IP Library › Granted Patent US 12,498,141
Granted Patent B2
US 12,498,141 · App. 17/851,591 · Granted Dec 16, 2025

Tiltable radiant heater

Inventors: Charles F. Caldwell (Eau Claire, WI); Brian Ruben (Eau Claire, WI)
Assignee: National Presto Industries, Inc.
F24H3/0417F24H9/1863
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Quick Facts
Patent No.
US 12,498,141
App. No.
17/851,591
Granted
Dec 16, 2025
Kind
B2
Abstract

Disclosed is a portable radiant heating device that has a base, a radiant heat source mounted in a tiltable reflector, and a safety interlock device located in the base. The safety interlock uses a pressure-sensitive foot that prevents the heater from producing infrared heat when not in contact with a mounting surface. The safety interlock device also prevents the heater from producing infrared heat when the reflector is not tilted so as to prevent excessive amounts of infrared heat from being directed towards the mounting surface.

Claims (50)

1 . A safety interlock system for a portable radiant heating device, the system comprising:

a disconnect switch;

an engagement finger;

a plunger shaft; and

a plunger foot;

wherein the plunger shaft comprises a first flange, a second flange, and a recess formed between the first and second flange;

wherein the plunger shaft is movably attached to the plunger foot, the safety interlock system further comprising a second spring which exerts a spring force against the plunger shaft such that plunger shaft is held in a first position by the spring force, the plunger shaft movable to a second position when the spring force is overcome; and

wherein an actuator of the disconnect switch is actuated by the second flange when the portable radiant heater is in a normal condition such that the disconnect switch is closed.

2 . The safety interlock system of claim 1 , further comprising a first spring which applies a force to the plunger foot such that it extends from a base portion of the portable heating device.

3 . The safety interlock system of claim 2 , wherein the actuator of the disconnect switch is de-actuated when the plunger foot extends from the base portion of the portable heating device such that the disconnect switch is opened.

4 . The safety interlock system of claim 1 , wherein the disconnect switch is de-actuated when the plunger shaft is in the second position.

5 . The safety interlock system of claim 4 , wherein the engagement finger contacts the plunger shaft to cause the plunger shaft to be in the second position.

6 . The safety interlock system of claim 1 , further comprising a plunger collar, the plunger collar configured to trap the plunger shaft between the plunger collar and the plunger foot.

7 . The safety interlock system of claim 6 , the plunger collar rotationally aligning the plunger shaft with the plunger foot and adapted to allow the plunger shaft to move from a first position to a second position.

8 . The safety interlock system of claim 7 , the plunger foot comprising alignment fins to rotationally align the plunger foot with a radiant heater base, the radiant heater base comprising a mount for the disconnect switch such that the disconnect switch is rotationally aligned with the second flange of the plunger shaft.

9 . A portable electric heater comprising:

a heater assembly comprising:

a reflector;

a heating element;

a grating; and

an engagement finger;

a base flexibly connected to the heating assembly such that the heating assembly can be tilted from a storage position to a heating position, the base comprising:

a disconnect switch;

a plunger shaft; and

a plunger foot;

wherein the plunger shaft comprises a first flange, a second flange, and a recess formed between the first and second flange;

a first spring which applies a force to the plunger foot such that the plunger foot extends from the base portion of the portable heating device when the base portion is not in contact with a placement surface;

wherein the plunger shaft is movably attached to the plunger foot, the safety interlock system further comprising a second spring which exerts a spring force against the plunger shaft such that plunger shaft is held in a first position by the spring force, the plunger shaft movable to a second position when the spring force is overcome;

wherein an actuator of the disconnect switch is actuated by the second flange when the portable radiant heater is in the heating condition such that the disconnect switch is closed; and

wherein the actuator of the disconnect switch is de-actuated when the plunger foot extends from the base portion of the portable electric heater device such that the disconnect switch is opened.

10 . The portable electric heater of claim 9 , wherein the disconnect switch is de-actuated when the plunger shaft is in the second position.

11 . The portable electric heater of claim 10 , wherein the engagement finger contacts the plunger shaft causing the plunger shaft to be in the second position when the heating assembly is in the storage position.

12 . The portable electric heater of claim 9 , further comprising a plunger collar, the plunger collar configured to trap the plunger shaft between the plunger collar and the plunger foot.

13 . The portable electric heater of claim 12 , the plunger collar rotationally aligning the plunger shaft with the plunger foot and adapted to allow the plunger shaft to move from a first position to a second position.

14 . The portable electric heater of claim 13 , the plunger foot comprising alignment fins to rotationally align the plunger foot with a radiant heater base, the radiant heater base comprising a mount for the disconnect switch such that the disconnect switch is rotationally aligned with the second flange of the plunger shaft.

15 . A method of preventing the operation of a portable electric heater when the heater is in a storage configuration, the method comprising:

providing a portable electric heater, the heater comprising:

a heater assembly, the heater assembly further comprising:

a reflector;

a heating element;

a grating; and

an engagement finger;

a base flexibly connected to the heating assembly such that the heating assembly can be tilted from a storage configuration to a heating configuration, the base comprising:

a disconnect switch;

a plunger shaft; and

a plunger foot;

wherein the plunger shaft comprises a first flange, a second flange, and a recess formed between the first and second flange;

wherein the plunger shaft is movably attached to the plunger foot, the safety interlock system further comprising a second spring which exerts a spring force against the plunger shaft such that plunger shaft is held in a first position by the spring force, the plunger shaft movable to a second position when the spring force is overcome; and

contacting the plunger shaft with the engagement finger to cause the plunger shaft to be in the second position when the heating assembly is in the storage position, the disconnect switch opens to prevent a flow of electrical power to the heating element when the plunger shaft is in the second position.

16 . The method of claim 15 , wherein the plunger shaft is movably attached to the plunger foot, the base further comprising a spring which exerts a spring force against the plunger shaft such that plunger shaft is held in a first position by the spring force, the plunger shaft movable to the second position when the spring force is overcome.

Assignments (1)
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Aug 22, 2022
From: CALDWELL, CHARLES F.; RUBEN, BRIAN
To: NATIONAL PRESTO INDUSTRIES, INC.
Reel/Frame 060858/0811 →
Continuity (2)
Provisional Application 63224042 · Jul 21, 2021
Related Publication 20230028879A1 · Jan 26, 2023
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