EP3321509B1

EP3321509B1 - A shutter for fan

Info

Publication number: EP3321509B1
Application number: EP16425104.3A
Authority: EP
Inventors: Riccardo Danio
Original assignee: Munters Italy SpA
Current assignee: Munters Italy SpA
Priority date: 2016-11-10
Filing date: 2016-11-10
Publication date: 2019-08-07
Anticipated expiration: 2036-11-10
Also published as: EP3321509A1; DK3321509T3; CN108071606A; ES2753592T3; CN108071606B

Description

The present invention relates in general to the field of axial electric fans, of the type provided with a shutter which intercepts the passage of fluid in the duct of the electric fan. More particularly, the present invention relates to a fan shutter.
There are known shutter solutions wherein the movement of the shutter blades is controlled by levers operated by a centrifugal governor device. To this end, the governor device rotates integrally with the fan. A solution of this type is known for example from US 5,288,202 or CN 85 203 799 U .
Even simpler and more cost-effective solutions are known, wherein the movement of the shutter blades is directly caused by the air flow between the inlet and the outlet of the passage in which the shutter is positioned, this air flow being produced by the fan itself and generating a moment on the blades due to their hinging to the shutter's frame. In such solutions, a return element can be provided, typically a spring, connected on the one side to the frame and on the other to the plurality of blades, which cooperates with the flow of air to obtain the movement of the shutter blade.
In such known solutions, it is necessary to correctly size the return element in such a way that does not negatively affect the operation of the shutter. For example, if, all other conditions being equal, thicker and heavier blades are used, a return element designed to work with thinner and lighter blades may not function properly. This is not only a problem during the design, it can also occur during the use of the shutter, since the accumulation of dust and dirt on the blades can cause the weight of the same to vary significantly, possibly resulting in the return element failing to operate properly.
An aim of the present invention is to provide a fan shutter capable of overcoming at least in part the aforementioned drawbacks.
In view of this aim, the object of the invention is a fan shutter, comprising

a frame provided with a pair of lateral uprights and defining a passage for a flow of air positioned between the lateral uprights, and having an inlet and an outlet,
a plurality of blades hinged to the lateral uprights and rotatable between an open passage configuration and a closed passage configuration, wherein the plurality of blades is able to assume the open passage configuration through the direct effect of an air flow between the inlet and outlet of the passage, and
a return element connected to the plurality of blades and arranged in such a way as to apply on the blades a return force to return the blades towards the closed passage configuration,
wherein the plurality of blades comprises an upper blade array and a lower blade array, the upper blades being interconnected so as to simultaneously rotate in the same direction of rotation and being pivoted in such a way as to tend to assume by gravity one of said open or closed passage configurations, and the lower blades being interconnected so as to rotate simultaneously in the same direction of rotation and being pivoted in such a way as to tend to assume by gravity the other of said open or closed passage configurations,
wherein a drive is provided which connects the upper blade array to the lower blade array in such a way that the two blade arrays have opposite directions of rotation, and the tendency of the upper blades to assume by gravity one of said open or closed passage configurations is countered by the tendency of the lower blades to assume by gravity the other of said open or closed passage configurations, and
wherein the return element is connected to at least one of said upper or lower blade arrays and is arranged in such a way as to apply on the blade array(s) a maximum moment of the return force in the closed passage configuration and a minimum moment of the return force in the open passage configuration.

Preferred embodiments of the invention are defined in the dependent claims, which are intended as an integral part of the present description.
In a shutter according to the invention, the action of the force of gravity on the upper blades is counteracted by the action of this force on the lower blades due to the dynamic link between these blades, operated by the drive. Consequently, if the number of upper blades is equal to the number of lower blades, there is a substantial balance of forces, whereby it is obtained that the weight has no significant influence on the blade actuator mechanism; the shutter is therefore fundamentally neutral. In the case in which the number of upper blades is slightly different from that of the lower blades (for example by 1-3 blades), there is nevertheless a substantial reduction in the effect of the weight of the blades on the actuating mechanism of the same. There is therefore a substantial neutralization or reduction of the effect of the weight of the blades on the shutter's opening capacity: also with thicker and heavier components the degree of opening is not significantly affected. Therefore, in practice, when the return element is sized, only the action of the air flow on the blades needs to be taken into account, or, at most, also the weight of only the number of blades constituting the difference between the upper array and the lower array. For the same reason, the accumulation of dust and dirt on the blades which adds to the weight has far less of a limiting effect on the opening compared to traditional solutions.
The invention relates to shutters designed as a separate element that is mounted on an electric fan unit, as well as to shutters which are integrated in the electric fan unit itself. In the latter case, the frame of the shutter can be constituted by the same casing which encloses the impeller of the electric fan.
Further features and advantages of the shutter according to the invention will become more apparent in the following detailed description of an embodiment of the invention, made with reference to the appended drawings, provided purely to be illustrative and nonlimiting, wherein:

figure 1 is a perspective view of a first embodiment of the fan shutter according to the invention;
figures 2 and 3 are sectional views of the shutter of figure 1, respectively in the closed configuration and in the open configuration;
figure 4 is a perspective view of a second embodiment of the fan shutter according to the invention; and
figures 5 and 6 are sectional views of the shutter of figure 4, respectively in the closed configuration and in the open configuration.

Figures 1 to 3 illustrate a first embodiment of the fan shutter according to the invention. This embodiment is intended to be positioned on the discharge side of the fan impeller.
The fan is not represented in the figures, but its location would be to the right of the shutter, according to the orientation shown in figures 2 and 3. The arrow A in these figures represents the direction of the air flow.
The shutter, indicated collectively with 10, comprises a frame 11, which in the illustrated example is formed by a pair of lateral uprights 12, a pair of end cross members 13 that interconnect these uprights at their ends, and a central cross member 15 which interconnects the uprights at their intermediate positions. The frame 11 thus defines a passage for an air flow positioned between the lateral uprights 12, and having an inlet and an outlet, respectively upstream and downstream of the shutter 10 according to the direction of the air flow A. The inlet is oriented toward the electric fan.
The shutter 10 also comprises a plurality of blades 21 and 23 hinged to the lateral uprights 12 and rotatable between an open configuration (figure 3) and a closed configuration (figure 2) of the passage for the air flow. In the figures, the axes of rotation of the blades are indicated by x1 and x2. Each blade 21, 23 has a substantially rectangular shape according to a plan view. Each blade 21, 23 forms approximately a plane in a direction of extension orthogonal to the rotation axis x1, x2 of the blade 21, 23. In the respective direction of extension, each blade 21, 23 has a front portion 21a, 23a, and a rear portion 21p, 23p positioned on opposite sides of the rotation axis x1, x2 of the blade. As can be observed in figure 3, the front portion 21a, 23a has a greater extension than the rear portion 21p, 23p.
The plurality of blades comprises an upper blade array 21 and a lower blade array 23 having the opposite direction of rotation. The two blade arrays are arranged in mirror symmetry with respect to a plane passing through the central cross member 15. In the case illustrated, the number of blades is the same for the two arrays; in an embodiment not illustrated, the number of blades may be different. In the latter case, it is advisable to make the difference in the number of blades small, at most less than half of the total number of blades of the smallest array. The spatial terms used in the present description refer to the operating position of the fan, which is substantially vertical, as shown in the figures. In the example shown, in the closed position (figure 2) the upper blades 21 are lowered and the lower blades 23 are raised. Conversely, in the opening position (figure 3) the upper blades 21 are raised and the lower blades 23 are lowered. In the closed position, the short sides of the blades 21 and 23 rest against abutments 25 positioned on the lateral uprights 12 of the frame 11. The long sides of the central blades 21, 23 of each array rest against the long sides of the immediately adjacent blades 21, 23 and one long side of each end blade 21, 23 of each array rests against abutments formed on the frame 11 at the end cross members 13 or the central cross member 15. In the opening position (figure 3), the blades 21 and 23 form a certain angle, for example approximately 90°, with respect to their respective closed positions.
According to one embodiment, the blades of the upper blade array 21 and the blades of the lower blade array are arranged in mirror symmetry, i.e. the inside angle that each upper blade forms with respect to a vertical axis is equal to the inside angle that each lower blade forms with respect to the same vertical axis. According to another embodiment, a slight offset may be provided (for example of 1-5°) between the two arrays with respect to the arrangement in mirror symmetry indicated above.
Given the asymmetrical configuration of the blades 21 and 23 with respect to the respective rotation axes x1 and x2, the upper blades 21 tend, due to gravity, to assume the closed configuration, while the lower blades 23 tend to assume the open configuration. In other words, if hypothetically one raises an upper blade 21, free from any connection with the other blades 21 and 23 bringing it into the open position, and thereafter releases it, it is lowered due to gravity to assume the closed position. If instead one raises a lower blade 23, free from any connection with the other blades 21 and 23, bringing it into the closed position, and subsequently releases it, it is lowered due to gravity to assume the open position.
The upper blades 21 are interconnected in such a way as to rotate simultaneously in the same direction of rotation. In particular, the blades 21 of the upper blade array 21 are interconnected by the upper rigid connecting rod 31 positioned near one of the short sides of the blades 21a. Each blade 21 of the upper blade array 21 is hinged to the upper connecting rod 31 at a hinging point x3 positioned outside the plane formed by the blade 21. To this end, each upper blade 21 is rigidly connected to a crank 41, by which the blade 21 is hinged to the upper connecting rod 31. Of course, there are other possibilities for getting the upper blades 21 to rotate in the same direction. For example, this can be achieved by means of gear wheels.
The lower blades 23 are linked together in such a way as to rotate simultaneously in the same direction of rotation. In particular, the blades 23 of the lower blade array 23 are linked together by the lower rigid connecting rod 33 positioned near one of the short sides of the blades 23a. Each blade 23 of the lower blade array 23 is hinged to the lower connecting rod 33 at a hinging point x4 positioned outside the plane formed by the blade 23. To this end, each lower blade 23 is rigidly connected to a crank 43, through which the blade 23 is hinged to the lower connecting rod 33. Of course, there are other possibilities for getting the lower blades 23 to rotate in the same direction. For example, this can be achieved by means of gear wheels.
Furthermore, a drive is provided which connects the upper blade array 21 to the lower blade array 23 in such a way that the two blade arrays 21, 23 have opposite directions of rotation, and the tendency due to gravity of the upper blades 21 to assume the passage's closed configuration is countered by the tendency due to gravity of the lower blades 23 to assume the open configuration. If the number of blades of the upper blade array were different from the number of blades of the lower blade array, the tendencies of the two arrays would however be in reciprocal opposition.
In the illustrated example, this drive comprises an upper geared element 61 and a lower geared element 63 (for example, in the case illustrated, two geared sectors) in reciprocal engagement and having respective axes of rotation x5 and x6, positioned substantially at the level of the central cross member 15. The upper and lower connecting rods 31 and 33, beyond the respective end blades 21, 23 of the upper blade array 21 and the lower blade array 23 have respective extensions 71 and 73 hinged respectively to the upper geared element 61 and the lower geared element 63, at the respective hinging points x7 and x8.
It is thus possible to identify an upper articulated parallelogram and a lower articulated parallelogram, the vertices of which are respectively identified by:

a) the rotation axis x1 of the end blade 21 of the upper blade array 21, the hinging point x3 of the end blade 21 of the upper blade array 21 to the upper connecting rod 31, the hinging point x7 of the extension 71 of the upper connecting rod 31 to the upper geared element 61, and the rotation axis x5 of the upper geared element 61, and
b) the rotation axis x2 of the end blade 23 of the lower blade array 23, the hinging point x4 of the end blade 23 of the lower blade array 23 to the lower connecting rod 33, the hinging point x8 of the extension 73 of the lower connecting rod 33 to the lower geared element 63, and the rotation axis x6 of the lower geared element 63.

In the shutter described above, the action of the force of gravity on the blades is balanced and does not influence the mechanism: the shutter is therefore neutral. If the two blade arrays had a different number of blades, as long as the difference was small, the shutter would still be almost neutral, taking friction into account. The opening occurs by direct effect of the air flow, which generates a moment on the blades due to their hinging.
Closing occurs instead due to (at least) one elastic return element 81, for example a traction spring, connected on one side to the frame 11 and on the other to the plurality of blades 21, 23. In the illustrated example, the return element 81 is connected to the lower blade array 23 and is positioned in such a way as to apply on the blade array 23 a maximum moment of the return force in the closed configuration and a minimum in the open configuration. In particular, the elastic return element 81 is a linear elastic member having opposite ends, respectively hinged to the frame 11 and to one of the blades of the lower blade array 23, via a connecting element 83 rigidly connected to the blade 23 in question. The elastic return element 81 defines, with respect to the rotation axis x3 of said blade 23, an arm b of the variable elastic return force that is at its maximum in the closed configuration and at its minimum in the open configuration, as is shown in figures 2 and 3. In this way, the return action acting on the blades is at its maximum when the shutter is closed to encourage the sealing of the same, and at its minimum when the shutter is open, not to limit the degree of opening while allowing the shutter to close once the effect of the air flow has ceased.
Figures 4 to 6 illustrate a second embodiment of the fan shutter according to the invention. This embodiment is suitable to be arranged on the inlet side of the fan impeller. The fan is not represented in the figures, but its location would be to the left of the shutter, according to the orientation shown in figures 5 and 6. The arrow A in these figures represents the direction of the air flow.
This embodiment is substantially identical to the above; accordingly, for a detailed description thereof reference is made to what has been explained with respect to the previous embodiment. For this reason, in figures 4-6 the same numerical references were used as in figures 1-3. The embodiment of figures 4-6 differs from the previous essentially by the fact that the frame and the drive and return mechanism of the blades are positioned, with respect to the position of the rotation axes x1 and x2 of the blades 21 and 23, on the side the front portion 21a, 23a of these blades (in the previous embodiment they were arranged on the side of the rear portion 21p, 23p).
According to a further embodiment (not illustrated), the shutter can be integrated into the structure of an electric fan unit on the discharge side or on the suction side of the fan. In this case, the frame of the shutter can be constituted by a portion of the casing which contains the impeller of the electric fan.
Naturally, the constructive details of the shutter may vary widely with respect to what is described above. For example, it is possible to conceive of a shutter wherein the directions of rotation of the upper blades and the lower blades are reversed with respect to those described above. Or the drive that ensures the counter-rotation and the balancing of the two blade arrays may have a different number of gear wheels, and/or with different shapes, or also consist of a different type of drive from the geared drive, for example a lever mechanism or a belt drive, or a combination of different types of drives. Furthermore, the connection between the blades of a single array can be obtained in a different manner from the rigid connecting rod described above, for example with a series of gear wheels respectively associated with each blade, and between which are interposed counter-rotating gear wheels. Also, the method for connecting the elastic return element to the frame and to the blades may vary with respect to what is described above. Moreover, there may be multiple elastic return elements associated with one or the other blade array, or both. Also, the shape of the elastic return element may be different; instead of a linear element working in traction, it is possible, for example, to use a linear element working in compression, or even an elastic element working in torsion, arranged coaxially with the rotation axis of one of the blades. According to further embodiments, as a return element in place of the elastic element, a weight attached to one of the blades of the upper blade array or the lower blade array, via a connecting element rigidly connected to the blade in question (and similar to the element 83 described above) may be used. In this case, the return element is positioned so as to define a center of gravity whose position relative to the rotation axis of the blade determines the arm of the force of gravity (provided by the weight in question) which is at its maximum in the closed configuration and at its minimum in the open configuration.

Claims

Fan shutter, comprising
a frame (11) provided with a pair of lateral uprights (12) and defining a passage for an air flow positioned between the lateral uprights (12), and having an inlet and an outlet,
a plurality of blades (21, 23) hinged to the lateral uprights (12) and rotatable between an open passage configuration and a closed passage configuration, wherein the plurality of blades (21, 23) is able to assume the open passage configuration through the direct effect of an air flow between the inlet and outlet of the passage, and
a return element (81) connected to the plurality of blades (21, 23) and arranged in such a way as to apply on the blades (21, 23) a return force to return the blades (21, 23) towards the closed passage configuration,
characterized in that
the plurality of blades (21, 23) comprises an upper blade array (21) and a lower blade array (23), the upper blades (21) being interconnected so as to simultaneously rotate in the same direction of rotation and being pivoted in such a way as to tend to assume by gravity one of said open or closed passage configurations, and the lower blades (23) being interconnected so as to rotate simultaneously in the same direction of rotation and being pivoted in such a way as to tend to assume by gravity the other of the said open or closed passage configurations,
wherein a drive (61, 63) is provided, which connects the upper blade array (21) to the lower blade array (23) in such a way that the two blade arrays (21, 23) are opposite the direction of rotation and the tendency of the upper blades (21) to assume by gravity one of said open or closed passage configurations is countered by the tendency of the lower blades (23) to assume by gravity the other of the said open or closed passage configurations, and
wherein the return element (81) is connected to at least one of said upper (21) and lower blade arrays (23) and is arranged in such a way as to apply on the blade array(s) (21, 23) a maximum moment of the return force in the closed passage configuration and a minimum moment of the return force in the open passage configuration.
A shutter according to claim 1, wherein each blade (21, 23) forms approximately a plane in a direction of extension orthogonal to the blade's (21, 23) rotation axis (x1, x2), wherein, in the respective direction of extension, each blade (21, 23) has a front portion (21a, 23a) and a rear portion (21p, 23p) positioned on opposite sides of the rotation axis (x1, x2) of the blade (21, 23), the front portion (21a, 23a) having a greater extension than the rear portion (21p, 23p).
A shutter according to claim 2, wherein the blades of the upper blade array (21) are interconnected by means of an upper rigid connecting rod (31), each blade of the upper blade array (21) being hinged to the upper connecting rod (31) at a hinging point (x3) positioned outside the plane formed by the blade (21), and wherein the blades of the lower blade array (23) are interconnected by means of a lower rigid connecting rod (33), each blade of the lower blade array (23) being hinged to the lower connecting rod (33) at a hinging point (x4) positioned outside the plane formed by the blade (23).
A shutter according to claim 3, wherein the drive comprises an upper geared element (61) and a lower geared element (63) in reciprocal engagement and having respective axes of rotation (x5, x6), wherein the upper and lower connecting rods (31, 33), in addition to the respective end blades of the upper blade array (21) and the lower blade array (23), have respective extensions (71, 73) hinged respectively to the upper geared element (61) and to the lower geared element (63), and wherein
a) the rotation axis (x1) of the end blade of the upper blade array (21), the hinging point (x3) of the end blade of the upper blade array (21) to the upper connecting rod (31), the hinging point (x7) of the extension (71) of the upper connecting rod (31) to the upper geared element (61), and the rotation axis (x5) of the upper geared element (61), and

b) the rotation axis (x2) of the end blade of the lower blade array (23), the hinging point of the end blade of the lower blade array (23) of the lower connecting rod (33), the hinging point (x8) of the extension (73) of the lower connecting rod (33) to the lower geared element (63), and the rotation axis (x6) of the lower geared element (63),
define the vertices, respectively, of an upper articulated parallelogram and a lower articulated parallelogram.
A shutter according to one of the preceding claims, wherein the return element (81) is connected to one of the blades of the upper blade array (21) or of the lower blade array (23), and is positioned in such a way as to define, with respect to the rotation axis (x1, x2) of said blade, a maximum arm (b) of the return force in the closed passage configuration and a minimum arm of the return force in the open passage configuration.
A shutter according to one of the preceding claims, wherein the return element is an elastic element connected on one side to the frame (11) and on the other side to the plurality of blades (21, 23).
A shutter according to one of the claims 1 to 5, wherein the return element is a weight connected to one of the blades of the upper blade array (21) or of the lower blade array (23), wherein the return element is positioned in such a way as to define a center of gravity wherein the position with respect to the rotation axis (x1, x2) of said blade determines a maximum arm (b) of the force of gravity in the closed passage configuration and a minimum arm of the force of gravity in the open passage configuration.