Fluid-pressure and analogous brake systems – Speed-controlled – With failure responsive means
Reexamination Certificate
2000-09-20
2002-07-09
Dickson, Paul N. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
With failure responsive means
C303S146000
Reexamination Certificate
active
06416140
ABSTRACT:
This application is based on Japanese Patent Application Nos. 11-266614 filed Sep. 21, 1999 and 11-337750 filed Nov. 29, 1999, the contents of which are incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a brake control apparatus for controlling braking forces to be generated by a plurality of brake devices for braking respective wheels of a vehicle.
2. Discussion of Related Art
An example of such a brake control apparatus is disclosed in JP-B2-2835173. This brake control apparatus is adapted to control braking forces to be generated by respective brake devices in the form of four wheel brakes for braking four wheels of an automotive vehicle, namely, a front left wheel, a front right wheel, a rear left wheel and a rear right wheel of the vehicle. The brake control apparatus includes a brake-operation inhibiting portion operable when at least one of the wheel brakes is defective, for inhibiting an operation of one of the normal wheel brakes which is determined by the location of the at least one wheel corresponding to the defective at least one wheel brake.
Where the wheel brake for the rear right wheel is defective, for instance, the brake-operating inhibiting portion of the brake control apparatus indicated above inhibits an operation of the normal wheel brake for the rear left wheel. Where the wheel brakes for the front left and right wheels are defective, the brake-operation inhibiting portion inhibits an operation of the normal wheel brake for the rear right wheel. This control arrangement reduces a difference between the total braking force generated by the two wheel brakes on the left side of the vehicle and the total braking force generated by the two other wheel brakes on the right side, so that the running stability of the vehicle is improved.
The present inventors have found that the known brake control apparatus indicated above has a further room for improvement for more effectively utilizing the normal wheel brake or brakes while restraining a reduction in the running stability of the vehicle when at least one of the wheel brakes is defective. That is, the inventors have found that there are some cases where a reduction in the running stability of the vehicle due to a difference between the total braking force of the left wheel brakes and that of the right wheel brakes is not so large as to cause a problem.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a brake control apparatus which permits effective utilization of the normal brake devices while assuring a substantially acceptable degree of running stability of the vehicle.
The above object may be achieved 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. It is to be further understood that a plurality of elements or features included in any one of the following modes of the invention are not necessarily provided all together, and that the invention may be embodied without some of the elements or features described with respect to the same mode.
(1) A brake control apparatus for controlling at least three brake devices provided for braking respective at least three wheels of an automotive vehicle which includes two wheels located on respective left and right sides of the vehicle, the brake control apparatus comprising an emergency brake control portion for controlling at least two normal brake devices of the at least three brake devices when at least one of the at least three brake devices is defective, such that a difference between a total left-side braking force to be generated by at least one of the at least two normal brake devices which is located on the left side of the vehicle and a total right-side braking force to be generated by the other of the at least two normal brake devices which is located on the right side of the vehicle is made larger when operations of all of the at least two normal brake devices in a detected running condition of the vehicle are not likely to deteriorate a running stability of the vehicle, than when the operations of all of the at least two normal brake devices in the detected running condition are likely to deteriorate the running stability of the vehicle.
In the brake control apparatus constructed according to the above mode (1) of this invention, the emergency brake control portion is operable when at least one of the at least three brake devices, for controlling at least two normal brake devices of the at lest three brake devices, such that a difference between the total left-side braking force to be generated by at least one of the at least two normal brake devices which is located on the left side of the vehicle and the total right-side braking force to be generated by the other of the at least two normal brake devices which is located on the right side of the vehicle is made larger when operations of all of the at least two normal brake devices in the detected vehicle running condition are not likely to deteriorate the vehicle running stability, than when the operations of all of the at least two normal brake devices in the detected vehicle running condition are likely to deteriorate the vehicle running stability.
In the known brake control apparatus, when the brake device for the rear right wheel is defective, the operation of the normal brake device for the rear left wheel is necessarily inhibited. To the contrary, the present brake control apparatus may be adapted to permit the operation of the normal brake device for the rear left wheel when the operation of this normal brake device for the rear left wheel in the presently detected vehicle running condition is not likely to deteriorate the vehicle running stability. Thus, the present brake control apparatus permits effective utilization of the normal brake device for the rear left wheel, thereby reducing the reduction of the total braking force of the vehicle when at least one of the brake devices is defective.
(2) A brake control apparatus according to the above mode (1), wherein the emergency brake control portion includes a running-condition detecting portion for effecting a determination as whether the operations of all of the at least two normal brake devices in the detected running condition of the vehicle are likely to deteriorate the running stability of the vehicle or not, on the basis of at least one of a detected running speed and a detected steering state of the vehicle.
Where the defective brake device is provided for the wheel which is located on the inner side of the path of turning of the vehicle, for instance, the operations of all the normal brake devices in the detected vehicle running condition including. the detected vehicle steering state (steering angle and direction) are less likely to deteriorate the vehicle running stability than when the defective brake device is provided for the wheel located on the outer side of the path of turning of the vehicle. When the vehicle is turning with the defective brake device located on the inner side of the vehicle turning path, a moment acts on the vehicle in the turning direction, while a moment due to a difference between the total inner-side braking force and the total outer-side braking force acts on the vehicle in the direction opposite to the turning direction of the vehicle, since the total outer-side braking force is larger than the total inner-side braking force on the inner side. Accordingly, the vehicle has a comparatively low spinning tendency owing to an effect of offsetting of the moment due to the turning of the vehicle and the moment due to the braking force difference on the inner and outer sides of the vehicle turning path when th
Aizawa Hiroaki
Kojima Seiichi
Sawada Naoki
Yamamoto Takayuki
Kenyon & Kenyon
Pezzlo Benjamin A
Toyota Jidosha & Kabushiki Kaisha
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