“An insole for a shoe comprising a system for converting the mechanical energy generated during walking into electrical energy”

Technical field

This invention relates to an insole for a shoe comprising a system for converting the mechanical energy generated during walking into electrical energy. More in detail, the invention relates to a shoe having an insole provided with a housing in which a generator for converting the mechanical energy produced during walking into electrical energy, in particular into electrical current, can be placed.

The invention is mainly applied in the field of electronics applied to the shoe industry.

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Prior art

Certain types of shoes which comprise internal systems for accumulating and exploiting the electrical energy produced are known in the art.

Normally, the electrical energy produced in these types of shoes exploits the physical properties of the materials capable of converting mechanical energy that stresses them, into electrical energy, for example the piezoelectric materials inserted inside the insole. More precisely, the piezoelectric element inserted inside the insole is subject to the pressure and torsion induced by the foot during walking, which cause such a mechanical deformation that produces a generation of electrical energy of a few microJoules.

However, the electrical energy produced is not enough to power a series of electronic modules dedicated to innovative applications such as for example foot massage, measurement of the foot impact with the ground and other surfaces, device charging via wireless connection and many others.

Object of the invention

The present invention aims to eliminate or at least reduce the drawbacks and disadvantages typical of the prior art and, therefore, to propose an insole for a shoe comprising a system for converting the mechanical energy generated during walking into electrical energy, which is able to electrically power one or more electrical or electronic devices.

In particular, an object of the present invention is to provide an insole for a shoe, in which the insole comprises an energy conversion system capable of generating a sufficient quantity of electrical energy in small spaces from the mechanical energy of walking, without compromising the comfort offered by the shoe itself.

The specified technical task and the specified objects are substantially achieved by an insole for a shoe comprising a system for converting the mechanical energy generated during walking into electrical energy, which comprises the technical characteristics set forth in claim 1. The dependent claims delineate some embodiments of the invention, in particular those considered advantageous. It should be highlighted that this summary introduces, in simplified form, a selection of concepts which will be further elaborated in the detailed description given below.

The invention relates to an insole for a shoe provided with at least one housing in which an energy conversion system can be inserted. In particular, this conversion system comprises at least one generator of electrical current arranged at least in a part of the housing to convert the mechanical energy generated during walking into electrical energy.

In particular, the generator of electrical current comprises a transducer apparatus and at least one compressible container, the latter being capable of containing a liquid or gaseous fluid capable of flowing towards said transducer apparatus since it is arranged in fluid communication with the compressible container itself.

In detail, the transducer apparatus has a box-shaped body which comprises at least one electrode and at least one polymer film, both lying on two substantially mutually parallel planes. The polymer film is movable between a first operating position, in which it distanced from the electrode, and a second operating position, in which it is in contact at least with the electrode.

The compressible container is configured to convey, when compressed during walking, a flow of fluid within the transducer apparatus for moving at least once said polymer film between the first operating position and the second operating position.

The alternating and repeated movement of the polymer film between the operating positions thereof produces a plurality of impacts of the latter with the electrode of the transducer apparatus. Advantageously, due to the triboelectric effect and electrostatic induction, these impacts generate on the electrode a quantity of electrical energy, in the form of alternating current, which can be used by an electrical or electronic device, such as for example a rechargeable battery, for the operation thereof. The quantity of electrical energy produced depends on the frequency with which the impacts on the electrode occur, on the contact surface between the polymer film and the electrode itself and, in addition, on the type of material used for making the electrode and the polymer film.

Therefore, the main advantages of the present invention include a high flexibility, a better miniaturization of the energy conversion system, a greater lightness, and a better integrability within a shoe.

According to an embodiment of the invention, the insole defines a separate body from the shoe and, therefore, is advantageously insertable into or removable from the latter for any maintenance, cleaning or other operations.

According to an alternative embodiment of the invention, the insole defines a single body with the shoe that comprises it. Brief description of the drawings

Further characteristics and advantages of the present invention will become clearer from the indicative, and therefore non-limiting, description of a preferred but not exclusive embodiment of an insole for a shoe comprising a system for converting the mechanical energy generated during walking into electrical energy, as illustrated in the appended drawings, in which:

- Figure 1 illustrates, according to a schematic view, an embodiment example of an insole for a shoe comprising a system for converting the mechanical energy generated during walking into electrical energy.

- Figure 2 illustrates, according to a perspective view, an embodiment example of the components that can be housed in the insole and configured to convert the mechanical energy of the steps into electrical energy;

- Figures 3a-3d illustrate, according to a side sectional view, embodiment examples of the generator that can be housed in the insole for energy conversion;

- Figure 4 illustrates, according to a top view, an embodiment example of an insole for a shoe comprising pressure sensors.

With reference to the drawings, they serve solely to illustrate embodiments of the invention with the aim of better clarifying, in combination with the description, the inventive principles on which the invention is based.

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Detailed description of preferred embodiments of the invention

This invention relates to an insole for a shoe comprising a system for converting the mechanical energy generated during walking into electrical energy. Any modifications or variants which, in the light of the description, are evident to the person skilled in the art, must be considered to fall within the scope of protection established by the present invention, according to considerations of technical equivalence.

Figure 1 illustrates a shoe which comprises an insole 1 provided with at least one housing 3 in which at least a part of a system for converting the mechanical energy generated during walking into electrical energy can be inserted.

Preferably, the insole 1 is composed of several layers of soft materials having shock-absorbing properties in order to preserve some of the components of the energy conversion system, such as for example some parts of the control electronics, inserted inside the housing 3 fashioned in the insole 1 itself.

Even more preferably, some of the layers of the insole 1 are made of expanded foams or the like to ensure a good cushioning during walking to offer the user a high sensation of comfort.

The conversion system comprises at least one generator 4 of electrical current, which is arranged in the housing 3 and is configured to convert the mechanical energy generated during walking into electrical energy.

Figure 2 illustrates a preferred embodiment of generator 4, which comprises a transducer apparatus 5 having a box-shaped body 6 and at least one compressible container 7 configured to contain a liquid or gaseous fluid and arranged in fluid communication with the box-shaped body 6 of the transducer apparatus 5.

In greater detail, at least a first electrode 8a and at least a first polymer film 9a are included inside the box-shaped body 6 of the transducer apparatus 5, both lying on two substantially mutually parallel planes (as illustrated in Figure 3a). Advantageously, the first polymer film 9a is movable between a first operating position, in which it is distanced from the first electrode 8a, and a second operating position, in which it is at least partially in contact with the first electrode 8a.

The compressible container 7, when compressed during walking, is configured to convey a flow of fluid within the transducer apparatus 5 for moving at least once the first polymer film 9a between the first operating position and the second operating position.

In this way, at each walking step, the pressure exerted by the foot on the insole 1 deforms the compressible container 7, which is configured as a pump to generate a flow of fluid. In other words, the compression of the latter generates a flow of fluid which, on entering the box-shaped body 6 with which it is in direct communication, induces the movement by fluttering of the first polymer film 9a between the first and second operating positions, alternately and repeatedly several times. Given the nature of the materials the first electrode 8a and the first polymer film 9a are made of, due to the triboelectric phenomenon and electrostatic induction, each impact of the first polymer film 9a with the first electrode 8a advantageously generates a quantity of electrostatic charge usable to power an electrical or electronic device possibly connected to the generator 4. The quantity of electrical energy produced, therefore, in addition to the frequency with which the impacts occur on the electrode and to the contact surface between the polymer film and the electrode itself, also depends on the type of material used to make the electrode 8a, 8b and the polymer film 9a, 9b.

According to an aspect of the invention, each electrode 8a, 8b is made of electronic and/or ionic conducting metal materials, or electronic and/or ionic conducting non-metal materials, or electronic and/or ionic conducting composite materials. Preferably, each electrode 8a, 8b is made of a metal material, including gold, copper, aluminium, or it is made of carbon-based materials, for example metal sheets coated with a layer of graphite or graphene.

According to another aspect of the invention, each polymer film 9a, 9b is made of a flexible and/or rigid plastic material, including preferably fluorinated ethylene propylene ("FEP"), polyethylene terephthalate ("PET"), polypropylene ("PP"), nylon (preferably nylon 6,6) and rigid (non- foaming) polyurethane, or it is made of composite materials, or it is made of natural fibrous materials, such as bamboo fibre or horsehair.

A possible choice of materials to be used for making the electrode 8a, 8b and the polymer film 9a, 9b is given by the advantageous coupling between aluminium and polypropylene.

According to an aspect of the invention, an electrical or electronic device is connected to the generator 4 for storing and/or using the electrical current generated by the latter. The electrical or electronic device is not necessarily arranged within the housing 3, as it could be hooked to a different or external point of the shoe or, alternatively, worn by an operator.

According to another aspect of the invention, the compressible container 7 consists of a structure that can be moulded by means of additive manufacturing techniques and can be made of flexible and/or elastic plastic materials, or of metal-plastic composite materials, or materials of natural origin. Preferably, the compressible container 7 is made of flexible polyurethane.

The compressible container 7 can have any shape that does not cause negative effects on the comfort of the shoe in which it is housed. Preferably, as illustrated in Figures 1 and 2, the compressible container 7 follows the shape of the front portion of the insole 1 , having a height of about 2 centimetres to define a containment volume of about 140cm ³ .

According to a further aspect of the invention, the box-shaped body 6 of the transducer apparatus 5 consists of a structure which can be moulded by means of additive manufacturing techniques. Furthermore, the box-shaped body 6 is made of rigid and/or flexible plastic materials, or metal materials, or materials of natural origin.

Preferably, the inside of the box-shaped body 6 is coated with a conductive layer, for example made of aluminium, so that the same internal surfaces define at least the first electrode 8a of the transducer apparatus 5. Figure 3b illustrates another embodiment example of the transducer apparatus 5, in which the latter comprises a second electrode 8b opposite the first electrode 8a with respect to the first polymer film 9a. Therefore, according to the present configuration, the first polymer film 9a is in contact with the first electrode 8a or with the second electrode 8b, when it is in the second operating position.

In this configuration, the aluminium layers (made in the form of a thin film) which cover the lower and upper walls of the box-shaped body 6 are electrically separated from each other so as to constitute the first electrode 8a and the second electrode 8b.

In this way, the movement of the first polymer film 9a following the formation of the flow of fluid leaving the compressible container 7 allows optimizing the production of electrical energy necessary to power an electrical or electronic device. The electrical energy is produced in the form of electrostatic electricity thanks to a correct potential difference that is established between both electrodes 8a, 8b and, possibly, the polymer film 9a, 9b.

According to an aspect of the invention, the transducer apparatus 5 comprises a plurality of transduction systems electrically connected in parallel with each other. In particular, each of these transduction systems comprises a pair of electrodes 8a, 8b between which at least one polymer film 9a is arranged.

Figure 3c illustrates an alternative embodiment example of the transducer apparatus 5, in which the latter comprises a conductive film 10 opposite the first electrode 8a with respect to the first polymer film 9a. In particular, the first polymer film 9a is in contact with the first electrode 8a or with the conductive film 10 when it is moved to the second operating position.

With reference to this configuration, the conductive film 10 is made of a flexible conductive material and, therefore, similarly to the polymer film, it is capable of vibrating between a first and a second operating position due to the flow of fluid coming from the compressible container 7.

Preferably, the first polymer film 9a is arranged integrally (for example by moulding or gluing or by any chemical-physical deposition technique on supports) to the respective first electrode 8a, so that only the conductive film 10 is movable due to fluttering.

Alternatively, the first polymer film 9a is made of a rigid material capable of maintaining a static position, while the conductive film 10 is made of a flexible conductive material capable of vibrating upon the passage of the flow of fluid.

Figure 3d illustrates a further embodiment example of the transducer apparatus 5, in which the layering of the materials is double and specular to that of Figure 3c.

In other words, the transducer apparatus 5 comprises a second electrode 8b and a second polymer film 9b opposite the first polymer film 9a and the first electrode 8a with respect to the conductive film 10. Each polymer film 9a, 9b is in contact with a respective electrode 8a, 8b or with the conductive film 10 when it is moved to the second operating position.

With reference to this configuration, the conductive film 10 is made of a flexible conductive material and, therefore, similarly to the polymer film, it is capable of vibrating due to the flow of fluid coming from the compressible container 7.

Preferably, each polymer film 9a, 9b is arranged integrally (for example by moulding or gluing) to the respective electrode 8a, 8b, so that only the conductive film 10 is movable due to fluttering.

Alternatively, the first polymer film 9a and/or the second polymer film 9b are made of a rigid material capable of maintaining a static position, while the conductive film 10 is made of a flexible conductive material capable of vibrating upon the passage of the flow of fluid.

According to an aspect of the invention, the first polymer film 9a and the second polymer film 9b are made of a flexible and/or rigid plastic material, for example polypropylene. According to an aspect of the invention, as previously anticipated with reference to Figure 3b but not limited thereto, the generator 4 comprises a plurality of transducer apparatuses 5, each of which is arranged in fluid communication with a respective compressible container 7 and with at least one electrical or electronic device.

According to an alternative aspect of the invention (not illustrated), the generator 4 comprises at least two compressible containers 7 opposite each other with respect to the transducer apparatus 5 and each in fluid communication with the latter. In other words, by describing an embodiment example, it is possible that the generator 4 comprises two compressible containers 7, arranged respectively at the toe and heel of the insole 1 , capable of powering a bidirectional transducer apparatus 5 interposed between them through the flow of fluid.

According to an aspect of the invention, the generator 4 is closed hermetically so that the liquid or gaseous fluid is completely confined within the compressible container 7 and the transducer apparatus 5. In other words, the generator 4 can be made as a closed system so as to prevent the exchange of material between its inside and the outside. This is advantageously useful when the fluid initially contained in the compressible container 7 is a liquid, for example a dielectric liquid, or an inert gas, for example argon, helium or nitrogen, which must not be dispersed outside the total containment volume of the generator 4 (i.e. the volume of the compressible container 7 and of the box-shaped body 6).

If the fluid used is ambient air, this arrangement for making a closed system need not necessarily be respected since the flow easily dispersed outside the generator 4 can also be introduced again. In fact, following the crushing of the compressible container 7, the depression that is formed inside it and the elastic properties of the material of which it is made tend to draw a flow of gaseous fluid (in this case ambient air) inside it.

According to an aspect of the invention, the fluid used by the generator 4 comprises an inert gas, preferably anhydrous, such as for example nitrogen, argon or helium.

In fact, the use of anhydrous gases (i.e. gases devoid of humidity) can advantageously improve the performance of the devices based on the triboelectric phenomenon thanks to the elimination of humidity, and therefore of the water molecules, present inside the fluid made to flow from the compressible container 7 towards the relative transducer apparatus 5.

According to an aspect of the invention illustrated in Figures 1 and 2, the generator 4 comprises at least one manifold 11 interposed between the transducer apparatus 5 and the compressible container 7. In particular, the manifold 11 has an inlet section 12 in fluid connection with the compressible container 7 greater than an outlet section 13 in fluid connection with the box-shaped body 6 for conveying the flow of fluid substantially at the polymer film 9a, 9b.

In other words, the manifold 11 is mainly configured to convey the flow of fluid from the compressible container 7 to the box-shaped body 6. In addition, given the difference in surface opening between the inlet section 12 and the outlet section 13, the manifold 11 is able to increase the speed of the flow of fluid and, therefore, to increase the movement frequency of the polymer film 9a, 9b and/or of the conductive film 10 between the first and second operating position. Advantageously, the greater the number of impacts that occur between the conductive surface (of the conductive film 10 and/or of the electrode 8a, 8b) the greater the quantity of electrostatic charge produced by the generator 4.

According to an aspect of the invention, the manifold 11 is made of flexible and/or elastic plastic materials, or of metal materials, or of materials of natural origin.

According to a further aspect of the invention, the manifold 11 and the compressible container 7 are made as two separate and connectable bodies. Alternatively, according to a further aspect of the invention, the manifold 11 and the compressible container 7 are made as a single body. Figure 4 illustrates a possible aspect of the invention, wherein the electrical or electronic device comprises an electrical energy storage element 14, preferably a rechargeable battery, and at least one sensor 15, preferably capacitive (cmut) or resistive (load cells), or piezoelectric pressure sensors, like in the podometric pads. The electrical energy storage element 14 is advantageously configured to store the electrical current produced by the generator 4, while the sensor is connected to the electrical energy storage element 14 to be powered thereby.

For example, the electrical or electronic device may comprise temperature, pressure, accelerometer sensors or a combination thereof.

According to an advantageous aspect of the invention, the electrical energy storage element 14 can be removed from the insole 1 so as to be more easily transportable and connectable to external electrical or electronic devices, such as for example smartphones or other.

According to another aspect of the invention, the electrical energy storage element 14 is integrated with the transducer apparatus 5 and, therefore, both are removable from the insole 1.

Preferably, the electrical energy storage element 14 has substantially the same surface extension as the transducer apparatus 5 and, therefore, it is arranged above or below it, in contact or connected with the relative surface of the transducer element 5 so as to define a single body.

According to an aspect of the invention, the insole 1 comprises a control unit 16 connected to the generator 4 and to the electrical or electronic device. In particular, the control unit is configured to manage the electrical current generated by the generator 4 and, in addition, to send command signals and to receive response signals with the electrical or electronic device.

In other words, the control unit has the purpose of managing the collection and the use of the electrical energy produced by the generator 4, in order to optimize the energy consumption of the electronic components of the system for converting the energy in question, that is, the electrical connection circuits, any communication modules and the sensors 15 connected.

According to another aspect of the invention, the control unit comprises a programmable processor for processing and/or combining between them the response signals received from the electrical or electronic device.

Preferably, the processor is programmable as a function of the type of sensors 15 present within the insole. In other words, one or more different software can be installed on the processor, each of which has the commands suitable for the management and communication of one or more sensors 15.

According to an embodiment of the invention, the insole 1 comprises a plurality of pressure sensors, each of which is arranged at a different area of the foot in order to detect the actual pressure exerted during walking. In this way, advantageously, the user is able to view, in real time or subsequently, a "heat map" of the pressure that the feet exert on the ground during running and walking. Specifically, the pressure sensors send the detected pressure data to the processor in order to send them to an external electrical or electronic device via a wireless communication module for the display thereof. Advantageously, the pressure data detected are processed, preferably by the external electrical or electronic device, to be converted into information understandable to the user (for example the intensity of the pressure is converted with a colour scale and associated with the correct position of the foot in which the sensor is located).

According to an alternative embodiment of the invention, the insole 1 comprises one or more location sensors (for example a GPS module and position accelerometers) configured to instantly detect, or at pre-set time intervals, the user's position and his difference in height. Once received by the processor, this information signal, containing for example the latitude and longitude coordinates, is configured to send this position signal to an external electrical or electronic device via the wireless communication module, if any, so that it can be reprocessed to be associated with a geographical map in which a history of the positions and/or the current positioning of the user is saved.

According to a further aspect of the invention, the control unit comprises a wireless communication module configured to send the command signals or to receive the response signals from the electrical or electronic device. In particular, the wireless communication module is connected to a control panel external to the shoe and, moreover, is configured to send at least the response signals to the latter.

In other words, the wireless communication module is configured to interface the control unit with the electrical or electronic device, in particular any sensors 15 it comprises, to send command signals to the latter and to receive its response signals to be forwarded, before or after any processing, to an external control panel, for example a tablet or smartphone, which can be used by an operator.

According to a possible aspect of the invention, the wireless communication module can be an infrared IR system, or a Bluetooth module, or a wireless module, or a fixed frequency radio module, or an XBEE module, or a GPRS-UMTS module, or an NFC module.

According to an aspect of the invention, the processor is programmed to generate a warning signal to be sent via the wireless communication module to any operator, for example the user of the insole 1 or a different person, in order to alert the latter that at least one of the sensors 15 arranged in the insole 1 is detecting a signal that is not congruent with a pre-set value.

In other words, the processor is configured to send alert messages and/or notifications to an external electrical or electronic device, if at least one of the sensors detects a specific signal, for example of pressure or positioning, which is not congruent with those pre-set in the processor. For example, if it is detected that the user's positioning coincides with a forbidden or dangerous access zone, the processor is configured to generate an alarm signal that the wireless communication module will send at least to the user himself.

According to an aspect of the invention, the insole also comprises a rectifier device configured to convert the generated electrical current from alternating to direct current.

Preferably, the rectifier device is included in the control unit or in the electrical or electronic device or in the electrical energy storage element 14.

In this way, the electrical current produced by the generator 4 by means of the triboelectric and electrical induction effect can advantageously be stored in an electrical energy storage element 14, which has the purpose of accumulating electrical energy until a minimum level is reached that is sufficient to activate further electrical or electronic devices, such as for example the sensors.

According to another aspect of the invention, the control unit comprises an electronic latch module configured to inhibit the electrical energy storage element 14 from releasing a quantity of electrical energy contained, if the quantity of electrical energy contained is lower than a pre fixed level.

In other words, only after the electrical energy storage element 14 has stored a minimum quantity of electrical energy, controlled by the electronic latch module, it will be able to power the other electrical or electronic devices connected thereto, such as for example the sensors.

It appears clear that, with respect to the solutions of the prior art, the insole 1 according to the present invention features an important innovation constituted by the presence of the system for converting the mechanical energy of walking into electrical energy by exploiting the triboelectric effect and/or the fluttering effect, preferably the combination thereof. Advantageously, therefore, the insole 1 arranged in the shoe is capable of powering different types of electrical or electronic devices connected thereto.

According to alternative aspects of the invention (not illustrated), the electrical or electronic device can comprise an electrical energy storage element 14, or a two-dimensional matrix of capacitive or resistive pressure sensors (the sensors 15 described above), or a heating resistance, a fan or a Peltier cell, or vibrating actuators, or a GPS module and/or at least one accelerometer, or a series of electro-stimulation electrodes, or a waveform generator, or an active tag, or a speaker or a base circuit and an antenna for wireless charging of electronic devices.

Some of the above-mentioned electrical or electronic devices are described below.

One aspect of the invention provides that the insole 1 is used to cool the foot. In this case it is possible to insert inside the insole 1 some vent grids (for example shape memory grids that vary in size according to the mechanical load to which they are subjected) and a fan powered by the battery, or a Peltier cell.

Another aspect of the invention provides that the shoe can be provided with vibrating actuators with 5V offset flywheel (of the type used to obtain vibration on mobile phones), located in the points of greatest accumulation of stress on the foot. In this case, a massaging effect is achieved on the foot during walking.

A further aspect of the invention provides that the processor power terminals themselves interact with electrodes located on the surface of the insole 1. In this way an electrostimulation of the foot is carried out by means of controlled current pulses (for example at 5V and 20mA).

One aspect of the invention provides that the processor interfaces with a waveform generator. In this case, a low intensity shock wave therapy is carried out by means of a pair of plates on the surface.

Another aspect of the invention provides that an active tag is inserted in the insole 1. In this case the entire shoe becomes a badge that can be marked by receiving systems.

A further aspect of the invention provides for the arrangement of an accelerometer in the insole 1 so as to interface the shoe with a speaker or with an acoustic headset. Therefore, the same shoe becomes a speaking pedometer or in any case able to emit sounds during movement. Similarly, by further adding a GPS or RFID module, the shoe turns into a talking chronometer.

An aspect of the invention provides for the arrangement of a base circuit and a super-wound antenna for wireless charging (and possibly providing the shoe with a USB connector) so as the shoe becomes an automatic device for recharging devices during walking, in particular of mobile phones.