JPH099415A - Hybrid vehicle - Google Patents

Abstract

(57) [Abstract] [Purpose] In a hybrid vehicle, reduce engine braking during braking to increase regenerative power, and effectively complement the engine with a motor under high load to reduce engine size and improve fuel efficiency. Plan. [Structure] During braking, if the engine speed is high, the engine brake acts greatly, and the regenerative electric power obtained by regenerative braking is correspondingly reduced. Therefore, at the time of braking, the shift point is moved to the low speed side to lower the rotation speed of the entire engine. As a result, the regenerative power increases, and the power reserve for the power source increases. In contrast to the conventional shift point of FIG. 5A, in FIG. 5B, the shift point of 3 → 2 during deceleration is moved to the low speed side, and the shift point of 2 → 1 is eliminated.

Description

Detailed Description of the Invention

The present invention relates to a hybrid vehicle having an engine and a motor as a direct drive source for an output shaft.

[0002]

2. Description of the Related Art In vehicles such as automobiles, a so-called parallel type hybrid vehicle is known in which an engine and a motor are mounted as a drive source for rotationally driving an output shaft.

This is different from the case where a series type hybrid vehicle uses an engine exclusively for power generation and rotationally drives a motor as a drive source by the electric power obtained thereby, and both the engine and the motor are drive sources. Are connected to the output shaft, and these are appropriately used according to the running condition of the vehicle. For example, in a city area, a motor is used to eliminate exhaust gas emissions, and in the suburbs, an engine is used to extend the cruising range. further,
If the driving force of the engine is insufficient during high-load traveling such as climbing up a mountain or high loading, the motor compensates for the insufficient driving force. As described above, since the motor can compensate for the insufficient driving force due to only the engine, the engine itself can be downsized. And because there are more opportunities to travel using the high efficiency area of the miniaturized engine,
It is possible to realize low fuel consumption of the engine.

Among the above-mentioned hybrid vehicles, those that perform regenerative braking are known. The above-mentioned motor is used as a generator when braking the vehicle body during traveling. During braking, the motor as a generator is rotated by the output shaft, which causes regenerative power to be generated in the motor. This regenerated electric power is returned to the power source (for example, battery) of the motor. A part of the kinetic energy of the vehicle body is effectively stored in the power source as regenerative power.

[0005]

However, according to the above-described hybrid vehicle, the engine is connected to the output shaft in addition to the motor. Therefore, the rotation of the output shaft during braking is not limited to the motor. Is also transmitted. Therefore, there was a problem that the energy that the vehicle had was partly lost due to the engine braking, and the regenerated electric power that was effectively recovered decreased by that amount.

Therefore, an object of the present invention is to provide a hybrid vehicle in which the energy lost by engine braking during braking is reduced and the regenerative power is increased accordingly.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and includes an engine and a motor, transmits at least one power to an output shaft, and the engine and the output shaft. In a hybrid vehicle that shifts through a multi-stage automatic transmission arranged between
While supplying electric power to the motor, a power source that receives regenerative electric power from the motor as a generator is provided, and at the time of regenerative braking of the vehicle body, a shift point that determines a shift stage of the multi-stage automatic transmission is set to a high speed. It is characterized in that it is moved in a direction in which the step region is expanded.

Next, a hybrid which includes an engine and a motor, transmits at least one power to an output shaft, and shifts through a continuously variable automatic transmission arranged between the engine and the output shaft. In the vehicle, a power source is provided for supplying electric power to the motor while receiving regenerative electric power from the motor as a generator, and the gear ratio is improved during regenerative braking of the vehicle body (when the drive shaft is driven to rotate). The feature is that it is set small.

When the above-described multi-stage automatic transmission or continuously variable automatic transmission has a torque converter with a lock-up mechanism, it is preferable to release the lock-up mechanism during regenerative braking of the vehicle body.

[0010]

In the hybrid vehicle described above, the output shafts of the engine and the motor are common, based on the above configuration. Therefore, for example, the rotation of the output shaft during braking is transmitted to the engine and the motor. The rotation of the output shaft transmitted to the motor rotates the motor to generate regenerative electric power. This regenerated power is returned to the power source and is effectively stored. On the other hand, of the rotation of the output shaft, that transmitted to the engine is lost as engine braking. That is, part of the kinetic energy that the vehicle body has during braking is effectively stored in the power source as regenerative power, and partly lost by engine braking. In addition, the kinetic energy may be consumed by frictional heat of the foot brake or internal resistance of the moving part. However, in the following description, description thereof will be omitted, and regenerative power and engine brake will be mainly used. Let us focus on and. That is, the description will be made assuming that when the energy consumed by the engine brake is large, the regenerative electric power is reduced accordingly.

By the way, the engine brake is generally
The higher the engine speed, the larger. Therefore,
For example, in the case where the automatic transmission has a plurality of shift speeds, when the rotation of the output shaft during braking is the same, the lower the shift speed of the automatic transmission, the higher the engine speed, and the larger the engine brake operates. Much energy is consumed by large engine brakes.

Therefore, at the time of braking, the shift point that determines the shift speed of the multi-speed automatic transmission is moved in a direction in which the high speed range is expanded. This lowers the engine speed and reduces the energy consumed by the engine brake. As a result, the regenerative power is increased by that amount, and the power stored in the power source is increased. That is, it is possible to reduce the consumed portion of the kinetic energy of the vehicle at the time of braking, and increase the amount of energy to be stored for that portion.

When the automatic transmission is a continuously variable automatic transmission,
By setting the gear ratio at the time of braking to be low, it is possible to obtain substantially the same operation as in the case of the above-described multi-stage automatic transmission.

When the above-mentioned multi-stage automatic transmission or continuously variable automatic transmission is provided with a lockup mechanism, the resistance due to engine braking becomes larger when the lockup mechanism is operating. Therefore, by releasing the lockup mechanism, the resistance of the engine can be reduced, and the regenerative electric power is correspondingly increased.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. <Embodiment 1> FIG. 1 shows a schematic configuration of a drive system of a hybrid vehicle according to the present invention. In the following description, a hybrid vehicle according to the present invention will be described as an example in which an automatic transmission with three forward gears is mounted, but the present invention is not limited to this.
The present invention can be applied to a step-gear, a 5-gear, and even a continuously variable automatic transmission without changing the basic configuration. Further, the configuration of the entire hybrid vehicle is almost the same as that of a general vehicle equipped with a combustion engine (for example, a vehicle equipped with a gasoline engine), and therefore description thereof will be omitted.

The drive system of FIG. 1 includes an engine 1 as a drive source, an automatic transmission 2 connected to the output side thereof, a motor 3 as a drive source connected to the output side thereof, and further connected to the output side thereof. The output shaft 5 is provided. here,
In the figure, a thick solid line indicates the flow of driving force, and a thin solid line (between the motor 3 and a power supply 6 described later) indicates the flow of electric power. The above-mentioned output shaft 5 is connected to front wheels or rear wheels (neither is shown) via a differential device and a front axle or a rear axle. A battery 6 as a power source is connected to the motor 3 described above. The motor 3 is rotatably driven by the electric power from the power source 6 and applies a torque to the output shaft 5 as a so-called general motor.
Alternatively, when it is rotationally driven by the output shaft 5, it is configured to act as a so-called generator that generates regenerative power and converts the regenerative power into the battery 6.

In the figure, a clutch (not shown) may be interposed between the automatic transmission 2 and the motor 3. At this time, since the power between the automatic transmission 2 and the motor 3 can be disconnected, the output shaft 5 can be rotated by the motor 3 alone, for example, by disengaging the clutch.

The engine 1 and the motor 3 can be arranged in parallel with the same output shaft 5 in common. For example, the engine 1, the automatic transmission 2, and the output shaft 5 are connected in series, while the motor 3 is connected to the output shaft 5 via a gear or the like. At this time, the transmission of power between the motor 3 and the output shaft 5 can be cut off by removing the gear or the like from the output shaft 5 or the motor 3.

FIG. 2 shows an example in which the arrangement of the automatic transmission 2 and the motor 3 of FIG. 1 is reversed. That is, in this example, the motor 3 is first arranged on the output side of the engine 1, the automatic transmission 2 is arranged on the downstream side of the motor 3, and the output shaft 5 is arranged on the downstream side of the automatic transmission 2. Thick solid lines and thin solid lines in the figure show the same contents as in FIG. In the configuration of FIG. 2, a clutch (not shown) similar to that described above can be interposed between the engine 1 and the motor 3.

Here, comparing the above-mentioned FIG. 1 and FIG. 2 with respect to the case where the driving forces of both the engine 1 and the motor 3 are transmitted to the output shaft 5, the case of FIG. The rotation of the engine 1 is first shifted by the automatic transmission 2, and a driving force is added to the rotation after the shift by the motor 3 and output from the output shaft 5. In contrast, FIG.
In the case of 1, the driving force is first applied by the motor 3, then the speed is changed by the automatic transmission 2 and output from the output shaft 5. In addition, in the present invention, both the configurations of FIG. 1 and FIG. 2 can be adopted including the case of generating a regenerative current.

In the following, the configuration of FIG. 1 will be taken as an example for further detailed description.

FIG. 3 is a block diagram in which a control system is added to the drive system of FIG. In the figure, the thick solid line and the thin solid line respectively indicate the flow of driving force and electric power, and the dotted line indicates the flow of signals, as in FIGS. 1 and 2.

The hybrid vehicle according to the present invention includes an engine 1, a automatic transmission 2, a motor 3 as a drive system,
In addition to the output shaft 5 and the battery 6, a vehicle control device (control device) 9 is configured as a main component. And
The characteristic of the operation is that the shift point is moved to the low speed side during braking to reduce the rotation of the engine 1 as a whole, weaken the action of the engine brake, and increase the regenerative power accordingly.

The details will be described below.

An engine controller 11 is connected to the engine 1 to control the number of revolutions of the engine 1 based on a throttle opening signal 11s from the vehicle controller 9. An automatic transmission 2 is connected to the output side of the engine 1.

As the automatic transmission 2, for example, a multi-stage automatic transmission having a plurality of stages can be used. In the present embodiment, the multi-stage automatic transmission 2 having three forward gears will be described as an example.
To the multi-stage automatic transmission 2, a shift actuator 12 that is operated by a shift signal 12s from the vehicle control device 9 is connected. Based on the operation of this shift actuator 12, the shift of the multi-stage automatic transmission 2 is performed. It has become. A motor 3 is connected to the output side of the multi-stage automatic transmission 2.

The motor 3 receives the electric power from the battery 6 and is rotationally driven, and also functions as a generator. That is, when the motor 3 is rotationally driven by the engine 1 via the automatic transmission 2, the motor 3 generates regenerative power, and this regenerative power is returned to the battery 6. Further, the torque command value signal 1 from the vehicle control device 9 is sent to the motor 3.
A drive motor control device 13 for controlling the operation of the motor 3 based on 3s is connected. On the output side of the motor 3,
The output shaft 5 is connected.

The output shaft 5 is connected to left and right axles (both not shown) via a differential device or the like.

A battery state detecting device 7 for detecting the remaining power capacity of the battery 6 is connected to the battery 6. The detection result is input to the vehicle control device 9 as the battery remaining amount signal 7s.

The vehicle control device 9 further includes a vehicle speed sensor 1
5, an accelerator pedal 16 and a brake pedal 17 are connected, and a vehicle speed signal 15s, an accelerator opening signal 16s, and a brake depression amount 17s are input from each.

FIG. 4 shows the relationship between the engine speed of the engine 1 and the negative engine torque due to engine braking.
From the figure, it can be seen that the action of the engine brake increases as the rotation speed of the engine 1 increases. That is, in the present embodiment, the kinetic energy of the vehicle body during braking is partly consumed by the engine brake and partly returned to the power source as regenerative power. The greater the effect of the engine brake, that is, the higher the number of revolutions of the engine, the more energy is consumed by the engine brake, and the less the amount of energy regenerated by the regenerative electric power. Therefore, in the present embodiment, the gear stage of the automatic transmission is shifted up during braking to lower the engine speed and increase the regenerative electric power. That is, the shift point that determines the shift speed is moved in a direction in which the high-speed range is expanded to increase the regenerative power.

The state of the shift up is shown in FIG.
(B). (A) illustrates a shift point in the relationship between the vehicle speed and the accelerator opening. Solid lines 1 → 2 and 2 → 3
Indicates shift points from the first speed to the second speed and from the second speed to the third speed during acceleration. On the other hand, the dotted lines 3 → 2 and 2 → 1 show the shift points from the third speed to the second speed and from the second speed to the third speed during deceleration. (B) shows an example in which the shift point at the time of deceleration is moved to the low speed side, and the shift point from 3 to 2 is moved to the low speed side as indicated by the solid line step. Even if the vehicle speed drops during braking and reaches a vehicle speed that shifts from 3 to 2 in the past (see the dotted line in FIG. 5B), this shift is not performed, and when the vehicle speed further drops, the shift is performed. (Solid line in the figure). By doing so, the rotation of the engine 1 at the time of braking becomes low as a whole, and the portion of the kinetic energy of the vehicle body at the time of braking that is consumed by engine braking is reduced. Along with this, the amount of energy converted to regenerative power increases. It should be noted that in FIG. 5B, the shift from 2 to 1 which is performed during conventional braking is not performed.

Next, referring to the flowchart of FIG.
The operation will be described.

After the start (S1), the vehicle control device (see FIG.
By referring to (9), it is detected whether or not the brake is turned on (S2). Return (S
Proceed to 3). On the other hand, when it is turned on, FIG.
Gear shifting is performed based on (S4). At this time, engine 1
Performs fel cut, and further opens the throttle to reduce throttle loss (S5. Throttle opening θ 10
0% ). Then, the regeneration routine (S6) is entered.

As described above, the regenerative electric power at the time of regenerative braking can be increased and the energy returned to the battery 6 can be increased. This increased energy is
It can be used to rotate the output shaft 5 via the motor 3. For example, the motor 3 is rotationally driven by the battery 6 when complementing the driving force of the engine 1 during high-load traveling. At this time, the regenerative power described above is effectively used.
Therefore, the burden on the engine 1 can be reduced, and the fuel economy can be improved. In other words, when braking, the kinetic energy of the vehicle is
Although much was lost by the engine brake of the engine 1, the present invention can reduce the energy lost by the engine brake and increase the regenerative power, and this regenerative power can be effectively used for the traveling of the vehicle body thereafter. Since it can be used, it is possible to improve fuel efficiency as a whole. <Second Embodiment> FIG. 7 shows a flowchart of the second embodiment.
In the second embodiment, a case will be described in which the automatic transmission 2 according to the first embodiment described above includes a torque converter with a lockup mechanism.

In the automatic transmission 2 having the torque converter, when the lockup mechanism is operated, the engine 1
Is transmitted to the output shaft mechanically directly connected via the lockup mechanism without passing through the fluid of the torque converter. Therefore, the effect of engine braking is increased during braking.

Therefore, in order to prevent a decrease in regenerative electric power due to an increase in engine braking, the lockup mechanism is released during braking (S15, S16).

In FIG. 7, S11 to S14, and S
17, S1 to S18 in FIG. 6 of the first embodiment, respectively.
4 and S5 and S6, and thus description thereof will be omitted.

In the above-described three forward gear automatic transmission 2,
In the case where the minimum regulation of the rotation speed of the engine 1 is provided in order to favorably operate so-called auxiliary equipment such as an oil pump and a cooler, the engine 1 keeps the rotation speed equal to or higher than the rotation speed even during braking. Need to hold. But,
Without these restrictions, when only regenerative electric power is taken into consideration, it is preferable to stop at the third speed without downshifting during braking. This is because the energy consumed by the engine brake at this time is the lowest, and therefore the energy that is fed to the regenerative electric power is the highest.

Although the regenerative braking when the brake is on has been described above, the same effect can be obtained for the engine brake when the accelerator is off. That is, the deceleration energy can be effectively recovered by upshifting with the accelerator off to weaken the engine braking force and applying a force corresponding to the weakened amount to drive the motor for regeneration. This control can be achieved, for example, in (S2) in FIG. 6 by determining accelerator off instead of brake on.

Although the present invention has been described in the above-described first and second embodiments, the present invention is not limited to these.

For example, as described in the beginning of the embodiment,
It can be used as it is for an automatic transmission having four forward gears and five forward gears and a continuously variable automatic transmission.

The movement of the shift point to the low speed side to increase the regenerative electric power during braking includes the case where the shift point is eliminated. An example of this is shown in FIG.
There is one in which the shift point 2 → 1 is omitted.

Further, although the battery 6 is used as the power source in the above-described first or second embodiment, instead of this, a capacitor, a flywheel battery,
An oil (pneumatic) accumulator or the like can be used.

In the case of, a large capacity capacitor can be used. In this case, the SOC detects via the voltage on the capacitor.

In the case of, the flywheel is arranged coaxially with the flywheel motor, and the rotation of the motor is performed by the electric power generated based on the rotation of the flywheel. On the other hand, for example, the motor is rotationally driven by the engine, Regenerative power is generated and the flywheel is rotated by the flywheel motor by this power. That is,
The energy supplied to the motor and the energy returned from the motor are stored as kinetic energy of the flywheel.

In the one described above, the oil (empty) pressure pump connected to the oil (empty) accumulator causes the oil (empty) to be taken in and out of the accumulator, whereby electric power is taken in and out of the motor.

[0048]

As described above, according to the present invention,
In a hybrid vehicle having an engine and a motor, when the vehicle body is braked, the shift point of the multi-stage automatic transmission is
By moving in the direction in which the high-speed range is expanded or by reducing the gear ratio of the automatic transmission without notice, the rotation of the engine as a whole during braking is reduced, and the energy consumed by engine braking is reduced. It is possible to reduce and increase the energy that is recycled to the regenerative power. Therefore, for example, when the driving force of the engine is insufficient under high load or the like, it is possible to favorably supplement the driving force of the motor. Therefore, the engine can be downsized. Furthermore, since the high efficiency area of the miniaturized engine can be effectively used,
It is possible to improve fuel efficiency. It should be noted that the improvement of fuel efficiency is directly realized based on the fact that the regenerative electric power returned to the power source increases and the power source can effectively drive the motor to supplement the driving force of the engine. Is what you can do.

[Brief description of drawings]

FIG. 1 is a block diagram showing a drive system of a hybrid vehicle according to a first embodiment.

FIG. 2 is a block diagram showing another drive system of the hybrid vehicle of the first embodiment.

FIG. 3 is a block diagram showing a drive system and a control system of the hybrid vehicle of the first embodiment.

FIG. 4 is a diagram showing a relationship between engine speed and engine torque.

FIG. 5 is a diagram showing an example of shifting the shift point to a lower speed side in the first embodiment.

FIG. 6 is a flowchart of the first embodiment.

FIG. 7 is a flowchart of the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 engine 2 automatic transmission (multi-stage automatic transmission) 3 motor 5 output shaft 6 power supply (battery) 7 remaining amount detection means (battery state detection means) 9 control device (vehicle control device) 11 engine control device 12 speed change actuator 13 drive Motor controller 15 Vehicle speed sensor 16 Accelerator pedal 17 Brake pedal

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Claims (3)

[Claims] 1. A hybrid vehicle comprising an engine and a motor, transmitting at least one power to an output shaft, and performing a gear shift via a multi-stage automatic transmission arranged between the engine and the output shaft. A power source for receiving regenerative electric power from the motor as a generator while supplying electric power to the motor, and at the time of regenerative braking of the vehicle body, a shift point that determines a shift speed of the multi-speed automatic transmission, A hybrid vehicle, wherein the hybrid vehicle is moved in a direction in which the high-speed range is expanded. 2. A hybrid vehicle comprising an engine and a motor, transmitting at least one power to an output shaft, and shifting gears via a continuously variable automatic transmission arranged between the engine and the output shaft. A power supply for receiving regenerative electric power from the motor as a generator while supplying electric power to the motor, wherein the gear ratio is set to be smaller during regenerative braking of the vehicle body. vehicle. 3. The multi-stage automatic transmission according to claim 1 or the continuously variable automatic transmission according to claim 2 having a torque converter with a lock-up mechanism, wherein the lock-up mechanism is engaged during regenerative braking of the vehicle body. The hybrid vehicle according to claim 1, wherein the hybrid vehicle is released.