Patent Application
20170299212
The present invention relates to systems and methods for ventilating enclosed spaces, and more particularly, to a system and method for controlling activation and deactivation of an exhaust system for ventilating an enclosed space, such as a bathroom, based on a relative humidity level.
Ventilation systems are often used to ventilate enclosed spaces, such as by removing humid air from bathrooms. The simplest ventilation systems are manually switched on and off by an occupant of the space. More sophisticated systems employ a sensor to measure an actual humidity level in the space, compare the measured actual humidity level to a stored threshold humidity level, and automatically control activation and deactivation of an exhaust system based on whether the actual humidity level exceeds the threshold humidity level. The exhaust system remains activated until the actual humidity level falls below the threshold humidity level or times out.
This background discussion is intended to provide information related to the present invention which is not necessarily prior art.
Embodiments of the present invention solve the above-described and other problems and limitations by providing a system and method for controlling activation and deactivation of an exhaust system for ventilating an enclosed space based on a relative humidity level. Rather than blindly operate the ventilation system continuously or for a pre-determined interval, the present invention smartly controls operation of the ventilation system based on the relative humidity value.
In a first embodiment of the present invention, a system is provided for controlling activation and deactivation of an exhaust system for ventilating an enclosed space. The system may broadly include a humidity sensor, a memory element, and a processing element. The humidity sensor may be configured to measure a humidity value in the enclosed space. The memory element may be configured to receive and store the measured humidity value along with a series of previously measured humidity values, and to store a look-up table. The processing element may be configured to calculate a normal humidity value based on a weighted average of the stored series of previously measured humidity values, and to consult the look-up table which specifies activation and deactivation criteria for the exhaust system based on the measured humidity value and the normal humidity value, and to cause the exhaust system to activate or deactivate as specified by the look-up table.
Various implementations of the first embodiment may include any one or more of the following additional features. The exhaust system may include an exhaust fan for drawing air out of the enclosed space, a motor for driving the exhaust fan, and a grill for shielding access to an interior of the exhaust system. The enclosed space may be a bathroom, and the exhaust system may be installed in a ceiling of the bathroom or attic space. The humidity sensor may be positioned near the exhaust system, or the humidity sensor may be positioned remote from the exhaust system. The measured humidity value may be added to the series of previously measured humidity values and stored in the memory element at a first interval of approximately between ten and thirty seconds, or approximately between fifteen and twenty-five seconds. The normal humidity value may be calculated based on the weighted average of the series of previously measured humidity values stored in the memory element over a second interval of approximately between twenty and forty seconds, or approximately thirty seconds. While the exhaust system is activated, the normal humidity value may not be re-calculated. If the exhaust system remains activated for more than a time limit, the processing element may deactivate the exhaust system even if the measured humidity value does not satisfy the deactivation criteria specified in the look-up table, and the system may reset by determining a new normal humidity value. The system may further include an occupancy sensor configured to determine whether the enclosed space is occupied, and the processing element may be further configured to control activation and deactivation of the exhaust system only when the enclosed space is occupied.
In a second embodiment of the present invention, a system is provided for controlling activation and deactivation of an exhaust fan for ventilating a bathroom. The system may broadly include a humidity sensor, a memory element, and a processing element. The humidity sensor may be configured to measure a humidity value in the bathroom. The memory element may be configured to receive and store at a first interval of approximately between ten and thirty seconds the measured humidity value along with a series of previously measured humidity values, and to store a look-up table. The processing element may be configured to calculate a normal humidity value based on a weighted average of the series of previously measured humidity values stored in the memory element over a second interval of between twenty and forty seconds, and to consult the look-up table which specifies activation and deactivation criteria for the exhaust fan based on the measured humidity value and the normal humidity value, and to cause the exhaust fan to activate or deactivate as specified by the look-up table. This second embodiment may further one or more additional features discussed in connection with other embodiments.
In a third embodiment of the present invention, a method is provided for controlling activation and deactivation of an exhaust fan for ventilating a bathroom. The method may broadly include the following steps. A humidity sensor may measure a humidity value in the bathroom. An electronic memory element may receive and store at a first interval of approximately between ten and thirty seconds the measured humidity value along with a series of previously measured humidity values. An electronic processing element may calculate a normal humidity value based on a weighted average of the series of previously measured humidity values stored in the memory element over a second interval of between twenty and forty seconds. The electronic processing element may consult a look-up table stored in the memory element which specifies activation and deactivation criteria for the exhaust fan based on the measured humidity value and the normal humidity value. The electronic processing element may cause the exhaust fan to activate or deactivate as specified by the look-up table. This third embodiment may further include one or more additional features discussed in connection with other embodiments.
This summary is not intended to identify essential features of the present invention, and is not intended to be used to limit the scope of the claims. These and other aspects of the present invention are described below in greater detail.
Embodiments of the present invention are described in detail below with reference to the attached drawing figures, wherein:
The figures are not intended to limit the present invention to the specific embodiments they depict. The drawings are not necessarily to scale.
The following detailed description of embodiments of the invention references the accompanying figures. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those with ordinary skill in the art to practice the invention. Other embodiments may be utilized and changes may be made without departing from the scope of the claims. The following description is, therefore, not limiting. The scope of the present invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.
In this description, references to “one embodiment”, “an embodiment”, or “embodiments” mean that the feature or features referred to are included in at least one embodiment of the invention. Separate references to “one embodiment”, “an embodiment”, or “embodiments” in this description do not necessarily refer to the same embodiment and are not mutually exclusive unless so stated. Specifically, a feature, structure, act, etc. described in one embodiment may also be included in other embodiments, but is not necessarily included. Thus, particular implementations of the present invention can include a variety of combinations and/or integrations of the embodiments described herein.
Broadly characterized, the present invention provides a system and corollary method for controlling activation and deactivation of an exhaust system for ventilating an enclosed space based on a relative humidity value. The system monitors transient fluctuations in humidity values over a period time in order to determine a normal humidity value at any particular time. The system then sets limits on normal levels and calls for ventilation when a current humidity value exceeds these limits. Thus, rather than blindly operate the ventilation system continuously or for a pre-determined interval, the present invention smartly controls operation of the ventilation system based on relative humidity values.
Referring to
The one or more humidity sensors 30 may be configured to measure a humidity value of the air in the space 14. The humidity sensor(s) 30 may be mounted near to 30a,30b and/or remote from 30c the exhaust system 12. The electronic memory element 32 may be configured to receive and store the measured humidity value along with a series of previously measured humidity values, and to store a look-up table. The system 10 may measure and/or store the humidity value continuously or periodically, such as at a first interval of approximately between ten (10) and thirty (30) seconds, or approximately between fifteen (15) and twenty-five (25) seconds, or approximately eighteen and seventy-five hundredths (18.75) seconds.
The electronic processing element 34 may be configured to calculate a normal humidity value based on a weighted average of the stored series of previously measured humidity values, and to consult the look-up table which specifies criteria for activation or deactivation of the exhaust fan 18 based on the measured humidity value and the calculated normal humidity value, and to cause the exhaust fan 18 to activate or deactivate as specified by the look-up table. In one implementation, the processing element 34 may calculate at a second interval, which may be approximately between twenty (20) and forty (40) seconds, or approximately thirty (30) seconds, the weighted average of the series of previously measured humidity values as follows: Average Humidity=(Average Humidity−(Average Humidity/32))+(Reading×32)). If the first interval between humidity measurements and/or storage is eighteen and seventy-five hundredths (18.75) seconds, then this algorithm produces an averaging filter with a natural time constant (T) of 10 minutes (i.e., 18.75 seconds×32). This filter may track to within five percent (5%) of a step value change in three T (3T), or thirty (30) minutes.
Thus, the system 10 may measure and/or store the actual humidity value at the first interval (e.g., eighteen and seventy-five hundredths (18.75) seconds), and then calculate the weighted average of the stored series of previous humidity values measured over the second interval (e.g., thirty (30) seconds) to determine the “normal” humidity value for the space 14. In general, if the normal humidity value is X, and if the measured actual humidity value, Y, is greater than the system “ON” set point, then the system 10 may activate the exhaust fan 18, and then if the measured humidity value drops below the system “OFF” set point, the system 10 may deactivate the exhaust fan 18. In one implementation, as long as the exhaust fan 18 is activated, the system 10 may not update the normal humidity value (i.e., the normal relative humidity value is temporarily fixed).
An exemplary look-up table may be constructed substantially as follows. In this table, XX % may be a user-adjustable variable between thirty percent (30%) and seventy percent (70%), wherein lower values may bring humidity values closer to normal, while higher values may reduce the running time of the exhaust fan 18.
In one implementation, if the exhaust fan 18 remains activated for more than a time limit, such as approximately between two (2) and three (3) hours, or approximately two and one-half (2.5) hours, the exhaust fan 18 may be deactivated and the system 10 may be reset even if the measured humidity value does not satisfy the deactivation criteria. This may occur when the exhaust system 12 is not capable of sufficiently reducing the humidity level, which might happen, for example, if a window is opened and the space 14 is flushed with humid outside air. If this happens, a new normal humidity value may be determined to reflect the abnormally high humidity value, and the process may proceed with the new normal humidity value.
In one implementation, the system may further include a motion or other sensor 38 configured to determine whether the space 14 is occupied, and to consider the occupancy status when controlling the exhaust fan 18, such as by activating or continuing to activate the exhaust system 12 only when the enclosed space is occupied.
Referring to
Other features described with regard to the system 10 may similarly apply to the method 110. For example, in one implementation, if the exhaust system 12 remains activated for more than the time limit, the method 110 may further include deactivating by the processing element 34 the exhaust system 12 even if the measured humidity value does not satisfy the deactivation criteria specified in the look-up table, and resetting by the processing element 34 by calculating a new normal humidity value, as shown in 122. Similarly, the method 110 may further include determining with the occupancy sensor 38 whether the space 14 is occupied, and controlling by the processing element 34 activation and deactivation of the exhaust system 12 only when the space 14 is occupied, as shown in step 124.
Although the invention has been described with reference to the one or more embodiments illustrated in the figures, it is understood that equivalents may be employed and substitutions made herein without departing from the scope of the invention as recited in the claims.
