines the second coefficient Kt for the soak time sensitivity using a map such as that shown in FIG. 6.

[0022] After the processes of steps S02 and S03 are completed, the process proceeds to step S04. In step S04, the control device 40 calculates the hydraulic pressure gradient ΔP at the time of initial engine start. The hydraulic pressure gradient ΔP at the time of initial engine start is calculated based on the engine oil pressure data detected by the pressure sensor 43.

[0023] 4A illustrates the change in the hydraulic pressure gradient ΔP at the initial engine start depending on the degree of engine oil dilution (fuel dilution), and FIG. 4B illustrates the corresponding engine speed. As illustrated in FIG. 4, the hydraulic pressure gradient ΔP2 when the engine oil is diluted is smaller than the hydraulic pressure gradient ΔP1 when the engine oil is not diluted. In this embodiment, the degree of engine oil dilution is estimated by focusing on this point.

[0024] In step S04, the control device 40 determines whether the hydraulic pressure gradient taking the correction coefficient into consideration is below a threshold hydraulic pressure gradient. Specifically, the hydraulic pressure gradient ΔP at the initial engine start calculated in step S04 is multiplied by the first coefficient Kw calculated in step S02 and the second coefficient Kt calculated in step S03, and determines whether the hydraulic pressure gradient is below a threshold hydraulic pressure gradient ΔP2. As illustrated in Figure 7, as the hydraulic pressure gradient ΔP decreases, the estimated engine oil fuel dilution value increases, and as the hydraulic pressure gradient ΔP increases, the estimated engine oil fuel dilution value decreases.

[0025] If ΔP×Kw×Kt is less than ΔP2 (step S05: YES), the process proceeds to step S06. If ΔP×Kw×Kt is not less than ΔP2 (step S05: NO), the process proceeds to step S07.

[0026] In step S06, the control device 40 executes engine warm-up priority control. The engine warm-up priority control, for example, controls the rotation speed of the engine 11 to a predetermined low rotation speed, and controls the operation of the motor 13 so as to obtain a desired driving torque. In step S07, the control device 40 executes normal operation control.

[0027] As described above, the control device 40 of this embodiment is a control device mounted on a hybrid vehicle having an engine and a motor as power sources, and calculates a first coefficient Kw related to the coolant temperature at startup and a second coefficient Kt related to the soak time before startup, corrects the slope of the engine oil pressure increase at startup using the first coefficient Kw and the second coefficient Kt, and determines whether fuel dilution has occurred in the engine oil in the engine based on whether the corrected result is below a predetermined threshold value.If it is determined that fuel dilution has occurred in the engine oil, it performs dilution control to promote engine warm-up.

[0028] According to this embodiment, the slope of the engine oil pressure rise at startup, which is closely related to the occurrence of fuel dilution, is corrected by the cooling water temperature and soak time at startup, which affect it, to determine fuel dilution, so that appropriate warm-up promotion control can be performed when there is a concern that fuel dilution may occur.

[0029] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples made by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements of the above-described specific examples, as well as their arrangement, conditions, shape, etc., are not limited to those exemplified and can be modified as appropriate. The elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise. [Explanation of symbols]

[0030] 10: Hybrid vehicle 11: Engine 12: Generator 13: Motor 40: Control device

Claims

[Claim 1] A control device mounted on a hybrid vehicle equipped with an engine and a motor as power sources, Calculating a first coefficient related to the coolant temperature at startup and a second coefficient related to the soak time before startup; correcting a slope of engine oil pressure increase at start-up using the first coefficient and the second coefficient, and determining whether fuel dilution of engine oil has occurred in the engine based on whether the corrected result is below a predetermined threshold value; When it is determined that the fuel dilution has occurred, the control device performs warm-up priority control to promote warm-up of the engine.

Images