Gas flow sensor chip and gas flow sensor

Abstract

The embodiment of the present specification relates to the technical field of flow sensor, and provides a kind of gas flow sensor chip, comprising: circuit substrate, heating resistance and temperature measurement resistance;The gas flow sensor chip has first working mode for measuring gas flow;And, the second working mode for the temperature measurement resistance is powered, and the temperature measurement resistance generates heat;Wherein, the working current of the temperature measurement resistance in the second working mode is greater than the working current of the temperature measurement resistance in the first working mode.Through the above technical method, by the temperature measurement resistance is powered, and the temperature measurement resistance is in the second working mode of heat generation, so as to reduce the pollution degree of the gas flow sensor chip in the flowing medium to a certain extent by the pollutant, so as to improve the measurement accuracy of the gas flow sensor chip.

Description

TECHNICAL FIELD

[0001] Embodiments of the present specification relate to the technical field of flow sensor, and particularly relate to a gas flow sensor chip and a gas flow sensor. BACKGROUND

[0002] With the development of technology, flow sensors are widely used in industrial production. Among them, the flow sensor can measure the flow of gas, liquid, steam and other media. With the development of technology, MEMS technology has developed, and the thermal gas flow sensor based on MEMS technology has the characteristics of fast response, low power consumption, small size, high integration, etc., so that the thermal gas flow sensor based on MEMS technology has been greatly developed. In the measurement process of the thermal gas flow sensor, pollutants follow the flowing medium to the flow sensor chip, and after a long period of deposition, when the pollutants reach a certain degree, the pollutants will change the heat conduction value on the surface of the gas sensor chip and the micro flow field of the upstream flow direction of the gas sensor, thereby affecting the measurement signal. Therefore, the pollutants deposited on the gas sensor chip will reduce the measurement accuracy of the gas sensor chip.

[0003] Therefore, the gas sensor chip in the prior art may have the technical problem that the measurement accuracy is reduced due to pollutants. SUMMARY

[0004] Therefore, the gas sensor chip in the prior art may have the technical problem that the measurement accuracy is reduced due to pollutants.

[0005] In order to achieve the above-mentioned purpose, one embodiment of the present specification provides a gas flow sensor chip, comprising: a circuit substrate, a heating resistor and a temperature measuring resistor; the gas flow sensor chip has a first working mode for measuring gas flow; and a second working mode for energizing the temperature measuring resistor to make the temperature measuring resistor heat; wherein the working current of the temperature measuring resistor in the second working mode is greater than the working current of the temperature measuring resistor in the first working mode.

[0006] One embodiment of the present specification provides a gas flow sensor, which comprises the above-mentioned gas flow sensor chip.

[0007] The gas flow sensor chip provided by the present specification has the beneficial effect that, compared with the prior art, the measuring accuracy of the gas flow sensor chip is improved to some extent by the heating of the temperature measuring resistor to block the deposition of pollutants in the flowing medium on the gas flow sensor chip. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 A structural schematic diagram of a gas flow sensor chip is provided for an embodiment of the present specification.

[0009] Figure 2 A structural schematic diagram of a gas flow sensor chip is provided for an embodiment of the present specification.

[0010] Figure 3 A structural schematic diagram of a gas flow sensor chip is provided for an embodiment of the present specification.

[0011] Figure 4 A structural schematic diagram of a gas flow sensor chip is provided for an embodiment of the present specification. DETAILED DESCRIPTION

[0012] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present specification will be described clearly and completely in conjunction with the accompanying drawings of the embodiments of the present specification. Obviously, the described embodiments are only some of the embodiments of the present specification, not all the embodiments. Based on the embodiments in the present specification, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0013] Please refer to Figure 1 An embodiment of the present specification provides a gas flow sensor chip 100, which comprises a circuit substrate 110, a heating resistor 120 and a temperature measuring resistor 130; the gas flow sensor chip 110 has a first working mode for measuring gas flow; and a second working mode in which the temperature measuring resistor 130 is powered to heat the temperature measuring resistor 130; wherein the working current of the temperature measuring resistor 130 in the second working mode is greater than the working current of the temperature measuring resistor 130 in the first working mode.

[0014] In the embodiment, the temperature measuring resistors 130 are symmetrically arranged on both sides of the heating resistor 120 in the gas flow sensor chip 100. When the flowing medium is static, the temperatures measured by the temperature measuring resistors 130 equidistant from the heating resistor 120 are the same. When the flowing medium flows on the surface of the gas flow sensor chip, the temperatures measured by the temperature measuring resistors 130 are different, and the gas flow sensor chip 100 measures the mass flow of the flowing medium through the temperature difference. The temperature measuring resistors 130 can have a first working mode for measuring the gas flow. By energizing the temperature measuring resistors 130, the temperature measuring resistors 130 are in a second working mode, i.e., the temperature measuring resistors 130 generate heat, so that the flowing medium has a temperature gradient. The pollutants in the flowing medium move from the high-temperature part to the low-temperature part due to the higher kinetic energy of the gas molecules in the high-temperature part than that of the gas molecules in the low-temperature part, so that the pollutants in the flowing medium move to the low-temperature part, reduce the pollution of the flowing medium on the surface of the gas flow sensor chip, and further improve the measurement accuracy of the gas flow sensor chip.

[0015] In the embodiment, the working mode of the temperature measuring resistors 130 is controlled by adjusting the working current for energizing the temperature measuring resistors 130. When the working current reaches a certain value, the temperature measuring resistors 130 are in a first working mode, i.e., a working mode for measuring the gas flow. When the working current of the temperature measuring resistors 130 reaches a certain current value and is greater than the current value of the working current of the temperature measuring resistors 130 in the first working mode, the temperature measuring resistors 130 are in a second working mode, i.e., an anti-pollution working mode. The heat generated by the temperature measuring resistors 130 blocks the pollutants in the flowing medium from adhering to the surface of the gas sensor chip 100. The greater the working current of the temperature measuring resistors 130, the greater the heat generated by the temperature measuring resistors 130.

[0016] In some embodiments, the temperature measuring resistors 130 can be resistors with adjustable resistance values. The working mode of the temperature measuring resistors 130 can be controlled by adjusting the resistance values of the temperature measuring resistors 130 through a controller. When the resistance value of the temperature measuring resistors 130 reaches a certain value, the temperature measuring resistors 130 are in a first working mode. When the resistance value of the temperature measuring resistors reaches a certain resistance value and is greater than the resistance value of the temperature measuring resistors 130 in the first working mode, the temperature measuring resistors 130 are in a second working mode.

[0017] In some embodiments, the temperature measuring resistor 130 on the gas flow sensor chip 100 includes a first resistor and a second resistor, and the heating resistor 120 is in an inactive state when the temperature measuring resistor 130 is in the second working mode. Of course, it can also be that the first resistor close to the main flow direction of the flowing medium is in the second working mode, and the heating resistor 120 and the second resistor away from the main flow direction of the flowing medium are in the inactive state. To some extent, the power consumption is reduced.

[0018] Please refer to Figure 2 In some embodiments, when the gas flow sensor chip 100 includes at least an outer resistor pair 131 and an inner resistor pair 132, the outer resistor pair 131 is in the second working mode, the inner resistor pair 132 is in the first working mode, and the heating resistor 120 is in the working mode.

[0019] In some embodiments, the gas flow sensor 100 is an instrument that converts the temperature, pressure, etc. signals of the fluid into flow. There are many types of gas flow sensors 100, such as throttling type, volumetric type, vortex type, electromagnetic type, thermal type, and ultrasonic type. Among them, the thermal type gas flow sensor 100 can use the principle of thermodynamics to detect the flow of gas medium in the flow channel, and has good precision and repeatability.

[0020] In some embodiments, the first working mode can refer to the working mode of the temperature measuring resistor 130 for measuring the temperature for measuring the flow.

[0021] In some embodiments, the second working mode can refer to the working mode of the temperature measuring resistor 130 for resisting the deposition of pollutants in the flowing medium to the gas flow sensor chip 100. The heat generated by the temperature measuring resistor 130 in the second working mode to some extent makes the pollutants in the flowing medium away.

[0022] In some embodiments, the working current can be the current that makes the temperature measuring resistor 130 work. Specifically, for example, the working current of the temperature measuring resistor 130 in the first working mode is 5mA, and the working current in the second working mode is 10mA. When the current of the temperature measuring resistor 130 reaches 5mA, the temperature measuring resistor 130 is in the first working mode. In order to make the temperature measuring resistor 130 in the second working mode, 10mA working current needs to be passed through the temperature measuring resistor 130.

[0023] In some embodiments, the heating resistor 120 can be a resistor that generates heat with an isothermal gradient for the sensing area of the gas sensor chip 100 together with the temperature measuring resistor 130.

[0024] In some embodiments, the working current of the temperature measuring resistor 130 is alternately converted between the working currents corresponding to the first working mode and the second working mode.

[0025] In the present embodiment, the gas flow sensor chip 100 is electrically connected with a controller, which adjusts the working current of the temperature measuring resistor 130, so as to control the working mode of the temperature measuring resistor 130. The controller controls the working current of the temperature measuring resistor 130 to be converted between the working currents corresponding to the first working mode and the second working mode, so as to convert the temperature measuring resistor 130 between the first working mode and the second working mode, so that the gas flow sensor chip 100 can measure the flow of the flowing medium and reduce the adhesion of pollutants on the gas flow sensor chip 100 by the heat generated by the temperature measuring resistor 130, thereby improving the measurement accuracy of the gas flow sensor chip 100.

[0026] Please refer to Figure 2 In some embodiments, the temperature measuring resistor 130 on the gas flow sensor chip 100 includes at least an outer resistor pair 131 and an inner resistor pair 132, which together measure the flow of the flowing medium, so as to improve the measurement accuracy of the gas flow sensor chip 100. By supplying power to the outer resistor pair 131, the outer resistor 131 is in the second working mode, while the inner resistor pair 132 of the gas flow sensor chip 100 is in the first working mode for measuring the flow of the flowing medium. The gas flow sensor chip 100 can generate heat by the outer resistor 131 while measuring the flow of the flowing medium, so as to reduce the adhesion of pollutants in the flowing medium on the surface of the gas flow sensor chip 100, thereby improving the measurement accuracy of the gas sensor chip 100. Of course, the controller can also control the current to alternately place the inner resistor pair 132 and the outer resistor pair 131 in the working state, i.e., when the inner resistor pair 132 is in the first working mode, the outer resistor pair 131 is in the non-working state, and when the outer resistor pair 131 is in the second working mode, the inner resistor pair 132 is in the non-working state. The inner resistor pair 132 and the outer resistor pair 131 are alternately placed in the working state. By controlling the controller, when the inner resistor pair 132 is working, the outer resistor pair 131 is not working, so as to avoid the influence of the heat generated by the outer resistor pair 131 in the second working mode on the measurement of the flow of the flowing medium by the inner resistor pair 132, thereby improving the measurement accuracy of the gas flow sensor chip 100.

[0027] In some embodiments, the time interval of the alternately conversion is set; wherein the value of the time interval does not affect the measurement of the gas flow by the sensor chip.

[0028] In the present embodiment, the controller sets the time interval value T1 between the first working mode and the second working mode of the temperature measuring resistor 130, and of course the second working mode and the first working mode of the temperature measuring resistor 130. According to the time interval values T1 and T2, the temperature measuring resistor 130 is switched between the first working mode and the second working mode, wherein T1 is the time interval value between the end of the first working mode and the beginning of the second working mode of the temperature measuring resistor 130, and T2 is the time interval value between the end of the second working mode and the beginning of the first working mode of the temperature measuring resistor 130. T1 and T2 can be fixed values, and of course the values of T1 and T2 cannot affect the normal operation of the flow measurement circuit. After judging the degree of pollution of the gas sensor chip, T1 can be set according to the degree of pollution. The higher the degree of pollution, the smaller the T1 set, and the more time the temperature measuring resistor 130 is in the second working state, effectively preventing the pollutants in the flowing medium from adhering to the gas sensor chip 100. The greater the T2 set in a certain range, the more effectively the heat generated by the temperature measuring resistor 130 in the second working mode affects the measurement of the first working mode, and of course it cannot affect the normal operation of the flow measurement circuit. The controller can calculate the degree of pollution of the gas sensor chip 100 according to the measured data, and set T1 and T2 according to the degree of pollution of the gas sensor chip 100 and the flow rate of the flowing medium. By adjusting T1 and T2, the frequency of the temperature measuring resistor 130 in the second working mode can be reduced in the early stage of use of the gas sensor chip 100, and the temperature measuring resistor 130 and the heating resistor 120 in the first mode can be in an inactive state without affecting the measurement, thereby reducing the operating power consumption of the gas flow sensor chip 100 to a certain extent. The time interval T2 ensures the measurement of the flowing medium, and avoids the heat generated by the temperature measuring resistor 130 in the second working mode from affecting the measurement of the flow, thereby improving the measurement accuracy.

[0029] Please refer to Figure 3 In some embodiments, the flowing medium has a main flow direction 140: the temperature measuring resistor 131 in the second working mode is in front of the temperature measuring resistor 132 in the first working mode.

[0030] In the embodiment, the flow medium can have multiple flow directions, one of which is a main flow direction 140. The temperature sensing resistor 130 includes at least one pair of inner resistor pair 132 in the first working mode and one pair of temperature sensing resistor pair 131 in the second working mode. In the main flow direction, one of the temperature sensing resistor 133 in the temperature sensing resistor pair 131 is in front of the temperature sensing resistor pair 132 in the inner resistor pair 132 close to the main flow direction, that is, the flow medium first flows through the temperature sensing resistor 133 in the second working mode and then flows through one of the inner resistor pair 132. The temperature sensing resistor 133 in the second working mode effectively blocks the pollutants in the flow medium from adhering to the gas flow sensor chip 100, to some extent, reduces the degree of pollutants adhering to the gas sensor chip 100, thereby improving the detection accuracy.

[0031] In some embodiments, the flow medium can refer to a gas with multiple flow directions and a main flow direction. Specifically, for example, oxygen.

[0032] Please refer to Figure 3 In some embodiments, the distance between the temperature sensing resistor 133 in the second working mode and the temperature sensing resistor 132 in the first working mode is 1-2 mm.

[0033] In the embodiment, the heat generated by the temperature sensing resistor 133 in the second working mode can cover the range of 1-2 mm distance between the temperature sensing resistor 133 and the temperature sensing resistor 132 in the first working mode. When the distance between the temperature sensing resistor 133 in the second working mode and the temperature sensing resistor 132 in the first working mode is 1-2 mm, the temperature sensing resistor 133 in the second working mode can reduce the pollutants in the flow medium from adhering to the gas sensor chip 100 by heating. Of course, the heat generated by the temperature sensing resistor 133 in the second working mode is not enough to affect the measured value of the flow medium flow. Specifically, for example, when the distance between the temperature sensing resistor 133 in the second working mode and the temperature sensing resistor 132 in the first working mode is less than 1 mm, the heat measured by the temperature sensing resistor 132 includes the heat generated by the temperature sensing resistor 133 in the second working mode, thereby affecting the measured value of the flow medium flow. When the distance between the temperature sensing resistor 133 in the second working mode and the temperature sensing resistor 132 in the first working mode is greater than 2 mm, the pollutants in the flow medium cannot be effectively blocked from adhering to the gas sensor chip 100, thereby the gas sensor chip 100 cannot be well protected from being contaminated by the pollutants in the flow medium.

[0034] Please refer to Figure 4In some embodiments, on the gas flow sensor chip 100, at least the heating resistor 121, the heating resistor 122 and six temperature measuring resistors can be included. The six temperature measuring resistors can be the temperature measuring resistor 134, the temperature measuring resistor 135, the temperature measuring resistor 136, the temperature measuring resistor 137, the temperature measuring resistor 138 and the temperature measuring resistor 139. The temperature measuring resistor 135 and the temperature measuring resistor 136, the temperature measuring resistor 134, the temperature measuring resistor 137 and the heating resistor 121 constitute the flow measurement working area 1, wherein the temperature measuring resistor 135 and the temperature measuring resistor 136 constitute the temperature measuring resistor pair in the flow measurement first working area 141, and the temperature measuring resistor 134 and the temperature measuring resistor 137 constitute the temperature measuring resistor pair outside the flow measurement first working area 141. The temperature measuring resistor 136 and the temperature measuring resistor 137, the temperature measuring resistor 138, the temperature measuring resistor 139 and the heating resistor 122 constitute the flow measurement second working area 142, wherein the temperature measuring resistor 137 and the temperature measuring resistor 138 constitute the temperature measuring resistor pair in the flow measurement second working area 142, and the temperature measuring resistor 136 and the temperature measuring resistor 139 constitute the temperature measuring resistor pair outside the flow measurement second working area 142.

[0035] In some embodiments, the flow measurement first working area 141 can be in the direction of the incoming flow of the flowing medium. There is a certain regular deviation in the flow measurement between the flow measurement first working area 141 and the flow measurement second working area 142, which indicates that the cold-hot flowing body convection boundary of the flow measurement first working area 141 is polluted, and the flow measurement of the flow measurement second working area 142 is dominant, thereby improving the accuracy of the measured flow. In some embodiments, after the flow measurement first working area 141 is seriously polluted after working for a period of time, the controller can control the flow measurement first working area 141 to work or not to work, and control the flow measurement second working area 142 to work, so that the gas flow sensor chip 100 can work uninterruptedly, thereby prolonging the stable operation time and the calibration period of the gas flow sensor chip 100.

[0036] In some embodiments, at least part of the sensor chip is a suspended structure.

[0037] In the embodiment, the part of the gas flow sensor chip 100 is set as a suspended structure. Specifically, for example, the suspended structure is a thin film suspended structure. By setting the part of the gas flow sensor chip 100 as a suspended structure, the area of the sensor chip 100 in the main flow direction 140 of the flow medium is reduced, and the area where the pollutants in the flow medium can adhere is reduced, thereby avoiding the formation of pollutants on the gas sensor chip to a certain extent. Of course, the main flow direction of the flow medium can have multiple selection directions, which improves the applicability of the gas flow sensor chip 100. By reducing the structure of the gas flow sensor chip 100, the local micro flow field on the surface of the gas flow sensor chip 100 is reduced, and the measurement accuracy of the gas flow sensor chip 100 is further improved.

[0038] Please refer to Figure 2 In some embodiments, the temperature measuring resistor 130 at least includes an outer resistor pair 131 and an inner resistor pair 132; wherein the outer resistor pair 131 and the inner resistor pair 132 are respectively arranged on both sides of the heating resistor 120; when the comparison value of the output signal of the outer resistor pair 131 and the output signal of the inner resistor pair 132 is greater than or equal to a pollution threshold value, the outer resistor pair 131 is passed through electricity, and the working mode of the outer resistor pair 131 is the second working mode.

[0039] In the embodiment, the temperature measuring resistor 130 is arranged on both sides of the heating resistor 120, and the outer resistor pair 131 and the inner resistor pair 132 alternately measure the flow of the flow medium. By comparing the flow measurement signals of the outer resistor pair 131 and the inner resistor pair 132 in adjacent measurement periods, a comparison value is obtained, and the comparison value is compared with a pollution threshold value. When the comparison value is greater than or equal to the pollution threshold value, the controller controls the outer resistor 131 to pass through electricity, so that the working current of the outer resistor 131 reaches the working current of the second working mode, so that the outer resistor 131 is in the second working mode, and the outer resistor 131 generates heat to a certain extent. Block the pollutants on the gas flow sensor chip 100, thereby improving the measurement accuracy. Specifically, for example, the flow measurement signals of the outer resistor pair 131 and the inner resistor pair 132 in adjacent measurement periods are U1 and U2 respectively, and the comparison value A can be calculated by difference operation (U1-U2). When A is greater than or equal to B, the controller controls the outer resistor pair 131 to pass through electricity, and the outer resistor pair 131 is in the second working mode of heat generation. The comparison value can also be calculated by division operation (U1 / U2). Of course, the calculation method of the comparison value needs to be consistent with the method used when calibrating the pollution threshold value.

[0040] In some embodiments, the temperature measuring resistor 130 includes at least an outer resistor pair 131 and an inner resistor pair 132; wherein the outer resistor pair 131 and the inner resistor pair 132 are symmetric resistor pairs; in the case that the differential voltage of the outer resistor pair 131 and the differential voltage of the inner resistor pair 132 are different, the outer resistor pair 131 is powered, and the working current of the outer resistor pair 131 is increased, so that the working mode of the outer resistor pair 131 is the second working mode.

[0041] In the present embodiment, the outer resistor pair 131 and the inner resistor pair 132 are symmetric resistor pairs respectively, and are distributed on both sides of the heating resistor 120. The temperature measuring resistor 130 is measured and calculated by difference respectively, and two differential voltages are obtained. When the differential voltages of the outer resistor pair 131 and the inner resistor pair 132 are different, it is judged that the gas flow sensor chip 100 has been contaminated by the pollutants in the flowing medium, and a method for judging whether the gas flow sensor chip 100 is contaminated is provided. At this time, the controller controls the outer resistor pair 131 to be powered, and the working current of the outer resistor pair 131 is increased, so that the working current of the outer resistor pair 131 reaches the working current of the second working mode, so that the outer resistor pair 131 generates heat to block the pollutants in the flowing medium from continuing to contaminate the gas flow sensor chip 100, and the measurement accuracy of the gas flow sensor chip 100 is improved.

[0042] In some embodiments, the temperature measuring resistor 130 inputs a zero point voltage; when the temperature measuring resistor 130 has an output voltage, the temperature measuring resistor 130 is powered, so that the temperature measuring resistor 130 starts the second working mode.

[0043] In the present embodiment, the controller controls the temperature measuring resistor 130 to input a zero point voltage, and when it is detected that the temperature measuring resistor 130 has an output voltage, it is judged that the gas flow sensor chip 100 is contaminated, and a method for judging whether the gas flow sensor chip 100 is contaminated is provided. At this time, the controller controls the temperature measuring resistor 130 to be powered, and the working current of the temperature measuring resistor 130 reaches the working current corresponding to the second working mode, so that the temperature measuring resistor 130 generates heat to further block the pollutants in the flowing medium from continuing to adhere to the gas flow sensor chip 100.

[0044] One embodiment of the present specification provides a gas flow sensor, which includes the gas flow sensor chip 100 described in any of the above.

[0045] Any technical features of the above embodiments can be combined, and for the sake of brevity, not all possible combinations are described, however, any combination of the technical features should be considered as within the scope of the present specification.

[0046] The above description is merely illustrative of the application and is not intended to limit the scope of the application. Any modification, equivalent replacement, and the like which do not depart from the spirit and principle of the application are intended to be included in the scope of the application.

Claims

1. A gas flow sensor chip, characterized by, The gas flow sensor chip comprises: a circuit substrate, a heating resistor and a temperature measuring resistor; the gas flow sensor chip has a first working mode for measuring gas flow; and a second working mode for energizing the temperature measuring resistor to make the temperature measuring resistor generate heat; wherein the working current of the temperature measuring resistor in the second working mode is greater than the working current of the temperature measuring resistor in the first working mode; the temperature measuring resistor comprises at least an outer resistor pair and an inner resistor pair; wherein the outer resistor pair and the inner resistor pair are respectively arranged on both sides of the heating resistor; when the comparison value of the output signal of the outer resistor pair and the output signal of the inner resistor pair is greater than or equal to a pollution threshold value, the outer resistor pair is energized, and the working mode of the outer resistor pair is the second working mode.

2. The sensor chip according to claim 1, characterized in that The flowing medium has a main flow direction; the temperature measuring resistor in the second working mode is upstream of the temperature measuring resistor in the first working mode in the main flow direction.

3. The sensor chip according to claim 2, characterized in that The distance between the temperature measuring resistor in the second working mode and the temperature measuring resistor in the first working mode is 1-2 mm.

4. The sensor chip of claim 1, wherein, At least part of the sensor chip is a suspended structure.

5. A gas flow sensor, characterized by The gas flow sensor chip comprises any one of claims 1-4.

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