Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Reexamination Certificate
2000-12-08
2004-07-13
Butler, Douglas C. (Department: 3683)
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
C303S122040, C303S020000
Reexamination Certificate
active
06761418
ABSTRACT:
INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application No. 11-370507 filed on Dec. 27, 1999, including the specification, drawings and abstract is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to brake fluid pressure control devices including a plurality of fluid pressure control valves that control fluid pressures in a plurality of brakes.
2. Description of Related Art
Japanese Laid-Open Patent Application No. 7-277175 discloses a brake fluid pressure control device including: (1) a control device mainly composed of a computer, (2) a pump that pressurizes operating fluid by means of motive power, (3) fluid pressure control valves that operate in accordance with control signals supplied from the control device and capable of controlling fluid pressures in brakes based on a fluid pressure in the pump, (4) pump shut-off valves provided between the fluid pressure control valves and the pump and that are switched in accordance with control signals supplied from the control device between a communication state where the fluid pressure control valves communicate with the pump and a shut-off state where the fluid pressure control valves are shut off from the pump, and (5) signal lines connecting the fluid pressure control valves to the control device and signal lines connecting the pump shut-off valves to the control device.
In this brake fluid pressure control device, the fluid pressure control valves are provided on the side of front wheels and on the side of rear wheels respectively. The pump shut-off valves are provided between the front-wheel-side fluid pressure control valves and the pump, and between the rear-wheel-side fluid pressure control valves and the pump respectively. If an abnormal condition arises either on the side of the front wheels or on the side of the rear wheels, the pump shut-off valves provided on the side experiencing the abnormal condition are switched to a shut-off state in accordance with control signals from the control device. Consequently, the fluid pressure control valves are shut off from the pump, and the brakes are operated by operating fluid in a master cylinder.
However, the aforementioned publication does not disclose a fail-safe system of such a brake fluid pressure control device, for example, as a countermeasure against cases where connectors for the signal lines are disconnected or incorrectly connected (where an abnormally connected condition arises) and where electric energy cannot be supplied to the fluid pressure control valves, the pump shut-off valves and the pump.
SUMMARY OF THE INVENTION
The invention has been made in view of the aforementioned circumstances. It is an object of the invention to improve fail-safe performance during abnormal operation of an electric system and thereby enhance reliability of a brake fluid pressure control device.
In order to solve the aforementioned and/or other problems, a brake fluid pressure control device according to a first aspect of the invention includes a controller, a fluid pressure control unit that operates in accordance with a control signal supplied from the controller and having a plurality of fluid pressure control valves that control fluid pressures in a plurality of brakes for inhibiting rotations of a plurality of wheels, and a plurality of signal lines connecting the fluid pressure control valves to the controller. The signal lines are divided into a plurality of signal line groups. The signal lines of a first one of the signal line groups are connected between the controller and the fluid pressure control unit by a first connector, whereas the signal lines of a second one of the signal line groups are connected between the controller and the fluid pressure control unit by a second connector.
In the brake fluid pressure control device according to the first aspect of the invention, the signal lines connecting the controller to the fluid pressure control valves respectively are divided into signal line groups, each of which includes a separate connector between the controller and the fluid pressure control unit. The signal lines are not connected altogether by a single connector but are divided into a plurality of groups, which are respectively connected by separate connectors. Accordingly, even in the case where some of the connectors fall into an abnormally connected condition, for example, due to disconnection or inappropriate fitting, as long as the other connectors are normally connected, it is possible to supply control signals to the fluid pressure control valves via the signal lines connected by the connectors that are normally (correctly) connected. The fluid pressure control valves corresponding to the normally connected signal lines can be controlled, and fluid pressures in the brakes corresponding to those fluid pressure control valves can be controlled. Thus, if fail-safe performance during abnormal operation of the electric system (during abnormal operation of the control system) is improved, it is accordingly possible to enhance reliability of the brake fluid pressure control device.
The signal lines are divided into a plurality of signal line groups. The number of the groups is arbitrary. If the number of groups increases, the number of connectors increases. However, the number of fluid pressure control valves that become incapable of receiving control signals upon occurrence of an abnormally connected condition of one connector decreases. Therefore, it is desirable to determine the number of groups in consideration of the cost required for the connectors, the influence exerted upon emergence of an abnormally connected condition of the connectors, and the like. In general, it is adequate to divide the signal lines into two or three groups. However, it is also possible to divide them into four or more groups. The connectors may be provided on either or both of the controller and the fluid pressure control unit, or at a location between the controller and the fluid pressure control unit.
The brake fluid pressure control device operates according to the first aspect of the invention, as long as the signal lines are divided into a plurality of groups, each having its own connector. The invention is not intended to exclude the possibility of providing a plurality of controllers. It is also possible to respectively control the groups by means of separate controllers.
The brakes may respectively be provided in a front-left wheel, a front-right wheel, a rear-left wheel and/or a rear-right wheel. The brakes may be divided such that one or more signal lines connected to one or more fluid pressure control valves corresponding to the brakes respectively provided in the front-left wheel and the rear-right wheel and one or more signal lines connected to one or more fluid pressure control valves corresponding to the brakes respectively provided in the front-right wheel and the rear-left wheel belong to different signal line groups.
In such a brake fluid pressure control device, the signal lines are divided such that one or more signal lines connected to one or more fluid pressure control valves that control fluid pressures in brakes for diagonally located wheels belong to the same group. Accordingly, even in the case where one of the connectors falls into an abnormally connected condition, if the other connector is normally connected, fluid pressures in the brakes for a pair of diagonally located wheels are controlled. Because fluid pressures in the brakes for the diagonally located wheels are controlled, it is possible to inhibit a decline in braking stability of the vehicle.
Furthermore, the fluid pressure control unit may be constructed to include a connecting passage connecting at least either brake cylinders for the front-left wheel and the front-right wheel or brake cylinders for the rear-left wheel and the rear-right wheel and a communication state control valve provided in the connecting passage and switched in accordance with a control signal from the controller between a comm
Hirose Masanori
Nakamura Eiji
Otomo Akihiro
Butler Douglas C.
King Bradley T
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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