Underwater flow velocity sensor and working method thereof

Abstract

The present invention discloses an underwater flow velocity sensor and its working method, which relates to the field of underwater flow velocity measurement technology. The sensor includes an upper substrate and a lower substrate, both of which have electrodes and are arranged in an upper and lower staggered manner. A groove is provided at one end of the upper substrate. A torsion assembly includes a torsion beam, a seesaw, and cilia. The torsion assembly is arranged directly above the groove at one end of the upper substrate. The torsion assembly and the upper substrate are separated by a groove and can be twisted around the torsion beam. The torsion beam and the axis of the upper substrate in the longitudinal direction coincide with each other. The bottom of the cilia is fixed to the torsion beam. Two heaters are respectively fixed to the two ends of the seesaw of the torsion assembly and can be twisted synchronously with the torsion assembly. Two sensors on the upper substrate are respectively located outside the torsion assembly and adjacent to the heaters. The two sensors are respectively connected to a bridge circuit. Based on the working method of the underwater flow velocity sensor of the present invention, it can be applied to both low flow velocity measurement and high flow velocity measurement.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater flow velocity measurement, and in particular to an underwater flow velocity sensor and a working method thereof. Background Art

[0002] With the rapid development of underwater exploration, marine engineering, environmental monitoring and other fields, the demand for accurate underwater flow velocity measurement is becoming increasingly higher. Traditional underwater flow velocity measurement methods, such as Doppler current meters and acoustic Doppler current profilers, have met these requirements to a certain extent, but their stability and accuracy in extreme environments (such as high flow rates, high pressures, and low temperatures) still need to be improved.

[0003] In order to meet the needs of underwater flow velocity measurement, calorimetric flow velocity sensors or ciliary flow velocity sensors are currently commonly used. The sensing principle of the calorimetric flow velocity sensor is: the central heating unit generates heat, and the flow of the fluid changes the distribution of the upstream and downstream thermal fields; the specific implementation is that when the flow comes from the left, the temperature on the left side of the heating unit drops, and the temperature on the right side rises. The change in temperature will affect the resistance of the sensors on the left and right sides, and the specific value of the flow velocity is solved by taking the difference between the resistance values ​​of the sensors on both sides. The sensing principle of the ciliary flow velocity sensor is: the flow velocity is measured by the deformation of the cilia with the flow velocity; the greater the flow velocity, the greater the strain accumulated at the root of the cilia. By arranging a strain sensor at the root of the cilia, the flow velocity can be measured.

[0004] Existing calorimetric flow sensors offer high sensitivity and resolution for flow velocity measurement, but they easily saturate at lower underwater flow rates. Their output tends to remain constant at lower flow rates, making them inadequate for sensing high flow rates. Cilia-based flow sensors measure flow velocity using the drag created by cilia in the flow field, making them ideal for high-velocity measurements. However, the drag created by cilia in the flow field has a quadratic relationship with flow velocity. At lower flow rates, the drag created by cilia barely allows strain sensors to react, making them unsuitable for low-velocity measurements.

[0005] In order to achieve high-sensitivity measurement of flow velocity within a large flow velocity range underwater, it is necessary not only to inherit the high sensitivity characteristics of calorimetric flow velocity sensors at low flow velocities, but also to develop the advantages of the high range of ciliary flow velocity sensors. Therefore, it is urgent to design a flow velocity sensor with a wide range that can be used for both low and high flow velocity measurements. Summary of the Invention

[0006] The purpose of the present invention is to provide an underwater flow velocity sensor and its working method to solve the problems existing in the above-mentioned prior art. When the flow velocity is low, two sensors on the upper substrate are used to measure the flow velocity. When the flow velocity is high, cilia are used to measure the flow velocity in combination with two sensors on the lower substrate. It can be used for both low flow velocity measurement and high flow velocity measurement.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] The present invention provides an underwater flow velocity sensor, comprising:

[0009] A substrate, comprising an upper substrate and a lower substrate arranged alternately in an up-and-down manner, wherein electrodes are provided on both the upper substrate and the lower substrate;

[0010] A groove is formed at one end of the upper substrate and is located at an intersecting position between the upper substrate and the lower substrate;

[0011] A torsion assembly comprises a torsion beam, a seesaw, and cilia. The torsion assembly is disposed directly above the groove at one end of the upper substrate, separated from the upper substrate by a groove, and capable of twisting around the torsion beam. The torsion beam coincides with the axis in the longitudinal direction of the upper substrate. The base of the cilia is fixed to the torsion beam, and when the cilia swing, they can drive the torsion assembly to twist synchronously.

[0012] Heaters, two of which are respectively fixed to the two ends of the seesaw of the torsion assembly and are capable of synchronously twisting with the torsion assembly;

[0013] Sensors, two of which are respectively provided on the upper substrate and the lower substrate;

[0014] The two sensors on the upper substrate are respectively located outside the torsion assembly and adjacent to the heater on the same side; and the two sensors on the upper substrate are externally connected to a bridge circuit through the electrodes of the upper substrate;

[0015] The two sensors on the lower substrate are respectively located directly below the two heaters and at the bottom of the groove; and the two sensors on the lower substrate are externally connected to another bridge circuit through the electrodes of the lower substrate.

[0016] Optionally, the torsion assembly includes a torsion beam and a seesaw, the seesaw includes two seesaw arms symmetrical with respect to the torsion beam, the seesaw arms are connected to both sides of the torsion beam, the torsion beam is arranged at one end of the upper substrate, and the axis of the torsion beam coincides with the axis in the length direction of the upper substrate; the bottom of the cilia is fixed on the torsion beam, and when the cilia swing, it can drive the seesaw to twist around the torsion beam; a heater is fixedly provided at one end of the seesaw arm away from the torsion beam.

[0017] Optionally, the torsion beam passes through the middle of the groove, and the rocker arm is located on the groove; the two sensors on the upper substrate are respectively located on two sides of the outside of the groove.

[0018] Optionally, an ambient temperature resistor is further included, which is located on the lower substrate and covered by the upper substrate. The ambient temperature resistor is externally connected to a control circuit, and the heater is connected to the control circuit through the electrodes of the upper substrate.

[0019] Optionally, the sensor is a platinum / chromium resistor or a Vox resistor sputtered by an ion beam sputtering apparatus, where the platinum / chromium resistor is a Pt / Cr resistor, and Vox is vanadium oxide, which is a mixture of various oxides such as VO2 and V2O3.

[0020] Optionally, the heater is a platinum / chromium resistor sputtered by an ion beam sputtering apparatus or a magnetron sputtering apparatus.

[0021] Optionally, the cilia are prepared by spin coating photoresist followed by photolithography. The photoresist used in the present invention is SU-8 photoresist. The shape and size of the cilia need to be adjusted according to the specific application scenario.

[0022] Optionally, the cilia are prepared by bonding optical fibers.

[0023] The present invention further provides a method for operating the underwater flow velocity sensor, comprising the following steps:

[0024] The two sensors of the upper substrate are respectively connected to the two bridge arms of one bridge circuit; the two sensors of the lower substrate are respectively connected to the two bridge arms of another bridge circuit;

[0025] Start the control circuit to raise the heater temperature to a temperature higher than the ambient temperature;

[0026] When the incoming flow flows from one side and the flow rate is lower than the limit value, the ciliary swing amplitude is small and the heater is fixed; on the upper substrate, the temperature of the sensor located upstream of the incoming flow drops and the resistance value increases, and on the upper substrate, the temperature of the sensor located downstream of the incoming flow rises and the resistance value decreases. The bridge circuit connecting the two sensors on the upper substrate is unbalanced, and the voltage at the output end of the operational amplifier becomes larger, and the voltage size is used to reflect the flow rate size; when the flow rate of the incoming flow to be measured is large, the speed value when it reaches the speed that can just drive the ciliary swing is used as the limit value of the present invention.

[0027] When the flow rate of the incoming flow exceeds the limit value, the cilia swing, causing the torsion beam to drive the seesaw to twist synchronously. The heater located upstream of the incoming flow moves upward, away from the sensor located directly below it on the lower substrate; the heater located downstream of the incoming flow moves downward, closer to the sensor located directly below it on the lower substrate. The temperature of the sensor located upstream of the incoming flow on the lower substrate drops, and the resistance value increases. The temperature of the sensor located downstream of the incoming flow on the lower substrate rises, and the resistance value decreases. The bridge circuit connecting the two sensors on the lower substrate becomes unbalanced, and the voltage at the output of the op amp increases. The voltage is used to reflect the flow rate. The two sensors located on the same substrate are located upstream and downstream of the incoming flow to be measured, respectively, which increases the temperature difference between the two. This temperature difference will continue to increase with the increase of flow rate, making it more sensitive than using a single sensor.

[0028] Compared with the prior art, the present invention has achieved the following technical effects:

[0029] The present invention uses two sensors on the upper substrate to measure flow velocity at low speeds, while using cilia in conjunction with two sensors on the lower substrate to measure flow velocity at high speeds. This allows for high-precision measurement of both high and low flow rates. This invention employs a calorimetric measurement approach, combining a torsion assembly with a solid cilia structure and employing a thermal-fluid-solid coupling approach to address the saturation drawback of calorimetric flow measurement. This allows for a significant increase in measurement range while maintaining sensitivity using the calorimetric principle. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 It is a schematic diagram of a partially enlarged structure of the underwater flow velocity sensor structure and its upper substrate of the present invention;

[0032] Figure 2 It is a structural schematic diagram of the torsion assembly of the present invention;

[0033] Figure 3 This is a schematic diagram of the arrangement structure of the ambient temperature resistor of the present invention;

[0034] Figure 4 Schematic diagram of the control circuit of the present invention;

[0035] Figure 5 A schematic diagram of a bridge circuit connected to a sensor according to the present invention;

[0036] Figure 6 This is a schematic diagram of a temperature difference simulation between the first sensor and the third sensor of the present invention;

[0037] Figure 7 Schematic diagram of the temperature difference simulation between the second sensor and the fourth sensor of the present invention.

[0038] In the figure: 1-upper electrode, 2-lower electrode, 3-first sensor, 4-third sensor, 5-second sensor, 6-fourth sensor, 7-first heater, 8-second heater, 9-cilia, 10-torsion beam, 11-seesaw arm, 12-ambient temperature resistor, 13-upper substrate, 14-lower substrate, 15-groove, 16-trench. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention 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 making creative efforts are within the scope of protection of the present invention.

[0040] The purpose of the present invention is to provide an underwater flow velocity sensor and its working method to solve the problems existing in the above-mentioned prior art. When the flow velocity is low, two sensors on the upper substrate are used to measure the flow velocity. When the flow velocity is high, cilia are used to measure the flow velocity in combination with two sensors on the lower substrate. It can be used for both low flow velocity measurement and high flow velocity measurement.

[0041] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] refer to Figure 1 、 Figure 2 、 Figure 3As shown, the present invention provides an underwater flow rate sensor, comprising an upper substrate 13 and a lower substrate 14 arranged alternately in an upper and lower manner, an upper electrode 1 being provided on the upper substrate 13, and a lower electrode 2 being provided on the lower substrate 14; a groove 15 being provided at one end of the upper substrate 13, the groove 15 being located at the interlaced position of the upper substrate 13 and the lower substrate 14, a torsion assembly being arranged directly above the groove 15 at one end of the upper substrate 13, comprising a torsion beam 10, a seesaw and cilia 9, the torsion assembly being separated from the upper substrate 13 by a groove 16, and being capable of torsion around the torsion beam 10, the torsion beam 10 coinciding with the longitudinal axis of the upper substrate 13; the bottom of the cilia 9 being fixed on the torsion beam 10, and ... When the hair 9 swings, it can drive the torsion component to twist synchronously; the two heaters are respectively fixed at the two ends of the seesaw of the torsion component, and can twist synchronously with the torsion component; two sensors are respectively provided on the upper substrate 13 and the lower substrate 14; the two sensors on the upper substrate 13 are respectively located on the outside of the torsion component, and the two sensors are respectively adjacent to the heaters located on the same side of each other; and the two sensors on the upper substrate 13 are externally connected to a bridge circuit through the upper electrode 1; the two sensors on the lower substrate 14 are respectively located directly below the two heaters and at the bottom of the groove 15; and the two sensors on the lower substrate 14 are externally connected to another bridge circuit through the lower electrode 2.

[0043] During the detection process, a pair of sensors located on the same layer of substrate are located on both sides of the bridge arm. Because the resistance values ​​of the two sensors change in opposite directions with the flow rate, and the resistance difference increases with the increase of the temperature difference. Therefore, as the flow rate increases, the bridge becomes more and more unbalanced, and the voltage at the output of the operational amplifier gradually increases. The output voltage value is used to reflect the magnitude of the flow rate. The bridge circuit involved in the present invention belongs to the prior art. The bridge is a circuit structure used to accurately measure electrical parameters such as resistance, capacitance, and inductance. The core of the bridge circuit is to achieve high-precision measurement by comparing the impedance of two or more branches in the circuit.

[0044] In a specific embodiment, the sensors include a first sensor 3, a second sensor 5, a third sensor 4, and a fourth sensor 6, and the heater includes a first heater 7 and a second heater 8. A groove 15 is provided at one end of the upper substrate 13 and passes through the surface of the upper substrate 13. The seesaw includes two seesaw arms 11 symmetrical with respect to the torsion beam 10. The seesaw arms 11 are connected to both sides of the torsion beam 10 and are located on the groove 15. The torsion beam 10 is provided at one end of the upper substrate 13 and passes through the middle of the groove 15. The axis of the torsion beam 10 coincides with the axis of the length direction of the upper substrate 13. The bottom of the cilia 9 is fixed to the torsion beam 10. When the cilia 9 swing, they can drive the seesaw to twist around the torsion beam 10. A first heater 7 is fixed to the end of one of the seesaw arms 11 away from the torsion beam 10, and a second heater 8 is fixed to the end of the other seesaw arm 11 away from the torsion beam 10. The two sensors on the upper substrate 13 are respectively located on both sides of the outside of the groove 15, including a first sensor 3 located on the outside of the first heater 7 and a third sensor 4 located on the outside of the second heater 8; the two sensors on the lower substrate 14 include a second sensor 5 located directly below the first heater 7 and a fourth sensor 6 located directly below the second heater 8.

[0045] In this embodiment, the second sensor 5, fourth sensor 6, first heater 7, and second heater 8 are combined into a fluid-solid coupled calorimetric measurement unit for measuring high-flow sections. When the incoming flow is from the third sensor 4 to the first sensor 3, and the incoming flow velocity is high, the cilia 9 are blown, driving the seesaw arm 11 to rotate around the torsion beam 10. The first heater 7 approaches the second sensor 5, and the temperature of the second sensor 5 rises. The second heater 8 moves away from the fourth sensor 6, and the temperature of the fourth sensor 6 drops. The temperature difference between the two sensors increases. This temperature difference continues to increase as the flow velocity increases.

[0046] In order to make the temperature value of the heater of the present invention always higher than the temperature value of the external environment, the present embodiment introduces an ambient temperature resistor 12. The ambient temperature resistor 12 belongs to a conventional structure in this field, and generally refers to resistors used to monitor and respond to changes in ambient temperature. Their resistance value will change with changes in temperature. This type of resistor is commonly used in electronic equipment for temperature sensing, compensation circuits, thermal protection circuits, etc. to achieve temperature monitoring and control. The ambient temperature resistor 12 is located on the lower substrate 14. The ambient temperature resistor 12 is located on the same plane as the second sensor 5 and the fourth sensor 6, but is covered by the upper substrate 13. The ambient temperature resistor 12 is externally connected to a control circuit, and the heater is connected to the control circuit through the upper electrode 1 of the upper substrate 13. The control circuit is another bridge circuit in the prior art, such as Figure 4As shown. Ambient temperature resistor 12 is used in conjunction with first heater 7 and second heater 8 to ensure that the heater temperature is always a fixed value higher than the ambient temperature. Bridge balancing ensures that the heater temperature remains constant above the ambient temperature even when current is flowing. When the ambient temperature changes, the resistance of ambient temperature resistor 12 changes, disrupting the balance of the bridge circuit. Feedback from the op amp affects the current in the bridge circuit. This change in current causes the heater temperature to change, causing the heater temperature to vary with the ambient temperature.

[0047] The present invention also provides a method for operating the underwater flow velocity sensor, comprising the following steps:

[0048] The two sensors of the upper substrate 13 are connected to the two bridge arms of one bridge circuit respectively; the two sensors of the lower substrate 14 are connected to the two bridge arms of another bridge circuit respectively;

[0049] Start the control circuit to raise the heater temperature to a temperature higher than the ambient temperature;

[0050] When the flow is from the left and the flow rate is low, the movement amplitude of the ciliary hair 9 is small, the torsion beam 10 is basically not twisted, and the mechanical structure remains basically unchanged. At this time, the temperature of the third sensor 4 drops and the temperature of the first sensor 3 rises, which will cause the resistance changes of the two sensors to be opposite. By connecting the two sensors to the corresponding bridge circuit, as shown in FIG. Figure 5 As shown, the temperature of the first sensor 3 rises, and the resistance decreases. The temperature of the third sensor 4 drops, and the resistance increases, causing the bridge to become unbalanced and the voltage at the output of the op amp to increase. The voltage is used to reflect the flow rate.

[0051] When the flow is from the left and the flow rate is high, ciliary fibers 9 experience greater resistance from the incoming flow, causing torsion beam 10 to twist. First heater 7 moves downward, approaching second sensor 5, while second heater 8 moves upward, away from fourth sensor 6. Consequently, the temperature of second sensor 5 rises, while the temperature of fourth sensor 6 drops. By connecting the two sensors to corresponding bridge circuits, the output voltage of the op amp is used to reflect the flow rate. It is important to note that the relationship between the output voltage and flow rate of the bridge composed of second sensor 5 and fourth sensor 6 is different from that of the bridge composed of first sensor 3 and third sensor 4, requiring separate calibration of the two measurement systems.

[0052] After simulation, Figure 6 The figure shows the temperature difference between the first sensor 3 and the third sensor 4 in the range of 0-5 m / s (water flow). As can be seen from the figure, the temperature difference shows an upward trend in the flow rate range of 0-0.6 m / s, and saturates and decreases in the subsequent flow rate range.

[0053] like Figure 7 Figure 2 shows the temperature difference between the second sensor 5 and the fourth sensor 6. The temperature difference shows an upward trend within the 0-5 m / s (water flow) range, but changes little within the 0-0.6 m / s (water flow) range. Therefore, the present invention uses the 0-0.6 m / s range as the low-flow measurement segment, measured using the first sensor 3 and the third sensor 4, and the 0.6-5 m / s range as the high-flow measurement segment, measured using the second sensor 5 and the fourth sensor 6. Sensor data is collected throughout the entire flow velocity range, and sensor data is selectively used in different flow velocity segments. Cilia 9 move throughout the entire flow velocity range, but their movement is minimal in the low-flow velocity range.

[0054] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. An underwater flow velocity sensor, characterized in that: include: A substrate, comprising an upper substrate and a lower substrate arranged alternately in an up-and-down manner, wherein electrodes are provided on both the upper substrate and the lower substrate; A groove is formed at one end of the upper substrate and is located at an intersecting position between the upper substrate and the lower substrate; A torsion assembly comprises a torsion beam, a seesaw, and cilia. The torsion assembly is disposed directly above the groove at one end of the upper substrate, separated from the upper substrate by a groove, and capable of twisting around the torsion beam. The torsion beam coincides with the axis in the longitudinal direction of the upper substrate. The base of the cilia is fixed to the torsion beam, and when the cilia swing, they can drive the torsion assembly to twist synchronously. Heaters, two of which are respectively fixed to the two ends of the seesaw of the torsion assembly and are capable of synchronously twisting with the torsion assembly; Sensors, two of which are respectively provided on the upper substrate and the lower substrate; The two sensors on the upper substrate are respectively located outside the torsion assembly and adjacent to the heater on the same side; and the two sensors on the upper substrate are externally connected to a bridge circuit through the electrodes of the upper substrate; The two sensors on the lower substrate are respectively located directly below the two heaters and at the bottom of the groove; and the two sensors on the lower substrate are externally connected to another bridge circuit through the electrodes of the lower substrate; The seesaw includes two seesaw arms symmetrical with respect to the torsion beam, the seesaw arms are connected to both sides of the torsion beam, the torsion beam is arranged at one end of the upper substrate, and the axis of the torsion beam coincides with the axis of the length direction of the upper substrate; the bottom of the cilia is fixed on the torsion beam, and when the cilia swing, the seesaw can be driven to twist around the torsion beam; a heater is fixedly provided on one end of the seesaw arm away from the torsion beam.

2. The underwater flow velocity sensor according to claim 1, characterized in that: The torsion beam passes through the middle of the groove, and the rocker arm is located on the groove; the two sensors on the upper substrate are respectively located on two sides of the outside of the groove.

3. The underwater flow velocity sensor according to claim 1, characterized in that: It also includes an ambient temperature resistor, which is located on the lower substrate and covered by the upper substrate. The ambient temperature resistor is externally connected to a control circuit, and the heater is connected to the control circuit through the electrodes of the upper substrate.

4. The underwater flow velocity sensor according to claim 1, characterized in that: The sensor is a platinum / chromium resistor or a Vox material resistor.

5. A method for operating the underwater flow velocity sensor according to any one of claims 1 to 4, characterized in that: The steps include: The two sensors of the upper substrate are respectively connected to the two bridge arms of one bridge circuit; the two sensors of the lower substrate are respectively connected to the two bridge arms of another bridge circuit; Start the control circuit to raise the heater temperature to a temperature higher than the ambient temperature; When the incoming flow flows from one side and the flow velocity is lower than the limit value, the ciliary swing amplitude is small and the heater is fixed; the temperature of the sensor located upstream of the incoming flow on the upper substrate drops and the resistance value increases; the temperature of the sensor located downstream of the incoming flow on the upper substrate rises and the resistance value decreases, the bridge circuit connecting the two sensors on the upper substrate becomes unbalanced, the voltage at the output end of the operational amplifier becomes larger, and the voltage magnitude is used to reflect the flow velocity magnitude; When the flow rate of the incoming flow is higher than the limit value, the cilia swing, causing the torsion beam to drive the seesaw to twist synchronously, and the heater located upstream of the incoming flow moves upward, away from the sensor located directly below it on the lower substrate; the heater located downstream of the incoming flow moves downward, close to the sensor located directly below it on the lower substrate; on the lower substrate, the temperature of the sensor located upstream of the incoming flow drops and the resistance value increases, and on the lower substrate, the temperature of the sensor located downstream of the incoming flow rises and the resistance value decreases, the bridge circuit connecting the two sensors on the lower substrate is unbalanced, the voltage at the output end of the operational amplifier becomes larger, and the voltage size is used to reflect the flow rate.

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