CN211348306U - MEMS constant-temperature differential thermal film type anemometer - Google Patents
MEMS constant-temperature differential thermal film type anemometer Download PDFInfo
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- CN211348306U CN211348306U CN202020219146.6U CN202020219146U CN211348306U CN 211348306 U CN211348306 U CN 211348306U CN 202020219146 U CN202020219146 U CN 202020219146U CN 211348306 U CN211348306 U CN 211348306U
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Abstract
The utility model relates to a poor hot diaphragm type anemograph of MEMS constant temperature, include: the differential amplification circuit is provided with a heating resistor Rj, and the resistance value of the heating resistor Rj changes along with the temperature change; the constant temperature difference control circuit is connected with the differential amplification circuit, and is provided with two temperature measuring resistors Rc1 and Rc2, wherein the temperature measuring resistor Rc1 and the temperature measuring resistor Rc2 are symmetrically arranged at two ends of the heating resistor Rj; the acquisition circuit is connected with the constant temperature difference control circuit, and the difference amplification circuit can convert the wind speed signal into a voltage signal; and the power supply circuit is respectively connected with the differential amplification circuit, the constant temperature difference control circuit and the acquisition circuit. The technical scheme of the utility model, owing to adopted MEMS technology to make hotfilm and temperature compensation part, the temperature sensitivity of assurance these three kinds of resistances that can be fine is unanimous, and has added some insulating film inside it for heat loss on the heating resistor is less, thereby just can heat appointed temperature point with less power.
Description
Technical Field
The utility model relates to an anemorumetric sensor technical field especially relates to a poor hot diaphragm type anemograph of MEMS constant temperature.
Background
Wind speed is an important parameter in the fields of life, scientific research, measurement and the like, but some existing wind speed measuring equipment has the defects of large size, high price, high power consumption and the like. The sensor of the constant temperature difference hot film type anemometer consists of a heating resistor, three compensating resistors and two temperature measuring resistors. The method is realized by utilizing a heat exchange principle, a heating resistor is heated by a heat source, when gas flows in and heat exchange occurs, a thermal field around the heating resistor changes, the change of the thermal field is generally converted by a processing circuit and can be mapped into corresponding voltage change or current change to be collected by a CPU, and then a certain functional relation exists between the changes and the gas inflow speed. The gas velocity is generally measured by measuring the temperature difference between the upstream resistance and the downstream resistance near the heating resistance and then converting into a corresponding voltage difference to react the gas velocity, or by measuring the magnitude of the heating current by controlling the temperature difference between the heating resistance and the fluid to be constant.
SUMMERY OF THE UTILITY MODEL
The present invention aims at least solving one of the technical problems existing in the prior art or the related art.
Therefore, an object of the present invention is to provide a MEMS constant temperature differential thermal film type anemometer, which can reduce the heating power, reduce the heat capacity of the device, reduce the heat conduction of the device, reduce the heat dissipation, and improve the sensitivity of the sensor.
In order to achieve the above object, the present invention provides a MEMS constant temperature differential thermal film type anemometer, including: the differential amplification circuit is provided with a heating resistor Rj, and the resistance value of the heating resistor Rj changes along with the temperature change; the constant temperature difference control circuit is connected with the differential amplification circuit, and is provided with two temperature measuring resistors Rc1 and Rc2, wherein the temperature measuring resistor Rc1 and the temperature measuring resistor Rc2 are symmetrically arranged at two ends of the heating resistor Rj; the acquisition circuit is connected with the constant temperature difference control circuit and can convert the voltage signal of the constant temperature difference control circuit into a wind speed signal; and the power supply circuit is respectively connected with the differential amplification circuit, the constant temperature difference control circuit and the acquisition circuit.
In the technical scheme, the anemometer adopts a silicon-based film structure, and a heating resistor, a temperature measuring resistor and a compensating resistor are integrated in the anemometer. Because the thermal film and the temperature compensation part are manufactured by adopting the MEMS process, the temperature sensitivity of the three resistors can be well ensured to be consistent, and the insulation films are added in the resistors, so that the heat loss on the heating resistor is less, and the resistors can be heated to a specified temperature point with lower power.
In the above technical solution, preferably, the constant temperature difference control circuit includes a resistor R3, a resistor R4, a resistor R40, a resistor R41, a resistor Rh, an operational amplifier U4 and a MOS transistor Q1, which are connected to each other, the resistor R4, the resistor R40 and the resistor Rh are connected in series and then grounded, the resistor R40 and the heating resistor Rj are connected in series and then grounded, the operational amplifier U4 is connected to a connection line between the resistor R40 and the heating resistor Rj and between the resistor R4 and the resistor R41, and the MOS transistor Q1 is connected to the resistor R4, the resistor R40 and the resistor R3, respectively.
In any of the above technical solutions, preferably, the differential amplifier circuit includes a resistor R6, a resistor R7, a resistor R37, a resistor R38, a resistor R42-a resistor R47, a resistor R50, and an operational amplifier U5-an operational amplifier U7, which are connected to each other, the resistor R6 is connected in series with the temperature measurement resistor Rc1, the resistor R7 is connected in series with the temperature measurement resistor Rc2 and then connected in parallel, the operational amplifier U5 is connected to a connection line between the resistor R7 and the temperature measurement resistor Rc2, and the operational amplifier U6 is connected to a connection line between the resistor R6 and the temperature measurement resistor Rc 1; one end of a resistor R37, one end of a resistor R50 and one end of a resistor R3 which are connected in series are connected to the operational amplifier U5, the other end of the resistor R46 and the resistor R47 are connected in series to the operational amplifier U6, one end of a resistor R42 and one end of the resistor R43 are connected in series, the other end of the resistor R5393 and the other end of the resistor R43 are connected to the operational amplifier U5, and the resistor R44 and the resistor R45 are connected in parallel to the resistor R47.
In any of the above technical solutions, preferably, the power supply circuit includes a capacitor C5, a capacitor C10-a capacitor C12, a capacitor C14, and a capacitor C15, the power supply circuit comprises a resistor R25, a resistor R27, a diode D8, an inductor L1, a power supply chip U1 and a power supply chip U2, a BST end and a SW end of a power supply chip U1 are connected through a capacitor C10, an IN end and an EN end of the power supply chip U1 are connected through a resistor R25, a capacitor C11 and a capacitor C12 are connected with the resistor R25 after being connected IN parallel, an SW end of the power supply chip U25 is connected with an IN end of the power supply chip U25 through an inductor L25, a diode D25 is connected to a connecting line between the SW end and the inductor L25 of the power supply chip, the capacitor C25 is connected to a connecting line between the inductor L25 and the IN end of the power supply chip U25, the capacitor C25 and the capacitor C25 are respectively connected to an OUT end of the power supply chip U25, the resistor R25 and the resistor R25 are connected with the ground after being connected IN series, and.
In any one of the above technical solutions, preferably, the acquisition circuit includes an acquisition chip U3, a capacitor C3 and a single chip microcomputer, the acquisition chip U3 is connected to the SPI terminal of the single chip microcomputer, and the AIN1+ terminal of the acquisition chip U3 is connected to the capacitor C3.
In any of the above technical solutions, preferably, the heating resistor Rj, the temperature measuring resistors Rc1 and Rc2 are all platinum resistors.
In any of the above embodiments, the thermometric resistors Rc1 and Rc2 are preferably platinum resistors of the same specification.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 shows a block diagram of an anemometer according to an embodiment of the present invention;
fig. 2 shows a circuit diagram of a differential amplifier circuit according to an embodiment of the present invention;
fig. 3 is a circuit diagram of a constant temperature difference control circuit according to an embodiment of the present invention;
fig. 4 shows a circuit diagram of a power supply circuit according to an embodiment of the present invention;
fig. 5 shows a circuit diagram of an acquisition circuit according to an embodiment of the invention;
fig. 6 shows a block flow diagram of an anemometer according to an embodiment of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention more clearly understood, the present invention will be described in further detail with reference to the accompanying drawings and detailed description. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the scope of the present invention is not limited to the specific embodiments disclosed below.
As shown in fig. 1 to 6, a MEMS constant temperature differential thermal film type anemometer according to an embodiment of the present invention includes: a differential amplifier circuit 10 having a heating resistor Rj whose resistance value changes with temperature change; a constant temperature difference control circuit 20 connected to the differential amplifier circuit 10, the constant temperature difference control circuit 20 having two temperature measuring resistors Rc1 and Rc2, the temperature measuring resistor Rc1 and the temperature measuring resistor Rc2 being symmetrically provided at both ends of the heating resistor Rj; the acquisition circuit 30 is connected with the constant temperature difference control circuit 20, and the acquisition circuit 30 can convert the voltage signal of the constant temperature difference control circuit 20 into a wind speed signal; and the power supply circuit 40 is respectively connected with the differential amplifying circuit 10, the constant temperature difference control circuit 20 and the acquisition circuit 30.
In this embodiment, the anemometer adopts a silicon-based thin film structure, and a heating resistor, a temperature measuring resistor and a compensation resistor are integrated inside the anemometer. Because the thermal film and the temperature compensation part are manufactured by adopting the MEMS process, the temperature sensitivity of the three resistors can be well ensured to be consistent, and the insulation films are added in the resistors, so that the heat loss on the heating resistor is less, and the resistors can be heated to a specified temperature point with lower power.
In the above embodiment, preferably, as shown in fig. 3, the constant temperature difference control circuit 20 includes a resistor R3, a resistor R4, a resistor R40, a resistor R41, a resistor Rh, an operational amplifier U4 and a MOS transistor Q1 which are connected to each other, the resistor R4, the resistor R40 and the resistor Rh are grounded after being connected in series, the resistor R40 and the heating resistor Rj are grounded after being connected in series, the operational amplifier U4 is connected to a connection line between the resistor R40 and the heating resistor Rj and between the resistor R4 and the resistor R41, and the MOS transistor Q1 is connected to the resistor R4, the resistor R40 and the resistor R3 respectively.
In this embodiment, the constant temperature difference control circuit 20 is a heating resistor heating to make its temperature higher than the ambient temperature, and the common control modes include constant power, constant current, constant temperature and constant temperature difference modes. Compared with other modes, the constant temperature difference control mode is to control the difference value between the temperature of the sensor and the ambient temperature to be a fixed value, so that the output value of the measuring circuit is theoretically unrelated to the ambient temperature.
In any of the above embodiments, preferably, as shown in fig. 2, the differential amplifier circuit 10 includes a resistor R6, a resistor R7, a resistor R37, a resistor R38, a resistor R42-a resistor R47, a resistor R50, and an operational amplifier U5-an operational amplifier U7, which are connected to each other, wherein the resistor R6 is connected in series with the temperature measurement resistor Rc1, and the resistor R7 is connected in series with the temperature measurement resistor Rc2 and then connected in parallel, the operational amplifier U5 is connected to a connection line between the resistor R7 and the temperature measurement resistor Rc2, and the operational amplifier U6 is connected to a connection line between the resistor R6 and the temperature measurement resistor Rc 1; one end of a resistor R37, one end of a resistor R50 and one end of a resistor R3 which are connected in series are connected to the operational amplifier U5, the other end of the resistor R46 and the resistor R47 are connected in series to the operational amplifier U6, one end of a resistor R42 and one end of the resistor R43 are connected in series, the other end of the resistor R5393 and the other end of the resistor R43 are connected to the operational amplifier U5, and the resistor R44 and the resistor R45 are connected in parallel to the resistor R47.
In this embodiment, the signal processing circuit in the anemometer selects the differential amplification circuit 10, the temperature measuring resistors symmetrically arranged on both sides of the heating resistor, and the two temperature measuring resistors and the other two resistance value fixing resistors are used to build a bridge circuit. The thermal field on the heating resistor is influenced by wind force, so that the temperature sensed by the temperature measuring resistors on two sides is different, the resistance values are also different, the voltage on the two resistors can generate a difference value, the difference value is sent into the differential amplification circuit 10, and the signal output finally is acquired by the singlechip 31 after amplification and filtering.
In any of the above embodiments, preferably, as shown in fig. 4, the power supply circuit 40 includes a capacitor C5, a capacitor C10-a capacitor C12, a capacitor C14, a capacitor C15, the power supply circuit comprises a resistor R25, a resistor R27, a diode D8, an inductor L1, a power supply chip U1 and a power supply chip U2, a BST end and a SW end of a power supply chip U1 are connected through a capacitor C10, an IN end and an EN end of the power supply chip U1 are connected through a resistor R25, a capacitor C11 and a capacitor C12 are connected with the resistor R25 after being connected IN parallel, an SW end of the power supply chip U25 is connected with an IN end of the power supply chip U25 through an inductor L25, a diode D25 is connected to a connecting line between the SW end and the inductor L25 of the power supply chip, the capacitor C25 is connected to a connecting line between the inductor L25 and the IN end of the power supply chip U25, the capacitor C25 and the capacitor C25 are respectively connected to an OUT end of the power supply chip U25, the resistor R25 and the resistor R25 are connected with the ground after being connected IN series, and.
In any of the above embodiments, preferably, as shown in fig. 5, the acquisition circuit 30 includes an acquisition chip U3, a capacitor C3 and a single chip microcomputer 31, the acquisition chip U3 is connected to the SPI terminal of the single chip microcomputer 31, and the AIN1+ terminal of the acquisition chip U3 is connected to the capacitor C3.
In any of the above embodiments, the heating resistor Rj, the temperature measuring resistors Rc1 and Rc2 are preferably all platinum resistors.
In any of the above embodiments, preferably, thermometric resistors Rc1 and Rc2 are platinum resistors of the same specification.
The utility model provides a poor hot membrane type anemograph of MEMS constant temperature, anemograph inside contain temperature measurement resistance Rc1 and Rc2 (platinum resistance) and a heating resistor Rj (platinum resistance) that two coefficients are unanimous, and the temperature measurement resistance equidistance is arranged on the heating resistor both sides. The temperature measuring resistor and two same fixed resistance resistors form a Wheatstone bridge circuit. The heating resistor in the constant temperature difference control circuit 20 and the resistor R40 in the differential amplifier circuit 10 form one path, and the resistor R4, the resistor R41, and the resistor Rh form an environment compensation resistor as the other path. The change of the resistance value of the resistor R41 can adjust the heating temperature of the heating resistor.
In the process of measuring the wind speed, different voltages V2 and V1 are sent into a differential circuit, and voltage variation corresponding to the wind speed is obtained through differential pressure amplification:
V0＝((2R38+R50)/R50)(R43R42)(V2-V1)+VOFFSET。
the working principle of the thermal mode anemometer is as follows:
when the wind speed flows, the temperature on the heating resistor can be reduced, because the heating resistor is a platinum resistor, the reduction of the resistance value can lead to the reduction of the voltage on the heating resistor, the input voltage difference of the operational amplifier is increased, the corresponding increase of the output voltage leads to the increase of the voltage and the temperature on the heating resistor, and the resistance value of the heating resistor is ensured to be maintained in dynamic balance, so that the temperature difference between the heating resistor and the ambient temperature is kept consistent. Although the heating resistors are balanced, the temperature sensing resistors Rc1 and Rc2 which are arranged at equal intervals upstream and downstream of the heating resistors are influenced by wind force, the temperature sensed by the upstream resistors is low, and the temperature sensed by the downstream resistors is high. The voltages V1 and V2 on the two resistors are not equal to generate a voltage difference (V2-V1), the voltage difference is larger when the wind speed is larger, the voltage difference is sent to an amplifying circuit to be converted into the voltage V0, and the wind speed can be determined by measuring the voltage and utilizing the corresponding relation between the voltage and the wind speed.
In the present application, the terms "first", "second", "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance; the term "plurality" means two or more unless expressly limited otherwise. The terms "mounted," "connected," "fixed," and the like are to be construed broadly, and for example, "connected" may be a fixed connection, a removable connection, or an integral connection; "coupled" may be direct or indirect through an intermediary. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.
In the description of the present invention, it should be understood that the terms "upper", "lower", "left", "right", "front", "back", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the device or unit indicated must have a specific direction, be constructed and operated in a specific orientation, and therefore, should not be construed as limiting the present invention.
In the description of the present specification, the description of the terms "one embodiment," "some embodiments," "specific embodiments," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. A MEMS constant temperature differential thermal film anemometer comprising:
the differential amplification circuit is provided with a heating resistor Rj, and the resistance value of the heating resistor Rj changes along with the temperature change;
a constant temperature difference control circuit connected to the differential amplifier circuit, the constant temperature difference control circuit having two temperature measuring resistors Rc1 and Rc2, the temperature measuring resistor Rc1 and the temperature measuring resistor Rc2 being symmetrically provided at both ends of the heating resistor Rj;
the acquisition circuit is connected with the differential amplification circuit, and the differential amplification circuit can convert the wind speed signal into a voltage signal and send the voltage signal to the acquisition circuit;
and the power supply circuit is respectively connected with the differential amplification circuit, the constant temperature difference control circuit and the acquisition circuit.
2. The MEMS constant temperature differential thermal film anemometer of claim 1 wherein: the constant temperature difference control circuit comprises a resistor R3, a resistor R4, a resistor R40, a resistor R41, a resistor Rh, an operational amplifier U4 and a MOS tube Q1 which are connected, wherein the resistor R4, the resistor R40 and the resistor Rh are connected in series and then grounded, the resistor R40 and the heating resistor Rj are connected in series and then grounded, the operational amplifier U4 is respectively connected with a connecting line between the resistor R40 and the heating resistor Rj and between the resistor R4 and the resistor R41, and the MOS tube Q1 is respectively connected with the resistor R4, the resistor R40 and the resistor R3.
3. The MEMS constant temperature differential thermal film anemometer of claim 1 wherein: the differential amplification circuit comprises a resistor R6, a resistor R7, a resistor R37, a resistor R38, a resistor R42-a resistor R47, a resistor R50 and an operational amplifier U5-an operational amplifier U7 which are connected with one another, wherein the resistor R6 is connected with the temperature measurement resistor Rc1 in series, the resistor R7 is connected with the temperature measurement resistor Rc2 in series and then connected in parallel, the operational amplifier U5 is connected with a connecting line between the resistor R7 and the temperature measurement resistor Rc2, and the operational amplifier U6 is connected with a connecting line between the resistor R6 and the temperature measurement resistor Rc 1; the resistance R37, the resistance R50 and the one end access after the resistance R3 connects in series the operational amplifier U5, the other end access the operational amplifier U6, the resistance R46 and the resistance R47 connect in series the operational amplifier U6, the resistance R42 and the resistance R43 connect in series, one end access the operational amplifier U5, the other end access the operational amplifier U7, the resistance R44 and the resistance R45 connect in parallel the resistance R47.
4. The MEMS constant temperature differential thermal film anemometer of claim 1 wherein: the power supply circuit comprises a capacitor C5, a capacitor C10-a capacitor C12, a capacitor C14, a capacitor C15, a resistor R25-a resistor R27, a diode D27, an inductor L27, and power supply chips U27 and U27, wherein a BST end and a SW end of the power supply chip U27 are connected through the capacitor C27, an IN end and an EN end of the power supply chip U27 are connected through the resistor R27, the capacitor C27 and the capacitor C27 are connected IN parallel and then connected with the resistor R27, the SW end of the power supply chip U27 and the IN end of the power supply chip U27 are connected through the inductor L27, the diode D27 is connected to a connecting line between the SW end of the power supply chip and the inductor L27, the capacitor C27 is connected to a connecting line between the inductor L27 and the IN end of the power supply chip U27, the capacitor C27 and the capacitor C27 are connected to the OUT end of the power supply chip U27, and the resistor R27 are connected IN series, the FB end of the power chip U1 is connected to the connection line between the resistor R26 and the resistor R27.
5. The MEMS constant temperature differential thermal film anemometer of claim 1 wherein: the acquisition circuit comprises an acquisition chip U3, a capacitor C3 and a single chip microcomputer, wherein the acquisition chip U3 is connected with the SPI end of the single chip microcomputer, and the AIN1+ end of the acquisition chip U3 is connected with the capacitor C3.
6. MEMS constant temperature differential thermal film anemometer according to any of the claims 1 to 5 characterized in that: the heating resistor Rj, the temperature measuring resistors Rc1 and Rc2 are all platinum resistors.
7. The MEMS constant temperature differential thermal film anemometer of claim 6 wherein: the temperature measuring resistors Rc1 and Rc2 are platinum resistors with the same specification.
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| CN202020219146.6U CN211348306U (en) | 2020-02-27 | 2020-02-27 | MEMS constant-temperature differential thermal film type anemometer |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113156159A (en) * | 2021-02-10 | 2021-07-23 | 复旦大学 | Airspeed meter applied to aircraft and without airspeed tube |
| CN113759145A (en) * | 2021-09-08 | 2021-12-07 | 华东师范大学 | Thermal type wind speed and wind direction sensor and preparation method of graphene film |
-
2020
- 2020-02-27 CN CN202020219146.6U patent/CN211348306U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113156159A (en) * | 2021-02-10 | 2021-07-23 | 复旦大学 | Airspeed meter applied to aircraft and without airspeed tube |
| CN113759145A (en) * | 2021-09-08 | 2021-12-07 | 华东师范大学 | Thermal type wind speed and wind direction sensor and preparation method of graphene film |
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