Electronic control unit for operating a sensor for sensing at least one property of a measurement gas

Abstract

The invention relates to an electronic control unit (10) for operating a sensor (100) for sensing at least one property of a measurement gas in a measurement gas chamber, in particular for sensing a component of a gas component in the measurement gas or a temperature of the measurement gas, wherein the sensor (100) has a sensor element (102), wherein the sensor element (102) has a solid electrolyte (104), at least one pump cell (106) and at least one Nernst cell (108). The control unit (10) has a control and evaluation circuit (12) and a microcontroller (20). The microcontroller (20) is connected to the control and evaluation circuit (12). The microcontroller (20) also has a Nernst voltage regulator (22) for regulating a Nernst voltage (U N ) of the Nernst cell (108).

Description

Background Technology

[0001] Various sensors and methods for sensing at least one characteristic of a measuring gas in a measuring gas chamber are known from the prior art. In principle, this can be any physical and / or chemical characteristic of the measuring gas, wherein one or more characteristics can be sensed. The invention is described below with particular reference to the qualitative and / or quantitative sensing of the gas components of the measuring gas, and especially with reference to the sensing of the oxygen component in a portion of the measuring gas. The oxygen component can be sensed, for example, in the form of partial pressure and / or percentage. However, alternatively or additionally, other characteristics of the measuring gas, such as temperature, can also be sensed.

[0002] Sensors with ceramic sensor elements are known from the prior art, the ceramic sensor elements being based on the use of defined electrolytic properties of solids, i.e., the ion-conducting properties of the solids. These solids can be, in particular, ceramic solid electrolytes, such as zirconium dioxide (ZrO2), especially yttrium-stabilized zirconium dioxide (YSZ) and scandium-doped zirconium dioxide (ScSZ), which can contain small amounts of alumina (Al2O3) and / or silicon dioxide (SiO2).

[0003] This type of sensor can be configured, for example, as a so-called λ probe, as known from Konrad Reif (ed.): Sensoren im Kraftfahrzeug, 2010, 1st edition, pp. 160-165. With the aid of a broadband λ probe, especially a planar broadband λ probe, it is possible to determine, for example, the oxygen concentration in the exhaust gas over a wide range and thereby infer the air-fuel ratio in the combustion chamber. The air coefficient λ describes this air-fuel ratio.

[0004] A broadband lambda probe measures either the oxygen concentration or the concentration of a reducing agent in the gas. Information on the residual oxygen in the exhaust gas is crucial for optimizing the operation of an internal combustion engine. To operate the broadband lambda probe, it is attached to an analytical processing module (ASIC) specifically created for this purpose on the controller. The ASIC's primary task is to adjust the Nernst voltage measured between the reference electrode and the internal pump electrode to a target value, typically 450 mV. The setting parameter used to adjust the Nernst voltage is the pump current driven by the ASIC between the external and internal pump electrodes. If the Nernst voltage is close to its target value, the required pump current is used to measure the oxygen concentration in the exhaust gas. Therefore, accurate determination of the pump current is a prerequisite for accurately determining the O2 concentration in the exhaust gas.

[0005] The pump current source receives the desired pump current value digitally from the Nernst voltage regulator, which should then be driven by a probe. A current source that drives a continuous, adjustable current is also known as a DAC current source.

[0006] Despite the advantages of sensors and methods for operating them known in the prior art, there is still potential for improvement. Different broadband λ probes constitute very different regulation segments (Regelstrecken), each requiring a Nernst voltage regulator to be adapted to it. Here, not only the regulator parameters but also the regulator structure need to be adjusted. Currently, the Nernst voltage regulator is fixed in the hardware of the ASIC. Changing the regulator structure means modifying the ASIC by manufacturing a new mask. Regulator parameters can only be adjusted via software. Adjustments to the regulator structure, including resolution, can only be achieved through hardware modifications. This type of modification is laborious and expensive. Summary of the Invention

[0007] Therefore, an electronic control unit is proposed for operating a sensor for sensing at least one characteristic of a measuring gas in a measuring gas chamber. This electronic control unit at least largely avoids the drawbacks of known manipulation and analysis processing circuits, and enables rapid and cost-effective adjustment of the regulator structure of the Nernst voltage regulator, for example, to adapt to different probes.

[0008] An electronic control unit according to the invention for operating a sensor for sensing at least one characteristic of a measuring gas in a measuring gas chamber includes a manipulation and analysis processing circuit and a microcontroller. The sensor has a sensor element for sensing the characteristic of the measuring gas, wherein the sensor element has a solid electrolyte, at least one pump battery, and at least one Nernst battery. The microcontroller is connected to the analysis processing circuit. The microcontroller also has a Nernst voltage regulator for regulating the Nernst voltage of the Nernst battery.

[0009] Accordingly, the transfer of Nernst voltage regulators from control and analysis processing circuits (e.g., ASICs) to microcontrollers is proposed. Here, changes to the regulation structure and word width can be implemented cost-effectively and quickly without hardware modifications. This allows for resource savings in ASICs. An arithmetic logic unit (ALU) is unnecessary in ASICs because the microcontroller's resources are used for regulator calculations. Furthermore, a simpler overall ASIC structure can be implemented.

[0010] In particular, the Nernst voltage regulator can be implemented in the microcontroller's software. Here, changes to the regulation structure and word width can be cost-effectively and quickly achieved through software adjustments, without requiring hardware modifications.

[0011] The control and analysis processing circuit can be an ASIC. An ASIC (Application-Specific Integrated Circuit) is an electronic circuit implemented as an integrated switching circuit. Therefore, the function of an ASIC cannot be changed, resulting in lower manufacturing costs despite high initial costs. This allows for a reduction in the computational requirements within the ASIC, making the computational demands smaller. Consequently, the required silicon area for the arithmetic unit in the microcontroller is significantly smaller and therefore more cost-effective, as the semiconductor process of the microcontroller can be optimized for digital structures.

[0012] The input parameter of the Nernst voltage regulator can be the Nernst voltage of the Nernst battery, and the output parameter can be the pump current used to pump the battery. Therefore, the regulation algorithm is calculated in the microcontroller. The regulator's output value is available in the microcontroller with very little latency. This value is the setting parameter for the pump current source, which is the main signal of the width λ probe. The λ signal is thus calculated, and this λ signal is therefore available in the microcontroller with little or no latency. Therefore, precise λ regulation can be achieved even under high driving dynamics, which provides particular advantage in real-world driving emissions.

[0013] The electronic control unit may also include an analog-to-digital converter configured to sense the Nernst voltage of the Nernst cell. Therefore, the input parameters for the Nernst voltage regulator can be represented as digital parameters in a simple manner.

[0014] The control and analysis processing circuit can have an analog-to-digital converter, wherein the microcontroller has a data interface through which the sensed Nernst voltage can be transmitted. In this embodiment, the analog-to-digital converter is located in the interface ASIC. The voltage value is sensed in the ASIC and transmitted to the microcontroller via the data interface.

[0015] Alternatively, the microcontroller can have an analog-to-digital converter. Therefore, the Nernst voltage value is sensed directly within the microcontroller, and thus, the Nernst voltage value is directly available within the microcontroller.

[0016] The output parameters of the Nernst voltage regulator indicate the oxygen content in the measured gas. Therefore, the regulator's output value is directly available in the microcontroller. This value corresponds to the oxygen content in the measured gas (e.g., exhaust gas) and is required for λ adjustment. If this value is available with a lower latency, the desired λ value can still be adjusted even under high driving dynamics, thus enabling lower emissions.

[0017] The control and analysis processing circuit can have a digital-to-analog converter, wherein the output parameters of the Nernst voltage regulator can be provided to the digital-to-analog converter. Therefore, the digital output parameters can be converted into analog parameters in order to adjust the pump current on the pump current source.

[0018] The regulator architecture of a Nernst voltage regulator can be modified by adjusting the source code. If the regulator is implemented in a microcontroller, it can be adapted to new requirements at any time by adjusting the code text. Therefore, the regulator architecture can be adapted to new requirements, such as different word widths or different regulator types.

[0019] Within the framework of this invention, a solid electrolyte body should be understood as a subject or object possessing electrolytic properties, i.e., ion-conducting properties (e.g., the property of conducting oxygen ions). This is particularly likely to be a ceramic solid electrolyte. For example, a solid electrolyte body can have stable zirconium dioxide and / or scandium-stabilized zirconium dioxide. A solid electrolyte body can also be composed of multiple solid electrolyte layers. Here, a layer should be understood as a uniform mass extending in a plane at a certain height, located above, below, or between other elements.

[0020] Within the framework of this invention, an electrode is generally understood as an element capable of contacting a solid electrolyte, such that a current can be maintained or a voltage measured through the solid electrolyte and the electrode. Accordingly, the electrode can include elements at which ions can be inserted into and / or extracted from the solid electrolyte. Typically, the electrode comprises a noble metal electrode, which can be applied to the solid electrolyte, for example, as a cermet electrode, or otherwise connected to the solid electrolyte. A typical electrode material is a platinum cermet electrode. However, other noble metals, such as gold or palladium, can also be used in principle.

[0021] Within the framework of this invention, the Nernst cell should be understood as an electrochemical measuring cell that uses a solid electrolyte as a membrane between two electrodes. Here, the solid electrolyte utilizes the following property: it can electrolytically transport ions of the gas to be measured (e.g., oxygen ions) from one electrode to the other from a defined temperature, thereby generating a so-called Nernst voltage. This property allows the determination of the difference in partial pressure of the gas on different sides of the membrane. In the case of a λ probe, one side of the membrane is exposed to the gas being measured, while the other side serves as a reference.

[0022] Within the framework of this invention, the pump cell should be understood as an electrochemical cell in which, on the one hand, the content of a component (e.g., oxygen) of the measuring gas in the measuring gap is determined by the measuring gas acting via a diffusion channel, and on the other hand, the content is influenced by the current of the pump cell. Depending on the polarity, the measuring gas is pumped from the measuring gas side of the solid electrolyte membrane into or out of the measuring gap by the pump current. Here, the pump current is adjusted by an external regulator so that the λ value in the measuring gas accurately compensates for the measuring gas flow through the diffusion channel, and the measuring gas in the measuring gap is constantly maintained at a predetermined value, for example, λ = 1. For example, when the voltage on the Nernst cell is 0.45V, a λ value of 1 is always given in the measuring gap. The pump current pumps measuring gas ions into the measuring gas in the measuring gap in the case of a rich gas mixture, and pumps the measuring gas ions out of the measuring gas in the case of a poor gas mixture.

[0023] Within the framework of this invention, a microcontroller should be understood as a semiconductor chip that includes a processor and also peripheral functions. In many cases, working memory and program memory are also partially or completely located on the same chip. A microcontroller is a single-chip computer system. For many microcontrollers, the terms "System-on-a-Chip" or SoC are also used. Modern microcontrollers typically also have complex peripheral functions, such as CAN (Controller Area Network) interfaces, LIN (Local Interconnect Network) interfaces, and I... 2 Microcontrollers may include an Inter-Integrated Circuit (ICI) interface, an SPI (Serial Peripheral Interface) interface, a serial or Ethernet interface, a PWM output, an LCD controller and LCD driver, and an analog-to-digital converter (Analog-Digital-Umsetzer). Some microcontrollers also have programmable digital and / or analog or mixed-function blocks.

[0024] Within the framework of this invention, the control and analysis processing circuit should be understood as an electronic circuit, especially an integrated circuit, which is suitable for analyzing and processing the measurement signals of a sensor element or processing the measurement signals for analysis and processing, and controlling the sensor element based on the obtained control signals during operation of the sensor element.

[0025] Within the framework of this invention, a multiplexer should be understood as a selection circuit in analog and digital electronic devices, by means of which one input signal can be selected from multiple input signals and connected to the output. A multiplexer is similar to a rotary switch, which is adjusted electronically rather than manually. The difference from a relay is that the connection is not implemented mechanically, but (nowadays) through integrated semiconductor circuitry. Attached Figure Description

[0026] Other optional details and features of the invention will become apparent from the following description of preferred embodiments, which are schematically illustrated in the accompanying drawings.

[0027] The attached diagram shows:

[0028] Figure 1 An electronic control unit according to a first embodiment of the present invention, and

[0029] Figure 2 An electronic control unit according to a second embodiment of the present invention. Detailed Implementation

[0030] Figure 1 An electronic control unit 10 according to a first embodiment of the present invention is shown. The electronic control unit 10 is configured to operate a sensor 100 for sensing at least one characteristic of a measuring gas in a measuring gas chamber, particularly for sensing the component content of a gas in the measuring gas or the temperature of the measuring gas. The sensor 100 has a sensor element 102. Figure 1 The sensor element 102 shown can be used to examine the physical and / or chemical properties of the measured gas, wherein one or more properties can be sensed. The invention is described below with particular reference to the qualitative and / or quantitative sensing of the gas components of the measured gas, and especially with reference to the sensing of the oxygen component in the measured gas. The oxygen component can be sensed, for example, in the form of partial pressure and / or percentage. However, in principle, other types of gas components, such as nitrogen oxides, hydrocarbons, and / or hydrogen, can also be sensed. However, alternatively and / or additionally, other properties of the measured gas can also be sensed. The invention is particularly applicable in the field of automotive technology; therefore, the measuring gas chamber can particularly be the exhaust pipe of an internal combustion engine, and the measuring gas can particularly be exhaust gas.

[0031] Sensor element 102 includes a solid electrolyte body or solid electrolyte 104, a pump cell 106, and a Nernst cell 108. The sensor element is electrically contactable via pin 110. Sensor 100 is configured only as a broadband λ probe, so that its operation and more detailed construction can be referenced to the prior art described above, and in particular to Konrad Reif (ed.): Sensoren im Kraftfahrzeug, 1st edition, 2010, pp. 160-165.

[0032] The electronic control unit 10 includes a control and analysis processing circuit 12. The control and analysis processing circuit 12 is an ASIC. The control and analysis processing circuit 12 can be connected to pin 110 of the sensor element 102. For example, the control and analysis processing circuit 12 includes a multiplexer 14 that is electrically contacted with pin 110. The control and analysis processing circuit 12 also includes an analog-to-digital converter 16 connected to the multiplexer. The analog-to-digital converter 16 is configured for sensing the Nernst voltage U of the Nernst cell 108. N The control and analysis processing circuit 12 also includes a digital-to-analog converter 18, which is connected to the output of the multiplexer 14 or to at least one of the pins 110.

[0033] The electronic control unit 10 also includes a microcontroller 20. The microcontroller 20 is connected to, or communicates with, the control and analysis processing circuitry 12. The microcontroller 20 includes a Nernst voltage regulator 22 for regulating the Nernst voltage of the Nernst battery 108. The Nernst voltage regulator 22 is implemented in the microcontroller's software 24. Figure 1 As shown, the input parameter of the Nernst voltage regulator is the Nernst voltage U of the Nernst cell 108. N The output parameter of the Nernst voltage regulator 108 is the pump current I used for the pump battery 106. P For example, further in Figure 1 As can be seen, the output parameter of the Nernst voltage regulator 22 indicates the oxygen content in the measured gas, for example, in the form of a Lambda value λ. The output parameter of the Nernst voltage regulator 22 can be provided to the digital-to-analog converter 18. The microcontroller 20 has a data interface 26, through which the Nernst voltage U can be... N The measurement signal is transmitted to the microcontroller 20. Since the Nernst voltage regulator 222 is not implemented in the ASIC, but in the microcontroller 20 or its software 24, the regulator structure of the Nernst voltage regulator 22 can be changed by adjusting the source code of the Nernst voltage regulator 22.

[0034] Figure 2 An electronic control unit 10 according to a second embodiment of the present invention is shown. The differences from the first embodiment are described below only; identical or similar components are given the same reference numerals. In the electronic control unit 10 of the second embodiment, the microcontroller 20 has an analog-to-digital converter 16. Therefore, the Nernst voltage value is sensed directly in the microcontroller 20, and thus, the Nernst voltage value is directly available in the microcontroller 20.

[0035] The electronic control unit according to the present invention is indirectly verifiable. For example, the dimensions of the digital section of the ASIC can be analyzed. The Nernst voltage regulator on the ASIC requires a digital section with a defined size. If the digital section on the ASIC is too small, the Nernst voltage regulator in the microcontroller needs to be positioned. In the second embodiment, the Nernst voltage is transmitted digitally at a correspondingly high frequency in a manner similar to that of the microcontroller. In both embodiments, the value I is adjusted... P The corresponding high-frequency transmission is used for transmission.

Claims

1. An electronic control unit (10) for operating a sensor (100) for sensing at least one characteristic of a measuring gas in a measuring gas chamber, wherein, The sensor (100) has a sensor element (102), wherein the sensor element (102) has a solid electrolyte (104), at least one pump battery (106) and at least one Nernst battery (108), wherein the control unit (10) has a control and analysis processing circuit (12) and a microcontroller (20), wherein the microcontroller (20) is connected to the control and analysis processing circuit (12), wherein the microcontroller (20) also has a Nernst voltage regulator (22), the Nernst voltage regulator being used to regulate the Nernst voltage (U) of the Nernst battery (108). N ), wherein the control and analysis processing circuit (12) is an ASIC, and wherein the control and analysis processing circuit (12) has a digital-to-analog converter (18), wherein the output parameter of the Nernst voltage regulator (22) is the pump current (I) for the pump battery (106). P And can be provided to the digital-to-analog converter (18).

2. The electronic control unit (10) according to claim 1, wherein, The Nernst voltage regulator (22) is implemented in the software (24) of the microcontroller (20).

3. The electronic control unit (10) according to claim 1 or 2, wherein, The input parameter of the Nernst voltage regulator (22) is the Nernst voltage (U) of the Nernst cell (108). N ).

4. The electronic control unit (10) according to claim 1 or 2, further comprising an analog-to-digital converter (16) configured to sense the Nernst voltage (UN) of the Nernst cell (108). N ).

5. The electronic control unit (10) according to claim 4, wherein, The control and analysis processing circuit (12) has an analog-to-digital converter (16), wherein the microcontroller (20) has a data interface (26), wherein the sensed Nernst voltage (U) can be transmitted via the data interface (26). N The data is transmitted to the microcontroller (20).

6. The electronic control unit (10) according to claim 4, wherein, The microcontroller (20) has the analog-to-digital converter (16).

7. The electronic control unit (10) according to claim 1 or 2, wherein, The output parameter of the Nernst voltage regulator (22) is the oxygen content in the measured gas.

8. The electronic control unit (10) according to claim 1 or 2, wherein, The regulator structure of the Nernst voltage regulator (22) can be changed by adjusting the source code of the Nernst voltage regulator (22).

9. The electronic control unit (10) according to claim 1, wherein, The sensor is used to sense the composition of the gas components in the measured gas or the temperature of the measured gas.

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