Electric steam iron with a low temperature steam control system

Abstract

A low temperature steam control system of an electric steam iron includes a low temperature water discharge valve and a high temperature water discharge valve, which may be controlled by a low temperature bi-metal plate and a high temperature bi-metal plate respectively. Each bi-metal plate may include two overlaying metal plates with different thermal expansion coefficients. When the soleplate is heated by a heating element to a first temperature, the low temperature bi-metal plate can flex and open the low temperature water discharge valve allowing water to flow from a water tank into a vaporization chamber. When the soleplate is further heated by the heating element to a second temperature, the high temperature bi-metal plate can flex and open the high temperature water discharge valve allowing additional water to flow from the water tank into the vaporization chamber.

1 . A steam iron comprising:
 a soleplate having a plurality of steam vents;   a vaporization chamber provided on the soleplate;   a water tank for supplying water to the vaporization chamber;   first and second valves through which water flows from the water tank to the vaporization chamber;   a first bi-metal plate configured to flex towards and push the first valve open when the soleplate is heated by a heating element to a first temperature, allowing a first volume of water to flow from the water tank into the vaporization chamber and generate a first volume of steam through the steam vents for steam ironing delicate clothing; and   a second bi-metal plate configured to flex towards and push the second valve open when the soleplate is further heated by the heating element to a second temperature, allowing an additional volume of water to flow from the water tank into the vaporization chamber and generate an additional volume of steam through the steam vents for steam ironing non-delicate clothing.   
     
     
         2 . The steam iron as claimed in  claim 1 , wherein the second bi-metal plate flexes away and closes the second valve when the temperature of the soleplate drops to a temperature below the second temperature, and the first bi-metal plate flexes away and closes the first valve when the temperature of the soleplate drops to a temperature below the first temperature. 
     
     
         3 . The steam iron as claimed in  claim 1 , wherein each of the first and second bi-metal plates comprises two overlaying metal plates with different thermal expansion coefficients. 
     
     
         4 . The steam iron as claimed in  claim 3 , further comprising first and second arms fixed to and extending from the first and second bi-metal plates for pushing the first and second valves respectively. 
     
     
         5 . The steam iron as claimed in  claim 1 , wherein each of the first and second valves comprises a spring for biasing the valve in a closed position. 
     
     
         6 . The steam iron as claimed in  claim 1 , wherein the first and second valves are seated on a platform mounted between the water tank and the vaporization chamber. 
     
     
         7 . The steam iron as claimed in  claim 1 , wherein the first and the second valves are operable in first and second valve openings respectively on a platform mounted on the vaporization chamber, and the platform is provided with first and second passageways through which water flows from the first and second valve openings to the vaporization chamber. 
     
     
         8 . The steam iron as claimed in  claim 7 , further comprising a water compartment having a first opening through which water flows from the water tank into the water compartment, and second and third openings in registration with the first and second valve openings respectively through which water flows from the water compartment into the first and second passageways and then into the vaporization chamber. 
     
     
         9 . The steam iron as claimed in  claim 1 , wherein the first and second bi-metal plates are supported on the vaporization chamber. 
     
     
         10 . The steam iron as claimed in  claim 1 , wherein the first temperature is about 100° C. 
     
     
         11 . The steam iron as claimed in  claim 1 , wherein the second temperature is about 140° C. 
     
     
         12 . The steam iron as claimed in  claim 2 , wherein the second bi-metal plate flexes away and closes the second valve when the temperature of the soleplate drops to about 130° C. 
     
     
         13 . The steam iron as claimed in  claim 2 , wherein the first bi-metal plate flexes away and closes the first valve when the temperature of the soleplate drops to about 95° C. 
     
     
         14 . The steam iron as claimed in  claim 1 , wherein the first volume of steam is generated at a rate of about 2 to 7 g/min. when the temperature of the soleplate reaches about 120° C. 
     
     
         15 . A steam iron comprising:
 a first valve assembly adapted to allow water to flow from a water tank into a vaporization chamber when a soleplate is heated to a first temperature; and   a second valve assembly adapted to allow additional water to flow from the water tank into the vaporization chamber when the soleplate is further heated to a second temperature.   
     
     
         16 . The steam iron as claimed in  claim 15 , wherein:
 the first valve assembly comprises:   a first valve through which water flows from the water tank to the vaporization chamber; and   a first bi-metal plate configured to flex towards and push the first valve open when the soleplate is heated by a heating element to the first temperature, allowing a first volume of water to flow from the water tank into the vaporization chamber and generate a first volume of steam for steam ironing delicate clothing; and   the second valve assemblies comprise:   a second valve through which water flows from the water tank to the vaporization chamber; and   a second bi-metal plate configured to flex towards and push the second valve open when the soleplate is further heated by the heating element to the second temperature, allowing an additional volume of water to flow from the water tank into the vaporization chamber and generate an additional volume of steam for steam ironing non-delicate clothing.   
     
     
         17 . The steam iron as claimed in  claim 16 , wherein the second bi-metal plate flexes away and closes the second valve when the temperature of the soleplate drops to a temperature below the second temperature, and the first bi-metal plate flexes away and closes the first valve when the temperature of the soleplate drops to a temperature below the first temperature. 
     
     
         18 . The steam iron as claimed in  claim 16 , wherein each of the first and second bi-metal plates comprises two overlaying metal plates with different thermal expansion coefficients. 
     
     
         19 . The steam iron as claimed in  claim 16 , wherein the first and the second valves are operable in first and second valve openings respectively on a platform mounted on the vaporization chamber, and the platform is provided with first and second passageways through which water flows from the first and second valve openings to the vaporization chamber. 
     
     
         20 . The steam iron as claimed in  claim 19 , further comprising a water compartment having an upper opening through which water flows from the water tank into the water compartment, and first and second lower openings in registration with the first and second valve openings respectively through which water flows from the water compartment into the first and second passageways and then into the vaporization chamber.