Abstract:
A leak detecting apparatus is provided that tests for leaks in closed systems such as the air intake system of an internal combustion engine. The system connects to a conventional air supply that provides air under pressure. The air from the air supply is routed through a fluid tank where the air is directed against the fluid thereby generating fog. The fluid is preferably a mineral oil. The fog is routed out of the apparatus and is fed into the system for detecting leaks. Leaks are observed visually when the fog escapes from cracks or fissures in the system being tested. In order to aid in the observation of the fog escaping from the leaks, a light reflective pigment is added to the fluid thereby making the fog easier to observe upon the application of white light to the fog.

Description:
PRIORITY CLAIM  
       [0001]     The present application claims priority to Canadian Patent Application No. ______ filed Aug. 27, 2003, the entirety of which is hereby incorporated by reference.  
       FIELD OF THE INVENTION  
       [0002]     The invention relates to an apparatus for generating vapour and delivering the vapour under pressure to a closed system to test for leaks in the closed system.  
       BACKGROUND  
       [0003]     Devices for detecting leaks have existed for many years. These devices typically involve the introduction of a visible vapour such as smoke or fog into the system being tested. Leaks would then be detected visually as the vapour escaped through tiny cracks or holes in the system. These devices are useful for testing for leaks in hydraulic or gas systems, air craft pipe systems and pipe systems in ships for example.  
         [0004]     Many leak detector apparatuses employ smoke to test for leaks. For example, U.S. Pat. No. 5,107,698 describes an apparatus for testing an internal combustion engine for vacuum leaks. For example, the apparatus generates smoke in a chamber and pumps the smoke into the intake manifold of a vacuum system in an internal combustion engine. Leaks are detected upon the escape of smoke. The fact that this apparatus produces smoke is problematic in that smoke is potentially toxic to workers operating the apparatus. Also, the introduction of smoke into the atmosphere causes environmental concerns.  
         [0005]     To address this problem, other apparatuses have been developed to test for leaks with the use of smoke and ultraviolet dye as a vapour. However, these apparatuses require the vapours generated to be heated. They therefore employ heat elements to generate vapours for detection purposes. U.S. Pat. No. 6,392,227 for example discloses a system that generates a marker vapour that incorporates a fluorescent substance. The vapour stain is detected using ultraviolet light when escaping from a leak in the system being tested. This system however requires that the vapour be heated. This is a disadvantage because of the increased energy required to operate the device. Also, the heating element can be a fire hazard. In the event of a malfunction in the heating element circuit, a fuel tank explosion is a potential hazard in testing systems such as evaporative emissions systems in the automotive industry. To reduce or eliminate the possibility of combustion, an inert gas such as nitrogen is currently required to propel the smoke in these types of machines.  
         [0006]     There is therefore a need for an apparatus for testing leaks in a system being tested that that does not employ smoke and that does not require that the medium being used to detect and indicate the location of leaks to be heated.  
         [0007]     It is an object of the present invention to provide an apparatus that is effective for detecting leaks in systems wherein the apparatus generates a vapour other than smoke that does not need to be heated.  
         [0008]     It is a further object of the present invention to provide an apparatus for detecting leaks that is connectable to an air supply.  
         [0009]     It is a further object of the present invention to provide an apparatus for detecting leaks that employs fog as a medium under pressure for detecting leaks.  
         [0010]     It is yet a further object of the present invention to provide a leak detector that provides a higher volume of vapour to a system being tested and a higher fill rate than conventional existing leak detectors.  
         [0011]     It is a further object of the present invention to provide a leak detecting apparatus that applies preset pressure ranges of detection vapour to the system being tested for safe and reliable detection of leaks.  
       SUMMARY OF THE INVENTION  
       [0012]     The invention provides a leak detector that is either connectable to an external air supply or has an internal air supply in the form of an internal pump for example. The air from the air supply enters a conduit that passes through a vapour tank. A vapour is delivered, by another conduit, from the vapour tank to the system being tested. The vapour is generated when fluid located in the vapour tank contacts air from the conduit. Heating is not required for the production of vapour. A preferred fluid is a mineral oil based fluid. The vapour may optionally include a light reflective pigment in dispersion for easier visual detection.  
         [0013]     According to one aspect of the present invention, there is provided a leak detector for connection to an air supply. The leak detector is adapted to deliver vapour under pressure to a system for detecting leaks in the system. The leak detector comprises: 
        a tank defining a fluid chamber for holding a quantity of fluid, the tank further defining an inlet and outlet;     a first conduit for delivering air from the air supply to the fluid chamber. The first conduit has a first end for attachment to the air supply and a second end received in the inlet. The second end of the conduit is positioned to direct a flow of air from the air supply into the fluid chamber against the fluid thereby generating a vapour; and     a second conduit for delivering the vapour from the fluid chamber to the closed system. The second conduit has a first end received in the outlet and a second end receivable in the system being tested for delivering vapour under pressure to the system for testing for leaks in the system.        
 
         [0017]     According to another aspect of the present invention there is provided a leak detector for connection to an air supply, the leak detector being adapted to deliver a vapour under pressure to a system for detecting leaks in the system, the leak detector comprising: 
        a housing defining a chamber. The housing further defines first and second openings;     a tank located in the chamber, the tank defining a fluid chamber for holding a quantity of fluid. The tank further defining an inlet and outlet;     a first conduit for delivering air from the air supply to the fluid chamber. The first conduit has a first end for attachment to the air supply and a second end received through both the first opening of the chamber and the inlet of the fluid chamber for delivering air from the air supply to the fluid chamber. The second end of the first conduit is positioned in the fluid tank to direct air against the fluid whereby a vapour is generated in the tank by contact of the air against the fluid; and     a second conduit located in the chamber for delivering vapour from the fluid chamber to the system. The second conduit has a first end received in the outlet of the fluid chamber and a second end received through the second opening of the housing for connection to the system;        
 
         [0022]     According to yet another aspect of the present invention, there is provided a leak detector for delivering vapour under pressure to a system for detecting leaks in the system, the leak detector comprising: 
        a fluid tank defining a chamber therein, the fluid tank defining first and second openings;     a vapour producing fluid located in the fluid tank;     an air supply;     a first conduit for delivering air from the air supply to the fluid tank, the first conduit having a first end attached to the air supply and a second end received in the first opening of said fluid tank; and     a second conduit for delivering the vapour from said fluid tank to the system, the second conduit having a first end received in the second opening of the fluid tank and a second end receivable in said system.       
 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0028]      FIG. 1  is a front perspective view of a preferred embodiment of the present invention;  
         [0029]      FIG. 2  is a top view of the preferred embodiment shown in  FIG. 1 ;  
         [0030]      FIG. 3  is a bottom perspective view of the preferred embodiment with a portion cut away to show internal features of the preferred embodiment;  
         [0031]      FIG. 4  is a cross sectional view taken along lines  4 - 4  of  FIG. 3 ; and  
         [0032]      FIG. 5  is a schematic depiction of the preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0033]     Leak detector apparatus  1  includes a housing  2 . The housing  2  has a front portion  5 , a top portion  7  and side portions  17 ,  19 . The housing  2  defines a chamber  80  formed therein. An air supply conduit  8  is received through side portion  17  of housing  2 . Air supply conduit  8  is preferably a flexible hose. The air supply conduit  8  has a first end  3  which is preferably attachable to a conventional external air supply and a second end  9  which is received through the housing  2  for delivering air under pressure into the chamber  80 . Although it is preferable for the apparatus  1  to be used in conjunction with an external air supply, alternate embodiments that employ an internal air supply located in the housing  2  such as an internal pump are within the scope of the present invention.  
         [0034]     An outflow conduit  12  which is preferably a flexible hose is received through side  19  of the housing  2 . The outflow conduit  12  has a first end  10  which is received through the housing  2  for communication with the interior chamber  80 . The outflow conduit  12  has a second end  11  for connection to a system being tested for leaks. The connection is preferably accomplished by virtue of air supply coupling  6 .  
         [0035]     A flow gauge  54  is located on the front portion  5  of housing  2 . A flow lamp  16  and a polarity lamp  18  are also located on the front of the housing  2 . A foot switch port  40  is located on the front of the housing for connection to a switch by way of a conventional attachment. The switch would preferably be a bulb switch. A pressure gauge display  36  is also located on the front of the housing  2 .  
         [0036]     As shown in  FIGS. 1 and 2 , a handle  14  is preferably attached to the top surface of  7  of housing  2  for the purpose of portability. A knob  44  for a timer  65  (shown in  FIG. 3 ) is located on the top surface  7 . A knob  28  is located on the top surface  7 . The knob  28  operates air pressure regulator  70  (shown in  FIG. 3 ). Mode calibration switch actuator  32  is located on top surface  7 . Actuator  7  interacts with air valve  56  (shown in  FIG. 3 ). The mode calibration switch actuator is movable between a first position which is preferably marked 1 psi, a second position which is unmarked and a third position which is preferably marked 3 psi.  
         [0037]     Electrical line  20  is connected to the leak detector  1  through the top surface  7  of housing  2 . Leads  24  are attached to the electrical line and connect to the poles of a conventional battery. A plurality of pegs  48  may be attached to the top surface  7 . Each of the pegs  48  is adapted to receive an adapter  50 . Each adapter  50  has an opening  51  for engaging a peg  58 . The opening of adapter  50  may also engage the coupling  6  for the purposes of engaging certain types of systems that are to be tested for leaks but which do not fit coupling  6 .  
         [0038]     The internal features of the leak detector are shown in  FIG. 3 . The internal components of the leak detector are located within the chamber  80 . Vapour tank  60  is located in the chamber  80 . The vapour tank  60  contains a fluid  78  depicted in  FIG. 5 . The fluid is preferably a mineral oil. The preferred mineral oil based fluids for the present invention are zinc sulphide compounds and rare earth compounds. However, other fluids that are capable of generating a vapour upon contact with a stream of air are within the scope of the invention. For the purposes of the present invention, the meaning of the word air includes all gases including inert gases such as nitrogen. The meaning of vapour includes fog and smoke according to the present invention. The mineral oil preferably includes a light reflective pigment using a surfactant to create a smaller sized pigment in a stable dispersion. The preferred light reflective pigment is rare earth alkaline aluminate photoluminescence pigment. The preferred light reflective pigments are zinc sulphide compounds and rare earth compounds. However, other light reflective pigments may also be used. Other additives to the fluid that improve the visibility and detection of the vapour generated from the fluid including fluorescent substances detectable by ultraviolet light are also within the scope of the invention.  
         [0039]     The internal features of the vapour tank  60  are shown in  FIG. 4 . The vapour tank  60  defines a chamber  86 . The pre-vapour fluid  78  is received in the chamber  86 . Conduit  64  is received in the vapour tank  60  and is connected to spray nozzle conduit  74 . Spray nozzle  76  is attached to an end of spray nozzle conduit  74 . A well  4  is attached below the nozzle  76 . The well  4  gathers fluid and is also used to fill the vapour tank  60  initially during assembly. A well plug  72  is attached to vapour tank  60 .  
         [0040]     Conduit  8  is received through the side  17  of housing  2 . Hoses  21 ,  22 ,  23 ,  25  transport air and/or fog through the apparatus  1 . Preferably, the hoses are made of nylon and are ¼″ in diameter. The hoses are preferably flexible and have preferably push to connect fittings. Conduit  8  connects to hose  21 . The hose  21  extends to and is received in air pressure regulator  70 . Hose  22  connects air pressure regulator  70  to flow gauge  54 . Hose  23  is connected to flow gauge  54  and extends to and is connected to air valve  56 . Conduit  64  connects the air valve  56  to the vapour tank  60 . Hoses,  21 ,  22 ,  23  and conduit  64  form a first conduit for delivering air from the air supply to the fluid chamber.  
         [0041]     Hose  25  is connected to exhaust air outlet  82  and extends between exhaust air outlet  82  and pressure gauge  38 . Hose  25  is received in pressure gauge  82 .  
         [0042]     Vapour tank outlet  26  connects to cross-piece  58 . The cross piece  58  is connected to exhaust air outlet  82 . The cross piece  58  is also connected to exterior outlet  42 . The vapour tank outlet  26 , the exterior outlet  42  and the outflow conduit  12  form a second conduit for delivering the vapour from the fluid chamber  60  to the system to be tested for leaks.  
         [0043]     Rear portions of the flow lamp  16  and the polarity lamp  18  are located in the chamber  80 . Foot switch  30  is located in the chamber  80  as is relay assembly  66  and relay plug  68 . Receptacle  84  for electrical cord  20  is located in the chamber  80 . Rear portion of the timer  65  is located in the chamber  80 . Spade connector  62  is attached to the timer  65 .  
         [0044]     Mode calibration switch  34  is attached to attachment  88  of cross-piece  58 . Pressure limiting switch  52  is attached to attachment  90  of cross-piece  58 .  
         [0045]     The operation of the preferred embodiment of the leak detector is shown schematically in  FIG. 5 . Air supply conduit  8  is connected to a conventional air supply known in the art. Air is introduced into air supply conduit  8 . The air flows from the air supply conduit  8  into hose  21 . The air then flows through hose  21  to the air pressure regulator  70 . The air pressure regulator  70  controls the pressure of the air that enters the apparatus  1 . The air pressure is generally in the range of 0-15 psi entering the apparatus  1 . The air flows through the air pressure regulator  70  and then through hose  22  into the flow gauge  54 . The flow gauge  54  provides a visual display of the rate of air flow. The display is preferably in the unit of standard cubic feet per hour (SCFH). Air from the flow gauge  54  flows through hose  23  to air valve  56 . Air valve  56  is preferably an electronically operated on/off valve. The valve  56  functions to either allow or prevent the flow of air through the valve. The air valve  56  is operated by either the timer  65  which is preferably electrically controlled or manually operated by foot switch  30 . The foot switch  30  control can be located at distance from the apparatus  1  so that the operator may shut off the apparatus  1  when checking for leaks at a distance from the apparatus  1 .  
         [0046]     A check valve may optionally be included between the air valve  56  and the spray nozzle  76 . The check valve ensures that the liquid in the vapour tank cannot flow back under pressure. Air flows from hose  23  through conduit  64  and then through the spray nozzle conduit  74 . Air from the conduit  74  flows through the spray nozzle  76  which directs the air flow against the fluid  78 . The spray nozzle is preferably configured to spray air at a specific angle on the fluid to most efficiently disperse the fluid as vapour. The vapour generated is preferably fog.  
         [0047]     Vapour under pressure flows from the vapour tank  60  through conduit  26  to cross piece  58 . The apparatus preferably includes the switches  34 ,  56  which are pressure activated switches that can be preferably set to 1 psi and 3 psi respectively using mode calibration switch actuator  32  as shown in  FIGS. 1 and 2 . These preset switch values are pre-set by the operator to inhibit the opening of air valve  56  by electrical connection between switches  34 ,  56  and air valve  56 . Alternate embodiments of the invention that do not include switches  34 ,  56  are within the scope of the present invention. Vapour flows out of the apparatus through outlet conduit  42  to outflow conduit  12 . Outflow conduit  12  is preferably a flexible, clear  6 ′ inch hose. Coupling  6  is adapted to connect with an inlet of the system being tested in order to deliver vapour under pressure to the system being tested. Adapter  50  may be attached to coupling  6  in order to fit inlets of other systems being tested that are not sized to securely accept the coupling  6 .  
         [0048]     Leaks in the system are detected visually upon the escape of vapour from cracks, fissures and other leaks that may be present in the system being tested. The preferred vapour which is a mineral oil based fog is light grey in colour. The fog is more easily observed when white light source is applied on the fog. White light may be applied by any type of light source such as a 50 watt halogen lamp. The light reflective pigment in the fog makes it more readily observable when light is applied to the fog.  
         [0049]     The external pressure gauge  38  provides a reading of the amount of pressure that that is being applied to the system being tested by measuring the pressure of the fog leaving through the vapour tank outlet  26 . This allows the operator to ensure that a pressure is not applied that exceeds a maximum pressure rating that the system being tested can tolerate. Once a pre-set applied pressure of for example 1 psi or 3 psi is reached, the pressure switch  52  prevents the further application of fog under pressure to the system being tested. If there is a leak, the system will therefore lose pressure due to the leak. Pressure switch  52  will not be activated in such a case and the apparatus  1  will resume applying vapour under pressure to the system being tested in an automatic fashion. This continuous application of vapour under pressure will alert the operator to the fact a leak is present in the system being tested. The flow gauge  54  and flow lamp  16  also serve to alert the operator to the fact that there is a continuous flow of vapour under pressure and therefore a leak. The flow lamp  16  is illuminated when fog under pressure is flowing out of the apparatus  1  through vapour tank outlet  26 . The flow lamp  16  goes out when the pre-set pressure of preferably either 1 psi or 3 psi is achieved.  
         [0050]     Hose  25  connects outlet  46  to the inlet  100  of the pressure gauge  38 . Fog under pressure emanating from vapour tank outlet  26  flows through the hose  25  to the pressure gauge  38 .  
         [0051]     The pressure reading is displayed on pressure gauge display  36 .  
         [0052]     The polarity lamp  18  is illuminated when the leads  24  are connected to the correct poles of a battery.  
         [0053]     There are two types of modes available. One mode is the manual mode while the other mode is the pressure limiting mode. The relay assembly  66  functions to change a ground path for each of the two modes. When the mode switch  32  is in the centre position corresponding to the manual mode, the ground path is preferably supplied from a pin (not shown) of the relay. This ground path by-passes the two pressure limiting switches  34 ,  52 . When the mode switch  32  is in either of the two pressure-limiting positions of 1 or 3 psi, the relay assembly  66  is switched to provide a ground path through the pin. The two different pressure limiting modes are differentiated by the use of a series of diodes ensuring that only one of the two pressure limiting modes may be selected at a time.  
         [0054]     It is necessary to calibrate the apparatus  1  before use in order to ensure that there are no internal leaks in the apparatus  1 . The mode calibration switch actuator  32  is switched to the middle position between the 1 psi setting and the 3 psi setting in order to put the apparatus  1  in a calibration mode. Between 10 psi and 15 psi is applied to the apparatus  1 . An appropriate flow rate is set. The flow rate may be for example 20 SCFH.  
         [0055]     The calibration achieves two purposes. Firstly the calibration of the apparatus  1  provides an internal leak test. Because the apparatus is used to locate extremely small leaks, it is necessary to prove that any leak that has been located by the apparatus is outside the apparatus and is not an internal leak. Calibration is also necessary to determine an appropriate flow rate.  
         [0056]     The calibration is performed in the manual mode. The apparatus is attached to an air supply and preferably a conventional automotive 12-volt battery. The timer  44  is preferable set to 5 minutes or less enabling airflow. The pressure regulator  70  is turned up using knob  28  to indicate 10 psi on the air pressure gauge. During calibration of the apparatus, outflow conduit  12  is not installed in the apparatus. This causes the internal air pressure to rise to 10 psi at which point the timer  44  is turned counter clockwise to an off position. If there is an internal leak, the pressure registered on the air pressure gauge will drop, indicating the leak. If there is no internal leak, the pressure gauge will maintain the initial reading of 10 psi. Once it is established that there is no internal leak, testing of the system for leaks can begin.  
         [0057]     For optimal vapour generation an airflow rate of at least 5 SCFH is required. Since the airflow rate is directly related to the air pressure regulator setting, the calibration setting of 10 psi provides an airflow rate between 15 and 25 SCFH depending on the inlet air supply. This ensures that there will be good quality vapour based on the airflow rate, and that the pigment, if used will quickly mix with the mineral oil fluid at the outset.  
         [0058]     While the preferred embodiment has been described, those skilled in the art will appreciate that numerous modifications may be made to the embodiments described herein without departing from the spirit of the invention.