SYSTEM AND METHOD FOR DYNAMICALLY CONTROLLING MAXIMUM FAN SPEED TO MAINTAIN ENERGY EFFICIENCY

Description

This patent application claims the benefit of U.S. Provisional Patent Application No. 63/707,736, filed Oct. 15, 2024, the disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

This document relates generally to the fan control arts and, more particularly, to a system and method for automatically controlling a maximum fan speed to comport with energy efficiency requirements and enhanced performance.

BACKGROUND

In the context of operating certain types of air movement devices, such as fans, motors have a maximum continuous power output that can be achieved without exceeding a safe operating temperature. This maximum output is a physical limitation of the motor. In addition to physical limitations of air movement devices, building design professionals, regulatory entities, electric utilities, or other authorities may impose certain limits on the efficient operation of such fans from an energy use perspective. These limits may conceptually be thought of as imposing a maximum unit of power to maintain a specified amount of functionality. One reason for doing so is to provide a balance of fan functionality with energy consumption.

In one example, a fan must not exceed a maximum daily energy use for a sustainable building project to meet its energy efficiency goals. In this example, the fan is required to deliver a specific airflow, measured in cubic feet per minute (CFM), and to not exceed a maximum a total amount of energy used, measured in Watts (W) multiplied by the operating hours (h). This requirement could be expressed in the project specifications as a minimum efficacy of airflow divided by power (CFM/W). Other measurements or characterizations of efficacy may include the Fan Efficiency Index (or “FEI”) or the Ceiling Fan Efficiency Index (or “CFEI”).

An exemplary fan may include a 60 inch impeller diameter which operates at a maximum speed of 200 revolutions per minute (rpm) and has a maximum airflow of 10,000 cfm which is limited by the maximum continuous output power of the motor. At this operating speed, the fan consumes 50 Watts of power, so the efficacy of the fan is 200 CFM/W. However, if a user were to desire a higher flow of air (or CFM) from the 60 inch fan, the only way to increase this is to increase the maximum rate of rotation of the fan. So, for example, under a second condition, the same 60 inch fan may be able to produce 12,500 CFM by rotating at a maximum speed of 250 rpm. However, due to diminishing returns and other motor or fan limitations, rotating that fan at a speed of 250 rpm in order to generate 12,500 CFM may require 75 W of power. Thus, the efficacy at maximum speed would only be 167 CFM/W. Additionally the motor would not be able to operate continuously at this speed due to the potential for overheating.

While a user may be satisfied with fan operation at the speed of the first condition under most circumstances, there may be instances in which an increased speed (and therefore an increased CFM) may be desired for short periods of time. This may include desiring a burst of speed to disperse stagnant air in a space, or to quickly disperse heat, pathogens, or air pollutants that may have accumulated in a space due to cooking or other heat-generating activity, or which may be present due to any number of environmental factors.

Accordingly, a need is identified to allow a user to at least temporarily operate a fan above a normally limiting maximum speed while also maintaining a desired or advertised overall energy efficiency of the fan.

SUMMARY

According to an aspect of the disclosure, a fan is provided. The fan includes a plurality of fan blades connected to a hub, a motor adapted to rotate the plurality of fan blades, and a controller adapted to operate the motor in a first mode of operation and in a second mode of operation. The first mode of operation includes a first range of speeds with a first maximum allowed speed, and the second mode of operation includes a second range of speeds with a second maximum allowed speed, different from the first maximum allowed speed.

In one aspect, the fan further includes a user interface adapted to accept an input from a user. The input may comprise a selection of the first mode or the second mode. The input may comprise a selected speed.

In one aspect, the controller is adapted to accept a selected speed from the user, wherein the controller is further adapted to limit the selected speed to within the first range of speeds when the controller is operating the motor in the first mode, and wherein the controller is further adapted to limit the selected speed to within the second range of speeds when the controller is operating the motor in the second mode.

In another aspect, the controller is adapted to automatically operate the motor in the second mode within a predetermined time period after the motor has been operated in the first mode.

In one aspect, the controller is adapted to operate the motor in the first mode for a first time period at a first efficiency and in the second mode for a second time period at a second efficiency, such that an average time-weighted efficiency over a balancing time period is equal to a predetermined standard efficiency.

According to another aspect of the disclosure, a fan is provided, which includes a plurality of fan blades connected to a hub, a motor adapted to rotate the plurality of fan blades, and a controller adapted to operate the motor in a first mode for a first time period at a first efficiency and in the second mode for a second time period at a second efficiency, such that an average time-weighted efficiency over a balancing time period is equal to a predetermined standard efficiency.

In one aspect, the first efficiency is a function of a first volumetric flow rate of air at a first maximum allowed speed, wherein the second efficiency is a function of a second volumetric flow rate of air at a second maximum allowed speed, and wherein the first maximum allowed speed is greater than the second maximum allowed speed. The controller may be adapted to automatically select the second maximum allowed speed based at least partially on the first maximum allowed speed. The controller may be adapted to automatically select the second maximum allowed speed based at least partially on the first efficiency or power consumption. The controller may be adapted to automatically select the second time period based at least partially on the first maximum allowed speed. The controller may be adapted to automatically select the second time period based at least partially on the first efficiency or power consumption.

In one aspect, the fan may include a user interface adapted to allow a user to provide a selection to the controller. The selection may be one of the first mode or the second mode. The selection may be a selected speed.

In another aspect of the disclosure, a method of controlling fan efficiency is disclosed. The method may include the steps of operating the fan at a first efficiency or power for a first period of time, and automatically operating the fan at a second efficiency or power, different from the first, for a second period of time. An average time-weighted efficiency or power consumption of the fan over a balancing time period including the first time period and the second time period is equal to a predetermined standard efficiency or power consumption.

In one aspect, the first efficiency or power is a function of a first maximum allowed speed, and wherein the second efficiency or power is a function of a second maximum allowed speed, different from the first maximum allowed speed. The second maximum allowed speed may be less than the first maximum allowed speed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fan of the present invention;

FIG. 2 is a schematic of a system for controlling the fan of FIG. 1; and

FIG. 3A-3D illustrate fan speed over time for various aspects of control of the present invention.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and like numerals represent like details in the various figures. Also, it is to be understood that other embodiments may be utilized and that process or other changes may be made without departing from the scope of the disclosure. The following detailed description is not to be taken in a limiting sense, and the scope of the invention is defined only by the appended claims and their equivalents. In accordance with the disclosure, a system and method for automatically controlling a device based on rules related to location is provided.

Turning now to FIG. 1, an exemplary fan 10 is disclosed, which has a motor assembly 20, a hub assembly 30 coupled to the motor assembly 20, and a plurality of fan blades 50 coupled to the hub assembly 30. In the present example, the fan 10 including hub assembly 30 and the fan blades 50 has a diameter of approximately 60 inches. In some versions, the fan 10 may have a smaller diameter (e.g. less than 48 inches), and in some versions the diameter may be larger (e.g. 72 inches or larger). In some instances, the fan impeller may be of a centrifugal instead of an axial style.

The motor assembly 20 may be operably coupled to the hub assembly 30 such that the motor assembly 20 rotates the hub assembly 30 relative to the motor assembly 20. It should be understood that when the fan blades 50 are coupled to the hub assembly 30, the motor assembly 20 rotates fan blades 50 with the hub assembly 30. The motor assembly 20 of the present example comprises a motor 22, as indicated in FIG. 2. The motor 22 may comprise an axial motor. In one example, the motor 22 may comprise a permanent magnet brushless DC motor having a drive shaft that is coupled to hub assembly 30, though it should be understood that the motor 22 may alternatively comprise any other suitable type of motor (e.g., an AC induction motor, a brushed motor, an inside-out motor, etc.).

By way of example only, motor assembly 20 may be constructed in accordance with at least some of the teachings of U.S. Pat. Pub. No. 2009/0208333, entitled “Ceiling Fan System with Brushless Motor,” published Aug. 20, 2009, the disclosure of which is incorporated by reference herein. Furthermore, fan 10 may include control electronics that are configured in accordance with at least some of the teachings of U.S. Pat. Pub. No. 2010/0278637, entitled “Ceiling Fan with Variable Blade Pitch and Variable Speed Control,” published Nov. 4, 2010, the disclosure of which is incorporated by reference herein. Alternatively, motor assembly 20 may have any other suitable components, configurations, functionalities, and operability, as will be apparent to those of ordinary skill in the art in view of the teachings herein.

It is to be understood that the disclosure herein may relate to a fan as illustrated, or any other sort of air moving or circulating device, with alternative motor, hub, or airfoil configurations.

With further reference to FIG. 2, the fan 10 may be associated with a controller 100. The controller 100 may be adapted to turn the fan 10 on and off, and/or may be adapted to control a speed with which the fan turns, including imposing a maximum speed at which the fan 10 may rotate.

In some instances, the controller 100 may be associated with a user input 102, which may allow a user to provide instructions or other feedback indicative of a desired speed at which the fan will rotate. The user input may be in the form of a remote control, a wall mounted control, a mobile application or other interactive program associated with a mobile device such as a phone, a tablet, or a laptop, or any other type of user interface known in the art.

The controller 100 may be adapted to provide a user with a range of available speeds at which the fan may rotate, including a maximum allowed speed, such as through the user input 102. The user may select a desired speed, which may cause the controller 100 to rotate the fan 10 at the selected speed.

With reference to FIG. 3A, an exemplary plot of maximum allowed speed (rpm) and efficacy at maximum speed (CFM/W) is shown over time for a traditional fan with a constant allowed maximum speed. In this example, the fan may be an axial fan with a diameter of 60 inches or greater. As can be seen, the fan is able to rotate at a constant maximum speed of 200 rpm, while operating with an efficacy at maximum speed of 200 CFM/W (e.g. 10,000 CFM at 50 W), either in order to be in compliance with the customer specified efficiency or due to the maximum continuous motor output. Of course, this rotational speed which results in this efficiency rating is merely exemplary in nature and would depend on any number of factors, including the aerodynamics of the fan blades and/or hub, the efficiency of the motor, etc. In other fan models, higher or lower maximum speeds may result in the same efficiency level.

In a traditional fan, a given efficiency rating would be determined a constant maximum allowed fan speed in order to deliver the volumetric flow rate of air (CFM) per unit of power (W) at the maximum allowed speed in order to deliver the specified efficacy at maximum speed of 200 CFM/W. As can be seen, this constant maximum allowed speed causes the efficiency rating to remain constant over time. Importantly, this “maximum” allowed speed is not the speed at which the fan is operated, but rather is the maximum speed that a user is allowed to operate the fan. In other words, a range of fan speeds may be offered to a user for fan operation, with the maximum allowed speed being the upper limit of that range of speeds, beyond which the user is not allowed to operate the fan.

However, it may be advantageous for a user to choose a fan speed that is higher than that maximum allowed speed of the traditional fan, at least for some abbreviated period of time. In a normal fan, such as the one whose operation is illustrated in FIG. 3A, if the fan were allowed to rotate at a maximum speed higher than the illustrated maximum speed, the efficiency could drop below the specified value or the motor could start to overheat. This is because a proportionally higher amount of additional power may be required to produce a proportionately lower additional increase in volumetric flow rate of air. In other words, the fan may operate less efficiently at speeds higher than the maximum allowed speed based on motor limitations or other requirements. In a normal fan, this would effectively prevent any ability for a user to rotate a fan at a higher speed than a default maximum allowed speed.

With the understanding that rotating at higher speeds may reduce the efficiency of the fan during such higher speed, this invention contemplates a system and method for maintaining a similar average energy consumption as the fan in the example of FIG. 3A, but with modifications which allow for temporary operation above the exemplary 200 rpm, or the default maximum allowed speed. This is accomplished by allowing for dynamic adjustment of maximum allowed speed in a way such that an average efficiency of the fan over a period of time remains at or above the specified or advertised efficiency. This dynamic maximum allowed speed control is illustrated in FIG. 3B-3D. For the purposes of a fan which is allowed to operate with dynamic adjustment of maximum allowed speed, the efficiency at any given time is measured as the efficacy at the maximum allowed speed at that given time.

With reference to FIG. 3B, a user may wish to operate the fan at a first speed higher than the default maximum allowed speed of 200 rpm for a certain period of time. For example, the user may wish to operate the fan at 250 rpm for a short amount of time, such as in order to quickly clear or disperse the air in which the fan is located. This higher speed may yield a higher flow rate (e.g. 12,500 cfm), but also at a higher power draw (e.g. 75 W). Thus, operation of the fan at a first raised maximum allowed speed of 250 rpm results in a reduction in efficiency and potentially overheating of the motor. A raised maximum allowed speed simply means a maximum allowed speed that is above the default maximum allowed speed. And for the purposes of this disclosure, the time during which the fan may be allowed to operate at a raised maximum allowed speed may be referred to as “burst mode.” In the illustrated example of FIG. 3B, this burst mode results in a lower efficacy at this first raised maximum speed of only 167 CFM/W.

However, allowing the fan to operate in burst mode at all times would clearly result in a fan that either does not comply with a specified efficiency (i.e. 200 CFM/W) or will cause the motor to overheat and fail. Thus, in an effort to maintain overall efficiency and product life, the current disclosure contemplates, at a time after burst mode, the fan may be restricted in operation such that it is not allowed to rotate at any higher than a first reduced maximum allowed speed. A reduced maximum allowed speed simply means a maximum allowed speed that is below the default maximum allowed speed. By restricting use of the fan to this first reduced maximum allowed speed may result in a reduced loading of the motor and an increased efficiency, above the published efficiency. For example, as shown in the illustrated example of FIG. 3B, the fan may be restricted to a first reduced maximum allowed speed of 100 rpm, which may result in a reduced air flow rate (e.g. 5,000 cfm), but also at a lower power requirement (e.g. 15 W), and thus an increased efficiency of 333 CFM/W. For the purposes of this disclosure, the time during which the fan may be restricted in operation so as to have a reduced maximum allowed speed may be referred to as “eco mode.”

Collectively, allowing the maximum allowed speed to vary over time, such as allowing a fan to operate in burst mode and eco mode may be referred to as operating the fan in a dynamic mode.

Such eco mode may be imposed for at least a time period until the decreased efficiency or power consumption resulting from the burst mode is balanced out by the increased efficiency and reduced power consumption resulting from eco mode. Thus, an average efficiency or power consumption over time, considering the decreased efficiency during burst mode and the increased efficiency of eco mode (along with any operation of the fan in a default mode at the default maximum allowed speed) over a given period of time must result in an at least equal overall performance be it efficiency or power consumption. This may be calculated by integrating the curve of efficiency or power over time. The area under the curve created by a fan in dynamic mode over a given period of time (e.g. the operation as illustrated in FIG. 3B) should equal the area under the curve created by a fan operating in default mode over the same period of time (e.g. the operation as illustrated in FIG. 3A). Stated another way, over a given period of time, the average time-weighted efficiency or power in dynamic mode must equal the efficiency or power in default mode. In one instance, this period of time may be one calendar day. In another instance, this period of time may be a 24 hour period starting at the beginning of burst mode.

For the purposes of this disclosure, the term “average time-weighted efficiency” means the average of all efficiencies per unit time the fan is operated at such efficiencies. For example, with reference to FIG. 3B, the efficiency at time intervals 1-2 is 167 CFM/W, the efficiency at time interval 3 is 200 CFM/W, the efficiency at time intervals 4-5 is 333 CFM/W, and the efficiency at time intervals 6-24 is 200 CFM/W. This results in an average time-weighted efficiency of ((23×167)+(1×200)+(2×333)+(19×200))/24=208 CFM/W. The power consumed over 24 hours would be 24h×50W=1200 Wh and in dynamic mode the power consumed over 24 hours would be (2×75)+(1×50)+(2×15)+(19×50)=1180Wh. In this way, the total energy used by the fan in dynamic mode is not allowed to exceed the total energy used in default mode. The time intervals could be any unit of time, including seconds, minutes, or hours.

In some instances, it may be desirable to restrict the fan speed less severely than the example of FIG. 3B so that the fan is still able to have a higher volumetric flow rate during eco mode than in the previously illustrated embodiment. In order to arrive at the same result of an average time-weighted efficiency matching (or exceeding) that of the default mode, this will require that the fan remain in eco mode for a longer period of time than the previous example. In other words, as illustrated in FIG. 3C, a second reduced maximum allowed fan speed in eco mode may be 150 rpm (instead of 100 rpm), but the time required for the fan to remain in this eco mode may increase. This may result in the fan generating 7,500 cfm, using 33 W of power, thus resulting in an efficiency of 227 CFM/W during eco mode. This would require 3 time intervals in eco mode, as opposed to the 2 time intervals required in the previous embodiment, in order to achieve an average time-weighted efficiency in dynamic mode (i.e. 200.6 CFM/W) to not fall below the efficiency in default mode (i.e. 200 CFM/W), and in order for the power consumption over a 24 hour period in dynamic mode (i.e. 1199 Wh) to be no greater than the power consumption in default mode (i.e. 1200 Wh).

It is not necessary that the time intervals required in eco mode to balance out the reduced efficiency of burst mode must be consecutive. Rather, the number of time intervals required for the fan to be in eco mode in order to balance out the reduced efficiency of burst mode may be spread throughout the relevant given period of time period for calculations. This relevant given period of time may be referred to as a “balancing time period,” as it is the time period by which any reduced efficiency from burst mode must be balanced with an increased efficiency in eco mode in order to create an average time-weighted efficiency equal to that of the default mode. For example, the balancing time period may be a calendar day or a 24 hour period starting at the time the burst mode is initiated.

Such embodiment is illustrated in FIG. 3D. In this example, the fan is operated at a second raised maximum allowed speed (which is higher than the first raised maximum allowed speed of the examples of FIGS. 3B and 3C), namely 300 rpm. This may allow for a burst mode that creates a larger volumetric flow rate of air (e.g. 15,000 cfm) than in the examples of the first raised maximum allowed speed. However, this higher, second raised maximum allowed speed requires additional power (e.g. 115 W) and results in an even lower efficiency than in the previous examples (i.e. 130 CFM/W), which occurs in the example of FIG. 3D for two time intervals. Thus, in order to balance out this reduced efficiency, the fan may be run in eco mode limiting the fan to a third reduced maximum allowed fan speed of 140 rpm (which may generate 7,000 cfm while requiring 30 W to do so), resulting in an efficiency of 233 CFM/W, for a total of seven time intervals in order to create an average time-weighted efficiency (i.e. 204 CFM/W) equal or higher to that of default mode (i.e. 200 CFM/W) and a daily power consumption (i.e. 1190 Wh) equal or lower than default mode (i.e. 1200 Wh). As shown in FIG. 3D, these seven time intervals need not be consecutive, so long as they all occur within the balancing time period (illustrated as 24 time intervals).

It should be understood that the precise values of the number of time intervals, maximum allowed fan speeds, and efficiencies may vary, so long as the average time-weighted efficiency and/or power consumption of the fan in dynamic mode is equal to or greater than the average time-weighted efficiency and/or power consumption of the fan in default mode.

Turning back to FIGS. 1 and 2, the controller 100 may be adapted to normally operate the fan in default mode. During default mode, the user may select any fan speed up to an including the default maximum allowed speed. This results in an efficiency meeting or exceeding the standard efficiency or energy use.

The user interface 102 may also provide a user with an option to select to operate the fan in dynamic mode. This may first allow the user to select operation of the fan in burst mode, such as from the user interface 102. The controller 100 may be adapted to limit the parameters of fan operation during burst mode. For example, the controller 100 may restrict the user to select a raised maximum allowed fan speed of no greater than an upper limit. For example, this upper limit may be 110%, 125%, 150%, 200%, or more, than the default maximum allowed fan speed. This upper limit may be determined by an upper limit of the motor's speed capabilities, by a predetermined lower limit on the resulting efficacy at that raised maximum allowed fan speed, or both.

The controller 100 may also limit a time for which the fan may operate in burst mode. For example, the controller may limit burst mode to 1 minute, 5 minutes, 10 minutes, or more. In some instances, the controller may limit the time that the fan may be in burst mode to a certain total time within the balancing time period. In other instances, the controller may limit the time that the fan may be in burst mode to a total consecutive number of time intervals (e.g. no more than 1 minute at a time, but may allow a total of 5 minutes per 24 hour period).

If the controller allows the user to operate the fan in burst mode, then the controller must also cause the fan to operate in eco mode during the balancing time period. During eco mode, the controller may limit the maximum allowed speed at which a user may select to operate the fan to some speed lower than the default maximum allowed speed. The value of the reduced maximum allowed speed during eco mode and the time period during which eco mode must be imposed during the balancing time period may vary, but in any case, must cause the average time-weighted efficiency of the fan during the balancing time period during dynamic mode to equal the efficiency or power consumption of the fan during default mode. The controller may vary the value of the reduced maximum allowed fan speed and duration of operation in eco mode in accordance with the various descriptions herein in order to cause the average time-weighted efficiency of the fan in dynamic mode to equal the efficiency of the fan in default mode.

In a further aspect of the disclosure, the system may include a sensor for sensing an environmental condition near the fan, such as in the same room as the fan, within the same building as the fan, or within a certain distance of the fan. The sensor may be connected to or in communication with the fan or the controller. The sensor may be adapted to sense a level of gas within the air (e.g. carbon dioxide, carbon monoxide, or oxygen), a particulate level in the air, or a level of a pathogen or other toxic or undesirable compound within the air. In a non-limiting example, the sensor may be any of a CO₂ sensor, a smoke detector, or other particulate matter sensor. In some instances, a plurality of such sensors may be provided.

The controller may be further adapted to automatically cause the fan to enter burst mode when a value measured by the sensor exceeds (or drops below) a threshold value. The threshold value may be a pre-programmed value stored within a memory accessible to or part of the controller, may be programmed or entered by a user, may be a value measured by a second or a remote sensor, or may be based on an average measured value of the given parameter over time (or a factor of that average measured value).

In one instance, in the case of a CO₂ sensor, if the value measured by the sensor rises above a threshold value, the controller may automatically cause the fan to enter burst mode to quickly disperse the CO₂ in the air.

In another instance, in the case of an oxygen sensor, if the value measured by the sensor falls below a threshold value, the controller may cause the fan to automatically enter burst mode to quickly replenish oxygen on the area.

In a further instance, in the case of a particulate sensor, if the value measured by the sensor rises above a threshold value, the controller may automatically cause the fan to enter burst mode to quickly disperse the particulates from the area. Such may be particularly useful in the case of an exhaust fan, which may automatically enter burst mode to quickly evacuate particulates or smoke from an area.

Summarizing, this disclosure may be considered to relate to the following items:

• • 1. A fan comprising:
  • a plurality of fan blades connected to a hub;
  • a motor adapted to rotate the plurality of fan blades; and
  • a controller adapted to operate the motor in a first mode of operation and in a second mode of operation, wherein the first mode of operation includes a first range of speeds with a first maximum allowed speed, wherein the second mode of operation includes a second range of speeds with a second maximum allowed speed, different from the first maximum allowed speed.
  • 2. The fan of item 1, further including a user interface adapted to accept an input from a user.
  • 3. The fan of item 2, wherein the input comprises a selection of the first mode or the second mode.
  • 4. The fan of any of the above items, wherein the input comprises a selected speed.
  • 5. The fan of any of the above items, wherein the controller is adapted to accept a selected speed from the user, wherein the controller is further adapted to limit the selected speed to within the first range of speeds when the controller is operating the motor in the first mode, and wherein the controller is further adapted to limit the selected speed to within the second range of speeds when the controller is operating the motor in the second mode.
  • 6. The fan of any of the above items, wherein the controller is adapted to automatically operate the motor in the second mode within a predetermined time period after the motor has been operated in the first mode.
  • 7. The fan of any of the above items, wherein the controller is adapted to operate the motor in the first mode for a first time period at a first efficiency and in the second mode for a second time period at a second efficiency, such that an average time-weighted efficiency over a balancing time period is equal to a predetermined standard efficiency.
  • 8. A fan comprising:
  • a plurality of fan blades connected to a hub;
  • a motor adapted to rotate the plurality of fan blades; and
  • a controller adapted to operate the motor in a first mode for a first time period at a first efficiency and in the second mode for a second time period at a second efficiency, such that an average time-weighted efficiency over a balancing time period is equal to a predetermined standard efficiency.
  • 9. The fan of item 8, wherein the first efficiency is a function of a first volumetric flow rate of air at a first maximum allowed speed, wherein the second efficiency is a function of a second volumetric flow rate of air at a second maximum allowed speed, and wherein the first maximum allowed speed is greater than the second maximum allowed speed.
  • 10. The fan of item 9, wherein the controller is further adapted to automatically select the second maximum allowed speed based at least partially on the first maximum allowed speed.
  • 11. The fan of any of items 9-10, wherein the controller is further adapted to automatically select the second maximum allowed speed based at least partially on the first efficiency or power consumption.
  • 12. The fan of any of items 9-11, wherein the controller is further adapted to automatically select the second time period based at least partially on the first maximum allowed speed.
  • 13. The fan of any of items 9-12, wherein the controller is further adapted to automatically select the second time period based at least partially on the first efficiency or power consumption.
  • 14. The fan of any of items 8-13, further including a user interface adapted to allow a user to provide a selection to the controller.
  • 15. The fan of item 14, wherein the selection is one of the first mode or the second mode.
  • 16. The fan of item 14 or 15, wherein the selection is a selected speed.
  • 17. A method of controlling fan efficiency comprising:
  • operating the fan at a first efficiency or power for a first period of time; and
  • automatically operating the fan at a second efficiency or power, different from the first, for a second period of time;
  • wherein an average time-weighted efficiency or power consumption of the fan over a balancing time period including the first time period and the second time period is equal to a predetermined standard efficiency or power consumption.
  • 18. The method of item 17, wherein the first efficiency or power is a function of a first maximum allowed speed, and wherein the second efficiency or power is a function of a second maximum allowed speed, different from the first maximum allowed speed.
  • 19. The method of item 18, wherein the second maximum allowed speed is less than the first maximum allowed speed.

Each of the following terms written in singular grammatical form: “a”, “an”, and the”, as used herein, means “at least one”, or “one or more”. Use of the phrase “One or more” herein does not alter this intended meaning of “a”, “an”, or “the”. Accordingly, the terms “a”, “an”, and “the”, as used herein, may also refer to, and encompass, a plurality of the stated entity or object, unless otherwise specifically defined or stated herein, or the context clearly dictates otherwise. For example, the phrases: “a unit”, “a device”, “an assembly”, “a mechanism”, “a component, “an element”, and “a step or procedure”, as used herein, may also refer to, and encompass, a plurality of units, a plurality of devices, a plurality of assemblies, a plurality of mechanisms, a plurality of components, a plurality of elements, and, a plurality of steps or procedures, respectively.

Each of the following terms: “includes”, “including”, “has”, “having”, “comprises”, and “comprising”, and, their linguistic/grammatical variants, derivatives, or/and conjugates, as used herein, means “including, but not limited to”, and is to be taken as specifying the stated components), feature(s), characteristic(s), parameter(s), integer(s), or step(s), and does not preclude addition of one or more additional component(s), feature(s), characteristic(s), parameter(s), integer(s), step(s), or groups thereof. Each of these terms is considered equivalent in meaning to the phrase “consisting essentially of.” Each of the phrases “consisting of” and “consists of, as used herein, means “including and limited to”. The phrase “consisting essentially of” means that the stated entity or item (system, system unit, system sub-unit device, assembly, sub-assembly, mechanism, structure, component element or, peripheral equipment utility, accessory, or material, method or process, step or procedure, sub-step or sub-procedure), which is an entirety or part of an exemplary embodiment of the disclosed invention, or/and which is used for implementing an exemplary embodiment of the disclosed invention, may include at least one additional feature or characteristic” being a system unit system sub-unit device, assembly, sub-assembly, mechanism, structure, component or element or, peripheral equipment utility, accessory, or material, step or procedure, sub-step or sub-procedure), but only if each such additional feature or characteristic” does not materially alter the basic novel and inventive characteristics or special technical features, of the claimed item.

Terms of approximation, such as the terms about, substantially, approximately, generally, etc., as used herein, refer to ±10 % of the stated numerical value or as close as possible to a stated condition.

It is to be fully understood that certain aspects, characteristics, and features, of the invention, which are, for clarity, illustratively described and presented in the context or format of a plurality of separate embodiments, may also be illustratively described and presented in any suitable combination or sub-combination in the context or format of a single embodiment. Conversely, various aspects, characteristics, and features, of the invention which are illustratively described and presented in combination or sub-combination in the context or format of a single embodiment may also be illustratively described and presented in the context or format of a plurality of separate embodiments.

Although the invention has been illustratively described and presented by way of specific exemplary embodiments, and examples thereof, it is evident that many alternatives, modifications, or/and variations, thereof, will be apparent to those skilled in the art. Accordingly, it is intended that all such alternatives, modifications, or/and variations, fall within the spirit of, and are encompassed by, the broad scope of the appended claims.