SENSOR FOR DETERMINING AT LEAST ONE PARAMETER OF A FLUID MEDIUM FLOWING THROUGH A MEASURING CHANNEL

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 possible parameters, can be any physical and / or chemical measurable properties that qualify or quantify the flow of the fluid medium. In particular, these 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, such as those 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, which is permeable to the flowing fluid medium. 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 located upstream of the heating element and the other temperature sensor located downstream of the heating element.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 of the fluid medium.

[0003] Hot-film air mass meters are typically designed as plug-in sensors that can be permanently or interchangeably inserted into a flow pipe. This flow pipe could, for example, be the intake manifold of an internal combustion engine.

[0004] In this process, a partial flow of the medium passes through at least one main channel provided in the hot-film air mass meter. A bypass channel is formed between the inlet and outlet of the main channel. Specifically, 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. This curved section then transitions into a section in which a sensor chip is arranged. This latter section constitutes the actual measuring channel in which the sensor chip is located.

[0005] In conventional hot-film air mass meters of the type described, a sensor carrier with the sensor chip attached or embedded on it typically protrudes into the measuring channel. For example, the sensor chip can be glued into or onto the sensor carrier. The sensor carrier can form a unit with a metal base plate, onto which electronics, a control and evaluation circuit (e.g., with a circuit board, especially a printed circuit board), can also be glued. Alternatively, 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, for example, by bonding. The resulting electronic module can then be glued into a sensor housing, and the entire plug-in sensor can be sealed with covers.

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

[0007] Despite the numerous advantages of existing sensors, there is still room for improvement. For example, determining qualitative air properties currently requires additional sensors, which entails significant extra costs.

[0008] From US patent 2016 / 016 1313 A1, an air mass meter for the intake air mass flow of an internal combustion engine is known, which, in addition to a first sensor element for detecting the flowing air mass, has a second sensor element for detecting the moisture contained in the intake air.

[0009] US Patent 5,708,585 discloses a sensor device for detecting the concentration of combustible elements in the exhaust gas of an internal combustion engine.

[0010] From US patent 2009 / 0188235 A1, an exhaust aftertreatment system with a sensor for detecting the oxygen concentration in the exhaust gas is known.

[0011] From EP 2 245 570 A1 a system for controlling vehicle emissions in a geographical area is known, wherein the system comprises an engine control system for a vehicle with one engine and a control system.

[0012] From US patent 2018 / 0101997 A1, a control system is known which is designed to detect hydrocarbon emissions from a first vehicle by means of a sensor in the air intake tract of a second vehicle. Disclosure of the invention

[0013] 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 detection of additional qualitative properties of the fluid medium or its qualitative composition.

[0014] A sensor according to the invention 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, comprises a sensor housing, in particular a plug-in sensor inserted or insertable into a flow tube, in which the measuring channel is formed, at least one first sensor chip arranged in the measuring channel for determining the parameter of the fluid medium, and an electronic module. The electronic module comprises a control and / or evaluation circuit. The sensor further comprises a second sensor chip for determining a qualitative composition of the fluid medium. The second sensor chip is connected to the control and / or evaluation circuit.

[0015] This allows a single sensor to measure not only the parameters of the fluid flowing through the measuring channel, but also the quality of the fluid, thus eliminating the need for additional sensors to determine this property. The sensor is therefore functionally enhanced.

[0016] Within the scope of the present invention, the qualitative composition of the fluid medium is understood to mean the quantity and type of the components of the fluid medium.

[0017] The electronic module comprises a printed circuit board (PCB) on which the control and / or evaluation circuitry is located, and on which the second sensor chip is also located. This allows the second sensor chip to be integrated compactly into the electronic module.

[0018] In the context of the present invention, a printed circuit board (PCB) is generally understood to be a substantially plate-shaped element that can also be used as a carrier for electronic structures, such as conductive traces, terminal contacts, or the like, and preferably also has one or more such structures. In principle, at least slight deviations from the plate shape are also conceivable and are included in the definition. The PCB can, for example, be made of a plastic material and / or a ceramic material, such as an epoxy resin, in particular a fiber-reinforced epoxy resin. In particular, the PCB can, for example, be designed as a printed circuit board (PCB) with conductive traces, in particular printed conductive traces.

[0019] The second sensor chip is a micro-electromechanical sensor chip. Therefore, the second sensor chip is comparatively small and requires little installation space.

[0020] Within the scope of the present invention, a micro-electro-mechanical sensor chip is understood to be a sensor chip whose components have minute dimensions in the range of 1 micrometer and interact as a system. Such a microsystem consists of one or more sensor elements and control electronics arranged on the chip. The size of the individual components is in the range of a few micrometers.

[0021] The second sensor chip has a substrate that is at least partially made of a semiconductor material, such as silicon. The substrate carries the components of the sensor chip.

[0022] According to the invention, the qualitative composition comprises at least a proportion of a gas component in the fluid medium and / or a proportion 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 oxide. Alternatively or additionally, the solid is at least one element selected from the group consisting of particles, soot, dust, and fine dust.

[0023] In this further development, the sensor housing features an electronics compartment in which the electronic module is located. This allows the electronic module to be protected within the sensor housing.

[0024] According to the invention, the sensor is designed for connection 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, the measurement signal of which can be processed by the control unit for controlling and / or regulating the air conditioning system. Thus, it is possible to control or regulate the air conditioning system using the data obtained by the second sensor chip.

[0025] In a further development, the sensor is configured for connection to a motor vehicle control unit, wherein the motor vehicle has an internal combustion engine and an exhaust aftertreatment device for treating the exhaust gas of the internal combustion engine, wherein the second sensor chip is configured to output a measurement signal, the measurement signal of which can be processed by the control unit for controlling and / or regulating the exhaust aftertreatment device. Thus, it is possible to control or regulate the exhaust aftertreatment device using the data obtained by the second sensor chip.

[0026] Furthermore, a sensor system is proposed comprising an electronic data processing device and a plurality of sensors according to the aforementioned specifications. The sensors are wirelessly connected to the electronic data processing device, with the second sensor chip configured to output a measurement signal. This signal can be processed by the electronic data processing device to determine information about ambient air conditions. This allows the data from the respective sensors to be centrally acquired, enabling the determination of information about the quality of the fluid medium at various locations. For example, if the sensors are installed in several motor vehicles, information about the air quality in the vicinity of the vehicles can be obtained and processed centrally by a remote processing device.In this way, traffic can be controlled in a targeted manner to improve air quality.

[0027] Within the scope 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 arrangement, whereby, for example, local irregularities such as turbulence can be disregarded. In particular, the main flow direction can thus be understood as the locally averaged transport direction of the flowing fluid medium. The main flow direction can therefore refer either to the flow direction at the location of the sensor arrangement itself or to the flow direction in the channel within the sensor housing, such as at the location of the sensor carrier or the sensor chip, whereby these two main flow directions may differ. Within the scope of the present invention, it is therefore always specified to which location the main flow direction refers.Unless otherwise specified, the main flow direction refers to the location of the sensor arrangement.

[0028] Within the scope of the present invention, the sensor carrier can be configured wholly or partially as a circuit carrier, in particular as a printed circuit board, or can be part of a circuit carrier, in particular a printed circuit board. For example, the circuit carrier, in particular the printed circuit board, can have a projection which forms the sensor carrier and which projects into the channel, for example the measuring channel of a hot-film air mass meter. The remaining part of the circuit carrier, in particular the printed circuit board, can be housed, for example, in an electronics compartment, in a housing of the sensor arrangement, or in a plug-in probe of the sensor arrangement. Short description of the drawings

[0029] 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.

[0030] They show: Figure 1 is a perspective view of a sensor, Figure 2 is an enlarged view of an electronic module of the sensor, Figure 3 is a representation of the transmission of signals in a motor vehicle, Figure 4 is an example of signal processing in a control unit of a motor vehicle, and Figure 5 is an example of a sensor system. Embodiments of the invention

[0031] Figure 1Figure 1 shows a perspective view of a sensor 10 for determining a parameter of a fluid medium. The sensor 10 is designed as a hot-film air mass meter and comprises a sensor housing 12 designed as a plug-in sensor, which can be inserted, for example, into a flow pipe, in particular an intake manifold of an internal combustion engine. The sensor housing 12 has a housing body 14, a measuring channel cover 16, an electronics compartment 18, and an electronics compartment cover 20 for closing the electronics compartment 18. A channel structure 22 is formed in the housing body 16. The channel structure 22 has a main channel 24, which is located in a main flow outlet 26, for example, on the underside 28, as shown in the illustration in Figure 1. Figure 1The sensor housing 12 opens into a bypass or measuring channel 30 branching off from the main channel 24, which opens into a bypass or measuring channel outlet 32, which can be separate or integrated. A representative quantity of the fluid medium can flow through the channel structure 22 via an inlet opening 34, which, in the installed state, points in the opposite direction to the main flow direction 36 of the fluid medium at the location of the sensor housing 12.

[0032] Figure 2Figure 1 shows an enlarged view of an electronic module 38 of the sensor 10. In an inserted state of the electronic module 38, a sensor carrier 40 projects into the measuring channel 30. A first sensor chip 42 is embedded in this sensor carrier 40 such that a micromechanical sensor membrane 44, designed as the sensor area of ​​the first sensor chip 42, is permeable to the fluid medium. The sensor carrier 40 and the first sensor chip 42 are components of the electronic module 38. The electronic module 38 further comprises a curved base plate 46 and a printed circuit board 48, for example, glued to it, with a control and / or evaluation circuit 50. The control and / or evaluation circuit 50 is arranged on the printed 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 electrical connections 52, which are implemented here as wire bonds. The resulting electronic module 38 is inserted into the electronics compartment 18 of the housing body 14 – itself an integral part of the sensor housing 12 – for example, by gluing. The sensor carrier 40 projects into the channel structure 22. The electronics compartment 18 is then closed by the electronics compartment cover 20.

[0033] Sensor 10 further comprises a second sensor chip 54 for determining the qualitative composition of the fluid medium. The qualitative composition includes at least one proportion of a gas component in the fluid medium and / or one proportion of a solid in the fluid medium. The gas component is at least one compound selected from the group consisting of carbon dioxide, carbon monoxide, ozone, sulfur dioxide, and nitrogen oxide. The solid is at least one element selected from the group consisting of particles, soot, dust, and fine dust.

[0034] The second sensor chip 54 is a micro-electromechanical sensor chip. In particular, the second sensor chip 54 has a substrate that is at least partially made of a semiconductor material. The semiconductor material is, for example, silicon. Alternatively, the semiconductor material is gallium arsenide. The substrate can alternatively 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.

[0035] Figure 3Figure 10 shows a representation of signal transmission in a motor vehicle 56. For example, sensor 10 is located in the intake manifold of an internal combustion engine 58 of the motor vehicle 56. The motor vehicle 56 has a control unit 60. Sensor 10 is connected to the control unit 60 so that data or signals can be exchanged between them. The motor vehicle 56 also has an air conditioning system 62. The second sensor chip 54 is designed to output a measurement signal. This measurement signal can be processed by the control unit 60 to control and / or regulate the air conditioning system 62. For example, a measurement signal is acquired by means of the second sensor chip 54 and output to the control and / or evaluation circuit 50, where a qualitative composition of the fluid medium is determined or calculated. The control and / or evaluation circuit 50, in turn, outputs the measurement signal to the control unit 60 via a predetermined channel 64.Channel 64 is a digital interface for communication, such as SENT (Single Edge Nibble Transmission). The control unit 60 processes the measurement signal and outputs it to the control unit of the air conditioning system 62 via a CAN bus 66. In this way, it can be determined whether and how much fresh air and / or recirculated air the air conditioning system 62 should supply into the interior of the vehicle 56.

[0036] The motor vehicle 56 can alternatively or additionally have an exhaust aftertreatment device 68 for treating the exhaust gas of the combustion engine 58. The measurement signal from the second sensor chip 54 can be processed by the control unit 60 for controlling and / or regulating the exhaust aftertreatment device 68 in the manner described above. For example, the measurement signal is acquired by means of the second sensor chip 54 and output to the control and / or evaluation circuit 50, where a qualitative composition of the fluid medium is determined or calculated. The control and / or evaluation circuit 50, in turn, outputs the measurement signal to the control unit 60 via the predetermined channel 64. The control unit 60 processes the measurement signal and outputs it to the control or regulation of the exhaust aftertreatment device 68 via the CAN bus 66. In this way, the measurement signal can, for example, be considered as an input variable in nitrogen oxide or soot models.

[0037] Figure 4 Figure 1 shows an example of signal processing in a control unit 60 of a motor vehicle 56. In step S10, the control unit 60 acquires a raw signal 70. The raw signal 70 can be supplied by the second sensor chip 54 or the first sensor chip 42. In step S12, a signal transformation takes place. The transformed signal is subjected to low-pass filtering in step S14. After low-pass filtering, a summation calculation is performed in step S16. Finally, in step S18, a moving average is calculated, whereby a trigger signal is supplied from step S20 after each half-path change. The moving average thus obtained is then used as an input for other control systems in the motor vehicle.

[0038] Figure 5Figure 1 shows an example of a sensor system 72. The sensor system 72 comprises an electronic data processing device 74 and a plurality of sensors 10 according to the embodiment 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 that can be processed by the electronic data processing device 74 to determine information about ambient air conditions. For example, the sensors 10 are mounted in motor vehicles 56. The measurement signals are wirelessly transmitted from the control units 60 of the motor vehicles 56 to the data processing device 74. Using further data from the motor vehicles 56, such as position data, the information about air quality can thus be assigned to the positions of the motor vehicles 56.This allows information about air quality to be collected at various locations, which in turn can be used to control traffic.

Claims

1. Sensor (10) for determining at least one parameter of a fluid medium flowing through a measurement channel (30), wherein the flowing fluid medium is an intake air mass flow of an internal combustion engine, wherein the sensor (10) has a sensor housing (12), in particular a plug-in sensor, which is inserted or can be inserted into a flow tube and in which the measurement channel (30) is formed, at least one first sensor chip (42) which is arranged in the measurement channel (30) and is intended to determine the parameter of the fluid medium, and an electronics module (38), wherein the electronics module (38) has a control and / or evaluation circuit (50), wherein the sensor (10) has a second sensor chip (54) for determining a qualitative composition of the fluid medium, wherein the second sensor chip (54) is connected to the control and / or evaluation circuit (50), wherein the qualitative composition comprises at least a portion of a gas component in the fluid medium and / or a portion of a solid in the fluid medium, wherein the electronics module (38) has a printed circuit board (48), on which the control and / or evaluation circuit (50) and the second sensor chip (54) are arranged, characterized in that the gas component is at least one compound selected from the group consisting of carbon dioxide, carbon monoxide, ozone, sulphur dioxide and nitrogen oxide and / or the solid is at least one element selected from the group consisting of particles, soot, dust and particulate matter, in that the second sensor chip (54) is a micro-electro-mechanical sensor chip, wherein the second sensor chip (54) has a substrate which is at least partially produced from a semiconductor material, in particular silicon, wherein the sensor (10) is designed for connection to a control unit (60) of a motor vehicle (56), wherein the motor vehicle (56) has an air conditioning system (62), wherein the second sensor chip (54) is designed to output a measurement signal, wherein the measurement signal can be processed by the control unit (60) in order to control and / or regulate the air conditioning system.

2. 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. Sensor (10) according to either of Claims 1 and 2, wherein the sensor (10) is designed for connection to a control unit (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 the aftertreatment of exhaust gas of the internal combustion engine (58), wherein the second sensor chip (54) is designed to output a measurement signal, wherein the measurement signal can be processed by the control unit (60) in order to control and / or regulate the exhaust gas aftertreatment device (68).

4. Sensor system (72) comprising an electronic data processing device (74) and a plurality of sensors (10) according to one of Claims 1 to 3, wherein the sensors (10) are wirelessly connected to the electronic data processing device (74), wherein the second sensor chip (54) is designed to output a measurement signal, wherein the measurement signal can be processed by the electronic data processing device (74) in order to determine information about an air condition in the vicinity of the sensors (10).