Safety timing control device of gas appliance

Abstract

A safety timing control device is provided for a gas appliance and includes an electromagnetic switch, a first timing controller, a second timing controller, a power converter, and an alarm unit. The electromagnetic switch includes an electromagnet, a return spring, a housing, a connection bar, and a plug. The first timing controller sets a predetermined period of operation of the gas appliance in order to control the supply of electrical power to the electromagnet, which in turn opens or closes a gas passage of the gas appliance to prevent a potential risk of explosion caused by undesired continuous supply of fuel to a flaming site of the gas passage or to prevent a potential risk of being poisoned by carbon monoxide generated by incomplete combustion of fuel gas in the gas appliance.

What is claimed is: 
     
         1 . A safety timing control device of a gas appliance, comprising:
 an electromagnetic switch, which comprises an electromagnet, a connection bar, a return spring, a housing, and a plug, the housing being mounted to an opening of a gas passage, the plug being received in the gas passage, the connection bar having a first end extending through the housing and coupled to a plug, the return spring disposed around and encompassing the first end of the connection bar and received in the housing, the connection bar having a second end that is movable by a magnetic force generated by the electromagnet;   a first timing controller, which is operable to count a predetermined time period of operation of the gas appliance and is electrically connected to an electrical power supply unit;   a second timing controller, which is electrically connected to the electromagnetic switch to count a time period of conduction-on of the electromagnetic switch;   a power converter, which is electrically connected to the first timing controller and the second timing controller to convert and transfer electrical power supplied from the electrical power supply unit from the first timing controller to the second timing controller; and   an alarm unit, which is electrically connected to the first timing controller so that when the predetermined time period of operation of the gas appliance elapses, the first timing controller controls the alarm unit to issue an alarm signal;   wherein the electromagnetic switch is in a conduction-on condition during the predetermined time period of operation and the electromagnet generates a magnetic force that overcomes a return spring force of the return spring to attract and move the second end of the connection bar so as to open the gas passage; and when the first timing controller reaches the predetermined time period of operation, the first timing controller cuts off the electrical connection with the electrical power supply unit to set the electromagnetic switch in a cut-off condition, where the magnetic force of the electromagnet varnishes and the plug is forced back by the return spring force of the return spring to close the gas passage.   
     
     
         2 . The safety timing control device as claimed in  claim 1 , wherein the connection bar comprises a material that is magnetically attractable. 
     
     
         3 . The safety timing control device as claimed in  claim 1  further comprising a first winding and a second winding wound around and encompassing the electromagnet, the second timing controller being electrically connectable to the first winding or the second winding according to a time of conduction-on of the electromagnetic switch, wherein during a time period of conduction-on of  3  seconds for the electromagnetic switch, the second timing controller is electrically connected to the first winding and after time lapse of  3  seconds of conduction-on time of the electromagnetic switch, the second timing controller is electrically connected to the second winding. 
     
     
         4 . The safety timing control device as claimed in  claim 3 , wherein a first electrical current flowing through the first winding is greater than a second electrical current flowing through the second winding. 
     
     
         5 . The safety timing control device as claimed in  claim 1  further comprising a third timing controller, which counts an alarm time period of the alarm signal and is electrically connected to the first timing controller and the alarm unit. 
     
     
         6 . The safety timing control device as claimed in  claim 1 , wherein the electrical power supply unit supplies to the first timing controller an alternating current, which is converted by the power converter into a direct current to be fed to the second timing controller. 
     
     
         7 . The safety timing control device as claimed in  claim 1 , wherein the power converter comprises a transformer. 
     
     
         8 . The safety timing control device as claimed in  claim 1 , wherein the alarm unit comprises a buzzer or an alarm light. 
     
     
         9 . The safety timing control device as claimed in  claim 1  further comprising a carbon monoxide and gas leakage detector, which is electrically connected to the first timing controller so that when the carbon monoxide and gas leakage detector detects gas leaking outside the gas passage or carbon monoxide generated by incomplete combustion of gas has a concentration exceeding a threshold, an electrical signal is generated and applied to the first timing controller to have the first timing controller cut off the electrical connection with the electrical power supply unit and establish a connection with the alarm unit. 
     
     
         10 . The safety timing control device as claimed in  claim 5 , wherein the first timing controller, the second timing controller and the third timing controller are time relays.