Fluid-pressure and analogous brake systems – Multiple fluid-receiving devices – Multiple motors
Reexamination Certificate
2000-09-22
2001-11-27
Butler, Douglas C. (Department: 3613)
Fluid-pressure and analogous brake systems
Multiple fluid-receiving devices
Multiple motors
C303S015000, C303S071000, C303S003000, C303S009760, C188S00111E
Reexamination Certificate
active
06322159
ABSTRACT:
TECHNOLOGY FIELD OF THE INVENTION
This invention generally relates to a brake controller for providing electrical control of a motor vehicle parking brake, and more particularly, the invention prevents inadvertent application of the parking brake in an air brake system when the vehicle loses electrical power.
BACKGROUND OF THE INVENTION
Conventional heavy-duty vehicle air brake systems use mechanical pneumatic push-pull control valves to actuate and release the vehicle parking brakes and the trailer brake supply line. According to Federal Motor Vehicle Safety Standard (FMVSS) No. 121, the parking brake and the trailer brake controls must be located in close proximity to the driver. This requires the installation of large pneumatic push-pull valves in the vehicle instrument panel and further requires pneumatic lines and connections within the instrument panel, connecting with other components of the truck air brake system. The resulting system is very bulky and uses critical volume in the instrument panel, often imposing design parameters to the detriment of driver comfort and convenience. Furthermore, installation of the instrument panel controls requires making complex airtight connections during final vehicle assembly. With the goal of improving instrument panel design and driver ergonomics, attempts have been made to reduce the volume of switches within the instrument panel. Fundamental limitations, however, limit the potential of this approach. A different approach to controlling application of the parking brake is the use of an electrical switch in the instrument panel, controlling a solenoid driven valve located remotely in the air parking brake system. An inherent disadvantage exists for previous electrically controlled systems. In an air brake system, the braking force is applied by a coil spring whenever the brake line pressure goes below a certain threshold level thus, when the brake line is at atmospheric pressure, the spring, activates the parking brake. In previous electrically controlled systems, when power was lost to the solenoid air valve, the valve would move to the exhaust position, dropping the parking brake line pressure to atmospheric and activating the parking brake. The result could be inadvertent engagement of the parking brake. In conducting a failure mode and effect analysis of such a failure due to a power loss, the combination of a single point failure having significant consequences discourages use of conventional electrical instrument panel controls for vehicle air brake systems of this type.
SUMMARY OF THE INVENTION
This invention provides for a latching electric control for a vehicle air parking brake system which is mounted to the instrument panel, overcoming the problems and disadvantages of the conventional techniques in the art. The invention provides for the use of a latching solenoid air valve that assures that a loss of electrical power on the highway will not result in an unwanted automatic application of the vehicle's parking brakes. Briefly, the invention includes tractor parking brake and trailer parking brake supply switches which control, through an electrical circuit, latching solenoid air valves which in turn control the air supply to the tractor parking brake and the trailer parking brake supply line. Additionally, low pressure switches automatically vent the parking brake and trailer supply lines under conditions of low supply pressure and indicate low pressure in the parking brake and trailer supply lines to instrument panel indicator lamps.
Further object features and advantages of the invention will become apparent from consideration of the following description and the appended claims when taken in connection with the accompanying drawings.
REFERENCES:
patent: 4550953 (1985-11-01), Bartholomew
patent: 4671578 (1987-06-01), Rothen et al.
patent: 4763959 (1988-08-01), Vandemotter
patent: 4824178 (1989-04-01), Petersen
patent: 5061015 (1991-10-01), Cramer et al.
patent: 5118165 (1992-06-01), Latvala
patent: 5370449 (1994-12-01), Edelen et al.
patent: 5520446 (1996-05-01), Wilson
Butler Douglas C.
Honeywell Commercial Vehicle Systems Co.
LandOfFree
Latching electric-control vehicle air brake system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Latching electric-control vehicle air brake system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Latching electric-control vehicle air brake system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2614233