VEHICLE AIR FILTER, FOR A HEATING, VENTILATION AND AIR CONDITIONING SYSTEM

Description

VEHICLE AIR FILTER, FOR A HEATING SYSTEM VENTILATION AND AIR CONDITIONING DESCRIPTION Technical field The present invention relates to a vehicle air filter for a heating, ventilation and air conditioning system. Context As is known, vehicles are equipped with a heating, ventilation and air conditioning system, commonly referred to by the acronym HVAC (acronym for the English terms Heating, Ventilating, Air Conditioning), which takes air from an outside environment via a fan and sends it into the vehicle's passenger compartment through a duct equipped with heat exchangers to heat, cool and dehumidify the air flow. The HVAC system is equipped with an air filter, whose filter material is a pleated sheet. This air filter is typically located upstream of the fan and is designed to trap any dust and particulate matter contained in the outside air. The most common known solutions are equipped with two rigid or semi-rigid lateral bands, arranged at opposite lateral edges of the pleated sheet and defining a sort of frame that stably maintains the pleated shape of the sheet and, therefore, its overall dimensions. To achieve a large filtering surface area in the pleated sheet, conventional air filters are generally relatively large, especially in the longitudinal direction, i.e., perpendicular to the fold lines of the sheet. However, having a large air filter makes it difficult to install and / or replace the air filter in the HVAC system. Specifically, careful design of the entire HVAC system, regarding the layout of its components and the available space in the vehicle, is necessary to ensure operators have sufficient space to easily access the air filter housing, remove the air filter to be replaced, and insert a new one. There is therefore a need to improve the air filters of vehicle HVAC systems, in order to make these installation / replacement operations easier. The aim of the present invention is, therefore, to provide a vehicle air filter, for a heating, ventilation and air conditioning system, which allows the above-mentioned requirement to be met. Summary According to the present invention, a vehicle air filter is provided, for a heating, ventilation and air conditioning system, as defined in claim 1. The dependent claims define specific embodiments of the present invention. Brief description of the drawings For a better understanding of the present invention, some embodiments thereof are now described, purely by way of non-limiting example, with reference to the attached drawings, in which: - figure 1 illustrates by way of example a vehicle on which an air filter according to the present invention is installed; - Figure 2 is a schematic cross-sectional view of a vehicle heating, ventilation and air conditioning system, in which a preferred embodiment of the air filter according to the present invention is installed; - figure 3 illustrates, in perspective and on an enlarged scale, the air filter of figure 2, in an undeformed reference condition; - figure 4 is similar to figure 3 and shows the air filter in a compacted condition; - Figure 5 illustrates a sheet of flat filter material used to form the air filter of the present invention; and - figure 6 is a schematic cross-section along the section plane identified by the trace VI-VI in figure 2. Description of preferred embodiments Figure 2 illustrates, in a partial and schematic way, a heating, ventilation and air conditioning system, hereinafter referred to as the HVAC system, which is installed on a vehicle 1, in particular on a car, which in turn is illustrated by way of example in Figure 1. The HVAC system has the function of air conditioning the internal volume of the passenger compartment of vehicle 1, with particular attention to the volume corresponding to the seats in which the occupants of vehicle 1 are located. With reference to figure 2, the HVAC system comprises a plurality of ventilation vents 10 arranged inside the passenger compartment, and an air handling unit 11, suitable for heating, cooling and / or dehumidifying a flow of air which is introduced into the passenger compartment through the ventilation vents 10. The HVAC system also includes a ventilation device 12 configured to generate the aforementioned airflow. Specifically, the ventilation device 12 comprises a fan driven by an electric motor. In particular, the air handling unit 11 is arranged inside a dashboard (not shown) of the vehicle 1, while the ventilation device 12 may also be housed in the dashboard, or it may be arranged externally, forward, i.e., in front of the passenger compartment. Alternatively, the air handling unit 11 could be arranged behind the passenger compartment, together with the ventilation device. Still referring to figure 2, the ventilation device 12 has an outlet 13 which is connected to an inlet 14 of the air handling unit 11 via a supply duct 15. In turn, the air handling unit 11 is connected to the ventilation outlets 10 via distribution ducts 16. Starting from the outlet 13 of the ventilation device 12 towards the inlet 14 of the air handling unit 11, the supply duct 15 has a cross-section (obtained via section planes orthogonal to the average advancement axis of the air flow) with variable dimensions, in particular to adapt to the spaces available in the vehicle 1. In the example illustrated, the cross-section of the supply duct 15 in the vicinity of the inlet 14 has a larger area than that in the vicinity of the outlet 13. The HVAC system further comprises: at least one external air intake 20, positioned so as to draw air from an external environment (i.e. from the atmosphere) and communicating with an inlet of the ventilation device 12; and a box or casing 21, of a substantially parallelepiped shape, defining a seat 22 which houses an air filter 23. The housing 21 with the air filter 23 is preferably arranged downstream of the ventilation device 12, i.e. along the supply duct 15, for example at the inlet 14 of the air handling unit 11. According to a variant not illustrated, the housing 21 with the air filter 23 can be arranged between the external air intake 20 and the ventilation device 12. Furthermore, preferably, the HVAC system comprises an internal air intake 24 connected to the ventilation device 12 and arranged in such a way as to draw air from the passenger compartment itself and obtain recirculation, for example as an alternative to the air drawn from the external air intake 20. With reference to figure 3, the air filter 23 extends along a longitudinal axis 30 and a transverse axis 31, orthogonal to each other, and comprises a sheet 32 ​​which is made of filtering material, of a type known in itself and not described in detail, and is pleated, so that it is made up of a plurality of rectangular strips 33, which are flat, face each other longitudinally and are joined to the adjacent strips 33 by folding lines 34, which in turn are rectilinear, orthogonal to the longitudinal axis 30 and parallel to the transverse axis 31. In practice, the sheet 32 ​​has an accordion or bellows configuration, as in common solutions for vehicle air filters. The fold lines 34 define respective virtual hinges, so that the inclination of each strip 33 with respect to the adjacent strips 33 can be varied. The distance between two consecutive folding lines 34 defines a width of the strips 33, which is always the same for the entire sheet 32, and also represents the maximum height of the air filter 23 (where this height is measured orthogonally to the longitudinal axis 30 and the transverse axis 31). Overall, the sheet 31 can be compacted (Figure 4) and extended along the longitudinal axis 30, based on the inclination angle between the strips 33 at the fold lines 34. In this way, the overall length of the air filter 23 is also varied along the longitudinal axis 30. In this regard, according to the present invention, the air filter 23 comprises at least one elastically deformable member 35, which is constituted by an element distinct from the sheet 32, preferably extends along the entire length of the sheet 32, is coupled to the latter and has a stiffness greater than that of the material of the sheet 32, so as to maintain it in a reference condition (i.e., it is able to maintain the inclination angles between the strips 33 at approximately a predefined reference value). In practice, this reference condition corresponds to a situation in which the elastically deformable member 35 is in a rest condition.However, the elastically deformable member 35 is configured so as to deform elastically when the sheet 32 ​​is subjected to an external action, directed along the longitudinal axis 30, so as to allow the set of strips 33 to compact (allowing a reduction of the inclination angles in correspondence with the folding lines 34), in order to shorten the overall length of the air filter 23. Such external action, for example, can be represented by a manual action performed by an operator who is responsible for installing the air filter 23 in the seat 22, as will also be described below. The elasticity of the elastically deformable member 35, in addition to allowing compaction, has the function of returning the sheet 32 ​​to its reference condition (Figure 3), once the external compression action has ceased. In other words, the air filter 23 is free to extend longitudinally autonomously (i.e. without any external intervention) to increase its length again, thereby reaching the previous reference condition. In other words, thanks to the elasticity of the elastically deformable member 35, the sheet 32 ​​has a so-called shape memory that tends to always return it to the reference condition. In summary: starting from the reference condition, the bellows or accordion shape of the air filter 23 can be manually compressed, and then automatically re-extend. In this regard, the air filter 23 is devoid of rigid (or relatively rigid) supports or frames, which in known solutions perform a retention function to prevent longitudinal compression and, therefore, a reduction in the length of the sheet 32 ​​compared to its reference condition. Compared to known solutions, the absence of a frame also leads to a reduction in overall weight. With reference to figure 6, along the transverse axis 31, the sheet 32 ​​ends with two lateral portions 36, opposite to each other, whose end edges are pleated, while the air filter 23 comprises two elastically deformable members 35, which are equal to each other and are arranged in positions spaced apart from each other along the transverse axis 31, preferably in correspondence, respectively, with the lateral portions 36 (i.e., in proximity to the end edges). Figure 5 shows the sheet 32, with the elastically deformable members 35, in a flat shape, before being plastically deformed to obtain the pleated configuration of Figure 3 during the production of the filter 23. Preferably, each elastically deformable member 35 lies on an external face of the sheet 32, and is fixed to this external face (for example, by gluing, overmolding or melting material); alternatively, each elastically deformable member 35 is embedded in the material of the sheet 32 ​​itself. Thanks to these configurations, the elastically deformable members 35 assume the same bellows (or accordion) shape as the sheet 32.In other words, with reference to figure 3, each elastically deformable member 35 is made up of a series of portions 38, which are respectively arranged on the strips 33, are transversal to the folding lines 34 of the sheet 32, and are joined to the adjacent portions 38 by means of folding points 39 arranged in correspondence with the same folding lines 34. The compaction and subsequent extension of the sheet 32 ​​is permitted by the bending elasticity of the elastically deformable members 35 in correspondence with the folding points 39. For example, each elastically deformable member 35 is made of metallic material. Preferably, each elastically deformable member 35 consists of a wire element or an elastically flexible sheet element. It is advisable to choose the elastically deformable member 35 so that it has a limited thickness (measured orthogonally to the two opposite faces of the sheet 32), in order to hinder the longitudinal compaction of the sheet 32 ​​as little as possible. For example, it is advisable to choose the thickness of the elastically deformable member 35 so as to allow the strips 33 of the sheet 32 ​​to come into contact with each other along the longitudinal axis 30, and therefore achieve a condition of maximum compaction of the sheet 32. As mentioned above, the air filter 23 can be compacted longitudinally thanks to an external compression action during installation operations, so that it can be easily inserted into the casing 21, for example during a replacement and / or maintenance operation. Once compacted, the air filter 23 is easier for operators to handle, having a reduced length. In particular, the air filter 23 may be equipped with a releasable retention device (not illustrated) to be held in the compacted condition provisionally, i.e. temporarily. With reference to figure 2, the seat 22 ends longitudinally with an access opening 40, closed in a fluid-tight manner by a cover 41 (for example, a rotating door) and which can be opened to carry out insertion and extraction operations on the air filter 23. At the same time, with reference to figure 6, along the transverse axis 31 the casing 21 ends with two lateral channels 43, opposite to each other and parallel to the longitudinal axis 30: the lateral channels 43 have (in a direction orthogonal to the axes 30, 31) a height that is constant and which approximates by excess the height of the air filter 23, so as to define a guide, i.e. so as to guide the lateral end portions 36 respectively during the insertion operations of the air filter 23: in fact, after having inserted a longitudinal end of the filter 23 into the access opening 40 (and after having released the aforementioned retention device, if provided), the filter 23 is left free to return to its reference condition, so that it automatically occupies the seat 22 under the guidance of the channels 43.The latter, in practice, favor the extension of the lateral portions 36 towards the reference condition, in order to avoid deviations in other directions or jamming during such extension. According to variants not illustrated, it is not excluded that the ducts 43 may have a slight curvature along the longitudinal axis 30 (for example, set by design based on the position and size of the HVAC system components); in this case, sliding in the ducts 43 the air filter 23 goes to longitudinally occupy the seat 22, therefore it assumes a curved condition which is imposed by the ducts 43 and which does not correspond exactly to the reference condition that the air filter 23 had outside the casing 21. It is also possible that the air filter 23 in the reference condition (undeformed) has a length slightly greater than that of the seat 22, so that it remains slightly compressed longitudinally by the cover 41 when the latter closes the access opening 40. It is evident from the above that the air filter 23, being able to be elastically compacted, is shorter and therefore easier to handle during installation operations; furthermore, thanks to its ability to automatically extend towards its reference condition, under the push of the elastically deformable member 35 and under the guidance of the channels 43, the insertion of the air filter 23 into the seat 22 is also facilitated, and potentially faster, compared to known solutions equipped with a rigid frame that supports the pleated filter sheet. The proposed solution, then, is relatively simple; In particular, it does not involve any particular complexity in coupling the elastically deformable member 35 to the sheet 32 ​​during production. Furthermore, as anticipated above, the proposed solution is lighter than known solutions equipped with a support frame. Finally, it is clear that modifications and variations can be made to the air filter 23 described above with reference to the attached figures without departing from the scope of the present invention, as defined in the attached claims. In particular, the elastically deformable member 35 could have a shape and / or position different from those illustrated by way of example; and / or the air filter 23 could be equipped with a greater number of elastically deformable members 35; and / or each elastically deformable member 35 could not be continuous, i.e. it could be made up of a series of flexible elements, distinct and spaced from each other, respectively defining the folding points 39; and / or each deformable member 35 could engage only a part of the sheet 32 ​​(i.e. act elastically only on some of the folding lines 34).

Claims

1. Vehicle air filter (23), for a heating, ventilation and air conditioning (HVAC) system, the vehicle air filter extending along a longitudinal axis (30) and a transverse axis (31) orthogonal to each other and comprising a sheet (32) made of filter material and pleated so as to have a plurality of folding lines (34) parallel to said transverse axis (31); characterised in that it further comprises at least one elastically deformable member (35) which is distinct from said sheet (32) and is coupled to said sheet (32) in such a way as to allow: a) a compaction of said sheet (32) along the longitudinal axis (30), starting from a reference condition, in response to an external compressive action along the longitudinal axis (30); b) an automatic extension of said sheet (32) towards said reference condition once said external compressive action has ceased.

2. Vehicle air filter according to claim 1, wherein the vehicle air filter (23) comprises at least two elastically deformable members (35), equal to each other and spaced apart along said transverse axis (31).

3. Vehicle air filter according to claim 2, wherein said sheet (32) ends, along said transverse axis (31), with two lateral portions (36) opposite each other, and wherein said elastically deformable members (35) are respectively arranged in correspondence with said lateral portions (36).

4. Vehicle air filter according to any of the preceding claims, wherein said elastically deformable member (35) comprises at least one elastically flexible element lying on one face of said sheet (32), or is embedded in said sheet (32), so as to have the same pleated shape as said sheet (32).

5. Vehicle air filter according to claim 4, wherein said elastically flexible element is constituted by an elastically flexible wire or an elastically flexible sheet.

6. Vehicle air filter according to any of the preceding claims, wherein said elastically deformable member (35) is made of a more rigid material than the filtering material of said sheet (32).

7. Vehicle air filter according to claim 6, wherein said elastically deformable member (35) is made of metallic material.

8. A vehicle heating, ventilation and air conditioning (HVAC) system comprising: a) an external air intake (20); b) a ventilation device (12) for drawing an air flow from said external air intake (20) and supplying said air flow, in use, to a vehicle passenger compartment; c) an air handling unit (11) for heating, cooling and / or dehumidifying said air flow; d) a supply duct (15) connecting an outlet (13) of said ventilation device (12) to an inlet (14) of said air handling unit (11); e) a casing (21) housing an air filter (23) for filtering said air flow; wherein said air filter (23) is a vehicle air filter according to any of the preceding claims.

9. Vehicle heating, ventilation and air conditioning system according to claim 8, wherein said casing (21) is arranged along said supply duct (15).

10. Vehicle heating, ventilation and air conditioning system according to claim 9, wherein said housing (21) is arranged at the inlet (14) of said air handling unit (11).

11. Vehicle heating, ventilation and air conditioning system according to any of claims 8 to 10, wherein said sheet (32) ends, along said transverse axis (31), with two lateral portions (36) opposite each other and having, orthogonally to said longitudinal and transverse axes (30,31), a first height; and wherein said casing (21) comprises two lateral channels (43), which are opposite each other along said transverse axis (31) and have, orthogonally to said longitudinal and transverse axes (30,31), a second height; and wherein said second height is constant and approximates said first height in such a way as to define a guide for said lateral portions (36) during an insertion operation into said casing (21).