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US 5,854,584 AGranted
Protective device against thermal overload for a small high-heat-load electric motor
OwnerDieter Rogeleininventor
Life of this patent
Estimating the term…
Abstract
A device for protecting a fractional-horsepower motor from overheating. The motor is intended to accommodate a high heat load. Its power supply accommodates a make-or-break switch. A bimetal component opens the switch once a certain temperature has been attained. The bimetal component is mounted on a support. The switch, the bimetal component, and its support are electrically connected in series. There is a specific ratio between the electrical impedance and heat capacity of the bimetal component and those of its support, and they are extensively in surface-to-surface contact.
Claims9
A device for protecting a fractional-horsepower motor from overheating when accommodating a high heat load, comprising:
- a make-or-break switch;
- a bimetal component for opening said switch, suddenly once a specific temperature has been attained;
- a support for mounting said bimetal component and having at least one part;
- said switch, said bimetal component, and said support being electrically connected in series;
- said bimetal component having an electrical impedance and a heat capacity that have a specific ratio to the electrical impedance and heat capacity of said support, said bimetal component and said support being in extensive surface-to-surface contact;
- said support being flat and radiating heat toward said bimetal component;
- said ratio being dimensioned so that switching cycles following a maintenance time determined by when the motor is first turned on and when said motor is first turned off due to overheating, provide an increasingly shorter switching-on duration as an overload continues at constant current and have an increasing ratio of switch-off duration to switch-on duration, ratios of electrical resistance and heat storage capacity of said bimetal component and said support being measured with said support comprising a large-area heat radiator, so that a stop time determined on initial switch-on of the motor and a first heat-overload switch-off with continuing overload and constant current sets an increasingly shorter switch-on duration for subsequent switching cycles and an increasing ratio of switch-off duration to switch-on duration;
- support being in form of a flat heat radiator substantially planar parallel to and overlapping to an extent at least one of two surfaces of said bimetal component while remaining slightly off said bimetal component the ratio of the heat-storage capacities of said support to the storage capacities of said bimetal component are at least 1.5:1 to 3.5:1, the ratio of said electrical impedance of said support to the electrical impedance of said bimetal component being at least 4:1 to 8:1.
5 more elements
A device for protecting a fractional-horsepower motor from overheating when accommodating a high heat load, comprising:
- a make-or-break switch;
- a bimetal component for opening said switch, suddenly once a specific temperature has been attained;
- a support for mounting said bimetal component and having at least one part;
- said switch, said bimetal component, and said support being electrically connected in series;
- said bimetal component having an electrical impedance and a heat capacity that have a specific ratio to the electrical impedance and heat capacity of said support, said bimetal component and said support being in extensive surface-to-surface contact;
- said support being flat and radiating heat toward said bimetal component;
- said ratio being dimensioned so that switching cycles following a maintenance time determined by when the motor is first turned on and when said motor is first turned off due to overheating, provide an increasingly shorter switching-on duration as an overload continues at constant current and have an increasing ratio of switch-off duration to switch-on duration, ratios of electrical resistance and heat storage capacity of said bimetal component and said support being measured with said support comprising a large-area heat radiator, so that a stop time determined on initial switch-on of the motor and a first heat-overload switch-off with continuing overload and constant current sets an increasingly shorter switch-on duration for subsequent switching cycles and an increasing ratio of switch-off duration to switch-on duration;
- support having zones defined by shaping of specific areas to determine electrical impedance and heat conductivity of said support.
5 more elements
Dependencies are inferred from the claim text.