Circuit, method and equipment for detecting medium temperature in a thermal gas mass flow meter

Abstract

This invention discloses a medium temperature detection circuit for a thermal gas mass flow meter. It includes a bridge module and a temperature-sensing resistor. The bridge module is connected to the temperature-sensing resistor and is used to measure the flow rate information of the thermal gas mass flow meter. The bridge module includes a first bridge arm and a second bridge arm. The first bridge arm is connected to the temperature-sensing resistor at a first intermediate node, and the second end of the temperature-sensing resistor is connected to a ground terminal. The second bridge arm includes a voltage adjustment unit and a first voltage divider network, which are connected to a second intermediate node. The voltage adjustment unit is used to reduce the voltage signal at the second intermediate node. A detection module is connected to both the first and second intermediate nodes. The detection module is used to detect the voltage signals at the first and second intermediate nodes and calculate the temperature information of the temperature-sensing resistor. The technical solution provided by this invention improves the calculation accuracy of the thermal gas mass flow meter.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to the technical field of thermal gas mass flow detection, in particular to a medium temperature detection circuit, method and equipment of a thermal gas mass flow meter. BACKGROUND

[0002] The thermal gas mass flow meter is widely applied to the control and measurement of gas flow in the nuclear power field, and the gas flow is calculated by the proportional relationship between the heat loss of the heating object and the flow of the fluid when the fluid flows through the heating object. In the process of calculating the flow or the flow rate, the medium temperature is approximated by a fixed value in most current constant temperature difference thermal gas mass flow meters, so that the measurement accuracy of the thermal gas mass flow meter is poor under different working conditions. SUMMARY

[0003] The embodiment of the present application provides a medium temperature detection circuit, method and equipment of a thermal gas mass flow meter, so as to solve the problem of poor measurement accuracy of the thermal gas mass flow meter under different working conditions.

[0004] According to an aspect of the present application, a medium temperature detection circuit of a thermal gas mass flow meter is provided, which comprises:

[0005] A bridge module and a temperature measuring resistor, the bridge module is connected with the temperature measuring resistor, and the bridge module and the temperature measuring resistor are used for measuring the flow information of the thermal gas mass;

[0006] The bridge module comprises a first bridge arm and a second bridge arm; the first bridge arm is connected with the temperature measuring resistor at a first intermediate node, and a second end of the temperature measuring resistor is connected with a ground end; the second bridge arm comprises a voltage adjusting unit and a first voltage dividing network, and the voltage adjusting unit and the first voltage dividing network are connected at a second intermediate node; the voltage adjusting unit is used for reducing the voltage signal of the second intermediate node;

[0007] A detection module, the detection module is connected with the first intermediate node and the second intermediate node, and the detection module is used for detecting the voltage signals of the first intermediate node and the second intermediate node and calculating the temperature information of the temperature measuring resistor.

[0008] Optionally, the bridge module further comprises:

[0009] A third bridge arm and a fourth bridge arm, the first bridge arm and the second bridge arm are connected at a first node, the second bridge arm and the third bridge arm are connected at a second node, the third bridge arm and the fourth bridge arm are connected at a third node, and the fourth bridge arm and the first bridge arm are connected at the ground end.

[0010] Optionally, the voltage adjusting unit comprises:

[0011] A second voltage dividing network and a constant voltage driving subunit;

[0012] The first end of the second voltage dividing network is connected with the second node, the second end of the second voltage dividing network is connected with the first end of the constant voltage driving subunit, and the third end of the second voltage dividing network is grounded; the second end of the constant voltage driving subunit is connected with the second intermediate node, and the third end of the constant voltage driving subunit is connected with the second node; the second voltage dividing network is used for dividing the voltage signal of the second node to generate the first voltage dividing information;

[0013] The constant voltage driving subunit is used for adjusting the amplitude of the voltage signal output by the second end of the constant voltage driving subunit according to the first voltage dividing information and the voltage signal of the second node, so as to reduce the voltage signal of the second intermediate node.

[0014] Optionally, the second voltage dividing network comprises a first resistor and a second resistor, the first end of the first resistor is connected with the second node, the second end of the second resistor is grounded, and the second end of the first resistor is connected with the first end of the second resistor and the first end of the constant voltage driving subunit.

[0015] Optionally, the constant voltage driving subunit comprises a first amplifying component and a switching component, the noninverting input end of the first amplifying component is connected with the second end of the second voltage dividing network, the inverting input end of the first amplifying component is connected with the second end of the switching component, and the output end of the first amplifying component is connected with the control end of the switching component.

[0016] The first end of the switching component is connected with the second node.

[0017] The first amplifying component is used for processing the signals input by the noninverting input end and the inverting input end and outputting the processed voltage signal.

[0018] The switching component is used for adjusting the voltage signal of the inverting input end of the first amplifying component according to the processed voltage signal, so as to control the voltage signal of the second intermediate node to be reduced to a preset threshold value.

[0019] Optionally, the constant voltage driving subunit further comprises:

[0020] a third resistor, a fourth resistor and a first capacitor.

[0021] The inverting input end of the first amplifying component is connected with the first end of the first capacitor and the first end of the fourth resistor, and the output end of the first amplifying component is connected with the second end of the first capacitor and the first end of the third resistor.

[0022] The second end of the third resistor is connected with the control end of the switching component, and the second end of the fourth resistor is connected with the second end of the switching component and the second intermediate node.

[0023] Optionally, the first bridge arm further comprises:

[0024] A third voltage dividing network, a first end of the third voltage dividing network is connected to the first intermediate node and a second end of the third voltage dividing network is connected to the first node.

[0025] Optionally, the first voltage dividing network comprises a fifth resistor and a sixth resistor, a first end of the fifth resistor and a first end of the sixth resistor are connected to the first node, and a second end of the fifth resistor and a second end of the sixth resistor are connected to the second intermediate node.

[0026] The third voltage dividing network comprises a seventh resistor and an eighth resistor, a first end of the seventh resistor and a first end of the eighth resistor are connected to the first intermediate node, and a second end of the seventh resistor and a second end of the eighth resistor are connected to the first node.

[0027] Optionally, the detection module comprises:

[0028] The first calculation unit, a first end of the first calculation unit is connected to the second intermediate node, a second end of the first calculation unit is grounded, and an output end of the first calculation unit is connected to the first detection end.

[0029] The second calculation unit, a first end of the second calculation unit is connected to the second intermediate node, a second end of the second calculation unit is connected to the first end of the temperature resistance, and an output end of the second calculation unit is connected to the second detection end; wherein the first detection end is used to detect first voltage information of the output end of the first calculation unit; and the second detection end is used to detect second voltage information of the output end of the second calculation unit.

[0030] The first calculation unit is used to detect voltage information of the second intermediate node.

[0031] The second calculation unit is used to detect voltage information of the first intermediate node.

[0032] Optionally, the second calculation unit comprises a ninth resistor and a tenth resistor, a first end of the ninth resistor is connected to the first end of the temperature resistance, a second end of the ninth resistor is connected to a first end of the tenth resistor, and a second end of the tenth resistor is grounded; the ninth resistor and the tenth resistor are used to calculate a current of the temperature resistance; wherein the current of the temperature resistance is calculated by the following formula:

[0033]

[0034] wherein U1 is voltage of the second intermediate node, U2 is voltage of the first intermediate node, R64 is resistance value of the fifth resistor, R66 is resistance value of the sixth resistor, R32 is resistance value of the seventh resistor, R65 is resistance value of the eighth resistor, R54 is resistance value of the ninth resistor, R52 is resistance value of the tenth resistor, I RT is the current of the temperature resistance.

[0035] Optionally, impedance information of the temperature resistance is calculated by the following formula:

[0036]

[0037] The temperature information of the temperature measuring resistor is calculated by the following formula:

[0038]

[0039] Wherein, R T is the resistance value of the temperature measuring resistor at the current temperature, R0 is the resistance value of the temperature measuring resistor at 0℃, is the temperature coefficient of the temperature measuring resistor, and T is the temperature information of the temperature measuring resistor.

[0040] In a second aspect, the present application provides a medium temperature calculation method of a thermal gas mass flowmeter, which is executed by a medium temperature detection circuit of the thermal gas mass flowmeter, and comprises the following steps:

[0041] The voltage signal of the second intermediate node is reduced by the voltage adjusting unit arranged on the second bridge arm of the bridge module;

[0042] The voltage signals of the first intermediate node and the second intermediate node are detected by the detection module, and the temperature information of the temperature measuring resistor is calculated;

[0043] The flow information of the thermal gas mass is measured by the bridge module according to the temperature information of the temperature measuring resistor;

[0044] Wherein, the bridge module is connected with the temperature measuring resistor, the bridge module comprises a first bridge arm and a second bridge arm; the first bridge arm is connected with the temperature measuring resistor at the first intermediate node, and the second end of the temperature measuring resistor is connected to the ground end; the second bridge arm comprises a voltage adjusting unit and a first voltage dividing network, and the voltage adjusting unit and the first voltage dividing network are connected to the second intermediate node.

[0045] In a third aspect, the present application provides a detection device of a thermal gas mass flowmeter, which comprises the medium temperature detection circuit of the thermal gas mass flowmeter according to any one of the above.

[0046] The medium temperature detection circuit of the thermal gas mass flowmeter provided by the embodiment of the present application comprises a bridge module, a temperature measurement resistor and a detection module. The bridge module comprises a first bridge arm and a second bridge arm, and the second bridge arm comprises a voltage adjustment unit and a first voltage division network. After a voltage signal is input into the bridge module, the voltage adjustment unit reduces the voltage signal of the input circuit and outputs the voltage signal to the first voltage division network. The voltage signal is divided by the first voltage division network and then output to the temperature measurement resistor. The detection module detects the voltage signals of the first intermediate node and the second intermediate node, and calculates the temperature information of the temperature measurement resistor according to the voltage signals of the first intermediate node and the second intermediate node. The voltage signal between the temperature measurement resistor is reduced by the voltage adjustment unit, so that the heat generation of the temperature measurement resistor is reduced, and the temperature rise of the temperature measurement resistor is reduced. The temperature information of the temperature measurement resistor can be used to perform thermal compensation on the process of calculating the flow or flow rate, so that the calculation accuracy is improved, and the error reduction effect is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments of the present application will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of the contents of the embodiments of the present application and the drawings.

[0048] Figure 1 is a schematic diagram of a medium temperature detection circuit of a thermal gas mass flowmeter provided by the embodiment of the present application;

[0049] Figure 2 is a schematic diagram of another medium temperature detection circuit of a thermal gas mass flowmeter provided by the embodiment of the present application;

[0050] Figure 3 is a circuit schematic diagram of a detection module provided by the embodiment of the present application;

[0051] Figure 4 is a flow chart of a medium temperature calculation method of a thermal gas mass flowmeter provided by the embodiment of the present application;

[0052] Figure 5 is a schematic diagram of a detection device of a thermal gas mass flowmeter provided by the embodiment of the present application. DETAILED DESCRIPTION

[0053] The present application will be further described in detail below in combination with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. In addition, it should be noted that, in order to facilitate the description, only the parts related to the present application are shown in the drawings, but not all the structures.

[0054] In the constant temperature differential gas mass flowmeter, two measuring resistors are used, one for measuring medium temperature and the other for measuring medium flow rate, the constant temperature differential thermal gas mass flowmeter is based on the hardware Wheatstone bridge to realize the regulation of constant temperature difference, the mass flow rate or mass flow of fluid satisfies King's law with the heat taken away by the fluid flowing through the thermal sensor or wherein, Delta T is the temperature difference, P is the heat taken away, u m is the mass flow rate, q m is the mass flow, k1, k2, k3 are coefficients, k1, k2, k3 will change in the case that the temperature change of the temperature measuring resistor is large, thereby causing a large error of the measurement result of the flowmeter.

[0055] Figure 1 is a medium temperature detection circuit schematic diagram of the thermal gas mass flowmeter provided by the embodiment of the present application. Referring to Figure 1 , the medium temperature detection circuit of the thermal gas mass flowmeter provided by the embodiment of the present application comprises a bridge module 60 and a temperature measuring resistor R T , the bridge module 60 is connected with the temperature measuring resistor R T , and the bridge module 60 and the temperature measuring resistor R T are used for measuring the flow information of the thermal gas mass. The bridge module 60 comprises a first bridge arm 61 and a second bridge arm 62; the first bridge arm 61 is connected with the temperature measuring resistor R T at a first intermediate node U2, and a second end of the temperature measuring resistor R T is connected with a ground terminal; the second bridge arm 62 comprises a voltage adjusting unit 10 and a first voltage dividing network 20, and the voltage adjusting unit 10 and the first voltage dividing network 20 are connected with a second intermediate node U1; the voltage adjusting unit 10 is used for reducing the voltage signal of the second intermediate node U1. A detection module 30 is connected with the first intermediate node U2 and the second intermediate node U1, and the detection module 30 is used for detecting the voltage signals of the first intermediate node U2 and the second intermediate node U1 and calculating the temperature information of the temperature measuring resistor R T .

[0056] Specifically, the bridge module 60 is a circuit for measuring resistor, which can comprise a plurality of bridge arms, the temperature measuring resistor R T is used for measuring the temperature of gas, and the detection module 30 is connected with the bridge module 60 in parallel, which is used for detecting the voltage signals of the first intermediate node U2 and the second intermediate node U1 and calculating the temperature information of the temperature measuring resistor R T after the bridge module 60 enters a steady state. The voltage adjusting unit 10 is used for reducing the size of the voltage signal input into the bridge module 60, and the voltage signal output from the bridge module 60 is reduced, thereby reducing the temperature of the temperature measuring resistor R TThe heat generation of the temperature measuring resistor R T The temperature influence is reduced, and the calculation accuracy of the mass flow rate or mass flow is improved. The first voltage dividing network 20 is used to reduce the output voltage signal and maintain the stability of the bridge module 60.

[0057] For example, when using the thermal gas mass flow meter, the voltage signal enters the second bridge arm 62 after inputting the bridge, and the voltage signal enters the first bridge arm 61 from the first voltage dividing network 20 after being reduced by the voltage adjusting module, and then enters the temperature measuring resistor R T T The temperature measuring resistor R T begins to work and measures the medium temperature. The detection module 30 is connected in parallel to the bridge module 60, measures the voltage signals of the first intermediate node U2 and the second intermediate node U1, and calculates the temperature information of the temperature measuring resistor R T The voltage signal entering the temperature measuring resistor R T The heat generation of the temperature measuring resistor R T begins to work and measures the medium temperature. The detection module 30 is connected in parallel to the bridge module 60, measures the voltage signals of the first intermediate node U2 and the second intermediate node U1, and calculates the temperature information of the temperature measuring resistor R T The voltage signal entering the temperature measuring resistor R T The heat generation of the temperature measuring resistor R

[0058] The medium temperature detection circuit of the thermal gas mass flow meter provided by the embodiment includes a bridge module, a temperature measuring resistor, and a detection module. The bridge module includes a first bridge arm and a second bridge arm, and the second bridge arm includes a voltage adjusting unit and a first voltage dividing network. After the voltage signal is input into the bridge module, the voltage adjusting unit reduces the voltage signal of the input circuit and outputs it to the first voltage dividing network. The voltage signal is divided by the first voltage dividing network and then output to the temperature measuring resistor. The detection module detects the voltage signals of the first intermediate node and the second intermediate node, and calculates the temperature information of the temperature measuring resistor according to the voltage signals of the first intermediate node and the second intermediate node. The voltage adjusting unit reduces the voltage signal between the temperature measuring resistor, reduces the heat generation of the temperature measuring resistor, and reduces the temperature rise of the temperature measuring resistor. The temperature information of the temperature measuring resistor can be used to heat compensate the process of calculating the flow rate or flow rate, improve the calculation accuracy, and reduce the error effect.

[0059] Optionally, on the basis of the above embodiment, continuing to refer to Figure 1The bridge module 60 further comprises a third bridge arm 63 and a fourth bridge arm 64, the first bridge arm 61 and the second bridge arm 62 are connected to a first node U3, the second bridge arm 62 and the third bridge arm 63 are connected to a second node U0, the third bridge arm 63 and the fourth bridge arm 64 are connected to a third node U4, and the fourth bridge arm 64 and the first bridge arm 61 are connected to a ground terminal.

[0060] Specifically, the bridge module 60 further comprises a third bridge arm 63 and a fourth bridge arm 64, the first bridge arm 61, the second bridge arm 62, the third bridge arm 63 and the fourth bridge arm 64 form a Wheatstone bridge. The Wheatstone bridge can utilize the change of resistance to measure the change of physical quantity, and the voltage signals of the first intermediate node U2 and the second intermediate node U1 can be collected to calculate the temperature measuring resistance R T The medium temperature detection circuit of the thermal gas mass flowmeter further comprises a steady-state resistance R62 and a speed measuring resistance R H The steady-state resistance R62 is used to participate in maintaining the steady state of the bridge, and the speed measuring resistance R H is used to measure the flow rate of the medium, and together with the medium temperature, is used to calculate the flow rate or the flow rate of the thermal gas.

[0061] Optionally, Figure 2 is another medium temperature detection circuit schematic diagram of a thermal gas mass flowmeter provided by the embodiment of the present application. Based on the above-mentioned embodiment, referring to Figure 2 , the voltage regulation unit 10 provided by the embodiment comprises a second voltage dividing network 40 and a constant voltage driving sub-unit 50, the first end of the second voltage dividing network 40 is connected to the second node U0, the second end of the second voltage dividing network 40 is connected to the first end of the constant voltage driving sub-unit 50, and the third end of the second voltage dividing network 40 is grounded. The second end of the constant voltage driving sub-unit 50 is connected to the second intermediate node U1, and the third end of the constant voltage driving sub-unit 50 is connected to the second node U0. The second voltage dividing network 40 is used to divide the voltage signal of the second node U0 to generate first voltage division information, and the constant voltage driving sub-unit 50 is used to adjust the amplitude of the voltage signal output by the second end of the constant voltage driving sub-unit 50 according to the first voltage division information and the voltage signal of the second node U0, so as to reduce the voltage signal of the second intermediate node U1.

[0062] Specifically, the voltage regulating unit 10 can include a second voltage dividing network 40 and a constant voltage driving subunit 50. The second voltage dividing network 40 can regulate the size of the voltage signal input to the constant voltage driving subunit 50. The voltage signal of the second node U0 is input to the second voltage dividing network 40 after entering the bridge module 60, and the second voltage dividing network 40 divides the voltage signal to generate first voltage dividing information. The first voltage dividing information is the voltage signal after being divided by the second voltage dividing network 40, which is smaller than the voltage signal input by the second node U0. The constant voltage driving subunit 50 adjusts the voltage signal output by the second end of the constant voltage driving subunit 50 according to the first voltage dividing information and the voltage signal of the second node U0, so that the voltage signal output by the second end of the constant voltage driving subunit 50 to the second intermediate node U1 is the same as the first voltage dividing information, that is, the voltage signal of the second intermediate node U1 is reduced.

[0063] Optionally, on the basis of the above embodiment, continuing to refer to Figure 2 , the second voltage dividing network 40 includes a first resistor R21 and a second resistor R24. The first end of the first resistor R21 is connected with the second node U0, the second end of the second resistor R24 is grounded, and the second end of the first resistor R21 is connected with the first end of the second resistor R24 and the first end of the constant voltage driving subunit 50.

[0064] Specifically, the resistance values of the first resistor R21 and the second resistor R24 are adjustable. After the voltage signal is input to the second voltage dividing network 40 from the second node U0, the voltage signal is divided according to the resistance ratio of the first resistor R21 and the second resistor R24, and the voltage signal input to the constant voltage driving subunit 50 from the first resistor R21 is the first voltage dividing information. According to the resistance ratio of the first resistor R21 and the second resistor R24, the size of the first voltage dividing information can be adjusted, and then the heat generation of the temperature measuring resistor R T is adjusted.

[0065] Optionally, on the basis of the above embodiment, continuing to refer to Figure 2 , the constant voltage driving subunit 50 includes a first amplification component 11 and a switching component 12. The non-inverting input end of the first amplification component 11 is connected with the second end of the second voltage dividing network 40, the inverting input end of the first amplification component 11 is connected with the second end of the switching component 12, and the output end of the first amplification component 11 is connected with the control end of the switching component 12. The first end of the switching component 12 is connected with the second node U0. The first amplification component 11 is used to process the signals input by the non-inverting input end and the inverting input end, and output the processed voltage signal. The switching component 12 is used to adjust the voltage signal of the inverting input end of the first amplification component 11 according to the processed voltage signal, so as to control the voltage signal of the second intermediate node U1 to be reduced to a preset threshold value.

[0066] Specifically, the first amplification component 11 is configured to adjust the output processed voltage signal according to the voltage signals input from the in-phase input end and the reverse input end, so that the final output voltage signal is of a preset threshold value. The voltage signal output from the first amplification component 11 can control the on and off of the switch component 12, and then the switch component 12 adjusts the voltage signal of the reverse input end of the first amplification component 11 to control the voltage signal of the second intermediate node U1 to decrease to the preset threshold value. The preset threshold value is a preset voltage signal value, and when the voltage signal is lower than the preset threshold value, the temperature of the temperature measuring resistor R T has less influence. For example, at the beginning of power-on, the voltage signal is input to the in-phase input end of the first amplification component 11, at this time the voltage of the in-phase input end is greater than that of the reverse input end, the voltage signal is amplified by the first amplification component 11, and after being output from the output end, the switch component 12 is controlled to be turned on, the voltage signal is input to the first amplification component 11 from the reverse input end through the switch component 12, resulting in that the voltage signal output from the first amplification component 11 is reduced. This process is repeated until the voltage signal of the in-phase input end is equal to that of the reverse input end, at this time the size of the voltage signal is the preset threshold value, and the voltage signal can be output to the second intermediate node U1.

[0067] Optionally, on the basis of the above embodiment, referring to Figure 2 , the constant voltage driving subunit 50 further comprises a third resistor R23, a fourth resistor R25 and a first capacitor C1, the reverse input end of the first amplification component 11 is connected with the first end of the first capacitor C1 and the first end of the fourth resistor R25, and the output end of the first amplification component 11 is connected with the second end of the first capacitor C1 and the first end of the third resistor R23. The second end of the third resistor R23 is connected with the control end of the switch component 12, and the second end of the fourth resistor R25 is connected with the second end of the switch component 12 and the second intermediate node U1.

[0068] Specifically, the third resistor R23 and the fourth resistor R25 are current limiting resistors, which are configured to limit the circuit current, the current output from the first amplification component 11 is input to the control end of the switch component 12 through the third resistor R23, and the current output from the output end of the switch component 12 is input to the reverse input end of the first amplification component 11 through the fourth resistor R25. When the voltage signal of the in-phase input end of the first amplification component 11 is equal to that of the reverse input end, the voltage signal output from the output end is output to the second intermediate node U1 through the first capacitor C1.

[0069] Optionally, on the basis of the above embodiment, referring to Figure 2 , the first bridge arm 61 comprises a third voltage dividing network 70, the first end of the third voltage dividing network 70 is connected with the temperature measuring resistor R T , and the second end of the third voltage dividing network 70 is connected with the first node U3.

[0070] Specifically, the first bridge arm 61 includes a third voltage dividing network 70, the voltage signal output from the second intermediate node U1 is output to the temperature measuring resistor R T The third voltage dividing network 70 is used to further reduce the voltage signal input to the first intermediate node U2, so as to maintain the stability of the bridge module 60.

[0071] Optionally, on the basis of the above embodiment, continuing to refer to Figure 2 The first voltage dividing network 20 includes a fifth resistor R32 and a sixth resistor R65, the first end of the fifth resistor R32 and the first end of the sixth resistor R65 are connected with the first node U3, and the second end of the fifth resistor R32 and the second end of the sixth resistor R65 are connected with the second intermediate node U1. The third voltage dividing network 70 includes a seventh resistor R64 and an eighth resistor R66, the first end of the seventh resistor R64 and the first end of the eighth resistor R66 are connected with the temperature measuring resistor R T The second end of the seventh resistor R64 and the second end of the eighth resistor R66 are connected with the first node U3.

[0072] Specifically, the voltage signal is output from the second intermediate node U1, then is divided by the parallel connection of the fifth resistor R32 and the sixth resistor R65, and then is output to the first node U3, and then is divided by the parallel connection of the seventh resistor R64 and the eighth resistor R66, and then is output to the temperature measuring resistor R T At this time, the voltage signal of the temperature measuring resistor is at a low level, and the temperature measuring resistor R T In the case of low voltage, the heat generation is also reduced, and the influence on the calculation of the thermal gas mass flowmeter is also reduced, thereby improving the calculation accuracy.

[0073] For example, when the bridge enters a steady state, the following relationship is satisfied:

[0074]

[0075] Wherein, R62 is the resistance value of the steady-state resistor, R64 is the resistance value of the fifth resistor, R66 is the resistance value of the sixth resistor, R32 is the resistance value of the seventh resistor, R65 is the resistance value of the eighth resistor, R T is the resistance value of the current temperature measuring resistor, and R H is the resistance value of the speed measuring resistor.

[0076] Optionally, Figure 3 is a circuit schematic diagram of a detection module provided by an embodiment of the present application. On the basis of the above embodiment, referring to Figure 3, the detection module 30 can include a first computing unit 31, a first end of the first computing unit 31 is connected with the second intermediate node U1, a second end of the first computing unit 31 is grounded, and an output end of the first computing unit 31 is connected with a first detection end. A second computing unit 32, a first end of the second computing unit 32 is connected with the second intermediate node U1, a second end of the second computing unit 32 is connected with a first end of a temperature measurement resistor RT, and an output end of the second computing unit 32 is connected with a second detection end; wherein the first detection end is used for detecting first voltage information of the output end of the first computing unit 31; and the second detection end is used for detecting second voltage information of the output end of the second computing unit 32. The first computing unit 31 is used for detecting voltage information of the second intermediate node U1, and the second computing unit 32 is used for detecting voltage information of the first intermediate node U2.

[0077] Specifically, the first computing unit 31 and the second computing unit 32 can be operational amplifier circuits, the first detection end of the first computing unit 31 detects the first voltage information of the output end of the first computing unit 31, and the relationship between the first voltage information and the voltage information of the second intermediate node U1 can be confirmed according to the calculation of the operational amplifier circuit; the second detection end of the second computing unit 32 detects the second voltage information of the output end of the second computing unit 32, and the relationship between the second voltage information and the voltage information of the first intermediate node U2 can be confirmed according to the calculation of the operational amplifier circuit, and then the voltage information of the second intermediate node U1 and the voltage information of the first intermediate node U2 are calculated.

[0078] Exemplarily, the first computing unit 31 satisfies the following relationship:

[0079] U1=V out1 (5)

[0080] The second computing unit 32 satisfies the following relationship:

[0081] 1.25U2-0.7833U1=V out2 (6)

[0082] According to the formula (5) and the formula (6), the following can be obtained:

[0083] U2=0.8V out2 +0.6267V out1 (7)

[0084] Wherein, U1 is the voltage of the second intermediate node, U2 is the voltage of the first intermediate node, V out1 is the first voltage information, and V out2 is the second voltage information. Since the first voltage information and the second voltage information can be directly measured, the voltage of the first intermediate node and the voltage of the second intermediate node can be obtained according to the formula (5), the formula (6) and the formula (7).

[0085] Optionally, on the basis of the above embodiments, in combination with Figure 1 , Figure 2 and Figure 3 , the second calculation unit 32 comprises a ninth resistor R54 and a tenth resistor R52, a first end of the ninth resistor R54 is connected with a first end of the temperature measuring resistor R T , a second end of the ninth resistor R54 is connected with a first end of the tenth resistor R52, and a second end of the tenth resistor R52 is grounded; the ninth resistor R54 and the tenth resistor R52 are used to calculate the current of the temperature measuring resistor R T ; wherein the current of the temperature measuring resistor R T is calculated by the following formula:

[0086]

[0087] Wherein U1 is the voltage of the second intermediate node, U2 is the voltage of the first intermediate node, R64 is the resistance value of the fifth resistor, R66 is the resistance value of the sixth resistor, R32 is the resistance value of the seventh resistor, R65 is the resistance value of the eighth resistor, R54 is the resistance value of the ninth resistor, R52 is the resistance value of the tenth resistor, and I RT is the current of the temperature measuring resistor.

[0088] Specifically, the voltage signal is output from the first intermediate node U2, passes through the ninth resistor R54 and the tenth resistor R52, and is finally grounded. The current of the temperature measuring resistor can be calculated by the circuit through which the voltage signal of the second intermediate node U1 passes. Formula (2) can be understood as the voltage of the second intermediate node U1 minus the voltage of the first intermediate node U2 divided by the sum of the parallel resistance value of the fifth resistor R64 and the sixth resistor R66 and the parallel resistance value of the seventh resistor R32 and the eighth resistor R65, minus the quotient of the voltage of the first intermediate node U2 divided by the sum of the ninth resistor R54 and the tenth resistor R52, which is the current of the temperature measuring resistor.

[0089] Optionally, the impedance information of the temperature measuring resistor is calculated by the following formula:

[0090]

[0091] The temperature information of the temperature measuring resistor is calculated by the following formula:

[0092]

[0093] Wherein R T is the resistance value of the temperature measuring resistor at the current temperature, R0 is the resistance value of the temperature measuring resistor at 0℃, is the temperature coefficient of the temperature measuring resistor, and T is the temperature information of the temperature measuring resistor.

[0094] Specifically, in formula (2), V out1V is the first voltage information out2 V is the second voltage information. According to the voltage of the first intermediate node U2 and the temperature measuring resistance R T , the current of the temperature measuring resistance R T , the impedance information of the temperature measuring resistance R T can be calculated. Formula (3) is the relationship between the resistance value of the temperature measuring resistance R T and the temperature information of the temperature measuring resistance R T , and the temperature information of the temperature measuring resistance R T can be obtained according to formula (3).

[0095] Optionally, Figure 4 is a medium temperature calculation method flowchart of a thermal gas mass flowmeter provided by an embodiment of the present application. In combination with Figure 1 , Figure 2 and Figure 3 , referring to Figure 4 , the medium temperature calculation method of the thermal gas mass flowmeter provided by the embodiment of the present application is executed by a detection circuit of a medium temperature of a thermal gas mass flowmeter, and includes:

[0096] S101, reducing the voltage signal of the second intermediate node by the voltage adjusting unit arranged on the second bridge arm of the bridge module.

[0097] Specifically, after the voltage signal is input into the bridge module 60, the voltage signal is weakened by the voltage adjusting module 10 on the second bridge arm 62, so that the voltage finally output to the second intermediate node U1 reaches a lower level.

[0098] S102, detecting the voltage signals of the first intermediate node and the second intermediate node by the detection module, and calculating the temperature information of the temperature measuring resistance.

[0099] Specifically, the detection module 30 detects the voltage information of the first intermediate node U2 and the voltage information of the second intermediate node U1, calculates the current of the temperature measuring resistance according to the voltage information of the first intermediate node U2 and the voltage information of the second intermediate node U2, calculates the impedance information of the temperature measuring resistance R T according to the current of the temperature measuring resistance R T and the voltage information of the first intermediate node U2, and finally calculates the temperature information of the temperature measuring resistance R T according to the relationship between the resistance value of the temperature measuring resistance R T and the temperature information of the temperature measuring resistance R T .

[0100] S103, measuring the flow information of the thermal gas mass by the bridge module according to the temperature information of the temperature measuring resistance.

[0101] Specifically, the flow information of the thermal gas mass is calculated by the King's law, and the flow information of the thermal gas mass is calculated according to the temperature information of the temperature measuring resistance R TTemperature information is used to compensate for the flow rate of the thermal gas mass, thereby further improving the calculation accuracy.

[0102] Among them, the bridge module 60 and the temperature measuring resistor R T The bridge module 60 includes a first bridge arm 61 and a second bridge arm 62; the first bridge arm 61 is connected to the temperature sensing resistor R. T The temperature measuring resistor R is connected to the first intermediate node U2. T The second end is connected to the ground end; the second bridge arm 62 includes a voltage regulation unit 10 and a first voltage divider network 20, the voltage regulation unit 10 and the first voltage divider network 20 being connected to the second intermediate node U1.

[0103] For example, when using a thermal gas mass flow meter, after the voltage signal is input to the bridge module 60, it enters the second voltage divider network 40 from the second bridge arm 62. The second voltage divider network 40 divides the voltage signal according to the resistance ratio of the first resistor R21 and the second resistor R24 ​​to generate the first voltage divider information. The first voltage divider information is input to the non-inverting input terminal of the first amplification component 11 and amplified and output. After being current-limited by the third resistor R23, the switching component 12 is turned on. The switching component 12 inputs a voltage signal to the inverting input terminal of the first amplification component 11 to reduce the output voltage until the voltage signal at the non-inverting input terminal is equal to the voltage signal at the inverting input terminal. At this time, the voltage signal reaches a preset threshold, and the voltage signal can be output to the second intermediate node U1.

[0104] The voltage signal is divided by 20 in the first voltage divider network and then enters the first bridge arm 61. After being divided by 70 in the third voltage divider network, it is output to the temperature sensing resistor R. T Temperature sensing resistor R T The system begins operation, measuring the temperature of the medium. The first calculation unit 31 and the second calculation unit 32 calculate the voltage information of the second intermediate node and the first intermediate node U2 based on the first and second voltage information output from the output terminals. They also calculate the temperature sensing resistor R based on the voltage information of the second intermediate node U1 and the first intermediate node U2. T The current, and then based on the temperature measuring resistor R T Calculate the temperature measuring resistor R based on the current and voltage information of the first intermediate node U2. T The impedance information is then used to determine the final impedance based on the temperature measuring resistor R. T The resistance value and the temperature measuring resistor R T Calculation of the relationship between temperature information and the thermometer resistor R T Temperature information.

[0105] Since the voltage signal entering the temperature measuring resistor is weakened, the heat generation of the temperature measuring resistor itself is reduced, the temperature change is small, the influence on the calculation of the thermal gas mass flowmeter is also reduced, and the calculation precision of the thermal gas mass flowmeter on the mass flow rate or mass flow is improved.

[0106] Optionally, Figure 5 is a schematic diagram of a detection device of a thermal gas mass flowmeter provided by an embodiment of the present application. Based on the above embodiments, referring to Figure 5 The detection device 200 of the thermal gas mass flowmeter provided by the embodiment of the present application comprises the medium temperature detection circuit 100 of the thermal gas mass flowmeter in any of the above embodiments. The beneficial effects of the medium temperature detection circuit 100 of the thermal gas mass flowmeter in any of the above embodiments are not repeated here.

[0107] Note that the above are only preferred embodiments of the present application and the technical principles applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and those skilled in the art can make various obvious changes, re-adjustments and substitutions without departing from the scope of the present application. Therefore, although the present application has been described in more detail through the above embodiments, the present application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the appended claims.

Claims

1. A medium temperature detection circuit of a thermal gas mass flowmeter, characterized by, The detection circuit comprises: a bridge module and a temperature measuring resistor, the bridge module being connected with the temperature measuring resistor, and the bridge module and the temperature measuring resistor being used for measuring flow information of a thermal gas mass; the bridge module comprises a first bridge arm and a second bridge arm; the first bridge arm is connected with the temperature measuring resistor at a first intermediate node, and a second end of the temperature measuring resistor is connected with a ground end; the second bridge arm comprises a voltage adjusting unit and a first voltage dividing network, and the voltage adjusting unit and the first voltage dividing network are connected at a second intermediate node; the voltage adjusting unit is used for reducing a voltage signal at the second intermediate node; a detection module, the detection module being connected with the first intermediate node and the second intermediate node, and the detection module being used for detecting voltage signals at the first intermediate node and the second intermediate node and calculating temperature information of the temperature measuring resistor; the voltage adjusting unit comprises: a second voltage dividing network and a constant voltage driving subunit; a first end of the second voltage dividing network is connected with a second node, a second end of the second voltage dividing network is connected with a first end of the constant voltage driving subunit, and a third end of the second voltage dividing network is grounded; a second end of the constant voltage driving subunit is connected with the second intermediate node, and a third end of the constant voltage driving subunit is connected with the second node; the second voltage dividing network is used for dividing a voltage signal at the second node to generate first voltage dividing information; the constant voltage driving subunit is used for adjusting an amplitude of a voltage signal output by the second end of the constant voltage driving subunit according to the first voltage dividing information and the voltage signal at the second node, so as to reduce the voltage signal at the second intermediate node; the constant voltage driving subunit comprises a first amplifying component and a switching component; a non-inverting input end of the first amplifying component is connected with the second end of the second voltage dividing network, an inverting input end of the first amplifying component is connected with a second end of the switching component, and an output end of the first amplifying component is connected with a control end of the switching component; a first end of the switching component is connected with the second node; the first amplifying component is used for processing signals input by the non-inverting input end and the inverting input end and outputting a processed voltage signal; the switching component is used for adjusting a voltage signal at the inverting input end of the first amplifying component according to the processed voltage signal, so as to control the voltage signal at the second intermediate node to be reduced to a preset threshold value.

2. The detection circuit of claim 1, wherein, The bridge module further comprises: a third bridge arm and a fourth bridge arm, the first bridge arm and the second bridge arm being connected at a first node, the second bridge arm and the third bridge arm being connected at a second node, the third bridge arm and the fourth bridge arm being connected at a third node, and the fourth bridge arm and the first bridge arm being connected at a ground end.

3. The detection circuit according to claim 1, wherein the second voltage dividing network comprises a first resistor and a second resistor; a first end of the first resistor is connected with the second node; a second end of the second resistor is grounded; and a second end of the first resistor is connected with a first end of the second resistor and a first end of the constant voltage driving subunit.

4. The detection circuit of claim 1, wherein, the constant voltage driving subunit further comprises: a third resistor, a fourth resistor and a first capacitor; an inverting input terminal of the first amplification component is connected with a first terminal of the first capacitor and a first terminal of the fourth resistor, and an output terminal of the first amplification component is connected with a second terminal of the first capacitor and a first terminal of the third resistor; a second terminal of the third resistor is connected with a control terminal of the switch component, and a second terminal of the fourth resistor is connected with a second terminal of the switch component and the second intermediate node.

5. The detection circuit of claim 1, wherein, The first bridge arm further comprises: a third voltage dividing network, a first terminal of the third voltage dividing network is connected with the temperature measuring resistor at the first intermediate node, and a second terminal of the third voltage dividing network is connected with the first node.

6. The detection circuit according to claim 5, wherein the first voltage dividing network comprises a fifth resistor and a sixth resistor, a first terminal of the fifth resistor is connected with a first terminal of the sixth resistor and the first node, and a second terminal of the fifth resistor is connected with a second terminal of the sixth resistor at the second intermediate node; the third voltage dividing network comprises a seventh resistor and an eighth resistor, a first terminal of the seventh resistor and a first terminal of the eighth resistor are connected with the temperature measuring resistor at the first intermediate node, and a second terminal of the seventh resistor and a second terminal of the eighth resistor are connected with the first node.

7. The detection circuit of claim 6, wherein, The detection module comprises: a first calculation unit, a first terminal of the first calculation unit is connected with the second intermediate node, a second terminal of the first calculation unit is grounded, and an output terminal of the first calculation unit is connected with a first detection terminal; a second calculation unit, a first terminal of the second calculation unit is connected with the second intermediate node, a second terminal of the second calculation unit is connected with a first terminal of the temperature measuring resistor, and an output terminal of the second calculation unit is connected with a second detection terminal; wherein the first detection terminal is used for detecting first voltage information of the output terminal of the first calculation unit, and the second detection terminal is used for detecting second voltage information of the output terminal of the second calculation unit; the first calculation unit is used for detecting voltage information of the second intermediate node; the second calculation unit is used for detecting voltage information of the first intermediate node.

8. The detection circuit according to claim 7, wherein the second calculation unit comprises a ninth resistor and a tenth resistor, a first terminal of the ninth resistor is connected with the first terminal of the temperature measuring resistor, a second terminal of the ninth resistor is connected with a first terminal of the tenth resistor, and a second terminal of the tenth resistor is grounded; the ninth resistor and the tenth resistor are used for calculating the current of the temperature measuring resistor; wherein the current of the temperature measuring resistor is calculated by the following formula: （1） Wherein, U1 is the voltage of the second intermediate node, U2 is the voltage of the first intermediate node, R64 is the resistance value of the fifth resistor, R66 is the resistance value of the sixth resistor, R32 is the resistance value of the seventh resistor, R65 is the resistance value of the eighth resistor, R54 is the resistance value of the ninth resistor, R52 is the resistance value of the tenth resistor, I RT is the current of the temperature measuring resistor.

9. The detection circuit according to claim 8, wherein impedance information of the temperature measuring resistor is calculated by the following formula: （2） wherein V out1 is the first voltage information, V out2 is the second voltage information; temperature information of the temperature measuring resistor is calculated by the following formula: （3） wherein R T is a resistance value of the temperature measuring resistor at a current temperature, R0 is a resistance value of the temperature measuring resistor at 0°C, ∂ T is a temperature coefficient of the temperature measuring resistor, and T is temperature information of the temperature measuring resistor.

10. A method of calculating the medium temperature of a thermal gas mass flowmeter, characterized in that The method is performed by the detection circuit of the medium temperature of the thermal gas mass flowmeter according to any one of claims 1-9; the method comprises: reducing the voltage signal of the second intermediate node by the voltage adjusting unit arranged on the second bridge arm of the bridge module; detecting voltage signals of the first intermediate node and the second intermediate node by a detection module, and calculating temperature information of the temperature resistance; measuring flow information of the thermal gas mass by the bridge module according to the temperature information of the temperature resistance; The bridge module is connected with the temperature resistance, and the bridge module includes a first bridge arm and a second bridge arm; the first bridge arm is connected with the temperature resistance at the first intermediate node, and the second end of the temperature resistance is connected with the ground end; the second bridge arm includes a voltage adjusting unit and a first voltage dividing network, and the voltage adjusting unit and the first voltage dividing network are connected at the second intermediate node.

11. A sensing device for a thermal gas mass flowmeter, characterized by comprising: A medium temperature detection circuit of the thermal gas mass flow meter according to any one of claims 1-9.

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