Patent Description:
This section provides background information related to the present invention and is not necessarily prior art.

Sight glasses are used in a wide variety of industrial and residential applications including, but not limited to, heating, ventilating, and air conditioning (HVAC) systems and refrigeration systems. As an example, a technician may observe a flow of refrigerant through an HVAC or refrigeration system using a sight glass, and the technician may subsequently determine various characteristics of the HVAC or refrigeration system, such as an amount of refrigerant charge of the HVAC or refrigeration system. As another example, a technician may observe a lubricant of a compressor using a sight glass, and the technician may subsequently determine various characteristics of the HVAC or refrigeration system, such as an amount of lubricant within the compressor.

<CIT> discloses a monitoring system for liquid level control. <CIT> discloses a refrigerator sensing device. <CIT> discloses an oil level control system.

This section provides a general summary of the invention, and is not a comprehensive disclosure of its full scope or all of its features.

In accordance with the present invention, there is disclosed a refrigeration system as defined in claim <NUM>, comprising: an optical sensor configured to be disposed on a sight glass, wherein the optical sensor is configured to generate signals based on a light reflectivity associated with a liquid of the refrigeration system; and an optical sensor control module that includes a processor that is configured to execute instructions stored in a nontransitory memory, wherein the instructions include: generating a set of databased on the signals; and determining an amount of liquid of the refrigeration system based on the set of data; characterized in that: the set of data is a frequency distribution; and the instructions further include, in response to the liquid being a refrigerant: generating the frequency distribution associated with the refrigerant, wherein the frequency distribution is based on a fast Fourier transform, FFT, of the signals; determining at least one probability, wherein each of the at least one probability corresponds to an amount of refrigerant of the refrigeration system; and determining the amount of refrigerant of the refrigeration system based on the at least one probability.

In some configurations and in response to the liquid being a refrigerant, the instructions further include generating a weight ratio based on (i) a first sum of frequency components of a first set of frequency bins of the frequency distribution and (ii) a second sum of frequency components of a second set of frequency bins of the frequency distribution, wherein each value of each frequency bin of the first set of frequency bins of the frequency distribution is less than each value of each frequency bin of the second set of frequency bins of the frequency distribution, and each value of the frequency distribution is associated with dynamic flow characteristics of the refrigerant. The instructions also include, in response to the weight ratio being less than a threshold weight ratio, generating a first alert signal indicating an insufficient amount of refrigerant of the refrigeration system.

In some configurations, generating the weight ratio further comprises dividing the first sum of frequency components of the first set by the second sum of frequency components of the second set.

In some configurations and in response to the liquid being a lubricant of a compressor of the refrigeration system, the instructions further include generating the frequency distribution associated with the lubricant, wherein the frequency distribution is based on a standard deviation of the signals. The instructions also include identifying a largest frequency component of the frequency distribution and determining an amount of lubricant based on the largest frequency component.

In some configurations, the instructions further include determining whether the compressor is operating in a flooded state based on the largest frequency component.

In some configurations and in response to the liquid being a lubricant of a compressor of the refrigeration system, the instructions further include generating the frequency distribution associated with the lubricant, wherein the frequency distribution is based on a difference between a maximum value and a minimum value of the signals. The instructions also include identifying a largest frequency component of the frequency distribution and determining an amount of lubricant based on the largest frequency component.

In some configurations, the instructions include transmitting an alert signal based on the amount of liquid to at least one of a remote server and a local controller in communication with the optical sensor control module.

In some configurations, the alert signal is configured to cause at least one of a computing device in communication with the remote server and the local controller to generate an indication corresponding to the alert signal.

In accordance with the present invention, there is also disclosed a method as defined in claim <NUM> comprising: generating, using an optical sensor, signals based on a light reflectivity associated with a liquid of a refrigeration system, wherein the optical sensor is configured to be disposed on a sight glass; generating, using an optical sensor control module, a set of data based on the signals, wherein the optical sensor control module includes a processor that is configured to execute instructions stored in a nontransitory memory; determining, using the optical sensor control module, an amount of liquid of the refrigeration system based on the set of data; and characterized in that: the set of data is a frequency distribution; and the method further comprises: in response to the liquid being a refrigerant, (i) generating the frequency distribution associated with the refrigerant, wherein the frequency distribution is based on a fast Fourier transform, FFT, of the signals, (ii) determining at least one probability, wherein each of the at least one probability corresponds to an amount of refrigerant of the refrigeration system, and (iii) determining the amount of refrigerant of the refrigeration system based on the at least one probability.

In some configurations and in response to the liquid being a refrigerant, the method further comprises generating, using the optical sensor control module, a weight ratio based on (i) a first sum of frequency components of a first set of frequency bins of the frequency distribution and (ii) a second sum of frequency components of a second set of frequency bins of the frequency distribution, wherein each value of each frequency bin of the first set of frequency bins of the frequency distribution is less than each value of each frequency bin of the second set of frequency bins of the frequency distribution, and each value of the frequency distribution is associated with dynamic flow characteristics of the refrigerant. The method also includes, in response to the weight ratio being less than a threshold weight ratio, generating, using the optical sensor control module, a first alert signal indicating an insufficient amount of refrigerant of the refrigeration system.

In some configurations and in response to the liquid being a lubricant of a compressor of the refrigeration system, the method further comprises generating the frequency distribution associated with the lubricant, wherein the frequency distribution is based on a standard deviation of the signals. The method also includes identifying a largest frequency component of the frequency distribution and determining an amount of lubricant based on the largest frequency component.

In some configurations, the method further includes determining whether the compressor is operating in a flooded state based on the largest frequency component.

In some configurations and in response to the liquid being a lubricant of a compressor of the refrigeration system, the method further comprises generating the frequency distribution associated with the lubricant, wherein the frequency distribution is based on a difference between a maximum value and a minimum value of the signals. The method also includes identifying a largest frequency component of the frequency distribution and determining an amount of lubricant based on the largest frequency component.

In some configurations, the method further includes transmitting an alert signal based on the amount of liquid to at least one of a remote server and a local controller in communication with the optical sensor control module.

The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present invention which is defined in the claims.

With reference to <FIG>, an example refrigeration system <NUM> is shown and includes a compressor <NUM>, a condenser <NUM>, an evaporator <NUM>, and a flow control device <NUM>. The refrigeration system <NUM>, for example, may be an HVAC system, with the evaporator <NUM> located indoors and the compressor <NUM> and condenser <NUM> located in a condensing unit outdoors.

The compressor <NUM> receives refrigerant in vapor form and compresses the refrigerant. The compressor <NUM> provides pressurized refrigerant in vapor form to the condenser <NUM>. The compressor <NUM> includes an electric motor (shown in <FIG>) that drives a pump, which may include a scroll compressor and/or a reciprocating compressor.

The pressurized refrigerant is converted into liquid form within the condenser <NUM>. The condenser <NUM> transfers heat away from the refrigerant, thereby cooling the refrigerant. When the refrigerant vapor is cooled to a temperature that is less than a saturation temperature, the refrigerant transforms into a liquid refrigerant. The condenser <NUM> may include an electric fan that increases the rate of heat transfer away from the refrigerant.

The condenser <NUM> provides the refrigerant to the evaporator <NUM> through the flow control device <NUM>. The flow control device <NUM> controls the flow rate at which the refrigerant is supplied to the evaporator <NUM>. As an example, the flow control device <NUM> may be a capillary tube, a thermal expansion valve (TXV), or an electronic expansion valve (EXV). A pressure drop caused by the flow control device <NUM> may cause a portion of the liquid refrigerant to transform back into vapor form. As such, the evaporator <NUM> may receive a mixture of refrigerant vapor and liquid refrigerant.

The refrigerant absorbs heat in the evaporator <NUM>. Liquid refrigerant transitions into vapor form when warmed to a temperature that is greater than the saturation temperature of the refrigerant. The evaporator <NUM> may include an electric fan that increases the rate of heat transfer to the refrigerant.

The refrigeration system <NUM> may include sight glass <NUM>-<NUM> and sight glass <NUM>-<NUM> (collectively referred to as sight glasses <NUM>) that, for example, enable a technician to view the liquid refrigerant and/or lubricant of the refrigeration system <NUM>. As an example, sight glass <NUM>-<NUM> enables the technician to view characteristics of liquid refrigerant discharged from the condenser <NUM>. More specifically, the technician may be able to determine an amount of refrigerant charge of the refrigeration system <NUM> based on dynamic flow characteristics of the liquid refrigerant. As another example, sight glass <NUM>-<NUM> enables the technician to view characteristics of a lubricant (e.g., oil) of the compressor <NUM>. More specifically, the technician may be able to determine an amount of lubricant of the compressor <NUM> and/or a flood back state of the compressor <NUM> using the sight glass <NUM>-<NUM>. The sight glasses <NUM> are described below in further detail with reference to <FIG>.

The compressor <NUM> is connected to a power supply <NUM> via a converter module <NUM>. As an example, the converter module <NUM> may be configured to convert a single-phase or three-phase alternating current (AC) power from the power supply having a first voltage to a second voltage suitable for operating the compressor <NUM>. In one embodiment, the converter module <NUM> may include, but is not limited to, an electromagnetic interference (EMI) filter and protection circuit for protecting against power surges and sags and reducing EMI; a power factor correction (PFC) circuit that converts AC power to direct current (DC) power, improves the efficiency of the refrigeration system <NUM>, and/or performs voltage conversion functions; and an inverter circuit for converting the DC power to an AC power suitable for operating the compressor <NUM>.

A refrigeration system control module <NUM> controls the compressor <NUM> by turning the compressor <NUM> on and off. More specifically, the refrigeration system control module <NUM> controls a compressor contactor (shown in <FIG>) that connects or disconnects an electric motor (shown in <FIG>) of the compressor <NUM> to the power supply <NUM>.

The refrigeration system control module <NUM> may be in communication with a number of sensors. For example, the refrigeration system control module <NUM> may receive outdoor ambient temperature data from an outdoor ambient temperature sensor <NUM> that may be located outdoors near the compressor <NUM> and condenser <NUM> to provide data related to the ambient outdoor temperature. The outdoor ambient temperature sensor <NUM> may also be located in the immediate vicinity of the compressor <NUM> to provide data related to the temperature at a location in the immediate vicinity of the compressor <NUM>. Alternatively, the refrigeration system control module <NUM> may receive the outdoor ambient temperature data through communication with a thermostat, or remote computing device, such as a remote server, that monitors and stores outdoor ambient temperature data.

Additionally, the refrigeration system control module <NUM> may receive electrical current data from a current sensor <NUM> connected to a power input line between the power supply <NUM> and the compressor <NUM>. The electrical current data may indicate an amount of current flowing to the compressor <NUM> when the compressor is operating. Alternatively, a voltage sensor or power sensor may be used in addition to, or in place of, the current sensor <NUM>.

Additionally, the refrigeration system control module <NUM> may receive compressor temperature data from a compressor temperature sensor <NUM> attached to and/or located within the compressor <NUM>. For example, the compressor temperature sensor <NUM> may be located at a lower portion of the compressor <NUM> due to any liquid refrigerant being located near the bottom of the compressor due to gravity and density. Other temperature sensors may be used. For example, alternatively, a motor temperature sensor may be used as the compressor temperature sensor <NUM>.

The refrigeration system control module <NUM> may be located at or near the compressor <NUM> at the condensing unit that houses the compressor <NUM> and condenser <NUM>. In such case, the compressor <NUM> may be located outdoors. Alternatively, the compressor <NUM> may be located indoors and inside a building associated with the refrigeration system. Alternatively, the refrigeration system control module <NUM> may be located at another location near the refrigeration system <NUM>. For example, the refrigeration system control module <NUM> may be located indoors. Alternatively, the functionality of the refrigeration system control module <NUM> may be implemented in a refrigeration system controller. Alternatively, the functionality of the refrigeration system control module <NUM> may be implemented in a thermostat located inside a building associated with the refrigeration system <NUM>. Alternatively, the functionality of the refrigeration system control module <NUM> may be implemented at a remote computing device.

A user interface <NUM> is configured to receive user inputs to the refrigeration system control module <NUM>. As an example, the user inputs may include a desired temperature, requests regarding operation of a fan, and/or other suitable inputs. In one embodiment, the user interface <NUM> may be implemented by a thermostat.

With reference to <FIG>, another refrigeration system <NUM> is shown. Refrigeration system <NUM> is a reversible heat pump system, operable in both a cooling mode and a heating mode. The refrigeration system <NUM> is similar to the refrigeration systems <NUM> shown in <FIG>, except that the refrigeration system <NUM> includes a four-way reversing valve <NUM>. Further, the refrigeration system <NUM> includes an indoor heat exchanger <NUM> and an outdoor heat exchanger <NUM>. In the cooling mode, refrigerant discharged from the compressor <NUM> is routed by the four-way reversing valve <NUM> to the outdoor heat exchanger <NUM>, through a flow control device <NUM>, to the indoor heat exchanger <NUM>, and back to a suction side of the compressor <NUM>. In the heating mode, refrigerant discharged from the compressor <NUM> is routed by the four-way reversing valve <NUM> to the indoor heat exchanger <NUM>, through the flow control device <NUM>, to the outdoor heat exchanger <NUM>, and back to the suction side of the compressor <NUM>. In a reversible heat pump system, the flow control device <NUM> may include an expansion device, such as a thermal expansion device (TXV) or electronic expansion device (EXV). Optionally, the flow control device <NUM> may include a plurality of flow control devices <NUM> arranged in parallel with a bypass that includes a check valve. In this way, the flow control device <NUM> may properly function in both the cooling mode and in the heating mode of the heat pump system. Other components of the refrigeration system <NUM> are the same as those described above with respect to <FIG> and their description is not repeated here.

With reference to <FIG>, the electric motor <NUM> of the compressor <NUM> is shown. As shown, a first electrical terminal (L1) is connected to a common node (C) of the electric motor <NUM>. A start winding is connected between the common node (C) and a start node (S). A run winding is connected between the common node (C) and a run node (R). The start node (S) and the run node (R) are each connected to a second electrical terminal (L2). A run capacitor <NUM> is electrically coupled in series with the start winding between the start node (S) and the second electrical terminal (L2). The refrigeration system control module <NUM> turns the electric motor <NUM> of the compressor on and off by opening and closing the compressor contactor <NUM> that connects or disconnects the common node (C) of the electric motor <NUM> to electrical terminal (L1).

With reference to <FIG>, the refrigeration system control module <NUM> is shown and includes a power converter <NUM>, a processor <NUM>, and memory <NUM>. The power converter <NUM> is configured to convert power from the power supply <NUM> into a suitable power for logic of the refrigeration system control module <NUM>. As an example, the power converter <NUM> may include an AC-DC converter and/or a buck converter that is configured to convert the AC power from the power supply <NUM> to a DC voltage suitable for logic of the refrigeration system control module <NUM> (e.g., <NUM> Volts, <NUM> Volts, etc.). Alternatively, the power converter <NUM> may only include a buck converter that receives a first DC power from the PFC circuit of the converter module <NUM> and converts it into a second DC power suitable for logic of the refrigeration system control module <NUM>.

The memory <NUM> may store control programs <NUM>. As an example, the control programs <NUM> may include programs for execution by the processor <NUM> to perform the control algorithms for executing various HVAC and refrigeration system functions. The memory <NUM> may be implemented by a nontransitory medium, such as a random-access memory (RAM) and/or read-only memory (ROM).

The memory <NUM> also includes data <NUM>, which may include historical operational data of the compressor <NUM> and refrigeration systems <NUM>, <NUM>. The data <NUM> may also include configuration data, such as setpoints and control parameters. As an example, the data <NUM> may include system configuration data and asset data that corresponds or identifies various system components in the refrigeration system <NUM>, <NUM>. As an example, the asset data may indicate specific component types, capacities, model numbers, serial numbers, and the like. The refrigeration system control module <NUM> can then reference the system configuration data and asset data during operation as part of executing various HVAC and refrigeration system functions.

The refrigeration system control module <NUM> includes inputs <NUM>, which may, for example, be connected to the various sensors, such as the current sensor <NUM>. The refrigeration system control module <NUM> may also include outputs <NUM> for communicating output signals, such as control signals. For example, the outputs <NUM> may communicate control signals from the refrigeration system control module <NUM> to the compressor <NUM>, as described herein. The refrigeration system control module <NUM> may also include communication ports <NUM>. The communication ports <NUM> may allow the refrigeration system control module <NUM> to communicate with other devices, such as an optical sensor device (discussed below and shown with respect to <FIG>), a refrigeration system controller, a thermostat, and/or a remote monitoring device. The refrigeration system control module <NUM> may use the communication ports <NUM> to communicate through an internet router, Wi-Fi, or a cellular network device to a remote server for sending or receiving data.

With reference to <FIG>, an illustration of an example sight glass <NUM> is shown. The sight glass <NUM> may be located between the condenser <NUM> and the flow control device <NUM> on the corresponding refrigeration line. In one embodiment, the sight glass <NUM> includes a lens <NUM>, an indicator <NUM>, and an indicator reference element <NUM>. As an example, the lens <NUM> may implemented by a transparent material (e.g., glass, plastic, etc.). Accordingly, the technician may view the characteristics of the liquid refrigerant discharged from the condenser <NUM> (as indicated by the dashed line) through the lens <NUM>, such as an amount of refrigerant charge in the refrigeration system.

Additionally, the indicator <NUM> may provide a visual indication corresponding to an amount of moisture in the refrigeration system. Specifically, the indicator <NUM> may have a color that represents an amount of moisture in the refrigeration system. Subsequently, the technician may compare the color of the indicator <NUM> to the indicator reference element <NUM> in order to determine a moisture level of the refrigeration system. Likewise, in other embodiments, the technician may view the characteristics of the lubricant of the compressor <NUM> using the lens <NUM> of the sight glass <NUM>.

With reference to <FIG>, an example illustration of the sight glass <NUM>, an optical sensor <NUM>, and an optical sensor control module <NUM> is shown. In one embodiment, the optical sensor <NUM> is disposed on the sight glass <NUM>, as shown by the dotted lines in <FIG>. As such, the optical sensor <NUM> is configured to obtain measurements associated with the refrigerant and/or lubricant. As an example, the optical sensor <NUM>, using a photosensor and a backlight (shown in <FIG>) is configured to measure an amount of light and/or changes in light within the lens <NUM> of the sight glass <NUM> and convert the measurements into corresponding signals. Subsequently, the optical sensor control module <NUM> is configured to determine various operating conditions and/or characteristics of the refrigeration system based on the signals received from the optical sensor <NUM>, as described below in further detail with reference to <FIG>.

In one example embodiment, refrigeration systems that have low refrigerant charge may have more bubbles within the refrigerant, while refrigeration systems that have a higher refrigerant charge may have less bubbles within the refrigerant. As such, the optical sensor <NUM> may be configured to detect dynamic flow characteristics created by the reflective light properties of a flow of bubbles within the liquid stream of refrigerant passing through the sight glass <NUM> by measuring an amount of light and/or changes in the amount of light with respect to a bias light value generated by, for example, the backlight of the optical sensor <NUM> (shown in <FIG>). The optical sensor control module <NUM> may then determine an amount of refrigerant charge of the refrigeration system, as described below in further detail with reference to <FIG>.

In another example embodiment, compressors that have a low amount of lubrication may have more turbulence, while compressors that have a normal amount of lubrication may have less turbulence. As such, the optical sensor <NUM> may be configured to detect an amount of turbulence within the lubricant by measuring an amount of light and/or changes in the amount of light with respect to a bias light value generated by, for example, the backlight of the optical sensor <NUM>. The optical sensor control module <NUM> may then determine an amount of lubricant of the compressor <NUM>, as described below in further detail with reference to <FIG>.

In another example embodiment, compressors that have a large amount of refrigerant within a compressor sump may be flooded (i.e., in a flooded state). Specifically, when an excessive amount of refrigerant is located within the compressor sump, the refrigerant may replace or offset the lubricant such that the lubricant floats on top of the refrigerant. As such, the optical sensor <NUM> may be configured to detect a presence of refrigerant in the compressor sump by measuring an amount of light and/or changes in the amount of light with respect to a bias light value generated by, for example, the backlight of the optical sensor <NUM>. The optical sensor control module <NUM> may then determine whether the signals indicate that the compressor <NUM> is flooded. As an example, signals indicating significantly elevated levels of light reflectivity may indicate the presence of refrigerant and that the compressor <NUM> is flooded, while relatively lower levels of light reflectivity may indicate that the compressor <NUM> is not flooded and therefore does not include a significant amount of refrigerant within the compressor sump.

While this embodiment illustrates the optical sensor <NUM> and the sight glass <NUM> as separate components, in alternative embodiments, the optical sensor <NUM> and the sight glass <NUM> may be implemented by a single component. In other embodiments, the sight glass <NUM> may be removed, and the optical sensor <NUM> may be incorporated within the refrigeration system such that it can obtain measurements associated with the refrigerant and/or lubricant of the refrigeration system.

With reference to <FIG>, an example functional block diagram of the optical sensor <NUM>, which includes a photosensor <NUM>, a backlight <NUM>, and an optical sensor control module <NUM>, is shown. The photosensor <NUM> may be configured to detect dynamic flow characteristics created by the reflective light properties of a flow of bubbles within the liquid stream of refrigerant passing through the sight glass <NUM> by measuring an amount of light and/or changes in the amount of light with respect to a bias light value generated by the backlight <NUM> (e.g., a light-emitting diode (LED)). Additionally, the photosensor <NUM> may be configured to detect an amount of turbulence within the lubricant by measuring an amount of light and/or changes in the amount of light with respect to a bias light value generated by the backlight <NUM>. Furthermore, the photosensor <NUM> may be configured to detect a presence of refrigerant in the compressor sump by measuring an amount of light and/or changes in the amount of light with respect to a bias light value generated by the backlight <NUM>.

The optical sensor control module <NUM> may be implemented by a microcontroller. The optical sensor control module <NUM> includes a power supply <NUM> that is configured to provide power to the various components of the optical sensor control module <NUM>. A memory <NUM> may store control programs <NUM>. As an example, the control programs <NUM> may include programs for execution by a processor <NUM> to perform the control algorithms for detecting various refrigeration system abnormalities, such as a machine learning algorithm for detecting an amount of refrigerant charge and an algorithm for detecting an amount of lubricant, as described herein. The memory <NUM> may be implemented by a nontransitory medium, such as a random-access memory (RAM) and/or read-only memory (ROM). The memory <NUM> also includes data <NUM>, which may include historical operational data corresponding to the refrigeration system abnormalities.

The optical sensor control module <NUM> includes inputs <NUM>, which may, for example, be connected to the photosensor <NUM>. The optical sensor control module <NUM> may also include an analog-to-digital converter (ADC) <NUM> for converting analog sensor data received at the inputs <NUM> to a digital value that is readable by the processor <NUM>. The optical sensor control module <NUM> may also include outputs <NUM> for communicating output signals, such as alert signals. For example, the outputs <NUM> may communicate alert signals from the optical sensor control module <NUM> to at least one of a supervisory controller and a remote server, as shown below in <FIG>. Alternatively, the outputs <NUM> may communicate alert signals from the optical sensor control module <NUM> to the refrigeration system control module <NUM>, as shown in <FIG>.

In other embodiments, the functions and configurations of the optical sensor control module <NUM> may be partially or entirely subsumed by the refrigeration system control module <NUM> or the supervisory controller described below in <FIG>.

With reference to <FIG>, an example illustration of refrigeration system <NUM> is shown. Refrigeration system <NUM> is similar to the refrigeration system <NUM> described above with reference to <FIG>, but each of the sight glasses <NUM> is coupled to a respective optical sensors <NUM>-<NUM>, <NUM>-<NUM> (collectively referred to as optical sensors <NUM>). Furthermore, each of the optical sensors <NUM> is in communication with a respective optical sensor control module <NUM>-<NUM>, <NUM>-<NUM> (collectively referred to as optical sensor control modules <NUM>). As described above with reference to <FIG>, the optical sensors <NUM> and the optical sensor control modules <NUM> are configured to determine various operating refrigeration system abnormalities of the refrigeration system <NUM> and generate alerts based on the determined refrigeration system abnormalities.

As described above, the optical sensor control modules <NUM> may transmit alert signals corresponding to the refrigeration system abnormalities to at least one of a supervisory controller <NUM> (e.g., an EMERSON® E2 controller) and a remote server <NUM> via any suitable telemetric communication link. Based on the alert signal, the supervisory controller <NUM> and the remote server <NUM> are configured to, using a respective processor that is configured to execute instructions stored on a nontransitory memory, such as a random-access memory (RAM) and/or read-only memory (ROM), generate an indication of the refrigeration system abnormalities. As an example, the supervisory controller <NUM> may, in response to receiving the alert signals, generate visual indications on a graphical user interface of the supervisory controller <NUM> indicating that the refrigeration system <NUM> needs additional refrigerant charge, the compressor <NUM> needs additional lubricant, and/or the compressor <NUM> is flooded. As another example, the remote server <NUM> may generate and transmit the alert signal to a computing device <NUM> (e.g., smartphone, laptop, PDA, etc.), which is associated with an onsite and/or a remote technician. The computing device <NUM>, in response to receiving the alert signal, may indicate, using a graphical user interface of the computing device <NUM>, to the technician that the refrigeration system <NUM> needs additional refrigerant charge, the compressor <NUM> needs additional lubricant, and/or the compressor <NUM> is flooded.

With reference to <FIG>, an example illustration of refrigeration system <NUM> is shown. Refrigeration system <NUM> is similar to refrigeration system <NUM> described above with reference to <FIG>, but each of the sight glasses <NUM> includes a respective optical sensor <NUM>-<NUM>, <NUM>-<NUM> (collectively referred to as optical sensors <NUM>). Furthermore, each of the optical sensors <NUM> is in communication with a respective optical sensor control module <NUM>-<NUM>, <NUM>-<NUM> (collectively referred to as optical sensor control modules <NUM>). As described above with reference to <FIG>, the optical sensors <NUM> and the optical sensor control modules <NUM> are configured to determine various operating refrigeration system abnormalities of the refrigeration system <NUM> and generate alerts based on the determined refrigeration system abnormalities.

Similar to the embodiment described above with reference to <FIG>, the optical sensor control modules <NUM> may be configured to transmit the alert signal to at least one of the supervisory controller <NUM> and the remote server <NUM>. Based on the alert signal, the supervisory controller <NUM> and the remote server <NUM> are configured to, using a respective processor that is configured to execute instructions stored on a nontransitory memory, generate an indication of the refrigeration system abnormalities. As an example, the supervisory controller <NUM> may, in response to receiving the alert signals, generate visual indications on a graphical user interface of the supervisory controller <NUM> indicating that the refrigeration system <NUM> needs additional refrigerant charge, the compressor <NUM> needs additional lubricant, and/or the compressor <NUM> is flooded. As another example, the remote server <NUM> may generate and transmit the alert signal to the computing device <NUM> (e.g., smartphone, laptop, PDA, etc.), which is associated with an onsite and/or a remote technician. The computing device <NUM>, in response to receiving the alert signal, may indicate, using a graphical user interface of the computing device <NUM>, to the technician that the refrigeration system <NUM> needs additional refrigerant charge, the compressor <NUM> needs additional lubricant, and/or the compressor <NUM> is flooded.

With reference to <FIG>, an example illustration of refrigeration system <NUM> is shown. Refrigeration system <NUM> is similar to the refrigeration system <NUM> described above with reference to <FIG>, but in this embodiment, the optical sensor control modules <NUM> are configured to transmit the alert signal to the refrigeration system control module <NUM> provided that the inputs <NUM> (not shown) of the refrigeration system control module <NUM> are able to process the alert signal. In response to receiving the alert signal, the refrigeration system control module <NUM> is configured to indicate, using a user interface of the refrigeration system control module <NUM> or other discrete circuitry, that the refrigeration system <NUM> needs additional refrigerant charge, the compressor <NUM> needs additional lubricant, and/or the compressor <NUM> is flooded.

With reference to <FIG>, a flowchart for a control algorithm <NUM> for detecting an amount of refrigerant charge of a refrigeration system is shown. The control algorithm <NUM> begins at <NUM> when, for example, the refrigeration system is turned on. At <NUM>, the control algorithm <NUM> detects, using the optical sensor <NUM>, reflective bubble flow within the liquid refrigerant. At <NUM>, the control algorithm <NUM> reads, via the ADC <NUM>, the data into an array. At <NUM>, the control algorithm <NUM> processes, using the optical sensor control module <NUM>, the array using a fast Fourier transform (FFT). The FFT may be defined as an algorithm that samples the signals received from the optical sensor <NUM> over a period of time and divides it into its frequency components.

At <NUM>, the control algorithm <NUM> calculates, using the optical sensor control module <NUM>, a magnitude of the FFT spectrum and stores the magnitude into a data array. At <NUM>, the control algorithm <NUM> determines whether a predetermined period of time (e.g., <NUM> hours) has elapsed. The predetermined period of time may correspond to an amount of time that the optical sensor <NUM> is in a data acquisition mode. During the data acquisition mode, the optical sensor <NUM> collects and the optical sensor control module <NUM> processes data. Additionally, the optical sensor control module <NUM> may be configured to generate a signal in response to the optical sensor <NUM> operating in the data acquisition mode. As an example, while executing steps <NUM>-<NUM>, the optical sensor control module <NUM> may generate a signal that causes a graphical user interface of the supervisory controller <NUM> to display an indication corresponding to the data acquisition mode. If the predetermined period of time elapses, the control algorithm <NUM> proceeds to <NUM>; otherwise, the control algorithm <NUM> proceeds to <NUM>.

At <NUM>, the control algorithm <NUM> segments, using the optical sensor control module <NUM>, the data array into a frequency histogram. At <NUM>, the control algorithm <NUM> executes, using the optical sensor control module <NUM>, a machine learning algorithm based on the frequency histogram. The machine learning algorithm may be implemented by, for example, a neural network. Furthermore, the hidden layers of the neural network may be configured to execute various linear functions or nonlinear functions (e.g., a sigmoid function) based on the frequency histogram. The neural network may also normalize data of the frequency histogram in order to decrease the amount of time that is needed to train the neural network and to improve the accuracy of the neural network.

In one embodiment, the machine learning algorithm may be configured to determine a probability that the refrigerant level of the refrigeration system is either at a sufficient level (i.e., normal), is below a threshold level (i.e., low), and/or is substantially below a threshold level (i.e., critically low). As an example, the machine learning algorithm may normalize the value of each frequency bin (e.g., a first frequency bin associated with a number of samples having a magnitude between <NUM>-<NUM>, a second frequency bin associated with a number of samples with a magnitude between <NUM>-<NUM>,. a fifth frequency bin associated with a number of samples having a magnitude between <NUM>-<NUM>, and a sixth frequency bin associated with a number of samples having a magnitude greater than or equal to <NUM>). The values may be normalized such that each frequency bin is associated with a value from <NUM>-<NUM>. Based on each of the normalized frequency bin values, the machine learning algorithm may be configured to generate a probability value for each potential output (normal, low, critically low). Subsequently, the machine learning algorithm may determine a refrigerant level of the refrigeration system based on the probability values.

In another embodiment, the machine learning algorithm may be configured to generate a weight ratio based on the frequency histogram. The machine learning algorithm may generate the weight ratio based on (i) a first set of frequency bins of the frequency histogram and (ii) a second set of frequency bins of the frequency histogram, wherein each value of each frequency bin of the first set is less than each value of each frequency bin of the second set. As a more specific example, the machine learning algorithm may determine the number of samples of the two frequency bins having the lowest ranges (e.g., <NUM>,<NUM> samples in the <NUM>-<NUM> frequency bin and <NUM> samples in the <NUM>-<NUM> frequency bin) and then sum the corresponding number of samples (<NUM>,<NUM> samples). The machine learning algorithm may then identify and sum the samples of the remaining frequency bins (e.g., <NUM>,<NUM> samples for the remaining frequency bins). Subsequently, the machine learning algorithm may determine whether the weight ratio is greater than a threshold value (e.g., <NUM>). The weight ratio may be based on (i) the sum of samples of the first set of frequency bins and (ii) the sum of samples of the second set of frequency bins. Specifically, the weight ratio may be determined by dividing the sum of samples of the first set of frequency bins by the sum of samples of the second set of frequency bins. If the weight ratio is greater than the threshold value, the machine algorithm may determine that there is a sufficient amount of refrigerant in the refrigeration system (i.e., normal). If the weight ratio is below the threshold weight ratio, the machine learning algorithm may determine that there is an insufficient amount of refrigerant in the refrigeration system (i.e., low). If the weight ratio is substantially below the threshold weight ratio, the machine learning algorithm may determine that there is a substantially insufficient amount of refrigerant in the refrigeration system (i.e., critically low).

At <NUM>, the control algorithm <NUM> generates, using the optical sensor control module <NUM> and at least one of the supervisory controller <NUM> and the remote server <NUM>, signals based on the machine learning algorithm outputs. As an example, the optical sensor control module <NUM> may generate a signal that causes a graphical user interface of the supervisory controller <NUM> to generate an indication that the amount of refrigerant in the refrigeration system is normal, low, or critically low. As another example, the signal may cause discrete circuitry (e.g., an LED circuit) of the supervisory controller <NUM> to generate an indication corresponding to the output (e.g., the LED circuit emits a green light when the refrigerant level is normal, a yellow light when it is low, and a red light when it is critically low).

Additionally, the optical sensor control module <NUM> may generate signals based on a status of the optical sensor <NUM>. As an example, the optical sensor control module <NUM> may be configured to generate and output a pulse-width modulation (PWM) signal to the supervisory controller <NUM> based on a condition of the optical sensor <NUM>. Specifically, the optical sensor control module <NUM> may generate a first PWM signal in response to the optical sensor <NUM> operating normally, and the optical sensor control module <NUM> may generate a second PWM signal in response to the optical sensor <NUM> operating incorrectly due to, for example, a fault. Alternatively, the optical sensor control module <NUM> may not generate a signal in response to the optical sensor <NUM> operating incorrectly. In other embodiments, the optical sensor control module <NUM> may only generate the PWM signal when the optical sensor <NUM> is operating incorrectly. As such, in response to receiving the signal based on the condition of the optical sensor <NUM>, the graphical user interface of the supervisory controller <NUM> is configured to generate an indication corresponding to the condition of the optical sensor <NUM>. At <NUM>, the control algorithm <NUM> ends.

With reference to <FIG>, a control algorithm <NUM> for detecting an amount of lubrication of the compressor <NUM> or whether the compressor <NUM> is operating in a flooded state is shown. The control algorithm <NUM> begins at <NUM> when, for example, the compressor <NUM> is turned on. At <NUM>, the control algorithm <NUM> detects, using the optical sensor <NUM>, turbulence within the lubricant. At <NUM>, the control algorithm <NUM> determines, using the optical sensor control module <NUM>, whether the compressor <NUM> is operating. If so, the control algorithm <NUM> proceeds to <NUM>; otherwise, the control algorithm <NUM> remains at <NUM> until the refrigeration system control module <NUM> determines that the compressor <NUM> is operating. At <NUM>, the control algorithm <NUM> reads, via the ADC <NUM>, the data into an array.

At <NUM>, the control algorithm <NUM> determines whether a predetermined period of time (e.g., <NUM> hours) has elapsed. The predetermined period of time may correspond to an amount of time that the optical sensor <NUM> is in a data acquisition mode. During the data acquisition mode, the optical sensor <NUM> collects and the optical sensor control module <NUM> processes data. Additionally, the optical sensor control module <NUM> may be configured to generate a signal in response to the optical sensor <NUM> operating in the data acquisition mode. As an example, while executing steps <NUM>-<NUM>, the optical sensor control module <NUM> may generate a signal that causes a graphical user interface of the supervisory controller <NUM> to display an indication corresponding to the data acquisition mode. If the predetermined period of time elapses, the control algorithm <NUM> proceeds to <NUM>; otherwise, the control algorithm <NUM> proceeds to <NUM>.

At <NUM>, the control algorithm <NUM> performs, using the optical sensor control module <NUM>, a statistical analysis on the array. As an example, the optical sensor control module <NUM> may derive an average value of the array, a standard deviation of the array, a minimum value of the array, and/or a maximum value of the array. At <NUM>, the control algorithm <NUM> segments, using the optical sensor control module <NUM>, the standard deviation or a difference between the maximum value and the minimum value (i.e., a delta minimum/maximum value) in a frequency histogram. At <NUM>, the control algorithm <NUM> determines, using the optical sensor control module <NUM>, an amount of lubricant and/or whether the compressor is operating in a flooded state based on the largest segment of the frequency histogram and outputs a corresponding alert signal to at least one of the supervisory controller <NUM> and the remote server <NUM>. In order to determine an amount of lubricant in the compressor <NUM>, the optical sensor control module <NUM> may reference a lookup table that includes information associating various frequency components and lubricant levels. In order to determine whether the compressor <NUM> is operating in a flooded state, the optical sensor control module <NUM> may determine, based on the lookup table, whether the signals indicate significantly elevated levels of light reflectivity.

As an example, if the lubricant level of the compressor <NUM> is substantially less than a threshold value, the optical sensor control module <NUM> may provide a signal to the supervisory controller <NUM>, which then generates an indication that the lubricant level of the compressor <NUM> is very low. As another example, if the lubricant level of the compressor <NUM> is less than but near the threshold value, the optical sensor control module <NUM> may provide a signal to the supervisory controller <NUM>, which then generates an indication that the lubricant level of the compressor <NUM> is low. As another example, if the lubricant level of the compressor <NUM> is greater than or equal to the threshold value, the optical sensor control module <NUM> may provide a signal to the supervisory controller <NUM>, which then generates an indication that there is a sufficient amount of lubricant in the compressor <NUM>.

Furthermore, in response to the compressor <NUM> being in the flooded state, the optical sensor control module <NUM> may provide a signal to the supervisory controller <NUM>, which subsequently generates an indication corresponding to the compressor <NUM> being in the flooded state. Furthermore, the signal may cause the supervisory controller <NUM> to activate a lubricant pump of the compressor <NUM> and thereby enable additional lubricant to enter the compressor sump. In other embodiments, the supervisory controller <NUM> may be configured to generate an indication corresponding to the operating condition of the optical sensor <NUM>, as described above.

The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. Further, although each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the disclosure can be implemented in and/or combined with features of any of the other embodiments, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with one another remain within the scope of this disclosure.

Spatial and functional relationships between elements (for example, between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including "connected," "engaged," "coupled," "adjacent," "next to," "on top of," "above," "below," and "disposed. " Unless explicitly described as being "direct," when a relationship between first and second elements is described in the above disclosure, that relationship can be a direct relationship where no other intervening elements are present between the first and second elements, but can also be an indirect relationship where one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean "at least one of A, at least one of B, and at least one of C.

In the figures, the direction of an arrow, as indicated by the arrowhead, generally demonstrates the flow of information (such as data or instructions) that is of interest to the illustration. For example, when element A and element B exchange a variety of information but information transmitted from element A to element B is relevant to the illustration, the arrow may point from element A to element B. This unidirectional arrow does not imply that no other information is transmitted from element B to element A. Further, for information sent from element A to element B, element B may send requests for, or receipt acknowledgements of, the information to element A.

In this application, including the definitions below, the term "module" or the term "controller" may be replaced with the term "circuit. " The term "module" may refer to, be part of, or include: an Application Specific Integrated Circuit (ASIC); a digital, analog, or mixed analog/digital discrete circuit; a digital, analog, or mixed analog/digital integrated circuit; a combinational logic circuit; a field programmable gate array (FPGA); a processor circuit (shared, dedicated, or group) that executes code; a memory circuit (shared, dedicated, or group) that stores code executed by the processor circuit; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system-on-chip.

The term memory circuit is a subset of the term computer-readable medium. The term computer-readable medium, as used herein, does not encompass transitory electrical or electromagnetic signals propagating through a medium (such as on a carrier wave); the term computer-readable medium may therefore be considered tangible and non-transitory. Non-limiting examples of a non-transitory, tangible computer-readable medium are nonvolatile memory circuits (such as a flash memory circuit, an erasable programmable read-only memory circuit, or a mask read-only memory circuit), volatile memory circuits (such as a static random access memory circuit or a dynamic random access memory circuit), magnetic storage media (such as an analog or digital magnetic tape or a hard disk drive), and optical storage media (such as a CD, a DVD, or a Blu-ray Disc).

The apparatuses and methods described in this application may be partially implemented by a special purpose computer created by configuring a general purpose computer to execute one or more particular functions embodied in computer programs. The functional blocks and flowchart elements described above serve as software specifications, which can be translated into the computer programs by the routine work of a skilled technician or programmer.

The computer programs include processor-executable instructions that are stored on at least one non-transitory, tangible computer-readable medium. The computer programs may also include or rely on stored data. The computer programs may encompass a basic input/output system (BIOS) that interacts with hardware of the special purpose computer, device drivers that interact with particular devices of the special purpose computer, one or more operating systems, user applications, background services, background applications, etc..

The computer programs may include: (i) descriptive text to be parsed, such as HTML (hypertext markup language) or XML (extensible markup language), (ii) assembly code, (iii) object code generated from source code by a compiler, (iv) source code for execution by an interpreter, (v) source code for compilation and execution by a just-in-time compiler, etc. As examples only, source code may be written using syntax from languages including C, C++, C#, Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl, Pascal, Curl, OCaml, Javascript®, HTML5 (Hypertext Markup Language 5th revision), Ada, ASP (Active Server Pages), PHP (PHP: Hypertext Preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, Visual Basic®, Lua, MATLAB, SIMULINK, and Python®.

None of the elements recited in the claims are intended to be a means-plus-function element within the meaning of <NUM> U. §<NUM>(f) unless an element is expressly recited using the phrase "means for," or in the case of a method claim using the phrases "operation for" or "step for.

Claim 1:
A refrigeration system (<NUM>) comprising:
an optical sensor (<NUM>) configured to be disposed on a sight glass (<NUM>), wherein the optical sensor (<NUM>) is configured to generate signals based on a light reflectivity associated with a liquid of the refrigeration system (<NUM>); and
an optical sensor control module (<NUM>) that includes a processor (<NUM>) that is configured to execute instructions stored in a nontransitory memory (<NUM>), wherein the instructions include:
generating a set of data based on the signals; and
determining an amount of liquid of the refrigeration system (<NUM>) based on the set of data;
characterized in that:
the set of data is a frequency distribution; and
the instructions further include, in response to the liquid being a refrigerant:
generating the frequency distribution associated with the refrigerant, wherein the frequency distribution is based on a fast Fourier transform, FFT, of the signals;
determining at least one probability, wherein each of the at least one probability corresponds to an amount of refrigerant of the refrigeration system (<NUM>); and
determining the amount of refrigerant of the refrigeration system (<NUM>) based on the at least one probability.