CZ9900771A3 - Electronic fuse preventing undesired changes in temperature of electrical and/or electrically controlled appliances - Google Patents

Abstract

An electronic cut-out preventing electric and/or electrically controlled consumers from undesirable temperature changes, consists of a high interrupting-capacity switch (HICS), connected between the source (S) of electric power and the consumer (C), and connected to an evaluating circuit (EC) which is connected to a temperature picking-up circuit, particularly thermosensor (TS), connected to the consumer (C) in a thermally conductive way. Between the consumer (C) and the source (S) of electric power, there is connected a thermoregulator (TR).

Description

Electronic fuse to prevent unwanted temperature changes of electrical and / or electrically operated appliances

Technical field

The invention relates to an electronic fuse to prevent unwanted temperature changes of electric and / or electrically operated appliances such as plastic welders, electric boilers, cookers, refrigerators, electric kettles, electrically operated boilers, irons and the like.

BACKGROUND OF THE INVENTION

Mechanical thermal fuses, emergency thermostats, blocking thermostats or temperature limiters have been used to ensure the safety of electrical and / or electrically operated appliances against undesired temperature changes that interrupt the power supply to the appliance when the temperature is undesirable. This prevents damage to the appliance, which also affects the safety of operation. The disadvantage of this solution is the unreliability of the said elements ensuring the safety of the appliance caused by the temperature cycles, which results in the gradual loosening of the mechanical joints of said safety elements. Another problem is the fuse trip tolerance of fuses due to, for example, the aging of metals used in safety devices. The unreliability is also caused by the liquid contained in some thermal fuse or emergency thermostat systems.

Thus, in extreme cases, the fuse may switch off prematurely or not at all. These defects affect the reliability of the fuse and affect the safety of the appliance and its operation.

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION The present invention provides an electronic fuse to prevent unwanted temperature variations. according to the invention, it consists of a power switch interposed between the power supply and the consumer and connected to an evaluation circuit which is connected to a temperature sensing circuit, in particular a temperature sensor, thermally conductively connected to the consumer. A temperature controller may advantageously be connected between the appliance and the power source. The evaluation circuit, the power switch and the temperature controller may advantageously have some electrical elements in common. The evaluation circuit may advantageously comprise a control algorithm of the microprocessor temperature controller. The temperature controller is preferably in a microprocessor design. The power switch preferably comprises an active switching element, for example a triac, a thyristor, a relay, a contactor or a selenoid. In case of an undesirable change of temperature, failure of the regulator or sensor, the evaluation circuit disconnects the voltage for the power switch, which interrupts the power supply (electric current, gas, diesel, etc.) to the appliance. The electronic fuse appliance according to the invention is reliable, non-defective and can operate over a wide temperature range.

Examples

BRIEF DESCRIPTION OF THE DRAWINGS In the following, the invention is illustrated in greater detail in the drawing, in which a block diagram of an exemplary electronic fuse circuitry according to the invention is shown.

The electronic fuse consists of a VS power switch and a VO evaluation circuit. The appliance S is supplied from the power supply Z. An RT temperature controller can be connected between the power supply Z and the appliance S. The output from the RT temperature controller is fed to the VS power switch. If the RT temperature controller is not used, the VS power switch can be connected directly to the Z power supply. The VS power switch is for example a triac, thyristor, relay, contactor or selenoid. The output of the VS power switch is * »to ·« • this • this «

«· ·« This to · * · • «• this to this ·

Appliance S is connected. The excitation of the VS power switch is brought from the evaluation circuit VO. The input of the VO evaluation circuit is connected to the temperature sensor of the heat pump. which is also connected to the RT temperature controller input. The RT temperature controller and the VO evaluation circuit may have some components in common, such as a microprocessor, integrated circuit, resistor, etc.

Industrial applicability

The electronic fuse according to the invention can be used in electrical and / or electrically operated appliances, for example in manual welding machines for welding plastic pipes, irons, cookers, refrigerators and the like.

Claims (5)

PATENT CLAIMS An electronic fuse to prevent unwanted temperature changes of electrical and / or electrically operated appliances, characterized in that it consists of a power switch (VS) interposed between the power supply (Z) and the appliance (s) and connected to the evaluation circuit (VO); which is connected to a temperature sensing circuit, in particular a temperature sensor (TC) thermally conductively connected to the consumer (S). Electronic fuse according to claim 1, characterized in that the power switch (VS) is a triac, a thyristor, a relay, a contactor or a selenoid. Electronic fuse according to claims 1 to 2, characterized in that a temperature controller (RT) is connected between the appliance (S) and the power supply (Z). Electronic fuse according to claims 1 to 3, characterized in that the evaluation circuit (VO), the power switch (VS) and the temperature controller (RT) have common electronic elements. Electronic fuse according to claims 1 to 4, characterized in that the evaluation circuit (VO) and possibly the temperature controller (RT) form a control algorithm of the microprocessor temperature controller.