Patent ID: 12253457

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

With reference now toFIG.1, an example of a transport refrigeration system20is illustrated. In the illustrated, non-limiting embodiment, the transport refrigeration system is shown as a trailer system. As shown, the refrigerated container system20includes a cargo container or trailer22being towed or otherwise transported by a tractor24including an operator's compartment or cab26and also including an engine (not shown), which acts as the drivetrain system of the system20. A refrigeration unit30is configured to maintain cargo located within the container22at a selected temperature by cooling the cargo space of the container22. As shown, the refrigeration unit30is typically mounted at the front wall28of the container22. Together, the refrigeration unit30and the cargo container22may form a refrigerated container system. It should be appreciated by those of skill in the art that embodiments described herein may be applied to any transport refrigeration system such as, for example shipping containers that are shipped by rail, sea (via a watercraft), or any other suitable container, without use of a tractor24.

With reference toFIG.2, a basic refrigeration circuit of the refrigeration unit30is shown. The refrigeration unit30is divided into two sections, a condenser section30aand an evaporator section30b. The condenser section30amay disposed generally forward of a front wall of the container22and is arranged in fluid communication with the ambient atmosphere external to the trailer22and the refrigeration unit30to exchange air and heat therewith. The evaporator section30bis not in fluid communication with the ambient atmosphere to control temperature within the trailer22. The refrigeration unit30includes a compressor32, a condenser coil34, an expansion device36, and an evaporator coil38fluidly connected to one another to form a closed loop system. A fluid R, such as a refrigerant for example, is configured to flow from the compressor32to the condenser coil34, expansion device36, and evaporator coil38in series. A condenser fan40, such as driven by a condenser motor (not shown) is configured to move a flow of air across an exterior of the condenser coil34, and an evaporator fan42, such as driven by an evaporator motor (not shown), may be used to drive a flow of fluid (air) across an exterior of the evaporator coil38.

In an embodiment, the refrigerant R circuiting within the refrigeration unit30is an A2L refrigerant. The classification of refrigerant is based upon American Society of Heating, Refrigerating and Air-Conditioning (ASHRAE) Standard 34. The standard evaluates each refrigerant's flammability and toxicity and gives it a class referenced as a letter and number combination. The letter refers to the refrigerants' toxicity, and is based on the particular refrigerant's occupational exposure limit (OEL). The number adjacent to the letter refers to the refrigerant's flammability, and is based on the burning velocity (BV), heat of combustion (HOC), and lower flammability limits (LFL) of the particular refrigerant.

With continued reference toFIG.2, the refrigerant R within the closed loop refrigerant circuit of the refrigeration unit30may, in rare instances, leak. When utilizing A2L refrigerants in the refrigeration unit30, a leak of refrigerant R could lead to undesirable consequences due to the mildly flammable nature of A2L refrigerants. Accordingly, in an embodiment, the refrigeration unit30includes at least one refrigerant detection assembly50operable to detect a refrigerant leak therein. For example, the evaporator section30bincludes at least one refrigerant detection assembly50. The at least one refrigerant detection assembly50may be mounted to the evaporator housing of the evaporator coil38to detect gaseous refrigerant located external to the at least one tube44of the evaporator coil38. However, embodiments where a refrigerant detection assembly50is alternatively or additionally arranged at any suitable location relative to the refrigeration unit30or the container22to detect a leak therein are within the scope of the disclosure. In an embodiment, the refrigerant detection assembly50enables the detection of leaks within ten seconds of being exposed to 100% lower flammability limit (LFL). In another embodiment, the refrigerant detection assembly50enables the detection of leaks within thirty seconds of being exposed to 25% lower flammability limit (LFL). A lower flammability limit (LFL) of a refrigerant is the minimum concentration limit that is required for the refrigerant to become potentially combustible. It is envisioned that the refrigerant detection assembly50described herein may be capable of detecting a leak of at least one A2L refrigerant when the refrigerant detection assembly50detects at least 5 to 50% LFL in the sample.

An example of a refrigerant detection assembly50is illustrated in more detail inFIGS.3-4. The refrigerant detection assembly50includes a housing52. In the illustrated, non-limiting embodiment, the refrigerant detection assembly50is configured to mechanically integrate or couple to refrigerant unit30using the mounting holes52bon the housing52. Further, the refrigerant detection assembly50may be configured to electrically integrate with the refrigerant unit30via the connectors52aon the housing52. As an example, the mounting holes52band connectors52aare formed as a continuous piece of material52.

In the illustrated, non-limiting embodiment, the housing52is formed from a separate cover54and base56that are generally complementary in size and shape. The cover54and base56may be formed from a durable material, such as plastic or resin for example. The cover54may be removably coupled to the base56, such as via a plurality of fasteners, or alternatively, may be permanently affixed thereto. In an embodiment, the base56has a bottom58and a plurality of sidewalls60extending from the bottom58such that an internal cavity62is defined between the bottom58and the plurality of sidewalls60. Accordingly, the cover54may be configured to couple to the distal end of the plurality of sidewalls60to seal the cavity62. However, it should be understood that embodiments where the cavity62is formed in the cover54and embodiments where the cavity62is defined by the cover54and the base56in combination are also contemplated herein.

A subassembly64may be installed within the cavity62of the housing52. The subassembly64includes a housing65that defines an internal air chamber. In an embodiment, the housing65is formed from a removably or permanently coupled top sensor cover66and a corresponding bottom sensor cover68. At least one of the top sensor cover66and the bottom sensor cover68has an opening or hole70formed therein. In the coupled configuration, the top and bottom sensor covers66,68define an air chamber72therebetween, the air chamber72being fluidly connected with the opening70.

Further, a sensor such as a non-dispersive infrared (NDIR) sensor for example, may be associated with the air chamber72. As is known in the art, a NDIR sensor is configured to use light, for example infrared light, to evaluate the absorption characteristics of gas molecules within the light path. The gas molecules are identified and the concentration of the gas molecules may be determined by utilizing the relation (Lambert-Beer law) between the gas concentration and the absorption intensity. In an embodiment, the NDIR sensor is configured to detect the presence of refrigerant molecules, such as an A2L refrigerant for example. Accordingly, when a leak is present, the sample within the air chamber72will contain a mixture of air and refrigerant.

A printed circuit board74is disposed generally adjacent to a portion, such as the bottom surface for example, of the housing65. Although the air chamber72within the housing65functions as a reflective cavity for the optical path of the sensor, the printed circuit board74includes the circuitry and/or components associated with operation of the sensor. In an embodiment, the printed circuit board74contains the infra-red light source (not shown) and at least one corresponding detector element (not shown). The printed circuit board74may additionally include signal amplification and conditioning electronics. In an embodiment, the heat generated by the infra-red light source and/or the other electrical components of the printed circuit board74may be sufficient to maintain the sensor at a temperature above ambient to prevent condensation and/or frosting. However, in other embodiments, the printed circuit board74additionally includes one or more heating elements disposed throughout and adjacent to the housing65.

The printed circuit board74may be directly connected to a power source, or alternatively, may be adapted to receive one or more batteries sufficient to provide power thereto to operate the refrigerant detection assembly50for an extended period of time. In such embodiments, the power provided by the batteries may be the sole source of power used to operate the refrigerant detection assembly50or alternatively, may be supplemental to the power source, for example in the event of a failure or loss of power at the power source. The printed circuit board74is configured to form an interface between the sensor and the connectors52bto provide power and data to or from the refrigeration unit30.

In an embodiment, a heat conduction plate76is permanently or removably connected to the printed circuit board74opposite the housing65. The heat conduction plate76may be in direct contact with the one or more heating elements75or may be indirectly coupled to said heating elements75. The heat conduction plate76may be formed from a material having a high thermal conductivity, such as aluminum for example, to keep the sensor and/or the printed circuit board74at a higher temperature relative to surroundings, thereby preventing condensation and frosting conditions. The heat conduction plate76is additionally configured to shield the sensor/printed circuit board74from electrical noise and emissions within the environment of the container22. A breathable film78, selectively permeable to certain elements, may be mounted in overlapping relationship with a portion of the housing65. In an embodiment, the opening70is formed in an upper surface of the top sensor cover66, and the breathable film78is in direct contact with and overlaps the upper surface of the top sensor cover66. By positioning the breathable film78over the opening70, gasses are able to permeate through the film78into the air chamber72, but contaminants such as dust, oil droplets and moisture in the form of liquid are prevented from entering the air chamber72and from damaging the printed circuit board74.

The subassembly formed by the housing65, printed circuit board74, and heat conduction plate76is receivable within the cavity62of the housing52. At least one insulator80may be used to position or mount the subassembly within the cavity62. Examples of suitable materials for the insulator(s)80include but are not limited to Styrofoam and rubber. In an embodiment, at least one first insulator80is arranged between the distal end of the heat conduction plate76and an interior surface of the base56. Alternatively, or in addition, at least one second insulator80may be arranged adjacent to the top of the housing65. Inclusion of the one or more insulators80is intended to restrict movement of the subassembly within the cavity62, dampen any vibrations that may be transferred to the subassembly, and further enhance the weatherproof seal of the subassembly. The insulators80may additionally prevent heat loss from the electronics embedded within the printed circuit board74, active heating elements75and heat conduction plate76.

As shown, an insulator80may have a groove82formed in a surface thereof, the groove82being complementary to the adjacent portion of the subassembly. For example, the insulator80positioned adjacent to the base56of the housing52has a groove82complementary in size and shape to the heat conduction plate76such that the adjacent portion of the heat conduction plate76is seated within the groove82. Furthermore, an insulator80may contain additional groves for accommodating the one or more heating elements75. Similarly, the insulator80positioned adjacent to the cover54of the housing52may have a groove complementary to the top sensor cover66, such that the top sensor cover66is at least partially received within the groove. The insulators80illustrated and described herein are intended as an example only and it should be understood that the use of more than one insulator80at each of the positions described herein, as well as the inclusion of one or more insulators80at other locations about the subassembly are within the scope of the disclosure.

The cover54of the housing52has an opening84formed therein to define a flow path between the opening and the cavity62. As a result, the ambient atmosphere or air surrounding the refrigerant detection assembly50is configured to flow through the opening84, into the internal cavity62and into the air chamber72. In an embodiment, a secondary cover or shell86is connectable to the cover54of the housing52. The shell86is positionable in overlapping arrangement with the opening84and may be permanently or removably affixed to the cover54, such as with a plurality of fasteners for example. Similar to the cover54, the shell86has a shell opening88formed therein, the shell opening88being arranged in fluid communication with the opening84in the cover54. In the illustrated, non-limiting embodiment, the shell86has a plurality of substantially identical shell openings88aligned to form a grill. To further protect the subassembly from damage and contamination, a breathable film90and/or an insulator, also referred to herein as a shell insulator92, may be arranged between the exterior of the cover54and a portion of the shell86. In an embodiment, the breathable film90is replaceable.

The refrigerant detection assembly50components are combined to enable environmental robustness. The printed circuit board74, breathable films78,90, insulator80and shell openings88may be designed such that in combination these features reduce the impact of moisture on operation of the sensor or detection of refrigerant by limiting water intrusion and reducing condensation buildup. Furthermore, the portions54,56of the housing52, the internal housing65, the shell86, the heat conduction plate76, and the one or more insulators80may be configured to remove condensation when present and/or may be integrated to enable mechanical robustness while allowing fluid connection with the refrigeration unit30.

The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.

While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.