Electric vehicles
The electric vehicle's control unit addresses inefficiencies by managing engine speed during scavenging operations, reducing power consumption and ensuring efficient engine restarts by controlling engine speed between set points, thus enhancing energy efficiency and starting performance.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2024-11-15
- Publication Date
- 2026-05-27
Smart Images
Figure 2026087130000001_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to electric vehicles.
Background Art
[0002] The electric vehicle of Patent Document 1 includes an internal combustion engine, a motor, and a control unit. The internal combustion engine can stop self-driving. The motor can rotate the internal combustion engine whose self-driving has stopped. The control unit controls the internal combustion engine and the motor. After the self-driving of the internal combustion engine is stopped, the control unit performs a scavenging operation to rotate the internal combustion engine with the motor.
[0003] If the engine rotation stops immediately after the self-driving of the internal combustion engine stops during cold conditions, the moisture remaining in the combustion chamber of the internal combustion engine may adhere to the spark plug, which may deteriorate the starting performance in the next engine start. However, by performing the scavenging operation after the self-driving of the internal combustion engine is stopped as described above, the moisture remaining in the combustion chamber of the internal combustion engine is discharged, so the deterioration of the starting performance in the next engine start is suppressed.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0005] By the way, after the self-driving of the internal combustion engine is stopped and before the scavenging operation is started, the engine rotation speed is controlled by the motor so as to change from the value at the time of self-driving stop to the target value at the time of scavenging operation. Then, the scavenging operation is started based on the fact that the engine rotation speed after the self-driving stop of the internal combustion engine has decreased to the target value.
[0006] However, when the engine speed is controlled by the motor to the target value mentioned above during scavenging operation after the internal combustion engine has stopped operating autonomously, the engine speed does not necessarily reach the target value solely through a decrease in engine speed.
[0007] For example, depending on the motor's operating status before the internal combustion engine's autonomous operation is stopped, the motor may control the engine's rotational speed to increase above the value at the time of the autonomous operation stop after the autonomous operation is stopped. In this case, the motor's power consumption will increase as a result of the motor controlling the engine's rotational speed to increase as described above, until the engine's rotational speed is controlled to the target value during scavenging operation after the autonomous operation is stopped. Consequently, the electric vehicle's energy efficiency will worsen. [Means for solving the problem]
[0008] The following describes the means and effects of solving the above problems. An electric vehicle that solves the above problems comprises an internal combustion engine capable of stopping autonomous operation, a motor capable of rotating the internal combustion engine after autonomous operation has stopped, and a control unit that controls the internal combustion engine and the motor. After the autonomous operation of the internal combustion engine is stopped, the control unit performs a scavenging operation in which the internal combustion engine is rotated by the motor. When the conditions for performing the scavenging operation are met, the control unit acquires the engine rotation speed at that time as the first rotation speed and sets the second rotation speed as the target value for the engine rotation speed during the scavenging operation. After the autonomous operation of the internal combustion engine is stopped based on the conditions for performing the scavenging operation being met, the control unit controls the motor to reduce the engine rotation speed of the internal combustion engine, which is rotated by the motor, to a value between the first and second rotation speeds, so as to the second rotation speed. Based on the fact that the engine rotation speed has decreased to the second rotation speed through the control of the motor, the control unit starts the scavenging operation.
[0009] According to the above configuration, after the autonomous operation of the internal combustion engine is stopped based on the fulfillment of the conditions for performing scavenging, the motor is controlled to reduce the engine speed to the second rotational speed while maintaining a value between the first and second rotational speeds. Then, based on the reduction in engine speed to the second rotational speed, scavenging is started. As a result, the motor will not be controlled to increase the engine speed above the value at the time autonomous operation was stopped, i.e., the first rotational speed, after autonomous operation has stopped, thus suppressing the increased power consumption of the motor in such situations. Consequently, the deterioration of the electric vehicle's energy efficiency due to increased motor power consumption can be suppressed. [Brief explanation of the drawing]
[0010] [Figure 1] This is a schematic diagram showing the overall configuration of a hybrid vehicle. [Figure 2] Figure 1 shows the HV driving range and EV driving range of a hybrid vehicle. [Figure 3] This flowchart shows the procedure for performing scavenging on the internal combustion engine installed in the hybrid vehicle shown in Figure 1. [Figure 4] This is a time chart showing the change in engine rotational speed over time after the conditions for scavenging operation have been met. [Figure 5] This is a time chart showing the change in engine rotational speed over time after the conditions for scavenging operation have been met. [Figure 6] This is a time chart showing the change in engine rotational speed over time after the conditions for scavenging operation have been met. [Modes for carrying out the invention]
[0011] An embodiment of an electric vehicle will be described below with reference to Figures 1 to 6. As shown in Figure 1, the hybrid vehicle 500, which is an electric vehicle, is equipped with an internal combustion engine 10 that uses hydrogen as fuel, and electric motors, a first motor generator 310 and a second motor generator 320. Furthermore, the hybrid vehicle 500 is equipped with a control device 100 that functions as a control unit for controlling the internal combustion engine 10, the first motor generator 310 and the second motor generator 320.
[0012] The crankshaft 18 of the internal combustion engine 10 is mechanically connected to the carrier C of the planetary gear mechanism 350, which constitutes the power split device. The sun gear S of the planetary gear mechanism 350 is mechanically connected to the rotating shaft 310a of the first motor generator 310. The ring gear R of the planetary gear mechanism 350 is mechanically connected to the rotating shaft 320a of the second motor generator 320 and the drive wheel 360.
[0013] The first motor generator 310 functions as a generator that generates electricity using engine output, and also functions as a starting starter that cranks the crankshaft 18 when starting the internal combustion engine 10. This first motor generator 310 is an electric motor that motorizes the internal combustion engine 10 by applying torque to the crankshaft 18.
[0014] The second motor generator 320 functions as an electric motor that generates driving force for the drive wheels 360, and also functions as a generator that generates electricity through regeneration when the hybrid vehicle 500 is decelerating.
[0015] The first motor generator 310 and the second motor generator 320 exchange power with the battery 250 via the PCU (Power Control Unit) 200. The battery 250 is charged using the output of the internal combustion engine 10 and also supplies power to the first motor generator 310 and the second motor generator 320.
[0016] The PCU200 includes a converter that boosts the DC voltage input from the battery 250 and outputs it, and an inverter that converts the DC voltage boosted by the converter into AC voltage and outputs it to the first motor generator 310 and the second motor generator 320. The PCU200 is also connected to an external power supply terminal 300 that supplies power from the battery 250 to equipment outside the vehicle. Examples of external power supply include supplying power to power supply equipment installed in homes or shops.
[0017] <Details of control device 100> The control device 100 controls the output and exhaust characteristics of the internal combustion engine 10 by controlling the intake air volume, fuel injection volume, and ignition timing. The control device 100 also operates the inverter via the PCU 200 to control the torque of the first motor generator 310. The control device 100 also operates the inverter via the PCU 200 to control the torque of the second motor generator 320. The control device 100 includes a processing circuit 110. The processing circuit 110 includes a CPU that performs various processes according to a program and a ROM in which various programs are stored.
[0018] The control device 100 refers to the detection values of various sensors. For example, the control device 100 refers to the detection value of the air flow meter 51, which detects the intake air volume GA of the internal combustion engine 10. The control device 100 refers to the detection signal Scr of the crank angle sensor 52, which detects the rotation angle of the crankshaft 18. The control device 100 refers to the detection value of the water temperature sensor 53, which detects the coolant temperature THW of the internal combustion engine 10. The control device 100 refers to the detection value of the intake air temperature sensor 54, which detects the intake air temperature THA of the internal combustion engine 10. The control device 100 refers to the detection signal of the accelerator position sensor 55, which detects the accelerator pedal operation amount ACCP, which is the amount of accelerator pedal operation performed by the driver of the hybrid vehicle 500. The control device 100 refers to the detection signal of the speed sensor 56, which detects the vehicle speed SP of the hybrid vehicle 500. The control device 100 refers to the charge level (SOC) of the battery 250 calculated by the PCU 200.
[0019] The control device 100 calculates the engine speed NE based on the detection signal Scr of the crank angle sensor 52. Further, the control device 100 calculates the engine load factor KL based on the engine speed NE and the intake air amount GA. The engine load factor KL represents the ratio of the current cylinder intake air amount to the cylinder intake air amount when the internal combustion engine 10 is in steady operation at full load at the current engine speed NE. Note that the cylinder intake air amount is the amount of air flowing into each cylinder during the intake stroke.
[0020] The control device 100 calculates the required drive torque Tr required for the running of the hybrid vehicle 500 based on the accelerator operation amount ACCP and the vehicle speed SP. Then, the control device 100 controls the torque of the internal combustion engine 10 and the torques of the first motor generator 310 and the second motor generator 320 so as to satisfy the required drive torque Tr.
[0021] As shown in FIG. 2, in the operation region where the operating point indicated by the required drive torque Tr and the vehicle speed SP is above the boundary line indicated by the solid line L1, HV running is performed in which the vehicle runs using the torque of the internal combustion engine 10, the torque of the first motor generator 310, and the torque of the second motor generator 320. On the other hand, in the operation region where the operating point indicated by the required drive torque Tr and the vehicle speed SP is below the boundary line indicated by the solid line L1, running by only the motor is performed. That is, EV running is performed in which the vehicle runs using only the torque of the second motor generator 320. During this EV running, the combustion in the internal combustion engine 10 is stopped, so that the self-sustained operation of the internal combustion engine 10 is stopped.
[0022] <Scavenging operation> If the engine rotation is stopped immediately after the self-sustained operation of the internal combustion engine 10 is stopped during cold operation, the moisture remaining in the combustion chamber of the internal combustion engine 10 may adhere to the spark plug, which may deteriorate the starting performance in the next engine start. In particular, in the internal combustion engine 10 using hydrogen as fuel, since moisture derived from the fuel is likely to occur in the combustion chamber compared to an engine using gasoline or the like as fuel, the deterioration of the starting performance described above becomes remarkable.
[0023] To address these issues, the control device 100 stops the autonomous operation of the internal combustion engine 10 and then performs a scavenging operation to remove moisture from the combustion chamber. This scavenging operation is a so-called motoring operation in which the internal combustion engine 10 is rotated with fuel injection stopped. The motoring of the internal combustion engine 10 is performed by driving the first motor generator 310, which is powered by the battery 250.
[0024] Figure 3 is a flowchart showing the procedure for performing the scavenging operation described above. The processing circuit 110 of the control device 100 determines whether the conditions for performing the scavenging operation are met as step 101 (S101) of the series of processes shown in Figure 3. Whether the conditions for performing the scavenging operation are met is determined based on whether all of the following conditions (A1) to (A3) are met.
[0025] (A1) The autonomous operation of the internal combustion engine 10 can be stopped, for example, when the accelerator pedal operation amount ACCP is "0" and the vehicle speed SP is less than or equal to a predetermined value. For example, "0" can be used as the predetermined value. Alternatively, a value greater than "0" may be used as the predetermined value.
[0026] (A2) The air conditioning system of the hybrid vehicle 500 is not operating, in other words, there is no drive requirement for the internal combustion engine 10 to operate the air conditioning system. (A3) There is no request to prohibit scavenging. A request to prohibit scavenging is made, for example, when there is a possibility that the hybrid vehicle 500 will start moving. The determination that there is a possibility that the hybrid vehicle 500 will start moving may be made, for example, based on the current position of the hybrid vehicle 500 on the map and the display status of the traffic signals ahead determined using a camera, etc.
[0027] If it is determined in S101 that the conditions for scavenging operation are not met, the processing circuit 110 terminates this series of processes. On the other hand, if it is determined in S101 that the conditions for scavenging operation are met, the process proceeds to S102. As the process in S102, the processing circuit 110 takes in the current engine rotational speed NE and sets that rotational speed NE as the first rotational speed NE1 to be used in a later process. As the process in the following S103, the processing circuit 110 stops the autonomous operation of the internal combustion engine 10 by stopping the fuel injection of the internal combustion engine 10. After that, the process proceeds to S104.
[0028] The processing circuit 110 determines, as part of the process in S104, whether or not the internal combustion engine 10 can be started. The determination that the internal combustion engine 10 can be started is made, for example, when at least one of the following conditions (B1) to (B3) is met.
[0029] (B1) The air conditioning system of hybrid vehicle 500 has started operating. (B2) The charge level (SOC) of the battery 250 has fallen below the threshold. (B3) Hybrid vehicle 500 has started driving.
[0030] If it is determined in S104 that the internal combustion engine 10 cannot be started, the process proceeds to S105. The processing circuit 110 sets the second rotational speed NE2, which is the target value for the engine rotational speed during scavenging, as the process for S105. Specifically, the engine rotational speed at which the moisture content in the combustion chamber of the internal combustion engine 10 can be scavenged in the shortest time is determined by referring to a map, etc. The above moisture content can be calculated based on physical quantities and model equations that correlate with the moisture content in the combustion chamber. Examples of physical quantities that correlate with the moisture content in the combustion chamber include engine rotational speed NE, coolant temperature THW, intake air temperature THA, air-fuel ratio of the mixture, combustion temperature of the mixture, fuel injection amount, fuel temperature, and intake manifold wall temperature. The above moisture content may also be detected using a sensor. The determined engine rotational speed is set as the second rotational speed NE2. The process then proceeds to S107. On the other hand, if it is determined in S104 that the internal combustion engine 10 can be started, the process proceeds to S106. As part of the process in S106, the processing circuit 110 sets the engine rotation speed suitable for starting the internal combustion engine 10 as the second rotation speed NE2. Then proceeds to S107.
[0031] As part of the processing in S107, the processing circuit 110 controls the first motor generator 310 so that the engine rotational speed NE decreases from the first rotational speed NE1 to the second rotational speed NE2. More specifically, the processing circuit 110 controls the first motor generator 310 so that the engine rotational speed NE of the internal combustion engine 10, which is rotated by the first motor generator 310, decreases to the second rotational speed NE2 while being set to a value between the first rotational speed NE1 and the second rotational speed NE2. At this time, it is preferable to control the first motor generator 310 so that there is no increase in the engine rotational speed NE, and it is more preferable to control the first motor generator 310 so that the engine rotational speed NE decreases at a constant rate of change. Then, the process proceeds to S108.
[0032] As the process in S108, the processing circuit 110 determines whether or not there is a request to stop the scavenging operation. A request to stop the scavenging operation here is made, for example, when the internal combustion engine 10 needs to operate independently to satisfy the required drive torque Tr. If it is determined in S108 that there is no request to stop the scavenging operation, the process proceeds to S109. As the process in S109, the processing circuit 110 starts the scavenging operation when the engine rotational speed NE decreases to the second rotational speed NE2. This scavenging operation continues until an operating time determined, for example, according to the amount of moisture in the combustion chamber calculated above, has elapsed. After that, the processing circuit 110 terminates this series of processes.
[0033] On the other hand, if it is determined in S108 that there is a request to stop the scavenging operation, the process proceeds to S110. As part of the processing in S110, the processing circuit 110 stops the scavenging operation of the internal combustion engine 10 and then terminates this series of processes. At this point, the processing circuit 110 starts the internal combustion engine 10. As a result, the internal combustion engine 10 starts independent operation.
[0034] Next, the effects and advantages of the electric vehicle of this embodiment, i.e., the hybrid vehicle 500, will be described. (1) When the conditions for performing scavenging are met during the autonomous operation of the internal combustion engine 10, the autonomous operation of the internal combustion engine 10 is stopped, for example, at timing T1 in Figure 4. Subsequently, the first motor generator 310 is controlled so that the engine rotation speed NE decreases to the second rotation speed NE2, while maintaining a value between the first rotation speed NE1 and the second rotation speed NE2, as shown by the solid line in Figure 4. Then, based on the fact that the engine rotation speed NE has decreased to the second rotation speed NE2 at timing T2 in Figure 4, scavenging is started. As a result, after the autonomous operation of the internal combustion engine 10 is stopped, the first motor generator 310 will not control the engine rotation speed NE to increase to the value at the time the autonomous operation was stopped, i.e., above the first rotation speed NE1, as shown by the dashed line in Figure 4. Therefore, it is possible to suppress the increased power consumption of the first motor generator 310 in such cases. Consequently, it is possible to suppress the deterioration of the electric efficiency of the hybrid vehicle 500 that occurs due to increased power consumption of the first motor generator 310.
[0035] (2) After the autonomous operation of the internal combustion engine 10 is stopped based on the fulfillment of the conditions for performing scavenging, it is conceivable to reduce the engine rotation speed NE to the second rotation speed NE2 through the control of the first motor generator 310, while preventing an increase in the engine rotation speed NE. In this case, when reducing the engine rotation speed NE from the first rotation speed NE1 to the second rotation speed NE2, the engine rotation speed NE will not increase due to the first motor generator 310 as shown by the dashed line in Figure 5. As a result, the increase in power consumption of the first motor generator 310 due to the driving of the first motor generator 310 can be suppressed. For this reason, the deterioration of the electric efficiency of the hybrid vehicle 500 due to the increase in power consumption of the first motor generator 310 can be effectively suppressed.
[0036] (3) As described above, when the engine rotational speed NE is reduced from the first rotational speed NE1 to the second rotational speed NE2 through the control of the first motor generator 310, it is conceivable to control the first motor generator 310 so that the engine rotational speed NE decreases at a constant rate of change. In this case, as shown by the solid line in Figure 6, the engine rotational speed NE decreases from the first rotational speed NE1 to the second rotational speed NE2. This makes it possible to smoothly reduce the engine rotational speed NE to the second rotational speed NE2.
[0037] (4) When the engine speed NE begins to decrease toward the second rotational speed NE2 after the self-sustaining operation of the internal combustion engine 10 has stopped based on the conditions for performing scavenging, the second rotational speed NE2 is usually the value that allows for the shortest possible scavenging operation. However, when there is a possibility of starting the internal combustion engine 10, the second rotational speed NE2 is the value suitable for starting the internal combustion engine 10. For this reason, when a request to start the internal combustion engine 10 is made after the engine speed NE has begun to decrease from the first rotational speed NE1 toward the second rotational speed NE2, the internal combustion engine 10 can be restarted quickly.
[0038] (5) After the autonomous operation of the internal combustion engine 10 is stopped based on the fulfillment of the conditions for performing scavenging, if there is a request to stop scavenging, the first motor generator 310 is controlled as follows: The control of the first motor generator 310 to reduce the engine rotation speed NE to the second rotation speed NE2 is terminated, and control of the first motor generator 310 to start the internal combustion engine 10 is performed. This prevents unnecessary scavenging from being performed.
[0039] The above embodiment can also be modified as follows, for example. The above embodiment and the following modifications can be combined and implemented to the extent that they do not contradict each other technically. • By omitting processes S108 and S110 in the series of processes shown in Figure 3, the process may proceed to S109 after executing process S107.
[0040] • By omitting processes S104 and S106 in the series of processes shown in Figure 3, the process may proceed to S105 after executing process S103. After the autonomous operation of the internal combustion engine 10 is stopped based on the fulfillment of the conditions for performing scavenging, it is not essential to reduce the engine rotational speed NE at a constant rate of change through the control of the first motor generator 310.
[0041] After the autonomous operation of the internal combustion engine 10 was stopped based on the fulfillment of the conditions for scavenging, the engine rotation speed NE was reduced to the second rotation speed NE2 through the control of the first motor generator 310, while preventing an increase in the engine rotation speed NE. However, this is not essential. In other words, the engine rotation speed NE may temporarily increase as long as it is between the first rotation speed NE1 and the second rotation speed NE2.
[0042] The internal combustion engine 10 does not necessarily have to use hydrogen as fuel; it may use other fuels such as gasoline. Although the hybrid vehicle 500 was given as an example of an electric vehicle, the present invention may also be applied to an electric vehicle that, for example, is equipped with an internal combustion engine solely for power generation and is driven only by an electric motor. [Explanation of symbols]
[0043] 10...Internal combustion engine, 18...Crankshaft, 51...Air flow meter, 52...Crank angle sensor, 53...Water temperature sensor, 54...Intake air temperature sensor, 55...Accelerator position sensor, 56...Speed sensor, 100...Control device, 110...Processing circuit, 200...PCU, 250...Battery, 300...Terminal for external power supply, 310...First motor generator, 310a...Rotating shaft, 320...Second motor generator, 320a...Rotating shaft, 350...Planetary gear mechanism, 360...Drive wheels, 500...Hybrid vehicle.
Claims
1. An electric vehicle comprising an internal combustion engine capable of stopping autonomous operation, a motor capable of rotating the internal combustion engine after autonomous operation has stopped, and a control unit that controls the internal combustion engine and the motor, wherein the control unit performs a scavenging operation in which the internal combustion engine is rotated by the motor after autonomous operation of the internal combustion engine has stopped, The control unit, when the conditions for executing the scavenging operation are met, acquires the engine rotation speed at that time as the first rotation speed and sets a second rotation speed as the target value for the engine rotation speed during the scavenging operation. After the autonomous operation of the internal combustion engine is stopped based on the conditions for executing the scavenging operation being met, the motor controls the motor to reduce the engine rotation speed of the internal combustion engine, which is rotated by the motor, to a value between the first and second rotation speeds, and then starts the scavenging operation based on the fact that the engine rotation speed has decreased to the second rotation speed through the control of the motor.
2. The electric vehicle according to claim 1, wherein the control unit controls the motor to reduce the engine rotation speed of the internal combustion engine, which is rotated by the motor, to the second rotation speed while keeping the engine rotation speed between the first rotation speed and the second rotation speed, after the autonomous operation of the internal combustion engine has been stopped based on the fulfillment of the conditions for executing the scavenging operation, and controls the motor in such a way that the engine rotation speed does not increase.
3. The electric vehicle according to claim 2, wherein the control unit controls the motor to reduce the engine rotation speed of the internal combustion engine, which is rotated by the motor, to the second rotation speed while keeping the engine rotation speed between the first rotation speed and the second rotation speed, after the autonomous operation of the internal combustion engine has been stopped based on the fulfillment of the conditions for executing the scavenging operation, and controls the motor to reduce the engine rotation speed at a constant rate of change.
4. The electric vehicle according to any one of claims 1 to 3, wherein the control unit sets the second rotational speed to a value that minimizes the scavenging operation, and sets the second rotational speed to a value suitable for starting the internal combustion engine when there is a possibility of starting the internal combustion engine after the self-sustaining operation of the internal combustion engine has stopped.
5. The electric vehicle according to any one of claims 1 to 3, wherein the control unit, after stopping the autonomous operation of the internal combustion engine, when there is a request to stop the scavenging operation, terminates the control of the motor to reduce the engine rotation speed to the second rotation speed and controls the motor to start the internal combustion engine.