JP2024121871A - Electric vehicle control system - Google Patents

Abstract

An object of the present invention is to provide a control system for an electric vehicle capable of suppressing the outflow of fuel components.
[Solution] A control system for an electric vehicle includes an internal combustion engine mounted on the electric vehicle, a rotating electric motor that drives the internal combustion engine, a drive battery that supplies power to the rotating electric motor, and a control device that controls the electric vehicle, wherein the control device obtains the dilution state of the lubricating oil of the internal combustion engine and changes a first judgment value at which the charging rate of the drive battery is fully charged in accordance with the dilution state.
[Selected Figure] Figure 1

Description

This disclosure relates to a control system for an electric vehicle.

Conventionally, there is known a control system for an electric vehicle having an internal combustion engine and a rotating electric machine that drives the internal combustion engine (see, for example, Patent Document 1). In the electric vehicle control system of Patent Document 1, when the lubricating oil of the internal combustion engine is diluted by fuel, the internal combustion engine is operated for combustion to burn the lubricating oil. In the electric vehicle control system of Patent Document 1, the rotating electric machine is driven and charged during this time.

JP 2020-192897 A

However, once the drive battery is fully charged, it cannot be charged. If the drive battery cannot be charged, for example, the regenerative braking of the electric vehicle cannot be used. For this reason, in conventional electric vehicle control systems, motoring is performed to drive the internal combustion engine using a rotating electric machine, and the regenerative electricity is consumed. At this time, if the lubricating oil of the internal combustion engine is diluted, the fuel components contained in the lubricating oil will flow into the exhaust.

The objective of this disclosure is to provide a control system for an electric vehicle that can suppress the leakage of fuel components.

The control system for an electric vehicle according to the present disclosure includes 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, and the control device acquires the dilution state of the lubricating oil of the internal combustion engine and changes a first determination value at which the charge rate of the drive battery is fully charged according to the dilution state.

The control system for this electric vehicle can change the first judgment value depending on the dilution state of the lubricant. This allows the control system for this electric vehicle to change the charging rate of the drive battery when fully charged depending on the dilution state. As a result, the control system for this electric vehicle can suppress the execution of motoring control when the lubricant for the internal combustion engine is in a diluted state. As a result, the control system for this electric vehicle can suppress the outflow of fuel components.

This disclosure provides a control system for an electric vehicle that can suppress the leakage of fuel components.

1 is a system diagram of an electric vehicle according to one embodiment of the present disclosure. 1 is a system diagram of an internal combustion engine according to one embodiment of the present disclosure. 4 is a flowchart showing a control procedure executed by a control device according to an embodiment of the present disclosure. 4 is a flowchart showing a control procedure of full charge control executed by a control device according to an embodiment of the present disclosure. 4 is a timing chart illustrating an example of a control procedure executed by a control device according to an embodiment of the present disclosure.

An embodiment of the present disclosure will be described below with reference to the drawings.

As shown in FIG. 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 a 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 a power supply device 22 that can supply power to external devices such as home appliances, and a charge button (not shown) that the user instructs to charge. 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 by the charger 20.

As shown in FIG. 2, the internal combustion engine 1 has a port injection valve 30, an ignition plug 32, a catalyst 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 air-fuel mixture with the ignition plug 32. The catalyst 34 is a three-way catalyst that purifies the exhaust gas of the gasoline engine. The temperature sensor 42 is a sensor that detects the catalyst temperature T of the catalyst 34.

Lubricating oil O is injected into the internal combustion engine 1 to help lubricate sliding members such as the piston 40, the intake cam 36, and the exhaust cam 38. The lubricating oil O may be diluted by fuel components adhering to the cylinders 50, etc.

As shown in FIG. 1, the generator 4 is connected to the internal combustion engine 1 and is capable of driving the internal combustion engine 1. The generator 4 performs motoring to drive the internal combustion engine 1 while the internal combustion engine 1 is being powered by electric power from the drive battery 6. On the other hand, the generator 4 is driven by the internal combustion engine 1 to generate electricity while the internal combustion engine 1 is in operation. Therefore, the generator 4 is a motor-generator capable of powering and generating electricity.

The driving battery 6 outputs power to the motor 2 and generator 4 via a DC-DC converter 24, and also receives the 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 driving battery 6. Furthermore, external power is input to the driving battery 6 via a charger 20. The driving battery 6 in this embodiment is composed of a secondary battery such as a lithium ion battery, and has a battery module (not shown) that is made up of multiple battery cells.

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. The battery monitoring unit 6a may also detect the state of health (SOH) and battery temperature Btmp of the battery module. The battery monitoring unit 6a acquires the voltage Bv, state of charge SOC, state of health SOH, and battery temperature Btmp of the drive battery 6 and transmits them to the vehicle control device 12.

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 in the disengaged state, the transaxle 8 cuts off the power transmission between the internal combustion engine 1 and the axle 10, and when the clutch 8a is in the engaged state, the power of 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.

The electric vehicle C of this embodiment has various modes such as EV mode, series mode, parallel mode, and charging mode. In the EV mode, the electric vehicle C drives the motor 2 with power from the drive battery 6. In the series mode, the electric vehicle C drives the generator 4 with the internal combustion engine 1 and drives the motor 2 with the power generated by the generator 4. In the parallel mode, the electric vehicle C connects the clutch 8a and drives the axle 10 with 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. In the electric vehicle C, the vehicle control device 12 switches between each mode depending on the depression state of the accelerator pedal 16 and the operation state of the charge button, controls the motor 2 and the generator 4 via the inverter 18, and has the engine control device 14 control the internal combustion engine 1.

When the charging rate SOC of the drive battery 6 reaches a first determination value SOCt1, the vehicle control device 12 determines that the battery is fully charged, and stops charging by the charger 20 or power generation by the generator 4. When the charging rate SOC is greater than a second determination value SOCt2, the vehicle control device 12 executes full charge control to perform motoring to drive the internal combustion engine 1 by the generator 4. As a result, 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 a first motoring control to drive the internal combustion engine 1 in a non-combustion state by the generator 4, or a second motoring control to drive 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) that is composed of a microcomputer including a calculation device, memory, an input/output buffer, etc. The vehicle control device 12 executes various controls of the electric vehicle C based on maps and programs stored in the memory.

The vehicle control device 12 is also electrically connected to a control unit (not shown) of the drive battery 6, and can obtain information such as the charging rate SOC and battery temperature Btmp of the drive battery 6 from the control unit of the drive battery 6.

The engine control device 14 is electrically connected to various devices of the internal combustion engine 1 and is a control device that controls the internal combustion engine 1. The engine control device 14 is actually an ECU (Electronic Control Unit) composed of a microcomputer including a calculation device, 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.

Next, the control procedure of the vehicle control device 12 of this embodiment will be explained using the flowchart in Figure 3.

In step S1, the vehicle control device 12 acquires a dilution ratio (an example of a dilution state) D of the lubricating oil O. The dilution ratio D is the ratio of the amount of fuel components mixed in 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. After acquiring the dilution ratio D, the vehicle control device 12 proceeds to step S2.

In step S2, the vehicle control device 12 determines whether 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 O flow out of the exhaust gas during full charge control. In other words, the predetermined ratio Dt is a threshold value that determines whether or not the fuel components may pass through the catalyst 34 and flow out to the outside of the electric vehicle C when full charge control is executed if 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.

In step S3, the vehicle control device 12 lowers the first judgment value SOCt1, which is the charging rate SOC at which the battery is determined to be fully charged. The vehicle control device 12 may set the first judgment value SOCt1 to a lower value as the dilution ratio D becomes larger than the predetermined ratio Dt. The lower the first judgment value SOCt1 at which the battery is determined to be fully charged, the larger the difference between the second judgment value SOCt2 at which the full charge control is executed and the first judgment value SOCt1. This allows the vehicle control device 12 to reduce the opportunities for executing the full charge control. As a result, the vehicle control device 12 can suppress the outflow of fuel components. After lowering the first judgment value SOCt1, the vehicle control device 12 proceeds to step S4.

In step S4, the vehicle control device 12 determines whether the catalyst temperature T is equal to or lower than the first temperature T1. In this embodiment, the vehicle control device 12 executes the process of step S4 when the vehicle control device 12 is connected to an external power source via the charger 20 and the drive battery 6 is being charged. The first temperature T1 is a temperature determined based on whether the catalyst 34 is at a temperature at which it can purify fuel components. In this embodiment, the first temperature T1 is a temperature (e.g., about 300°C) at which the three-way catalyst is in a semi-activated state. During charging from an external power source, if the outside air temperature is low, the catalyst temperature T is likely to drop. If the vehicle control device 12 determines that the catalyst temperature T is equal to or lower than the first temperature T1 (step S4 YES), the process proceeds to step S5.

In step S5, the vehicle control device 12 further lowers the first determination value SOCt1. If the catalyst temperature T is lower than the first temperature D1, there is a higher possibility that fuel components will leak out due to full charge control. For this reason, the vehicle control device 12 can further reduce the opportunities for executing full charge control by further lowering the first determination value SOCt1. After further lowering the first determination value SOCt1, the vehicle control device 12 proceeds to step S6.

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

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

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

In step S9, the vehicle control device 12 determines whether the electric vehicle C is in a deceleration state due to regeneration of the motor 2. If the vehicle control device 12 determines that the electric vehicle C is in a deceleration state (YES in step S8), the process proceeds to step S10. In step S10, the vehicle control device 12 executes full charge control.

If the vehicle control device 12 determines in step S2 that the dilution ratio D is equal to or less than the 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.

If the vehicle control device 12 determines in step S6 that the charging rate 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 processes from step S1 to step S6 until the charging rate SOC becomes the first determination value SOCt1. As a result, the vehicle control device 12 changes the first determination value SOCt1 based on the dilution ratio D and the catalyst temperature T.

If the vehicle control device 12 determines in step S8 that the charging rate SOC has not reached the second determination value SOCt2 (step S8 NO), the vehicle control device 12 proceeds to step S1. That is, the vehicle control device 12 repeats the processes from step S1 to step S8 until the charging rate SOC reaches the second determination value SOCt2 and full charge control is executed.

If the vehicle control device 12 determines in step S9 that the vehicle is not decelerating (step S9 NO), the vehicle control device 12 proceeds to step S1.

Next, the control procedure for full charge control executed by the vehicle control device 12 will be explained using the flowchart in FIG. 4.

In step S20, the vehicle control device 12 acquires the dilution ratio D during 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 equal to or less than the predetermined ratio Dt (YES in step S20), the vehicle control device 12 proceeds to step S21.

In step S21, the vehicle control device 12 executes non-combustion motoring. The combustion components supplied to the catalyst 34 by non-combustion motoring are purified by the catalyst 34. After executing non-combustion motoring, the vehicle control device 12 advances the process to step S22.

In step S22, the vehicle control device 12 determines whether deceleration has ended. If the vehicle control device 12 determines that deceleration has ended (step S22: YES), the process proceeds to step S23, where the full charge control is stopped. On the other hand, if the vehicle control device 12 determines that deceleration has not ended (step S22: NO), the process proceeds to step S9, where the full charge control is continued.

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

In step S24, the vehicle control device 12 determines whether the catalyst temperature T is equal to or higher than the second temperature T2. The second temperature T2 is the temperature at which the catalyst 34 is activated to such an extent that it can purify fuel components even under full charge control. In this embodiment, the second temperature T2 is the temperature at which the three-way catalyst is fully activated (e.g., approximately 600 to 700°C). If the catalyst temperature T is equal to or higher than the second temperature T2 (YES in step S24), the vehicle control device 12 proceeds to step S25 and performs non-combustion motoring.

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 executes combustion motoring. That is, the vehicle control device 12 executes either non-combustion motoring or combustion motoring depending on the dilution ratio D. In combustion motoring, the fuel components are combusted by the internal combustion engine 1. This suppresses the outflow of the fuel components. After executing the process of step S25, the vehicle control device 12 proceeds to step S22.

Next, an example of the above control procedure will be described with reference to the timing chart in FIG. 5. In this embodiment, an example in which charging is performed by the charger 20 using an external power source will be described.

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 is repeatedly accelerated and decelerated in a cold state. As shown at time t2, when the dilution ratio D exceeds the predetermined ratio Dt (YES in step S2 of FIG. 3), the vehicle control device 12 lowers the first judgment value SOCt1.

As shown from time t2 to time t3, when the drive battery 6 is charged from an external power source in this state, the charging rate SOC increases. When the charging rate SOC reaches the first determination value SOCt1 as shown at time t3, the vehicle control device 12 stops charging (YES in step S6 in FIG. 3).

As shown from time t3 to time t4, when the charging rate SOC becomes the second judgment value SOCt2 and the electric vehicle C decelerates due to regeneration by the motor 2, the vehicle control device 12 starts full charge control by turning on the full charge control (steps S8 and S9 YES in FIG. 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 (step S20 YES in FIG. 4). Also, as shown by the catalyst temperature T at time t4, the catalyst temperature T is less than the second temperature T2 (step S24 NO in FIG. 4). Therefore, the vehicle control device 12 executes combustion motoring.

As shown by the catalyst temperature T from time t4 to time t5, the catalyst temperature T rises due to combustion motoring. As shown by time t5, when the catalyst temperature T becomes equal to or higher than the second temperature T2 (YES in step S24 in FIG. 4), the vehicle control device 12 switches from combustion motoring to non-combustion motoring. As shown by time t6, when the deceleration of the electric vehicle C ends, the vehicle control device 12 ends the full charge control.

As shown from time t7 to time t8, when the drive battery 6 is charged again, the charging rate SOC rises. However, at this time, the dilution ratio D is equal to or less than the predetermined ratio Dt (step S2 NO in FIG. 3). In this case, the vehicle control device 12 of this embodiment uses the second judgment value SOCt2 as the first judgment value SOCt1 at which full charge is reached. As shown at time t8, the vehicle control device 12 ends charging when the second judgment value SOCt2 is reached. 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 equal to or less than the predetermined ratio Dt, the vehicle control device 12 executes non-combustion motoring.

As described above, the present disclosure provides a control system 3 for an electric vehicle C that can suppress the outflow of fuel components.

<Other embodiments>
Although the embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention. In particular, the multiple modifications described in this specification can be arbitrarily combined as necessary.

(a) In the above embodiment, the internal combustion engine 1 has been described as a gasoline engine, but the present disclosure is not limited to this. The internal combustion engine 1 may be a diesel engine, etc.

(b) In the above embodiment, an example was described in which the catalyst temperature T was detected by the temperature sensor 42, but the present disclosure is not limited to this. The catalyst temperature T may be estimated from the operating time of the internal combustion engine 1, etc.

(c) In the above embodiment, 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., but the present disclosure is not limited to this. The vehicle control device 12 may obtain the amount of lubricating oil O and the amount of mixed fuel from an oil level sensor (not shown) or the like, and obtain the dilution ratio D.

1: internal combustion engine, 3: control system, 4: generator, 6: driving battery, 12: vehicle control device, 20: charger, 34: catalyst, C: electric vehicle, D: dilution ratio, D1: first temperature, Dt: predetermined ratio, O: lubricant, SOC: charging rate, SOCt1: first judgment value, SOCt2: second judgment value, T: catalyst temperature, T1: first temperature, T2: second temperature, O: lubricant

Claims (6)

An internal combustion engine mounted on an electric vehicle;
a rotating electric machine that drives the internal combustion engine;
a driving battery for supplying power to the rotating electric machine;
A control device for controlling the electric vehicle;
Equipped with
the control device acquires a dilution state of the lubricating oil of the internal combustion engine, and changes a first determination value used to determine that the driving battery is fully charged in accordance with the dilution state.
Electric vehicle control system. The control device acquires a dilution ratio of the lubricating oil of the internal combustion engine, and reduces the first determination value as the dilution ratio becomes higher.
The control system for an electric vehicle according to claim 1 . A catalyst for purifying exhaust gas from the internal combustion engine;
an external charging device that charges the drive battery from a device external to the electric vehicle;
Further equipped with
the control device acquires a temperature of the catalyst during charging by the external charging device, and when the temperature of the catalyst is lower than a first temperature, further reduces the first determination value.
The control system for an electric vehicle according to claim 1 . when the charging rate of the driving battery is equal to or higher than a second determination value higher than the first determination value, the control device executes, in accordance with the dilution ratio, either a first motoring control in which the internal combustion engine is driven in a non-combustion state by the rotating electric machine, or a second motoring control in which the internal combustion engine is driven in a combustion state by the rotating electric machine.
The control system for an electric vehicle according to claim 1 . 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 4. The internal combustion engine further includes a catalyst for purifying exhaust gas from the internal combustion engine.
The control device acquires a temperature of the catalyst, and when the temperature is equal to or higher than a second temperature, switches to the first motoring control.
The control system for an electric vehicle according to claim 5 .