Description Built-in ventilation unit for kitchen hoods The present patent application relates to a built-in ventilation unit comprising a fan, a motor and a motor support for installation in kitchen hoods, normally above the cooker, in order to convey and eject under pressure the fumes, vapours and odours originated while cooking.

The purpose of the present invention is to simplify and accelerate the assembling procedure of the current electroaspirators for kitchen hoods as well as reduce overall assembling costs.

In order to appreciate the advantages of the model according to the invention reference must be made to the traditional assembling technique used to produce electroaspirators. Electroaspirators mainly include three main components: an ordinary fan, an ordinary electrical motor and a special support for the motor consisting in a one-piece injection-moulded plastic circular grid whose centre is provided with a suitably reinforced plate that acts as anchoring platform and support for the electrical motor.

The electrical motor is conventionally made up of a rotor and a stator and provided with an opposite pair of U bolts. Each U bolt features a central collar that houses oscillating bushings for the support of the rotor shaft. The two U bolts are fixed on opposite sides to the stator with two screws located in diametrically opposite position with respect to the rotation axis of the rotor.

The screws are also used to fix the motor to the plastic support plate on which two holes for the screws with nuts are drilled during the moulding process.

The motor is fixed to the support plate after all the electrical cables for its connection to the control switch box located on the hood in which the electroventilation unit is installed have been soft-soldered.

According to the model of the invention, the shaft of the electrical motor is supported on a hub that forms an integral part of the plastic grid, from whose internal side an opposite pair of guide-pins protrudes. The two pins are inserted into two holes suitably located on the stator, which also features four

small holes in which corresponding small pins protruding from the internal side of the plate are exactly inserted.

The arrangement of the small pins on the plastic grid and the small holes on the stator is such that-once the pins have been inserted into the holes-the hub assumes a perfectly centred coaxial position with respect to the circular housing inside the stator for the rotor.

This operation ensures concentricity between the stator and rotor and therefore a constant air gap by using fixed bushings only.

The motor is permanently fixed onto the plate by means of a pair of elastic rings that are inserted and tightened on the two guide-pins, which can no longer be extracted from their insertion holes.

According to the invention, a wide opening is located in the centre of the grid.

The perimeter of the opening features injection-moulded housings for the female element of the electrical faston connectors designed for connection with the corresponding male elements previously mounted on the reels of the stator windings.

According to the invention, the wiring of the motor can be automatically carried out when the motor is coupled with the support grid, as long as female faston connectors are applied at the ends of the electrical cables to be connected to the motor.

The advantages of the model according to the invention will appear more evident in the description below with reference to the enclosed drawings, which are intended for purposes of illustration and not in a limiting sense, whereby: -Fig. 1 is a cross-section with an axial plane of the built-in ventilation unit according to the invention, without fan; -Fig. 1A is an enlarged detail of Fig. 1; -Fig. 2 is an exploded view of the built-in ventilation unit according to the invention without fan, sectioned with the same axial plane of Fig. 1 ; -Fig. 3 is a front view from the outside of the motor support in a first constructive version ; -Fig. 3A is an enlarged detail of Fig. 3 ;

-Fig. 3B is the cross-section of Fig. 3A with the B-B plane ; -Fig. 4 is a front view from the inside (side facing the motor) of the motor support ; -Fig. 5 is the cross-section of Fig. 3 with the V-V diametrical plane ; -Fig. 6 shows the built-in ventilation unit according to the invention with fan, sectioned with the V-V axial plane of Fig. 3; -Figs. 7A, 7B, 7C and 7D are respectively the external view, the internal view and two cross-sections with the C-C and D-D planes of the motor support, in the version in which the motor support is not manufactured in one moulded piece with the grid ; -Figs. 8A, 8B, 8C and 8D are respectively the external view, the internal view and two cross-sections with the C-C and D-D planes of the grid designed to be coupled with the motor support, in the version in which the motor support is not manufactured in one moulded piece with the grid; -Fig. 9 is an external view of the cover hooked to the motor support, in the version in which the support is not manufactured in one moulded piece with the grid ; -Fig. 10 is the cross-section of Fig. 9 with the X-X plane of Fig. ; -Figs. 11A and 11 B are two enlarged cross-sections of two details of Fig. 9 ; -Fig. 12 is a cross-section with an axial plane of the motor support in a third constructive version, in which the female faston connectors are engaged into suitable housings located on the edges of the motor support cover ; -Fig. 13 is an exploded view of the built-in ventilation unit according to the invention, according to the version of Fig. 11; -Figs. 14A, 14B, 14C and 14D are respectively the external view, the internal view and two cross-sections with the C-C and D-D planes of the motor support cover, in the version in which the cover is provided with housings for the female faston connectors.

With reference to figures 1 to 6, in a preferred embodiment of the invention, the support of the motor (1) consists in a one-piece injection-moulded plastic circular grid (2) that centrally features a wide opening (3)-a rectangular one in this case-provided with fixing and support means for the electrical motor

(1).

The internal side of the grid (2)-that is the side facing the motor (1)-is provided with a radial series of support elements (4) designed to support a central hub (5) with the bushings that support the shaft (6) of the motor (1).

In the preferred embodiment of the invention, the hub (5) consists in a metal insert placed inside a collar (4a) in which the support elements (4) converge.

A pair of guide-pins (7) protrudes from the internal side of the grid (2) in diametrical opposite position with respect to the hub (5), together with four small centring pins (8).

The guide-pins (7) are freely inserted into two corresponding through holes (7a) located on the stator (1a) of the motor (1), which is also provided with four small holes (8a) in which the four centring pins (8) are exactly inserted.

The arrangement of the small pins (8) on the plastic grid (2) and the small holes (8a) on the stator (1a) is such that-once the pins (8) have been inserted into the holes (8a)-the hub (5) assumes a perfectly centred coaxial position with respect to the circular housing inside the stator (1a) for the rotor (1b).

With reference to figures 3,4 and 1A, the perimeter of the opening (3) features housings (9) obtained by injection-moulding with the grid (2) and designed to house the female element (10) of the electrical faston connectors used for connection with the corresponding male elements (11) previously mounted on the caps (1 c) of the stator windings.

The female faston connectors (10) are the terminals of the electrical cables (12) that connect the motor (1) to the control switch box located on the hood in which the electroventilation unit is installed.

More precisely, the female faston connectors (10) are inserted and engaged into corresponding housings (9) from the outside of the grid (2), where the cables (12) rest. The cables (12) are compacted and stopped inside a suitable collection guide channel (13a) located inside the plastic cover (13) fixed on the outside of the grid (2) to close the opening (3).

The cover (13) externally features elastic claws (13b) used to fix a filter cartridge (not shown in the figure). The same cover (13) internally features

elastic claws (13c) used to fix the grid (2).

The assembling of the motor (1) with the grid (2) is performed according to the procedure below.

To prepare the grid (2) for coupling with the motor (1), the bushings (14) are inserted into the hub (5) and the female faston connectors (10) that have already been fixed to their connection cables (12) are inserted into the housings (9).

To prepare the motor (1), the male faston connectors (11) are inserted into the cap (1c) of the stator windings and suitable connected with the stator windings.

The stator (1a) can now be mounted on the grid (2). The stator (1a) is placed against the internal side of the grid (2) using the guide-pins (7) that slide inside the corresponding holes (7a) of the stator (1a) as a reference, whose perfect centring is automatically performed at the end of the stroke due to the exact coupling between the small pins (8) and the small holes (8a) of the stator (1a).

The permanent fixing of the stator (1a) onto the plate (3) is ensured by a pair of elastic rings (15) that are inserted and tightened on the guide-pins (7), which can no longer be extracted from their insertion holes (7a).

The male faston connectors (11) are automatically inserted into the female faston connectors (10) during the assembling operation of the stator (1a) and the grid (2).

To assemble the rotor (1b), the rotor shaft (6) is inserted into the cylindrical bushings (14) until it comes out of the hub (5). A Seger anti-sliding ring (16) and a pre-compressed spring (17) are mounted onto the protruding end of the shaft (6) to maintain the correct axial position of the rotor (1b) with respect to the stator (1a).

Finally, the fan (18) is mounted onto the other end of the shaft (6).

The capacity of the model according to the invention to reduce the constructive and assembling costs of the ventilation units for kitchen hoods appears evident from the description above.

First of all, the invention eliminates the intrinsic cost of the two U bolts and

two screws that are currently used both to support the rotor with respect to the stator and fix the motor onto the support grid.

Moreover, according to the invention, the ordinary cylindrical bushings used to support the motor are much cheaper than the oscillating spherical bushings that are currently used for electroventilation units.

Compared to the current technique, the soft soldering for the wiring between the stator windings and the connection cables between the motor and the control switch box is eliminated.

From the economical viewpoint, the most significant aspect is that in the model according to the invention the assembling of the motor (1) with the grid (2) coincides with the assembling of the motor (1), that is the fixing of the rotor (1 b) inside the stator (1a).

In other words, according to the current technique, first the rotor and the stator are coupled and then the motor is fixed to the grid. The model according to the invention allows for eliminating the two separate assembling steps, which are unified in a single step.

With this solution, the assembling operation can be easily mechanised on round tables or palletised lines with suitable loading and operation units.

In fact, according to the model of the invention, the rotor (1b) and the stator (1 a) are separately mounted and fixed to an ordinary grid (2), which is provided with individual specific support means for the rotor and the stator to guarantee the perfect centring of the rotor inside the stator, once assembled.

According to another constructive version of the invention, the motor support is mounted at the centre of the grid (2) and not manufactured in one single injection-moulded piece with the grid (2).

The second version of the invention is shown in Figs. 7A to 7D and 8A to 8D, in which the same numbers used in the previous figures identify the same components.

According to this version, the centre of the grid (2) features an opening (30) which exactly houses the support (40) of the motor that consists in a one- piece injection-moulded bearing structure comprising: the support elements

(4) converging on the support collar (4a) of the hub (5), the guide-pins (7), the centring pins (8) and the housings (9) for the female faston connectors (10).

The support (40) is fixed to the opening (30) of the grid (2) by means of elastic teeth (40a) protruding from the internal side of the support (40) and designed to elastically fit to the edge of the opening (30), as shown in Fig.

11 B.

Figs. 9 and 10 show the support (40) applied onto the grid (2) and the cover (13) hooked to the outside of the support (40).

Figs. 12,13 and 14A to 14D show a third constructive version of the invention, in which the motor support is injection-moulded in one piece with the grid (2), as in the first version above, with the housings for the female faston connectors located on the cover (13) and not on the grid (2).

The latter group of figures uses the same numbers as the previous figures to identify the same elements.

As shown in Figs. 12 and 13, the grid (2) incorporates in one injection- moulded piece the support elements (4) that converge onto the support collar (4a) of the hub (5), the guide-pins (7) and the centring pins (8).

The grid (2) is fixed to the cover (13A), whose edges feature the housings (9A) for the female faston connectors (10).