Sensor device for detecting at least one flow property of a flowing fluid medium

Abstract

Sensor device (10) for detecting at least one flow property of a fluid medium, comprising at least one sensor housing (14), wherein at least one electronic module (30) with at least one flow sensor (40) for detecting the flow property is included in the sensor housing (14), wherein the electronic module (30) is at least partially enclosed in an electronics compartment (20), wherein at least one humidity sensor (42) is further included within the sensor housing (14), wherein the sensor housing (14) has at least one inlet opening (46) for supplying the humidity sensor (42) with moisture from the fluid medium, characterized in that the sensor housing (14) has at least one outlet opening (48) for releasing the fluid medium from the electronics compartment (20), wherein a gel (58) is provided in the electronics compartment (20), wherein the gel (58) at least partially covers the electronic module (30).wherein the sensor housing (14) has at least one projection (60) extending towards the electronics compartment (20), the projection (60) extending into the gel (58), the projection (60) defining at least one channel (62), the channel (62) connecting the inlet opening (46) and the outlet opening (48).

Description

State of the art

[0001] Numerous methods and devices for determining the flow properties of fluid media, i.e., liquids and / or gases, are known from the prior art. These flow properties can, in principle, be any physically and / or chemically measurable properties that qualify or quantify the flow of the fluid medium. In particular, they can be flow velocity and / or mass flow rate and / or volume flow rate.

[0002] The invention is described below, in particular with reference to so-called hot-film air mass meters, as described, for example, in Konrad Reif (ed.), Sensors in Motor Vehicles, 1st ed. 2010, pages 146-148. Such hot-film air mass meters are generally based on a sensor chip, in particular a silicon sensor chip, with a measuring surface that is permeable to the flowing fluid medium. The sensor chip typically 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. An asymmetry in the temperature profile detected by the temperature sensors, which is influenced by the flow of the fluid medium, allows conclusions to be drawn about the mass flow and / or volume flow rate of the fluid medium. Hot-film air mass meters are usually designed as plug-in sensors that can be permanently or interchangeably inserted into a flow tube..

[0003] For example, this flow pipe could be an intake manifold of an internal combustion engine.

[0004] To be able to precisely infer specific flow characteristics of the fluid medium from the sensor signals of the hot-film air mass meter, it is desirable in many cases to be able to provide further information about the fluid medium. For example, DE 10 2010 043 083 A1 describes a sensor device for detecting a flow characteristic of a fluid medium, which includes an air mass meter with a sensor element for detecting an air mass flow. A humidity sensor is also provided.

[0005] Despite the advantages offered by these sensor devices, there is still room for improvement. For example, the humidity sensor, mounted on a separate circuit board, is protected from media and mechanical impact by a plastic frame with an integrated membrane that acts as a pressure equalization element. To ensure the humidity sensor has access to the measuring medium, the electronics compartment cover above it is equipped with an inlet opening. The humidity sensor features a humidity frame and a moisture-semi-permeable membrane at the same level as the electronics compartment cover. Fluid media can enter and exit the electronics compartment through the gap between the electronics compartment cover and the humidity sensor, or via a drain hole in the cover. In particular, water ingress can damage the electronic components in the electronics compartment, for example, through icing. Disclosure of the invention

[0006] Therefore, a sensor device for detecting at least one flow property of a flowing fluid medium is proposed, which largely avoids the disadvantages of known sensor devices described above and is designed in particular to provide improved discharge of the fluid medium and thus ventilation of the humidity sensor.

[0007] Regarding the at least one flow property to be detected, which can be measured qualitatively and / or quantitatively, reference can be made, for example, to the above description of the prior art. In particular, this flow property can be a flow velocity and / or a mass flow rate and / or a volume flow rate of the fluid medium. The fluid medium can be, in particular, a gas, preferably air. The sensor device is particularly suitable for use in automotive engineering, for example, in the intake manifold of an internal combustion engine. However, other areas of application are also possible in principle.

[0008] The sensor device according to the invention for detecting at least one flow property of a fluid medium comprises at least one sensor housing. Within the scope of the present invention, a sensor housing is understood to be a one-piece or multi-piece device that at least largely seals the sensor device externally and protects it at least largely against mechanical influences and preferably also against other types of influences, for example, chemical influences and / or moisture influences. In particular, the sensor housing can comprise at least one plug-in sensor or be designed as a plug-in sensor, wherein the plug-in sensor can be inserted into the flowing fluid medium, and a replaceable or permanent insertion is conceivable.The probe can, for example, protrude into a flow tube of the flowing fluid medium, whereby the flow tube itself can be part of the sensor device or can be provided as a separate component, for example with an opening into which the probe can be inserted. The probe and the sensor housing can, in particular, be made at least partially of a plastic material, for example by means of an injection molding process.

[0009] The sensor housing contains at least one electronic module with at least one flow sensor for detecting the flow characteristics. A housing within the sensor housing means that the electronic module is at least partially, and preferably completely, enclosed by the sensor housing. The electronic module is at least partially arranged in at least one electronic compartment within the sensor housing. Within the scope of the present invention, an electronic compartment is understood to be a partially or completely enclosed space within the sensor housing, which is closed off by the sensor housing in at least one direction. Preferably, the electronic compartment comprises at least one recess in the sensor housing accessible from a surface of the sensor housing, for example, a cuboid recess.The electronics compartment can be accessible for component placement, for example from the surface, as will be explained in more detail below, and can be permanently or reversibly closed by at least one closing element, for example at least one electronics compartment cover.

[0010] A flow sensor is essentially any sensor element designed to detect at least one flow characteristic. In particular, the flow sensor can be at least one hot-film air mass meter chip, for example, of the type described above. Specifically, this hot-film air mass meter chip can comprise at least one silicon chip with a measuring surface that is accessible to the flowing fluid medium. This sensor surface can, for example, contain at least one heating element and at least two temperature sensors, whereby, as described above, an asymmetry in the temperature profile measured by the temperature sensor can indicate the at least one flow characteristic. The at least one flow sensor can, for example, be arranged on a sensor carrier of the electronic module that projects into the flowing fluid medium.The electronic module can be designed as a single unit and can, in particular, include a control and / or evaluation circuit configured to control the flow sensor and / or receive signals from the flow sensor. Accordingly, the electronic module can, for example, have at least one circuit carrier. Furthermore, the electronic module can, in particular, have at least one sensor carrier, which is preferably mechanically connected to the circuit carrier. For example, the circuit carrier can be arranged in the electronics compartment of the sensor housing, and the sensor carrier can project from this electronics compartment into the fluid medium.It is particularly preferred if the sensor housing has at least one flow channel through which the fluid medium flows, wherein the sensor carrier of the electronic module, which carries the flow sensor, projects from the electronics compartment into the at least one flow channel through which the fluid medium flows in the sensor housing. This at least one flow channel can, in particular, be designed as a single piece, but can also have at least one main channel and at least one bypass channel branching off from this main channel, wherein the sensor carrier preferably projects into the bypass channel, as is generally known from the prior art.

[0011] The circuit carrier of the electronic module can, in particular, comprise a printed circuit board (PCB), which can be used independently or, for example, mounted on a mechanical support, such as a base plate in the form of a stamped and bent part, which may be made of a metallic material. The sensor carrier can be directly connected to the circuit carrier or to the support component, such as the base plate, for example, by injection molding the sensor carrier onto the base plate. Other configurations are also possible in principle. For example, it is conceivable to manufacture the electronic module from the PCB material, with both the circuit carrier and the sensor carrier being made from the same PCB material, preferably from a single piece of the PCB material.Alternatively or additionally, it is also possible to use injection-molded printed circuit boards known from the prior art as electronic modules, for example, injection-molded printed circuit boards using one or more so-called MID technologies (MID = molded interconnect device). Various configurations are therefore conceivable.

[0012] The sensor device further comprises at least one humidity sensor. The humidity sensor is housed within the sensor housing. An arrangement within the sensor housing is understood to mean an arrangement in which the humidity sensor is at least partially, and preferably completely, enclosed by the sensor housing. A humidity sensor is, in principle, any sensor element designed to detect the moisture content of the fluid medium. For example, resistive and / or capacitive sensor elements, as known from the prior art, are suitable. Examples of such humidity sensors are described in Konrad Reif (ed.), 1st ed. 2010, pages 98-101. However, other types of humidity sensors are also suitable, either alternatively or additionally, for use within the scope of the present invention.

[0013] The sensor housing has at least one inlet opening for supplying the humidity sensor with moisture from the fluid medium. Furthermore, the sensor housing has at least one outlet opening for draining the fluid medium from the electronics compartment. A gel is provided in the electronics compartment. The gel at least partially covers the electronic module. Preferably, the gel is cured and therefore no longer flowable. The sensor housing also has at least one projection extending towards the electronics compartment. This projection extends into the gel and defines a channel. The channel connects the inlet opening and the outlet opening. Accordingly, any fluid medium that has entered the electronics compartment is guided through the channel to the outlet opening.

[0014] Preferably, as mentioned above, the sensor housing has at least one electronics compartment cover. The electronics compartment cover is designed to close the electronics compartment. The electronics compartment cover has a projection. This allows the channel to be formed when the electronics compartment is closed by means of the electronics compartment cover. The channel is laterally bounded by the electronics compartment cover, the projection, and the gel.

[0015] Preferably, the inlet and / or outlet openings are formed in the electronics compartment cover. Alternatively or additionally, the inlet and / or outlet opening can be formed in the sensor housing itself. The projection can define the inlet and outlet openings.

[0016] The electronic module can include the humidity sensor. The electronic module can, for example, include a circuit carrier, with the humidity sensor mounted on the circuit carrier. The electronic module can also include a sensor carrier, as mentioned above. The sensor carrier can support the flow sensor and project from the electronics compartment into at least one flow channel in the sensor housing through which the fluid medium flows, with the flow sensor and the humidity sensor being located on the same side of the electronic module. For example, the electronic module includes a control and / or evaluation circuit, with the control and / or evaluation circuit being mounted on the circuit carrier, and the control and / or evaluation circuit and the humidity sensor being located together on one side of the circuit carrier.

[0017] The channel can be designed to ventilate the humidity sensor. Ventilation in this context refers to creating a flow of the fluid medium within the channel from the inlet to the outlet. This can be achieved, in particular, by designing the sensor housing such that, when the fluid medium flows around the sensor housing, a higher static pressure prevails in the area of ​​the inlet than in the area of ​​the outlet. Static pressure in the area of ​​the inlet and outlet refers to the static pressure exerted on the respective cross-sectional area of ​​the inlet and outlet by the fluid medium from the outside; that is, the static pressure acting from the surroundings of the sensor housing towards the interior of the sensor housing or the channel.

[0018] Within the scope of the present invention, static pressure is understood to be the ratio of a force exerted on each surface in contact with the fluid, which is proportional to the size of the surface. The static pressure can be determined, for example, using the equation Pstat. = P × g × h, where P is the density of the fluid, g is the acceleration due to gravity, and h is the height of the fluid column above the surface.

[0019] Within the scope of the present invention, the pressure difference between the inlet opening and the outlet opening is achieved through structural features of the sensor housing. For example, a pressure difference can be realized by appropriately designing the cross-sectional areas, position, and shape of the inlet and outlet openings. Further structural features, such as turbulators or the shape of the electronics compartment cover, can also cause fluid to flow from the inlet to the outlet opening in the channel.

[0020] The humidity sensor can have at least one measuring chamber, wherein the measuring chamber is bounded by at least one membrane that is at least partially permeable to moisture and a frame.

[0021] The inlet opening can have any cross-section, for example, a rectangular, round, and / or polygonal cross-section. Other designs are also possible.

[0022] The projection itself can form a channel. For example, the electronics compartment cover is double-walled, so the projection forms a channel. This design can be used in cases where it is assumed that the gel will not form a flat surface when curing. A projection in the form of a channel thus allows for defined cross-sectional ratios to be achieved.

[0023] The sensor device can also include one or more additional sensor elements for detecting at least one further physical and / or chemical property of the fluid medium. In particular, the sensor device can further comprise at least one temperature sensor, especially at least one temperature sensor arranged on an outer surface of the sensor housing. For example, a temperature sensor can be arranged on an outer surface of the sensor housing such that it is located on a side opposite the humidity sensor. However, other configurations are also possible in principle. In particular, the temperature sensor can be arranged in at least one recess on a side wall of the sensor housing. The temperature sensor can, in particular, comprise at least one temperature-dependent resistor. Alternatively or additionally, other types of temperature sensors can also be used.The temperature sensor can be freely exposed to the flowing fluid medium, meaning it is not enclosed by the sensor housing of the sensor element. The temperature sensor can be connected to the sensor housing by friction and / or positive locking, for example, by crimping the sensor leads to an outer wall of the sensor housing or connecting them in another way. The temperature sensor leads can be routed into the interior of the sensor housing and connected there, for example, to the electronic module and / or to a connector of the sensor device. Various other configurations are conceivable.

[0024] The sensor device may also include, for example, a pressure sensor. A pressure sensor is generally understood to be any sensor element designed to detect the pressure of the fluid medium. In particular, this can refer to pressure sensors such as those described in Konrad Reif (ed.), Sensors in Motor Vehicles, 1st ed. 2010, pages 80-82 and 134-136. However, other types of pressure sensors can also be used alternatively or additionally, for example, pressure sensors that are directly based on the use of one or more strain gauges or similar pressure sensor elements. Brief description of the drawings

[0025] Further optional details and features of the invention will become apparent from the following description of preferred embodiments, which are shown schematically in the figures.

[0026] They show: Fig. 1 an exploded view of a sensor device according to the invention for detecting at least one flow property of a fluid medium, Fig. 2 a cross-sectional view of the sensor device and Fig. 3 A top view of the sensor device. Embodiments of the invention

[0027] Fig. Figure 1 shows an exploded view of a sensor device 10 according to the invention for detecting at least one flow property of a fluid medium. In this embodiment, the sensor device 10 is designed as a hot-film air mass meter and comprises a plug-in sensor 12. The plug-in sensor 12 can be inserted into a flow of the fluid medium, for example, an intake air mass flow, for example, reversibly plugged into an intake pipe or permanently installed. The plug-in sensor 12 comprises a sensor housing 14. The sensor housing 14 contains a channel section 16 and an electronics section 18 with an electronics compartment 20 embedded in the sensor housing 14. The channel section 16 can be closed by a bypass channel cover 22. A flow channel 24 through which the fluid medium flows is formed in the bypass channel cover 22. The flow channel 24 has a main channel 26 and a bypass channel 28 branching off from it.

[0028] Electronics compartment 20 contains an electronics module 30. The electronics module 30 has a circuit carrier 32 with a control and / or evaluation circuit 34, which can, for example, be mounted on a base plate 36. The electronics module 30 also has a sensor carrier 38 in the form of a wing molded onto the base plate 36. The sensor carrier 38 projects into the bypass channel 28. A flow sensor 40 in the form of a hot-film air mass meter chip is embedded in the sensor carrier 38.

[0029] The sensor device 10 also includes a humidity sensor 42. The humidity sensor 42 is housed within the sensor housing 14. The humidity sensor 42 is thus arranged on the circuit carrier 32 of the electronic module 30. The sensor carrier 38, the base plate 36, and the circuit carrier 32 form the electronic module 30, which may additionally include the control and / or evaluation circuit 34. In addition to the sensor carrier 38, the electronics of the circuit carrier 32 and the control and / or evaluation circuit 34 are bonded to the base plate 36. The flow sensor 40, the humidity sensor 42, and the control and / or evaluation circuit 34 are typically connected to each other by bonding. The resulting electronic module 30 is, for example, bonded into the electronics compartment 20.

[0030] The sensor device 10 further comprises an electronics compartment cover 44. The electronics compartment cover 44 is designed to close the electronics compartment 20. This closure can be permanent or reversible. The sensor device 10 further comprises at least one inlet opening 46 for supplying the humidity sensor 42 with moisture from the fluid medium. The inlet opening 46 is formed in the electronics compartment cover 44. The sensor device 10 further comprises at least one outlet opening 48 for releasing the fluid medium from the electronics compartment 20. The outlet opening 48 is also formed in the electronics compartment cover 44. The inlet opening 46 and the outlet opening 48 are spaced apart from each other. For example, the inlet opening 46 and the outlet opening 48 are arranged on opposite longitudinal sides of the electronics compartment cover 44.

[0031] Fig. Figure 2 shows a cross-sectional view of the sensor device 10. As in Fig. As shown in Figure 2, the humidity sensor 42 has at least one measuring chamber 50. The measuring chamber 50 is bounded by at least one membrane 52 that is at least partially permeable to moisture and a frame 54. The humidity sensor 42 can be designed as a humidity module 56 or be contained within a humidity module 56. A gel 58 is provided in the electronics compartment 20. The gel 58 at least partially covers the electronics module 30 and, in particular, the circuit carrier 32. The gel 58 is cured, for example, by thermal treatment or by UV light, and is therefore no longer flowable. The sensor device 10 has a projection 60 extending towards the electronics compartment 20. In particular, the electronics compartment cover 44 has the projection 60. The projection 60 is designed, for example, as a sealing blade. The projection 60 extends into the gel 58. In other words, the projection 60 penetrates the gel 58.

[0032] The gel 58 protects the electronics of the sensor device 10. The electronics compartment cover 44 is provided for mechanical protection.

[0033] Fig. Figure 3 shows a top view of the sensor device 10. For illustrative purposes, the electronics compartment cover 44 is shown transparently, with only the projection 60 depicted as a solid outline. The projection 60 defines a channel 62. The channel 62 connects the inlet opening 46 and the outlet opening 48. Accordingly, fluid medium that has entered the electronics compartment 20 can exit the electronics compartment 20 within the channel 62 in the area of ​​the outlet opening 48. This allows the humidity sensor 42 to be ventilated. As shown in Figure 3, the electronics compartment cover 44 is transparent, with only the projection 60 shown as a solid outline. Fig. As can be seen in figure 3, the projection 60 limits the inlet opening 46 and the outlet opening 48.

[0034] As in Fig. As shown in Figure 1, the flow sensor 40 and the humidity sensor 42 are arranged on the same side 64 of the electronic module 30. In other words, the flow sensor 40 and the humidity sensor 42 are arranged together on one and the same side 64 of the electronic module 30. In particular, the humidity sensor 42 and the control and / or evaluation circuit 34 are arranged together on one side 66 of the circuit carrier 32.

[0035] The sensor device 10 can be configured to detect further flow properties of the fluid medium. As in Fig. As shown in Figure 1, the sensor device 10 can, for example, further comprise at least one temperature sensor 68 designed to detect the temperature of the fluid medium. The temperature sensor 68 can be arranged on an outer surface of the sensor housing 14. For example, the temperature sensor 68 can be arranged on an outer surface of the sensor housing 14 opposite the humidity sensor 42. In particular, the temperature sensor 68 can be arranged in at least one recess on a side wall or the rear of the sensor housing 14. As shown in Figure 1, the sensor device 10 can be further comprised of at least one temperature sensor 68 designed to detect the temperature of the fluid medium. Fig. As further shown in Figure 1, the sensor device can also have a housing seal 70 designed to seal the sensor housing 14 against a flow tube.

Claims

[1] Sensor device (10) for detecting at least one flow property of a fluid medium, comprising at least one sensor housing (14), wherein at least one electronic module (30) with at least one flow sensor (40) for detecting the flow property is included in the sensor housing (14), wherein the electronic module (30) is at least partially enclosed in an electronics compartment (20), wherein at least one humidity sensor (42) is also included within the sensor housing (14), and wherein the sensor housing (14) has at least one inlet opening (46) for supplying the humidity sensor (42) with moisture from the fluid medium. characterized by, that the sensor housing (14) has at least one outlet opening (48) for draining the fluid medium from the electronics space (20), wherein a gel (58) is provided in the electronics space (20), wherein the gel (58) at least partially covers the electronics module (30), wherein the sensor housing (14) has at least one projection (60) extending towards the electronics space (20), wherein the projection (60) extends into the gel (58), wherein the projection (60) defines at least one channel (62), wherein the channel (62) connects the inlet opening (46) and the outlet opening (48). [2] Sensor device (10) according to the preceding claim, wherein the sensor housing (14) has an electronics compartment cover (44), wherein the electronics compartment cover (44) is designed to close the electronics compartment (20), wherein the electronics compartment cover (44) has the projection (60). [3] Sensor device (10) according to the preceding claim, wherein at least the inlet opening (46) and / or the at least one outlet opening (48) are formed in the electronics compartment cover (44) and / or in the sensor housing (14). [4] Sensor device (10) according to one of the preceding claims, wherein the projection (60) limits the inlet opening (46) and the outlet opening (48). [5] Sensor device (10) according to one of the preceding claims, wherein the electronic module (30) comprises the humidity sensor (42). [6] Sensor device (10) according to one of the preceding claims, wherein the electronic module (30) has a circuit carrier (32), wherein the humidity sensor (42) is arranged on the circuit carrier (32). [7] Sensor device (10) according to one of the preceding claims, wherein the electronic module (30) comprises a sensor carrier (38), wherein the sensor carrier (38) carries the flow sensor (40) and projects from the electronic space (20) into at least one flow channel in the sensor housing (14) through which the fluid medium can flow, wherein the flow sensor (40) and the humidity sensor (42) are arranged on the same side (64) of the electronic module (30). [8] Sensor device (10) according to the preceding claim, wherein the electronic module (30) has a control and / or evaluation circuit (34), wherein the control and / or evaluation circuit (34) is arranged on the circuit carrier (32), wherein the control and / or evaluation circuit (34) and the humidity sensor (42) are arranged together on one side (66) of the circuit carrier (32). [9] Sensor device (10) according to one of the preceding claims, wherein the channel (62) is designed to ventilate the humidity sensor (42). [10] Sensor device (10) according to one of the preceding claims, wherein the humidity sensor (42) has at least one measuring chamber (50), wherein the measuring chamber (50) is limited by at least one membrane (52) that is at least partially permeable to moisture and a frame (54).

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