Patent Publication Number: US-9835330-B2

Title: Linear slide damper system

Description:
PRIORITY CLAIM 
     This invention claims the benefit of priority of U.S. Provisional Application Ser. No. 61/829,036, entitled “Linear Slide Damper System,” filed May 30, 2013, the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     The present embodiments relate generally to a damper system, and more specifically, to a linear slide damper system. 
     Dampers have been used for many years to reduce heat loss during the off cycle period of gas-fired equipment. Vent dampers are typically mounted above the draft hood or draft diverter on gas-fired equipment such as furnaces and boilers and flue dampers are mounted between the equipment flue outlet and the draft hood on gas-fired commercial water heating equipment. 
     A newer use of the flue dampers are for residential style water heating equipment. Unlike the applications on commercial water heaters, the size of the draft hood is much smaller on the residential style heaters, and therefore the damper does not mount underneath the draft hood as they typically do on commercial heaters. Because of the size of the draft hood, the draft hood may need to be mounted directly onto the damper assembly. This mounting method raises the hood from the top of the water heater, thereby affecting the vent pipe mounting height and shipping carton sizes, which are both undesirable features to the water heater manufacturers. 
     Current damper product designs use a rotating shaft attached to the damper blade and rotate the damper through a 360 degree rotation open and closed, or it operates the damper through a 90 degree rotation open and closed with a spring return method. The circular shape of the rotating damper method increases the height of mounting the draft hood and requires a precise positioning of the damper when the damper blade stops in the open position. If the open position of the damper blade varies off of the true vertical open position, it causes an increased restriction to the flue gas flow. This venting path restriction can cause poor combustion and increased potential of flue gas spillage from the draft hood. 
     SUMMARY 
     A damper system comprises a damper blade having open and closed states. The damper blade is movable in a linear direction only between the open and closed states. The damper blade may comprise a rectangular shape. The damper blade may fully overlap with a flue passage in the closed state, and the damper blade may lack any overlap with the flue passage in the open state. 
     A drive member is coupled to the damper blade, and rotation of the drive member in a circumferential direction imparts linear motion to the damper blade. In one embodiment, the damper blade comprises first and second ends, a solid segment disposed at the second end, and a slot disposed at the first end. The drive member comprises at least one pin disposed for movement within the slot of the damper blade. In one embodiment, a circumferential position of the drive member may vary by at least 5 degrees while the damper blade remains in a fully open state. 
     In one embodiment, a portion of the damper blade directly contacts a switch activation arm in the open state, wherein the switch activation arm confirms the open state of the damper blade. A first end of the damper blade may contact a tapered segment of the switch activation arm when the damper blade is in the open state. 
     Advantageously, the linear slide damper assembly may comprise a reduced height when disposed between a water heater and a draft hood. Further, the damper blade may be entirely removed from the air stream of the flue passage when in the open state. Still further, the drive system can allow at least a 5 degree variation, and up to a 20 degree variation or more, in the positioning of the drive member while still maintaining a completely open state of the damper blade. 
     Other systems, methods, features and advantages of the invention will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be within the scope of the invention, and be encompassed by the following claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like referenced numerals designate corresponding parts throughout the different views. 
         FIG. 1  is a schematic perspective view of a first embodiment of a system comprising a linear slide damper, as shown coupled to a portion of a water heater. 
         FIG. 2  is a schematic perspective view of the linear slide damper of  FIG. 1  with the water heater and hood of  FIG. 1  removed for illustrative purposes. 
         FIG. 3  is a side view of the system of  FIG. 1 . 
         FIG. 4  is a schematic perspective view illustrating features of the linear slide damper of  FIGS. 1-3  in further detail. 
         FIG. 5  is a top schematic view of the linear slide damper in a closed position. 
         FIGS. 6A-6B  are top schematic views of the linear slide damper in open positions. 
         FIGS. 7A-7B  are side schematic views illustrating a portion of the linear slide damper in different states of engagement with a switch. 
         FIG. 8  is a schematic perspective view of exemplary connections suitable for use with the linear slide damper. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , a schematic perspective view of a first embodiment of a system  20  comprising a linear slide damper assembly  30  is shown and described. The linear slide damper assembly  30  is shown coupled to an upper surface  23  of a water heater tank  22 . It will be appreciated that, while the linear slide damper assembly  30  is shown as being coupled to a water heater tank in the example described herein, the linear slide damper assembly  30  may be used in other systems and applications. 
     A cover  50  may be mounted to the upper surface  23  of the water heater tank  22  in order to enclose components of the linear slide damper assembly  30 . The cover  50  may include a main housing  52  and a motor housing portion  53 , as shown in  FIG. 1 . The main housing  52  encloses a majority of the components of the linear slide damper assembly  30 , and comprises a height h, as shown in  FIG. 1 . The height h of the main housing  52  used with the linear slide damper assembly  30  is considerably shorter than a housing that would be used with a conventional rotary-style damper assembly. In particular, the damper blade sizes used on residential water heaters generally range between about 3 inches to about 4 inches in diameter, so by eliminating the rotating blade of a rotary damper, for which circumferential rotation impacts vertical height above the water heater  22 , the height of the present linear damper system may be reduced between about 1.5 inches to about 2 inches, or approximately one-half of the damper blade diameter. 
     A flue passage  24  is disposed at the upper surface  23  of the water heater tank  22 . An inner draft limiting ring  25  is positioned adjacent to the flue passage  24 , as best seen in  FIG. 2 . A draft hood  26  may be mounted to the main housing  52  at a position above the flue passage  24  and the inner draft limiting ring  25 , as shown in  FIGS. 1 and 3 . It should be noted that the motor housing portion  53  may be offset from the draft hood  26 , and therefore the motor housing portion  53  does not increase the overall height of the system  20  beyond the height h of the main housing  52  plus the draft hood  26 . 
     During use, when the linear slide damper assembly  30  is in an open position as shown in  FIGS. 6A-6B  below, flue gases flow through the flue passage  24  and through the inner draft limiting ring  25  towards the draft hood  26 . The linear slide damper  30  does not reduce the effective open area of the flue passage  24  since the damper blade is completely removed from overlap with the flue passage  24  in the open position, as will be explained further below. By contrast, in a conventional rotary-style damper system, the effective surface area of the damper blade itself can reduce the outlet venting area by about 10% due to the presence of the rotary damper within the flue passage  24 , and moreover, a 10 degree variation of the damper&#39;s vertical orientation from a true vertical position in the open state in a rotary system can reduce the effective open area by an additional 10%. 
     Under a down draft condition, flue gases from the flue passage  24  are restricted by air flow from a vent, which produces a downward capping pressure on the flue area, and a reduction in flue gas flow can be seen. To reduce the effect of the capping pressure during the down drafting condition, the inner draft limiting ring  25  is used to divert the downward flow of air from the vent away from the flue passage  24 . Advantageously, the inner draft limiting ring  25  diverts the down flow of air away from the damper outlet and allows for the gases to vent horizontally out of the damper to reduce the capping pressure produced on the outlet of the damper. 
     Referring now to  FIGS. 4-6 , further features of the linear slide damper assembly  30  of  FIGS. 1-3  are shown and described in further detail. Linear slide damper assembly  30  comprises a damper blade  32  having first and second ends  33  and  34 , respectively. In this example, the damper blade  32  comprises a generally rectangular shape, which may facilitate being guided linearly within a channel and covering the flue passage, although it will be appreciated that other shapes may be employed. 
     The damper blade  32  comprises closed and open states, as shown in  FIGS. 5-6 , respectively. The damper blade  32  comprises a solid segment  32   a  that is dimensioned to cover the entirety of the flue passage  24  when the damper blade  32  is in the closed state, as shown in  FIG. 5 . The damper blade  32  is linearly movable along a longitudinal axis L, such that it moves from the closed state to an open state as shown in  FIGS. 6A-6B . 
     The linear slide damper assembly  30  further comprises a drive member  40 . In the examples shown herein, the drive member  40  comprises a shape that is slightly larger than semi-circular, with a location  41  corresponding to a center of a circle that would be defined if the drive member  40  were to comprise a full circle. A motor may be operatively coupled to the drive member  40  at the location  41 , such that rotation of the motor causes corresponding rotation of the drive member  40  about the location  41 . 
     The damper blade  32  further comprises a slot  35 , which may be positioned at the first end  33  of the damper blade  32 , and which extends in a perpendicular direction relative to the longitudinal axis L. It will be appreciated that while the exemplary slot  35  is shown as an integral opening disposed at the first end  33  of the damper blade  32 , the slot  35  alternatively may comprise a separate opening or channel that is operatively coupled to the damper blade  32 , whether at the first end  33  or another location, to achieve the functions described below. 
     The drive member  40  comprises a pin  42 , which in the example shown is positioned at an outer periphery of the drive member  40 . The pin  42  of the drive member  40  is disposed within the slot  35  of the damper blade  32 . 
     In use, rotational movement of the drive member  40 , e.g., via the motor, is translated into linear motion of the damper blade  32 . Specifically, as the drive member  40  is rotated, the pin  42  rotates circumferentially about the location  41 . As the pin  42  rotates, it moves in directions that are both parallel and perpendicular to the longitudinal axis L of the assembly. Since the pin  42  is secured within the slot  35  of the damper blade  32 , the linear movement of the pin  42  relative to the longitudinal axis L causes a corresponding linear movement of the slot  35  along the longitudinal axis L. During this movement, the pin  42  may move laterally within the slot  35  as needed. 
     As the pin  42  and the slot  35  move linearly along the longitudinal axis L, the entirety of the damper blade  32  moves linearly along the longitudinal axis L. The damper blade  32  may be guided by channels, such as partially rectangular or C-shaped channels that at least partially enclose opposing sides the damper blade  32 , to assure the linear movement path shown. In this manner, the solid segment  32   a  of the damper blade  32  is moved linearly between the closed and open states of  FIGS. 5-6 , respectively. 
     Advantageously, the linear slide damper assembly  30  reduces the height required to mount the damper between the water heater  22  and the draft hood  26 , as compared to conventional rotating damper assemblies having blades that rotate circumferentially at least partially in a vertical direction between the water heater and draft hood. 
     As another advantage, the damper blade  32  of the present embodiments is entirely removed from the air stream of the flue passage  24  when in the open state, as seen in  FIGS. 6A-6B . Such design of the present embodiments is expected to reduce flow obstruction during operation of the water heater  22  as compared to a conventional rotating damper blade that is positioned partially within the flue passage. 
     As a further advantage, the present linear damper system can allow at least a 5 degree variation, and up to a 20 degree or more variation, in the position of the drive member  40  while still maintaining a completely open state, as depicted in the different open states of  FIGS. 6A-6B . In particular, the flue passage  24  is entirely open in both  FIG. 6A  and  FIG. 6B , even when there is a relatively large degree of variation of the rotational position of the drive member  40 . In contrast, a typical rotary drive damper uses a cam or other mechanical position indicators to position the damper blade in the open position vertically within the flue passage, and in such systems the desired positional tolerance is plus or minus 3 degrees, which requires precision components and limits the type of drive motors that can be used. 
     In short, the combination of the drive member  40  being coupled to the damper blade  32  reduces the stopping position accuracy required by the actuation components, e.g., including a motor, which increases the allowable tolerance. Such design allows for the use of simple controls to operate a DC volt operated motor, which can continue to rotate after power is removed due to the residual magnet field of the motor dissipating. 
     Referring to  FIGS. 7A-7B , a portion of the linear slide damper assembly  30  is shown in different states of engagement with a switch. The linear slide damper design uses the first end  33  of the damper blade  32  to indicate the open position of the damper.  FIG. 7A  shows the first end  33  of the damper blade  32  about to contact a tapered segment  62  on a switch activation arm  60 , while  FIG. 7B  shows the first end  33  of the damper blade  32  being pushed into full engagement with the tapered segment  62  of the switch activation arm  60 . The state of  FIG. 7B  corresponds to the states of  FIGS. 6A-6B , in which the damper blade  32  is in the open state. In the open state, the damper blade  32  may move the tapered segment  62  of the switch activation arm  60  in a direction or manner such that a switch activation point  64  of the switch activation arm  60  becomes fully engaged with damper position switch contacts  84 , as shown in  FIG. 8  below. The periodic connection between the switch activation point  64  and the damper position switch contacts  84  provides a signal confirming that the damper blade  32  is in the open position. 
     Advantageously, the technique shown in  FIGS. 7A-7B  ensures that the damper blade  32  is in the open position before the burner operates by providing direct contact of the damper blade  32  itself with position sensing controls. This ensures that the damper blade  32  is in the fully open state before allowing the water heater burner to fire. In contrast, typically on rotary style dampers, the open position of the damper is indicated by a lobe on a cam device connected between the drive motor and the shaft of the damper, and there is no direct indicator to ensure the damper blade is opened completely because the positional indicator is attached to the drive unit and not to the damper blade itself. 
     Referring to  FIG. 8 , a schematic view of exemplary connections suitable for use with the linear slide damper assembly  30  are shown and described. The exemplary connections comprise damper position switch contacts  84 , motor power connections  85 , motor operation activation arm  86 , neutral power and motor connection  87 , and damper blade position circuit connections  88 . 
     The motor position is controlled by the motor operation activation arm  86 . When the damper blade  32  is in the closed position, the motor power connections  85  are coupled to the normally closed connection, which allows power to be applied to the motor to drive the damper blade  32  to the open position. When the damper blade  32  reaches the fully open state, the switch activation arm  60  is engaged, as explained in  FIG. 7B  above, to switch the contact from the closed to the open contact, which stops the motor rotation. The damper is driven closed by applying power to the normally open contact, and once the damper reaches the full closed position the motor activation arm moves off the tapered segment  64  on the drive arm, which resets the motor drive circuit to the closed position. 
     As noted in  FIGS. 7A-7B  above, the open position of the damper blade  32  is verified by the activation of a pair of contacts  64 , which are engaged when the damper blade  32  is in the open state. While the exemplary system of  FIG. 8  shows the use of simple contacts to operate the damper and to prove the damper open position, these contacts could be substituted with micro switches or magnetic reed switches if small magnets are added to the ends of the switch and motor activation arms. 
     While various embodiments of the invention have been described, the invention is not to be restricted except in light of the attached claims and their equivalents. Moreover, the advantages described herein are not necessarily the only advantages of the invention and it is not necessarily expected that every embodiment of the invention will achieve all of the advantages described.