Fluid-pressure and analogous brake systems – Speed-controlled – Regenerative brakes
Reexamination Certificate
2000-08-30
2002-08-27
Lavinder, Jack (Department: 3683)
Fluid-pressure and analogous brake systems
Speed-controlled
Regenerative brakes
C180S165000
Reexamination Certificate
active
06439674
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle braking apparatus and a vehicle braking method for applying a braking force to a vehicle by summing a braking force of a hydraulic braking device and a braking force of an auxiliary braking device.
Many of motor-driven vehicles, such as electric automotive vehicles and hybrid vehicles, have a regenerative braking device in addition to a hydraulic braking device to effectively utilize the limited energy. The braking force of the hydraulic braking device is referred to as “hydraulic braking force”, while the braking force of the regenerative braking device is referred to as “regenerative braking force.” This kind of motor-driven vehicles perform a cooperative control wherein the ratio of hydraulic braking force and the regenerative braking force is adequately determined to optimize the braking force applied to the vehicle as well as the storage of regenerative electric power.
FIG. 23
shows a conventional hybrid vehicle which comprises a regeneration ECU
110
sending a drive request value to each of the following electronic control units (i.e., ECUs). A motor ECU
120
controls a motor
170
via an inverter
180
based on the drive request sent from the regeneration ECU
110
. The motor
170
drives front wheels of this vehicle. A battery ECU
130
monitors a charging condition of a battery
190
equipped in this vehicle. A brake ECU
140
performs a cooperative control for the regenerative braking device and the hydraulic braking device. The brake ECU
140
sends a control signal to a cooperative control valve system
150
to control the switching of this cooperative control valve system
150
. A hydro booster system
160
generates a hydraulic braking force in response to a depression force applied on a brake pedal BP by a driver.
According to this hybrid vehicle, when the brake pedal BP is depressed by the driver, the brake ECU
140
calculates a target vehicle braking force corresponding to a depression amount of the brake pedal BP. In this case, the target vehicle braking force of this hybrid vehicle is substantially equal to a target braking force of an ordinary vehicle having a hydraulic braking device only. Then, the brake ECU
140
calculates a regenerative braking force determined in accordance with the target vehicle braking force. The regenerative braking force obtained by the brake ECU
140
is transmitted to the regeneration ECU
110
as a requested regenerative braking force. The regeneration ECU
110
causes the motor ECU
120
to perform a regenerative control based on the requested regenerative braking force. Then, the regeneration ECU
110
detects an actual regenerative braking force generated by the motor
170
. The regeneration ECU
110
returns the detected actual regenerative braking force to the brake ECU
140
as a producible regenerative braking force. In response to this, the brake ECU
140
obtains a hydraulic braking force which is obtained by subtracting the producible regenerative braking force from the target vehicle braking force. Then, the brake ECU
140
obtains a target W/C pressure corresponding to the hydraulic braking force. In this description, W/C stands for “wheel cylinder.” The brake ECU
140
controls the switching of the cooperative control valve system
150
so that a W/C pressure of each wheel is equalized to the target W/C pressure.
FIG. 24
shows a schematic arrangement of a hydraulic circuit of this hybrid vehicle. Like a general braking device, the hydro booster system
160
comprises a master cylinder (hereinafter, referred to as “M/C”)
161
generating a hydraulic pressure in accordance with a piston stroke, a hydraulic pump
163
supplying a pressurized oil, an accumulator
164
storing the pressurized oil supplied from the hydraulic pump
163
, and a regulator
162
adjusting the pressurized oil supplied from the accumulator
164
to the same pressure level as that of the M/C
161
in proportion to a depression force applied on the brake pedal BP. A reservoir
165
is provided to supply the oil to the hydraulic pump
163
.
The hydraulic pressure of the regulator
162
is transmitted to each W/C of front right, front left, rear right and rear left wheels via the cooperative control valve system
150
. The cooperative control valve system
150
comprises a linear solenoid valve SLA which increases the hydraulic pressure and a linear solenoid valve SLR which decreases the hydraulic pressure. Each of the linear solenoid valves SLA and SLR is opened or closed in response to a control signal supplied from the brake ECU
140
to adjust the pressure level of each W/C. The downstream side of the cooperative control valve system
150
is bifurcated into a front oil passage
166
supplying the oil to the front right W/C and the front left W/C of the front wheels, and a rear oil passage
167
supplying the oil to the rear right W/C and the rear left W/C of the rear wheels. The front oil passage
166
comprises a switching solenoid valve SS which is usually kept open under supply of electric power. The downstream side of the switching solenoid valve SS is bifurcated into an oil passage
168
supplying the oil to the front left W/C of the front left wheel and an oil passage
169
supplying the oil to the front right W/C of the front right wheel. Each of the bifurcated oil passages
168
and
169
has a well-known ABS solenoid valve SABS consisting of a pressure increasing valve SH and a pressure reducing valve SR. Similarly, the rear oil passage
167
has an ABS solenoid valve SABS consisting of a pressure increasing valve SH and a pressure reducing valve SR. Furthermore, the rear oil passage
167
has a P&B valve provided at the downstream side of the ABS solenoid valve SABS.
The hydraulic pressure of M/C
161
is transmitted to the P&B valve and to a stroke simulator SSI generating a pedal stroke in accordance with the depression force applied by the driver. Furthermore, M/C
161
is connected to the front left W/C via a switching solenoid valve SMC
1
and to the front right W/C via a switching solenoid valve SMC
2
. The switching solenoid valves SMC
1
and SMC
2
are usually kept closed under supply of electric power. Accordingly, the front right W/C and the front left W/C receive the regulator pressure in an ordinary condition.
According to the above-described hybrid vehicle, when the depression amount of the brake pedal BP is small, the regenerative braking force may be sufficient enough to supply all of the required vehicle braking force. In such a case, no hydraulic braking force is required. Accordingly, in the cooperative control valve system
150
, the pressure-increasing linear solenoid valve SLA is closed. The switching solenoid valves SMC
1
and SMC
2
are closed, too. However, when the depression amount of the brake pedal BP is increased, the regenerative braking force may be insufficient to supply all of the required vehicle braking force. In such a case, the hydraulic braking force is required. The linear solenoid valve SLA is opened under the condition where both of the switching solenoid valves SMC
1
and SMC
2
are closed. Thus, the regulator pressure is supplied to each W/C. However, requiring the hydraulic braking force in this manner may encounter with a system fail wherein the valve SLA is stuck in the closed position and cannot be opened. To solve this situation, the solenoid of each valve is turned off. In this case, the switching solenoid valves SMC
1
and SMC
2
are opened, and the M/C pressure is transmitted to the front right W/C and to the front left W/C. Thus, the braking force is obtained in accordance with the depression amount of the brake pedal BP.
However, according to the above-described hybrid vehicle, the cooperative control valve system
150
is provided at the downstream side of the hydro booster system
160
. Thus, in the installation of the switching solenoid valves SMC
1
and SMC
2
, it is necessary to consider the possibility that the cooperative control valve system
150
or the hydro booster system
160
may be damaged.
Denso Corporation
Lavinder Jack
Law Offices of David G. Posz
Torres Melanie
LandOfFree
Vehicle braking apparatus and vehicle braking method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Vehicle braking apparatus and vehicle braking method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vehicle braking apparatus and vehicle braking method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2975071