Hybrid vehicle control method and hybrid vehicle control device

Abstract

To improve a hybrid vehicle by utilizing pitching caused on a vehicle body.SOLUTION: A hybrid vehicle 1 includes a first motor generator 5 capable of supplying an electrically generated power to a battery 8, a second motor generator 6 which functions as a driving source of front wheels 3, a third motor generator 7 which functions as a driving source of rear wheels 4 and an internal combustion engine 2 which functions as a driving source of the first motor generator 5. The hybrid vehicle 1 makes rear wheel share rate of driving force larger than prior acceleration request if the predetermined acceleration request is generated during travel.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] For example, Patent Document 1 discloses a technology for suppressing pitch vibration of a vehicle body in a hybrid vehicle driven by the driving force of an internal combustion engine and an electric motor by increasing or decreasing the driving force of the vehicle by the electric motor (motor driving force) and changing the distribution of the driving force of the vehicle by the internal combustion engine (engine driving force) and the motor driving force depending on the degree of pitch vibration. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-114821 Summary of the Invention [Problem to be solved by the invention]

[0004] However, Patent Document 1 is a technology for suppressing pitch vibrations that occur in the vehicle body, and does not actively utilize pitch vibrations that occur in the vehicle body.

[0005] In other words, in hybrid vehicles, there is room for further study regarding improvements that utilize pitch vibrations (pitching) that occur in the vehicle body. [Means for solving the problem]

[0006] The hybrid vehicle of the present invention has a first electric motor capable of supplying generated electricity to a battery, a second electric motor that serves as a drive source for the front wheels, a third electric motor that serves as a drive source for the rear wheels, and an internal combustion engine that serves as a drive source for the first electric motor, and is capable of distributing the driving force of the entire vehicle to the front wheels and rear wheels in a predetermined ratio depending on the driving state, and when a predetermined acceleration request occurs while driving, the rear wheel share of the driving force is made larger than before the acceleration request. The predetermined acceleration request occurs when the accelerator pedal is fully opened while the vehicle is traveling at a speed equal to or greater than a predetermined vehicle speed, and the rate of change in the accelerator pedal opening until the accelerator pedal is fully opened is equal to or greater than a predetermined value. [Effects of the Invention]

[0007] In the hybrid vehicle of the present invention, when a specified acceleration request is made, the rear wheel share of the driving force becomes larger, making it possible to create a pseudo acceleration by pitching, allowing the driver to drive without losing the feeling of acceleration. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an explanatory diagram showing an example of the configuration of a powertrain of a hybrid vehicle to which the present invention is applied; [Figure 2] FIG. 2 is an explanatory diagram illustrating pitching of a hybrid vehicle. [Figure 3] FIG. 4 is a characteristic diagram illustrating an example of the relationship between acceleration calculated from vehicle speed and acceleration detected by an acceleration sensor. [Figure 4] FIG. 4 is a characteristic diagram showing a change in acceleration of a hybrid vehicle when a predetermined acceleration request is made while the vehicle is running. [Figure 5] FIG. 4 is a characteristic diagram showing changes in the distribution of driving force to the rear wheels when a predetermined acceleration request is made while driving. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described in detail with reference to the accompanying drawings. Figure 1 is an explanatory diagram showing an example of the configuration of a power train of a hybrid vehicle 1 to which the present invention is applied.

[0010] The hybrid vehicle 1 is a so-called series hybrid vehicle that does not use the internal combustion engine 2 as a direct power source. That is, in the hybrid vehicle 1 of this embodiment, the internal combustion engine 2 is used exclusively for generating electricity, and the drive wheels are driven by electric motors. The hybrid vehicle 1 is also a so-called four-wheel drive vehicle, and the drive force of the entire vehicle can be distributed to the front wheels 3 and the rear wheels 4 in a desired ratio.

[0011] That is, the hybrid vehicle 1 has an internal combustion engine 2 for generating electricity, a first motor generator 5 driven by the internal combustion engine 2, a second motor generator 6 that is the drive source for the front wheels 3, a third motor generator 7 that is the drive source for the rear wheels 4, and a battery 8 that can charge the electricity generated by the first motor generator 5, and the front wheels 3 and rear wheels 4 each use a different electric motor as the drive source.

[0012] The internal combustion engine 2 is connected to work in conjunction with the first motor generator 5. The internal combustion engine 2 may use the first motor generator 5 as a starter when starting. Alternatively, the internal combustion engine 2 may be started by a dedicated starter motor different from the first motor generator 5.

[0013] The first motor generator 5 corresponds to the first electric motor and is a motor generator mainly used for generating electricity. The electric power generated by the first motor generator 5 is supplied to the battery 8 or the second and third motor generators 6 and 7 via an inverter (not shown). In other words, depending on the operating state, the electric power generated by the first motor generator 5 can be supplied directly to the second and third motor generators 6 and 7 instead of being used to charge the battery 8, for example.

[0014] The second motor generator 6 corresponds to a second electric motor and is a motor generator mainly used for driving the vehicle. The second motor generator 6 is mainly supplied with power from the battery 8 and serves as a drive source for the front wheels 3. The rotation of the second motor generator 6 is transmitted to the front wheels 3 via a first gear train 11. The first gear train 11 has a first input shaft 12 to which the rotating shaft of the second motor generator 6 is directly connected, and a first output shaft 13 connected to the front wheels 3. The first gear train 11 is configured so that torque can be transmitted from the first input shaft 12 to the first output shaft 13.

[0015] The third motor generator 7 corresponds to a third electric motor and is a motor generator mainly used for driving the vehicle. The third motor generator 7 is mainly supplied with power from the battery 8 and serves as a drive source for the front wheels 3. The rotation of the third motor generator 7 is transmitted to the rear wheels 4 via a second gear train 14. The second gear train 14 has a second input shaft 15 to which the rotating shaft of the third motor generator 7 is directly connected, and a second output shaft 16 connected to the rear wheels 4. The second gear train 14 is configured so that torque can be transmitted from the second input shaft 15 to the second output shaft 16.

[0016] The first, second and third motor generators 5, 6 and 7 are each connected via the inverter to a battery 8. The hybrid vehicle 1 has a powertrain controller 21 that controls the entire powertrain in response to driver requests and the like.

[0017] The powertrain controller 21 receives detection signals from various sensors, such as an acceleration sensor 22 that detects the acceleration of the hybrid vehicle 1, a vehicle speed sensor 23 that detects the vehicle speed of the hybrid vehicle 1, a temperature sensor 24 that can detect the outside air temperature, and a humidity sensor 25 that can detect the humidity around the hybrid vehicle 1. The powertrain controller 21 also receives information from a car navigation system 26 that assists driving of the hybrid vehicle 1. The powertrain controller 21 can calculate the acceleration of the hybrid vehicle 1 using the detection value of the vehicle speed sensor 23.

[0018] The powertrain controller 21 controls the motor generators 5, 6, and 7 via a motor controller 31 serving as a first control unit and a second control unit. The powertrain controller 21 controls the internal combustion engine 2 via an engine controller 32. The motor controller 31 can distribute the driving force of the entire vehicle to the front wheels 3 and the rear wheels 4 in a desired ratio.

[0019] The second and third motor generators 6, 7 function as generators when the hybrid vehicle 1 decelerates. That is, the second and third motor generators 6, 7 are generator motors that can charge the battery 8 with regenerative energy generated when the vehicle decelerates as electric power.

[0020] Here, in the hybrid vehicle 1 of this embodiment, the internal combustion engine 2 is not directly (mechanically) connected to the drive wheels, that is, the front wheels 3 and the rear wheels 4. Therefore, the hybrid vehicle 1 can achieve a responsive acceleration feeling without being hindered by the internal combustion engine 2 from making sudden changes in the rotation speed of the second and third motor generators 6 and 7.

[0021] However, in order to realize acceleration performance that can respond to a sudden acceleration request while traveling, the hybrid vehicle 1 is required to have a high maximum acceleration value.

[0022] One way to increase the maximum acceleration value is to increase the amount of electric power supplied to the second and third motor generators 6 and 7. However, in order to increase the amount of electric power supplied to the second and third motor generators 6 and 7, it is necessary to increase the output of the internal combustion engine 2, which may increase the cost and weight of the internal combustion engine 2.

[0023] Furthermore, if the hybrid vehicle 1 is configured to quickly reach maximum output in response to a sudden acceleration request while driving, the amount of electricity generated can be secured, but the engine speed of the internal combustion engine 2 will rise suddenly, and the vehicle speed will not keep up with the engine noise, which may result in a deterioration in noise and vibration performance.

[0024] Passengers of the hybrid vehicle 1 feel a sense of acceleration as the vehicle speed increases, but they also feel a pseudo-acceleration sensation due to pitching, which is a rotational behavior around an axis along the width direction of the hybrid vehicle 1. The pseudo-acceleration sensation due to pitching occurs when the hybrid vehicle 1 tries to rotate in a direction that lifts the front wheels 3, as shown in Figure 2.

[0025] In other words, the acceleration detected by the acceleration sensor 22, i.e., the acceleration felt by the occupants, does not necessarily coincide with the acceleration calculated from the vehicle speed of the hybrid vehicle 1, but rather takes into account the pseudo-acceleration sensation caused by pitching.

[0026] FIG. 3 is a characteristic diagram that schematically shows an example of the relationship between the acceleration calculated from the vehicle speed (dashed line in FIG. 3) and the acceleration detected by the acceleration sensor 22 (solid line in FIG. 3) in the above-described hybrid vehicle 1.

[0027] When pitching occurs in the hybrid vehicle 1, the acceleration detected by the acceleration sensor 22 becomes a value greater than the acceleration calculated from the vehicle speed, as shown in FIG.

[0028] Therefore, in the hybrid vehicle 1 of this embodiment, when a predetermined sudden acceleration request occurs while traveling, the motor controller 31 increases the rear wheel driving force share rate compared to before the acceleration request, thereby generating a pseudo acceleration feeling by pitching. In other words, when a predetermined sudden acceleration request occurs while traveling, the motor controller 31 increases the rear wheel driving force share rate compared to before the acceleration request.

[0029] A predetermined sudden acceleration request is, for example, when the accelerator opening (throttle opening) is fully opened while traveling at a speed equal to or greater than a predetermined vehicle speed, and the rate of change in the accelerator opening until the accelerator opening is fully opened is equal to or greater than a predetermined value.

[0030] In addition, when the powertrain controller 21 determines that the hybrid vehicle 1 is traveling on a highway based on information from the car navigation system 26, for example, and a predetermined sudden acceleration request occurs, the hybrid vehicle 1 is permitted to increase the rear wheel driving force share rate compared to before the acceleration request.

[0031] As a result, the occupants of the hybrid vehicle 1 can feel the acceleration due to the pitching of the vehicle in addition to the acceleration due to the vehicle speed by increasing the rear wheel share of the driving force of the hybrid vehicle 1 during a predetermined sudden acceleration.

[0032] In other words, when a predetermined sudden acceleration request is made, the rear wheels share of the driving force of the hybrid vehicle 1 becomes larger, so that pitching the hybrid vehicle 1 can produce a pseudo-acceleration, allowing the driver to drive without losing the feeling of acceleration.

[0033] When a predetermined sudden acceleration request occurs while the hybrid vehicle 1 is traveling, the rear wheel share of the driving force may be set to 100%, for example.

[0034] When a predetermined sudden acceleration request occurs while the hybrid vehicle 1 is traveling, the driving force of the rear wheels 4 may be set to the driving force at the tire slip limit. In other words, when a predetermined sudden acceleration request occurs while the hybrid vehicle 1 is traveling, the rear wheel driving force share rate may be set so that the driving force of the rear wheels 4 becomes the driving force at the tire slip limit.

[0035] The driving force at the tire slip limit is calculated based on the surrounding environment ascertained using, for example, the outside temperature, humidity, and information from a navigation system installed in the hybrid vehicle 1. The driving force at the tire slip limit becomes smaller, for example, as the outside temperature decreases, the humidity increases, and the radius of curvature of the road becomes smaller.

[0036] Furthermore, in the hybrid vehicle 1 of the above-described embodiment, when a predetermined sudden acceleration request occurs while the vehicle is traveling, the front wheel driving force share rate may be made larger than the rear wheel driving force share rate during an initial predetermined period until the output power of the battery 8 reaches a maximum. This allows the hybrid vehicle 1 to obtain a feeling of increasing acceleration without suppressing vehicle speed when a predetermined sudden acceleration request occurs while the vehicle is traveling.

[0037] FIG. 4 is a characteristic diagram showing a change in acceleration of the hybrid vehicle 1 when a predetermined sudden acceleration request is made while the hybrid vehicle 1 is running.

[0038] The characteristic line P1 shown by a thick solid line in Fig. 4 shows an example of the change in acceleration detected by the acceleration sensor 22 when the rear wheel share of driving force is increased. The characteristic line P2 shown by a dashed line in Fig. 4 shows an example of the change in acceleration when the driving force distribution between the front and rear wheels is constant before and after an acceleration request and the peak value of acceleration at the start is suppressed. The characteristic line P3 shown by a thin solid line in Fig. 4 shows an example of the change in acceleration when the driving force distribution between the front and rear wheels is constant before and after an acceleration request.

[0039] Note that characteristic line P2 in Fig. 4 overlaps with characteristic line P1 until just before time t1, and overlaps with characteristic line P3 after time t2. Characteristic line P3 in Fig. 4 overlaps with characteristic line P1 until time t1.

[0040] Fig. 5 is a characteristic diagram showing changes in the drive force distribution to the rear wheels 4 when a predetermined sudden acceleration request is made while driving. Characteristic line Q1 shown by a solid line in Fig. 5 shows an example of changes in the rear wheel drive force distribution rate when the rear wheel drive force distribution rate is increased. Characteristic line Q2 shown by a dashed line in Fig. 5 shows a case where the drive force distribution to the front and rear wheels is constant before and after the acceleration request.

[0041] 4 and 5, time t1 is the timing when the battery 8 reaches maximum output after a sudden acceleration request. In Figures 4 and 5, time t2 is the timing when, as the output of the internal combustion engine 2 increases, the electric power generated by the first motor generator 5 starts to be supplied to the second and third motor generators 6 and 7. In Figures 4 and 5, time t3 is the timing when the internal combustion engine 2 reaches maximum output and the system reaches maximum output.

[0042] Between time t0 and time t2, the hybrid vehicle 1 accelerates using only the output (electric power) of the battery 8. Between time t1 and time t2, the hybrid vehicle 1 operates using only the output (electric power) of the battery 8, and therefore the excess driving force decreases as the vehicle speed increases, causing the acceleration to attenuate (decrease). Between time t2 and time t3, the hybrid vehicle 1 accelerates using the maximum output of the battery 8 and the electric power generated by the first motor generator 5 in accordance with the output of the internal combustion engine 2. After time t3, the excess driving force decreases as the vehicle speed increases, causing the acceleration to attenuate (decrease).

[0043] When the hybrid vehicle 1 suddenly accelerates, the excess driving force decreases as the vehicle speed increases, and therefore the acceleration decreases for a predetermined period (until time t2) from time t1 when the output of the battery 8 reaches a maximum.

[0044] The hybrid vehicle 1 can also be configured to keep the acceleration low at time t1 when the output of the battery 8 is at its maximum, and allow the acceleration to increase after time t1 as shown by characteristic line P2. However, in this case, the acceleration until time t1 when the output of the battery 8 is at its maximum is kept low, resulting in a deterioration in acceleration performance.

[0045] Therefore, when a predetermined sudden acceleration request occurs, the hybrid vehicle 1 increases the rear wheel driving force share rate from the timing of maximum battery output (time t1) when the output power from the battery 8 is at its maximum, as shown by characteristic line Q1, compared to before the acceleration request.

[0046] This allows the hybrid vehicle 1 to increase the acceleration detected by the acceleration sensor 22 even after time t1, as shown by characteristic line P1, without suppressing the acceleration at time t1 when the output of the battery 8 is at its maximum. Between time t1 and time t2, the hybrid vehicle 1 generates pseudo acceleration due to pitching, thereby giving the driver a good (increasing) feeling of acceleration.

[0047] In addition, when a predetermined sudden acceleration request occurs, the hybrid vehicle 1 may make the front wheel share of the driving force greater than the rear wheel share until the timing of maximum battery output (time t1) when the output power from the battery 8 is at its maximum, and may make the rear wheel share of the driving force after time t1 greater than the rear wheel share before time t1.

[0048] Although specific embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention.

[0049] The above-described embodiments relate to a control method for a hybrid vehicle and a control device for a hybrid vehicle. [Explanation of symbols]

[0050] 1. Hybrid vehicle 2...Internal combustion engine 3...Front wheel 4...Rear wheel 5...First motor generator 6...Second motor generator 7...Third motor generator 8...Battery 21...Powertrain controller 22...Acceleration sensor 23...Vehicle speed sensor 26...Car navigation system 31...Motor controller 32...Engine controller

Claims

1. a first electric motor capable of supplying generated electric power to a battery; a second electric motor that receives power from the battery and serves as a drive source for the front wheels of the vehicle; a third electric motor that receives power from the battery and serves as a drive source for rear wheels of the vehicle; an internal combustion engine as a drive source for the first electric motor, and a hybrid vehicle capable of distributing the drive force of the entire vehicle to front wheels and rear wheels in a predetermined ratio depending on the driving state, When a predetermined acceleration request occurs while driving, the rear wheel driving force share is increased compared to before the acceleration request, A control method for a hybrid vehicle in which a predetermined acceleration request occurs when the accelerator pedal is fully opened while the vehicle is traveling at a speed equal to or greater than a predetermined vehicle speed, and the rate of change in the accelerator pedal opening until the accelerator pedal is fully opened is equal to or greater than a predetermined value.

2. 2. The method for controlling a hybrid vehicle according to claim 1, wherein when a predetermined acceleration request occurs while the vehicle is running, the rear wheel driving force share is set to 100%.

3. 2. The method for controlling a hybrid vehicle according to claim 1, wherein the driving force of the rear wheels is set to a driving force at the tire slip limit when a predetermined acceleration request occurs during driving.

4. 4. The hybrid vehicle control method according to claim 3, wherein the driving force at the tire slip limit is calculated based on the surrounding environment ascertained using information from an outside temperature, humidity, and a navigation system mounted on the vehicle.

5. 5. A control method for a hybrid vehicle according to claim 1, wherein, when information from a navigation system installed in the vehicle determines that the vehicle is traveling on a highway, if a predetermined acceleration request is made, the rear wheel driving force share rate is permitted to be larger than that before the acceleration request.

6. 6. A method for controlling a hybrid vehicle according to claim 1, wherein when a predetermined acceleration request occurs while the vehicle is running, the front wheel driving force distribution rate is made greater than the rear wheel driving force distribution rate for an initial predetermined period.

7. A control method for a hybrid vehicle according to any one of claims 1 to 6, wherein when a predetermined acceleration request occurs during driving, the rear wheel driving force share rate after the battery has reached maximum output is made larger than the rear wheel driving force share rate before the battery has reached maximum output.

8. a first electric motor capable of supplying generated electric power to a battery; a second electric motor that receives power from the battery and serves as a drive source for the front wheels of the vehicle; a third electric motor that receives power from the battery and serves as a drive source for rear wheels of the vehicle; an internal combustion engine that serves as a drive source for the first electric motor; a first control unit that can distribute the driving force of the entire vehicle to the front wheels and the rear wheels at a predetermined ratio depending on the driving state; a second control unit that, when a predetermined acceleration request is made during traveling, increases the rear wheel driving force distribution rate compared to before the acceleration request is made, A control device for a hybrid vehicle where a predetermined acceleration request occurs when the accelerator pedal is fully opened while the vehicle is traveling at a speed equal to or greater than a predetermined vehicle speed, and the rate of change in the accelerator pedal opening until the accelerator pedal is fully opened is equal to or greater than a predetermined value.

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