Electronic control system

Claim 2

An electronic system for controlling a selectively operable control system comprising a selectively energizable switch coupled to the control system for rendering the control system operative in response to the energization of said switch, a first power switch serially connected between a source of power and said selectively energizable switch to supply energizing signals thereto and render said control system operative, said first power switch including a control element adapted to render said first power switch conductive only in response to the application of a trigger signal to said control element, a second power switch connected in shunt with said selectively energizable switch and with said first power switch for shunting energizing signals from said selectively energizable switch and rendering said control system inoperative, said second power switch including a control element adapted to render said second power switch conductive only in response to the application of a trigger signal to said control element, a switch control means for selectively applying trigger signals either to said control element of said first power switch or to said control element of said second power switch to render said control system operative and inoperative Respectively, and a current interrupting means serially connected between the source of power and the selectively energizable switch for disrupting the supply of power to said selectively energizable switch and rendering the control system inoperative responsive to concomitant conduction of said first and second power switches when said switch control means applies trigger signals to the control element of only one of said first and second power switches and the other of said power switches remains in a conductive state in the absence of the application of a trigger signal to its control element.

Claim 3

An electronic system in accordance with claim 1 wherein said selectively energizable switch comprises a relay, including a selectively energizable relay coil coupled to said first power switch and to said second power switch and including a pair of associated relay contacts operatively connected to said relay coil and adapted to be closed in response to energization of said relay coil and opened in response to de-energization of said relay coil, and relay contacts being connected to said control system for rendering said control system operative in response to the closure thereof, and inoperative in response to the opening thereof.

Claim 4

An electronic system in accordance with claim 2 wherein said first and second power switches respectively comprise first and second triacs, said control elements comprise the respective gate electrodes thereof, and said switch control means comprises a movable contact member for selectively connecting each of said gate electrodes to a source of power to render its associated triac conductive in order to energize and de-energize said relay coil.

Claim 5

An electronic system in accordance with claim 3 wherein said current interrupting means comprises a fuse having a preselected current limit, said fuse being coupled between said selectively movable contact member and the source of power for disrupting the flow of trigger signals between the source of power and said gate electrodes of said first and second triacs regardless of the position of said movable contact member in response to a current flow through said fuse in excess of said preselected current limit.

Claim 6

An electronic system in accordance with claim 3 wherein said current interrupting means comprises a fuse having a preselected current limit, said fuse being serially connected between the source of power and said relay coil for disrupting the flow of power through said relay coil in response to a current flow in excess of said preselected limit, thereby effecting de-energization of said relay coil.

Claim 7

An electronic system in accordance with claim 5 wherein said preselected current limit is exceeded in response to concomitant conduction of said first and second triacs.

Claim 8

An electronic system for effecting fail-safe control of the operation of a brake control system in which the brake is released when the brake control system is rendered operative and is set when the brake control system is rendered inoperative, the electronic system comprising selectively energizable switch means coupled to the brake control system for rendering said brake control system operative in response to energization of said switch means and inoperative in response to de-energization of said switch means, first a.c. switch means serially connected between a source of a.c. power and said selectively energizable switch means for selectively supplying energizing signals to said selectively energizable switch means to render said brake control system operative, said first a.c. switch means including a control element adapted to render said second power switch conductive only in response to the application of a trigger signal to said control element, second a.c. switch means connected in shunt with said first a.c. switch means and said selectively energizable switch means for selectively shunting energizing signals from said selectively energizable switch means and rendering said brake contRol system inoperative, said second a.c. switch means including a control element adapted to render said second power switch conductive only in response to the application of a trigger signal to said control element, a selectively operable switch control means connectable to said control element of said first a.c. switch means and to said control element of said second a.c. switch means for respectively supplying trigger signals to said first a.c. switch means or to said second a.c. switch means in order to render said brake control system respectively operative and inoperative, and a current limiting means serially connected between the source of a.c. power and said selectively energizable switch means for interrupting the a.c. power flow and rendering said brake system inoperative responsive to concomitant conduction of said first and second a.c. switch means when said switch control means is connected to said control element of said first a.c. switch means and said second a.c. switch means remains in a conductive state in the absence of the application of a trigger signal to its control element or when said switch control means is connected to said control element of said second a.c. switch means and said first a.c. switch means remains in a conductive state in the absence of the application of a trigger signal to its control element.

Claim 9

An electronic system for effecting fail-safe control of the operation of a brake control system in which the brake is released when the brake control system is rendered operative and is set when the brake control system is rendered inoperative, the electronic system comprising selectively energizable switch means coupled to the brake control system for rendering said brake control system operative in response to energization of said switch means and inoperative in response to de-energization of said switch means, first a.c. switch means serially connected between a source of a.c. power and said selectively energizable switch means for selectively supplying energizing signals to said selectively energizable switch means to render said brake control system operative, said first a.c. switch means including a control element adapted to render said second power switch conductive only in response to the application of a trigger signal to said control element, second a.c. switch means connected in shunt with said first a.c. switch means and said selectively energizable switch means for selectively shunting energizing signals from said selectively energizable switch means and rendering said brake contRol system inoperative, said second a.c. switch means including a control element adapted to render said second power switch conductive only in response to the application of a trigger signal to said control element, a selectively operable switch control means connectable to said control element of said first a.c. switch means and to said control element of said second a.c. switch means for respectively supplying trigger signals to said first a.c. switch means or to said second a.c. switch means in order to render said brake control system respectively operative and inoperative, and a current limiting means serially connected between the source of a.c. power and said selectively energizable switch means for interrupting the a.c. power flow and rendering said brake system inoperative responsive to concomitant conduction of said first and second a.c. switch means when said switch control means is connected to said control element of said first a.c. switch means and said second a.c. switch means remains in a conductive state in the absence of the application of a trigger signal to its control element or when said switch control means is connected to said control element of said second a.c. switch means and said first a.c. switch means remains in a conductive state in the absence of the application of a trigger signal to its control element.

Claim 10

An electronic system in accordance with claim 7 wherein said selectively energizable switch means comprises a relay including a selectively energizable relay coil electrically connected in series with said first a.c. switch means and in parallel with said second a.c. switch means and including a pair of relay contacts operatively connected to said relay coil, and relay contacts being coupled to said brake control system and adapted to be closed in response to energization of said relay coil for rendering said brake control system operative, and opened in response to deenergization of said relay coil rendering said brake control system inoperative.

Claim 11

An electronic system in accordance with claim 8 wherein said first and second a.c. switch means respectively comprise first and second triacs, said control elements comprise the respective gate electrodes of said triacs, said selectively operable switch control means comprises a multiposition contact member for selectively separately coupling each of said gate electrodes to the source of a.c. power to effect the application of a trigger signal thereto so as to selectively render the associated triac conductive in order to energize and de-energize said relay coil.

Claim 12

An electronic system in accordance with claim 9 wherein said current interrupting means comprises a fuse having a preselected current limit serially connected between the source of power and said relay coil for interrupting the power flow through said relay coil in response to a current flow in excess of said preselected limit, said fuse being subjected to a current flow in excess of said preselected limit in response to simultaneous conduction of said first triac and said second triac.