JP2574461B2 - Apparatus and method for detecting leaks in a fluid-containing chamber - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel tank leak detecting device.

2. Description of the Related Art The importance of detecting fuel tank leaks has long been recognized in the automotive industry. Unfortunately, current methods of detecting fuel tank leaks are either not suitable for the automotive industry's production line system or are not sufficiently reliable. It is an object of the present invention to provide a method and apparatus for detecting fuel tank leaks which is very accurate and reliable and which can be used in a manufacturing plant situation.

The current method of fuel tank leak detection used in the automotive industry is the "bubble" method. The fuel tank is submerged and pressurized, and then inspected to see if air bubbles leak from the tank. This method has several major disadvantages, the most important being the speed and reliability of the test. In operation, the speed and reliability of this bubble method are mercilessly linked. The bubble test is performed manually, whereby a human operator monitors the bubbles emanating from the fuel tank submerged in water. Therefore, the accuracy of the test depends on the attention of the test investigator. The human element of this test cannot be easily removed because it is difficult for an automated unit to detect the bubbles emanating from the tank. In addition, the bubble test is limited by its sensitivity, the human eye can only recognize bubbles with a volume of more than 0.04 cm ^{3 and} therefore cannot detect even smaller leaks. This method has some advantages, such as test flexibility, where the observer can ignore irrelevant leaks, such as from an incomplete seal in the fuel tank for testing. The disadvantages are more than enough. Even this flexibility is adversely affected by the time constraints of the automotive industry. The more he is forced to perform the test earlier, the more likely he is to be less accurate. It is also necessary to soak the tank in water, which wets the tank and requires a drying cycle before painting or finally assembling the tank.

Other leak detection methods include conventional mass spectrometer pressure tests and pneumatic decay tests. Conventional mass spectrometer leak testing requires placing the test part in a leak-tight enclosure and sealing all holes. A high vacuum is drawn on either side of the part or inside the enclosure and helium is directed to the other side that is exposed to atmospheric pressure. Any helium detected by the spectrometer scanning the high vacuum space indicates a leak. This test is extremely sensitive, can be easily automated and operates quickly, but is a delicate system that is not suitable for use in the automotive industry. This is mainly due to the need to maintain high vacuum, which requires special parts and special maintenance. Furthermore, wet parts cannot be tested in this way, even if they are a requirement for a previously welded steel fuel tank. The end result of this new instrument is the expense of a relatively expensive mass spectrometer.

In contrast, air pressure decay tests are inexpensive and are well adapted to the situation in the automotive industry. However, this test cannot be used for parts having a small leakage allowance and having a constitution larger than several tens of cm ³ (several in ³ ). This exam is
This is done either by pressurizing or evacuating the part to be tested. Whether the rate of pressure change is measured, or the flow required to maintain a constant pressure,
One of The speed of this test is greatly affected by the size of the part and by the test pressure, and the accuracy is affected by the temperature of the part being tested.

A fairly comprehensive and descriptive work on leak detection has been written by Varian Associates Incprorated, entitled "Introduction to Helium Mass Spectrometer Leak Datetechnique."
on to Helium Mass Spectrometer Leak Detection) "
The title was published in 1980.

Halogen leak detectors are commonly used, especially in the refrigeration industry, and generally include systems pressurized with test gases, including inorganic halides or similar gases. Furthermore, the exterior of the system is scanned with a detector probe that is sensitive to the traces of the test gas. Disadvantages of this system are that the leak detector is sensitive to various other gases, including cigar smoke, and that most systems emit test gases to the atmosphere.

A further significant problem with the use of refrigerant gases is their effect on ozone in the upper atmosphere. This is causing a substitution of other gases for leak detection.

It is an object of the present invention to provide a quick and accurate method of detecting fuel tank leaks suitable for use in automotive work. The systematic testing of fuel tanks during production serves two purposes, in other words it guarantees the performance of the production system and assures quality control by eliminating tanks that leak during use. .
This device is robust enough to withstand the rapid loading and unloading required in relation to the floor conditions of the car factory, especially the production line speed, and also sufficient to detect small leaks in the fuel tank. Only have to be sensitive.
Since most fuel tanks are two-part metal structures, most fuel tank leaks occur around the weld seam of the tank. Recently, however, seamless plastic fuel tanks have grown in popularity with the automotive industry. Small but significant leaks can occur in plastic tanks in any part of the tank. Despite the automotive industry's desire for leak detection accuracy, the overriding consideration has always been the speed at which tests are performed. It can be said that every second is important in the efficiency work of an automobile plant in which automation of the system is essential.

Perhaps the most important requirement of a leak detection system in the automotive industry is its ability to be reused many times when testing is repeated for a very large number of individual components to be tested. The detection system must maintain its sensitivity and give consistently accurate results. The present invention specifically avoids many of the problems that can arise from the above repeated use.

There are also competing issues when selecting a vacuum-based leak detection system. The smaller the chamber to be evacuated, the more quickly and efficiently the system can be operated. In the current automotive industry, service operations can be said to be a decisive factor in the selection of a leak detection system, as any downtime caused by waiting for the required parts is very expensive. Another problem encountered in leak detection systems is variation in the group of components to be tested. Even though the parts may be manufactured simultaneously or sequentially, the products may not be identical and there may be small variations in their dimensions and shapes. Therefore, the leak detection system must be adaptable to the individual components being tested.

Another problem that must be encountered when utilizing a vacuum leak detection system is the effect of the resulting differential pressure on the fuel tank being tested. Conventional fuel tanks are made of a two-part metal structure, with each half welded to a peripheral flange. Since leaks often occur in fuel tanks at flange welds, one method previously used in the art has utilized a weaker crushing flexible chamber around the tank being tested. Thus, the tank flange is not supported throughout the test, but the weaker recess in the tank half is supported by the vacuum chamber itself.

While flexible chambers are useful for reducing the volume of a chamber that needs to be evacuated, the use of flexible chambers reduces the effectiveness of other methods that improve test speed and accuracy. Let it. In addition, flexible chambers have a tendency to block or cover leaks, thus reducing the effectiveness of the test except in the area surrounding the flange. As mentioned earlier, this is not a major problem as most leaks occur at seams when conventional metal tanks are tested, but seamless plastic fuel tanks can be used in any given tank. It seems to leak at that point. As with conventional metal tanks, uniform leak detection is one goal.

Furthermore, with flexible chambers, no structural support is provided in the tank from atmospheric pressure outside this chamber. When a vacuum is drawn into the tank and the pressure between the tank and the chamber is equalized, as is done when the tank is scavenged, the flexible chamber allows external air pressure to act on the tank. Become. Since the fuel tank has a tensile strength much greater than the compressive strength, it is important that the chamber be sufficiently rigid to withstand atmospheric pressure even if a slight vacuum is created in the tank. Furthermore, a flexible chamber creates a great deal of difficulty in supporting the peripheral seal and a great deal of difficulty in modifying the chamber due to the difficulties of effective adhesion of the resilient material.

A common method of supporting a component to be tested by the vacuum chamber leak detection method is to provide a rib in the test chamber, whereby the component is suspended between the ribs when the chamber is closed. Thus, a substantial portion of the surface of the component to be tested is exposed to the vacuum created in the chamber. However, a particular problem with the above device is that the portion of the surface of the component being tested that contacts the ribs is not exposed to vacuum. Since the ribs effectively "block" the leak, any leaks that occur in those parts that are not exposed to the vacuum will not be detected during the test. It is an object of the present invention to provide a support for a component to be tested while completely exposing the entire surface of the component to be tested to the vacuum in a vacuum leak detection system.

Detecting the presence of a leak is important to ensure that no leaking container is released to the general public, but unless a leak is detected, the container cannot be easily repaired and the source of the leak Cannot be determined.
Thus, providing a device for locating any detected leaks is a clear benefit to a leak detection method or device. Information on where the container leak is located can help identify defects in the materials used to make the container, the method of shaping the container, or any method of sealing the container, such as welding. obtain. Furthermore,
Locating any leaks indicated by the leak detection system exposes any defects in the leak detection system itself and prevents the loss of a good container that could simply be rejected due to a leak in the detection system. You. It is an object of the present invention to locate leaks in addition to detecting them.

Other objects, features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings.

An example of the prior art in the field of leak detection through the use of a vacuum chamber is described in US Pat. No. 3,813,923, “Adaptive Fixture For Leak Testing of Con
tainers) ". This patent discloses the use of a chamber having a flexible diaphragm. The diaphragm is pushed toward the container to be tested to engage and support the container by increasing the pressure in the space between the diaphragm and the chamber. The diaphragm is also provided with a protrusion so that the diaphragm can contact the container to be tested while maintaining a fluid space between the diaphragm and the container to be tested. The patent discloses the use of a vacuum to evacuate the fluid space and the use of a halogen test gas with a halogen gas sensor.

The use of a vacuum chamber, particularly a flexible chamber, to facilitate the reversal test fuel leak detection test is well known in the art, as shown in this patent. The present invention stands out over the prior art in speed, reliability and accuracy in performing tests. The vacuum chamber in the present invention is designed so that a new chamber can be formed for each series of parts to be tested. Furthermore, the prior art does not propose a scavenging process, a porous or grooved standoff, a self-aligning seal, or a leak location method.

SUMMARY OF THE INVENTION The fuel tank leak detection method and apparatus described herein is a "reversal" detection system. The method begins by loading a fuel tank into a two-part test chamber configured for the fuel tank to be tested. The chamber is closed and sealed. Each of the fuel tank components to be tested is sealed. The chamber is partially evacuated and the fuel tank is pressurized with the test fluid. The differential pressure causes the test fluid to flow into the test chamber through any leak present in the fuel tank. During testing, the output of the vacuum pump used to maintain the reduced pressure in the test chamber is directed through a sensor that detects the presence of any test gas that enters the test chamber.

With the method specifically described here, this procedure can be performed at factory speed under factory conditions, while maintaining a high degree of accuracy. The accuracy and sensitivity of the leak detection system is improved by removing almost all external test gas sources and by removing all residual test gases in the system prior to performing each test. All air entering the system is filtered, so that no trace of the test gas present in the atmosphere can enter the system. Any air exiting the system can be filtered or vented to the outside, so that traces of the test gas do not enter the atmosphere within the test area. This filtering of the effluent air increases the accuracy of the test and increases the safety of the test by reducing the chance of anyone in the area of the test being exposed to the test gas. Filtration of the effluent further helps to prevent the release of the test gas to the outside world and allows the test gas to be collected for possible recirculation.

The most critical factor, the speed of the process, is increased by the particular pumping system utilized, which also increases the sensitivity of the process. A roughing pump is used to quickly evacuate the test chamber to the desired pressure, and at that pressure stage a smaller pump is used to maintain that pressure throughout the test. This system guides the speed of large displacement pumps while maintaining the accuracy of small pumps, avoiding the inherent problems of each.

The apparatus described herein provides an apparatus for operating a "reversal" leak detection system that is particularly suitable for the automotive industry. The operation of the device consists of charging the test chamber with a fuel tank, sealing the test chamber, evacuating the test chamber, filling the test chamber with scavenging air, and evacuating the test chamber. Pressurizing the fuel tank with the test fluid, switching the system to a test pump, detecting any test fluid flowing into the test chamber, and purging both the fuel tank and the test chamber. And removing the tested fuel tank. The entire system or a part thereof can be automated. The configuration of the device reduces the time required to perform the test by reducing the volume of the test chamber to be evacuated.
The described laboratory can be formed quickly and inexpensively,
Thus, in the event of damage to the test chamber or of a design change of the fuel tank to be tested that requires a different test chamber, it can be easily replaced. The test chamber can be easily modified in case of minor design changes to the tank geometry being tested. The configuration of the test chamber is such that the stress resulting from the differential pressure during the test is received in the test chamber, not in the fuel tank being tested.

This arrangement provides a device for sealing holes in a fuel tank to be tested that is easily automated and can accommodate variations between individual fuel tanks to be tested. These sealing devices can also be used to provide an inlet for the test gas or scavenging air to enter the fuel tank being tested. In addition, the sealing arrangement can provide an outlet for all air exiting the fuel tank to be tested.

According to an additional embodiment of the device, a method is provided for supporting the component to be tested with a porous standoff so that the entire surface of the component to be tested is subjected to a vacuum during the test.

According to another embodiment of the device, by sequentially flushing and detecting each of the plurality of leak zones, a leak to be identified can be located.

The drawings depict only preferred exemplary embodiments of the invention by way of example only. Those skilled in the art will readily recognize that the principles of the present invention are well suited for application to devices other than fuel tank leak detectors and to other fuel tank leak detectors shown in the drawings.

Example and operation The test is carried out by charging a fuel tank into the lower part of the vacuum chamber. The chamber is closed and sealed. A vacuum is then drawn into the room via the vacuum port. If any large loss of pressure inside the tank is detected, the test is stopped and the tank is rejected as having a large leak in the tank. To quickly draw a vacuum,
A large roughing vacuum pump is used. When the roughing pump achieves the desired vacuum, the system is switched to a smaller sensing pump for testing. Switching between pumps is accomplished by having a small sensing pump draw a vacuum into a line extending through a valve to a vacuum chamber. When the pressure inside the vacuum chamber reaches the pre-regulated valve,
A pressure switch closes the line from the roughing vacuum pump to the vacuum chamber. Leakage is not a significant problem in roughing pumps because the roughing pump is used to speed up the testing process by rapidly depressurizing the chamber to the desired vacuum chamber. However, the sensing pump must not leak during operation. Diaphragm pumps are a good choice for sensing pumps. Oil filled pumps should not be used for detection as trace gases dissolve in the oil. An anemometer can be inserted at the diaphragm pump outlet to check if there is a diaphragm pump leak indicating that the pump is faulty, but this anemometer also
Leaks in chambers, tank seals, or associated valves and lines are also indicated.

Trace gas into the fuel tank is about 414,000-550,000Pa
(About 60-80 psi), this high pressure injection fills the tank in less than 1 second and produces good dispersion of the test gas throughout the fuel tank. R-12, helium, or sulfur hexafluoride are preferred choices for gases, primarily because of their flame retardancy, non-toxicity, and ability to be detected electronically in air at less than 10 ppm. A sensor is placed at the outlet of the diaphragm pump, which detects any trace of the test gas which then indicates a leak. Before and after each test, a systematic high-fluid air scavenging process is performed. Prior to testing, the chamber is purged to remove any test gas that may cause inaccurate readings. After the test, the fuel tank is partially evacuated and then flushed with scavenging air to remove all test gases from the system. Each chamber is scavenged or flushed with air after each test.

The sensor is exposed only to the filtered air, even though it may be using the tank for testing, which extends the life of the sensor and increases its reliability. As soon as any leaks are detected, the filtered air flows through the sensor. An advantage of using a mass spectrometer with helium trace gas is that it can detect atmospheric helium between tests. This allows
A device is obtained that constantly checks the correct operation of the mass spectrometer. Helium in the atmosphere is present in only 5 ppm of air.

FIG. 1 shows a fuel tank leak detection device having a fuel tank in a test chamber. Fuel tank 10 is shown in a vacuum chamber, generally indicated at 12. The vacuum chamber has two parts:
It has a stationary upper chamber 14 and a lower chamber 16 which is lowered to load and unload the fuel tank into and out of the vacuum chamber and is raised closer to the chamber for testing. Each of the two parts of the chamber is concave with respect to each other, and when closed, both parts of the chamber form a vacuum chamber substantially matching the fuel tank to be tested. A sealing element (preferably an extruded "T" rubber gasket) 15 is located in the bottom chamber portion near the periphery of the two chamber portions, and an "O" shaped ring adapted for the "T" gasket is provided with an upper ring. Placed on a piece. The "T" gasket and "O" ring seal the vacuum chamber formed when the two chamber parts are brought together. The lower chamber is raised and lowered by a closing cylinder or a pair of closing cylinders shown at 24 and mounted on a guide rod 22. Alternatively, the vacuum chamber may be opened and closed by raising and lowering the upper chamber.
The main entrance to the room is a vacuum manifold 20 and an air manifold 22. The location and use of these inlets will depend on the fuel tank being tested, and they will be molded directly into the vacuum chamber when the chamber is manufactured. Vacuum manifold 20 connects the vacuum device to a vacuum chamber. Air manifold
18 can be used to provide an inlet for air into the vacuum chamber. The vacuum and air manifolds are easily connected to a vacuum or air inlet by connecting flanges well known in the vacuum industry and are sealed by O-rings 19. The main port seal assembly shown at 25 in the perspective view provides access to the fuel tank being tested.

The vacuum chamber is filled with pressurized scavenging air during the scavenging operation. Given the speed at which this process is run, the pressure build-up is probably rapid, and leaving it unidentified can damage the vacuum chamber. One of the vacuum chamber parts may be supported on one or more springs to prevent any damage. These springs are designed to open the vacuum chamber at a predetermined pressure level below which damages the vacuum chamber. In addition to the pressure relief, this spring also makes the chamber closing force even.

This preferred method of construction of the vacuum chamber is inexpensive and probably very fast, so that a new chamber can be constructed for each type of fuel tank to be tested, or any damaged chamber part can be replaced. It is convenient to construct a new part of the fuel tank chamber. The vacuum chamber is configured using a specific fuel tank or the type of fuel tank to be tested as the chamber type. Since each chamber part corresponds to one half of the fuel tank to be tested, the mold for the chamber part should be surrounded by a flat surface at the seam of the fuel tank and around the fuel tank. It is formed by providing a frame. Other devices for supporting the tank are described herein.

A suitable material, such as a two-part hard epoxy, is poured over the top of the fuel tank and into the mold defined by the enclosure. The epoxy can be reinforced with chopped fiberglass (about 12% by weight). The two chambers can be formed simultaneously by providing a flat insert in the flange of the fuel tank and pouring the appropriate material over the entire tank and splitting the mold in two at the flange. A structural support, shown as 21 in FIGS. 1 and 2, is inserted during the molding process to impart structural support and possibly steel beams or the like to the chamber structure. Ladder-type steel frames are suitable for providing the necessary room support to prevent the epoxy chamber from deforming over time, even though the epoxy can be supported by fiberglass. The above-mentioned frame also provides a powerful and convenient mounting point. Manifolds 18, 20 are inserted into the tank prior to the molding procedure and are molded therein. Further, the base of the main port and seal assembly 25 can be integrally molded into the casting.

A small circular spacer, shown at 72 in FIG. 2, is attached to the interior surface of the chamber to provide support for the fuel tank to be tested during the test. The standoff is made of a low wear material, such as a high durometer urethane. The surface of the standoff that contacts the fuel tank is sharply grooved to provide a leak path if the leak is covered. During the test, the tank is subjected to a pressure of about 89,600 Pa (about 13 psi) as a vacuum is drawn into the chamber. In addition, the inside of the tank, as the tank is pressurized with the test gas, 3,450-4,140Pa (0.5-
0.6 psig). The test gas is forced by the differential pressure through any leaks that appear in the tank, but the fuel tank to be tested also experiences that differential pressure. The standoff helps protect the fuel tank from differential pressure while maintaining the space between the tank and the chamber.

When forming the vacuum chamber, an annular element is placed around the flange of the fuel tank to provide space for insertion of the sealing element. A sealing element 15 and an "O" ring are used to seal both parts of the vacuum chamber when they are closed, but can be replaced as needed. This configuration provides the vacuum chamber with an almost unlimited service life. Similarly, the manifold is provided with a space suitable for sealing with an O-ring, so that the chamber can be easily replaced.

FIG. 2 shows a general embodiment of the invention with a molded vacuum chamber. A large port and seal assembly 25 is shown in perspective and includes a discharge outlet 26. The vacuum chamber 12 is shown closed and is sealed with an element 15.

The embodiment shown in FIG. 2 is for illustration only. The particular arrangement of the seal assembly will depend on the particular design of the tank used. The port assembly shown in FIG. 2 is shown in detail in FIG. 3 merely to show one possible embodiment of the seal assembly. The seal assembly must be configured to seal individual ports of the fuel tank to be tested, and thus the seal assembly must be individual for each port of the particular model of fuel tank being tested. Designed individually. The seal assembly must have an inlet into the fuel tank for the scavenging air and the test gas, and
There must be outlets for all air discharged from the fuel tank. Desirably, each of the seal assemblies is complementary so that the fuel tank can be mechanically sealed when the test chamber is closed.

FIG. 3 shows an embodiment of a port and seal assembly (shown at 25 in FIG. 2). The seal assembly can be inserted into and sealed to a port of the fuel tank and is movable to compensate for variations within a given production range of the fuel tank. The port shaft 40 is inserted into a port of the fuel tank, and is an annular urethane port for sealing the fuel tank 10.
It has a seal 36. The vacuum chamber is sealed with a special face-type lip seal 38. This seal 38 is of a flexible construction and therefore has a 5 ° angular runout or
Can withstand 7.62mm (0.3in) deflection. Inside the port shaft is a scavenging exhaust outlet 26. The scavenging exhaust outlet 26 may be an inlet if necessary for the design of the tank, but is shown here as an exhaust outlet. In other embodiments,
A vacuum may be drawn into the exhaust outlet 26 to facilitate the scavenging process. The port shaft is reciprocated by the cylinder 51 inward and outward of the fuel tank. The cylinder 51 is mounted on a frame 53 attached to an annular support platform 55 formed integrally with the vacuum chamber 12.

FIG. 4 shows a pneumatic configuration diagram of a test process controlled by an automatic system. The test room with the fuel tank in place for the test is shown at 100. The tank is placed in the test room,
The test chamber is closed by one or more sets of pneumatic cylinders (not shown). The first port seal assembly 102 is reciprocated by a pneumatic cylinder 104 and the second port seal assembly 106 is reciprocated by a pneumatic cylinder 108 to seal the fuel tank port. The air used during the test is controlled by a valve 110 and includes a particle filter 112 and a two-stage aggregator.
114 and 116. A separate air supply can be used if the air supply of a plant does not seem to be able to supply the required amount of air. Air enters the chamber via the chamber inlet manifold 120 and is
It is placed in the tank via port 122 of seal assembly 106. The test gas is about 414,000 to 550,000 Pa (about 60 to 80 psi).
At g), it is stored in the supply canister 126, possibly further pressurized and contained in the surge tank 130, and into the fuel tank via the port 124 of the port seal assembly 102. The flow of the test gas can be controlled by the valve 132. If the test gas inflow requires a separate inlet port, a scavenging valve 134 is required, which allows the test gas inlet line to be scavenged and removes any presence of the test gas. Air is exhausted from the chamber via the first port and seal assembly 102 and from the chamber via the chamber exhaust manifold 136. For illustrative purposes, an additional view of the tank inside the chamber is shown at 101 to illustrate the use of the test outlet 140. Air exiting the chamber via outlet 140 is selected via sensing pump 144 and sensor inlet valve 146. This effluent is directed past the sensor 148 during the detection phase. Air is pumped out of the chamber via a discharge manifold 136 by a roughing pump 150 to enter a discharge outlet 152 to quickly reduce the pressure in the test chamber.

The number of outlets 140 in the vacuum chamber can be as high as 60 or more. 6
If zero outlets are used, selected zones of the tank are individually tested by transporting the effluent from the 15-20 outlets at a time via the test gas sensor. For example, the effluent from the 20 outlets near the weld seam can be tested first, then the effluent from the 20 outlets near the upper half of the tank, and finally the lower half of the tank. The effluent from 20 outlets close to can be tested.

An important feature of this test is its accuracy and its speed. A leaking tank will not be passed at all. Any signs of leakage will result in a failure of the tank being tested. In addition to detecting the test gas entering the chamber,
All significantly incorrect pressure and flow changes will result in the activation of fault lamps and failure of the tested tank. A given number of consecutive tank failures will result in a signal to the operator, and therefore an outrageous number of tank failures will not result from equipment malfunctions such as seal leaks. No, and therefore the systematic deficiencies of the tank need to be noted and corrected.

The test is started by loading the test container into the chamber and closing the chamber. When the chamber begins to close, the tank discharge valve 156 closes, the test gas line scavenging valve 134 closes, and the chamber discharge valve 160 closes. During this phase, the exhaust vacuum detector 170 checks the exhaust pressure, and if the pressure is too high, the test is interrupted and the fault light turns on. Once the chamber is closed, the seal assembly is reciprocated to seal the test container. Tank discharge valve
156, the test gas line scavenging valve 134 and the chamber discharge valve 160 are all closed. Once the chamber is closed and the tank is sealed, the chamber is evacuated by opening and closing valve 163 and then scavenging, but both the chamber scavenging inlet valve 164 and the chamber scavenging outlet valve 160 are open. The chamber scavenging pressure detector 172 monitors the chamber pressure and interrupts the test if the pressure is too high or too low. Once the chamber has been scavenged, the chamber is evacuated by opening the roughing pump valve 163 so that the roughing pump 150 can quickly evacuate the chamber.
Pump control valve 174 detects when chamber vacuum has reached a predetermined valve, at which point it switches the effluent of sensing pump 144 to sensor 148 via valve 146. If this transition does not occur within 1.5 seconds, the test is aborted and the fault light is turned on. In order to detect a general leak in the tank, a device for detecting a small negative pressure in the fuel tank may be included. When the chamber is evacuated and the effluent of the detection pump is switched to the sensor, the roughing pump control valve 16
3 is closed, so that the roughing pump can continue to operate without affecting the system. Vacuum level indicator 176 detects whether the vacuum inside the chamber is maintained at least at a given minimum level, or the test is aborted if this vacuum level is not maintained. When the chamber is evacuated to the test state, the test gas inlet valve 132
By opening the tank, the tank is quickly filled with the test gas. The pressure in the tank is 3,450 to 41,400 Pa (0.5 to 6.0 psi)
When the predetermined valve is reached in the range of g), the test gas pressure control detector 178 closes the test gas inlet valve 132. If the pressure does not reach within one second, the test is interrupted and the fault light is turned on. During sensing, the sensor inlet control valve 146 remains open. Similarly, vacuum level detector 176 has been activated. If the detector detects a flow rate greater than the normal operating flow rate, which indicates an air leak, the sensing pump effluent flow detector 180 interrupts the test. If the effluent flow rate is less than normal, it indicates that the sensing pump 144 or sensing valve 146 has failed and the flow detector 180 also interrupts the test. Test gas sensor 148 is engaged and interrupts the test upon detection of a predetermined amount of any test gas. Upon completion of the test, or upon detecting any of the test gases, or upon detecting a leak or component failure that could cause the test to be interrupted, the system enters a scavenging mode where all particles of the test gas are removed. The tank and the chamber are scavenged so that Tank vacuum valve 156 is momentarily opened to facilitate the scavenging process. The tank vacuum is controlled to block a higher vacuum than the chamber to prevent damage to the tank. Tank scavenging inlet valve 168,
The tank scavenging outlet valve 158, test gas line scavenging valve 134, chamber scavenging inlet valve 164 and chamber scavenging outlet valve 160 are all open. The tank scavenging pressure detector 182 and the chamber scavenging pressure detector 172 each detect whether the pressure is too high or too low and interrupt the test in either case. When opening the room after the test,
The tank discharge valve 158, test gas line scavenging valve 134 and chamber discharge valve 160 are all open. The test gas low pressure detector 128 and the exhaust vacuum pressure detector 170 indicate whether the pressure is too low, at which time subsequent tests are aborted and the corresponding fault light is turned on.

To further increase the reliability of the test, enhanced ventilation can be provided to the plant surrounding the vacuum chamber. This removes any traces of the test gas from the area surrounding the test device.

FIG. 5 shows a sealing device for both the upper and lower parts of the test chamber. The chamber 200 comprises an upper chamber part 202 and a lower chamber part 204 and is structurally supported by a steel beam 206. This chamber is sealed by using three sealing rings. The O-ring 208 is insertable into a trapezoidal cutout 210 formed in the upper portion 202 as it flows into the upper portion 202. Another O-ring 212 is insertable into a groove 214 formed in the lower portion 204 as it flows into the lower portion 204. The sealing surface 216 of the lower part is
It is out of alignment. An annular T-shaped seal ring 218 is insertable between the two sealing surfaces 216, 217 and has a normal uncompressed height greater than the stagger distance between the two sealing surfaces.

The T-shaped seal ring 218 is located between the O-ring 208 and the O-ring 212, so that the sealing device
A ring 208 exists between the O-ring 208 and the T-shaped seal ring 218, the T-shaped seal ring 218 and the O-ring 212, and between the O-ring 212 and the lower portion 204. The seal ring 218 is compressible to the staggered distance between the upper and lower chambers when the chamber is closed. This creates an additional sealing device between the upper portion 202 and the seal ring 218 and between the seal ring 218 and the lower portion 204. Seal ring 218
Has a flange-shaped portion 220, so that it is fixed to the lower chamber.

The holding strip 224 can be fixed to the lower chamber by a screw device 226 for holding the seal strip 218. Preferably, however, the grooves 222,228 are formed in the lower chamber as it flows into the lower chamber so that the seal ring 218 can be inserted into the grooves 222,228 and retained there by a friction device. This method of securing the seal ring 218 reduces cost and time to assemble the chamber and replace the seal ring 218.

FIG. 6 (not to scale) shows the part 3 tested in the vacuum chamber 302 of the leak detector, supported by a porous spacer 304.
00 is shown. The porous spacer 304 is formed to allow gas to pass through the spacer. The type of spacer shown in FIG. 6 is a circular flat boss formed integrally with the chamber. Like gluing with cyanoacrylate glue,
Other methods for attaching the separating material may be used. The spacing material need not be circular and may be of any shape, but a cylindrical spacing material having a diameter of 9.525 mm (3/8 in) and a height of 2.286 mm (0.09 in) is preferred.

Rather than having a uniform cross-sectional area, the standoff may be formed with a fairly large area within the chamber surface and a smaller area exposed from the chamber surface. The protrusion of the standoff must have sufficient compressive strength to support the part being tested while a vacuum is being drawn into the chamber.

Similarly, there must be a sufficient number of spaced material evenly support the component to be tested while the vacuum into the chamber is drawn, the interval of about 31.75 mm (about ¹ _1/4 in) in each direction It is desirable to open. As long as the part is properly supported, a minimum volume of standoff between the chamber and the part is desirable.
The reduced volume of the standoff projecting from the chamber surface reduces the amount of gas flowing through the standoff. While it is not necessary for the standoff to have a larger cross-sectional area in the room, such an arrangement increases stability and increases the force securing the standoff within the room. A particular shape that reduces the volume of the standoff between the chamber and the supported component is essentially the flat boss shape described above, engraved with two perpendicular grooves or slots. . As long as the parts are properly supported, any number of grooves may be cut to reduce the volume of the standoff, and they may be of any depth, shape, direction, or width. Is also good. Another possible configuration is to provide porous ribs that can be molded into the chamber and can be of any width, length, or spacing within the limits of suitable component support.

The porous standoffs or ribs can be made of any suitable porous material that has sufficient compressive strength to support the part while a vacuum is being drawn into the chamber, but steel screens are particularly effective. Has been proven. Urethane (of about 70-A durometer) is used to avoid scratching the special coating of some fuel tanks. Porous metal separators, with the same size and spacing, can be used in most metal and plastic tanks. The standoff may be partially or wholly hollow to reduce cost or reduce possible gas entrapment. In addition, the standoff material is completely porous material as long as there is sufficient passage of the porous material in contact with the supported components, so that any leaks are not blocked, and thus gas can flow through the standoff material. Need not be composed of

7 to 10 show a method of fixing a porous spacer on the surface of the chamber. In FIG. 7, the separating material is the chamber 308.
Is formed so that it can be inserted into a corresponding space in the inside. The standoff is secured to the chamber by a screw 310 located at the center of the standoff in the cylindrical bore 312. Only the remaining circumferential portion 314 of the standoff projects from the chamber, which reduces the volume of the protrusion of porous material.

FIG. 8 shows the use of a circular, toothed push ring 316. The standoff 318 is insertable into the cavity 320 of the chamber 322. Void 320 has a small internal diameter and a large external diameter. The spacing material 318 is similarly formed with a small diameter and a large diameter. The small diameter of the standoff 318 substantially fills the small diameter of the cavity 320. Spacing material 3
The large diameter of 18 is the same as the large diameter of the void 320,
Therefore, the spacer 318 can be slidably inserted into the space 320. The large diameter thickness of the standoff 318 is less than the large diameter thickness of the cavity 320, forming a flange 324 and leaving a recess 326 in the cavity 318. Boss 328 projects beyond chamber surface 330 and has a smaller diameter than the larger diameter of standoff 318. Retaining ring 316 is inserted into recess 326 over boss 328. Retaining ring 316 is concave, so that it bends inward when inserted and reduces its diameter, but tends to increase its diameter when stressed outward. Retaining ring 316 may also be provided with teeth therearound to assist in frictional engagement with the inner wall of recess 326.

FIG. 9 illustrates the use of an adhesive to secure the standoff 332 to the surface of the chamber 334.

FIG. 10 shows a modification of the method shown in FIG. A metal plug 336 is integrally formed with the chamber 338. The standoff 340 can then be secured within the metallic plug by the screw 342. FIGS. 11 and 12 show how to isolate and locate leaks when testing containers for leaks. For the initial detection of leaks,
Leaks can be located by sequentially testing the individual zones of the chamber 334, separated by the standoffs 340. The aforementioned method of detecting a leak while the vacuum is held in the chamber and the pressurized test gas inside the part to be tested is temporarily suspended. Purified air at an absolute pressure higher than the chamber pressure is introduced into each zone to "flush" the zones, causing any trace gases to be withdrawn through the outlet of the zone to be detected. Once the chamber is created, or perhaps simply defined by the inlet and outlet ports, the inlet and outlet flow paths of the zone can be formed into the chamber. Each of the zones is tested for a test gas, and once a leaky zone is identified, a leak locator is fitted to that zone. To increase the efficiency of the zone, a non-porous release, such as a rib-type separator, parallel to the flow path of the zone or near the inlet and outlet ports of the zone outside the flow path can also be provided. The separation material is
Air flow between the inlet and outlet ports of each zone must be allowed.

The zones can be set to test specific areas of the fuel tank that are most sensitive to leaks. For example, seams in metal tanks are likely to leak. A zone can be set with a non-porous standoff to test the seam of the tank. The tank can also be tested with an already installed oiling assembly.
In this case, a band can be set to test the seal of the oil supply facility.

FIG. 11 illustrates one method of locating a particular band where a leak has occurred. Purified air enters the inlet 400 and the inlet valve 4
02 is introduced into a specific band in a controllable manner. The inlet junction 424 allows air to flow to other inlets in other zones. The flow rate of the purified air into a specific zone is adjusted by a flow controller 404. The flow controller 404 can be adjusted manually or automatically. Inlet valve 4
When 02 opens, conditioned air flows into chamber 408 via zone inlet port 408. An inlet channel 410 extending across the full width of the zone can be molded into the chamber 406 to facilitate flushing the full width of the zone. The purified air flows over the zone defined by the chamber surface, the surface of the part 411 to be tested, the inlet port 408 and the outlet port 412. Outlet channel extending over the full width of the zone
The 414 can be molded into a room. A vacuum is drawn through outlet port 412 by test vacuum pump 416 to maintain a differential pressure across part 411. The differential pressure forces the gas through the leak, which then flows through the zone and through outlet port 412. The effluent of the vacuum pump 416 is exposed to a gas sensor that detects the presence of a test gas. An outlet valve 418 is located in front of an outlet junction 420, shown at 422, which connects all of the outlets of all zones to a vacuum pump 416. Thus, the individual zones are opened in a particular order to the vacuum pump 416 and the sensor, but the vacuum pump 416 can operate continuously. By opening valves 402, 408 for a given zone,
The zone is tested for traces of the test gas. The valves 402, 418 can then be closed for the first zone, opened for the next zone, and continue continuously until all zones have been tested.

An alternative way of controlling the above method is by a single control valve 402. The flow controller 404 is located before the inlet junction 424. No outlet control valve 418 is required. Only the inlet control valve 402 for the zone to be tested is opened, so the only flow through the vacuum pump and the sensor is through the zone to be tested. This method is quick and easy.

Another method for locating leaks is shown in FIG. A flow controller 426 is provided at the purified air inlet 428 leading to the inlet port 430. An inlet channel 432 extending across the full width of the zone is a chamber 434
Can be molded into. The purified air traverses the part 436 to be tested and flows through the zone via the outlet port 438. The outlet channel 440, which extends over the entire width of the channel,
Can be molded into 34. Air flow path is three-way valve 44
Controlled by 2. If a particular zone is being tested, a valve 442 directs the flow at the outlet through the sensor vacuum pump 444 to the sensor. The flow through the sensor vacuum pump 444 is controlled by a flow controller 446. If a particular zone has not been tested, valve 442 is activated to direct flow through non-sensing vacuum pump 448, and the effluent is discharged. The sensing inlet 450 shows the outlet flow from each of the other zones in test mode (with valve 442 open toward the sensing vacuum pump). The discharge inlet 452 shows the outlet flow from each of the other zones in test mode (open to the discharge vacuum pump of valve 442). In this method,
Each of the zones is experiencing a stream of purified air, and the zones can be easily tested in sequence.

The optional leak band detection cycles are:
Complete scavenging of the chamber and outlet lines while retaining gas in the fuel tank after detection of an overall leak. The valve 418 or 442 is then opened following the sensing pump.

Although the process and apparatus described herein involves testing a fuel tank, the process is likely to have many other useful uses. Fluid-enclosed containers will be in terms of leaks, such as in automotive fuel supplies, especially fuel pumps, fuel filters, fuel pressure regulators, heater cores and radiators. Other possible items in the automotive industry that could be tested include wheels,
A converter, vacuum modulator or spark plug. Each of these, by utilizing the process described here,
Testing can be done quickly and accurately.

Even if it turns out that the preferred embodiments of the invention disclosed have been sufficiently confirmed to achieve the objects and advantages or advantages of the invention, the invention is to be defined by the proper scope of the appended claims. It will be understood that modifications, variations, and alterations can be made without departing from the valid meaning.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a device for detecting leakage of a fuel tank,
FIG. 2 is a perspective view of the port and seal assembly, a longitudinal sectional view of the fuel tank leak detector, FIG. 3 is a sectional view of the port and seal assembly taken along line 3-3 of FIG. FIG. 4 is a pneumatic configuration diagram of a system for operating a device for detecting leakage of a fuel tank, FIG. 5 is a sectional view showing a sealing device of a device for detecting leakage of a fuel tank, and FIG. 6 is a porous separator. FIG. 7 to FIG. 10 are cross-sectional views of a test part held in a test chamber, and FIG. 7 to FIG.
FIG. 11 is a schematic diagram of an operation of a device for locating a leak when detecting a leak, and FIG. 12 is a schematic diagram of an operation of a device for locating a leak when detecting a leak. 10 Fluid-containing chamber 12 Vacuum chamber 14 Static part 16 Retractable part 18 Inlet manifold 20 Vacuum manifold 25, 102, 106 Port seal assembly 36 Annular device 122, 124, 408, 412 Port .

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References Practical application Microfilm (JP, U) photographing the contents of the specification and drawings attached to the application form of Japanese Utility Model Application No. Sho 61-59833 (Japanese Utility Model Application No. Sho 62-170547) Japanese Patent Application No. Sho 61-126749 (Japanese Utility Model Application No. Sho 63-33440) A microfilm photographing the contents of the specification and drawings attached to the application (JP, U) Japanese Patent Publication No. 51-19357 (JP, B2) 62-12988 (JP, Y2)

Claims (5)

(57) [Claims] An apparatus for detecting a leak in a portion of a fluid-filled chamber that includes at least two ports, the device including a vacuum chamber having two portions, a stationary portion and a retractable portion, wherein the vacuum chamber comprises An inlet manifold and a vacuum manifold generally conforming to the shape of the portion of the occupied chamber and integrally formed in the evacuated chamber; and At least two reciprocable port and seal assemblies that can be inserted;
A fluid containment chamber discharge manifold disposed within one of the set of port seal assemblies; a test fluid input device disposed within one of the set of port seal assemblies; A fluid-filled chamber scavenging air input device disposed within one of the set of port seal assemblies, and an annular device for sealing the port seal assembly at least partially inserted into the port. And a pneumatic device for reciprocating the retractable portion relative to the stationary portion, wherein the annular device is disposed on the port seal assembly, and wherein the port seal assembly is inserted into the port. A pneumatic device for reciprocating the port and seal assembly and a rapid vacuum device pneumatically connected to the vacuum manifold to rapidly reduce the pressure in the vacuum chamber to a given test pressure; and A test vacuum device pneumatically connected to maintain the test pressure in the vacuum chamber during the test, and an air inlet device for introducing air into the vacuum chamber, wherein the air inlet device is connected to the inlet manifold. And a leak detection device further comprising a fluid detection device exposed to the effluent of the test vacuum device. 2. Apparatus according to claim 1 wherein said vacuum chamber is opened when the pressure in said vacuum chamber exceeds a predetermined level, thereby preventing said chamber from being caused by excessive internal pressure. Equipment that includes equipment to prevent damage. 3. Apparatus according to claim 1, including a device for ventilating the atmosphere surrounding said vacuum chamber to prevent accumulation of said test fluid in the atmosphere surrounding said vacuum chamber. 4. A method for detecting leakage of a portion of a fluid-filled chamber in an apparatus having a vacuum chamber having a rigid interior, wherein said portion of said fluid-filled chamber is loaded into said vacuum chamber. Closing and sealing the vacuum chamber, sealing all ports of the portion of the fluid containing chamber, reducing the air pressure in the vacuum chamber to a test pressure by a vacuum device; Injecting the mixture into the portion of the fluid-filled chamber; detecting the output of the vacuum device with a test fluid detection device; evacuating the portion of the fluid-filled chamber; Purging the vacuum chamber by injecting air into the interior, and removing the portion of the fluid containing chamber from the vacuum chamber. 5. The method according to claim 4, wherein, upon detecting a leak, purified air having a pressure higher than the test pressure is introduced to one end of each of the zones partitioned in the vacuum chamber. Creating a flow of air through the zone, the vacuum device causing the flow of air to flow out of the opposite end of the zone;
And sequentially testing said zones for said leak by detecting spillage of said vacuum device with said detection device.