JP2005039908A - Regenerative braking control unit of hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a regenerative braking control unit of a hybrid vehicle provided with a constant speed travel control function and a following distance control function, capable of utilizing a regenerative braking without applying a load on a motor nor making a crew feel uncomfortable during constant speed travel control or following distance control. <P>SOLUTION: When a regenerative braking from a driving motor (10) is utilized during deceleration in constant speed travel control or following distance control, the regenerative braking force is provided with an upper limit value for the constant travel control and that for the following distance control which is higher than the upper limit value for constant speed travel control. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a regenerative braking control device for a hybrid vehicle, and more particularly to a regenerative braking technology for a hybrid vehicle having a constant speed traveling control function and an inter-vehicle distance control function.
[0002]
[Prior art]
2. Description of the Related Art In recent years, hybrid vehicles (series type or parallel type) that are equipped with an electric motor as a driving power source of a vehicle and that can travel by combining the output of the electric motor and the output of the internal combustion engine have been developed and are publicly known. .
In such a hybrid vehicle, at the time of braking of the vehicle, so-called regenerative braking is performed in which the electric motor is operated by the power from the drive wheels to generate a braking force, while the electric power generated by the electric motor is used as regenerative energy. Is possible.
[0003]
In addition, recently, automatic braking has been applied to a vehicle having a constant speed traveling control function for traveling while maintaining a constant vehicle speed and an inter-vehicle distance control function for traveling while maintaining a constant distance from the preceding vehicle, that is, a cruise control function. A technique to perform (automatic brake system) has been developed (see Patent Document 1), and it is considered to use the regenerative braking in a hybrid vehicle having the cruise control function (see Patent Document 2).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 9-323628 [Patent Document 2]
Japanese Patent Laid-Open No. 2001-191814
[Problems to be solved by the invention]
By the way, when carrying out automatic braking by regenerative braking of an electric motor in a hybrid vehicle having a cruise control function, while it is possible to achieve energy-efficient traveling, if the deceleration due to regenerative braking is too large during constant speed traveling control There is a problem that an unpleasant deceleration feeling like sudden braking is given to a vehicle occupant. Also, during inter-vehicle distance control, a relatively large deceleration is often required to perform regenerative braking of the host vehicle in accordance with the braking condition of the preceding vehicle, which places a heavy burden on the electric motor and causes burnout of the electric motor. There is a problem that there is a high possibility of being connected.
[0006]
The present invention has been made to solve such problems, and an object of the present invention is to perform constant speed traveling control or inter-vehicle distance control in a hybrid vehicle having a constant speed traveling control function and an inter-vehicle distance control function. An object of the present invention is to provide a regenerative braking control device for a hybrid vehicle that can use regenerative braking without causing discomfort to the occupant or imposing a burden on the electric motor.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, in the regenerative braking control device for a hybrid vehicle according to claim 1, the inter-vehicle distance between the driving motor, the constant speed traveling control means for controlling the vehicle so as to keep the vehicle speed constant, and the preceding vehicle. In the hybrid vehicle having the inter-vehicle distance control means for controlling the vehicle so as to keep the vehicle constant, the vehicle needs to be decelerated during the constant speed travel control by the constant speed travel control means or during the inter-vehicle distance control by the inter-vehicle distance control means. When the vehicle is decelerated according to the actual vehicle speed during the constant speed traveling control or the inter-vehicle distance during the inter-vehicle distance control, regenerative braking is performed by the driving motor to generate the braking force so as to obtain the deceleration. Regenerative braking control means, and the regenerative braking force by the drive motor is used for controlling the inter-vehicle distance greater than the upper limit value for constant speed traveling control and the upper limit value for constant speed traveling control. It is characterized in that a and limit values.
[0008]
In other words, during constant speed traveling control, even if the braking force based on the deceleration according to the actual vehicle speed is large, the regenerative braking force is clipped to the upper limit value for constant speed traveling control. Even if the braking force based on the corresponding deceleration is large, the regenerative braking force is clipped to the upper limit value for inter-vehicle distance control.
Further, in the regenerative braking control device for a hybrid vehicle according to claim 2, when the braking force necessary for vehicle deceleration according to the inter-vehicle distance during the inter-vehicle distance control exceeds the upper limit value for inter-vehicle distance control, It is characterized by warning the person.
[0009]
That is, when the braking force based on vehicle deceleration according to the inter-vehicle distance during the inter-vehicle distance control exceeds the inter-vehicle distance control upper limit value, the regenerative braking force is clipped to the inter-vehicle distance control upper limit value. The driver is warned, and the necessity of a braking operation by a service brake or the like is urged.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a regenerative braking control device for a hybrid vehicle according to the present invention will be described below with reference to the accompanying drawings.
Referring to FIG. 1, the configuration of a regenerative braking control device for a hybrid vehicle according to the present invention is shown in a block diagram, and will be described below with reference to FIG.
[0011]
The hybrid vehicle shown in FIG. 1 is a so-called parallel type, and an output shaft 2 of an engine (internal combustion engine) 1 is connected to a rotating shaft 12 of an electric motor (drive motor) 10 via a coupling device 4. The rotating shaft 12 is connected to the axle 22 via the transmission 20. The transmission 20 includes a differential gear, and a pair of wheels 24 and 24 are connected to both ends of the axle 22 as drive wheels.
[0012]
The electric motor 10 functions as both a motor and a generator, and is configured to be connected to a battery (not shown) so that a stator coil (excitation coil) surrounds a rotor coil integrated with the rotating shaft 12. Has been. That is, the electric motor 10 functions as a motor that rotates the rotating shaft 12 by, for example, energizing the stator coil to form a magnetic field and energizing the rotor coil to generate the magnetic field. The rotor coil integral with the rotating shaft 12 is rotated by an external force from the wheels 24 and 24 transmitted through the rotating shaft 12 to generate a magnetic field, thereby generating an exciting current in the rotor coil. Functions as a generator.
[0013]
When the electric motor 10 functions as a generator, the rotational energy of the rotor coil is converted into electric energy, so the rotational speed of the rotor coil is reduced by an amount corresponding to the amount of power generation. That is, when the electric motor 10 functions as a generator, it functions as a braking device at the same time as generating power. That is, if the electric motor 10 is caused to function as a generator when it is desired to brake the vehicle, vehicle braking, that is, regenerative braking can be performed while the braking energy is favorably changed to electric energy and stored in the battery.
[0014]
The axle 22 is provided with a pair of hydraulic disc brake devices (service brakes) 30 and 30 in proximity to the wheels 24 and 24. The hydraulic disc brake devices 30, 30 are connected to a brake booster 32 through an oil passage 31, and a brake pedal 34 is connected to the brake booster 32.
The electronic control unit (ECU) 40 includes a central processing unit (CPU) and the like, and is a main control device that controls various operations of the hybrid vehicle, and detects an operation state of the brake pedal 34 on its input side. In addition to the brake sensor 35, an accelerator position sensor (APS) 37 for detecting an operation amount of the accelerator pedal 36, that is, an accelerator opening θacc is connected. On the other hand, an alarm device 42 is connected to the output side of the ECU 40 in addition to the engine control unit 1a of the engine 1 and the motor control unit 10a of the electric motor 10.
[0015]
The hybrid vehicle also has a constant speed traveling control function (constant speed traveling control means) that travels while maintaining the vehicle speed V constant, and an inter-vehicle distance control function that travels while maintaining a constant distance D between the preceding vehicle and the preceding vehicle ( A distance control means), that is, a cruise control function, and an operation switch 52 of the cruise control system and a distance detector (ranging sensor, laser radar, etc.) 54 are further connected to the input side of the ECU 40. Yes.
[0016]
That is, when the operation switch 52 is turned ON, cruise control is started, and the vehicle is set to a constant speed traveling control state or an inter-vehicle distance control state.
Specifically, referring to FIG. 2, there is shown a state transition diagram during cruise control. As shown in FIG. 2, when the operation switch 52 is turned on in a normal manual state, the vehicle speed V is first set to the set vehicle speed Vs. The constant speed running control is performed and the speed control state is entered. When a preceding vehicle is detected by the inter-vehicle distance detector 54 in the speed control state, the inter-vehicle distance detector 54 detects the inter-vehicle distance D, and the inter-vehicle distance D is held at a predetermined inter-vehicle distance Ds corresponding to the vehicle speed V. As a result, the inter-vehicle distance control is performed to enter the inter-vehicle distance control state.
[0017]
On the other hand, when the preceding vehicle disappears and is not detected in the inter-vehicle distance control state, the state returns to the speed control state again. In the inter-vehicle distance control state or the speed control state, the operation switch 52 is turned off or the brake pedal 34 is operated by the brake sensor 35. When is detected, the cruise control is canceled and the manual state is restored.
Hereinafter, the operation content of the regenerative braking control device for a hybrid vehicle configured as described above will be described.
[0018]
As described above, in the hybrid vehicle, when the operation switch 52 is turned ON and the cruise control system is operating, the vehicle is in the constant speed traveling control state or the inter-vehicle distance control state. Further, the set vehicle speed Vs can be increased or decreased by operating the operation switch 52.
At this time, for example, when the operation switch 52 is operated and the set vehicle speed Vs is changed to the deceleration side, the vehicle speed V is decelerated toward the new set vehicle speed Vs. The deceleration is set according to the vehicle speed V and the newly set vehicle speed Vs, and regenerative braking by the electric motor 10 is performed (regenerative braking control means). Thereby, it is possible to satisfactorily perform braking while changing the braking energy to electric energy, and to improve the energy efficiency.
[0019]
By the way, when the vehicle is decelerated toward the new set vehicle speed Vs as described above, if the braking force is large and the deceleration is too large, the vehicle occupant feels unpleasant deceleration, which is not preferable.
Therefore, here, when decelerating toward the new set vehicle speed Vs, a constant speed running control upper limit value Fvmax is provided for the regenerative braking force, and the regenerative braking force is applied to the braking force corresponding to the deceleration. Regenerative braking is performed so as not to exceed the control upper limit value Fvmax. That is, the regenerative braking force is clipped at the constant speed traveling control upper limit value Fvmax.
[0020]
For example, when the change degree of the set vehicle speed Vs is small and the difference between the current actual vehicle speed V and the new set vehicle speed Vs is small, the deceleration is not so large, and therefore regenerative braking is performed by the regenerative braking force according to the deceleration. On the other hand, when the degree of change in the set vehicle speed Vs is large and the difference between the current actual vehicle speed V and the new set vehicle speed Vs is large, the deceleration increases, so regenerative braking is performed by the constant speed traveling control upper limit value Fvmax. Is done.
[0021]
Thus, when the set vehicle speed Vs is changed to the deceleration side during the constant speed traveling control, the vehicle is satisfactorily decelerated by the regenerative braking of the electric motor 10 without the passenger feeling uncomfortable deceleration.
In the inter-vehicle distance control state, the vehicle speed V of the host vehicle increases or decreases so as to maintain the predetermined inter-vehicle distance Ds according to the increase / decrease change of the inter-vehicle distance D with respect to the preceding vehicle. When the distance D decreases and the host vehicle approaches the preceding vehicle, the ECU 40 sets a deceleration according to the current actual inter-vehicle distance D and the predetermined inter-vehicle distance Ds. Regenerative braking is performed (regenerative braking control means). As a result, the braking can be performed satisfactorily while changing the braking energy to the electric energy as described above, and the energy efficiency can be improved.
[0022]
By the way, when the inter-vehicle distance D with the preceding vehicle is greatly reduced and the own vehicle is rapidly approaching the preceding vehicle, a large deceleration is required, and a large regenerative braking force is required accordingly. The That is, a large load is required for the electric motor 10. And if deceleration is too large, the electric motor 10 will be in an overload state and the electric motor 10 may burn out.
[0023]
Therefore, here, when the vehicle is decelerated to maintain the predetermined inter-vehicle distance Ds, an inter-vehicle distance control upper limit value Fdmax is provided for the regenerative braking force, and the regenerative braking force is used for the inter-vehicle distance control with respect to the braking force corresponding to the deceleration. Regenerative braking is performed so as not to exceed the upper limit value Fdmax. That is, the regenerative braking force is clipped at the inter-vehicle distance control upper limit value Fdmax.
That is, when the difference between the current actual inter-vehicle distance D and the predetermined inter-vehicle distance Ds is small, the deceleration is not so large, so regenerative braking is performed with the regenerative braking force corresponding to the deceleration, while the actual actual distance When the difference between the inter-vehicle distance D and the predetermined inter-vehicle distance Ds is large, the deceleration increases, so regenerative braking is performed by the inter-vehicle distance control upper limit value Fdmax.
[0024]
In the case of the above-mentioned constant speed traveling control, the purpose is to prevent an unpleasant deceleration feeling. Therefore, the constant speed traveling control upper limit value Fvmax is set to a relatively small value. The vehicle distance control upper limit value Fdmax is within the range of the regenerative braking capability of the electric motor 10 so as to perform sufficient braking because the vehicle needs to be decelerated with good response according to changes in the vehicle speed. The value is sufficiently larger than the upper limit value Fvmax.
[0025]
Thus, when the inter-vehicle distance D decreases during inter-vehicle distance control, the vehicle is satisfactorily decelerated by regenerative braking without burning the electric motor 10 without being overloaded.
By the way, when the regenerative braking force is limited to the inter-vehicle distance control upper limit value Fdmax in this way, the braking force is insufficient. Therefore, when the braking force necessary for the set deceleration exceeds the upper limit value Fdmax for inter-vehicle distance control, a warning is given to the driver by the warning device 42, and the driver is given a service brake, that is, a hydraulic disc brake. Encourage the use of the devices 30,30. Here, for example, a warning light is turned on and a warning sound is generated.
[0026]
When the warning is issued and the use of the service brake is encouraged in this way, the driver operates the brake pedal 34 to compensate for the insufficient braking force, and sufficient braking is performed by adding the service brake to the regenerative braking. Thus, the inter-vehicle distance D can be reliably maintained at the predetermined inter-vehicle distance Ds during the inter-vehicle distance control.
This is the end of the description of the embodiment of the regenerative braking control device for a hybrid vehicle according to the present invention, but the embodiment is not limited to the above embodiment.
[0027]
For example, in the above embodiment, the case where the hybrid vehicle is a parallel type has been described, but the present invention is also applicable to a series type hybrid vehicle.
[0028]
【The invention's effect】
As described above in detail, according to the regenerative braking control device for a hybrid vehicle of claim 1 of the present invention, the regenerative braking force is clipped at a relatively small constant speed traveling control upper limit value during constant speed traveling control. This prevents the vehicle occupant from feeling uncomfortable deceleration and clips the regenerative braking force during the inter-vehicle distance control with a relatively large inter-vehicle distance control upper limit value that is larger than the upper limit value for constant speed traveling control. As a result, the load on the electric motor can be reduced, overload can be prevented, and burning of the electric motor can be prevented.
[0029]
Further, according to the regenerative braking control device for a hybrid vehicle of claim 2, when the regenerative braking force is clipped at the upper limit value for inter-vehicle distance control, the driver is prompted to perform a braking operation by a service brake or the like. Therefore, the insufficient braking force can be compensated for by the driver's braking operation, and the inter-vehicle distance can be reliably maintained during inter-vehicle distance control.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a regenerative braking control device for a hybrid vehicle according to the present invention.
FIG. 2 is a state transition diagram of cruise control.
[Explanation of symbols]
1 engine (internal combustion engine)
10 Electric motor (drive motor)
24 Wheel 30 Hydraulic disc brake device (Service brake)
34 Brake pedal 40 Electronic control unit (ECU)
42 warning device 52 operation switch 54 inter-vehicle distance detector

Claims (2)

In a hybrid vehicle having a drive motor, a constant speed travel control means for controlling the vehicle so as to keep the vehicle speed constant, and an inter-vehicle distance control means for controlling the vehicle so as to keep the inter-vehicle distance from the preceding vehicle constant.
When the vehicle needs to be decelerated during constant-speed traveling control by the constant-speed traveling control means or during inter-vehicle distance control by the inter-vehicle distance control means, the actual vehicle speed during the constant-speed traveling control or the inter-vehicle distance during the inter-vehicle distance control Regenerative braking control means for obtaining a deceleration of the vehicle according to the above and generating a braking force by performing a regenerative braking by the driving motor so as to obtain the deceleration,
The regenerative braking of a hybrid vehicle, wherein the regenerative braking force by the driving motor is provided with the upper limit value for constant speed traveling control and the upper limit value for inter-vehicle distance control that is larger than the upper limit value for constant speed traveling control. Control device. The vehicle driver is warned when a braking force necessary for vehicle deceleration according to the inter-vehicle distance control during the inter-vehicle distance control exceeds the upper limit value for inter-vehicle distance control. Regenerative braking control device for hybrid vehicles.

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