Spray device for pulsed spraying of test gas from a test gas reservoir and corresponding method

Abstract

The invention relates to a spray device (12) for pulsed spraying of test gas from a test gas reservoir (18, 19), comprising a test gas line (22) which has a test gas inlet (16) for connection to the test gas reservoir (18, 19), a test gas outlet (20), at least one electronically controllable first valve (V1) arranged between the test gas inlet (16) and the test gas outlet (20), and a first flow restrictor (D1) arranged between the first valve (V1) and the test gas outlet (16), and comprising an electronic control device (26) connected to the first valve (V1), which control device (26) is configured to repeatedly open and close the first valve (V1) in order to spray the test gas in multiple successive pulses via the first valve (V1) and through the test gas outlet (20).

Description

[0001] Spray device for pulsed spraying of test gas from a test gas reservoir and corresponding procedure

[0002] The invention relates to a spray device for spraying test gas onto a test specimen during test gas leak detection. For this purpose, the test specimen is evacuated via a vacuum pump and connected to a gas detector. The evacuated test specimen is sprayed externally with test gas from the spray device, while the gas extracted from the test specimen is analyzed by the gas detector. When the test specimen is sprayed with test gas in the area of ​​a leak, the proportion of test gas in the analyzed gas increases.

[0003] Spray devices for dispensing test gas are often called spray guns. These have a spray lance connected to a test gas container. When a trigger on the spray device is activated, test gas flows from the container through the lance and is sprayed as it exits.

[0004] The invention is based on the objective of providing an improved spraying device for spraying test gas from a test gas supply and an improved method for spraying test gas.

[0005] The spraying device according to the invention is defined by claim 1. The spraying method according to the invention is defined by claim 9.

[0006] The spray device according to the invention comprises a test gas line having a test gas inlet for connection to a test gas reservoir and a test gas outlet. The test gas inlet is typically arranged at a first end of the test gas line, while the test gas outlet is arranged at the opposite second end of the test gas line. At least one electronically controllable first valve is arranged between the test gas inlet and the test gas outlet. A throttle is arranged between the first valve and the test gas inlet. An electronic control device is connected to the first valve and is configured to repeatedly open and close the first valve in order to transport the test gas from a test gas reservoir connected to the test gas inlet through the first valve to the test gas outlet in several successive pulses and to spray it through the test gas outlet.

[0007] One variant of the spray device may also include a test gas reservoir connected to the test gas inlet. The test gas reservoir is preferably removable and interchangeable with another test gas reservoir.

[0008] By pulsedly actuating or opening the valve during the spraying of test gas, the test gas is expelled in the form of several successive pulsed sprays. This results in lower test gas consumption compared to continuous spraying without pulsed actuation of the valve. Furthermore, with pulsed spraying, the test gas is expelled through the test gas outlet at a higher flow velocity than with continuous spraying. This is because, when the valve is closed, the test gas accumulates upstream of the valve, increasing the test gas pressure. This increased test gas pressure leads to a higher flow velocity when the valve is opened, thus increasing the spraying range. Therefore, pulsed spraying consumes less test gas than continuous spraying while simultaneously increasing the distance the test gas travels after exiting the test gas outlet.

[0009] A section of the test gas line containing the throttle and the first valve can be bypassed by at least one first bypass line. The bypass line is part of the spraying device and has a different flow resistance for the test gas than the bypassed section of the test gas line. Preferably, the bypass line has a second valve connected to the electronic control device. Each subsequent bypass line can accordingly also have a further valve connected to the electronic control device. The control device is configured to repeatedly open and close each subsequent valve independently of the first valve in such a way as to transport the test gas in several successive pulses through the respective valve and to the test gas outlet, and to spray it through the test gas outlet.

[0010] By actuating one or more of the valves, the strength, i.e., the flow velocity of a spray burst and the flow rate of the sprayed gas can be changed in order to alter the quantity and / or the range of a spray pulse.

[0011] Between the first valve and the throttle and / or upstream of a valve, at least one of the bypass lines, and preferably each bypass line, an accumulation volume for the test gas is provided. Each accumulation volume is designed such that, when the valve is closed, the test gas accumulates in the respective accumulation volume, the accumulated amount of gas being sufficient to continuously expel test gas through the valve and from the test gas outlet during a subsequent opening phase of the respective valve until the valve is subsequently closed. Each accumulation volume can vary in size and shape. In relation to the conductance of the throttle or...The bypass line must be designed such that the pressure of the test gas within the accumulation volume is sufficient at the end of the valve's closing phase to spray the test gas during the subsequent opening phase until the valve closes, without the spray pattern ceasing or the flow velocity of the expelled test gas decreasing significantly during the opening phase. For this purpose, the accumulation volume should be designed according to the conductivity of the respective throttle, bypass line, or test gas line, the test gas pressure in the connected test gas reservoir, and the duration of the opening and closing phases of the respective valve.

[0012] The following may apply to the nature of the accumulation volume, for example: where

[0013] V is the volume of the accumulation volume, q is the gas flow through the test gas outlet of the spray device, f is the modulation frequency with which the respective valve is opened and closed,

[0014] Pd is the pressure at the pressure reducer, namely at the end of the pressure reducer facing the valve, Patm is the ambient pressure in the atmosphere surrounding the spray device and

[0015] A is the percentage of gas directly expelled, i.e., the proportion of time the valve is open during modulation.

[0016] The percentage of directly expelled gas A determines what proportion of the gas in the accumulation volume is directly expelled. It is advantageous to keep this proportion low. The percentage of directly expelled gas A should therefore be between 10% and 50%, i.e., approximately 0.1–0.5. For example, if the gas flow through the test gas outlet of the spray device is q = 12 sccm = 0.2 mbar l / s and is modulated at a frequency of f = 5 Hz, and the percentage of directly expelled gas A = 0.1, this means that the gas is expelled within 0.02 seconds. If Pd = 1.3 bar and Patm = 1 bar, this results in a suitable volume of 0.013 cm³. 3 , in order to expel only 10% of the gas. For a percentage of directly expelled gas A = 1, where all the gas is expelled, the resulting maximum volume is then 0.1 cm³. 3 -

[0017] The test gas line may have a pressure regulator between the first restrictor and the test gas connection. This regulator is designed such that, upstream of the regulator (i.e., on the side facing the test gas connection), the test gas pressure is higher when a test gas reservoir is connected than downstream (i.e., on the side facing the test gas outlet). A pressure gauge may be provided between the pressure regulator and the test gas connection to measure the pressure within the test gas line upstream of the regulator. This pressure typically corresponds to the test gas pressure in a connected test gas reservoir.An electronic evaluation device can be designed to determine, based on the measured pressure value, the quantity of test gas present in the connected test gas supply and / or the spray duration remaining for the test gas present in the connected test gas supply and / or the spray pulses remaining for the test gas present in the connected test gas supply.

[0018] The electronic evaluation device can be integrated into the spraying device, i.e., housed within a common enclosure. The electronic evaluation device can be directly connected to the pressure gauge to receive the reading. Alternatively, the pressure gauge reading could be displayed elsewhere, for example, at the leak detector location, such as on a display on the leak detector, and manually entered by a user into the user interface of the electronic evaluation device. Direct, automatic electronic communication between the pressure gauge and the electronic evaluation device is therefore not strictly necessary.

[0019] The pressure gauge and evaluation device can be used to determine the quantity of test gas in a connected test gas reservoir, for example taking into account the volume within the test gas reservoir and the gas density of the test gas.

[0020] Alternatively or additionally, the pressure gauge can be located on the low-pressure side of the pressure regulator. Using this pressure gauge, in conjunction with the pressure gauge on the high-pressure side of the pressure regulator, the pressure drop across the pressure regulator during pulsing can be measured. Furthermore, this pressure gauge can be used to measure the gas flow downstream of the pressure regulator. The spraying device can, in particular, include a counting device designed to detect and count each spray pulse, i.e., each ejected spray burst, in order to determine, taking into account the amount of test gas in the supply at the start of spraying or after connecting a new supply, the number of remaining spray pulses possible with the remaining test gas in the connected supply.When determining the remaining spray pulses, the gas volume of each spray must be taken into account, which depends on the duration of the opening phase of the respective valve and on the conductivity of the test gas line or any bypass lines. Furthermore, the counting device can be designed to account for the loss of gas volume in the connected test gas supply over time due to leakage.

[0021] In particular, the counting device can be connected to the electronic control device and / or the electronic evaluation device in order to, for example, record the duration of the opening phase of a valve and the actuation of a valve from the control device and to obtain the quantity of test gas in the connected test gas supply from the evaluation device.

[0022] The electronic control device can, in turn, be configured to modify or limit the pulse duration, pulse frequency, and / or number of pulses of a spray by appropriately controlling at least one of the valves, depending on the determined remaining spray duration and / or remaining spray bursts. The pulse duration is the length of the opening phase of a valve. The pulse frequency is the number of opening and closing cycles of a valve within a unit of time. The number of pulses is the number of opening phases of a pulsed spray burst during activation of the spray device.

[0023] The spray device is activated by a trigger or button, which is pressed by an operator and generates a control signal to the control unit to actuate one of the valves. It is also possible to trigger the device remotely via a digital signal. For this purpose, the control unit can, for example, receive a remotely triggered control signal via the user interface, which then activates the valves.

[0024] The electronic control device can be configured, in particular, to select an initial spray range at the beginning of each spraying process by appropriately pulsing the valves, i.e., by appropriately actuating, opening, and closing a valve or by selecting a flow path for the test gas from the test gas connection through the test gas line and / or through one or more of the bypass lines. The control device is further configured, after a spraying process with an initial range, to increase the sensitivity of the leak detection by reducing the flow through the test gas outlet by selectively actuating one or more valves and / or by changing the flow path for the test gas through the test gas line and / or through one or more of the bypass lines.The flow through the test gas outlet is reduced more and more to increase the sensitivity of the leak detection as the spray device gets closer to a leak.

[0025] It is conceivable that the spraying device is equipped with a distance sensor that measures the distance to a surface to be sprayed and changes the flow through the test gas outlet depending on the measured distance. In this context, the term "flow through the test gas outlet" refers to the flow velocity or flow rate of the test gas exiting the outlet.

[0026] In the inventive method for pulsed spraying of test gas with a spray device of the type described above, several successive spray pulses, which can also be referred to as spray bursts, are generated by repeatedly opening and closing one of the valves at short intervals. When the valves are closed, the pressure of the test gas increases upstream of each closed valve, e.g., within an accumulation volume for the test gas located upstream of the valve. When at least one of the valves is opened again, the test gas is expelled from the test gas outlet at a higher velocity and over a greater range due to the increased pressure than in the case of continuous spraying with a permanently open valve or valves.

[0027] In the method according to the invention, the pressure of the test gas in a test gas reservoir connected to the test gas connection can be determined. As described above, the quantity of test gas in the test gas reservoir can be determined from the pressure. Knowing the duration of the valve opening phases and the respective conductances of the upstream throttles or the test gas line or respective bypass line, the remaining number of possible spray strokes can be determined from the quantity of test gas in the test gas reservoir. By counting each spray stroke, it can be calculated how many spray strokes remain for the test gas in the test gas reservoir. Alternatively or additionally, according to the invention, the duration of the remaining spraying until the test gas in the test gas reservoir is consumed can be calculated.

[0028] The remaining spray duration and / or the number of remaining spray pulses determined in this way can be displayed on a display of the spray device.

[0029] The following section provides a more detailed explanation of exemplary embodiments of the invention with reference to the figures. The figures show:

[0030] Fig. 1 shows a first embodiment,

[0031] Fig. 2 shows a second embodiment,

[0032] Fig. 3 shows a third embodiment and Fig. 4 a fourth embodiment.

[0033] In all embodiments, the spray device 12 has a closed housing 14 with a test gas connection 16 for a test gas supply 18, 19 and with a test gas outlet 20 through which the test gas is sprayed from the test gas device.

[0034] The test gas connection 16 and the test gas outlet 20 are connected by a test gas line 22. A section 24 of the test gas line 22 has an electronically controlled first valve VI and a first throttle Dl. The first valve VI is electrically connected to an electronic control device 26, which is configured to open and close the first valve VI. During an opening phase, the control device 26 holds the first valve VI open, and during a closing phase, it holds it closed. The opening and closing phases alternate at short intervals, resulting in pulsed actuation of the first valve VI to expel test gas from the test gas outlet 20 in the form of short, successive bursts. An accumulation volume Al is formed between the first valve VI and the first throttle Dl, in which test gas accumulates when the valve VI is closed until the valve VI is opened again.

[0035] The test gas line 22 has a pressure reducer 28 between the first throttle D1 and the test gas connection 16. The pressure reducer 28 is designed such that, when a test gas reservoir 18 is connected to the test gas connection 16, the test gas pressure in the test gas line 22 is higher upstream of the pressure reducer 28 than downstream of the pressure reducer 28. Upstream refers to the side facing the test gas connection 16, while downstream refers to the side facing the test gas outlet 20. A test gas reservoir 18 is detachably connected to the test gas connection 16, so that the test gas reservoir 18 can be replaced by another test gas reservoir 19.

[0036] A pressure gauge PI is connected to the test gas line upstream of the pressure reducer 28 in order to measure the pressure in the test gas line 22 upstream of the pressure reducer 28, which essentially corresponds to the pressure in the connected test gas reservoir 18.

[0037] The test gas device 12 includes an electronic evaluation device 30, also arranged in the housing 14, which is configured to determine the quantity of gas present in the test gas reservoir 18 based on the pressure measured by the pressure measuring device PI and taking into account the volume of the connected test gas reservoir 18. For this purpose, it is conceivable to transmit the measured pressure value directly from the pressure measuring device PI to the evaluation device 30, as shown in Fig. 1, e.g., by means of a direct electronic or electrical data connection.

[0038] A preferred alternative is shown in Fig. 4, in which the measured pressure value can be transmitted to a separate device, such as a leak detector 32, e.g., wirelessly. The pressure measuring device PI is connected to a transmitter 36 of the spray device 12. The transmitter 36 transmits the measured value to the leak detector 32. The transmitted pressure value is displayed on a display 38 of the leak detector 32. A user can read the pressure value from the display 38 and enter it into a user interface 40, which is, for example, located on the housing 14 of the spray device 12. The user interface 40 is electronically connected to the evaluation device 30 and transmits the entered value to the evaluation device 30. In this variant shown in Fig. 4, there is no direct data connection between the pressure measuring device PI and the evaluation device 30. In the exemplary embodiments shown in Fig.2 and 3 are both transmission variants, i.e. according to Fig. 1 or Fig. 4, for a transmission of the measured value from the pressure measuring device PI to the evaluation device 30 is conceivable.

[0039] In all embodiments, a counting device 42 is also provided, which is electronically connected to the control device 26 and the evaluation device 30. The connection to the control device 26 enables the counting device 42 to detect and count each actuation of a valve, its duration, and thus each spray pulse of the spray device 12. The connection to the evaluation device 30 enables the counting device to detect the quantity of gas within a connected gas supply 18 at the beginning of a spraying process and / or after connecting a new test gas supply, as well as the resulting remaining spray pulses and / or the remaining spray duration. The counting device 42 then counts the number of remaining spray pulses backward with each valve actuation.The counter 42 is further connected to a display 44 of the spray device in order to show on the display 44 the number of remaining spray bursts and / or the remaining spray duration determined in this way. The display 44 can alternatively or additionally be connected to the evaluation device 30 and / or to the control device 26.

[0040] The embodiment shown in Fig. 2 differs from that shown in Fig. 1 in that section 24 is bypassed by a bypass line 46, which has a second valve V2 and a second throttle D2 upstream of the second valve V2. A second accumulation volume A2 is formed between the second valve V2 and the second throttle D2. The second valve V2 is also connected to the electronic control device 26 in order to be actuated by it.

[0041] The embodiment shown in Fig. 3 differs from that shown in Fig. 2 in that section 24 is bypassed by several, namely n-1, bypass lines 46. The number n of bypass lines is generally a natural number. Each of the bypass lines 46 is equipped accordingly with a valve V2...Vn, a restrictor D2...Dn, and an accumulation volume A2...An. The restrictors of the bypass lines have different flow resistances in order to produce different conductances of the bypass lines 46. Each accumulation volume is adapted to the respective restrictor. By selectively opening one or more of the valves VI, V2...Vn via the control device 26, the gas flow, i.e., the flow rate or velocity of the gas flow of test gas through the test gas outlet 20, can be selectively changed.

[0042] In all of the illustrated embodiments, a first filter Fl is provided between the first throttle Dl and the pressure reducer 28 and a second gas filter F2 is provided downstream of the test gas connection 16.

[0043] A further restrictor 48 is provided at the test gas outlet 20. Upstream of the restrictor 48, a filling line 50 branches off from the test gas line 22 and reconnects to the test gas line 22 downstream of the filter F2. The filling line 50 allows for easy refilling of the connected gas reservoir 18 by introducing test gas into the test gas outlet 20. The filling line 50 is shown with a restrictor D0, which may be a physical component or simply represent the flow resistance of the filling line 50 itself.

[0044] The filling line is further equipped with a non-return valve V0, which blocks in the direction of flow from the test gas connection 16 to the test gas outlet 20 and opens automatically in the direction of flow from the test gas outlet 20 to the test gas connection 16 in the event of an applied defined pressure difference.

Claims

Claims 1. Spraying device (12) for pulsed spraying of test gas from a test gas reservoir (18, 19), comprising a test gas line (22) having a test gas inlet (16) for connection to the test gas reservoir (18, 19), a test gas outlet (20), at least one electronically controllable first valve (VI) arranged between the test gas inlet (16) and the test gas outlet (20), and a first throttle (D1) arranged between the first valve (VI) and the test gas inlet (16), and an electronic control device (26) connected to the first valve (VI) which is configured to repeatedly open and close the first valve (VI) in order to spray the test gas in several successive pulses via the first valve (VI) and through the test gas outlet (20).

2. Spray device (12) according to claim 1, characterized in that a section (24) of the test gas line (22) comprising the first throttle (D1) and the first valve (VI) is bypassed by at least one first bypass line (46), wherein the bypass line (46) has another The flow resistance for the test gas is greater than that of the bridged section (24) of the test gas line (22).

3. Spray device (12) for pulsed spraying of test gas from a test gas reservoir (18, 19) according to claim 2, characterized in that the bypass line (46) has at least a second valve (V2) connected to the electronic control device (26) and the control device (26) is configured to repeatedly open and close the second valve (V2) independently of the first valve (VI) in order to spray the test gas in several successive pulses via the second valve (V2) and through the test gas outlet (20).

4. Spray device (12) according to one of the preceding claims, characterized in that an accumulation volume (Al, A2...An) is formed between the first valve (VI) and the first throttle (Dl) and / or upstream of a valve (V2...Vn) of at least one bypass line (46) such that, when the valve is closed, a quantity of gas accumulates in the accumulation volume (Al, A2...An) that is sufficient to continuously expel test gas from the test gas outlet (20) during the opening phase of the valve until the valve is closed.

5. Spray device (12) according to one of the preceding claims, characterized in that the test gas line (22) has a pressure reducer (28) between the first throttle (Dl) and the test gas connection and a pressure gauge (PI) between the pressure reducer (28) and the test gas connection, wherein an electronic evaluation device (30) is provided and configured to determine, on the basis of the pressure value measured with the pressure gauge (PI), the quantity of test gas present in the connected test gas reservoir (18) and / or to determine the spray duration remaining for the test gas present in the connected test gas supply (18) and / or the spray pulses remaining for the test gas present in the connected test gas supply (18).

6. Spray device (12) according to one of the preceding claims, characterized in that a counting device (42) is provided which is designed to count each spray pulse in order to determine, taking into account the amount of gas in the test gas supply (18) at the beginning of spraying or after connecting a new test gas supply (18, 19), the number of remaining spray pulses for the test gas that is still present in a test gas supply (18) connected to the test gas connection.

7. Spray device (12) according to claim 5 or 6, characterized in that the electronic control device is configured to change or limit the pulse duration, pulse frequency and / or number of pulses of a spray stroke by appropriately controlling at least one of the valves (VI, V2...Vn) depending on the result of the determination of the spray duration and / or the number of spray bursts.

8. Spray device (12) according to one of the preceding claims, characterized in that the electronic control device is configured to select a first spraying range at the beginning of a spraying process by pulsing or selecting the flow path through the test gas line (22) and / or through a bypass line (46) and subsequently, to increase the sensitivity of the leak detection, to control the flow through the test gas outlet (20) by selectively controlling one or more of the valves (VI, V2...Vn) and / or by changing the to reduce the flow path the closer the spray device (12) is brought to a leak.

9. Method for spraying test gas with a spray device (12) according to one of the preceding claims, characterized in that several spray pulses are generated by repeatedly opening and closing the first valve (VI) and / or at least the second valve (V2), wherein, with the valve and / or valves closed, the pressure of the test gas in the test gas line (22) between the test gas reservoir (18, 19) and a valve increases, and when one of the valves is opened again, the gas is expelled from the test gas outlet (20) at a higher speed and with a greater range due to the increased pressure than in the case of a lower pressure, for example, during continuous spraying with a permanently open valve.

10. Method for spraying test gas according to claim 9, characterized in that the remaining spray duration and / or the number of remaining spray pulses for the test gas present in a test gas reservoir (18) connected to the test gas connection is determined by determining the pressure in the test gas reservoir (18, 19).

11. Method for spraying test gas according to claim 10, characterized in that, in order to determine the pressure in the test gas reservoir (18, 19), the pressure in the test gas line (22) between the first valve (VI) and the test gas reservoir (18, 19) or the pressure between a pressure reducer (28) arranged between the first valve (VI) and the test gas reservoir (18, 19) and the test gas reservoir (18, 19) is measured.

12. Method for spraying test gas according to one of the preceding claims, characterized in that the number of remaining spray pulses for the test gas, which is connected to the test gas connection, is The amount of test gas still available in the connected test gas supply (18) is determined by counting each spray pulse, taking into account the amount of gas in the test gas supply (18, 19) at the beginning of spraying or after connecting a new test gas supply (18, 19).

13. Method for spraying test gas according to claim 11 or 12, characterized in that the determined remaining spray duration and / or the remaining spray pulses are displayed on a display (44) of the spray device (12).

14. Method for spraying test gas according to the preceding claim, characterized in that the pulse duration, pulse frequency or number of pulses used in a spraying process is changed and / or limited depending on the result of determining the remaining spray duration or number of remaining spray pulses.

15. Method for spraying test gas according to one of the preceding claims, characterized in that at the beginning of a spraying process the test gas is expelled by suitable pulsing of the first and / or at least second valve and / or by suitable selection of the flow path with a first range, while subsequently, to increase the sensitivity of the leak detection, the flow through the test gas outlet is reduced by pulsing the first and / or at least second valve and / or by changing the flow path.

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