Fluid-pressure and analogous brake systems – Electric control
Patent
1998-01-20
2000-05-30
Schwartz, Chris
Fluid-pressure and analogous brake systems
Electric control
303 3, 303124, B60T 1372
Patent
active
06068352&
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to controllers for electrically actuated braking systems such as those used to apply the brakes of towed vehicles, i.e., trailers, in response to commands from the towing vehicle. More particularly, the invention relates to electronic controllers for braking systems which operate in response to inertial sensors and/or manually actuated switches, or the like, to actuate a towed vehicle's brakes in a particular controlled manner.
Substantial effort and progress has been made towards the goal of providing more stable and more responsive electronic brake system controllers which actuate the electromagnetic brake shoe actuators of a towed vehicle. For example, it is known that continuous braking excitation is likely to promote trailer brake lockup which causes a substantial decrease in braking efficiency and loss of operator control. Prior art brake controllers have eliminated these undesirable effects by applying pulsating excitation to the brakes by means of a constant pulse width applied at varying frequencies or a varying pulse width applied at a constant frequency. It is also known that trailer brake lockup may occur if the towed vehicle's brakes are applied too rapidly. However, the brakes may feel sluggish and may not be fully actuated in a timely manner if the brake current is applied too slowly. Prior art controllers have been designed to apply current to the brakes in a controlled manner which avoids these problems and which releases the brakes rapidly when the brake actuation signal is removed to prevent continued actuation of the towed vehicle's brakes. Another example of progress in prior art brake controllers is the accommodation of different towed vehicle weights and brake system characteristics which are variables having a substantial impact upon the proper braking of the towed vehicle.
Although substantial progress has been made in brake system controllers, most of these prior art devices have relied on the extensive use of analog technologies to implement the controller circuitry. There are several drawbacks to these analog designs. First, analog circuits often exhibit operational variations (drift) over temperature extremes and component variability. Second, because the operation of the controller is hardwired into the design of the circuitry, these prior art devices have only limited flexibility which necessitate complete redesigns of the circuitry when changes are desired in the brake controller operational parameters or when the addition of new operational features are desired. Finally, since analog, designs rely on small variations in voltage during normal operation, they are often sensitive to voltage fluctuations and radio frequency noise sources which may cause operational problems.
SUMMARY OF THE INVENTION
The present invention provides a new and more effective electronic brake system controller that eliminates many of the above-mentioned problems of the prior art devices caused by the reliance on analog circuit technologies.
The electronic brake controller of the present invention implements a microcontroller-based design that works in conjunction with analog circuit technology to provide improved operation and reliability over an extended temperature range and an improved response to braking conditions. The programming of the microcontroller can be quickly modified and adapted to implement a variety of analog circuits, resulting in a brake controller that has the flexibility to provide varied features and capabilities.
In the preferred embodiment, the brake controller of the present invention applies pulsating excitation to the brakes of the towed vehicle in a controlled manner such that brake lockup is avoided, and provides a gain adjustment control that accommodates different towed vehicle weights and brake system characteristics. Furthermore, the brake controller displays the magnitude of the braking current, and terminates the braking current if the magnitude exceeds a threshold value.
One aspect of the present invention is
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Albright Marcia S.
Kulkarni Chandrakumar D.
Smith Bruce E.
Zavodny Stephen A.
Schwartz Chris
Tekonsha Engineering Company
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