Field of the invention

The present invention relates to a gas flow measuring device intended to measure gas flows in a wet space by liquid displacement. Technical Background

Different types of liquid displacement gas flow measuring devices are known. For instance in WO 2010/120229 there is disclosed a measuring device for measuring an ultra-low gas flow, working by the principle of liquid displacement, wherein the measuring device comprises at least one cell comprising a gas inflow means, a gas compartment means with a predefined inner geometric physical volume and active volume, the gas compartment means having one gas accumulating end and one lifting end, the gas compartment means also defining a geometric gas collecting point inside of the gas compartment means during a gas filling cycle, the geometric gas collecting point moving further and further from the gas accumulating end to the lifting end during the gas filling cycle, and wherein the cell comprises a holding means having a pivoting element enabling the gas compartment means to pivot upwards when the geometric gas collecting point is positioned at the lifting end and the lifting force is larger than the down-pressing force at the lifting end, thereby releasing all of the accumulated gas in the gas compartment means, and then pivoting back to its initial standby position for new receipt and storage of gas during another gas filling cycle until next releasing sequence, and wherein the cell also comprises a sensor means provided to generate a signal and/or change the state of a signal when the gas compartment means is not in its initial standby position, wherein the gas storing capacity of the inside of the gas compartment means is larger at the gas accumulating end than at the lifting end and wherein the gas accumulating end has a higher vertical position than the lifting end at the initial standby position. Furthermore, in WO 2017/200464 there is disclosed a similar device as disclosed above, however in this case the space compartment is a closed wet space compartment.

The present invention is directed to a gas flow device which is suitable to handle not only ultra-low gas flows but also comparatively larger gas flows. The device according to the present invention is improved in terms of measuring gas flows which changes from very low gas flows to comparatively large gas flows.

Summary of the invention

The stated purpose above is achieved by a gas flow measuring device intended to measure gas flows in a wet space by liquid displacement, said gas flow measuring device having a first larger compartment with a definite and predefined inner geometric volume, the first larger compartment having one gas accumulating end and one lifting end and having a pivoting element enabling the first larger compartment to pivot upwards to a releasing position where the gas contained in the first larger compartment is released and then downwards again to its initial position ready to be filled with gas again, said first larger compartment operating according to the leverage effect, said gas flow measuring device also comprising a second smaller compartment contained inside of the first larger compartment, which second smaller compartment is arranged to be filled when the first larger compartment is in its releasing position.

As mentioned above, the gas flow measuring device according to the present invention is especially suitable for comparatively large gas flows. It should be noted that the gas flow measuring device according to the present invention can be applied to any volume, however, it makes sense mainly to large volumes where the movement of flipping up and down of the first larger compartment in the liquid would be slow. As will be explained further below, if a regular gas flow measuring device is used, considerable amount of gas is in the risk of escaping during the opening of a flow cell. This may be avoided by using a device according to the present invention.

As should be understood from above, the gas flow measuring device according to the present invention comprises two compartments where the second compartment is arranged to be filled with gas when the first large main compartment is in its releasing position. This function has several advantages. First of all, even if the main larger compartment is in its releasing position, or on its way to the releasing position, additional gas entering the device is possible to capture and measure. This implies that gas escape is avoided when the flow cell in its releasing position or on its way to the releasing position or on its back to its initial position from the releasing position. This is a great advantage of the device according to the present invention as it implies that the measuring device can handle comparatively large gas flows in a very smart way without any gas escape/leakage.

Secondly, when the smaller second compartment is filled accumulatively this event may drive the larger first compartment to pivot back to its initial position again faster than otherwise. Also this may be enabled by levering effect and no counter-weight is needed. This functionality provides for the possibility to measure also large gas flows in a very accurate way as the larger gas compartment is arranged in its releasing position a comparatively short time, when being in gas releasing mode, and during that time additional gas bubbles entering the gas flow measuring device is captured by the smaller second compartment.

In relation to the above it should be mentioned that the larger compartment and smaller compartment is linked to each other so that when one of them moves and changes its position, then the other also changes its position relatively.

Specific embodiments of the invention

Below there is provided and discussed some specific embodiments of the present invention.

According to one embodiment, the second smaller compartment has an open side which is the bottom side of the smaller compartment when the first larger compartment is in its releasing position, which open side enable for the second smaller compartment being arranged to be filled with gas when the first larger compartment is in its releasing position. According to one specific embodiment of the present invention, the second smaller compartment is formed by a limiter, such as a clap board.

According to yet another embodiment, the second smaller compartment is arranged to release gas into the first larger compartment at the initial position of the first larger compartment and wherein the second smaller compartment is arranged to trap gas inside of the second smaller compartment at at least the releasing position of the first larger compartment. In this regard it should be mentioned that suitably the second smaller compartment captures gas when the first larger compartment is in its releasing position, on its way to the releasing position or on its back to its initial position from the releasing position.

Different designs and sizes are possible according to the present invention. One example is provided in fig. 1.

In line with the above, according to one embodiment of the present invention, the first larger compartment is arranged with a longitudinal cross section in the shape of a triangle and/or a trapezoid, preferably a combined shape of a triangle and a trapezoid, more preferably a symmetrical triangle sitting on an asymmetrical trapezoid, preferably wherein an open bottom side of the first large compartment is the longest side of the first larger compartment. Again, one such example is shown in fig. 1.

In this regard it should be noted that various shapes are possible according to the present invention. The combination of triangle plus trapezoid is just one example. As another example, the larger compartment and thus two compartments can be integrated in one big trapezoid shape.

According to yet another embodiment, the pivoting element is arranged closer to a middle point of a longitudinal cross section than any of two end points of the longitudinal cross section. For a solution like the one provided by the present invention, this may be beneficial to provide an optimization from different perspectives. First of all it creates a suitable balance for the pivoting of the main first compartment based on leverage effect. Secondly, as a measuring device according to the present invention comprises also a smaller second compartment, this type of positioning of the pivoting element may be suitable and beneficial also for the second smaller compartment as such. As mentioned, the first and second compartments are linked to each other, and a positioning with the pivoting element arranged closer to a middle point provides a good balance for the leverage effect of both compartments, relatively to each other. This may be understood from viewing e.g. fig. 1 .

In relation to the above it should be noted that, in order to improve the sensitivity, one can use the lifting effort by providing the flow cell so that the geometric shape of a right side is longer than a left side, so that a larger lifting force can be generated, and accumulated gas can reach a far distance to the flipping point on the right side. See for instance one such alternative in fig. 1 .

According to one embodiment of the present invention, the second smaller compartment has an open side which is the bottom side of the smaller compartment when the first larger compartment is in its releasing position, and wherein the open side is the longest side of the smaller compartment. Again, one such example is shown in fig. 2. Here it can be seen that the open sides, i.e. the gas receiving sides, of each of the compartments are the longest sides of these compartments.

According to yet another embodiment, the pivoting element is arranged at a vertical distance from a bottom side of the first large compartment. This placement of the pivoting element is of interest to provide a balance or optimal point when the larger compartment and thus flow cell starts to flip over from its initial position to its gas releasing position. When the gas is trapped in the first larger compartment which is above horizontal level of the pivoting element, the first larger compartment will stand its initial position. Instability will increase when the trapped gas is continuously increased and push the water level below the horizontal level of the pivoting element. It is at this situation, the first larger compartment will lose its balance and flip over to its releasing position. This also implies that the shorter distance from the pivoting element to the bottom line of the first larger compartment, the more gas will be trapped inside the compartment before flipping over and releasing the trapped gas. In other words, this aspect is related to the volume size of entrapped gas volume. When the pivoting element (point) is placed at a higher vertical distance from the bottom, less entrapped gas is expected before flipping over the flow cell. On the other hand, if the pivoting element is placed close to the bottom part, then the flow cell can hold more entrapped gas before flipping over to release the entrapped gas. As should be understood, a suitable balance here is preferred, i.e. placing a pivoting element at a distance from a bottom side of the first large compartment.

According to one embodiment this distance is in a range from 30 - 60% of the full distance from the bottom to the top. As may be seen in the figures, a placing of the pivoting element more or less in the middle of the first larger compartment.

Also other components may be part of the gas flow measuring device according to the present invention. According to one specific embodiment of the present invention, the gas flow measuring device comprises a bottom stand connected to the first larger compartment via pivoting elements on each longitudinal side of the first larger compartment. One alternative is shown in fig. 1.

Moreover, the first larger compartment may be provided with one or more extra weights, suitably close to the pivoting endpoint, to ensure an efficient driving force from the releasing position and back to its initial position of the first larger compartment. Such an extra weight positioned as far from the pivoting element as possible, that is at the endpoint or close to it, will also provide further stability ensuring that once the first larger compartment starts to pivot upwards, then this procedure is performed efficiently, meaning that the risk of releasing only a small part of the gas inside the first larger compartment and then pivoting back again to its initial position is suppressed.

Furthermore, according to yet another embodiment of the present invention, the gas flow measuring device comprises a sensor detecting a position change for the gas flow measuring device. According to one embodiment, the sensor detecting a position change for the gas flow measuring device is a magnetic sensor, motion sensor, optical coupler, or any kind of light emitting diode & receiver, IR infrared emitter & receiver and LED- photo diode & photo transistor, ultrasonic detector, camera unit, preferably a magnetic sensor. It should be noted that any sensor that can detect movement is possible to use according to the present invention. According to yet another embodiment of the present invention, the gas flow measuring device comprises at least one temperature sensor and at least one pressure sensor. Also these sensors may be beneficial to include to detect changes.

Also other features in relation to the second smaller compartment is of interest in relation to the present invention. According to one embodiment, the second smaller compartment, when containing accumulated gas inside, is arranged to drive the first larger compartment back to its initial position from its releasing position. One such alternative is shown in the figures, see especially fig. 2.

It should be noted that the gas flow measuring device according to the present invention may have a so called closed or open design. A closed first larger compartment implies that this is totally sealed to the outside and is only connected to the outside via a gas inlet and a gas outlet. Such a closed first compartment is preferred for certain technical applications.

According to the present invention there is also provided a method comprising using a gas flow measuring device according to the present invention, for trapping gas into the second smaller compartment when the first larger compartment is in its releasing position. Moreover, according to yet another embodiment these is provided a method comprising using a gas flow measuring device according to the present invention, for driving back the first larger compartment to its initial position from its releasing position by means of the second smaller compartment containing accumulated gas inside and as such pushing the first larger compartment to flip back to its initial position. Detailed description of the drawings

In fig. 1 there is shown one embodiment of the present invention. In this embodiment, the gas flow measuring device has a first larger compartment 2 with a definite and predefined inner geometric volume, the first larger compartment 2 having one gas accumulating end 3 and one lifting end 4 and having a pivoting element 5 enabling the first larger compartment 2 to pivot upwards to a releasing position where the gas contained in the first larger compartment 2 is released and then downwards again to its initial position ready to be filled with gas again, said first larger compartment 2 operating according to the leverage effect, and wherein the gas flow measuring device 1 also comprises a second smaller compartment 6 contained inside of the first larger compartment 2, which second smaller compartment 6 is arranged to be filled when the first larger compartment 2 is in its releasing position. Furthermore, in this case, and very suitably, an open bottom side 20 of the first large compartment 2 is the longest side of the first larger compartment 2. Moreover, according to this embodiment, the second smaller compartment 6 has an open side 60 which is the bottom side of the smaller compartment 6 when the first larger compartment 2 is in its releasing position, preferably wherein the open side 60 is the longest side of the smaller compartment 6.

According to the specific embodiment shown in fig. 1 , the pivoting element 5 is arranged closer to a middle point 7 of a longitudinal cross section than any of two end points 8, 9 of the longitudinal cross section. In figs. 2a - c there are shown different side views of an embodiment such as the one shown in fig. 1 .