JP2004225564A - Control system of hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain a braking force change by regenerative power generation while performing the regenerative power generation according to a charging quantity SOC of a battery in braking. <P>SOLUTION: In the braking, a request for an engine brake (friction + pumping resistance) is determined from request braking force, regenerative braking force corresponding to a regenerative power generation request according to the charging quantity SOC of the battery and hydraulic braking force, and the pumping resistance of an engine is adjusted so as to coincide with a request for the engine brake. An adjustment of the pumping resistance is made by control of throttle opening in an electronic control throttle and the valve timing (a valve overlap quantity) of an intake valve. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device for a hybrid vehicle having a configuration in which a motor as a drive source performs regenerative power generation and stores recovered energy in a battery during braking of the vehicle.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a hybrid vehicle including an engine and a motor as drive sources has been known (for example, see Patent Document 1 and Non-Patent Document 1).
[0003]
The hybrid vehicle includes a battery that supplies power to a motor, and a generator that is driven by an engine and supplies charging power to the battery. When the vehicle is braked, the motor is made to perform regenerative power generation, and the recovered energy is stored in a battery.
[0004]
Also, it is known that the battery life is extended by always keeping the charge amount SOC of the battery (for example, the ratio of the residual current amount to the full charge current amount) within a specific range. When the charge amount SOC decreases, the generator is driven by the engine to charge the battery.
[0005]
[Patent Document 1]
JP-A-10-288028 [Non-Patent Document 1]
Edited by Masayuki Okazawa, "Automotive Engineering June 1997", Railway Japan Co., Ltd., June 1, 1997, p38-p52
[0006]
[Problems to be solved by the invention]
By the way, at the time of braking in a state where the charge amount SOC is not small, it is desired that the regenerative power generation of the motor is performed as much as possible to promote the battery charging. It is desired to suppress power generation to avoid overcharging of the battery.
[0007]
However, when the regenerative power generation is controlled based on the request for the SOC, there is a problem in that a change in the regenerative braking force causes an excess or deficiency in the required braking force, giving the driver an uncomfortable feeling.
[0008]
The present invention has been made in consideration of the above problems, and has as its object to provide a control device for a hybrid vehicle that can prevent a change in braking force while performing regenerative power generation in accordance with the SOC of a battery.
[0009]
[Means for Solving the Problems]
Therefore, according to the first aspect of the invention, when the vehicle is braked, the regenerative power generation amount of the motor is set according to the charge amount of the battery, and the pumping resistance of the engine is adjusted based on the regenerative power generation amount.
[0010]
According to this configuration, when the amount of charge of the battery is small and charging is required, the pumping resistance of the engine constituting the engine brake is reduced, and the reduced amount of the pumping resistance (engine brake) is distributed to the braking force by the regenerative power generation of the motor. Increase regenerative power generation.
[0011]
Conversely, when the amount of charge in the battery is large and charging is not required, instead of suppressing regenerative power generation, the pumping resistance (engine brake) of the engine is increased to avoid a change in braking force.
[0012]
Therefore, a change in the braking force can be avoided while performing regenerative power generation in accordance with the request for the amount of charge of the battery.
According to the second aspect of the present invention, the pumping resistance is adjusted by changing the valve overlap amount of the engine by controlling the valve timing.
[0013]
According to such a configuration, if the valve overlap amount is increased by, for example, retarding the valve timing of the exhaust valve and / or advancing the valve timing of the intake valve, the resistance when inhaling air and / or the air , The pumping resistance in the intake stroke and / or the exhaust stroke is reduced.
[0014]
Therefore, the pumping resistance can be easily adjusted in the engine having the variable valve timing mechanism.
According to the third aspect of the present invention, the pumping resistance is adjusted by changing the opening of the throttle valve by the actuator.
[0015]
According to such a configuration, for example, by increasing the opening of the throttle valve, the resistance at the time of inhaling air decreases, and accordingly, the pumping resistance in the intake stroke decreases.
[0016]
Therefore, the pumping resistance can be easily adjusted in an engine having an electronically controlled throttle that opens and closes the throttle valve with the actuator.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a system schematic diagram of a hybrid vehicle according to the present embodiment.
[0018]
In FIG. 1, the driving force of a spark ignition gasoline engine 1 is divided by a power split mechanism 2 into a driving force of driving wheels 3 and a driving force of a generator 4.
As the power split mechanism 2, a planetary gear device as shown in FIG. 2 is used, and the power of the engine 1 is transmitted to a directly connected planetary carrier, and is distributed to a ring gear and a sun gear through a pinion gear.
[0019]
The rotating shaft of the ring gear is directly connected to the motor 5, and the driving force is transmitted to the driving wheels 3 through the speed reducer 8, while the rotating shaft of the sun gear is directly connected to the generator 4.
[0020]
That is, the power of the engine 1 is input to the power split mechanism 2 which is directly connected, one of the output shafts of the power split mechanism 2 is connected to the motor 5 and the drive wheels 3, and the other is connected to the generator 4. .
[0021]
In the power split device 2, the rotation speed of the engine 1 (carrier) can be changed by controlling the rotation of the generator 4 (sun gear) by the inverter 6 (see FIG. 3).
[0022]
At the same time, a part of the engine output is transmitted to the motor 5 via the generator 4 and converted into the driving force of the vehicle, thereby having a function as a continuously variable transmission.
[0023]
The electric power generated by the generator 4 is directly used for driving the motor 5, is converted into direct current by the inverter 6, and is stored in the battery 7.
In such a configuration, the control unit 9 including the microcomputer controls the engine 1, the generator 4, and the motor 5 as described below.
[0024]
First, when the vehicle is stopped, the engine 1, the generator 4, and the motor 5 are both stopped (see FIG. 3A), and the fuel supply to the engine 1 is stopped when the engine 1 is started at a low efficiency or at a light load. And run only with the motor 5.
[0025]
The fuel supply of the engine 1 is started after the start (see FIG. 3B), and the engine 1 is mainly driven by the output of the engine 1 during steady running.
Therefore, during steady running, power generation by the generator 4 becomes almost unnecessary (see FIG. 3C).
[0026]
When accelerating from steady running, the engine 1 is rotated at a higher speed, the generator 4 is caused to generate power, and the motor driving force is added to the direct driving force of the engine 1 to accelerate (see FIG. 3D).
[0027]
At the time of braking (at the time of engine braking and at the time of foot braking), the driving wheel 3 drives the motor 5 so that the motor 5 functions as a generator and regenerative power generation is performed. The regenerated energy is stored in the battery 7. .
[0028]
As shown in FIG. 1, a hydraulic pressure adjusting unit 11 controlled by the control unit 9 is provided downstream of a brake hydraulic pressure source 10 that generates a brake hydraulic pressure by operating a brake pedal. The deceleration of the vehicle is adjusted by regenerative braking by hydraulic pressure and regenerative power generation, and further by pumping resistance and friction of the engine 1.
[0029]
FIG. 4 is a system configuration diagram of the engine 1.
An electronic control throttle 104 (ETC) for opening and closing a throttle valve 103b by a throttle motor 103a (actuator) is interposed in an intake pipe 102 of the engine 1. A combustion chamber is provided through the electronic control throttle 104 and the intake valve 105. Air is sucked into 106.
[0030]
The combustion exhaust gas is exhausted from the combustion chamber 106 via an exhaust valve 107, purified by a front catalyst 108 and a rear catalyst 109, and then released into the atmosphere.
The intake valve 105 and the exhaust valve 107 are opened and closed by cams provided on the exhaust camshaft 110 and the intake camshaft 134, respectively. The intake camshaft 134 has a variable valve timing mechanism 113 (VTC). Is provided.
[0031]
The variable valve timing mechanism 113 is a known mechanism that changes the valve phase of the intake valve 105 by changing the rotation phase of the intake camshaft 134 with respect to the crankshaft 120.
[0032]
In the present embodiment, the variable valve timing mechanism 113 is provided only on the intake side. However, the variable valve timing mechanism 113 may be provided on the exhaust side instead of the intake side or together with the intake side. .
[0033]
In addition, an electromagnetic fuel injection valve 131 is provided at the intake port 130 of each cylinder. When the fuel injection valve 131 is driven to open by an injection pulse signal, the fuel adjusted to a predetermined pressure is supplied to the intake valve 131 by an intake valve. Inject toward 105.
[0034]
The control unit 9 also has a function of controlling the electronic control throttle 104, the variable valve timing mechanism 113, and the fuel injection valve 131.
Detection signals from various sensors are input to the control unit 9.
[0035]
The various sensors include an air flow meter 115 that detects an intake air amount Q of the engine 1, an accelerator opening sensor APS116 that detects an accelerator opening, a crank angle sensor 117 that detects an angle of a crankshaft 120, and an opening of a throttle valve 103b. A throttle sensor 118 for detecting the degree TVO, a vehicle speed sensor 119 for detecting the vehicle speed, and the like are provided.
[0036]
Then, when the driver steps on the accelerator pedal, the control unit 9 opens the electronic control throttle 104 according to the amount of depression, and at the same time, controls the engine speed by controlling the rotation speed of the generator 4.
[0037]
At this time, the ratio of distributing the engine power to the portion for directly driving the drive wheels 3 and the portion for driving the motor is also controlled, and the direct drive force of the engine 1 and the drive force of the motor 5 are combined to obtain the overall drive force. I do.
[0038]
Here, the control during regeneration by the control unit 9 will be described in detail with reference to the flowchart of FIG.
First, in step S1, it is determined whether or not the vehicle is decelerating (at the time of braking) in which the driver steps on the brake pedal while releasing his / her foot from the accelerator. If the driver is decelerating, the process proceeds to step S2.
[0039]
In step S2, a required braking force (required deceleration) is obtained.
Here, for example, the stepping pressure (stepping allowance) of the brake pedal by the driver is detected, and the required braking force (requested deceleration) is set from the stepping pressure.
[0040]
In the next step S3, a required value of the regenerative power generation amount is calculated based on the state of charge SOC obtained from the time integration of the charge / discharge current of the battery 7.
Here, if the state of charge SOC is saturated and regeneration to the battery 7 cannot be performed, the required value of the regenerative power generation amount is set to 0, and the smaller the charge amount SOC, the larger the required value of the regenerative power generation amount. Set.
[0041]
In step S4, a hydraulic braking force is obtained from the hydraulic pressure at the outlet of the hydraulic pressure adjustment unit 11.
In step S5, the engine brake generated by the friction and the pumping resistance of the engine 1 is obtained from the required braking force, the regenerative braking force corresponding to the required value of the regenerative power generation amount, and the hydraulic braking force as follows.
[0042]
Engine brake = requested braking force-regenerative braking force-hydraulic braking force Then, in step S6, a pumping resistance for the engine brake is determined at the engine speed (rpm) at that time.
[0043]
That is, the engine braking is determined by adding an adjustable pumping resistance to the friction that increases with an increase in the engine speed (rpm). Therefore, the engine speed is changed from the engine brake to the current engine speed (rpm). The value obtained by subtracting the corresponding friction is used as the target pumping resistance.
[0044]
In steps S7 and S8, the throttle opening of the electronically controlled throttle 104 (ETC) and the valve of the intake valve 105 are set so that the pumping resistance of the engine 1 during braking when the fuel supply is stopped is kept at the target pumping resistance. Controls the timing (valve overlap amount).
[0045]
Here, the pumping resistance decreases as the throttle opening increases, and the pumping resistance decreases as the valve timing of the intake valve 105 is advanced to increase the valve overlap amount.
[0046]
When the variable valve timing mechanism 113 is provided only on the exhaust side, the valve timing of the exhaust valve 107 is retarded to increase the valve overlap amount, and the variable valve timing mechanism is provided on both the intake side and the exhaust side. When the timing mechanism 113 is provided, the valve overlap amount may be increased by advancing the valve timing of the intake valve 105 and retarding the valve timing of the exhaust valve 107.
[0047]
As described above, if the pumping resistance of the engine 1 is adjusted according to the request for regenerative power generation based on the state of charge SOC and the decrease in the pumping resistance (engine brake) is allocated to the braking force by regenerative power generation, It is possible to prevent the braking force from being excessive or deficient with respect to the request while performing the regenerative power generation according to.
[0048]
The adjustment of the pumping resistance is not limited to the configuration performed by the throttle opening and the valve overlap amount, but can be adjusted by only one of the throttle opening and the valve overlap amount. It can also be adjusted by adjusting the opening area of the throttle bypass passage.
[0049]
Further, the pumping resistance can be reduced by increasing the opening area of the intake / exhaust valve.
Here, technical ideas other than the claims that can be grasped from the above embodiment will be described below together with their effects.
(A) In the control device for a hybrid vehicle according to claim 1,
The engine includes a variable valve timing mechanism that varies a valve timing of an engine valve, and a throttle valve of the engine is configured to be opened and closed by an actuator,
A control device for a hybrid vehicle, wherein a valve overlap amount is controlled by controlling a valve timing, and a pumping resistance is adjusted by controlling an opening degree of the throttle valve by the actuator.
[0050]
According to such a configuration, for example, by maximizing the valve overlap amount and the throttle opening, it is possible to minimize the pumping resistance in an engine including the variable valve timing mechanism and the throttle actuator.
[0051]
Accordingly, a large adjustment amount of the pumping resistance can be secured, and the pumping resistance can be largely changed in response to a change in the regeneration request.
(B) In the control device for a hybrid vehicle according to any one of claims 1 to 3,
The target of the engine brake was calculated from the required braking force, the regenerative braking force and the hydraulic braking force corresponding to the required value of the regenerative power generation amount, and the friction corresponding to the engine speed at that time was subtracted from the target of the engine brake. A control device for a hybrid vehicle, characterized in that a minute is a target pumping resistance.
[0052]
According to such a configuration, the pumping resistance of the engine is adjusted by the change in the regenerative braking force so that the required braking force is obtained from the engine brake (friction + pumping resistance), the regenerative braking force, and the hydraulic braking force.
[0053]
Therefore, the required braking force can be maintained in response to the change in the regenerative braking force.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of a hybrid vehicle according to an embodiment.
FIG. 2 is a diagram showing a planetary gear device constituting the power split device according to the embodiment.
FIG. 3 is a collinear chart showing a correlation between shaft rotation speeds of planetary gears constituting a power split mechanism in the embodiment.
FIG. 4 is a system configuration diagram of an engine in the embodiment.
FIG. 5 is a flowchart illustrating regeneration control according to the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Power distribution mechanism, 3 ... Drive wheel, 4 ... Generator, 5 ... Motor, 6 ... Inverter, 7 ... Battery, 8 ... Reduction gear, 9 ... Control unit, 103a ... Throttle motor (actuator), 103b ... Throttle valve, 104 ... Electronic control throttle, 105 ... Intake valve, 107 ... Exhaust valve, 113 ... Variable valve timing mechanism

Claims (3)

A control device for a hybrid vehicle, comprising: an engine and a motor as drive sources; and a battery for supplying power to the motor, wherein the motor performs regenerative power generation during braking of the vehicle and stores recovered energy in the battery. At
A control apparatus for a hybrid vehicle, wherein a regenerative power generation amount of the motor is set according to a charge amount of the battery when the vehicle is braked, and a pumping resistance of the engine is adjusted based on the regenerative power amount. 2. The pump according to claim 1, wherein the engine includes a variable valve timing mechanism that varies a valve timing of an engine valve, and adjusts a pumping resistance by changing a valve overlap amount by controlling the valve timing. Control device for hybrid vehicle. 3. The hybrid vehicle control device according to claim 1, wherein a throttle valve of the engine is driven to open and close by an actuator, and a pumping resistance is adjusted by changing an opening of the throttle valve. .

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