Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
2000-12-28
2002-03-05
Louis-Jacques, Jacques H. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C303S152000
Reexamination Certificate
active
06353786
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a braking device for a vehicle. In particular, this invention relates to a technique of optimizing control of a brake device in a vehicle using a load as a braking force, the load occurs when an electrical motor driving the vehicle generates electricity during braking.
BACKGROUND OF THE INVENTION
A vehicle is provided with an electrical motor for driving the vehicle which uses a battery as a power source, and is provided with a controller comprising a microcomputer for controlling the electrical motor, which controls the electrical motor so that a required drive torque is generated in response to an operational condition signal such as the stroke amount of an accelerator pedal, is known in the prior art.
In this type of vehicle, when the accelerator pedal is released, the load on the electrical motor which had been driving the drive system including the drive wheels is reversed. The electrical motor is driven by the drive system. At this time, regeneration braking control is performed to make effective use of the inertial energy of the vehicle. That is to say, generation of electricity is performed in the electrical motor by the driving force from the drive system. The generating load on the electrical motor at this time is used as a braking force and the generated electricity from the electrical motor is supplied to charge the battery. However when this type of vehicle is slowing down, the possibility exists of overcharging the battery as the braking force of the braking device and the amount of generated electricity from the electrical motor are not limited to an appropriate range for a required braking force determined in response to a brake pedal operational amount. On the other hand, Tokkai-Hei-8-308016 published by the Japanese Patent Office in 1996 discloses a control which is performed not with the regeneration amount of the electrical motor but in a generator driven by the engine in order to prevent over-supply of electricity during regenerative braking of the electrical motor in the electrical generator of a hybrid drive system.
SUMMARY OF THE INVENTION
The present invention is proposed to solve the above problem and has the object of maximizing the regenerative braking force of the electrical motor in a range of the electricity supply amount to the battery while satisfying the required braking force in response to the brake pedal operational amount. This is enabled by controlling the regenerative braking force of the electrical motor and the braking force of the braking device during braking of the vehicle.
The braking force calculation means calculates a driven-wheel braking force B
FO
in response to a braking operational amount of the driver, a driving-wheel braking force B
RO
and a driven-wheel minimum required braking force B
FM
. The required braking force calculation means calculates the required braking force BO=B
FO
+B
RO
−B
FM
based on each braking force. The first regenerative braking calculation means calculates the regenerative braking force B
M
which can be generated by the electrical motor. The second regenerative braking force calculation means calculates the regenerative braking force B
B
of the power supply equivalent input to the battery. The regenerative braking force setting means compares the values B
M
and B
B
and sets B
M
as a regenerative braking force B
M
of the electrical motor when is B
B
greater than or equal to B
M
and sets B
B
as the regenerative braking force B
M
when is B
B
smaller than B
M
. Furthermore a regenerative braking control means is provided which compares the set regenerative braking force B
M
and the required braking force B
O
and controls the electrical motor and the braking mechanism. When B
M
is greater than or equal to B
O
, a required braking force B
O
is generated only by the electrical motor, while generating the driven-wheel minimum required braking force B
FM
. When B
M
is smaller than B
O
, a regenerative braking force B
M
is generated by the electrical motor while generating the driven-wheel minimum required braking force B
FM
and the remainder of the braking force is generated by the vehicle braking mechanism in the range of the driving-wheel braking force B
RO
and the driven-wheel braking force B
FO
.
When a braking operation is performed while the vehicle is slowing down, this invention allows the calculation of the driving-wheel braking force BR
O
, the driven-wheel braking force BF
O
and the driven-wheel minimum required braking force B
FM
in response to the braking operational amount. Thus it is possible to calculate a required braking force B
O
=BF
O
+BR
O
−B
FM
. A regenerative braking force B
M
generated by the electrical motor and the regenerative braking force B
B
of the power supply equivalent input to the battery are calculated. The comparison of the values B
B
and B
M
allows a regenerative braking force B
M
of the electrical motor to be re-set as B
M
when B
B
is greater than or equal to B
M
or as B
B
when B
B
is smaller than B
M
. When B
M
is greater than or equal to B
O
, only the electrical motor generates the required braking force B
O
by control based on a comparison of the regenerated braking force B
M
and the required braking force B
O
. The driven-wheel minimum required braking force B
FM
is generated by the braking mechanism. When B
M
is smaller than B
O
, the driven-wheel minimum required braking force BF
M
is generated by the braking mechanism and the regenerative braking force B
M
is generated with the electrical motor.
The remainder is generated by the braking mechanism in the range of the driving-wheel braking force BR
O
and the driven-wheel braking force BF
O
. Thus it is possible to prevent over-supply of electricity to the battery while satisfying the braking force required by the brake operational amount. In this way, it is possible to optimize the generation of a regenerative braking force by the electrical motor in a permitted battery range. Furthermore since a braking force above the minimum required braking force acts on the driven wheel, it is possible to generate a required braking force only with the electrical motor and thus it is possible to maintain sufficient operational stability in the vehicle.
It is possible to apply various types of controllable braking mechanisms in a control device comprising a microcomputer or the like to the braking force as a vehicle braking mechanism. These types of braking mechanisms comprise a brake plunger, a pressure proportion control valve, and a pressure regulation means. The brake plunger operates a braking force on vehicle wheels based on the pressure from a pressure source for example. The pressure proportion control valve adds pressure in response to commands from a control means and/or a brake pedal operational amount of the driver. The pressure regulation means comprises a solenoid pilot operation section, a cut-off valve or the like which regulates the pressure supplied to the pressure proportion control valve in response to the brake pedal operational amount (the amount of brake pedal activation) based on commands from the regenerative braking control means. In this case, during regenerative braking, the regenerative braking control means suppresses the pressure in response to the brake pedal operational amount due to the pressure regulation means and the remainder of the regenerative braking force with respect to the required braking force is generated by the brake plunger by controlling the pressure proportion control valve.
REFERENCES:
patent: 5882093 (1999-03-01), Enomoto et al.
patent: 5951115 (1999-09-01), Sakai et al.
patent: 6024420 (2000-02-01), Yonemura et al.
patent: 6070954 (2000-06-01), Urababa et al.
patent: 05-284607 (1993-10-01), None
patent: 08-163008 (1995-06-01), None
patent: 08/308016 (1996-11-01), None
patent: 09-74605 (1997-03-01), None
patent: 09-154202 (1997-06-01), None
patent: 09-289705 (1997-11-01), None
Yamada Jun
Yamada Yoshiaki
Louis-Jacques Jacques H.
Nissan Diesel Co., Ltd.
Rabin & Berdo
LandOfFree
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