Automatic, temperature responsive damper assembly

Abstract

A pivoted, split butterfly vane, damper assembly provided with an automatic temperature responsive actuating means for opening and closing the damper vanes in response to temperature changes useable primarily with turbine ventilators in buildings is disclosed. A temperature sensitive bellows element positioned beneath the damper vanes actuates a pivoted lever to cause opening and closing of the damper vanes over a predetermined range of temperatures. The free end of the pivoted lever terminates in an upwardly extending arm, the arm being provided with vane engaging fingers having sloped camming surfaces with, in the preferred embodiment, the fingers having cosine curve shaped camming surfaces for controlling the rate of opening of the damper vanes over the selected temperature range and for providing protection for the damper assembly should the temperature range be exceeded.

Description

FIELD OF THE INVENTION

The present invention is directed generally to a ventilation conduit damper assembly for use primarily with a turbine ventilator. More specifically, the present invention is directed to such a ventilation damper assembly provided with automatic, temperature responsive, actuating means whereby the amount of movement of the damper vanes, over a preselected temperature range, is controlled.

A pivoted, split butterfly vane, damper is provided within a ventilating conduit with the damper vanes being disposed horizontally in their closed position. A temperature sensitive bellows assembly is positioned beneath the damper vanes and upon expansion or contraction of the bellows due to temperature change, a lever, pivoted at one end, is caused to move. A bifurcated or generally Y shaped arm is carried at the free end of the lever and is provided with fingers having camming surfaces which engage the damper vanes, thus causing the damper to open or close with a change in temperature. In the preferred embodiment, the fingers' camming surfaces are of a cosine curve shape and cause rapid initial opening of the damper in response to a small temperature change, and also provide that, upon the opening of the damper to its full open position, additional movement of the arm may be had without damage to the assembly. Since the bellows and the camming surface shape may be changed, a damper is provided which allows for operation over various preselected ranges of temperatures.

DESCRIPTION OF THE PRIOR ART

Dampers for use in conduits are generally known and are utilized, for example, in stoves, fireplaces, furnaces and the like. Typically these assemblies consist of a movable vane or vanes which are positionable to control the amount of air flow through the conduit within which the damper is placed. In many of these installations, the damper is either open or closed with this position selection being done manually. Dampers are additionally often used in conjunction with ventilating systems in homes and similar buildings when it is desired to provide ventilation for a portion of the building.

In some areas of the country where rather hot weather is experienced during at least a portion of the year, it is often desirable to provide a means for ventilating a portion of a building, typically an attic or the like. This ventilation is often provided by using a turbine air ventilator of a known type in which wind causes the turbine to turn and causes air to be, in effect, pumped out of the area provided with the ventilating conduit.

While turbine ventilation systems are quite effective in promoting air flow, they have, in the past, suffered from the lack of an effective automatic means to control the amount of air removed. Obviously the air flow should be at a maximum during hot weather when the temperature in the area to be ventilated is high, but just as obviously the ventilation should be much less when the temperature in the area to be ventilated is lower. Constant ventilation, even in periods of cool temperatures, causes an unnecessary loss of heat and a consequent increase in heating costs. While this problem of present ventilation systems is recognized, the attempted solutions have been less than satisfactory.

Although some type of adjustable damper is desirable, in a number of instances no such adjustable flow control means has been provided. When a damper is provided, it often is of the type where the position of the damper means is adjustable by, for example, a manual movement of the vanes. Since the space to be ventilated, typically an attic, is often inaccessible, the homeowner is not apt to manually adjust the damper as often as he should to provide for efficient ventilation in hot periods or for retention of heated air during cold periods. Other adjusting means such as chain pulls, elongated adjusting rods and the like have been provided, but again either these are difficult to use or else the homeowner simply forgets to change the damper position. Hence the damper is open when it should be closed or closed when it should be open so that it is ineffectual in performing its intended function. With the increasing cost of power used for heating and air-conditioning, it becomes readily apparent why an automatic damper system should be utilized in conjunction with ventilation systems.

Unfortunately, the few prior automatic adjustable dampers which have been contemplated or manufactured have been unable to perform their desired function in an effective, economical manner. These automatic controls, when available, have suffered from high cost, undependability, a failure to provide simple means to vary the range of temperature over which they operate the damper, and a propensity to become damaged or disabled in cases of temperature fluctations in excess of those designed for. This lack of dependability, high cost and incidence of damage to the device by abnormal temperature fluctations has combined to limit the use and acceptance of automatic damper control systems in home ventilating systems and the like.

SUMMARY OF THE INVENTION

It is, accordingly, an object of the present invention to provide an automatic damper assembly for use in a home ventilating system.

A further object of the present invention is to provide an automatic damper which requires no attention from the homeowner.

Yet another object is to provide an automatic damper assembly which is simple in operation and low in cost.

A still further object of the present invention is to provide an automatic damper assembly for use with a turbine ventilator wherein the operating temperature range may be preselected and further wherein temperatures in excess of those preselected will not adversely affect the assembly.

The damper assembly of the present invention is comprised generally of a split butterfly vane damper positioned in an air flow conduit. Temperature sensitive bellows are positioned below the damper vanes and expand or contract in accordance with temperature changes. A lever is positioned between the bellows and vanes and is pivoted at one of its ends. The free end of the lever carries an upwardly extending bifurcated or generally Y shaped arm provided with vane contacting fingers having sloped camming surfaces. In the preferred embodiment, these fingers have generally cosine curve shaped camming surfaces which engage the damper's vanes and cause movement thereof in response to expansion or contraction of the temperature-sensitive bellows.

As previously discussed, it is desirable to provide ventilation for enclosed spaces such as buildings or attics during at least a portion of the year. The present damper, where used in conjunction with a conventional turbine ventilator, provides such ventilation and additionally, and more importantly, provides an automatic control such that air flow is controllable in response to ambient air temperatures, thereby insuring that adequate ventilation is provided when necessary, yet preventing the unwanted flow of air when the ambient temperature is below a preset level. Thus, heating costs are reduced since the system is closed during cold weather.

The damper of the present invention is contained within the air conduit and hence is mountable in an existing line with no additional exterior space required. This feature is of particular benefit in areas where there is insufficient space for external controls or linkages.

Due to the completely automatic nature of the present damper assembly, no attention is required on the part of the homeowner. The damper operates automatically over the preselected temperature range, opening and closing in response to temperature changes, thus assuring even the most forgetful homeowner that proper ventilation is taking place. The fully automatic nature of the present damper assembly also eliminates the need for mechanical adjusting means such as the chains, levers and rods discussed previously. This allows the apparatus to be positioned at the most advantageous portion of the flow conduit with no necessity for providing access for any mechanical or manual adjusting means.

The temperature-sensitive bellows which cause the movement of the lever and hence the damper are well known and can be selected to operate over any desired temperature range. A bellows with the desired temperature sensitivity is chosen and installed in the assembly to cause the damper to open and close over the desired range. An abnormally low temperature will not adversely affect the damper assembly since once the temperature falls below the range of the bellows, further temperature decreases will have no effect. Similarly, an abnormally high temperature will not harm the damper mechanism since the camming surfaces on the damper vane contacting fingers are so shaped as to slide over the face of the vanes once the vanes are in their fully opened position. Hence the assembly, unlike previously attempted automatic dampers, is efficient, reliable, unharmed by temperature fluctuations in excess of those designed for, completely automatic, capable of insertion into existing conduits, and low in cost.

BRIEF DESCRIPTION OF THE DRAWINGS

While the novel features of the present invention are set forth with particularity in the appended claims, the invention will be understood more fully and completely from the detailed description of a preferred embodiment as set forth hereinafter, and as seen in the accompanying drawings in which:

FIG. 1 is a schematic elevation view of a portion of a building with the ventilation system and automatic damper assembly in place;

FIG. 2 is a side elevation view of the automatic damper assembly of the present invention with a portion of the conduit removed;

FIG. 3 is an end elevation view of the apparatus, partly in cross-section, taken along line 3--3 of FIG. 2; and,

FIG. 4 is an elevation view of a preferred shape of the vane engaging fingers.

DESCRIPTION OF A PREFERRED EMBODIMENT

Referring now to FIG. 1, there is shown generally at 10 a ventilation system utilizing the automatic damper assembly of the present invention. As may be seen, system 10 is comprised of an air conducting conduit 12 passing through the roof 14 of a building 16. Conduit 12, which is provided with a suitable sealing means generally indicated at 18 at its point of passage through roof 14, carries, at its exterior portion, a turbine ventilator 20 of conventional construction. Since these ventilators are well known it will be sufficient to indicate that ventilator 20 is provided with a number of vertical slats 22 which cause the assembly to rotate under the influence of wind, and to act as an air pump. Conduit 12 carries, at an exterior portion thereof, an automatic, temperature actuated, damper assembly 24 in accordance with the present invention. Although damper assembly 24 is shown as being placed in conduit 12 exteriorly of roof 14, it may alternatively be placed interiosly thereof if desired. While damper assembly 24 will hereinafter be described as being positioned in a circular air conduit 12, it will be understood that other similar conduit shapes such as square or rectangular may also be utilized with appropriate modifications being made to damper assembly 24.

As may be seen more completely in FIG. 2, damper assembly 24 is carried within a section of circular air conduit 12, such conduit being preferably of conventional galvanized sheet metal, with damper assembly 24 being comprised generally of a movable vane portion 26, and a temperature actuated vane opening and closing assembly 28.

Movable vane assembly 26, as seen in FIGS. 2 and 3, consists of a pair of movable vanes 30 and 32 with each such vane being in the shape of a semi-circular disc and being formed preferably of aluminum sheet metal. Each vane 30 and 32 is secured, along a diametral portion 34 and 36 respectively thereof, to a hinge rod 38 and 40 respectively. Each of these hinge rods 38, 40 pass generally through the center of conduit 12 and are free to rotate. Each hinge rod 38, 40 is provided, at its segment external to conduit 12, with a vane position indicator portion 42, such indicator being a flag or painted portion (not shown) or the like and serving to indicate the relative position of the vane carried by each such rod. Vanes 30 and 32 may be securely affixed to hinge rods 38 and 40 by any acceptable means such as screws (not shown) so long as vanes 30, 32 move with rods 38, 40. While, in the preferred embodiment, vanes 30 and 32 are shown as being separate and each carried by separate hinge rods 38 and 40 respectively, it will be understood that various other hinge means such as piano hinges and the like may be utilized and that both vanes may be hinged together so long as each vane is capable of pivotal movement about its diametral portion.

A vane stop piece 44 is affixed to the interior of conduit 12 by, for example, a screw 46. Vane stop 44 is positioned above hinge rods 38 and 40 and between vanes 30 and 32, as seen in FIG. 3, to insure that the vanes do not open past vertical, thereby preventing the vanes from becoming stuck in their full open position. A means such as inwardly extending screws 48 and 50, as seen in FIG. 3, is also provided to insure that vanes 30 and 32 do not travel past a horizontal position when in their closed mode. Again, it will be understood that alternative vane stops may be utilized with, for example, piece 44 being replaced by spaced screws or the like and with screws 48 and 50 being replaced by inwardly extending lips or the like.

Automatic opening and closing of vanes 30 and 32 is, as previously indicated, afforded by temperature actuated vane opening and closing assembly 28. As illustrated in FIGS. 2 and 3, vane opening and closing assembly 28 is carried within conduit 12 and is disposed generally beneath vanes 30 and 32. A generally U-shaped, upwardly opening bracket 52 is positioned beneath hinge rods 38 and 40 and parallel thereto. This bracket, which is affixed, at its ends, to conduit 12 by any suitable means such as, for example, screws 54 and 56, carries thereon a movable vane actuating lever 58 and a temperature sensitive drive assembly 60, as will now be more fully discussed.

Vane actuating lever 58 which, as may be seen in FIGS. 2 and 3, is of generally channel shape, is pivotally connected at a first end 62 thereof to bracket 52, and has a free end 63. This pivotal connection may be of any conventional type and is shown in the preferred embodiment as being a conventional cotter pin 64 which passes through bracket 52 and lever 58. It will be noted that, as shown in FIG. 3, lever 58 is of slightly less width than is bracket 52 so that lever 58 will be capable of being disposed within bracket 52 when lever 58 is in its rest position.

Again as shown in FIGS. 2 and 3, an adjustable lever actuating leg 66 is carried by lever 58 adjacent the lever's pivoted end 62 and above the center of bellows assembly 60. In the preferred embodiment, leg 66 is shown as being comprised of a screw 68 provided with a rounded heat 70 and two adjusting nuts 72 and 74 carried above and below the web portion of lever 58. Head 70 rides on an upper surface 76 of drive assembly 60, with screw 68 passing through a suitable aperture (not shown) in bracket 52 so that expansion or contraction of drive assembly 60 will cause movement of leg 66 and hence movement of lever 58. Since screw 66 is provided with adjusting nuts 72 and 74, the position of screw head 70 may be varied thereby varying the point at which leg 66 will be caused to move by expansion of drive assembly 60.

Drive assembly 60 is, as seen in FIGS. 2 and 3, carried by a supporting member 78 affixed to the underside of bracket 52 by screws 80, 82 or by any other conventional means. Assembly 60 is comprised of any conventional temperature sensitive drive means with, in the preferred embodiment, two bellows elements 84 and 86 being provided. Each of these bellows elements 84 and 86 is generally disc-shaped and both are so constructed that a change in temperature will cause them to expand or contract. Lower bellows elements 86 is provided with a downwardly extending bolt 88 which passes through a hole (not shown) in supporting member 78 so that bellows assembly 60 may be affixed thereto by means of a nut 90. Upper face 76 of upper bellows element 84 is carried adjacent the aperture (not shown) in bracket 52 and is contacted by the screw head portion 70 of leg 66. It will be understood that any of a number of temperature sensitive means may be utilized in assembly 60 so long as the expansion and contraction thereof is predictable over a given temperature range.

A vane engaging arm 92 is carried at the free end 63 of lever 58, as may be seen in FIG. 2. Arm 92 is secured to lever 58 by any conventional means such as screws 94. As shown more clearly in FIGS. 3 and 4, arm 92 is comprised of two upwardly extending, spaced fingers 96 and 98 carried by a flat base plate 100. Fingers 96 and 98 have generally parallel inner edges 110 and 112 which are provided, at their upper inner edges, with sloped camming surfaces 102 and 104 respectively. These camming surfaces are so shaped that the space between fingers 96 and 98 increases with an increase in distance from flat base plate 100. Camming surfaces 102 and 104 terminate at points 106 and 108, respectively, spaced from the base plate 100 so that a constant space between edge portions 110 and 112 of the two fingers 96 and 98 is maintained over a portion of the length of the fingers adjacent flat base plate 100. This constant space is sufficient, as illustrated in FIGS. 3 and 4, to allow the passage of the diametral portions 34 and 36 of vanes 30 and 32 therebetween when the vanes approach a vertical position, as limited by stop 44. This insures that, even if lever 58 and hence fingers 96 and 98 move upwardly to a greater extent than planned due to abnormal temperatures, vanes 30 and 32 will pass between the fingers and will not be damaged. Should lever 58 and hence arm 92 move upwardly to an extent in excess of that necessary to fully open vanes 30 and 32, a flat spring 113, secured to the free end 63 of lever 58 and extending outwardly therefrom as may be seen in FIG. 2, will engage the diametral portions 34 and 36 of the vanes and will tend to force lever 58 downward.

Camming surfaces 102 and 104 are shown, in FIG. 3, as being of a constant slope, while in FIG. 4 they are shown at 114 and 116 as having a generally cosine curve shape. The constantly sloped surfaces of FIG. 3 provide essentially two points of contact, one at the ends of the fingers and one at points 106 and 108 for each of the vanes, the contact point shifting as the bellows moves through the intended temperature range. The cosine curved camming surfaces of FIG. 4 provide a continually changing point of contact between each camming surface and its corresponding vane. The shape of the cam surface provides a rapid initial opening with a subsequent reduction in vane opening rate due to the decreasing rate of change of slope of the camming surface. Additionally, since the amount of force required to raise the vanes decreases as they are raised, the cosine curve shape of the cam surface provides that its point of contact is further from the vane's pivot point initially, and moves inwardly during vane opening, thereby providing a generally constant vane opening force which makes maximum use of the bellows movement and allows the use of a smaller assembly. While either camming surface may be utilized, depending on the type of vane actuation desired, the cosine curved shape of FIG. 4 is also preferred since it provides substantially point contact between the camming surfaces 102 and 104 and the vanes 30 and 32 with a consequent reduction in friction in addition to the constant opening force.

In operation, a bellows assembly 60, having predetermined expansion characteristics over the anticipated temperature range to be encountered, is selected and installed in the supporting member 78. The depth of member 78 is such that it limits the amount that bellows assembly 60 may expand as top surface 76 of assembly 60 will be limited in its upward movement by contact with the underside of bracket 52. This insures that assembly 60 will not be harmed by over-expansion due to excessively high temperatures encountered, for example, in shipping. The section of conduit 12 which carries the automatic damper assembly 24 is positioned in a desired location in the ventilation system with conduit section 12 being provided with corrugations 118 to facilitate such insertion. The damper assembly 24 is so positioned that vanes 30, 32 are substantially horizontal when in their closed position. Leg 66 is adjusted to allow the vanes to close completely at the low end of the temperature range. As the ambient air temperature starts to rise through the preselected range, bellows assembly 60 expands, thereby forcing leg 66 upward, as shown in FIG. 2. Upward movement of leg 66 causes lever 58 to pivot about pivot point 64 and to raise its free end 63, thereby causing camming surfaces 102 and 104, carried by fingers 96 and 98, to engage vanes 30 and 32 forcing them to pivot open on hinge rods 38 and 40. As the temperature increases, the vanes continue to open until they are limited by engagement with stop 44. Further upward movement of lever 58 caused by temperatures in excess of the predetermined range will not adversely affect vanes 30 and 32 due to the uniform space maintained between the fingers.

As the ambient temperature decreases, bellows assembly 60 contracts thus causing lever 58 to lower and hence lowering vanes 30 and 32. Any tendancy of the vanes to stick in the open position is prevented by stop 44, flat spring 113, and may also, as a practical matter, be counteracted by the vibration caused in conduit 12 by the action of the turbine 20. The vanes continue to lower to their horizontal closed position where they may be held by screw stops 48 and 50, effectively preventing air flow through the conduit. Alternatively, screws 48 and 50 may be eliminated and the spacing between the vanes and lever 58 adjusted so that vanes 30 and 32 are horizontally supported by arm 92 when lever 58 is in its lowered position. A further decrease in the ambient temperature below the preselected range has no adverse effect on the damper assembly since it merely causes the bellows to contract further.

While a preferred embodiment of a fully automatic temperature responsive damper assembly that is low cost, dependable, easily installed and not affected by temperature fluctuations in excess of those anticipated has been hereinabove fully described, it will be evident to one of ordinary skill in the art that a number of variations in, for example, the shape of the conduit, and hence the shape of the vanes, the positioning of the assembly in the conduit -- i.e. either interiorly or exteriorly of the building roof, the materials used, the various fastening means utilized such as, for example, self tapping screws or pop rivets, and the specific bellows structure may be made without department from the spirit and scope of the invention and that therefore the invention is to be limited only the following claims.

Claims

I claim:

1. An automatic temperature responsive damper assembly for use within a ventilating conduit, said assembly comprising:

at least two movable vanes carried within said conduit, each of said vanes being movable between a generally horizontal closed position and a generally vertical open position in response to temperature changes in said ventilating conduit;

a temperature responsive drive assembly mounted on a bracket within said conduit beneath said vanes, said drive assembly being movable in response to temperature changes in said ventilating conduit;

a lever positioned in said conduit and located between said drive assembly and said vanes, said lever being pivotably connected at a first end to said bracket, and being provided at a second end with at least one vane engagable finger;

means to communicate said movement of said drive assembly to said lever; and,

a camming surface for each of said movable vanes on said vane engagable finger, each of said camming surfaces slidably contacting a corresponding one of said vanes to move said vanes between said open and closed positions in response to said movement of said drive assembly.

2. The apparatus of claim 1 wherein said vanes are movable about a substantially common axis, said axis lying generally in the center of said conduit.

3. The apparatus of claim 2 wherein said drive assembly is an expansible and contractable bellows assembly, said bellows assembly expanding and contracting in response to said temperature changes in said conduit.

4. The apparatus of claim 3 wherein said means to communicate said movement of said bellows assembly to said lever comprises a leg adjustably secured to said lever adjacent said lever's first end and further wherein said leg engages said bellows assembly whereby movement of said bellows causes movement of said lever.

5. The apparatus of claim 4 wherein said camming surfaces are in the shape of a cosine curve.

6. The apparatus of claim 5 further wherein each said vane is secured to a separate hinge rod, each of said rods passing through said conduit and having an indicator portion exterior of said conduit whereby the position of said vanes in said conduit is indicated by the position of said indicator means portions of said hinge rods.