RU226329U1 - FLEXIBLE HEATER FOR SHOE INSOLES - Google Patents

Abstract

The utility model relates to the shoe and sports industry. A flexible heater for shoe insoles consists of two conductors, insulated from one another, with different resistances, interconnected and located together in one flexible insulating tube. The heating nichrome conductor is located parallel to the current-carrying conductor in insulation. Technical result: increasing the reliability of the heater, ensuring long-term operation of the insoles. 2 ill.

Description

The utility model relates to shoe insoles heaters built into shoes for heating feet in the cold season, powered from low-voltage power sources suitable for charging mobile phones, tablets, etc., having a voltage of 5 volts.

Currently, heated insoles are available for sale, with heating elements consisting of woven and non-woven carbon fiber material. The disadvantage of this material is that with active use of insoles, this heating material breaks off, reducing the cross-section of the conductor, and subsequently completely fails, since it has a fragile structure and does not tolerate frequent bending in one place.

The closest to the claimed utility model is a household electric heater (patent RU 97624 U1, September 20, 2010), containing a heating element with a cord connecting to a power source and an operating mode switch placed on it, characterized in that the heating element is designed with overheating protection the entire length and is a flexible heating wire enclosed on top in elastic insulation, containing a copper current-carrying wire, covered with an insulating layer, on top of which a heating spiral of nichrome wire is wound, and the melting temperature of the insulating layer of the current-carrying wire is below 70 ° C and below the temperature of the heating coil and elastic insulation of the heating element having a melting point above 100°C.

However, this heater is suitable for the production of heating devices that do not have serious loads, such as electric blankets, etc., but is not suitable for embedding in shoe insoles, which have much larger loads. The reason for this is a nichrome wire wound onto an insulated current-carrying core. It has been experimentally proven that a wound nichrome wire breaks off from regular bending of the heater in one place, the reason for this is that during the manufacture of this heater, it is possible to wind a nichrome wire only onto a straight insulated current-carrying core, and when bending it to small radii for installation in shoe insoles, the winding weakens on the inner radius and tension on the outer radius, as a result of which, with active walking, and therefore frequent bending of the insole in one place, the nichrome heater is destroyed and the entire heater fails.

The author also proposes to make the insulation of the current-carrying core from a material whose melting point is below 70 ° C, to protect against uncontrolled heating, by melting the shell and short circuiting, as a result of which the fuse blows. However, the use of this insulation in a flexible heater for a shoe insole is not advisable, both from an economic component and for safety reasons, since it is assumed that the inventive heater is connected to a low voltage source of 5 V and heating in idle mode does not exceed 60°C, and when using insoles directly, with the inventive heater, it is even lower since it has a low heat capacity and part of the heat is dissipated into the foot and sole of the shoe.

The task to be solved by the claimed utility model is to increase the reliability and, therefore, longer service life of electrically heated insoles.

This problem is solved due to the fact that the claimed flexible heater for a shoe insole, which consists of two conductors with different resistances, connected to each other on one side and located in one insulating flexible tube, which can be a heat-shrinkable tube. One conductor consists of copper or its alloy, insulated, the other of a nichrome conductor located parallel to the current-carrying conductor, on the free ends, on the other side of these conductors electricity is supplied with a voltage of 5 V through extension wires.

The technical result provided by the given set of features is that this heater is flexible and thin enough to be installed in the insole of a shoe, and at the same time durable enough for use in this area. The strength of this heater is ensured by a copper conductor insulated with a much larger cross-section than the heating filament itself, and located together in a heat-shrinkable tube, which prevents creases in the heater (and therefore the thinner nichrome conductor) located in the insole.

The power of this heater varies depending on its length. For example, a heater with a length of 600 mm and a 0.3 mm nichrome thread used in it has a resistance of 5 Ohms. Using Ohm's law formula to calculate power, we find out that this heater at a voltage of 5 V has a power of 5 W at a current of 1 A, which allows the heaters to be powered from the voltage supplied by portable battery chargers.

The temperature generated by the heater is not enough for the heater to self-destruct by melting the insulation of a wire or heat-shrinkable tube, but it is sufficient to heat the foot. On average, the heater temperature does not exceed 60°C, but since the heater has a low heat capacity, most of the heat is dissipated into the foot.

The essence of the utility model is illustrated by figures that depict:

Fig. 1 - Heater device

1. Nichrome conductor

2. Heat shrink

3. Conductor insulation

Fig. 2 - Example of installing a heater in an insole

Making a flexible heating element for the insole:

on one side, free the copper conductor from the insulation, long enough to attach the nichrome heating conductor to it;

connect the nichrome conductor;

insert both wires parallel to each other into one heat-shrinkable tube so that the connected part is completely hidden in the tube, which is almost equal to the length of the entire future heater, leaving on the other side the outgoing wires sufficient for connection to the power wires;

heat the heat shrink tube until it shrinks completely so that it is completely adjacent to the two wires placed in it;

solder one side of the heat shrink tube, on the opposite side from the wires coming out of it, by heating with an open flame and squeezing the tube. This ensures the tightness of the entire heating element.

The heater is ready to be connected to the power wires (Fig. 1).

An example of installing a flexible heater in an insole.

To ensure that the heater mounted in the insole does not cause inconvenience when walking, it should be installed in pre-prepared zigzag grooves (Fig. 2) located across the insole, which reduces the load caused by transverse bending on the heating element. These grooves can be made in various ways (depending on the materials used), such as burning on CNC laser machines, or molded by casting on automated equipment. Thus, the insole forms one, two or three layers, depending on the manufacturing method.

Claims (1)

A flexible heater for a shoe insole, which consists of two conductors, insulated from one another, with different resistances, interconnected and located together in one flexible insulating tube, characterized in that the heating nichrome conductor is located parallel to the current-carrying conductor in insulation.

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