CN111609896A

CN111609896A - Flow sensing device

Info

Publication number: CN111609896A
Application number: CN202010458661.4A
Authority: CN
Inventors: 斯特凡·贝斯勒
Original assignee: Ottotec Co ltd
Current assignee: Ottotec Co ltd
Priority date: 2019-11-04
Filing date: 2020-05-25
Publication date: 2020-09-01
Anticipated expiration: 2040-05-25
Also published as: CN111609896B; CN212585777U; DE102020128703A1

Abstract

The disclosed embodiments provide a flow sensing device. The device comprises a device housing (2) and a sensing unit (4) located in an inner space (13) of the device housing (2). Wherein a first pressure chamber (11) and a spaced apart second pressure chamber (12) are formed in the device housing (2), and the sensing unit (4) comprises at least one pressure sensor (41). The sensing unit (4) is at least adapted to determine a pressure difference (dP) between a first pressure (p1) in the first pressure chamber (11) and a second pressure (p2) in the second pressure chamber (12). The device has the advantages of simple manufacturing method and high durability.

Description

Flow sensing device

Technical Field

The present invention relates to a flow sensing device, and more particularly, to a mass flow sensing device.

Background

DE 2051829 a discloses a flow sensing device which generates a pressure difference. A constriction is provided in the conduit so that locations with different cross-sectional areas can be formed in the conduit. The pressure difference and the absolute pressure at the location are determined and the mass flow may be calculated based on the determined values.

DE 2630771 a discloses a similar sensing device, which describes a differential pressure sensor in more detail. A diaphragm is arranged between the two pressure chambers, which diaphragm is always held in a neutral position by the magnetic actuator, irrespective of the pressure difference. The control values of the actuators, in particular the energy consumption values, constitute input values for calculating the pressure difference dp.

WO 2009/030494 a1 discloses an apparatus for a mass flow metering system. The marker depositor is connected to the signal generator and introduces at least one marker into the flow channel, thereby causing a change in the flowing medium. The marker detection sensor is configured to detect a change in the flowing medium caused by introduction of the at least one marker.

For volumetric and mass flow meters, suitable sensors are connected to a pressure generating device such as the devices described above, orifices, venturi tubes, venturi nozzles, jets, pitot tubes, laminar flow meters, or any type of flow element that provides a pressure differential caused by the flowing fluid.

Typical problems with durable industrial sensors for automotive applications are the large size and high cost. Due to their large number of sensor elements, they have a very slow response time in the order of seconds, combined with a low sampling rate, which makes the measurement insufficient when a fast pulsating flow (>10Hz) needs to be measured. Therefore, such sensors are not suitable for use in the automotive industry.

Lightweight, compact, smart sensors using MEMS sensor elements and internal data processing are suitable for the automotive industry. They need to address problems such as chemical attack, condensation, heat resistance and thermal effects in a suitable way.

A conventional arrangement of sensors typically uses an elastomeric seal to separate pressure regions inside the sensor housing. In sealing a pressure sensor element, one or both pressure ports are typically sealed with respect to the sensor housing with an O-ring. From a manufacturing point of view, the installation of O-rings is an additional process that requires special equipment and labor (camera inspection, pressure testing, etc.) to control the correct installation to meet the vehicle production quality.

The positioning tolerances of the components, such as sensor components placed on a PCB (printed circuit board) inserted into the housing and sealed with an O-ring against the other housing part, must be small to ensure a correct sealing of the intermediate O-ring. Another drawback is the difference in thermal expansion of the outer sensor housing and the sensor elements which are typically mounted on an inner board or PCB board. The elongation coefficient of the plastic housing is significantly higher than that of the PCB. This causes mechanical stress on the part. In the case of high-precision pressure sensors and differential pressure sensors, this can lead to significant drift of the sensor signal. Since most pressure-based meters have a characteristic that the pressure difference and the flow rate have a quadratic dependence, a large metering error is caused.

Disclosure of Invention

It is an object of the present invention to provide an improved flow sensing device. This object is solved by the flow sensing device and the pipe assembly of the independent claims, embodiments being the subject matter of the dependent claims and the description. In particular, the flow sensing device is a mass flow sensing device.

The advantage of this device is that the manufacturing method is simple, so that a high durability can be achieved, in particular by sealing and fixing in such a way that the initial flow is cured after the component mounting is completed.

The mass flow sensing means is particularly positioned to measure the mass flow of air, exhaust gas, CNG/air or any mixture thereof in the internal combustion engine. In particular, the first and second measuring positions are located in a measuring duct inserted into the internal combustion engine. Since variations in the intake pipe from the vehicle to the engine can lead to metering deviations, the preferred measurement location is fixed relative to the engine, typically after the compressor and hot or cold EGR pipe.

Preferably, the measurement location is located after the compressor in the flow direction. The temperature of the medium here can generally be up to 260 ℃. In particular, in order to avoid active cooling of the sensor element and its internal electronics, the sensor component (i.e. the temperature probe) inserted into the measuring tube region can be designed to completely withstand the medium temperature. Furthermore, by allowing cold air to flow between the outer measuring tube and the gap between the sensor housing, cooling by natural convection is achieved and the use of thermal resistance from the medium air to the sensor element and the electronics is achieved.

The sensing means is particularly adapted to determine the flow rate of a pulsating fluid having a pulsation frequency of at least 10 Hz. In particular, the flowing medium is a gaseous fluid.

Drawings

The invention is described in more detail in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view of the device of the present invention;

FIG. 2 is a cross-sectional view of the device of FIG. 1 taken along section C-C of FIG. 3;

FIG. 3 is a view of the device of FIG. 1 taken along arrow A3 of FIG. 1;

FIG. 4 is a view of the device of FIG. 1 taken along arrow A4 of FIG. 1;

FIG. 5 is a cross-sectional view of the device of FIG. 1 taken along section A-A of FIG. 3;

FIG. 6 is a cross-sectional view of the device of FIG. 1 taken along section B-B of FIG. 3;

FIG. 7 is a perspective view of a pressure sensing unit of the device of FIG. 1;

FIG. 8 is a cross-sectional view of the sensing unit of FIG. 7 taken along section C of FIG. 7;

FIG. 9 is an isolated view of the sensing unit of FIG. 7 rotated 180 degrees;

FIG. 10 is a schematic view of a conduit assembly of the present invention including a conduit and a sensing device in the context of measuring mass flow of a fluid stream;

FIG. 11 is a different perspective view of the lower housing in the embodiment of FIG. 11;

FIG. 12 is one embodiment of a housing: 12a is a bottom view; 12b is a cross-sectional view taken along line A-A in 12 a;

FIG. 13 is a tubing assembly of the present invention

a) The complete perspective view of the device is shown,

b) there is no perspective view of the sensing device,

c) a perspective view without the sensing device and the first thermal shield,

d) a complete cross-sectional view perpendicular to the direction of flow through the first measurement location;

fig. 14 is a detailed view of a temperature sensor of the device of fig. 1.

Detailed Description

Fig. 10 schematically shows an inventive device 1 for determining the mass flow of a fluid flow F flowing in a pipe D. In particular, the fluid is air, exhaust gas, CNG/air or any mixture thereof flowing in an internal combustion engine.

In one embodiment, the conduit D is a venturi nozzle having a small installation length. The venturi nozzle has a first cross-section a1 followed by a second cross-section a2 in the fluid direction F. The second cross-section a2 is smaller than the first cross-section a 1.

The first measurement location L1 is located in the first cross-section a 1; the second measurement position L2 is located in the second cross section a 2. Due to the narrowing of the shape, a pressure difference is created between cross sections a1 and a2, which is a function of the fluid flow. The fluid velocity at the second measurement position L2 is increased compared to the fluid velocity at the first measurement position L1. Therefore, the static pressure p2 at the second measurement position L2 is smaller (bernoulli's law) than the static pressure p1 at the first measurement position L1. In particular, the measurement positions L1, L2 are located in the fluid F after passing through the compressor outlet.

The device 1 of the invention has a temperature sensor 5 for determining a first temperature T1 of the fluid at a first measurement location L1. The inventive device 1 has a sensing unit 4, the sensing unit 4 being adapted to determine a pressure difference dp between the first static pressure p1 and the second static pressure p2 or the first pressure p1 and the second pressure p 2. The mass flow rate m (strictly speaking, there is a point at the top as shown in fig. 10, but written herein as no point at the top) is a function according to the formula shown in fig. 10 and is calculated by the calculation unit 6. This principle of determining the mass flow rate of the fluid flow F is known in the art (i.e., the bernoulli equation).

Fig. 1-8 show a mass flow sensing device 1 of the present invention in different views.

The pressure sensing unit 4 is adapted to determine at least a pressure difference dp and a (absolute) pressure p2 or p 1. The sensing unit 4 is accommodated within the device case 2. The device case has an upper device case 2a and a lower device case 2 b. The upper device case 2a is independent from the lower device case 2 b. Within the device housing 2, the two

pressure chambers

11, 12 are separated from one another. The first pressure chamber 11 is in fluid communication with a first measurement location L1 and the second pressure chamber 12 is in fluid communication with a second measurement location L2. Thus, the same first pressure p1 is present in the first pressure chamber 11 as at the first measurement location L1, and the same second pressure p2 is present in the second pressure chamber 12 as at the second measurement location L2.

The device housing 2 has a first pressure opening 31, which first pressure opening 31 enables fluid to pass between the first measurement position L1 and the first pressure chamber 11. The device housing 2 has a second pressure opening 32, which second pressure opening 32 enables fluid to pass between the second measurement position L2 and the second pressure chamber 12. Suitable fluid conduits, not shown here (see the "connecting pipe 65" in fig. 13 below), can be installed between the measuring locations L1, L2 and the pressure openings 31, 32. The

seals

35, 36 serve to seal the pressure chamber at the interface with the device housing 2.

The temperature sensor 5 is located directly within the fluid flow F. The housing thus has a distance tube 23 bridging the distance from the sensing unit 4 to the fluid flow. As in this example, the distance tube 23 is formed in particular by the lower device housing 2 b. The distance tube 23 is used to hold the temperature sensor 5 in place within the flowing fluid. It also provides some protection against mechanical damage (i.e., drop testing, ice crushing, operator handling, etc.) by two protruding pins 34.

The details of the temperature sensor 5 are described later with reference to fig. 14.

The gaps between the pins 34 allow air flow at high flow rates through the bead of the temperature sensor 5. Furthermore, the inclined surface 33 at the lower surface of the distance tube 23 helps to deflect air towards the bead of the temperature sensor. Since a high local flow velocity is critical for a fast temperature signal response of the temperature sensor 5, both measures contribute to improving the mass flow sensing accuracy when the medium temperature changes rapidly. Such measures are generally required in the flow behind the compressor when it goes from a high load (>200 ℃) to an idling condition (close to ambient temperature). The heated part of the distance tube may affect the measurement due to heat conduction with the bead of the temperature sensor. It is therefore preferred to have a small contact surface, for example the region of the inclined surface 33 where there is a pin 34 and a cut-out of the tube.

The lower device housing 2b faces the fluid flow. In order to withstand high fluid temperatures, in particular at least 260 ℃, the lower housing is made of metal. Suitable metals may be selected from one of aluminum, steel, zinc or any alloy comprising the above metals. In particular, the metal comprises zinc or aluminium and a suitable alloy is additionally selected for the required corrosion resistance. In addition, an anti-corrosion protective coating or surface treatment may be used.

The spacer tube has a hollow interior with a small outer diameter and a small wall thickness to reduce heat transfer from the medium to the sensor housing area.

Since the thermal load acting on the upper device case 2a is smaller than that acting on the lower case, the upper device case 2a may be made of plastic.

The distance tube 23, the first and second pressure openings 31, 32 are formed by the lower device housing 2 b. The upper device housing 2a forms a connection portion 22, more specifically a plug receptacle for electrical connection of the device.

The terms "upper" and "lower" are arbitrary and are used only to define two portions from each other. Such terms do not require that the respective upper component be positioned above the respective lower component during manufacture or use. The terms "upper" and "lower" may be replaced by "first" and "second".

The pressure sensing unit 4 has a sensing unit housing 40. The sensing unit housing 40 has an upper unit housing 40a and a lower unit housing 40 b. The sensing unit housing 40, in particular the lower unit housing 40b, may be positioned on a substrate 26, which may be part of the device housing 2. Preferably, the unit 4 is mounted on a PCB board, which in particular serves as the base plate 26.

The sensing unit housing 40 forms two

pressure chambers

411, 412 within the unit housing. The first and

second pressure chambers

411, 412 of the unit housing are connected next to the respective first and

second pressure chambers

11, 12 of the sensing device 1 through the respective first and

second pressure inlets

401, 402. Thus, the first and

second pressure chambers

411, 412 of the sensing unit 4 constitute sub-chambers of the respective first and

second pressure chambers

11, 12, respectively. Thus, the pressure p1 in the first pressure chamber 411 of the sensing unit 4 is the same as the remaining pressure in the first pressure chamber 11 of the device 1; the second pressure p2 in the second pressure chamber 412 of the sensing unit 4 is the same as the remaining pressure in the second pressure chamber 12 of the device 1.

Both

pressure inlets

401, 402 are tubular and protrude upwards from the sensing cell housing 40. The shape of the

pressure inlets

401 and 402 may be chosen differently. The tubular and oval shapes may be beneficial for component testing in sensor element manufacturing, i.e. temporary connection with O-rings for pressure testing. More inlets may be installed than just the two

inlets

411 and 412. The parallel third inlet may facilitate the addition of a protective agent (i.e. a gel) into one of the sensing

cell pressure chambers

411, 412, in particular onto the

sensors

41 and 42. One inlet may be used for injection of the formulation through the syringe and the other inlet may be used as a discharge orifice.

The housing, particularly the upper unit housing 40a, has a dividing wall 425. The dividing wall divides the first and

second pressure chambers

411, 412 within the sensing cell housing 40. There is no fluid exchange between the

pressure chambers

411, 412 and 11, 12 within the device.

A second pressure sensor 42 is provided in the second pressure chamber 412 of the sensing unit 4. The second pressure sensor 42 measures the absolute value of the second pressure p 2. The first pressure sensor 41 is located at the junction of the first pressure chamber 411 and the second pressure chamber 412. The first pressure sensor 41 measures a pressure difference dp between the first and second pressures p1, p 2. Accordingly, the first pressure port 41a of the differential pressure sensor 41 is in contact with the first pressure chamber 411, and the second pressure port 41b of the differential pressure sensor 41 is in contact with the second pressure chamber 412.

Alternatively, the pressure difference dp may be calculated from two separate absolute pressure sensors. In this case, the first pressure sensor and the second pressure sensor are located in two different pressure chambers. However, it is preferred to use at least one differential pressure sensor for determining the pressure difference, since commercially available differential pressure sensors are more accurate than equally priced absolute pressure sensors.

The first pressure sensor 41 is located in one of the

pressure chambers

411, 412 of the sensing unit 4, preferably in the second pressure chamber 412. A pressure channel 404 is provided to connect the first pressure chamber 411 and the second pressure chamber 412. Of course, the end of the pressure channel 404 facing the second pressure chamber 412 is completely sealed, so that only the second port 41a contacts the first pressure chamber 411.

Obviously, alternatively, the first pressure sensor 41 may be located within the first pressure chamber 411 (not shown in the figures). Then, the end of the pressure channel 404 facing the first pressure chamber 411 is completely sealed, so that only the second port 41b contacts the second pressure chamber 412 and the first port 41a contacts the first pressure chamber 411.

In one of the pressure chambers, in particular in one of the

pressure chambers

411, 412 of the sensing unit 4, a second pressure sensor 42 is additionally provided. The second pressure sensor 42 is adapted to determine the absolute pressure present in the pressure chamber in which it is located. Here, the second pressure sensor 42 is located within the second pressure chamber 412 and is therefore adapted to determine the second pressure p 2. In particular, the second pressure sensor 42 is a component of the pressure sensing unit 4. Alternatively, the second pressure sensor 42 may be located in the first pressure chamber 411 to measure the first pressure p 1.

The lower unit case 40b includes an upper plate 403a and a lower plate 403 b. The upper plate 403a is sandwiched between the

pressure chambers

411, 412 and the lower plate 403 b. The first pressure sensor 41 is fixed to the upper base plate 403 a. The upper plate 403a is sandwiched between the lower plate 403b and the upper unit case 40 a.

A pressure channel 404 is formed within the lower unit housing 40b, which pressure channel 404 constitutes an extension of one of the

pressure chambers

412 and 411 that does not accommodate one of the first sensors 41, which extension leads to a respective pressure port of the first sensor 41 located in the other of 411 and 412.

The connecting channel has a connecting slot 404b in one or both of the

bottom plates

403a, 403b, which bridges the distance between the second pressure chamber 412 and the first pressure chamber 411. In fig. 8, a coupling groove 404b is formed in the lower base plate 403 b. Alternatively, the coupling groove 404b may be formed in the upper bottom plate, as shown by a dotted line 404b' in fig. 8.

It will be appreciated that the bottom plate 403b may be bonded to a substrate 26, preferably a PCB. In this case, the substrate 26 is used as a sealing plate in the case where the channel 404 is formed in the substrate 26, or the channel 404 is formed in the bottom plate 403a or the channel is formed in the combination of the substrate 26 and the bottom plate 403 a. An advantageous arrangement is to use two PCB-shaped panels for the

base panels

403a, 403b or, alternatively, two PCB-shaped panels for the base panel 26 and the base panel 403 b. Thus, electrical traces matching the upper and lower portions can be formed around the channel so that, if welded together, the channel is sealed by welding. The soldering process may be part of the PCB 26 assembly and soldering process.

In the present embodiment, the first hole 404a through the upper base plate 403a constitutes a connection portion between the second pressure chamber 412 and the connection groove 404 b. The second hole 404c passing through the upper base plate 403a constitutes a connection portion between the first pressure chamber 411 and the connection groove 404 b. In particular, the first sensor 41 seals the second pressure chamber 412 against the first pressure chamber 411 to prevent fluid communication between the two

pressure chambers

411, 412. Here the pressure port, in particular the first pressure port 41a, covers the first hole 404a to be correlated with the pressure of the further pressure chamber 411.

In other words: the first pressure chamber 411 and the pressure channel 404 of the sensing unit 4 extend the first pressure chamber 11 of the device to the first pressure port 41 a. The second pressure chamber 412 of the sensing unit 4 extends the second pressure chamber 12 of the device to the second pressure port 41 b.

In an alternative embodiment not shown, the first sensor 41 is located in the first pressure chamber 411: the second pressure chamber 412 and the pressure channel 404 of the sensing unit 4 extend the second pressure chamber 12 of the device to the second pressure port 41 b; the first pressure chamber 411 of the sensing unit 4 extends the first pressure chamber 11 of the device to the first pressure port 41 a.

The device housing 2 encloses an inner space 13, which is divided into a first pressure chamber 11 and a second pressure chamber 12. Initially, the inner space 13 is not divided into two

pressure chambers

11, 12. In order to divide the inner space 13 into the first and

second pressure chambers

11, 12, the bottom area in the inner space 13 opposite the pressure openings 31, 32 is filled with a sealing compound 24 (fig. 5, 6). The inner space 13 is not completely filled with the sealing compound 24. The part of the inner space 13 above the sealing compound 24 is kept open to both

pressure chambers

11, 12. At the same time, the first pressure opening 31 and the second pressure opening 32 are not in contact with the sealing compound 24.

In particular, the sealing compound 24 is a silicone and/or fluoro-gum based compound.

A portion of the sensing unit 4 is cast within the sealing compound 24, but the first and

second pressure inlets

401, 402 of the sensing unit housing 40 extend out of the sealing compound 24. Between the first pressure inlet 401 and the second pressure inlet 402 a groove 405 is provided, which separates the two

pressure inlets

401, 402 from each other. The recess is also partially filled with a sealing compound 24.

As is apparent from a combination of fig. 6 and 8, the first pressure inlet 401 is arranged offset from the first pressure opening 31, in particular, from each of the first pressure openings 31i, 31 o. This means that the first pressure inlet 401 is not aligned with the first opening 31, in particular, with each of the inner first opening 31i and the outer first opening 31 o. Additionally, the second pressure inlet 402 is disposed offset from the second pressure opening 32. This means that the second pressure inlet 402 is not aligned with the second opening 32. This causes the fluid flowing through the openings 31, 32 to bend around before approaching the

pressure inlets

401, 402. Any soot or condensate may be removed from the fluid before it reaches the

respective pressure inlet

401, 404.

The lower device housing 2b includes a pressure chamber partition 25, the pressure chamber partition 25 extending into the recess 405 and thus into the sealing compound 24 located within the recess. The pressure chamber partition 25 extends horizontally in the entire inner space 13, so that the pressure chamber partition 25 partitions the space above the sealing compound 24 into the first pressure chamber 11 and the second pressure chamber 12.

The lower device housing 2b comprises a circumferential edge 27 surrounding the first and

second pressure chambers

11, 12. The edge 27 extends into the sealing compound 24. The

pressure chambers

11, 12 are thus sealed from the environment.

As is apparent from the figures, the sensing device 1 may comprise one or two different independent first openings, i.e. an outer first opening 31o and/or an inner first opening 31 i.

The outer first opening 31o is adapted to let fluid enter the first pressure chamber 11 from a further outer region of the first measuring position L1, and the inner first opening 31i is adapted to let fluid enter the first pressure chamber 11 from an inner region of the first measuring position L1. In principle, both embodiments are suitable for supporting the determination of the mass flow m.

When there is no difference in the present specification or claims with respect to the internal/external pressure openings 31i/31o and the internal/external pressures p1i, p1o, any one of these openings/pressures may be indicated.

The fluid velocity of the inner region may be higher than the fluid velocity of the outer region, and thus the inner first pressure p1i may be different from the outer first pressure p1 o. This difference can be mathematically considered when evaluating the measurement values.

In one embodiment, the first inner and outer pressure openings 31i, 31o are both provided in the same device. Due to the pressure difference (p1i-p1o) between the outer first pressure opening 31o and the inner first pressure opening 31i, a fluid flow through the first pressure chamber 11 is generated between the two first pressure openings 31i, 31 o. This fluid flow may have a cleaning effect of removing any dirt, in particular soot particles and condensates, which may be deposited at the openings or in the pressure ducts and which may be washed away by the fluid flow generated between the two first openings 31o, 31 i.

Fig. 9 shows a process of protecting the

pressure sensors

41, 42 within the pressure sensing unit 4 from chemical attack, smoke and particles, condensation and the like. Thus, the sensing unit housing 40 is located toward the position where the sensor is located at the downward position. Previously, the sensors were fixed (i.e., adhesively secured, welded, etc.) and electrically connected (i.e., glued, welded, etc.) to the sensing cell housing 40. The protective agent 44 is then fed into the interior of the sensing unit housing 40, in particular, through

pressure inlets

401, 402 leading to

pressure chambers

411, 412 of the sensing unit housing 40, in which the

sensors

41, 42 are provided. A suitable feeding means 46, for example a pipette, is used. The protective agent 44 seals in particular the junction 45 of the upper unit housing 40a and the lower unit housing 40 b.

Fig. 9a shows an embodiment in which two

sensors

41, 42 to be fixed are located in one pressure chamber 412 (as shown in fig. 8). In particular, both sensors require only one step of formulation dispensing.

Fig. 9b shows an embodiment in which the two

sensors

41, 42 are located in different pressure chambers. This can be fully integrated with all the details described in figure 8 and in the other figures, without protecting the sensor. In particular, the two

sensors

41, 42 may be absolute pressure sensors, which together are adapted to determine the pressure difference dp.

Fig. 11 and 12 show details of an alternative embodiment. A liquid level check chamber 14 is provided in the inner space 13 of the device housing. One, two or more inspection openings 414 are included in one of the device housing parts, in particular in the part opposite the sealing compound 24, in particular in the lower device housing 2 b. Each inspection opening 414 connects one of the respective fluid level inspection chambers 14 to the environment. The inspection chamber partition 254 extends into the sealing compound 24 that separates the liquid level inspection chamber from the first pressure chamber 11 and the second pressure chamber 12. As shown in fig. 11 and 12, the inspection chamber partition 254 may be part of the pressure chamber partition 25.

As long as the sealing compound 24 does not cure, the sealing compound 24 can flow between the

pressure chambers

11, 12 and the level checking chamber 14, thereby forming a uniform level within the

chambers

11, 12, 14. At any time after the sealing compound 24 is cured, the liquid level FL within the inspection chamber 14 may be determined by, inter alia, optical inspection, tactile inspection, or any form of distance measurement. The fluid level FL in the

pressure chambers

11, 12 can be inferred by the state of the fluid level FL in the fluid level check chamber 14. If the fluid level FL in the inspection chamber 14 is low, the fluid level FL in the pressure chambers may also be low, resulting in the pressure chambers not being separated by the sealing compound 24. If the level FL in the examination chamber 14 is high, the level FL in the

pressure chambers

11 and 12 may also be high, resulting in the

pressure inlets

401, 402 of the sensing cell housing 40 being sealed by the sealing compound 24.

In the exemplary embodiment shown, there are two level check chambers 14 that are separate and remote from each other. The design of each level check chamber 14 is as described above. If the fluid level FL in one of the inspection chambers 14 is different from the fluid level in the other inspection chamber 14, it can be detected that the fluid level FL of the sealing compound 24 is angled relative to the housing. This may occur while the housing is held in a tilted position during curing of the sealing compound.

Alternatively, the pressure openings 31, 32 may be used as inspection openings for determining the liquid level. Since the pressure openings 31, 32 are arranged offset from the pressure inlets, there is no risk of damaging the pressure sensor unit during a tactile check.

In particular, the device housing 2 and/or the lower device housing 2b are made of an opaque material, so that the level of sealing compound cannot be seen through the housing material.

Fig. 13a shows a conduit assembly 100 of the present invention comprising a conduit D and a flow sensing device 1 as described above, the flow sensing device 1 being attached to the conduit. The device 1 may be attached to the pipe by conventional fastening means, such as a threaded connection at the fastening portion 21. In this exemplary version, the duct D has, internally, as already described with reference to fig. 10, a profile in the shape of a venturi nozzle.

The sensing device 1 is kept at a distance from the pipe D by at least one spacer 63. At least one spacer 63 is provided between the sensing device 1 and the pipe D. Thus, the assembly 100 allows for various directions of airflow AF between the sensing device 1 and the conduit D.

At least one connecting tube 65 is provided between the catheter D and the sensing device 1. Each connecting tube 65 forms a fluid connection between the

pressure chamber

11, 12 and one of the pressure openings 31, 32 (see in particular fig. 5, 6) on the one hand and one of the measuring positions L1, L2 (see fig. 10) within the pipe on the other hand. The surface of the connecting tube 65 is fitted with seals 35 and 36 (here referred to as O-rings), which seals 35 and 36 are axially compressed when the sensing device is secured by screws. The

seals

35, 36 may act as thermal resistances to reduce heat transfer to the lower device housing 2 b.

As shown in fig. 13d, a spacer tube 23 can be inserted into one of the connecting tubes 65.

When we refer to the assembly 100 we refer to the sensing device 1 being kept at a distance from the pipe D, but it should be noted that the distance tube 23 (see fig. 5 and 6) constitutes an exception, which is not under consideration. The distance tube 23 is an optional element for directly bridging said distance between the sensing device 1 and the pipe D.

In the embodiment shown in fig. 13a and 13b, there is a mounting plate 61 attached to the pipe D, in particular, the mounting plate 61 is formed integrally with the pipe D. The sensing device 1 is attached to the mounting plate 61.

In the embodiment shown in fig. 13a and 13b, the pipe assembly 100 comprises a first thermal shield 61 located between the pipe and the sensing device 1. The thermal insulation is adapted to prevent or at least reduce thermal radiation emanating from the duct D and reaching the device.

In the embodiment shown in fig. 13a and 13b, the pipe assembly 100 comprises a second thermal shield 62, which second thermal shield 62 is located at the side of the sensing device 1 with respect to the pipe D, in particular, in a direction that is and/or is perpendicular to, but not parallel to, the fluid F. The second thermal shield is adapted to prevent or at least reduce thermal radiation emitted by other components in the vicinity of the sensing device and reaching the device.

In the embodiment of fig. 13a, in particular, the first thermal insulation element optionally constitutes a mounting plate. In another embodiment, the insulation can be made independent of the duct.

To further reduce heat conduction, insulation or additional parts between the pipe and the sensing device may be used as additional thermal resistance. This thermal resistance may also be a thermal barrier coating or any spacer material (i.e. rubber, silicone sheet) preferably having low electrical conductivity. Increasing the height is beneficial for reducing heat transfer. A coating may be applied to the distance tube 23. The coating should provide a lower electrical conductivity than the material of the distance tube 23. The coating can also be applied partially to completely on the lower device housing 2 b.

Fig. 13c shows an embodiment without insulation (sensing device 1 not shown). The arrangement of the

spacers

63 and 65 is the same as in the embodiment of fig. 13a and 13 b.

Fig. 10 and 13 illustrate an exemplary direction of fluid F through the conduit D. The direction of the fluid F may also be the opposite direction.

The pipe assembly 100 is adapted to be measured at fluid temperatures exceeding the maximum temperature of the material, in particular the electronic components used in the sensing device 1. Heat transfer occurs between the sensing device, the fluid, the measurement device to which the sensing device is attached, and the environment of the sensing device. If the fluid F or the conduit (i.e., the venturi nozzle tube) is too hot, a significant amount of heat may be transferred to the sensing device. To counteract the heat, cooling is required. At cold temperature levels, heat transfer can be used to heat the sensing device if condensation or freezing occurs. This can be achieved in particular by the following described ways, which can be used individually or in combination:

heat is transferred from the fluid F towards the distance tube 23 by convection and conduction. This effect has a great effect on the overall heat transfer. To reduce this effect, it is beneficial to use a material that is less thermally conductive. Therefore, for the lower device case 2b, it is preferable to use a zinc material instead of aluminum and steel. By using spacers with small diameters and small wall thicknesses (with a large inner bore diameter of 31 i), the cross-sectional area of the spacer tube 23 can be reduced, thereby reducing heat transfer.

The temperature of the flow sensing device 1 can be actively regulated by the flow of liquid (i.e. cooling water) in the area between the pipe and the sensing device 1. However, this adds more parts and cost to achieve cooling. Air convection is therefore recommended. If the outside temperature of the fluid pipe is high compared to the surrounding air, a buoyancy driven flow is generated, resulting in a natural convection flow. The flow cooling spacer 63 and the connecting pipe 65, and any other exposed surfaces of the lower device housing 2b and the upper device housing 2 a.

To improve the natural convection effect, it is suggested to rotate the sensing device 1 as shown in fig. 13 d. Preferably, the sensing means is angled relative to the horizontal plane H at 0 < α < 180 degrees, where α is about 45 degrees +/-20 degrees is most preferred. If the rotation is defined and applied counterclockwise, the effect is the same.

In case of a forced air flow, i.e. generated by the movement of the fan or the engine/vehicle, any rotation angle alpha may be chosen.

To increase the surface for heat dissipation, the fluid tube may be provided with a mounting plate 61 (fig. 13a, b), which mounting plate 61 also acts as a thermal insulation. The form, size and thickness may be selected to have a beneficial shape for manufacturing and to enhance the cooling effect. The surface of the mounting plate 61 may be roughened or configured in a manner to increase the effective cooling area.

In particular, when the forced air flow reaches the sensing device 1, it may be heated by the thermal component. For internal combustion engines, these hot components may be exhaust pipes, turbochargers, and exhaust aftertreatment system components. In order to reduce the heat transfer by convection and/or radiation, it is proposed here to add a second thermal insulation 62. The second thermal shield 62 may be part of the duct assembly 100, and in particular, may be integrally formed with the duct D, as shown in fig. 13a, 13b, or may be an additional mounting part of the sensing device 1. Furthermore, the material, surface, colour (preferably non-black, non-grey), shape and orientation may be in a beneficial way. In order to use the sensing means for measuring the air flow after the compressor, an insulation towards the compressor is proposed.

Heat is transferred from the duct D to the lower device case 2b by conduction. To reduce heat transfer, the contact area is reduced. The sensing device 1 is attached to the top of the spacer 61, which is formed with a reduced area flange interface having two mounting ports for mounting screws and spacers 63.

A beneficial use of the heat transfer to the lower device housing 2b is to avoid or eliminate condensation within the sensing device 1, in particular in the fluid region within the interior space 13 and the pressure sensing unit 4. The lower device housing 2b can heat the area. To improve this, the surface of the lower device housing 2b is in contact with the inner space 13, in particular with the edge 27, the barrier 28, the pressure chamber partition 25 and the upper part of the distance tube 23 can serve as heating surfaces.

The fluid F may comprise particles, liquids or condensed matter. It is not desirable that they enter the sensing device 1, in particular the sensing unit 4. In particular the inner area of the sensing unit 4 should be protected. Due to the pressure variations, a flow into or out of the pressure openings 31 and 32 may be caused. The barrier 28 blocks fluid entering through 32 and flowing to 412. The fluid must make a sharp turn until it finally enters the internal pressure chamber 412 through the corresponding pressure inlet 402. The particles have momentum due to their weight which can be used to deflect them from the direction of flow entering the pressure chamber 412 within the sensing cell 4 through the pressure inlet 402. In this case, the sealing compound 24 acts as an impact wall.

Condensate, particles and fluid (e.g. oil) should remain mainly in the area before the barrier, in particular, to the left of the barrier 28 as shown in fig. 5. Condensate and fluid should remain at the bottom of 13. Likewise, fluid passing through either of the pressure inlet openings 31, 32, in particular the first pressure opening 31, must also make sharp turns until entering the respective pressure chamber within the sensing unit 4 through the respective pressure port.

To assist in draining fluid entering the interior space 13 and the

pressure chambers

411 and 412 within the sensing unit 4, a flow of air from the interior space 13, the

pressure chambers

411 and 412 towards the fluid F is used. This air flow is generated when the pressure inside the

pressure chambers

411 and 412 is temporarily higher than the pressures p1 and p2 in the fluid F at the measurement locations connected to the respective pressure chambers. For optimal use, it is beneficial to direct the condensate to the area of openings 31 and 32. The size, surface and shape of these openings are designed to reduce the effect of surface tension of the removed liquid. A sharp edge at the opening may act as a stop element. In the proposed device, sharp edges are avoided and a round shape is used to support the funnel-type function.

Fig. 14 shows the temperature sensor 5 in more detail. The temperature sensor 5 has a sensing head 51, the sensing head 51 being located in the fluid F for determining the temperature within the fluid flow.

The temperature sensor 5 has two terminals 55. Each terminal 55 is remote from the sensing head 51, in particular each terminal 55 is located within the device housing 2. The terminal 55 has an electrical interface 55p for electrically contacting the temperature sensor 5. Each terminal 55 may have a contact pin 55p as an electrical interface. The terminals are made of a conductive material.

In particular, the terminals may be attached to a substrate 26 (see, e.g., fig. 9). The substrate may be a circuit board in electrical contact with the temperature sensor 5.

Temperature sensor 5 includes at least one electrical cable 53 to provide an electrical connection between sensing head 51 and terminal 55. The at least one cable 53 comprises at least two conductors 53c made of electrically conductive material. An insulating sleeve 53i is provided at least partially around the conductors 53c to insulate the conductors 53c, in particular to insulate the conductors 53c from each other and from the environment.

In this particular embodiment, two separate cables 53 are provided, each having a conductor 53c and an insulating sheath 53 i. In another embodiment of the invention (not shown), one cable 53 comprises two conductors 53c, the two conductors 53c being insulated from each other by an insulating sheath 53 i.

The cable 53 has a non-insulated portion 53u at the first end 53a and/or the second end 53 b. This means that there is no insulating sleeve 53i surrounding the conductor 53 c. At the uninsulated portion 53u, a conductor 53c is attached to the sensing head or terminal 55.

In particular, at the non-insulated portion 53u at the first end 53a, the conductor 53c is attached to the sense head 51 by a brazed connection 53 s. Specifically, at the non-insulated portion 53u at the second end 53b, the conductor 53c is attached to the terminal 55 through the connecting portion 53 s.

At the first end 53a, the connecting portion 53s and the non-insulating portion 53u are completely surrounded by the head coating 52. In particular, the sensing head may also be completely or at least partially surrounded by the head coating 52. The head coating is made of an insulating material, and therefore, it establishes insulation between the two brazed connection portions 53s and the non-insulated portion 53 u. At the first end 53a, the connection 53s may be a pressure-welded connection or a fusion-welded connection. In particular, the connection 53s at the first end 53a is adapted to withstand a temperature of at least 200 ℃.

At the second end 53b, the connecting portion 53s and the non-insulating portion 53u are completely surrounded by the sealing compound 24. In particular, the sealing compound 24 is identical to the material 24 filled in the pressure chamber, which has been described in particular with reference to fig. 5 and 6. At the second end 53b, the connection 53s may be a pressure-welded connection or a brazed connection. In particular, the connection 53s at the second end 53b may be adapted to withstand only temperatures of less than 200 ℃.

In an alternative embodiment, the terminals 55 may be formed by conductors that directly contact the substrate/PCB board 26. Here, the non-insulating part may also be cast into the material as described above.

In embodiments where the sealing compound 24 is made of an insulating material, the sealing compound 24 establishes insulation between the two solder connections 53s and the non-insulating portion 53 u.

In particular, the cable 53 has a length of at least 20 mm. In particular, the cable is at least partially housed inside the distance tube 23 (figures 5 and 6).

List of reference numerals:

1-a flow sensing device;

2-a device housing;

4-a pressure sensing unit;

5-a temperature sensor;

6-a calculation unit;

11-a first pressure chamber of the sensing device;

12-a second pressure chamber of the sensing device;

13-the inner space of the device housing;

14-inspection chamber level;

2 a-upper device housing;

2 b-lower device housing;

21-a fixed moiety;

22-a linking moiety;

23-a distance tube;

24-a sealing compound;

25-pressure chamber divider;

254-inspection chamber partition;

26-a substrate;

27-a circumferential edge;

28-a barrier;

29-a tubular barrier;

31 o-outer first pressure opening;

31i — an inner first pressure opening;

32-a second pressure opening;

33-inclined surface;

34-a pin;

35-first seal (O-ring);

36-second seal (O-ring);

40-a sensing unit housing;

40 a-an upper unit housing;

40 b-lower unit housing;

401 — a first pressure inlet;

402-a second pressure inlet;

403 a-upper sole plate;

403 b-lower floor;

404-pressure channel through the base plate;

404 a-a first hole through the upper plate;

404 b-a connecting slot in the lower base plate;

404 c-a second hole through the lower plate;

405 — a groove between the first pressure inlet and the second pressure inlet;

41-first sensor/differential pressure sensor;

41 a-a first pressure port of a differential pressure sensor;

41 b-a second pressure port of the differential pressure sensor;

414-liquid level check opening;

42-second sensor/absolute pressure sensor;

44-a binder;

45-interface;

46-adhesive supply means;

425-dividing walls;

51-a sensing head;

52-head coating;

53-a cable;

53 a-cable first end;

53 b-cable second end;

53 c-conductor;

53 i-insulating sleeve;

53 s-soldering of the cable to the terminal 55;

53 u-non-insulated portion;

a 55-terminal;

55 p-terminal interface (contact pin);

55 s-terminal to substrate 26;

61-mounting plate/first insulation;

62-a second thermal shield;

63-a spacer;

65-connecting pipe;

100-a pipe assembly;

p1o — external first pressure;

p1i — internal first pressure;

p 2-second pressure;

t1-fluid temperature;

m-mass flow rate;

f-fluid flow;

a D-pipe;

l1 — first measurement position;

l2 — second measurement position;

a1 — first cross section;

a 2-second cross section/stenosis;

level of FL-sealing compound;

g-direction of gravity.

Claims

1. Flow sensing device (1), characterized in that it comprises:

a) device case (2)

Wherein a first pressure chamber (11) and a spaced apart second pressure chamber (12) are formed in the device housing (2);

b) a sensing unit (4) located in an inner space (13) of the device housing (2), the sensing unit (4) comprising at least one pressure sensor (41);

the flow sensing device (1), in particular the sensing unit (4), is adapted to determine at least a pressure difference (dP) between a first pressure (p1) in the first pressure chamber (11) and a second pressure (p2) in the second pressure chamber (12).

2. The device (1) according to claim 1,

the device housing (2) has a first pressure opening (31) for introducing a first pressure (p1) into the first pressure chamber (11) and a second pressure opening (32) for introducing a second pressure (p2) into the second pressure chamber (12).

3. The device (1) according to any one of the preceding claims,

the sensing unit (4) has a first pressure inlet (401) and a second pressure inlet (402);

the first pressure inlet (401) is located in the first pressure chamber (11), in particular in fluid communication with the first pressure chamber (11);

the second pressure inlet (402) is located in the second pressure chamber (12), in particular in fluid communication with the second pressure chamber (12);

in particular, the first pressure inlet (401) connects a first pressure chamber (411) of the sensing unit (4) with the first pressure chamber (11) of the device (1);

and/or

In particular, the second pressure inlet (402) connects a second pressure chamber (412) of the sensing unit (4) with the second pressure chamber (12) of the device (1).

4. The device (1) according to any one of the preceding claims,

the sensing unit (4) is at least partially cast in a cured sealing compound (24); wherein the first pressure inlet (401) and the second pressure inlet (402) protrude out of the sealing compound (24).

5. The device (1) according to any one of the preceding claims,

the device housing (2) has a pressure chamber partition (25) which projects into the sealing compound (24) and thus divides the interior space (13) of the device housing (2) into the first pressure chamber (11) and the second pressure chamber (12).

6. The device (1) according to any one of claims 4 or 5,

at least one, in particular two, level checking means (14, 254) in particular provide an indication of the level of the sealing compound (24) in the first pressure chamber (11) and/or the second pressure chamber (12).

7. The device (1) according to any one of claims 4 to 6,

the liquid level check device (14, 254) comprises:

a liquid level check chamber (14), the liquid level check chamber (14) being at least partially filled with the sealing compound (24);

an inspection opening (414), said inspection opening (414) connecting said level inspection chamber (14) with the environment, in particular being adapted to allow the liquid level (FL) within said level inspection chamber (14) to be reached from the environment through measuring means from the outside;

in particular, the liquid level checking device (14, 254) comprises a liquid level checking chamber partition (254), the liquid level checking chamber partition (254) protruding into the sealing compound (24) and separating the liquid level checking chamber (14) from any one of the first pressure chamber (11) and/or the second pressure chamber (12).

8. The device (1) according to any one of the preceding claims,

comprising a pressure sensor arrangement (41, 42), in particular having two pressure sensors (41, 42), the pressure sensor arrangement (41, 42) being adapted to determine at least one absolute pressure (p1, p2) in at least one of the pressure chambers (11, 12) and a pressure difference (dp) between the first pressure (p1) present in the first pressure chamber (11) and the second pressure (p2) present in the second pressure chamber (12);

in particular, the pressure sensor arrangement comprises at least a pressure sensor (41) as a differential pressure sensor, in particular, the pressure sensor (41) is adapted to determine a pressure difference without determining an absolute pressure.

9. The device (1) according to any one of the preceding claims,

at least a part (2b) of the device housing (2), in particular a lower device housing (2b), in particular a part facing and/or located between the sensing unit and the fluid flow (F), is made of metal;

in particular, the portion (2b) has a heat resistance of at least 260 ℃.

10. The device (1) according to any one of the preceding claims,

the sensing unit (4) comprises a lower unit housing (40b),

the lower unit case (40b) is formed with a connecting passage (404) between the first pressure chamber (11) and the second pressure chamber (12);

in particular, the lower unit housing (40b) comprises an upper base plate (403a) and a lower base plate (403b), in particular the upper base plate (403a) and the lower base plate (403b) abut against each other, wherein the upper base plate (403a) faces in the direction of the pressure chambers (411, 412).

11. The device (1) according to any one of the preceding claims,

the connection channel (404) comprises:

a connecting slot (404b) in a surface of one of the two bottom plates (403b) facing the other bottom plate (403 a);

a first aperture (404a) connected with the first pressure chamber (411), in particular the first pressure chamber (411) within the sensing unit (4), through the connection slot (404 b);

a second bore (404c) connected with the second pressure chamber (412), in particular the second pressure chamber (412) within the sensing unit (4), through the connection slot (404 b).

12. The device (1) according to any one of the preceding claims,

the first sensor (41) is in particular a differential pressure sensor;

the first sensor (41) comprises a first pressure port (41a) and a second pressure port (41b) and is adapted to determine a pressure difference existing between the first pressure port (41a) and the second pressure port (41 b).

13. The device (1) according to any one of the preceding claims,

the first pressure port (41a) is in fluid communication with the first pressure chamber (11), and the second pressure port (41b) is in fluid communication with the second pressure chamber (12).

14. The device (1) according to any one of the preceding claims,

the first pressure sensor (41) is located in one of the pressure chambers (11, 12), in particular within the first pressure chamber (11) or the second pressure chamber (12);

in particular, each of said pressure ports (41a, 41b), in particular said first pressure port (41a) or second pressure port (41b), is also located in one of said pressure chambers (11, 12);

the first pressure sensor (41) is connected to another one of the pressure chambers (12, 11) by a pressure channel (404), in particular the respective other pressure port (41b, 41a), in particular the second pressure port (41b) or the first pressure port (41a), is in contact with the connection channel (404).

15. The device (1) according to any one of the preceding claims,

in order to protect and/or fix at least one pressure sensor (41, 42) within each pressure chamber (11, 12) and pressure chamber (411, 412), which are partially filled with a preparation, in particular a protective agent and/or an adhesive (44), in particular within the pressure chamber (411, 412) within a sensing unit housing (40) of the sensing unit (4);

in particular, the agent (44) also seals an interface (45) between two parts (40a, 40b) of the sensing unit housing (40).

16. The device (1) according to any one of the preceding claims,

also comprises a temperature sensor (5),

the fluid sensing device (1), in particular the temperature sensor (5), is adapted to determine a temperature (T1) of a fluid, in particular a fluid at a first measurement position (L1);

in particular, the temperature sensor (5) comprises a sensing head (51) located in the fluid (F) and a terminal (55) for electrical contact with the temperature sensor (5).

17. Device (1) according to any one of the preceding claims, characterized in that

The sensing head (51) and the terminal (55) are electrically connected to each other by at least one cable (53), the at least one cable (53) having at least one conductor (53 c);

wherein the cable (53) comprises an insulating sheath (53i), wherein the insulating sheath (53i) locally insulates the conductor (53 c);

wherein the cable (53) comprises, at cable ends (53a, 53b), uninsulated portions (53u) of the insulating sheath (53i) that do not insulate the conductor (53 c);

wherein the uninsulated portion (53u) is completely cast in a compound (52, 24), wherein the compound at least partially surrounds or completely surrounds the sense head (51) or the terminal (55).

18. The device (1) according to any one of the preceding claims,

the two pressure inlets (401, 402) of the pressure sensing unit are arranged offset from the respective pressure opening (31, 32).

19. A conduit assembly (100) with a device (1) according to any one of the preceding claims, further comprising:

a conduit (D) through which the fluid flow (F) is directed,

wherein the first pressure chamber (11), in particular the first pressure opening (31), is in fluid communication with a first measurement location (L1) within the fluid flow (F),

wherein the second pressure chamber (12), in particular the second pressure opening (32), is in fluid communication with a second measurement location (L2) within the fluid flow (F).

20. The conduit assembly (100) of claim 19,

wherein the conduit (D) comprises a Venturi nozzle having a narrowed portion (A2);

wherein the pressure difference to be determined is caused by the passage of fluid through the constriction (A2),

and/or

Wherein the first measurement position (L1) is located in a region of the duct (D) having a first cross section (A1);

wherein the second measurement position (L2) is located in a region of the duct (D) having a second cross section (A2);

wherein the second cross-section (A2) is smaller than the first cross-section (A1).

21. The conduit assembly (100) of the preceding claim,

wherein the sensing device (1) is connected to the conduit (D) by at least one spacer (63); in particular, wherein,

the spacer (63) is formed integrally with the pipe (D), and/or

The spacer (63) is configured such that an Air Flow (AF) can exist between the sensing device (1) and the conduit (D).

22. The piping component (100) of any preceding claim,

wherein a thermal insulation (61) is mounted between the sensing device (1) and the duct (D), in particular the thermal insulation (61) is positioned parallel to the direction of the fluid in the duct (D).