High-precision cooling effect sensor under large-flow condition and working method thereof

Abstract

The invention belongs to the technical field of sensors, and discloses a high-precision cooling effect sensor under the large flow condition and a working method thereof.The sensor comprises a power circuit module, an excitation circuit module, a sensitive element module, a control circuit module and an output circuit module, and the output end of the excitation circuit module is connected with the input end of the sensitive element module; the sensitive element module senses external temperature and changes output voltage, the output end of the sensitive element module is connected with the input end of the control circuit module, the control circuit module carries out calculation based on a constant temperature difference algorithm on the voltage output by the sensitive element module, and temperature-related voltage and flow-related voltage are obtained and sent to the output circuit module. And the input voltage of the adjustable constant current source circuit is sent to the excitation circuit module. Digital negative feedback is used for replacing a negative feedback circuit formed by a cooling effect sensor based on a bridge circuit in practical application, and current passing through a platinum resistor is prevented from exceeding the natural heat dissipation capacity of the platinum resistor.

Description

Technical Field

[0001] This invention belongs to the field of sensor technology and relates to a cooling effect sensor for aircraft, specifically a high-precision cooling effect sensor under high flow conditions and its working method. Background Technology

[0002] Cooling effect sensors are used to measure the temperature and flow rate of cooling air in aircraft electronic equipment cabinets to monitor whether the cabinet ventilation meets the equipment's heat dissipation requirements. When the ventilation cooling effect is detected to be insufficient, the air conditioning controller automatically controls the switching of fans. The cooling effect sensor is installed inside the equipment cabinet's exhaust duct and fixed to the duct with a flange. In practical applications, the sensitive elements for cooling effect, platinum resistance thermometers Rt and Rw, are in the same bridge circuit. Under high flow conditions, the current flowing through platinum resistance thermometer Rt will cause it to heat up, resulting in a temperature higher than its ambient temperature, thus causing inaccurate temperature measurements. Summary of the Invention

[0003] To address the aforementioned issues, this invention provides a high-precision cooling effect sensor under high flow conditions and its operating method, which can accurately measure the temperature inside the electronic equipment bay of an aircraft under high flow conditions.

[0004] The technical solution of the present invention is as follows: A high-precision cooling effect sensor under high flow conditions includes a power supply circuit module, an excitation circuit module, a sensing element module, a control circuit module, and an output circuit module. The power supply circuit module provides power to the excitation circuit module, the control circuit module, and the output circuit module. The output terminal of the excitation circuit module is connected to the input terminal of the sensing element module. The sensing element module senses the external temperature and changes its output voltage. The output terminal of the sensing element module is connected to the input terminal of the control circuit module. The control circuit module calculates the voltage output by the sensing element module based on a constant temperature difference algorithm, obtains a temperature-related voltage and a flow-related voltage, and sends them to the output circuit module. The output circuit module obtains an adjustable constant current source circuit input voltage, which is then sent to the excitation circuit module as the input voltage for flow excitation.

[0005] Furthermore, the excitation circuit module includes a parallel micro constant current source circuit and an adjustable current source circuit. The micro constant current source circuit outputs a small current It with a constant amplitude, and the adjustable constant current source circuit outputs a current Iw with an adjustable amplitude. Among them, Iw=KfUf Iw is the amplitude of the output current of the adjustable constant current source circuit; Kf is the proportional coefficient; Uf is the input voltage of the adjustable constant current source circuit.

[0006] Furthermore, the sensitive element module includes platinum resistors Rt and Rw connected in parallel. The input terminal of platinum resistor Rt is connected to the output terminal of the micro constant current source circuit, and the input terminal of platinum resistor Rw is connected to the output terminal of the adjustable constant current source circuit. Platinum resistor Rt outputs voltage Ut, and platinum resistor Rw outputs voltage Uw.

[0007] Furthermore, the control circuit module includes a first voltage sampling circuit, a second voltage sampling circuit, and a microprocessor. The input terminal of the first voltage sampling circuit is connected to the output terminal of the platinum resistance Rt, and the input terminal of the second voltage sampling circuit is connected to the output terminal of the platinum resistance Rw. The Vt output by the first voltage sampling circuit and the Vw output by the second voltage sampling circuit are input to the microprocessor. After calculation by the microprocessor, the temperature-related voltage U1, the flow-related voltage U2, and the input voltage Uf of the adjustable constant current source circuit are obtained.

[0008] Furthermore, the output circuit module includes a temperature output circuit and a flow output circuit connected in parallel. The input terminal of the temperature output circuit receives a temperature-related voltage U1 and outputs a voltage Ua. The input terminal of the flow output circuit receives a flow-related voltage U2 and outputs a voltage Ub.

[0009] Furthermore, the platinum resistance Rt is a platinum resistance in the range of 300~2000Ω, and the platinum resistance Rw is a platinum resistance in the range of 20~100Ω.

[0010] A method for operating a high-precision cooling effect sensor under high flow rate conditions, using the aforementioned high-precision cooling effect sensor under high flow rate conditions, wherein the method for the microprocessor to calculate the input voltage of the adjustable constant current source circuit is as follows: Uf(s) = (Ki + Kp / s) (Tw - Tt) Tw=KwVw+Dw Tt=KtVt+Dt Where s is the Laplace transform operator; Tw is the temperature of the platinum resistance thermometer Rw; Tt is the temperature of the platinum resistance Rt; Ki, Kp (obtained through experimental calibration), Kw, and Kt are proportionality coefficients; Dw and Dt are bias coefficients. Ki and Kp were obtained through experimental calibration. Kt and Dt are related to the output current of the micro constant current source circuit of the excitation circuit module, while Kw and Dw are related to the output of the adjustable current source circuit of the excitation circuit module.

[0011] Furthermore, the method for the microprocessor to calculate the temperature-related voltage and the flow-related voltage is as follows: U1=f(Vt) U2=g(Vw)h(Vt) f(), g(), and h() are injective mappings (obtained through experimental calibration).

[0012] Furthermore, the method for outputting voltage Ua through temperature-dependent voltage U1 is as follows: Ua=Ka U1+Da The method for outputting voltage Ub through the flow-related voltage U2 is as follows: Ub = Kb U2 + Db Ka and Kb are proportionality coefficients; Da and Db are bias coefficients; Ka, Kb, Da, and Db are all derived from the voltage range that the aircraft system needs to identify.

[0013] In the aforementioned aircraft cooling effect sensor, the current in the platinum resistance Rt is a small constant current, and the heat generated by the platinum resistance Rt itself is negligible, so it will not cause the temperature of the platinum resistance Rt to exceed the ambient temperature.

[0014] The beneficial effects of this invention are as follows: Replacing the negative feedback circuit based on the bridge circuit of the cooling effect sensor in practical applications with digital negative feedback prevents the current passing through the platinum resistor Rt from exceeding its natural heat dissipation capacity, ensuring that the temperature of the platinum resistor Rt is always equal to the ambient temperature. This eliminates the temperature measurement error caused by the temperature rise of the platinum resistor Rt under high flow conditions (accuracy improved by 10% under high flow conditions). At the same time, the current passing through the platinum resistor Rt is a small current of fixed amplitude, which can reduce the power of the platinum resistor Rt by about 80% under high flow conditions, effectively reducing the power consumption of the cooling effect sensor on the aircraft and extending the service life of the platinum resistor Rt. Attached Figure Description

[0015] Figure 1 This is a circuit diagram of a cooling effect sensor for an aircraft. Detailed Implementation

[0016] This section describes embodiments of the present invention, used to explain and illustrate the technical solutions of the present invention. Unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0017] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating directions or positional relationships, are based on the orientation or positional relationships in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or case referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include more than one of those features. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0018] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integrated connections; they can refer to mechanical connections or point connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0019] Example 1: A circuit diagram for an aircraft cooling effect sensor, see [link / reference]. Figure 1 It includes a power supply circuit module, an excitation circuit module, a sensing element module, a control circuit module, and an output circuit module. The power supply circuit module provides power to the excitation circuit module, the control circuit module, and the output circuit module. The output terminal of the excitation circuit module is connected to the input terminal of the sensing element module. The sensing element module senses the external temperature and changes its output voltage. The output terminal of the sensing element module is connected to the input terminal of the control circuit module. The control circuit module calculates the voltage output by the sensing element module based on a constant temperature difference algorithm, obtains the temperature-related voltage and the flow-related voltage, and sends them to the output circuit module. The output circuit module obtains the adjustable constant current source circuit input voltage and sends it to the excitation circuit module for flow excitation.

[0020] Furthermore, the excitation circuit module includes a parallel micro constant current source circuit and an adjustable current source circuit. The micro constant current source circuit outputs a small current It with a constant amplitude, and the adjustable constant current source circuit outputs a current Iw with an adjustable amplitude. Among them, Iw=KfUf Iw is the amplitude of the output current of the adjustable constant current source circuit; Kf is the proportional coefficient; Uf is the input voltage of the adjustable constant current source circuit.

[0021] Furthermore, the sensitive element module includes platinum resistors Rt and Rw connected in parallel. The input terminal of platinum resistor Rt is connected to the output terminal of the micro constant current source circuit, and the input terminal of platinum resistor Rw is connected to the output terminal of the adjustable constant current source circuit. Platinum resistor Rt outputs voltage Ut, and platinum resistor Rw outputs voltage Uw.

[0022] Furthermore, the control circuit module includes a first voltage sampling circuit, a second voltage sampling circuit, and a microprocessor. The input terminal of the first voltage sampling circuit is connected to the output terminal of the platinum resistance Rt, and the input terminal of the second voltage sampling circuit is connected to the output terminal of the platinum resistance Rw. The Vt output by the first voltage sampling circuit and the Vw output by the second voltage sampling circuit are input to the microprocessor. After calculation by the microprocessor, the temperature-related voltage U1, the flow-related voltage U2, and the input voltage Uf of the adjustable constant current source circuit are obtained.

[0023] Furthermore, the output circuit module includes a temperature output circuit and a flow output circuit connected in parallel. The input terminal of the temperature output circuit receives a temperature-related voltage U1 and outputs a voltage Ua. The input terminal of the flow output circuit receives a flow-related voltage U2 and outputs a voltage Ub.

[0024] Furthermore, the platinum resistance Rt is a platinum resistance in the range of 300~2000Ω, and the platinum resistance Rw is a platinum resistance in the range of 20~100Ω.

[0025] A method for operating a high-precision cooling effect sensor under high flow rate conditions, using the aforementioned high-precision cooling effect sensor under high flow rate conditions, wherein the method for the microprocessor to calculate the input voltage of the adjustable constant current source circuit is as follows: Uf(s) = (Ki + Kp / s) (Tw - Tt) Tw=KwVw+Dw Tt=KtVt+Dt Where s is the Laplace transform operator; Tw is the temperature of the platinum resistance thermometer Rw; Tt is the temperature of the platinum resistance Rt; Ki, Kp (obtained through experimental calibration), Kw, and Kt are proportionality coefficients; Dw and Dt are bias coefficients. Ki and Kp were obtained through experimental calibration. Kt and Dt are related to the output current of the micro constant current source circuit of the excitation circuit module, while Kw and Dw are related to the output of the adjustable current source circuit of the excitation circuit module.

[0026] Furthermore, the method for the microprocessor to calculate the temperature-related voltage and the flow-related voltage is as follows: U1=f(Vt) U2=g(Vw)h(Vt) f(), g(), and h() are injective mappings (obtained through experimental calibration).

[0027] Furthermore, the method for outputting voltage Ua through temperature-dependent voltage U1 is as follows: Ua=Ka U1+Da The method for outputting voltage Ub through the flow-related voltage U2 is as follows: Ub = Kb U2 + Db Ka and Kb are proportionality coefficients; Da and Db are bias coefficients; Ka, Kb, Da, and Db are all derived from the voltage range that the aircraft system needs to identify.

[0028] Based on the above analysis and parameter calculations, the circuit design for the aircraft cooling effect sensor can be completed.

[0029] Example 2: A circuit for a cooling effect sensor on an aircraft is characterized by comprising a power supply circuit module, an excitation circuit module, a sensing element module, a control circuit module, and an output circuit module. The output terminal of the power supply circuit module is connected to the input terminals of the excitation circuit module, the control circuit module, and the output circuit module; the output terminal of the excitation circuit module is connected to the input terminal of the sensing element module; the output terminal of the sensing element is connected to the input terminal of the control circuit module; and the output terminal of the control circuit module is connected to the input terminal of the adjustable current source of the excitation circuit module and the input terminal of the output circuit module.

[0030] The excitation circuit module consists of a micro constant current source circuit and an adjustable constant current source circuit. The micro constant current source circuit outputs a small current It with a constant amplitude, and the adjustable constant current source circuit outputs a current Iw with an adjustable amplitude.

[0031] The amplitude of the output current of the adjustable constant current source circuit is determined by the following formula: Iw=KfUf In the formula: Iw is the amplitude of the current output by the adjustable constant current source circuit; Kf is the proportionality coefficient; Uf is the input of the adjustable constant current source circuit.

[0032] The sensitive element module consists of a platinum resistance resistor Rt and a platinum resistance resistor Rw. The input of the platinum resistance resistor Rt is It, and the output is voltage Ut, which is connected to the input terminal of voltage sampling circuit 1. The input of the platinum resistance resistor Rw is Iw, and the output is voltage Uw, which is connected to the input terminal of voltage sampling circuit 2.

[0033] The control circuit module consists of a voltage sampling circuit 1, a voltage sampling circuit 2, and a microprocessor. The input of voltage sampling circuit 1 is Ut, and the output is voltage Vt, which is connected to the input terminal 1 of the microprocessor. The input of voltage sampling circuit 2 is Uw, and the output is Vw, which is connected to the input terminal 2 of the microprocessor. The inputs of the microprocessor are Vt and Vw, and the outputs are voltages Uf, U1, and U2. Uf is connected to the input terminal of the adjustable constant current source circuit, U1 is connected to the input terminal of the temperature output circuit, and U2 is connected to the input terminal of the flow output circuit.

[0034] The microprocessor uses a constant temperature difference algorithm. The microprocessor's outputs—voltage Uf, voltage U1, and voltage U2—are determined by the following formulas: Uf(s)=(Ki+Kp / s)*(Tw-Tt) Tw=KwVw+Dw Tt=KtVt+Dt U1=f(Vt) U2=g(Vw)h(Vt) In the formula: s is the Laplace transform operator; Tw is the temperature of the platinum resistance thermometer Rw; Tt is the temperature of the platinum resistance Rt; Ki, Kp, Kw, and Kt are proportionality coefficients; Dw and Dt are bias coefficients; f(), g(), and h() are injective mappings.

[0035] The output circuit module consists of a temperature output circuit and a flow output circuit. The temperature output circuit has U1 as its input and voltage Ua as its output, while the flow output circuit has U2 as its input and voltage Ub as its output.

[0036] The voltages Ua and Ub are determined by the following formula: Ua=Ka*U1+Da Ub = Kb * U² + Db In the formula: Ka and Kb are proportionality coefficients; Da and Db are bias coefficients.

[0037] The current in the platinum resistance Rt is a tiny constant current, and the heat generated by the platinum resistance Rt itself is negligible, so the temperature of the platinum resistance Rt will not exceed the ambient temperature.

[0038] The above description is merely illustrative of the technical solutions of this invention. Those skilled in the art can modify or make equivalent substitutions to the technical solutions of this invention. All modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A high-precision cooling effect sensor under large flow conditions, characterized by, It includes a power supply circuit module, an excitation circuit module, a sensing element module, a control circuit module, and an output circuit module. The power supply circuit module provides power to the excitation circuit module, the control circuit module, and the output circuit module. The output terminal of the excitation circuit module is connected to the input terminal of the sensing element module. The sensing element module senses the external temperature and changes its output voltage. The output terminal of the sensing element module is connected to the input terminal of the control circuit module. The control circuit module calculates the voltage output by the sensing element module based on a constant temperature difference algorithm, obtains the temperature-related voltage and the flow-related voltage, and sends them to the output circuit module. The output circuit module obtains the adjustable constant current source circuit input voltage and sends it to the excitation circuit module for flow excitation.

2. The high-precision cooling effect sensor under large flow conditions according to claim 1, characterized in that, The excitation circuit module includes a parallel micro constant current source circuit and an adjustable current source circuit. The micro constant current source circuit outputs a small current It with a constant amplitude, and the adjustable constant current source circuit outputs a current Iw with an adjustable amplitude. Where Iw=Kf*Uf Iw is the amplitude of the output current of the adjustable constant current source circuit; Kf is the proportional coefficient; Uf is the input voltage of the adjustable constant current source circuit.

3. The high-accuracy cooling effect sensor under large flow conditions according to claim 1, characterized by The sensitive element module includes a platinum resistor Rt and a platinum resistor Rw connected in parallel. The input terminal of the platinum resistor Rt is connected to the output terminal of the micro constant current source circuit, and the input terminal of the platinum resistor Rw is connected to the output terminal of the adjustable constant current source circuit. The platinum resistance resistor Rt outputs voltage Ut, and the platinum resistance resistor Rw outputs voltage Uw.

4. The high-accuracy cooling effect sensor under large flow conditions according to claim 3, characterized by The control circuit module includes a first voltage sampling circuit, a second voltage sampling circuit, and a microprocessor. The input terminal of the first voltage sampling circuit is connected to the output terminal of the platinum resistance resistor Rt, and the input terminal of the second voltage sampling circuit is connected to the output terminal of the platinum resistance resistor Rw. The Vt output by the first voltage sampling circuit and the Vw output by the second voltage sampling circuit are input to the microprocessor. After calculation by the microprocessor, the temperature-related voltage U1, the flow-related voltage U2, and the input voltage Uf of the adjustable constant current source circuit are obtained.

5. The high-accuracy cooling effect sensor under large flow conditions according to claim 4, characterized by The output circuit module includes a temperature output circuit and a flow output circuit connected in parallel. The input terminal of the temperature output circuit receives a temperature-related voltage U1 and outputs a voltage Ua. The input terminal of the flow output circuit receives a flow-related voltage U2 and outputs a voltage Ub.

6. The high-accuracy cooling effect sensor under large flow conditions according to claim 3, characterized by Platinum resistance thermometers Rt are in the 300~2000Ω range, and platinum resistance thermometers Rw are in the 20~100Ω range.

7. A method of operating a high-precision cooling-effect sensor under high-flow conditions, characterized in that Using a high-precision cooling effect sensor under high flow conditions as described in claim 4 or 5, the method for a microprocessor to calculate the input voltage of an adjustable constant current source circuit is as follows: Uf(s) = (Ki + Kp / s)(Tw - Tt) Tw=KwVw+Dw Tt=KtVt+Dt Where s is the Laplace transform operator; Tw is the temperature of the platinum resistance thermometer Rw; Tt is the temperature of the platinum resistance Rt; Ki, Kp, Kw, and Kt are proportionality coefficients; Dw and Dt are bias coefficients. Ki and Kp were obtained through experimental calibration. Kt and Dt are related to the output current of the micro constant current source circuit of the excitation circuit module, while Kw and Dw are related to the output of the adjustable current source circuit of the excitation circuit module.

8. A method of operating a high-precision cooling-effect sensor under high-flow conditions, characterized in that Using the high-precision cooling effect sensor under high flow conditions as described in claim 5, the method for a microprocessor to calculate the temperature-related voltage and the flow-related voltage is as follows: U1=f(Vt) U2=g(Vw)h(Vt) f(), g(), and h() are injective mappings.

9. The working method of a high-precision cooling effect sensor under high flow rate conditions according to claim 7, characterized in that, The method for outputting voltage Ua through temperature-dependent voltage U1 is as follows: Ua=KaU1+Da The method for outputting voltage Ub through the flow-related voltage U2 is as follows: Ub=KbU2+Db Ka and Kb are proportionality coefficients; Da and Db are bias coefficients; Ka, Kb, Da, and Db are all derived from the voltage range that the aircraft system needs to identify.

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