Device for detecting the state of a switch

• US 9,064,649 B2
• Filed: 04/03/2007
• Issued: 06/23/2015
• Est. Priority Date: 04/04/2006
• Status: Active Grant

• Current Assignee: Airbus Operations SAS (Airbus SE)
• Original Assignee: Airbus Operations SAS (Airbus SE)
• Inventors: Bonnet, Guillaume, Dulaur, Mathieu
• Primary Examiner(s): Valone, Thomas F
• Application Number:
  US12/295,884
• Publication Number:
  US 20100052705A1
• Time in Patent Office: 3,003 Days
• Field of Search: 324/421
• US Class Current: 1/1
• CPC Class Codes: H01H 1/605 Cleaning of contact-making surfaces by relatively high voltage pulses
• CPC Class Codes: H01H 71/04 Means for indicating condition of the switching device by means of an auxiliary contact H01H71/46
• CPC Class Codes: H01H 9/167 Circuits for remote indication
• CPC Class Codes: H02H 3/04 with warning or supervision in addition to disconnection, e.g. for indicating that protective apparatus has functioned watching of pilot wires H02H1/0084; protection of protective arrangements H02H7/008; indication of the state of electronic switches H03K17/18

Abstract

A device for detecting the state of a switch. The device includes a detection circuit which delivers a signal of specified value (V_pullup) when the value of an electrical quantity (R_Sw) characterizing the state of the switch is less than a threshold called the lower threshold (R_closed) and/or a signal of different value when the value of the electrical quantity is greater than a threshold different from the lower threshold, called the upper threshold (R_open). The disclosed embodiments also concern flight control systems, in which the device is implemented, and the aircraft including the systems.

Claims

1. A device for detecting the state of a switch, including a switch and a feed circuit of said switch, the device comprising:

a detection circuit which delivers at least one of;

a first signal of a first specified value when the value of an electrical quantity characterizing the state of the switch is any value less than a lower threshold value at a terminal of the detection circuit; and

a second signal of a second specified value, different than the first value of the first signal, when the value of said electrical quantity is any value greater than an upper threshold value, different from the lower threshold value at the same terminal of the detection circuit as the first signal;

the device further comprising said feed circuit and an adjustment circuit that includes a voltage divider having resistors, a voltage delivered by the adjustment circuit to the detection circuit being made dependent on a resistance of the switch, the adjustment circuit allowing for reading the resistance of the switch through the voltage divider, the feed circuit, and the voltage delivered to the detection circuit; and

wherein at least one of;

a voltage of the feed circuit, and

values of the resistors of the voltage divider,

are adjusted in such a way to provide sufficient current to clean a contact of the switch based on the reading, and

wherein the detection circuit includes a hysteresis circuit which delivers a first output-voltage value for an input voltage less than a first voltage threshold and a second, different output-voltage value for an input voltage greater than a second voltage threshold, and the first output-voltage value is determined based on a following expression;

2. A device according to claim 1, further comprising that, when the value of the electrical quantity is between the lower-threshold value and the upper-threshold value or is equal to the lower and upper threshold values, the detection circuit delivers a signal identical to that of a previous state.

3. A device according to claim 1, further comprising that said electrical quantity is the resistance of the switch and that the detection circuit delivers both of:

the first signal of specified first value when the value of the resistance is less than a lower resistance threshold; and

the second signal of the second, different value when the value of the resistance is greater than an upper resistance threshold.

4. A detection device according to claim 1, further comprising that one of the first and second signals indicates the closed state and the other signal the open state of said switch.

5. A device according to claim 1, wherein the hysteresis circuit includes further feed and resistances with values such that the hysteresis circuit provides a current sufficient to clean the contact of the switch.

6. A flight control system, comprising a device according to claim 1.

7. An aircraft, comprising a device according to claim 1.

8. A device according to claim 1, wherein the switch is considered to be open when the resistance value of the switch is greater than 10 kΩ

.

9. A device for detecting the state of a switch, including a switch and a feed circuit of said switch, the device comprising:

a detection circuit which delivers at least one of;

a first signal of a first specified value when the value of an electrical quantity characterizing the state of the switch is any value less than a lower threshold value at a terminal of the detection circuit; and

a second signal of a second specified value, different than the first value of the first signal, when the value of said electrical quantity is any value greater than an upper threshold value, different from the lower threshold value at the same terminal of the detection circuit as the first signal;

the device further comprising said feed circuit and an adjustment circuit that includes a voltage divider having resistors, a voltage delivered by the adjustment circuit to the detection circuit being made dependent on a resistance of the switch, the adjustment circuit allowing for reading the resistance of the switch through the voltage divider, the feed circuit, and the voltage delivered to the detection circuit; and

wherein at least one of;

a voltage of the feed circuit, and

values of the resistors of the voltage divider,

are adjusted in such a way to provide sufficient current to clean a contact of the switch based on the reading; and

the device further comprising a cutoff frequency filter having a resistor and a capacitor, wherein the resistance value of the resistor is fixed at approximately 100 kΩ

, and a capacitance value of the capacitor is substantially equal to 22 nF.

10. A device according to claim 9, wherein the resistance values of the first resistor and the second resistor are selected such that the cleaning current is greater than 10 mA and a voltage at terminals of the switch is less than 5 V when the resistance of the switch tends toward zero.

11. A device according to claim 9, wherein an output frequency of the cutoff frequency filter ranges between 50 Hz and 100 Hz.