Gas detection system

• US 20060114113A1
• Filed: 03/03/2005
• Published: 06/01/2006
• Est. Priority Date: 11/26/2004
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Goto, Yasushi, Yokosawa, Koichi, Nakano, Sadaki
• Granted Patent: US 7,242,309 B2
• Time in Patent Office: Days
• US Class Current: 340/632
• CPC Class Codes: G01N 27/123 for controlling the temperature temperature control per se G05D23/00
• CPC Class Codes: G01N 33/0063 using a threshold to release an alarm or displaying means

Abstract

A gas detection system capable of suppressing the power consumption of the system using gas sensors required for heating for measurement at high accuracy, comprising a server and a plurality of gas sensors connected by way of wireless communication with the server, in which each of the gas sensors is provided with a heater, a controller for controlling the ON-OFF for the power supply to the heater and a comparator for comparing the detected gas concentration with a predetermined threshold value. In the gas detection system, electric power is not usually supplied to the heater in each of the gas sensors and the gas sensor measures the gas concentration at a low accuracy and always compares it with the threshold value. In a case where the gas concentration exceeds the threshold value in one of the gas sensors, it turns the heater of its own to ON thereby switching the measurement to that at high accuracy and turns the heater to OFF upon completing the measurement. At the same time, it informs the detection for the excess of threshold value to the server and the server lowers the threshold value of the gas sensors in the vicinity of the gas sensor that has informed the detection for the excess of threshold value to make the monitoring level severer.

Claims

1. A gas detection system comprising a plurality of sensor nodes located dispersedly, each having a gas sensor module and a communication control module having a controller connected with the gas sensor module and a communication system, and

a server associated with each of the plural sensor nodes and sending a control signal to necessary sensor nodes, wherein

each of the gas sensor module has a gas sensor, a temperature control device for the gas sensor and a temperature measuring device for the gas sensor, and the controller, upon detecting that the measured value of the gas sensor exceeds a predetermined threshold value, operates the temperature control device to increase the measuring accuracy of the gas sensor and informs that the measured value of the gas sensor exceeds a predetermined threshold value by way of the communication control module to the server, and

the server, upon receiving the information that the measured value of the gas sensor exceeds the predetermined threshold value sends a control signal for lowering the threshold value relative to the measured value of the gas sensor to other sensor nodes.

2. A gas detection system according to claim 1, wherein other sensor nodes to which the server sends the control signal for lowering the threshold value relative to the measured value of the gas sensor in response to the information that the measured value of the gas sensor exceeds the predetermined threshold value are sensor nodes in the vicinity of said sensor node informing that the measured value of the gas sensor exceeds the predetermined threshold value, and the sensor group is previously determined on every arbitrary sensor.

3. A gas detection system according to claim 1, wherein the server sends a signal to the sensor nodes for operating the temperature control devices of the gas sensors in a state of supplying a predetermined gas to the gas sensors on a predetermined period or at a desired timing.

4. A gas detection system according to claim 1, wherein the server supplies a predetermined gas to the gas sensors on a predetermined period or at a desired timing.

5. A gas detection system according to claim 1, wherein the server sends an instruction to the sensor node for lowering the threshold value of the gas sensors in a state of supplying a predetermined gas to the gas sensors on a predetermined period or at a desired timing.

6. A sensor node, comprising:

a gas sensor for measuring the gas concentration;

a threshold value setting circuit for storing a predetermined threshold value; and

a comparator for comparing the gas concentration with the predetermined threshold value, and wherein

the threshold value setting circuit lowers the stored threshold value to less than the predetermined threshold value based on the output from the comparator or the instruction from the outside.