Multiple filter unit, particularly for ventilation and air conditioning systems for motor vehicles and closed environments, and provided with efficiency checking means

Claim 2

A multiple filter unit, particularly for motor vehicle ventilation and air conditioning systems, characterised by being arranged for introduction and stable insertion as a complete interchangeable unit (10) into the air intake duct (7) in motor vehicles, and comprising: - a substantially rigid casing (11) having a cross-sectional shape corresponding to that of the intake duct (7) into which it is inserted, but of slightly smaller dimensions; - an outer, rearwardly tapering covering (12) of elastic, flexible material, for example foamed material, on said casing (11) to enable said casing (11) to be forced into and retained in said duct (7); - a series of filter elements (13, 15, 16, 17, 18) constituted by mechanical and chemical filters disposed in a predetermined order for the complete filtration and purification of the air; - means for gripping and extracting the filter unit, such as a transverse bar (19) provided with a gripping ring (19a) and connected to the casing (11); - means for checking the state of efficiency of the individual elements (13, 15 to 18) or of the filter unit (10) overall.

Claim 3

A filter unit as claimed in claim 1, characterised by comprising, in the fluid flow direction: - a first filter element (13) constituted by a coarse inertial separating filter for the coarse solid particulate matter of diameter greater than 1 micron; - a perimetral spacer (14); - a second filter element (15) constituted by a finer inertial separating filter for solid particulate matter of diameter less than 1 micron; - a third filter element (16) constituted by an absolute separating filter or a sieve, for retaining residual minor particles suspended in the flow; - a fourth filter element (17) constituted by adsorbent solids or selective molecular sieves, used either individually or in combination with each other, for eliminating pollutant gases; - a fifth filter element (18) constituted by a catalyst, particularly for eliminating the residual C0.

Claim 4

A filter unit as claimed in claims 1 or 2, characterised in that one of the filter elements can be impregnated or mixed with a deodorant substance.

Claim 5

A filter unit as claimed in any one of claims 1 to 3, characterised in that the individual elements (13, 15 to 18) of the filter unit (10) are of such thickness and/or material and/or operating conditions that their degradation and life is substantially equal for all.

Claim 6

A filter unit as claimed in any one of claims 1 to 4, characterised in that the means for checking the state of efficiency of each individual element (13, 15 to 18) or of the filter unit (10) overall are constituted by warning strips or tapes (13a, 15a to 18a) of the same material as the filters with colours or decolorations or particular signs for comparison purposes, they being disposed to the rear of each individual element (13, 15 to 18), preferably in a trasverse direction, and having dimensions such as to be traversed by a significant air flow, said warning tapes (13a, 15a to 18a) being extractable individually or, if the ends projecting out of the casing are joined together, extractable altogether simultaneously for the periodical checking of the state of efficiency of the filters at successive times.

Claim 7

A filter unit as claimed in any one of claims 1 to 4, characterised in that the means for checking the state of efficiency of the filter unit (10) overall comprise a tube (21) of plastics material or the like which axially passes through all the elements (13, 15 to 18) of the filter unit (10) and is associated at one of its ends with a diaphragm (22) sensitive to the increase in the pressure difference created between the upstream and downstream sides of the filter unit (10) by virtue of its progressive clogging, said diaphragm (22) being connected to electrical, visual and/or acoustic means for checking and indicating its deformation and for signalling when a predetermined limiting deformation has been attained, said diaphragm (22) also operating, simultaneously with the attainment of the limiting deformation on account of total clogging of the filter unit (10), Means for stopping the operation of the vehicle electric fan (8) in order to prevent it being started under conditions which would cause it to become damaged.

Claim 8

A filter unit as claimed in claim 6, characterised in that said diaphragm (22) is disposed at the front end of the axial tube so as to enable it to be directly inspected from the outside and to be able to know when the filter unit (10) is completely spent, either by the fact of the diaphragm (22) rupturing, where said diaphragm (22) is sized for determined limiting pressure difference values, or by the fact of its becoming blocked in the position at which limiting deformation is attained, for example by elastic, magnetic or like retention means.

Claim 9

A multiple filter unit for closed environments, characterised by comprising: - a rigid outer casing (31) of metal, plastics material or the like, of a suitable cross-section for fitting into seats provided on a wall or on a glass pane, and provided with a flange (31a) with passage holes for screws or the like for its fixing to the fixed structure, and with seal gaskets; - a filter unit assembly (30) divided into two separate parts (30', 30") each contained in a rigid inner casing (33, 38) of cardboard, pastics material or the like; - a low-speed electric fan (32) disposed between the two filter units (30', 30") for creating the suction necessary for the operation of the entire filter assembly.

Claim 10

A multiple filter unit for closed environments, characterised by comprising: - a rigid outer casing (31) of metal, plastics material or the like, of a suitable cross-section for fitting into seats provided on a wall or on a glass pane, and provided with a flange (31a) with passage holes for screws or the like for its fixing to the fixed structure, and with seal gaskets; - a filter unit assembly (30) divided into two separate parts (30', 30") each contained in a rigid inner casing (33, 38) of cardboard, pastics material or the like; - a low-speed electric fan (32) disposed between the two filter units (30', 30") for creating the suction necessary for the operation of the entire filter assembly.

Claim 11

A multiple filter unit for closed environments as claimed in claim 8, characterised in that the first part (30') of the filter unit assembly (30) comprises: - a first inner rigid casing (33) of cardboard, plastics material or the like, surrounded by a layer of flexible material (34), for example foamed plastics, of such dimensions as to create a sufficient forced and retention fit inside the rigid outer casing (31), said first rigid casing (33) containing a first filter element (35) constituted by a coarse separating filter, a peripheral spacer (36) and a second filter element (37) constituted by a current-fed electrostatic precipitator and/or by a second inertial separating filter, said first part (30') of the filter unit assembly (30) being removable to allow regeneration and thus re-utilisation of the filter elements (35, 37), and in that the second part (30") of the filter unit assembly (30) comprises: - a second inner rigid casing (38) of cardboard, plastics material or the like, surrounded by a layer of flexible material (39), for example foamed plastics, of such dimensions as to create a sufficient forced and retention fit inside the rigid outer casing (31), said second rigid inner casing (38) containing a third filter element (40) constituted by an absolute separating filter or a sieve, for retaining residual minor particles, a fourth filter element (41) constituted by adsorbent solids or by selective molecular sieves, used either individually or in combination with each other, for eliminating pollutant gases, and a fifth filter element (42) constituted by a catalyst particularly for eliminating C0.

Claim 12

A filter unit as claimed in claims 8 or 9, characterised by comprising means for checking the state of efficiency of each individual element (35, 37, 40 to 42) of the unit (30), and constituted for example by warning strips or tapes with colours or decolorations or particular signs for comparison purposes, and disposed to the rear of each individual element (35, 37, 40 to 42) preferably in a transverse direction, or by directly viewing the colour assumed by the various elements (35, 37, 40 to 42) of the filter unit (30), or other similar indications, either through apertures provided in the outer (31) and inner (33, 38) casings, or through transparent casings, or by diaphragm means for measuring the pressure difference.

Claim 13

A filter unit as claimed in any one of claims 8 to 10, characterised in that, when in the form of an embodiment without the electric fan (32), it can be adapted for fitting into the inlet mouth of an air conditioner or air conditioning system, using for its operation the suction created by the conditioner itself or by said system.