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

Abstract

The invention provides a sensor (10) for determining at least one parameter of a fluid medium flowing through a measuring channel (30), in particular an intake air mass flow of an internal combustion engine. The sensor (10) comprises a sensor housing (12), in particular a plug-in probe which is installed or can be installed in a flow tube, the measuring channel (30) being constructed in the sensor housing and comprising at least one first sensor chip (42) arranged in the measuring channel (30) for determining the parameter of the fluid medium and an electronic component module (38). The electronic component module (38) comprises a control and / or analysis circuit (50). The sensor (10) further comprises a second sensor chip (54) for determining the mass composition of the fluid medium. The second sensor chip (54) is connected to the control and / or analysis circuit (50).

Description

Background Art

[0001] From the prior art, a variety of methods and devices are known for determining at least one flow property of a fluid medium, i.e. a liquid and / or a gas. In this case, the flow property as a possible parameter can be any physical and / or chemical measurable property which qualitatively or quantitatively determines the flow of the fluid medium. In this case, it can be, in particular, a flow velocity and / or a mass flow and / or a volume flow.

[0002] The invention is described below with particular reference to so-called hot film air flow meters, as are known, for example, from Konrad Reif (editor): Sensoren im Kraftfahrzeug, 1st edition 2010, pages 146-148. Such hot film air flow meters are usually based on a sensor chip, in particular a silicon sensor chip, for example having a sensor diaphragm as a measuring surface or sensor area, through which a flowing fluid medium can flow. The sensor chip usually comprises at least one heating element and at least two temperature probes, which are arranged, for example, on the measuring surface of the sensor chip, wherein one temperature probe is arranged upstream of the heating element and the other temperature probe is arranged downstream of the heating element. The mass flow and / or volume flow of the fluid medium can be inferred from the symmetry of the temperature curve sensed by the temperature probes, which is influenced by the flow of the fluid medium.

[0003] Hot film air flow meters are usually designed as plug-in probes that can be fixedly or replaceably inserted into a flow tube, which can be, for example, an intake section of an internal combustion engine.

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

[0005] In conventional hot film air flow meters of the type described, a sensor carrier usually extends into the measuring channel, the sensor carrier having a sensor chip placed or inserted thereon. The sensor chip can, for example, be glued into the sensor carrier or glued to the sensor carrier. The sensor carrier can, for example, form a unit with a base plate consisting of metal, to which electronic components, control and analysis circuits can also be glued (for example via a circuit carrier, in particular a circuit board). The sensor carrier can, for example, be configured as a sprayed plastic part of an electronic component module. The sensor chip and the control and analysis circuit can, for example, be connected to each other via a bonding connection. The electronic component module produced in this way can, for example, be glued into a sensor housing and the entire plug-in detector can be closed by a cover.

[0006] Hot film air flow meters are mainly used to determine the intake air mass flow of an internal combustion engine. In addition, there are hot film air flow meters that additionally determine the humidity, temperature or pressure of the intake air.

[0007] Although the sensors known from the prior art have many advantages, they still contain potential for improvement. To date, in order to determine the quality properties of the air, it has been necessary to provide additional or additional sensors, which is associated with considerable additional costs. Summary of the invention

[0008] Therefore, a sensor for determining at least one parameter of a fluid medium flowing through a measuring channel is proposed which can at least largely avoid the disadvantages of known sensors and which in particular allows the sensing of additional mass properties or mass components of the fluid medium.

[0009] The sensor for determining at least one parameter of a fluid medium flowing through a measuring channel, in particular an intake air mass flow of an internal combustion engine, according to the present invention comprises a sensor housing, in particular a plug-in probe that has been installed or can be installed in a flow tube, in which a measuring channel is constructed, and at least one first sensor chip and an electronic component module arranged in the measuring channel for determining the parameters of the fluid medium. The electronic component module has a control and / or analysis circuit. The sensor also has a second sensor chip for determining the mass composition of the fluid medium. The second sensor chip is connected to the control and / or analysis circuit.

[0010] In addition to the parameter of the fluid medium flowing through the measuring channel, the mass of the fluid medium can thus be sensed by a single sensor, which avoids the need to provide a further sensor for determining this property. The sensor is thus expanded in terms of functionality.

[0011] In the context of the present invention, the mass composition of a fluid medium is understood to mean the amount and type of the components of the fluid medium.

[0012] In a further development, the electronics module has a printed circuit board, wherein the control and / or evaluation circuit is arranged on the printed circuit board, wherein the second sensor chip is arranged on the printed circuit board. The second sensor chip can thus be integrated in the electronics module in a compact manner.

[0013] Here, within the framework of the present invention, a circuit board is generally understood to be a substantially plate-shaped element, which can also be used as a carrier for electronic structures, such as conductor tracks, connecting contacts or the like, and preferably also has one or more of these structures. In principle, at least slight deviations from the plate shape are also considered and should also be included in the concept. The circuit board can be made of plastic material and / or ceramic material, for example epoxy resin, in particular fiber-reinforced epoxy resin. In particular, the circuit board can be configured, for example, as a circuit board (printed circuit board, PCB) with conductor tracks, in particular printed conductor tracks.

[0014] In one embodiment, the second sensor chip is a microelectromechanical sensor chip. The second sensor chip is therefore relatively small and thus requires little installation space.

[0015] In the context of the present invention, a microelectromechanical sensor chip is understood to be a sensor chip whose components have a minimum size in the range of 1 micrometer and function together as a system. Such a microsystem consists of one or more sensor elements and control electronics arranged on the chip. The dimensions of the individual components vary in the range of a few micrometers.

[0016] In one embodiment, the second sensor chip has a substrate which is at least partially produced from a semiconductor material, such as silicon. The substrate carries the components of the sensor chip.

[0017] In a further development, the mass composition comprises at least a proportion of a gas component in the fluid medium and / or a proportion of a solid component in the fluid medium.

[0018] In an extended embodiment, the gas component is at least one compound selected from the group consisting of carbon dioxide, carbon monoxide, ozone, sulfur dioxide and nitrogen oxides. Alternatively or additionally, the solid is at least one element selected from the group consisting of particles, carbon black, dust and fine dust.

[0019] In a further development, the sensor housing has an electronics chamber in which the electronics module is arranged. As a result, the electronics module can be accommodated in the sensor housing in a protected manner.

[0020] In an embodiment, the sensor is designed to be connected to a control unit of a motor vehicle, wherein the motor vehicle has an air conditioning system, wherein the second sensor chip is designed to output a measurement signal, wherein the measurement signal can be processed by the control unit for controlling and / or regulating the air conditioning system. It is thus possible to control or regulate the air conditioning system with the aid of the data obtained by the second sensor chip.

[0021] In an embodiment, the sensor is designed to be connected to a control unit of a motor vehicle, wherein the motor vehicle has an internal combustion engine and an exhaust gas aftertreatment device for aftertreatment of exhaust gas of the internal combustion engine, wherein the second sensor chip is designed to output a measurement signal, wherein the measurement signal can be processed by the control unit for controlling and / or regulating the exhaust gas aftertreatment device. It is thus possible to control or regulate the exhaust gas aftertreatment device with the aid of data obtained by the second sensor chip.

[0022] In addition, a sensor system is proposed, which includes an electronic data processing device and a plurality of sensors according to the aforementioned embodiment. The sensor is wirelessly connected to the electronic data processing device, wherein the second sensor chip is configured to output a measurement signal, wherein the measurement signal can be processed by the electronic data processing device to obtain information about the state of the ambient air. This makes it possible to centrally sense the data of each sensor and to determine information about the quality of the fluid medium at different locations. If the sensor is installed in a plurality of motor vehicles, for example, information about the air quality in the environment of the motor vehicle can be obtained, which information is centrally processed by a remote processing device. In this way, traffic can be controlled in a targeted manner to improve the air quality.

[0023] In the context of the present invention, the main flow direction is understood to be the local flow direction of the fluid medium at the location of the sensor or sensor assembly, wherein, for example, local inhomogeneities such as turbulence may be disregarded. In particular, the main flow direction may therefore be understood to be the locally averaged conveying direction of the flowing fluid medium. The main flow direction may therefore relate, on the one hand, to the flow direction at the location of the sensor assembly itself, or also to the flow direction in a channel inside the sensor housing, such as at the location of the sensor carrier or the sensor chip, wherein the two mentioned main flow directions may be different. In the context of the present invention, it is therefore always specified to which location the main flow direction relates. If no detailed specification is made, the main flow direction relates to the location of the sensor assembly.

[0024] Within the scope of the invention, the sensor carrier can be designed completely or partially as a circuit carrier, in particular a circuit board, or as part of a circuit carrier, in particular a circuit board. The circuit carrier, in particular a circuit board, can, for example, have a projection which forms the sensor carrier and which projects into a channel, for example a measuring channel of a hot film air flow meter. The remainder of the circuit carrier, in particular a circuit board, can, for example, be accommodated in an electronics compartment, a sensor assembly or a housing of a plug-in probe of a sensor assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Further optional details and features of the invention emerge from the following description of preferred exemplary embodiments which are schematically illustrated in the drawings.

[0026] The accompanying drawings show:

[0027] Figure 1 Stereoscopic view of the sensor,

[0028] Figure 2 A magnified view of the sensor's electronics module.

[0029] Figure 3 Schematic representation of signal transmission in a motor vehicle,

[0030] Figure 4 An example of a signal processing for use in a controller of a motor vehicle, and

[0031] Figure 5 Example for sensor systems. DETAILED DESCRIPTION

[0032] Figure 1 A perspective view of a sensor 10 for determining a parameter of a fluid medium is shown. The sensor 10 is configured as a hot film air flow meter and comprises a sensor housing 12 configured as a plug-in probe, which can be inserted into a flow pipe, in particular an intake pipe section of an internal combustion engine, for example. The sensor housing 12 has a housing body 14, a measuring channel cover 16, an electronics chamber 18 and an electronics chamber cover 20 for closing the electronics chamber 18. A channel structure 22 is configured in the housing body 16. The channel structure 22 has a main channel 24, which is connected, for example, to a measuring channel cover 16 in relation to the sensor housing 12. Figure 1 2 , opens into a main flow outlet 26 and has a bypass or measuring channel 30 branching off from the main channel 24 and opening into a bypass or measuring channel outlet 32, which can be designed separately or integrated. A representative amount of the fluid medium can flow through the channel structure 22 via an inlet opening 34, which in the operating state is directed counter to a main flow direction 36 of the fluid medium at the location of the sensor housing 12.

[0033] Figure 2 An enlarged view of an electronic module 38 of a sensor 10 is shown. In the use state of the electronic module 38, a sensor carrier 40 projects into the measuring channel 30. A first sensor chip 42 is inserted into the sensor carrier 40 in such a way that a micromechanical sensor membrane 44, which is configured as a sensor region of the first sensor chip 42, can be flowed through by a fluid medium. The sensor carrier 40 and the first sensor chip 42 are components of the electronic module 38. The electronic module 38 also has a curved base plate 46 and a circuit board 48 mounted on the base plate, for example, bonded thereto, which has a control and / or evaluation circuit 50. The control and / or evaluation circuit 50 is arranged on the circuit board 48. In the illustrated embodiment, the control and / or evaluation circuit 50 is an application-specific integrated circuit (ASIC). The sensor chip 42 is electrically connected to the control and / or evaluation circuit 50 via an electrical connection 52, which is configured here as a wire bond. The electronic component module 38 thus produced is inserted, for example glued, into the electronic component chamber 18 of the housing body 14 (to this extent a fixed component of the sensor housing 12). Here, the sensor carrier 40 projects into the channel structure 22. The electronic component chamber 18 is then closed by the electronic component chamber cover 20.

[0034] The sensor 10 also has a second sensor chip 54 for determining the mass composition of the fluid medium. The mass composition includes at least one component of a gas component in the fluid medium and / or a component of a solid in the fluid medium. The gas component is at least one compound selected from the following group, the group consisting of carbon dioxide, carbon monoxide, ozone, sulfur dioxide and nitrogen oxides. The solid is at least one element selected from the following group, the group consisting of particles, carbon black, dust and fine dust.

[0035] The second sensor chip 54 is a microelectromechanical sensor chip. In particular, the second sensor chip 54 has a substrate which is at least partially made of a semiconductor material. The semiconductor material is, for example, silicon. Alternatively, the semiconductor material is gallium arsenide. Alternatively, the substrate can be made of plastic. The second sensor chip 54 is connected to the control and / or evaluation circuit 50. For this purpose, the second sensor chip 54 is arranged on the circuit board 48.

[0036] Figure 3The diagram of signal transmission in a motor vehicle 56 is shown. The sensor 10 is arranged, for example, in the intake pipe section of an internal combustion engine 58 of the motor vehicle 56. The motor vehicle 56 has a controller 60. The sensor 10 is connected to the controller 60 so that data or signals can be exchanged between the two. The motor vehicle 56 also has an air conditioning facility 62. The second sensor chip 54 is configured to output a measurement signal. The measurement signal can be processed by the controller 60 for controlling and / or regulating the air conditioning facility 62. For example, the measurement signal is obtained by means of the second sensor chip 54 and output to the control and / or analysis circuit 50, where the mass composition of the fluid medium is determined or calculated. The control and / or analysis circuit 50 outputs the measurement signal to the controller 60 through a predetermined channel 64. The channel 64 is a digital interface for communication, such as SENT (Single Edge Nibble Transmission). The controller 60 processes the measurement signal and outputs the processed signal to the control or regulation device of the air conditioning facility 62 through a CAN bus 66. In this way, it can be determined whether and how much fresh air and / or ambient air should be supplied to the interior of motor vehicle 56 by air conditioning system 62 .

[0037] The motor vehicle 56 may alternatively or additionally have an exhaust gas aftertreatment device 68 for aftertreatment of the exhaust gas of the internal combustion engine 58. The measurement signal of the second sensor chip 54 can be processed by the controller 60 in the manner described above for controlling and / or regulating the exhaust gas aftertreatment device 68. For example, the measurement signal is obtained by means of the second sensor chip 54 and output to the control and / or analysis circuit 50, where the mass composition of the fluid medium is determined or calculated. The control and / or analysis circuit 50 in turn outputs the measurement signal to the controller 60 via a predetermined channel 64. The controller 60 processes the measurement signal and outputs the measurement signal to the control or regulation device of the exhaust gas aftertreatment device 68 via the CAN bus 66. In this way, the measurement signal can be considered as an input value in a nitrogen oxide or soot sample, for example.

[0038] Figure 4 An example of signal processing in a control unit 60 of a motor vehicle 56 is shown. In step S10, a raw signal 70 is sensed by the control unit 60. The raw signal 70 can be provided by the second sensor chip 54 or the first sensor chip 42. In step S12, the signal is transmitted. The transmitted signal is subjected to low-pass filtering in step S14. After the low-pass filtering, a summation calculation is performed in step S16. Finally, in step S18, a moving average is calculated, wherein the moving average is calculated by step S20 at each half track change. The trigger signal is then provided. The moving average value obtained in this way is used as an input value for further control or regulation in the motor vehicle.

[0039] Figure 5 An example for a sensor system 72 is shown. The sensor system 72 comprises an electronic data processing device 74 and a plurality of sensors 10 according to the embodiments described above. The sensors 10 are wirelessly connected to the electronic data processing device 74. The second sensor chip 54 is configured to output a measurement signal, which can be processed by the electronic data processing device 74 to obtain information about the state of the ambient air. The sensor 10 is, for example, mounted in a motor vehicle 56. The measurement signal is wirelessly transmitted to the data processing device 74 by the controller 60 of the motor vehicle 56, so that information about the air quality can be associated with the position of the motor vehicle 56 with reference to other data of the motor vehicle 56, such as position data. Therefore, information about the air quality at different locations can be sensed, which in turn can be used to control traffic.

Claims

1. A sensor (10) for determining at least one parameter of a fluid medium flowing through a measuring channel (30), wherein: The fluid medium is an intake air mass flow of an internal combustion engine, wherein the sensor (10) has a sensor housing (12), the measuring channel (30) is formed in the sensor housing and has at least one first sensor chip (42) arranged in the measuring channel (30) for determining a parameter of the fluid medium and an electronics module (38), wherein the electronics module (38) has a control and / or evaluation circuit (50), It is characterized in that The sensor (10) comprises a second sensor chip (54) for determining the mass composition of the fluid medium, wherein the mass composition of the fluid medium is the amount and type of components of the fluid medium, wherein the second sensor chip (54) is connected to the control and / or evaluation circuit (50), wherein the electronic component module (38) comprises a circuit board (48), wherein the control and / or evaluation circuit (50) and the second sensor chip (54) are both arranged on the circuit board (48), Wherein, the second sensor chip (54) is a micro-electromechanical sensor chip, The second sensor chip (54) has a substrate which is at least partially made of a semiconductor material. wherein the mass composition comprises at least one component of a gas component in the fluid medium and / or a component of a solid in the fluid medium, wherein the gas component is at least one compound selected from the group consisting of carbon dioxide, carbon monoxide, ozone, sulfur dioxide and nitrogen oxides, and / or the solid is at least one element selected from the group consisting of particles, carbon black, dust and fine dust, The sensor (10) is configured to be connected to a controller (60) of a motor vehicle (56), wherein the motor vehicle (56) has an air conditioning system (62), wherein the second sensor chip (54) is configured to output a measurement signal, wherein the measurement signal can be processed by the controller (60) for controlling and / or regulating the air conditioning system.

2. The sensor (10) according to claim 1, wherein: The sensor housing (12) has an electronics compartment (18) in which the electronics module (38) is arranged.

3. The sensor (10) according to claim 1 or 2, wherein: The sensor (10) is configured to be connected to a controller (60) of a motor vehicle (56), wherein the motor vehicle (56) has an internal combustion engine (58) and an exhaust gas aftertreatment device (68) for aftertreatment of exhaust gas of the internal combustion engine (58), wherein the second sensor chip (54) is configured to output a measurement signal, wherein the measurement signal can be processed by the controller (60) for controlling and / or regulating the exhaust gas aftertreatment device (68).

4. The sensor (10) according to claim 1, wherein: The sensor housing (12) is a plug-in probe which has been installed or can be installed in a flow tube.

5. The sensor (10) according to claim 1, wherein: The semiconductor material is silicon.

6. A sensor system (72) comprising an electronic data processing device (74) and a plurality of sensors (10) according to any one of claims 1 to 5, wherein: The sensor (10) is wirelessly connected to the electronic data processing device (74), wherein the second sensor chip (54) is configured to output a measurement signal, wherein the measurement signal can be processed by the electronic data processing device (74) to obtain information about air conditions in the environment of the sensor (10).

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