Vehicle control system

Abstract

This vehicle control system to be mounted on an electric vehicle comprises: an internal combustion engine; a motor; a power generator; and a control device that can perform switching between a series mode for driving the power generator by the internal combustion engine, driving the motor by means of generated power, and driving an axle by the motor, and a parallel mode for driving the axle by the internal combustion engine. The control device acquires a demand output of the electric vehicle and a real output which is being actually transmitted to the axle, and, if the demand output is higher than the real output when switching the series mode to the parallel mode, executes first control for changing a parallel ratio which is an output proportion of the parallel mode so as not to reduce the real output.

Description

Vehicle Control System

[0001] The present disclosure relates to vehicle control systems.

[0002] 2. Description of the Related Art Conventionally, a vehicle control system that switches from a series mode to a parallel mode is known (see, for example, Patent Document 1).

[0003] JP 2014-234065 A

[0004] When switching from series mode to parallel mode, if the actual power transmitted to the axles decreases, the vehicle's acceleration feeling will deteriorate.

[0005] An object of the present disclosure is to provide a vehicle control system that can suppress a decrease in actual output.

[0006] The vehicle control system according to the present disclosure is a vehicle control system mounted on an electric vehicle, and includes an internal combustion engine, a motor, a generator, and a control device capable of switching between a series mode in which the generator is driven by the internal combustion engine, the motor is driven by the generated electricity, and the motor drives an axle, and a parallel mode in which the axle is driven by the internal combustion engine, and the control device acquires the required output of the electric vehicle and the actual output actually transmitted to the axle, and when switching from the series mode to the parallel mode, if the required output is higher than the actual output, executes a first control that changes the parallel ratio, which is the output proportion of the parallel mode, so as to prevent a decrease in the actual output.

[0007] According to the present disclosure, a vehicle control system that can suppress a decrease in actual output can be provided.

[0008] 2 is a system diagram of a vehicle control system according to a first embodiment of the present disclosure; FIG. 3 is a diagram showing output characteristics in series mode and parallel mode according to the first embodiment of the present disclosure; FIG. 4 is a diagram showing parallel ratios at points C and D in FIG. 2; FIG. 5 is a flowchart showing a control procedure executed by a control device according to the first embodiment of the present disclosure; FIG. 6 is a system diagram of a vehicle control system according to a second embodiment of the present disclosure; FIG. 7 is a diagram showing output characteristics in series mode and parallel mode according to the second embodiment of the present disclosure; and FIG. 8 is a flowchart showing a control procedure executed by a control device according to the second embodiment of the present disclosure.

[0009] First Embodiment A first embodiment of the present disclosure will be described below with reference to the drawings.

[0010] 1 , the vehicle control system 1 includes an internal combustion engine 2, a motor (FrM) 3, a generator (GEN) 4, a traction 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 2, an accelerator pedal 16 operated by a user of the electric vehicle C, an inverter 18 that controls the motor 3 and the generator 4, and a charger 20. In this embodiment, the electric vehicle C is a plug-in hybrid vehicle (PHEV) that can externally charge the traction battery 6 with electric power from an external power source using the charger 20, or can receive external power from the traction battery 6. However, the electric vehicle C may also be a hybrid car or the like.

[0011] The motor 3 is connected to an axle 10 via a transaxle 8. The axle 10 drives the wheels C1. In this embodiment, the motor 3 is, for example, a three-phase AC motor-generator. When powering, the motor 3 receives power from the generator 4 and the drive battery 6 via an inverter 18. When regenerating, the motor 3 supplies power to the drive battery 6 via the inverter 18.

[0012] The generator 4 is connected to the internal combustion engine 2 and is capable of driving the internal combustion engine 2. The generator 4 performs motoring to drive the internal combustion engine 2 while powered by electric power from the drive battery 6. On the other hand, the generator 4 is driven by the internal combustion engine 2 to generate electricity while the internal combustion engine 2 is in operation. Therefore, the generator 4 is a motor-generator capable of powering and generating electricity.

[0013] The drive battery 6 outputs electric power to the motor 3 and the generator 4, and also receives electric power generated by the motor 3 and the generator 4. The drive battery 6 in this embodiment is formed of a secondary battery such as a lithium ion battery.

[0014] The transaxle 8 has a plurality of gears and a clutch 8a. The internal combustion engine 2 is connected to the generator 4 and the axle 10 via the transaxle 8. When the clutch 8a is in a disengaged state, the transaxle 8 cuts off the power transmission between the internal combustion engine 2 and the axle 10, and when the clutch 8a is in a engaged state, the power of the internal combustion engine 2 is transmitted to the axle 10.

[0015] The electric vehicle C of this embodiment has various modes, including an EV mode, a series mode, a parallel mode, and a charge mode. In the EV mode, the electric vehicle C drives the motor 3 with electric power from the drive battery 6. In the series mode, the electric vehicle C drives the generator 4 with the internal combustion engine 2 and drives the motor 3 using electric power generated by the generator 4. In the EV mode and the series mode, the clutch 8a is maintained in a disengaged state. In the parallel mode, the electric vehicle C engages the clutch 8a and drives the axle 10 using power from the internal combustion engine 2. In the charge mode, the electric vehicle C drives the generator 4 with the internal combustion engine 2 and stores the electric power generated by the generator 4 in the drive battery 6. The electric vehicle C causes the vehicle control device 12 to switch between various modes depending on the depression state of the accelerator pedal 16 and the operation state of the charge button.

[0016] The vehicle control device 12 is a control device that controls switching between EV mode, series mode, and parallel mode (hereinafter referred to as each mode in the specification). The vehicle control device 12 is electrically connected to the motor 3, the generator 4, the clutch 8a of the transaxle 8, and the engine control device 14, and controls the motor 3 and the generator 4 via the inverter 18 according to each mode, and also controls the disengagement and engagement of the clutch 8a. The vehicle control device 12 causes the engine control device 14 to control the internal combustion engine 2 according to each mode. In addition, the vehicle control device 12 is electrically connected to various devices of the electric vehicle C (e.g., the charger 20) and performs integrated control of the various devices. The vehicle control device 12 is actually an ECU (Electronic Control Unit) configured by a microcomputer including a calculation device, a 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.

[0017] As shown in FIG. 2 , the electric vehicle C has different output characteristics depending on the vehicle speed in the series mode and the parallel mode. The vehicle control device 12 calculates, for example, the required torque (an example of required output) Fr required to accelerate the electric vehicle C, and controls the clutch 8a according to the required torque Fr to switch from the series mode to the parallel mode. The vehicle control device 12 switches from the series mode to the parallel mode while adjusting a first output (torque) Pf in the parallel mode and a second output (torque) Sf, which is the output in the series mode. The first output Pf is an output directly distributed from the internal combustion engine 2 to the axle 10. The second output Sf is an output from the internal combustion engine 2 that drives the motor 3 via the generator 4 and is distributed to the axle 10.

[0018] Specifically, the vehicle control device 12 calculates the required torque Fr from the accelerator opening Th based on the depression amount of the accelerator pedal 16. The accelerator opening Th may be a value calculated by the vehicle control device 12 when the electric vehicle C is in cruise control, for example. The required torque Fr may be a torque that takes into account the amount of power generated by the generator 4, in addition to the accelerator opening Th.

[0019] The vehicle control device 12 further acquires the rotation speed of the axle 10 and the vehicle speed V. The vehicle control device 12 calculates the actual torque (one example of actual output) F, which is the torque actually transmitted to the axle 10, from the rotation speed of the axle 10. For example, when the vehicle speed V is a first vehicle speed V1, the actual torque F is at point A in Figure 2, and the required torque Fr continues to increase and is greater than the actual torque F, the vehicle control device 12 executes first control to switch from the series mode to the parallel mode.

[0020] In the first control, the vehicle control device 12 calculates the actual torque F for each predetermined cycle. The vehicle control device 12 changes the parallel ratio x, which is the output ratio in the parallel mode, so that the actual torque F does not decrease.

[0021] A more specific example will be described using Figures 2 and 3. The graph of Fs in Figure 2 is a graph showing the characteristics of series maximum torque (an example of series maximum output) Fs, which is the maximum torque in series mode. The graph of Fp in Figure 2 is a graph showing the characteristics of parallel maximum torque (an example of parallel maximum output) Fp, which is the maximum torque in parallel mode, according to accelerator opening Th (in this embodiment, accelerator opening Th is 100 percent). In this embodiment, an example will be described in which required torque Fr increases from point A to point B in Figure 2. The vehicle control device 12 calculates the parallel ratio x so that the actual torque F follows the required torque Fr.

[0022] Point C in FIG. 2 is a point where the actual torque F has increased from point A. Point D in FIG. 2 is a point where the actual torque F has increased by one cycle from point C. The vehicle control device 12 calculates the actual torque F1 at point C using equation (1). F1 = F ｓ１ ×(1-x1)+F ｐ１ ×x １ ...Formula (1) F ｓ１ is the series maximum torque Fs at point C. ｐ１ is the parallel maximum torque Fp at point C. x1 is the parallel ratio x at point C. F ｐ１ ×x １ corresponds to the first output Pf at point C. ｓ１×(1−x1) corresponds to the second output Sf at point C. That is, the parallel ratio x indicates the ratio of the first output Pf to the difference between the parallel maximum torque Fp and the series maximum torque Fs.

[0023] Similarly, the vehicle control device 12 calculates the actual torque F ２ is calculated using equation (2). ２ = F ｓ２ ×(1-x ２ )+F ｐ２ ×x ２ ...Formula (2) F ｓ２ is the maximum torque Fs at point D. ｐ２ is the parallel maximum torque Fp at point D. ２ is the parallel ratio x at point C.

[0024] As shown in FIG. 2, as the vehicle speed V increases, the parallel maximum torque Fp and the series maximum torque Fs decrease. Therefore, at points C and D, the series maximum torque Fs and the parallel maximum torque Fp decrease. If the parallel ratio x is increased at a constant rate, F ２ and F １ In such a case, as shown by the dashed line in Fig. 2, the actual torque F decreases, the acceleration of the electric vehicle C decreases, and the acceleration feeling is impaired.

[0025] Therefore, the vehicle control device 12 ２ and F １ The parallel ratio x is set to satisfy equation (3) so that the difference between ２ Calculate the following. Here, ηs is the rate of decrease of the series maximum torque Fs from point C to point D. ηp is the rate of decrease of the parallel maximum torque Fp from point C to point D.

[0026] As shown in FIG. 3, the first term of the equation (3) is the parallel maximum torque Fp ２ and maximum torque Fs ２The second term of the equation (3) represents the ratio of the series maximum torque Fs that has decreased from point C to point D relative to the difference between the series maximum torque Fs and the parallel maximum torque Fp at point D. ２ and maximum torque Fs ２ The parallel ratio at point C is x １ 4 shows the ratio of the first output Pf to the

[0027] That is, the vehicle control device 12 adjusts the parallel ratio x so as to maintain a torque equal to or greater than the sum of the first output Pf corresponding to the parallel ratio x1 at point C and the torque compensating for the torque reduction of the series maximum torque Fs from point C to point D (corresponding to the actual torque F obtained in the previous cycle). ２ This prevents the actual torque F from decreasing. Also, the maximum series torque Fs at point C is １ From point D, the maximum torque Fs of the series ２ The larger the rate of decrease, the larger the ratio of the numerator to the denominator of the first term of equation (3). １ Parallel ratio x at point D ２ The change in the parallel ratio x to the parallel maximum torque Fp ２ and maximum torque Fs ２ The larger the difference between

[0028] Instead of the above calculation, the vehicle control device 12 may calculate the parallel ratio x1 at point C by back-calculating the actual torque F1. ２ Using the actual torque F ２ Even with such a calculation, the actual torque F does not decrease.

[0029] The vehicle control device 12 has a second control for switching from the series mode to the parallel mode while maintaining a constant change in the parallel ratio x. The second control is executed when switching from the series mode to the parallel mode when the required torque Fr is equal to or less than the actual torque F. For example, when the required torque Fr transitions from point E to point F in FIG. 2 , the vehicle control device 12 switches from the series mode to the parallel mode when the vehicle speed V reaches a predetermined vehicle speed Vt (an example of a predetermined speed). In such a case, if the required torque Fr is equal to or less than the actual torque F, the vehicle control device 12 switches from the series mode to the parallel mode by the second control. The predetermined vehicle speed Vt is a vehicle speed V at which the parallel mode is more efficient than the series mode. In this embodiment, the predetermined vehicle speed Vt is a value determined in advance by comparing the power generation efficiency of the generator 4 with the transmission efficiency from the internal combustion engine 2 to the axle 10.

[0030] In the second control, the vehicle control device 12 keeps the change in the parallel ratio x constant. Specifically, the vehicle control device 12 increases the parallel ratio x by a preset constant rate. By changing the parallel ratio x in this way, the vehicle control device 12 can easily adjust the feeling related to noise, vibration, and harshness of the electric vehicle C that occurs when switching from the series mode to the parallel mode.

[0031] Next, a control procedure executed by the vehicle control device 12 will be described with reference to the flowchart of Fig. 4. The vehicle control device 12 starts the control procedure when an ignition switch (not shown) is pressed.

[0032] In step S1, the vehicle control device 12 determines whether or not there is a request to switch from series mode to parallel mode. As described above, the vehicle control device 12 may determine that there is a request to switch to parallel mode when a required torque Fr equal to or greater than the series maximum torque Fs is generated. Alternatively, as described above, the vehicle control device 12 may determine that there is a request to switch to parallel mode when the vehicle speed is equal to or greater than a predetermined vehicle speed Vt. If the vehicle control device 12 determines that there is a request to switch to parallel mode (YES in step S1), the process proceeds to step S2. On the other hand, if the vehicle control device 12 determines that there is no request to switch to parallel mode (NO in step S1), the process of step S1 is repeated and the vehicle control device 12 waits until there is a request to switch to parallel mode.

[0033] In step S2, the vehicle control device 12 controls the clutch 8a to put the clutch 8a into an engaged state. After putting the clutch 8a into an engaged state, the vehicle control device 12 proceeds to step S3.

[0034] In step S3, the vehicle control device 12 determines whether the required torque Fr is greater than the actual torque F. If the vehicle control device 12 determines that the required torque Fr is greater than the actual torque F (YES in step S3), the process proceeds to step S4, where the first control is executed. On the other hand, if the vehicle control device 12 determines that the required torque Fr is equal to or less than the actual torque F (NO in step S3), the vehicle control device 12 executes the second control.

[0035] In this way, by selectively using the first control and the second control, the vehicle control system 1 prevents a loss of the acceleration feeling of the electric vehicle C while maintaining the feeling related to noise, vibration, and harshness. In this way, the vehicle control system 1 can improve the power performance of the electric vehicle C without sacrificing the comfort of the electric vehicle C.

[0036] Second Embodiment Next, a vehicle control system 201 according to a second embodiment of the present disclosure will be described. In the second embodiment, only the differences from the first embodiment will be described.

[0037] A vehicle control system 201 in the second embodiment differs from the vehicle control system 1 in the first embodiment in that a transaxle 208 has multiple gears. As shown in Fig. 5 , the vehicle control system 201 includes an internal combustion engine 202, a motor (FrM) 203, a generator (GEN) 204, a drive battery (BT) 206, a transaxle (an example of a transmission) 208, a vehicle control device (an example of a control device) 212, an engine control device 214 that controls the internal combustion engine 202, an accelerator pedal 216 operated by a user of the electric vehicle C, an inverter 218 that controls the motor 203 and the generator 204, and a charger 220. The configuration other than the transaxle 208 and the vehicle control device 212 is the same as that in the first embodiment, and therefore description thereof will be omitted. In addition to the clutch 208a, the transaxle 208 has a low gear (an example of a first gear) 208b, a high gear (an example of a second gear) 208c, and a gear switching device 208d. The gear switching device 208d is a device that can switch between the low gear 208b and the high gear 208c. The vehicle control device 212 controls the gear switching device 208d to switch between the low gear and the high gear, in addition to controlling the switching from the series mode to the parallel mode.

[0038] As shown in Fig. 6, the electric vehicle C according to the second embodiment has different output characteristics depending on the vehicle speed V in the series mode, low gear parallel mode, and high gear parallel mode. The parallel maximum torque FsHi in the high gear parallel mode is lower than the series maximum torque FsLo in the low gear parallel mode. On the other hand, the high gear parallel mode can output torque up to a position where the vehicle speed V is higher than that in the low gear parallel mode.

[0039] The vehicle control device 212 executes the first control if a low gear is selected when switching from series mode to parallel mode. The case where the vehicle control device 212 switches from series mode to parallel mode while selecting a low gear is, for example, when the required torque Fr changes from point G to point H in FIG. 6. In other words, the vehicle control device 212 executes the first control when the vehicle control system 1 strongly accelerates the electric vehicle C. When strongly accelerating the electric vehicle C in this way, it is preferable to prioritize not impairing the acceleration feeling.

[0040] The vehicle control device 212 executes the second control if a high gear is selected when switching from series mode to parallel mode. The case where the vehicle control device 212 switches from series mode to parallel mode while selecting a high gear is, for example, when the required torque Fr changes from point I to point J in FIG. 6 . That is, the vehicle control device 212 executes the second control when the vehicle control system 1 increases only the vehicle speed V while decreasing the acceleration of the electric vehicle C. When increasing the vehicle speed V of the electric vehicle C in this manner, it is preferable to prioritize not impairing the feeling related to noise, vibration, and harshness.

[0041] Next, a control procedure executed by the vehicle control device 12 will be described with reference to the flowchart of Fig. 7. The vehicle control device 212 starts the control procedure when an ignition switch (not shown) is pressed.

[0042] In step S21, the vehicle control device 212 determines whether or not there is a request to switch from series mode to parallel mode. As described above, the vehicle control device 212 may determine that there is a request to switch to parallel mode when a required torque Fr equal to or greater than the series maximum torque Fs is generated. Alternatively, as described above, the vehicle control device 212 may determine that there is a request to switch to parallel mode when the vehicle speed is equal to or greater than a predetermined vehicle speed Vt. If the vehicle control device 212 determines that there is a request to switch to parallel mode (YES in step S21), the process proceeds to step S22. On the other hand, if the vehicle control device 212 determines that there is no request to switch to parallel mode (NO in step S21), the process of step S21 is repeated and the vehicle control device 212 waits until there is a request to switch to parallel mode.

[0043] In step S22, the vehicle control device 212 determines whether there is a request to switch to the parallel mode low gear. The vehicle control device 212 may select the low gear 208b or the high gear 208c based on the required torque Fr. For example, the vehicle control device 212 may determine that there is a request to switch to the parallel mode low gear when a torque higher than the series maximum torque Fs is required in the parallel mode. If the vehicle control device 212 determines that there is a request to switch to the parallel mode low gear (YES in step S22), the process proceeds to step S23.

[0044] In step S23, the vehicle control device 212 switches to low gear 208b and controls clutch 208a to connect clutch 208a. After connecting clutch 208a, the vehicle control device 212 proceeds to step S24.

[0045] In step S24, the vehicle control device 12 determines whether the required torque Fr is greater than the actual torque F. If the vehicle control device 12 determines that the required torque Fr is greater than the actual torque F (YES in step S24), the process proceeds to step S25, where the vehicle control device 12 executes the first control. After executing the first control, the vehicle control device 212 proceeds to step S21.

[0046] If the vehicle control device 212 determines in step S22 that there is no request to switch to the parallel mode low gear (step S22 NO), the vehicle control device 212 proceeds to step S26. In step S26, the vehicle control device 212 switches to the high gear 208c and controls the clutch 208a to connect the clutch 208a. Once the vehicle control device 212 has connected the clutch 208a, the vehicle control device 212 proceeds to step S27. In step S27, the vehicle control device 212 executes the second control.

[0047] When the vehicle control device 212 determines that the required torque Fr is equal to or less than the actual torque F (NO in step S24), the vehicle control device 212 executes the second control.

[0048] As described above, the vehicle control system 201 in the second embodiment selectively uses the first control and the second control depending on the selection status of the low gear 208b and the high gear 208c, in addition to the magnitude relationship between the required torque Fr and the actual torque F. This prevents a loss of acceleration feeling when the low gear 208b of the electric vehicle C is selected, while preventing a loss of feeling related to noise, vibration, and harshness when the high gear 208c is selected. This allows the vehicle control system 201 to improve the power performance of the electric vehicle C without sacrificing comfort.

[0049] As described above, according to the present disclosure, it is possible to provide the vehicle control system 1, 201 that can suppress a decrease in the actual torque (actual output) F.

[0050] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the invention. In particular, the multiple modifications described in this specification can be combined as needed.

[0051] (a) In the first embodiment described above, an example has been described in which the vehicle control device 12 determines the parallel ratio x using equation (3) so as not to reduce the actual torque F, but the present disclosure is not limited to this. The vehicle control device 12 may perform any calculation as long as it can determine the parallel ratio x so as not to reduce the actual torque F.

[0052] (b) In the second embodiment described above, an example was described in which the transaxle 208 had two gears, low gear 208b and high gear 208c. However, the present disclosure is not limited to this. The transaxle 208 may have gears with, for example, three or more gear ratios. In this case, the vehicle control device 212 may selectively use the first control and the second control depending on the gear ratio of each gear.

[0053] 1, 201: Vehicle control system 2, 202: Internal combustion engine 3, 203: Motor 4, 204: Generator 8, 208: Transaxle 10: Axle, 12, 212: Vehicle control device 201: Vehicle control system, 202: Internal combustion engine 203: Motor, 204: Generator 208b: Low gear, 208c: High gear 208d: Gear change device C: Electric vehicle Th: Accelerator opening V: Vehicle speed, Vt: Predetermined vehicle speed x: Parallel ratio

Claims

1. A vehicle control system mounted on an electric vehicle, an internal combustion engine; A motor; A generator and a series maximum output in which the generator is driven by the internal combustion engine, the generated electric power is used to drive the motor, and the motor drives an axle; and a parallel maximum output in which the internal combustion engine drives the axle. a control device that acquires an accelerator opening degree of the electric vehicle, and is capable of switching from the series maximum output to the parallel maximum output while adjusting the series maximum output according to the accelerator opening degree and the parallel maximum output according to the accelerator opening degree; Equipped with the control device acquires a required output of the electric vehicle and an actual output transmitted to the axles, acquires the actual output for each predetermined cycle, and, when switching from the series maximum output to the parallel maximum output, if the required output is higher than the actual output and the series maximum output and the parallel maximum output decrease, executes first control to change a parallel ratio, which is an output ratio of the parallel maximum output, so that the actual output does not fall below the actual output acquired in the previous cycle. Vehicle control system.

2. The larger the difference between the parallel maximum output and the series maximum output, the larger the change in the parallel ratio. The vehicle control system of claim 1 .

3. the control device executes second control to switch from the series mode to the parallel mode while keeping the change in the parallel ratio constant when the speed of the electric vehicle is equal to or higher than a predetermined speed and the required output is equal to or lower than the actual output.

3. A vehicle control system according to claim 1 or 2.

4. a first gear that transmits power from the internal combustion engine to the axle; a second gear having a lower gear ratio than the first gear; a transmission capable of selecting the first gear and the second gear; Furthermore, The control device executes the first control when the first gear is selected, and executes the second control when the second gear is selected. The vehicle control system according to claim 3 .