Volatile organic compound control relay for power application

Abstract

To provide a power relay (10) to be controlled by the presence of volatile organic compounds often emitted by the release of gases from electronic components during overheating and fault conditions.SOLUTION: A relay housing (12) accommodates a standard power relay (22) ranging from a single-pole, single-throw (SPST) to a multi-pole, twin-throw relays in accordance with an usage. A micro-VOC integrated circuit (24) is arranged in the housing (12) and is made to be accessible to surrounding air through a port (14) on the side of a relay (10). The air quality is such that a system properly monitors a fault event and sampled periodically or continuously as required to latch the relay mechanism (22) open and interrupt the flow of electrical energy on a downstream circuit.SELECTED DRAWING: Figure 2

Description

[Background technology]

[0001] Fuses are often expected to extinguish a fire within a housing based on a circuit creating a short circuit or overload that eventually clears the fuse. Other mechanisms such as thermal fuses and switches have also been used, but with limited results because the point of thermal stress must be mechanically connected to the thermally overstressed component to perform their intended function. Many small and transient events may cause smoke, but will not be of sufficient magnitude to trip either the thermal limit or the input fuse. This leaves a damaged or failed product operating until such time as the unit fails completely, often placing additional stress on personnel within a confined area of ​​the failed equipment, such as an aircraft cabin. Summary of the Invention

[0002] Disclosed herein is a volatile organic compound (VOC) control relay utilized as a changeover relay for enabling and disabling power to electronic circuits, particularly suited for power conversion electronics where high power and high power or voltage operation poses risks of failure due to overstress, unpredictable input variations, thermal overstress, component failure, poor design practices, and other failure mechanisms.

[0003] A feature of the VOC control relay is that miniaturization and microelectronics allow the integration of the sensor, microcontroller, and power relay in an integrated package into a single sensing and power control device. [Brief description of the drawings]

[0004] [Figure 1] FIG. 2 is an isometric view of a VOC control relay as described herein. [Diagram 2] FIG. 2 is a cross-sectional view of a VOC control relay. [Diagram 3] FIG. 2 is a block diagram of a VOC control relay. [Figure 4] FIG. 2 is a schematic diagram of a VOC control relay. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005] 1 is an isometric view of a VOC control relay 10 having a housing 12 and a gas port 14. A number of leads provide electrical interconnection between the VOC control relay and an external circuit. These leads include a controller lead 16 and a relay lead 18.

[0006] 2 is a cross-sectional view of the VOC control relay 10. Housed within the housing 12 are a controller section 20 and a relay section 22. The controller section 20 includes a gas sensor 24 and a microcontroller 26. Optionally, a radio 28 may be included. Data and power are provided through a bus 30 electrically interconnected to the controller leads 16. The gas sensor 24 and microcontroller 26 may be powered from the power input to the relay section 22 or from a secondary circuit separate from the relay assembly. A self-contained power relay section 22 with separate power sources to the gas sensor 24 and microcontroller 26 is one preferred embodiment.

[0007] The gas sensor 24 receives a gas input through the gas port 14 and measures the level of VOCs. The gas input is typically ambient air. Sampling can be continuous or periodic as required by the system to properly monitor for fault events. The VOC levels are communicated to the microcontroller 26 to monitor the VOC levels. Depending on the concentration of the VOCs and the rate of change of the VOC concentration, the microcontroller transmits the data via optional radio 28 to an external monitor. If a programmed threshold level is exceeded, the microcontroller 26 opens the relay 32 to remove power from the managed unit. As an example, the microcontroller may instruct the relay to open when the VOC concentration exceeds a nominal level based on the environment by a predetermined amount, such as 50% in concentration. The nominal level may be determined by taking several measurements over time to establish a baseline. An increase in VOC concentration is an indication that there is a component overheating or outgassing. Opening the relay removes power from the managed device. As an example, if the baseline VOC concentration is 480 parts per billion (ppb), and if a reading is made that the concentration exceeds 700 ppb, the relay will trip to remove power.

[0008] VOC gases enter through gas ports 14 extending into the housing 12 where they are analyzed for their substance content. This information is processed by a microcontroller 26 which compares the gross value of the VOC particles to a maximum value allowed based on a programmed value. The programmed value can include offsets for other environmental contaminants, such as dust or other organic compounds, to ensure that false triggering of the system does not occur. Setting of the trip value can be done at the factory or using an optional radio 28. This value can be set at the location of the equipment being monitored. The radio reports the continuous or periodic monitored values ​​of the VOC levels. One suitable gas sensor is a micro-VOC integrated circuit such as the ultra-low power digital gas sensor for monitoring indoor air quality sold by AMS USA Inc. (Cupertino, Calif.) as the CCS811 Gas Sensor Solution.

[0009] The relay 32 is normally in electrical contact with the first contactor 34 in a closed position such that the first relay lead 18A and the third relay lead 18C are electrically interconnected and the device controlled by the VOC control relay 10 functions normally. When a threshold level of the VOC is exceeded, the magnetic coil 36 is energized causing the relay 32 to break contact with the first contactor 34 and make contact with the second contactor 38. When the relay 32 is in electrical contact with the second contactor 38, the second relay lead 18B and the third relay lead 18C are electrically interconnected and the device controlled by the VOC control relay 10 does not receive power.

[0010] Relay 32 may be a single pole single throw (SPST) relay or a multiple pole double throw relay depending on the application.

[0011] When the microcontroller 26 determines that the VOC level has exceeded the programmed level, the microcontroller 26 sends a signal to the relay section, causing the relay 32 to "set" to latch open, thereby removing power from the managed unit. To reset the latching relay 32, an additional electrical signal or a mechanical push button may be used to return the relay 32 to its normal closed position in electrical contact with the first contactor 34.

[0012] 1 and 2 show the gas sensor 24 housed within the same housing 12 as the relay 22, the gas sensor may alternatively be housed in a separate housing and located remotely from the relay, in which case communication between the gas sensor and the relay is by any suitable wired or wireless communication system.

[0013] FIG. 3 is a block diagram depiction of one embodiment. Power is provided via a power bus 138 and a power return 40 wire. Power may be AC ​​or DC power depending on the application. In an exemplary aircraft cabin application, the power is typically 115 volts AC at 400 Hz. Depending on the power bus source selected, fine tuning of the circuit may be required. Power is provided through a normally closed first contactor 34 of the relay section 22 to the managed unit 42 through a power output 48 of the relay section 22. The VOC sensor (gas sensor 24) continuously monitors the air quality within the managed unit 42. The VOC content is requested by the microcontroller 26 through an inter-integrated circuit (I2C) interface 46. Once the measurement is completed, the VOC sensor 24 responds with the VOC content to the microcontroller 26 through the I2C interface 46. The microcontroller 26 determines if the response value is greater than a programmed limit. The programmed limit may be set at the factory or loaded over the air through a wireless interface with the microcontroller 26. The microcontroller 26 with embedded radio is a design strategy that keeps the device 10 as small as possible.

[0014] Figure 4 shows the electrical connections from component to component diagrammatically. An I2C interface 46 between the microcontroller 26 and the sensor 24 allows two-way communication between these devices. Power for the microcontroller and the sensor is derived from a suitable power supply that is taken from the input power. The method is determined by the input power bus 138 voltage and the configuration selected.

[0015] J1 in FIG. 4 is a programming port that allows firmware to be loaded into the microcontroller (26) U2. U1 is a voltage regulator for converting the 5VDC of the Universal Serial Bus (USB) interface to a regulated 3.0VDC used by the microcontroller for operation during programming. Y1 is a crystal oscillator for setting the operating frequency of the microcontroller instruction cycle timing to operatively execute firmware instructions. The loaded firmware is adapted to monitor the VOC sensor 24 through an Inter-Integrated Circuit (I2C) interface 46. The microcontroller 26 contains a non-volatile memory for storing the firmware along with nominal values ​​of the VOC sensor under nominal operating conditions for comparison with the obtained operational readings.

[0016] When the microcontroller receives a reading from the VOC sensor 24 indicating a dramatic increase in the VOC value, the microcontroller determines that a smoking, overheating, or outgassing event is occurring. The microcontroller via port PF0 enables the relay control K1 by setting the port to logic 1. K1 then drives the relay (22) LS1 to an open state, removing power 52 to the managed unit. Driving the relay on only in the event of a fault reduces the power consumption of this circuit. Driving on or off, or using a latched state relay may be done with minor modifications to the circuit.

[0017] Power to the microcontroller 26 during operation is obtained from the power input 50. Conversion of power from the power input form is required to produce a 3.0 VDC bias supply to operate the microcontroller 26 and the VOC sensor 24, as well as the relay driver circuit K1. Power conversion from line voltage to DC voltage is well known in the industry and is not included in this disclosure.

Claims

1. A changeover relay (10) for enabling and disabling power (50) to an electronic circuit (42), comprising: a gas sensor (24) capable of measuring a gas concentration in an environment and providing an indication of said measured gas concentration; a relay (22) having a first position that enables the supply of power to the electronic circuitry and a second position that disables the supply of power to the electronic circuitry; a controller operable to receive an indication of the measured gas concentration, the controller operable to provide a control signal to the relay such that the relay is in the first position or the second position based on the received measured gas concentration; Equipped with the controller is operable to establish a baseline gas concentration level based on one or more previously measured gas concentration levels within the environment of the gas sensor and the switching relay, and to compare currently received gas concentration measurements to the baseline gas concentration level; A changeover relay (10), characterized in that said changeover relay further comprises a wireless interface with said controller.

2. The changeover relay (10) according to claim 1, characterized in that the gas sensor (24) is capable of continuously measuring the gas concentration in the environment.

3. The changeover relay (10) according to claim 1, characterized in that the gas sensor (24) is capable of measuring the gas concentration in the environment at predetermined time intervals.

4. 2. The changeover relay (10) of claim 1, characterized in that the controller is capable of controlling the relay to disable the supply of power if the measured gas concentration exceeds a predetermined threshold level.

5. 5. A changeover relay (10) according to claim 4, characterized in that the predetermined threshold level is set at the factory or later via wireless communication using a wireless interface with the controller.

6. 2. The changeover relay (10) of claim 1, characterized in that the controller is capable of controlling the relay to disable the supply of power if the measured gas concentration exceeds a predetermined rate of change.

7. 7. A changeover relay (10) according to claim 6, characterized in that the predetermined rate of change is set at the factory or later via wireless communication using a wireless interface with the controller.

8. 2. The changeover relay (10) of claim 1, wherein the gas sensor and the relay are located remotely from each other, and the microcontroller of the changeover relay (10) and the gas sensor are capable of bidirectional communication.

9. 2. A changeover relay (10) according to claim 1, characterized in that the measured level of gas is stored in a memory, said stored measured level being capable of being provided to an external device when required.

10. 2. The changeover relay (10) of claim 1, wherein said first position is a normally closed position of said relay.

11. A changeover relay (10) according to claim 1, characterised in that the gas to be measured comprises volatile organic compounds.

12. The changeover relay (10) of claim 1, characterized in that the environment comprises the air within an aircraft cabin.

13. A method of using a changeover relay (10) to enable and disable power (50) to an electronic circuit (42), comprising: - using a gas sensor (24) capable of measuring a gas concentration in an environment, providing an indication of said measured gas concentration; using a relay (22) having a first position that enables the supply of power to the electronic circuitry and a second position that disables the supply of power to the electronic circuitry; using a controller operable to receive an indication of the measured gas concentration, the controller operable to provide a control signal to the relay such that the relay is in the first position or the second position based on the received measured gas concentration; Including, 4. The method of claim 3, wherein the transfer relay further comprises a wireless interface with the controller.

14. 14. The method of claim 13, wherein the environment comprises the air within an aircraft cabin.

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