The present invention relates generally to an apparatus for removing the glasses of a vehicle.

More particularly, the invention relates to an improved apparatus suitable to provide an induction heating in areas of the windscreen and of other glasses of a vehicle, in order to remove said glasses during the vehicle's repair in a bodywork.

The induction heating is already used in a bodywork to remove the windscreen, the rear window and the side windows that are glued to the metal sheet of the vehicles; said known technique consists in heating, by means of an inductor (the tool), the edge of the metal sheet where the glue is located for fixing the glass.

Therefore, the adhesive material is heated by conduction until it is detached from the metal sheet, thus also removing the glass (the enclosed figures 1 , 2, 3 and 4 show a typical application of said prior art method, according to which an inductor or tool 10 is used for heating the edge of the metal sheet 11 in the area of the adhesive material 12 that is able to fix the glass 13 of the vehicle 14).

However, as seen in the heat map of the inductor 10 that is shown in the enclosed figure 4, using said known equipment causes the fact that the greater concentration of heat that is produced on the metal sheet 11 is obtained at the center of the tool 10.

It follows that the use of said equipments causes a high risk of burning the paintwork of the vehicle near the glass to remove.

As part of the above requirements, therefore, an aim of the present invention is to obviate the above technical problems and, in particular, to make an equipment for removing vehicles glasses, which allows to use the known induction technique, by performing the removal of the glass without causing damage to the painted parts of the vehicle body that are located near the glass (i.e. the roof and the side uprights of the vehicle).

Another purpose of the invention is to provide an apparatus for removing glazing of vehicles, which, compared to the prior art, would result in reduced time and costs of execution.

These and other purposes are achieved providing an apparatus for removing glazing of vehicles according to the enclosed claim 1 ; other technical and/or construction details of the above-mentioned equipment can also be found in the further dependent claims. Advantageously, according to the present invention, a specific "bound field" inductor (or tool) is provided for removing glasses, also by actuating a suitable control of the power that is transferred to the metal sheet of the vehicle, thanks to the use of a special generator powering the inductor. The operating principle is based on making an alternate magnetic field, which is concentrated by the inductor toward the metal portion to be heated; thus, "eddy" currents are generated and said currents are able to heat very quickly said metal portion.

The inductor, in fact, generates eddy currents inside non-magnetic materials, such as aluminum, copper, silver, etc. but, due to their low electrical resistivity, said materials are slightly heated.

On the contrary, said inductor generates strong eddy currents in all ferromagnetic materials, such as iron, steel, cast iron, etc.; said materials, due to their high electrical resistivity, are very quickly heated.

Furthermore, the flow that is generated is able to heat metals that are far no more than a few centimeters from the tool and the heating power is greater the closer distance is provided between the inductor and the metal portion.

Moreover, according to the present invention, the tool is improved as a result of the following phases:

- estimating the distribution of the power transmitted to the plate (that is proportional to the generated heat), through a finite element method (FEM), by using a known inductor;

- checking the goodness of the results that are obtained with said computation method, by means of laboratory measurements;

- computer simulation of fictitious inductors with different geometries and construction;

- analysis of results and choice of the optimal configuration for the work;

- making a prototype tool as shown in the simulations;

- checking the obtained results, through suitable measures;

- final implementation of the tool by means of practical tests.

The above mentioned purposes and advantages, as well as others which will be mentioned hereinafter, become more readily clear from the description which follows, relating to a preferred embodiment of the invention, and from the enclosed drawings, in which:

- figure 1 shows a partial and schematic section view of a tool for removing the glazing of vehicles, according to the prior art; - figure 2 shows an example of two tools used for removing the glazing of vehicles, according to the prior art;

- figure 3 shows a schematic side view of the tool for removing the glazing of vehicles, according to the prior art;

- figure 4 shows a diagram representing the localization of heat on the plate, in correspondence of the tool that is used according to the known technique, as shown in the enclosed figures 1-3;

- figures 5, 6 and 7 show respective computer simulations of the tool or inductor of Figures 1-4, according to the prior art, and the relative power distributions on a flat metal sheet and on a metal sheet with edge and step;

- figure 8 shows a perspective view of a tool prototype (figures 1-4), that is made according to the prior art;

- figures 9 and 10 show two diagrams reporting measures of the temperature detected below the tool of figure 8, according to the prior art, during the heating, respectively, of a flat metal sheet and of a metal sheet with edge and step;

- figure 11 shows a schematic and partial view of the tool or inductor used in the apparatus for removing glazing of vehicles, according to the present invention, together with a diagram showing the localization of heat on the metal sheet;

- figures 12, 13 and 14 show relative computer simulations of an improved tool or inductor that is used in the equipment for removing glazing of vehicles, according to the present invention, as well as the related power distributions on a flat metal sheet and on a metal sheet with edge and step;

- figure 15 shows a perspective view of the tool shown in figures 12, 13 and 14, according to the present invention;

- figures 16 and 17 show diagrams relative to temperature measurements that are detected below the tool of figure 15, according to the invention, during heating, respectively, of the flat metal sheet and of the metal sheet with edge and step;

- figures 18 and 19 show two perspective views of the inductor or tool of figure 15, that is used in the equipment for removing glazing of vehicles, according to the present invention;

- figures 20 and 21 show two side views of the equipment for removing glazing of vehicles, according to the present invention; - figure 22 shows a partial top plan view of the equipment for removing the glazing of vehicles, according to the present invention;

- figure 23 shows a partial perspective view of the equipment for removing the glazing of vehicles, according to the present invention;

- figure 24 shows a block diagram of the equipment for removing the glazing of vehicles, according to the present invention.

With particular reference to the above mentioned figures 5, 6 and 7, the equipment according to the invention is made firstly by reconstructing a known tool or inductor through a PC (figure 5); the tool or inductor has a U-shaped ferrite core 15, with the windings 16 that are wounded around each leg 17 of the core 15 and that are series-connected so that the generated magnetic flux are both concordant; the eddy heating current that are generated on the metal sheet are added together between the two windings 16.

The enclosed figure 6 shows the results of the simulation on a flat metal sheet; the greatest power distribution is achieved at the center of the tool and the heated region 18, in which the eddy currents are added together, has a substantially square shape and symmetrical with respect to the axis of the tool.

The enclosed figure 7 shows the results of the simulation on a metal sheet with edge and step (in order to simulate the real shape of the metal sheet on which the vehicles glasses are usually glued); as shown, the greatest power distribution is always achieved at the center of the tool, but the heated region 19 has a shape that partially affects also the step of the metal sheet and, therefore, the visible portions of the vehicle body.

The enclosed figure 8 shows a tool prototype 20, on which measures have been carried out to verify the above mentioned results of the computer simulations, using FEM.

In particular, figure 9 shows a temperature measurement that is made with a thermo-camera during the heating of a flat metal sheet; it is clear that said measurement confirms the heat distribution simulated with the PC (see the enclosed figure 6).

Furthermore, figure 10 shows the temperature measurement performed with a thermo-camera during the heating of a metal sheet with edge and step; the right portion constitutes the glass, while the cusp-shaped portion 21 shows that the heat tends to affect mostly the portion opposite to the edge of the metal sheet where the exposed part of the vehicle body is placed. Furthermore, the measurement confirms the heat distribution simulated with the PC (see figure 7).

The above research about a known tool (inductor) able to remove the glasses of a vehicle shows the use limitations of said tool; in fact, it is possible to damage the visible parts of the vehicle's bodywork and the PC simulations have also pointed out that said known tool would be perhaps more suitable to perform other operations on a flat metal sheet (such as, for example, removing plastics or rubbers glued to the metal sheet of the bodywork that is not in view).

Therefore, other various geometrical structures of the tool (inductor) have been planned, in order to achieve a complete optimization of the same. The enclosed figure 11 shows a tool (inductor) 25 which is made according to the present invention; it is able to remove the vehicle's glasses and, at the same time, with respect to the known tools, it allows to screen off the painted metal sheet 1 from the magnetic field closing on it, thus protecting the metal sheet 11 from over-heating, as well as allows to produce the heat with an elongated distribution on the metal sheet 11 , so as to better follow the shape of the insulating seal that has to be unglued. Figure 11 also shows the heat map of the metal sheet 11 ; in this case, it is clear that the heat distribution is asymmetrical and uniform throughout the tool (inductor) 25 and the heating zone generated on the metal sheet 11 follows the straight distribution of the insulator (glue) which is able to fix the glass.

According to the invention, therefore, it is possible to identify a lateral portion 26 of the tool 25 (where the word "GLASS" can be written, for example, so as to easily find the portion), which will be facing the center of the glass to be removed; with reference to the heat map showed in the enclosed figure 11 , the glue will be below the zone 27 in which the maximum heat is developed, while the visible portions of the bodywork are positioned to the right of said zone 27 and the center of the glass is placed to the left.

In order to obtain the above heat map, according to the invention, an inductor 25 having a structure such as that shown in detail in the enclosed figures 12, 15, 18 and 19 is provided; in particular, the inductor 25 essentially consists of a C-shaped ferrite core 28 and of a coil 29 that is wrapped essentially around one leg of the C.

The coil 29 may be provided of a spool 30 and the core 28 can be constituted by a sintered magnetic core operating at frequencies ranging from 1 kHz to 1000 kHz; the shape of the core 28 can be obtained by injection molding or by combinations of one or more U, UR, I commercial cores, so as to obtain a structure similar to the structure shown in the enclosed figures 12, 15, 18 and 19, in which the length L may vary from 20 mm to 300 mm and the height H may vary from 30 mm to 400 mm.

The result is a finished structure or a containment casing, such as the structure indicated with 31 in the enclosed figures 11 , 20, 21 , 22 and 23, which contains, within the body 33, the inductor 25 (with the highlighted lateral portion 26) and which also includes a power cable 32 and a control button 34, which makes the apparatus easy to handle and practical (unlike other known apparatus comprising footswitches or similar devices).

The enclosed figure 12 shows a PC construction of the tool (inductor) 25, with the ferrite core 28 and the coil 29; as shown, the loops of the coil 29 are provided on a single leg of the core 28, while the free leg is used to shield the magnetic fields towards the visible portions of the vehicle's bodywork.

The distribution of the eddy currents on the metal sheet 11 is concentrated below the coil 29, due to a "mirror" effect of the currents which are able to generate a counter-flow to counteract the magnetic flux generating said currents.

The enclosed figure 13 shows the results of a simulation provided on a flat metal sheet; the greater heat distribution (area indicated with 35) is obtained between the two legs of the core 28 and the heated zone 36, in which the eddy currents are concentrated, has a narrow and elongated shape with a well-defined geometric shape.

The enclosed figure 14 shows the results of a simulation provided on a metal sheet with edge and step, to simulate the real shape of the metal sheet 11 where the vehicles glasses are glued; the greater distribution of heat (area indicated with 37) is very similar to the distribution which has been previously obtained (figure 13) and does not affect the step of the metal sheet and therefore the visible portions of the vehicle bodywork. The enclosed figure 15 shows an inductor or tool prototype 25, on which measures have been carried out to verify the above PC simulation results obtained using FEM.

In particular, the enclosed figure 6 shows the temperature measurements that have been made with a thermo-camera during the heating of a flat metal sheet; the measure fully confirms the heat distribution simulated with the PC.

Finally, the enclosed figure 17 shows the temperature measurements that have been made with a thermo-camera during the heating of a metal sheet with edge and step; the portion 38 at the bottom constitutes the glass, while the uppermost portion 39 shows that the heat is abruptly limited in correspondence of the side opposite to the edge of the metal sheet where the visible portion of the vehicle bodywork is located. In any case, the measurement fully confirms the heat distribution simulated with the PC.

Therefore, the induction heating equipment which is used for removing the glazing of vehicles, according to the present invention, may be schematically shown as in the enclosed figure 24 and substantially comprises an AC supply 40, which is series-connected with a bridge rectifier 49, a power generator 41 and the inductor or tool 25 that is applied to a load 42.

The basic circuit 47 of the power generator 41 , which is series-connected with a HF transformer 48, is a series or parallel resonant circuit, in which the inductance of the tool 25 resonates with the capacity of the generator 41 at a given resonance frequency "f" .

Normally, the resonance current I circulating in the inductor or tool 25 is adjusted, through a microcontroller 44 and a driver 45, by varying the frequency of the inverter 43; at equal distance between the inductor 25 and the metal sheet (the load 42), the heating power increases with the increase of the current flowing in the inductor 25 and, also, at the same current circulating inside the inductor 25, the power transferred to the metal sheet (the load 42) is greater as the inductor 25 is closer to the load 42 (the metal sheet) to heat.

The known power generators allows to set the current of the inductor 25, but, during the removal of the glass, the tool 25 may contact directly the vehicle bodywork, thus transferring in a short time a very high power to the metal sheet (the load 42) and causing damages to the bodywork paint.

The power generator 41 of the present invention is designed so that the inductor 25 operates with a constant power (and not with a constant current); consequently, the tool 25 always transfers the same power (that is previously set), regardless of the distance between the inductor 25 and the metal sheet (the load 42). This is obtained thanks to a feedback control, carried out by the microcontroller 44, which reads, through the block 46, the active power that the power generator 41 requests to the power supply 40; said active power is proportional to the heating power which is transferred to the load 42 and, therefore, if the value of the input power increases, then the control acts on the inverter 45 to increase the frequency and decrease the current I of the inductor 25 up to always obtain the same power.

From the above description the technical features, as well as the advantages, of the equipment for removing the vehicles glasses, which is the object of the present invention, are clear.

It is also clear, finally, that other variations may be made to said equipment, without departing from the principles of novelty inherent in the inventive idea, just as it is clear that, in the practical embodiment of the invention, the materials, shapes and dimensions of the illustrated details can be any, depending on requirements, and may furthermore be replaced with others that are technically equivalent.