Patent Application
20110143320
The disclosure generally relates to regenerative braking systems in hybrid electric vehicles (HEVs, FHEVs, PHEVs, BEVs, FCEVs). More particularly, the disclosure relates to an HEV brake pedal air gap filler system and method which fills an air gap between a Brake pedal push rod and/or arm and a master cylinder push rod (or input rod) to impart braking to an HEV in the event that brake system control of the active booster is compromised during regenerative braking thereby affecting brake pedal feel.
In regenerative braking systems, where independent force control of the hydraulic brake system is required, the capability of the active booster function to provide the force which is required to allow flow of ambient air into the booster and induce vacuum boost within a desired period of time may be reduced under some conditions. The system performance may become unacceptably slow and result in a fall back level that changes the brake pedal feel and increases the brake travel distance which is required to stop the vehicle. The changes in brake pedal feel and travel distance are due to the presence of an air gap between the pedal push rod/arm and the master cylinder/booster push rod (or input rod). Under normal conditions, the space in the air gap is used during series regenerative braking. Under conditions in which the active booster function is compromised, series regenerative braking is disabled and the pedal feel simulator is shut off or bypassed.
Therefore, an HEV brake pedal simulator air gap filler system and method which fills an air gap between a brake pedal arm and a master cylinder push rod to impart braking to an HEV in the event that a pedal feel simulator is compromised during regenerative braking is needed.
The disclosure is generally directed to a brake pedal simulator air gap filler system. An illustrative embodiment of the system includes a brake pedal, a pedal feel simulator engaged by the brake pedal, a pedal push rod engaged by the brake pedal, a master cylinder/booster push rod (or input rod) spaced-apart from the pedal push rod, an air gap between the pedal push rod and the master cylinder/booster push rod, a master cylinder/booster engaged by the master cylinder/booster push rod and an air gap filling apparatus having an air gap filling head in adjacent proximity to the air gap and adapted to selectively engage and disengage the air gap.
In some embodiments, the brake pedal simulator air gap filler system may include an electronic control unit; a brake pedal; a pedal feel simulator engaged by the brake pedal and interfacing with the electronic control unit; a pedal push rod engaged by the brake pedal; a master cylinder/booster push rod spaced-apart from the pedal push rod; an air gap between the pedal push rod and the master cylinder/booster push rod; a master cylinder/booster engaged by the master cylinder/booster push rod and interfacing with the electronic control unit; and an air gap filling apparatus having an air gap filling head in adjacent proximity to the air gap and interfacing with the electronic control unit. The electronic control unit may be adapted to detect a condition affecting the master cylinder/booster and responsively inactivate the pedal feel simulator and cause engagement of the air gap filling head of the air gap filling apparatus with the air gap.
The disclosure is further generally directed to an HEV brake pedal simulator air gap filler method. An illustrative embodiment of the method includes positioning an air gap filling head in adjacent proximity to an air gap between a pedal push rod and a master cylinder/booster push rod of a hybrid electric vehicle braking system; detecting a condition affecting a master cylinder/booster of the braking system; disabling a series regenerative braking mode and a pedal feel simulator of the braking system; extending the air gap filling head into the air gap; and extending the master cylinder/booster push rod into a master cylinder/booster of the braking system through the pedal push rod and the air gap filling head.
The disclosure will now be made, by way of example, with reference to the accompanying drawings, in which:
The following detailed description is merely exemplary in nature and is not intended to limit the described embodiments or the application and uses of the described embodiments. As used herein, the word “exemplary” or “illustrative” means “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” or “illustrative” is not necessarily to be construed as preferred or advantageous over other implementations. All of the implementations described below are exemplary implementations provided to enable persons skilled in the art to practice the disclosure and are not intended to limit the scope of the appended claims. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.
Referring initially to
A pedal push rod 8 may extend from the brake pedal 2. In the event that a pedal push rod does not exist, a gap filling device extends from pedal arm to master cylinder input rod. A master cylinder/booster push rod 10 may be axially aligned with and disposed in spaced-apart relationship with respect to the pedal push rod 8. An air gap 16 may separate the master cylinder/booster push rod 10 from the pedal push rod 8. The master cylinder/booster push rod 10 may engage a master cylinder/booster 12. An active booster solenoid valve provides assist to input rod movement to provide power brake 14 may engage the master cylinder/booster push rod 10.
An air gap filling apparatus 20 may be disposed in adjacent proximity to the air gap 16 between the pedal push rod 8 and the master cylinder/booster push rod 10 for purposes which will be hereinafter described. The air gap filling apparatus 20 may include a gap filling head actuator 21 which may be a solenoid, for example and without limitation. An actuator shaft may be engaged for extension and retraction by the gap filling head actuator 21. An air gap filling head 23 may be on the distal or extending end of the actuator shaft 22. In some embodiments, the air gap filling head 23 may have a generally wedge-shaped configuration, as shown. Accordingly, as shown in
Referring next to
During braking of the HEV, an operator (not shown) of the HEV depresses the brake pedal 2. The ECU 26 may continually receive input on the position of the brake pedal 2 (
In the series regenerative braking supplemented by hydraulic braking mode, the ECU 26 activates the motor or motors (
Under some circumstances, the ECU 26 may determine that conditions (such as ambient cold conditions, for example and without limitation) exist which may compromise the active booster function of the master cylinder/booster 12. Accordingly, the ECU 26 may disable the series regen braking function and the pedal feel simulator 5. Upon depression of the brake pedal 2, the ECU 26 actuates the air gap filling apparatus (as indicated by reference numeral 20a in
Referring next to
Although the embodiments of this disclosure have been described with respect to certain exemplary embodiments, it is to be understood that the specific embodiments are for purposes of illustration and not limitation, as other variations will occur to those of skill in the art.
