DESCRIPTION

This invention refers in general to a device for air speed measurement, and in particular to a portable device for speed measurement.

Known are apparatuses for the measurement of air speed based on the measurement of the rotation of a wheel linked to a moving body and rolling on a fixed reference, for example the ground. Such apparatuses require the contact with the fixed reference to be a rolling one, without any dragging, and furthermore they require a mechanism able to transform the wheel rotation into a visible indication.

Also known are apparatuses based on the pressure change of a fluid moving through a constriction; such apparatuses don't require a contact with a fixed rigid reference, and they are suited, for example, for measuring the speed of flying vehicles, but they require quite complex devices to transform the pressure change measurement into a visible speed indication.

For certain uses, there is the need to measure a relatively slow speed by means of a portable device, featuring a low weight and a low cost, for example in the practice of some sport disciplines, such as downhill ski or cross-country ski, cycling; on small boats; or to measure the speed of a moving fluid, in general when it is not possible to

refer the measurement to the rolling in respect of a fixed reference or similar, and the use of rather complex devices, such as differential pressure gauges, is not convenient.

For these uses, the Applicant has observed that known apparatuses are excessively complex, heavy and expensive. In consideration thereof, the Applicant perceived the need to devise a device for speed measurement, which is particularly simple and light-weighted, suitable to be carried or comfortably worn, and in addition inexpensive.

In light of the above, the Applicant found out that a device for speed measurement suitable for the above-mentioned purposes could be realized through the reading of the deflection of an elastic foil exposed to the air flow.

Furthermore, the Applicant observed that, in case o slow speeds, the dynamic pressure exerted by air is relatively low, and this means that it requires a relatively flexible foil in order to be able to measure the speed, while, in case of higher speeds, the dynamic pressure increases considerably, so much that a foil suitable for slow speeds is totally deflected, beyond the measuring scale, thus making the measurement in such conditions impossible.

Therefore, the Applicant sensed that the measurement could be done in a relatively wide range of speed, provided that the flexibility of the foil is progressively reduced when the speed increases. More in detail, the Applicant perceived that by progressively changing the foil flexibility it is possible to obtain a measurement on a scale which is essentially linear, easy to be read.

More in detail, the invention concerns in the first instance an device for air speed measurement, comprised of: a casing equipped with inlet and outlet openings, suitable to allow the inflow and outflow of air into and from the casing; a flexible foil

inside the said casing, placed in front of the inlet opening, suitable to be inflected by incoming air; and a shaped profile to support the said foil, suitable to define a predetermined' bending at different speeds of incoming air into the casing.

In particular, one end of the said flexible foil is preferably embedded inside the casing.

Preferably, the said shaped profile comprises several points of support, which determine relative inflections of the foil at different air speeds, according to a linear scale.

Conveniently, if the said inlet opening is to be used in different positions, it shall include a steering deflector.

Preferably, the said casing is supplied with a small fixing belt.

According to a preferred realization form, the device subject-matter of the invention comprises a maximum indicator that is placed in an interfering position with respect to the inflection of the said foil, suitable to be pushed by the said foil with controlled friction.

The said maximum indicator is geometrically balanced and, preferably, it includes a resetting element.

In the second instance, this invention concerns a headgear fitted with a peak, in which the said peak is equipped with a device according to one or more of the above- mentioned claims.

These and other features of the invention will emerge more clearly in the following description of some examples relating to the realization of the invention, with reference to the figures of the enclose drawings, which show respectively:

figure 1: the measuring device according to one of its realization forms (transversal section); figure 2: the device indicator (frontal view); figure 3: the device indicator (transversal view); figure 4: the scheme of the indicator operating positions; figure 5: the section according to the plane V-V of figure 1; figure 6: the device of figure 1 worn on the wrist; figure 7: the device of figure 1 fitted onto the peak of a hat; figure 8: a particular of a realization form concerning the maximum indicator resetting device; figure 9: the measuring device fitted onto the tip of a ski (side view); figure 10: the measuring device of figure 9 (frontal view); figure- 11: the measuring device fitted with a maximum indicator, in an alternative realization form (side view); figure 12: the measuring device of figure 11 (section according to the plane XII-XII of figure 11); figure 13: the measuring device of figure 11 (frontal view, partially in section);

As shown by figures 1 and 5, the device for speed measurement subject-matter of the invention, in one of its realization forms, includes a case 1, appropriately shaped, featuring two sides Ia and Ib and a border Ic.

The border Ic, that borders the sides Ia and Ib, features an inlet opening 2 and an outlet opening 3.

At least one of the sides Ia and Ib comprises a transparent reading area 4, to allow to look inside in correspondence of indicator 5 of a flexible sheet 6.

In a preferred realization form, the whole case 1 can be made of a transparent material, for example plastic material.

The flexible sheet 6, hereinafter referred to as indicator sheet, is comprised of a shaped foil made of elastic material, for example plastic material, whose upper part 6a, of width A basically corresponding to the width of the inlet opening 2, is made well visible by a coloured border or similar, preferably in relief, that constitutes the device indicator 5; in the realization example shown, the indicator sheet 6 has a lower part comprised of two lateral portions 6b, of width t, separated by a medial carving 6c. If necessary, the medial carving 6c can be omitted, as shown further on.

The lower end of the lateral portions 6b of the indicator sheet 6 is firmly cantilevered, like an inserted beam, close to the lower border of case 1, for example by gluing.

At rest, the indicator sheet 6 leans against a transversal side Id of case 1.

The inlet opening 2, placed in correspondence of the upper part 6a of the indicator sheet 6, is designed to be turned to face the motion direction, and it is fit to allow motion-speed air to affect the indicator sheet 6; on the other hand, the outlet opening 3 is fit to allow air to outflow from the case.

On the transparent part of the case reading area 4, a speed scale 7 is clearly marked.

Case 1 comprises some points of support 10a, 10b, 10c, 1Od, 1Oe, made up, for example, by transversal pins, or couples of transversal pins, with a space between them, and placed in predetermined positions in correspondence of the inflection positions of the indicator sheet 6 at different inflow speeds of the air into case 1.

If required, a deflector 15, which can be turned by means of a pin 16, preferably a screw pin in order to allow, if desired, the deflector to be blocked in a determined position, allows the air inlet to be turned towards the prevailing direction determined by motion. It has. been verified by way of an experiment that deflections up to 45° and more do not significantly modify the indication of speed.

The force exerted by air speed on the exposed surface of indicator sheet 6 determines the deflection of the said indicator sheet 6, shown by indicator 5 on graduated scale 7.

The deflection of indicator sheet 6, and therefore the information given by indicator 5, depends on the free length of sheet 6, and therefore on the distance between the free end and the intermediate points of support that the sheet encounters in its length.

Therefore, if these points of support are appropriately placed, it is possible to obtain that indicator sheet 6 deflection is, at regular intervals, both a measure and a speed shift.

Figure 4 shows the deflection of indicator sheet 6 in different operating conditions.

The deflection of indicator sheet 6, and therefore the information given by indicator 5, depends on the free length determined by points of support 10a- 1Oe with which the said sheet interacts in the various conditions.

At a slow incident air speed, indicator sheet 6 inflects in position 6 ¹ and encounters the first point of support 10a.

As air speed increases, the indicator sheet 6 inflects in the following positions 6 ^π , 6 ^iπ , 6 ^IV , 6 ^V , determined by the relevant points of support 10b, 10c, 1Od, 1Oe.

An air speed increase corresponds to an increase in the dynamic pressure exerted by air on area 6a of indicator sheet 6; the reduction of the free length of indicator sheet 6 determines a higher flexural rigidity of the same, which allows, when the position of points of support 10a- 1Oe is appropriately chosen, to obtain a value scale which is essentially linear with respect to speed in the application field concerned.

The position of scale 7 and of the points of support 10 can be operationally defined as follows, with reference to figure 4:

A first reading of the scale is defined when the end of indicator sheet 6 has moved of a value f, according to bending 6 ¹ . It corresponds to an inflection length Ll of the sheet 6 between the point of support 10a and the sheet end. When the end of the value f is moved again, the length between the point of support 10b and the sheet end is equal to L2, bending is 6 ^π , and if we draw an isosceles triangle with line Ll we find the point of support 10b. By applying the same method, we can find the five intermediate points of support and the corresponding position of the main marks 7 ¹ , 7 ^π , 7 ^πi , 7 ^IV , 7 ^V of the graduated scale 7.

Preferably, the space between the marks of the graduated scale is regular (for example 10mm, corresponding to a speed of 20 km/h).

The position of the intermediate points of support (i.e. the length of the various distances Ll, L2, ..., Lj), depending on speed and on the other elements involved, can be calculated using the following equation:

Lj = ((f«s ³ E-t«10 ⁹ )/(k'V ² 'A ² )) ^1/3 , where:

Lj = length of the free parts Ll, L2, ... (in mm) f = deflection of the sheet (distance in mm. between two consecutive indicators)

s = thickness of the sheet (in mm)

E = elastic module of the sheet (in kg/mm ² )

V = incident air speed t = width of the flexible part of the sheet (in mm)

A ² = -surface of the sheet that receives the air (in mm ² ) (with a supposed essentially square shape); k is an experimentally-defined coefficient depending on the size of the device; in one example of realization, a coefficient k = 5.5 has been adopted.

The intermediate points of support 10 can be obtained by inserting some metal wires in the lateral sides of case 1; alternatively, the intermediate points of support 10 can be obtained by securing two appropriately shaped metal tablets (not shown here) inside case 1.

In one example of realization, the graduated scale 7 includes main reading indications marked on the side, continuing until the border, with opaque black segments and spots and intermediate values indicated by shorter marks. Conveniently, the numbers corresponding to speed, expressed in decades, are indicated, without zeroes, horizontally and facing the air inlet, in order to allow the identification also when the instrument is upside down.

The measuring device can be worn, for example, on a skier's gloved hand 11, as shown in figure 6, without interfering with the equipment usually required to practice the sport activity, such as for example the ski pole handle 12 and the related wrist strap 13.

A strap 14, consisting for example of an elastic band loop or a stiff band with a buckle, Velcro strap or similar, secured on the side to case 1 with a small bolt, rivet or

similar, is used to fasten the measuring device to the gloved hand. When the strap 14 is made of an elastic band loop, the skier can wear the glove, insert the hand into the strap carrying the device and then clasp the pole. When the strap 14 has an openable fastening, for example a buckle or Velcro strap, it can be worn in any moment, also while holding the pole with the hand.

Conveniently, for this usage, in the device subject-matter of this invention the reading area is placed on one side, left or right according to specific needs, or on both sides for a two-sided use.

To allow a continuous reading, without averting one's eyes from motion direction, the device can be fitted upside-down onto the peak 17 of a hat or helmet, in a side-front position, as shown in figure 7, my means of a fixing element 19 and a swivelling support 18, which allows to control verticality. Alternatively, a Velcro strap can be used in this case as well.

In this application, it is opportune that deflector 15 is mounted on inlet opening 2.

A lateral position is the preferred position for mounting the device on the peak, in vertical direction, forming a 45° angle on the horizontal plane with respect to the motion direction.

Conveniently, the device comprises a maximum indicator 8, to record the maximum speed reached.

A realization form of the maximum indicator 8 is shown in figures 1 and 8, while figures 11-13 show an alternative realization form.

In the realization form shown in figures 1 and 8, the maximum indicator consists of a small shaped foil, pivoted and swivelling on a pin 20. the foil features an

indicator 8a and a balancing portion 8b, such as to make its balance around pin 20 irrelevant in the various positions of the device, in order not to alter the position determined by indicator 6.

For the purpose of not interfering with maximum indicator 8 rotation, side Id of case 1, against which indicator sheet 6 leans, is supplied with an opening 21, as shown in figure 1.

The maximum indicator 8 revolves around pin 20 with a limited friction, in a way that its upper end 8a, pushed by indicator sheet 6, traces an arch similar to that of indicator 5; conveniently, the maximum indicator 8 consists of a flat foil made of plastic material or similar.

The resetting of maximum indicator 8 can be performed by means of an axially- movable pin 22, cutting across lateral sides Ic of case 1, as shown in figure 8, supplied with a side protrusion 23, suitable to act on a corresponding protrusion 24 of the maximum indicator 8. A small spring 25 ensures the spring back of pin 22 in rest position.

Alternatively, as shown in figures 11-13, the maximum indicator 8 consists of a small stick inside of the measuring device body, revolving around a pin 9 that cuts across lateral sides Ia and Ib of case 1, placed in a position that interferes with indicator sheet 6 deflection, so that it is turned by it.

Preferably, as shown in figures 11-13, in this realization form the maximum indicator 8 is comprised a shaped stiff wire, for example a metal wire, with a portion 8c that constitutes the indicator, a portion 9 that constitutes the rotation pin, and a portion 8d for balancing. Portion 9 is essentially orthogonal with respect to portions 8c and 8d,

and the whole of the wire is such that, in installed position, portion 8c is inside the measuring device body and portion 8d is outside.

The two segments 8c and 8d have the same length, in order to be balanced for rotation in every device position.

In correspondence of the hole where portion 9 goes through, a wedge 26 is fitted, which can be blocked in position, suitable to exert a controlled friction, sufficient to prevent the indicator from moving due to vibrations, but sufficiently low so that it does not significantly interfere with indicator sheet 6 deflection.

A sector 27, placed outside portion 8d, ensures a protection of the same and constitutes the points of minimum and maximum rotation of indicator 8. The end 8e of portion 8d conveniently protrudes beyond the border of sector 27, and constitutes a reading indicator (for example by means of a scale reproduced on sector 27) and allows the resetting of the indicator after reading.

With this second realization form of the maximum indicator, sheet 6 and support Id do not require the presence of carvings 6c and 21. Due to the lack of carving 6c, the thickness of sheet 6 will have to be appropriately changed in order to obtain the desired deflection in the foreseen speed range.

Also pins 10, or the corresponding continuous shape of support, can be continuous through the whole inside length of case 1.

In the foregoing description, the device subject-matter of the invention has been described with particular reference to the use of the same made by a user that wears it while practicing a sport.

However, for other applications it can be more appropriate to permanently mount the device on a moving object of which we would like to measure the speed, for

example on a small boat or similar, or in a fixed position to measure the incident air speed, for example in front of a fan or a ventilation duct, or to measure wind speed.

In particular, as shown in figures 9 and 10, the measuring device can be mounted in a permanent or removable way, by means of a Velcro strap 28 or similar, on the tip of a ski or snowboard 29, in such a way that the inlet opening 2 mouth faces the motion direction. Deflector 15 is conveniently placed so that it automatically turns under air pressure, in order to convey the air flow into, the device.

If necessary, a net cover 30 prevents snow or debris, from entering into the device.

Furthermore, for particular needs the device can be simply held and turned towards one or more directions or positions, for example to identify a speed distribution in the scope of an air flow, for example on small sailboats or on aeraulic equipment.