Patent Publication Number: US-2023139875-A1

Title: Vacuum-Based Leak Detection

Description:
TECHNICAL FIELD 
     This disclosure relates to leak detection in enclosures. In particular, this disclosure is related to leak detection for enclosures used in automobiles. 
     BACKGROUND 
     Automobile components may comprise a number of enclosures or components that provide a degree of protection from the outside elements during operation of the automobile. Such enclosures or components may require leak-proof functionality, for proper operation. For example, an electric vehicle comprises a battery that may be disposed within an enclosure to protect it from exposure to liquid, such as rain or water within a driving environment. In another example, a fuel tank (suitable for liquid fuels, such as gasoline or diesel) may be sealed prevent contamination of the fuel or a reduction in pressure within the fuel delivery to the motor. 
     Such components often utilize seals to prevent leakage into or out of the enclosure. These seals may be handled or removed from the enclosure during normal service functions. Upon completion of the service function, testing of the enclosure for leaks in the seals may be necessary to ensure proper functionality of the enclosure during normal operation. Conventional testing methods may rely upon complicated and time-consuming procedures, reducing the overall efficiency of a technician or a shop performing service to the enclosure. It would therefore be desirable for testing procedures to be made less complicated and less time consuming. 
     SUMMARY 
     One aspect of this disclosure is directed to a method of leak detection for an enclosure having a seal, an internal chamber, and a port in fluid communication with the internal chamber. The method comprises applying a vacuum pump to the port, activating the vacuum pump to apply a predetermined fixed vacuum pressure to the internal chamber, generating mass exchange rate data with a mass airflow sensor indicating a rate of mass exchange within the closure, and outputting an indication signal. The indication signal may comprise a leak indication signal indicating at least one leak in the seal is present if the rate of mass exchange is greater than an expected threshold value. The indication signal may otherwise comprise a seal indication signal indicating that no leak has been detected. In some embodiments of enclosures having multiple ports, all but one port may be sealed prior to applying the vacuum pump to the remaining port. 
     Another aspect of this disclosure is directed to a method of leak detection for an enclosure having a seal, an internal chamber, a valve, and a port in fluid communication with the internal chamber. The method comprises applying a vacuum pump to the port, activating the vacuum pump to apply a predetermined fixed vacuum pressure to the internal chamber, measuring the displacement of the valve while the vacuum pump is activated, and outputting an indication signal. The indication signal may comprise a leak indication signal indicating at least one leak in the seal is present if the displacement of the valve differs from an expected displacement value by an amount greater than an expected threshold displacement value. The indication signal may otherwise comprise a seal indication signal indicating that no leak has been detected. In some embodiments of enclosures having multiple ports, all but one port may be sealed prior to applying the vacuum pump to the remaining port. 
     A further aspect of this disclosure is directed to a method of leak detection for an enclosure having, a seal, an internal chamber, and a port in fluid communication with the internal chamber. The method comprises applying a vacuum pump to the port, activating the vacuum pump to apply a predetermined fixed vacuum pressure to the internal chamber, generating mass exchange rate data with a mass airflow sensor indicating a rate of mass exchange within the closure, increasing the pressure applied by the vacuum pump after activation until the mass airflow sensor indicates a predetermined pressure value, measuring the applied pressure of the vacuum pump when the mass airflow sensor indicates the predetermined pressure value, and outputting an indication signal. The indication signal may comprise a leak indication signal indicating at least one leak in the seal is present when the time required to achieve the internal pressure is greater than an expected threshold time value or the applied pressure is greater than an expected threshold pump pressure value. The indication signal may otherwise comprise a seal indication signal indicating that no leak has been detected. In some embodiments of enclosures having multiple ports, all but one port may be sealed prior to applying the vacuum pump to the remaining pump. 
     A yet further aspect of this disclosure is directed to a system for leak detection of an enclosure, the system utilizing a vacuum pump and a mass airflow sensor configured to measure vacuum pressure applied to the enclosure while the vacuum pump is activated. The vacuum pump may be coupled to the enclosure using a vacuum tube configured to detachably couple to a port of the enclosure. The system may further comprise a controller and memory operable to collate data generated by the mass airflow sensor, and generate data indicating the voltage applied to power the vacuum pump, or make time measurements. 
     The above aspects of this disclosure and other aspects will be explained in greater detail below with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a diagrammatic illustration of an enclosure leak-detection system. 
         FIG.  2    is a diagrammatic illustration of an enclosure leak-detection system for an enclosure having a valve. 
         FIG.  3    is a flowchart illustrating a first method of leak detection. 
         FIG.  4    is a flowchart illustrating a second method of leak detection. 
         FIG.  5    is a flowchart illustrating a third method of leak detection. 
         FIG.  6    is a flowchart illustrating a fourth method of leak detection. 
     
    
    
     DETAILED DESCRIPTION 
     The illustrated embodiments are disclosed with reference to the drawings. However, it is to be understood that the disclosed embodiments are intended to be merely examples that may be embodied in various and alternative forms. The figures are not necessarily to scale and some features may be exaggerated or minimized to show details of particular components. The specific structural and functional details disclosed are not to be interpreted as limiting, but as a representative basis for teaching one skilled in the art how to practice the disclosed concepts. 
       FIG.  1    is a diagrammatic illustration of a leak detection system configured for use with an enclosure  100 . Enclosure  100  may be configured to permit a degree of gaseous exchange but may not be suitable to permit exchange of liquids. In the depicted embodiment, enclosure  100  may comprise an enclosure suitable to house the battery of an electric vehicle. In such an embodiment, enclosure  100  may be configured to prevent exchange of liquid material into an internal chamber  102  of enclosure  100  from outside the enclosure. In such an embodiment, enclosure  100  may exhibit a degree of weatherproofing, preventing outside liquids such as rain, mud, puddles, or other environmental hazards from entering internal chamber  102  and potentially causing failures. A similar embodiment may be realized for other enclosures where the exchange of liquids from the outside is undesirable, such as fuel containers. 
     In the depicted embodiment, enclosure  100  comprises a number of ports  104  that provide fluid communication with internal chamber  102 . During normal operation, each of the ports  104  may provide necessary fluid communication to other components of the automobile. Each port may utilize a corresponding seal  106  to prevent leakage into or out of internal chamber  102 . In the depicted embodiment, ports  104   a  and  104   b  have similar dimensions, as do seals  106   a  and  106   b  respectively, but other embodiments may comprise any arbitrary number of ports  104 , each having an arbitrary configuration that operates with a corresponding seal  106  without deviating from the teachings disclosed herein. 
     During service, enclosure  100  may require disassembly, including removal of one or more of seals  106 . Upon reassembly after service, it is desirable to ensure that each of seals  106  has been properly re-assembled, and that none of seals  106  has been damaged. Improper reassembly or damage to seals  106  may result in an undesired leak. In conventional testing for leaks, a time-intensive leak detection process is frequently utilized. In the depicted embodiment, a leak tester  107  comprising a vacuum pump  109  may provide a faster test results. 
     Tester  107  comprises a vacuum pump  109 . Vacuum pump  109  may comprise an electric pump in the depicted embodiment, but other embodiments may comprise other configurations without deviating from the teachings disclosed herein. Advantageously, the operation of an electric vacuum pump  109  may be controlled electronically via a controller  111 . Controller  111  is configured to activate and control the power level supplied to vacuum pump  109 , and subsequently additionally configured to activate and control the pressure applied to any chamber in fluid communication with vacuum pump  109 . In the depicted embodiment, tester  107  further comprises a memory  112  that may provide executable instructions for controller  111  to execute, or may store data generated by other components of tester  107 . In the depicted embodiment, vacuum pump  109  is coupled with fluid communication to internal chamber  102  via a vacuum tube  113 . Vacuum tube  113  provides fluid communication between vacuum pump  109  and internal chamber  102  by detachably coupling to a port, such as port  104   a . Vacuum tube  113  defines a tube conduit  114  that enables fluid communication through the length of vacuum tube  113 . In the depicted embodiment, tester  107  comprises a tester seal  115  to ensure a proper pressure gradient can be achieved, but other embodiments may comprise a different configuration not having a distinct seal from vacuum tube  113  or vacuum pump  109  without deviating from the teachings disclosed herein. 
     Disposed within tube conduit  114  is a sensor  117 . In the depicted embodiment, sensor  117  comprises a mass airflow sensor configured to generate data indicating pressure within tube conduit  114 , the rate of exchange of gaseous matter through tube conduit  114 , or other data indicating mass or pressure conditions within tube conduit  114 . Controller  111  may comprise a clock component operable to generate time-based data in conjunction with the data generated by sensor  117 . 
     In the depicted embodiment, enclosure  100  comprises a second port  104   b  that must be sealed prior to the testing operation in order to ensure an accurate reading of pressure within internal chamber  102 . In such embodiments, the system may utilize a stopper  119  inserted into port  104   b  along direction  121 . The dimensions and composition of stopper  119  may be defined in order to ensure compatibility with the particular dimensions and operability of port  104   b  when pressure is applied. In the depicted embodiment, stopper  119  may comprise a conic section composed of a rubber polymer that forms an airtight seal with seal  106   b , but other embodiments may comprise other configurations without deviating from the teachings disclosed herein. In other embodiments having different or additional ports  104 , a plurality of stoppers  119  having different configurations may be utilized to accommodate the specifications of the respective ports in those embodiments without deviating from the teachings disclosed herein. 
     In the depicted embodiment, once vacuum tube  113  has been coupled to port  104   a  and port  104   b  has been effectively sealed using stopper  119 , pressure may be applied to internal chamber  102  by activating vacuum pump  109 . In the depicted embodiment, the pressure applied by vacuum pump  109  is electrically controlled by controller  111 : larger voltages applied by controller  111  to vacuum pump  109  correspond to higher pressure gradients generated by vacuum pump  109 . While pressure is applied, mass airflow sensor  117  generates pressure data indicating pressure within the space defined by internal chamber  102  and tube conduit  114 . The pressure date may additionally indicate the rate of mass exchange as atmosphere is removed from internal chamber  102 . 
     Once pressure data is generated, controller  111  may compare the pressure data to expected values of pressure or rate of mass exchange. If the pressure within the internal chamber  102  is found to be outside of the expected values by a degree larger than a specified threshold, controller  111  may generate a leak indication signal indicating that a leak has been detected within enclosure  100 . If the rate of mass exchange deviates from an expected value by a degree that has a magnitude larger than a specified expected threshold rate value, controller  111  may generate the leak indication signal. If the pressure and rate of mass exchange are found to be within specified expected values, controller  111  may generate a seal indication signal indicating that no leak has been detected. Controller  111  may output the respective generated signal to a human-user interface (not depicted) to alert a user whether a leak has been detected or a leak has not been detected. The human-user interface may comprise a visual indicator, audible indicator, display screen, or any other feedback element recognized by one of ordinary skill without deviating from the teachings disclosed herein. Such a human-user interface may comprise input element to permit a user to interact with controller  111 , such as a touchscreen, keyboard, dipswitch, or any other element for electronic input recognized by one of ordinary skill without deviating from the teachings disclosed herein. In the depicted embodiment, the human-user interface may comprise a touchscreen display, light-based visual indicators, and an audio speaker, but other embodiments may comprise other configurations without deviating from the teachings disclosed herein. 
     During the testing operation, it may take a brief period of time for the internal chamber  102  to achieve the desired pressure, even under nominal operating circumstances. Controller  111  may delay generation of an indication signal until a sufficient time has elapsed that the measurements of mass airflow sensor  117  would be considered valid under normal conditions. For example, an indication signal may not be generated until a predetermined number of measurements have been acquired by the mass airflow sensor  117 , or until the measurements have be consistent for a designated period of time. Advantageously, utilization of the mass exchange rate data may be considered almost immediately upon activation of vacuum pump  109 , yielding a faster response to generate an indication signal. 
     Other data derived from the measurements of mass airflow sensor  117  may be utilized to detect a leak. In some embodiments, the amount of time that passes to achieve an expected pressure within internal chamber  102  may be compared to an expected time value, and if the measured time deviates from the expected value beyond an expected threshold time value, a leak may be indicated. In some embodiments, the amount of pressure applied by the vacuum pump  109  to achieve a desired pressure within internal chamber  102  may be considered. In such embodiments, the applied pressure of vacuum pump  109  corresponds to the voltage applied to vacuum pump  109  by controller  111 . In instances wherein the voltage applied deviates from an expected voltage, the applied pressure being generated by vacuum pump  109  is understood to be different than what is observed within internal chamber  102 . If the applied pressure of the vacuum pump  109  deviates from an expected pump pressure value beyond a threshold pump pressure value, controller  111  may indicate a leak. 
     The specified expected values of pressure, applied pressure, applied voltage, or mass exchange rate are expected to be correlated to the particular configuration of enclosure  100 . These expected values may be different for different configurations of enclosure  100 , and the different expected values may be stored in memory  112 , such as in a lookup table accessible by controller  111 . In embodiments where these deviations are accessible by controller  111 , tester  107  advantageously remains functional across all specified enclosure configurations. In the depicted embodiment, different data for new enclosure configurations may be input by a user utilizing the human-machine interface (not shown), and stored in memory  112 . Already-stored configurations of enclosures  100  may be utilized by referencing the particular expected values in memory  112  prior to the testing operation, increasing the speed and flexibility of testing using tester  107 . 
     Tester  107  may be configured to utilize other methods for leak detection.  FIG.  2    depicts tester  107  in use with an embodiment of enclosure  100  wherein port  104   b  (see  FIG.  1   ) is sealed by a valve  204 . In such an embodiment, sealing of valve  204  may not be accomplished with an external stopper such as stopper  119 , and instead the valve itself may be self-sealing when pressure is applied. Alternately, the calculations of expected values of pressure, applied pressure, applied voltage, or mass exchange rate may be adapted to accommodate the presence of valve  204 . 
     In the depicted embodiment, the physical condition of valve  204  may be monitored during application of pressure by vacuum pump  109  for expected conditions thereof. By way of example, and not limitation, valve  204  may comprise a solenoid valve having a valve seal  206  that is spring-loaded and operable for a degree of motion along an axis  209 . When a vacuum pressure is applied to internal chamber  102 , valve seal  206  may become displaced along axis  209  to a degree correlated to the magnitude of applied pressure. If this displacement deviates from an expected displacement, then a leak may be indicated. If a leak is indicated, controller  111  may generate a leak indication signal for output to a user of tester  107 . 
     In the depicted embodiment, tester  107  further comprises a displacement sensor  217  operable to measure the position of valve seal  206 . Displacement sensor  217  is further in data communication with controller  111  to report the measurements as displacement data. Multiple such measurements may additionally be controller  111  to generate data describing the rate of change in the displacement of valve seal  206 . In the depicted embodiment, displacement sensor  217  may comprise an optical sensor, but other embodiments may comprise different types of sensors without deviating from the teachings disclosed herein. In some embodiments, a user may measure the displacement of valve seal  206  manually and provide the displacement to controller  111  via the human-machine interface (not shown) without deviating from the teachings disclosed herein. 
     For a known configuration of enclosure  100  having one or more valves  204 , the expected displacement of valve seal  206  for a given pressure, applied pressure, applied voltage, or mass exchange rate may be stored in memory  112  in a lookup table. These expected values may be utilized by tester  107  to determine if the displacement of valve seal  206  deviates from the expected displacement value by an amount greater than an expected threshold displacement value. Different enclosure configurations may correspond to different sets of expected values without deviating from the teachings disclosed herein. different data for new enclosure configurations may be input by a user utilizing the human-machine interface (not shown), and stored in memory  112 . Already-stored configurations of enclosures  100  may be utilized by referencing the particular expected values in memory  112  prior to the testing operation, increasing the speed and flexibility of testing using tester  107 . 
       FIG.  3    is a flowchart illustrating a method of leak detection for an enclosure using the teachings disclosed herein. The method beings at step  300 , where the enclosure is prepared for a vacuum-based leak detection. Preparation of the enclosure may comprise coupling a vacuum tube to a port of the enclosure, and inserting stoppers into one or more other ports of the enclosure as appropriate for the particular configuration of the enclosure under test. Once the enclosure is properly prepared, the method proceeds to step  302 , where a vacuum pump is activated to apply a vacuum pressure to the enclosure. The method then proceeds to step  304  to generate data measuring the conditions of the enclosure under the applied pressure. In this embodiment, the generated data may comprise a measurement of the rate of mass exchange by a mass airflow sensor. After collection of generated data, the method proceeds to step  306  where the generated data is compared to an expected threshold rate value. If the measured exchange rate data is within specified parameters, the method proceeds to step  308  where the method ends with the generation and output of a seal indication signal indicating that a leak was not detected. If the measured exchange rate data deviates from the expected values by an amount greater than a specified threshold value, the method instead proceeds to step  310 , where the method ends after the generation and output of a leak indication signal indicating the detection of a leak. 
       FIG.  4    is a flowchart illustrating a method of leak detection for an enclosure using the teachings disclosed herein. In this embodiment, the subject enclosure is understood to comprise a valve having measurable displacement features (such as valve  204 ; see  FIG.  2   ). The method beings at step  400 , where the enclosure is prepared for a vacuum-based leak detection. Preparation of the enclosure may comprise coupling a vacuum tube to a port of the enclosure, and inserting stoppers into one or more other ports of the enclosure as appropriate for the particular configuration of the enclosure under test. Once the enclosure is properly prepared, the method proceeds to step  402 , where a vacuum pump is activated to apply a vacuum pressure to the enclosure. The method then proceeds to step  404  to generate data measuring the conditions of the enclosure under the applied pressure. In this embodiment, the generated data may comprise a measurement of the displacement of a valve of the enclosure while pressure is applied. After collection of generated data, the method proceeds to step  406  where the generated data is compared to an expected displacement value. If the measured displacement data is within specified parameters, the method proceeds to step  408  where the method ends with the generation and output of a seal indication signal indicating that a leak was not detected. If the measured displacement data deviates from the expected values by an amount greater than a specified threshold value, the method instead proceeds to step  410 , where the method ends after the generation and output of a leak indication signal indicating the detection of a leak. 
       FIG.  5    is a flowchart illustrating a method of leak detection for an enclosure using the teachings disclosed herein. The method beings at step  500 , where the enclosure is prepared for a vacuum-based leak detection. Preparation of the enclosure may comprise coupling a vacuum tube to a port of the enclosure, and inserting stoppers into one or more other ports of the enclosure as appropriate for the particular configuration of the enclosure under test. Once the enclosure is properly prepared, the method proceeds to step  502 , where a vacuum pump is activated to apply a vacuum pressure to the enclosure. The method then proceeds to step  504  to generate data measuring the conditions of the enclosure under the applied pressure. In this embodiment, the generated data may comprise a measurement of the vacuum pressure within an internal chamber of the enclosure as observed by a mass airflow sensor. The generated data may further comprise a measurement of the amount of time elapsed before the internal chamber achieves an expected pressure as observed by the mass airflow sensor. After collection of generated data, the method proceeds to step  506  where the generated data is compared to an expected threshold pressure value. If the pressure data is within specified parameters, the method proceeds to step  508 . If the measured pressure data deviates from the expected values by an amount greater than a specified threshold value, the method instead proceeds to step  510 , where the method ends after the generation and output of a leak indication signal indicating the detection of a leak. If the method proceeds to step  508 , the measured data is compared to an expected value for the amount of time required to achieve an expected pressure the internal chamber as observed by the mass airflow sensor. If the pressure time deviates from the expected value by an amount greater than a specified time value, the method proceeds to step  510 , where the method ends after the generation and output of a leak indication signal indicating the detection of a leak. If the pressure time data is within specified parameters, the method proceeds instead to step  512 , where the method ends after generating and outputting a seal indication signal indicating that no leak has been detected. In the depicted embodiment, the actions of step  506  precede those of step  508 , but other embodiments may reverse this order or execute the steps concurrently without deviating from the teachings disclosed herein. 
     In some embodiments, a leak detection method may comprise a combination of comparisons of measured data to detect a leak.  FIG.  6    is an illustration of such an embodiment utilizing multiple checks against leaks. 
       FIG.  6    is a flowchart illustrating a method of leak detection for an enclosure using the teachings disclosed herein. In this embodiment, the subject enclosure is understood to comprise a valve having measurable displacement features (such as valve  204 ; see  FIG.  2   ). The method beings at step  600 , where the enclosure is prepared for a vacuum-based leak detection. Preparation of the enclosure may comprise coupling a vacuum tube to a port of the enclosure, and inserting stoppers into one or more other ports of the enclosure as appropriate for the particular configuration of the enclosure under test. Once the enclosure is properly prepared, the method proceeds to step  602 , where a vacuum pump is activated to apply a vacuum pressure to the enclosure. The method then proceeds to step  604  to generate data measuring the conditions of the enclosure under the applied pressure. In this embodiment, the generated data may comprise a measurement of the rate of mass exchange by a mass airflow sensor, a measurement of the displacement of a valve of the enclosure while pressure is applied, a measurement of the vacuum pressure within an internal chamber of the enclosure as observed by a mass airflow sensor, and a measurement of the amount of time elapsed before the internal chamber achieves an expected pressure as observed by the mass airflow sensor. Each of these data may be utilized in a distinct leak detection check, providing a robust leak detection for the enclosure. 
     After collection of generated data, the method proceeds concurrently to each of steps  606 ,  608 ,  610 , and  612  where the generated data is compared to one of a number of expected threshold values. At step  606 , the measured mass exchange rate is compared to an expected rate value. At step  608 , the displacement of the valve is compared to an expected displacement value. At step  610 , the pressure inside an internal chamber of the enclosure for the active applied pressure of the vacuum pump is compared to an expected pressure value for the same applied pressure. At step  612 , the time to achieve an expected pressure within the internal chamber for the applied pressure of the vacuum pump is compared to an expected pressure time value for the same applied pressure. The results of each of steps  606 ,  608 ,  610 , and  612  are collated and considered at step  614 . If any of the measured data values deviated from their respective expected counterparts by a degree larger than a threshold value specified for each comparison, that comparison is considered to be unsuccessful, indicating a potential leak. If all of the comparisons are found to be within the specified operating parameters, the method proceeds to step  616 , where a seal indication is generated and output to a user, indicating that no leak was detected. If any of the comparisons are found to be unsuccessful at step  614 , the method instead proceeds to step  618 , where a leak indication signal is generated and output indicating that a leak has been detected. 
     In the depicted embodiment, the comparisons of steps  606 ,  608 ,  610 , and  612  are compared concurrently, but these comparisons may be performed in any sequential order without deviating from the teachings disclosed within. By way of example, and not limitation, an alternative embodiment could sequentially perform steps  606 ,  608 ,  610  and  612  in that order. If the comparison is found to be unsuccessful at any given step, the method could immediately proceed to  618 , rather than waiting for any other comparison to be performed. This arrangement may advantageously minimize the amount of time to perform the method of  FIG.  6    in instances when a leak is detected. In such embodiments, step  614  may be omitted without deviating from the teachings disclosed herein. 
     The respective steps  606 ,  608 ,  610 , and  612  may be applied in any combination of sequential and concurrent operation without deviating from the teachings disclosed herein. By way of example, and not limitation, the method may sequentially perform the comparisons of step  606  and step  608 , then in a final operation of the comparison sequences perform steps  610  and  612  concurrently. Other embodiments may comprise other combinations without deviating from the teachings disclosed herein. 
     In some embodiments, one or more of steps  606 ,  608 ,  610  and  612  may be omitted without deviating from the teachings disclosed herein. By way of example, and not limitation, a version of the method of  FIG.  6    that omits steps  608 ,  610 , and  612  would be functionally very similar to the method of  FIG.  3   . Any such combination of the steps of  606 ,  608 ,  610  and  612  may be selectively combined by a user performing the tests with a dedicated device, such as tester  107  (see  FIG.  1   ;  FIG.  2   ). By way of example, and not limitation, a user subjecting an enclosure having no valves exhibiting displacement may selectively omit step  608  from the method in order to save time in the leak detection without deviating from the teachings disclosed herein. In some embodiments, a dedicated testing device, such as tester  107 , may have stored in a memory (such as memory  112 ; see  FIG.  1   ) pre-set leak detection methodologies that are found to be suitable with known configurations of enclosures. 
     While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the disclosed apparatus and method. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure as claimed. The features of various implementing embodiments may be combined to form further embodiments of the disclosed concepts.