Fluid-pressure and analogous brake systems – Speed-controlled – Odd condition or device detection
Reexamination Certificate
1999-08-03
2001-07-17
Oberleitner, Robert J. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Odd condition or device detection
C303S009690, C303S022800
Reexamination Certificate
active
06260934
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a brake control system and method, in particular, to a brake control system and method for preventing a vehicle from rolling downward when starting on a slope and for providing driving stability by automatically controlling brake force when parking and stopping.
(b) Description of the Related Art
A brake system is an important safety system used to bring a vehicle to a safe controlled stop and maintain the vehicle in a stationary state. Accordingly, the brake system requires durable braking ability considering the top speed and weight of the vehicle and the brake system itself must not obstruct the rotation of wheels when it is not operating.
Brake systems are classified into mechanical brakes, hydraulic brakes, servo brakes, and air brakes according to their operating method. Among them, the air brake systems are widely used for heavy-duty vehicles such as trucks and trailers because the air brakes can obtain high brake forces using relatively low control pressure.
However, the air brake systems cannot still satisfactorily operate for the heavy-duty vehicle especially when the vehicle restarts after stopping on a slope. That is, the heavy-duty vehicle may roll downward due to the weight of the vehicle and its load when starting on the slope. To avoid the vehicle's rolling downward on the slope, drivers should push the acceleration pedal to increase engine torque. This kind of operation leads to an incomplete combustion of fuel, a decreased air/fuel ratio, and noise creation.
Therefore, a slope start auxiliary device preventing a vehicle from rolling downward on a slope has been used. Japanese Laid-Open Patent No. 95-48017 discloses a slope start auxiliary device using a 5-way control valve for maintaining front and rear wheels in a locked state. However, the 5-way control valve makes the operation of device very complex. In addition, if the control valve breaks down, brake service is not available and it is impossible to use the slope start auxiliary device.
SUMMARY OF THE INVENTION
The present invention has been made in an effort to solve the above problems of the prior art.
It is an object of the present invention to provide a brake control system which can control the release time of the brake force in consideration with the gradient degree of a slope and the load and vehicle weight when the vehicle starts on the slope, so as to prevent the vehicle from rolling downward on the slope.
It is another object of the present invention to provide a brake control system which can provide driving convenience on congested roads where stops and restarts are frequently repeated by automatic control of an auxiliary parking device without the driver's operation.
It is another object of the present invention to provide a brake control system in which a plurality of solenoid valves are used such that even though a solenoid valve is out of service, the auxiliary slope start and auxiliary-parking function can still be performed, resulting in driving safety and reliability.
Also, it is another object of the present invention to provide a brake control system which can reduce the manufacturing cost by using easily obtainable, inexpensive solenoid valves.
To achieve the above objects, the brake control system is provided with a switching signal detector for detecting signals from various switching points of the vehicle; a sensor data detector for detecting data on vehicle condition from various sensors provided in the vehicle; a gradient detector for detecting a degree of the road gradient; a load sensor for sensing a weight loaded on the road by the vehicle; a main control unit for collecting the information from all the above detecting devices, analyzing data through predetermined algorithms, and performing an overall operation of slope start control and auxiliary parking control functions; an interface part for performing an upgrade of programs and serial communication of self-analyzing data by contacting I/O devices; a plurality of solenoid valves executing the slope start control and auxiliary parking control by being adjusted according to signals from the main control unit; an indicator for indicating the operating state of the slope start control and auxiliary parking control by lighting an affected lamp according to the signals from the main control unit; and an alarm generator for generating a predetermined alarm when the vehicle rolls backward on a slope or when normal brake force is not generated in parking according to signals from the main control unit.
Also, to achieve the above objects, a full air type brake system comprising a wheel speed sensor for sensing wheel rotational speed of a front and a rear wheels of the vehicle, an ABS control unit for controlling anti-lock and anti-slip brake systems on the basis of data detected by the wheel speed sensor, and a modulator for adjusting the air pressure providing to air chambers according to signal from the ABS control unit, in accordance with the present invention are provided with a slope start control unit for integrally controlling an auxiliary slope starting and auxiliary parking functions on the basis of data of the overall vehicle conditions; a first and a second solenoid valves connected to the output of dual brake cylinder for performing the slope start function by adjusting the air pressure supplying to a release valve and a main relay valve, the solenoid valves being adjusted according to a control signal from the slope start control unit; and a third solenoid valve placed between the air tanks and the main relay valve for performing the auxiliary parking function by adjusting a post-front wheel side relay valve and a post-rear wheel side main relay valve, the third solenoid valve's duty being adjusted according to a control signal from the slope start control unit.
Also, to achieve the above objects, an air-over-hydraulic brake system comprising a speed sensor for sensing wheel rotational speed of a front and a rear wheels, a plurality of master cylinders for generating hydraulic pressure by using applied air pressure, an ABS control unit for outputing an anti-lock control signal on the basis of data detected by the speed sensor in case when the brake force is generated by the dual brake cylinder, and modulators for performing brake operation according to anti-lock control signals from the ABS control unit, in accordance with the present invention are provided with a slope start control unit for integrally controlling an auxiliary slope start and auxiliary parking functions on the basis of the data of the overall vehicle conditions; a first and second solenoid valves placed between the output of a dual brake cylinders and a relay valve for adjusting air pressure of modulators, the valves being adjusted according to the control signal from the slope start control unit; and a third solenoid valve connected between the air tanks and output side of the relay valve for adjusting the amount of air supplying according to a control signal from the slope start control unit.
The process for controlling brake systems according to the present invention comprises the steps of determining if conditions of a vehicle are suitable for entering a slope start control mode; determining if air pressure in air tanks are maintained over a predetermined pressure after entering the slope start control mode, when it has been determined that the conditions of the vehicle were suitable for the slope start control mode; maintaining brake force by controlling of solenoid valves without brake pedal operation, when it has been determined that the air pressure in the air tanks were maintained over the predetermined pressure; determining if conditions of doors and transmission gear position, clutch stroke, and acceleration pedal operation are suitable for the vehicle's start, while maintaining the brake force without brake pedal operation; determining if the degree of the gradient road is within a predetermined range for the vehicle's steady
Christie Parker & Hale LLP
Hyundai Motor Company
Kramer Devon
Oberleitner Robert J.
LandOfFree
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