JP2000291461A - Series hybrid vehicle regenerative electric power consumption controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide sufficient regenerative braking force, even if exhaust gas amount is small, in a series hybrid vehicle. SOLUTION: An exhaust valve 20 is provided in an exhaust pipe 9 of an engine, and an exhaust valve control unit 21 for controlling the opening is provided. In a case where regenerative electric power is consumed by motor- operating a generator, if the engine speed exceeds a first prescribed engine speed, the opening of the exhaust valve is gradually decreased, while if the engine speed exceeds the second specified engine speed, the exhaust valve is closed. Since the motor-driven generator consumes more regenerative electric power, braking force larger than conventional braking force can be obtained. Since the opening is gradually changed, the change of load torque of the engine is smoothed, and a sense of incongruity is not generated on operating feeling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a regenerative power consumption control device for a series hybrid vehicle, which is a hybrid vehicle in which an engine is used only for driving a generator.

[0002]

2. Description of the Related Art Hybrid vehicles are equipped with an engine, a motor for driving the vehicle, and a battery for supplying power to the motor. There are various types depending on how the engine is used. The type in which the engine drives only the generator and charges the battery and supplies power to the motor with the generated power is called a series hybrid vehicle. In a series hybrid vehicle, regenerative braking is performed in which a motor operates as a generator during braking in order to secure braking force and improve fuel efficiency.

FIG. 7 shows a conventional regenerative power consumption control device for a series hybrid vehicle. In FIG. 7, 1 is an accelerator sensor, 2 is a brake switch, 3 is a shift lever,
4 is a vehicle speed sensor, 5 is a vehicle controller, 6 is an engine controller, 7 is an engine, 8 is an engine speed sensor, 9 is an exhaust pipe, 10 is a generator, 11 is a generator inverter detector, 12 is a generator inverter, 13 is a battery,
14 is a battery state detection unit, 15 is a motor inverter,
Reference numeral 16 denotes a motor inverter detection unit, 17 denotes a motor, 18 denotes a differential gear unit, and 19 denotes wheels. Generator 1 with engine 7
0 to generate AC power. Generator inverter 1
2 converts the AC power into DC power, and
And supply the same to the motor inverter 15. The motor inverter 15 converts DC power into AC power,
Power is supplied to the motor 17. The torque of the motor 17 is transmitted to the wheels 19 via the differential gear unit 18 to drive the vehicle.

An engine mounted on a series hybrid vehicle has a smaller displacement (approximately half the displacement) than an engine mounted on a vehicle in which wheels are directly driven by the engine. The reason is that, in a series hybrid vehicle, when the motor 17 requires large power, power is also supplied from the battery, so that the power generation by the engine is sufficient to cover the average power of the vehicle running load. Because it is. Also,
In general, the output efficiency of the engine is higher when the engine is operated with a high load applied to some extent. Therefore, a smaller engine is mounted on this point.

[0005] Information on the driving operation of the driver includes an accelerator sensor 1, a brake switch 2, a shift lever 3
Is transmitted to the vehicle controller 5. The vehicle speed is transmitted from the vehicle speed sensor 4 and the engine speed is transmitted from the engine speed sensor 8. Further, the state (remaining capacity, voltage, current, temperature, etc.) of the battery 13 is transmitted from the battery state detection unit 14. Generator inverter detector 11
Is for detecting the voltage, current, and power in the generator inverter 12, and the motor inverter detection unit 16 is for detecting the voltage, current, and power in the motor inverter 15.

[0006] The vehicle controller 5 is configured as a computer. That is, CPU (Central Processing Unit),
It comprises a ROM, a RAM, an input interface, an output interface and the like. Vehicle controller 5
Controls the engine 7, the generator inverter 12, and the motor inverter 15 based on the input information. The engine 7 is controlled via the engine controller 6. For example, when it is desired to increase the engine speed,
Control is performed to increase the injected fuel. When the rotational force of the motor 17 is to be increased, the motor inverter 15 is controlled so that the current from the battery 13 is increased.

[0007] A command for regenerative braking is issued by the driver's operation. The braking strength is, for example, weak regeneration when the accelerator pedal is released, and moderate regeneration when the brake pedal is depressed. , Shift lever to D
When the vehicle enters the b range, it can be set in several stages, such as strong regeneration. (Note that the Db range is used to secure braking force on steep downhill slopes, etc.) It is the range provided.). The regenerative braking transmits the traveling inertia force of the vehicle to the wheels 19 → the differential gear unit 18 → the motor 17, and operates the motor 17 as a generator,
This is done by consuming or absorbing the generated power (regenerated power) in some way. At the time of regenerative braking, the motor inverter 15 is controlled not as a converter from DC to AC but as a converter to convert AC to DC in the reverse direction, and the generated power (AC power) of the motor 17 is converted to DC power. Is done.

[0008] This DC power is first supplied to the battery 13 to charge the battery 13 (regeneration charging). But,
If an attempt is made to charge the battery beyond the limit, problems such as decomposition of the electrolytic solution, generation of gas, and increase in heat generation occur, and the life of the battery is extremely shortened. Therefore, battery 1
When the power generated by the motor 17 cannot be completely absorbed by only 3, the power is also supplied to the generator inverter 12. Such a case includes a case where the battery 13 is fully charged, a case where the regenerative power exceeds the maximum power that can be accepted by the battery (= maximum battery regenerable power) (when the vehicle speed is high or the deceleration is large). It happens in some cases).

In this case, the generator inverter 12 is controlled not as an AC → DC converter but as a DC / AC converter in the reverse direction, and converts the DC power supplied from the motor inverter 15 into a DC / AC converter. Convert to AC power.
The generator 10 is operated by a motor with this AC power, and the engine 7 is rotated. There is no need to supply fuel to the engine 7 at this time, so the engine controller 6 controls so as not to supply fuel. Therefore, the fuel is saved correspondingly, and the fuel efficiency is improved. The regenerative electric power supplied to the generator inverter 12 is consumed as power for rotating the engine 7.

[0010] Conventional documents relating to the hybrid vehicle regenerative power consumption control device include, for example, Patent Document 2
No. 800451 (Japanese Patent Application Laid-Open No. 4-322105) and Japanese Patent Application Laid-Open No. 8-79914.

[0011]

(Problems to be Solved) However, in the conventional series hybrid vehicle regenerative power consumption control device described above, even if the generator is driven by the motor to rotate the engine, the regenerative power that can be consumed is small. However, there is a problem that a sufficient regenerative braking force cannot be obtained.

(Explanation of Problems) As described above, the engine mounted on the series hybrid vehicle has a relatively small displacement, and has a small load torque when it is rotated as a rotational load. Therefore, even if an attempt is made to consume the regenerative electric power by rotating the engine, the regenerative electric power cannot be consumed when the regenerative electric power is large. If not consumed, braking power cannot be secured.

Another method of consuming regenerative power is to provide a discharge resistor and consume it there. However, such a discharge resistance becomes considerably large and heavy, so that it is not desirable to mount the discharge resistance on a vehicle which has a limited installation space and aims to reduce the weight. In order to prevent the regenerative power from becoming too large to consume enough, there is a way to use a mechanical service brake as much as possible. Inconveniences such as a decrease in the braking force and a rapid wear of the brake pad occur. An object of the present invention is to solve the above problems.

[0014]

According to the present invention, there is provided a motor for driving a vehicle which is driven by a generator at the time of regenerative braking, and a generator which is directly connected to the engine and which can be driven by the motor at the time of regenerative braking. A vehicle drive battery that is charged at the time of regenerative braking, and when the regenerative power from the motor exceeds the battery charging capacity, a series hybrid vehicle that operates the generator to drive the engine and consumes the regenerative power by rotating the engine. The regenerative power consumption control device further includes an exhaust valve in an exhaust pipe of the engine, an exhaust valve control unit that controls opening and closing of the exhaust valve, and an engine speed sensor. The exhaust valve is opened until the number of rotations increases to a predetermined number of rotations from the first predetermined rotation number to a second predetermined rotation number higher than the first predetermined rotation number. It was set to the changing the opening of the exhaust valve according to the engine speed, and controls closed like to increase than the predetermined rotational speed of the second of said exhaust valve.

(Summary of operation to be solved) When the regenerative electric power is large, if the opening degree of the exhaust valve provided in the exhaust pipe of the engine is reduced, the load torque of the engine increases in accordance with the degree of the decrease. A generator running a motor to turn on requires more power. Therefore, it is possible to consume more regenerative power than when the exhaust valve is open, and it is possible to obtain a larger braking force than before. If the engine speed at which the exhaust valve starts to close and the engine speed at which the exhaust valve closes are determined in advance, and the opening is controlled in accordance with the engine speed during that time, the change in load torque becomes smooth. Therefore, the change in the engine speed is smoother (therefore, the change in the engine noise is smoother) and the driving feeling of the driver is smaller than when the exhaust valve is controlled to take only two positions, that is, fully open and fully closed. Will also be comfortable. Conventionally, the engine of a series hybrid vehicle is provided not for directly driving wheels but for driving a generator, and thus it was not necessary to provide an exhaust valve for braking. Therefore, the state of the exhaust pipe was the same as the state where the exhaust valve was opened.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram illustrating a series hybrid vehicle regenerative power consumption control device of the present invention. The reference numerals correspond to those in FIG. 7, 20 is an exhaust valve, 21
Denotes an exhaust valve control unit. 7 are the same as those in FIG. 7, and the description thereof is omitted. The exhaust valve 20 is a valve provided in the exhaust pipe 9 of the engine 7. The exhaust valve control unit 21 sets the opening / closing amount (opening degree) of the exhaust valve 20 to an arbitrary value according to a command from the vehicle controller 5. It is provided for controlling (in other words, controlling the throttle amount of the exhaust valve 20).

According to the present invention, when the regenerative braking is started, the regenerative electric power is absorbed by the battery 13 or the generator 10 is driven by the motor with the regenerative electric power to rotate the engine 7 for consumption. The exhaust valve 20 is kept open until the rotation speed of the engine 7 increases to a _first predetermined value (N ₁ ), and closed when the rotation speed of the engine 7 exceeds a second predetermined value (N ₂ ) (however, the same as in the conventional case). When the exhaust is completely shut off, the gasket of the exhaust pipe 9 and the exhaust valve 20 may be damaged due to excessive pressure. .). Then, between the first predetermined value (N ₁ ) and the second predetermined value (N ₂ ), the opening (throttle amount) is controlled according to the engine speed.

FIG. 4 is a diagram showing such opening / closing control of the exhaust valve 20. As shown in FIG. The horizontal axis represents the engine speed, and the vertical axis represents the opening / closing amount (throttle amount) of the exhaust valve. Is open when the N ₁ (100% opening), N
(0% opening) closed and when the _two are the opening Q% of the intermediate when the N _M between N ₁ and N _2. Engine 7
The load torque becomes larger as the opening degree of the exhaust valve 20 becomes smaller, so that more regenerative power can be consumed than before. Next, it will be described.

FIG. 5 is a diagram showing a change in load torque required when the engine is run as a rotating load. The horizontal axis represents the engine speed, and the vertical axis represents the load torque. The curve A indicates the load torque when the exhaust valve 20 is open, and the curve B indicates the load torque when the exhaust valve 20 is closed. In each case,
As the engine speed increases, the load torque also increases. However, when the exhaust valve 20 is closed, the pressure in the exhaust pipe 9 increases, so that the engine 7 becomes difficult to rotate.
Therefore, the curve B is larger as a whole.

When the exhaust valve 20 is located at an intermediate position between the open state and the closed state (ie, when the exhaust valve 20 is intermediately closed), the curve is as follows.
It will be in the range of C which is the range between the curves A and B. Curve d is one example. When the case where the engine rotational speed is N try by way of example, the load torque of the curve b (in the case of fully open) is T _1, the curve b (in the case of fully closed) is T _3, curve D for (If some of the intermediate closed) is T ₂ (where _{T 1 <T 2 <T 3} ).

FIG. 6 is a diagram showing a change in power consumption when the generator is operated by the motor. The horizontal axis represents the engine speed, and the vertical axis represents the power consumption of the motor-driven generator. A curve A indicates the power consumption when the exhaust valve 20 is open, and a curve B indicates the power consumption when the exhaust valve 20 is closed. In each case, the power consumption increases as the engine speed increases, but when the exhaust valve 20 is closed, the load torque increases. Therefore, the power consumption also increases as a whole in the curve B. .

The curve C is a curve connecting the operating point D at the engine speed N ₁ of the curve A and the operating point E at the engine speed N ₂ of the curve B. This curve shows the case where the opening degree of the exhaust valve 20 is gradually reduced (the throttle amount is increased) as the engine speed increases between the engine speeds N _{1 and} N ₂ . It shows power consumption. Since the opening is gradually changed, the power consumption changes smoothly. When the generator 10 and motor driver to rotate the engine 7, the first, is rotated with open exhaust valve 20, the engine speed is increased to _one or more predetermined N, the engine speed becomes N ₂ By the way, the opening of the exhaust valve 20 is gradually reduced in accordance with the engine speed so as to be just closed. When the engine speed exceeds N ₂ , the exhaust valve 2
0 remains closed. When the engine speed decreases, the exhaust valve 20 is controlled so as to follow the opposite.

That is, during the regenerative operation when the regenerative power is large, the operating point in FIG. 6 changes from C → D → E → F in the process of increasing the engine speed, and in the process but to decrease follows a reverse (where, C is the point where engine speed curve b is in the position of less than N _1, F is a point where the engine rotational speed curve b is from N ₂ to a large position Is.). Note that the values of the rotation speeds N ₁ and N ₂ are appropriately set in consideration of the magnitude of the regenerative electric power from the motor 17 and the magnitude of the power consumption in FIG. the value of N ₁ thing than, smaller is larger than the idling speed of at least the engine (eg, 1000Rp
m). ).

Next, the control operation according to the present invention will be described. FIG. 2 is a flowchart illustrating regenerative power consumption control according to the present invention. This control is performed mainly by the vehicle controller 5. Step 1: Check whether the motor 17 is performing regenerative braking. This can be checked by checking the current flowing through the motor 17. When the regenerative braking is not being performed, the process proceeds to step 2. Step 2: In this step, the exhaust valve control unit 21 is instructed to open the exhaust valve 20 (or keep it open). Step 3: If the regenerative braking is being performed in Step 1, it is checked whether the regenerative power detected by the motor inverter detector 16 is larger than the maximum regenerable power of the battery 13. If not, go to step 2. In addition,
FIG. 3 shows the maximum power that can be regenerated by the battery.

FIG. 3 is a diagram showing the maximum power that can be regenerated to the battery. The horizontal axis represents the remaining battery capacity, and the vertical axis represents the maximum power that can be regenerated. Vehicle controller 5
, Such a map is held, the remaining battery capacity is obtained from the detection signal from the battery state detection unit 14, and the obtained remaining power is applied to this map to determine the maximum regenerable battery power at that time. . For example, the point on the graph when the remaining battery capacity is B ₁ % is K ₁ , and the maximum regenerable battery power corresponding to that point K ₁ is determined as P _BM . It should be noted that this map does not always use the same map. If a map corresponding to the battery temperature or the state of deterioration of the battery is used, a more appropriate maximum regenerable battery power is obtained. Battery life can be extended.

Step 4: The regenerative power (excess power) that cannot be regenerated by the battery 13 is calculated. This is calculated by subtracting the maximum regenerable battery power shown in FIG. 3 from the regenerative power detected by the motor inverter detector 16. Step 5: The generator inverter 12 is controlled so that the generator 10 is operated by the motor with the calculated excess power. In that case, the fuel supply to the engine 7 is reduced or stopped (improved fuel efficiency). Step 6: engine rpm engine speed coming detected from sensor 8 checks whether became first greater than the predetermined rotational speed N _1. If still greater than N _1, the process proceeds to step 2, and keeps the exhaust valve 20 is opened.

[0027] Step 7: If the engine speed becomes larger than N _1, it is greater than the second predetermined rotational speed N ₂
Check to see if it has become larger. The when the engine speed is not greater than N ₂ at Step 8 ... Step 7, but it comes to the rotational speed between the N ₁ to N _2, case according to the engine speed, opening of the exhaust valve 20 Adjust the degree (squeeze). Thereby, the power consumption in the generator 10 changes smoothly according to the engine speed.

[0028] Step 9: If the engine speed becomes larger than N ₂ come to increase (YES in step 7) to close the exhaust valve 20. When closed, the load torque further increases and the power (power consumption) required to rotate the engine further increases as described with reference to FIGS. In other words, more regenerative power can be consumed than in the past, so that a larger braking force than in the past can be secured by regenerative braking. The engine may be a gasoline engine or a diesel engine. However, in the case of a gasoline engine, when closing the exhaust valve, the throttle valve is fully opened in order to prevent the load from decreasing.

[0029]

As described above, according to the regenerative power consumption control device for a series hybrid vehicle of the present invention, when the regenerative power is large, the exhaust valve provided in the exhaust pipe of the engine is controlled to the first predetermined rotational speed. The exhaust valve is gradually reduced in accordance with the engine speed, and is controlled so as to close in a range larger than the second predetermined speed. Therefore, no exhaust valve is provided in the generator that is operating the motor to rotate the engine. More regenerative power can be consumed compared to the conventional case. Therefore, a larger braking force can be obtained at the time of regenerative braking than before. In addition, since the exhaust valve is controlled so as to be gradually reduced, the change in the engine load torque, the power consumption of the generator, the engine speed, and the like becomes smoother than in the case where the two-position control of the fully open and the fully closed is performed. In terms of feeling, the driver does not feel uncomfortable.

[Brief description of the drawings]

FIG. 1 is a diagram showing a regenerative power consumption control device for a series hybrid vehicle according to the present invention;

FIG. 2 is a flowchart illustrating regenerative power consumption control according to the present invention.

FIG. 3 is a diagram showing the maximum power that can be regenerated to a battery.

FIG. 4 is a diagram showing opening / closing control of an exhaust valve.

FIG. 5 is a diagram showing a change in load torque required when the engine is run as a rotational load.

FIG. 6 is a diagram showing a change in power consumption when a generator is driven by a motor.

FIG. 7 is a diagram showing a conventional series hybrid vehicle regenerative power consumption control device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Accelerator sensor, 2 ... Brake switch, 3 ... Shift lever, 4 ... Vehicle speed sensor, 5 ... Vehicle controller, 6
... Engine controller, 7 ... Engine, 8 ... Engine speed sensor, 9 ... Exhaust pipe, 10 ... Generator, 11 ... Generator inverter detector, 12 ... Generator inverter, 13 ...
Battery, 14: Battery state detection unit, 15: Motor inverter, 16: Motor inverter detection unit, 17: Motor, 18: Differential gear unit, 19: Wheel, 20: Exhaust valve, 21: Exhaust valve control unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B60L 11/08 F02D 9/06 D F02D 9/06 B 29/06 D 29/06 B60K 9/00 EF Terms (Reference) 3G065 AA01 AA09 AA10 BA06 CA00 DA04 EA05 GA10 GA17 3G093 AA07 AA16 AB01 BA17 CB07 DA01 DB00 EA09 EA11 EC01 FA11 5H115 PA08 PA15 PG04 PI16 PI24 PO17 PU08 PU24 PU26 PV09 QI04 QN03 RB08 TI04 TI04 SE04 TO14 TR19 TR20 TU16

Claims (1)

[Claims] 1. A vehicle driving motor that is driven by a generator during regenerative braking, a generator that is directly connected to the engine and that can be driven by the motor during regenerative braking, and a vehicle driving battery that is charged during regenerative braking. In a series hybrid vehicle regenerative power consumption control device that regenerates power by operating the generator and rotating the engine when the regenerative power from the motor exceeds the battery charging capacity, an exhaust valve is provided in an exhaust pipe of the engine. And an exhaust valve control unit for controlling the opening and closing of the exhaust valve, and an engine speed sensor. From the first predetermined rotation speed to a second predetermined rotation speed higher than the first predetermined rotation speed, the opening degree of the exhaust valve is changed according to the engine rotation speed. A regenerative power consumption control device for a series hybrid vehicle, wherein the exhaust valve is controlled to be closed when the number of rotations exceeds the second predetermined number of revolutions.