US 5,370,449 AGranted

Electrically operated parking brake system

AssigneeEaton Corporation

InventorsStephen A. Edelen, Robert W. Jones

Life of this patent

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Abstract

A parking brake system is provided which includes a dual solenoid operated valve located in series with the emergency brake control valve of a hydraulically operated brake system. The dual solenoid valve is operable to either one of two mechanical detent positions so that positioning of the valve is retained in the event of loss of power. The dual solenoid valve is controlled by the vehicle operator from the transmission console and removes fluid pressure from the brakes when actuated to a PARK position. An electronic control unit is provided for sensing the speed of the vehicle and the pressure in the hydraulic line to the brakes and provides a PARK enabling signal when the vehicle speed is below a predetermined amount. When a gear is selected at the console the dual solenoid valve is actuated to a position permitting fluid pressure to be applied to the brakes and effectively returns control of the brakes to the emergency brake control device. A pressure sensor is provided in the line to the brakes and is used to provide feedback to the driver and to control transmission shifting.

Claims7

Dependent claims

A brake control system for a motor vehicle parking brake means which is biased toward a brake apply position and maintained in a brake release position by the application of pressurized fluid to the brake means, said control system comprising:

a source of fluid pressure,
mechanically actuated valve means,
electrically actuated valve means,
said mechanically actuated valve means actuable to a position communicating fluid from said source to said electrically actuated valve means,
said electrically actuated valve means including a valve structure actuable to a first position by energization of a first solenoid means and to a second position by energization of a second solenoid means, said structure including means for releasably maintaining said structure in said first and second positions upon de-energization of said first or second solenoid means respectively,
said electrically actuated valve means adapted to relieve the fluid pressure from said parking brake means while in said first position, and to apply pressurized fluid from said source to said parking brake means while in said second position,
transmission gear selection means for selecting at least one transmission gear and for selecting application of the parking brake means,
control means for energizing said first solenoid means in response to a parking brake application selection, and for energizing said second solenoid means in response to a gear selection.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/135,901Filed 12 Oct 1993
Granted: 6 Dec 1994
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

B60T 13/686
By electrically-controlled valves: in hydraulic systems or parts thereof
B60T 13/22
The fluid being liquid: brakes applied by springs or weights and released hydraulically
F16H 63/48
Comprising signals other than signals for actuating the final output mechanisms: signals to a parking brake or parking lock; Control of parking…
F16H 2059/746
Inputs being a function of engine parameters: engine running state, e.g. on-off of ignition switch