A high temperature exhaust gas sensor chip crack detection circuit and device

Abstract

The present invention discloses a high-temperature exhaust gas sensor chip crack detection circuit and device thereof, which are used for crack detection of oxygen sensor chips. The detection circuit includes: a sensor chip, which is used to monitor the oxygen concentration of automobile exhaust; a current detection unit, which is used to detect the current value of the oxygen sensor; a power supply unit, which is used to provide power; a crack detection unit, which is configured with a crack detection solution, which is used to detect the current on-off state between the pins of the sensor chip, and determine whether the sensor chip has cracks according to the current on-off state. The present invention provides a simple crack detection system and method to determine whether cracks appear inside the oxygen sensor chip. The present invention is simple to operate and low in cost, and can quickly confirm whether cracks appear inside the oxygen sensor chip. It can be used to analyze failed oxygen sensor chips and detect oxygen sensor chips before leaving the factory.

Description

Technical Field

[0001] The present invention relates to a detection circuit and a device thereof, and in particular to a high-temperature exhaust gas sensor chip crack detection circuit and a device thereof. Background Art

[0002] Wide-band oxygen, narrow-band oxygen, and NOX sensors are key core components of automobile powertrains. The role of oxygen sensors in automobiles is to monitor the oxygen concentration in automobile exhaust and input the monitoring signal to the engine ECU. The engine ECU adjusts the air-fuel ratio of the engine according to the monitoring signal fed back by the oxygen sensor to keep the air-fuel ratio in the best state, thereby achieving the purpose of energy saving and emission reduction. Each passenger car in the National VI stage needs to be equipped with two oxygen sensors, namely, a wide-band oxygen sensor and a narrow-band oxygen sensor. The wide-band oxygen sensor is a six-wire sensor, and the λ detection range of the wide-band oxygen sensor is 0.65≤λ≤1.7. The narrow-band oxygen sensor is a four-wire sensor, and the λ detection range of the narrow-band oxygen sensor is near λ=1. According to the different installation positions, it can be divided into front oxygen sensors and rear oxygen sensors. The wide-band oxygen sensor is installed before the three-way catalytic converter and is also called the front oxygen sensor. The narrow-band oxygen sensor is installed after the three-way catalytic converter and is also called the rear oxygen sensor. λ is the excess air coefficient, λ=actual air consumption\theoretical air requirement.

[0003] Oxygen sensors may fail during use. Common failure modes include sensor poisoning, sensor carbon deposits, sensor chip cracking, heater short circuit, etc.

[0004] (1) Cracking of the sensor chip: The main material of the oxygen sensor chip is YSZ ceramic. When the oxygen sensor is working, the surface temperature of the chip is around 700-800°C. When the condensed water in the exhaust pipe or the water vapor contained in the exhaust gas contacts the oxygen sensor chip, the local temperature will drop sharply, causing the ceramic to crack.

[0005] (2) Heater short circuit: The heating electrode of the oxygen sensor is a platinum electrode. When the oxygen sensor is working, the temperature of the heating electrode exceeds 800°C. Excessive heating voltage or high temperature may cause the platinum electrode of the heater to short circuit, making it impossible to heat the sensor and causing the oxygen sensor to lose signal.

[0006] Cracking of the sensor chip and short circuit of the heater will cause the oxygen sensor to lose its signal. For these two failure modes, the chip surface can be observed under a microscope, or the internal structure of the chip can be observed using a high-precision CT scan to detect the cause of the chip failure. The detection equipment for these two methods is complex to operate, the detection cost is high, and it takes a long time. Summary of the invention

[0007] The purpose of the present invention is to provide a high-temperature exhaust gas sensor chip crack detection circuit and device thereof, which can quickly detect cracks in the sensor chip and solve the shortcomings of the prior art.

[0008] The present invention provides the following scheme:

[0009] A high-temperature exhaust gas sensor chip crack detection circuit is used to detect cracks in an oxygen sensor chip, comprising:

[0010] Sensor chips for monitoring oxygen concentration in automobile exhaust;

[0011] A current detection unit, used to detect the current value of the oxygen sensor;

[0012] A power supply unit, used for providing power;

[0013] The crack detection unit is configured with a crack detection solution and is used to detect the on-off state of the current between the pins of the sensor chip, and determine whether the sensor chip has a crack according to the on-off state of the current.

[0014] Furthermore, the oxygen sensor includes a wide-range oxygen sensor and a narrow-range oxygen sensor, the wide-range sensor is specifically a six-wire sensor, and the narrow-range oxygen sensor is specifically a four-wire sensor.

[0015] Furthermore, the pins of the six-wire sensor include: a pump current pin, a virtual ground pin, a heating pin, a power heating pin, an adjustment resistor pin, and a Nernst voltage pin.

[0016] Furthermore, the current detection unit is a digital multimeter, the power supply unit is a voltage-stabilized power supply, the digital multimeter, the voltage-stabilized power supply and the oxygen sensor chip are connected in series in sequence, and the oxygen sensor chip is immersed in the crack detection solution of the crack detection unit.

[0017] Furthermore, the crack detection solution includes: alcohol, methanol, n-butanol or salt water.

[0018] Furthermore, the concentration of the alcohol is in the range of 75%-95%, and the concentration of the salt water is in the range of 0.5%-25%.

[0019] Furthermore, the oxygen sensor chip is a ceramic chip.

[0020] Furthermore, the ceramic chip is a yttrium-stabilized zirconia ceramic chip.

[0021] Furthermore, the heating electrode of the oxygen sensor chip is a platinum electrode.

[0022] A high-temperature exhaust gas sensor chip crack detection device is provided with the high-temperature exhaust gas sensor chip crack detection circuit.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The present invention sets a crack detection module in the crack detection circuit of the sensor chip, immerses the sensor chip in the solution in the detection module, and determines whether the sensor chip has cracks according to the on-off state of the current in the detection circuit. The present invention provides a simple crack detection system (circuit) and method for judging whether cracks appear inside the oxygen sensor chip. The operation is simple and the cost is low, and whether cracks appear inside the oxygen sensor chip can be quickly confirmed. The system can be used to analyze failed oxygen sensor chips and detect oxygen sensor chips before leaving the factory. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 It is the principle block diagram of the high-temperature exhaust gas sensor chip crack detection circuit.

[0027] Figure 2 This is the assembly effect diagram of the high-temperature exhaust gas sensor chip crack detection circuit.

[0028] Figure 3 This is the schematic diagram of the wide-band oxygen sensor.

[0029] Figure 4 This is the schematic diagram of a narrow-band oxygen sensor. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] like Figure 1 and Figure 2 The high temperature exhaust gas sensor chip crack detection circuit shown in the figure is used to detect cracks in the oxygen sensor chip, and includes:

[0032] Sensor chips for monitoring oxygen concentration in automobile exhaust;

[0033] Specifically, the oxygen sensor includes a wide-range oxygen sensor and a narrow-range oxygen sensor. The wide-range sensor is specifically a six-wire sensor, and the narrow-range oxygen sensor is specifically a four-wire sensor.

[0034] Exemplarily, the pins of the six-wire sensor include: a pump current pin, a virtual ground pin, a heating pin, a power heating pin, an adjustment resistor pin, and a Nernst voltage pin - the Nernst potential is used to describe the diffusion potential formed by a certain ion between the A and B systems.

[0035] Exemplarily, the oxygen sensor chip is a ceramic chip, the ceramic chip is a YSZ ceramic, that is, a yttrium-stabilized zirconia ceramic chip, and the heating electrode of the oxygen sensor chip is a platinum electrode.

[0036] A current detection unit, used to detect the current value of the oxygen sensor;

[0037] Specifically, the current detection unit is a digital multimeter, the power supply unit is a voltage-stabilized power supply, the digital multimeter, the voltage-stabilized power supply and the oxygen sensor chip are connected in series in sequence, and the oxygen sensor chip is immersed in the crack detection solution of the crack detection unit.

[0038] Exemplarily, the crack detection solution includes: alcohol, methanol, n-butanol or brine, the concentration of the alcohol ranges from 75% to 95%, and the concentration of the brine ranges from 0.5% to 25%.

[0039] A power supply unit, used for providing power;

[0040] The crack detection unit is configured with a crack detection solution and is used to detect the on-off state of the current between the pins of the sensor chip, and determine whether the sensor chip has a crack according to the on-off state of the current.

[0041] Based on the high-temperature exhaust gas sensor chip crack detection circuit, the present invention also provides a corresponding high-temperature exhaust gas sensor chip crack detection device, in which a high-temperature exhaust gas sensor chip crack detection circuit is provided.

[0042] It is worth noting that, although only some basic functional modules (units) are disclosed in the embodiments of the present invention, it does not mean that the composition of the present system is limited to the above basic functional modules (units). On the contrary, what the present embodiment wants to express is that on the basis of the above basic functional modules (units), those skilled in the art can arbitrarily add one or more functional modules in combination with the prior art to form an infinite number of embodiments or technical solutions. In other words, the present circuit is open rather than closed. Just because the present embodiment only discloses individual basic functional modules (units), it cannot be considered that the protection scope of the claims of the present invention is limited to the disclosed basic functional modules. At the same time, for the convenience of description, the above devices are described by functions and are divided into various units and modules. Of course, when implementing the present invention, the functions of each unit and module can be implemented in the same or one or more software and / or hardware.

[0043] The implementation methods of the system described above are merely illustrative, for example, the various functional modules, units or subsystems in the system may or may not be physically separated, or may or may not be physical units, that is, they may be located in the same place, or they may be distributed to multiple different systems and their subsystems or modules. Those skilled in the art may select some or all of the functional modules, units or subsystems according to actual needs to achieve the purpose of the embodiments of the present invention, and those of ordinary skill in the art may understand and implement the above-mentioned situations without creative work.

[0044] like Figure 3 and Figure 4 As shown, the present invention provides an implementation method of a high-temperature exhaust gas sensor chip crack detection circuit and a device thereof in a specific application scenario:

[0045] In the background technology, wide-band oxygen sensors and narrow-band oxygen sensors have been mentioned, and oxygen sensors may fail during use. Sensor chip cracking and heater short circuiting can cause the oxygen sensor to lose signal. For these two failure modes, the chip surface can be observed with a microscope, or the internal structure of the chip can be observed with a high-precision CT to detect the cause of chip failure. However, whether it is observed with a microscope or with a CT machine, special equipment and sites are required, the detection cost is high and the detection process is complicated. Compared with the above two methods, this embodiment uses a simple crack detection system and method to determine whether cracks appear inside the oxygen sensor chip. This embodiment is simple to operate and low in cost, and can quickly confirm whether cracks appear inside the oxygen sensor chip. It can be used to analyze failed oxygen sensor chips and detect oxygen sensor chips before leaving the factory.

[0046] In this embodiment, the signal terminal pin or the heater terminal pin of the oxygen sensor is connected to a voltage-stabilized power supply, a digital multimeter is connected in series in the circuit, a voltage value is set on the voltage-stabilized power supply, the current reading of the digital multimeter is recorded at this time, the voltage value on the voltage-stabilized power supply is kept unchanged, the oxygen sensor chip is immersed in alcohol, methanol, n-butanol, brine or other solutions, and the digital multimeter reading is recorded again.

[0047] When cracks appear in the oxygen sensor chip, the cracks in the chip will be filled with air, the sensor pins will be open, and the current is only at the nanoampere level. Alcohol, methanol, n-butanol, brine or other solutions have good wettability for YSZ ceramics. When the oxygen sensor chip is immersed in alcohol, methanol, n-butanol, brine or other solutions, alcohol, methanol, n-butanol, brine or other solutions will fill the middle of the crack. For example, the conductivity of 95% alcohol solution at room temperature is 1.35×10-3μs / cm. The conductivity of alcohol, methanol, n-butanol, brine or other solutions is greater than the air in the crack. The current can be observed to increase rapidly on the digital multimeter, and the current can reach the microampere level or milliampere level. The change in current can be used to determine whether cracks appear inside the oxygen sensor chip. This method can be used to easily and quickly determine whether cracks appear inside the oxygen sensor chip.

[0048] The following table describes the test results:

[0049] Table 1 95% alcohol test results

[0050]

[0051] Use a regulated power supply to load 20V voltage to the heater pin of the oxygen sensor, connect a digital multimeter in series in the circuit, record the reading of the digital multimeter as I1, immerse the oxygen sensor chip in 95% alcohol solution, record the reading of the digital multimeter as I2, and the results are shown in Table 1.

[0052] Table 2 10% salt water test results

[0053]

[0054] Use a voltage regulator to apply 20V voltage to the heater pin of the oxygen sensor. Connect a digital multimeter in series in the circuit and record the reading of the digital multimeter as I1. Immerse the oxygen sensor chip in 10% salt water and record the reading of the digital multimeter as I2. The results are shown in Table 2

[0055] Table 3 n-Butanol detection results

[0056]

[0057] Use a regulated power supply to load 20V voltage to the heater pin of the oxygen sensor, connect a digital multimeter in series in the circuit, record the reading of the digital multimeter as I1, immerse the oxygen sensor chip in n-butanol, record the reading of the digital multimeter as I2, and the results are shown in Table 3.

[0058] From the above text description and table, it can be seen that in this embodiment, the oxygen sensor chip is immersed in alcohol, methanol, n-butanol, brine or other solutions, and whether cracks occur is determined by the change in current. Alcohol concentration range: 95% to 75%, brine concentration range: 25% to 0.5%, a simple device consisting of a digital multimeter and a voltage-stabilized power supply is used to determine whether the sensor chip has cracks by the change in current. If cracks occur in the oxygen sensor chip, the current is only at the nanoampere level. When the oxygen sensor chip is immersed in the detection solution of the crack detection unit, since the conductivity of the detection solution (alcohol, methanol, n-butanol, brine or other solutions is greater than the air in the crack, the current reading displayed by the digital multimeter will quickly increase to the microampere level or milliampere level, and an order of magnitude change has occurred. Therefore, the change in the current reading can determine whether the cause of the fault is from the oxygen sensor chip or from other places.

[0059] Those skilled in the art will appreciate that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by those skilled in the art in the field to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined.

[0060] It should be noted that certain words are used in this specification and claims to refer to specific components. Those skilled in the art should understand that different manufacturers and producers may use different terms to refer to the same component. This specification and claims do not use the difference in terms as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction.

[0061] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0062] In addition, those skilled in the art will appreciate that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present invention and form different embodiments. For example, any one of the embodiments claimed in the claims can be used in any combination in the embodiments of the present invention.

[0063] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0064] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0065] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any way. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features. Throughout the specification, the same reference numerals indicate the same elements.

[0066] Those skilled in the art will appreciate that the modules in the devices in the embodiments can be adaptively changed and set in one or more devices different from the embodiments. The modules or units or components in the embodiments can be combined into one module or unit or component, and in addition they can be divided into multiple submodules or subunits or subcomponents. Except that at least some of such features and / or processes or units are mutually exclusive, all features disclosed in this specification (including corresponding claims, abstracts and drawings) and all processes or units of any method or device disclosed in this manner can be combined in any combination. Unless otherwise explicitly stated, each feature disclosed in this specification (including corresponding claims, abstracts and drawings) can be replaced by an alternative feature that provides the same, equivalent or similar purpose.

[0067] In addition, to simplify the description and discussion, and in order not to obscure one or more embodiments of the present specification, known power / ground connections to integrated circuit (IC) chips and other components may or may not be shown in the provided figures. In addition, the device may be shown in the form of a block diagram so as to avoid obscuring one or more embodiments of the present specification, and this also takes into account the fact that the details of the implementation of these block diagram devices are highly dependent on the platform on which one or more embodiments of the present specification will be implemented (i.e., these details should be fully within the scope of understanding of those skilled in the art). Where specific details (e.g., circuits) are set forth to describe exemplary embodiments of the present disclosure, it is apparent to those skilled in the art that one or more embodiments of the present specification may be implemented without these specific details or with variations in these specific details. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-temperature exhaust gas sensor chip crack detection circuit, used for crack detection of oxygen sensor chips, characterized in that: include: Sensor chips for monitoring oxygen concentration in automobile exhaust; A current detection unit, used to detect the current value of the oxygen sensor; A power supply unit, used for providing power; A crack detection unit, configured with a crack detection solution, for detecting the on-off state of the current between the pins of the sensor chip, and determining whether the sensor chip has a crack according to the on-off state of the current; Wherein, the signal end pin of the oxygen sensor or the heater end pin is connected to the power supply unit; Wherein, the oxygen sensor comprises a narrow-band oxygen sensor, and the narrow-band oxygen sensor is specifically a four-wire sensor; Wherein, the crack detection solution includes: alcohol, methanol, n-butanol or salt water; The concentration of the alcohol is in the range of 75% to 95%, and the concentration of the salt water is in the range of 0.5% to 25%.

2. The high temperature exhaust gas sensor chip crack detection circuit according to claim 1, characterized in that: The current detection unit is a digital multimeter, the power supply unit is a voltage-stabilized power supply, the digital multimeter, the voltage-stabilized power supply and the oxygen sensor chip are sequentially connected in series, and the oxygen sensor chip is immersed in the crack detection solution of the crack detection unit.

3. The high temperature exhaust gas sensor chip crack detection circuit according to claim 1, characterized in that: The oxygen sensor chip is a ceramic chip.

4. The high temperature exhaust gas sensor chip crack detection circuit according to claim 3, characterized in that: The ceramic chip is a yttrium-stabilized zirconia ceramic chip.

5. The high temperature exhaust gas sensor chip crack detection circuit according to claim 1, characterized in that: The heating electrode of the oxygen sensor chip is a platinum electrode.

6. A high-temperature exhaust gas sensor chip crack detection device, characterized in that: The high-temperature exhaust gas sensor chip crack detection device is provided with a high-temperature exhaust gas sensor chip crack detection circuit according to any one of claims 1 to 5.

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