DAMPER DEVICE

Abstract: A damper device comprises a flow conveying casing (1) having a wall curved in cross section and two damper elements (2, 3) pivotably arranged in the casing. These damper elements are curved generally in correspondence to the wall of the casing and arranged to cooperate so that they in closed position in unison generally shut off flow through the casing. The damper elements are in their open positions located generally along the wall of the casing while delimiting between themselves an entirely open channel.

Description: Damper device FIELD OF INVENTION AND PRIOR ART This invention is related to a damper device comprising a fl conveying casing having a curved wall and two damper elemen pivotably arranged in the casing. The damper device is pr ferably intended for air flow regulation in ventilati arrangements. Damper devices of various kinds are previously known but suff from several problems. One of these problems resides in t noise generated by the turbulence of the air around dampers a shafts. Another problem relates to the regulation characte ristics of the dampers. A linear characteristic is aimed at i.e. the pivoting angle of the damper should preferably b proportional to the flow. Prior dampers, e.g. so calle throttle dampers and iris dampers, present a regulatio characteristic which considerably deviates from the linear one In recent time it has been established that also ventilatio ducts for the supply of air should be possible to be cleaned which previously only was considered necessary for channels fo spent air. The reason therefor is that after some time of us particles have been collected in the ducts and form multiplication environment for bacteria and fungi. If cleanin of the duct should be easy to carry out, hindering damper blades and through shafts should not occur in the ducts. The known damper designs also cause problems concerning mea¬ suring of the flow through the ducts provided with the dampers. These problems manifest themselves in either unfavourable measuring accuracy or relatively complicated embodiments. SUMMARY OF THE INVENTION The object of the present invention is to provide a damper device having such a structural design that the problems discussed hereinabove are eliminated or at least reduced. This object is according to the invention obtained by the features more specifically defined in the characterizing portions of the appendent claims. The advantages and structural features of the damper device according to the invention will appear more closely herein¬ after. BRIEF DESCRIPTION OF THE DRAWINGS With reference to the enclosed drawings a more specific description of embodiments of the invention cited as examples will follow hereinafter. In the drawings: fig 1 is a side view of the damper device in its open position, a portion of the casing being cut away; fig 2 is a view of the damper device as viewed from the left in fig 1? --, fig 3 is a view of the damper device as viewed from above fig 1, i.e. parallel to its pivot axis, a portion of the casi and the operating arrangement having been removed; fig 4 is a view similar to fig 3 but illustrating the device a closed position; fig 5 is an enlarged basic view illustrating one of the damp elements in its extreme positions; fig 6 is an enlarged view illustrating an operating arrangeme for the damper elements; fig 7 is a view of the operating arrangement as viewed from t right in fig 6; fig 8 is a view illustrating the damper elements in a plana flattened state; fig 9 is a diagram illustrating the relation flow q and degr β of opening of the damper; fig 10 is a view similar to fig 2 of an alternative embodimen fig 11 is a view similar to figs 3 and 4 of the alternati embodiment according to fig 10; fig 12 is a side view similar to fig 1 of another alternati comprising another damper element shape and another operati arrangement, the damper elements being in open position; fig 13 is a view of fig 12 from above, the casing being part cut away and some other parts removed for gaining clarity; fig 14 is a view similar to fig 13 but illustrating the damp elements in a closed position; fig 15 is a view similar to figs 3 and 4 of a third alternative for the damper device; and fig 16 is a view similar to fig 15 of a fourth alternative embodiment. DETAILED DESCRIPTION OF PREFERRED EMBODIMENT The embodiment according to figs 1-9 The damper device comprises a flow conveying casing 1 with a curved mantle wall and two damper elements 2, 3 pivotably arranged in the casing. These elements are curved generally in correspondence to the wall of the casing and adapted to coope¬ rate so that they in a closed position (fig 4) in unison generally shut off or at least reduce the flow through the casing. In their open positions (figs 1-3) the damper elements are located generally along the interior side of the casing wall while delimiting between themselves an entirely open channel extending in the longitudinal direction of the casing. The casing 1 is generally circular in cross section and each of the damper elements 2, 3 is generally semi-circularly curved. The opposite edges 4, 5 of the damper elements 2, 3 form in the planar, flattened state (fig 8) of the elements parabolic archs. In the area of the connection points of the parabolic archs, each of the damper elements comprises lugs 6 provided with holes. In the duct space delimited in unison by the damper elements 2, 3 in their open position (see fig 2) there is no shaft exten¬ ding transversely relative to the casing. Instead, the damper elements 2, 3 are at the bottom of the view according to figs 1 and 2 pivotably connected to the casing by means of a short stub axle 7 projecting through the holes in the lower lugs 6. The design at the top appears most clearly from figs 6 and The damper elements 2, 3 are pivotable by means of a ge transmission 8 comprising two gears 9, 10 connected to t respective damper elements 2, 3. These gears are in engageme with a further gear 11 secured against rotation relative to shaft 12, which serves as a pivot shaft for the damper devic The gears 9-11 are bevelled as illustrated and the pivot shaf 12 extends at an angle of about 90 relative to the axes of t gears 9, 10. The first gear 9 is secured against rotatio relative to a sleeve 13, which protrudes through the casing and is secured against rotation relative to the damper elemen 2. The second gear 10 is secured against rotation relative to shaft 14, which protrudes through a central hole in the gear 1 and extends through the sleeve 13 to a rigid connection to th second damper element 3 at its lower end. The shaft 14 run freely within the sleeve 13 and is preferably radially jour nalled by means of the latter. Within the casing 1 there may b provided a spacer and/or bearing ring 15 cooperating with th damper element 2 and/or the sleeve 13. On the casing 1 there is secured a holder 16 comprising bearing opening for the shaft 12. A spring 17 acts between th holder 16 and the gear 11 and/or an abutment on the shaft 1 and has the purpose to maintain the gear 11 in engagement wit gears 9, 10. Accordingly, the shaft 12 is displacably journal led in its longitudinal direction relative to holder 16. Th spring 17 may for instance be formed by a screw compressio spring arranged about shaft 12. The shaft 12 may be connected to an operating arm 18 fo operation of damper elements 2, 3. The shaft 12 is rotatable b means of this arm and this rotational movement is transferre from gear 11 to gears 9 and 10 in such a way that the dampe elements 2 and 3 will be pivoted uniformly but in differen directions. As is illustrated in fig 7, the holder 16 may b provided with a scale 19 serving to assist in adjusting the ar 18 so that the damper elements obtain the desired position. A certain adjustment established to be suitable may be defined by means of an indicator member 20, which may be secured in a desired position along the scale and which may operate as a stop for the movement of arm 18. The normal direction of air flow is indicated with arrows in the figures. The edge 4 of each of the damper elements located up-stream in the air flow direction forms in the spread out condition a parabolic arch, which is flatter than the parabolic arch formed by the edge 5 located downstream. Such a design gives rise to a nearly linear regulation characteristic, which will be discussed hereinafter. It appears in particular from fig 2 that the damper elements 2, 3 are curved in accurate correspondence to the internal surface of the casing 1 so that there is, in the open position of the damper elements, always an equally large distance between the outside of the damper elements and the inside of casing 1. The casing 1 may suitably comprise grooves 21 or other designs for receiving sealing rings intended to provide a tight connection relative to duct pieces connectable to the opposite ends of the casing. The edge 4 of each of the damper elements located upstream in the air flow direction lies, in the open position (see fig 5) of the damper elements, generally in a plane forming an angle a with a plane P extending transversely to the casing which is smaller than 30 but larger than 0 . More specifically, said upstream edge 4 lies upstream relative to the plane P, which is drawn out in fig 5 and extends transversely relative to the casing 1 while passing through the pivot axis of the damper elements. It is suitable that the angle a is smaller than 28 but larger than 2°. It is preferred that the angle a is between 17.5 an 27.5 , 20-25 being particularly preferred. The angle a is the embodiment about 22.5 . It appears from fig 5 that the closed position of the damp element is indicated with dashed lines. Furthermore, it appea by the dashed double arrow how the portion of the edge 4 whi is mostly spaced from the pivot axis of the damper element moving when operating the damper element from its open to i closed position. It also appears that said portion of t damper element is located at generally the same distance fr the inner wall of the casing 1 in these open and closed pos tions. In order to obtain this, the pivot angle c of the damp element between the open and closed position is approximate 2 x a. The angle c is in the embodiment smaller than 60 Preferably, the angle c is between 30 and 60 . The most pr ferred is between 40 and 50 , the angle c being in the emb diment about 45 . The upstream and downstream edges 4, 5 of each of the damp elements are generally located in planes, which between the selves form an angle which is larger than 60 preferably larg than 65°. In the embodiment this angle (a + b) is about 67.5 . With other words, the edge 5 of the damper elements which located downstream in the air flow direction, will in the op position of the damper elements generally lie in a plane, whi forms an angle with a plane P extending transversely to t longitudinal direction of the casing which is larger than 3 and smaller than 60°. It is preferred that the angle b between 40 and 50°. In the embodiment the angle is about 45°. The edges 5, which in the open position of the damper a located downstream, abut against each other in the clos position (fig 4) of the damper elements in a plane which parallel to the axis of the casing and orientated in the cent of the casing. Between the casing 1 and at least one of the damper elements there is provided at least one sealing member 22 preventing or reducing air flow externally of the damper element. In the embodiment this sealing member 22 is arranged on the damper elements 2, 3 to accompany them in their movements. The sealing members 22 have preferably the character of a strip like slipping sealing, which by slippingly abutting against the inside of the casing seals the space between this inside and the respective damper element in the opened and closed posi¬ tions of the damper element as well as in its positions there¬ between. Each of the damper elements 2, 3 comprises preferably a sealing member 22 along its entire edge 4 located upstream. The sealing member 22 is of an elastic design, e.g. of rubber or plastic, and secured to the respective damper element in an arbitrary manner, e.g. glueing, screwing, riveting etc. The casing 1 is provided with at least two measuring openings 23, 24, a first 23 of which is adapted to communicate with the interior of casing 1 up-stream of the damper elements 2, 3 whereas the second 24 is adapted to communicate with the interior of the casing downstream of the damper elements. The arrangement of these measuring openings 23, 24 is based upon the notion that for determining flow amounts, flow measuring means of the pressure drop type may be used, wherein the static pressure drop across a restriction device gives a differential pressure which is proportional to an amount of flow. Accor¬ dingly, pressure measuring members 25 and 26 may be connecte as indicated diagrammatically in fig 3. Knowing the amount of restriction between the measuring openings 23 and 24 and th pressure differential obtained with the assistance of the pressure measuring members 25, 26, information is accordingl obtained, on basis of which the flow through the casing 1 ma be determined. According to the invention the damper elements 2, 3 will them selves form said restriction device, i.e. in dependence upo the position of the damper elements a smaller or larg restriction of the flow through the casing is obtained. means of the previously described scale 19 (fig 7) or oth similar means, information about the actual restriction accordingly obtained. The device is of course preferably such that the sealing memb 22, which is coordinated to at least one of the damper elemen and which is located in the area of the measuring openings 23 24, acts sealingly relative to the casing 1 in the area betwe the measuring openings. Accordingly, there will also in t open position (fig 3) of the damper elements occur a restric tion functioning between the measuring openings 23, 24 due the engagement of the sealing member 22 against the casing i the area between the measuring openings. This restriction i sufficient to provide, by means of the measuring openings 23 24, information about the flow in the casing although t damper elements are parallel to the wall of the casing. The relation flow q/damper opening degree β for the dampe device according to figs 1-8 is illustrated with the full lin 27 in fig 9. The straight inclined line indicates an idea proportional regulation characteristic. As can be seen, th curve illustrated with the line 27 is relatively close to th ideal proportionality. The regulation characteristics for tw dampers commonly occurring in ventilation arrangements, namel the throttle damper and the iris damper respectively, ar indicated with dashed and dash dotted curves. As can be seen the known dampers have a considerably worse regulation charac teristic. The embodiment according to figs 10 and 11. This embodiment differs from the one previously describe generally only as far as the operating arrangement is concer ned. In this case, the damper elements 2 and 3 are each rigidl secured relative to two respective shafts 28, 29 and 30, 31 respectively. These shafts are rotatably received in the casing 1 or in bearings arranged thereon. Each of the shaft pins 28-31 comprises a gear rigidly secured thereto, the gears being in engagement with each other in pairs. One of the shafts, e.g. the one denoted 28, comprises an extensioning forming an operating member 32, which may be rotatably supported relative to a holder 33 attached to the casing 1. By rotating the shaft 28, the damper elements 2, 3 will be pivoted in opposite directions as in the preceding case. The embodiment according to figs 12-14. This embodiment differs from the preceding one, in that the damper elements 2, 3 here have edges 4, which in the open positions of the damper elements are located up-stream and which in the planar, spread out condition of the damper ele¬ ments do not form any parabola but instead a straight line. However, the edges 5 of the damper elements 2, 3 located downstream in the open position form in the spread out condi¬ tion of the damper elements parabolic archs. The edges 4 are in the open position of the damper elements generally located in a plane extending transversely to the longitudinal axis of the casing 1. The operating arrangement 34 disclosed herein is for the rest of another kind than the one previously described. More speci¬ fically, the operating arrangement 34 comprises a rotatable shaft 35, which is rotatably journalled at the casing 1 and/or a holder 36 arranged thereon. An operating member 37 rigidly mounted to the shaft 35 comprises two guides 38, 39, along which follower members 40, 41 are movable on rotation of the operating member 37 by means of the shaft 35. The two follower members 40, 41 are connected to a respective arm 42 and 43, which in its turn is secured against rotation relative to respective shaft 44 and 45. Each of these two shafts 44, 45 connected to one of the damper elements 2, 3. The operating or transmission member 37 has in the embodime the character of a plate and its guides 38, 39 are formed arcuate slots therein, said slots having first ends relative close to the center of the plate and second ends relative close to the periphery of the plate. The follower members 4 41 are formed by pins or projections received in these respe tive slots 38, 39. One 45 of the shafts 44, 45 has the chara ter of a sleeve secured against rotation relative to the damp element 2 whereas the other shaft 44 projects through a preferably is radially journalled in the shaft sleeve 45 a secured against rotation relative to the other damper eleme 3. When it is desired to adjust the position of the damper el ments, the shaft 35 is rotated, which gives rise to rotation the plate 37. The pins 40, 41 will thereby be moved in t slots 38, 39 and this gives rise to pivoting of the arms 42, and rotation of the shafts 44, 45 secured against rotati relative to said arms so that the damper elements are pivot with the same angular velocity but in opposite directions. The shaft sleeve 45 is preferably supported relative to t casing 1 or the holder 36 by means of suitable bearings. The embodiment according to fig 15. The damper elements in this embodiment have generally the sa design as in figs 1-9. The difference consists in the presen of a different type of sealing members 46 between the inside the casing 1 and the damper elements 2, 3. More specificall these sealing members are designed as a ring shaped coll comprising a surface turned inwardly towards the damper el ments, said surface being designed in correspondence to t movement described by points on the edges 4 located upstream on the damper elements on movement of the damper elements from open to closed position and vice versa. With other words, the edges of the damper elements located upstream will always be very close to or in slipping engagement against this collar 46 along the entire circumference of the configuration formed by the damper elements in common. Also here the edges 4 of the damper elements 2, 3 located upstream could possibly comprise some kind of elastical sealings for slipping engagement against the collar 46 then being generally rigid. Alternatively, the collar 46 could be provided with some kind of elastical coating on its side turned inwardly towards the damper elements, said elastical coating being adapted to be in contact with the edges 4 of the damper elements located upstream. The shape of the annular collar 46 will of course vary along the circumference in correspondence to the path of movement of the edges 4 of the damper elements located upstream. As previously, measuring openings 23, 24 are provided and these are here located on either sides of the collar 46, which is tightly connected to the inside of the casing 1. The embodiment according to fig 16. This embodiment corresponds to the one illustrated in fig 15 with the exception that each of the damper elements 2, 3 here are so designed that they in a planar, spread out condition have opposite parabolic archs, which are generally identical. With other words, the edges, 4, 5 of the damper elements located upstream and downstream respectively will form angles a and b with the transverse plane P passing through the pivot axis of the damper elements which are equally large. Each of the angles a and b is in the embodiment about 30 , from whic it follows that the angle of pivoting of the damper element between open and closed position is about 60 . POSSIBLE MODIFICATIONS OF THE INVENTION The invention is of course not only limited to the embodimen illustrated. For instance, the sealing members 22 and 46 may designed in many other ways than those described. One or mo elastical sealing members could for example be attached on t inside of the casing 1 for cooperation with the damper el ments. Furthermore, it should be mentioned that the inventi by no means is limited to such designs, where the casing 1 ha in cross section, circular, oval or otherwise round shape Thus, the casing could be cross-sectionally rectangular otherwise polygonal with damper elements curved in correspo dence thereto and pivotably supported about a common axis alternatively two axes disposed relatively close to each oth in the central area of the casing. Thus, in the case with cross-sectionally rectangular casing, each of the damp elements would accordingly have a generally U-shaped curv profile. Also other modifications are possible within the sco of the invention.

Claims: Claims 1. A damper device, in particular for air flow regulation in ventilation arrangements, comprising a flow conveying casing (1) and two damper elements (2, 3) pivotably arranged in the casing, c h a r a c t e r i z e d in that the damper elements are designed subtantially in correspondence to the wall of the casing and adapted to cooperate so that they in closed position in unison substantially close or at least reduce the flow through the casing (1) and that the damper elements (2, 3) in their open positions are located substantially along the casing wall delimiting between themselves an open channel. 2. A device according to claim 1, c h a r a c t e r i z e d in that the casing (1) is substantially circular in cross section and that each of the damper elements is substantially semi¬ circularly curved. 3. A device according to any of claims 1 and 2, c h a r a c t e r i z e d in that each of the damper elements (2, 3) in its planar, spread out condition has its opposite edges (4, 5) forming parabolic archs. 4. A device according to claim 3, c h a r a c t e r i z e d in that the edge (4), which is located up-stream in the air flow direction, of each of the damper elements in the spread out condition forms a parabolic arch which is flatter than the parabolic arch formed by the edge (5) located downstream. 5. A device according to any preceding claim, c h a r a c t e r i z e d in that the edge ( ) , which is located upstream in the air flow direction, of each of the damper elements (2, 3) in their open position is located substantially in a plane forming an angle (a) which is smaller than 30° but larger than 0°. 6. A device according to any preceding claim, c h a r a c t e r i z e d in that the edges (4, 5) , which a located upstream and downstream, of each of the damper elemen (2, 3) substantially are located in planes, which betwe themselves form an angle (a + b) which is larger than 60°. 7. A device according to any preceding claim, c h a r a c t e r i z e d in that a sealing or shieldi member (22, 46) acts between the casing (1) and at least one the damper elements (2, 3) to prevent or reduce air fl externally of the damper element. 8. A device according to any preceding claim, c h a r a c t e r i z e d in that the casing is provided wi at least two measuring openings (23, 24), a first (23) of whi is arranged to communicate with the interior of the casi upstream of the damper elements whereas the second (24) arranged to communicate with the interior of the casing dow stream of the damper elements. 9. A device according to any predecing claim, c h a r a c t e r i z e d in that the damper elements (2, 3 are pivotal by means of a gear transmission comprising at leas two gears (9, 10; 28, 30 and 29, 31 respectively) connected t the respective damper element, and that these gears are i mutual engagement or in engagement with at least one furthe gear (11). 10. A device according to any of claims 1-8, c h a r a c t e r i z e d in that an arrangement (34) fo operating the damper elements comprises a rotatable operatin member (37), which comprises two guides (38, 39), along whic follower members (40, 41) are movable on rotation of th operating member, that the two follower members are connecte to a respective arm (42, 43), which in its turn is secure against rotation relative to a respective shaft (44, 45), an these two shafts are connected to a respective one of th damper elements.

Inventors: BERGDAHL KNUT, BERGDAHL, KNUT
Applicants: BERGDAHL KNUT, BERGDAHL, KNUT
Application year: 1989
Main classification: F24F13
IPC codes: F16K1, F24F13