Patent ID: 11913736
Assignee: WATLOW ELECTRIC MANUFACTURING COMPANY
Field: Thermal processes and apparatus (Mechanical engineering)
Classification: CPC F  H | IPC F

Claim 19:
20. A heater assembly comprising:
a flow guide defining a continuous geometric helicoid disposed about a longitudinal axis of the heater assembly, the flow guide defining a predetermined pattern of perforations that extend in a longitudinal direction through a first longitudinal length of the geometric helicoid, the longitudinal direction being parallel to the longitudinal axis, wherein the first longitudinal length is less than a full longitudinal length of the geometric helicoid such that the electrical resistance heating elements do not extend through a portion of the geometric helicoid that is farther in the longitudinal direction than the first longitudinal length; and
a plurality of electrical resistance heating elements extending through the perforations, each electrical resistance heating element of the plurality of electrical resistance heating elements includes a first region with a first watt density and a second region with a second watt density, the second region being located farther in the longitudinal direction than the first region, the second watt density being less than the first watt density, and wherein the second region includes an end portion of the electrical resistance heating element,
wherein each electrical resistance heating element includes a resistance element, a sheath surrounding the resistance element, and an insulating material between the resistance element and the sheath and electrically insulating the resistance element from the sheath, wherein the resistance element has a lower resistance in the second region,
wherein the resistance element includes a resistance coil in the first region,
wherein, in the second region, the resistance element includes either a resistance coil having a longer pitch than the resistance coil of the first region or a pin,
wherein the plurality of electrical resistance heating elements includes a first set of electrical resistance heating elements and a second set of electrical resistance heating elements, the end portion of each electrical resistance heating element of the first set is farther in the longitudinal direction than the end portion of each electrical resistance heating element of the second set, wherein the end portions of the electrical resistance heating elements of the second set are located further along a helical flow path defined by the geometric helicoid than the end portions of the electrical resistance heating elements of the first set.