Fluid-pressure and analogous brake systems – Speed-controlled – Braking pressure demand or braking force desire
Reexamination Certificate
1998-06-30
2001-01-09
Graham, Matthew C. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Braking pressure demand or braking force desire
C303S115500, C303S113400
Reexamination Certificate
active
06170924
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to a brake force control apparatus, and particularly to a brake force control apparatus which is suitable for an apparatus used for controlling a brake force of a vehicle.
2. Description of the Related Art
Conventionally, as disclosed in Japanese Laid-Open Patent Application No. 4-121260, a brake force control apparatus is known which generates an increased brake fluid pressure as compared to that generated during a normal brake operation when a brake pedal is depressed at a speed exceeding a predetermined speed. A driver of a vehicle operates a brake pedal at a high speed when a rapid increase in a brake force is desired. According to the above-mentioned brake force control apparatus, when such a brake operation (hereinafter referred to as an emergency brake operation) is performed, it is possible to generate a brake force which appropriately responds to a request of the driver by generating an increased brake fluid pressure as compared to that generated during the normal brake operation.
The control for generating the increased brake fluid pressure as compared to that generated during a normal brake operation (hereinafter referred to as a brake assist (BA) control) can be achieved, for example, in a system in which a master cylinder and a wheel cylinder are connected via a first solenoid valve, the master cylinder and an inlet of a pump are connected via a second solenoid valve, and an outlet of the pump and the wheel cylinder are directly connected.
According to the above-mentioned system, the master cylinder and the wheel cylinder can be connected to each other and the master cylinder and the pump can be disconnected from each other by opening the first solenoid valve and closing the second solenoid valve. In this case, it is possible to generate a wheel cylinder pressure P
W/C
which is equal to a master cylinder pressure P
M/C
. Thus, the above-mentioned system can operate as a normal brake apparatus by achieving the above-mentioned state.
Additionally, in the above-mentioned system, the master cylinder and the wheel cylinder can be disconnected from each other and brake fluid in the master cylinder can be pressurized by the pump and supplied to the wheel cylinder by closing the first solenoid valve, opening the second solenoid valve, and setting the pump in operation. In this case, it is possible to generate a wheel cylinder pressure P
W/C
which is higher than the master cylinder pressure P
M/C
.
In the above-mentioned system, the master cylinder pressure P
M/C
can be detected by, for example, providing a fluid pressure sensor in a fluid pressure passage which connects the master cylinder and the first solenoid valve. If the master cylinder pressure P
M/C
can be detected during execution of the brake assist control, it is possible to detect a brake operation performed by the driver after the brake assist control is started based on the detected value.
However, in the above-mentioned system, that is, in a system in which the brake fluid is pumped up by the pump from the master cylinder, a decrease, which is not due to a change in the amount of brake operation, is generated in the master cylinder pressure P
M/C
. Additionally, in the above-mentioned system, a pulsation which is not due to a change in the amount of brake operation (hereinafter simply referred to as a pulsation) is generated in the master cylinder pressure immediately after the pump has stopped to pump up the brake fluid.
Thus, in the above-mentioned system, a brake operation performed by the driver during execution of brake assist control cannot be accurately detected by simply detecting the master cylinder pressure P
M/C
using the fluid pressure sensor.
Further, in the above-mentioned system, there is a period in which the master cylinder pressure does not correspond to the amount of brake operation intended by the driver immediately after the pump has started pumping the brake fluid and immediately after the pump has stopped to pump up the brake fluid, as described above. Accordingly, it is necessary to prevent an erroneous detection of the brake operation during the period in which the master cylinder pressure does not correspond to the amount of brake operation, in order to accurately detect the brake operation intended by the driver in the above-mentioned system.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a brake force control apparatus comprising a pump for pumping up brake fluid from a fluid pressure passage connecting a master cylinder and wheel cylinder which can accurately detect an amount of brake operation intended by a driver during execution of the brake assist control.
It is another object of the present invention to provide a brake force control apparatus of the above-mentioned type which can prevent an erroneous detection of an amount of brake operation intended by a driver during execution of the brake assist control.
The above objects can be achieved by a brake force control apparatus comprising:
a master cylinder;
a wheel cylinder;
a fluid pressure passage connecting the master cylinder and the wheel cylinder;
a pump for pumping up brake fluid from the fluid pressure passage
a fluid pressure sensor for generating an output signal corresponding to a master cylinder pressure;
a brake assist control means for supplying the brake fluid delivered by the pump to the wheel cylinder when an emergency brake operation is performed by a driver based on the output signal; and
inhibiting means for inhibiting the output signal from being used when the master cylinder pressure fluctuates due to pumping up of the brake fluid by the pump.
The above objects can also be achieved by a brake force control apparatus which comprises a pump for pumping up brake fluid from a fluid pressure passage connecting a master cylinder and a wheel cylinder and a fluid pressure sensor for generating an output signal corresponding to a master cylinder pressure and performs a brake assist control for supplying the brake fluid delivered by the pump to the wheel cylinder when an emergency brake operation is performed by a driver, further comprising:
control signal generating means for generating a control signal to compensate a decrease generated in the output signal when the pump pumps up the brake fluid from the fluid pressure passage; and
fluid pressure control means for performing the brake assist control based on the control signal.
In the present invention, when an emergency brake operation is performed by a driver, the brake assist control is started. During execution of the brake assist control, the brake fluid pumped up by the pump is supplied to the wheel cylinder, and thereby a relatively high wheel cylinder pressure is generated. After the BA control is started, the driver increases a brake operating force when a greater brake force is required and decreases the brake operating force when a smaller brake force is required. When these brake operations are performed during execution of the BA control, a change is generated in the master cylinder pressure, that is, in the output signal of the fluid pressure, in accordance with the brake operation. Thus, the driver's intention can be detected based on the output signal of the fluid pressure sensor.
In the brake force control apparatus of the present invention, the brake fluid supplied to the wheel cylinder is pumped up by the pump from the fluid pressure passage connecting the master cylinder and the wheel cylinder. When the brake fluid is pumped up by the pump from the fluid pressure passage, the master cylinder pressure is temporarily decreased. The output signal of the fluid pressure sensor reflects the change in the master cylinder pressure which is associated with the operation of the pump, as well as the change in the master cylinder pressure which is associated with the brake operation. The control signal is generated by eliminating the influence of the operation of the pump from the output signal of the fluid pressure sensor. Thus,
Aizawa Hideyuki
Hara Masahiro
Nakanishi Nobuyasu
Shimizu Satoshi
Yamada Akiyoshi
Graham Matthew C.
Kenyon & Kenyon
Siconolfi Robert A.
Toyota Jidosha & Kabushiki Kaisha
LandOfFree
Brake force control apparatus accurately detecting an amount... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Brake force control apparatus accurately detecting an amount..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Brake force control apparatus accurately detecting an amount... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2525724