Patent Application
20240263819
The field of the disclosure relates generally to a system for controlling and monitoring heating cooling and ventilation (HVAC) systems and, more specifically, to a control system that detects and mitigates leakage of A2L class refrigerants from components of a refrigeration system.
HVAC systems, such as refrigerators and freezers, as well as heat pump systems, primarily use hydrofluorocarbon (HFC) class refrigerants. HFC class refrigerants are significant contributors to global warming and have a high Global Warming Potential (GWP). GWP is defined by the heat absorbed by any greenhouse gas in the atmosphere. As a result of their detrimental impact on global warming, HFC class refrigerants are being phased out and replaced by low GWP refrigerants such as A2L class refrigerants. However, A2L class refrigerants are flammable and cooling systems which use A2L class refrigerants require additional safety features. Such safety features include leakage detection systems and automatic shutdown systems. The categorization of “A2L” comes from the classification of refrigerants according to ASHRAE Standard 34.
In the event of a A2L class refrigerant leakage, safety regulations require specific warning, mitigation and shutdown process of the cooling system. Therefore, there exists a need for improved warning, mitigation and shutdown process of cooling systems using A2L class refrigerant, allowing for corrective action before the leakage has reached a critical stage.
In one aspect of the disclosure, an air delivery system comprises: an air handler enclosure having an inlet for enabling air to flow into the air handler enclosure and an outlet exhaust air out of the air handler enclosure, a blower located in the air handler enclosure for drawing air through the inlet and exhausting air from the outlet, at least one sensor A2L refrigerant sensor for sensing the concentration of A2L refrigerant in the air delivery system, at least one auxiliary fan, and a controller for receiving data from the A2L sensor, and powering the at least one auxiliary fan to reduce the concentration of A2L refrigerant below a predetermined threshold level.
In another aspect of the disclosure comprises a method of operating an air delivery system wherein the air delivery system comprises a blower, at least one sensor for sensing A2L refrigerant concentration in the air, and a controller for receiving data from the sensor representing the A2L refrigerant concentration and controlling operation of the blower, the method comprising: sensing the concentration of A2L refrigerant in the delivered air; sending data representing the sensed concentration of A2L refrigerant to the controller; processing the data to determine if the concentration of A2L refrigerant has exceeded a threshold concentration limit; and if the concentration of A2L refrigerant exceeds a threshold limit, controlling the air delivery system and instructing the air delivery system to perform a mitigating operation to reduce the A2L refrigerant concentration below the threshold level.
Various refinements exist of the features noted in relation to the above-mentioned aspects. Further features may also be incorporated in the above-mentioned aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the illustrated examples may be incorporated into any of the above-described aspects, alone or in any combination.
The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present disclosure. The disclosure may be better understood by reference to one or more of these drawings in combination with the detailed description of specific embodiments presented herein.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. Although specific features of various examples may be shown in some drawings and not in others, this is for convenience only. Any feature of any drawing may be referenced or claimed in combination with any feature of any other drawing.
The interior subsystem of the HVAC system 50 comprises an air handler enclosure 54 having an inlet air duct 56, an outlet air duct 58 and a drain pan 60. In some embodiments, auxiliary exhaust fans 62 are positionable at the inlet air duct 56, outlet air duct 58 or drain pan 60. The interior subsystem of the HVAC system 50 includes an evaporator 110, an expansion valve 112 and a duct blower 120 positioned within the air handler enclosure 54. The duct blower 120 is proximate the evaporator 110 and is configured to draw interior air 64 through the inlet air duct 56, to the evaporator 110 and exhaust the air 64 out the outlet air duct 58. The exterior subsystem of the HVAC system comprises a compressor 106, a condenser 108 and a condenser fan 118 configured to supply air 116 to the condenser 108.
In some embodiments, each of the condenser fan 118 and duct blower 120 include controllers 119, 121 respectively. In some embodiments, the auxiliary exhaust fans 62 are controlled by a system controller 132 of the interior subsystem. In some embodiments, operation of controllers 119, 121 of the condenser fan 118 and duct blower 120 are controlled by the system controller 132.
The compressor 106, condenser 108, evaporator 110 and expansion valve 112 are fluidly connected by refrigeration tubes 114 to form a refrigeration circuit and deliver refrigerant to the system 50 and subsystem 70. The condenser fan 118 and duct blower 120 urge the entering air 116 and 64 into the condenser 108 and the evaporator 110 respectively. The condenser fan 118 and duct blower 120 have a normal operating directions or “forward direction,” and are driven by variable speed motors well known by those skilled in the art. The condenser fan 118 or duct blower 120 are operable at the variable speed in response to a signal from the system controller 132 to the controllers 119, 121. The controllers 119 and 121 process the signals to set the speed of the respective variable speed motor. Likewise, the auxiliary exhaust fans 62 are controlled directly by the system controller 132. In some embodiments, each of the auxiliary exhaust fans 62 include a dedicated auxiliary fan controller. In some embodiments, each of the dedicated auxiliary fan controllers is communicatively coupled to the system controller 132 or the blower motor controller 121. In some embodiments, the auxiliary fan controllers receive input from an A2L refrigerant sensor 126 and control operation of the auxiliary exhaust fans 62 without intervention from the system controller 132.
In some embodiments, the A2L refrigerant sensor 126 is positioned internal to the duct blower 120 (also shown in
In some embodiments, the A2L refrigerant sensor 126 is positioned at a sensing location external to the blower housing 42, and is located along the air circulation path defined by the air handler enclosure 54. In particular the A2L refrigerant sensor 126 is positioned at one or more of the following locations within the air handler enclosure 54 where A2L refrigerant may accumulate: at the drain pan 60, at the outlet air duct 58 proximate the duct blower 120 and at the inlet air duct 56. In some embodiments, The A2L refrigerant sensor 126 is combined with the electronics of the blower motor controller 121 (as shown in
In certain embodiments, motors 122 are electronically commutated motors (ECMs). The motors 122 are communicatively coupled, either directly or through controllers 119, 121 to the system controller 132 and the motors 122 are configured to operate in response to a control signal generated by the system controller 132 or by the blower motor controller 121. Motors 122 are capable of changing operation based on the control signal. For example, in response to the control signal, motors 122 may activate, deactivate, operate at a specified speed, torque, power, or reverse direction or otherwise modify motor functionality consistent with another operating parameter.
The system controller 132 includes a microprocessor 134 and a local memory 138. In some alternative embodiments, microprocessor 134 and local memory 138 are incorporated into the controllers 119, 121 of one or more of motors 122. Microprocessor 134 is communicatively coupled to motors 122 and sensors 124 using, for example, a wired Modbus connection. Microprocessor 134 is configured to read instructions stored in local memory 138 and generate the control signal for motors 122 based on the instructions and sensor data received from sensors 124. Such instructions include data (sometimes referred to herein as “configuration data”) that defines settings under which microprocessor 134 controls the operation of motors 122. For example, motor operation may be controlled by the microprocessor by specifying a particular control signal output for a given sensor data input. More specifically, in the general example provided, the microprocessor 134 may receive power data and motor direction data from motor performance sensor 128 and thereby controls motor operating speed, torque, power or direction after executing an algorithm using the sensed power data and motor direction data. The algorithm may comprise a lookup table or a formula (e.g., a polynomial function determined by regression analysis). In some embodiments, microcontroller further controls operation of motors 122 based on humidity data, air pressure data, motor performance data, other data, or a combination thereof in a similar manner as described with respect to power data and motor direction data and the like.
In some embodiments, the system controller 132 is further in communication with a network 140 (shown in more detail with respect to
As used herein, the term LFL % (Lower Flammability Limit) data shall denote the percentage of A2L refrigerant in a gaseous medium. The A2L refrigerant sensor 126 is configured to measure the percentage of A2L refrigerant in a gaseous medium.
Sensors 124 are configured to detect physical properties of HVAC system 50 or its environment, and generate a sensor signal that represents data (sometimes referred to herein as “sensor data”) collected by sensors 124. For example, A2L refrigerant sensors 126 detects A2L refrigerant gas concentrations in the HVAC system 50. The HVAC system 50 may also include additional sensors that detect other properties of HVAC system 50 and its environment such as system temperature and pressure sensors 128 or a static air pressure sensor 127. In response to the measurements made and data collected by the A2L refrigerant sensors 126 and system temperature and pressure sensors 128, the blower motor controller 121 (or the system controller 132) executes instructions by sending signals to the motors 122, either directly or through respective controllers 119, 121. The instructions are generally stored in memory 138 as one or more profiles. The profiles can be specific to duct blower 120, or for a particular end user cooling solution. The profiles can also be uploaded to a server or local memory. Thus, the blower motor controller 121 (or the system controller 132) can be retrofitted to existing HVAC systems with the inclusion of the A2L refrigerant sensor 126 onto existing blower motors.
In some embodiments, the A2L refrigerant sensor 126 can have one or more different communication interfaces with the blower motor controller 121 (or the system controller 132), each of which provide a different data output. As shown in
In the following embodiments, the A2L refrigerant sensor 126 provides data to the blower motor controller 121 (or the system controller 132) of the duct blower 120, and the blower motor controller 121 process the data from the A2L refrigerant sensor 126 and send the processed data to the system controller 132. Such a configuration enables retrofitting the duct blower 120 by only including the A2L refrigerant sensor 126 onto existing blower motors. The various configurations permit retrofitting on both older and newer systems. By way of example, but not limitation, existing systems having a Digital Serial communication interface can be retrofitted with an A2L refrigerant sensor 126 having the same interface, whereas existing systems having an analog communication interface can be retrofitted with an A2L refrigerant sensor 126 also having an analog communication interface.
In one embodiment, the A2L refrigerant sensor 126 has a Digital Serial communication interface, where the A2L refrigerant sensor 126 provides as data outputs: LFL % data, air temperature of the air 64 drawn through the blowers, humidity of the air 64 drawn through the blowers and a device status indicator. These parameters are communicated as data from the motor to either of the blower motor controller 121 or the system controller 132. In some embodiments, the controller 121 of the duct blower 120 is communicatively connected to the system controller 132 by way of a DSI Mode-AIRKOM. In such a configuration, the blower motor controller 121 of the duct blower 120 sends LFL % data and the rotational speed of the duct blower 120 to the system controller 132. In some embodiments, the A2L refrigerant sensor 126 includes a drive located a distance from the associated sensor, where the sensor is positioned at a location suitable to effectively measure LFL % at the associated location and the drive is positioned remote from the sensor location. In some embodiments, the A2L refrigerant sensor 126 is integral to the blower assembly 10 as shown in
In another embodiment, the A2L refrigerant sensor 126 has an analog signal communication interface, where the A2L refrigerant sensor 126 provides as data output the LFL % data. The LFL % data is sent by the blower motor controller 121 of the duct blower 120 to the system controller 132 by way of a tachometer signal. Although the A2L refrigerant sensor 126 in this embodiment is specifically sending LFL % data, it should be understood that in some embodiments, the blower motor controller 121 of the duct blower 120 may also communicate air temperature of the air 64 drawn through the blowers, and humidity of the air 64 drawn through the blowers measured from other sensors 124. In some embodiments, the tachometer signal is a pulse-width-modulation (PWM) signal. This data is used to control operation of motors 122.
In operation, the blower motor controller 121 of the duct blower 120 receives a PWM Signal from the system controller 132 to regulate the speed and torque of the duct blower 120, which may be varied linearly with the duty of the PWM with a fixed frequency. The blower motor controller 121 of the duct blower 120 sends a feedback signal to the system controller 132 in the form of the tachometer signal having a frequency that varies linearly with the rotational speed of the duct blower 120. The tachometer signal is a feedback signal to the system controller 132 which represents the actual speed of the duct blower 120.
In yet another embodiment, the A2L refrigerant sensor 126 has an I/O communication interface, where the A2L refrigerant sensor 126 provides as data output status signals: Active HIGH signal when the LFL % measured by the sensor has exceeded a threshold limit, and an Active LOW signal when the LFL % measured by the sensor is below the threshold limit. The threshold limit may be programmed into the A2L refrigerant sensor 126. The LFL % data is sent by the blower motor controller 121 of the duct blower 120 to the system controller 132 by way of a dedicated signal. Although the A2L refrigerant sensor 126 in this embodiment is disclosed as only communicating a status signal, it should be understood that in some embodiments, the blower motor controller 121 of the duct blower 120 may also communicate temperature of the air 64 drawn through the duct blower 120, and/or humidity of the air 64 urged through the duct blower 120 measured from other sensors 124. This sensed data will be used singly, or in combination to control motors 122.
The system controller 132 continuously receives LFL % data and, upon determination that the LFL % data has exceeded a threshold percentage, the system controller 132 may transmit a signal to the controller 121 of the duct blower 120 to cause the blower to perform one or more operations to reduce the LFL % present in the system, and thereby achieve an acceptable LFL % that is below a predetermined threshold LFL %. In some embodiments, the threshold percentage is 25%. In some embodiments, the blower motor controller 121 (or the system controller 132) can further instruct the relay 107 of the compressor 106 to perform one or more operations to reduce the LFL % present in the system (also reffered to as a “mitigating operation”). In some embodiments, the mitigating operation includes instructing, by the blower motor controller 121 (or the system controller 132), the blower motor controller 121 of the duct blower 120, to increase the rotational speed from a normal operating speed to full operating speed, where the full operating speed is greater than the normal operating speed. This increase to the rotational speed is implemented when the LFL % has exceeded the threshold.
In some embodiments, the rotational speed of the duct blower 120 is operated at an overdrive speed, where the overdrive speed is greater than the full operating speed. The duct blower 120 is run at the overdrive speed such that air 64 is drawn through the blower at a greater velocity, and thereby increasing the rate of expulsion of A2L refrigerant to more quickly reduce the LFL % to a level that is below the predefined acceptable threshold LFL %.
In some embodiments, the rotational speed of the duct blower 120 is proportional to the LFL %, where an increased concentration of A2L refrigerant results in a greater rotational speed of the duct blower 120. When the A2L refrigerant concentration LFL % is below the threshold but the sensor 126 detects an increase in LFL % that is at a value that is proximate the threshold LFL %, the speed of the duct blower 120 may be increased to prevent the concentration from reaching the threshold LFL %.
In some embodiments, the mitigating operation includes instructing, by the blower motor controller 121 (or the system controller 132), the relay 107 of the compressor 106 to shut off power to the compressor when the LFL % has exceeded the threshold. In some embodiments, the blower motor controller 121 (or the system controller 132) can shut off power to all electrical components of the HVAC system 50, except control transformers by means of a relay and sends the data to the blower motor controller 121 (or the system controller 132) when the LFL % has exceeded the threshold.
After the LFL % present in the system has returned to a value that is below the threshold, the blower motor controller 121 (or the system controller 132) send a signal to the controller 121 of the duct blower 120 and upon processing the signal, return the blower speed to the normal operating speed. In some embodiments, after the LFL % present in the system has returned below the threshold, the blower motor controller 121 (or the system controller 132) instructs the relay 107 of the compressor 106 to turn on power to the compressor 106, activating the compressor 106.
In some embodiments if mitigating operations do not completely reduce the concentration of A2L to an acceptable level, further controlled operations may be performed. In such situations, the blower motor controller 121 (or the system controller 132) is further configured to send a signal to the network 140 to alert an end user of the presence of airborne A2L. In some embodiments, where the HVAC system 50 does not completely mitigate the concentration of A2L refrigerant in the air 64, the blower motor controller 121 (or the system controller 132) is further configured to shut down the HVAC system 50. By way of example, when the duct blower 120 runs at high volume flow rate of airflow, but the A2L gas concentration still cannot be reduced below the threshold, the blower motor controller 121 (or the system controller 132) is further configured to shut down the HVAC system 50. In some embodiments, at least one of system controller 132 and controller 121 may transmit wired or wireless information about A2L refrigerant concentration status to the system thermostat or a building/home automation system. In some embodiments, the blower motor controller 121 (or the system controller 132) may include long term memory storage (e.g. EEPROM) where the microcontroller can store information related to the number of A2L alarms over time or the data related to the concentration of A2L gas over time. Based on the analysis of the information, the blower motor controller 121 (or the system controller 132) can detect system leaks over time.
In some embodiments, the duct blower motor has a lower PWM switching frequency below 15 KHz (which is audible to human ear) when LFL % reaches a specific set threshold and that switch to a lower frequency creates a hissing noise to alert the homeowner of a possible leak. In some embodiments, the blower motor lowers its PWM switching frequency below 15 KHz when LFL % reaches a specific set threshold creating harmonic torque in the motor which produces a vibration of the motor that serves to alert a third party of a possible leak. In some embodiments, blower motor switches back to its normal operating switching frequency once the LFL % comes back to the safe range.
In some embodiments, where the HVAC system 50 does not successfully mitigate the concentration of A2L refrigerant in the air 64, the blower motor controller 121 (or the system controller 132) is configured to monitor pressure variation between components against a profile to determine if a leak of A2L refrigerant is occurring between components. In some embodiments, the blower motor controller 121 (or the system controller 132) is configured to monitor tube leaks within a housing of the HVAC system 50. In some embodiments, the blower motor controller 121 (or the system controller 132) is configured to indirectly sense a leak with volume of space for concentration, which is linked to constant airflow. In some embodiments, the blower motor controller 121 (or the system controller 132) is configured to predict leakage over time. In some embodiments, the blower motor controller 121 (or the system controller 132) is configured to use pressure information as a backup in the event that the A2L refrigerant sensor 126 fails. If the A2L refrigerant sensor 126, the blower motor controller 121 (or the system controller 132) is configured to enter a limp mode.
The method includes receiving 302 LFL % data from an A2L refrigerant sensor of a duct blower present in the HVAC system 50; sending 304 LFL % data to blower motor controller 121; and processing 306, by the blower motor controller 121 the LFL % data to determine if A2L refrigerant has exceeded a predetermined threshold value stored in memory. In some embodiments, the method 300 further comprises instructing 308, by the blower motor controller 121, the blower controller to perform one or more mitigating operations if the A2L refrigerant has exceeded the predetermined threshold value.
In the foregoing specification and the claims that follow, a number of terms are referenced that have the following meanings.
As used herein, an element or step recited in the singular and preceded with the word “a” or “an” should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. Furthermore, references to “example implementation” or “one implementation” of the present disclosure are not intended to be interpreted as excluding the existence of additional implementations that also incorporate the recited features.
“Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.
Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here, and throughout the specification and claims, range limitations may be combined or interchanged. Such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise.
Some embodiments involve the use of one or more electronic processing or computing devices. As used herein, the terms “processor” and “computer” and related terms, e.g., “processing device,” “computing device,” and “controller” are not limited to just those integrated circuits referred to in the art as a computer, but broadly refers to a processor, a processing device, a controller, a general purpose central processing unit (CPU), a graphics processing unit (GPU), a microcontroller, a microcomputer, a programmable logic controller (PLC), a reduced instruction set computer (RISC) processor, a field programmable gate array (FPGA), a digital signal processing (DSP) device, an application specific integrated circuit (ASIC), and other programmable circuits or processing devices capable of executing the functions described herein, and these terms are used interchangeably herein. The above embodiments are examples only, and thus are not intended to limit in any way the definition or meaning of the terms processor, processing device, and related terms.
In the embodiments described herein, memory may include, but is not limited to, a non-transitory computer-readable medium, such as flash memory, a random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and non-volatile RAM (NVRAM). As used herein, the term “non-transitory computer-readable media” is intended to be representative of any tangible, computer-readable media, including, without limitation, non-transitory computer storage devices, including, without limitation, volatile and non-volatile media, and removable and non-removable media such as a firmware, physical and virtual storage, CD-ROMs, DVDs, and any other digital source such as a network or the Internet, as well as yet to be developed digital means, with the sole exception being a transitory, propagating signal. Alternatively, a floppy disk, a compact disc—read only memory (CD-ROM), a magneto-optical disk (MOD), a digital versatile disc (DVD), or any other computer-based device implemented in any method or technology for short-term and long-term storage of information, such as, computer-readable instructions, data structures, program modules and sub-modules, or other data may also be used. Therefore, the methods described herein may be encoded as executable instructions, e.g., “software” and “firmware,” embodied in a non-transitory computer-readable medium. Further, as used herein, the terms “software” and “firmware” are interchangeable, and include any computer program stored in memory for execution by personal computers, workstations, clients and servers. Such instructions, when executed by a processor, cause the processor to perform at least a portion of the methods described herein.
Also, in the embodiments described herein, additional input channels may be, but are not limited to, computer peripherals associated with an operator interface such as a mouse and a keyboard. Alternatively, other computer peripherals may also be used that may include, for example, but not be limited to, a scanner. Furthermore, in the example embodiment, additional output channels may include, but not be limited to, an operator interface monitor.
The systems and methods described herein are not limited to the specific embodiments described herein, but rather, components of the systems and/or steps of the methods may be utilized independently and separately from other components and/or steps described herein.
Although specific features of various embodiments of the disclosure may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the disclosure, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.
This written description uses examples to provide details on the disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences.
| Number | Date | Country | |
|---|---|---|---|
| 63483026 | Feb 2023 | US |
