Patent Publication Number: US-2016230634-A1

Title: Active cooling assembly for sensor module

Description:
TECHNICAL FIELD 
     The present disclosure relates to a cooling system, and more specifically to an active cooling assembly for a sensor unit of an engine system. 
     BACKGROUND 
     Engine systems may include a plurality of sensors, for example, sensors for measuring a quantity of Nitrous Oxides (NOx) present in an exhaust gas generated by the engine system. Such sensors may be located at various locations, such as, on or within an aftertreatment system associated with the engine system. These locations may experience elevated temperatures during operation of the engine system and/or the aftertreatment system. The elevated temperatures at such locations may result in an increase in temperature of the sensors placed therein. In a situation when the temperature of the sensors may exceed an operating temperature limit, the sensors may provide incorrect readings and/or may fail prematurely before an estimated life span, thereby causing an increase in service intervals and operating costs, and also affect an overall productivity of the system. This situation is especially prevalent among NOx sensors, which due to the nature of their operation are typically placed in direct exposure to the hot exhaust gases. 
     U.S. Pat. No. 8,341,949 describes an aftertreatment module. The aftertreatment module includes a housing having an exhaust inlet and an exhaust outlet. The aftertreatment module includes at least one NOx sensor disposed within the housing. The aftertreatment module also includes a thermal isolating structure connected directly to the housing. The thermal isolating structure includes a mounting plate disposed at a distance from the housing such that an air gap is formed between the mounting plate and the housing. 
     SUMMARY OF THE DISCLOSURE 
     In one aspect of the present disclosure, an actively cooled nitrous oxide sensor module is provided. The actively cooled nitrous oxide sensor module includes a sensor unit comprising at least one nitrous oxide sensor and at least a portion of circuitry associated with the at least one nitrous oxide sensor. The actively cooled nitrous oxide sensor module also includes an active cooling assembly thermally coupled to the sensor unit. The active cooling assembly includes a coolant inlet and a coolant outlet. The active cooling assembly also includes a coolant path disposed between the coolant inlet and the coolant outlet. The active cooling assembly is configured to control a temperature of the sensor unit based, at least in part, on a circulation of a coolant flow therethrough. 
     In another aspect of the present disclosure, an engine system is provided. The engine system includes an engine having an exhaust conduit. The engine system includes a reductant injector coupled to the exhaust conduit. The engine system also includes a selective catalytic reduction module in fluid communication with the reductant injector. The selective catalytic reduction module is positioned downstream of the reductant injector with respect to an exhaust gas flow. The engine system further includes an actively cooled nitrous oxide sensor module. The actively cooled nitrous oxide sensor module includes a sensor unit provided in association with the selective catalytic reduction module. The sensor unit includes at least one nitrous oxide sensor and at least a portion of circuitry associated with the at least one nitrous oxide sensor. The actively cooled nitrous oxide sensor module also includes an active cooling assembly thermally coupled to the sensor unit. The active cooling assembly includes a coolant inlet and a coolant outlet. The active cooling assembly also includes a coolant path disposed between the coolant inlet and the coolant outlet. The active cooling assembly is configured to control a temperature of the sensor unit based, at least in part, on a circulation of a coolant flow therethrough. 
     In yet another aspect of the present disclosure, a method for cooling a nitrous oxide sensor is provided. The method includes providing an active cooling assembly in association with a sensor unit for the nitrous oxide sensor. The method includes receiving a coolant flow into a coolant inlet of the active cooling assembly from an aftercooler. The method also includes circulating the coolant flow through a coolant path of the active cooling assembly. The method further includes controlling a temperature of the sensor unit based, at least in part, on the circulation of the coolant flow therethrough. 
     Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partial cross sectional view of an exemplary machine, according to an embodiment of the present disclosure; 
         FIG. 2  is a top right perspective view of an aftertreatment system showing an exemplary inlet sensor unit, according to an embodiment of the present disclosure; 
         FIG. 3  is a top left partial perspective view of the aftertreatment system showing an exemplary outlet sensor unit, according to an embodiment of the present disclosure; 
         FIG. 4  is a perspective view of the exemplary inlet sensor unit, according to an embodiment of the present disclosure; and 
         FIG. 5  is flowchart of a method of working of an active cooling assembly for the inlet and/or outlet sensor unit, according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or similar parts. Referring to  FIG. 1 , a partial cross sectional view of a machine  100  is illustrated. More specifically, in the illustrated embodiment, the machine  100  is a locomotive. In other embodiments, the machine  100  may be associated with an industry including, but not limited to, transportation, construction, agriculture, forestry, material handling, and waste management. Accordingly, the machine  100  may be any machine such as, a mining truck, an off-highway truck, a wheel loader, a track loader, a track type tractor, and other such machines. 
     The machine  100  includes a frame  102 . The frame  102  is configured to support one or more components of the machine  100 . The machine  100  includes an operator cabin  104  provided on the frame  102 . The operator cabin  104  may include an operator interface (not shown). The machine  100  includes a set of wheels  106  rotatably coupled to the frame  102 . The set of wheels  106  are configured to provide mobility to the machine  100  on a set of rails (not shown). 
     The machine  100  includes an enclosure  108  provided on the frame  102 . An engine system  110  is provided within the enclosure  108 . The engine system  110  includes an engine  112 . The engine  112  is an internal combustion engine powered by a fuel, such as, gasoline, diesel, natural gas, and any other fuel known in the art. The engine  112  is configured to provide power to the machine  100  for mobility and other operational requirements. 
     The engine system  110  includes a turbocharger  114 . The turbocharger  114  is fluidly coupled to an intake manifold  116  and an exhaust manifold (not shown) of the engine  112 . The turbocharger  114  is configured to compress intake air before being supplied to the intake manifold  116  of the engine  112 . The engine system  110  also includes an aftercooler  118 . In other embodiments, the engine system  110  may include an intercooler. The aftercooler  118  is fluidly coupled to the turbocharger  114  and the intake manifold  116  and is provided downstream of the turbocharger  114  with respect to a flow of the intake air. The aftercooler  118  is configured to cool the compressed intake air supply of the compressed air to the intake manifold  116 . The aftercooler  118  also includes an aftercooler cooling circuit (not shown). The aftercooler cooling circuit is configured to allow heat exchange with the aftercooler  118 . 
     The machine  100  includes an aftertreatment system  120 . Referring to  FIG. 2 , a top right perspective view of the aftertreatment system  120  is illustrated. The aftertreatment system  120  is configured to reduce the amount of regulated exhaust constituents in the exhaust gas flow from the engine  112 . The aftertreatment system  120  includes an inlet  202 . The inlet  202  is provided in fluid communication with the exhaust manifold of the engine  112 . The inlet  202  is configured to receive the exhaust gas flow within the aftertreatment system  120 . The aftertreatment system  120  includes a casing  204 . The casing  204  is configured to enclose and support one or more components of the aftertreatment system  120 . 
     The aftertreatment system  120  may include one or more Selective Catalytic Reduction (SCR) modules (not shown) and/or a reductant injector (not shown) configured to introduce a reductant into the exhaust gas flow. The reductant injector may be coupled to an exhaust conduit (not shown) of the engine  112  and provided in fluid communication with the SCR modules. Further, the SCR modules may be provided downstream of the reductant injector with respect to the exhaust gas flow. The reductant, and/or decomposition byproducts thereof, disposed on the SCR modules may react with Nitrous Oxides (NOx) present in the exhaust gas flow to form water (H 2 O) and diatomic nitrogen (N 2 ). Specifically, the reductant may be gaseous or liquid urea, ammonia, any of a variety of hydrocarbons, or other similar compositions as known to one of ordinary skill in the art. Additionally or optionally, the aftertreatment system  120  may also include other components (not shown), such as, a Diesel Particulate Filter (DPF), a Diesel Emission Fluid (DEF), a Diesel Oxidation Catalyst (DOC), and so on. 
     The aftertreatment system  120  also includes an outlet  206 . The outlet  206  is provided in fluid communication with the casing  204 . The outlet  206  is configured to exit the exhaust gas flow from the aftertreatment system  120 . The aftertreatment system  120  includes a sensor unit placed at the inlet  202  of the aftertreatment system  120 , hereinafter referred to as an inlet sensor unit  208 , or the exhaust conduit of the engine  112 . 
     The inlet sensor unit  208  includes a body  210  configured to enclose at least one of an inlet Nitrous Oxide (NOx) sensor  214  and at least a portion of an inlet sensor circuitry  216  associated with the inlet NOx sensor  214 . The inlet sensor circuitry  216  may include, but not limited to, communication cables, a controller, a Printed Circuit Board (PCB), other electrical/electronic components, and so on. The inlet NOx sensor  214  is configured to generate a signal indicative of an amount of NOx present in the exhaust gas flow entering the aftertreatment system  120  at the inlet  202 . Further, the inlet sensor unit  208  includes an active cooling assembly  212 . The active cooling assembly  212  will be explained in more detail with reference to  FIG. 4 . 
     Referring to  FIG. 3 , a top left partial perspective view of the aftertreatment system  120  is illustrated. As shown in  FIG. 3 , the aftertreatment system  120  also includes an outlet sensor unit  302  placed at the outlet  206  of the aftertreatment system  120  or the exhaust conduit of the engine  112 . 
     The outlet sensor unit  302  includes a body  304  configured to enclose at least one of an outlet Nitrous Oxide (NOx) sensor  314  and at least a portion of an outlet sensor circuitry  316  associated with the outlet NOx sensor  314 . The outlet sensor circuitry  316  may include, but not limited to, communication cables, a controller, a Printed Circuit Board (PCB), other electrical/electronic components, and so on. The outlet NOx sensor  314  is configured to generate a signal indicative of an amount of NOx present in the exhaust gas flow exiting the aftertreatment system  120  from the outlet  206 . Additionally, the outlet sensor unit  302  includes an active cooling assembly  312  that is substantially similar to the active cooling assembly  212 . The active cooling assemblies  212 ,  312  will be explained in more detail with reference to  FIG. 4 . 
     It should be noted that the number and location of the inlet and/or outlet NOx sensors  214 ,  314  of the inlet and/or outlet sensor units  208 ,  302  described herein are merely exemplary. For example, in other embodiments, the inlet and/or outlet sensor units  208 ,  302  may include any other sensor such as, a Sulfur Oxide (SOx) sensor, a Carbon Monoxide (CO) sensor, a Hydrocarbon (HC) sensor, an Infrared (IR) sensor, a Thermal Imaging (TI) sensor, a temperature sensor, a pressure sensor, and so on as per system design and requirements. Also, the inlet and/or outlet sensor units  208 ,  302  may be located at any other location on the aftertreatment system  120  and/or the engine system  110  as per system design and requirements. Further, in some embodiments, the system may include any one of the inlet sensor unit  208  and the outlet sensor unit  302 . A person of ordinary skill in the art will appreciate that the inlet and outlet sensor units  208 ,  302  may be similar or different in construction and design, as the case may be. 
     Referring to  FIG. 4 , a perspective view of an exemplary embodiment of the active cooling assembly  212  is illustrated. For the purpose of clarity and explanation, the inlet NOx sensor  214  and the inlet sensor circuitry  216  have been omitted from  FIG. 4 . In the present embodiment, the active cooling assembly  312  is substantially similar in structure and function to the active cooling assembly  212 . The active cooling assembly  212  is configured to control a temperature of the inlet sensor unit  208  based, at least in part, on a circulation of a coolant flow therethrough. The coolant may be any coolant known in the art, such as water, a water based coolant, an oil based coolant, an air based coolant, such as ambient air, and so on. 
     In the present embodiment, the active cooling assembly  212  includes a housing  404 . The housing  404  has a hollow configuration. The housing  404  is provided on the body  210  of the inlet sensor unit  208  in a manner such that the inlet sensor unit  208  is provided in conductive thermal contact with and is positioned within the active cooling assembly  212 . The housing  404  includes a coolant inlet  406 , a coolant outlet  410 , and at least one coolant path  408  connected therebetween. The coolant path  408  is provided in conductive thermal contact with at least a portion of one face of the inlet sensor unit  208 . For example, in the illustrated embodiment, the coolant path  408  is provided on more than one face of the inlet sensor unit  208 . In other embodiments, the coolant path  408  may be provided on any one face of the inlet sensor unit  208 . 
     The coolant inlet  406  is configured to receive the coolant flow into the active cooling assembly  212 . The coolant inlet  406  may be provided in fluid communication with the aftercooler  118 . More specifically, the coolant inlet  406  may be provided in fluid communication with an inlet section of the aftercooler cooling circuit. The coolant inlet  406  is configured to receive the coolant flow into the active cooling assembly  212  therefrom. The active cooling assembly  212  functions to actively cool the inlet sensor unit  208  via heat transfer from either the environment external to the inlet sensor unit  208  or the environment internal to the inlet sensor unit  208 , or both, to the coolant flow within the active cooling assembly  212 . 
     In the embodiment wherein the engine system  110  may include the intercooler, the active cooling assembly  212  may be provided in fluid communication with an intercooler cooling circuit such that coolant flow is received therefrom. In yet other embodiments, the active cooling assembly  212  may be provided in fluid communication with any other cooling system provided on the machine  100 , such as, an engine cooling system, a transmission cooling system, a cooling system associated with an electrical system of the machine  100 , an operator cabin cooling system, any other Heating, Ventilation and Air Conditioning (HVAC) unit, and so on. 
     In the present exemplary embodiment, the active cooling assembly  212  includes the coolant path  408  provided in the housing  404 . The coolant path  408  is provided in fluid communication with the coolant inlet  406 . The coolant path  408  is configured to circulate the coolant flow through the housing  404  and exchange heat with the inlet sensor unit  208 . The active cooling assembly  212  is configured such that the coolant path  408  provides sufficient surface area such that the inlet sensor unit  208  is exposed to the coolant flow to produce the desired heat transfer and temperature moderation; one of ordinary skill in the art would appreciate that a variety of patterns or channels may be provided to create the coolant path  408 . 
     One of ordinary skill in the art will appreciate that the coolant may be at a temperature lower than the temperature of the inlet sensor unit  208 . In such a situation, the coolant may exchange heat with the inlet sensor unit  208  in order to lower the temperature of the inlet sensor unit  208 . In the illustrated figures, the coolant path  408  is provided within the housing  404  in a serpentine configuration. In other embodiments, the coolant path  408  may be provided within the housing  404  in a coiled configuration, a helical configuration, a zigzag configuration, a configuration having a plurality of parallel paths, or in any other manner such that the coolant may flow through the housing  404  of the active cooling assembly  212 . 
     The coolant outlet  410  is provided in fluid communication with the coolant path  408 . Further, in the embodiment wherein the coolant is provided from the aftercooler  118 , the coolant outlet  410  is provided in fluid communication with an outlet section of the aftercooler cooling circuit. The coolant outlet  410  is configured to exit the coolant flow from the active cooling assembly  212 . In other embodiments, the coolant may flow to other parts or components of the engine system  110 . In some embodiments, the housing  404  may further include a plurality of fins (not shown) provided thereon. The plurality of fins may be configured to provide heat exchange between the housing  404  and ambient air. 
     Additionally, the active cooling assembly  212  includes at least one mounting leg  412  extending from the housing  404 . The at least one mounting leg  412  may be configured to affix the housing  404  to the aftertreatment system  120 , the exhaust conduit and/or the inlet sensor unit  208 . Further, the at least one mounting leg  412  may extend in such a manner so as to separate the inlet sensor unit  208  away from a mounting surface of the aftertreatment system  120  or the exhaust conduit, in order to further control, lessen or prevent the increase in the temperature of the inlet sensor unit  208  due to conduction with a relatively heated surface of the aftertreatment system  120  or the exhaust conduit respectively. 
     In another embodiment, the at least one mounting leg  412  may be provided extending from the body  210  of the inlet sensor unit  208  in order to affix the inlet sensor unit  208  to the casing  204  of the aftertreatment system  120 . In another embodiment, the at least one mounting leg  412  may be provided extending from the active cooling assembly  212  in order to affix the active cooling assembly  212  to the casing  204  of the aftertreatment system  120 . In yet other embodiments, the body  210  of the outlet sensor unit  302  or the housing  404  of the active cooling assembly  212  may be affixed to the casing  204  of the aftertreatment system  120  by any fastening method known in the art such as, welding, riveting, bolting, and so on. 
     Components of the active cooling assembly  212  may be made of at least one of a metal and a polymer known in the art. More specifically, the coolant inlet  406 , the coolant path  408 , and the coolant outlet  410  may be made of any metal or alloy such as steel, copper, and so on, or any known polymer. However, materials with high heat transfer coefficients are especially favorable due to their ability to quickly absorb heat from the respective sensor unit. The coolant path  408  may be made of any metal or alloy such as steel, copper, and so on. Further, the housing  404  may be made of any metal or alloy such as steel, copper, and so on or any known polymer. In one embodiment, the housing  404  may be affixed to the body  210  of the inlet sensor unit  208  by any fastening method known in the art such as, welding, bolting, riveting, and so on. 
     INDUSTRIAL APPLICABILITY 
     During operation of the aftertreatment system  120 , the temperature of the NOx sensor may increase beyond a threshold temperature limit. As a result, the NOx sensor may provide inaccurate readings, and in some situations may experience failures. The active cooling assembly  212 ,  312  described herein, allows for controlling the temperature of the inlet and outlet NOx sensor  214 ,  314  within acceptable limits, thus improving sensor life and overall performance. The active cooling assembly  212 ,  312  allows for the circulation of the coolant flow therethrough, thereby reducing the temperature of the inlet and outlet sensor unit  208 ,  302  respectively via heat exchange with the coolant flow. The active cooling assembly  212 ,  312  utilizes a portion of the coolant from an existing cooling circuit present on the machine, by diverting the portion of the coolant to flow through the active cooling assembly  212 ,  312 . Accordingly, this may cause a reduction in complexity of the system design and may also cut down on an overall cost of otherwise having to include an additional cooling arrangement in the system. 
     A method  500  of working of the active cooling assembly  212  will now be described. Referring to  FIG. 5 , a flowchart of the method  500  is illustrated. The method  500  will be explained with reference to the inlet sensor unit  208 , but may also be used to explain the working of the outlet sensor unit  302  without any limitation. At step  402 , the active cooling assembly  212  is provided in association with the inlet sensor unit  208 . The inlet sensor unit  208  includes at least one of the inlet NOx sensor  214  and the inlet sensor circuitry  216 . 
     At step  504 , the coolant flow is received into the coolant inlet  406  of the active cooling assembly  212 . In one embodiment, the coolant flow is received from the aftercooler cooling circuit. In other embodiments, the coolant flow may be received from any other system such as, the intercooler cooling circuit, the engine cooling system, the transmission cooling system, the cooling system associated with the electrical system of the machine  100 , the operator cabin cooling system, any other Heating, Ventilation and Air Conditioning (HVAC) unit, and so on. 
     At step  506 , the coolant flow is circulated though the active cooling assembly  212 . More specifically, the coolant flow is circulated through the coolant path  408  provided in the housing  404  of the active cooling assembly  212 . At step  508 , the temperature of the inlet sensor unit  208  is controlled based, at least in part, by the circulation of the coolant flow therethrough. For example, during operation of the engine system  110 , the temperature of the coolant is relatively lower than the temperature of the inlet sensor unit  208 . During flow of the coolant through the coolant path  408 , the coolant may exchange heat with the inlet sensor unit  208  and provide cooling thereof. Further, the coolant flow is exited from the active cooling assembly  212  and returned to the aftercooler cooling circuit through the coolant outlet  410 . In the embodiment when the coolant flow is received into the active cooling assembly  212  from any other cooling circuit or system, the coolant flow is returned to the respective cooling circuit or system. Additionally, conduction of heat from the mounting surface of the aftertreatment system  120  or the exhaust conduit, as the case may be, into the sensor unit may be controlled by using at least one mounting leg  412  on the active cooling assembly  212 . 
     While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof