Sensor arrangement for determining at least one parameter of a fluid medium flowing through a channel structure

Abstract

Sensor arrangement (10) for determining at least one parameter of a fluid medium flowing through a channel structure (14), in particular an intake air mass flow of an internal combustion engine, wherein the sensor arrangement (10) has a sensor housing (12), in particular a plug-in sensor introduced or insertable into a flow tube, wherein the sensor housing (12) has the channel structure (14), wherein the sensor housing (12) has a housing body (16) and a cover (18), wherein the channel structure (14) has a main channel (24) and a measuring channel (34), wherein at least one sensor chip for determining the parameter of the fluid medium is arranged in the measuring channel (34), wherein the sensor housing (12) has an inlet (20) into the channel structure (14), which faces opposite a main flow direction (22) of the fluid medium, at least one first main channel outlet (26) from the main channel (24) and at least one measuring channel outlet (38) from the measuring channel (34),wherein the channel structure (14) is formed in the cover, characterized in that the sensor housing (12) has a second main channel outlet (28) from the main channel (24), wherein the first main channel outlet (26) and the second main channel outlet (28) are formed in the cover (18) and on opposite sides (30, 32) of the cover (18), wherein the main channel (24) has a tapered section (52) formed upstream of the first main channel outlet (26) and the second main channel outlet (28), wherein the first main channel outlet (26) is longer than the second main channel outlet (28), wherein the second main channel outlet (28) is straight, and the first main channel outlet (26) is delimited by curved channel walls (54).

Description

State of the art

[0001] Numerous methods and devices for determining at least one flow property of fluid media, i.e., liquids and / or gases, are known from the prior art. The flow properties as a possible parameter can be any physical and / or chemical, measurable properties that qualify or quantify a flow of the fluid medium. In particular, this can be a flow velocity and / or a mass flow and / or a volume flow.

[0002] The invention is described below in particular with reference to so-called hot-film air mass meters, as known, for example, from Konrad Reif (ed.): Sensors in Motor Vehicles, 1st edition 2010, pages 146-148. Such hot-film air mass meters are generally based on a sensor chip, in particular a silicon sensor chip, for example with a sensor membrane as the measuring surface or sensor area over which the flowing fluid medium can flow. The sensor chip generally comprises at least one heating element and at least two temperature sensors, which are arranged, for example, on the measuring surface of the sensor chip, with one temperature sensor being mounted upstream of the heating element and the other temperature sensor downstream of the heating element.From an asymmetry of the temperature profile recorded by the temperature sensors, which is influenced by the flow of the fluid medium, a mass flow and / or volume flow of the fluid medium can be inferred.

[0003] Hot-film air mass meters are typically designed as plug-in sensors that can be permanently or replaceably inserted into a flow tube. For example, this flow tube can be the intake tract of an internal combustion engine.

[0004] A partial flow of the medium flows through at least one main channel provided in the hot-film air mass meter. A bypass channel is formed between the inlet and the outlet of the main channel. In particular, the bypass channel is designed such that it has a curved section for deflecting the partial flow of the medium entering through the inlet of the main channel. The curved section further transitions into a section in which the sensor chip is arranged. The latter section represents the actual measuring channel in which the sensor chip is arranged.

[0005] Such hot-film air mass meters must meet a variety of requirements in practice. In addition to the goal of reducing the overall pressure drop across the hot-film air mass meter through suitable fluidic design, one of the main challenges is to further improve the signal quality and the robustness of the devices against contamination by oil and water droplets, as well as soot, dust, and other solid particles. This signal quality refers, for example, to the mass flow of the medium through the measuring channel leading to the sensor chip, as well as, where appropriate, to reducing signal drift and improving the signal-to-noise ratio.Signal drift refers to the deviation, for example, of the mass flow of the medium, in the sense of a change in the characteristic curve relationship between the actual mass flow and the output signal determined during calibration during production. When determining the signal-to-noise ratio, the sensor signals output in rapid temporal succession are considered, whereas characteristic curve or signal drift refers to a change in the mean value.

[0006] In conventional hot-film air mass meters of the type described, a sensor carrier with a sensor chip attached or inserted thereon usually projects into the measuring channel. For example, the sensor chip can be glued into the sensor carrier or glued onto it. The sensor carrier can, for example, form a unit with a metal base plate, to which electronics, a control and evaluation circuit (for example with a circuit carrier, in particular a printed circuit board) can also be glued. For example, the sensor carrier can be designed as an injection-molded plastic part of an electronic module. The sensor chip and the control and evaluation circuit can be connected to one another, for example by bonding. The electronic module created in this way can, for example, be glued into a sensor housing, and the entire plug-in sensor can be closed with covers.

[0007] DE 101 35 142 A1 describes a device for determining at least one parameter of a medium flowing in a line. The device has an inlet area, which at its downstream end is connected to two discharge openings through which the liquid and solid particles can flow back into the line. All channels are formed in the sensor housing of the device itself. When the channels are closed by the cover, fitting inaccuracies can occur, which in turn affect the measurement accuracy.

[0008] DE 10 2011 005 768 A1 discloses a sensor arrangement for determining at least one parameter of a fluid medium flowing through a channel structure, in particular an intake air mass flow of an internal combustion engine. The sensor arrangement has a sensor housing designed as a plug-in sensor. The sensor housing has a channel structure. The sensor housing has a housing body and a cover. The channel structure has a main channel and a measuring channel in which a sensor chip for determining the parameter of the fluid medium is arranged. The sensor housing has an inlet into the channel structure, which faces opposite a main flow direction of the fluid medium, at least one first main channel outlet from the main channel, and at least one measuring channel outlet from the measuring channel. The channel structure is formed in the cover.

[0009] From DE 101 35 142 A1, a sensor arrangement for determining at least one parameter of a fluid medium flowing through a channel structure is known, in which two main channel outlets formed symmetrically to one another are provided on opposite sides of a plug-in sensor.

[0010] However, hot film air mass meters usually have a single outlet from the main duct.

[0011] Despite the numerous advantages of the devices known from the state of the art, they still have potential for improvement in terms of functionality. For example, the one-sided outlet means that the air flow around the plug-in sensor is asymmetrical. This increases sensitivity to changing inflow conditions, such as clogged filter mats. Such characteristic changes are perceived by the control unit as drift, so that in the worst case, the hot-film air mass meter is diagnosed as faulty, even though the cause of the deviation lies in the changed inflow and, for example, a filter change would solve the actual problem. Disclosure of the invention

[0012] A sensor arrangement for determining at least one parameter of a fluid medium flowing through a channel structure is therefore proposed, which can at least largely avoid the disadvantages of known methods and devices and in which, in particular, an asymmetric flow around the sensor arrangement is avoided.

[0013] The sensor arrangement according to the invention for determining at least one parameter of a fluid medium flowing through a channel structure, in particular an intake air mass flow of an internal combustion engine, comprises a sensor housing. The sensor housing can, for example, be a plug-in sensor that is inserted or can be inserted into a flow tube. The sensor housing has the channel structure. The sensor housing has a housing body and a cover. The channel structure has a main channel and a measuring channel. At least one sensor chip for determining the parameter of the fluid medium is arranged in the measuring channel. The sensor housing has an inlet into the channel structure that faces the main flow direction of the fluid medium, at least one first main channel outlet from the main channel, and at least one measuring channel outlet from the measuring channel. The channel structure is formed in the cover.According to the invention, the sensor housing has a second main channel outlet from the main channel, wherein the first main channel outlet and the second main channel outlet are formed in the cover and on opposite sides of the cover, wherein the main channel has a tapered section formed upstream of the first main channel outlet and the second main channel outlet, wherein the first main channel outlet is longer than the second main channel outlet, wherein the second main channel outlet is straight and the first main channel outlet is delimited by curved channel walls.

[0014] The housing body can have at least one outlet opening, wherein the first main channel outlet or the second main channel outlet is connected to the outlet opening. This allows the dirt particles flowing out of the main channel to flow out of the cover and out of the housing body. Such outflow is also possible simultaneously, since the dirt particles can leave the sensor housing at the cover and at the housing body. The first main channel outlet and the second main channel outlet can each be arranged on sides of the cover that are oriented substantially parallel to the main flow direction. The measuring channel outlet can be arranged on an end face of the cover. The main channel can be formed substantially parallel to the main flow direction. The orientation of the first main channel outlet and the second main channel outlet can be defined by their center line.

[0015] In the context of the present invention, the main flow direction is understood to mean the local flow direction of the fluid medium at the location of the sensor arrangement, where, for example, local irregularities such as turbulence can be disregarded. In particular, the main flow direction can thus be understood to mean the local averaged transport direction of the flowing fluid medium at the location of the sensor arrangement. The averaged transport direction refers to a transport direction in which the fluid medium predominantly flows on average over time.

[0016] In the context of the present invention, a downstream arrangement is understood to mean the arrangement of a component at a location which the fluid medium reaches later than a reference point when flowing in the main flow direction.

[0017] Analogously, within the scope of the present invention, an upstream arrangement of a component is to be understood as an arrangement of the component at a location which reaches the fluid medium flowing in the main flow direction earlier than a reference point.

[0018] In the context of the present invention, a housing body and a cover are understood to mean at least two components of the sensor housing which interact and which, for example, are in direct contact, such as a force-fitting and / or a form-fitting and / or a material-fitting connection.

[0019] The housing body and the cover can each be designed as a single piece or as multiple pieces. A cover is generally understood to be a component of the sensor housing which forms a surface around the outlet opening that faces the fluid medium outside the sensor housing. The housing body, on the other hand, is a component which is arranged in the region of the outlet opening on the side of the sensor housing opposite this surface. According to the invention, it is proposed to form the at least one channel in the cover. The housing body and / or the cover can, for example, be made entirely or partially from a plastic material, although, alternatively or additionally, the use of other materials is also possible, for example ceramic and / or metallic materials. The housing body and the cover can, for example, be part of a plug-in sensor.

[0020] The outlet opening, the first main channel outlet, the second main channel outlet, and the measuring channel outlet can, in principle, have any desired cross-section, for example, a round, oval, polygonal, or even slot-shaped cross-section. The outlet opening can preferably be arranged on a side surface of the housing body, which is arranged in the flow tube such that the side surface is preferably oriented substantially parallel to a main flow direction, i.e., with a deviation of preferably no more than 20°, in particular no more than 10°, and particularly preferably no more than 5° from a parallel alignment to the main flow direction.

[0021] Further possible configurations relate to the channel structure of the sensor arrangement. This channel structure can be configured as a single or multiple-part structure. In particular, at least one sensor element for detecting the at least one parameter can be accommodated in the channel structure. This sensor element can be, in particular, a hot-film air mass meter sensor element, for example, a hot-film air mass meter sensor chip according to the above description. However, other configurations are also possible as alternatives or in addition.

[0022] The channel structure can in particular have at least one main channel and at least one bypass channel branching off from the main channel. The sensor element can in particular be arranged in the optional at least one bypass channel. For example, the main channel can extend from an upstream, front-side inlet opening to the outlet opening. The bypass channel can branch off from the main channel and open into one or more bypass channel outlet openings, which can for example also be arranged on a side surface of the plug-in sensor and / or on a head side that projects furthest into the flowing fluid medium. However, other configurations are also possible.

[0023] The cover can, in particular, have an outer side facing the fluid medium. This outer side can, for example, face the fluid medium outside the sensor housing, in particular in the flow tube, and can, for example, be flowed around or flushed by the fluid medium in the flow tube. The first main channel outlet or the second main channel outlet is formed in the cover. Accordingly, a portion of the fluid medium conveying the particles can flow out of the sensor housing back into the fluid medium outside the sensor housing.

[0024] A basic idea of the present invention is to eliminate asymmetric flow around the sensor assembly by providing main channel outlets on both sides of the cover. This reduces the sensitivity to changing flow conditions. Compared to conventional sensor assemblies with a single-sided outlet, the inventive implementation requires only a new cover, while the rest of the housing body can remain unchanged. Short description of the drawings

[0025] Further optional details of the invention emerge from the following description of preferred embodiments, which are shown schematically in the figures.

[0026] They show: Fig. 1 a perspective view of a sensor arrangement according to the invention, Fig. 2 a partially sectioned, perspective view of the sensor arrangement, Fig. 3 a cross-sectional view of a sensor arrangement not according to the invention, which serves only for explanation and Fig. 4 a cross-sectional view of a sensor arrangement according to the invention according to a first embodiment. Embodiments of the invention

[0027] Fig. 1 shows a perspective view of a sensor arrangement 10 for determining a parameter of a fluid medium flowing through a channel according to a first embodiment of the present invention. In this exemplary embodiment, the sensor arrangement 10 is designed as a hot-film air mass meter and can, in particular, detect an intake air mass flow of an internal combustion engine. In this exemplary embodiment, the sensor arrangement 10 comprises a sensor housing 12. The sensor housing 12 is designed as a plug-in sensor which can, for example, be plugged into a flow pipe, in particular an intake tract of the internal combustion engine. A channel structure 14 is formed in the sensor housing 12, as will be explained in more detail below. The sensor housing 12 has a housing body 16 and a cover 18. The channel structure 14 is formed in the cover 18. Through the channel structure 14, air can be passed via an inlet opening oran inlet 20 which, when inserted, points in the opposite direction to a main flow direction 22 of the fluid medium, a representative quantity of the fluid medium can flow.

[0028] Fig. 2 shows a partially sectioned, perspective view of the sensor arrangement 10. The section runs parallel to the main flow direction 22 and perpendicular to an extension direction of the sensor housing 12 of the sensor arrangement 10. The channel structure 14 has a main channel 24, which opens into a first main channel outlet 26 and a second main channel outlet 28. The first main channel outlet 26 and the second main channel outlet 28 are on opposite sides 30, 32 of the cover 18 with respect to the illustration in Fig. 1 and Fig. 2. The first main channel outlet is arranged on an upper side 30 of the cover 18 facing away from the housing body 16, as shown in Fig. 1 and Fig. 2. The second main channel outlet 28 is formed on a bottom side 32 of the cover 18 facing the housing body 16. In the Fig. 2, the first main channel outlet 26 and the second main channel outlet 28 are arranged on the top side 30 and the bottom side 32, respectively, and thus are each arranged on sides 30, 32 of the cover 18 which are oriented substantially parallel to the main flow direction 22.

[0029] The channel structure 14 further comprises a bypass or measuring channel 34 branching off from the main channel 24, which opens into a measuring channel outlet 38 of the measuring channel 34 arranged on an end face 36. As with conventional air mass meters, a sensor carrier in the shape of a wing protrudes into the measuring channel 34. A sensor chip is embedded in this sensor carrier in such a way that the fluid medium flows over a sensor membrane designed as the sensor region of the sensor chip. The sensor carrier, together with the sensor chip, is part of an electronic module that has a curved base plate and a printed circuit board attached thereto, for example glued, with a control or evaluation circuit. The sensor carrier can, for example, be injection-molded onto the base plate as a plastic component.The sensor carrier, which is injection-molded onto the base plate, for example, and can then be formed integrally with the base plate of the circuit board, is provided with a leading edge, which can be rounded.

[0030] The sensor chip is electrically connected to the control and evaluation circuit via electrical connections, which can be implemented as wire bonding. The resulting electronic module is inserted, such as glued, into an electronics compartment 40 of the sensor housing 12, or more precisely, the housing body 16. This can be done in such a way that the sensor carrier protrudes into the channel structure 14. The electronics compartment 40 is then closed by an electronics compartment cover 42.

[0031] The housing body 16 has a cover receiving section 44, onto which the cover 18 with the channel structure 14 is placed, so that the channel structure 14 is closed on all sides. Fig. 2 further shows that the housing body 16 has at least one outlet opening 46 formed in the cover receiving section 44. The first main channel outlet 26 or the second main channel outlet 28 is connected to the outlet opening 46. In the Fig. 2, the second main channel outlet 28 is connected to the outlet opening 46. In other words, the second main channel outlet 28 is in fluid communication with the outlet opening 46. Particles, such as dirt particles or oil droplets, that enter the main channel 24 through the inlet opening 20 cannot completely follow the fluid medium into the measuring channel 34 and are transported through it with the fluid medium flowing in the main channel 24. After flowing through the main channel 24, the particles can thus flow out of the cover 18 on both sides through the first main channel outlet 26 and the second main channel outlet 28. Some of these particles exit the sensor housing 12 through the first main channel outlet 26, whereas another part of these particles exit the sensor housing 12 through the second main channel outlet 28 and the outlet opening 46.

[0032] Fig. 3 shows a cross-sectional view of a sensor arrangement 10 not encompassed by the invention, wherein the section runs parallel to the main flow direction 22 and perpendicular to the extension direction of the sensor housing 12 and is laid through the main channel 24. In Fig. 3 shows the main channel 24, which is formed substantially parallel to the main flow direction 22. The first main channel outlet 26 and the second main channel outlet 28 are straight. In particular, the first main channel outlet 26 and the second main channel outlet 28 are formed symmetrically to one another. The symmetrical design is oriented, for example, on a plane parallel to the main flow direction and parallel to the extension direction of the sensor housing 12. A section 48 of the cover 18, which is located between the first main channel outlet 26 and the second main channel outlet 28 in a cross-sectional view parallel to the main flow direction 22, is wedge-shaped. A tip 50 of the wedge-shaped section 48 faces the inlet 20.Such a symmetrical design of the first main channel outlet 26 and the second main channel outlet 28 is optimal in terms of a symmetrical flow around the sensor housing 12. However, this embodiment requires an additional slide in the injection mold for production.

[0033] Fig. Fig. 4 shows a cross-sectional view of the sensor arrangement 10 according to the invention according to a first embodiment, wherein the section runs parallel to the main flow direction 22 and perpendicular to the extension direction of the sensor housing 12 and is laid through the main channel 24. Only the differences to Fig.3 and identical components are provided with identical reference numerals. In this embodiment, the first main channel outlet 26 and the second main channel outlet 28 are not formed symmetrically to one another. The main channel 24 has a tapered section 52 formed upstream of the first main channel outlet 26 and the second main channel outlet 28. Furthermore, the first main channel outlet 26 is longer than the second main channel outlet 28. The second main channel outlet 28 is straight as in the first embodiment, whereas the first main channel outlet 26 is delimited by curved channel walls 54. The second embodiment has the advantage that it can be manufactured without an additional slide in the injection mold, since the first main channel outlet 26 can be completely demolded from the upper and lower mold halves. A dashed line indicates a parting line 56 for the mold halves.

Claims

[1] Sensor arrangement (10) for determining at least one parameter of a fluid medium flowing through a channel structure (14), in particular an intake air mass flow of an internal combustion engine, wherein the sensor arrangement (10) comprises a sensor housing (12), in particular a plug-in sensor introduced or insertable into a flow tube, wherein the sensor housing (12) comprises the channel structure (14), wherein the sensor housing (12) comprises a housing body (16) and a cover (18), wherein the channel structure (14) comprises a main channel (24) and a measuring channel (34), wherein at least one sensor chip for determining the parameter of the fluid medium is arranged in the measuring channel (34), wherein the sensor housing (12) has an inlet (20) into the channel structure (14), which faces the main flow direction (22) of the fluid medium, at least one first main channel outlet (26) from the main channel (24) and at least one measuring channel outlet (38) from the measuring channel (34),wherein the channel structure (14) is formed in the cover, , characterized by in that the sensor housing (12) has a second main channel outlet (28) from the main channel (24), wherein the first main channel outlet (26) and the second main channel outlet (28) are formed in the cover (18) and on opposite sides (30, 32) of the cover (18), wherein the main channel (24) has a tapered section (52) formed upstream of the first main channel outlet (26) and the second main channel outlet (28), wherein the first main channel outlet (26) is longer than the second main channel outlet (28), wherein the second main channel outlet (28) is straight and the first main channel outlet (26) is delimited by curved channel walls (54). [2] Sensor arrangement (10) according to claim 1, wherein the sensor housing (12) has at least one outlet opening (46), wherein the first main channel outlet (26) or the second main channel outlet (28) is connected to the outlet opening (46). [3] Sensor arrangement (10) according to one of the preceding claims, wherein the first main channel outlet (26) and the second main channel outlet (28) are each arranged on sides (30, 32) of the cover (18) which are substantially parallel to the main flow direction (22). [4] Sensor arrangement (10) according to one of the preceding claims, wherein the measuring channel outlet (38) is arranged on an end face (36) of the cover (18). [5] Sensor arrangement (10) according to one of the preceding claims, wherein the main channel (24) is formed substantially parallel to the main flow direction (22).

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