Abstract Electrical heating devices and methods for making same comprising plastic material having a positive temperature resistivity coefficient (PTC) provided with an insulating plastic encapsulent in which foraminous terminal strips are employed for making electrical connection with the PTC material. The PTC plastic material coalesces with the plastic material of the insulating encapsulent through the openings in the foraminous terminal strips to firmly and permanently maintain the terminal strips in good electrical connection with the PTC material. Several embodiments are shown including tubular configurations in which the terminal strips are either wound around the PTC material with a particular spacing and pitch to control the resistivity of the device, or are located at both inner and outer peripheral surfaces of the PTC material, and a web configuration with terminal strips in clamping engagement with opposite ends of the web or on opposite faces thereof. Also disclosed is a heating device comprising a tubular element formed with a series of bends between terminal elements.
A self-regulating heater comprising: a. an elongated tubular PTC element having an outer sleeve of electrically insulating material and having a plurality of bends; and b. means including two electrically conductive members having piercing means adapted to pierce through the sleeve into the PTC element, one conductive member connected to even numbered bends, the other connected to odd numbered bends, to apply voltage across the bends of the PTC element whereby resulting current flow will cause the PTC element to heat up until an electrical thermal equilibrium is reached limiting the temperature of the element.
Claim 2
Dependent Claim
95 words
A self-regulating heater comprising: a. an elongated tubular PTC element having an outer sleeve of electrically insulating material and having a plurality of bends; and b. means including two electrically conductive members having piercing means adapted to pierce through the sleeve into the PTC element, one conductive member connected to even numbered bends, the other connected to odd numbered bends, to apply voltage across the bends of the PTC element whereby resulting current flow will cause the PTC element to heat up until an electrical thermal equilibrium is reached limiting the temperature of the element.
Claim 3
Dependent Claim
27 words
A heater according to claim 1 in which the PTC element has an inner sleeve of electrically insulating material and the conductive members comprise channel shaped clamps.
Claim 4
Dependent Claim
21 words
A heater according to claim 2 wherein the piercing means comprise tubular elements having sawtoothed piercing edges on an end thereof.
Claim 5
Dependent Claim
20 words
A heater according to claim 3 further comprising: c. electrical insulating couplings attached to each end of said tubular element.