Fluid conductivity sensor for actuating and testing an electroexploding device
View Patent ↗Disclosed is an apparatus for sensing the electrical conductivity of fluid wherein when electrodes of the apparatus are exposed to fluid. When the electrodes are exposed to a fluid with a predetermined salinity, a voltage is developed on a capacitor which in turn fires a load, such as a resistive bridge wire. Also disclosed is a testing circuit, whereby the integrity of the circuit can be ascertained without the necessity of actually firing the circuit.
1. A sensor ( 10 ) for use in conjunction with a canopy release mechanism, the sensor ( 10 ) having firing and testing modes and comprising:
a detection sub-circuit ( 12 ) including a battery ( 20 ) and first and second electrodes ( 22 ), the detection sub-circuit ( 12 ) further including a first switch (S 1 ) having a closed position completing a circuit between the first and second electrodes ( 22 ) and an opened position with no circuit being completed between the first and second electrodes ( 22 );
a firing sub-circuit ( 14 ) connected to the detection sub-circuit ( 12 ), the firing sub-circuit ( 14 ) including a comparator ( 56 ) having positive and negative terminals and a comparator output, a capacitor ( 54 ) and a load ( 52 ) interconnected to the comparator output, a fixed reference voltage ( 62 ) connected to the negative terminal, a second switch (S 2 ) interconnected to the positive terminal, and two resistors, the second switch (S 2 ) having a closed position wherein the two resistors are placed in parallel whereby the fixed reference voltage ( 62 ) is not exceeded and there is no output from comparator ( 56 ), the second switch (S 2 ) further including an opened position wherein current flow at the comparator output is permitted;
a test switch ( 38 ) and an associated test power source ( 36 ), closure of the test switch ( 38 ) effecting closure of the first and second switches (S 1 and S 2 );
a controller sub-circuit ( 16 ) connected to the detection sub-circuit ( 12 ) and including a microcontroller ( 70 ) and an EPROM ( 72 ), the controller sub-circuit ( 16 ) functioning to record data regarding the firing mode;
whereby the firing mode is achieved when the test switch ( 38 ) is opened and sea water is present to complete a circuit between the first and second electrodes ( 22 ), the completed circuit delivering current to the firing sub-circuit ( 14 ), the opening of second switch (S 2 ), permitting current flow at the comparator output to charge capacitor ( 54 ) and fire load ( 52 ); and
whereby the testing mode is achieved when the test switch ( 38 ) is closed to complete a circuit between the first and second electrodes ( 22 ), the complete circuit delivering current to the firing sub-circuit ( 14 ), the closing of second switch (S 2 ) preventing current flow at the comparator output, whereby capacitor ( 54 ) is not charged and load ( 52 ) is not fired, current being supplied to the controller sub-circuit ( 16 ) during the testing mode.
2. A sensor ( 10 ) comprising:
a detection sub-circuit ( 12 ) including first and second electrodes ( 22 ), the detection sub-circuit ( 12 ) further including a first switch (S 1 ) having a closed position completing a circuit between the first and second electrodes ( 22 ) and an opened position with no circuit being completed between the first and second electrodes ( 22 );
a firing sub-circuit ( 14 ) connected to the detection sub-circuit ( 12 ), the firing sub-circuit ( 14 ) including a comparator ( 56 ) having a comparator output, a load ( 52 ) interconnected to the comparator output, a second switch (S 2 ) connected to the comparator ( 56 ), wherein the comparator ( 56 ) includes first and second inputs in addition to an output, and wherein a fixed reference voltage ( 62 ) is connected to the first input and the second switch (S 2 ) is connected to the second input, the firing sub-circuit ( 14 ) further comprising two resistors wherein closing the second switch (S 2 ) places the two resistors in parallel whereby the fixed reference voltage ( 62 ) is not exceeded, there is no output from comparator ( 56 ), and the load ( 52 ) cannot be fired.
3. The sensor as described in claim 2 further comprising a test switch ( 38 ) for selectively opening or closing the first and second switches (S 1 and S 2 ).
4. the sensor ( 10 ) as described in claim 3 wherein the sensor ( 10 ) includes a firing mode that is achieved when the test switch ( 38 ) opened and sea water is present to complete a circuit between the first and second electrodes ( 22 ), the completed circuit delivering current to the firing sub-circuit ( 14 ), the opening of second switch (S 2 ) permitting current flow at the comparator output to fire load ( 52 ).
5. The sensor ( 10 ) as described in claim 4 wherein the sensor ( 10 ) also includes a testing mode that is achieved when the test switch ( 38 ) is closed to complete a circuit between the first and second electrodes ( 22 ), the complete circuit delivering current to the firing sub-circuit ( 14 ), the closing of second switch (S 2 ) preventing current flow at the comparator output, whereby load ( 52 ) is not fired.
6. The sensor ( 10 ) as described in claim 5 further comprising a controller sub-circuit ( 16 ) for recording data regarding the firing mode.
7. The sensor ( 10 ) as described in claim 6 wherein a normal condition is recorded when sensor ( 10 ) is in the testing mode and current is recorded by controller sub-circuit ( 16 ).
8. The sensor ( 10 ) as described in claim 6 wherein a failure to condition is recorded when the sensor ( 10 ) is in the testing mode but no current is recorded by controller sub-circuit ( 16 ).
9. The sensor ( 10 ) as described in claim 2 further comprising a capacitor ( 54 ) and the load ( 52 ) that are connected to the output of comparator ( 56 ) whereby when there is current at the output of comparator ( 56 ) the capacitor ( 54 ) triggers the load ( 52 ).
10. The sensor ( 10 ) as described in claim 9 further comprising a canopy release mechanism that is triggered by the load ( 52 ).
11. A sensor ( 10 ) comprising:
a detection sub-circuit ( 12 ) including first and second electrodes ( 22 ), the detection sub-circuit ( 12 ) further including a first switch (S 1 ) having a closed position completing a circuit between the first and second electrodes ( 22 ) and an opened position with no circuit being completed between the first and second electrodes ( 22 );
a firing sub-circuit ( 14 ) connected to the detection sub-circuit ( 12 ), the firing sub-circuit ( 14 ) including a load ( 52 ), a comparator ( 56 ) having a comparator output, wherein the comparator ( 56 ) includes first and second inputs in addition to an output, and wherein a fixed reference voltage ( 62 ) is connected to the first input and a second switch (S 2 ) is coupled to the second input, the firing sub-circuit ( 14 ) further comprising two resistors wherein closing the second switch (S 2 ) places the two resistors in parallel whereby the fixed reference voltage ( 62 ) is not exceeded, there is no output from comparator ( 56 ), and load ( 52 ) cannot be fired;
whereby the circuit ( 10 ) has a firing mode wherein both the first and second switches (S 1 -S 2 ) are opened and a testing mode wherein both the first and second switches (S 1 -S 2 ) are closed;
a controller sub-circuit ( 16 ) connected to the detection sub-circuit ( 12 ) and firing sub-circuit ( 14 ) and including a microcontroller ( 70 ) and an EPROM ( 72 ), the controller sub-circuit ( 16 ) functioning to record data regarding the firing mode.
12. The sensor as described in claim 11 wherein the microcontroller ( 70 ) initiates the testing mode in a timed sequence.
13. The sensor as described in claim 11 wherein a capacitor ( 54 ) is used to fire load ( 52 ).
14. The sensor as described in claim 13 wherein the controller sub-circuit ( 16 ) records the charge and discharge slopes of the capacitor ( 52 ).