Test gas sensor device and method for searching for a test gas leak

Abstract

The invention relates to a test gas sensor device (12) for detecting a test gas when searching for a test gas leak according to the spray principle, comprising a measuring sensor (14) for measuring the test gas concentration at the measurement location (46), an electronic signal processing device (18) which is designed to compare at least one measurement value captured by the measurement sensor (14) with a reference value and to generate an electronic control signal if a measurement signal threshold which is based on the reference value is exceeded, and a display device (20) which is connected to the signal processing device (18) and is designed to output an optical and / or acoustic display signal upon receiving the control signal when the measurement signal exceeds the threshold.

Description

[0001] Test gas sensor device and method for test gas leak detection

[0002] The invention relates to a test gas sensor device and a method for detecting test gas at a measuring location during test gas leak detection according to the spray principle.

[0003] In this test, the interior of a test specimen is evacuated and sprayed with test gas from the outside. The gas evacuated from the test specimen is analyzed for the presence of test gas using a test gas detector. If a certain test gas concentration is detected in the analyzed gas from the test specimen, this is considered an indication that the test specimen has a leak through which test gas has penetrated into the interior of the test specimen.

[0004] The test object is typically sprayed with a handheld spray probe, e.g., in the form of a spray gun. The spray probe is connected to a test gas source and designed to emit test gas in a desired direction. The spray probe is then guided along the test object to emit test gas toward it. The area of ​​the test object sprayed with the spray probe is referred to as the measurement area.

[0005] One difficulty is determining whether and how much test gas has been released from the spray probe to the measurement location. Typical test gases, such as helium, are invisible. Small amounts of gas are difficult to detect using human skin sensors. Conventionally, an unnecessarily large amount of test gas is often released to the measurement location.

[0006] The invention is based on the object of providing a device for measuring test gas.

[0007] The test gas sensor device according to the invention is defined by patent claim 1.

[0008] According to the invention, the test gas sensor device comprises a reference sensor and a measuring sensor, each of which can be designed as a thermal conductivity sensor. The sensor device can also consist of only a measuring sensor. Typical test gases, such as helium, can be detected with high accuracy based on the changed thermal conductivity of the thermal conductivity sensor. The reference sensor serves to incorporate changed ambient conditions into the evaluated measurement signal. Atmospheric pressure, ambient temperature, and the amount of test gas present in the surrounding atmosphere can vary. Typically, a certain proportion of test gas, such as helium, is present in the surrounding atmosphere.

[0009] The measuring sensor detects the concentration of the test gas sprayed onto the measuring location. The reference sensor and the measuring sensor are connected to an electronic signal processing device, which is designed to store reference values ​​recorded by the reference sensor and to compare measured values ​​of the measurement signal recorded by the measuring sensor with the stored reference values.

[0010] The signal processing device is further configured to compare at least one measured value of the measurement signal with a threshold value. The threshold value can be an absolute value or a value that includes at least one of the stored reference values. For example, the threshold value can be a multiple of one of the stored reference values.

[0011] The signal processing device is further configured to output at least one electrical or electronic control signal when the threshold value is exceeded, which is transmitted to a display device of the test gas sensor device. Upon receipt of the control signal, the display device outputs an optical and / or acoustic display signal, e.g., via a loudspeaker or a light source.

[0012] The test gas sensor device can have a housing containing the signal processing device and at least part of the display device. The reference sensor, the measuring sensor, and at least part of the display device, such as a light source and / or a loudspeaker, can be attached to the housing. The sensor surfaces of the reference sensor and the measuring sensor must be exposed to the outside. The display device must be designed such that the display signal is output to the outside of the housing so that it can be detected by a user outside the housing. The housing can be designed such that the measuring sensor can be positioned directly in the gas stream of the spray probe.

[0013] The housing has a grip area for holding the device in the hand and bringing it closer to the measurement location. The housing can further have a display area containing part of the display device, such as a light source and / or a speaker, to output the display signal when the threshold value in the display area is exceeded. The display area is exposed when a user encloses the grip area with their hand.

[0014] The reference sensor and the measurement sensor are located on the housing at an end of the display area opposite the grip area. For example, this can be an elongated housing similar to a pen, which the user points toward the measurement location, so that the reference sensor and the measurement sensor are closer to the measurement location than the user's hand holding the housing.

[0015] In particular, the invention also relates to a test gas leak detection device comprising a test gas detector connectable to the test object and a vacuum pump that evacuates the test gas detector and the test object. The leak detection device further comprises a spray probe connected to a test gas source and designed to spray test gas toward the measurement location. The spray probe is a handheld probe. The leak detection device comprises a test gas sensor device of the type described above for determining the concentration of the test gas at the measurement location.

[0016] The signal processing device can be connected to the spray probe and / or to the test gas detector via a data connection in order to transmit the control signal and / or a second measurement signal, different from the first control signal, to the spray probe and / or the test gas detector when the threshold value is exceeded. In this case, the spray probe and / or the test gas detector are designed to output an optical and / or acoustic display signal upon receiving the control signal. Furthermore, it is conceivable that the spray probe is designed to automatically stop the spraying of test gas upon receiving the control signal transmitted by the test gas sensor device. The data connection can be a wired and / or wireless data connection, e.g., a radio connection.

[0017] The light source of the display device can, for example, be at least one LED.

[0018] According to the inventive method for test gas detection based on the spray principle, the test object is first sprayed with test gas using the spray probe, while the test object is evacuated by the vacuum pump. The gas evacuated from the test object is fed to a gas detector in a conventional manner. The test gas sensor device is guided to the sprayed measuring location to determine whether the measuring location has a sufficient test gas concentration for leak detection and, in particular, whether the test gas concentration at the measuring location deviates sufficiently from the ambient concentration of the test gas in the atmosphere surrounding the test object.

[0019] The measuring sensor is used to measure the gas at the measuring location. The thermal conductivity sensor measures the thermal conductivity as a measurement signal. The signal processing device evaluates the measurement signal and compares at least one measured value of the measurement signal with at least one previously stored reference value of a reference signal recorded with the reference sensor. The signal processing device compares the measured value with the reference value or with a threshold value, which can be a multiple of at least one of the reference values. As soon as the threshold value is exceeded, the signal processing device outputs at least one control signal, which is transmitted to the display device. Upon receipt of the control signal, the display device outputs a visual and / or acoustic display signal.

[0020] In addition, the control signal can be transmitted as a first control signal and / or a second control signal to the gas detector and / or the spray probe when the threshold value is exceeded. The transmission takes place via a data connection. In this case, the spray probe and / or the gas detector are configured to also output an acoustic and / or visual indication signal upon receiving the control signal via the data connection. It is also conceivable for the spray probe to be configured to automatically stop spraying upon receiving the control signal.

[0021] The measurement of the test gas concentration with the measuring sensor during spraying with test gas is preceded by a reference measurement with the reference sensor. While the reference sensor measures the ambient concentration, the measurement location is not sprayed with test gas. Instead, a possible test gas concentration in the atmosphere surrounding the test object is measured without spraying the test object with test gas via the spray probe.

[0022] In one embodiment of the invention, the measured value of the test gas recorded by the test gas sensor device is recorded as the first measured value at the measuring location, while the test gas detector of the leak detection device records a second measured value of the gas evacuated from the test object. The first measured value can be transmitted from the test gas sensor device to the test gas detector. The test gas detector then determines the leak rate of a leak in the test object from the first measured value of the test gas sensor device and the second measured value recorded by the test gas detector. This leak rate value is output by the test gas detector. Accordingly, in this embodiment, the test gas concentration measured at the test location is taken into account when measuring the leak rate with the leak detection device.For example, if the first measured value (test gas concentration at the measurement location) is half the first measured value (test gas concentration in the test gas detector), the leak rate is twice the measured value. If the test gas concentration at the test location is only one-tenth of the test gas concentration in the test gas detector, the actual leak rate is ten times the measured leak rate. In general, the actual leak rate can be determined from the measured leak rate by multiplying the measured leak rate by the quotient of the second measured value and the first measured value.

[0023] In the following, exemplary embodiments of the invention are explained in more detail with reference to the figures. They show:

[0024] Fig. 1 is a schematic representation of a first embodiment,

[0025] Fig. 2 is a schematic representation of a second embodiment and

[0026] Fig. 3 is a block diagram of an embodiment.

[0027] Figs. 1 and 2 each show an embodiment of the test gas sensor device 12 with two thermal conductivity sensors, namely the measuring sensor 14 and the reference sensor 16. Both sensors 14, 16 are each electrically connected to a signal processing device 18, which is designed to store the measured values ​​received by the two sensors 14, 16 and to compare the measured values ​​of the measurement signal recorded by the measuring sensor 14 with a threshold value. The threshold value can be a multiple of at least one stored reference value.

[0028] A display device 20, which in the illustrated embodiments has an LED 22 as a light source for outputting an optical display signal, is electronically connected to the signal processing device 18. When the threshold value is exceeded, the signal processing device 18 generates a control signal, which is transmitted to the display device 20 to turn on the LED 22. The signal processing device 18 and the display device 20 are each electrically connected to a voltage source 24 for supplying power to the latter.

[0029] A housing carries, holds, and / or contains the measurement sensor 14, the reference sensor 16, the signal processing device 18, the display device 20, and the voltage source 24. The LED 22 is attached to the housing 26. The housing also carries the measurement sensor 14 and the reference sensor 16.

[0030] The housing 26 has a gripping area 28 and a display area 30. The gripping area 28 is designed to be grasped and held by the hand of a user of the test gas sensor device 12. The display area 30 adjoins the gripping area and is exposed when the user's hand encloses the gripping area 28.

[0031] In the embodiment shown in Fig. 1, the housing 26 is designed as a flat cuboid in the manner of a credit card. In the embodiment shown in Fig. 2, the housing 26 is designed as an elongated rod in the manner of a pen. The measuring sensor 14 and the reference sensor 16 are arranged at the outer, distal tip of the display region 26, opposite the grip region 26.

[0032] In both embodiments, the handle portion 28 carries or contains the signal processing device 18 and the voltage source 24, while the display portion 30 carries or contains the display device 26. The signal processing device 18 has an electronic amplifier circuit (not shown in the figures) for signal evaluation and communication with the display device 22.

[0033] Fig. 3 shows the leak detection device 10 according to the invention, which, in addition to the test gas sensor device 12, has a test gas spray device 32 with a hand-held spray probe 34 and a test gas source 36 connected to the spray probe 34. Furthermore, the leak detection device 10 has a test gas detector 38, which is gas-conductively connected to a vacuum pump 40 and to a connection 42 for connecting a test object 44.

[0034] A test specimen 44 connected to the test specimen connection 42 is evacuated by the vacuum pump 40, wherein the gas stream extracted from the test specimen 44 is passed through the test gas detector 38 and analyzed by the latter for the presence of test gas, wherein the quantity of test gas is also to be determined.

[0035] While the test object 44 is being evacuated, the exterior of the test object is actively sprayed with test gas at a measuring location 46 using the spray probe 34. The concentration of test gas in the region of the measuring location 46 is determined using the test gas sensor device 12 to determine whether a sufficient amount of test gas is sprayed to the measuring location 46, which in particular deviates sufficiently from the test gas concentration in the atmosphere surrounding the test object 44.

[0036] The measured values ​​recorded by the measuring sensor 14 are compared by the signal processing device 18 with previously recorded reference values. As soon as the measured values ​​exceed a threshold value related to the reference values, the signal processing device 18 outputs a first control signal, which is transmitted to the display device 20, which then activates a display by switching on the LED 22 on the test gas sensor device 12, which signals the sufficient presence of test gas at the measuring location 46. The signal processing device 18 also outputs a second control signal, which is transmitted via the electronic data connection 48 shown in dashed lines in Fig. 3 to the test gas detector 38 and to the spray probe 34, in order to also trigger a display there, which signals that sufficient test gas is present. The second control signal can also trigger an automatic shutdown of the spray probe 34.The measured values ​​measured by the test gas sensor device 12 can be referred to as first measured values, while the measured values ​​recorded by the test gas detector 38 are referred to as second measured values. The first measured values ​​are preferably transmitted from the test gas sensor device 12 to the test gas detector 38 via the electronic data connection 48, which can be wired or wireless. The test gas detector 38 then takes into account the test gas concentration recorded by the test gas sensor device 12 at the measuring location 46 when determining the actual leak rate. The leak rate value determined by the test gas detector 38 can be corrected using the product of the reciprocal of the test gas concentration recorded by the test gas sensor device 14 and the leak rate measured value, in order to thereby determine the actual leak rate from the measured leak rate.

Claims

Claims 1. Test gas sensor device (12) for detecting test gas during test gas leak detection according to the spray principle, with a measuring sensor (14) for measuring the test gas concentration at the measuring location (46), an electronic signal processing device (18) which is designed to compare at least one measured value recorded with the measuring sensor (14) with a reference value, to generate an electronic control signal when a threshold value of the measuring signal dependent on the reference value is exceeded, and a display device (20) which is connected to the signal processing device (18) and is designed to output an optical and / or acoustic display signal upon receipt of the control signal as soon as the measuring signal exceeds the threshold value.

2. Test gas sensor device (12) according to claim 1, with a reference sensor (16) for measuring the reference value as test gas concentration, temperature or humidity in the atmosphere surrounding the measuring location (46).

3. Test gas sensor device (12) according to claim 1 or 2, characterized in that the signal processing device (18) has an electronic amplifier circuit.

4. Test gas sensor device (12) according to one of the preceding claims, characterized in that the display device (20) has a light source (22) for outputting an optical signal and / or a loudspeaker for outputting an acoustic signal.

5. Test gas sensor device (12) according to one of the preceding claims, characterized in that the test gas sensor device (12) has a housing which has at least part of the display device (20) and / or part of the signal processing device (18), wherein a reference sensor (16) and the measuring sensor (14) are arranged on the housing.

6. Test gas sensor device (12) according to claim 5, characterized in that the measuring sensor (14) and the reference sensor (16) are arranged side by side.

7. Test gas sensor device (12) according to one of the preceding claims, characterized in that the housing (26) has a voltage source (24) for supplying the signal processing device (18) and / or the display device (20).

8. Test gas sensor device (12) according to one of the preceding claims, characterized in that the light source (22) and / or the loudspeaker are arranged on the housing (26) in such a way that the display signal is output to the outside of the housing (26).

9. Test gas sensor device (12) according to one of the preceding claims, characterized in that the housing (26) is elongated in the manner of a pin and has the voltage source (24), the display device (20), the signal processing device (18), a reference sensor (16) and / or the measuring sensor (14) in succession in the longitudinal direction.

10. Test gas sensor device (12) according to claim 9, characterized in that the reference sensor (16) and the measuring sensor (14) are arranged at a distal end of the elongated housing (26).

11. Test gas sensor device (12) according to one of the preceding claims, characterized in that the housing (26) has a gripping area (28) for manually enclosing the housing (26) and a display area (30) for the display device (20) protruding from the gripping area (28), wherein a reference sensor (16) and / or the measuring sensor (14) are arranged at an end of the display area (30) opposite the gripping area (28).

12. Leak detection device (10) with a test gas detector (38) connectable to a test object (44), a vacuum pump (40) connected to the test gas detector (38) and evacuating the test object (44), a spray probe (34) connected to a test gas source (36) for spraying the test object (44) with test gas at a measuring location (46) and a test gas sensor device (12) according to one of the preceding claims.

13. Leak detection device (10) according to claim 12, characterized in that the test gas sensor device (12) is connected to the spray probe (34) and / or to the test gas detector (38) by an electronic data connection (48) in order to transmit the control signal and to output an optical and / or acoustic signal to the spray probe (34) and / or the test gas detector (38) when the threshold value is exceeded.

14. Method for test gas leak detection with a leak detection device (10) according to one of the preceding claims, characterized by the steps: Spraying the test specimen (44) with the spray probe (34) at the measuring point (46) with test gas, Evacuating the test specimen (44) during spraying and analyzing the gas evacuated from the test specimen with the test gas detector (38), Detecting test gas at the measuring location (46) with the test gas sensor device (12) by recording a measured value and comparing the measured value with a reference value, Output of an optical and / or acoustic indication signal as soon as the measurement signal exceeds a threshold value, Stop spraying the measuring location (46) with the spray probe (34) when the display signal is output.

15. Method according to the preceding claim, characterized in that after comparing the measured value with a reference value, an electronic control signal is generated when the measured value exceeds a threshold value of the measurement signal dependent on the reference value, wherein the display signal is output as soon as the measurement signal exceeds the threshold value.

16. Method according to claim 14 or 15, characterized by the steps: Recording the reference value with the test gas sensor device (12) as test gas concentration, temperature or humidity in the atmosphere surrounding the measuring location (46), Saving the reference value, Comparing the recorded measured value with the stored reference value, Generating an electronic control signal when the measured value exceeds a threshold value of the measurement signal dependent on the reference value, and Output of an optical and / or acoustic indication signal as soon as the measurement signal exceeds the threshold value.

17. Method according to the preceding claim characterized by the steps: Recording the measured value of the test gas detector in the leak detector, recording the measured value of the test gas concentration at the test location by the test gas sensor device (12), transferring the measured value of the test gas concentration at the test location from the test gas sensor device (12) to the test gas detector (38), calculating the measured leakage from the measuring signal of the test gas detector (38) in the leak testing device and the test gas concentration measured at the test location, outputting the value calculated from the test gas concentration and the measured value of the test gas detector.

18. Method according to one of the preceding claims, wherein the measured value recorded with the test gas sensor device (12) is a first measured value, characterized by the steps: Recording a second measured value of the gas evacuated from the test specimen (44) with the test gas detector (38), Determining the leakage rate of a leak in the test object (44) from the first measurement signal and the second measurement signal.

19. Method according to the preceding claim, characterized in that the first measured value is transmitted to the test gas detector (38) and the test gas detector (38) determines and outputs the value of the leakage rate.

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