Control device for hybrid vehicle

Abstract

To provide a control device for a hybrid vehicle capable of suppressing damage during cranking.SOLUTION: A control device for a hybrid vehicle includes: an acquisition section that acquires hydraulic pressure of engine oil; and a cranking control section that performs cranking of an internal combustion engine by using an electric motor. When the hydraulic pressure is a predetermined value or lower, the cranking control section sets rotational frequency of the cranking to a first value, and when the hydraulic pressure is the predetermined value or higher, the cranking control section sets the rotational frequency of the cranking to a second value that is higher than the first value.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a control device for a hybrid vehicle. [Background technology]

[0002] 2. Description of the Related Art Hybrid vehicles equipped with an internal combustion engine and an electric motor are known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-206021 A Summary of the Invention [Problem to be solved by the invention]

[0004] An internal combustion engine can be started by cranking it with an electric motor. However, immediately after filling the engine with oil, air may be present in the oil path. This causes air to be sent to the internal combustion engine, resulting in insufficient lubrication performance. If cranking is performed in this state, damage such as seizure may occur to the parts. Therefore, the object of the present invention is to provide a control device for a hybrid vehicle that can suppress damage during cranking. [Means for solving the problem]

[0005] The above object can be achieved by a control device for a hybrid vehicle, comprising an acquisition unit that acquires engine oil oil pressure and a cranking control unit that cranks an internal combustion engine using an electric motor, wherein when the oil pressure is less than a predetermined value, the cranking control unit sets the cranking speed to a first value, and when the oil pressure is equal to or greater than the predetermined value, the cranking control unit sets the cranking speed to a second value higher than the first value. Effect of the Invention

[0006] It is possible to provide a control device for a hybrid vehicle that is capable of suppressing damage during cranking. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic configuration diagram of a vehicle according to this embodiment. [Diagram 2] FIG. 2 is a flowchart illustrating a process according to the embodiment. [Diagram 3] FIG. 3 is a diagram illustrating an example of a time chart. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] FIG. 1 is a schematic configuration diagram of a vehicle 1 according to this embodiment. The vehicle 1 is a hybrid vehicle, and includes an ECU (Electronic Control Unit) 40, an engine 10 (internal combustion engine), a first motor generator (hereinafter referred to as "first MG (Motor Generator)") 14, a second motor generator (hereinafter referred to as "second MG") 15, a PCU (Power Control Unit) 17, a battery 18, a torsional damper 19, a power split mechanism 20, a reduction mechanism 22, a differential gear 24, and drive wheels 26. The engine 10 may be a gasoline engine or a diesel engine. The engine 10, the first MG 14, and the second MG 15 are power sources for driving the vehicle 1.

[0009] The first MG 14 and the second MG 15 function as an electric motor and a generator. The first MG 14 and the second MG 15 output torque when supplied with driving power, and generate regenerative power when torque is applied to them. The first MG 14 and the second MG 15 are, for example, AC rotating electric machines. The AC rotating electric machine is, for example, a permanent magnet type synchronous motor having a rotor with a permanent magnet embedded therein.

[0010] The first MG 14 and the second MG 15 are electrically connected to the battery 18 via the PCU 17. The PCU 17 charges the battery 18 using regenerative power generated in the first MG 14 or the second MG 15, and drives the first MG 14 or the second MG 15 using the charging power of the battery 18. The PCU 17 includes a first inverter that exchanges power with the first MG 14, a second inverter that exchanges power with the second MG 15, and a converter. The converter boosts the power of the battery 18 and supplies it to the first and second inverters, and reduces the power supplied from the first and second inverters and supplies it to the battery 18. The first inverter converts the DC power from the converter into AC power and supplies it to the first MG 14, and converts the AC power from the first MG 14 into DC power and supplies it to the converter. The second inverter converts DC power from the converter into AC power and supplies it to second MG 15, and converts AC power from second MG 15 into DC power and supplies it to the converter.

[0011] The battery 18 is composed of a plurality of stacked cells. The cells are, for example, secondary cells such as nickel-metal hydride cells or lithium-ion cells.

[0012] The power split mechanism 20 is, for example, a planetary gear mechanism including a sun gear, a planetary carrier, a pinion gear, and a ring gear. The crankshaft 27 of the engine 10 is connected to the power split mechanism 20 via a torsional damper 19. The power split mechanism 20 mechanically connects the crankshaft 27 of the engine 10, the rotating shaft of the first MG 14, and the output shaft of the power split mechanism 20.

[0013] The reduction mechanism 22 is a multi-stage automatic transmission that changes the gear ratio. Under the control of the ECU 40, the reduction mechanism 22 changes the gear ratio and switches between a plurality of power transmission states. The plurality of power transmission states include an N (neutral) range, a D (drive) range, an R (reverse) range, and a P (parking) range. Instead of the reduction mechanism 22, a continuously variable transmission (CVT) that continuously changes the gear ratio may be employed.

[0014] An output shaft of the power split mechanism 20 is connected to a reduction mechanism 22. A rotating shaft of the second MG 15 is also connected to the reduction mechanism 22. The reduction mechanism 22 is connected to a differential gear 24. A drive shaft 25 is connected to the differential gear 24. A drive wheel 26 is attached to the tip of the drive shaft 25.

[0015] The engine 10, the first MG 14, and the second MG 15 function as drive sources that generate drive forces. The drive forces of the engine 10, the first MG 14, and the second MG 15 are transmitted to drive wheels 26 via a speed reduction mechanism 22 and a differential gear 24.

[0016] For example, the engine 10 can be started by cranking the engine 10 using the first MG 14. In detail, the driving force generated by the first MG 14 is transmitted to the crankshaft of the engine 10 via the power split mechanism 20 and the like, causing the crankshaft to rotate.

[0017] The oil pump 30 operates in response to the rotation of the engine 10, pumping up oil (engine oil) from an oil pan (not shown) and supplying it to the engine 10 through an oil passage 36. The engine oil lubricates and cools the components of the engine 10.

[0018] The temperature sensor 31 acquires the temperature of the cooling water for the engine 10. The oil level sensor 32 is provided in an oil pan (not shown) and detects the amount of oil. The oil pressure switch 34 detects the pressure (oil pressure) of the oil supplied to the engine 10. For example, when the oil pressure rises to or exceeds a threshold value, the oil pressure switch 34 outputs a signal.

[0019] The ECU 40 is a control device of the vehicle 1, and includes an arithmetic unit 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 40 performs various controls by executing programs stored in the ROM and the storage device. The ECU 40 acquires the rotation speed of the engine 10 detected by the rotation speed sensor 29. The ECU 40 controls the engine 10, the first MG 14, the second MG 15, the PCU 17, and the battery 18.

[0020] The ECU 40 is connected to the temperature sensor 31 and acquires the amount of water temperature detected by the temperature sensor 31. The ECU 40 is connected to the oil level sensor 32 and acquires the amount of oil detected by the oil level sensor 32. The ECU 40 functions as an acquisition unit, is connected to the oil pressure switch 34, acquires the oil pressure detected by the oil pressure switch 34, and receives the signal output by the oil pressure switch 34.

[0021] The ECU 40 functions as a cranking control unit that controls the cranking of the engine 10 by the first MG 14. The ECU 40 changes the cranking rotation speed, and switches it between R1 (a first value) and R2 (a second value).

[0022] 2 is a flowchart illustrating a process in this embodiment, which is executed when starting the engine 10. The ECU 40 obtains the amount of oil from the oil level sensor 32 and determines whether the current state is after the oil has been changed (step S10). If the determination is negative (No), the process in FIG. 2 ends. For example, if the amount of oil increase is equal to or greater than a predetermined amount, the oil has been changed. If the determination is positive (Yes) in step S10, step S12 is executed.

[0023] The ECU 40 sets the cranking speed to R1 (step S12). The ECU 40 executes cranking (step S14). The ECU 40 obtains the oil pressure from the oil pressure switch 34, and determines whether the oil pressure P is equal to or higher than the threshold value Pth (step S16). If the determination is negative, step S16 is repeated. Cranking at the rotation speed R1 is continued. If the determination is positive, the ECU 40 sets the cranking speed to R2, which is higher than R1 (step S18). This ends the processing in FIG. 2.

[0024] Fig. 3 is a diagram illustrating a time chart. The horizontal axis represents time. From the top of Fig. 3, the oil change flag, cranking speed, cranking on / off, engine 10 speed (engine speed), oil pressure, and on / off of the oil pressure switch 34 are shown.

[0025] In Fig. 3, before time t1, cranking is not performed and the engine speed is zero. The oil pressure P is lower than the threshold value Pth. The oil is changed and the oil level sensor 32 detects an increase in the amount of oil. At time t1, the ECU 40 switches the oil change flag from OFF to ON (step S10 in Fig. 2). The ECU 40 sets the cranking speed to R1, which is lower than R2 (step S12).

[0026] Cranking is started at time t2 (step S14). The engine speed increases. The oil pump 30 operates to supply oil to the engine 10. The oil pressure P increases. At time t3, the oil pressure P becomes equal to or greater than the threshold value Pth (step S16). The oil pressure switch 34 switches from off to on. The ECU 40 turns off the oil change flag and switches the cranking speed from R1 to R2 (step S18). Cranking is performed at the speed R2, and the engine speed increases further. The engine 10 starts and cranking ends (time t4).

[0027] According to this embodiment, the engine 10 is cranked by the first MG 14. The ECU 40 controls the cranking speed. Immediately after an oil change, the oil passage 36 contains air, and may be filled with air, for example. Since oil is not easily supplied to the engine 10, lubrication may deteriorate. When the oil pressure P is less than the threshold value Pth, the ECU 40 sets the cranking speed to R1. Since the cranking speed is small, damage to the engine 10, such as wear and seizure, is suppressed even when there is little oil. When the oil pressure P becomes high enough to be equal to or higher than the threshold value Pth, air is removed from the oil passage 36, and the oil passage 36 is filled with oil. By driving the oil pump 30, a sufficient amount of oil is supplied to the engine 10, and lubrication performance is improved. The ECU 40 sets the cranking speed to R2, which is higher than R1. Cranking is performed at a high speed to start the engine 10. That is, damage such as seizure is suppressed, and the engine 10 can also be started.

[0028] When the water temperature is low, the oil temperature is also low, and there is a risk of the lubrication environment deteriorating. The ECU 40 may set the cranking speed R1 to be lower as the water temperature is lower. This can effectively suppress damage.

[0029] Although a preferred embodiment of the present invention has been described in detail above, the present invention is not limited to such a specific embodiment, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0030] 1 vehicle, 10 engine, 14 first motor generator, 15 second motor generator, 17 PCU, 18 battery, 19 torsional damper, 20 power split mechanism, 22 reduction mechanism, 24 differential gear, 25 drive shaft, 26 drive wheel, 27 crankshaft, 29 rotation speed sensor, 30 oil pump, 31 temperature sensor, 32 oil level sensor, 34 oil pressure switch, 36 oil passage, 40 ECU

Claims

[Claim 1] An acquisition unit for acquiring an engine oil pressure; A cranking control unit that cranks the internal combustion engine by an electric motor, When the hydraulic pressure is less than a predetermined value, the cranking control unit sets the cranking rotation speed to a first value, A control device for a hybrid vehicle, wherein when the hydraulic pressure is equal to or higher than a predetermined value, the cranking control unit sets the cranking rotation speed to a second value higher than the first value.

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