Control system for electric vehicles

Abstract

To provide a control system of an electric vehicle that can suppress fuel components from flowing out.SOLUTION: A control system of an electric vehicle is provided with: an internal combustion engine mounted on the electric vehicle; a rotary electric machine that drives the internal combustion engine; a battery for driving that supplies electric power to the rotary electric machine; and a control device that controls the electric vehicle. The control device obtains a dilution state of a lubricant of the internal combustion engine and changes a first determined value at which a charging rate of the battery for driving becomes maximum in accordance with the dilution state.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a control system for an electric vehicle.

Background Art

[0002] Conventionally, a control system for an electric vehicle having an internal combustion engine and a rotary electric machine for driving the internal combustion engine is known (see, for example, Patent Document 1). When the lubricating oil of the internal combustion engine is diluted by fuel in the control system of the electric vehicle of Patent Document 1, the internal combustion engine is operated in a combustion mode to burn the lubricating oil. During this period, the rotary electric machine is driven and charged in the control system of the electric vehicle of Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the drive battery is fully charged, it cannot be charged anymore. When the drive battery cannot be charged, for example, the regenerative brake of the electric vehicle cannot be used. Therefore, in the conventional control system of an electric vehicle, motoring for driving the internal combustion engine by the rotary electric machine is executed, and the regenerative power is consumed. At this time, if the lubricating oil of the internal combustion engine is diluted, the fuel component contained in the lubricating oil flows out into the exhaust gas.

[0005] An object of the present disclosure is to provide a control system for an electric vehicle that can suppress the outflow of fuel components.

Means for Solving the Problems

[0006] The electric vehicle control system according to this disclosure comprises an internal combustion engine mounted on the electric vehicle, a rotating electric machine that drives the internal combustion engine, a drive battery that supplies power to the rotating electric machine, and a control device that controls the electric vehicle. The control device acquires the dilution state of the lubricating oil of the internal combustion engine and changes a first determination value that indicates the charge level of the drive battery is fully charged according to the dilution state.

[0007] The control system of this electric vehicle can change a first determination value according to the dilution state of the lubricating oil. This allows the control system to change the charge ratio of the drive battery when fully charged according to the dilution state. As a result, the control system can prevent the motoring control from being performed when the lubricating oil of the internal combustion engine is diluted. Consequently, the control system can suppress the leakage of fuel components. [Effects of the Invention]

[0008] According to this disclosure, a control system for electric vehicles that can suppress the leakage of fuel components can be provided. [Brief explanation of the drawing]

[0009] [Figure 1] A system diagram of an electric vehicle according to one embodiment of the present disclosure. [Figure 2] A system diagram of an internal combustion engine according to one embodiment of the present disclosure. [Figure 3] A flowchart illustrating a control procedure performed by a control device according to one embodiment of the present disclosure. [Figure 4] A flowchart illustrating a control procedure performed by a control device according to one embodiment of the present disclosure. [Figure 5] A timing chart showing an example of a control procedure performed by a control device according to one embodiment of the present disclosure. [Modes for carrying out the invention]

[0010] Hereinafter, one embodiment of this disclosure will be described with reference to the drawings.

[0011] As shown in Figure 1, the control system 3 of the electric vehicle C includes an internal combustion engine 1, a motor (FrM) 2, a generator (GEN: an example of a rotating electric machine) 4, a drive battery (BT) 6, a transaxle 8, a vehicle control device (an example of a control device) 12, an engine control device 14 that controls the internal combustion engine 1, an accelerator pedal 16 operated by the user of the electric vehicle C, an inverter 18 that controls the motor 2 and the generator 4, and a charger (an example of an external charging device) 20 that can be connected to an external power source. In addition, the control system 3 of the electric vehicle C may include, for example, a power supply device 22 that can supply power to external devices such as home appliances, and a charging button (not shown) that the user can use to instruct charging. In this embodiment, the electric vehicle C is a plug-in hybrid vehicle (PHEV) that can store power from an external power source in the drive battery 6 using the charger 20.

[0012] As shown in Figure 2, the internal combustion engine 1 includes a port injection valve 30, a spark plug 32, a catalytic converter 34, an intake cam 36, an exhaust cam 38, a piston 40, and a temperature sensor 42. In this embodiment, the internal combustion engine 1 is a gasoline engine that ignites the fuel-air mixture with the spark plug 32. The catalytic converter 34 is a three-way catalytic converter that purifies the exhaust gas of the gasoline engine. The temperature sensor 42 is a sensor that detects the catalytic converter temperature T of the catalytic converter 34.

[0013] The internal combustion engine 1 is injected with lubricating oil O to assist in the lubrication of sliding members such as the piston 40, intake cam 36, and exhaust cam 38. The lubricating oil O may be diluted by fuel components adhering to the cylinder 50, etc.

[0014] As shown in Figure 1, the generator 4 is connected to the internal combustion engine 1 and is capable of driving the internal combustion engine 1. While the vehicle is powered by the drive battery 6, the generator 4 performs motoring, driving the internal combustion engine 1. On the other hand, the generator 4 generates electricity when driven by the internal combustion engine 1 while the engine is running. Therefore, the generator 4 is a motor-generator capable of both powering and generating electricity.

[0015] The drive battery 6 outputs power to the motor 2 and generator 4 via the DC-DC converter 24, and also receives power generated by the motor 2 and generator 4. The DC-DC converter 24 has a boost circuit and boosts the voltage Bv of the drive battery 6. Furthermore, the drive battery 6 receives external power via the charger 20. The drive battery 6 in this embodiment is composed of a secondary battery such as a lithium-ion battery and has a battery module (not shown) which is composed of multiple battery cells bundled together.

[0016] The drive battery 6 has a battery monitoring unit (BMU) 6a. The battery monitoring unit 6a calculates the State of Charge (SOC) of the battery module as an example of the charge state of the drive battery 6. In addition, the battery monitoring unit 6a may also detect the State of Health (SOH) of the battery module and the battery temperature Btmp. The battery monitoring unit 6a acquires the voltage Bv, charge level SOC, state of health SOH, and battery temperature Btmp of the drive battery 6 and transmits them to the vehicle control device 12.

[0017] The transaxle 8 has multiple gears and a clutch 8a. The internal combustion engine 1 is connected to the generator 4 and the axle 10 via the transaxle 8. When the clutch 8a is open, power transmission between the internal combustion engine 1 and the axle 10 is interrupted, and when the clutch 8a is engaged, power from the internal combustion engine 1 is transmitted to the wheels C1 via the axle 10. The motor 2 is connected to the axle 10 via the transaxle 8.

[0018] The electric vehicle C of this embodiment has various modes such as an EV mode, a series mode, a parallel mode, and a charging mode. In the case of the EV mode, the electric vehicle C drives the motor 2 with the power from the drive battery 6. In the case of the series mode, the electric vehicle C drives the generator 4 with the internal combustion engine 1 and drives the motor 2 using the power generated by the generator 4. In the case of the parallel mode, the electric vehicle C connects the clutch 8a and drives the axle 10 using the power of the internal combustion engine 1. In the charging mode, the electric vehicle C drives the generator 4 with the internal combustion engine 1 and stores the power generated by the generator 4 in the drive battery 6. The electric vehicle C switches each mode according to the depression state of the accelerator pedal 16 and the operation state of the charging button, controls the motor 2 and the generator 4 via the inverter 18, and causes the engine control device 14 to control the internal combustion engine 1.

[0019] When the state of charge SOC of the drive battery 6 reaches the first determination value SOCt1, the vehicle control device 12 determines that it is fully charged and stops charging by the charger 20 or power generation by the generator 4. Further, when the state of charge SOC is greater than the second determination value SOCt2, the vehicle control device 12 executes full charge control for performing motoring to drive the internal combustion engine 1 with the generator 4. Thereby, the vehicle control device 12 causes the generator 4 to consume the power generated by the regeneration of the motor 2 when the electric vehicle C decelerates. At this time, the vehicle control device 12 executes either the first motoring control for driving the internal combustion engine 1 in a non-combustion state by the generator 4 or the second motoring control for driving the internal combustion engine 1 in a combustion state by the generator 4. The vehicle control device 12 transmits a signal such as the first motoring control to the engine control device 14 and causes the engine control device 14 to control the internal combustion engine 1. The vehicle control device 12 is actually an ECU (Electronic Control Unit) constituted by a microcomputer including an arithmetic unit, a memory, an input / output buffer, etc. The vehicle control device 12 executes various controls of the electric vehicle C based on the map and program stored in the memory.

[0020] In addition, the vehicle control device 12 is electrically connected to a control unit (not shown) of the drive battery 6, and can acquire information such as the state of charge SOC and the battery temperature Btmp of the drive battery 6 from the control unit of the drive battery 6.

[0021] The engine control device 14 is a control device that is electrically connected to various devices provided in the internal combustion engine 1 and controls the internal combustion engine 1. The engine control device 14 is actually an ECU (Electronic Control Unit) constituted by a microcomputer including an arithmetic unit, a memory, an input / output buffer, etc. The engine control device 14 executes various controls of the internal combustion engine 1 based on maps and programs stored in the memory. Note that the control of the internal combustion engine 1 may be executed by the vehicle control device 12 in addition to the engine control device 14.

[0022] Next, the control procedure of the vehicle control device 12 of the present embodiment will be described using the flowchart of FIG. 3.

[0023] In step S1, the vehicle control device 12 acquires the dilution ratio D (an example of the diluted state) of the lubricating oil O. The dilution ratio D is the ratio of the amount of fuel components mixed in with respect to the amount of the lubricating oil O. The vehicle control device 12 estimates the dilution ratio D from the number of engine starts, the oil temperature of the lubricating oil O, the operating time of the internal combustion engine 1, the water temperature of the internal combustion engine 1, etc. When the vehicle control device 12 acquires the dilution ratio D, it proceeds to step S2 for processing.

[0024] In step S2, the vehicle control device 12 determines whether or not the dilution ratio D is greater than a predetermined ratio Dt. The predetermined ratio Dt is a value determined based on whether or not the fuel components contained in the lubricating oil О flow out from the exhaust in the full charge control. That is, the predetermined ratio Dt is a threshold value for determining whether or not there is a possibility that the fuel components will pass through the catalyst 34 and flow out to the outside of the electric vehicle C when the full charge control is executed when the dilution ratio D is greater than the predetermined ratio Dt. When the vehicle control device 12 determines that the dilution ratio D is greater than the predetermined ratio Dt (step S2 YES), it proceeds to step S3 for processing.

[0025] In step S3, the vehicle control device 12 lowers the first determination value SOCt1, which is the charge rate SOC at which full charge is determined. The vehicle control device 12 may set the first determination value SOCt1 to a lower value as the dilution ratio D becomes greater than a predetermined ratio Dt. The lower the first determination value SOCt1 at which full charge is determined, the larger the difference between the second determination value SOCt2 at which full charge control is executed and the first determination value SOCt1. As a result, the vehicle control device 12 can reduce the opportunities to execute full charge control. As a result, the vehicle control device 12 can suppress the outflow of fuel components. When the vehicle control device 12 lowers the first determination value SOCt1, it proceeds to step S4.

[0026] In step S4, the vehicle control device 12 determines whether the catalyst temperature T is below the first temperature T1. In this embodiment, the vehicle control device 12 executes the process in step S4 when the vehicle is connected to an external power source by the charger 20 and the drive battery 6 is being charged. The first temperature T1 is a temperature determined by whether the catalyst 34 is at a temperature at which it can purify fuel components. In this embodiment, the first temperature T1 is the temperature at which the three-way catalyst is in a semi-activated state (for example, around 300°C). When charging by an external power source, the catalyst temperature T tends to decrease if the ambient temperature is low. If the vehicle control device 12 determines that the catalyst temperature T is below the first temperature T1 (step S4 YES), it proceeds to the process in step S5.

[0027] In step S5, the vehicle control device 12 further lowers the first determination value SOCt1. When the catalyst temperature T is lower than the first temperature D1, the likelihood of fuel components leaking out due to full charge control increases. Therefore, by further lowering the first determination value SOCt1, the vehicle control device 12 can further reduce the opportunities to perform full charge control. After further lowering the first determination value SOCt1, the vehicle control device 12 proceeds to step S6.

[0028] In step S6, the vehicle control device 12 determines whether charging of the drive battery 6 by the charger 20 or by the generator 4 has started and whether the charge level SOC has reached the first determination value SOCt1. If the vehicle control device 12 determines that the charge level SOC has reached the first determination value SOCt1 (step S6 YES), it proceeds to step S7.

[0029] In step S7, the vehicle control device 12 stops charging by the charger 20 or the generator 4. Once charging is stopped, the vehicle control device 12 proceeds to step S8.

[0030] In step S8, the vehicle control device 12 determines whether the charge level (SOC) is equal to or greater than the second determination value (SOCt2). The second determination value (SOCt2) is the charge level (SOC) at which full charge control is required. The second determination value (SOCt2) is a charge level (SOC) that is higher than the first determination value (SOCt1). If the vehicle control device 12 determines that the charge level (SOC) is equal to or greater than the second determination value (SOCt2) (step S8 YES), it proceeds to step S9.

[0031] In step S9, the vehicle control device 12 determines whether the electric vehicle C is in a deceleration state due to regenerative braking by the motor 2. If the vehicle control device 12 determines that it is in a deceleration state (step S8 YES), it proceeds to step S10. In step S10, the vehicle control device 12 performs full charge control.

[0032] If the vehicle control device 12 determines in step S2 that the dilution ratio D is below a predetermined ratio (step S2 NO), the vehicle control device 12 proceeds to step S6. That is, the vehicle control device 12 proceeds to step S6 without lowering the first determination value SOCt1. If the vehicle control device 12 determines in step S4 that the catalyst temperature T is greater than the first temperature T1 (step S4 NO), the vehicle control device 12 proceeds to step S6.

[0033] If the vehicle control device 12 determines in step S6 that the charge level (SOC) is not equal to the first determination value (SOCt1) (step S6 NO), the vehicle control device 12 proceeds to step S1. That is, the vehicle control device 12 repeats the process from step S1 to step S6 until the charge level (SOC) becomes equal to the first determination value (SOCt1). In this way, the vehicle control device 12 changes the first determination value (SOCt1) based on the dilution ratio (D) and the catalyst temperature (T).

[0034] If the vehicle control device 12 determines in step S8 that the charge level SOC is not equal to the second determination value SOCt2 (step S8 NO), the vehicle control device 12 proceeds to step S1. In other words, the vehicle control device 12 repeats the process from step S1 to step S8 until the charge level SOC becomes equal to the second determination value SOCt2 and full charge control is executed.

[0035] If the vehicle control device 12 determines in step S9 that the vehicle is not in a deceleration state (step S9 NO), the vehicle control device 12 proceeds to step S1.

[0036] Next, the control procedure for full charge control performed by the vehicle control device 12 will be explained using the flowchart in Figure 4.

[0037] In step S20, the vehicle control device 12 obtains the dilution ratio D in full charge control and determines whether the dilution ratio D is equal to or greater than a predetermined ratio Dt. If the dilution ratio D is less than or equal to the predetermined ratio Dt (step S20 YES), the vehicle control device 12 proceeds to step S21.

[0038] In step S21, the vehicle control device 12 performs non-combustion motoring. The combustion components supplied to the catalyst 34 by the non-combustion motoring are purified by the catalyst 34. After performing non-combustion motoring, the vehicle control device 12 proceeds to step S22.

[0039] In step S22, the vehicle control device 12 determines whether deceleration has ended or not. If the vehicle control device 12 determines that deceleration has ended (step S22 YES), it proceeds to step S23 and stops the full charge control. On the other hand, if the vehicle control device 12 determines that deceleration has not ended (step S22 NO), it proceeds to step S9 and continues the full charge control.

[0040] If the vehicle control device 12 determines in step S20 that the dilution ratio D is less than a predetermined ratio Dt (step S20 YES), the vehicle control device 12 proceeds to step S13.

[0041] In step S24, the vehicle control device 12 determines whether the catalyst temperature T is equal to or greater than the second temperature T2. The second temperature T2 is the temperature at which the catalyst 34 is activated to the extent that fuel components can be purified even under full charge control. In this embodiment, the second temperature T2 is the temperature at which the three-way catalyst is fully activated (for example, around 600 to 700°C). If the catalyst temperature T is equal to or greater than the second temperature T2 (step S24 YES), the vehicle control device 12 proceeds to step S25 and performs non-combustion motoring.

[0042] If the catalyst temperature T is less than the second temperature T2 (step S24 NO), the vehicle control device 12 proceeds to step S25. In step S25, the vehicle control device 12 performs combustion motoring. That is, the vehicle control device 12 performs either non-combustion motoring or combustion motoring depending on the dilution ratio D. In combustion motoring, the fuel components are burned by the internal combustion engine 1. This suppresses the outflow of fuel components. After performing the process in step S25, the vehicle control device 12 proceeds to step S22.

[0043] Next, an example using the above control procedure will be explained using the timing chart in Figure 5. In this embodiment, an example will be described in which charging is performed using an external power supply by the charger 20.

[0044] As shown in the operating state of the internal combustion engine 1 from time t1 to t2, the dilution ratio D changes when the internal combustion engine 1 is operating. The dilution ratio D increases when the internal combustion engine 1 repeatedly accelerates and decelerates in a cold state. As shown in time t2, when the dilution ratio D exceeds a predetermined ratio Dt (state S2 YES in Figure 3), the vehicle control device 12 lowers the first determination value SOCt1.

[0045] As shown from time t2 to time t3, when the drive battery 6 is charged from an external power source in this state, the charge level (SOC) increases. As shown at time t3, when the charge level (SOC) reaches the first determination value (SOCt1), the vehicle control device 12 stops charging (state S6 YES in Figure 3).

[0046] As shown from time t3 to time t4, when the charge level (SOC) reaches the second determination value (SOCt2) and the electric vehicle C decelerates due to regeneration by motor 2, the vehicle control device 12 starts full charge control by turning on full charge control (state S8 and S9 YES in Figure 3). As shown by the dilution ratio D at time t4, the dilution ratio D is greater than the predetermined ratio Dt at this time (state S20 YES in Figure 4). Also, as shown by the catalyst temperature T at time t4, the catalyst temperature T is less than the second temperature T2 (state S24 NO in Figure 4). For this reason, the vehicle control device 12 performs combustion motoring.

[0047] As shown in the catalyst temperature T from time t4 to time t5, the catalyst temperature T increases due to combustion motoring. As shown in time t5, when the catalyst temperature T reaches or exceeds the second temperature T2 (state S24 YES in Figure 4), the vehicle control device 12 switches from combustion motoring to non-combustion motoring. As shown in time t6, when the deceleration of the electric vehicle C is completed, the vehicle control device 12 terminates the full charge control.

[0048] As shown from time t7 to time t8, when the drive battery 6 is charged again, the charge rate SOC increases. However, at this time the dilution ratio D is less than or equal to a predetermined ratio Dt (state NO in step S2 of Figure 3). In this case, the vehicle control device 12 of this embodiment uses the second determination value SOCt2 as the first determination value SOCt1 for full charge. As shown at time t8, when the second determination value SOCt2 is reached, the vehicle control device 12 terminates charging. As shown from time t9 to time t10, when the vehicle control device 12 starts full charge control in a situation where the dilution ratio D is less than or equal to a predetermined ratio Dt, the vehicle control device 12 performs non-combustion motoring.

[0049] As explained above, this disclosure provides a control system 3 for an electric vehicle C that can suppress the leakage of fuel components.

[0050] <Other Embodiments> Although embodiments of the present disclosure have been described above, the present disclosure is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. In particular, the various modifications described herein can be combined as needed.

[0051] (a) In the above embodiment, the internal combustion engine 1 was described using a gasoline engine as an example, but this disclosure is not limited thereto. The internal combustion engine 1 may be a diesel engine or the like.

[0052] (b) In the above embodiment, an example was described in which the catalyst temperature T is detected by a temperature sensor 42, but the disclosure is not limited thereto. The catalyst temperature T may be estimated from the operating time of the internal combustion engine 1 or the like.

[0053] (c) In the above embodiment, the vehicle control device 12 estimated the dilution ratio D from the number of engine starts, the oil temperature of the lubricating oil O, the operating time of the internal combustion engine 1, the water temperature of the internal combustion engine 1, etc., but the present disclosure is not limited thereto. The vehicle control device 12 may also obtain the amount of lubricating oil O and the amount of fuel mixed in from an oil level sensor (not shown) or the like, and obtain the dilution ratio D. [Explanation of Symbols]

[0054] 1: Internal combustion engine, 3: Control system, 4: Generator, 6: Drive battery 12: Vehicle control device, 20: Charger, 34: Catalytic converter, C: Electric vehicle D: Dilution ratio, D1: First temperature, Dt: Predetermined ratio, O: Lubricating oil SOC: Charge level, SOCt1: First judgment value, SOCt2: Second judgment value T: catalyst temperature, T1: first temperature, T2: second temperature О: Lubricating oil

Claims

1. Internal combustion engines installed in electric vehicles, A catalyst for purifying the exhaust gas of the internal combustion engine, A regenerative motor mounted on the aforementioned electric vehicle, A rotating electric machine that drives the internal combustion engine and is driven by the internal combustion engine to generate electricity, A drive battery that supplies power to the rotating electric machine and receives the power generated by the rotating electric machine, An external charging device for charging the drive battery from an external device of the electric vehicle, A control device for controlling the electric vehicle, Equipped with, The control device acquires the dilution state of the lubricating oil of the internal combustion engine and changes a first determination value that determines the drive battery is fully charged according to the dilution state. The temperature of the catalyst during charging by the external charging device is obtained, and if the temperature of the catalyst is lower than the first temperature, the first determination value is further reduced. The aforementioned full charge refers to a state in which power generation by the rotating electric machine is stopped, and motoring control is performed in which the power generated by the regeneration of the motor is consumed by driving the internal combustion engine with the rotating electric machine. Control system for electric vehicles.

2. The control device obtains the dilution ratio of the lubricating oil of the internal combustion engine, and lowers the first determination value as the dilution ratio increases. The control system for an electric vehicle according to claim 1.

3. The control device, when the charge level of the drive battery is higher than a second determination value, which is higher than the first determination value, executes either a first motoring control that drives the internal combustion engine in a non-combustion state using the rotating electric motor, or a second motoring control that drives the internal combustion engine in a combustion state using the rotating electric motor, according to the dilution ratio. The control system for an electric vehicle according to claim 2.

4. The control device executes the second motoring control when the dilution ratio is equal to or greater than a predetermined ratio. The control system for an electric vehicle according to claim 3.

5. The control device acquires the temperature of the catalyst, and if the temperature is equal to or higher than the second temperature, switches to the first motoring control. The control system for an electric vehicle according to claim 4.

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