Abstract:
A method of controlling a temperature of one or more zones using a fan. In one embodiment, the method includes inputting a temperature set point and a temperature control band for the one or more zones, initializing the fan to operate at a first speed setting, and determining a relationship between the temperature of the one or more zones, the temperature set point, and the temperature control band. The method also includes modulating a speed of the fan between the first speed setting and at least one second speed setting based at least partially on the determined relationship.

Description:
RELATED APPLICATION  
       [0001]     This application claims priority to U.S. Provisional Patent Application Ser. No. 60/727,812, filed on Oct. 18, 2005, the entire contents of which are incorporated herein by reference. 
     
    
     FIELD  
       [0002]     Embodiments of the invention relate generally to temperature control systems and methods.  
       BACKGROUND  
       [0003]     Fan coil units are often used to control indoor air temperatures. Generally, a fan coil unit includes a water or direct expansion coil, a fan, and ductwork to distribute the air. In some instances, significant energy costs are incurred by fan coil units due to inadequate controls. Additionally, without proper control, air temperatures may not be able to be maintained effectively.  
       SUMMARY  
       [0004]     In one embodiment, a method of controlling a temperature of one or more zones using a fan includes inputting a temperature set point for the one or more zones and inputting a temperature control band for the one or more zones. The temperature control band represents an acceptable temperature variation of the one or more zones. The method also includes initializing the fan to operate at a first speed setting, determining a relationship between the temperature of the one or more zones, the temperature set point, and the temperature control band, and modulating a speed of the fan between the first speed setting and a second speed setting based at least partially on the determined relationship. The first speed setting is less than the second speed setting. The fan speed is set to the second speed setting as the temperature of the one or more zones exceeds a sum of the temperature set point and at least a portion of the temperature control band. The fan speed is set to the first speed setting as the temperature of the one or more zones approaches the temperature set point.  
         [0005]     In another embodiment, a fan control system configured to control a fan and an air temperature control mechanism for controlling a temperature of one or more zones, includes an input module, a fan speed control module, and an air temperature control module. The input module receives a signal from a temperature sensor which generates a signal indicative of the temperature of the one or more zones; receives a signal from a temperature selection device which allows a user to select a temperature set point for the one or more zones; and stores a control band parameter representing an acceptable temperature variation of the one or more zones. The fan speed control module modulates the fan speed between a first speed setting and a second speed setting, the second speed setting being greater than the first speed setting. The fan speed control module initially operates the fan to the first speed setting, switches the fan speed to the second speed setting upon the temperature of the one or more zones exceeding the sum of the temperature set point and the control band parameter, and switches back to the first speed setting upon the temperature of the one or more zones returning to the sum of the temperature set point and the control band parameter. The air temperature control module modulates the temperature of the air temperature control mechanism to maintain the temperature of the one or more zones at approximately the temperature set point.  
         [0006]     In another embodiment, a method of programming a temperature control system controller for controlling the temperature of one or more zones includes programming a first temperature control loop and a second temperature control loop. The first control loop initially operates a fan at a first speed setting, increases the fan speed to a second speed setting upon the temperature of the zone exceeding a sum of a temperature set point and at least a portion of a temperature control band, and decreases the fan speed to the first speed setting upon the temperature of the one or more zones returning to the temperature set point. The second temperature control loop maintains the temperature of the one or more zones at the temperature set point by decreasing the temperature of the air temperature control mechanism upon the temperature of the one or more zones exceeding a sum of the temperature set point and at least a portion of the control band, and increasing the temperature of the air temperature control mechanism upon the temperature of the one or more zones returning to the temperature set point.  
         [0007]     Embodiments herein can be implemented in new control systems or retrofitted into existing systems. Further, embodiments can be useful in a host of temperature-controlled environments, such as, for example, industrial production facilities, medical buildings, manufacturing assemblies, laboratories, and ships.  
         [0008]     Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a schematic diagram of a portion of a multi-speed fan coil unit (“FCU”) according to an embodiment of the invention.  
         [0010]      FIG. 2  is a block diagram of a controller according to an embodiment of the invention.  
         [0011]      FIG. 3  illustrates a process for controlling a two-speed fan according to an embodiment of the invention.  
         [0012]      FIG. 4  illustrates a process for controlling a three-speed fan according to an embodiment of the invention.  
         [0013]      FIG. 5  illustrates a process for controlling an air temperature control mechanism according to an embodiment of the invention.  
         [0014]      FIG. 6  illustrates a process for controlling a fan according to an embodiment of the invention.  
         [0015]      FIG. 7  illustrates a process for controlling an air temperature control mechanism according to an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0016]     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.  
         [0017]     As should also be apparent to one of ordinary skill in the art, the systems shown in the figures are models of what actual systems might be like. Many of the modules and logical structures described are capable of being implemented in software executed by a microprocessor or a similar device or of being implemented in hardware using a variety of components including, for example, application-specific integrated circuits (“ASICs”). Terms like “controller” may include or refer to both hardware and/or software. Furthermore, throughout the specification, capitalized terms are used. Such terms are used to conform to common practices and to help correlate the description with the coding examples, equations, and/or drawings. However, no specific meaning is implied or should be inferred simply due to the use of capitalization. Thus, the claims should not be limited to the specific examples or terminology or to any specific hardware or software implementation or combination of software or hardware.  
         [0018]      FIG. 1  illustrates a portion of a multi-speed fan coil unit (“FCU”)  100  having a multi-speed fan  105 , a coil  110 , a valve  115 , a temperature sensor  120 , and a controller  125 . In other embodiments, the FCU  100  may have more or fewer components than those shown in  FIG. 1 . For example, in an alternative embodiment, the FCU  100  includes two coils  110  and two valves  115 . Other variations are possible. As shown in  FIG. 1 , air flows through the fan  105  and past the coil  110 .  
         [0019]     The multi-speed fan  105  of the FCU  100  supplies airflow to the one or more zones that the FCU services. In one embodiment, this is accomplished using a series of fan blades, as known in the art. As such, the size, operating speed, and capacity of the fan  105  may vary according to the application. In some embodiments, the coil  110  is a water or direct expansion coil that is used to cool the airflow passing over the coil  110 . In other embodiments, the coil  110  can be used to heat the air passing over the coil  110 . The valve  115  controls the amount of water or other liquid that is supplied to the coil  110 . Accordingly, the valve  115  can effectively control the temperature of the coil  110 . For example, in one embodiment, if the valve  115  is in a completely closed position, little or no liquid is supplied to the coil  110 , and the coil  110  is allowed to attain room temperature. Alternatively, if the valve  115  is in a fully open position, a maximum amount of liquid is supplied to the coil  110 , and maximum cooling is attained. The valve  115  transmits and receives signals from the controller  125 , as described in greater detail below. The temperature sensor  120  measures the temperature of the zone to which the FCU  100  is supplying airflow. In some embodiments, the temperature sensor  120  is a stand-alone thermometer that transmits a signal indicative of the zone temperature to the controller  125 . In other embodiments, the temperature sensor  120  is integrated into or coupled to the controller  125 , for example, forming a single control and sensing unit (e.g., a thermostat device).  
         [0020]     Generally, the controller  125  can be a variety of suitable electronic devices, such as, for example, one or more integrated circuits (“ICs”), a microcomputer, a programmable logic controller (“PLC”), and/or other computing device. As such, the controller  125  may include both hardware and software components, and is meant to broadly encompass the combination of such components. In the embodiment shown in  FIG. 1 , the controller  125  receives signals from the fan  105 , the valve  115 , and the temperature sensor  120 , and transmits signals to the fan  105  and valve  115 . In some embodiments, the signals received by the controller  125  are used to generate the signals that are transmitted from the controller  125 . For example, as described in greater detail below, the controller  125  may receive a temperature signal from the temperature sensor  120 , and use that signal to generate a speed control signal that is transmitted to the fan  105 . Additionally, in other embodiments, the controller  125  may be in communication with other components of the FCU  100  (e.g., other controllers, fans, temperature sensors, etc.).  
         [0021]      FIG. 2  is a block diagram of the controller  125  of  FIG. 1 . In the embodiment shown in  FIG. 2 , the controller  125  includes an input module  200 , a fan speed control module  205 , and a temperature control module  210  having a cooling control module  215  and a heating control module  220 . In other embodiments, the controller  125  may include a variety of other processing and/or memory modules, as should be apparent to one of ordinary skill in the art.  
         [0022]     Generally, the input module  200  receives signals from components of the FCU  100 , which signals can then be used by the other modules. In some embodiments, the input module  200  also stores certain parameters that are used by the other modules. For example, in one embodiment, the input module  200  receives, from the temperature sensor  120 , a signal indicative of the temperature of the zone to which the FCU  100  is supplying airflow. The input module  200  also receives a signal from a temperature selection device (e.g., a thermostat), which allows a user to select a temperature set point, or desired temperature, of the zone. Additionally, a user can store a control band parameter in the input module  200  that represents an acceptable temperature variation of the one or more zones. In other embodiments, the input module  200  also receives a signal from the fan  105  that is indicative of fan speed, and a signal from the valve  115  that is indicative of valve position.  
         [0023]     The fan speed control module  205  controls the speed at which the fan  105  operates. In some embodiments, the fan speed control module  205  stores a set of rules or processes (e.g., the processes described with respect to  FIGS. 3-7 ) that can be used to determine a proper fan speed setting. After determining the proper fan speed, the fan speed control module  205  can transmit a control signal to the fan  105 . Generally, the fan speed control module  205  modulates the fan speed between a first speed setting and one or more other speed settings, in order to maintain the lowest fan speed possible while maintaining the zone temperature set point.  
         [0024]     The temperature control module  210  modulates the temperature of the coil  110 . More specifically, the temperature control module  210  modulates the temperature of the coil  110  by modulating the position of the valve  115 . In some embodiments, cold and hot controls may be separated, such that the cooling control module  215  is used to control the flow of cold liquid through the coil  110 , and the heating control module  220  is used to control the flow of hot liquid through the coil  110 . In other embodiments, the cooling control module  215  and the heating control module  220  are not separated. Similar to the fan speed control module  205 , in some embodiments, the temperature control module  210  stores one or more sets of rules or processes (e.g., the processes described with respect to  FIGS. 3-7 ) that can be used to determine the proper valve position. After determining the proper valve position, the temperature control module  210  transmits a control signal to the valve  115  to adjust the valve position. Generally, the temperature control module  210  modulates the temperature of the coil  110  to maintain the temperature of the one or more zones at approximately the temperature set point. In some embodiments, the temperature control module  210  and the fan speed control module  205  operate in conjunction with each other, such that the calculations completed by the temperature control module  210  can be utilized by the fan speed control module  205 , and vice versa.  
         [0025]      FIGS. 3-7  illustrate a variety of processes that can be implemented to control certain functions of an FCU to provide conditioned air to one or more zones. By way of example only, the processes shown in  FIGS. 3-7  are described as being carried out by the FCU  100 , shown in  FIG. 1 . However, as should be apparent to one of ordinary skill in the art, the processes shown in  FIGS. 3-7  are capable of being implemented by a variety of FCUs. For example, in each of the processes shown in  FIGS. 3-7 , multiple parameters are described as being input into the controller  125 . However, in other embodiments, an alternative controller of an alternative FCU may be used. Further, the specific multipliers (e.g., fractions) set forth in connection with the temperature control band are merely examples.  
         [0026]      FIG. 3  illustrates a process  300  for controlling a two-speed fan. The process  300  begins by inputting a variety of parameters into the controller  125  (step  305 ). In some embodiments, parameters are input by a user into the controller  125  using an input device, such as, for example, a thermostat. In other embodiments, the parameters may be programmed into the controller  125 , for example, into a memory of the controller  125 . In the embodiment shown in  FIG. 3 , a fan start/stop command, a zone temperature set point (“T RSP ”), a zone temperature (“T R ”), a cooling/heating mode, and a temperature control band (“ΔT”) are inputs to the controller  125 . The fan start/stop command, zone temperature set point, and cooling/heating mode are input into the controller  125  by a user using a thermostat device. The zone temperature signal is provided to the controller  125  by the temperature sensor  120 . The temperature control band, which represents an acceptable temperature variation of the one or more zones, is programmed and stored within the controller  125 .  
         [0027]     After providing the necessary inputs, the next step in the process  300  is to check if a fan command is on (step  310 ). As described above, the fan start/stop command can be input by a user with an input device such as a thermostat. In another embodiment, the fan start/stop command may be automatically controlled by the controller  125 . For example, if the temperature of the zone that is being conditioned falls below a predetermined temperature, the fan command can be automatically initialized. If the fan command is not on, the fan  105  is turned off (step  315 ). If the fan command is on, the fan  105  is initialized to run at the slow speed setting (step  320 ). After the fan  105  has been initialized and is running at the slow setting, the mode (e.g., heating mode or cooling mode) is determined (step  325 ). In one embodiment, the heating or cooling mode is selected automatically by the controller  125  according to the temperature of the zone. For example, if the zone temperature is above the zone temperature set point, the controller  125  automatically selects the cooling mode. Similarly, if the zone temperature is below the zone temperature set point, the controller  125  automatically selects the heating mode. In other embodiments, a user may be able to manually select the heating or cooling mode using an input device. If the controller  125  is not in the cooling mode, the process  300  returns to step  320 , and the fan  105  continues to run at slow speed. If the controller  125  is in the cooling mode, the next step in the process  300  is to check whether the zone temperature is greater than or equal to the combination or sum of the zone temperature set point and a control band. In some embodiments, the zone temperature set point is approximately 72 to 74 degrees Fahrenheit and the control band is approximately ±1 degree Fahrenheit. In other embodiments, however, the zone temperature set point and control band may be set to other values. For example, in one embodiment, a user can select the zone temperature set point using a thermostat device.  
         [0028]     If the zone temperature is less than the sum of the temperature set point and the control band, the process  300  returns to step  320 , and the fan  105  continues to run at the slow speed setting. If, however, the zone temperature is greater than or equal to the sum of the temperature set point and the control band, the fan speed is increased to a higher speed setting (step  335 ). The higher speed setting supplies the zone that the FCU  105  is conditioning with a greater amount of cooled air, thereby increasing the speed at which the zone is cooled. After switching to the higher speed setting, the process continues by checking whether the zone temperature is less than or equal to the zone temperature set point (step  340 ). If the zone temperature has not reached the zone temperature set point, the process  300  returns to step  335 , and the fan  105  continues to operate at the higher speed setting. Upon the zone temperature reaching the zone temperature set point, the process  300  returns to step  310 , and the fan  105  returns to operating at a slower speed setting. The process  300  continues to be evaluated until the fan command is turned off.  
         [0029]      FIG. 4  illustrates a process  400  for controlling a three-speed fan. The first steps of the process  400  are similar to those shown in  FIG. 3 . For example, the first step of the process is to input the fan start/stop command, the zone temperature set point, the zone temperature, the cooling/heating mode, and the temperature control band (step  405 ). The next step of the process  400  is to check if the fan command is on (step  410 ), and if the fan command is not on, to turn the fan off (step  415 ). If the fan command is on, the fan begins to operate at a slow speed setting (step  420 ), and the mode is determined (step  425 ). If the cooling mode is not selected, the process returns to step  420 , and the fan remains at the slow speed setting. If the cooling mode is selected, the controller  125  checks if the zone temperature is greater than or equal to the sum of the zone temperature set point and one quarter of the control band (step  430 ). If the zone temperature has not met or exceeded the sum of the zone temperature set point and one quarter of the control band, the process  400  returns to step  420 , and the fan continues to operate at the slow speed setting. If, however, the zone temperature has met or exceeded the sum of the zone temperature set point and one quarter of the control band, the controller  125  checks if the zone temperature is less than or equal to the sum of the zone temperature set point and three quarters of the control band (step  435 ). If the zone temperature has exceeded the sum of the zone temperature set point and three quarters of the control band, the fan speed is increased to operate at the highest speed setting (step  440 ), and remains at the highest speed setting until the zone temperature is less than or equal to the sum of the zone temperature set point and one half of the control band (step  445 ). Upon the temperature falling to the sum of the zone temperature set point and one half of the control band, the fan speed is decreased to the middle or medium speed setting (step  450 ).  
         [0030]     Returning to step  435 , if the temperature of the zone is greater than or equal to the sum of the zone temperature set point and one quarter of the control band (step  430 ), but less than or equal to the sum of the zone temperature set point and three quarters of the control band (step  435 ), the fan speed is increased to the middle speed setting (step  450 ), and remains at the medium speed setting until the zone temperature is less than or equal to the zone temperature set point (step  455 ). Upon the temperature falling to the zone temperature set point, the process  400  returns to step  410 , and the speed of the fan is reduced to the slowest speed setting. The process  400  continues to be evaluated until the fan command is turned off.  
         [0031]      FIG. 5  illustrates a process  500  for controlling an air temperature control mechanism, such as, for example, the coil  110 . More specifically, the process  500  is used to control the valve  115  that controls the temperature of the coil  110 . In some embodiments, the process  500  is completed concurrently with the processes shown in  FIGS. 3-4 , such that the speed of the fan  105  and the temperature of the coil  110  are modulated concurrently. In other embodiments, the control valve  115  may be controlled completely independently of the fan  105 . Similar to the processes shown in  FIGS. 3-4 , the first step of the process  500  is to input the fan start/stop command, the zone temperature set point, the zone temperature, the cooling/heating mode, and the temperature control band (step  505 ). The next step of the process  500  is to check if the fan command is on (step  510 ). If the fan command is not on, the control valve is closed completely (step  515 ). In some embodiments, closing the control valve completely allows the coil  110  to warm to room temperature (i.e., the coil  110  does not provide any cooling). If the fan command is on, the mode is determined by first checking if the cooling mode has been activated (step  515 ). If the cooling mode is not activated, the controller  125  determines if the heating mode has been activated (step  520 ). If neither the heating mode nor the cooling mode is activated, the valve  115  is fully closed (step  515 ).  
         [0032]     If the cooling mode is activated (step  515 ), the controller  125  checks if the zone temperature is greater than or equal to the zone temperature set point less the control band (step  525 ). If the zone temperature is less than the zone temperature set point less the control band, the valve  115  is fully closed (step  515 ). If, however, the zone temperature is greater than or equal to the zone temperature set point less the control band, the controller  125  checks if the zone temperature is greater than the zone temperature set point (step  530 ). If the zone temperature is less than or equal to the zone temperature set point, the position of the valve is modulated to maintain the zone temperature set point within the zone (step  535 ). This position modulation can be accomplished using a variety of methods including, for example, a proportional integral (“PI”) control loop. If the zone temperature is greater than the zone temperature set point, the valve  115  is opened completely (step  540 ) to attain the greatest potential cooling.  
         [0033]     If the heating mode is activated (step  520 ), the controller  125  checks if the zone temperature is less than the zone temperature set point less the control band (step  545 ). Additionally, if the heating mode is activated, the coil  110  may be operated such that air passing over the coil  110  is heated. For example, upon activation of the heating mode, hot liquid, such as water, can be passed through the coil  110  so that the coil  110  substantially heats the air. In another embodiment, the FCU  100  can include two separate coils, with one coil being activated with the cooling mode and the other coil being activated with the heating mode. If the zone temperature is greater than or equal to the zone temperature set point less the control band, the valve  115  is closed completely (step  515 ). If, however, the zone temperature is less than the zone temperature set point less the control band, the valve  115  is modulated to maintain the zone temperature set point (step  550 ). As described with respect to the cooling mode above, the valve  115  can be modulated according to a PI control loop or other suitable control scheme. The process  500  continues by checking if the zone temperature is greater than the zone temperature set point (step  555 ). If the zone temperature is less than or equal to the zone temperature set point, the process  500  returns to step  550 , and the valve  115  continues to be modulated to maintain the zone temperature set point. If the zone temperature is greater than the zone temperature set point, the valve is closed (step  515 ). Upon completion, the process  500  can be repeated as needed to control the temperature of the zone.  
         [0034]      FIG. 6  illustrates a process  600  for controlling a fan and an air temperature control mechanism. The embodiment shown in  FIG. 6  is similar to that shown in  FIG. 3 . The first step of the process  600  is to input the fan start/stop command, the zone temperature set point, the zone temperature, the cooling/heating mode, the temperature control band, and a valve position (step  605 ). Steps  610 - 635  are essentially the same as steps  310 - 335  and will not be specifically addressed in regard to  FIG. 6 . After operating the fan at the high speed setting (step  635 ), the controller  125  checks if the zone temperature is less than or equal to the zone temperature set point less the control band (step  640 ). If the zone temperature is greater than the zone temperature set point less the control band, the process  600  returns to step  635 , and the fan continues to operate at the high speed setting. If the zone temperature is less than or equal to the zone temperature set point less the control band, the controller  125  checks if the control valve position is less than 60 percent of the completely open position (step  645 ). If the control valve is not positioned less than 60 percent of the completely open condition, the process  600  returns to step  635 , and the fan continues to operate at the high speed setting. If the position of the control valve is less than  60  percent of the completely open position, the process  600  returns to step  610 , and the fan speed is slowed to the low speed setting (step  620 ) provided that the fan command is on. The process  600  continues to be evaluated until the fan command is turned off.  
         [0035]      FIG. 7  illustrates another process  700  for controlling an air temperature control mechanism, such as, for example, the coil  110 . More specifically, the process  700  is used to control the valve  115  that controls the temperature of the coil  110 . Similar to the processes described above, the first step of the process is to input the fan start/stop command, the zone temperature set point, the zone temperature, the cooling/heating mode, and the temperature control band (step  705 ). The next step in the process  700  is to determine if the fan command is on (step  710 ). If the fan command is not on, the valve is positioned in the fully closed position (step  715 ). If the fan command is on, the controller  125  checks if the cooling mode is activated (step  720 ). If the cooling mode is not activated, the controller  125  checks if the heating mode is activated (step  725 ). If the heating mode is not activated, the valve  115  is positioned in the fully closed position (step  715 ). If either the heating mode is activated (step  725 ), or the cooling mode is activated (step  720 ), the valve  115  is modulated to maintain the zone temperature at the zone temperature set point (step  730 ). This can be completed, as previously described, by a variety of suitable methods. Upon completion, the process  700  can be repeated as needed to control the temperature of the zone.  
         [0036]     In some embodiments, each of the processes illustrated in  FIGS. 3-7  can be carried out independently of one another. In other embodiments, as previously described, two or more of the processes may be carried out concurrently. Additionally, each of the processes shown in  FIGS. 3-7  may be stored within the controller  125  such that they can be selected or deselected (i.e., turned “on” or “off”) by a user. For example, a user could access the controller  125  and select the one or more processes that are best suited for conditioning a particular zone.  
         [0037]     Various features and advantages of the invention are set forth in the following claims.