Abstract:
An air-distribution device based upon the Coanda-effect comprises two mobile elements that move in synchronism and in phase opposition for distributing an air flow into two ducts.

Description:
SUMMARY OF THE INVENTION 
   The present invention relates to Coanda-effect air-distributing devices of the type comprising a duct set upstream that branches off into a number of ducts set downstream and means designed to deflect the flow of air that traverses said duct set upstream into one or the other of said ducts set downstream, exploiting the Coanda effect. 
   The Coanda effect is the phenomenon whereby a flow of air exiting from a duct tends to “stick” to a wall that is adjacent to it. In a device previously proposed by the present applicant, the aforesaid means of deviation by the Coanda effect comprise a first mobile element, which is provided on a wall of the duct set upstream in the proximity of the inlet of one of the ducts set downstream and can be displaced between a first position, in which it does not interfere with the flow of air through the duct set upstream, and a second position, in which it projects into said flow, so that, in the aforesaid first position of the mobile element, the flow enters a first duct set downstream, remaining adherent to a wall thereof by the Coanda effect, whilst, in the aforesaid second position of the mobile element, the flow that traverses the duct set upstream tends to adhere to a wall of a second duct set downstream that is opposite to said first wall, so that the flow enters the aforesaid second duct set downstream. 
   The purpose of the present invention is to provide an air-distribution device based upon the Coanda effect of the type indicated above that will be even more efficient than the devices proposed up to now. 
   In order to achieve said purpose, the subject of the invention is a Coanda-effect air-distributing device having the characteristics indicated above and characterized moreover in that the means of deviation of the air by the Coanda effect comprise a second mobile element, which is set on the aforesaid second wall and can be displaced between a first position, in which it does not interfere with the flow of air in the duct set upstream and a second position, in which it projects into said flow, and in that said first and second mobile elements are displaceable in synchronism with one another so that when said first mobile element is in its first position, the second mobile element is in its second position, whereas, conversely, when said first mobile element is in its second position, the aforesaid second element is in its first position. 
   Thanks to the characteristics indicated above, the means of deviation of the air by the Coanda effect according to the invention are more efficient and reliable than the systems so far proposed. 
   In a preferred embodiment, the aforesaid first and second mobile elements form an integral part of a single mobile member. Preferably, said mobile member is mounted oscillating on the structure that defines said main duct about an axis of articulation. 
   Once again according to the invention, there are provided actuator means for actuating each mobile element, said means being preferably selected between electromagnetic actuators, piezoelectric actuators, shape-memory actuators, fluid actuators, and electric motors. 
   A preferred application of the air-distributing device described above relates to the air-distribution systems associated to the dashboards of motor vehicles. It is, however, evident that the distributing device according to the invention is of general application. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described with reference to an example of application to the dashboard of a motor vehicle, as is illustrated in the annexed drawings, in which: 
       FIG. 1  is a diagram illustrating the principle underlying the air-distribution system according to the invention; 
       FIG. 2  is a partial schematic, perspective view of an air-distribution system for the dashboard of a motor vehicle according to the invention; 
       FIG. 3  is a view, at an enlarged scale, of a detail of  FIG. 2 ; 
       FIGS. 4 ,  5  and  6  are cross-sectional views, at an enlarged scale, of a detail of  FIG. 3 , which show the system according to the invention in different conditions of operation; 
       FIG. 7  is a perspective schematic view of a detail of  FIGS. 4–6 ; 
       FIG. 8  is a schematic view of the actuator of the item represented in  FIG. 7 ; and 
       FIG. 9  illustrates a variant of  FIG. 7 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In  FIG. 1 , the reference number  1  designates as a whole a dashboard (illustrated only schematically) of a motor vehicle, inside which there is provided an air-distribution system  2 . The system  2  comprises a main duct  3 , which receives air from an air-conditioning system, including a main fan  4  and a heater/evaporator  5 . The main duct  3  gives out into a manifold or rail  6 , from which there branch off four auxiliary ducts  7 , distributed in parallel along the dashboard, one pair on the driver side, and one pair on the passenger side, each pair comprising a duct adjacent to the central part of the dashboard and a duct closer to a side window of the motor vehicle. Each auxiliary duct  7  branches off into three terminal ducts  8 ,  9 ,  10  (see also  FIG. 2 ), each of which terminates in air-outflow openings in the passenger compartment of the motor vehicle. In particular, the duct  8  supplies air to openings  11 , arranged at the base of the windscreen, for directing a flow of air onto the internal surface of the latter. The duct  9  terminates in one or more openings  12 , arranged at the front on the dashboard, for directing air towards the passenger compartment of the motor vehicle, and the duct  10  terminates in one or more openings  13 , which direct a flow of air towards the floor of the passenger compartment. 
   In the area in which each auxiliary duct  7  branches off into the three terminal ducts  8 ,  9 ,  10 , there are provided means for distributing the air flow between the terminal ducts, which will be illustrated in detail in what follows. 
   An important characteristic, which also forms a subject of a separate application, lies in the fact that each of the auxiliary ducts  7  is provided with an additional and independent unit for regulating at least one characteristic of the air flow. In particular, associated to each auxiliary duct  7  is, in the example of embodiment illustrated, a unit  14  for regulating the flow rate of the air, and a unit  15  for regulating the temperature of the air. In the example illustrated, the unit  14  comprises a fan with corresponding electric controlling motor, whilst the unit  15  comprises a section of duct in which an electrical resistor is inserted. 
   Therefore, the distribution system illustrated enables adjustment of the flow and/or the temperature of the flow of air exiting from the openings  11 ,  12 ,  13 , separately for each of the auxiliary ducts  7 , i.e., in the case of the example illustrated, separately for the driver area and for the passenger area and, for each of said areas, separately for the central area of the dashboard and for the area adjacent to the window. 
     FIGS. 4–6  illustrate the way in which the distribution of the air coming from each auxiliary duct  7  into the terminal ducts  8 ,  9 ,  10  that branch off therefrom is controlled. 
   With reference to said figures, the first terminal duct  8  has a first curved wall  8   a  set on the prolongation of a corresponding wall  7   a  of the auxiliary duct  7 . In a position corresponding to said wall, associated to the duct is a mobile element  16  that is mounted oscillating about an axis of articulation  17  on the wall  7   a  and can be displaced between a first position, visible in  FIG. 4 , and a second position, visible in  FIG. 5 . In the first position illustrated in  FIG. 4 , the mobile element  16  does not interfere with the air flow F coming from the auxiliary duct  7 , so that said flow remains “stuck” to the walls  7   a  and  8   a  and consequently enters the first terminal duct  8 . In the second position of the mobile element  16 , illustrated in  FIG. 5 , said mobile element projects into the flow F so that it invites said flow to adhere, by the Coanda effect, to a curved wall  8   b  opposite to the wall  8   a  and situated at the inlet of the two terminal ducts  9 ,  10 . 
   To obtain a more efficient distribution of the flow between the terminal duct  8  and the inlets  8   c  of the two terminal ducts  9 ,  10 , there is provided, according to the invention, a further mobile element  18 , which can be displaced between a first position, in which it does not interfere with the flow F (illustrated in  FIG. 5 ), and a second position, in which it projects into the flow F (illustrated in  FIG. 4 ). The two mobile elements  16 ,  18  must be controlled in synchronism so that when the mobile element  16  is in its first position the mobile element  18  is in its second position ( FIG. 4 ), whereas when the first mobile element  16  is in its second position the second mobile element  18  is in its first position ( FIG. 5 ). In the case of the example illustrated, this is obtained very simply in so far as the mobile element  16  and the mobile element  18  form part of a single member  19 , mounted articulated on the structure of the duct  7  about the axis  17 . As may be seen in  FIG. 7 , the member  19  comprises a vaned part, which defines the element  16 , and a U-shaped part, rigidly connected to the vane  16  and substantially orthogonal thereto, which includes a bent cross member that constitutes the mobile element  18 . 
   In the condition illustrated in  FIG. 4 , the mobile element  18  encourages “sticking” of the flow F to the wall  8  in so far as it prevents the flow F from remaining adherent to the wall  8   b . In the condition illustrated in  FIG. 5 , since the element  18  does not disturb the flow F it enables said flow top stick to the wall  8   b  by the Coanda effect. 
   As may be seen in  FIGS. 4–6 , a further mobile member  19 , which includes a first mobile element  16  and a second mobile element  18  altogether similar to the ones described above, is moreover provided in a position corresponding to the inlets  8   c  of the two terminal ducts  9 ,  10 . The mode of operation of said second mobile member is altogether similar to what is described above. In the condition illustrated in  FIG. 5 , the second mobile member favours sticking, by the Coanda effect, of the flow to a first curved wall  9   a  of the terminal duct  9 , so that the flow enters said duct, whereas, in the condition illustrated in  FIG. 6 , it favours sticking of the flow to a wall  10   a , which is also curved, of the terminal duct  10 , so that the flow enters said duct. Furthermore, the mobile element  18  in this case also performs the function of interfering (in the condition illustrated in  FIG. 4 ) with a possible part of the main flow F that were to enter the inlets  8   c , bestowing thereon a circulatory motion C ( FIG. 4 ) that “obstructs” the inlets  8   c , reducing to a minimum any undesired leakages of air into the ducts  9 ,  10 . 
   For the same purpose, in a position corresponding to the inlets of the terminal duct  8  and of the terminal duct  9  there are provided air-recirculation passages  20 , which are shaped so that in the conditions illustrated in  FIG. 5  and  FIG. 6 , respectively, any possible undesired leakages of air give rise to an air circulation C that obstructs the duct into which the flow is to be directed. 
   The mobile members  19  are controlled by actuators of any type, for example electromagnetic actuators (such as the actuator  40  in  FIG. 8 ), or piezoelectric actuators, or shape-memory actuators. 
     FIG. 8  illustrates a variant of the member  19 , in which the U-shaped portion defining the mobile element  18  also includes vanes  21  having the function of straightening the air flow. 
   Of course, without prejudice to the principle of the invention, the details of construction and the embodiments may vary widely with respect to what is described and illustrated herein, without thereby departing from the scope of the present invention.