Bubble separator and arrangement for optically measuring a liquid

Abstract

Bubble separation device (50) comprising• a first channel (51) with an inlet (55) and an outlet (56) for conveying liquid, in particular oil,• and a second channel (52) branching off from the first channel (51) for discharging gas bubbles from the first channel (51),• wherein the first channel (51) is arranged at an angle α of 35° to 55° to the horizontal (200) and the inlet (55) is higher than the outlet (56),• wherein the second channel (52) branches off parallel to the horizontal (200) with a deviation of -10° to +10°,• and wherein the first channel (51) has a first diameter (53) and the second channel has a second diameter (54), wherein the two diameters (53, 54) differ from one another by at most 30%, preferably at most 15%.

Description

[0001] The present invention relates to a bubble separator, which is used in particular upstream of a measuring device. Both the measuring device and the bubble separator can be used together in an arrangement for optical measurement shown here.

[0002] For example, systems for detecting (measuring) diesel fuel in engine oil are known from the state of the art. The specific measurement task involves determining the concentration of diesel fuel in the engine oil, particularly the low-boiling components, the biocomponent (e.g., fatty acid methyl ester), and the soot content.

[0003] US 2020 / 0 072 803 A1 shows a measuring device with a channel for passing a liquid. Windows are located on the channel for optical measurement of the liquid.

[0004] EP 3 553 364 A1 discloses a device for separating gas bubbles from a liquid. The device features a central chamber into which an inlet opens and from which an outlet leads. Gas can be released from this chamber via a valve.

[0005] Further researched prior art is shown in WO 2019 / 232 305 A1, DE 80 22 641 U1, DE 10 2011 102 430 A1 and US 2014 / 0 146 307 A1.

[0006] The object of the present invention is to provide a corresponding measuring device with which optical measurement of a liquid, in particular oil, is possible in a simple and rapid manner.

[0007] The problem is solved by the features of the independent claims. The dependent claims relate to advantageous embodiments of the invention.

[0008] A measuring device for optically measuring a liquid is provided, which can be used in an arrangement together with a bubble separation device according to the invention. The liquid is, in particular, oil. The oil is preferably engine oil from an internal combustion engine. The internal combustion engine is, in particular, a diesel engine, so that the optical measurement can be used to determine how much diesel fuel has mixed into the engine oil.

[0009] The measuring device comprises a flow cell. The liquid to be measured is continuously pumped through this flow cell during the measurement. For this purpose, the flow cell comprises a housing. A liquid channel is formed in the housing. The liquid channel serves to convey the liquid through the flow cell. In particular, the liquid channel runs in a straight line through the housing.

[0010] Furthermore, a light channel is formed in the housing. The light channel intersects the liquid channel. In particular, the light channel runs straight through the housing. In particular, the light channel and the liquid channel are perpendicular to each other. The light channel is designed to transmit light through the liquid and thus to optically measure the liquid.

[0011] Within the scope of the invention, it was recognized that gas bubbles, in particular air bubbles, in the liquid to be measured interfere with optical measurement. In order to avoid this disruptive influence of the bubbles, it was recognized that the liquid channel should have a non-circular cross-section. The liquid channel has this non-circular cross-section in the area where the liquid channel intersects the light channel. The non-circular cross-section means that the bubbles do not move centrally through the liquid channel, but rather collect, for example, in the upper area of the non-circular cross-section. The light that is guided through the light channel has, in particular, a round cross-section and can intersect the liquid channel in such a way that it runs through an area of the liquid in which as few bubbles as possible are present.In particular, it is intended that the liquid channel is aligned horizontally so that the bubbles collect in the upper area of the non-circular cross-section due to gravity.

[0012] The cross-section of the fluid channel is preferably oval. The oval is preferably upright: Analogous to an ellipse, the oval has a major axis and a minor axis defined on it. The major axis is longer than the minor axis. The two axes are perpendicular to each other. In particular, the minor axis of the oval cross-section is oriented parallel to the horizontal, so that the bubbles collect in the upper region of the upright oval cross-section.

[0013] Particularly preferably, the length of the major axis is at least 1.2 times, preferably at least 1.5 times, the length of the minor axis. In a further preferred embodiment, the oval cross-section is designed as slit-shaped as possible, with the major axis being at least 3 times the length of the minor axis.

[0014] A first receptacle for connecting a light source to the light channel is preferably formed on the housing of the flow cell. The light source can be connected directly or via a suitable light guide.

[0015] Furthermore, a second receptacle is preferably provided for connecting a light-receiving optical fiber to the light channel. This second connection is used, in particular, to connect an optical fiber leading to the measuring unit.

[0016] Furthermore, a third receptacle for connecting a supply line to the fluid channel and / or a fourth receptacle for connecting a discharge line to the fluid channel is preferably provided. At the third and fourth receptacles for connecting the supply line and discharge line, the corresponding bore in the housing has, in particular, a round cross-section suitable for connecting the corresponding lines. The round cross-section transitions into the non-round cross-section of the fluid channel toward the center of the housing.

[0017] The corresponding recordings can be designed in any way to fulfill their purpose.

[0018] The measuring device preferably comprises the described light source, which is connected in particular to the first receptacle of the housing, and the described light guide, which is connected in particular to the second receptacle of the housing.

[0019] Furthermore, the measuring device preferably comprises a measuring unit. The measuring unit is optically connected to the light channel via the light guide.

[0020] In its simplest design, the measuring unit serves only to record the received light signals. The FTNIR spectra of the fluid are preferably analyzed directly in the measuring unit or in a higher-level or downstream unit. Based on these spectra, chemometrics can be used to determine, in particular, the concentration of low-boiling components, the biocomponent (e.g., fatty acid methyl ester), and the soot content in the fluid, especially in engine oil.

[0021] The invention features a bubble separator. This is used, in particular, upstream of the measuring device described above, so that the liquid to be measured first passes through the bubble separator and then through the measuring device.

[0022] The bubble separator comprises a first channel and a second channel. The two channels can be implemented, for example, by corresponding holes in a housing or by a corresponding arrangement of other lines. The first channel serves to convey the liquid, in particular the oil, from an inlet to an outlet of the first channel. Thus, one end of the first channel forms the inlet. The other end of the first channel forms the outlet.

[0023] The second channel branches off from the first channel. The second channel serves to remove gas bubbles from the first channel or from the liquid in the first channel. The gas bubbles can be removed along with some of the liquid.

[0024] Various tests have shown that for effective bubble separation, the two channels must be arranged at appropriate angles to each other. The first channel is positioned at an angle of 45 degrees to the horizontal, although efficient bubble separation also occurs when the first channel is positioned at an angle of 35 degrees to 55 degrees, preferably 40 degrees to 50 degrees, to the horizontal. The inlet is always higher than the outlet; thus, the liquid flows from top to bottom in the first channel.

[0025] The second channel branches off horizontally. Accordingly, the second channel is arranged parallel to the horizontal, whereby the advantageous bubble separation also occurs when the second channel is arranged at a deviation of -10 degrees to +10 degrees, in particular -5 degrees to +5 degrees, from the horizontal. The branch is arranged such that an acute angle is created between the branching second channel and the outlet of the first channel.

[0026] The diameters of the first and second channels are preferably the same. However, it is also intended that the two diameters differ by no more than 30%, preferably no more than 15%. Even with such slightly different diameters, effective bubble separation was observed in the test.

[0027] The invention preferably comprises an arrangement for optically measuring a liquid, preferably oil, comprising the described measuring device and the described bubble separation device, wherein the outlet of the bubble separation device is connected to the liquid channel of the measuring device, so that the liquid first flows through the bubble separation device and then through the measuring device.

[0028] Particularly preferably, the inlet of the bubble separation device and the outlet at the fluid channel of the measuring device are fluidically connected to an internal combustion engine. In particular, the connection is made to an engine oil pan of the internal combustion engine.

[0029] For example, using a suitable pump, engine oil can be pumped out of the engine oil pan and conveyed via the bubble separator into the measuring device, specifically the flow cell. From the flow cell, the engine oil flows back into the engine oil pan.

[0030] It is particularly preferred to install a heat exchanger upstream of the bubble separator to cool the engine oil accordingly. A flow heater can be installed upstream of the measuring device to heat the engine oil, which may have cooled too much, back to an optimal temperature for the measurement.

[0031] The invention further comprises a method for optically measuring a liquid, in particular oil. The method uses, in particular, the optical measuring arrangement described above. The method provides, in particular, that, during operation of an internal combustion engine, engine oil is removed from the internal combustion engine, passed through the described measuring device, and fed back into the internal combustion engine. Within the scope of the method according to the invention, the liquid is preferably measured using light in the measuring device. The light passing through the liquid is preferably evaluated using the described measuring unit.

[0032] Further details, features, and advantages of the invention will become apparent from the following description and the figures. They show: Fig. 1 a schematic view of an arrangement according to the invention, Fig. 2 a side view of a measuring device, Fig. 3 the in Fig. 2 marked section AA, Fig. 4 the in Fig. 3 marked section BB, Fig. 5 that in Fig. 4 marked detail V, and Fig. 6 a bubble separation device according to the invention.

[0033] In the following, the Fig. 1 to 6, an arrangement 100 with a measuring device 1 and a bubble separation device 50 is explained in detail according to an embodiment.

[0034] Fig. 1 shows purely schematically the arrangement 100 with an engine oil pan 101 of an internal combustion engine, a heat exchanger 102, a pump 103, a flow heater 104 as well as the measuring device 1 and the bubble separation device 50.

[0035] The bubble separator 50 is connected to the engine oil pan 101 by appropriate fluid-conducting connections. Between the bubble separator 50 and the engine oil pan 101 are the heat exchanger 102 for cooling the engine oil and the pump 103 for conveying it. The flow heater 104 is located between the bubble separator 50 and the measuring device. A return line leads from the measuring device 1 back to the engine oil pan 101.

[0036] The measuring device 1 comprises the Fig. 1 shows a purely schematic flow cell 2, a measuring unit 3, a light source 4, and a light guide 5. The light source 4 is arranged on the flow cell 2. The light passing through the liquid is guided via the light guide 5 to the measuring device 3. The light is evaluated in the measuring device 3, as explained in the general part of the description.

[0037] Fig. 2 to 5 show flow cell 2 in detail. Fig. 2 shows a side view. Fig. 3 shows section AA, Fig. 4 shows the section BB and Fig. 5 shows detail V.

[0038] The flow cell 2 comprises a housing 7 with a liquid channel 6 and a light channel 8 formed therein. The two channels 6, 8 are perpendicular to each other and each parallel to the horizontal 200.

[0039] At the two ends of the light channel 8, a first receptacle 11 for connecting the light source 4 and a second receptacle 12 for connecting the light guide 5 are formed.

[0040] Accordingly, the flow cell 2 comprises at the ends of the liquid channel 6 a third receptacle 13 for connecting a supply line for the liquid and a fourth receptacle 14 for connecting a discharge line to the liquid channel 6.

[0041] As particularly in the Fig. 4 and Fig. 5, the liquid channel 6 has an oval cross-section. In particular, the two receptacles 13, 14 with their round cross-sections merge into this oval cross-section in the center of the flow cell 2. The oval cross-section has Fig. 5 has a major axis 9 and a minor axis 10. The major axis 9 is significantly longer than the minor axis 10. Furthermore, the major axis 9 is vertical, so that any bubbles in the liquid collect in the upper region of the cross-section. The light passes through the center of this oval cross-section, thus essentially hitting liquid without bubbles.

[0042] Fig. 6 shows the Fig. 1 bubble separator 50 shown only schematically.

[0043] The bubble separator 50 has a first channel 51 and a second channel 52. The first channel 51 leads from its upper inlet 55 to its lower outlet 56. The first channel 51 is inclined at the angle α shown of approximately 45 degrees to the horizontal 200, resulting in a flow direction in the first channel 51 from top to bottom.

[0044] A second channel 52 branches off from the first channel 51 to remove bubbles from the liquid. The second channel 52 is essentially parallel to the horizontal 200. An acute angle of approximately 45 degrees exists between the downstream area of the first channel 51 and the second channel 52.

[0045] The two measures shown here, namely in particular the combination of the measuring device with the oval cross-section in the liquid channel 6 and the bubble separation device 50, result in the liquid being as bubble-free as possible being able to be measured with the light in the light channel 8. List of reference symbols: 1 measuring device 2 flow cell 3 measuring unit 4 Light source 5 light guides 6 Fluid channel 7 housings 8 light channels 9 Main axis 10 Minor axis 11 first recording 12 second shot 13 third recording 14 fourth recording 50 Bubble separator 51 first channel 52 second channel 55 inlet 56 Process 101 Engine oil pan 102 heat exchangers 103 Pump 104 instantaneous water heaters 200 Horizontal

Claims

[1] Bubble separator (50) comprising • a first channel (51) with an inlet (55) and an outlet (56) for conveying liquid, in particular oil, • and a second channel (52) branching off from the first channel (51) for removing gas bubbles from the first channel (51), • wherein the first channel (51) is arranged at an angle α of 35° to 55° to the horizontal (200) and the inlet (55) is higher than the outlet (56), • wherein the second channel (52) branches off parallel to the horizontal (200) with a deviation of -10° to +10°, • and wherein the first channel (51) has a first diameter (53) and the second channel has a second diameter (54), wherein the two diameters (53, 54) differ from each other by at most 30%, preferably at most 15%. [2] Arrangement (100) for optically measuring a liquid, preferably oil, with a measuring device (1) for optically measuring a liquid, preferably oil, comprising a flow cell (2) with • a housing (7), • a liquid channel (6) formed in the housing (7) for conveying the liquid, • and a light channel (8) formed in the housing (7) and intersecting the liquid channel (6) for passing light through the liquid for optical measurement, • wherein the liquid channel (6) has a non-circular cross-section, and with the bubble separator (50) according to claim 1, wherein the outlet (56) of the bubble separator (50) is connected to the liquid channel (6) of the measuring device (1). [3] Arrangement according to claim 2, wherein the cross section of the liquid channel (6) is oval. [4] Arrangement according to claim 3, wherein the oval cross-section has a main axis (9) and a secondary axis (10) perpendicular thereto, wherein the length of the main axis (9) is at least 1.2 times, preferably at least 1.5 times, the length of the secondary axis (10). [5] Arrangement according to one of claims 2 to 4, wherein the following is formed on the housing (7): • a first receptacle (11) for connecting a light source (4) to the light channel (8), • and / or a second receptacle (12) for connecting a light-receiving optical fiber (5) to the light channel (8), • and / or a third receptacle (13) for connecting a supply line to the liquid channel (6), • and / or a fourth receptacle (14) for connecting a drain to the liquid channel (6). [6] Arrangement according to one of claims 2 to 5, comprising a light source (4) and a light guide (5) at the two ends of the light channel (8) and a measuring unit (3) connected to the light guide (5). [7] Arrangement according to one of claims 2 to 6, wherein the inlet (55) of the bubble separator (50) and a discharge line on the liquid channel (6) of the measuring device (1) are fluidly connected to an internal combustion engine. [8] Method for optically measuring engine oil using the entire arrangement (100) according to one of claims 2 to 7, wherein during operation of an internal combustion engine, engine oil is removed from the internal combustion engine, passed through the measuring device (1) and fed back to the internal combustion engine.

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