Abstract A portable electrically operated gas heater for heating gases for use in curing sand molds. An electrical heating element fits tightly inside a bore in a heat exchange tube having sufficient mass for providing a reservoir for storage of a substantial amount of heat. The heat exchange tube is provided with fins on its outside and an inner shell fits around the fins to define a gas heating passage. An insulative outer shell is secured to the outside of the inner shell. An inlet port to the passage is provided for receiving cold gas from a pressurized source through a control valve and an outlet port from the passage is provided for distributing the gas after contact with the heat exchange fins in the passage. An automatic reset timer is connected to the control valve and is operative to open the valve for a predetermined period of time to deliver a burst of gas. Heater control means including a thermostat is provided for controlling the energization of the heating element to maintain a predetermined tempertaure within the gas heating passage. The heater control means is operable independently of the timer for continual energization of the heating element, under control of the thermostat, to store heat in the reservoir prior to delivery of a burst of gas by the timer. This storage of heat permits the use of a lower wattage heating element than would otherwise be necessary in order to instantaneously heat the burst of gas.
A portable gas heater for supplying intermittent bursts of heated gas, comprising: a. a generally cylindrical heat exchange tube having a central bore for receiving a heating element, said heat exchange tube having sufficient mass for providing a reservoir for storing a substantial amount of heat; b. an electrical heating element positioned within said bore, said heating element contacting said heat exchange tube in direct heat conduction relationship therewith; c. a cylindrical inner shell member coaxially positioned about said heat exchange tube but spaced apart therefrom to define a gas heating passage; d. an outer insulative shell attached to the outside of said inner shell; e. a plurality of heat exchange fins attached to the outside of said heat exchange tube and extending into said gas heating passage; f. means for conveying cold gas into one end of said gas heating passage and for conveying heated gas from the other end; g. a control valve connected to said conveying means for controlling the flow of gas therethrough; h. a control system including an adjustable automatic reset timer connected to said control valve, said timer operable when energized to open the control valve for a predetermined period of time to deliver a burst of gas; and i. heater control means including a thermostat for controlling the energization of said electrical heating element to maintain a predetermined temperature within said gas heating passage, said heater control means operable independently of said timer for continual energization of said electrical heating element under control of said thermostat, to store heat in said reservoir prior to delivery of a burst of gas by said timer.
Claim 2
Dependent Claim
270 words
A portable gas heater for supplying intermittent bursts of heated gas, comprising: a. a generally cylindrical heat exchange tube having a central bore for receiving a heating element, said heat exchange tube having sufficient mass for providing a reservoir for storing a substantial amount of heat; b. an electrical heating element positioned within said bore, said heating element contacting said heat exchange tube in direct heat conduction relationship therewith; c. a cylindrical inner shell member coaxially positioned about said heat exchange tube but spaced apart therefrom to define a gas heating passage; d. an outer insulative shell attached to the outside of said inner shell; e. a plurality of heat exchange fins attached to the outside of said heat exchange tube and extending into said gas heating passage; f. means for conveying cold gas into one end of said gas heating passage and for conveying heated gas from the other end; g. a control valve connected to said conveying means for controlling the flow of gas therethrough; h. a control system including an adjustable automatic reset timer connected to said control valve, said timer operable when energized to open the control valve for a predetermined period of time to deliver a burst of gas; and i. heater control means including a thermostat for controlling the energization of said electrical heating element to maintain a predetermined temperature within said gas heating passage, said heater control means operable independently of said timer for continual energization of said electrical heating element under control of said thermostat, to store heat in said reservoir prior to delivery of a burst of gas by said timer.