DESCRIPTION

The present invention relates to a portable electrical energy recovery device.

Implantable devices are currently known such as neurostimulators and pacemakers which require electrical energy for their operation.

The electrical energy is supplied by batteries and primary accumulators which are, however, sources with a limited duration, placing a time limit on the use of the implantable devices themselves.

The technical task which the present invention sets itself is, therefore, to create a portable electrical energy recovery device which makes it possible to eliminate the technical drawbacks complained of in the prior art.

Another object of the invention is to create a portable electrical energy recovery device which can be used as an alternative source of electrical energy or that is complementary to a battery or primary accumulator.

Another object of the invention is to create a portable electrical energy recovery device which can be integrated into an implantable medical device so as to increase the duration of time for which it can be used.

Another object of the invention is to create a compact and light portable electrical energy recovery device with high energy recovery efficiency.

The technical task and these and other objects according to the present invention are reached by making a portable electrical energy recovery device comprising an electrical energy generation unit, and a recovery, conversion and storage unit for the energy produced by the generation unit, characterised in that said generation unit comprises an oscillating system comprising at least one magnetic mass with linear oscillation, at least one elastic radial recall element with angular oscillation, connection and transformation means of said at least one magnetic mass into an angular oscillation of said at least one elastic recall element and vice versa, and a fixed magnetic induction module magnetically coupled with said at least one magnetic mass.

In a preferred embodiment of the invention, said at least one magnetic mass comprises a pile of magnets arranged with the magnetic poles of the same sign facing each other.

In a preferred embodiment of the invention, said oscillating system has its own frequency comprised between 1 and 2 Hz so as to resonate with the frequency of the vertical acceleration movement produced by a human being walking.

In a preferred embodiment of the invention, said magnetic induction module comprises a plurality of electric windings connected to one another in parallel and wound around said pile of magnets.

In a preferred embodiment of the invention, said elastic recall element comprises a spiral spring having a first end fixed to a fixed anchoring element and a second end connected to said oscillating mass through said connection and transformation means.

In a preferred embodiment of the invention, said connection and transformation means comprise a curved leverage.

In a preferred embodiment of the invention said connection and transformation means comprise a locking element of the radial distance between said first end and said second end of said spiral spring.

In a preferred embodiment of the invention said anchoring element is configured like a pin, and said locking element is configured like a wheel coaxially assembled on said pin, said second end of said spiral spring and said leverage being connected to the edge of said wheel.

In a preferred embodiment of the invention two identical elastic recall elements are provided, arranged symmetrically to balance the thrusts acting on the magnetic mass in the transversal direction to its sliding direction.

In a preferred embodiment of the invention, the interface between components of said connection and transformation means in reciprocal relative movement is formed by a hard metal in contact with a self-lubricating soft metal.

In a preferred embodiment of the invention said recovery, conversion and storage unit comprises an AC/DC rectifier circuit, a DC/DC voltage converter operating with MPPT (Maximum Power Point Tracking) logic, a charge regulator, an accumulator and a voltage reconverter.

In a preferred embodiment of the invention said recovery, conversion and storage unit is formed by integrated electronics on a printed circuit board that acts as a containing support for said at least one elastic recall element and for said connection and transformation means.

Further characteristics and advantages of the invention will more fully emerge from the description of a preferred but not exclusive embodiment of the portable electrical energy recovery device according to the invention, illustrated by way of indicative and non-limiting example in the accompanying figures of the drawings, in which:

figure 1 shows a partially disassembled view of the portable electrical energy recovery device;

figure 2 shows a partially disassembled view of the assembly formed by the elastic radial recall elements and the connection and transformation means of a linear oscillation of the magnetic mass into an angular oscillation of the elastic recall elements;

figure 3 shows a view of the magnetic mass;

figure 4 shows an exploded view of the fixed magnetic induction module;

figure 5 shows an exploded view of the linear guide means for the sliding of the magnetic mass;

figure 6 is a plan view of the assembly formed by the elastic radial recall elements and the connection and transformation means;

figure 7 is a sectional view along the line A-A of figure 6 of the assembly formed by the elastic radial recall elements and the connection and transformation means; figure 8 shows a functional diagram of the recovery device,

figure 9 shows an assembled plan view of the portable electrical energy recovery device; and

figure 10 shows the portable electrical energy recovery device sectioned along the line A-A of figure 9.

With reference to the mentioned figures, a portable electrical energy recovery device is shown.

Below we shall make reference to a portable electrical energy recovery device that can be integrated into an implantable electrostimulator such as a pacemaker or a neurostimulator device, but the device can also be applied in different areas where electrical energy recovery is required for supplying a portable device.

The energy recovery device in the case in question is able to convert and store the energy produced in a buffer element (secondary battery) which, along with the primary battery, represents the power supply source of the pacemaker or neurostimulator 50.

The recovery device comprises an electrical energy generation unit 1 and a recovery, conversion and storage unit 2 for the energy produced by the generation unit 1.

The generation unit 1 in turn comprises an oscillating system comprising a magnetic mass 3 with linear oscillation, at least one and preferably two elastic radial recall elements 5 with angular oscillation, connection and transformation means 6 of a linear oscillation of the magnetic mass 3 into an angular oscillation of the elastic radial recall elements 5 and vice versa and a fixed magnetic induction module 4 magnetically coupled with the magnetic mass 3.

The magnetic mass 3 comprises a pile of magnets 7 arranged with the magnetic poles of the same sign facing each other.

The magnets 7 have a quadrangular outline.

The pile of magnets 7 is oriented with its longitudinal axis in a substantially vertical direction when the recovery device is being used so as to oscillate vertically along its longitudinal axis.

The magnetic induction module 4 comprises a plurality of electric windings 10 mechanically separated by spacers 9 and electrically connected to one another in parallel and wound around the pile of magnets 7.

The electric windings 10 have a quadrangular outline corresponding to that of the magnets 7.

The spacers 9 protect the electric windings 10 and are rigidly connected to each other through fixing pins 17.

A further safety retaining element 11 rigidly connects all the spacers 9 still through fixing pins 17.

The electric windings 10 within which the magnetic poles of the magnetic mass 3 slide are crossed by a variable magnetic flux which generates an induced voltage from which the energy recovery is obtained.

The electric windings 10 wind the pile of magnets 7 with a gap preferably no larger than lOOum and their arrangement allows the use of a magnetic circuit to be avoided and the consequent problems related to the reluctant forces that could introduce parasitic braking forces and therefore a reduction in recoverable energy. More precisely, the magnetic mass 3 comprises a sequence of NdFeB permanent magnets 7 alternating with FeCo ferromagnetic laminae 8. The alternation of identical poles (S-S, N-N) facing the ferromagnetic laminae 8 produces a sum of the magnetic flux of the poles, inducing large peaks and substantial variations in the flux itself. The vertical sliding of the outer edge of the pile of magnets 7 causes a sudden variation in the magnetic induction flux in the electric windings 10. This variation in the magnetic induction flux is even more necessary the lower the oscillation frequency of the oscillating system. In fact, the energy produced and recovered depends (according to Faraday's Law) on the flow variation per unit of time.

The pile of magnets 7 is slidably coupled along linear guides 13 integrated in two longitudinally hollow longitudinal blocks 14 and 15 which also act as load-bearing structures for the entire recovery device.

The blocks 14 and 15 have a quadrangular outline and form two juxtaposed lengths.

The linear guides 13 are more precisely afforded on the inner side of specific bushings 16 fixed into the longitudinal cavity of the blocks 14 and 15.

The outer surface of the bushings 16 matches the inner surface of the blocks 14 and 15, whereas the inner surface of the bushings 16 has linear guides 13 in the form of a series of longitudinal projections along which the pile of magnets 7 slides.

The magnetic induction module 4 is also fixed into the longitudinal cavity between the block 14 and 15 in such a position as to wind an intermediate section of the pile of magnets 7 when the magnetic mass 3 is resting.

The oscillating system described above has its own frequency comprised between 1 and 2 Hz so as to resonate with the frequency of the vertical acceleration movement produced by a human being walking.

The elastic recall element 5 comprises a spiral spring 18 having a first end 24 fixed to a stationary anchoring element 19 and a second end 25 connected to the oscillating mass 3 through the connection and transformation means 6.

The spiral spring 18 is formed by a lamina.

The connection and transformation means 6 comprise a rigid curved leverage 20, in particular an arched bar 36, and a locking element 21 of the radial distance between the first end 24 and the second end 25 of the spiral spring 18.

The anchoring element 19 is configured like a pin 22 having an eccentric slit 35 into which the first end 24 of the spiral spring 18 is locked.

The locking element 21 is configured like a wheel 23 coaxially assembled on the pin 22 and arranged parallel to the spiral spring 18.

It must be underlined that the solution adopted which envisages a helical spring 18 cooperating with a wheel 23 which prevents a variation of the mechanical moment application arm allows the elastic coefficient to be kept constant for large angular ranges but with a dimension that is as small as possible in the longitudinal direction of the recovery device.

The pin 22 has an enlarged support base 32 fixed into a corresponding housing 33 afforded on a part of a flat plate 34 projecting from a longitudinal end of the block 14.

The plate 34 is fixed parallel to a flat outer face of the block 14 and supports the pin 22 orthogonally.

The pin 22 thus defines for the wheel 23 an axis of rotation that is orthogonal to the oscillation direction of the pile of magnets 7 and lies on the extension of a halfway plane of the pile of magnets 7.

The second end 25 of the spiral spring 18 is connected to the edge of the wheel 23 through a specific fixing plug 26.

A first end 28 of the arched bar 36 is hinged to the edge of the wheel 23 through a specific key-shaped hinging pin 27, whereas the second end 29 of the arched bar 36 is hinged through a specific key-shaped hinging pin 30 to a terminal 31 fixed to a longitudinal end of the magnetic mass 3.

The hinging pins 27, 30 of the arched bar 36 are parallel to the rotation pin 22 of the wheel 23.

The spiral spring 18 is therefore elastically deformable, keeping the distance between its ends unchanged, in a parallel plane to the movement plane of the arched bar 36 and the rotation plane of the wheel 23.

The choice of the curved leverage 20 to transmit the peripheral circular motion of the wheel 23 to the pile of magnets 7 is a significant turning point with respect to the use of a straight leverage the same length as the distance between the ends of the curved leverage. In fact, with respect to an axial-linear conversion of the movement, with a radial-linear conversion, angular widths can be obtained and therefore larger linear widths with a reduction in overall dimensions.

In the solution illustrated, each of the two identical elastic recall elements 5 has corresponding connection and transformation means 6.

The two elastic recall elements 5 and the corresponding connection and transformation means 6 are arranged symmetrically so as to balance the torsional forces and the thrusts acting on the magnetic mass 3 in the transversal direction to its oscillation direction.

More precisely, the two elastic recall elements 5 and the corresponding connection and transformation means 6 are arranged on different planes in a specular position with respect to the halfway plane of the pile of magnets 7 containing the axis of rotation of the wheels 23. In more detail a connection stem 37 is provided, which synchronises the opposite rotations of the two wheels 32.

The connection stem 37 centrally crosses the spiral springs 18 and is fixed with its opposite ends in specific axial housings 38 provided in the rotation pins 22 of the wheels 23.

On the connection stem 37, between the two spiral springs 18, another spacer wheel 39 is assembled.

Between the spacer wheel 39 and the helical springs 18, and between the wheels 23 and the helical springs 18, annular bearings 40, 41 are interposed to reduce the friction.

The rotation pins 22 are positioned resting on the annular bearings 40.

Between the support base 32 of the rotation pins 22 and the wheels 23 stopping rings 42 are applied to the rotation pins 22 which keep the assembly formed by the two pins 22, the two wheels 23, the wheel 39 and the two spiral springs 18 in an assembled condition.

Minimisation of the static and dynamic friction is obtained through the choice and combination of appropriate materials and through appropriate surface treatment techniques.

For example, the interface between components of the connection and transformation means 6 in reciprocal relative movement to one another and with the elastic recall elements 5 is formed by a hard metal (e.g. 316L stainless steel, stainless steel coated in DLC) in contact with a soft self-lubricating metal (e.g. bronze and nickel silver). Furthermore, one or more components of the connection and transformation means 6 are obtained by electrical discharge machining or have electrochemically polished surfaces and/or coated with synthetic diamond.

Electrical discharge machining (wire erosion) represents an excellent alternative to perimetral cutting with excellent precision (up to +/- lum). As well as the notable precision, this cutting method almost completely eliminates the problem related to the size of the cutting tool since cutting wires are available comprised between 0.02 and 0.33mm diameter.

Electrochemical polishing solves the need for time-consuming surface electrical discharge erosion operations. At the same time it is faster than common chemical polishing, since the presence of an electric charge on the item to be machined concentrates the action of the ions of the acid used for the treatment onto the surface. The current measurement and control of the electrochemical voltage also allows better control of the redox parameters of the surfaces to be polished. This machining process generally operates on the first ΙΟμιη of the material to be treated.

The diamond like coating (DLC) represents a very important surface treatment, both in terms of the visual impact of the final item (the colour depends on the thickness of the coating layer) and due to the mechanical characteristics typical of diamond, i.e. a hardness of 5300 HV (500HV for tool steel) and a friction coefficient comprised between 0.08 and 0.12. Synthetic diamond coating takes place on a few μηι through the application of plasma at low temperatures (<100°C). The recovery, conversion and storage unit 2 comprises an AC/DC rectifier circuit 43, a DC/DC voltage converter 44 operating with MPPT (Maximum Power Point Tracking) logic, a charge regulator 45, an accumulator 46 and a voltage reconverter 47 which brings the energy stored at the accumulator 46 voltage to the operating voltage.

The recovery, conversion and storage unit 2 is formed by electronics integrated onto a printed circuit.

Advantageously the printed circuit is defined by the plates 34 which cover the support block 14 and act as a containing support for the elastic recall elements 5 and for the connection and transformation means 6.

Due to the low levels of energy involved, the recovery, conversion and storage device 2 operates in ultra-low-power mode. This means that the electronic components taken into consideration for its implementation operate with very low losses and high conversion efficiency.

As a converter, by way of example, the bq25504 component by Texas Instruments™ can be used. This converter was designed to overcome the problems of recovering energy from photovoltaic cells and TEG elements. Since it is known that such energy sources have significant variations in efficiency according to the load conditions, this component offers an input impedance optimisation device through MPPT (Maximum Power Point Tracking). Together with this optimisation system, the internal converter performs a first unregulated very high efficiency conversion on a buffer capacity 48 to then be re-converted, at lower impedance conditions, to the storage voltage. This reconversion is interposed to a highly parameterisable load management system which allows the exploitation of lithium ion accumulators in optimal conditions and in full compliance with critical operating conditions.

For the reconversion of the energy recovered and stored in the secondary battery (lithium ion accumulator), an Ultra-Low-Power converter (LTC1877) can be used for the adaptation to the operating voltage.

The accumulator is preferably of the thin film lithium ion type.

It has been noted in practice how the portable electrical energy recovery device according to the invention is particularly advantageous: due to the construction choice of the particular radial-linear movement extended with the curved leverage; due to the provision of a pile of magnets with opposite poles for the creation of a higher flux density per dimensional unit of the magnetic pole and also for increasing the same magnetic flux variation measured longitudinally to the pile of magnets 7; due to the balance in transversal and torsional stress acting on the pile of magnets; due to the absence of a magnetic circuit which, if provided, would imply the presence of parasitic reluctant forces able to reduce the extractable energy and/or make it unusable; due to the increase in efficiency thanks to the provision of an electrical energy generation unit in mechanical resonance, and a recovery, conversion and storage unit for the energy in electrical resonance through the continuous adaptation of the transfer impedance.

The portable electrical energy recovery device as conceived herein is susceptible to many modifications and variations, all falling within the scope of the inventive concept; furthermore, all the details are replaceable by technically equivalent elements.

The materials used, as well as the dimensions, may in practice be of any type, according to needs and the state of the art.