Fluid-pressure and analogous brake systems – Speed-controlled – Regenerative brakes
Reexamination Certificate
2002-04-02
2003-12-16
Butler, Douglas C. (Department: 3683)
Fluid-pressure and analogous brake systems
Speed-controlled
Regenerative brakes
C188S156000, C188S158000, C303S003000, C303S020000, C303S112000, C303S155000, C303S177000
Reexamination Certificate
active
06663197
ABSTRACT:
BACKGROUND OF INVENTION
The present invention generally relates to vehicle braking and, more particularly, to an adaptive brake control system that compensates for braking variations to provide consistent brake pedal feel to the vehicle operator.
Conventional frictional braking systems installed on automobiles generally employ a brake pedal assembly having a brake pedal coupled to a master cylinder for providing pressurized hydraulic brake fluid to apply friction braking at the wheels of the vehicle. The brake pedal is actuated (depressed) by the vehicle operator to demand an amount of friction braking. Friction braking systems are generally configured to initially provide a consistent brake pedal feel to the vehicle operator such that the amount of friction braking achieved is substantially proportional to the amount of force applied to the brake pedal by the vehicle operator. However, it is generally known that a number of factors may lead to inconsistent brake pedal response. For example, wear in the friction brake pads, brake fade, variations from one brake pedal to another brake pedal in different vehicles, and temperature can influence the brake pedal response, and thus may provide for inconsistent friction braking over time. As a consequence, the vehicle operator may experience inconsistent variations in brake pedal feel.
The inconsistent brake pedal response generally experienced with friction braking can become more significant when combined with regenerative braking, commonly found on electric and hybrid vehicles. Regenerative braking systems are typically combined with friction braking systems to convert kinetic energy to electrical energy for storage in the vehicle battery. Regenerative braking is typically powered by an electric motor, which acts as a generator during braking, coupled to the powertrain to convert the kinetic energy to electrical energy. Regenerative braking may also be performed with other energy storage technologies that convert the kinetic energy of a vehicle into an alternate form of energy. Concepts exist for recovering vehicle kinetic energy and storing it in the form of pressurized hydraulic fluid, rotating flywheels, and magnetic fields maintained by super conducting coils. The proportional amounts of regenerative braking and friction braking is typically determined by the control system and varies depending on a number of factors including vehicle speed, battery charge, and the amount of braking force commanded. As the vehicle brake control system changes the proportional amounts of regenerative braking and friction braking, the inconsistent brake pedal response becomes more significant, since the amount of friction braking exhibiting inconsistent brake pedal response may change quickly between no friction braking and a substantial amount of friction braking. Thus, the inconsistent brake pedal feel becomes more noticeable to the vehicle operator.
Accordingly, it is desirable to provide for a brake control system in a vehicle that adapts and compensates for inconsistent brake pedal response. In particular, it is desirable to provide for a vehicle brake pedal control system for controlling both friction braking and regenerative braking, which compensates for inconsistent brake pedal response experienced in the friction braking, so as to provide more consistent brake pedal feel to the vehicle operator.
SUMMARY OF INVENTION
In accordance with the teachings of the present invention, a vehicle brake system is provided which compensates for brake pedal feel variation so as to provide for enhanced braking feel to the vehicle operator. The brake system includes a brake command input indicative of braking demand requested by a vehicle operator, an accelerometer for sensing longitudinal acceleration of the vehicle, and a brake actuator for generating braking force to be applied to one or more brakes on the vehicle. The vehicle brake system further includes a controller for receiving the brake demand signal and the sensed acceleration and detecting a brake torque variation as a function of the sensed longitudinal acceleration and brake demand signal. The controller further adjusts a torque command signal to adjust the amount of braking torque generated by the brake actuator so as to compensate for brake torque variation. According to one aspect of the present invention, the brake actuator includes friction braking and regenerative braking, wherein the amount of friction braking is adjusted to compensate for brake torque variation.
REFERENCES:
patent: 4962969 (1990-10-01), Davis
patent: 5358317 (1994-10-01), Cikanek
patent: 5511859 (1996-04-01), Kade et al.
patent: 5615933 (1997-04-01), Kidston et al.
patent: 5716108 (1998-02-01), Asa et al.
patent: 5839800 (1998-11-01), Koga et al.
patent: 5997107 (1999-12-01), Koga et al.
patent: 6070953 (2000-06-01), Miyago
patent: 6086166 (2000-07-01), Fukasawa
patent: 6142586 (2000-11-01), Sakai
patent: 2003/0080614 (2003-05-01), Soga
Brown Gregory P.
Butler Douglas C.
Ford Global Technologies LLC
LandOfFree
Vehicle brake system having adaptive torque control does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Vehicle brake system having adaptive torque control, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vehicle brake system having adaptive torque control will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3097488