POSITIVE DISPLACEMENT VENTILATION SYSTEM
A method includes inflating one or more inflatable bags from a first evacuated condition within an attic space to an inflated condition. The inflatable bags are configured such that when they are in an evacuated condition, they take up a relatively small space in the attic space to be ventilated. In the inflated condition, however, the bags have a cumulative volume much larger than the cumulative volume of the bags when in the evacuated condition, and make up a desired fraction of the volume of the attic space to be ventilated. When the bags are inflated from the evacuated condition to the inflated condition, they displace a volume of atmosphere equal to the difference between the cumulative volume of the bags in the evacuated condition and the cumulative volume of the bags in the inflated condition. The bags are then evacuated from the inflated condition to the fully evacuated condition or at least a substantially evacuated condition so as to draw ventilation air into the attic space through one or more ventilation inlets to the attic space.
The present invention relates to ventilation systems for enclosed spaces, and more particularly, to ventilation systems employing inflatable elements to displace the atmosphere from an enclosed space.
BACKGROUND OF THE INVENTIONThe attic space included in many houses and other buildings can have a significant impact on cooling requirements for the inhabited portions of the building. In hot, sunny weather, sunlight incident on the roofing material quickly heats the material and much of this heat is eventually transferred to the attic air. The heat accumulated in an attic space may be transferred to the inhabited areas of the building by conduction through ceiling materials even when the ceiling is well insulated. Hot air trapped in an attic space can also leak into inhabited areas through utility and other openings in ceilings and walls.
Numerous different systems have been developed to ventilate the hot air from an attic and replace it with cooler air from outside. Attic ventilation systems may generally be categorized as passive systems or forced-air systems. Passive attic ventilation systems typically include exhaust vents located at the high points of the roof structure and inlet openings located at lower points of the roof system, commonly along the soffits of the roof structure. This type of passive ventilation system allows hot attic air to rise out through the roof vents while cooler air is drawn in through the lower inlets. However, while hot air does rise in the attic space and eventually flow out through the roof vents to be replaced by cooler air entering through the lower inlets, these types of passive attic ventilation systems generally provide insufficient circulation through the attic to prevent heat from building up in the attic space.
Forced-air type attic ventilation systems use wind-driven or motor-driven fans to move air to and/or from an attic. While such devices can move air much more quickly than passive attic ventilation systems, they are typically more expensive. Furthermore, although fans may be capable of displacing a large amount of air, they may move the air in such a way as to create narrow flow channels through the attic space. If such channels occur, a portion of the air in the attic may remain stagnant, and the attic will not be effectively ventilated. Such incomplete ventilation may cause hot air to remain in the attic and cause undesirable heating in the inhabited areas of the building.
SUMMARY OF THE INVENTIONThe present invention includes methods and apparatus employing positive displacement for ventilating an enclosed space, particularly an attic space. The positive displacement ensures that atmosphere is effectively removed from the space to be ventilated.
One preferred method according to the present invention uses inflatable bags to ventilate an attic space. The method includes inflating one or more inflatable bags in the attic space from a first evacuated condition to an inflated condition. The inflatable bags are configured such that when they are in an evacuated condition, they take up a relatively small space in the attic space to be ventilated. In the inflated condition, however, the bags have a cumulative volume much larger than the cumulative volume of the bags when in the evacuated condition, and make up a desired fraction of the volume of the attic space to be ventilated. When the bags are inflated from the evacuated condition to the inflated condition, they displace a volume of atmosphere equal to the difference between the cumulative volume of the bags in the evacuated condition and the cumulative volume of the bags in the inflated condition. This volume of displaced atmosphere makes up desired fraction of the atmosphere within the attic, and is displaced through one or more ventilation outlets associated with the attic space as the bags are inflated. The bags are then evacuated from the inflated condition to the fully evacuated condition or at least a substantially evacuated condition (that is, a second evacuated condition) so as to draw ventilation air into the attic space through one or more ventilation inlets to the attic space.
The “desired fraction” of attic atmosphere which is displaced as the bags are inflated may be any significant fraction. Preferably, the desired fraction of atmosphere which is displaced as the bags are inflated is approximately thirty percent (30%) or more of the total volume of the attic space to be ventilated. However, lesser fractions of the total attic space volume, even as little as about ten percent (10%) can be used to effectively ventilate an attic space.
Although methods according to the present invention have particular application to ventilating attic spaces in homes and other buildings, the methods may also be employed in ventilating other enclosed spaces. Regardless of the particular enclosed space to which a method according to the invention is applied, the invention is well suited for displacing atmosphere having a first physical characteristic such as temperature, humidity, contaminant level, or some combination of these, and for drawing in atmosphere having a second physical characteristic. In one example, inflating the bag or bags in the enclosed space may displace and expel a desired fraction of atmosphere in the enclosed space at a first temperature. Evacuating the bag or bags to the evacuated condition may be applied so as to draw in atmosphere at a temperature that is significantly below or above the first temperature.
An apparatus according to the present invention includes one or more inflatable bags, each inflatable bag having a control opening. The one or more inflatable bags are sized so that when they are in an inflated condition they occupy a cumulative volume representing a desired fraction of a space to be ventilated. A blower is included in the apparatus along with a manifold which preferably includes an arrangement of conduits and a flow switching arrangement. The manifold operates to selectively connect the blower to the respective control opening of each bag to enable the blower to impress a desired air flow through each control opening. In particular, when the flow switching arrangement of the manifold is placed in a first condition it connects the blower to each control opening so as to enable the blower to impress a flow of air into each control opening to inflate each bag and thereby displace atmosphere from the space to be ventilated. When the flow switching arrangement is in a second condition, it connects the blower to each control opening so as to enable the blower to impress an opposite flow through the control opening of each bag to evacuate the bags. This flow out of the bags causes the bags to deflate and take up less volume in the space to be ventilated. A replacement atmosphere is drawn in to the space to be ventilated as the bags deflate.
These and other advantages and features of the invention will be apparent from the following description of the preferred embodiments, considered along with the accompanying drawings.
In the following description, the diagrammatic representations shown in
Referring to
A controller 112 is adapted to control the operation of both blower 103 and switching arrangement 104 to selectively inflate bags 102 from an evacuated condition to an inflated condition, and then evacuate the bags from the inflated condition to an evacuated condition. Controller 112 may operate using a number of different inputs shown diagrammatically in
Once inflatable bags 102 reach the desired inflated condition shown by the solid lines for the bags in
The cycle of operation described above, that is, the inflation of the bags 102 to the inflated condition and then evacuation to an evacuated condition, may be performed multiple times in close succession in order to ventilate space 108. On each cycle of operation, the system displaces the desired fraction of the atmosphere in space 108 and draws in a substantially equal volume of replacement atmosphere. This positive displacement of atmosphere and replacement provides a very effective level of ventilation for space 108 and avoids many of the problems associated with prior ventilation systems for enclosed spaces such as an attic space. Whether one cycle of operation is performed or multiple cycles of operation, it should be appreciated that the evacuated condition of the bags at the start of the cycle and at the end of the cycle may be somewhat different since it may be impractical to completely evacuate the bags in a given implementation. Thus, the evacuated condition of the bags may be referred to herein and in the following claims as different evacuated conditions, for example, a first and second evacuated condition. This usage merely indicates that the level of evacuation for the bags is somewhat variable and that it is not necessary to fully evacuate each bag on each cycle of operation. It is sufficient that the difference between the inflated condition of the bags and the evacuated condition (both at the start and end of the operation cycle) is such that the desired fraction of atmosphere is displaced from the space to be ventilated and a desired fraction of replacement atmosphere is drawn in to the space to be ventilated on each cycle of operation.
One preferred application of the invention is to ventilate an attic space in warm weather where the attic air can climb to temperatures far exceeding the ambient temperature. Temperature sensors such as sensor 116 inside the space to be ventilated and ambient air sensor 117 may be used together with controller 112 to ensure that the system performs a cycle of operation only when a certain differential exists between the air temperature in the space to be ventilated and the outside or ambient air that will be used as replacement air in the operation cycle. Controller 112 is preferably set so that the air temperature in the space to be ventilated is at least ten (10) degrees Fahrenheit higher than the ambient air before the system performs a cycle of operation. Although a 10° F. differential is preferred to trigger a cycle of operation for attic space ventilation purposes, other differentials may be employed within the scope of the invention, in particular a temperature differential between approximately 5° F. and 20° F. A temperature differential between the air temperature in the space to be ventilated and the ambient air temperature may also be used to stop the operation of the ventilation system. For example, where the start operation temperature differential is 10° F., controller 112 may be programmed to discontinue operation once the sensors 116 and 118 show a temperature differential of approximately five (5) degrees Fahrenheit of enclosed air temperature to ambient air temperature. Regardless of the temperature differential or other input or set of inputs used to discontinue operation of system 100, controller 112 is preferably programmed to complete a cycle and return the bags to an evacuated condition, and then discontinue operation at that point.
Each cycle of operation of apparatus 100 is preferably controlled using the pressure signal provided by pressure sensor 118. In particular, controller 112 may be programmed so that it operates flow switching arrangement 104 and blower 103 to inflate bags 102 until some predetermined pressure is reached in the bags, as indicated by the pressure sensed in conduit 105. That pressure may be set as a pressure at which bags 102 are inflated and expanded to a certain degree corresponding to the desired level of displacement of atmosphere from enclosed space 108. Alternately to a pressure signal, controller 112 may rely on a signal from a switch which is physically actuated by contact with a given bag 102 when the bag is inflated to a desired degree. Numerous other inputs such as tension in the material of bags 102, or length or width of the bags (as indicated by optical sensors for example), may be used to provide an indication when the bags are inflated to the desired degree, and thereby allow controller 112 to switch the operation of flow switching arrangement 104 to evacuate bags 102 and complete a cycle of operation. It should also be appreciated that additional control elements may be used in the operation to inflate and evacuate bags 102. For example, a pressure relief valve 119 may be included in conduit 105 or elsewhere in the system to ensure that some maximum pressure is not exceeded in bags 102.
Although the application to ventilate a space in order to reduce the temperature in the space represents a preferred application of the present invention, numerous other applications are possible within the scope of the invention as defined in the claims below. For example, apparatus 100 may be adapted to provide a replacement atmosphere that is warmer than the atmosphere displaced from space 108. In another example, the replacement atmosphere may be less humid or conceivable more humid than the atmosphere displaced from the enclosed space. In yet another example, a positive displacement ventilation system according to the present invention may be employed to decrease the concentration of a toxic or other gas within the enclosed space. Of course in applications that do not necessarily alter temperature in the enclosed space 108, controller 112 may operate to control blower 103 and flow switching arrangement 104 using sensors suitable for sensing the desired atmospheric condition to be changed within the enclosed space.
It should also be noted that although a preferred application of the present ventilation system is in connection with controlling temperature in attic space, the present invention is also applicable for providing ventilation to control temperature in other types of enclosed spaces. For example, a positive displacement ventilation system within the scope of the present invention may be used to control temperatures in the passenger compartment of an automobile or truck. In this application, the inflatable bag or bags would be housed in the passenger compartment such that they may be expanded when the vehicle is not occupied and then evacuated so as to be housed in an unobtrusive fashion within seats, doors, and/or roof.
Controller 112 may comprise any suitable device for properly activating blower 103 and flow switching arrangement 104 in order to inflate and then evacuate bags 102 in an operation cycle as described above. For example, controller 112 may comprise a programmable logic controller which has the capacity to receive the necessary control inputs, such as the inputs from sensors 116, 117, and 118 in
Depending upon the purpose of the ventilation provided according to the invention, it may be important to control the location from which the replacement atmosphere is taken, or the location at which the displaced atmosphere is expelled from the space to be ventilated (such as space 108 in
In other attic ventilation implementations, replacement air may be taken from a location adjacent the building which is shaded and protected at least somewhat from heating by solar radiation. For example, one or more ventilation inlets may include a suitably sized duct which extends to an area from which replacement air is to be taken. In this alternate implementation, one-way ridge vents may be used as ventilation outlets. Alternatively, one or more ventilation outlets may include a duct for directing the hot air displaced from the attic space to some desired location, preferably far removed from the area from which the replacement air is drawn.
One preferred implementation for ventilating a space to be cooled (such as an attic space) includes an arrangement for introducing a water mist into the stream of air directed from blower 103 to inflatable bags 102. This mist may provide some degree of evaporative cooling in the inflatable bags 102 to help remove heat from the space to be ventilated by heat transfer through the bag material. Since the added water is maintained in the bags 102 and conduits 105, it does not pose a risk of damage to the materials defining the space to be ventilated. A preferred device 124 for introducing a water mist is located in the conduits 105 adjacent to flow switching arrangement 104. Although the details of misting device 124 are not shown in
In a cycle of operation of a system according to the invention employing bag 302, the bag is initially in the evacuated condition shown in
Although
It should be appreciated that numerous variations on the arrangement shown in
In order to perform the inflation and evacuation of each bag 1002 (as described above in connection with corresponding bags 102 shown in
It should be noted that although bags 1002 are shown in
Although the implementations shown in
First valve plate 1204 and second valve plate 1206 are adapted to move relative to each other so that the two plates may be aligned in a first condition or a second condition.
In a preferred implementation of the flow switching arrangement 1201 shown in
It will also be appreciated that seals are required between first valve plate 1204 and second valve plate 1206 to facilitate efficient flow along the desired flow paths defined by the two valve plates. A close tolerance between the abutting surfaces of the two plates 1204 and 1206 may provide suitable seals in some cases. Otherwise, a gasket or O-ring arrangement may be used between the two plates 1204 and 1206 to provide the desired seals, but allow the required relative movement between the two plates. It should also be appreciated that the size of the various plate openings 1207, 1210, 1214, 1217, and 1218 will depend on the flow rate required to fill and evacuate the inflatable bags according to the method described in connection with
Flow switching arrangement 1401 is adapted to be alternatively placed in a first condition in which the blower 1402 inflates the bag or bags connected to conduit 1407, or a second condition in which the blower helps evacuate the bags or bags (the bags not being shown in
Each of the valves 1404, 1408, 1412, and 1413 is illustrated schematically in
As used herein, whether in the above description or the following claims, the terms “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” and the like are to be understood to be open-ended, that is, to mean including but not limited to. Any use of ordinal terms such as “first,” “second,” “third,” etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another, or the temporal order in which acts of a method are performed. Rather, unless specifically stated otherwise, such ordinal terms are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term).
The above described preferred embodiments are intended to illustrate the principles of the invention, but not to limit the scope of the invention. Various other embodiments and modifications to these preferred embodiments may be made by those skilled in the art without departing from the scope of the present invention.
Claims
1. A method for ventilating an attic space, the method including:
- (a) inflating one or more inflatable bags from a first evacuated condition in the attic space to an inflated condition in the attic space, the one or more inflatable bags having a total volume in the inflated condition which comprises a desired fraction of the volume of the attic space so that the inflation of the one or more inflatable bags from the first evacuated condition to the inflated condition displaces a desired fraction of the atmosphere in the attic space through one or more ventilation outlets from the attic space; and
- (b) evacuating the one or more inflatable bags in the attic space from the inflated condition to a second evacuated condition, the evacuation of the one or more inflatable bags drawing ventilation air into the attic space through one or more ventilation inlets to the attic space.
2. The method of claim 1 wherein evacuating the one or more inflatable bags includes applying a reduced pressure to the interior of each respective inflatable bag.
3. The method of claim 2 wherein evacuating the one or more inflatable bags includes applying an elongation force to each respective inflatable bag to elongate each respective bag along a first axis thereof and reduce a dimension of the respective bag along a second axis transverse to the first axis, the elongation force being a force exceeding a force resulting from the mass of the respective inflatable bag.
4. The method of claim 1 wherein evacuating the one or more inflatable bags includes applying an elongation force to each respective inflatable bag to elongate each respective bag along a first axis thereof and reduce a dimension of the respective bag along a second axis transverse to the first axis, the elongation force being a force exceeding a force resulting from the mass of the respective inflatable bag.
5. The method of claim 1 wherein the one or more inflatable bags are suspended within the attic space and wherein inflating the one or more inflatable bags includes raising a lower surface of each inflatable bag upwardly in the attic space.
6. The method of claim 1 wherein inflating the one or more inflatable bags and evacuating the one or more inflatable bags includes operating a blower which is connected to each of the one or more inflatable bags through a manifold.
7. The method of claim 1 wherein inflating the one or more inflatable bags includes applying positive pressure from a blower to the one or more inflatable bags through a valve structure in a first position, and wherein evacuating the one or more inflatable bags includes applying a vacuum from the blower to the one or more inflatable bags through the valve structure in a second position.
8. A method for modifying the atmospheric temperature in an enclosed space, the method including:
- (a) inflating an inflatable bag from a first evacuated condition in the enclosed space to an inflated condition in the enclosed space to displace a desired fraction of an atmosphere from the enclose space, the displacement causing a portion of the atmosphere from the enclosed space to be expelled from the enclosed space through one or more outlet openings to the enclosed space, wherein the expelled atmosphere has a first physical characteristic; and
- (b) evacuating the inflatable bag in the enclosed space to evacuate the inflatable bag from the inflated condition to a second evacuated condition, the evacuation of the inflatable bag drawing replacement atmosphere into the enclosed space through one or more ventilation openings to the enclosed space, wherein the replacement atmosphere has a second physical characteristic at the time it is drawn into the enclosed space, and wherein the second physical characteristic is different from the first physical characteristic.
9. The method of claim 8 wherein the first physical characteristic comprises a first temperature and the second physical characteristic comprises a second temperature.
10. The method of claim 9 wherein the second temperature is at least ten (10) degrees Fahrenheit below the first temperature.
11. The method of claim 8 wherein the enclosed space is an attic space and wherein inflating the inflatable bag and evacuating the inflatable bag is performed with a single blower device.
12. The method of claim 8 wherein the inflatable bag is suspended in the enclosed space and wherein inflating the inflatable bag includes raising a lower end of the inflatable bag to decrease the dimension of the inflatable bag along a first axis and increase the dimension of the inflatable bag along a second dimension extending transverse to the first dimension.
13. The method of claim 12 wherein evacuating the inflatable bag includes applying an elongation force at the lower end of the inflatable bag, the elongation force being a force exceeding a force resulting from the mass of the inflatable bag.
14. An apparatus including:
- (a) one or more inflatable bags, each inflatable bag having a control opening;
- (b) a blower;
- (c) a manifold adapted to selectively connect the blower to the respective control opening of each of the one or more inflatable bags to enable the blower to impress a desired air flow through each respective control opening; and
- (d) wherein the one or more inflatable bags are sized so that when they are in an inflated condition they occupy a total volume representing a desired fraction of a space to be ventilated.
15. The apparatus of claim 14 wherein manifold includes:
- (a) a bag connecting conduit; and
- (b) a switching arrangement adapted to reside alternatively in a first condition and a second condition, the first condition connecting a fill outlet of the blower to the control opening of each of the one or more inflatable bags through the bag connecting conduit, and the second condition connecting a vacuum outlet of the blower to the inlet opening of each of the one or more inflatable bags through the bag connecting conduit.
16. The apparatus of claim 15 further including a controller adapted to control the operation of the blower and control the condition of the switching arrangement in response to control inputs.
17. The apparatus of claim 16 further including a pressure sensor connected to provide a pressure output indicating of the pressure in the one or more inflatable bags, and wherein the control inputs include the pressure output provided by the pressure sensor.
18. The apparatus of claim 16 further including a first temperature sensor located to provide a temperature output indicating the temperature of an atmosphere in the space to be ventilated, and wherein the control inputs include the temperature output of the first temperature sensor.
19. The apparatus of claim 18 further including a second temperature sensor located to provide a temperature output indicating the temperature of ambient atmosphere outside of the space to be ventilated, and wherein the control inputs include the temperature output of the second temperature sensor.
20. The apparatus of claim 14 wherein at least one of the one or more inflatable bags is suspended in the space to be ventilated and further including a biasing weight connected to a lower end of the at least one inflatable bag to apply an elongating force to the at least one inflatable bag, the elongating force exceeding a force resulting from the mass of the at least one inflatable bag.
Type: Application
Filed: Oct 26, 2010
Publication Date: Apr 26, 2012
Inventor: Michael Davenport (Bertram, TX)
Application Number: 12/912,672
International Classification: E04B 9/02 (20060101); B65D 30/00 (20060101); F24F 11/00 (20060101); F24F 7/007 (20060101);