Fluid-pressure and analogous brake systems – Electric control
Reexamination Certificate
2000-01-31
2004-06-15
Burch, Melody M. (Department: 3683)
Fluid-pressure and analogous brake systems
Electric control
C303S115200
Reexamination Certificate
active
06749269
ABSTRACT:
This application is based on Japanese Patent Application No. 11-26158 filed Feb. 3, 1999, the content of which is incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrically controlled braking system including a brake control apparatus which is adapted to control a brake by controlling an electric energy supplied thereto from an electric power source.
2. Discussion of the Related Art
JP-A-5-158742 discloses an example of such an electrically controlled braking system including a brake for braking a wheel of an automotive vehicle, an electric power source, and a brake control apparatus for controlling the brake by controlling an electric energy supplied thereto from the electric power source. The brake is actuated by a pressurized working fluid, and the brake control apparatus includes a solenoid-operated valve device, and a control portion constituted principally by a computer, which is adapted to control an electric energy to be supplied to a solenoid coil of the solenoid-operated valve device so that an operation of the brake is controlled.
In the electrically controlled braking system, an electric power source switch is provided between the electric power source and the solenoid-operated valve device. This electric power source switch is turned from an OFF state to an ON state when an ignition switch of the vehicle is turned on. Therefore, this electrically controlled braking system suffers from a problem that the brake is not activated by an operation of a brake operating member while the ignition switch is off. Accordingly, the braking system is necessarily arranged such that a manually operated brake is activated while the ignition switch is in the off state. This arrangement suffers from another problem that the braking force produced by the brake changes when the ignition switch is turned on or off while the brake operating member is placed in an operated position. If the ignition switch is turned from its ON state to its OFF state while the brake operating member is placed in an operated position, the electrically controlled braking system changes from an operated state to a non-operated state, causing a change in the braking force, which may make the vehicle operator feel uneasy about the braking system. Further, the solenoid-operated valve device may be inoperable in the case of an excessive drop of the output of the single electric power source, or in the event of occurrence of any abnormality of an electric circuit connecting the solenoid-operated valve device and the electric power source.
SUMMARY OF THE INVENTION
It is therefore an object to provide an improved electrically controlled braking system.
This object may be achieved according to any one of the following modes of the present invention, each of which is numbered like the appended claims and depends from the other mode or modes, where appropriate, to indicate and clarify possible combinations of elements or technical features. It is to be understood that the present invention is not limited to the technical features or any combinations thereof which will be described for illustrative purpose only. The term “electrically controlled braking system” is interpreted to mean not only a braking system of the type described above, but also a braking system of a type wherein the brake includes an electrically operated actuator adapted to force a friction member onto a rotor so that the wheel rotating with the rotor is braked, while the brake control apparatus includes an actuator control device for controlling the electric energy to be supplied to the electrically operated actuator from the electric power source device, so as to control an operation of the brake.
(1) An electrically controlled braking system including an electrically controlled brake for braking a wheel of an automotive vehicle, an electric power source device, a brake operating member, and a brake control apparatus for controlling an electric energy to be supplied from the electric power source device to the brake, for thereby controlling an operation of the brake, when the brake operating member is operated, and wherein a switching device is disposed between the electric power source device and the brake control apparatus, the switching device being turned on for connecting the electric power source device to the brake control apparatus, in response to an operation of the brake operating member.
In the electrically braking system according to the above mode of this invention, the switching device disposed between the electric power source device and the brake control apparatus is switched from its off state to its on state when the brake operating member is operated, so that the electric power source device is electrically connected to the brake control apparatus, whereby the brake control apparatus is made operable to control the electrically controlled brake. Thus, the electrically controlled braking system does not require a manually operated brake which is adapted to be activated when the brake operating member is operated while an ignition switch provided on the vehicle is off. Further, the braking force produced by the brake will not change even when the ignition switch is turned on while the brake operating member is in operation. In other words, this arrangement prevents an undesirable change in the braking force. The switching device may be considered to be a power source switching device as distinguished from an actuator switching device and a controller switching device which will be described.
The brake control apparatus, which is provided for controlling an operation of the electrically controlled brake, may be adapted to control the amount of an electric energy to be supplied to the brake. When the amount of supply of the electric energy is zero or zeroed, the brake is at rest or de-activated. Alternatively, the brake control apparatus may be adapted to control the duty cycle of an electric actuator (e.g., electric motor) for operating the brake, namely, to alternately turn on and off the electric actuator so as to control a ratio of an ON period during which a predetermined amount of electric energy is supplied to the actuator, to an entire cycle time which is a sum of the ON period and an OFF period during which the electric energy is not supplied to the actuator.
(2) An electrically controlled braking system according to the above mode (1), wherein the electrically controlled brake includes a rotor rotating with the wheel, a friction member, and an electric motor for forcing the friction member onto the rotor, and the brake control apparatus includes a motor control device for controlling the electric energy to be supplied from the electric power source device to the electric motor.
In the braking system according to the above mode (2), which is a preferred form of the invention, an electrically operated actuator in the form of an electric motor is controlled by the brake control apparatus. Therefore, the present braking system is considered to be an electrically operated electrically controlled braking system. Where the electrically controlled brake includes a hydraulically operated actuator rather than an electrically operated actuator, it is comparatively easy to activate a manually operated brake in the event of an electrical failure of the electrically controlled braking system, or to selectively activate the manually operated brake or the electrically controlled brake. Where the electrically controlled braking system is an electrically operated braking system including an electrically operated actuator, it is comparatively difficult to activate the manually operated brake in the event of an electrical failure of the braking system, or selectively activate the manually operated brake or the electrically controlled brake. In this respect, the switching device provided according to the principle of this invention is particularly effective in the electrically operated braking system.
(3) An electrically controlled braking system according to the
Burch Melody M.
Toyota Jidosha & Kabushiki Kaisha
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